22963536 Manual of Retinal Surgery 2nd Edition 2001

Second Edition I

Manual of•etlna

ur e.

Andrew ] ..Packer

Contents

Contributing AuthorsForeword by Thomas M. Aaberg, Sr.Preface

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1. Anatomy and General ConsiderationsAndrew 1. Packer

2. Preoperative Evaluation of the Retinal Detachment PatientStanley Chang

3. Preoperative Ophthalmic Echography and ElectrophysiologyRoher! E. Leonard If and Dwain G. Fuller

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4. Laser Photocoagulation and Cryopexy of Retinal BreaksDavid W. Parke If

23

5. Pneumatic RetinopexyPaul E. Tornambe

33

6. Anesthesia for Vitreoretinal SurgeryW. Sanderson Grizzard

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7. Scleral Buckling Surgery (Cryopexy and Explants)Andrew 1. Packer

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8. Posterior Segment VitrectornyGary W. Abrams and Jane C. Werner

9. Macular Hole SurgeryLawrence S. Morse, Rahat T. Wendel, and Peter T. Yip

10. Complications and Postoperative ManagementMark S. Blumenkran:

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105

119

Index 131

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Preface

The purpose of this manual is to provide the reader with a straightforward. practicalguide to retinal surgery. It is not designed to provide a complete compendium on thetopic but rather an up-to-date, reasonable approach. This second edition provides cur-rent indications as well as technical updates for the surgical procedures and includesa new chapter on macular hole surgery. Many of the personal preferences presented inthis manual are intended to serve as suggestions for the surgeon who is looking todevelop or modify his approach to retinal detachment surgery. The reader must keepin mind that there are many valid alternative techniques that are not covered. Thesuggested readings at the conclusion of each chapter will enable readers to coverselected areas in greater depth and will also acquaint them with valid alternative tech-niques. It is hoped that residents and beginning vitrecretinal fellows will use thismanual as a starting point to help formulate their approach to retinal detachmentsurgery, and that practicing ophthalmologists will find some useful clinical "pearls"that will assist them in modifying their own individual approach.

I would like to acknowledge and thank Laurel C. Lhowe and Jerry Sewell, whocreated the wonderful illustrations for this edition.

Andrew 1. Packer, MD.

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1Anatomy and General Considerations

Andrew J. Packer

Rhegrnatogenous retinal detachments are caused byretinal breaks, which in most cases result from vit-reorerinal traction. Fluid accumulates between thesensory retina and the retinal pigment epithelium(RPE). Closing (or sealing) the retinal break is syn-onymous with repairing (or preventing) a rheg-m.uogenous retinal detachment, assuming that thev itre oret inu! traction has been relieved. Under-standing the anatomic and physiologic principles ofthe posterior segment is essential to formulatingappropriate treatment for retinal breaks and retinaldetachments.

Retinal Anatomy

The retina is a thin, transparent tissue that lines theposterior two-thirds of the globe. The retina variesin thickness from 0.13 mm (in the center of thefovea) to 0.55 mm (at the margin of the anatomicfovea). It extends from the optic nerve posteriorlytothe ora serrate anteriorly (which approximatesthe line of recti muscle insertion). Photoreceptors(rods and cones) are connected to neuronal path-ways terminating in nonmyelinated fibers thatform the optic nerve. The inner two-thirds of theretina are nourished by the retinal circulation; theouter one-third of the retina is nourished by thechoroidal circulation, a high flow circulationthat also serves as the cooling system for the eye(Figure 1- I).

The vortex veins, which are readily visiblethrough the retina, are important landmarksbecause they exit through the sclera, approxi-mately 3 mm posterior to the equator. There areusually four to six vortex veins, and they are fre-quently found near the 1,5,7, and II o'clockmeridians (Figure 1-2). Ciliary nerves also serveas landmarks.

The anatomic macula is defined as the posteriorportion of the retina containing two or more lay-ers of ganglion cells. It measures from 5.5-7.5 mmin diameter and is centered approximately 4 mrntemporal to and 0.8 mm inferior to the center ofthe optic disc. Clinically, this region is oftenreferred to as the posterior pole,

The anatomic fovea is a depression in the innerretinal surface in the center of the macula measur-ing 1.5 mm in diameter. The anatomic fovea iscommonly referred to clinically as the macula. Onthe external surface of the globe, it is centered Imm medial to and I mm above the posterior borderof the inferior oblique insertion.

The RPE, a single layer of pigmented epithe-lium, is located external to the sensory retina, andthe choroid is located external to the RPE. Thechoriocapillaris (the capillary bed of the choroid) islocated adjacent to the RPE, allowing access to theouter retina, which it nourishes (Figure 1-1). Theretina, the RPE, and the choroid are mechanicallysupported by the sclera, which varies in thicknessfrom 0.3 mm (just posterior to the insertions of the

2 MANUAL OF RETINAL SURGERY

...•"".......----234

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5

7

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9

101112

13

1. Inner Limiting Membrane2. Nerve Fiber Layer3. Ganglion Layer4. Inner Plexiform Layer5. Inner Nuclear Layer6. Outer Plexiform Layer7. Outer Nuclear Layer

8. External Limiting Membrane9. Photoreceptor Inner and Outer Segments

1O. Pigment Epithelium11 .. Bruch's Membrane12. Choriocapillaris13. Choroid

Figure I-I. Retinal anatomy. (Modified with permission from Bargmann W. Histologic lind Mikroscopische Anatomic des-Mcnschcn. 6th ed. Georg Thieme, Stuttgart; 1967.)

Anatomy and General Considerations 3

Anatomical vertical meridIan

Figure 1.2. Rctinallanumarks. (Reprinted with perrnission from Rutnin U. Schepens CL. Fundus appearance in normal

eyes. Alii ) Opluhulmol 1967;64:824.)

recti muscles) to greater than 1.0 mm (near the pos-terior pole). Abnormally thin. blue-appearing areasof sclera called stophylomato con be found in eyeswith retinal detachments. Narrow. radially orientedscleral dehiscenccs are also seen.

The Vitreous

The vitreous occupies a volume of approximately 4cc tn an emmetropic eye. It is firmly attached in a 2-to 4-mm-wide band at the om serrata (the vitreousbase) and is less tightly bound posteriorly (at theoptic nerve. the macula. and along retinal bloodvessels). It can also form abnormal focal adhesions,especially around areas of lattice degeneration andregions of chorioretinal scarring. The vitreous is acomplex gel composed of collagen fibrils andhyaluronic acid. As a result of degenerative changes(as well as trauma, hemorrhage, and inflammatorychanges), the vitreous may separate from the neu-

rosensory retina starting posteriorly: this is called aposterior vitreous separation (PVS) or posterior vit-reous detachment (PVD). In the normal eye. thedegeneration involves formation of large liquid cav-ities within the vitreous body. Contents of the liq-uefied cavities extrude posteriorly through defectsin the posterior hyaloid, which then separates andcollapses anteriorly.

In most cases, a PVD should be considered anormal process of an aging eye; present clinicallyin up to 65% of patients over 65 years of age. Asthe vitreous separates posteriorly, it remains firmlyattached to the retina at the vitreous base. Thisplaces anteroposterior traction on any focal areas ofvitreoretinal adhesion, which can lead to a retinalbreak as the vitreous is pulled anteriorly (Figure1-3). Retinal breaks that are specifically caused byvitreous traction ore referred to as retinal (ears (abocalled "flap" tears or "horseshoe" tears because ofthe U'-shnped defect that typically occurs). Ongoingtraction on the anterior edge of a horseshoe lear will


Figure 1-3. r","I,'rior vitreous separation with focal vitreo-retinal ~lllhc-",iull causing. a retinal lear.

tend to open the tear and encourage accumulationof subretinal fluid. If a section of retina is com-pletely torn from the retinal surface, an operculatedtear results. The round operculum can usually beseen hovering over the retinal defect. Since opercu-luted tears an: not affected by ongoing vitreorctinaltraction. they are in general less likely 10 allowaccumulation of subrelinal fluid once opposed 10

the RPE. Retinal breaks located within the vitreousbase are also not subject to ongoing tractionalforces and are. therefore. less likely 10 go on to reti-nal detachment.

Several forces tend to promote attachment of thesensory retina to the underlying RPE; these includethe RPE pump (creating negative pressure in thesubretinal space), intercellular mucopolysaccharide"glue" between the RPE and the sensory retina, andpossibly interdigitation of the RPE cell processesand the rods and cones of the sensory retina.

Factors that tend to promote retinal detachment,other than vitreoretinal traction, include the size ofthe retinal break and the dynamics of fluid currentswithin the vitreous cavity.

Suggested Reading

Hilton GF, Mcl.ean JB. Brinton DA. Retutul Dcruch"'ent:Principles and Practice. 2nd ed. San Francisco: Amer-ican Academy of Ophthalmology: 1995.

Jones LT, Reeh MJ, Wirtscnafter JD. Ophthalmic anatomy.In: American Academy of Oplzl/lOlmulogy Manual. SanFrancisco: American Academy of Ophthalmology;1970: 139-151.

Lowenstein A, Green WR. Retinal histology. In: Guyer DR.Yannuzzi LA. Chang S. Shields JA. Green WR. eds.Rctina-Vitrcous.Munda. Vol. 1. Philadelphia: Saunders:1999:3-20.

Macherncr R. The importance of fluid absorption. traction,intraocular currents and chorinrclinal scurs in the ther-apy of rhegmalOgenous retinal detachments. Am J OJ'''·thalmol 1984:98:681.

Ry"n SJ. ed. Retina. Vol. 1, 2nd ed. SI. Louis, MO: Mosby:1994:5-123.

Schepens CL. Retinal Dctochment and Allied Diseases. Vol.1. Philadelphia: Saunders: 1983:23-87.

2Preoperative Evaluationof the Retinal Detachment Patient

Stanley Chang

Thorough preoperative evaluation of the patient withretinal detachment is as important as the surgicalprocedure itself. After examination of the patient iscompleted. the surgical strategy can be planned pre-operatively. Specific aspects of the managementstrategy to be considered are a segmental or radialbuckle versus an encircling scleral buckle, the ncccx-sity for drainage of subretinal fluid. the possibleneed for air or gas tamponade. or the: need for vit-rectomy to mobilize fixed or star folds resultingfrom epiretinal proliferation. More recently, alterna-tive techniques for the management of retinaldetachment without permanent scleral buckling.such as a temporary parabulbar balloon or pneu-matic retinopexy. may also be: appropriate inselected cases. Careful study of the vitreoretinalrelationships is vital to a successful result. The pre-operative evaluation should include 0 detailed clini-cal history, comprehensive ophthalmic evaluation ofboth anterior and posterior segments of the eye, andinformed consent from the patient following detailedexplanation of the planned surgical procedure.

Clinical History

The duration of symptoms resulting from vitreousopacities should be determined as accurately as pos-sible. Often patients report symptoms such as spots,lines. cobwebs, or floaters. Sometimes they willobserve a mobile "veil" or "film." A history of pho-topsia may also be reported. Many patients are not

aware of- the signi ficance of floaters or photopsiaand do not seek attention unti I a peripheral fielddefect or central visual loss occurs secondary tomacular detachment. Prec ise description of thesymptoms may aid in localizing the retinal breaks.[I' the patient has had retinal detachment previously.the details and results of prior surgery should beobtained if posxiblc. A previous history of oculardisease relevant to retinal detachment such asmyopia, glaucoma, ocular influrnrnation, trauma. orcataract surgery should be documented. A familyhistory of retinal detachment should also be noted.

There is wide variation in the ability of patientsto recall their symptoms. Some patients are able torelate a very derailed history of the direction of fieldloss and associated symptoms, while others areunable to describe their symptoms precisely.Patients who have had a retinal detachment previ-ously are often more alert to symptoms that mayoccur in the fellow eye.

Ocular Examination

The ocular examination should include a completegeneral eye examination as well as a detailed fun-dus study. The refractive error should be recorded.In eyes with a history of amblyopia, an autorefrac-tor or retinoscopic evaluation may determine thetrue refractive status. The corrected visual acuityshould be recorded for each eye. A confrontati.onvisual field may determine the extent of the retinal

5

-6 MANUAL OF RETINAL SURGERY

detachment prior to funduscopic examination. Anafferent pupillary defect is usually present in theaffected eye. Applanation tonometry may be usedto record the intraocular pressure. In most cases theintraocular pressure is lower as a result of the reti-nal detachment, but the presence of hypotonyshould raise the possibility of accompanyingchoroidal detachment. In patients with a history ofglaucoma, the usc of cycloplegic agents for preop-erative pupillary dilation may cause a rise inintraocular pressure.

The lids and conjunctiva should be examined forblepharitis or conjunctivitis prior to pupillary dila-tion. Phenylephrine hydrochloride may constrictconjuncti val blood vessels and mask an ocularinfection. The presence of severe blepharitis or con-junctivitis should lead to a delay in surgery until thecondition has been treated.

Limitations in ocular motility or strabismusshould be measured and noted. If the patient hashad previous retinal surgery and abnormalities inocular motility are noted, the patient should beinformed of the increased possibility of diplopiaafter the retina is reattached.

On slit-Iump examination. ahnormalities incorneal clarity or size should he noted. The depthof the anterior chamber should be checked. Inpatients with a narrow peripheral angle. gonioscopyis indicated to avoid angle closure by pupillary dila-tion. Such eyes may require laser iridectomy priorto pupillary dilation and retinal detachment surgery.Any patients with a history of glaucoma or pupil-lary rubeosis should also undergo gonioscopy.

In patients with Marfan's syndrome or a history ofocular trauma. lens subluxation or phacodonesis mayalso be present. If an intraocular lens implant has beeninserted, the type of implant and integrity of the pos-terior capsule following extracapsular cataract extrac-tion should be noted. In aphakic patients, vitreousfibrils may be displaced anteriorly through the pupilby ;1 bullous retinal detachment. Vitreous strands totbe cataract wound should be studied. The hyaloidface may be in contact with the corneal endothelium,resulting in localized corneal edema.

In phakic patients with symptoms of posteriorvitreous separation, it is helpful to examine the.anterior vitreous with the slit lamp. The presence ofpigment (frequently present only after vertical andhorizontal eye movements) almost invariably indi-cates the presence of a retinal tear.

After the slit-lamp examination is completed,maximum pupillary dilation should be obtainedprior to funduscopic cxamination. Cyclopentolatchydrochloride I% and phenylephrine hydrochloride2.5% (or 10% in refractory cases) can be used incombination at 20--30 minute intervals until maxi-mum dilation occurs. In patients with iris-fixatedintraocular lenses, dilation should be done morecautiously to prevent dislocation of the implant.

Examination of the Fundus

The funduscopic exurninat ion consists of threeparts: (1) indirect ophthalmoscopy with scleraldepression. (2) noncontact biomicroscopy of vitreo-retinal relationships using an aspheric lens, and (3)contact lens examination of the retina and anteriorchamber angle. The following instruments shouldbe available:

• Indirect ophthalmoscope with small pupilanachment

• Scleral depressor• Fundus drawing paper• Colored pencils• Lenses for indirect ophthalmoscopy: 14-.20-,

25-. 28-, or 30-diopter• 90-. 78-, or 66-diopter aspheric noncontact

lenses• Three-mirror contact lens• Macular lens• Panfun.duscopic lens

An indirect ophthalmoscope should be chosenthat is lightweight and fits comfortably. since theexamination in some difficult cases may take up to60 minutes. A small pupil attachment is helpful forpoorly dilated eyes or in pseudophakic eyes withperipheral lens remnants. The room is darkened andindirect ophthalmoscopy is started when the exam-iner is dark adapted. The patient is placed supine onan examining chair or table. The chin is extendedforward slightly. The examiner stands at the head ofthe patient and the fundus drawing paper is keptnext to the head of the patient on the side of theexaminer's writing hand or on the patient's chest.The 120 'dock meridian of the drawing is directedtoward the patient's feet and the examiner is posi-tioned opposite to the meridian of interest andsketches exactly what is observed. By placing the

drawing upside-down. one obviates the need totranspose the inverted image of the indirect oph-thalmoscope. The beginning examiner should learnto hold the lens with the nondorninunt hand so thatthe writing hand can be: used for drawing or scleraldepression. The conventional color scheme used forfundus drawing is:

Light blue: retinal detachmentDark blue: retinal veins, margins of retinalbreaksLight red: attuched retinaDark red: retinal arteries, preretinal orintraretinal hemorrhages

• Green: vitreous or lens opacitiesBlack: chorioretinal pigmentationYellow: inrrare rinal or subretinal e xudute s.subretinal bandsBrown: choroidal detachment. nevi. ormelanomas

At the beginning of the ex arnination. the inten-sity of the indirect ophthalmoscope is reduced roallow the patient to adjust to the brightness or' thelight. Initially. a broad survey of the funduscopicfindings is obtained without sc lcrul depression.When the patient is more comfortable with theexamining light. the illuminarion can be increased.The meridians delimiting the edges of the retinaldetachment are first nored and the extent ofdetachment is sketched onto the fundus drawing.The fundus drawing paper (Figure 2-1) containsthree concentric circles. The inner circle representsthe equator of the fundus, the middle circle repre-sents the ora serrata. and the outer band the parsplana.

Retinal breaks vixible without scleral depressionare localized and drawn. Following the retinalblood vessels out to the periphery allows system-atic examination of the entire fundus. Scleraldepression is required for examination of theperipheral retina. The patient is more comfortablewhen scleral depression is started temporally. Thetemporal periphery is more easily visualized and, asthe eye softens from scleral depression. the nasalfundus can be more easily examined. Optimal visu-alization of the peripheral fundus is usuallyobtained when the examiner stands directly oppo-site to the meridian of interest. In patients withsmall pupils or peripheral lens opacities, visualiza-tion of retinal breaks may also be improved by turn-

Preoperative Evaluation of the Retinal Detachment Patient 7

ing the patient's head toward the examiner and ask-ing the patient to look toward that meridian.

Specific features of the reti nul detachmentshould be noted on the fundus drawing:

I. The rc lur ioush ips of rctinal blood vessels andvortex veins to the location of breaks should bedrawn to provide landmarks for intraoperativelocalization. These may be helpful duringsurgery if visualization decreases due to cornealedema or vitreous hemorrhage. Avulsed or bridg-ing blood vessels over retinal tears should alsobe noted.

2. The height or elevation of the retinal detachmentshould be studied to determine whether drainageof subretinal fluid is required. More bullousarcus are preferable for possible drainage sites.

3. Areas of chorcoretinal pigmentation and demar-cation lines should be indicated. Demarcationlines may help to localize the region of the reti-nal breaks.

4. Areas of per iphc rul lattice degeneration andareas suspicious for retinal breaks should benoted. Some Dr' these areas will require exami-nation under higher magniticatinll using the con-tact lens.

S. When multiple breaks arc present. their antero-posterior locution should be accurately depicted.As a general rule. vortex veins delineated theequator and can be helpful in the precise deter-mination of anteroposterior location. This infor-mation will be used to plan the size and extentof scleral buckling.

6. Lines of circumferential traction in the anteriorretina and star or fixed tolds should be indicated.By observing the mobility of the retina as thepatient moves the eye, the severity of tractioncan be evaluated. Poor mobility indicates thatthe retina is stiffened by epirctinal membranesand may require vitrcctorny.

The posterior pole is usually reserved for thefinal part of the examination with indirect ophthal-moscopy. A 14-diopter condensing lens provideshigher magnification for small breaks. Macularholes. cysts, or macular pucker may be present.Posterior breaks may also be present ncar the edgeof a staphyloma or coloboma or adjacent to largerretinal blood vessels.

When the examination is completed in thesupine position. the patient is examined in the


...

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Figure 2-1. Fundus drawing document.

XII

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siHing position. Tnis may allow folds within theretinal detachment to open. revealing previouslyunseen retinal breaks. The presence of shi ftingfluid is usually associated with exudative retinalderachrnents but Cl.J1also be seen in patients withrnegrnaroge nous retinal detachments with smallretinal breaks.

The patient is returned to the slit lamp andundergoes biomicroscopy using the 90-. 78-. or 66-diopter aspheric lens and three-mirror contact lens.T:"1eadvantages of the espheric lenses for fundu-scopic evaluation are that they allow a biomicro-scopic examination without placement of a lens onthe eye. ::InO its depth of focus permits exce llentvisuaiization of vitreoretinal relationships .. Areas ofaahesion of the posterior hyaloid [Q me retina can.~ ,~:;. Posterior fundus evaluation is particularlv~~~~:i\-e because of the ability to increase rnagnifi-cat.on, The beginning examiner quickly adapts to~~~ir:\'e~~d image and learns that me image movesc;;-;:-o~i:e:0 the direction of gaze.

Tr;e ~;'ree-mir.or contact lens examination is an:~::orc2r.t par; of fundus evaluation because it allows:':.;;_':er::;:Jgni:"icllion and refinement of the findings~e:1 In .ndirec: ophthalmoscopy .. At higher rnagni-::c~~;Gn. small breaks and vitreoretinal relarionshicsz:': 7.ore e~ii:- appreciated. Topical proparacaineI).': .-;,b instilled into the conjunctival fornix and.-:-.::~-.:,.ce iluiose sciuticns I 1 ':c to 2.50"c) are used 0;1

:.:~e:2r.[2:: ~er:s.The patient's head is placed into the31;[-1;:'~~.nicroscoce :J.I1dthe patient is instructed :01'-,:1-:~:: '.-;-.i:;::::-:e .ower lid is retracted me the lees;:, . .:.:::=-= :.'r.tO :r.~~:.c.. -\.:=te:-examination of the ~-Qst~·r cr ~r:d;lS :rl~oughine central lens. each of (he three:":".::-:-:r5:;; us;::,j :0 examine the fundus. The largestrr.irrcr .iilows 3[1.:0:; of the post-equatorial fundus.T~~~!c:lc-3~z~~ mirror is used to study the pre-e=.·=J.::~J.! r;:::;::J.I periphery .. Asking the patient [0

.cc-; .cv ard ±e meridian of the mirror allows more::,:,:er:c~ visu izaucn. while looking in the rneric-.ar: :::05i,e to the mirror provides a more peripheral.:e·.'. I: IS::e:p'ei :0 move the light of the slit lamp to:..'::;:: 52.;-:-'.;:: side J.S L':e mirror when examining inferior,:;~::,Cr::..--:L' of the fundus. and to direct the light from::-:e ocrcsire direction when studying the superior:=::.;3.1 2L::1tir.J1LS. \!:J.cu!:lr lenses (contact lenses sirn-ii;:r .o C.~,ecentral portion of the 3-mirror contact iens I

:::e onl: :Jsdul for examining the posterior pole.T:~e ';' ide field of visualization of the panfun-

cuscocic lenses C::In be useful in surveying the mid-

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Preoperative Evaluation of me Retinal Detachment Parient 9

peripheral fundus to the equatorial region. particu-larly in eyes with small pupils.

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Lesions Simulating Retinal Breaks

Some peripheral retinal abnormalities may mirrucretinal breaks. Small retinal hemorrhages in theregion of the vitreous base may be rnistuken forretinal tears because of their reddish appearance.Contact lens examination will differentiate thesefrom true retinal bremo Outer or inner layer retinalbreaks within areas of retinoschisis may be difficultto dirferentiare from retina! breaks in chronic retinal detachment. Retinal tufts. or tag s. may alsoresemble retinal breaks arid should be examinedcarerullv ·.,·iL1scleral depression. \leridional com-plexes should be examined with scleral depressionfor smail breaks at their posterior margin.

Some pe~Jher:Jl fundus changes rnay alsoresemble retinal detachment. Are:JS of white with-out pressure indicate vitreoretinal adhesion. Ifextensive. L'1ewhitish change may be mistaken forretinal de.achrnenr. These changes are more recdiiyapparent in yOU:lg patient» with daddy pigmenteJfundi. Retirial cysts are round intrarerinal coikc·tions of ::uic :'::.H may be prese:lt on [he inner orouter sue'3C:: of the retina. Retinal cysts are rre-queruiv 3..S50C:2~-=~ with chronic retinal detachrner.tand ,:Ls:lp;:c~ ~l:'iIo\l;ing surg ica! reauachrnent.

.-\.:~ui:-~d or congeniral retino-chi. ...is Hl:lY be J~(-

ficuir :0 c: F=:-e:-.:~~~~from atrophic rc.inc preser.t inchronic retinc] ':=r:lChmc:tL .-\ ;JigmC:lt dernarcaticr-

line is inc~c:l::" C'or retinal cetachrne:u. but the di~~-nos is may be d.rficult when none is pr:':5e~,[.Acquired re.inoschisis is U5U:1l!~. ;CC::HcC i:1 :~l::inferoternporal quadrant ::InC :1::J.Yalso be pres;:::lt .nthe sL:?e~ot;:::-:lccr::.1quadrant: it is bilateral in S5'-Cof cases. It cfte~, appears as a thin. con . ex. trcnv-parent surface :Jr.Q occasionally is seen with srnul Iwhitish C~JI1;:':s. Retinul breaks in either inner orouter 1:J:~rs ··\iii not result in retinal detachment.but '.vhen holes are present in both layers sirnult:i-neously. detachment is likely to be present.

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ItLincoff 's Rules of Retinal Detachment

When 'he funduscopic examination hJ.S been com-plered and the location of retinal breaks found. [he

11

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examiner should consider whether the configurationof the detachment is consistent with the' location ofthe retinal breaks. Retinal detachments accumulatesubretinal fluid in a predictable manner around theretinal break of origin. These observations havebeen extensively described and are known as Lin-coff's Rules. The shape of the retinal detachmentindicates the location of the break in 96% of cases.

Some concepts that may be useful in finding thebreak are that (1) in superonasal or temporal retinaldetachments, the retinal break lies within one andone-half clock hours of the highest border 98% ofthe time; (2) in superior detachments that cross themidline, the primary retinal break is at 12 o'clockor within a triangle the apex of which is at the oraserrata and that intersects the equator I hour toeither side of 12 o'clock, this is present 93% of thetime; (3) in inferior detachments, the higher sideindicates to which side of the 60 'clock meridian aninferior hole lies 95% of the time; (4) when an infe-rior retinal detachment has a bullous configuration,the primary hole lies above the horizontal meridian.

These rules are most applicable in the absenceof proliferative vitreoretinopathy since significanttractional forces can alter the distribution of sub-retinal fluid. If the location of the retinal breaksdoes not explain the retinal detachment, additionalstudy of the retinal detachment is suggested to seckany possible missed retinal breaks.

Preoperative Informed Consent

The patient with retinal detachment is often quiteapprehensive, for several reasons. The acute dis-covery of a retinal detachment has brought the reti-nal surgeon and the patient together. Usually thepatient has not met the retinal surgeon until referredfor evaluation of retinal detachment. Often patientshave a poor understanding of the pathophysiologicprocesses involved in retinal detachment and the

surgical procedure required for treatment. There-fore, an explanation should be provided to thepatient of the events leading to the retinal detach-ment and the planned treatment. The overall toneshould be supportive and positive since the progno-sis for retinal reattachment is good. The patientshould be informed of possible intraoperative aswell as postoperative complications. These includecomplications from drainage of subretinal fluid,retinal perforation during placement of scleralsutures, choroidal detachment, macular pucker, pro-liferative vitreoretinopathy, or diplopia. If the mac-ula is detached preoperatively, the prognosis forreturn of central vision should be indicated to thepatient. Patients may not realize that it may take upto 6 months before central vision returns. Finally,the patient should be given ample opportunity toask any questions related to the planned surgery.

Suggested Reading

Beyer NE. The Peripheral Retina in Profile: A StereoscopicAtlas, Torrance. CA: Criterion Press; 1'.182.

Beyer NE. Peripheral retinal lesions related to rhcgmatllge-nous retinal detachment. In: Guyer DR. Yannuzzi LA.Chang S. Shields JA. Green WR. cds, Re/illa·I/i/reousMacula. Vol. 2. Philadelphia: Saunders; 1999:1219-1247.

Brod RD. Lightman DA. Packer AJ. Saras HP. Correlationbel ween vitreous pigment granules and retinal breaksin eyes with acute posterior vitreous detachment. Oph-thulmology 1991 ;98: 1366-1369.

Hilton GF. McLean EB, Brinton DA. Retinal Detactnncnt:Principles and Practice, 2nd ed. San Francisco: Amer-ican Academy of Ophthalmology: 1995:41-81.

Lincoff H. Gieser R. Finding the retinal hole. Arch Opluhal-mo/1971;85:565.

Regillo CD, Benson WE. Retinol Derachmcnt : Diag-nosis and Management. 3rd ed. Philadelphia: Lippin-colt-Raven; 1998:45-99.

Schepens CLS. Retinal Detachment and Allied Diseases.Philadelphia: Saunders; 1983:99-232.

'('

3Preoperative OphthalmicEchography and Electrophysiology

Robert E. Leonard II and Dwain G. Fuller

Ophthalmic echography and electrophysiologic stud-ies can provide valuable aid to today's vitreoretinalsurgeon in the evaluation of eyes with opaque media.Obviously, in eyes with a rhegrnatogenous retinaldetachment and clear media. no ancillary testing isneeded for diagnosis and treatment. In contrast. an eyewith a dense cataract. cyclitic membrane, hyphcrna,vitreous hemorrhage. or other significant opacity ofthe media may harbor posterior segment pathologysuch as a tumor or detachment that can readily bediagnosed with preoperative echography. Ophthalmicechography has emerged as a diagnostic modality thatis extremely useful in the assessment of eyes withanterior or posterior segment media opacity. Electro-physiology may also be of use in the functional assess-ment of eyes with cloudy media to determine if therei.~a reasonable prospect of salvaging vision.

Echography

The! development of clinical ophthalmic echogra-phy in the 1970s greatly modified and improved themanagement of retinal detachments and other pos-terior segment pathology in eyes with opaquemedia. The concurrent introduction of pars planavitrectomy by Robert Macherner gave the retinalsurgeon the necessary tools to approach such eyes~Iggressively and, in many cases, to effect dramaticvisual restoration. Prior to the advent of pars planavitrcctomy, the management of retinal detachmentin the presence of vitreous hemorrhage typically

included bed rest. elevation of the head. and bilat-eral eye patching. If the blood cleared in a timelyfashion, retinal tears could be localized and scleralbuckling performed. Eyes in which the vitreoushemorrhage did not clear or did not clear ade-quately to allow for visualization of the retinalbreaks might be subjected to a so-called "blind"buckling procedure. Certainly. the advent of vitrcc-torny and subsequent advances in v itreoret inalsurgery have allowed for earlier and more preciseintervention in these cases. In an eye with mediaopacities that preclude visualization of the fundus.echography can quickly answer a number of ques-tions of interest to the vitreoretinal surgeon andfacilitate appropriate management.

I. Is the posterior segment anatomically normal')2. Is the retina detached? Is there evidence of pro-

liferative vitreoretinopathy (PVR)? Is there evi-dence of tractional retinal detachment?

3. Are there ultrasonographic findings that suggesta secondary retinal detachment (tumor, inflam-matory condition)?

4. Are choroidal detachments (serous or hemor-rhagic) present?

5. Are signs of trauma evident, such as subretinalhemorrhage, posterior rupture, intraocular for-eign body. or lens luxation or disruption?

6. Is there an occult posterior tumor present, and ifso, what are its characteristics?

Contact Bvscan echography is the method ofchoice for the vitreoretinal surgeon evaluating eyes

II


with cloudy media. Real-time dynamic Bvscunechography can yield valuable information regard-ing the nature of a retinal detachment, allowing forthe differentiation of a mobile, more acute detach-ment from a fixed. chronic one. Currently, three-dimensional ultrasound imaging is being evaluatedfor clinical application. Possible uses of three-dimensional ultrasound include volumetric analysisof tumors and more accurate assessment of com-plex retinal (Jetachlllents.

A-scan techniques. particularly standardized A-scan echography as popularized by Karl Ossoinig,are invaluable for determining the size and charac-teristics of intraocular tumors. Such procedures canaccurately assess the apical height of a tumor andoften provide useful tissue characterization. Forexample. a homogenous tumor mass such as a pos-terior uveal melanoma would display low internalreflectivity on A-scan. whereas a vascular tumorsuch as a choroidal hemangioma would typicallyshow a high internal reflectivity pattern due to itsheterogeneous tissue structure.

Normal Posterior Segment

If the posterior segment is anatomically normal. thevitreous cavity ",..ill be acoustically clear or have

minimal signal intensity. The retina will be attachedand the choroid will not be thickened. A posteriorvitreous detachment mayor may not be present.Contact B-scan eehography can rapidly and easilyidentify eyes with normal posterior segments.

Rhegmatogenous Retinal Detachment

Total retinal detachment is usually a straightfor-ward diagnosis with echography. Highly reflectiveretinal leaves emanate from the optic nerve headand rejoin the globe wall anteriorly at the ora ser-rata. Bullous detachments are widely separatedfrom the eye wall and have a convex configuration.In contrast, a shallow retinal detachment mayremain close to the eye wall and be difficult to dis-tinguish from other entities. A partial retinaldetachment is not hard to identify if the detachmentextends back to the optic nerve head. A localizeddetachment in the periphery, however. may some-times be difficult to differentiate from a vitreousmembrane. Detached retina is normally morereflective or echogenic <brighter on B-scan) thanare vitreous membranes. Figure 3-1 shows an eyewith vitreous hemorrhage and a localized retinaldetachment. In this particular echogram, one canalso visualize the retinal break (arrow). There is

Figure 3-1. Localized rhegmalogenous retinal detachment. Arrow demonstrates retinal break. Acoustically reflectivematerial in the vitreous cavity represents vitreous hemorrhage.

acoustically reflective material in the vitreous cav-ity that represents the vitreous hemorrhage. Thewell-differentiated membrane extending into thevitreous typifies a partial retinal detachment. Thesubretinal space is acoustically clear, and the tinydefect seen in the retina represents the retinalbreak. At surgery, a vitrectorny was performed thatallowed correlation of the ultrasonographic find-ings with the presence of a retinal tear, a bridgingretinal vessel, and !1 localized retinal detachment.Figure 3-2 demonstrates a retinal tear without reti-nal detachment. The area of vitreoretinal tractionis clearly seen.

Dynamic or kinetic examination allows theexaminer to determine the mobility of a detachedretina. The Bvscan ultrasound probe is placed on thepatient's closed eyelids, allowing visualization ofthe detached retina. By having the patient look invarious directions. characterization of the retinaldetachment is possible. A nonorganized retinaldetachment shows obvious. but limited after-move-ment at the completion of an eye duct ion. Vitreousmembranes typically are more mobile thandetached retina. In cases of significant PVR, there islink or no retinal after-movement since the retinahas extensive epiretinul membrane formation andfixed folds. With advanced PVR, several differentconfigurations may be seen. Anterior loop tractionmay be identified as retina is pulled up into periph-

Preoperarive Ophthalmic Echogruphy and Electrophysiology 13

eral folds with foreshortening of the posteriorretina. A so-culled open-funnel retinal detachmentmay also be seen. Figure 3-3 illustrates this type ofdetachment. The two retinal leaves that emanatefrom the optic nerve head are foreshortened andproceed to the posterior surface of the lens, indicat-ing anterior PVR. In the most severe form of PVR.the funnel closes. with fusion of the retinal leaves,resulting in a closed-funnel retinal detachment. asshown in Figure 3-4.

The subretinal space is acoustically clear in mostcases of retinal detachment: however. subretinalhemorrhage may be present in traumatic retinaldetachments. nonrheg matogenous detachmentsfrom disciform macular degeneration, or occasion-ally in retinal detachment from proliferative dia-betic retinopathy. Figure 3-5 illustrates theappearance of subretinal hemorrhage. in this casefrom a disciform process. Figure 3-6 demonstratesa diabetic tractional retinal detachment withechogenic subretinal fluid and a subhyaloid hemor-rhage. Subretinal particles can also be seen in somechronic retinal detachments in which mobile sub-retinal cholesterol crystals can develop. These par-ticles are highly echogenic and strikingly mobilewhen examined using kinetic echography and pro-vide an almost pathognomonic picture.

An organized posterior vitreous detachment(PVD), such as might be seen in an eye with

Figure J·2. Retinal break without retinal detachment,

7


Figure 3-3. Open-funnel retinal detachment.

Figure 3-4. Closed-funnel retinal derachrncnt. ( ,~,

previous vitreous cavity hemorrhage, can mimicultrasonographically a total retinal detachment if

- the posterior vitreous face remains adherent to theoptic nerve head. A PVD is usually more mobilethan a total retinal detachment and often has a dis-continuous border and irregular thickness on B-scan echography, but sometimes this distinction is

difficult. Figure 3-7 illustrates a PYD in an eyewith vitreous hemorrhage that could easily beconfused with a retinal detachment. Occasionally,one can also see a stalk that attaches to the opticnerve and extends into the vitreous cavity beforebifurcating into the apparent leaves of the mem-brane. This particular finding is characteristic of

Preoperative Ophthalmic Echogruphy and Electrophysiology 15

Figure )-5. Disciform scar with subretinul hemorrhage. Subrerinal blood is identified (arrow).

Figure 3-6. Diabetic traction retinal detachment.

PVD with a proliferative stalk at the optic nervehead, as might be seen with proliferative diabeticretinopathy. To help differentiate a PVD mirnick-ing a retinal detachment from a true retinaldct.rctuncnt. bright flash electroretinography(ERG) may be performed (see the following sec-tion on electrophysiology).

Nonrhegmatogenous Retinal Detachment

It is important to remember that a retinal detach-ment in an eye with opaque media is not alwaysrhegmatogenous and may be a secondary detach-ment. Such eyes are not candidates for vitreoreti-nal surgery to repair the retinal detachment, and


Figure 3-7. Posterior vitreous separation.

indeed. surgery on eyes containing malignantintruocu lar tumors such as melanoma may por-tend a poor systemic prognosis for the patient. Acareful ultrusonographic search of the subretinalspace is essential to rule out the presence of amass lesion such as a posterior uveal melanoma,choroidal metastatic tumor, or choroidal heman-

giorna. Posterior uveal melanomas may producea 'vitreous hemorrhage and secondary retinaldetachment thaI may mimic a retinal dctachmentunless careful echographic examination is pcr-formed. Figure 3-8 demonstrates a posterior uvculmelanoma associated with a secondary retinaldetachment.

{',..

Figure 3·8. Posterior uveal melanoma. Note secondary retinal detachment (arrow).

Serous ret inul detachments present in an eyewith opaque media can often be confused with arhegmatogenous retinal detachment. Shi Iringdependent tluid during positioning in a kineticechographic exam can be useful in differentiatingthese two entities. Additionally, increased reflectiv-ity in the subretinal fluid, a smooth convex appear-ance, choroidal thickening or associated choroidaldetachment, and absence of a break can be helpfulfactors in distinguishing a serous retinal detachmentfrom a rhegrnutogerious detachment.

Choroidal Detachment

A choroidal detachment is seen echographically as amembranous structure that can be confused with aretinal detachment by the uninitiated. It is impor-tant to make this distinction, since choroidal detach-ment is frequently managed medically while retinaldetachment often requires surgical intervention. Asa general rule. a choroidal detachment is overtlyconvex, does not originate as far posteriorly as theoptic nerve. and inserts anteriorly in front of the orascrrata. l.arge choroidal detachments can meet inthe rnidvitreous cavity and give an ultrasonographicpicture of "kissing" choroidals.

Choroidal detachments can be serous or hemor-rhagic. Serous choroidal detachments have an

Preoperative Ophthalmic Echogrophy and Electrophysiology 17

acoustically clear suprachoroidal space. Figure 3-9illustrates a serous "kissing" choroidal detachment.Note the position of the optic nerve in relationshipto the choroidal detachment. Figure 3-10 demon-strates a "kissing" hemorrhagic choroidal detach-ment, which. in contrast to a serous choroidaldetachment, has prominent echoes returning fromthe suprachoroidal space.

Ultrasonography can be useful in timing thedrainage of suprachoroidal hemorrhage if it isrequired. Kinetic examination may show mobility ofliquefied suprachoroidal blood in hemorrhagicchoroidal detachments that are amenable to drainage.The absence of liquefied blood often indicates that aclot may be present. which makes drainage of thehemorrhagic choroidal detachment difficult.

Trauma

Echography is of extreme value in the setting oftrauma. allowing for more accurate assessment ofinternal ocular anatomy than either conventionalplain orbital radiographs or computed tomography(CT) scans. By performing a gentle exam throughclosed lidx, many open globe injuries may be saf<:lyevaluated. Information on the status of the crys-talline lens, possible intraocular foreign bodies. reti-nal detachment. suprachoroidal hemorrhage. and

Figure 3-'1. Serous appositional or so-called "kissing" choroidal detachment.

III MANUAL OF RETINAL SURGERY

Figure 3-10. Hemorrhagic choroidal detachment. Note echogenic reflections in the suprachoroidal space (arrow).

posterior ruptures may be ascertained when no viewis obtainable preoperatively.

Bvscan echography can be used to identify andlocalize foreign bodies and determine their proxim-ity to other ocular surfaces. Metal, glass. and plasticare highly reflective and are seen as bright acousti-cal point sources. Often. shadowing or loss ofreflectiveness is apparent behind metallic or otherechogenic iruraocular foreign bodies, allowingsome insight into the material involved. Plastic,non leaded glass, and vegetable matter foreign bod-ies can be detected by ultrasonography, whereasplain foreign body radiographs or CT scans maymiss these materials. An average foreign bodydiameter of I mm is necessary to permit easy detec-tion and localization, While both CT- and B-scanechography are considered excellent for the detec-tion of metallic intraocular foreign bodies, the 2-mm cuts of standard computed tomography havebeen reported to miss small foreign bodies thatwere detected by echography (Weiss. Hofeldt, andBehrens: 1997).

Foreign bodies that are near other highly reflectivesurfaces such as the globe wall, lens, ciliary body, oriris are more difficult to find. Figure 3-11 demon-strates such a foreign body adjacent to the globe wall(arrow). Foreign bodies that lie outside the globe maybe more difficult to detect since fat is highly reflec-tive and may mask foreign body echoes. Spherical

foreign bodies such as BBs or buckshot arc particu-larly easy to find, whether they arc intraocular orextraocular. The parallel surfaces of these sphericalobjects cause ultrasonic reverberation within the for-eign body, producing a trail of duplication echoes thatextend directly behind the main foreign body echo onthe ultrasound screen (Figure 3-12). A small intraocu-lar air or gas bubble gives an identical sound pattern.Unlike the foreign body. however, the air or gas bub-ble can usually be mobilized during positioning of thepatient's head in a kinetic examination.

Echographic identification of a hernorrhug ic ret-inal detachment is a grave finding in an eye fol-lowing trauma. Figure 3-13 illustrates such ahemorrhagic retinal detachment. Most eyes withextensive subretinal hemorrhage are lost regardlessof the surgical skills employed to save the eye.

Electrophysiology(:'.

Preoperative electrophysiological studies are sel-dom indicated in eyes with clear media and retinaldetachments. In contrast, eyes with media opacitiesand a possible retinal detachment or other posteriorsegment disease may often benefit from electro-physiologic evaluation. The two primary tests uti-lized are the bright-flash ERG and the flash visuallyevoked response (VER).

Preoperative Ophthalmic Echography and Electrophysiology 19

FiJ.;ure 3-11. lntruocular foreign body adjacent to globe wallIarrow).

Figure 3-12. Metallic intraocular foreign body (BB). Arrow demonstrates trail uf duplication echoes extending behindforeign body.

The electroretinogram (ERG) records the electricalresponse of the retina to photic stimulation. Twoprincipal waves are generated; an initial negativewaveform culled the a-wave fo llowcd by a

positive waveform, the so-called b-wave (Figure3-14). The a-wave is derived from the outer retina(rod and cone photoreceptors), and the b-wave orig-inatcs from the inner retina (Muller cells and bipo-lar cell layer). Also of note, but less clinicallyimportant, are c-wave and oscillatory potentials.

E lectroretinogram

--

------ --

- 20 MANUAL OF RETINAL SURGERY

Figure 3- D. Traumatic hemorrhagic retinal detachment. Note blood in the subretinal space (arrow).

20 msec

Figure 3-14. Electroretinogram (ERG).

The c-wave represents the hyperpolarization of theretinal pigment epithelium and follows the b-wave.Diffuse degenerations that effect the retinal pigmentepithelium (RPE) may reduce the c-wave ampli-tude. Oscillatory potentials are a series of oscillat-ing wavelets that are superimposed on theascending b-wave. These may be useful clinicallyas their amplitude is decreased or absent in thepresence of retinal ischemia. Therefore, the oscilla-tory porenti als may be decreased in diabeticretinopathy, central vein occlusion, and sickle cellretinopathy.

In eyes with dense media opacities, the conven-tional ERG light stimulator used for eyes with clearmedia may not produce enough light to stimulatethe retina adequately. In such cases, a camera strobecan be used to generate up to 20,000 times more

light and thus stimulate the retina through majoropacities. This so-called bright-flash ERG tech-nique can be particularly useful for the vitrcorcunalsurgeon in evaluating the posterior segment of cycswith vitreous hemorrhage or total hyphCl11as.Cataracts alone do not block enough light to neces-sitate the use of a bright-flash stimulator.

Clinical application of the ERG is relativelystraightforward if one understands a few basicprinciples:

I. The amp! itude (height) of the a-wave corre-sponds with the amount of retina that is attachedand functioning normally. Think of a-waveamplitude as dependent on normal nutritionalsupport from the adjacent choriocapillaris. Totalretinal detachment (serous, hemorrhagic. orexudative) or loss of perfusion of the choriocap-illaris (ophthalmic artery occlusion) results inabolition of the a-wave,

2. The amplitude of the b-wave depends on normalinner retinal nutrition. Since rheb-wave followsthe a-wave and is initiated by it, anything thatdecreases the amplitude of the a-wave will ofnecessity decrease the amplitude of the b-wave.If the a-wave is extinguished, no b-wuve can hegenerated. If inner retinal nutrition is compro-mised, but the outer retina remains intact. a

decreased b-wave amplitude will be seen in thepresence of a normal a-wave amplitude.

3. No ERG is recordable in a total retinal detach-ment. Even minimal separation of the phutorc-ceprors from the retinal pigment epithcl iumcauses almost immediate loss of the ERG.

Application of the above principles allows oneto predict the ERG response in various clinical con-

ditions.

Central Retinal Artery Occlusion

The inner retina loses perfusion but the outer retinaremains nourished by the chorioccpillaris. Thus, theb-wave is extinguished or dirniru-hed in the pres-ence of a normal a-wave.

Proliferative Diabetic Retinopathy

The inner retina sutlers progressive loss of nutritionIrorn small-vessel vascular compromise. causingloss of oxci llatory potentials and b-wave amplitude.With worsening diabetic changes and retinal atro-phy or the development of tractional retinal detach-rncnt. the a-wave also diminishes.

Central Retinal Vein Occlusion

In perfused central retinal vein occlusion (CRVO).the b-wave is mainly affected, with liulc effect on

the a-wave. In nonpcrfuscd CRVO and in the pres-ence of diffuse retinal edema, both the a-wave andb-wave arc reduced.

Partial R etinat DetachmentI

The amount of reduction of a-wave amplitude cor-responds roughly with the percentage of the retinadetached. Therefore, a 50% retinal detachmentwould cause loss of one-half of the a-wave ampli-tude. Since the b-wave is triggered by the a-wave,approximately one-half of the b-wave amplitudewou ld he: lost.

Bright-flush ERG can be particularly helpful inan eye with no fundus view and an apparent total

retinal detachment seen by ultrasonography. A

Preoperative: Ophthalmic Echography and Electrophysiology 21

densely organized PVD that remains attached at theoptic nerve head can simulate a total retinal detach-ment. as mentioned earlier. In such cases, the pres-ence of a good-bright flash ERG response excludesthe possibility of a total retinal detachment andestablishes the diagnosis.

Visually Evoked Potential

The visually evoked potential (VEP), also knownas the visually evoked cortical potential (VEep). orvisually evoked response (VER). represents thesummated electrical signal generated at the visualcortex in response to visual stimulation of theretina. The YEP is smaller and buried within theelectroencephalogram (EEG). A normal YEPresponse requires not only a functional macula butalso an intact visual pathway from the macula to thevisual cortex. Since YEP responses are so small inamplitude. it is necessary to use a signal-averagingcomputer to summate responses.

Unlike the ERG. which assesses overall retinalfuric t ion , the YEP specifically evaluates theintcgruy of the central 6-12 degrees of v isual field.Thu s. the YEP provides information in eyes withopaLjue media that is available by no other meansot testing. An eye with cloudy media and count fin-gers visual potential due to a macular scar can havea perfectly normal ERG rcsponse. In contrast. suchan eye would have a severely reduced or absentYEP response. Likewise. an eye with opaque mediaand grossly compromised optic nerve functionwould have a normal ERG, but an obviously abnor-mal VEP.

The light stimulus for eliciting a YEP may be apattern such as a checkerboard or a simple flashstimulator. In eyes with opaque media. only a flashstimulator can be used. Fuller and Hutton (Il.JX2)have described a YEP technique for assessing mac-ular and optic nerve function in eyes with opaquemedia by using 10. 20, and 30 flashes per second.This technique generates "steady state" YEP sinu-soidal waveforms that can be evaluated simply bymeasuring amplitudes only (Figure 3-(5). With thismethod. it is possible for the vitrcorctinal surgeonto assess postoperative visual potential in eyes withnonv ixua l izcd posterior segments. In eyes withopaque media following severe trauma, the YEP is

the single best predictor of postoperative visual


Figur~ 3-15. Bright-flash VEP.

recovery. It must be remembered, however, that aneye with a macular detachment will have a poor ornonrecordable YEP despite the potential for thereturn of useful vision following successful surgi-cal repair.

Conclusion

Access to ultrasonography is essential for the vit-reoretinal surgeon and has become an integral partof the preoperative evaluation of any eye withopa4uc media. Electrophysiology, although of lesspractical value than ultrasonography. gives the vit-rcorct inal surgeon an added dimension in the pre-opcrut ive evaluation of eyes with opaque mediaand can be a distinct aid in the prediction of post-operative visual function in traumatized eyes withcloudy media.

Suggested Reading

Coleman OJ. Jack RL. B-scan ultrasonography in the diag-nosis and management of retinal detachments. ArchOplllhalmoI1973:90:29.

Coleman OJ. Lizzi FL. Jack RL. Ultrasonography of the Eyeand Orbit, Philadelphia: Lea & Febiger: 1977.

Cusumano A, Coleman OJ, Silverman RH, et al. Three-dimensional ultrasound imaging-clinical applications.Ophthalrnol 1998: 105 :300-306.

Fuller, OG. Assessment of visual potential in eyes withdensely opaque media. Ophthalmology Clinics of NorthAmerica Sept. 1989;2(3).

Fuller OG, Hutton WL. Presurgical Evaluation of Eyes withOpaque Media. Orlando, FL: Grune & Stratton; 1982.

Fuller OG, Hutton WL. Prediction of postoperative vision ineyes with severe trauma. Retina 1990;10:520-534.

Fuller DG, Knighton RW, Machemer R. Bright-flash elec-troretinography for evaluation of eyes with opaque vit-reous. Am j OphthalmoI1975;80:2I4.

Fuller OG. Laqua H, Macherner R. Ultrasonographic diag-nosis of massive periretinal proliferation in eyes withopaque media (triangular retinal detachment). Am J

Ophthalmol 1977;83:460.Hirose T. Miyake Y, Hara A. Evaluation of severe ocular

trauma: electroretinogram and visual evoked response.In: Freeman HM, ed. Ocular Trauma. East Norwalk,CT: Appleton-Century-Crofts: 1979:31.

Huber CH. Amplitude versus frequency characteristics ofvisually evoked conical potentials to sine wave modu-lated light in disease of the optic nerve. In: Lawwill T.cd. ERG. VER. and Psychophysics.' 14th I.SeER.G.Symposium. Louisville, KY: Junk Publishers; 1977.

Hutton WL. Fuller OG. Factors influencing final visualresults in severely injured eyes. Am j Ophtl"'/"'''/191\4:97;715.

Jack RL. Hutton WL, Machcrncr R. Ultra"mllgraphy andvitrectorny, A", J OphtllUl",,,1 197~:71\:26'i.

Kelley LM. Walker JP. Schepens CL. CI JI. Ultra sound-guided cryotherapy for retinal tea" in patients withvitreous hemorrhage. Ol'hrllUlmic S"rx Lasers 1997:28:565-569.

Sokol 5. Visually evoked potentials: theorv, techniques andclinical applications. SUTI' Opluhalmo! 1976;21: 18.

Srebo R. Wright WW. Visually evoked putemials 10 pseudo-random binary sequence stimulation. Prcliminary clin-ical trials. Arch Ophthalmo! 1980;91\:296.

Weinstein GW. Clinical aspects of the visual evoked potcn-tial. Ophthalmic S,,"X 1978:9:56.

Weiss MJ, Hofeldt AJ, Behrens M. et al. Ocular siderosis:diagnosis and management. Retina 1997: 17: 105-1 08.

1:-.

,"

4Laser Photocoagulationand Cryopexy of Retinal Breaks

David W. Parke II

Retinal breaks. whether atrophic retinal holes, oper-culated retinal holes. retinal dialyses, or retinal tearswith a flap under vitreous traction (horseshoe tears).may be associated with retinal detachments. Undercertain circumstances. the ophthalmologist maywish to treat these breaks prophylactically to reducethe chances of the development of a clinical retinaldetachment.

There are five major steps in this process.

l. Detection of the retinal break(s)2. Making a treatment decision3. Selection of treatment modality4. Treatment of the retinal.breakrs)5. Follow-up of treatment

Detection of Retinal Break(s)

The vast majority of retinal breaks are asymptomatic.They are discovered on routine examination of thepe~ipheral retina by indirect ophthalmoscopy or byslit lamp biomicroscopic examination either usinga contact lens with angled mirrors (such as a Gold-mann 3-mirror lens) or a noncontact lens (such as a78- or 90-diopter lens). Although the prevalence ofretinal breaks has been reported to lie between 4%and 18%, it is generally accepted that the preva-lence of asymptomatic retinal breaks in the generalpopulation is approximately 6%.1 Certain patients,although asymptomatic, should be considered athigher risk for retinal breaks and should be exam-

ined with a higher index of suspicion. This includespatients with a history of retinal detachment in mefellow eye; a strong family history of retinal detach-ment; high myopia; disorders associated with vitre-oretinal traction and retinal detachment such aslattice degeneration and Stickler's syndrome;aphakia; or pseudophakia with anterior segment vit-reous adhesions or incarceration.

Symptomatic retinal breaks are much less com-mon than asymptomatic ones. They are generallyassociated with spontaneous detachment (separa-tion) of the posterior vitreous. This detachment andsubsequent anterior migration of the posterior bor-der of the vitreous may induce traction in an area ofvitreoretinal adhesion. resulting in tearing of theretina. Such tears become symptomatic when theyare accompanied by light flashes (photopsia) or thesudden appearance of new floaters. These floaters(which may represent pigmented cells, red bloodcells, or posterior vitreous condensation) aredescribed by the patient as "spots," or (if they aremore numerous) "lines" or "clouds." A posteriorvitreous condensation may also be described as a"cobweb" or a "fishnet." The photopsia may OCCl!ronly once or may occur repeatedly over a period ofdays or weeks. Although these photopsia are gener-ally noticed in the temporal visual field, this has novalue for localizing the retinal break.

Every patient with the sudden onset of photop-sia and/or floaters does not necessarily have a reti-nal break. However, all such patients (unless theyare known to have an unrelated disease causing

23


these symptoms) deserve a careful examination todetermine if a break is present. Although vitreoushemorrhage may accompany a posterior vitreousdetachment unassociated with a retinal break, thefinding of red blood cells or frank vitreous hemor-rhage should particularly alert the examiner to thepossibility of a retinal break ..Finding pigment cellsin the vitreous is also highly associated with thepossibility of a coexisting retinal break.

Indirect ophthalmoscopy with scleral indentation(also known as scleral depression) remains the mostvaluable method of finding retinal breaks. Althoughmany breaks can be discovered without the use ofscleral indentation, tiny breaks, anteriorly locatedbreaks, atrophic breaks, and breaks in highlymyopic or lightly pigmented eyes may be easilyoverlooked if scleral indentation is not performed.Scleral indentation also permits more accuratedetermination of the presence and amount of sub-retinal fluid surrounding a break.

Most comprehensive ophthalmologists do notuse biornicroscopic examination of the peripheralretina on a routine basis. However, biomicroscopicexamination of the peripheral retina using a contactor noncontact lens can be valuable when a break issuspected but not clearly visualized by indirect oph-thalmoscopy with scleral depression. (A noncontactlens is preferred by many retina subspccialists overa contact lens, as it avoids the use of contact lubri-cants that can make subsequent indirect ophthal-moscopy difficult.)

If a small. difficult to visualize retinal break isdiscovered. the examiner should take careful noteof the location of the break in relation to other moreeasily visualized fundus landmarks such as chorioreti-nal scars. retinal vessels. VOJ1ex veins and ampul-Iae, and others. This will greatly facilitate localizingthe break during later treatment.

Decisions Regarding Treatment:Is Treatment Necessary?

If a retinal break is discovered on indirect ophthal-moscopy or biornicroscopic examination, the patientmust be informed of the findings, their significance,

.and the management options. Only then can anappropriate management decision be reached. Aswill be noted below, a decision to treat or not to treatis sometimes quite obvious to the ophthalmologist

and is supported by statistically valid data. In mostsituations, however, data do not currently exist toclearly direct a management decision. Availableincomplete data and the risks and benefits of thera-peutic options must be presented to the patient. Inthe hands of an experienced surgeon, the treatmentof retinal breaks should be associated with a very,very low incidence of complications. However, thisinfrequency of complications should not be trans-lated into a rationale to treat all breaks. Treatment ofmost asymptomatic retinal breaks Is not substanti-ated by available prospective data. Therefore, whiletreatment may carry a very low frequency of com-plications, it can be associated wirh discomfort andsubstantial cost, and may be ultimately unnecessary.

If most retinal breaks led to retinal detachment,the relative incidence of breaks would be similar tothat of retinal detachment. The incidence of clinicalretinal detachment (0.01-0.02%) is much lower thanthat for the discovery of retinal breaks. Byer, in along-term prospective follow-up of 235 eyes withasymptomatic retinal breaks (including 46 eyes withtraction retinal tears). detected no subsequent clini-cal retinal detachment from the nontrcatcd rears."

Even the treatment of lesions in certain groupsof "high-risk" eyes has not been statistically vali-dated. A large prospective trial treating vitrcorctinalpathology in fellow eyes of retinal detachmentpatients in Israel concluded that treatment conferredno significant benefit;' Yet another study observedthat it is not preexisting pathology that causes sub-sequent retinal detachments, but new breaks inretina previously felt to be normal."

How does the ophthalmologist determine whichbreaks require treatment? Certain criteria-some"hard" and some "soft"--ean assist in making thisclinical judgment.

Symptoms

The presence or absence of associated symptoms(photopsia and/or new floaters within-several weeksof examination) is the most important determinantof risk. In one series, symptomatic breaks wereassociated with subsequent clinical retinal detach-ment formation in about 30% of cases.~ Therefore,any break associated with fresh symptoms of pho-topsia and/or floaters should be strongly consideredfor treatment.

Tear versus Operculated Retinal Break versusAtrophic Retinal Break

The risk associated with the various types ofasymptomatic breaks has not been well quanti-fied. In his series, Mer in et al. discovered that19% of fe llow eyes had retinal breaks, 15% ofwhich later developed retinal detachments." Ofthose detachments, 71 % came from flap (or"horseshoe") tears and only 19% of the breakswere tears.

Tract io na l retinal rears, as noted above. aremore frequently assoc iated with symptoms andare therefore of more clinical significance. How-ever. it is not uncommon to find tractional tearsthat, by virtue of their appearance and associatedpigment epithelial reaction, have clearly beenpresent for months if not years. Therefore.asymptomatic tractional tears themselves do notnecessarily confer a poor prognosis. As notedabove. Byer evaluated 50 tractional tears for upto IR years without tre atrnerit and without anysubsequent retina! detachment. Although thestrongest data favoring treatment of horseshoetears are for symptomatic tears, some ophthal-mologists believe that all tractional tears shouldbe treated. Others believe that the treatment deci-sion should be made on the basis of associatedfactors such as symptoms. myopia, family his-tory. status of the fellow eye. and lenticular status(phak ia, aphakia. pseudophakia, and impendingpseudophakia).

Atrophic retinal holes with or without associatedlattice degeneration constitute a very common typeof retinal break. They are very rarely symptomatic.Furthermore. it is questionable whether they areresponsible for symptoms even when associatedwith them. Pathophysiologically. they are not asso-ciated with vitreous traction but with progressiveretinal atrophic changes. As such, they are veryrarely associated with retinal detachments andtherefore rarely require treatment.

Operculated retinal breaks are felt to generallybe low risk lesions as well. As the flap of the tearpulls free under vitreous traction creating theoperculum, traction on the break is usuallyrelieved. Occasionally, however, vitreous tractionwill remain to the retina surrounding the hole. Ifsuch traction is detected or strongly suspected.such lesions may be considered for treatment.

Laser Photocoagulation and Cryopexy of Retinal Breaks 25

Phakiat Apha kial Pse udoplzakia

The incidence of retinal detachment in aphakic eyesis clearly higher than in phakic eyes. Several smallseries have suggested that the incidence of retinaldetachment in aphakic eyes with known retinalbreaks is substantially higher than in a similar pha-kic group. Population-based studies have indicatedthat the risk of retinal detachment is 6 to 7 timeshigher following modern cataract surgery than inphakic control groups."

The risk of various types of retinal breaks in the:pseudophakic eye has not been clearly elucidated.There is, for example, no clear assessment ofthe risk of asyrnptornatic retinal breaks to thepseudophakic eye. It is clear, however. that the riskof retinal detachment is much higher in the eye withan open posterior capsule than when the capsule isintact." This is probably related to factors includingacceleration of the posterior vitreous detachment.changes in the chemical constitution of the vitreousand/or anterior movement of the anterior vitreous.While all symptomatic breaks should probably betreated and all asymptomatic atrophic holes shouldprobably not be treated. lesions of intermediate risk(such as an asymptomatic flap tear) arc deemed bymany (in the absence of good data) to be higher riskin pseudophakic than in phakic eyes.

Good data do not exist to help guide manage-ment decisions in phakic eyes with lesions of inter-mediate risk that will shortly undergo cataractsurgery or in pxeudophakic eyes scheduled for YAGcupsu lotorriy, Treatment in such cases should beindividualized taking into account patient demo-graphics, associated risk factors, and the character-istics of the lesion in question.

Myopia

Myopia has been considered an important factor bysome in electing to treat asymptomatic retinalbreaks. Studies published by the Eye Disease Case-Control Study Group and by Burton have demon-strated that myopia from I to 3 diopters isassociated with a fourfold increase in retinal detach-ment risk and that higher myopia is associated witha ten times increased risk9.IO However, patientswith highly myopic eyes also have an increasedprevalence of asymptomatic retinal breaks over the


general population. Therefore, asymptomatic reti-nal breaks in myopia may not confer a statisticallyworse prognosis than in emmetropia. Neumann andHymas reported in 1972 that only one clinical reti-nal detachment occurred in a group of 75 myopiceyes with retinal breaks evaluated for 2 years with-out treatment. II The one break that did progress to aclinical detachment was a 90-degree tractional tear.Byer noted a statistical association between highmyopia and subclinical retinal detachments but notwith cl inical retinal detachrnents.? The high risk ofretinal detachment following cataract extraction inhigh myopia (12-30%) has led some ophthalmolo-gists to recommend treatment of retinal breaks inaphakic or pseudophakic highly' myopic eyes aswell as in highly myopic phakic eyes prior tocataract surgery.

Fellow Eyes

A history of retinal detachment in one eye clearlyconfers a higher than normal risk for retinal detach-ment in the fcllow eye. Several studies have indi-cated that prophylactic treatment of retinal tears inthe fellow eye appears to lower the subsequent riskfor retinal detachment.' While this has not been val-idated by a large prospective study, most ophthal-mologists use this information 3S a basis for treatingtears in fellow eyes of patients with prior retinaldetachments, particularly if cataract surgery or YAGcapsulotomy is scheduled.

Associated Subretinal Fluid

It is not uncommon to find subretinal fluid associ-ated with retinal breaks, either symptomatic orasymptornatic. Strictly speaking. this constitutes aretinal detachment. However, such detachments areconsidered subclinical or limited if the fluid extendsless than two disc diameters posterior to the equa-tor. Therefore, even a eircumferentially extensivearea of subretinal fluid that remains anterior to theequator is still subclinical. Some subclinical retinaldetachments are clearly chronic (based on the asso- .eiated demarcation lines and changes in the under-lying retinal pigment epithelium). It is not rare tofind multiple subclinical retinal detachments asso-ciated with atrophic holes and lattice degeneration.

There are no data to suggest that these subclinicaldetachments are associated with a higher incidenceof clinical retinal detachment. The association ofsubstantial (but subclinical) subretinal fluid withtractional tears is considered by most to be an indi-cation for treatment.

Other FactorsI

A number of other factors are occasionally invokedin making a decision regarding treatment. Largetears and superior tears are thought by some tocarry a worse prognosis. There is no statisticalinformation to validate this clinical impression.

Lattice degeneration by itself (separated fromother previously mentioned factors) does not appearstatistically to confer an additional risk.12 Someophthalmologists believe that asymptomatic retinaltears at the edge of patches of lattice degenerationwarrant treatment because of the associated strongvitreoretinal adhesions.

The institution of miotic therapy in patients withhigh myopia or aphakia has been associated withretinal detachment. Therefore some ophthalmolo-gists recommend prophylactic treatment of tears inpatients with these findings prior to beginningmiotic therapy.

Conditions such as Ehlers-Danlos syndrome andStickler's syndrome are associated with a higherrisk of retinal detachment. It is not clear whetherthis risk is due to the associated myopia or to thevitreoretinal pathology inherent in these syndromes.Tractional tears in patients with these conditions aregenerally considered to warrant therapy, regardlessof symptoms.

It has also been suggested that treatment deci-sions be based in large measure on the relationshipof the tear to the vitreous base." Tears are thus cate-gorized as oral if they occur at the ora serrata, intra-basal if they occur within the vitreous base,juxtabasal if they occur at the posteriorborder of thevitreous base, and extrabasal if they are located pos-terior to the vitreous base. Sigelman has suggestedcriteria for treatment based in large part on this clas-sification. He argues that juxtabasal tears carry thehighest risk of retinal detachment of all postoratears, and intrabasal tears carrying the lowest risk.

Of all the factors noted above, the presence ofassociated symptoms is the most compelling argu-

rnent for the treatment of retinal tears. All other fac-tors are supported by less compelling scientificdata. Treatment decisions depend in part on theassociation of various factors and the clinical expe-rience and predisposition of the physician involved.This is not to say that only symptomatic breaksshould be treated. but for these the clearest statisti-cal rationale for treatment exists. Certainly mostophthalmologists would recommend treating a largeretinal tear in a highly myopic aphakic orpseudophukic eye. even one without symptoms. Onthe other hand. few ophthalmologists would recom-mend treatment of In asymptomatic atrophic reti-nal hole in aphakic patient as there exists no data tosupport this action. .

Selection of Treatment Modality

There are two basic options for the treatment ofperipheral retinal breaks with or without an associ-ated subclinical retinal detachment; cryopexy andlaser photocoagulation. Only rarely would othermore invasive treatments (cryopcxy or laser photo-coagulation in combination with either intruvirrcnlgas injection. usc ofan cxtrasclcral balloon. scleralbuckling. or primary vitrcctorny) be considered.

These other modalities have essentially no placein the management of simple retinal breaks. Theymay be used occasionally if there is associatedextensive subretinal fluid, profound vitreoretinaltraction, or significant vitreous hemorrhage.

Cryopexy

Cryopexy involves the use of a nitrous oxide or car-bon dioxide probe applied to the scleral or conjunc-tival surface, which causes transcleral freezing witha~ iceball extending to the pigment epithelium andusually the retina. The inflammatory reaction medi-ated by the freezing (and thawing) creates achoroidal/retinal pigment epithelial/retinal adhe-sion. Studies have shown that tight dcsrnosornalconnections have formed between the retina andretinal pigment epithelium by 8-12 days followingapplication." This follows cellular disruption owingto destruction of cell membranes. The amount ofnecrosis appears to be correlated with the size andextent of the freeze.


Within 2 weeks of cryopexy, adjacent retinalpigment epithelial (RPE) cells slide in to replace thecells disrupted by freezing. Desrnosornal connec-'tions form between the RPE cells and the overlyingMuliers cells. Over subsequent weeks and monthsthe scar undergoes remodeling. with interdigitationbetween the RPE and adjacent Muliers cell plasmamembranes. The maximum strength of the cryoad-hesion appears to occur between I and :2 weeks fol-lowing treatment.

Advantages

Cryopexy has several advantages as a treatmentmodality. It can be performed in conjunction withtopical. subconjunctival, or retrobulbar anesthesia.Treatment of most retinal breaks requires very fewapplications and is generally easy to perform with-out a conjunctival incision for any jeur from theequator to the ora serrata. It is generally performedas an outpatient procedure in the office. It is partic-ularly useful in cases where visibility is compro-mised by vitreous hemorrhage. a pscudophakosedge, lens opacities. or an opacified peripheral pos-terior capsule.

Disadvantages

Cryopexy also has several disadvantages. It is diffi-cult to treat more posterior breaks in most eyesunless the probe is placed subconjunctivally. It isassociated wjth more intlammation than is laserphotocoagulation and with more postoperative lidswelling and conjunctival chemosis. If topical anes-thesia alone is used, it is frequently associated withmoderate to severe discomfort. For this reason,many surgeons will at least supplement topicalanesthesia with subconjunctival anesthesia,

Complications

Complications of treatment are few. A recent retro-spective study by Roseman and colleagues of 241eyes with retinal breaks and subclinical detach-ments treated by transconjunctival cryopexyrevealed anatomic retinal attachment in 95% of thecases.'> Epiretinal membrane formation (premacu-lar fibrosis) sufficient to cause visual symptomsoccurred in some eyes following cryopexy. Theoverall incidence is probably between I % and 4%.


The role of cryopexy in epiretinal membrane for-mation is unclear. The RPE cells responsible in partfor the membrane can migrate through the retinalbreak without cryopexy or at the time of cryopexy.It is important to note that clinically and experi-mentally cryopexy does result in liberation of viablepigment epithelial cells into the vitreous cavity.!"

The progression of a very small number of reti-nal breaks (or retinal breaks associated with sub-cl inicul detachments) to clinical detachmentsfollowing cryopcxy may occasionally be related tothe cryopexy itself. Extensive eryopexy can beassociated with intraocular inflammation and fluidexudation (of choroidal origin) into the subretinalspace. These factors, alone or in combination, mayresult rarely in retinal detachment. Some retina sur-geons also believe that extensive cryopexy may beassociated with sufficient dispersion of retinal pig-ment epithelial cells and inflammation as to stimu-late the formation of proliferative vitreoretinopathy.This has not been proven.

Laser Photocoagulation

Laser photocoagulation is also a very efficaciousmode of therapy for retinal breaks with or withoutsurrounding subc lmical retinal detachment. Thelaser energy results in damage to the RPE (wheremost of the laser energy is actually absorbed), theouter retina, and the choriocapillaris. This results ina retinal-Rl'E bond similar ultrastructurally to thatfrom cryopexy. (The individual lesions are, ofcourse, smallcr.) Several studies have also sug-gested that the mechanical adhesion formed by pho-tocoagulation appears somewhat earlier followinglaser photocoagulation than following cryopexywith at least some adhesion present irnrnediarelyfollowing the laser treatment.

Advantages

Laser photocoagulation has a number of practicaladvantages. Like cryopexy, it can be performed inassociation with topical, subconjunctival, or rarelyretrobulbar anesthesia. With clear media and good

. pupillary dilation, it can be used to treat lesionsfrom the ora serrata to the posterior pole. It is par-ticularly useful for the treatment of more posteriorbreaks. It appears to be associated with less vitre-

ous inflammation and exudation. Laser photocoag-ulation is also experimentally associated with lessliberation of viable RPE cells into the vitreous cav-ity than is cryopexy. It is not clear whether this isdue to the biomechanics of the laser scar itself or tothe more precise (and generally less extensive)treatment that the fine control of laser photocoagu-lation permits.

There are no large studies comparing the clinicalresults of laser photocoagulation and cryopexy forretinal breaks. However, it appears that laser photo-coagulation is at least as efficacious as cryopexy.There are reasons to suspect that it might be associ-ated with less epiretinal membrane formation thancryopexy (although these data are not available).

Disadvantages

Like cryopexy, laser photocoagulation of theperipheral retina can also be somewhat painful.Because more precise control of spot location isnecessary, it may be more difficult to perform in thephotosensitive patient who cannot maintain rela-tively good control of fixation. It may also beimpossible to perform far peripheral treatment inthe presence of poor pupillary dilation, peripheralcortical or (in the pseudophakic patient) of periph-eral capsular opacification or dispersion of laserenergy by the edge of a pseudophakos.

Which Laser Wa\'elength Should 81' Used?

The longer exposure times, deeper burns, andincreased discomfort associated with longer wave-length (particularly red) laser treatment probablyconstitute a minor argument in favor of green wave-lengths for transpupillary laser. Diode lasers havealso been used in a transconjunctival fashion fortreatment of peripheral breaks, but are not widelyemployed for office-based treatment.

Cryopexy versus Laser Photocoagu'l~tion

ln summary, both treatment modalities appear tobe highly efficacious and associated with a verylow incidence of side effects and complications .Many retinal breaks can be treated with equalfacility with either form of therapy. ln general,cryopexy is most useful for anterior breaks and

eyes with media opacities. In each of these cases,visualization may be inadequate for slit lamplaser photocoagulation. (Indirect ophthalmoscope-delivered laser can be performed in many suchcuses.) Cryopexy or indirect ophthalmoscope-delivered laser photocoagulation are also theoptions of choice in small children and others whowill not cooperate for laser photocoagulation (andmust be sedated).

Laser photocoagulation is definitely easier thancryopexy in more posterior breaks. It is also gen-erally easy to perform regardless of break locationin adults with good dilation and no peripheral lensopacities. Even the most anterior of breaks can fre-quently be treated with an indirect delivery systemand scleral indentation. Laser also possesses the-oretical advantages in eyes with large breaks orthose requiring extensive treatment, since itinduces less inflammation and less RPE cell dis-persion. It is also frequently a more comfortableprocedure for the patient. and is associated with nopostoperative lid or conjunctival swelling. Mostimporturu ly. however. laser is associated with lessexudation of fluid than cryo and it experimentallyappears to form a biorncchanicu! adhesionbetween rcti na and RPE more rapidly than doescryopexy,

Treatment Technique

Cryopexy

The patient should be placed in the supine position.either in an examining chair or on an examining oroperating ruble. Topical, subconjunctival, or retro-bulbar anesthesia may be used. In general mosttreatment can be performed comfortably with theuse of subconjunctival lidocaine (Xylocaine) 1% or2%. This can be administered using a 30-gauge nee-dle and tuberculin syringe following topical anes-thesia with proparacaine 0.5% and lidocaine 2% ona cotton-tipped applicator applied to the injectionsite. If retrobulbar anesthesia is used, the resultingak incsia may require that a muscle hook or scleraldepressor be used to rotate the eye into a positionwhere the retinal break can be visualized and thecryoprobe easily positioned.

A nitrous oxide or carbon dioxide cryoprobe maybe used. The probe should be primed so that the


probe tip temperature of -50°C to -80°C is achievedwithin several seconds. The probe should be placedon the conjunctiva and the patient asked to look in adirection that allows easy indentation of the bordersof the; retinal break or subretinal fluid by the tip ofthe cryoprobe (Figure 4-1A). Care should be takento ensure that the; indentation visible ophthalmo-scopically is caused by the probe tip and not by theprobe shaft. If the shaft is indenting the sclera, eitherno visible freeze will occur (the tip is not appliedagainst the globe) or the freeze will be much moreposterior than intended (Figure 4-1 B).

The area to be treated should then be frozen withthe cryoprobe. In general. the ophthalmologist

Figure 4-1. A, Scleral indentation at the retinal break bythe tip of the cryoprobe. B, "False" scleral indentation atthe retinal break by the cryoprobe shaft.


should aim for a 1-2-mm diameter area of retinalwhitening. This can usually be achieved by releas-ing the foot-pedal the instant retinal whitening isfirst observed. Do not overfreeze. A single retinalfreeze should not be ailowed to enlarge to cover alarge retinal break. This results in extreme necrosisof the center of the cryo reaction, encourages pig-ment epithelial cell liberation, and increases theinflammatory reaction. It is preferable to use multi-ple, overlapping small cryo marks rather than one,single, large cryo mark (Figure 4-2).

After each freeze has been stopped, do not move thecryoprobe immediately but wait until there has beenthawing of the probe from the conjunctiva. This can befacilitated by irrigating the tip of the cryoprobe withbalanced salt solution. Premature movement of thecryoprobe can result in subconjunctival, episcleral, or,rarely, choroidal hemorrhaging. After the iceball hasvanished ophthalmoscopically, there may be no visibleresidual of the freeze. (Occasionally a faint gray colorwill persist.) Therefore, the ophthalmologist shouldcarefully note the location of each zone of retinalwhitening to allow proper overlapping of cryo markswithout rctrcatrncnt or skipped areas of nontrcatrnent.

If no iceball is visible ophthalmoscopically aftera reasonable period of freezing (4-6 secondsdepending on the cryo unit), check (I) to make surethe cryoprobe tip is directly applied against thesclera (not on the lid, angled improperly, or over arectus muscle; a longer freeze may be necessary inthis last case) and (2) to ensure proper machinefunction (gas pressure, probe function).

Which specific area should be treated') If no sub-retinal fluid is present, treatment should be directedto the borders of the retinal break. There is no pur-

Figure 4-2. Proper application of the multiple cryo spots.

pose in treating the bare RPE in the middle of theretinal break. (There is no overlying retina in thisarea to create an adhesive bond.) The surgeonshould attempt to leave a l-disc-diarneter margin ofcryo reaction around all edges of the retinal break,If the break is under significant traction, a widerzone of treatment should be placed anteriorly incase there is further enlargement of the break ante-riorly from traction on the flap. If a sufficient mar-gin cannot be created between the break and the oraserrata, treatment should be extended anteriorly tothe ora serrata on each side of the break.

If there is subretinal fluid, treatment should bedirected at the borders of the subretinal fluid ratherthan at the borders of the retinal break (Figure 4-3).Cryopexy will not generally cause resolution of thesubretina! fluid. Therefore, treatment of borders of thebreak will result in no adhesion because of the physi-cal separation of the RPE and retina caused by thesubretinal fluid. Treatment must therefore be directedat the border between attached and detached retina.Again, if fluid extends anteriorly to the ora serrata,treatment must be extended to the ora serrata,

Following cryopexy, the patient should beinstructed to use cold compresses or ice packs toreduce lid swelling. If there has been extensive treat-ment, the surgeon may wish to use topical cortico-Steroids for 3-5 days to decrease conjunctivalinflammation.

Laser Photocoagulation

Most patients can be treated comfortably under top-ical anesthesia. In some patients, retrobulbar anes-

Figure 4·3. Proper application of cryo spots to surroundsubretinal fluid and link with {he ora scrrara,

thesia may be necessary. Using a slit lamp deliverysystem, once the retinal break has been locatedusing a contact lens, a test burn should be placed innearby attached retina. A 200-0101 or, preferably, a500-0101 spot size should be utilized. A duration of0.1 or 0.2 seconds can be used. Generally, powersettings in the range of 100-300 mW with a greenwavelength laser will be required for the desiredgray-white retina/Rf'E bum for a 200-0101 spot size;power settings of 200-500 mW are typically usedfor a 500-0101 spot size. It is safest to start withlower power settings and work upward. If an indi-rect ophthalmoscope delivery system is utilized,similar spot durations should be employed withpower settings to achieve the same visible gray-white endpoint.

If no subretinal fluid is present. the borders ofthe retinal break should be surrounded by a doubleor triple row of confluent laser photocoagulation(Figure 4-4). [f the break is under traction, a moregenerous treatment margin should be placed anteri-orly to provide a good margin of treatment in theevent of further anterior tearing of the retina fromtraction on the flap. If the break is close to the oraserrate. treatment should be extended anteriorly tothe ora serrata,

If subrerinal fluid is present, treatment shouldagain be directed at the attached retina just beyondthe border of attached and detached retina. There isno purpose in attempting to treat detached retina.

Occasionally, laser photocoagulation will be dif-ficult to achieve in the very far peripheral retina justposterior to the ora serrata. This is particularly truein cases of cataract, poor pupillary dilation, or opti-cal aberration from a posterior chamber intraocular

Figure .1-4. Proper application of laser bums around aretinal break.


lens or peripheral posterior capsule opacification.In these situations, it may be necessary to place oneor several cryo marks to link the most anterioraspect of the laser photocoagulation with the oraserrate or to use the indirect ophthalmoscope-delivered laser.

Following laser photocoagulation there is gener-ally no need for topical medication.

Follow-Up Care

In general, the patient should be instructed to returnfor a follow-up evaluation about one week follow-ing treatment. There are no data to suggest thatrestriction of activity plays any role in efficacy oftreatment or in later complications. In general a sat-isfactory ophthalmoscopic appearance at I weekfollowing treatment will be associated with a satis-factory eventual outcome. although patients shouldgenerally be reevaluated again within 3 to 6 weeks.At these exam inations care should be taken toassure that subretinal fluid has not extended throughthe prior treatment. If this has occurred. the patientshould generally be retreated.

It is important to counsel patients about thesymptoms that might suggest subsequent new reti-nal breaks or subsequent detachment associatedwith treated breaks. Several studies have suggestedthat patients have between a 59'0 and 10% chance ofdeveloping a new retinal tear in an eye that has pre-viously undergone treatment. Such tears may occurremote from the area of treatment or may occur atthe border of the treatment scar and normal retina.Therefore, any patient with new photopsias, sub-stantially different floaters, or a peripheral fielddefect should be promptly reevaluated.

In the months following treatment (particularlycryopexy) the treated area may become moreatrophic in appearance. If treatment was placedaround the borders of a subclinical retinal detach-ment, the fluid within these borders will generallypersist. The ophthalmologist should therefore notexpect subretinal fluid within the borders of treat-ment to disappear entirely, although it may eventu-ally do so,

Patients should be informed that treatment ofretinal breaks is successful in about 95% of cases.Careful follow-up is necessary since 5% to 14% ofeyes will subsequently develop new breaks in either

32 MANUAL OF RETINAL SURGERY-eye.!? Counseling regarding the symptoms of newtears and retinal detachment is mandatory. Patientsshould be instructed to cover the noninvolved eyeregularly in the weeks following treatment andcheck their peripheral visual field. They shouldknow that prompt management of a retinal tear mayeliminate the need for retinal detachment surgeryand that prompt management of a retinal detach-ment optimizes the chances for best final visualacuity. Additionally. patients should be informed ofepirctinal membranes as a late complication of reti-nal tears-treated or untreated.

References

I. American Academy of Ophthalmology Preferred Prac-tice Paucrns Comrnince Retina Panel. Management ofposterior vitreous detachment, retinal breaks. and lat-tice degeneration. San Francisco. 1998.

2. Byer NE. The natural history of asymptomatic retinalbreaks. Ophthalmologv 1982;89; I033.

3. Michelson Ie. Stein R. Neuman E, et al. A nationalcooperative study in the prevention of retinal detach-ment. In: Pruct Re. Regan CDJ. cds. Retina Congress.New York: Applcron-Ccntury-Crofts: 1972:661--667.

4. Benson WE. Grand G. Okun E. Aphakic retinal detach-ment. Management of the fellow eye. Arch Ophthalmol1975:93;245-149.

5. Davis MD. Natural history of retinal breaks withoutdetachment. Arch Ophthalmol 1974:92: 183-194.

6. Merin S. Feiler V. Hyams S. et ul. The fate of the felloweye in retinal detachment. Am J Opluhalmol1971:7 I :477""+81.

7. Rowe JA. Erie JC. Gray DT, ct al. Retinal detachmentin Olmsted County, Minnesota 1976-1995. Opllllwl-mology 1999: J 06; 154--159.

8. Tielsch JM. Lcgro MW. Cassard SD. et al. Risk factorsfor rct inal detachment after cataract surgery. A pop-ulation-buse d case-control study. Ophthalmology1996: I03: 1537-1545.

9. The Eye Disease Case-Control Study Group. Risk fac-tors for idiopathic rhcgrnaiogcnous retinal detachment.Am'! EpidemiuI1993:137:749-757.

10. Burton TC. The influence of refractive error and latticedegeneration On the incidence of retinal detachment.Trans AII1 Ophthalmol Soc 1989:87: 143-155.

II. Neumann E. Hymas S. Conservative management ofretinal breaks. Br J 01'''''10111101 1971:5fi:4X1.

11. Byer NE. Long-term natural history of lattice degener-ation of the retina. Opluhulmolog» 19X9:96: 1396-1401.

13. Sigelman J. Vitreous base classification of retinal tears:clinical application. Surv Opluhalniol 1980:15:59.

14. Lincoff H. Krcissig I. Jakohicc F, ct al. Remodelinguf the cryosurgical adhesion. Arch 0l'h,'/{/IIII,,1

1'i81:99;IX45.15. Roseman RL. Olk RJ, Arribas NP. et al. Limited retinal

detachment: a retrospective analysis of treatment withIransconjunctival retinocryopexy. Ophthulmologv19X6:93:216.

16. Cumpoc hiaro PA. Kaden IH. Viduurri-Lcal J. et al.Cryotherapy enhances intravurcal dispersion of viableret inal pigment epithelial cells. Arc" 01' III Iw 111I,,1I%5: I()~:434.

17. Smiddy WE. Flynn HW Jr. Nicholson DH, et ul.Results and complications in treated retinal breaks. Alii

J 01'111110111I01 1991: 112:623--63 I.

<:

5Pneumatic Retinopexy

Paul E. Tornarnbe

This chapter emphasizes case selection, surgicaltechnique. and complications of pneumaticretinope x y.

Pneumatic re t inope x y, a term coined byGeorge Hilton in 1985, uses a positioned intra-vitrca l gas bubble to reattach the retina. Recentreports with this technique describe a single oper-ation success rate of 8]% and an overall successrate of lJS'7c. These results are comparable to thoseof scleral buckling techniques.

The intraocular bubble works in two ways: (1)buoyancy-it pushes the retina against the reti-nal pigment epithelium. and (2) surface tension-it closes the retinal break, preventing liquidvitreous access to the subretinal space. The actionof the retinal pigment epithelial (RPE) pumpremoves the remaining subretinal fluid, therebyreattaching the retina. The gas bubble reduces aretinal detachment to its primary component, aretinal tear. Once apposed to the eye wall, theretinal tear can/be treated as one never associatedwith subretinal fluid, that is, with cryopexy orlaser. Continued apposition of the bubble to thetreated retina is maintained unti I a chorioretinalbond has formed. Once the edges of the break aresealed, eddy currents induced by eye movementwi II not dissect beneath the edges of the breakand the retina will remain attached. The retinaldctuchrnent will recur if vitreous forces on thetear exceed the chorioretinul adhesion forces orif new breaks occur.

Patient Selection

The success of pneumatic rerinopexy demandscornp liance , Patients selected for pneumaticretinopexy must be mentally and physically able {Q

follow postoperative instructions. A senile orseverely arthritic patient may be unable to rnuiruainproper positioning. Patients with chronic obstruc-tive pulmonary disease or congestive heart failuremay be unable to assume the horizontal positionnecessary to close breaks at ] or 9 o'clock. How-ever, if medically compromised patients can toleratethe positioning. pneumatic rctinopexy poses a lowersurgical risk than conventional buckling surgery.

Ocular Considerations

Pneumatic retinopexy is an intraocular procedure.Attention should be directed toward lid hygiene,active hordeolums, or conjunctivitis. Eyes thathave recently undergone intraocular surgery willhave weakened sclera. A sudden rise in intraocularpressure could rupture a fresh wound, resulting intissue prolapse. Eyes with severe glaucoma maynot tolerate, even temporarily, elevated intraocularpressure. Such eyes should be treated with othertechniques or softened sufficiently prior to injec-tion of the gas bubble. Eyes with an unstableintraocular lens may not be good candidates forthis procedure.

33

34 MANUAL OF RETINAL SURGERY-Retinal Considerations

Pneumatic retinopexy may be used to treat retinaldetachments associated with retinal breaks, sepa-rated by up to 6 clock hours (180 degrees), locatedin the upper two-thirds of the fundus. Pneumaticretinopexy has been successfully used to treat reti-nal detachments associated with mild vitreous hem-orrhage and posterior breaks, including macularholes. Although retinal breaks up to 2.5 clock hoursin size have been successfully treated with pneu-matic retinopexy, most retinal surgeons limit thistechnique to retinal breaks up to I clock hour insize. It may be used to treat retinal detachmentsassociated with mild proliferative vitreoretinopathy(PYR) with star folds present in up to two quadrantsof the retina (PYR C~). as long as the star folds donot exert direct traction on the retinal breaks. Thisprocedure should not be used for detachments asso-ciated with inferior breaks located between 4 and 8o'clock. Eyes that demonstrate severe vitreoretinaltraction. have extensive lattice degeneration (greaterthan 3 clock hours). or whose fellow eyes have sus-tained a giant retinal tear may not be good candi-dates. However. a very limber, motivated patientwith a break at 5 or 7 o'clock may be adequatelypositioned and treated with pneumatic retinopexy.

Pneumatic retinopexy requires that all pathologicconditions be identified prior to injection of the gasbubble. The surgeon relinquishes the comfort of theoperating room environment, where a relaxed.sedated patient with an open conjunctiva mayundergo deep scleral depression. Inadequate visual-ization of the peripheral retina because of a poorlydilated pupil. media opacities, pseudophakia, orperipheral secondary capsular opacities may resultin failure to detect a small break. resulting in fail-ure of the retina to reattach.

Bubble Characteristics

The application of pneumatic retinopexy requiresan understanding of intraocular gas expansion andgeometry. The gas most frequently used is sulfurhexafluoride (SF6). Perfluoropropane (C3Fs or PFP)is used occasionally. Both gases are inert, have poorsolubility in water. and due to their high molecularweight, diffuse poorly out of the eye. Once the gasis injected into the vitreous cavity, osmotic forces

draw in nitrogen and oxygen, expanding the volumeof the gas bubble. A 0.3-cc injection of 100% SF6will increase in size 2.5 times (i.e., to 0.75 cc)within 48 hours, while a 0.3-cc injection of 100%PFP will quadruple its volume (i.e., to 1.2 cc) in 72hours. The greatest expansion of both gases occurswithin the first ] 2~24 hours. The SF6 bubble usu-ally persists 10-14 days, while the PFP bubbleshould last 4-6 weeks. A late rise in intraocularpressure owing to gas bubble expansion has notbeen reported. This is because the gas bubble actsas "internal tonography" and eyes with a relativelynormal outflow facility compensate well. A poten-tial problem might exist in eyes with glaucoma sec-ondary to severely compromised outflow facility.These eyes may be treated with paracentesis as wellas carbonic anhydrase inhibitors for a few days fol-lowing the procedure.

Intraocular Bubble Geometry

In an ernrnetropic eye, a 0.3-cc bubble will subtend1 clock hour of peripheral retinal arc. Much moregas is required to cover greater areas of retinal arc.A 0.8-cc bubble is necessary to subtcnd :2 clockhours at the equator. while a 2.4-cc bubble will sub-tend 6 clock hours (Figure 5-1).

Bubble Selection

Selection of the gas depends on the eye's facility foroutflow and the size, location. number of retinalbreaks, and existing vitreoretinal traction forces. AO.I-cc injection of 100% PFP will expand to 0.4 ccover 3 days. This may be adequate to treat a smallretinal break. However. if the break is larger. an ini-tially small gas bubble may not close the break andcould even pass through the retinal break into thesubretinal space.

If there are several breaks several clock hours apart,a longer-acting bubble may be necessary to close thebreaks sequentially or alternately. h is not necessaryfor a single bubble to treat all pathologic findingssimultaneously (see section "Postoperative Care").

The degree of vitreorctinal traction must be con-sidered. If significant vitreorctinal traction exists.bubble-break apposition may be necessary for sev-eral weeks, that is, until the choriorciinal scar has

1 hr.

0.3 cc

2 hrs.

Figure 5-1. Bubble size versus arc of contact (errunetropic eye),

0.8 cc

firmly evolved. Under such circumstances, alonger-acting bubble would be required. If thedetachment is due to an atrophic or operculatedhole with little residual v itreoretinal traction, ashorter-acting bubble is satisfactory.

Surgical Technique

The procedure may be done in the office examin-ing chair, an outpatient facility, or rarely in the oper-ating room (Table 5-1). Anesthesia is obtained bysubconjunctival or peribulbar injection. Retrobul-bar anesthesia is not necessary.

Light peripheral laser photocoagulation isapplied to attached retina between the insertion ofthe vitreous base and ora serrata (Figure 5-2A).Cryopexy is applied to the teur(s) (Figures 5-2A and5-3A) unless the "steamroller maneuver" is antici-pated (see the following section). Cryopexy can beomitted and laser (delivered with the laser indirectophthalmoscope using scleral depression) applied afew days later/ when the break has flattened (seeFigure 5-2C). However, photocoagulation can bedifficult in a partially gas-filled eye. Visibility islimited and care should be taken not to overtreat theretina with laser in areas in contact with gas. With-out the "insulating effect" of the liqu id vitreous,thermal burns can be excessive, resulting in retinalnecrosis and hole formation.

A lid speculum is inserted and five drops ofpovidone-iodine (Betadine solution) are instilledand left in place for 3 minutes. The conjunctiva isthen dried. A paracentesis (0.2-0.3 ml) is performed

Pneumatic Retinopexy 3S

6 hrs,

2.4 cc

now, with a 27 - or 30-gauge needle on a plunger-less syringe, before gas bubble injection. The exactvolume of gas (0.3-0.5 cc) to be injected is drawnthrough a millipore filter into a 1- or 3-ml syringe.With the patient supine, the head is turned 45degrees to the opposite side so that the needle isperpendicular to the sclera (avoiding the lens) andpoints inferiorly toward the center of the globe anddirectly toward the tlOOL The sclera is perforatedwith a 27 - or 30-g~luge, I{z-inch needle 3-4 mmfrom the limbus, preferably away from highlydetached retina or large open retinal breaks. Do notinject where the pars plana epithelium is detached.Once the needle is in the vitreous cavity, it is pulledback so that only 2 mm of the tip is in the eye. Theentire gas volume in the syringe is briskly injected.This permits injection of gas into the forming bub-ble so that a single bubble is created around the nee-dle tip (Figure 5-3B). As the needle is withdrawn,a cotton-tipped applicator is placed over the perfo-ration site and the patient's head is rotated to pre-vent gas from escaping through the sclerotomy. Ifthe bubble is in the vitreous cavity, it will move tothe most superior position in the eye. If the bubbleis anterior to the anterior hyaloidal face, it will notmove as the head is rotated and will appear oval. Ifit is under the retina, the bubble will look like awhite, round pearl mobile in the subretinal space.

If multiple bubbles are present, the eye can be"flicked" with the index finger or a COlton-tippedapplicator, which will force the bubbles to coalesce.The head should be turned 45 degrees to the oppo-site side so that the bubbles are positioned at thepars plana, away from the retinal breaks. That area

- 36 MANUAL OF RETINAL SURGERY

Table 5-1. Brief Summary of Protocol

A. Preoper-ative1. Dilate pupil2. Subconjunctival anesthesia

B. Operative1. Patient supine.2. Laser 10 periphral attached retina.3. Transconjunctival cryopexy of retinal break: defer

if steamroller technique is contemplated or ifplanned laser to peripheral retina when attached.

4. Place eyelid speculum.5. Treat conjunctiva with 5 or 6 drops of povidone-

iodine (Betudinc solution) and wait 3 minutes.6. Paracentesis.7. Dry injection site 3-4 mm posterior to limbus

with cotton-tipped applicator.8. Briskly inject 0.3 cc sterile (Millipore filter) perflu-

oropropane or 0.5 cc sulfur hexafluoride gas with atie-inch 30-gaugc needle through uppcnnost parsplana with needle pointing toward the floor.

9. Cover conjunctival perforation with sterile cotton-tipped applicator as needle is withdrawn. and turnhead to move gas bubble away from injection site,

10. Observe central ret inal artery. If the artery isclosed. wait up to 10 minutes. If artery docs notstart 10 pulsate. usc paracenlesis.

I I. Steamroller technique. if indicated. is performednow.

I~. Continue to monitor central retinal artery andintraocular pressure (applanation) until the arteryis parent and nonpulsatile. Apply cryopcxy ifsteamroller technique was used.

13. Apply topical anubiotic and eye pad with aITOWdrawnfor positioning.

14. Administer acetazolamide (Diarnox) ~50 rng fourtimes daily if patient has glaucoma or will driveto a higher altitude. not exceeding 4.000 feet.

C. Postoperative

1. Instruct patient La position head so that the retinalbreak is uppermost (to position the gas bubble atthe break site) for 16 hours a day.

2. Examine in office on first postoperative day. Dis-coruinue use of eye pad.

3. Prescribe topical antibiotic and steroid solutionfour times daily.

4. Continue head pnsilioning for 16 hours a day for:; days. Patient may sleep 011 side for R hours eachnight but should not sleep on back.

5. Follow-up examinations at I and 3 days. and at I.2.4. R. 16. and 26 weeks.

6. Patient can return to work 3-4 weeks after surgery.

should then be "flicked" through the eyelid. [f thisis not successful, the patient should rCI11:!in in aposition to keep the small bubbles away from alarge open retinal break for 24 hours. The multiplebubbles ("fish eggs") will usually coalesce over12-24 hours. If a bubble passes under the retina,massaging it toward the break and back into the vit-reous cavity can be tried with a scleral depressor. Ifthis is not successful and the bubble is small, theeye should be observed closely. If the subretinalbubble is large. it should be removed.

Immediately after the injection, {he central reti-nal artery is monitored. If the artery is closed, thetime is noted with a stopwatch to measure the dura-tion of closure. The absolute value of the intraocularpressure is not as important as the patency of thecentral retinal artery. In eyes containing gas. a 28-diopter lens provides the best view of the retina.Elevated intraocular pressure is usually nOI a prob-lem after the intraocular injection of less than 0.5cc of gas if a paracentesis has been performed. If aparacentesis has not been performed before gasbubble insertion. or more than 0.5 cc of gas isinjected, immediate elevation of intraocular pres-sure to levels between 30 and 70 mm Hg is COIll-

monly observed. but pressure usually rctur nxtoward normal within 30-60 minutes. The intraocu-lar pressure must be monitored by applanationtonometry, because Schiotz readings will be falselylow. If the central retinal artery remains nonpnrcn:and nonpulsatile 10 minutes after the gas injection.a second paracentesis is done. Removal of a ponionof the gas is rarely necessary. In phak ic eyes orthose with an intact posterior capsule. a limbal para-centesis is done. In aphakic eyes or those with anopen posterior capsule. the needle is introducedthrough the pars plana and angled into the anteriorchamber, where aqueous can be aspirated. This willavoid vitreous incarceration at the limbus. Once theintraocular pressure has returned to normal. eventhough the gas will later expand, a rise in intraocu-lar pressure has not been noted.

If the detachment is so bullous that the centralretinal artery cannot be visualized. the.patient, in asitting position. leans forward face do~n. The headis (hen rotated 50 that the gas bubble rolls nasal lyover the optic nerve. pushing the overhanging retinaaway. This will usually permit a view of the nerveand the central retinal artery.

Pneumatic Retinopexy 37

Cryopexy

Bubble

New laser

Old laser

Subretinalfluid

Fi/:ur. 5-2. A, Laser photocoagulation is first applied to attached retina between the insertion of the vitreous base and ora.Avoid placing laser bums near detached retina. Light cryopexy is applied to the edges of the retinal break. B, After Bela-dine prep and paracentesis. intravitreal gas bubble is injected. C, 24-48 hours following gas injection. the retina attachesand laser is applied. D, If a new (or missed) retinal break develops after peripheral laser (in this case at 6 o'clock), theretina will not rederach.

The Steamroller Technique

The "steamroller" technique can be used to forcesubretirial fluid back into the vitreous cavity. Themaneuver is recommended when the gas bubblemight displace spbretinal fluid beneath an attachedmacula or an attached inferior retinal break (Figure5-4)lor to prevent a macular fold (with a superiordetachment and a large bubble). It can also be per-formed to "debulk" the overall size of the retinaldetachment resulting in more rapid reattachment.The patient, in a sitting position, leans forward facedown (Figure 5-5A). Over a lO-minute period, thepatient's position is slowly changed from face downto a head position in which the retinal break isuppermost (Figure 5-58). If this maneuver is antic-ipated, cryopexy should not be applied prior to gas

injection to minimize the chances of displac ingviable RPE cells into the vitreous cavity. Althoughthere may be a potential for displacing viable RPEcells into the vitreous cavity, the PneumaticRetinopexy Clinical Trial did not show an increasedincidence of macular pucker or PYR in eyes thathad the steamroller maneuver performed.

A subconjunctival antibiotic may be adminis-tered near the injection site, The eye is patched andan arrow drawn on the patch to indicate the correctpostoperative head position (i.e., the arrow shouldbe aimed toward the ceiling). Alternatively theEscalon Pneuma Level can be used. This is aninexpensive (about $5) i-inch, fluid-filled plasticdisc containing a small air bubble with 12 clockhours printed on its face (Figure 5-6), It is affixed tothe eye patch and the head positioned so the bubble

/

31'1 MANUAL OF RETINAL SURGERY

BFigure 5-3. A, Cryopcxy is applied to the retinal break.H, The needle is perpendicular to the floor so that the bubbleforms around the needle tip avoiding "fish eggs."

lies over the desired clock hour. It greatly improvespatient compliance and is particularly useful to aidpositioni ng for breaks in the difficult 4 and 80' clock meridians. The patient and family areshown with a mirror the correct head posture to bemaintained as long as possible for the first 24-hourperiod. A postoperative instruction sheet is givenrestating the procedure, medication, instructions,restrictions, and date for return visit. The. patient is

. to use topical antibiotics four times daily, and pred-nisolone acetate drops four times daily for 10 days.For patients with glaucoma or those who will travelimmediately by car to higher altitudes (no greater

Figure 5-4. The gas bubble may displace subretinul fluidbeneath the macula.

than 4,000 feet), carbonic anhydrase inhibitors arerecommended for 3 days to minimize the chancesof an excessi ve postoperati ve pressure rise. Airtravel is avoided until the bubble completelyresorbs. The patient is usually asked to return for afollow-up examination the following day.

Postoperative Care

It has been recommended that the patient be posi-tioned so that the bubble is apposed to the retinalbreak for 16 hours a day for 3-5 days. Positioningduration depends upon the extent of vitreoretinaltraction. For example, a retinal detachment sec-ondary to a small, round break may be treated withbubble positioning until the break is flat. If there areno vitreoretinal traction forces, the RPE pump willhold the break apposed to the RPE while the chorio-retinal adhesion forms. However, in cases withextensive vitreoretinal traction, bubble appositionmay be necessary for longer periods of time.

It is not necessary for the bubble to be in contactwith all breaks simultaneously. If multiple breaks

.exist, the patient is positioned so-that the bubblecloses the most superior breaks for the first few days.Then the patient is repositioned to close the remain-ing breaks. The patient can also be positioned alter-nately during the day so that all breaks are in contactwith the bubble for a few hours each day.

Patients are examined on postoperative day l. Ifthe retina is flat, the patient returns in I week. If there


Figure 5·5. Steamroller maneuver. The patient is positioned face down (A), then slowly rotated so that the bubble rolls onthe surface of the retina toward the retinal break (B), displacing subretinal fluid into the vitreous cavity.

Figure 5-6. The Pneumo Level adheres to the eye patchand the patient is told to position his or her head so thatthe bubble is placed at a specific clock hour, in this case2 o'clock.

has been little resorption of subretina! fluid after 24hours, either an open or new break exists or thepatient has not been positioned properly. A total bul-lous retinal detachment usually flattens completelywithin a few days. Sometimes thick, turbid subretinalfluid persists inferiorly and may take several weeksto resorb. As long as the macula is attached, these aremanaged conservatively. In some cases, isolatedpockets of subretinal fluid in the midperiphery lingerfor weeks or months. These eyes should also be man-aged conservatively; the fluid eventually resorbs.

If the retina flattens within a few days, thepatient is rechecked in 7-14 days. Use of topicalantibiotics and steroid drops is maintained for 1~2weeks. The patient is then seen on postoperativedays 30, 60, 120, and 180. The patient is warned ofthe possibility of developing a new retinal breakand told to notify the surgeon immediately if newflashes, floaters, or a curtain develop.

Patients are also instructed to contact the sur-geon immediately if pain or loss of vision occurs,particularly within 24-72 hours after the intraoc-ular injection, since this may represent the onsetof endophthalmitis, which requires immediatetreatment.

If the retina redetaches while gas is still in theeye secondary to a new break in the upper two-thirds of the fundus, the patient is repositioned toclose the new break. If the bubble has absorbed oris not large enough, pneumatic retinopexy isrepeated. If the break occurs inferiorly, a scleralbuckling procedure is performed.

The patient may resume full activity 2-4 weeksafter successful reattachment but is instructed notto fly or ascend to altitudes greater than 4,000 feetuntil the bubble completely resorbs. If the patientmust undergo general anesthesia, the anesthesiolo-gist should be warned of bubble expansion andinduce the anesthesia appropriately (no nitrousoxide should be used).


Intraoperative Complications

The most serious intraoperative complication ofpneumatic retinopexy is the subretinal injection ofgas (Figure 5-7). If proper technique is followed(i.e., avoiding "fish eggs"), this complication can beavoided. If it does occur, the patient should be posi-tioned and the eye massaged to displace the bubbleback into the vitreous cavity. If the bubble is small,the patient can be managed conservatively. If alarge bubble exists' in the subretinal space, it mustusually be surgically removed.

The complication of injection of gas anterior tothe anterior hyaloid is usually easily treated byimmediately reinserting the needle through the parsplana into the affected area with the barrel of thesyringe removed. The gas will disperse passively. Anew bubble can then be injected.

Damage to the lens is possible but should notoccur if proper technique is used. Although a hemor-rhage may occur at the pars plana injection site, itusually is not significant. Central retinal artery occlu-sion is possible and must always be considered. If thecentral retinal artery is closed for 10 minutes follow-ing the bubble injection, paracentesis is performed.The patient must not be discharged until the artery ispatent and at least light perception documented. Theintraocular pressure usually returns to the mid-20swithin I hour following the injection of 0.3 cc of gas.A late rise in intraocular pressure has not been noted.

Displacement of subretinal fluid into the macula,macular folds or displacement of subretinal fluidinferiorly, elevating an inferior break, can beavoided if the steamroller technique is used.

Figure 5·7. If the gas is injected from below. "fish eggs"will always result and may pass into the subretinal space.

Postoperative Complications

The most common postoperative complication ofpneumatic retinopcxy is failure of the retina to re-attach owing to new or missed breaks. Failure ofthe retina to reattach within a few days usually indi-cates an open break. New breaks may occur imme-diately following the bubble injection, within thefirst few days, or even after several months. Thismay be due to increased traction ?r movement bythe bubble, or contraction and separation of the vit-reous. If the new break is not associated with sub-retinal fluid, it is treated with the laser or cryopexy.If the retina redetaches because of a new break inthe upper two-thirds of the fundus. the pneumaticprocedure can be repeated. Recent studies show thatif a new retinal break occurs, the overall finalanatomic and visual results with additional surgeryare comparable to conventional primary bucklingsurgery.

One case of postoperative endophthalmitis todate has been reponed following pneumaticretinopexy. There have been no reported cases ofsevere uveitis or choroidal detachment.

Case Selection and Surgical Technique

One operation success is strongly influenced by thephak ic status of the eye. the number of retinalbreaks, and the extent of the retinal detachment. Aphak ic quadran tic retinal detachment with onesuperior break carries a higher success rate than atotal pseudophakic detachment with multiple reti-nal breaks. Light peripheral laser photocoagulationbetween the insertion of the vitreous base and oraserrate may also improve the single procedure suc-cess rate by prophylactically treating overlookedsmall breaks in attached retina, or by "pretreating"retina in an area where a new break later develops(see Figure 5-2D).

A Different Philosophy

The most important parameter to judge an ophthal-.mological procedure is vision. Visual acuitydescribes how one perceives the cye chart. visiondescribes how one perceives the environment. A20/20 single operation surgical result might not be

considered a success if objects are severely dis-torted. smaller or double. Pneumatic retinopexydoes not change the shape of the eye nor interferewith the extraocular muscles: therefore it has thebest chance to restore pre-detachment vision. Sightalso returns more quickly following PR than scle-ral buckling. allowing patients to return to their nor-mal lifestyle faster. Pneumatic retinopexy (an officeprocedure) is much less costly than scleral buckling(an OR procedure). Pneumatic retinopexy may havea lower single operation success rate than scleralbuckling for some types of retinal detachments(pseudophakic, multiple breaks, more extensiveareas involved). However, several authors haveshown that a failed pneumatic attempt does not dis-advantage the eye to ultimate anatomic and visualsuccess. If final vision, patient morbidity, and costare weighed against single operation success, pneu-matic retinopexy remains a reasonable procedure totry first.

Conclusion

Pneumatic rcrinopcxy is useful for the treatment ofselected retinal detachments secondary to retinalbreaks less than I clock hour in size located in theupper two-thirds of the fundus. It has also been suc-cessfully used to treat retinal detachments sec-ondary to multiple retinal breaks separated by up to180 degrees: giant tears: posterior breaks, includingmacular holes: and detachment associated with starfolds that do not exert traction on the retinal breaks.Multiple breaks, pseudophakia, and subretinal fluidgreater than 180 degrees are negative prognosticindicators that will lower the single operation suc-cess rate. However, a pneumatic failure does notdisadvantage the eye in terms of a successfulanatomic or visual outcome. Pneumatic retinopexyoffers the advantages of minimal tissue trauma,minimal morbidity, rapid rehabilitation, and a sig-nificant reduction in cost.


Suggested Reading

Ambler JS. Meyers SM. Zegurra H. et ul. Reoperations and'visual results after failed pneumatic retinopexy, Oph-r/wlmulogy 1990:97:7X6-79().

Boker T. Schmitt C. Muugharbcl M. Results and prognostictucrors in pneumatic rcrinopcxy. Gcr J Ophthalniol199-i:3:73-7X.

Grizzard WS. Hilton GF. Hammer ME. ct al. Pncum.uicretinope xy failures. Cause. prevention. timing. andmanagement. Ophthulmolovy' 1995: 102:n9-936.

Hilton GF. Grizzard WS. Pneumatic retinopcxy: a two-stepoperation without conjunctival incision. Ophtliohnol-ugy 1986:93:626.

Hilton GF. Kelly NE. Tornarnbc PE. et al. Pneuruaricretinopexy: a cull.iborarive report of the first 100 cases.Ophrh,rllIlulog." 1987:l)-il-i):307.

Lincoff A. Half D. Ligg~[[ P. et a!' Iruravirrea! expanxion ofperfluorocarbon gases. Arch Ophthalmo! 19X():9X:I646.

Lincoff H. Coleman J. Kr~ssig I. er al. The perfluorocarbongases in the treatment of retinal detJC~m~nr. Opluhut-molog» 1983:90:5 .•6.

Poliner LS. Grand ,"(G. Shock LH. et al. N~w retinal detach-meat following pneumatic retinopcxy. Oplnhalmologv1987:9~l~):315.

Tornarnhe PE. Pneumatic rctinupcx y, SI/IT Ophthulmo!19X8:32:27Il,

Torn.unbe PE. Pneumatic rcrinopc xy: ThL' evolution of C~I;-'t.:

sclccrion ~nd surgical rcchuiquc-c-A twc] vc-yc.ir studyof 302 eyes. Transactions of the Amcruan Ophthalrno-lugic'ul Socictv, Vol. XCV. December 1997.

Tornarnbe PE. Grizzard WS. cds. Pneumatic Rrtinoprxv: r\Clinical Symposium. Westport. CT: Greenwood Pub-lishing: 1989.

Tornambe PE. Hilton GF The pneumatic rerinopcx y studygroup. Pncumutic n.:rillopexy-A rnulucenrcr random-ized controlled clinical tr ial c<)lllparin~ pneumaticr e tinopc x y with sc icral buck l ing. Oplnhulmol19/i9;96:772-783.

Tornambe PE. Hilton GF. The pneumatic retinopexy studygroup. Pneumatic retinopexy-s-A two-year follow-upstudy of the multicenter clinical trial comparing pneu-matic retinopc xy wi rh sclcrul buckling. Oplulralmo!1991:98: 1115-1123.

Tornambe PE. Hilton GF. Kelly NE. et al. Expanded indi-cations for pneumatic rerinop.uhy. Ophthol.no!I9/iX;95:5'!7,

6Anesthesia for Vitreoretinal Surgery

W. Sanderson Grizzard

In the last edition of this book I predicted that "reti-nal surgeons will also be doing more local and out-patient surgery." This certainly is true. Today, I domore than 90% of my surgery under local anesthe-sia. I have h;.JJ one inpatient in 2 ye;.Jrs. Improve-ments in general anesthesia and local sedation haveaided in this transition to outpatient surgery.Patients usually wake up quickly and quietly frommodern general anesthesia. Patients do better athome following surgery where they sleep in theirown bed and are cared for by their family. Diabeticpatients are usually able to manage their owninsulin and medical problems at home.

There are two basic approaches: (I) generalendotrachial anesthesia and (2) local infiltration ornerve block anesthesia. The two techniques blur inclinical practice. Patients receiving local anesthesiaare often sedated. and patients receiving generalanesthesia are often given periocular injections oflocal anesthetic to decrease the required depth ofgeneral anesthesia and to aid with post-operativepain management. The selection of anesthetic tech-nique is difficult for the retinal surgeon, because ofthe emergent nature of the surgery and the consul-tative nature of a retina practice. Often the patient isreferred away from his usual medical care providerand the patient's medical condition is not wellknown to the surgeon.

Techniques of local anesthetic injection havechanged over the last 10 years. The Atkinson tech-nique ("looking up and in") has fallen into disfa-vor. Peribulbar anesthesia involving larger volumes

of anesthetic injected away from the globe is nowthe most commonly used approach. Minimalisttechniques involving topical anesthesia. subcon-juncti val injections, and posterior irrigation havebeen proposed to di minish the risk of local anes-thesia. Bupivucaine (Marcai ne ) is now the mostcommonly used agent allowing blocks of muchlonger Juration. New drugs for general anesthesiaand new monitoring devices have. likewise,become available.

Patient Selection

No one anesthetic technique is right for everypatient or every operation. Over the years I havedeveloped prejudices about which patients will dowell with local anesthesia or local anesthesia sup-plemented by intravenous sedation. I have devel-oped a scoring system to select patients for localanesthesia (Table 6-1). Patients with a score ofgreater than three usually do better with generalanesthesia or general anesthesia supplemented withlocal injection.

Numerous factors influence the selection of ananesthetic. Which procedure is being done? Howcooperative is the patient? How familiar is the sur-geon' with the operating environment and the oper-ating room personnel? As more experience isacquired, it is possible to raise your threshold score.After a few bad experiences, however, it may bewise to lower it for a while.

43


Table 6-1. Scoring System to Select Patients forLocal Versus General Anesthesia .

Factor PointsProcedure

Pneumatic retinopexy 0Primary scleral buckling I"Easy" revision of buckling 2Diflicult revision elf buckling 3Simple vitrcctomy 2Vitrccroruy with preretinal membrane 2

removal or macular hole surgeryVurcctomy for cndophthalrnitis 3Vitrectorny for proliferative 4

vitrcorctinoputhy (PYR) or proliferativediabetic retinopathy

Patient FactorsUnder age 60 IUnder age 40 2Male ITrouble with previous local eye surgery 2Could not tolerate retinal examination with ::

scleral depressionHigh myopia 2Prefers general .mc stheric 2Severe cardiac or respiratory disease -2Patient just ate -2

Operating Room CunditionsInexperienced crew in operaung room IExcellent anesthetic department I

Operating at unfamiliar hospital 1Teaching situation 2Surgeon ju'sl out of fellowship 2

Vitrectomy and primary scleral buckle proce-dures can usually be done with local anesthesia.Vitrectomies can be done with local anesthesiamore easily than a scleral buckle, Complex vitrec-romies combined with scleral buckling may needgeneral anesthesia or general anesthesia supple-mented by periocular anesthetic injection. Endoph-thalmitis is a special situation because it is difficultto gel ,1 good block if there is orbital inflammation(see the section in this chapter on pharmacology).If only a tap with injection of antibiotics is neces-sary local injection may be adequate. If vitrectornyis going to be part of the management strategy, I.find that general anesthesia is frequently necessaryand should be available if a local block fails.

The most important "patient factors" are age andthe ability to undergo a good retinal examination in

the office. Young patients who are squeamish dur-ing scleral depression are best treated under generalanesthesia. Older patients who have previously hadcataract surgery are excellent candidates for localanesthesia,

The environment of the operating room is alsoimportant in selecting which technique to use. Sur-geons who are just out of training or who are in anew hospital may prefer to have the patient asleep.Operating room personnel who re;;pond, "What'sthat?" when asked for every instrument can makean experienced surgeon wish that the patient wereasleep. It is also much easier to teach when thepatient is asleep!

In summary, patient selection for local anesthe-sia is an art. We have all found ourselves in a situa-tion where we wished we had made the otherchoice. Table 6-1 and a little experience will, it ishoped, minimize those situations.

Anatomy

To safely provide regional anesthesia for ocularsurgery, it is necessary to have a thorough knowl-edge of orbital and periorbital anatomy and tounderstand the anatomic changes that take placeduring ocular movement.

The anterior orbit is occupied by the eye. whichgeometrically is a modified sphere or two mergedspheres, one in front of the other. The emmetropiceye has an anteroposterior diameter of approxi-mately 24 mm and a vertical diameter of 23 rnrn. Inmyopia, the eye is larger with a more elongated.ovoid shape. In eyes with more than 4-diopters ofmyopia, the axial length varies from 26.7 to 31.0mrn. A line joining the medial and lateral orbitalmargins will have a third of the eye anterior to it.The lateral orbital rim is more posterior than themedial orbital rim. The equator of the eye is gener-ally at, or slightly anterior to, the lateral orbital rim.The eye is closer to the roof of the orbit than to thefloor and the frontal bone overhangs the eye, mak-ing the inferoternporal approach the most openaccess to the retrobulbar space.

The concept of a well-defined muscle coneformed anteriorly by the coronal circumference ofthe eye and posteriorly by the rectus muscles with awell-developed intermuscular septum has beenshown to be not only a simplification but inaccu-

rate. Anteriorly, there are well-formed connectivetissue septa connccring the ocular muscles; posteri-orly. however, the intermuscular septum becomesless well defined and more complex connective tis-sue septa appear. Two poorly septated areas in theorbit. one lateral to the optic nerve and the otherabove the superior ophthalmic vein hammock,account for the high success rate of both retrobul-bar and peri bulbar anesthesia. The lateral rectus andinferior rectus muscles are in close proximity to theorbital wall. A large extraconal space does not existeither temporally or inferiorly.

The optic nerve, the cranial motor and sensorynerves. and the arterial circulation to the eye enterthe orbit posteriorly. Although a well-defined annu-lus of Zinn or common tendinous ring does notexist. it is convenient to think of three posterioropenings: (1) the superior orbital fissure superior tothe tendinous insertions, (2) the superior orbital fis-sure inferior to the tendinous insertion, and (3) theoptic foramen.

Through the optic foramen and the optic canalthat lie within the lesser wing of the sphenoid bone(S8) pass the optic nerve (ON) and the ophthalmicartery (OA) (Figure 6-1). After the optic nerveenters the orbit through the optic canal, it coursesanteriorly for about 30 mm before entering the eye.The distance from the optic foramen to the temporalorbital rim has been evaluated and found to beextremely variable. Although the mean is 50-51mm. the range extends from 45-58 mm.

Accompanying the optic nerve is the main vascu-lar supply to the orbit and eye, the ophthalmic artery.This artery is the fi rst intracranial branch of thecarotid artery. sharing the dural sheath with the opticnerve while in the optic canal. On exiting the canal, itcourses laterally giving off the central retinal arteryand then crosses superiorly over the optic nerve giv-ing off its branches, the lacrimal artery, the posteriorethmoidal artery, the long and short posterior ciliaryarteries, and the branches that course anteriorly.

The sensory nerves to the eye, orbit, and lids arebranches of the trigeminal nerve. The lacrimalnerve (LN), the frontal nerve (fN), and the nasocil-iary nerve (NCN) are branches of the ophthalmicdivision and enter the orbit through the superiororbital fissure (superior to the tendinous insertions),as shown in Figure 6-1. The tendinous ring is notwell formed, particularly temporally, where themotor and sensory nerves enter the orbit.

Anesthesia for Vitreoretinal Surgery 45

Figure 6-1. 58. sphenoid bone; ON, optic nave: TN,trochlear nerve; FN. frontal nerve; LN, lacrimal nerve:OA, ophthalmic artery: NCN. nasociliary nerve: AN •abducens nerve: OrviN. oculomotor nerve; SOY, superiorophthalmic vein: JOV. inferior ophthalmic vein; Inn.lateral rectus muscle: inn, inferior rectus muscle; mrrn,medial rectus muscle.

The frontal nerve and lacrimal nerve are the mostsuperior structures in the orbit and are just below theperiorbita. The frontal nerve courses anteriorly andmedially, branching into the supratrochlear (STN)and the supraorbital nerve (SON), as shown in fig-ure 6-2. The supratrochlear nerve courses anteriorly,exiting the orbit just above the trochlea of the supe-rior oblique muscle; it supplies the skin and con-junctiva of the medial part of the upper lid and asmall pan of the skin of the upper forehead and nose(Figure 6-3). The supraorbital nerve courses abovethe levator muscle anteriorly, exiting the orbitthrough the supraorbital notch. The supraorbitalnerve supplies the forehead and scalp and the skinand conjunctiva of the middle upper eyelid. The LNcourses laterally, superior to the lateral rectus muscleon its way to the lacrimal gland. It innervates thelacrimal gland and the conjunctiva and skin of thetemporal pan of the upper and lower lids.


Figure 6-2. LN, lacrimal nerve; ZN, zygomatic nerve; ZFN. zygomatic facial nerve; ION, infraorbital nerve; SON, supra-orbital nerve; STN, supratrochlear nerve; NCN, nasociliary nerve; EN, ethmoidal nerve; srrn, superior rectus muscle; sorn,superior oblique muscle; mrrn, medial rectus muscle; irrn, inferior rectus muscle; iom, inferior oblique muscle; lrrn, lateralreclus muscle; lrn, levator muscle.

The NCN enters the orbit with the other branchesof the ophthalmic division (Figure 6-1). It then entersthe muscle cone and runs above the optic nerve, giv-ing off a branch to the ciliary ganglion and the twolong, posterior ciliary nerves (Figure 6-2). It thencourses nasally to the medial orbital wall, giving offthe ethmoidal nerves (EN) and becoming theinfratrochlear nerve (lTN). The ciliary ganglion lieswell back in the orbit, lateral to the optic nerve, andreceives the preganglionic, parasympathetic fibersfrom the inferior branch of the oculomotor nerve.The short ciliary nerves are given off by the ciliaryganglion and enter the globe posteriorly around theoptic nerve. The afferent sensory supply from theglobe courses through the short and long ciliarynerves, as do the sympathetic and parasympathetic

innervation to the pupil. Good anesthesia to thenasociliary nerve, therefore, results in pupillary dila-tion from parasympathetic blockage.

The maxillary division of the trigeminal nerveexits the middle cranial fossa through the foramenrotundum and transverses the pterygopalatine fossa,where it gives off the posterior superior alveolarnerve to the posterior superior teeth. II then gives offthe zygomatic nerve (ZN) and becomes the infraor-

. bital nerve (ION) as it enters the orbit through theinfraorbital fissure and travels through the maxillarybone in the infraorbital canal to exit the skull throughthe infraorbital foramen. The ZN travels along theinfraorbital fissure and gives off two branches, thezygomaticofacial (ZFN) and the zygomaticotempo-ral (ZTN) nerves, which supply afferent sensory

Anesthesia for Virreoretinal Surgery 47

SON

STN

ZTN

LN ITN

ION )~\ ---

ZFN

Figure 6-3. SON. supraorbital nerve; ZTN. zygomatic temporal nerve; LN. lacrimal nerve; ION. infraorbital nerve: ZFN.zygornatic facial nerve; STN. supratrochlear nerve; ITN. infratrochlear nerve.

nerves to the lateral aspect of the upper and lower lidand conjunctiva. There are also deep pain fibers inthe inferoternporal aspect of the orbit supplied bythese nerves, which must be blocked for scleralbuckling procedures (see Figure 6-2).

Inferiorly and nasally in the superior orbital fis-sure. the upper and lower divisions of the oculomo-tor nerve (OMN) (motor nerves to the levator,superior rectus [srrn], medial rectus [rnrm], inferiorrectus [irm], and inferior oblique, and the abducensnerve (AN)-motor nerve to the lateral rectus[lnh)) enter the orbit from the middle cranial fossa(see Figure 6-1). The trochlear nerve enters superi-orly in the superior orbital fissure (see Figure 6-1).

During changes in gaze. the structures within theorbit undergo rapid changes. The eye, if it is spher-ical, rotates around a central point but does not havesigni ficant lateral or vertical motion. The rectusmuscles are fixed posteriorly by their tendinous ori-gins and anteriorly by their functional insertion inthe coronal, equatorial plane of the eye. The con-cept of "presenting the cone" by having the patient

look away from the needle is a geometric impossi-bility. The position of the cone does not move.What does move are the structures within the cone.A 30-mm intraorbital portion of the optic nerve isneeded to accommodate eye movement. The otherintraconal structures also must move because theyare held in place relati ve to the optic nerve by athree dimensional net of connective tissue.

The Atkinson position for retrobulbar injection(i.e., "up and in") causes the optic nerve to bebrought inferotemporally and held in a positiondirectly in the path of the needle (Figure 6-4A).Likewise, if the eye is not spherical but ovoid, asoccurs in myopia. the posterior pole of the eyemoves inferiorly toward the oncoming needle. It ismuch safer to maintain the eye in the primary gazeposition and direct the needle to a point behind themacula (Figure 6-4B). If one is injecting superiorly.it is unwise to have the patient look down for thesame reason. The ciliary ganglion and the nasocil-iary nerve sit superiorly near the optic nerve andmove with it. This accounts for the higher success


A

8

Figure 6·4. A, Atkinson position for the retrobulbar injec-tion (""up and in") endangers the optic nerve. B, Maintain-ing the eye in primary gaze position is safer.

rate when using the Atkinson technique, but theoptic nerve position accounts for the attendant highincidence of optic nerve complications,

It is important to remember that the brain stemsits just behind the orbit and is separated from it bythe sphenoid bone and dura. The optic canal and thesupraorbital foramen allow passage of arteries,veins, and nerves from the middle cranial fossa tothe orbit. The barrier between the brain and theorbit is not impermeable. If the anesthetic passesthrough the dura of the optic nerve such that allvision (no light perception) is lost, the anestheticalso will pass through the dura into the brain stem.

Needle perforation of the optic nerve is not ncccs-sary for central nervous system effects.

Pharmacology

Local anesthetics are drugs that interrupt nerve con-duction by interfering with the propagation of thenerve action potential. Nerves at rest are polarizedwith sodium ions in excess outside the membrane.As the membrane is stimulated there is an influx ofsodium into the cell and an outflow of potassium.The shift in ions causes formation of an actionpotential of 50-90 mY that is propagated along theneuron.

Local anesthetics interfere with this excitationprocess by displacing calcium ions from their bind-ing sites, so that changes in membrane permeabilitydo not occur and the membrane is not depolarized.Thus, the threshold potential cannot then be reachedand there is no propagation of the impulse.

Local anesthetics are grouped into two categoriesby chemical structure: the esters and the arnincs. Theesters (such as procaine) were commonly usedbefore 1940 but have been largely replaced by theamines (such as lidocaine), Amine salts arc morestable and water soluble than the bases. so the localanesthetics we use come in solution as salts. To beactive they must revert to their uncharged form-e-thebase. The percentage of the base form is determinedby the pH of the tissue and the pKa of the salt. Ininflamed tissue, the pH is lower so that there is lessbioactive form available in the tissue. Repealedinjection into the tissue to augment the block furtherlowers the pH, making matters worse. In severelyinflamed tissue, such as occurs in endophthalmitis, itis best to be prepared to convert to general anesthe-sia. Etidocaine (Duranest) may be the best drug forthis situation since its pKa is 7.7 and 33% of it is inthe active form at pH 7.4.

Table 6-2 briefly reviews concentrations,dosages, and duration of action of commonly usedophthalmic drugs. Lidocaine (Xylocaine), the mostcommonly used local anesthetic, has a duration ofaction that is marginally adequate for retinal proce-dures. Bupivacaine (Marcuine) has become thestandard because of its longer duration of action.Because it has a slower onset of effective molar andsensory block, many surgeons mix it with lidocaineto get a more rapid onset of action. Eiidocainc is

Table 6-2. Commonly Used Ophthalmic Anesthetics

Drug Concentration (%)

I24

0.50.75

lor 1.5

Lidocaine(Xylocaine)

Bupivacaine(Marcaine)

Etidocaine(Duranest)

Anesthesia for Virreoretinal Surgery 49

MaximumDose (rng)

3003002001503060

MaximumVolume (rnl)

30155

304"4"

Durationof Block (min)

90

ISO

ISO

" Denotes xpcciric retrobulbar dosage recommendation by drug manufacturers; others are for peripheral nerve block.

less popular because of its prolonged motor blockand increased cost. but it may offer some advan-tages. such as decreasing postoperative eye move-ment and being more effective in low pHenvironments.

Bupivacaine h;\s been implicated as causing re-spiratory arrest when used for retrobulbar injec-tions. In my opinion. it is no more dangerous at thedoxagcx used in ophthalmology than are other anes-thctics. The C;lSCS of cardiac arrest caused by bupi-vucainc during epidural anesthesia involved muchlarger volumes of anesthetic. which may have adirect cardiac effect.

Epinephrine can be added to local anesthetics toprolong their action by 50-100%. This is necessarywhen performing scleral buckling with lidocaine.but is not generally necessary when using bupi-vaca ine and etidocaine. I prefer not to usc it be-cause of potent ial systemic and local reactions.Hyaluronidase (Wydase) is also frequently added toretrobulbar injections to promote a more rapid dif-fusion of anesthetic. This practice has fallen intodisuse in all other branches of surgery and I havediscontinued using it without any noticeable effect.I know of one patient who had a severe allergicreaction to Hyaluronidase and lost the eye.

Needles

number of facets on the bevel edge. and the thick-ness of the shaft (Figure 6-5).

Long needles. both the II/~-inch (37-0101) nee-dle and particularly the l-inch (50-mm) needle givebetter blocks because they reach into the apex of theorbit. where the nerves and vesse Is' are crowdedtogether. This same advantage becomes a disadvan-tage because damage to the apical structures. orbitalhemorrhage. and inadvertent injection into the opticnerve and brain stem arc marc likely with longerneedles.

Many complications of retrobulbar injectionhave been attributed to the usc of a sharp needle. Inmy opinion. most of these complications were due

Tip

Bevel edge

Bevel face

I use a sharp. 27-gauge, 1'/4-inch (32-mm) dispos- --- Shaft surfaceable needle. There is controversy concerning whichneedle is best. I believe that blunt needles causemuch greater pain and are not safer than sharp nee-dles. Sharpness is determined by many factors; theangle of the tip, the angle of the bevel face, the Figure 6-5. Components of a needle.


to inappropriate technique (the Atkinson position ofgaze) or long needles. Ocular penetration, opticnerve penetration, retrobulbar hemorrhage, and cen-tral nervous system effects have all occurred fol-lowing the use of a blunt needle.

The theoretical advantage of a blunt needle isthat it requires more force to penetrate a tissue;therefore, it will be easier to detect the resistance ofsclera or optic nerve dura. The other supposedadvantage is that the optic nerve and sclera willslide away from the oncoming blunt needle. Unfor-tunately, this increased resistance caused by theblunt needle is more difficult to detect because ofthe greater preload caused by the blunt needle(Weber-Fechner law). The fibrous framework of theorbit that attaches to the eye and optic nerve doesnot allow them 10 move out of the way, as has beenproposed. The true situation in the orbit is analo-gous to a full pickle jar, not a nearly empty one.

The main advantage of a sharp needle is thatheavy premedication is not necessary in mostpatients. This is important if there is no anesthesiol-ogist available. J also believe that if one uses asharp needle one will be more careful when placingthe needle and doing the block. The most danger-ous situation is a nonophthalrnologist with a long,bl unt needle who thinks ocular penetration andoptic nerve damage are impossible.

Premedication and Monitoring

I prefer that my patients not receive heavy premed-ication before the anesthetic injection. I particularlydo not like 10 have the patients put to sleep withshort-acting barbiturates or propofol (Diprivan) sothat 1 can give them a local injection. A knowledge-able, competent, and reassuring staff is the best pre-operative sedation. If the patient is particularlyanxious, mild preoperative medication may be help-ful. With patients experiencing severe anxiety, itmay be better to consider general anesthesia. Intra-venous midazolam (Versed) or propofol (Diprivan)can be given for sedation if necessary but thepatient must be carefully monitored. Its usc hasbeen associated with respiratory depression and car-

. diac arrest. I always consider it wise to have trainedanesthesia personnel monitor the patient duringsurgery because of the potential for cardiac and res-piratory arrest.

Monitoring devices available should include ablood pressure cuff, a cardiac monitor, and a devicefor measuring oxygen saturation (pulse oximeter).The pulse oximeter is ideal for detecting respiratoryinsufficiency before it results in cardiac arrhythmiaor arrest. Unfortunately, in awake patients it cansometimes be difficult to keep it functioning prop-erly. I do believe that the patient should be observedclosely following a retrobulbar injection. Electronicmonitoring is not necessarily indicated, but thepatient should not be left unattended.

Technique

Several different anesthetic "cocktails" are in cur-rent use and come and go in popularity. J prefer 10

use as simple a mixture as possible. Table 6-3reflects my recent experience. J generally use bupi-vacaine or bupivacaine mixed with lidocaine. Themotor block may be delayed with bupivacainealone, but the sensory block is usually adequate forretinal surgery. The postoperative analgesia frombupivacaine is very helpful, particularly for outpa-tient surgery. The drugs are inexpensive.

Start the block by raising a skin weal with asmall amount of the anesthetic mixture and thenfollow by doing a retrobulbar injection using 4-5ml of the anesthetic with the eye in primary gaze.A sharp 11/4-inch (32-mm), 27-gauge needle isintroduced through the skin weal immediatelyabove the inferior orbital rim between the temporallimbus and the lateral canthus with the intention ofavoiding the recti muscles (Figure 6-6, point A).Some surgeons at this point place a finger betweenthe globe and the inferotemporal rim of the orbit [Q

"push" the globe out of harms way. When the nee-dle is advanced beyond the equator of the globe, itis directed toward an imaginary point behind themacula (see Figure 6-6, point A). Remember toinject very slowly (0 avoid discomfort 10 the patientand 10 prevent a sudden intravascular bolus if theneedle happens 10 be within a vess·el. Aspirationbefore injection to rule out intravascular placementof the needle is an added safety precaution. Next,partially withdraw the needle and inject an addi-tional 2 ml with the needle 1-2 cm below the skindirecied straight posteriorly. This is particularlyimportant when doing a scleral. buckle, hut unnec-essary for other procedures. Next, 1 instill topical

Anesthesia for Vitreoretinul Surgery 5 I

Table 6-3. Author's Personal Experience with Certain Anesthetics for Use in Retinal Surgery

Advantages

Familiar drugPrompt analgesia and motor blockEstablished safetyAdequate speed of onset for anesthesiaLong duration of actionGood postoperative anal gesia

Long duration of actionGood postoperative analgesiaPossibly safer than 0.75% bupivacainePrompt analgesia and motor blockGood postoperative analgesias

Anesthetic

Lidocaine 2%(Xylocaine)

Bupivacaine 0.75'70(Marcaine)

Bupivacaine 0.5%. (Marcaine)

Bupivacaine 0.75% mixed with 2%lidocaine or 4% lidocaine

Disadvantages

Short duration of actionNeeds epinephrine for retinal surgery

More than ..\ml exceeds dose recom-mended by manufacturer

Motor block delayedReports of respiratory arrestOnset of anesthesia delayedPoor" motor block

Practice not recommended by manufa-turer

High incidence of brain stem anesthesiain one report (Wittpcnn. et ul.; (936)

anesthetic into the conjunctival sac and then placedigual pressure on the eye. Next. I remove the 11

/4-

inch needle from the syringe and using a 5/K-inchneedle place the needle through the caruncledirected superiorly at a 45-degree angle, away fromthe globe (Figure 6-6. point B). For this part of theinjection a right-handed surgeon should stand to theright of the supine patient for both the right and lefteye. Left-handed surgeons should stand to the leftfor both eyes. Penetrate to the hub of the needle andinject 3 rn l slowly. You can see the anestheticspread along the upper lid. This approach avoids thevascular superior orbit and also avoids injectingsupero-ternporally where the superior orbital rimoverhangs the eye and makes safe injection diffi-cult. This approach blocks the frontal and supra-trochlear nerves.

I then place a Honan balloon to soften the eyeandl spread the anesthetic. If a soft eye is not criti-cal, a few minutes of ocular massage spreads theanesthetic. No lid block is necessary; this can be themost painful part of the procedure.

After the eye is draped, a lid speculum isinserted. I then inject a small amount of 0.5% bupi-vacaine (Marcaine), with or without epinephrine,under the conjunctiva. This helps with dissectionand gives good anesthesia to the conjunctiva ini-tially and more importantly at the end of the surgerywhen often the patient feels pain during closure. Ifthere is pain with the posterior dissection, local

infiltration in that quadrant with 0.5% bupivacaine(Marcaine) often solves the problem. The blunt.curved irrigation cannula can be used to irrigateanesthetic solution behind the eye (in each of thequadrants). If the discomfort comes from manipu-lating the muscles, a posterior injection may be nec-essary. Be careful doing these injections because themuscle cone narrows abruptly posterior to theglobe.

Complications

The advantage of using local anesthesia for ocularsurgery and. in particular, retinal surgery is thatpatients have so few serious complications. As withany other surgical intervention, however, certainproblems do arise.

Respiratory arrest and death have been reportedfollowing retrobulbar injection and have beenattributed to an allergic or idiosyncratic reaction tothe drug, systemic toxicity from intravascular injec-tion, or a brain stem injection through the opticnerve and optic foramen. Many of these cases havebeen the result of retinal surgery. The most probablemechanism is the latter, which can be avoided byusing proper technique and shorter needles.

Retinal vascular problems and unexplained opticatrophy following retinal surgery generally areblamed on the surgery itself and not the anesthetic.


Lateral view of needlepath for insertionpoint A

Superior view of needle pathfor insertion point B

Fi\:urc 6-6. Retrobulbar injection. Start the block by raising a skin weal with a small amount of the anesthetic mixtureand then follow with the retrobulbar injection using 4-5 ml of the anesthetic with the eye in primary gaze. A sharp \'/.-inch (32-mm). 27-gauge needle is introduced through the skin weal immediately above the inferior orbital-rim between thetemporal limbus and the lateral canthus (point A). Whcn the needle is advanced beyond the equator of th~ globe. it isdirected toward an imaginary point behind the macula. Next, partially withdraw the needle and inject an additional 2 rnlwith the needle 1-2 cm below the skin directed straight posteriorly. This is particularly important whcn doing a scleralbuckle but unnecessary for other procedures, Next I instill topical anesthetic into the conjunctival sac and then place digi-tal pressure on the eye. l then remove the I 'I.-inch needle from the syringe and using a St.-inCh needle place 'the needlethrough the caruncle directed superiorly at a 45-degree angle superiorly, away from the globe (point B). Penetrate 10 thehub of the needle and inject 3 ml slowly. You can see the anesthetic spread along the upper lid. This approach avoids thevascular superior orbit and also avoids injecting superiorly where the superior orbital rim overhangs the eye and makes

safe injection difficult.

When these problems Occur following pterygiumremoval or radial keratotomy, however, it is difficultto ignore: the: possible contribution of the retrobulbarinjection. Avoiding optic nerve penetration is easy ifone remembers to have the patient maintain primarygaze and if one uses a short needle. If retinal vascularocclusion occurs. evaluation of the optic nerve bycomputed tomography is necessary to rule out intra-nerve-sheath hemorrhage. If an intranerve-shearhhemorrhage or a dilated nerve is found. decompres-sion of the optic nerve may be beneficial.

Ocular penetration has also been reported fol-lowing retrobulbar and peri bulbar injections. It ismore likely to occur in myopic eyes because theyare larger. have thinner sclera. and are ovoid. Theovoid eye causes problems because, in the tradi-tional Atkinson position, the posterior pole of theeye is brought into the path of the oncoming nee-dle. Therefore. In highly myopic and large eyes,consideration should be given to using generalanesthesia. Blunt needles have been recommendedin this sctring: however. the thin sclera further lim-its the surgeon's ability to feel ocular penetration.

Intraocular injection of lidocaine has occurred andix not itself toxic to the retina. lntracameral xylocaineis now frequently used in cataract surgery. In onecuxc of inadvertent intraocular injection. there wasinitial loss of light perception with full visual recov-ery within 16 hours. If this happens. the eye shouldbe softened and observed for retinal vascular prob-lems. If an ocular perforation (entry and exit wound)occurs. the planned retinal surgery should be carriedout to fix the retinal detachment and to treat thenewly made retinal holes. If vitreous hemorrhageprevents adequate visualization. or if there are pos-tcrior breaks, vitrectorny may be necessary.

Retrobulbar hemorrhage is the most commonproblem following retrobulbar injection. If one usesshorter needles and primary gaze, the incidence ofthis problem i~ low because the highly vascularorbital apex is avoided.

General Anesthesia

The safety of anesthesia and our ability to monitorpatients have improved greatly. Undue fear of anes-thetic risk is no longer appropriate when one workswith a wcll-truincd anesthesiologist. In addition tothe usc of stethoscopcs. cardiac monitors, and blood

Anesthesia for Virreorerinal Surgery 53

pressure cuffs. instruments to measure expiratorycarbon dioxide. oxygen saturation. core body tem-perature. and arterial pulse pressures can be rou_-tinely used. This helps to minimize the risk ofanesthetic accidents.

There still remains the risk of allergic and idio-syncratic reactions to anesthetic agents and theproblem of medically unstable patients. Patientswho have recently experienced myocardial infarc-tion present a special problem when faced with theneed for a general anesthetic. These patients shouldbe managed with local anesthesia. Close consulta-tion with the patient, the patient's physician. and theanesthesiologist is critical in this setting. Sometimeseven urgent. sight-saving surgery should be delayedor canceled.

Another special problem that retinal surgeonsface with the use of general anesthesia is the effectthat inspired anesthetic gas mixtures have on thevolume of gas bubbles and the intraocular pressure:of the eye. The problem exists in three parts:

I. What happens dur ing anesthetic induction toeyes that already have a gas bubble in them:

2. What is the effect on a gas bubble placed duringsurgery?

3. What happens to the gas bubble in the eye afterthe anesthetic gases are discontinued?

A basic knowledge of the physics of gases is nec-essary to understand what happens and how to dealwith it.

Gases in body cavities try to establish equilib-rium with the gases in solution in the blood, so thatthe same gas mixture exists in the body cavity as inthe: blood. This is the "second gas effect." Gasmoves in both directions to establish this equilib-rium. The speed with which this occurs depends onthe molecular weight, the diffusion coefficient, andthe water solubility of the gases involved. Oxygen,nitrous oxide, and carbon dioxide are soluble andmove readily to establish equilibrium with a gascavity. Nitrogen, sulfur hexafluoride, and perfluo-ropropane are insoluble. Therefore, they remain inthe eye for prolonged periods and diffuse onlyslowly into solution to help reestablish equilibrium.

In a patient's eye, an insoluble gas bubble reachesequilibrium with the gases in the blood. When thepatient is anesthetized with a mixture of 50%. oxy-gen and 50% nitrous oxide, both of which are highlysoluble gases, rapid expansion of the bubble occurs

S4 MANUAL OF RETINAL SURGERY

with oxygen and nitrous oxide diffusing into the cav-ity. The effect may also occur, but to a lesser extent,with 100% oxygen. Careful attention should be paidto the effect on intraocular pressure of anestheticinduction and the surgeon should be prepared todecompress the eye rapidly through the limbus orpars plana with a 30-gauge needle.

Once the patient is intubated and breathing a gasmixture of oxygen and nitrous oxide, attention mustbe paid to the effect of these mixtures on gas bub-bles injected during surgery. If an air pump is used,the intraocular pressure is controlled by the pump.If air is moving through the eye, the mixture in theeye remains that of air. Once the eye is closed andmovement of air ceases, oxygen and nitrous oxidestart to diffuse into the eye. If equilibrium is estab-lished in the anesthetized state, the bubble willshrink when the patient awakens because thenitrous oxide and some of the oxygen will diffuseout of the eye. If the air is injected with a closedsystem, the bubble volume will expand rapidlywhile the patient breathes nitrous oxide and willbecome smaller when the patient breathes room air.The way to avoid these changes and their somewhatunpredictable effect is to have the patient breathe amixture as close to air as is practical. If the patientis breathing nitrous oxide, it takes about 10 minutesto wash the nitrous oxide out of the system. Try tohave the patient weaned from nitrous oxide for 10minutes before closing the system.

Combined Technique

The idea of giving both local and general anestheticmight sound bizarre at first. After using the com-bined technique for many years, I enthusiasticallysupport its use. Patients who are quite ill can toleratethe minimal anesthesia necessary for maintainingintubation. In this situation I do a subconjunctivalinjection as mentioned above and then follow withposterior irrigation of 0.5% bupivacaine (Marcaine),In all patients undergoing general anesthesia, I doposterior irrigation of bupivacaine (Marcaine)because of the excellent postoperative analgesia.

Minimal Anesthesia

Retinal surgery, particularly limited vitrectomies,can be done with a technique of topical drops fol-

lowed by subconjunctival injection and posteriorirrigation. Once the conjunctiva is opened, poste-rior irrigation using a blunt canula is carried out. Ifind this technique most useful for cooperativepatients and limited surgery.

Summary

Any retinal procedures can be done with localanesthesia, but as the surgery becomes more com-plex, the advantages of general anesthesia out-weigh the risks. The traditional Atkinson positionof gaze and use of long (greater than 11

/4 inch)needles should be abandoned. Sharp needles andslow injection make a retrobulbar injection tolera-ble for even the most pain-sensitive patients. Acombined anesthetic of retrobulbar injection andgeneral anesthesia is an excellent approach fordealing with sick patients who require long. com-plex retinal procedures.

Suggested Reading

Antoszyk AN. Buckley KG. Contralateral decreased visualacuity and extraocular muscle palsies following rctro-bulbar anesthesia. Ophllwlmol"sy I')g(':9~:·l()2.

Fanning GL. Sedation techniques. Ophrlwlmo/"gr Clinics 11North America 1998: 11:73.

Gills JP. Hustead RF. Sanders DR. Opluhalmir Allntll('5ia.

Thorofare. NJ: Slack Incorporated: 1993.Javitt IC. Addiego R. Friedberg HL. ct al. Brain stem anes-

thesia after retrobulbar block. OphrlwinlOlogy1987:94:718.

Koornneef L. Spalial Aspects of Orbital Musculo·FibrousTissue ill Mall. Amsterdam: Swers & Zeitlinger; 1977.

Lincoff HE. Sweifach P, Brodie S. et ul. Intraocular injectionof lidocaine. Ophthalmology 1985 :92: 1587.

Linn JG. Smith BR. Intraoperative complications and theirmanagement. 111/ Ophtlwlmol Clin 1973: 13(2): 149.

Pautler SE. Grizzard WS. Thompson LN. Wing GL. Blind-ness from retrobulbar injection into the optic nerve.Ophthalmic Surg 1986; 17;334.

Seelenfreund MH. Freilich DB. Retinal injuries associ'Hedwith cataract surgery. Am J Oplnhobno] 1980;89:654.

Sullivan KL, Brown GC, Forman AR. et al. Retrobulbarancsrhcsia and retinal vascular obstruction. Opillhal-mology 19113;90:373.

Unsold R, Stanley JA. DcGroot I. The CT-topography ofretrobulbar anesthesia. Gracjcs Arch cu« Ophtlutlmol1981;217:137.

Wittpcnn JR, Rapoza P. Sternberg P Jr. ct 'II. Respiratoryarrest following retrobulbar anesthesia. ()I'hrl/(llfllol(!.~y1986;93:867.

7Scleral Buckling Surgery(Cryopexy and Explants)

Andrew J. Packer

Rhegrnarogenous retinal detachments are causedby retinal breaks. usually resulting from vitreo-retinal traction. The main goals of retinal reattach-ment ~urgery are to relieve the v itreore tinaltraction and to close the retinal breaks (so thatfluid from the vitreous cavity cannot gain accessto the sub-retinal space). Once the retinal breaksarc closed. remaining subretinal flu id will beremoved by the retinal pigment epithelial "pump."In some instances of retinal detachment. vitreo-retinal traction is minimal and retinal breaks canbe treated with pneumatic retinopexy (see Chap-ter 5). At other times, severe vitreoretinal tractionnecessitates v itrectorny surgery (see Chapter 8).

Scleral buckling surgery accomplishes the goalof reattachment by indenting the underlyingsclera. choroid. and retinal pigment epitheliumwith buckling elements (i.e., solid silicone tires orsilicone sponges) to relieve mechanically the vir-reoretinal traction and approximate the edges ofthe retinal break to the underlying retinal pigmentepjthe l iurn. Buckling elements sutured to theexternal surface of the sclera are called explants,exoplants, or episcleral implants. If the sclera isdissected, the imbedded buckling material iscalled a scleral implant. The choroid and retinalpigment epithelium (RPE) in the vicinity of all ofthe retinal breaks is treated with a thermal irritant(i.e., cryopex y, diathermy, or laser photocoagula-tion) to form a permanent chorioretinal adhesion(i.e., a permanent seal) surrounding the retinalbreak. Frequently, it is necessary to drain subreti-

nal fluid in order to close the retinal breaks. Inthis chapter, the surgical technique discussed islimited to explants and cryopexy. In general, thiscombination decreases operating time, minimizescomplications, and allows easier intraoperativereadjustment of the buckle, if necessary.

As mentioned in Chapter 2, a crucial part ofthe procedure is identifying ali of the retinalbreaks, since there art: frequently more than one.The large. detailed fundus drawing should alwaysbe available in the operating room. Fundus land-marks in the drawing (such as vortex veins, reti-nal vessels, and regions of lattice degeneration)can help the surgeon to locate retinal breaks ifintraoperative rncdia problems prevent adequatevisual ization.

Preoperative Management

Once the decision is made to perform scleral buck-ling surgery, it is important that selected cases beperformed in a timely manner. "Macula-on" andrecent "macula-off' (i.e., up to 5 days) retinaldetachments should be operated upon as soon aspossible, preferably within 48 hours. Since outersegments of the retina depend upon blood supplyfrom the choriocapillaris. prompt reattachment ofthe macula (or prevention of a macular detach-ment) maximizes the chance of preserving goodvision. Chronic "macula-off' retinal detachmentscan be scheduled electively. Eyes with retinal

S5


detachments must be kept dilated (with atropine1.0% or scopolamine 0.25%) between the time ofdiagnosis and the time of the operative procedure;failure to do so may result in iritis, miosis, andposterior synechiae, which may require additionalsurgery to visualize the fundus and reattach the

retina.The choice of general or local anesthesia is

considered in detail in Chapter 6. If the surgeon(and pat icnt ) prefer general anesthesia, medicalproblems must be identified immediately so thatmedical consultation may be sought. Patients withhemoglobinopathies, particularly the sickle cellvarieties, are at great risk for the development ofanterior segment necrosis and this must be takeninto account when surgical options are considered.The fundus dra""'ings should ideally be performed.or at least rechecked. within 24-48 hours ofsurgery, since certain parameters (such as amountsof subretinal fluid or vitreous hemorrhage) maychange over time.

Patients with "macula-on" retinal detachmentsthreatening the macula are kept at bed rest untilthe surgery can be performed. Reading should be

, discouraged since saccadic eye movements can'lead \0 further ac.:cumulation of subretinal fluid.Watc.:hing a distant television is not a problemsince this requires little. if any. angular eye move-ments. Pinhole glasses also can limit extraocularmovements. The patient's head should be posi-tioned so that subretinal fluid remains away fromthe macula.

If elevated intraocular pressure is anticipatedduring surgery (i.e., large buckle required, littlesubretinal fluid to drain), patients may be treatedwith pressure lowering drops (i.e., beta blockers.or carbonic anhydrase inhibitors) or systemicacetazolamide preoperatively. Intravenous manni-101 (1 g/kg) can also be used preoperatively orintr;lOperatively. Immediately prior to surgery(30--45 minutes). three sets of cyclopentolate 1.0%and phenylephrine 2.5% drops are adminislered atapproximately lO-minute intervals. Topical antibi-otic drops are also given. Since phenylephrine10% is more likely to cause marked elevations insystemic blood pressure, its use, when necessary.-is reserved for the operating room, where betterpatient monitoring is available. Care must ofcourse be taken when dilating eyes with iris-fixated intraocular lenses.

Surgical Techniques

Opening

When positioning the patient's head (preferably on adonut-shaped pillow or a rolled towel). the chin shouldbe elevated slightly, so that the brow and the lowerorbital rim form a horizontal plane. The lid of theopposite eye is closed with tape if general anesthesia isused. If examination, cryopexy, or indirect laser pho-tocoagulation is scheduled on the contralateral eye.dilating drops should be instilled in that eye to avoiddelays ut the conclusion of the scleral buckling surgery.The lids. brow, and upper check are scrubbed with a10<7<.povidone-iodine (Bctadinc) solution. Cotton-tipped applicalOrs are used to cleanse the lashes. Adrop of 5'!'c povidone-iodine is placed in the conjuncti-val sac. The eye and lids are then rinsed with sterilewater and the periorbital area is dried with a steriletowel. Alcohol can then be used to swab the lids.

A plastic adhesive drape with iodophor on the"sticky" side can be used as a further precautionagainst infection. A horizontal incision is made inthe drape within the palpebral fissure unless a fen-estrated drape is used. The conjunctiva (includingthe fornices) is then vigorously rinsed with a phys-iologic saline solution. Adequate exposure is usu-ally provided with a lid speculum although on rareoccasions. a lateral canthotorny is needed.

A 360-degree lirnbal peritomy is usually per-formed (unless a segmented buckle is anticipated). Aradial cut is first ;nade temporally by grasping a con-junctival fold near the limbus and cutting down on itadjacent to the limbus (Figure 7-IA). The conjunc-tiva (together with Tenon's capsule) is then under-mined. using blunt Wescott scissors. and the incisionmade close to the limbus (Figure 7- J B). A more pos-terior peritomy can be performed in one or morequadrants if needed (for example. if a functioningfiltration bleb is present). The conjunctiva mustalways be handled carefully. to prevent buttonholing.especially when it is thin and atrophic; (as in elderlypatients). At this point it is a good ideato check pupil-lary dilatation and add more topical drops if needed.

Tenon's space in the four quadrants is then care-fully opened. with blunt dissection (using blunt,curved scissors, sec Figure 7-2). attempting to avoiddamage to the vortex veins. A cotton-tipped appli-cator is then used to strip the intermuscular fasciafrom the extraocular muscles. The four recti mus-

Figure 7-1. A. B, Lirnbal peritomy is performed.

Figure 7-2. Bluru, curved scissors are used to openTenon's space in th~ four quadrants.

cles are looped and traction sutures of 3-0 silkpassed beneath their tendons with fenestrated mus-cle hooks (Figure 7-3). It is important to isolate theentire muscle tendon during this step and not "split"the muscle. The oblique muscles are purposelyavoided (superiorly. the muscle hook should bepassed from the superoternporal to the superonasalquadrant, to avoid the superior oblique). Knots aretied close to the muscle and at approximately 4

Scleral Buckling Surgery (Cryopexy and Explunts) 57

figure 7-3. Recti muscles arc looped with tractionsutures.

inches away: this helps to prevent tangling withbuckle sutures later in the operation.

Muscle removal is virtually never required inscleral buckling surgery. If necessary, a double armsuture of 5-0 Vicryl with a spatula needle is passedthrough the ends of the muscle tendon close to themuscle insertion before the muscle is removed.Both needles are left on the long sutures for laterreattachment to the sclera.


The scleral surface is then examined. This is bestaccomplished by grasping two adjacent tractionsutures and pushing Tenon's capsule and conjunc-tive aside with a small retractor (Figure 7-4). Thisexamination should document the occurrence ofanomalous vortex veins, as well as regions of scle-ral thinning (scleral dehiscence) and staphyloma.

The surgeon must avoid damaging the corneaduring the entire procedure, to optimize visualiza-tion of the fundus. The cornea is periodically moist-ened with physiologic saline solution or a 1-2%methy1cellulose solution. The cornea may also beprotected with a moistened Week sponge. If thecornea becomes cloudy during the procedure, theepithelium can readily be removed with a No. 69 orNo. 64 Beaver blade. or a No. 15 Bard-Parker bladeby dragging the blade from the periphery towardthe visual axis (Figure 7 -5). It is important to avoiddamaging Bowman's membrane during this maneu-ver. A rim of intact corneal epithelium (at least 1-2mrn) should be left in the periphery, if possible.

Locotizint; Retinal Breaks

Indirect ophthalmoscopy is used to locate the retinalbreaks. usually with a 20-diopter lens. As previ-ously mentioned. it is helpful to have the large fun-dus drawing available in the operating room at thistime. A 28- or 30-diopter lens can be used if thepupil is small. The surgeon then performs scleraldepression with a moistened, colton-tipped applica-tor or instrument to localize the exact position ofthe retinal breaks on the corresponding external sur-face of the sclera. The straight (O'Conner) scleral

Figure 7-4. Retractors are used to examine the scleralsurface.

Figure 7-5. The corneal epithelium can be removed if itbecomes cloudy.

marker is particularly helpful for posterior breaks(Figure 7-6). The assistant can help the surgeon bygrasping two of the muscle sutures 180 degreesapart and rotating the eye so that the area of interestis directly opposite the surgeon.

If considerable scarring is present on the surfaceof the sclera. it can be difficult to identify a scleralmark. In this situation, a toothed forceps (0.3 mm)can be used to indent and then grasp the sclera atthe appropriate location. The grasped area can then

be marked.If the retinal break is small. just the posterior

margin need be marked. If it is large. the lateralmargins should also be included. Large "horseshoe"

Figure 7.6. Retinal breaks are marked on the sclera.

tears usually require three marks to localize the pos-terior margin. as well as the extent of the two ante-rior horns (Figure 7-7). A sterile marking pen(felt-tipped) is used on the scleral surface and theink "tatooed" with diathermy (or a disposablecautery). The localization should be checked; thiscan be readily accomplished by placing the backend of a cotton-tipped applicator on the scleral markand depressing while viewing the fundus with theindirect ophthalmoscope.

Areas of lattice degeneration usually should bemarked so that bands (or buckles) can cover theregions, particularly if retinal breaks are present andareas are treated with cryopexy,

After the retinal breaks are found, it is recom-mended that the surgeon examine the eye one finaltime by depressing the ora serrata 360 degrees in thehope of finding previously unrecognized retinalpathologic conditions. A wet, cotton-tipped applica-tor can be rolled continuously over the retinal periph-ery to ensure completeness of the examination.

ThermallHodalities

Cryopexy

Cryopexy should be performed to the regions sur-rounding each retinal break and to the areas of latticedegeneration. Contiguous freezes are applied, usuallyin a Vvshape for horseshoe tears. Treatment is usually

Figure 7·7, Marking a large "horseshoe" tear.

Scleral Buckling Surgery (Cryopexy and Explants) S9

Figure 7-8. Cryopexy is placed around the margins of thelarge "horseshoe" rears.

extended to the ora serrata for anterior or equatorialtears. For large tears, one full row of freezes is placedperipheral to the margins of the retinal break (Figure7-8). Treatment of bare RPE in the middle of largeretinal breaks should be avoided since this serves nopurpose and may cause dispersion of viable RPE cellsinto the vitreous cavity (leading to subsequentperiretinal membrane formation).

If the cryoprobe is used to indent the outer eyewall, the RPE frequently CJn be brought into con-tact with the retina. In this situation, the endpoint ofthe treatment is the instant the first whiteningappears within the retina (the foot pedal should beimmediately released at this point to avoidovertreatrnent). •

If the RPE cannot be brought into close proximityto the retina, a color change (pale yellow) frequentlycan be seen in the RPE itself; this represents an alter-native endpoint. Freezing can take place relativelyquickly in an eye with thin sclera and/or choroid (i.e.,a myopic eye). Freezing also takes place rapidly inan air-filled eye (if the treated section of the retina isin contact with the air).

Care must be taken always to sl ide the cryoprobeunder the conjunctive and rectus muscles and todirect the functioning portion of the probe againstthe scleral surface. The position of the opening ofthe protective plastic sheath covering the probemust always be checked. It is helpful to have anassistant call out temperature readings during [heprocedure, The endpoint should take place byapproximately -40°C, if [he sclera and choroid areof normal thickness. Freezes below -50°C usually


should be avoided. It is helpful to stop the proce-dure at such a point and check to be sure that thecryoprobe is indeed in contact with the scleral sur-face (and not on an extraocular muscle or lid). Thesurgeon must always be sure to view the tip of theprobe and not the shaft, to avoid inadvertent poste-rior freezing that may affect the macula or the opticnerve; this is particularly true for straight probes(refer to Figure 4-1). As mentioned in Chapter 4, itis important to allow the probe to thaw completely(with the help of irrigating fluid) before separatingit from the scleral surface to avoid the unnecessaryrisk of choroidal hemorrhage.

When the retina is highly elevated in the vicinityof a retinal break, it may be more accurate to markor recheck the position of the retinal breaks after thecryopexy has been performed, since the latter fre-quently softens the eye and allows deeper scleraldepression.

Laser

If any of the retinal breaks are present in areas ofau ached retina or in areas of shallow subret inalfluid, the indirect laser ophthalmoscope can beused to treat the retinal breaks. This can also beeffective for treating flat areas of lattice if clinicallyindicated.

Transscleral diode laser probes have recentlybeen used to treat retinal breaks during scleral buck-ling surgery though lack of widespread availabilityhas limited its use. Transscleral diode lasers havethe potential advantage of being able to functionthrough existing silicone explants.

Choice of Explant

In general, the choice of explant in scleral bucklingsurgery is influenced by the following factors:

I. Size, number, and location of retinal breaks2. Amount of vitreoretinal traction3. Aphakia or pseudophakia4. Available volume for the buckle (amount of sub-

retinal fluid that can be safely drained)5. Distribution of the subretinal fluid6. Presence of proliferative vitreoretinopathy

(PVR)7. "Geography" of the scleral surface8. Concern for choroidal detachment

Although the choice of the buckling hardware isalways based upon the previous experience of theindividual surgeon. it is beneficial for the retinalsurgeon to be as open-minded as possible to alter-native buckling techniques. This flexibility willallow for optimal results, particularly in challeng-ing cases. The buckling element can either be cir-cumferential (parallel to [he limbus) or radial(perpendicular to the limbus). The two most widelyused materials are solid silicone and siliconesponge. The solid silicone "tires" are usuallygrooved to accommodate an overlying band.

A wide variety of solid silicone bands, strips.tires, and accessories are available; several popularstyles are illustrated in Figure 7-9. Commonly usedvarieties of silicone sponge explants are illustratedin Figure 7-10. Categories of explant configurationare shown in Figure 7-11.

As a general rule, during scleral bucklingsurgery all retinal breaks need to be covered by the

!J U {I:J W40 band 20 strip 22 ("boat") accessory 276 tire

(;..

U D @~

41 strip 106 accessory 287 tire 280 tire

Figure 7-9. Commonly used solid silicone bands, strips, tires. and accessories.

505Ggrooved sponge

~onge

Figure 7-10. Examples of silicone sponge cxplarus,

buckle (or band). with the except ion of macularholes. If m;lny breaks are present and the availablebuckling volume is limited, it is necessary to designa "trim" buckle so that the intraocular pressure isnot raised to inordinate levels. Strips (4-6 mm inwidth). as well ;lS smaller tires and split sponges.can be e tfecti vc.

Encirclement (i.e .. with either a band or a 360-degree circumferential buckle) is specifically rec-ommended in the following circumstances:

I. Trcauncnt of aphakic and pxeudophak ic retinalde tach me III

") Multiple retinal breaks and/or large tears3. No retinal break found4. Preretinal membrane formation, star folds. vitre-

ous membranes. PVR5. High myopia6. Extensive drainage of subretinal fluid7. Extensive lattice degeneration8. Desire to create a permanent buckling effect

It is frequently not necessary to drain subretinalfluid; it is however, necessary to close the retinalbreaks. Buckle sutures can be temporarily tied tocheck for closure of retinal breaks without drainage.Drainage of sUbretinal fluid may also be necessaryto allow for the volume displacement required forthe buckling elements. In general, situations thattend to favor drainage include:

1. Longstanding retinal detachment (with viscoussubretinal fluid that may require long periods oftime for resorption)

2. Highly elevated retinal detachment (particularlywith elevated retinal breaks)

3. lnfer ior retinal breaks4. Presence of PVR

Scleral Buckling Surgery (Cryopexy and Explants) 61

5. Absence of a recognized retinal break6. Elderly patients (with poorly functioning RPE

"pumps")7. Eyes that cannot tolerate intraocular pressure

elevations (i.e .. recent intraocular surgery. severeglaucoma)

Radially oriented buckles are most effective fortreating single, large. posterior horseshoe tears. Thiscan prevent the posterior gaping of retinal tears("fish-mouthing") that can result with circurnfcrcn-t ial buckles. [11 addition to freestanding radialsponges, radial accessories may be placed beneathcircumferential buckles (see Figure 7- l l B) to pre-vent the fish-mouthing.

Segmental circumferentiul buckles (usually ofsilicone sponge) can be used to treat straightforwardanterior breaks .: when the pathologic condition islimited to discrete regions (i.e .. clock hours) andbuckle height is not crucial. It also can be helpful iflimited buckling volume is available.

As a general rule, solid silicone explants producebroader buckles and sponge explants producehigher indentation. For this reason. subretinal fluidneed not be drained in a higher proportion of casesin which sponges are used.

When planning a circumferential solid siliconebuckle. the following recommendations should beconsidered:

I. Bands or strips may be used to support smallretinal breaks, as well as areas of lattice degen-eration.

2. Extend the explant at least 15-30 degreesbeyond the margins of the retinal break.

3. When possible, position the posterior margin ofthe retinal break near the middle of the tire width.


A

E,

i'

Figure 7-11. Categories of explant configuration. A, circumferential silicone tire with encircling hand; II, circumferentialsilicone tire with underlying accessory; C, silicone strip with "boat" accessory; D, radial sponge with overlying encirclingband; E, circumferential sponge; F, tunnel sponge with internally threaded encircling band.

Scleral Buckling Surgery (Cryopexy and Explants) 63

3. If the posterior extent of the radial spongeapproaches the macula, use the "great toe"suture to avoid macular distortion (see following"Intrascleral Suture Placement" section).

4. Tie buckle sutures slowly (using temporary ties)to avoid excessive intraocular pressure elevation;watch the optic nerve head for arterial closure.(Paracentesis can be used to lower intraocularpressure; it is safest in phakic eyes or pseudopha-kic eyes with an intact posterior capsule.)

5. Trim radial sponges at the line of muscleinsertion.

6. Close Tenon's capsule 10 the anterior muscleinsertion (and episclera) in quadrants whereradial sponges are used.

4. Attempt to extend the buckle anteriorly to cover theora serrata to prevent anterior leakage (an anterior"gutter"); see Figure 7-12. Suture placement at theline of muscle insertion will accomplish this goal.If the posterior extent of the planned tire is inade-quate, an accessory can provide adequate posteriorcoverage, yet allow the anterior buckle suture to beplaced near the muscle insertion line. The posteriorsuture should be placed at least 3-mm posterior tothe posterior margin of the actual break.

Although it is desirable to place the circumfer-ential buckle around the greater curvature of the eye(to prevent hand migration), this can lead to vortexcompression if the band is placed too far posteri-orly. I find it best to keep the band between theeq uator and the ora serrata: this provides the bestsupport for the ever-threatening vitreous base andminimizes vortex compression.

The following recommendations pertain to theuse of radial sponges:

If a retinal break cannot be identified, it is a goodidea to encircle the eye, supporting the vitreous base.since small, unrecognized breaks are most likely 10

be present in this location. Suspicious areas in thevicinity of the vitreous base are treated with cryo-pexy. Many surgeons prefer to drain subretinal fluidin this situation. As rnc nt ioned in Chapter 2. thelocation of retinal breaks can frequently he sus-pected by examining the distribution of the subrcti-nal fluid. Suspected clock hours (for retinal breaks)should also be treated with two rows of cryopexy ifa definite retinal break cannot be identified.

It is important to realize that most retinal breakscan be fixed with a variety of explant configurations.

1. The diameter of the radial explant should be atleast twice the width of the retinal break (i.e., ifthe retinal break is 2.5 rnrn across, a sponge atleast 5 mm in diameter should be used).

') Posterior coverage is crucial: start posterior radialsutures at the posterior margin of the retinal breakand continue 2-3 mm posteriorly. If exposure is aproblem, both suture bites may be made in thesame anterior to posterior direction (Figure 7-13).

Figure 7-13. Posterior radial sutures pluccrncnt forsponges should start at the posterior margin of the retinalbreak.

Figure 7-12. Anterior "gutter" can develop if buckle doesnor coyer anterior portion of retinal break.


Geography of the scleral surface should be carefullyexamined before a course of action is chosen. Forexample, if a circumferential buckle is selected, yetwould require suture placement through (or close to)a vortex vein, a radial sponge can be chosen instead,Similarly. a radial sponge may require a verticalsuture through an area of thin sclera, and this maybe better accomplished with horizontally placedsutures for a circumferential buckle, with or withoutan accessory.

Once the buckle configuration has been chosen,the appropriate explant material should be soakedin an antibiotic solution.

lntrascleral Suture Placement

For circumferential buckles. one to two bucklesutures are usually placed in each quadrant, prefer-ably directly over the retinal breaks. In general.explant segments should be secured by at least twobuckle sutures. Suture material should be of the per-manent variety. Nylon has the advantage of allow-ing the surgeon to tie the sutures without assistance(with a three-one-one tie). Colored sutures may beeasier to find if reoperarion is subsequentlyrequired. Suture needles should be of the spatulatype (quarter or half circle). Half-circle needles areparticularly helpful for posterior suture placement.

The sclera is engaged with the tip of the needleto approximately half depth and the needle is thenpassed along the same plane for a total length of2-3 mm (Figure 7-14). Other surgeons preferlonger scleral bites (as long as 5 mm). Since sutureplacement is difficult in soft eyes, it is helpful toraise the intraocular pressure in such eyes by plac-ing cotton-tipped applicators adjacent to the globe180 degrees away.

Fixation of a rectus tendon with a toothed for-ceps for countertraction is helpful for suture place-ment. Bluish-appearing areas of sclera representthin regions and should be avoided.

Sutures are placed in a mattress fashion, accord-ing to the orientation of the buckling element. Thefree ends of the suture are held together with a Ser-refine clamp until the sutures are tied.

The distance between the anterior and posteriorbites for silicone tires should be approximately 2mm larger than the actual width of the explant. Theappropriate distance is usually printed on theexplant's packaging label. The use of accessories

Figure 7·J·t, Intrascleral buckle sutures are placed withthe needle at upproxirnately half depth.

requires modification (for exurnplc. the suggestedwidth for a No. 276 tire with underlying No. 106button is 13 mm). Buckle height can be enhancedby wider suture placement.

If a sponge explant is used. the distance betweenthe suture bites should be 1.5 times the diameter ofthe sponge.

Radial sponges can produce a "dimpling" effectthat extends posteriorly from the margin of thesponge. "Toe sutures" can be used to avoid potcn-rial macular distortion. As shown in Figure 7 -15A.the ends of the regularly placed posterior verticalmattress suture are left long and an additional scle-ral bite is taken at the posterior margin of thesponge; in Figure 7-15B, tho: ends are tied, whichlimits the posterior dimpling effect of the sponge,

If the suture is placed too deeply (penetrating thesclera, choroid, pigment epithelium, and possiblyretina) and/or fluid is noted to leak from the needletract, the tract should usually be marked and thesuture removed and placed more posteriorly. Theunderlying retina is then examined with indirectophthalmoscopy and, if a retinal brc'a'k is noted, itis treated accordingly. The indirect 'l~'ser can be use-ful in this situation if the retina is attached; cryo-pexy can also be used. Continued drainage of liquidvitreous or subretinal fluid may bestopped withshallow scleral sutures of 7-0 Vicryl, although thisis rarely necessary.

Band sutures arc placed in a very shallow fashion,to avoid unnecessary risk of scleral perforation. The

A

B

Figure 7-15. A, B, "Toe sutures' can avoid potential mac-ular distortion.

Figure 7-16. A curved hemostat can be used to placecircumferential buckling elements beneath sutures andmuscles.

Scleral Buckling Surgery (Cryopexy and Explunts) 65

anterior and posterior bites are placed approximately3 rnrn apart for a 2-mm band. One band suture isplaced in each quadrant that does not already containat least one buckle suture. When all sutures havebeen placed, buckling elements are positionedappropriately beneath the sutures and the recti mus-cles. Grooved, circumferential explants with theoverlying bands are grasped together by a small,curved hemostat that has been placed beneath thebuckle sutures and muscles (Figure 7-]6).

Drainage of Subretinat Fluid

As previously mentioned, subretinal fluid need bedrained only when retinal breaks cannot otherwisebe closed. Buckle sutures can be temporarily tied tocheck for closure of the retinal breaks withoutdrainage.

In general, it is desirable to drain subrctinalfluid:

I. Away from the retinal breaks (particularly largebreaks) to prevent drainage of liquid vitreousthrough the retinal breaks

2. Beneath the areas of maximal retinal elevation3. Beneath retinal star folds (since these areas of

the retina tend to remain elevated until otherareas of the retina flatten)

4. In the bed of the buckle (under prep laced bucklesutures)

Areas adjacent to the lateral rectus muscle arethe most desirable because of the easy accessibility.It is important to avoid areas adjacent to vortex veins(i.e., mid-quadrant), because of the higher risk ofchoroidal bleeding. Anterior drainage sites are prefer-able, again. to limit the risk of choroidal bleeding. Itis prudent to recheck the configuration of the sub-retinal fluid immediately before drainage. since thesubretinal fluid m;ly shift when the eye position isaltered and buckling elements are positioned.

The drainage site is prepared by radially orientedcuts in the sclera with J No. 64 or No. 69 Beaverblade. Diathermy to the scleral lips (using a conicaltip) can be used to open the scleral wound by lateraltissue contraction. The endpoint of the scleral dissec-tion (3-4 mm in length) is the herniation of a small,dark knuckle of choroid into the lips of the scleralwound (Figure 7-17A). If bleeding is noted from thechoroidal surface or if large choroidal vessels areseen, the site is abandoned and a new one chosen.


The choroidal surface can be readily examined withloupes or with the magnification of a 20-diopter lensusing the indirect ophthalmoscope. A preplacedsuture (of nylon) is placed in the lips of the scleralincision if the drain site is not in the bed of the buckle(Figure 7 -17B). The scleral lips are then held openwith a fine-toothed forceps (0.12 mm) and all trac-tion is released on the globe. If the intraocular pres-sure is still elevated, some of the preplaced bucklingmaterial must be temporarily removed to normalizethe intraocular pressure prior to drainage.

I favor light diathermy to the choroidal bed as aprecaution against choroidal bleeding, prior to pen-etration of the choroid and pigment epithelium witha sharp suture needle (see Figure 7-17B). Alterna-tively, a diathermy pin or 30-g:luge needle (with a90-degree bend) can be used. Penetration ispromptly stopped and the needle withdrawn whenfluid leakage is first noted. Choroidal penetrationcan also be performed with a disposable cautery orwith an argon endolaser probe. The latter techniqueis particularly useful if the retina is shallowlydetached at the planned drainage site.

After choroidal penetration. fluid can be gentlyexpressed using cotton-tipped applicators. The cot-ton-tipped applicators are placed adjacent to theglobe to take up volume temporarily and preventhypotony. It is desirable to place the drainage sitein a gravitationally dependent position. Endpointsof drainage include stoppage of fluid flow. appear-ance of pigment, or appearance of blood. If stop-page of flow is followed by a sudden gush of fluid,retinal incarceration and perforation in the drainage

site must be suspected. The overlying bucklesutures (or intrascleral mattress sutures if the drainis not in the bed of the buckle) are then tied tem-porarily with slip knots and the retina examinedwith indirect ophthalmoscopy. One observes theamount of remaining subretinal fluid and its prox-imity to the drainage site, and looks carefully forpossible complications, such as subretinal hemor-rhage, retinal breaks at the drainage site, and reti-nal incarceration (which should be treated as woulda retinal break). Again, the indirect laser ophthal-moscope can be particularly helpful in treatingthese breaks. Scleral depression is used on thebuckle and one or two rows of laser are placedaround the retinal break or incarceration.

If more fluid needs to be drained, the originaldrain site may be reopened (if it appears safe to doso) or a new drainage site selected. The originaldrainage site should never be reopened if hemor-rhage is observed at the site. If subretinal hemorrhageis seen, the head should be positioned to avoid col-lection of the blood in the macula. This, of course, isnot a concern with macula-on detachments.

An alternative technique for draining subretinalfluid can be performed using indirect ophthal-moscopy and a 25-gauge, s/ij-inch needle attachedto either a small syringe (without a plunger) or tothe foot pedal-controlled linear suction of a vitrec-tomy system. The needle is advanced Obliquelythrough the sclera (to allow self closure) avoidinglarger choroidal vessels; the bevel of the needle isturned toward the RPE (to avoid retinal incarcera-tion). Proponents of this technique prefer the con-

A

Figure 7-17. A, preparation of drainage site; B. penetration of choroid with a sharp needle.

trolled fluid egress and the simultaneous "internal"visualization.

When the drainage is completed, buckle suturesare pulled up and tied permanently. If a band isused, the ends may be joined with a permanentsuture clove hitch or a Watzke sleeve. The ends ofthe encircling sponges (or tires) may be joineddirectly (end-to-end), using a permanent mattresssuture.

While you are tying the buckle sutures. theintraocular pressure should be checked periodically.If it is elevated. the perfusion of the retinal arteri-oles (i.e .. arterial pulsation near the optic nervehead) must be checked; the arterioles should beopen at least 50% of the time. A paracentesis can beperformed if the intraocular pressure is excessivelyhigh. This maneuver is safer in phakic eyes orpseudophakic eyes with an intact posterior capsule.A 30-gauge needle is introduced over the peripheraliris (to avoid risking damage to the lens) andapproximately 0.1 011 of fluid withdrawn. A para-centesis kni fe can similarly be used. Paracentesisshould be avoided in aphakic eyes because vitreouscan be pulled to the limbal puncture site. I prefer toavoid removal of "liquid vitreous" via a pars plananeedle. since formed vitreous can be withdrawn,causing increased vitreoretinal traction.

If pressure elevation is anticipated. temporaryties can be used and the tension loosened appropri-ately. Slow. intermittent tying of the buckle suturesis frequently an effective technique for dealing withelevated intraocular pressure. As previously men-tioned, mannitol may be administered intravenously(l g/kg) for marked intraocular pressure elevation.

After the subretinal fluid is drained. fundus visu-alization may be poor; this usually results fromeither a hazy cornea or a small pupil. Miosis maybe corrected by topical drops in some instances.Epinephrine (0. I ml of I: 10.000 concentration) canalso ge injected into the anterior chamber and argonendolaser phorornydriasis used in refractory cases.Flexible iris retractors can be used in aphakic andpseudophakic eyes if visualization is crucial. Redi-recting the Iight of the indirect ophthalmoscopeupward and using a 28- or 30-diopter lens can alsohelp to see through a small pupil. If the cornealepithelium appears edematous, it can sometimes betemporarily cleared by rolling a wet and squeezed-out colton-tipped applicator over the corneal sur-face; the cornea is irrigated after the maneuver is

Scleral Buckling Surgery (Cryopcxy and Explant') 67

completed and the fundus viewed promptly. II mayalso be necessary at this point to remove edematouscorneal epithelium with a blade (as previouslydescribed).

The fundus is then reexamined to check the posi-tion of retinal breaks on the buckle. Although themargins of the retinal breaks need nOI be flat on thebuckle. the buckle element must entirely underliethe retinal break. Indentation of the buckling ele-ment (with external pressure) may aid in this evalu-ation. If the retinal breaks are not suff icient lycovered. buckle sutures may be repositioned oraccessories placed with new buckle sutures. Figure7-18 demonstrates the placement of a segment ofcircumferential sponge to the posterior margin of anexisting explant for further posterior coverage; newsutures are placed to include both explants. If aradial sponge appears to be too narrow. new bucklesutures may be placed lateral to the existing suturesand a wider sponge used after the original isremoved.

Physiologic saline solution. air. or cxpansilegases may be used to reconstitute the vitreous cav-ity after buckle sutures have been lied if the eye ishypotonus (though this is usually not ncccxxary).Injections are made through the pars plana (mea-sured 4 mm posterior to the limbus in phakic eyesand 3 rnrn posterior 10 the limbus in pseudophakiceyes) using a 3D-gauge needle. In aphakic eyes(without a posterior capsule). the injection may begiven through [he limbus. In general, physiologic

Figure 7-18. Pluccrncnt of circumferential sponge alongposterior margin of an existing explant.


saline is used when the retinal breaks are flat on thebuckle. Air or expunsile gas injections are usedwhen an intraocular tamponade is required to closean elevated retinal break over a well-positionedbudde, or if "fish-mouthing" (posterior gaping ofthe tear) occurs. Air/gas bubbles are most effectivewhen the breaks are located in the superior 8 hours,since inferior positioning of the bubble is difficultpostoperatively.

Air/gas should always pass through a Milliporefilter prior to intraocular injection. If the surgery isperformed under general anesthesia, the anesthetistshould be alerted to discontinue the nitrous oxidewhen air or gas bubbles are used, since nitrousoxide can drastically change the volume of the bub-bit: in a very short time. If an expansile gas is used,topical beta blockers and carbonic anhydraseinhibitors should be administered postoperatively.

Concluding Surgery

The buckling elements and the subconjunctivalspace arc irr ig atcd with an antibiotic solution.Tenon's ClpSUIt: should be attached to the anteriormuscle insertion or episclera with 7-0 Vicryl suturesin quadrunt-; where sponge material has been used(especially radially oriented sponges}. This specialtwo-layer closure helps to prevent sponge extrusionand infection.

The conjunctiva is closed with winged sutures of7 -0 Vinyl. incorporating episcleral tissue. Relaxingincisions and other dehiscences in the conjunctivashould be meticulously repaired to prevent buckleexposure, infection, and extrusion.

I prefer to inject subconjunctival cefazol in (20010')' as well ~ISpcribulbar steroid (Kenalog, 40 mg) atthe conclusion of the procedure. Atropine 190 drops(or ointment) and a combination antibiotic/steroid

ointment are also used. If the intraocular pressure iselevated, drops of tirnolol (0,5%) and topical car-bonic anhydrase inhibitors may be used; aceta-zolamide (500 mg) may also be administeredintravenously. As mentioned previously, pressure-lowering drops are always used when an expansilegas bubble is injected. and systemic acetazolamideis frequently used during the first 24 hours, The eyeis then patched and a protective Fox shield is tapedinto place.

A detailed operative report is particularly help-ful if postoperative problems are encountered andreoperation is required. A detailed diagram shouldbe placed in the patient's chart that shows the loca-tion and types of buckling material used, as well asthe locations of the drain sites.

Suggested Reading

Aaberg TM. Wiznia RA. The use of solid sott silicone rubberexoplants in retinal detachment surgery. Oplulta! Sw-g1976:7:98.

Charles ST. Controlled drainage of subrcrinul and choruidulnuill. Retina 19H5:5:23)-23~.

Haller lA. Lim 11, Goldberg MF. Pilot trial of trunsscler.rldiode laser rerinopexy in retinal detachrnent surgery.Arch Oplutuilmol 1993: III :952.

Harris M, Blum~nkrantz M, Wiupenn J. et al. Gel>m~lricalterations produced by encircling sckral buckles.Retinu 1987;7:1~.

Michels RG. Scleral buckling methods for rhegmatogenousretinal detachment. Retina 1986;6: I.

Regillo CO: Benson WE. Retinal Detochmcnt: Di(/gnosisand Manag~m~llt. 3rd ed. Philadelphia: Lippincott-Raven; 1998: IOO-I3~.

Wilkenson CP, Ric" TA. Michds R~rin(/I Detachment, 2nt.lcd. Philudelphia: Mosby: 1')97:537-594.

Williams GA. Aaberg TM. Techniques of scleral buckling.In: Ryan SJ. et al., ells. Retina. 20ll ed. St. Louis. MO:Mosby: 1994:1979-2017.

r;"

8Posterior Segment Vitrectomy

Gary W. Abrams and Jane C. Werner

Goals of Vitrectomy

The term vi trctt omv litcrully means to excise thevitreous. The vitrcctorn y operation. however.encompasses a wide r~nge of surgic~1 procedureswithin the postcr ior segment of the eye. In thischapter we will discuss the go~ds of and indic.u iunxfor virrcciomy and the instrurncntarion for viircc-torny procedures. We will describe the various com-ponents of ~ virrectorny operation.

The major goals of a vitrecrorny operation arelisted in Table 8-1. A single vitrcctnrny proceduremay have multiple goals.

Indications for Vit rect orny

The major indications for vitrcctorny arc listed InTable 11-2. Nonre solving vitreous opacities are offour basic types: hemorrhagic. inflammatory. meta-bolic. and neoplastic. Hemorrhage may result fromdiabetic or other proliferative retinopathies, retinal

Table 8-1. Major Goals of Vitrectorny

Clear the mediaRelieve vitreorcunal trucriun

lrucrnal treatment of retinal breaks and retinal detachmentDiagnosisTreat infection

Remove foreign or unwanted material from the eyeTreat macular disorders

tCHS. trauma. intraocular surgery. subarachnoidhemorrhage. avulsed retinal vessels. ocular rumors.and disciform processes. lnflarnrnutory debris mayresult from various types of uveitides. The mostcommon metabolic vitreous opacity is primary sys-temic or localized oculur nrnyloidos is. Lur g c celllvmphoma is the ll10st common cause of ncoplasricvitrcoux opacific.u ion.

The most common prul ifcrut ivc retinopathy isdiabetic retinopathy. Other proliferative retinopathiessometimes treated with vitrcctorny arc branch or cen-tral retinal vein occlusion. sickle cell retinopathy,Eulcsx disease. and other forms of vasculitis andobstruciivc retinopathies. Surgical indications for theproliferative retinopathies are usually long-standingvitreous hemorrhage and/or retinal detachment.

Vitreciorny may be indicated for complicatedret inul detachments. A retinal detachment associ-atcd with vitreous hemorrhage may require vitrec-tomy prior to a scleral buckling procedure to allowthe surgeon to visualize the retinal breaks. Someretinal detachments due to posterior retinal breaksarc best treated with vitrectorny. Retinal dctachmeurwith proliferative vitreoretinopathy requires vitrcc-torny in its advanced stages to remove tractionalmembranes. Giant retinal tears may require vitrec-torny in order to unfold the retina and introduce atamponade (such as gas or silicone oil).

Macular e pire tinal membranes may be idio-pathic or follow retinal detachment surgery, cryo-pexy. laser photocoagulation, or be associatedwith various vascular retinopathies. Surgery is

69


Table ~-2_ Indications for Vitrectomy

Nonresolving vitreous opacities

Proliferative retinop;lthies

Traction retinal detachments

Complicated rhegmutogenous retinal detachments

Retinal detachment with vitreous hemorrhage

Proliferative vitreoretinoputhy

Posterior tears

Giant tearsCombined tr;lctional-rhegmatogenous retinal

detachmentsPosteriorly dislocated crystalline lens or lens material

Posteriorly dislocated pseudophukos

Epireunal membranes. vitreornacular traction. and

vitreopapillary traction

Macular holesSubretinal neovascular membranes arid/or subrerinal

hemorrhage

Diagnostic vitrectorny

Ocu lar trauma including intraocular foreign bodies

Ent.!ophrhalmitis

Retinal detachment associated with retinopathy of

prematurity

[ntruvitreal ganciclovir implantation

Other: uveitis and aphakic cystoid macular edema

Foveal translocation

seldom indicated until the visual acuity is reducedto 20/60 or worse.

The whole lens or part of a lens may dislocateposteriorly during cataract surgery and may causeuveitis. glaucoma, or lead to retinal detachment. Adislocated lens may be secondary to Marfau's syn-drome, hornocystinuria, trauma, or syphilis. Poste-riorly dislocated lenses are best managed withvitrectorny techniques.

A posteriorly dislocated pseudophakos may leadto posterior segment complications. By using vit-rectorny techniques. a dislocated intraocular lens(I0L) can be either repositioned or removed.

Yitrectomy may be indicated to obtain a vitreousspecimen for cytologic diagnosis of a neoplasmsuch as large cell lymphoma. Cultures can beobtained in suspected cases of endophthalmitis anda cellular diagnosis obtained in cases of uveitis. Vit-rectomy for molecular diagnosis of several infec-tious organisms is now possible. In particular, PCRis useful for diagnosis of herpes viruses. In somecenters, peR diagnosis of syphilis, toxoplasmosis,bacteria, and fungi is available. Vitrectorny mayalso be indicated in uveitis to clear the media, to

treat tractional complications, and to removecyclitic membranes.

Vitrectorny may be indicated in patients withaphakic or pseudophakic cystoid macular edema(CME) if vitreous is incarcerated in the wound orperhaps adherent to anterior intraocular structures.Vitrectorny for CME is controversial in eyes with-out vitreous incarceration.

In cases of endophthalrnitis, vitrectorny is usefulfor obtaining a specimen for culture, as well as forremoving inflammatory debris from the eye. In asso-ciation with the use of intraocular antibiotics, the treat-ment of endophthalmitis has been greatly enhanced byvitrectorny techniques. Vitrectorny has been provenbeneficial in the most advanced forms of endoph-thalrnitis by the Endophthalmitis Vitrectorny Study.

Ocular trauma associated with penetrating injuriesor intraocular foreign bodies is often managed withvitrectorny techniques. Penetrating injuries withsevere hemorrhage with or without retinal detach-ment often require vitrectorny, Intraocular foreignbodies that are nonmagnetic, obscured by hemor-rhage, incarcerated in tissue, or encapsulated usuallyrequire treatment with vitrectomy.

Retinopathy of prematurity in advanced stagesmay require vitrectorny. Newer lens-sparing vitrec-tomy techniques may improve visual rehabilitationfollowing surgery in neonates. and the use ofsmaller, 25-gauge instruments should allow saferand more precise surgical maneuvers.

While not always requiring a vurectorny, the useof ganciclovir implants has improved the quality oflife of many patients by allowing them to stop orreduce the need for frequent intravenous or intra-vitreal anti viral therapy.

More recent indications for vitrectorny are fortreatment of macular disorders such as macular hole.subretinal hemorrhage, and subfoveal neovascularmembranes. Treatment of a macular hole requires vir-rectomy, separation of the posterior cortical vitreousover the macula, dissection of epiretinal membranes,and possibly internal limiting membranes, and tam-ponade with a gas bubble. Subfoveal neovascularmembranes and subretirial hemorrhages may beremoved through small retinotomies following vit-rectomy. The indications for the latter procedures arethe subject of an ongoing national randomized clinicaltrial (Subretinal Surgery Trial) sponsored by theNational Eye Institute. Foveal translocation tech-niques may offer the possibility of visual improve-

ment for some patients with subfoveal choroidal neo-vascular membranes. Indications for these procedureshave yet to be completely defined and randomized;controlled clinical trials are pending.

Instrumentation

Early vitreous cutting instruments were "full-func-tion" instruments that provided cutting capability,suction, fluid infusion, and illumination in a singlelarge probe. The full-function' instrument was placedthrough a single large sclerotomy site. Moderninstruments are of a "split-function" design, inwhich suction and cutting. infusion, and illumina-tion are separated and placed through three individ-ual small ports. By separating the function of theinstruments, it was possible to reduce their size, Theadvantages of rniniaturiz ing the instruments out-weigh the disadvantages of the multiport system.Early instruments had a routing or oscillating innercuning tip, but most recent instruments use a "guil-lotine" cutting action. The guillotine cutting instru-mcnt (Figure R-l) has an outer fixed tube (Figure8-1 A) with an opening (Figure 8-1 B) through whichvitreous is aspirated. An inner cutting tip (Figure8-1 C) slides across the inner ponion of the openingto cut the vitreous. There is less risk of incarceratingvitreous in the opening of an instrument with a guil-lotine-type action than one with a rotating or oscil-lating action. Most instruments cut at a maximum ofapproximately 600 cycles per second. Some newerinstruments have cutting rates of up to 1500 cyclesper second that cause less traction on the retina whencutting unseparated vitreous such as at the vitreousbase. Sm311er diameter cutters, as small as 25 gauge,have been developed for use in small eyes.

Other instruments necessary for vitreous surgeryare listed in Table 8-3. It is often difficult to predictwhich instruments will be necessary during an indi-vidual case, so we recommend that all instrumentsbe available for most cases.

C::?t' c

Figure 8-1. "Guillorine" vitreous cutler. Inner cylindricalblade (C) slides "cross opening (B) within outer tube (A).

Posterior Segment Vitrectomy 71

Table 8-3. Accessory Vitrcctorny Instruments

Microvitreorctinal blades (19 and 20 gauge)Scleral plugs and forcepsLens system

Hand-held infusion lensesSew-on lens ring set

Lenses for posterior pole, wide angle, periph-eral viewing and fluid-gas exchange

Wide-angle system (contact vs. noncoruact)Illumination system

Light sourceFiberoptic illumination probes

StandardWide-angleIlluminated picks (Figure 8-2). knives. or

forcepsUltrasound lens fragmentation unitBipolar diathermy

ExodiathermyUnimanual. bipolar endodiathcnny

Vitrcorcrinal picksBarbed MVR bladeMichels picksIlluminated picks

Vitreous scissors

Righi angle vertically cutting (Figure 8-3A)Horizontally cutting (Figure 8-3B)Automated handpieceMembrane Pcclerf.uner (MPC) (Figure 8-4)

Vitreous forcepsEnd-grabbing membrane

Various sizes and configurationsDiamond dusted (Figure 8-5A)

Machemer diarnond'dusted foreign body forceps(Figure 8-SB)

Subretinal forceps (Figure 8-SC)Illuminated forceps

Suction needlesSilicone-tipped

Charles (fluted) needle and handle (backflush systempreferred)

Backflush brushCannulated extrusion needle system (snake)

Laser endophotocoagulation systemLaser Indirect OphthalmoscopeContinuous infusion air-pump systemCryosurgical unitPerfluoropropane and SF6 gasesSilicone oilPerfluorocarbon liquidTissue manipulator (Figure 8-6)Iris retractorsDiamond-dusted membrane scraperIntraocular foreign body magnet

T!. MANUAL OF RETINAL SURGERY

Figure ::1-2. Fiberoptic illurninuted pick.

8Figure !l-J. Sutherland vitrcoretinal scissors (Alcon Surgical. Fort Worth, TX). A, Horizorually-cuttiug , B, Vertically-CUlling.

FiJ.:ure !l--t tvll'C virrcorctinal scissor (Alcon Surgical. Fort Worth, TX).

Preoperative Management biomicroscopy (i.e., using a Goldmann three-mirror ora 78- or 90-diopter noncontact aspheric lens). Cross-sectional vitreoretinal drawings can' be most helpfulin understanding complex vitreoretinal pathologicchanges. Retinal drawings should include the degreeof posterior vitreous separation and the areas of vitreo-retinal adhesion. Proliferative membranes and activencovascularization should be documented and areasof choroidal detachment and anterior cyclitic mem-brane (distorting the peripheral retina). which mightinterfere with instrument placement. should be noted.

Ocular Examination

A complete general eye examination should be per-formed on both eyes of all patients prior to vitreoussurgery (see Chapter 2). If the patient cannot readthe Snellen chart. lower levels of visual acuityshould be documented.

Of particular interest to the vitrectomy surgeon isthe study of vitreoretinal relationships with slit-lamp

Posterior Segment Vitrcctomy 73

1111.

1

1,1

I if/\

I{

fl .'II) I

II!

A B cFigure 8-5. Vitreoretinal forcers, A, Sutherland diamond-dusted end-grabbing forcer (Alcon Surgical. Fort Worth. TX).B, Machcrncr diamond-dusted foreign body forcep (Alcon Surgical. Fan Worth, TX). C, Subrcrinal forcer (Synergetics.SI. Louis. MOJ.

"'"---'=-=,===>E-'~-==-

Figure 8·6. Tissue manipulator.

Corneal clarity must be carefully evaluated,since severe opacification might require the use of atemporary keratoprostbesis device. A donor corneashould be available at the time of surgery if the tem-porary keratoprosthesis is to be used.

As mentioned in Chapter 2, the iris should bemeticulously examined prior to instillation of mydri-aries to search for iris ncovaxcularization (rubeosisiridis). Preoperative iris neovascularization is a par-ticularly poor prognostic factor in diabetics, although

7~ MANUAL OF RETINAL SURGERY

prompt reattachment of a detached retina and exten-sive intraoperative endophotocoagulation may sal-vage the eye.

The lens should be carefully evaluated to deter-mine both the clarity of the lens and the estimated"hardness" of the lens nucleus. It is usually easierto remove the lens early in the procedure; therefore,the decision to remove the lens is often made pre-operatively. If an extremely hard lens nucleus isanticipated, the decision to perform a limbal extrac-tion is sometimes made.

Surgical Planning

The surgeon should have a plan for the operation.Although findings and events at surgery maychange the surgical design. careful preoperativeplanning will reduce the likelihood of intraopera-ti ve problems. The surgeon should anticipate theequipment needed for the procedure. Ultrasoundlens fragmentation. scissors, forceps, or otherequipm~nt should be available as required (seeTable 8-3). The surgeon should try to anticipatepotential surgical complications.

Prior to induction of anesthesia, the operatingmicroscope. the vitrcctorny instrument and console,all foot pedals, and other critical instruments arechecked for proper function. All equipment neededfor the procedure should be available (see Table 8-3).

Anesthesia

Vitreous surgery can be performed under eitherlocal or general anesthesia (see Chapter 6). We uselocal anesthesia with close monitoring of thepatient's medical condition by an anesthesiologist(or most cases. We use general anesthesia for chil-dren and for adults unable to tolerate a local anes-thetic. Examples of adults that might benefit froma general anesthetic include patients that are men-tally challenged, highly anxious, or claustrophobic.

For local anesthesia, we require anesthesiastandby with constant monitoring of the patient. Weprefer a 50:50 mixture of 2% lidocaine (Xylocaine)and 0.75% bupivacaine as the local anestheticagent. A lid block is usually not used. We give aninjection of 5 rnl of the anesthetic solution in theretrobulbar space. The patient may be placed on an

air mattress for comfort. We create a tent over thepatient's nose and mouth by elevating the drapeswith a small cardboard device that adheres to theface with a Nevyas disposable drape retractor (Var-itronics, Inc., Broomall, PA). Oxygen is deliveredto the patient through a nasal catheter. High levelsof oxygen should usually be avoided since this canpromote retinal phototoxicity. Sedation may be ben-eficial for some patients. but it is important that thesedative be' carefully titrated by an anesthesiologistexperienced in local anesthesia. Patients should notbe overly sedated because they may move uponawakening during the procedure.

Patient Preparation

We cleanse the skin and the eyelids with 10%povidone-iodine (Betudine) solution. We place5% povidone-iodine in the conjunctival cul-de-sac.The head is centered on the headrest. leveled, andthe face is directed toward the ceiling. Proper drap-ing is critical to ensure a sterile. dry field and toprotect personnel and equipment from fluids on thefloor (Figure 8-7). We drape the forehead. thenplace a large plastic drape over the eye, draping outthe eyelids, with an adhesive portion covering theeyelid and periocular skin. The nonadhesive portionof the drape covers the remainder of the face andthe operati ve field. Figure 8-7 shows the drapedpatient and the trough around the head created inthe drape between the head and the U.shaped wristrest surrounding the top and sides of the head. Fluidis caught in the trough and is removed with a suc-tion catheter.

Instrument Arrangement

A host of large instrument consoles and foot pedalsare necessary for vitreous surgery. The instrumentsshould be arranged in a convenient and safe man-ner that allows easy access to th~" patient by theoperating room personnel. Foot pedals should beplaced so that the surgeon can easily engage themwhile maintaining his or her balance. Consoles canbe conveniently stacked on a neurosurgical tableplaced across and above the inferior portion of theoperating table (Figure 8-8). A sterile plastic drapecan be placed over the consoles.


Figure 8·7. Patient draped for vitreoretinal surgery.

Figure 8-8. Instrument consoles stacked on neurosurgical table.

Intraocular Infusion Solutions combination appears to be the best available ocularirrigating solution: (I) glutathione, which protects thecellular enzymes from oxidizing agents and is essen-tial for maintaining intercellular junctions; (2) glu-cose, an energy source; (3) magnesium, an important

The intraocular solution for infusion should be sterileand isotonic, with constituents near those of normalocular fluids and with a balanced pH. The following


factor in cellular enzymes; (4) a bicarbonate buffersystem; and (5) Ringer's lactate solution. We usecommercially available balanced salt solution (BSSplus, Alcon Laboratories, Fort Worth) for vitreoussurgery.

Diabetic lenses may develop posterior subcapsu-lar feathery opacities during vitrectorny due toexcessive accumulation of glucose. fructose, andsorbitol, which induce osmotic uptake of water. Weadd J cc of 50% dextrose (without preservatives orantiox idunts) to 500 cc BSS plus solution (whichincreases the glucose concentration to 400 mg/dland increases the osmolality of the solution to 320mOsm) to prevent lens opacitication during diabeticvitrectomy. We use glucose-fortitied BSS plus fordiabetic patients and regular BSS plus (withoutadditional glucose) for nondiabetic patients.

Preparation for Entrance into tire Eye

Prior to entering the eye, we inspect and test the vit-rcctorny instrument and flush air bubbles from thesystem. We inspect the infusion port and run fluidthrough the tubing to flush out any remaining air.We test the fiberoptic light probe. We make finalmicroscope adjustments. then adjust the height andposition of the surgeon's chair so that the surgeonis sitting with his or her back straight (to avoid laterdiscomfort) and on the front edge of the chair (toavoid later pressure-induced numbness of the feet).Ideally, the angle between the surgeon's upper legand lower kg approximates 90 degrees. All footpedals should be functional and comfortably acces-sible. The infusion bottle height is adjusted to about13-15 cm above the level of the eye.

The operating microscope should have coaxialillumination and X-Y function. A beam splitter isused to' give the assistant a coaxial view. We use amicroscope with a multifunctional foot switch thatcontrols zoom, focus, X- Y movement, room lights,and operating microscope lights. We prefer to coverthe microscope with a sterile plastic drape to avoidinstrument contamination. We orient the microscopevertically to permit equal access to all meridians ofthe eye. Many microscopes can be tilted toward oraway from the surgeon to improve visualization ofthe superior or inferior periphery. The microscopefoot pedal should be draped with a plastic bag to pre-vent fluids from causing electrical malfunction.

Operative Technique

Entrance into the Eye

If a scleral buckle is planned. we open the conjunc-tiva 360 degrees at the limbus, and loop the mus-cles with 2-0 silk sutures. However. we do notcreate a full lirnbal peritomy if we do not plan onplacing a scleral buckle. Figure 8-9 shows an eyeprepared for vitrectomy when a scleral buckle is notplanned. We place a transconjunctival 4-0 silksuture on 00-1 needle through the tendon of themedial rectus muscle. We then make a temporalconjunctival limbal peritomy with a radial relaxingincision at the temporal horizontal meridian. Weexpose the sclera and place a 4-0 silk traction suturethrough the tendon of the lateral rectus muscle. per-mitting good exposure for the temporal sclerotomysites (Figure 8-9). We then make a 5-mm radialconjunctival incision that extends from the limbusnasally toward an area just superior to the medialrectus muscle. We apply light bipolar diathermy tothe episcleral vessels in preparation for making thesclerotomies.

The ideal sclerotomy site is through the parsplana anterior to the vitreous base. Figure 8-10shows the surgical anatomy between the limbus andthe ora serrata. (The sclerotomy site is usuallylocated between the anterior pars plana and theanterior vitreous base.) Sclerotomies are made3 mm posterior to the limbus in aphakic orpseudophakic eyes or in eyes in which a lensectomyis planned. Sclerotomies are made 3.5-4.0 mm pos-terior to the limbus in phakic eyes. The sclerotomysites must be made more anteriorly in infants' eyesand in eyes in which the retina is pulled anteriorlyover the pars plana by anterior traction.

Sclerotomy sites should be close to the horizon-tal meridians in order to allow equal access of instru-ments to the superior and inferior peripheral retina,but we try to avoid the anterior ciliary arteries locatedanterior to the muscle insertions. The infusion portshould be located just inferior to the meridian of thelateral rectus insertion, while the instrument sclerot-omies should be just superior to the meridian of thehorizontal rectus insertions, 150--160 degrees apart(Figure 8-9). Infusion ports or instruments placed toofar from the horizontal meridian may hamper move-ment of the eye due to impaction of the instrumentor the infusion tubing on the lid speculum. We mark


Figure 8·9. Eye prepared for virrcorctinul surgery. Infusion port inserted inferorcrnporally, Note plugs in nasal andtemporal sclerotomies.

Anterior pars planaAnterior vitreous base

Ora serraia

Posteriorvitreous ----base

Figure 8-10. Surgical anutorny from limbus to posteriorvitreous rase.

the site of the planned sclerotomy with a markingpencil after measuring with calipers. We place a 5-0nylon mattress suture on a DO-S needle around theplanned site of the infusion port (Figure 8-11). Wemake the sclerotomy with a 19-9auge rnicrovitreo-retinal blade (MVR blade) with the flat portion par-allel to the limbus. Alternatively, a 20-gauge MVRblade may be used and the opening dilated with a 19-gauge sharp rieedle. We direct the knife toward thecenter of the phakic eye, although it can be directed

Figure 8·11. Mauress suture prcpluccd around sclcrut-orny prior to place men! of infusion port.

slightly more <Ulteriorly in the aphakic or pscudopha-kic eye. The widest portion of the arrowhead-likeknife must pass through the pars plana epithelium.This is accomplished by passing the tip approxi-mately 5 mm into the eye. We flush any remainingair bubbles from the infusion line; then, with theinfusion turned off, the infusion cannula is inserted.We use a 4-0101 long cannula in most eyes, but if thechoroid is thickened, the pars plana is covered by


dense blood, inflammatory cells, or fibrous tissue, orthe pars plana is detached, a 6-mm cannula can beused in the aphakic or pseudophakic eye. The can-nula is fixed in place with the mattress suture. If thetip of the infusion cannula does not pierce the parsplana epithelium, infusion into the choroidal or sub-retinal space may result. The tip is easily visualizedby directing the fiberoptic light from the oppositeside of the eye through the cornea as the irifusion portis depressed into the eye. The tip should be clearlyidentified before the infusion is turned on. If blood,cataract, or other opacity obscures the tip of the can-nula, a secondary hand-held, 20-gauge infusion nee-dle, with the tip visually identified in the eye, shouldbe used for infusion until the tip of the infusion can-nula can be visualized.

We make the instrument sclerotomies with a 20-gauge rather than a 19-9auge MVR blade so thatthere is less leakage from the sites during vitrec-tomy. We usually make the nasal sclerotomy firstfor the fiberoptic light probe. We direct the lightprobe toward the center of the phakic eye, but it canbe directed more anteriorly in the aphakic orpseudophakic eye. With the eye stabilized by thenasal instrument, we make the temporal sclerotomy,then place the vitrectorny instrument into the eye.In the aphakic eye, the instruments are easily visu-alized in the pupillary space without a contact lens.In the phakic eye. we place the contact lens on theeye immediately in order to identify the instru-ments. If one or both instruments cannot be seen,the surgeon should back his or her eyes away fromthe microscope and examine the eye grossly. Instru-ments can be realigned to point toward the centerof the eye, then the tips can be more easily seenwhen the surgeon once again looks through themicroscope. If tissue is seen to be pushed forwardby either instrument, that instrument should be.removed and the sclerotomy site opened once morewith the MYR blade before the instrument is rein-serted into the eye.

Basic Vitrectomy

The position of the wrist rest should be higher in thephakic eye to keep the hand position somewhat moreanterior; thus, the instrument tips will be directedmore posteriorly to avoid damage to the lens. In thephakic eye, the surgeon should develop a sense of

hand position to avoid bringing the instruments ante-riorly and possibly damaging the lens.

The eye is manipulated with a bimanual tech-nique with the two instruments. The basic eyemovements are vertical, horizontal, and obliqueductions of the eye. These movements are made byexerting equal force with the two instruments in thesame direction. Unequal force or torsional forces bythe instruments will create corneal striae and reducevisibility. Instruments are held with the fingertips.Individual instrument manipulations that must bemastered are rotational and in-out movements.Combinations of the bimanual manipulations of theeye and rotational and in-out movements are neces-sary to perform basic vitrectorny techniques.

The fiberoptic light should be held a short distanceaway from the vitrectomy instrument and directedjust to the side or just beyond the tip of the instrumentto illuminate the vitreous and reduce glare. Indirectillumination is frequently useful and is accomplishedby directing light at the posterior retina and using thereflected light to illuminate the field.

Moderate suction (maximum of 150 mm Hg)and a rapid cutting rate (400-600 cycles per secondor sometimes higher) are used. After ascertainingthat the infusion is on, cutting is tested in the centralanterior vitreous. With low suction. the vitreous isengaged in the port. If the instrument is not cuttingadequately, the vitrectomy hand piece should bereplaced. If there is inadequate suction or if suctiondoes not disengage, the instrument console shouldbe checked.-Yitreous to be removed may be opal\ueor clear. If the vitreous is clear, the retina can beeasily monitored during vitrectorny. If the vitreousis opaque, the retina is often hidden and there maybe a risk of cutting into the retina.

The four basic vitreoretinal relationships are asfollows: (l) vitreous separated from attached retina,(2) vitreous not separated from attached retina, (3)vitreous separated from detached retina, and (4) vit-reous adherent to detached retina. In addition, thereare eyes with partial vitreoretin~t~'eparation withfocal or broad areas of vitreoreti~al adhesion. Thevariable vitreoretinal relationships require differentapproaches during vitrectomy.

If the instrument is functioning properly, the vir-rectomy is begun. Loose central vitreous not undertraction will usually come directly toward the port.The instrument tip is placed in the anterior centra.vitreous and directed either slightly superiorly or

inferiorly to begin the vitrectorny. The surgeonshould follow the instrument tip with the X- Y of theoperating microscope, always keeping the instru-ments in the center of the field. Frequent change ofdepth of focus anterior and posterior to the field ofthe instruments will keep the surgeon aware of anyunwanted tissue, such as retina that might be com-ing toward the.instrument, The instrument cuts bestif the port is directed toward the vitreous to be cut(Figure 8- J 2A). If loose vitreous is not under trac-tion, it will sometimes curl around the probe 10 theport when the port is directed away from the vitre-ous (and away from the retina). This is a goodmethod if the retina cannot be seen. If the attachedretina can be identified, direct cutting with the portdirected toward the vitreous is preferable, If the vit-reous is under traction, the port must be directed atthe vitreous to be cut. In order to section a vitreousband, it must be directly engaged by the vitreouscutter. While cutting vitreous, the surgeon shoulddisengage from the vitreous regularly to check thatthe instrument continues to cut well.

Clear vitreous may be difficult to visualize dur-ing cutting. Formed vitreous can be seen whendirectly illuminated with the fiberoptic light, but isdifficult to see with diffuse or indirect illumination.If vitreous is not well seen, the angle or distance ofthe fiberoptic light from the vitreous should beadjusted in order to better illuminate the vitreous.

An important point in the procedure is the inci-sion of the posterior hyaloid. This frequently pro-

Posterior Segrneru Vitrectomy 79

vides the first view of the retina. The posteriorhyaloid should first be opened over attached retina,if possible, and preferably in an area in which thevitreous is well separated from the retina. The pre-operative ultrasound scan will frequently delineatethe best area, If the posterior hyaloid is collapsedand thin, it may curl around the vitrectomy instru-ment tip into the cutting port even if the port is notdirected toward the hyaloid. If the hyaloid is thick-ened, it is necessary to direct the port toward thehyaloid. The opening in the posterior hyaloid isenlarged until the retina can be visualized. If bloodin the subhyaloid space obscures the retina, after theopening is adequately enlarged. the blood isremoved with a silicone-tip suction needle. Whenthe retina is well-visualized, the cutting port of thevitrectomy instrument is placed through the open-ing in the hyaloid and the port is directed awayfrom the retina toward the hyaloidal edge. Thehyaloid is engaged and cut, centrifugally enlargingthe opening in progressively larger concentric cir-cles toward the periphery. It is necessary to cut theperipheral vitreous back far enough to give an ade-quate view of the peripheral retina (Figure 8-128).In eyes at risk of anterior cellular proliferation (eyeswith retinal detachment, diabetes, or anterior reti-nal breaks) scleral depression is useful in exposingthe peripheral vitreous for excision.

Removal of the peripheral vitreous is more diffi-cult than removal of the posterior vitreous. The inex-perienced surgeon may have difficulty visual izing

Figure 8-12. A, Cutring port directed toward vitreous to be cut. B, Postvitrectorny eye. Only remaining vitreous is atvitreous base,


the peripheral vitreous. There may be inadequateillumination and striae and distortion of the corneacreated by unequal force on the instruments whentaking the eye to extremes of direction. Relaxing thegrip and equalizing the force on the instruments inorder to reduce tension between the sclerotomy sitescan eliminate the corneal striae.

Direct illumination of the peripheral vitreous onthe side of the vitreous-cutting instrument is impos-sible in the phakic eye without touching the lenswith the shaft of the fiberoptic light source (Figure8-l3A). Adequate illumination can be obtained byusing indirect illumination, in which the light isdirected toward the posterior retina using thereflected light for visualization (Figure S-LJ B). Thesurgeon should not try to cut the far peripheral vit-reous on the side opposite the entrance site of thecutting instrument because of the danger of touch-ing the lens with the shaft of the instrument. Thatvitreous can best be removed by exchanging theinstruments so that the cutting instrument is on theside of the peripheral vitreous to be cut. Remainingblood or debris on the retinal surface is removedwith the silicone-tip suction needle.

If the retina is partially detached, the posteriorhyaloid should be incised over attached retina ifpossible. If the retina is completely detached, theincision of the hyaloid is best done over a less bul-lous area. Although preoperative ultrasound scans

may be helpful, the configuration of the retinaldetachment may change at surgery, so an incisionposteriorly over the optic nerve where the retina isflat is usually best. If the posterior hyaloid is col-lapsed anteriorly, the cutting port is directed anteri-orly and the vitreous and posterior hyaloid may curlaround the tip into the cutting port during suction.However, it is usually necessary to direct the cut-ting port at least parallel with the collapsed hyaloidor directly toward a thickened or taut hyaloid tocreate an opening. Cutting and suction should stopas soon as an opening is made in the hyaloid. Oncethe hyaloid is opened, the instrument tip is placedthrough the opening and the cutting port is directedaway from the detached retina toward the hyaloid.Low suction is applied and the retina is kept in viewduring vitrectorny. Vitreous is cut peripherall)toward the vitreous base. In the periphery there isdanger of suctioning bullous retina into the cuttingtip. A good method to use in the periphery near theretina is to engage the vitreous with low suction ancshort bursts of cutting, letting the vitreous (ancretina) fall back between .cuts. If a retinal break ilocated, subretinal fluid can be aspirated with thsilicone-tip suction needle to partially flatten thretina. thus reducing the risk of peripheral retinadamage. Newer high-speed vitreous cutting instru-ments may exert less traction on the detached retinabecause there is less unobstructed suction betweer

BFigure 8-13. A, Lens touch with endoilluminator while illuminating vitreous on opposite side of eye. B, Indirect illurni-

nation of vitreous avoids lens touch.

the high-speed cuts. There is more control duringthe procedure because of the reduced mobilityof the retina during cutting.

Another maneuver that will reduce the mobilityof the detached retina is to inject perfluorocarbonliquid (PFCL) over the posterior pole to flatten theretina posterior to the peripheral vitreous. It isimportant that posterior vitreous and membranes beremoved prior to PFCL injection and that there beno remaining posterior retinal traction. The PFCLshould not extend over retinal breaks still under trac-tion because of the risk of the PFCL going beneaththe retina. The PFCL should not extend so far ante-riorly so as to flatten the peripheral vitreous againstthe retina. Vitreous should be cut as far peripherallyas safety permits. In most cases of retinal detach-ment, scleral depression (usually by an assistantwith a scleral depressor or with a cotton-tippedapplicator) should be performed during cutting toimprove visibility and access to the peripheral vitre-ous. During scleral depression there is risk of inad-vertent retinal damage by the instruments. Duringinitial placement of the external scleral depressor,the internal instruments should be kept well clear ofthe area of depression. Once the depressor is inplace, the assistant should not change the position ofthe scleral depressor until the surgeon requests achange and moves the internal instruments out of theway. At the central area of depression the retina ispushed inwardly toward the vitreous, so it is oftensafest to cut at the margin of the area of depression.A contact or noncoruact wide-angle viewing systemreduces the need for scleral depression during exci-sion of the peripheral vitreous.

In some cases of rhegrnatogenous retinal detach-ment, diabetic retinopathy, penetrating ocularinjury, retained intraocular foreign body, uveitis, orepiretinal membrane, the posterior cortical vitreousmay not be separated from the retina. In most casesit is best to surgically separate the vitreous, which,if left in contact with the retina, may act as a scaf-fold for proliferation of scar tissue. In addition, it isnecessary to separate the posterior cortical vitreousfrom the retina in cases of macular hole. Sometimesas the formed central vitreous is cut, the posteriorhyaloid will spontaneously separate from the retina.In most cases, however, it is necessary to separatethe posterior hyaloid mechanically. If the vitreousis clear, it is sometimes difficult to determine if thehyaloid is separated. As the posterior cortical vitre-

Posterior Segment Vitrectorny SI

ous is cut, one can often see traction causing move-ment of the retina beneath the vitreous being cut. Ifthe vitreous is densely opaque, visualization of thevitreoretinal junction may be difficult. By "shav-ing" the vitreous in layers with low suction andapproaching the retina over the optic nerve area, thejunction can usually be visualized safely. Byapproaching over the optic nerve, there is less riskof engaging a detached retina.

The vitreous can be separated from the retina byone of two methods. We first apply suction to the cor"tical vitreous over the optic nerve head border (Fig-ure 8-14). It is best to begin the maneuver before thecore (central) vitrectorny is complete, because at thatstage the vitreous is easier to engage. By graduallyincreasing suction with a silicone-tip needle anteriorto the edge of the optic nerve head, the posterior cor-tical vitreous can usually he elevated. The vitrcciomyinstrument can be used in a similar manner (with suc-tion only) facing the open port posteriorly. Higher lev-els of suction are frequently required (up to 200 mmHg). Once the vitreous is elevated from the optic disc.fluid will go into the subhyaloid space through theopening over the optic nerve head to create. in effect,a rhcgrnatogcnous separation of the vitreous. A mem-brane pick can then be used to help separate the vitre-ous our 10 the retinal periphery (Figure 8-15). In therare event that the posterior conical vitreous will not

Figure 8-14. "Fish-strike ~ign" as aspiration through sili-cone-tip needle engages posterior vitreous cortex andcauses torsion of needle lip.


A BFigure 8-15. A, B, Lifting and separating posterior hyaloid with pick placed through epipapillary opening.

separate with suction, a sharp membrane pick can beused to separate the hyaloid (Figure 8-16). A sharpbut short-tipped pick is best and we have found theMVR blade useful. We create a short barb of the tipby pushing it against a ftut metal surface whileobserving the tip with the operating microscope. By

scratching the surface of the hyaloid at the optic nervehead edge, we engage the hyaloid and lift it awayfrom the retina. The hyaloid then separates in a m3II-ner similar to that described with the suction tech-nique. If the retina is detached. it is best to fixate theretina gently with a second instrument (i.e .. the light

(;.;

Figure 8-16. Separation of posterior hyaloid with sharp pick. Vitreous engaged at edge of optic disc.

probe or an illuminated spatula) as the hyaloid is sep-arated. As the hyaloid is stripped to the periphery, thesurgeon should constantly assess whether there isexcess vitreoretinal traction (which might lead to reti-nal tearing or hemorrhage). If the vitreous will notseparate from a firm vitreoretinal adhesion, the vitre-ous should be separated and circumcised around theadhesion. Figure 8- 17 shows the vitreous being cutwith the vitreous cutler around a point of adhesion torelieve the traction.

Termination of the Procedure

When the instruments are removed from the eye,the infusion should be turned off to prevent incar-ceration of vitreous and retina in the wound. Scleralplugs should be placed in the sclerotomy sites, andthe intraocular pressure restored to norrnal with theinfusion.

The eye should be examined with the indirectophthalmoscope to determine whether adequate vit-reous was removed and to look for complications.The peripheral retina should be examined withscleral depression 10 search for dialyses or tears at thevitreous base and posterior to the instrument sites.

With the infusion off. one plug is removed. andincarcerated vitreous is removed with the vitreouscutting instrument, using low suction. Remaining vit-reous is engaged with a dry cellulose sponge and cutwith scissors at the lips of the wound. When all gross

Posterior Segment Vitrectomy !!3

vitreous has been removed from the wound, the scle-rotomy is closed with a figure-of-eight 7-0 suture.The remaining sclerotomy sites are closed in a simi-lar manner. The pressure is adjusted if necessary withBSS injected through the limbus in the aphakic eyeor through the pars plana in the phakic eye. Theconjunctiva is closed with 6-0 plain gut or 7-0 Vicrylsutures.

Lensectomy

Lcnscctorny is performed if lens opacification willprevent adequate visualization during vitrcciomy.Rarely, the lens may opacify during surgery andrequire a lcnseciomy. A clear lens may be removedduring surgery for certain complicated retinaldetachments (such as caxcx requiring mcrnbrunedissection in the vicinity of the vitreous base). Thelens is removed most easi ly at the beginning of theprocedure. so the decision for lenscciorny should bemade preoperatively if possible. Posterior subcap-sular opacities interfere the most with visualization.Adequate visualization is possible through moder-ate nuclear sclerosis and con ical op.nitics.

The hardness of the nucleus is graded prcoper:.J-tively, Nuclear sclerosis is graded on a 0-4+ scale.A 4+ nuclear sclerotic lens is very hard. frequentlybrunesceru, and the lens is prominently seen inretroillumination. \Ve remove lenses with up to3+ nuclear sclerosis with pars plana ultrasound

Figure 8-17. Circumcision of vitreous around focal vitreoretinal adhesion.

8~ MANUAL OF RETINAL SURGERY

fragmentation, and those with 4+ nuclear sclerosisarc removed by limbal extraction.

If lirnbal extraction is necessary, we perform anextracapsular extraction of the nucleus. We closethe lirnbal wound with interrupted 10-0 ny\onsutures and then remove the remainder of the lenscortex and capsule during the pars plana vitrectorny.

For pars plana ultrasound fragmentation, afterthe infusion port has been sutured in place, the tem-poral sclerotomy is made as usual. directed towardthe center of the vitreous cavity. Then the MVRblade is redirected through the equator of the lensinto the nucleus. The sharp MVR blade will easilycut into a moderately hard nucleus. but may par-tially dislocate a very hard nucleus. Nuclear move-ment should be carefully observed to judgehardness. The ultrasound needle is placed into thelens through the sclerotomy site.

After the nasal sclerotomy is made, we place a20-gauge infusion needle through the nasal equatorof the lens. We bend the needle approximately 30degrees. 5-7 rnrn from the tip because the bend per-

mits better access across the patient's nose. We tem-porarily interrupt the pars plana infusion by clamp-ing the infusion tubing and attach the infusion to the20-gauge needle. We tum on the infusion in the cen-ter of the \el\~ a.nd begin ultrasound fragmentation ofthe nucleus with the infusion needle near but nottouching the ultrasound needle (Figure 8-18A).

It is important to initiate a flow of fluid throughthe ultrasound needle at the beginning of the lensec-torny so that nuclear material does not obstruct thetip. Ultrasound is applied in short bursts so as not togenerate heat with prolonged activation. The nucleusis removed inside out. preserving the cortex until theend. to help fixate the nucleus. Anterior, posterior,and peripheral nucleus are progressively removedwith intermittent simultaneous ultrasound fragmen-tation and suction. After the nucleus is removed. thecortex can be aspirated with the ultrasound needlewithout ultrasound energy (Figure 8-18B). Theperipheral cortex is stripped from behind the iris byengaging and gently pulling cortex toward the cen-ter of the pupil with simultaneous suction. If the ante-

A

Fil-:ure 11-11\.Pars planu lcnscctomy. A, Ultrasound fr~gmenlation of nucleus of lens from inside-out. B, Aspiration and

stripping of residual lens cortex.

rior capsule remains intact, there is little danger ofengaging iris. Nevertheless, the instrument tip shouldnot be pointed directly at the iris.

We usually remove the whole lens capsule in thefollowing manner. We remove the central portion ofthe anterior capsule, leaving a rim of capsule seenthrough the pupil. We then place a vitreoretinal for-cep in one of the sclerotomies and grasp the edge ofthe remaining anterior capsule and pull it centrally toexpose the peripheral lens capsule and the zonules.We then cut the zonules with the automated scissors(MPC, Alcon, Fort Worth). It is possible (0 sectionall of the zonules with the scissors and remove theremaining capsule. although it is usually necessaryto change sclerotomy sites with the instruments toaccess all of the zonules.

Alternatively. the anterior capsule can be left inplace to support a posterior chamber intraocular lens.A central 5 mm opening is usually made in the ante-rior capsule to improve SUbsequent visualization dur-ing the remainder of the vitrectorny procedure. Ifduring lcnsectorny the posterior capsule is prema-turely broken, there is risk of posterior dislocation oflens material, Lens nucleus or cortex will usually reston the intact vitreous and can be engaged and frag-mented. The infusion needle can be used to supportloose fragments, but the two needles should nottouch because metallic fragments may be released. If

Posterior Segment Vitrectorny 85

a lens fragment falls posteriorly, we remove anteriorlens material as described above with the ultrasoundneedle, the vitrectomy instrument, or both. We thenperform a vitreciomy with the vitrectorny instrument.Following vitrcctorny, we once more place the ultra-sound needle in the eye, and remove the posteriorlens material with posterior ultrasound fragmenta-tion. Figure 8-19A shows the posterior lens fragmentengaged with suction from the ultrasound fragmen-tation needle. The ultrasound is activated after thefragment is taken to the midvitreous cavity. Softnuclei mold 10 enter the tip of the needle, but hardernuclei fracture into smaller pieces. Each fragment isthen removed individually. It is important that ultra-sound not be activated near the retinal surfacebecause of the risk of retinal damage.

Additional Techniques in Vitreous Surgery

Membrane Peeling

ln-Iications

Membrane peeling is done to remove cpirerinalmembranes. Epirerinal membranes may be idio-pathic or may be associated with a variety of disor-ders, including proliferative vitreoretinopathy,

B

Figure 8-19. Ultrasound fragmentation of posteriorly dislocated lens nucleus. A, Nucleus retrieved from retinal surfacewith suction without ultrasound. H, Nucleus fragmented with ultrasound in rnidvitreous cavity. Adapted from Lewis JM.Abrams GW, Werner Jc. Managernent of complicated retinal detachment. In: Alben OM, ed. 01'11/1/(}II1l;c Surgery: Princi-ples and Practice. Vol. I. Malden, MA: Blackwell Science; t 999: 1306.


proliferative vascular retinopathy, uveitis, andtrauma.

Instrumentation

Instruments used for membrane removal are picksand forceps. Several varieties of sharp or bluntpicks or spatulas are manufactured. Forceps areusually of the end-opening variety and several areavailable (see Figure 8-5).

Surgical Technique

Epiretinal Membrane .••..ith Attached Retina. Mostepiretinal membranes removed in the presence ofan attached retina involve the macula. The retinabeneath the membrane is usually folded. There issometimes a thickened. elevated. or rolled edge tothe membrane but the edge may be nat and difficultto see. In most cases the edge of the membrane isengaged with a pick and elevated (Figure 8-20A)."Ve use a sharp. barb-like pick that we create underthe microscope by bending the tip of the 20-gaugeiv1V R blade again.~t the flat handle of anotherinstrument. There are also commercially availablesharp membrane picks. We engage the edge of themembrane and elevate it with a stripping motion.Sometimes the membrane will strip free with thepick. but usually it must be grasped with vitreoreti-nal forceps (Figure 8-208). A fine, end-grabbingforceps is best for this task because the membraneand retina arc not obscured by the forceps and canbe easily visualized as the membrane is grasped.

The retina beneath the membrane is oftenwhitened by axoplasmic stasis in the nerve fiberlayer. This may resemble additional membranes,but usually no further membrane is present. Unlessfurther membrane clearly remains, attempts at fur-ther membrane stripping should be avoided. Theretinal thickening and whitening will resolve post-operatively.

Epiretinal Membranes with Retinal Detachment,Epiretinal membranes associated with proliferativevitreoretinopathy may be widespread. Membranesare often associated with fixed folds. star folds. andmarked wrinkling and contraction. Membranes maynot be readi ly seen but should be expected in thecenter of a star fold or at the anterior extent of J

fixed radial fold. The only sign of some membranesis a graying of the retinal surface. Abrupt disap-pearance of a retinal vessel often indicates a foldobscured by an epiretinul membrane. Immaturemembranes may be composed of a sheet of con-tractile proliferative cells. with little collagenousmatrix, while mature membranes contain an abun-dant collagenous matrix. Mature membranes do nottear as easily as immature membranes and are moreeasily stripped free.

We usually begin membrane stripping posteri-orly at the optic nerve head and progress anteriorly.The posterior retina is thicker than the anteriorretina and is fixed at the optic nerve; therefore.membrane peeling posteriorly to anteriorly is bothsafer and easier.

Using J 3D-degree fiberoptic illuminated pick. weelevate the edge of the membrane (Figure 8-21 A).

Figure S-lO. Epiretinal membrane rernoval-s-attuchcd retina. A, Membrane edge lifted with membrane pick. B, Membranegrasped and removed with vitreous forcep. Traction force parallel with retinal surface. Adapted from Lewis JM. AbramsGW, Werner Jc. Management of complicated retinal detachment. In: Albert DM, cd. Ophthalmic Surgery: Principles andPrurtice. Vol. l. Malden. MA: Blackwell Science; 1999:1307.

We then grasp the membrane with forceps. We rec-ommend a bimanual technique be used for mem-brane removal. With the membrane under tension bythe forceps, we use the illuminated pick to hold theretina back during stripping (Figure 8-21 B) or, alter-natively, as a spatula to help free the membranefrom the retina. It is useful to run the illuminatedpick or barbed MVR blade within retinal folds (Fig-ure 8-22A) in order to locate membranes. At a starfold, we often engage the membrane in the center byrunning the illuminated piek radially in a foldtoward the center of the star fold (Figure 8-22B). Itis important to monitor the surrounding retina when


stripping a membrane because large breaks canoccur in a retina under traction. The risk of retinaltearing is reduced by using a bimanual technique, inwhich the retina is held back with another instru-ment such as the fiberoptic illuminated pick orspatula during membrane peeling. Thin or tightmembranes are sometimes difficult to engage witha blunt pick. These can often be engaged with theshort, sharp pick produced by barbing the tip of theMVR blade. We do not use the barbed MVR bladefor routine membrane peeling because the sharp.blade increases the risk of internal limiting mem-brane damage or tearing of the retina.

Figure 8-21. Epircrinal membrane rernoval-c--detached retina, A, Large membrane bridges retinal fold. Membrane edgelifted with illuminated pick. B. Membrane gra~ped and removed with vitreous forcep. Retinal countertraction with illumi-nated pick during membrane removal.

Figure 8-22. Membrane removal-PVR. A, Membrane engaged in retinal fold with illuminated pick. B, Membraneengaged with pick in center of "star fold."


Peripheral Membrane Removal. Peripheral vit-reoretinal membranes are found most commonly inproliferative vitreoretinopathy or following oculartrauma. but are sometimes found associated withproliferative vascular retinopathies. Most peripheralmembranes are associated with the vitreous basearea. The most severe forms of anterior prolifera-tive vitreoretinopathy are found following previousvitreous surgery. There are two major forms of ante-rior PYR: circumferential contraction caused bycontraction of membranes formed on the peripheralretina. usually at the posterior edge of the vitreousbase; and anterior retinal displacement, once called"anterior loop contraction." This latter form of PYRis caused by fibrous proliferation on the surface ofthe vitreous base with contraction that leads to trac-tion retinal detachment and anterior displacementof the peripheral retina. Figure 8-23A shows an eyewith proliferative vitreoretinopathy with prolifera-tion of cells on remaining peripheral vitreous fol-lowing vitrectomy. Following contraction of thevitreous base, the anterior retina is pulled forwardtoward the pars plana (Figure 8-23B), the ciliarybody. or even the posterior iris surface. Anteriorfibrovascular proliferation can be found followingdiabetic vitrectorny with either fibrous proliferationand contraction from a sclerotomy site or severet'ibrovascular proliferation from the peripheralretina called "anterior hyaloidal fibrovascular pro-liferation." While anterior proliferative membranes

in diabetic retinopathy tend to be more vascular, theappearance of the peripheral retina is similar to thatfound in anterior retinal displacement.

Surgical Technique

Surgical dissection in the vitreous base area neces-sitates removal of the lens. It is recommended thatthe lens capsule, which may become involved inanterior fibrous proliferation, be completelyremoved (as mentioned above). Scleral depressionis used to allow visualization of the vitreous base.Wide iris dilatation is helpful. Iris retractors may beuseful if the pupil is miotic. Coaxial illumination isused for the anterior portion of the dissection. Whiledepressing the anterior vitreous into view, the vir-rectomy instrument is used to remove any remain-ing formed vitreous (Figure 8-2'+).

Circumferential contraction becomes apparent asmembranes are peeled from posteriorly to anteri-orly. There are usually diffuse membranes and vit-reous is often adherent to these membranes,especially throughout the inferior 180 degrees ofthe retina. The vitreous and the membranes shouldbe stripped anteriorly to the vitreous base. Once themembranes have been stripped anteriorly andremoved if possible, the vitreous is excised to theretinal surface at the vitreous base with the vitreouscutter utilizing scleral depression.

Figure 8-23. A, Disbursement of cells onto retina and vitreous base. B, Anterior retinal displacement. Membrane bridg-ing vitreous base pulls anterior retina toward pars plana.

Figure S-2·t Removal of vitreous at vitreous base whiledepressing the ....clcru.

Anterior retinal displacement may only be apparentby a gray membrane that covers the tightly contractedvitreous basco The anterior retina is often pulled for-ward but m~IYbe obscured. There are two componentsto the anterior retinal displacement and each must bedeal! with. Circumferential sectioning of a membranethat covers the vitreous base is necessary to relieve ananterior-posterior (AP) component that pulls the retinaanteriorly. A circumferential component of contractionthat pulls the retina centrally and causes radial foldsthat extend posteriorly. must also be relieved.

The tight capsule-like membrane that overlies thevitreous base is incised with the tip of a sharp bladesuch as the MVR blade. After an opening is created inthis membrane, vertically cutting scissors, such as tilemembrane peeler-cutter (MPC) scissors (Alcon Lab-oratories, Fort Worth) , are used to section tile mem-brane anterior to tile anterior extent of tile retina in acircumferential direction (Figure 8-25). A bimanualtechnique is often useful and a fiberoptic illuminatedpick or spatula can be used to retract the fibrous mem-brane away from the vitreous base as it is cut. Theanterior retinal displacement is usually most promi-nent in the inferior 180 degrees but can extend 360degrees. There may be a "trough" created by themembrane between the anterior and posterior edgesof the membrane (see Figure 8-25). Formed vitreous


of tile vitreous base may be uncovered in the troughafter the membrane is opened and should be cut to thesurface of the peripheral retina and pars plana usi-ngthe vitreous cutting instrument.

The circumferential component of anterior reti-nal displacement is released by either excising themembrane on the surface of the vitreous base usingbimanual dissection or making multiple radial cutsin the membrane. When using coaxial illumination,it is possible to use both forceps and scissors in abimanual dissection technique. For endoillurnina-tion during bimanual dissection, the fibcroptic illu- .minared pick or spatula is useful. Fiberopticilluminated forceps and scissors have been intro-duced, but have not been universally adoptedbecause of their expense and limited availability.These illuminated instruments are helpful duringbimanual dissection of the vitreous base.

Treatment of Retinal Breaksand Retinal Detachment

Retinal breaks may be present prior to vitreoussurgery or may occur as a result of membrane

Figure 8-25. Treatment of anterior retinal displacement bysection of membrane overlying vitreous base,


removal techniques. Retinal detachment in associa-tion with the retinal breaks is usually treated with acombination of internal (vitrectomy) and external(scleral buckling) techniques. It is necessary to relieveall traction from the retinal breaks. It is best to removeremaining membranes by membrane peeling or exci-sion, but sectioning of the membranes is sometimesadequate. The retinal breaks are marked with endo-diathermy. The endodiathermy will whiten the edgesof the break and will allow easy identification fol-lowing fluid-air exchange. Subretinal fluid may bedrained internally during fluid-air exchange througha posterior retinal break if present. A continuous infu-sion air pump is used during fluid-air exchange. Theair pump is attached to the infusion port. A silicone-tip suction needle is used to remove the intraocularfluid. For visualization, a -98.00-diopter biconcavecontact lens is used in the phakic eye and theplanoconcave contact lens is used in the aphakic eye.Alternatively, a wide-angle viewing system can beused during the exchange providing a superior view.During the initial portion of the fluid-air exchange,the eye is positioned so that the posterior drainagebreak is easily seen. It is often best to aspirate someanterior fluid and till the anterior vitreous cavity withair. This gives a minified view of the fundus and it isnecessary to refocus the microscope and increase themagnification. The drainage needle tip is then placedjust anterior to or through the retinal break, and suc-tion is applied (Figure 8-26). As the eye fills with air,J meniscus can be seen between the fluid posteriorlyand the air anteriorly. When the fluid meniscus is pos-terior near the area of the retinal break, it is often bestto use a "dripping" technique to remove the fluid. Thedrainage needle tip is placed over the drainage retinot-amy and a bright reflex appears as the tip enters thefluid meniscus. The suction is applied until the fluidlevel drops below the needle tip and the reflex disap-

.pears. By continuing to "dip" over and into the break,the retina is completely flattened and as the needle tipenters the break, all of the subretinal fluid is removedwithout danger of the needle tip contacting the pig-ment epithelium and choroid. It is necessary to con-tinue dipping over the retinotomy and the optic nervefor several minutes because fluid tends to continue toaccumulate posteriorly for a short period of time. If aposterior break is not present, subretinal fluid can bedrained through a more anterior retinal break usingthe cannulated extrusion instrument. PFCL over theposterior pole can be useful during this maneuver.

After the retina is completely flattened and all fluidhas been removed, laser endophotocoagulation isapplied to surround any retinal breaks (Figure 8-27).

Figure 1l.26. Fluid-air exchange. Aspiration of subretinalfluid through posterior break while air is xirnultaneousl y

insufflated into the eye.

Figure 8-27. Endoluser photocoagulation of posterior reti-na! break in air-filled eye. Adapted from Lewis JM.Abrams GW, Wemer Ie. Management of complicated reti-nal detachment. In: Albert DM. ed, Ophthalmic Surgery:Principles and Techniques. Vol. l. Malden, MA, Blackwell

Science; 1999:542.

Perfluorocarbon Liquids

If a posterior break is not available and it is necessaryto reattach the retina completely, we now rarely createa posterior retinotomy. In most instances, if a poste-rior break is not present for drainage of subretinalfluid. perfluorocarbon liquid (PFCL) is used to reat-tach the retina, PFCL is a synthetic liquid that is heav-ier than water' or saline and will displace subretinalfluid anteriorly and reattach the retina from posteri-orly to anteriorly. Perfluorocarbon liquid can beinjected over the posterior pole after posterior mem-branes have been removed 10 flatten and stabilize theposterior retina. The heavy liquid flattening of theposterior retina makes midperipheral and far periph-eral membrane peeling easier by reducing the mobil-


ity of the retina during membrane peeling (Figure8-28A). As the retina is reattached with PFCL, fluidwill egress through anterior retinal breaks into the vit-reous cavity and allow near complete reattachment ofthe retina if the vitreous cavity is filled with PFCL(Figure 8-28B). The PFCL should never be directedtoward a retinal break during injection because thePFCL stream will go into the subretinal space throughthe break. IfPFCL is to be used, it is important that alltraction be released before the level of PFCL isextended over a retinal break, otherwise the PFCL,which has a low interfacial surface tension, will gothrough the break into the subretinal space. However,once traction is relieved from the retina, it is safe toextend the PFCL level anterior to a retinal break (Fig-ure 8-28C). Once the retina is attached, the PFCL can

Figure 8-28. Per1luorocarbon liquid (PFCL) in treatment of PVR. A, PFCL holds posterior retina in place as midperiph-eral membrane is stripped. B, Retina reattached with PFCL. Subretinal fluid forced through retinal break into vitreouscavity. C, Retina completely reattached with PFCL. Scleral buckle in place.


be removed by a PFCL-air exchange. The PFCL isaspirated with a silicone-tip suction needle as theeye is simultaneously filled with air. If anteriorsubretinal fluid remains before PFCL-air exchange,it is desirable to aspirate subretinal fluid duting theearly portion of the exchange through an anteriorretinal break so no subretinal fluid is forced poste-riorly into the posterior pole by the air. Whileperfluoro-n-octane, the most commonly usedPFCL has a high vapor pressure and will evaporatein air at body temperature. other commonly usedPFCLs do not evaporate. Therefore, it is necessaryto place a small amount of BSS over the posteriorpole following PFCL-air exchange to cause coales-cence of any remaining PFCL into bubbles that canbe seen and aspirated. Because larger amounts ofperfluoro-n-octane may not evaporate. we recom-mend flushing the posterior retina with BSSfollowing use of any PFCL. Perfluorocarbon liq-uids are also useful for management of giant retinaltears and retinotornies (see following sections"Relaxing Retinorornies and Retinectornies" and"Giant Retinal Tears").

Scleral Buckling

A scleral buckle is only necessary in the presenceof persistent or potential peripheral traction fol-lowing vitrectorny. A detailed discussion of scle-ral buckling surgery is presented in Chapter 7. Ascleral buckle is placed in most cases of prolifer-ative vitreoretinopathy where there is often atleast mild peripheral traction remaining and inmany other cases of rhegmatogenous retinaldetachment or giant retinal breaks. The sutures forthe scleral buckle are most easily placed at thebeginning of the case before starting the vitrec-tomy procedure. We prefer an encircling 4.0-mmdiameter band (42 band) for most retinal detach-ments at vitrectorny that require a scleral buckle.Occasionally, if the vitreous base extendsextremely posteriorly, we use a broader elementsuch as a 7 -rnrn diameter tire. If traction can beadequately relieved with vitrectomy, radial scle-ral buckling elements are usually not placed tosupport posterior retinal breaks. If it is not possi-ble to relieve traction adequately, posterior radialbuckles associated with an encircling element canbe used to relieve posterior traction.

Relaxing Retinotomies and Retinectomies

Indications

Relaxing retinotomies and retinectomies (in whichthe retina is cut or excised) are used in the presenceof shortening of the retina due to retinal incarcera-tion or fibrous proliferation and contraction thatprevents contact of the retina with the retinal pig-ment epithelium. Less significant. usually periph-eral, retina is cut or removed to preserve functionof posterior, more visually significant retina. Aretinotomy is the act of cutting the retina to relax ashortened retina. A retinectomy is the actual exci-sion of retina and associated proliferative mem-branes. Relaxing retinotomies and retinectomiesshould be performed only if other methods havefailed or have no chance of success. Several groundrules are necessary in surgery utilizing relaxingretinotornies or retinectomies. The retiriotorny orretinectorny should be performed late in the proce-dure, following complete membrane removal. If the:retina is cut or excised prior to complete membraneremoval, further membrane removal will be moredifficult and may result in larger than necessaryretinal defects or residual membranes that will leadto redetachmem of the retina. As a general rule. arelaxing retinotomy (in which the retina is cut. butnot excised) is made if the retina remains shortenedafter complete membrane removal; retinectorny (toexcise membranes and involved retina) is per-formed if membranes remain and traction cannot be:relieved by a scleral buckle. Larger peripheralretinotomies are less functionally significant thansmaller posterior retinotomies. Although a largerperipheral retinotomy may be more difficult tomanage, the greater preservation of retinal functionis usually worthwhile. Circumferential relaxingretinotomies are usually preferred over radialretinotornies. In the face of circumferential traction,a radial retinotomy that adequately relieves tractionmay extend too far posteriorly into t'entral retina., .

Surgical Method

In most cases, the area of retinotorny is made pos-terior to the area of shortened, contracted retina(Figure 8-29A). Heavy diathermy is applied to theretinal vessels and light diathermy is applied alongthe area to be cut. The incision in retina is usually

made with scissors (Figure 8-29A). To insure thatno traction remains at the margins of the retinot-orny, the retinotorny should be extended beyond thearea of contraction into noncontracted retina oneach end of the retinotomy. Figure 8-298 showsextension of the retinotomy anteriorly obliquely ateach end of the retinotomy with excision (retinec-torny) of the anterior contracted retina.

Retinectorny is usually done when membranescannot be adequately removed from extremely con-tracted retina. Figure 8-30A shows contracted retinabetween two large retinal breaks. A retinectomy

Figure 8-29. Relaxing rerinororny, A, Diathermy appliedto peripheral retina on posterior edge of contracted retina.Blood vessels occluded with diathermy prior 10 rctinororny,B, Rctinotomy followed by excision of scarred retina ante-rior to retinotomy, Retinotorny extended into normal rei inabeyond area of contracted retina.


should only be done if the retina cannot be re-attached by other methods. To perform a retincc-torny, diathermy is applied to the area of contractedretina and extended just into normal retinasurrounding the area of contraction. Excision is usu-ally done with the vitrectomy cutting instrument.Figure 8-308 shows a large retinal defect buttraction is relieved and the retina is reattached.

There are several potentially serious complica-tions of retinotornies and retinectornies. The majorcomplications are hemorrhage. inability to unfoldand reattach the retina, hypotony. visual field loss,

Figure 8-30. A, Superior retinal breaks within area ofcontracted retina. B, Rerinecromy of focally contractedretina. Laser treatment of edges of retinotomy. Adaptedfrom Lewis JM, Abrams GW, Werner J'C, Management ofcomplicated retinal detachment. In: Albert OM, ed. Oph-thalmic Surgery: Principles and Techniques. Vol. I.Malden. MA. Blackwell Science; 1999:547.

9.. MANUAL OF RETINAL SURGERY

recurrent fibrous proliferation from the retinotomysite, and persistent traction leading to retinal detach-ment when the retinotomy is too small. While care-ful planning and technique will prevent some of thecomplications, the potential seriousness of the com-plications means that relaxing retinotorny andretinectomy techniques should be used only if othertechniques are unsuccessful.

Once the retinotorny is made, the retina may foldposteriorly like a giant retinal tear. It is best to makethe retinotomy with the posterior retina held inplace by PFCL, with the retinal incision anterior tothe level of the PFCL. Once all traction is relievedand hemostasis is achieved, more PFCL is injecteduntil the level of the PFCL is anterior to the marginof the retinotomy. We usually do laser treatmentwith PFCL in the eye, then remove the PFCL with aPFCL-air exchange. There is a risk of slippage ofthe edge of the retinotomy posteriorly during thePFCL-air exchange. In order to prevent slippage, itis important to "dry" the edge of the retinotomybefore proceeding with the PFCL-air exchange. Wedry the edge by holding the soft silicone tip of thebackflush brush just anterior to the edge of theret inotorny in the initial portion of the PFCL-airexchange. This allows removal of fluid that maycollect beneath the edge. If not removed. this fluidcan be pushed posteriorly by the air and force theedge of the retina posteriorly, creating folds poste-rior to the edge of the retinotomy. Alternatively, aPFCL-silicone oil exchange can be done instead ofa PFCL-air exchange. There is less risk of slippageof the flap with the PFCL-silicone oil exchange.

Intraocular Gases

Intraocular gases are used in vitreous surgery to. tamponade retinal breaks. In eyes without signifi-cant retinal traction, air. which only persists in theeye for a few days. is useful. In eyes with tractionalcomplications, gases that persist in the eye longerthan air are useful for a prolonged retinal tampon-ade. The longer-acting gases are useful for tWOpur-poses: (I) to tamponade retinal breaks until anadhesion forms between the retina and the retinalpigment epithelium, and (2) to provide "retinal tam-ponade." in which the retina is held in place againstthe retinal pigment epithelium until widespreadlaser photocoagulation adhesions form. The latter

indication has found widespread application withthe use of long-acting gases in the treatment of pro-liferative vitreoretinopathy. In eyes with prolifera-tive vitreoretinopathy. there is often minor retinaltraction remaining following removal of epiretinalmembranes. Sometimes a long-acting gas bubblecan overcome minor residual epiretinal tractionuntil the retina becomes permanently adherent tothe underlying tissue following photocoagulation.

Besides air, the major gases used are sulfur hexa-fluoride (SF

6) and perfluoropropane (PFP or C3Fg).

An effective gas bubble is one that fills at least 50%of the vitreous cavity, which will maintain tampon-ade of the inferior retina when the patient is in theprone position. An eye filled with air will maintainan effective gas fill for only a few days. An eyefilled with SF

6will maintain an effective tampon-

ade for approximately 7-10 days. An eye filled withC

3F

ggas will maintain an effective tamponade for

at least 3 weeks or more.Longer-acting gases have in common a high

molecular weight, low diffusion coefficient, andlow water solubility. When these gases are injectedin a pure form into the vitreous cavity, they willexpand due to the infusion of nitrogen and otherblood gases into the gas pocket. A pure SF h gasbubble injected into the vitreous cavity will expandapproximately 2.5 times its injection volume. Apure C

3Fg gas bubble will expand approximately 4

times its injected volume. Both gases expand atapproximately the same rate. There is risk of ocu-lar hypertension and vascular occlusion when puregases are used during vitreous surgery. Because ofthe risk of ocular hypertension. we prefer to use"nonexpansile" gases at surgery. For use in vitreoussurgery, 20% SF

6and 14% PFP are essentially non-

expansile and safe.Intraocular gases are injected at the end of the

procedure following reattachment of the retina witha fluid-air exchange. We inject the gas by themethod of air-gas exchange. At the completion ofthe procedure. the two instrument '~clerotomy sitesare completely closed. Approximately 40 cc of theselected gas mixture are flushed through the air-filled eye through the infusion port and vented by a27-gauge needle inserted through the pars planainto the vitreous cavity. The needle is attached to atuberculin syringe from which the plunger has beenremoved to form a "chimney" to allow the egressof the flushed gas. The eye may need to be

reformed with the gas mixture to a normal intraoc-ular pressure following removal of the infusion portand closure of the last sclerotomy site.

The major risk of the use of intraocular gas isocular hypertension. By using a nonexpansile con-centration of the gas, the risk of ocular hypertensionis markedly decreased. Intraocular pressure andlight perception can be checked 2-4 hours aftersurgery since the intraocular pressure of an ex pan-sile bubble tends to peak at approximately this time.We give topical ocular antihypertensive medica-tions at the conclusion of surgery. Some surgeonsalso use oral acetazolamide through the first post-operative night. Special attention is given to highrisk eyes, including eyes with pre-existing glau-coma. hyperopic eyes, eyes with scleral buckle, andeyes with extensive laser panretinal photocoagula-tion at surgery. It is important to position the patientprone or on one side to prevent pupillary block bythe gas bubble. There is risk of cataract formationif the gas bubble stays in prolonged contact with thelens of the phakic eye.

Silicone Oil

Silicone oil is useful in the treatment of prolifera-tive vitrcorctinopathy, giant retinal tears, some eyesof diabetics with complicated retinal detachmentsor with severe anterior segment neovascularization.The silicone study showed no significant differencebetween C3Fg gas and silicone oil in managementof eyes with PVR. Eyes managed with gas had aslightly higher retinal reattachment rate than eyesmanaged with oil in eyes that had not had a previ-ous vitrectorny (group 1 eyes). However there wasno difference in the percent of eyes with visualacuity of 5/200 or better and there was no differ-ence in either retinal reattachment rate or visual

Iacuity in eyes that had had a previous vitrectomywith gas (group 2 eyes). Hypotony, lOP 55 mm Hgwas more common in gas eyes than oil eyes,whether the retina was attached or not and whetherthe eye had had a previous vitrectomy with gas ornot. Eyes with large retinotomies did better with oilthan gas. Longer tamponade provided by C3Fg gasor silicone oil was preferable to the shorter tam-ponade provided by SF6 gas. Silicone oil wasremoved from most eyes with attached retinas.nor-mal intraocular pressures, clear corneas, and better


visual acuities. Conversely, silicone oil was lesscommonly removed from eyes with detached reti-nas, poorer visual acuities, corneal abnormalities,and hypotony. Eyes managed with silicone oil thathad the silicone oil removed had better outcomesthan eyes with oil retained or eyes managed withgas. Silicone oil is preferred over gas in patientsunable to maintain a prone position after surgeryand for patients that need to fly in an airplane ortravel to a higher altitude. Gas may be preferred ineyes with residual hemorrhage, eyes without an-adequate iris diaphragm, and eyes with retinalbreaks on the posterior slope of very high scleralbuckles. In the latter instance, because the siliconeoil bubble might not conform to the shape of thehigh scleral buckle, the retinal breaks might not beadequately closed.

In diabetic retinopathy, silicone oil may be use-ful in eyes with severe anterior segment neovascu-lar complications, including neovascular glaucomaand anterior hyaloidal fibrovascular proliferation.High vascular endothelial growth factor levels havebeen documented in the anterior chamber of eyeswith neovascularization of the iris. The silicone oilmay block the circulation of such growth factorsinto the anterior segment. In addition, oil may beuseful in some eyes of diabetics with complicatedretinal detachments requiring extensive retinot-omies. These eyes are often very ischemic, so thevisual prognosis is poor, but such eyes can some-times be stabilized with silicone oil.

Silicone oil may be helpful in eyes with gianttears or giant rctinotomies. Most giant retinal tearsare repaired with vitrectorny and unfolding of theflap of the giant tear with PFCL. When the PFCLis removed and exchanged for air, the edge of thegiant tear can "slip" (slide posteriorly), creating aretinal fold posterior to the tear. This slippage isproduced by fluid collection behind the anteriorretina that may not be fully reattached by the PFCL.As the air goes into the eye, it can force the fluidposteriorly, creating the slippage and the fold.Directly exchanging the PFCL for silicone oil willusually prevent slippage of the flap. Because thebuoyancy of the silicone oil is less than that of air,there is less force applied to the retina as the sili-cone oil is infused, and there is less tendency toforce subretinal fluid posteriorly. Silicone oil maybe advantageous if there is proliferation of mem-branes that apply traction to the retina following


giant tear repair. The silicone oil tends to localizerecurrent retinal detachment due to proliferativemembranes and these eyes can sometimes be man-aged with a relatively simple membrane peelingprocedure under silicone oil or after silicone oilremoval. Eyes managed with gas are more likely tototally redetach if proliferative membranes form,especially if a retinal break is present.

Silicone oil is injected using one of two tech-niques. ln the most commonly used technique, theretina is reattached with a fluid-air exchange or,alternatively, with PFCL. We usually apply lasertreatment under PFCL or air, prior to silicone oilinfusion. If PFCl is used, the PFCl is exchangedfor air. The silicone oil is infused into the air-filledeye. In this method, the silicone oil is pumped intothe eye to fill the vitreous cavity to the level of theiris diaphragm. The anterior chamber is left filledwith fluid or air. The second method is by PFCL-silicone oil exchange. As the silicone oil is pumpedinto the eye with a silicone pump, the PFCl is pas-sively evacuated with a fluted needle with back-flush capability. Perfluorocarbon liquid-silicone oilexchange is more easily done with 1000-centistokesilicone oil than with SOOO-centistoke silicone oil.Any subretinal fluid beneath the peripheral retinacan be removed with a backflush brush held at anyanterior retina! breaks. The backflush capability ofthe needle allows easy release of the retina. Wemost commonly use PFCL-silicone oil exchangewhen there is a giant retinal tear or retinotorny morethan 270 degrees in circumference. when there is arisk of posterior slippage of the flap. This is also auseful technique if a silicone IOl is present. Withair or gas in the vitreous cavity. there is condensa-tion on the posterior surface of the silicone IOl thatobscures the view of the vitreous cavity. While theview is better when silicone oil is used. the silicone'oil adheres to the [Ol and obscures the view if thesilicone oil is removed. The IOL must be removedif the silicone oil is removed.

There are several potential complications of sili-cone oil. The major complication is corneal dam-age, which occurs when silicone oil is in contactwith the endothelium. Retrocorneal membranesform and band keratopathy is common. Cornealcontact by the silicone oil can be prevented in "theaphakic eye by creating an in ferior iridectomy.When silicone oil remains in contact with the lens, afeathery posterior subcapsular cataract is produced.

With prolonged silicone oil-lens contact, a perma-nent cataract will form in all cases. Therefore, if sil-icone oil is used in phakic eyes, it should beremoved as soon as possible (usually within 4-6weeks).

Glaucoma can result from emulsification of thesilicone oil. Small bubbles can pass into the ante-rior chamber and obstruct the trabecular meshwork.Emulsification is most commonly seen when thereis substantial movement of the silicone oil associ-ated with a loose iris diaphragm. Emulsification isprobably also more common with mixed siliconeoils of various molecular weights and densities. Useof purified silicone oil reduces the incidence of thiscomplication. Emulsification is more common withWOO-centistoke silicone oil than with the SOOO-cen-tistoke variety. If emulsification is seen. the siliconeoil should probably be removed because of the riskof glaucoma.

Proliferation of fibrous tissue that is sometimesseen with silicone oil is most commonly associatedwith large retinotomies or retinectornies and isaccentuated by the presence of preretinal blood. Ifrecurrent membranes are seen following silicone oilinjection. the membranes should be removed andthe silicone oil evacuated from the eye. if possible.

·0"\

Giant Retinal Tears

Giant retinal tears are retinal tears greater than 90degrees in circumference. Giant retinal tears areunique among retinal detachments because the flapof the retina posterior to the giant tear may fold pos-teriorly and may be difficult to return to its normalposition. Giant tears are usually repaired surgicallywith vitreous surgery. The goals of the surgery areto rei ieve retinal traction. unfold the flap of thegiant tear if necessary. and create a retinal adhesionbetween the tom retina and the underlying retinalpigment epithelium (RPE), usually with laser pho-tocoagulation. It may be necess'iry to removeepireti nal or subretinal membranes and place ascleral buckle.

Surgical Technique

If PVR is present, we remove the crystalline lens,even if clear. For giant tears without PVR, we usu-ally retain the [ens if the tear is less than 180

degrees, but remove the lens in larger giant tears. Ifthe lens is retained we usually place a scleralbuckle, because there may be residual anterior vit-reous that may be associated with postoperativeanterior traction. However, if the lens is removedand there is no significant PVR, it may be possibleto avoid a scleral buckle because it is possible toremove mostof the anterior vitreous, thus avoidinganterior traction. We remove the vitreous gel andcarefully remove anterior vitreous. A wide-angleviewing system is helpful for the anterior portion ofthe vitrectorny, and scleral depression will help withanterior vitreous removal. If there is PVR present,

Posterior Segment Vitrectomy : 97

we then remove epiretinal membranes starting atthe posterior pole, progressing <Interiorly. After weremove posterior membranes, PFCL can be injectedto stabi Iize the posterior retina as anterior mem-branes are removed (Figure 8-28A). We usuallyexcise nonfunctional retina anterior to the giant tear,and make sure all vitreous and membranes areremoved at the ends of the giant tear. Followingremoval of all membranes if present, the PFCL canbe injected to unfold and flatten the flap of the gianttear (Figure 8-31 A). If the flap is mobile. the PFCLcan be injected until the level is anterior to the levelof the tear (Figure 8-31 B). If the edge is folded,

Figure 8-31. Management of giant retinal lear or rctinoiorny with PFCL. A, Retina reattached from posteriorly to anteri-orly with PFCL. This unfolds flap of gi.mt tear. B, After retina attached, fluid-air exchange. "Drying" edge of giant tear byaspirating fluid frum beneath anterior edge of tear will prevent posterior slippage of flap of tear. C, Continuation of fluid-air exchange without posterior slippage of edge of tear. Adapted from Abram' GW, Gentile RC. Vitrectorny, In: Guyer DR,Yannuzzi LA, Chang S, Shields JA, Green WR, eds. Rt'lina-Virrcous-MaCltla. Vol. 2, Philadelphia: W,B. Saunders:1999: 1309.


PFCL should remain posterior to the folded edge ofthe retina. The anterior folds can usually beunfolded with the illuminated pick and forceps.However, in the event that the edge is so folded and'fixed that it cannot be completely freed, the foldededge should be excised with the vitreous cutter. Weapply endodiathermy to the area to be excised toprevent bleeding. After the edge is attached withPFCL, we apply two or three rows of laserendophotocoagulation to the edge of the tear. Wealso treat the untorn anterior retina with two or threerows of laser in a scatter pattern. A scleral buckle ismore likely needed for smaller giant tears thanlarger tears. The scleral buckle is used to supportthe ends of the giant tear and the untorn retina. Ifthere is no PVR and a lensectomy has been done, itmay be possible to remove enough vitreous torelease all traction on the retina. For giant tears lessthan 270 degrees, if a lensectorny is not done. weusually place a scleral buckle. A scatter pattern oferidolaser photocoagulation is placed on the retinasupported by the scleral buckle. If a scleral buckleis anticipated, we prefer to preplace the mattresssutures in the sclera prior to the vitrectomy assuture placement is easier and safer at that time. Weusually usc an encircling band, 3.5--4.0 mm wide,but wait until the vitrectomy is complete and theretina is attached before placing the buckle aroundthe eye. A low buckle is usually desirable to preventposterior slippage of the retina and radial folds.

We remove the PFCL with a PFCL-air (Figure8-31 C) or PFCL-silicone oil exchange. If a PFCL-air exchange is done, it is important ro "dry" theedge of the giant tear in the initial portion of theexchange as mentioned previously (see Figure8-31 B). If silicone oil is to be used in the aphakiceye, we create an inferior iridectomy prior toremoving the PFCL. The decision to use silicone oilor gas depends on a number of factors, includingsurgeon preference. We mentioned indications forsilicone oil when discussing the silicone study pre-viously. Those indications are similar for gianttears. Eyes with giant tears and PVR generally do

.better with silicone oil than gas; however, thosewithout PVR probably do equally well with oil orgas. Silicone oil requires less strict prone position-ing and may prevent total retinal detachment ifmembranes proliferate postoperatively. Patients areable to travel to high altitudes and fly with siliconeoil present, but not with gas. Silicone oil must be

removed, while gas is absorbed spontaneously. We'usually remove silicone oil within 6 weeks to 3months following surgery.

Membrane Removal ill Diabetic Retinopathy

Clinical Appearance and Indications

Fibrovascular proliferation in diabetic retinopathyorigin;ltes from focal epicenters on blood vessels ofthe optic nerve head and the retina. Fibrovasculartissue grows as a sheet in the potential spacebetween the retina and the vitreous. Contraction ofthe fibrovascular tissue may cause contraction ofthe vitreous that may exert traction on the new ves-sels, causing hemorrhage. Hemorrhage usuallyoccurs from tearing of the blood vessels within thernernbrane. Traction retinal detachment may occurand retinal breaks can occur adjacent to areas oftraction, causing a traction-rhegmatogenous retinaldetachment. The goal of diabetic vitrectorny is toclear the media (remove hemorrhage) and to releasevitrcoretin:.lltraction. There are two major elementsto the traction in diabetic retinopathy. The first isAP traction from contraction of the vitreous withtraction transmitted from the vitreous base periph-erally to the area of the fibrovascul:.lr membranesposteriorly where vitreoretinal adhesion is present.The second form is tangential traction, which isprirnarily posteriorly in areas of posterior fibrovas-cular membranes. Posterior tangential traction isdue to contraction of fihrovascular membranesbetween the epicenters of fibrovascular prolifera-tion. The traction is transmitted via the fibrovascu-lar mcmbranes and [he partially detached posteriorhyaloid.

Surgical Technique

We separate the posterior hyaloid and the associatedfibrovascular tissue as a single unit from the retinalsurface whenever possible, using atechnique called"en bloc" excision of the diabetic membranes andthe associated posterior hyaloid. We perform an ini-ti:.ll partial vitrectomy to remove the posteriorhyaloid adjacent to the fibrovascular tissue (Figure8-32). We usually remove the posterior hyaloidtemporal to the posterior pole, as well as the vitre-ous posterior to the temporal sclerotomy site where


nation, endodiathenny, and a blunt 3D-gauge can-nula on the end for aspiration to hold the tissue dur-ing dissection and to displace blood from the retinalsurface so the source of hemorrhage can be identi-fied and treated with endodiathenny. For excisionof membranes from the retina, we use the MPCscissors (Alcon Laboratories, Fort Worth), or alter-natively, the horizontally cutting Sutherland scis-sors. The hyaloid is initially separated from theepicenters using an illuminated membrane pickand/or the closed tips of the scissors. The posterior.hyaloid between the epicenters will strip cleanlyfrom the retina, exposing the epicenters. The epi-centers are then cut parallel to, and flush with theretinal surface (Figure 8-33A). We elevate themembrane during cuning with the aspiration func-tion of the tissue manipulator. This allows biman-ual removal of the membranes and enhancesvisualization of the epicenter of the membrane.Alternatively, illuminated forceps or picks can beused to elevate membranes. The membranes sepa-rate from the retina as the epicenters are cut, betterexposing the remaining epicenters of proliferation.Each is individually cut as it is exposed to releasethe fibrovascular membrane from the retinal sur-face. Minor bleeding sometimes occurs from thevessels severed at the epicenters, but this will usu-ally stop spontaneously. Raising the pressure in theeye by raising the infusion bottles for a short periodof time will control most persistent hemorrhage.Diathermy is applied to any persistent bleedingpoints on the retinal surface. Light direct pressure

Figure 8-33. Vitrectomy for diabetic retinopathy. A, Membrane and attached vitreous elevated with tissue manipulator asmembrane is excised with scissors parallel with the retinal surface. B, Following separation of vitreous. vitreous removedwith vitreous culler. Adapted from Lewis JM, Abrams CW, Werner Jc. Management of complicated retinal detachment.In: Alben DM, cd. Ophthalmic Surgery: Principles and Techniques. Vol. l . Malden, MA: Blackwell Science; 1999: 1309.

Figure 1\-32. Vitrcrrorny for diabetic retinopathy. Excisionof vitreous around posterior vitreorctinal adhesions.Adapted from Lewis JM. Abrams GW, Werner Jc. Man-agerncnt of complicated retinal detachment. In: Alben DM.cd. Opluhulmic Surgery: Principles GildTechniques, Vol.I. Malden. MA: Blackwell Science: 1999: 1309.

the scissors are placed in the eye. In some eyes theposterior hyaloid is only minimally separated fromthe retina and the posterior hyaloid is opened in thearea of separation. Any blood is removed from thesubhyaloid space through the limited opening. Weprefer to use the "tissue manipulator" (see Figure8-6), a multifunctional instrument with endoillumi-


can also be applied with the edge of the vitrectornyinstrument if other techniques are ineffective. Afterthe fibrovascular membrane is separated from theretina, any remaining posterior hyaloid attached tothe retina is stripped free to the far periphery. Thefibrovascular membranes and the vitreous are thenexcised using the vitreous cutting instrument (Fig-ure 8-33B). We remove remaining flbrovascular tis-sue on the retina surface by lifting the tissue withthe tissue manipulator and cutting with the scissors(Figure 8-34).

We have found complete excision of diabeticmembranes to be superior to membrane sectioningtechniques. There is less hemorrhage when the epi-centers are excised compared to cutting across (sec-tioning) the fibrovascular membranes. There is alsoless chance of occult retinal breaks being hidden byresidual fibrous tissue left behind with membranesectioning techniques. We believe that there is lesspostoperJtive hemorrhage when membrJnes areexcised rather than sectioned JS well as less risk ofmembrane reproliferation.

Ocher Techniques

A number of v itrectorny procedures have beenintroduced for macular diseases. Macular holes cannow be treated with vitrectomy (see Chapter 9).Other macular techniques have been developed for

Figure !l-34. Excision of isolated vitreoretinal membrane.Membrane elevated with tissue manipulator and excisedwith scissors parallel to retinal surface. Adapted fromLewis JM. Abrams GW.Werner I'C. Management of com-plicated retinal detachment. In: Albert OM. ed. OpllllwimicSlIrg('ry: Principles (J/l(1 Techniques. Vol. I. Malden, MA:Blackwell Science: 1<)')<): 1309.

Surgical Technique: Suhjr}\'I!(I{Neovascular /VlemhrU!1e Removal

subfoveal choroidal neovascular rnernbrane removaland foveal translocation. The indications for surgi-cal removal of sub foveal choroidal neovascularmembranes have not been well defined. Earlyreports indicate a likely benefit for patients withocular histoplasmosis syndrome (OHS), but less sofor other causes of subretinal neovascularization.The indications and outcomes of surgery for sub-foveal choroidal neovascular membranes due toOHS and age-related macular degeneration(ARMD) are being investig~l!ed in the subretinalsurgery trial (SST), a multicenter. mndomized. con-trolled clinical trial sponsored by the NatiOIlJI EyeInstitute. In addition. the SST is comparing surgi-cal evacuation of large subretinal hemorrhagesassociated with ARMD with no surgery.

Following vitrectorny, we separate the posteriorcortical vitreous from the retina. Using a 36--40-gauge sharp spatula. J small retinotorny is madeadjacent to the subfoveal choroidal ne ovusculamembrane. If no suhrctinul tluid is present. Vie

inject balanced saline solution with a m icrocunnulcthrough the retinotorny into the subretinal space toelevate the retina over the subretinal ne ovascula;membrane. If subretinul fluid is already pre senfluid injection is not necessary. The infusion botrlis raised to elevate the intraocular pressure to tem-porarily cause stasis of blood trow. We then place -blunt spatula through the retinotomy into the su -retinal space and we make an attempt to separutethe neovascular complex from the surrounding ti -sue. This is particularly important if the membraneis adherent to retinal pigment epithelium (RPEwhich can rip during removal of the membrane ar;cause a large area of RPE loss. The tip of a subretnul forceps is then placed through the retinotomy .grasp the subretinal neovascular membrane angently elevate it and separate it from its underlyirvascular attachment. There may be a single, SOl

vascular frond attached to the choroidal side of t:membrane that will separate when the membraneslowly withdrawn. Sometimes, however, the bof the membrane can be broad and adherent, cauing a significant RPE defect when the membra:and adhering RPE are removed. We maintain hi"intraocular pressure for approximately 3 minu:

and then slowly lower the lOP until the lOP is nor-malized. If hemorrhage reoccurs, we once more ele-vate the JOP for 3-5 minutes, then slowly lower thelOP. After hemostasis is confirmed, we inspect theperipheral retina for retinal breaks; if none are pres-ent, we proceed to a fluid-air exchange. We subto-tally fill the vitreous cavity with air, then close asdescribed above. Prone positioning is enforced forthe first 24 ho~rs postoperatively.

Retinal Translocation with360-Degree Retinotomy

Retinal or foveal translocation surgery may be use-ful for selected subfoveal choroidal neovascularmembranes. The goal of both techniques is to movethe fovea from abnormal RPE to a new positionover more normal RPE. Since these are new tech-niques. reports are limited and the indications andoutcomes are still unclear. Retinal translocationwith 360-dcgree retinotomy is used for large sub-foveal choroidal neovascular membranes and ismore difficult than the limited foveal translocationprocedure. In retinal translocation, the vitreous isseparated from the retina and the retina is totallydetached by injecting BSS transretinally with a 39-or 40-gauge cannula. It may be necessary to injectthrough more than one retinotomy to completelydetach the retina. After the retina is detached, it isquite bullous; then a 360-degree retinotomy is madeas far peripherally as possible. The rctinororny isbest made while viewing through a noncontuctwide-angle viewing system. The retina is rotated tothe desired position around the optic nerve, thenreattached with PFCL. The retinotomy is treatedwith two or three rows of laser endophotocoagula-tion. Silicone oil is infused into the eye duringfluid-silicone oil exchange and the eye is left filledwith silicone oil.

It is important to shave the peripheral vitreousflush'with the vitreous base. This is difficult in thephakic eye, so the lens is removed in most cases.Some surgeons place a posterior chamber IOL atthe time of vitrectorny, while others will place theIOL during a second surgery. Because there may berotation of 25-50 degrees, severe torsional diplopiamay result. It may be necessary to rotate the eyewith torsional muscle surgery. Some surgeons dothe muscle surgery at the same sitting as the retinaltranslocation surgery.


Limited Foveal Translocation

Limited foveal translocation is used for smallersubfoveal choroidal neovascular membranes. Priorto vitrectomy, we preplace five or six mattresssutures so as to cause superotcrnporal circumferen-tial, equatorial imbrication of the sclera over anarea of approximately 120 degrees, when thesutures are tightened following vitrectomy. Onesuture is placed just nasal to the superior rectusmuscle, four sutures are placed in the superotern-poral quadrant, and one suture is placed just infe-rior to the lateral rectus muscle. During thevitrectorny procedure, the vitreous is separatedfrom the retina. thcn the retina is detached byinjecting BSS transretinally with a 40-gauge can-nula. We limit the artificial retinal detachment tothe temporal 180 degrees plus part of the adjacentsuperonasal retina. It is important to detach themacula, as well as the peripheral retina. It may beuseful to do a partial fluid-air exchange to forcebullous retina posteriorly to aid in macular detach-ment. With the retina detached and air filling theanterior portion of the vitreous cavity. we tie theimbrication sutures. We then do additional fluid-airexchange to fill approximately 50-60'k of the vit-reous cavity with air. No subretinal fluid is drained.

Postoperatively. the patient is positioned uprightto move the retina inferiorly. The limited fovealtranslocation technique typically moves the foveafrom 200-1300 u, much less than can he attainedwith the retinal translocation with 360-degreercunoiomy technique. It may be necessary to treatthe choroidal ne ovasculur membrane with laserphotocoagulation postoperatively. Patients mayexperience transient torsional diplopia, but this usu-ally resolves in a matter of months.

Both translocat ion techn iques can be compli-cated by retinal detachment and/or PVR. Ran-domized, controlled clinical trials are needed todetermine the value of these procedures.

Other Indicationsfor Vitrcctomy

There are other important indications for vitrecrornyand vitrectorny procedures that are beyond the scopeof this chapter. Vitrectomy removal or repositioningof a dislocated IO], is an important indication. Bac-terial or fungal, exogenous or endogenous endoph-thai mitis, retinopathy of prematurity, and severe


CMV retinitis each may require specialized vitrec-tomy equipment and techniques.

Intraoperative Complications of Vitrectomy

Vitreous surgery is accompanied by many po-tential complications. some new and unique tovitreous surgery and others common to otherintraocular procedures. Complications are morecommon in severely diseased eyes. Intraoperativecomplications are classified as entrance-site com-plications. lens complications, acute ocular hyper-tension, hemorrhages. and retinal tears anddetachment. Corneal complications, postoperativeglaucoma. endophthalmitis, and sympathetic oph-thalmia will be discussed in Chapter 10. The majorentrance-site cornplications are uveal infusion andsubretinal infusion. If the infusion port fails to per-forate the pars plana pigmented or nonpigmentedepithelium. infusion fluids feed into the supra-choroidal space (Figure 8-35) or the subretinalspace. Uveal or subretinal infusion is best pre-vented by al ways ascertaining that the tip of theinfusion port has perforated the pars plana epithe-lium prior to turning on the infusion. Treatmentinvolves removing the infusion port and theninfusing fluid into the vitreous cavity through thevitrecrorny instrument or a needle (Figure 8-36).Suprachoroidal fluid escapes through the nowopen sclerotomy site.

Peripheral retinal dialysis can occur wheninstruments placed through the sclerotomy siteexert traction on the peripheral vitreous (Figure8-37). Although the incidence of peripheral dialy-sis is low when small-gauge instruments are used.

Figure 8-35. Choroidal infusion caused by incompletepenetration of pars plana epithelium by infusion port.

Figure 8-36. Drainage of choroidal infusion. Infusion portremoved to allow drainage of suprachoroidal fluid. Fluidinfused into vitreous cavity through vitreous cutter, Alter-

natively. fluid can be injected through needle,

Figure 8-37. Anterior retinal tear related to insertion ofscissors though sclerotomy. Tear caused by traction onvitreous base by scissors tip.

peripheral tears still do occur. The use of entrance-site trocars and cannulas probably reduces theincidence of entrance-site dialysis. .

Vitreous or retina can incarcerate in the sclerot-omy site. Some vitreous is probably incarceratedin the sclerotomy site at the end of surgery in mostcases. This can, on occasion, lead to intraocularfibrous proliferation and retinal traction or (atetears of the retina due to traction. It is helpful topay attention to reducing the amount of vitreousincarceration in the wounds by lowering the infu-

sion pressure before removing instruments. Vitre-ous should be removed from the lips of the scle-rotomy sites prior to closure using the vitreousculler and/or dry cellulose sponges and small scis-sors. Retinal incarceration can occur in the scle-rotomy in an eye with a bullous retinal detachmentand is best avoided by turning off the infusionbefore removing instruments. A viscoelastic injec-tion at the sclerotomy site or the use of a smoothinstrument may dislodge incarcerated retina fromthe sclerotomy site, As an alternative, the incar-cerated retina can be removed from the sclerotomysite internally with forceps or a suction needle (sil-icone tip) placed into the eye through another scle-rotomy site. PFCL injected over the posteriorretina will sometimes disengage retina from thesclerotomy site.

Corneal erosions are most common in diabeticsand appear to be less of a problem now than in ear-lier reports. Corneal epithelium should be protectedpreoperatively by using as little phenylephrine as

possible and intraoperatively by protecting thecornea from drying and trauma. Improved infusionsolutions used during surgery have probably helpedto reduce the incidence of severe cornea problemsfollowing vitrectorny. Corneal complicationsinclude recurrent erosions. (usually most severe indiabetic eyes). filamentary keratitis. and bullouskeraiopathy. Postoperative erosions are treated withpatching and emoll ierns. Persistent erosions can betreated with bandage contact lenses.

Lens damage can result from direct trauma tothe lens. This usually occurs during removal ofperipheral vitreous when an instrument comes incontact with the lens. Improvements in infusionsolutions have reduced the incidence of intraoper-ative lens opacification. The use of glucose-forti-fied BSS plus infusion has reduced the incidenceof cataract in diabetics.

The; cornea can be damaged and there can behemorrhage and iridodialysis during pars planaultrasound lensectomy. These complications arebest prevented by keeping ultrasound fragmenta-tion to a minimum and using gentle. controlledsuction when near the iris.

Intraoperative acute ocular hypertension mayproduce visually significant problems by occludingchoroidal and/or retinal vasculature. During surgerythe surgeon must be aware of the intraocular pres-


sure. The infusion bottle should not be raised to ahigh level for a prolonged period of time. Postop-erative glaucoma may result from hemorrhage,inflammation, choroidal edema, orbital hemor-rhage, pupillary block mechanisms, expansilegases, or ncovascular glaucoma. This will he con-sidered in Chapter 10.

Intraoperative or postoperative hemorrhagemay occur. Hemorrhage during vitrcctomy mayarise from iris or angle vessels. retinal vessels.retinal neovascu lar ization. or choroidal vessels.Hemorrhage is more likely to occur in a hypoto-nous eye than when the intruocular pressure is ele-vated. because the pressure gradient between [hevascular system and the eye is greater duringhypotony. Hemorrhage Gin initially be controlledby increasing the intraocular pressure by raisingthe infusion bottle. The source of he morrhug cshould be identified and treated with bipolar cndo-diathermy. Light direct pressure from the roundededge of the vitreciorny instrument can be effective.Severe uncontrolled hemorrhage may be managedwith the infusion of intraocular thrombin (IOO-ecsolution with a conccntrut ion of I ()() units per eel.Postoperative hcrnor rhag c m;IY he the result ofresidual hemorrhage from surgcry. rctui ned bloodwithin the vitreous. or continued hemorrhage frombleeding s ite s. Minor hc mnrr hag c will usuallyclear spontaneously. hut denser hemorrhage rnuyneed to he removed. Hemorrhage can sometimesbe removed with a postopcruri ve Ilu id-uirexchange or may sometimes require a vitreouswashout procedure. •

Retinal tears and retinal detachment may occurduring vitrectorny or during membrane removalprocedures. Posterior breaks. if not under traction.can be managed with air or gas injection tech-niques. Peripheral breaks do not require a scleralbuckle if all traction is relieved. If persistent trac-tion is present. an encircling scleral buckle is nec-essary. In most cases of ret inal derachmc ntassociated with vitrecrorny, a fluid-gus exchange isperformed or PFCL is injected to reattach the retina.Some form of intraocular tamponade is necessarywhen the retina is detached following vitrectomy.Tamponade with air. gas, or silicone oil is used forretinal detachments associated with vitrectomy.Retinal breaks arc trcuicd with cryopexy or laserendophotocoagularion.

Aaberg TM. Munagernent of anterior and posterior prol ifer-ative vitreoretinopathy. XLV Edward Jackson Memo-rial Lecture. Am J Ophtlwlmol 1988: 106:519.

Abrams GW. Azen SP. McCuen BW II. er al, Vitrectomywith silicone oil or long-at.:tlog gas in eyes with s~vereproliferative vitreoretinopathy: results of additional andlun~-term follow-up (Silicone Study Report I L). Arch

Ophrl",llIIol 1997: L\ 5:335-3+1.Abrams GW. Gentile RC. Vitrectomy. In: Guyer DR. Yan-

nuzzi LA. Chang S. Shields JA. Green WR. eds.R,-rilll1.Virreou.H"/Uculu. Vol. 2. Philadclphi~: Saunders:

1999: 1298-13\9.Abrams GW. Nunda S. Retinotomies and rctinectolllies. In:

Ryan SF. ed. Rerillll. Vol. 3. 3rd ed, St. Louis: Mosby:

2000.

Chang S. Low viscosity liquid fluorochemicals in vitreoussurgery. Am J Ophtl1£11mol 1987: L03:38.

Chang S. Lincoff H. Coleman OJ. Fuchs W. Farber ME. Per-fluorocarbon gases in vitreous surgery. Oplrrl1£11nwlogy

\ 985:92:65 I.Elion D. Abrams GW. vurectomy for diabetic retinopathy.

In: Ryan SF. ed. Retina. Vol. 3. 3rd ed. St. Louis:

Mosby: 2000.Lewis JM. Abrams GW. Werner JC. Management of compli-

cated retinal detachment. In: Alben OM. ed. Ooh-rlralmic Surgery: Prillciples and Practice. Vol. I.Malden. MA: Blackwell Science: 1999:531-566.

SiLicone Study Group. Vitrectomy with silicone oil or perfluo-ropropane gas in eyes with severe proliferative vitreo-retinopathy: results of a r.lJ1domizcd clinical trial (SiliconeStudy Repon 2). Arch Ol'hrlwlnlUl \9'12: 110:780--792.

Zivojnovic R. Silicone Oil in Vitreon'rilllli Surgery. Dor·drecht: Maninus :<ijhoff: 19l\7.

lO~ MANUAL OF RETINAL SURGERY

Suggested Reading

9Macular Hole Surgery

Lawrence S. Morse, Robert T. Wendel, and Peter T. Yip

Goals of Macular Hole Surgery

The surg icul gO:J! for macular hole surgery is tor~Kiliutc .m.uornic closure of the macular hole. Asfirst reported by Kelly and Wendel in 1991.1 this isachieved hy the use of viircctorny techniques torelieve .uucrior-postcrior and/or tangential tractionand the usc of retinal tamponade to facilitate reap-pro ximai ion of the ret ina to the retinal pigmentepithelium (RPE). The traction is relieved by iden-tification and removal of the cortical and posteriorhvuloidal vitreous, and removal of tangential trac-tion caused by epirerinul membranes (ERM) and/orthe internal limiting membrane (I LM) around thehole, Tamponade is provided by injection of a long-:Jcting gas. sulfur hexafluoride (SF6) or perfluoro-propane (C3FR). and strict face-down positioningfor 1-1 weeks.

Indications

IThe major indications for macular hole surgery arelisted in Table 9-1. Our indications for surgicalintervention are vision loss and the presence of afull-thickness retinal break. Clinically, we havefound very little use in dwelling on whether a mac-ular hole is classified as stage 2, stage 3, or stage 4(Table 9-1. Gass classification), Because our obser-vations that good preoperative vision, short dura-tion, and small holes are favorable predictors forboth anatomic and visual success and because the

natural history is unfavorable. we arc interveningcarlin than in the P~lSt.2

Vitreous surgery for impending macular holes(stage 1) is not considered routinely for the followingreasons: (I) difficulty in making the correct Ji~lgn()-six of impending macular holes. e) unproven thcra-pectic benefit, (3) cost and complic.nior», of surgery.(4) spontaneous recovery in many p.u icnts. and (::;)good anatomic and functional n.:sults after macularhole surgery for early full-thickness macular holes,'

The same techniques used for an idiopathic macu-lar hole can be applied 10 macular holes of other eti-ologies. Vision loss secondary to macu LIr holeassociated with rhegm;!togt.:nous retinal detachmenthas been successfully treated with macular holesurgery (MHS). Likewise. macular hole» after pncu-marie retinopexy have been managed successfullywith MHS.

Table 9-1. Indication for Macular Hole Surgery

Vision loss and presence of a f'ull-thickucxx retina! hreuksecondary 10:

a. Idiopathic macular holes

b. Macular holes associated with rhcgmaiogcnousretinal detachment

c. Macular holes after pncurnaric rcri nopc xy

d. Traumatic macular holes

e. Macular hole after macular pucker surgery

f. Macular holes associated with macular dcgcncra-iion, high myopia. adult vitclliform dystrophy.Best's disease, retinitis pigrnemosa. diabeticretinopathy, and peripheral telangiectasia

lll5


Table 9-2. Gass Classification of Macular HolesFluorescein Angiography

Faint hyperftuorescence or no abnorm"lityStages Clinical Appearance

l a, lb A yellow spot, lO0--200 P in diameter (La), or yellow ring, 200--300 pin diameter (I b) at the fovea

2 Full-thickness defect/dehiscence3 Full-thickness defect 2:400 p in diameter, a surrounding cuff of edema

and fluid, with or without pseudo-operculum4 Further development of a compkte posterior vitreous detachment,

with anterior displacement of the pseudo-operculum

Round "rea of window defect or normalWindow defect corresponding to the hole

Window defect corresponding to the hole

Traumatic macular holes frequently are associ-ated with other ocular injuries, including RPE dis-ruption and choroidal rupture. The patients usuallyare young men. Although most cases arise frompenetrating or blunt trauma; other injuries, such asindustrial laser burns, may result in a traumaticmacular hole. Experience has shown traumaticmacular holes can also be repaired with MHS.Rubin and colleagues" reported on 12 cases of MHSfor traumatic macular holes. They were able toclose 929c of the holes with one or more operationsand achieved 20/4(} or better vision in 50% of their

cases.Successful MHS has also been performed on

eyes that developed holes after macular puckersurgery, and on holes associated with maculardegeneration, high myopia, adult vitelliform dys-trophy, Best's disease, retinitis pigmentosa, diabeticretinopathy, and peripheral telangiectasia.s

Prognostic Factors

Favorable prognostic factors are listed in Table9-3. Eyes with earlier-stage holes, shorter macularhole duration, and better preoperative visual acuityhave a better prognosis for anatomic and visualsuccess (Figure 9-1)6 Kelly and Wendel \ reportedthat anatomic success rate in holes of ~ 6 monthswas 80%, for 6---24 months' duration was 74%, andfor >24 months was 22%. Postoperative visualsuccess rates declined with increasing duration of

Table 9-3. Favorable Prognostic Factors

• Preoper"ti ve VA 2:20/l 00Duration of symptoms <;I yearSmall size of macular hole <;450 pStage 2 or 3 macular hole

symptoms (Figure 9-2). Ryan and Gilbert7

reported a 95% anatomic success rate in early-stage holes (stage 2) versus 60'70 in late-stageholes (stages 3 and 4). The size of the macularhole may be the most important physical charac-teristic, as the size probably is related to duration.stage, and visual acuity."

Case Selection

Today, most eyes with macular holes are candidatesfor surgery. Relative contraindications includepatients unable to maintain prone positioning, somecases of traumatic macular hole with additional ocu-lar injuries, and long-standing or asymptomaticmacular holes. If the fellow eye is normal. conser-vative management can be discussed with thepatient. Just as obtaining consent is advised beforesurgery, the medical record should document clearlythat MHS was discussed, as were the reasons for aconservative approach. We are aware of one case oflegal action brought against a physician that allegeddelayed treatment of a macular hole. Informed con-sent should include discussion of MHS complica-tions that may arise intraoperatively as well asduring the early and late postoperative periods.

Preoperative Evaluation

Many conditions mimic a macular hole for whicheither no treatment or different surgical maneuversare needed. These conditions include epiretinalmembrane, geographic atrophy of the RPE andoverlying retina, cystoid macular edema, lamellarmacular holes, subfoveal choroidal neovasculariza·tion with a foveal cyst and intraretinal edema, andvitreomacular traction with a cystic fovea." Careful

A

c

Macular Hole Surgery 107

B

DFigure 9-\. A. Preoperative photograph of a patient with a macular hole and :W/lOO vision. B. Postoperative pl1OIographof the same patient showing a "closed" macular hole. Vision improved to 20/50. C, Preoperative fluorescein angiogram ofthe same patient showing a central hyperfluorescent window defect. D. Postoperative fluorescein angiogram of the samepatient showing partial resolution of a central hyperfluorescent window defect.

PERCENT MACULAR HOLES CLOSED

100~o

,;:6 m 6 m ->24 m ~ 24 m

A DURATION OF SYMPTOMS

VISUAL RESULTS

100~o

90%

80°/0

6 m -> 24 m ~ 24 m

B •

2:2 linesImprovement

?: 4 linesImprovement

Figure 9-2. A. Anatomic success is inversely related to duration of symptoms. Eighty percent of eyes symptomatic for 6months Or less were anatomically successful. 74% if symptomatic for 6 months {O 2 years, and 61 % of those symptomaticfor 2 years or more. B. Visual success is inversely related to duration of symptoms. Sixty-eight percent of eyes sympto-matic for 6 months or less improved by two lines or more. whereas only 26% of eyes symptomatic for 2 years or moreimproved.


clinical examination is needed to differentiate mac- .ular holes from the other pseudohole conditions.

The various stages of macular holes aredescribed according to the Gass classification (seeTable 9-2). Biomicroscopy is the most importanttechnique used to clinically evaluate macular holes.Fundus fluorescein angiography is also frequentlyused and may demonstrate an RPE window defectcorresponding to the macular hole. In addition tofluorescein angiography. other ancillary tests mayassist the physician in making a diagnosis of a mac-ular hole. The Watzke-Allen test is performed byplacing a thin slit-lamp beam directly on the retinalhole during contact-lens biomicroscopic examina-tion. The patient is asked about whether the thinvertical beam of light is interrupted at any point orwhether it simply narrows (Figure 9-3). An inter-ruption in the light beam perceived by the patient isa positive Watzke-Allen sign and is useful in diag-nosing the presence of a macular hole. A normal-appearing or only narrowed beam is a negativeresult. The Watzke-Allen sign. however, is of vari-able consistency particularly in stage 2 macularholes with small retinal dehiscences.

The laser aiming beam spot is also a useful testfor assessing the presence or absence of a full-thick-ness macular hole." The patient is seated at the laserapparatus with a fundus contact lens in place. TheSO-IJ aiming beam is used to test central areas of theretina focally for visual sensitivity. The inability ofthe patient to perceive the spot in the area of pre-sumed macular hole is strong evidence for the lackof retinal tissue in that location. In concert with 3

positive Watzke-Allen sign, this is strong evidencefor the presence of a full thickness macular hole.

Figure 9-3. Diagram that was given to the patient to deter-mine results of Watzke-Allen sign testing. Choices forresponse were break (righr). thinning (middle). and nobreak (/ejt). (Reprinted with permission from Martinez J,Smiddy WE. Kim 1. Gass JDM. Differenriating macularholes from macular pseudoholes. Am J Opluhalmol1994; 117:762-767.)

Ocular coherence tomography (OCT) is a newdiagnostic imaging technique for high-resolutionimaging of the human retina. to Cross-sectional imagesof optical reflectivity can be obtained with 10-11longitudinal resolution. This degree of resolution issuperior to that of other currently available diagnosticinstruments. The high-resolution, cross-sectionalimages can provide useful clinical information in thedifferential diagnosis and staging of macular holes.

Surgical Technique

Vitrectomy

MHS usually is performed under local anesthetic onan outpatient basis. Instruments necessary for MHSare listed in Table 9-4. The vitreous surgery is doneusing standard 20-gauge three-port incisions withinfusion cannula, endoillumination, and vitrectornyprobe. The vitrectomy proceeds from anterior toposterior. After surgical removal of the anterior andmid vitreous, it is necessary to identify and removethe attached posterior cortical vitreous.

Separation of the posterior hyaloid from th, . _..-031 surface is difficult because of the three ch.i-nc-teristics of posterior cortical vitreous: its softness,transparency. and tight adherence to the retina.Because of its softness, the cortical vitreous cannotalways be removed in a single sheet. It may frag-ment into multiple pieces, therefore requiring amore tedious effort from the surgeon. Because of itstransparency, the cortical vitreous is close to invisi-ble when it is attached to the retina. Lastly. becauseof its tight adherence to the retina, high suctionforces have to be used.

Table 9-4. Instruments Used for MacularHole Surgery

• 33-gauge tapered needleSoft silicone tip needle (GrieshaberjIlluminated pick (Grieshaber) ,Tano membrane stripper (Syncrgetics)Asymmetric forceps (Synergerics)Michels pickRice ILM elevator (Synergetics)ILM forceps (Grieshaber)Membrane forceps/Eckardt (DORe)

• Morris viscoelastic injector

To detect and engage the transparent and tightlyadhered posterior cortical vitreous, a soft-tipped sili-cone extrusion needle can be used. Using active aspi-ration (150-250 mm Hg) with elevated infusionbottle, the silicone-tipped suction cannula is gentlyswept over the retinal surface near the major arcades,around the optic nerve or temporal to the macula.The area immediately around the macular hole isavoided because the cuff of the hole is mobile andcan be easily incarcerated into the port. When thesoft silicone tip engages the cortical vitreous, it isnoted to flex. This has been termed the "fish-strikesign" or "divining rod sign" (Figure 9-4). The flexionis typically apparent before the vitreous fibers can beseen. This suction maneuver is safe as long as the vit-reous cortex is still present, because the vitreousplugs the port and prevents retinal incarceration andsubsequent tearing. However, if the cortex has beenunknowingly detached intraoperatively or preopera-tively (stage 4 hole), the retina can be aspirated intothe port and tom. Once the posterior cortical vitreousis engaged, a posterior vitreous detachment (PVD)can be created with continued suction with anterior-posterior and tangential traction, while moving thetip over the retinal surface. This can also be facili-tated by the combined bimanual use of a lighted pickand the soft silicone tip aspiration needle to gentlyelevate the posterior hyaloid from the retinal surfacein a very controlled fashion.


A faster and easier method to remove the p~ste-rior vitreous hyaloid is to use the vitreous cutter seton "suction only," directing the port posteriorly andgently sweeping over and around the optic nerveuntil cortical vitreous fibers are visualized stream-ing into the port. The cutter's larger port engagesthe vitreous more firmly and is more efficient atpeeling the cortex from the optic nerve. Once thishas been accomplished, the vitreous will usuallyseparate easily to the posterior vitreous base. Cau-tion should be exercised once the vitreous has sepa-rated from the posterior pole, as retinal tears maydevelop with excessive traction.

Once the posterior hyaloidal dissection has beeninitiated, the vitreous cortex becomes visible as athickened translucent sheet, especially with obliqueillumination. Occasionally, the nasal or disc attach-ments are so firm that the vitreous cutter (on suc-tion only), tissue forceps, or pick manipulation isrequired to complete the PYD in these areas. It iscommon to create small disc and retinal hemor-rhages during this process. Frequently, a pseudo-operculum can be detected as a luteal-coloredfragment attached to the vitreous cortex. A ring ofcondensed vitreous (Weiss' ring) is observed overthe disc corresponding to previous vitreopapillaryattachments. Vitreous cutting should be limiteduntil a complete PYD is present to avoid leavingislands of attached posterior cortical vitreous. Once

Figure 9-4. Soft-tipped silicone suction needle flexing as it engages the cortical vitreous-the "fish-strike" sign.


the vitreous is completely detached, the vitreouscutter is used to complete the vitrectomy. If resid-ual attached vitreous cortex is present in the poste-rior pole, it becomes apparent during completion ofthe air-fluid ex.change as a gelatinous substance onthe retinal surface.

ERM Removal

Histopathologic studies have shown that the major-ity of macular holes studied postmortem have asso-ciated epiretinal membranes (ERMs). AlthoughERMs typically appear with later-stage holes andholes of longer duration, they are also common instage 2 holes.

These ERMs are unlike typical ERMs fromother causes. They tend to be finer and more friableand at times are densely adhered to the retina. Itmay be difficult to distinguish an ERM from inter-nal limiting membrane (ILM) contraction. Often weuse a bent microvitreoretinal (MVR) blade or Tanomembrane scratcher to create an edge in the ERM,allowing the introduction of a membrane pick. Thefree edge is grasped with diamond-dusted intraocu-lar tissue forceps and stripped. The ERMs may sur-round the hole for 360 degrees or can involve onlya few clock hours. If present for 360 degrees, theyare often tightly adhered to the edge of the hole. Attimes, this attachment requires cutting to avoid tear-ing the edge of the hole.

During this maneuver, it is common to createnumerous small hemorrhages around the hole. Cau-tion is needed to avoid damaging the inner retina;an early sign of which may be the development offluffy whitish areas. To avoid phototoxic injury,care is taken to avoid prolonged intense illumina-tion from the light pipe held near the macula.

Internal Limiting Membrane Removal

In the absence of a significant amount of ERM thatcould be removed, some investigators advocate theremoval of the ILM to increase the success rate in .closing macular holes." This modification in surgi-cal techn ique to intentional removal of ILM hasbeen controversial. The advocates of this techniquehypothesize that the greater success in closing mac-ular holes with this modi fied technique is because

the removal of the ILM mobilizes the retina aroundthe macular hole so that it is more flex.ible or elas-tic, In one nonrandornized, controlled study, II 98%of the macular holes were successfully closed withthis technique, while only 70% among the controleyes were closed. Additionally, there appeared to beno damaging effect on the vision from the inten-tional removal of the ILM.

The first step of ILM removal is puncturing ILMwith a sharp-tipped MVR blade in the superiormacula (Figure 9-5A), about I disc diameter awayfrom the macular hole in an II o'clock position inboth right and left eyes. Once the ILM is puncturedthe MVR blade is withdrawn from the opening. Toassist in visualization of the ILM, Tornarnbe hassuggested using intrav itreal Indocyanine Green(leG) dye, which binds to the ILM and facilitatesits visualization intraoperatively (personal commu-nication).

The Rice ILM elevator or Michel's pick is intro-duced. with the tip directed· tangentially into theopening in the ILM and beneath it (Figure 9-58).The elevator is advanced slightly in an effort toengage only the ILM and not the nerve fiber layer(NFL). Positioning the ILM elevator in the properplane often is very difficult and sometimes takesseveral minutes of advancing the tip slightly andwithdrawing it if it is not beneath the ILM or if itpasses into the NFL. Once the proper dissectionplane is established, the ILM elevator is advancedin a clockwise or counter clockwise direction (Fig-ures 9-5C,O). Every effort is made to tunnelbeneath the ILM, creating a pocket, and not to cre-ate a broad-based sheet of dissected ILM. An inter-mittent slight lifting motion is used to lift the ILMoff the NFL ahead of the instrument tip, to avoidburrowing the tip into the NFL. The ILM is oftennot visible over the instrument tip, but a slightmovement of the retina in the direction of the ILMelevator indicates that it has been engaged. TheMorris viscoelastic injector can .also be used tofacilitate ILM removal by using' a' viscoelastic todissect the ILM from the retinal surface mechani-cally (personal communication). Once the ILM iselevated off at least from one side of the macula, itcan be grasped with ILM forceps and peeled off therest of the central macula, including the margins ofthe macular hole (Figure 9-5E). The ILM is thengrasped more centrally and gently separated fromattachments to the margins of the hole.

Macular Hole Surgery III

Figure 9-5. A-E, Internal limiting membrane removal.

Air-Fluid Exchange

After careful examination of the peripheral retina forretinal tears with an indirect ophthalmoscope. a total

air-fluid exchange is performed. Because dehydrationof the retinal surface may be associated with visual fielddefects following macular hole surgery, we no longerwait to exhaustively remove all of the intraocular fluid.


Once all fluid has been removed over the disc, theresidual fluid in the base of the macular hole is aspi-rated using a 33-gauge metal tapered-tip aspirationneedle. Care is taken to avoid "bumping" the RPE.The edges of the macular hole will tend to remain onthe pigment epithelium as this is completed. Fre-quently, the edges appear to slide closer together atthis stage: this is considered a good prognostic sign.In apparent eccentric stage 2 eyes, no attempt ismade to drain the fluid in the base of the hole, forfeur of causing progression of the hole to stage 3.

Tamponade

Long-Acting Gas

A nonexpansile concentration of long-acting gas ise xchung ed for the air. We have most frequentlyused 20% sulfur hexafluoride (SF 6)' althoughlonger-acting gases such as perfluoropropane (Cl g)have been used in cases in which compliance withprone positioning is difficult. Thompson et al.12

have reponed anatomic success in 5390 of patientsin which air alone was used versus 97% in whichl6% CJF g was used. The visual success rates were20% and 62%, respectively. A subsequent study!Jshowed that the success rate with 5% and 10% ofCJFg (shorter-acting bubble) was only 65% as corn-pared to 94% with 16% CJFg, Recently. Park et al.':'have reported good surgical results with the use ofintravitreous air, along with a shorter 4-day dura-tion of strict face-down positioning. Tomambe hasalso reported good surgical results using long-act-ing gas without face-down positioning. It is impor-tant, however, to realize that face-down positioningtheoretically increases the buoyancy effect of gasbubbles that may augment the surface tensioneffects of intraocular gas tamponades that in tummay enhance anatomic closure of macular holes inmost patients.

In those unusual situations in which generalanesthesia is used, it is critical that administrationof nitrous oxide be stopped at least 15-30 minutesbefore air-gas exchange.

Silicone Oil

In patients who are either unable or unwilling tocomply with the strict I-week face-down position-

ing postoperatively, liquid silicone can be usedinstead of long-acting gas as an extended intraocu-lar tamponade. However, silicone oil tamponadehas two disadvantages: (l) an increased potentialfor cataract formation, and (2) it requires a secondsurgery to remove the oil.

After the fluid-air exchange is performed, an air-silicone oil exchange is performed by injecting sili-cone into the air-filled eye (with the air pump on)until silicone oil reaches the level of the sclerot-omies or the posterior surface of the lens or intraoc-ular lens. Then, the infusion cannula is removed andthe sclerotomies are closed. The final intraocularpressure is left between 10 and 15 mrn Hg.

The patients are asked to maintain a face-downposition as much as possible until the morning ofthe first postoperative day, following which they areinstructed only to avoid extended supine position-ing. They may return to normal light activity on thefirst postoperative day, but are cautioned to avoidstrenuous physical exercise.

The silicone oil can be removed 4--8 weeks post-operatively. Oil removal is accomplished either bypassive efflux through a cannula or by active aspi-ration through a 19-9auge. \-inch needle. The eyeis meticulously examined for small droplets ofresidual silicone that are removed through a 19-gauge, thin-walled needle.

Adjuvants

Histopathologic studies have demonstrated thatwith macular hole resolution after MHS, the edgesare reapproximated, and the residual defect filledwith fibroglial cells. IS Furthermore, the pseudo-operculum has been demonstrated in some cases toconsist of fibroglial elements rather than photore-ceptor elernents.!" The rationale for using adjunc-tive therapy regimens is the stimulation of fibroglialproliferation to close the hole reproducibly, avoid-ing trauma to adjacent functional retinal elements."Therefore, adjunctive therapeutic interventions,including biological tissue adhesive, transforminggrowth factor-beta2 (TGF-~2)' autologous serum,and autologous platelet concentrate, have beeninvestigated to improve success rates in macularhole surgery. The adjuvant is added after a fluid-airexchange has been performed and is placed onto themacular hole via a 33-gauge cannula.

There are controversies in the use of adjunctivetherapy. Success rates for macular hole surgery113.vebeen improving as a result of greater familiar-ity with surgical techniques and better case selec-tion. Anatomic success rates in excess of 90%. withparallel visual success rates, among series withoutadjunctive agents call into question the beneficialrole offered by the use of adjunctive therapies.However, the excellent surgical results in mostseries with adjuvants have been achieved withoutILM removal, whereas similar surgical successamong those without adjuvants has needed ILMremoval. Therefore, the relative ease of the surgicalprocedures for adjunctive interventions merits con-sideration of their use.

Biological Tissue Adhesive

The first adjunctive therapy reported was a biologi-cal tissue adhesive. a commercially available prod-uct composed of bovine thrombin and pooledhuman fibrinogen. Since then, other investigatorshave used the strategy of thrombin with a fibrinogen-containing substance, such as autologous plasma,or cryoprecipitate derived from autologous serum.Both series reported anatomic success rates of80'10 with higher rates of visual improvement. How-ever, because these and subsequent pilot studieswere not randomized and did not have controls.the efficacy of biological tissue adhesives is diffi-cult to judge.

Transforming Growth Factor-Beta

Some investigators have reported improved successrates in macular hole surgery using bovine TGF-~2'However, the results of a phase III, prospective,randomized. placebo-controlled trial did not showa statistically significant difference between recom-binant tGF-~2 and placebo." Consequently. furtherinvestigations have been suspended.

Autologous Serum

Autologous serum has also been investigated.While several investigators have reportedanatomic success rates ranging from 80% to 90%in uncontrolled clinical trials. nonrandomized butcontrolled pilot studies have not shown a treatmentbenefit.'?

Macular Hole Surgery I I3

Autologous Platelet Concentrate

A pilot study using autologous platelet concentratereported a 95% anatomic success rate. Subse-quently, a nonrandomized study demonstrated thatthe group that underwent autologous platelet con-centrate therapy has a significantly higher anatomicsuccess rate than the control group, 95% to 65%?Further well-controlled and randomized studies willbe required to determine the efficacy of this as anadjunct.

Combined Cataract Extraction and IntraocularLens Implantation with Macular Hole Surgery

Many patients develop cataracts after MHS. even-tually requiring cataract surgery. Therefore. in-vestigators have looked into the feasibi Iity ofcombining MHS and cataract surgery by perform-ing them sequentially in the same operative session.One initial report shows that these two procedurescan be performed during the same operative sessionwith successful anatomic results and improvementin visual acuity." The advantages of combining thetwo procedures are patient convenience. decreasedsurgical expense, and shortened time for visualrehabilitation.

Postoperative Care

Postoperatively. 24:hour-a-day strict prone posi-tioning for 1 week is prescribed (Figure 9-6). Thisis a significant trial for both patient and familymembers, and careful patient selection and preop-erative counseling is mandatory to ensure coopera-tion. Families should ·be given the opportunity toplan ahead to secure such simple items as drinkingstraws for the patient and for specialized equipmentsuch as massage tables for comfortable prone sleep-ing (Figure 9-7). Other aids that our patients havefound useful include small portable television sets,prism glasses that aid in their head-down ambula-tion and viewing, analgesics, and anti-inflammatorydrugs for back or neck pain. At times, surgery is notrecommended because the preoperative evaluationconcludes that prone positioning will be too physi-cally taxing for the patient. A possible alternativeapproach in such cases is use of silicone oil, orlong-acting gas without prone positioning.

II" MANUAL OF RETINAL SURGERY

Figure 9-6. Face-down position.

At the l-wcek visit. approx imately 50% of thegas bubble remains after use of 20% SF6· If thepatient has been truly compliant. it is common tosee ce llular debris precipit;l(~d on the cornealendothelium. W~ call this a good positioning spot(CPS) (Figure 9-8). This finding may be the onlyobjective measure of actual patient compliance withprom; positioning. In the case of primary surgicalfailure. the absence of a CPS may suggest poorcompliance as an etiology. The macula can usuallybe seen at this visit. and predictions regardinganatomic success can usually be made. If the edgesof the macular hole are flattened, anatomic successis the rule. On the other hand. if the edges are stillvixiblc and the: cull elevated, anatomic failureoccurs despite additional prone positioning.

Complications

Macular hole surgery is accompanied by the samepotential complications seen in other vitreoretinalsurgical cases. These complications may be consid-ered as perioperative (intraoperative and early post-operative) complications or late postoperativecomplications (Table 9-5).

Iatrogenic retinal breaks are a relatively commoncomplication of macular hole surgery, occurring in2-l701o of cases.P They most likely develop during'the mechanical stripping of the cortical vitreous.Gentle manipulation of the vitreous at this step willreduce this complication. The majority of the breaksare peripheral. Thus, it is important to carefullyexamine for retinal breaks prior to fluid-air ex-change (using indirect ophthalmoscopy with scleraldepression), as small breaks are easily overlookedwhen the vitreous cavity is filled with air. The reti-nal tears are treated with cryotherapy or laser andfluid-air exchange, with appropriate postoperativepositioning.

Rhegmatogenous retinal detachments have areported frequency of less than 39'0 in most largeseries. In some instances. they have been noted inup to 14-25% of the cases. Again. thorough exami-nation of the retina prior to the fluid-air exchangewill identify the retinal detachments and ensure thatall detachments are appropriately treated.

A third perioperative complication is increasedintraocular pressure. Increased intraocular pressureafter macular hole surgery has been reported in upto one-third of eyes." This effect does not relate tothe type or concentration of gas used, or the dura-tion of gas tamponade, but W<lS found to be dramat-ically higher in patients who received recombinantTCF-~2' Angle-closure glaucoma has been reportedin two studies and was treated successfully withlaser iridotomy in both instances.

Figure ')-7. Prone sleeping position.

Mucular Hole Surgery 115

Figure 9-'1. The "good positioning spot" seen on the corneal endothelium indicates appropriate postoperative patientpositioning.

Table 9-5. Complications of Macular Hole SurgeryPe r iuper-ative

a. lurrogcnic retinal breaks

h. Rhq;malogennus retinal detachments

c. lncrcuxcd intraocular pressure

d. Endophthulmiti-,

Late Pustoperutive3. Reopening of the macular hole

h. Visual field defects

c. Progressive nuclear xclerosis

d. Macular pigmentary changes

e. Cystoid macular edema

r. Vascular occlusinn: AION, BRAO, CRAO

g. Choroidal ncovuscular membrane

Late postoperative complications includereopening of the macular hole. visual field defects,progressive nuclear sclerosis, and retinal pigrnen-tary changes. Macular holes reopen in approxi-mately 2--4% of cases.~1.~~Visual field defects occurmOSTcornrnonly in the inferior Temporal location.TIle etiology of this complication is poorly under-stood, It has been speculated that the visual fieldloss may be due to nerve fiber layer damage Thatoccurs during extended fluid-gas exchange and sub-sequent retinal dehydration," or possibly damage tothe peripapillary nerve fiber bundle during the sep-aration of the posterior vitreous from the retinal sur-face. Progression of nuclear sclerotic cataracts isthe most common campi ication of macular holesurgery, as in series of vitrectomies for conditions

other than macular holes. Studies have reportedincidence of nuclear sclerotic cataract progressionin the range of 13-95% after MHS,~o Althoughthe precise etiology of the progressive nuclear scle-rosis is unknown, altered lens rnctabolisrn aftervitreciorny is believed to play a role.?" Poor posi-tioning also increases contact between the gas bub-ble and the lens capsule, which facilitates cataractformation. Other risk factors are increased patientage and increased time interval after surgery. Thiscomplication is managed by cataract surgery andlens implantation. Finally, retinal pigment epithelialchanges have been "described and have been attrib-uted to phototox icity, mechanical damage to thepigment epithelium during suction of subretinalfluid through the macular hole, and pressure effectsof the gas bubble on the choriocapillaris and pigmentepithelium during prolonged face-down position-ing.~3 Later series in which prolonged illuminationof the foveal area with the fibcroptic illuminatorwas avoided have noted this finding less fre-quently." Other rare complications included cystoidmacular edema, vascular occlusion, choroidal neo-vascular membrane, postoperative cndophthalmitis,and ulnar nerve paralysis.

Conclusion

Vitrectomy is an effective procedure for closure ofmacular hole, While a variety of modifications in


surgical technique have been reported. the samebasic principles are present in all methods used. Theffi:l\Y'I ob)ecti.'Ie i.s to remove anterior-posterior andtangential tractions, which cause a central retinaldehiscence that eventually leads to formation of amacular hole. A complete pars plana vitrectomy isperformed with elevation and removal of the poste-rior cortical vitreous. Any epiretinal membraneshould be removed. Some surgeons also advocate theremoval of the internal limiting membrane (ILM).The retinal periphery is carefully examined by indi-rect ophthalmoscopy. and a fluid-air exchange is per-formed. followed by exchange of the air with along-acting gas. In selected patients who are notgood candidates for surgery with gas, the use of sili-cone oil provides an alternative for surgical repair.

Some investigators have reported a greater than90% success rate in macular hole closure by moreaggressively peeling off the ILM at the time ofmacular hole surgery. Others have reported achiev-ing similar results by using a variety of adjuvants,including autologous serum. autologous plasma orcryoprecipitate with bovine thrombin. and autolo-gous platelet concentrate without ILM removal toimprove closure rates of primary idiopathic macularholes, as well as to close reopened holes.

Regardless of the technique used to repair themacular hole. it is widely recognized that strict post-operative face-down positioning is a successful tech-nique used by most surgeons. Face-down positioninghelps to effectively tamponade the macular hole andpromotes macular hole closure. The continualimprovement of techniques and early surgical inter-vention has indeed made this a gratifying procedure.

References*

I. Kelly NE, Wendel RT. Vitreous surgery for idio-pathic macular hole. Arch OphthalmoI1991;109:65+-659.

2. Yuzawa M. Watanabe A. Takahashi Y. Matsui M.Observation of idiopathic full-thickness macular holes.Follow-up observation. Arch Ophthalmo! 1994; 112:

1051-1056.3. de Bustros S. Impending macular holes. In: Madreperla

SA. McCuen 11BW. eds. Macular Hole: Pathogenesis.Diagnosis. (lndTrearment. Boston: Butterworth-Heine-mann; 1999:89-94.

*Buld references indicate suggested reading as well.

4. Rubin JS. Glaser BM. Thompson JT. et al, Vitrectorny,fluid-gas exchange and transforming growth factorbeta-Z for the treatment of macular holes. Ophthalmol-ogy 1(}(})~\m·.\MG-\?>4S.

5. Huang SS, Wendel RT. Vitreous surgery for full-thickness macular holes. In: Madreperla SA,McCuen II BW, eds. Macular Hole: Pathogenesis,Diagnosis, and Treatment. Boston: Butterworth.Heinemann; 1999:95-104.

6. Smiddy WE. Pharmacologic adjuncts and macularhole surgery. In: Madreperla SA, McCuen II BW,eds. Macular Hole; Pathogenesis, Diagnosis, andTreatment. Boston: Butterworth-Heinemann; 1999:105-114.

7. Ryan EH. Gilbert HO. Results of surgical treatment ofrecent-onset full-thickness idiopathic macular holes.Arch Ophthalmol1994; 112:545-553.

8. Haller JA. Clinical characteristics and epidemiology ofmacular holes. In: Madreperla SA. McCuen U BW. eds.Macular Hole: Pathogenesis. Diagnosis. and Treat-ment. Boston: Butterworth-Heinemann; 1999:25-36.

9. Martinez J. Smiddy WE. Kim J. Gass JOM. Differenti-ating macular holes from macular pseuduholes. Am JOphthalmol 1994; 117:762-767.

10. Hee MR. Puliafito CA. Wong C. et al. Optical coher-ence tomography of macular holes. Ophthalmology1995; 102:748-756.

II. Rice TA. Internal limiting membrane removal insurgery for full-thickness macular holes. In: MadreperlaSA. McCuen II BW. eds. Macular Hole: Pathogenesis,Diagnosis, and Treatment, Boston: Butterworth-Heine-mann: 1999:125-146.

12. Thompson rr, Glaser BM. Sjaarda RN. et al. EffeCls ofintraocular bubble duration in the treatment of macularholes by vitrectorny and transforming growth faclor-p~.Ophthalmology 1994; 10 l: 1195-1200.

13. Thompson Jf', Smiddy WE. Glaser BM. et al. Intraocu-lar tamponade duration and success of macular holesurgery. Retina 1996; 16:373-382.

14. Park OW. Sipperley JO. Sneed SR. et al. Macular holesurgery with internal-limiting membrane peeling andintravitreous air. Ophthalmology 1999; 106(7):1392- 1397.

15. Funata M, Wendel RT. de la Cruz Z. Green WR. Clini-copathologic study of bilateral macular holes treatedwith pars plana vitrectorny and gas tamponade. Retina1992; 12:289-298.

16. Thompson J'T, Smiddy WE. Williams GA. et al. Com-parison of recombinant TGF-P2 and placebo as anadjunctive agent for macular hole surgery. Ophthulmol-ogy 1998;105:700-706.

17. Ezra E. Wells JA. Charteris DG. et al. Macular holesurgery with and without autologous serum: a prospec-tive study of 109 consecutive eyes. Invest OphthalmolVis Sci 1996:37:5474.

18. Gaudric A, Massin P. Paques M, et al. Autologousplatelet concentrate for the treatment of full-thicknessmacular holes. Graefes Arch Clin Exp Ophthalmol1995;233:549-554.

19. Miller JH, Googe JM, Hoskins rc. Combined macularhole and cataract surgery. Am J Ophthalmol 1997;123(5):705-707.

20. Pendergast SD, Williams GA. Complications of macularhole surgery. In: Madreperla SA, McCuen II BW. eds.Macular Hole: Pathogenesis. Diagnosis. and Treatment,Boston: Butterworth-Heinemann: 1999: 155-168.

21. Freeman WR, Azen SP, Kim JW, et al. Vitrectomyfor the treatment of full-thickness stage 3 or 4 mac-


ular holes. Results of a multicentered randomizedclinical trial. The vitrectorny for treatment of macu-lar hole study group. Arch Ophthalmol 1997;115:11-21.

22. Duker JS. Wendel RT, Patel AC. Puliafito CA. Latereopening of macular holes following initial success-ful vitreous surgery. Ophthalmology 1994;101:1373-1378.

23. Kokame GT. Vitrectomy for macular hole: the ran-domized multicenter clinical trials. In: MadreperlaSA. McCuen II BW, eds. Macular Hole: Pathogene-sis, Diagnosis, and Treatment. Boston: Butterworth.Heinemann; 1999:1I5-124.

10Complications andPostoperative Management

Mark S. Blumenkranz

The primary objective of retinal reattachmentsurgery is to restore normal anatomic relationshipsbetween the neurosensory retina and the retinalpigment epithelium (RPE) by methods that resultin the maintenance or maximal restoration of cen-tral and peripheral visual function. Experiencedretinal surgeons using the techniques outlined inprevious chapters of this book can achieve thisobjective in the majority of cases with a singleoperation and a minimum number of complica-tions. Complications are undesirable for two rea-sons: (I) they may lessen the chances for retinalreattachment with a single operation (as in thecase of retinal incarceration) or (2) they may resultin reduced visual function in cases in whichanatomic retinal reattachment is achieved (as inthe case of subretinal hemorrhage). As in all surgi-cal disciplines, the most effective treatment forsurgical complications is to avoid them. By usingatraurnatic surgical technique and following estab-lished surgical principles, complications can beminimized.

Complications of retinal reattachment surgerycan be broadly grouped into those that occur in theintraoperative environment or those in the postop-erative period. The latter can in tum be classifiedinto early and late complications, with the formerbeing the major subject of this chapter.

Intraoperative Complications

Penetration with Scleral Suture

The necessity of achieving adequate length anddepth of scleral bites to produce suitable buckleheight has already been addressed in Chapter 7.Occasionally, especially in myopic eyes or thosewith localized radial staphylornata, the needle willpenetrate the choroid and pigment epithelium. Thisrisk can be reduced by using a spatula rather than aCUlling needle. In eyes in which the retina is suffi-ciently detached in that quadrant, subretinal fluidwill be released as the needle hub is withdrawnfrom the scleral pass, with immediate softening ofthe globe. If the retina is attached in that quadrant,no outward sign may occur although occasionally asmall bead of vitreous may be seen at the site. Ineither case, if blood emanates from the needle tractexternally, the suture must be immediately but care-fully removed from the tract after cutting it close tothe sclera to reduce the chance of intravitreal orsubretinal bleeding. The site should then be care-fully inspected by indirect ophthalmoscopy andtreated by cryopexy or indirect laser if there is evi-dence of a traumatic retinal tear. If there is evidenceof localized subretinaI hemorrhage, the intraocularpressure should be increased and the eye and head

119


positioned so that extension of hemorrhage into themacula is either avoided or minimized. If there isno evidence of external or internal bleeding fromthe perforation site, it is advisable to proceed withplacement of the additional scleral sutures. Careshould be taken to avoid another accidental perfo-ration in the soft, already predisposed eye. When allthe additional sutures have been placed, and theglobe temporarily buckled to restore a more normalintraocular pressure, it may be advisable to replace

"_the defective suture 1-2 rnrn beyond the first bite(either anteriorly or posteriorly) such that the origi-nal perforation site is now' encompassed in thebuckle. In some cases, subretinal fluid drainagemay no longer be necessary, although as a generalrule it is unwise to evacuate subretinal fluid forciblyfrom an inadvertent drain site, because of the riskof hemorrhage.

Rupture of the Globe Wall

Occasionally in eyes that have undergone prior reti-nal procedures, trauma. or high myopia, a gapingdefect may occur intraoperatively that results inmassive loss of vitreous and deflation. Areas of thinsclera (such as beneath the insertions of the rectimuscles) are particularly prone to this complication.In such instances the most expeditious course is tooversew the defect with a 6-0 or 7-0 absorbable oran 8-0 nylon suture if the hole is not too large. Forlarger defects the entire area can be covered with anappropriately trimmed explant held in place by hor-izontal mattress sutures secured in more normal sur-rounding sclera. The globe is then reinflated withbalanced salt solution or air and the remainder ofthe operation resumed. In rare instances, the use ofcyanoacrylate glue. processed pericardium, or banksclera may be considered.

Inability to Drain Subretinal Fluid Successfully

In some cases the surgeon may not be able to evac-uate subretinal fluid successfully or safely becauseof its shallowness in an accessible scleral site,engorgement or detachment of the choroid, nearbychorioretinal scars. or other factors. In suchinstances it is highly recommended that the surgeonrevise the operative plan and consider other tech-

niques, including conventional nondrainage and theplacement of an intravitreal gas bubble, sincedrainage complications including incarceration,retinal hole formation, and subretinal hemorrhagetend to be the most frequent and severe intraopera-tive complications.

Retinal Incarceration in the Drain Site

During the course."Qtrelea&.\:. of subretinal fluidthrough a drainage sclerotomy, the retina maybecome incarcerated in the choroidal puncture siteand occasionally prolapse externally or blowout ifthe complication is not promptly recognized. Thelikelihood of this is increased by the following fac-tors: selection of a drainage site beneath shallowlydetached retina. excessive pressure on the globe dur-ing drainage, or creation of too large a defect in thechoroid. It should be immediately suspected whenthe surgeon notes an abrupt cessation of previouslybrisk fluid drainage, often immediately preceded bya small burst of external pigment. It can be con-finned ophthalmoscopically when the retina showsstarfolds and is engaged in the underlying drain site.

Prior to the ophthalmoscopic examination. somesurgeons prefer that the drainage site be closed bytemporarily tying either the overlying buckle suture(so that the explant covers the drainage site) or thepreplaced sclerotomy mattress suture (if one wasused; see Chapter 7).

Once an incarceration has been identified, thesurgeon may attempt to reverse this by reducingpressure on the globe and simultaneously avertingand pulling the lips of the sclerotomy outward. Insome cases in which the retina is not frankly pro-lapsed externally, gentle external pressure with ablunt muscle hook or a stream of balanced salt solu-tion may be successful. In most cases these maneu-vers are unsuccessful and the surgeon mustdetennine whether a retinal hole has also been cre-ated that requires an adhesive modality such as cryo-pexy or indirect laser. In most cases of irreversibleincarceration, the site is already in the bed of aplanned buckle, so no further modification isrequired. If not, however, scleral buckling of this siteis strongly advised. I routinely apply cryopexy to allaccidental incarceration sites since, in manyinstances, it may facilitate the identification of smallretinal defects. Larger retinal defects in incarcera-

tion sites are readily recognized by the appearanceof translucent vascularized retinal tissue or a burstof liquid vitreous from the site. In some instances, alate incarceration may be created after otherwisesuccessful drainage of subretinal fluid during bucklemanipulation if the drain site has not been previ-ously closed. For this reason as well as potentialreoperation, I choose to close all drain sites with apreplaced absorbable suture such as 7-0 Vicryl. Themajor complications of retinal incarceration (asidefrom retinal breaks) are the creation of radial retinalfolds that interfere with buckling of other tears in theearly postoperative period and localized or general-ized retinal proliferation (macular pucker, starfolds,and proliferative vitreoretinopathy [PVRJ) in thelater postoperative period.

Subretinal Hemorrhage

Another complication that may occur duringdrainage of subretinal fluid is intraocular hemor-rhage, usually into the subretinal space. Factors thatfavor the development of this complication includehighly myopic eyes. actively inflamed eyes, posteri-orly selected (and midquadrant) drain sites, and theuse of overly large, sharp drainage instruments. Thelikel ihood of developing this complication can bereduced by selecting a drainage site as anterior aspossible beneath adequately detached retina in the 3,6,9. and 12 o'clock meridians, which has the effectof avoiding the drainage beds of the vortex veins andtheir immediate larger tributaries. Once the sclerot-omy has been performed, the underlying choroidalknuckle is carefully inspected (preferably with mag-nification) to ensure that there are no large choroidalvessels in the region. If any doubt exists, transillumi-nation may be used. L generally, lightly diathermizethe choroidal bed to reduce further the risk of acci-dent~ hemorrhage, although this is probably not nec-essary jf the bed has been carefully inspected andfound to be free of large vessels. The developmentof a subretinal hemorrhage from a drainage site isusually, but not always, heralded by external bleed-ing. External bleeding from the drain site mandatesthat the surgeon promptly inspect the drain site inter-nally by indirect ophthalmoscopy before proceedingfurther with drainage. If blood is seen internally atthe drain site or posteriorly, light diathermy shouldbe applied externally to the drain site, the drain site

Complications and Postoperative Management 121

closed, the intraocular pressure normalized by exter-nal pressure on the globe with a cotton-tipped appli-cator, and a new drain site selected. If blood hastracked beneath the detached macula, some consid-eration should be given to appropriate positioning ofthe globe or head so that the blood may migrate grav-itationally to an inferior extrarnacular location. Thispositioning should be continued in the immediatepostoperative period. In the case of a large submacu-lar hemorrhage in an eye with total or inferior subto-tal detachment, it may be justified to defer furtherdrainage and use a pneumatic technique in conjunc-tion with reverse Trendelenburg positioning to facil-itate movement of blood to a more inferiorextramacular location overnight. In rare instances ofbullous hemorrhagic macular detachment occurringas a complication of scleral buckling, vitrectorny andfluid-air exchange with or without internal drainageof the hemorrhage may reduce late blood-relatedmacular dysfunction, although this techniqueremains unproven and controversial. In general thenatural history of submacular hemorrhage followingchoroidal perforation during scleral buckling is morebenign (han other clinical syndromes such as age-related macular degeneration.

Acute Ocular Hypertension

Acute rises in the intraocular pressure (lOP) are fre-quently encountered in the course of retinal reattach-ment surgery. Most frequently the lOP elevation is theresult of a buckle-induced compression of the globeor injection of a vitreous bubble to promote breaktamponade. Under normal physiologic circumstances,the outflow facility of the eye is able to compensatefor these acute pressu.re rises, with the rate of aque-ous outflow proportional (0 the lOP and therebyincreased. In the case of expansile concentrations ofinsoluble gases suc1J as sulfur hexafluoride and per-fluoropropane, the concomitant use of nitrous oxide(which is also highly insoluble) as a general anes-thetic agent may lead to severe and unpredictable lOPincreases related to the equilibrium-driven accumula-tion of nitrous oxide within the intraocular gas bub-ble. This complication can be avoided by advising theanesthesiologist when expansile gases may be usedand avoiding the use of nitrous oxide in such cases.When nitrous oxide has been used, it is highly rec-ommended that the ane.sthesiologist switch to another


inhalational agent at least l(}-15 minutes prior to theinstillation of intravitreal gas. Experimental studieson rabbits indicate that when outflow facility is nor-mal, elevation of the lOP acutely to levels of 100 mmHg by intravitreal injection of a O.4-cc gas bubble isfollowed by normalization of the lOP in 60 minutesor less. It is also known that placement of an encir-cling buckle reduces the outflow facility of the eye.at least temporarily. and thus may exacerbate the ten-dency toward ocular hypertension both intraopera-tively and postoper:.ltively. This can be offset byseveral methods including preoperative intermittentcompression of the globe to lower the lOP, preopera-tive or intraoperative treatrnent with a carbonic anhy-drase inhibitor (such as acetazolamide 500 mg) or ahyperosmotic agent (such as intravenous mannitolIgJkg) and. most commonly. paracentesis. A generalrule of thumb is that the normal eye will tolerate anlOP that does not result in closure of the central reti-nal artery for more than 50% of the duration of thecardiac cycle. This guideline should not be applied toeyes with preexisting glaucoma or ischemic ocular

disease.One special technique I have found helpful in rare

situations in which the ability to perform encirclageand intravitreal gas injection is effectively precludedby lOP considerations is to remove a small amountof vitreous. This is performed under indirect oph-thalmoscopic control with a mechanized cutter posi-tioned in the midvitreous cavity without the need fora separate infusion port or light pipe. Sufficient vol-ume is created to permit safe encirclage and gasinjection. although potential complications includethe creation of radial retinal folds, and accidental lensor retinal damage unless the surgeon is experiencedwith the technique. I find this technique preferable toneedle aspiration of vitreous, which is more unreli-able and prone to the creation of vitreous tracts (andpossibly increased vitreoretinal traction).

Retinal Fold Development

Radial retinal folds develop in eyes undergoingencircling procedures with drainage of subretinalfluid because the equatorial scleral circumference ofthe globe is shortened proportionally more than theequatorial retinal circumference. The radial fold rep-resents pleating of the retina to accommodate itsnew scleral circumference and appears to occur pref-

erentially in meridians containing retinal breaks. Inaddition to their potential involvement of the mac-ula and aesthetic considerations, retinal folds areundesirable because they often contribute to contin-ued movement of subretinal fluid through the reti-nal break. They can be avoided in many instancesby limiting the degree of circumferential scleralshortening induced by shortening (i.e., tightening)the encircling band and injecting a quantity ofintravitreal air or gas when a large amount of sub-retinal fluid has been evacuated. The instillation ofintravitreal air has the dual benefit of both restoringthe intravitreal volume (and pressure) to a morenormal level without excessive band shortening. andproviding postoperative tamponade for a retinalbreak should a retinal fold occur through a break.causing so-called fish-mouthing (see Chapter 7).Another approach to the problem of fish-mouthingis the placement of a radial buckle beneath the radialfold, although this technique is not generally appli-cable to eyes with multiple retinal folds and is ingeneral less desirable than the use of air or gas.

Early postoperative Complications(First 72 Hours)

Persistence of Subretirzal Fluid

When all subretinal fluid has been drained intraop-eratively, it is uncommon for any to be present onthe morning after surgery if all the breaks hive beenidentified and appropriately treated. In instances inwhich not all the subretinal fluid can be success-fully or easily drained, or in nondrainage proce-dures, subretinal fluid may still persist on the firstpostoperative day. If the breaks appear appropri-ately positioned overlying the buckle and theamount of fluid is either equal to or less than thatobserved at the termination of the operation thepatient may be safely observed for evidence of fur-ther subretinal fluid reabsorption, which generallyoccurs. If (1) there appears to be more subretinalfluid than present at the termination of the proce-dure, (2) a prominent retinal fold communicatesbetween the retinal break and subretinal fluid pos-terior to the buckle, (3) the retinal break is margin-ally positioned on the buckle, (4) the retinal break isvery large (and not well supported), (5) the maculais still detached, (6) there is clinical evidence of

continued vitreous traction on the retinal break, or(7) if retinal breaks have not settled in an eye thathas been previously vitreetomized, and there is notalready a bubble present, I favor an intravitrealinjection of air or an expansile gas within the first48-72 hours. This is most effective if the tear islocated within the superior 8 hours of the fundus (orin the posterior pole). The procedure can be per-formed at the patient's bedside, in a minor surgicalsuite, or in a reclining examination chair, with min-imal additional risk and invariably results in com-plete subretinal fluid reabsorption unless severevitrcoretinal traction is present. The technique isoutlined in the following section.


coma after scleral buckling. Most often this occursin pseudophakic patients with anterior chamberlenses, and is accompanied by frank iris bombe and,frequently, pupillary seclusion. The primary treat-ment is vigorous pupillary dilation to relieve theseclusion. If this is unsuccessful, laser iridectomieswith the YAG or argon laser are usually successfulin relieving the block, although multiple iridec-tomies in different secluded quadrants and, occa-sionally, vitreolysis behind the iridectomy, may berequired. If all of these measures are unsuccessful,pars plana vitrectomy and iridectomy will invariablyrelieve the problem in the absence of large choroidaldetachments. Some phakic patients (with either pre-existing uveitis or postoperative anterior segmentischemia) or aphakic and pseudophakic patients maydevelop pupillary seclusion, iris bombe, and acutelOP elevation as the result of a pupillary fibrin mem-brane (discussed in a subsequent section).

Choroidal Detachment

Along with mild ocular hypertension, serouschoroidal detachment is probably the most frequentcomplication of scleral buckling procedures, occur-ring in approximately 25% of cases. The likelihoodof postoperative choroidal detachment is increasedwith increasing patient age. the use of an encirclingbuckle, posterior placement of scleral buckles(compromising vortex veins), and drainage of sub-retinal fluid. Although the development of serouschoroidal detachment is not associated with adecreased long-term retinal reattachment rate, it isfrequently associated with moderate to severe ele-vation of the lOP and may be related to mildlyreduced levels of central vision in long-term folIow-up studies. Choroidal detachments may be annularand difficult to detect (often associated with mild tomoderate shallowing of the anterior chamber) orlobular and variable in size. In general, the treat-ment for mild to moderate choroidal detachment isconservative, consisting of cycloplegics and topicalsteroids. In some cases, oral steroids are used ifconsiderable inflammation is present. In rareinstances, it may be necessary to drain serouschoroidal detachments if they are "kissing" or asso-ciated with severe compromise of anterior struc-tures such as a malpositioned lens. Surgical therapyconsists of a radial or winged scleral incision

Exudative Retinal Detachment

Scleral buckling surgery, when combined with heavycryopcxy, can lead to the accumulation of exudativesubrciinul fluid 48-72 hours following surgery. Thesubretinal fluid tends to be turbid (obscuringchoroidal detail) and shifting in location; it tends toaccumulate posterior 10 the buckle and not contigu-ous to retinal breaks. Short courses of systemicsteroids are effective in treating this complication.

Ocular Hypertension

It is not uncommon to see mild to moderate ocularhypertension (lOP 25-30 mm Hg) with an openangle occurring on the first or second postoperativeday, especially in eyes undergoing encircling proce-dures. These can be successfully treated with a top-ical ~-blocker for the first week or two after surgery.with little risk of optic nerve damage in the other-wise normal eye. Patients with known preexistingglaucoma or a compromised angle should be pre-treated with a ~-blocker and/or carbonic anhydraseinhibdor to minimize expected fluctuations in thelOP. When the lOP is greater than 35 on the first orsecond day after surgery the most common cause inphakic patients is the concomitant development ofchoroidal detachment (see below). In most cases theangle remains open although there may be mild tomoderate shallowing. Treatment consists of pupil-lary dilation, topical steroids, a j3-blocker, and topi-calor oral carbonic anhydrase inhibitor if necessary.Patients may rarely develop true angle closure gIau-


overlying the pars plana to the plane of the supra-choroidal space. I have found the simultaneousintraocular infusion of air with an automated pumphelpful. In the case of kissing choroidal detach-ments, some consideration should be given to repo-sitioning the buckle to a more anterior location, ifpossible, to reduce vortex vein compression.

Fibrinoid Reaction andAnterior Segment Ischemia ~

When fibrinoid reaction is present in the anteriorchamber on the first postoperative day following ascleral buckling procedure in a nonuveitic eye, it gen-erally signifies that anterior segment ischemiahas occurred. This is frequently accompanied bychoroidal detachment and ocular hypertension.Patients with preexisting retinal vascular compromise,especially those with sickle cell anemia or the acuteretinal necrosis syndrome, are particularly prone tothis complication. In the otherwise noncompromisedeye the likelihood of anterior segment ischemia ornecrosis is increased by the use of an excessively highor broad encircling scleral buckle producing vortexvein compromise. In patients with predisposing reti-nal vascular disease, the frequency of this seriouscomplication can be reduced by avoiding encirclage ifpossible, being certain the intraocular tension is notexcessively elevated at the termination of surgery, andavoiding vortex vein compromise during orbital dis-section and buckle placement.

The other signs of anterior segment ischemia, inaddition to fibrinoid reaction. include cornealepithelial and stromal edema out of proportion tothe intraocular pressure, keratic precipitates (usu-ally pigmented), iris atrophy and liberation of pig-ment into the anterior chamber, acute cataract, andoccasionally pupillary eccentricity. The treatment ofchoice is reduction of the lOP and vigorous topicaland. in some instances, systemic steroid therapy. Incases where extremely large choroidal detachmentsare also present, some consideration may be givento replacing the buckling element and draining thechoroidal detachments within the first 24-48 hours.

Fibrinoid response in the anterior chamber is notinfrequently seen in eyes undergoing both scleralbuckling and vitrectomy (see Chapter 8) in theabsence of anterior segment ischemia. It most fre-quently occurs in diabetic patients with extensive

ocular neovascularization, trauma patients, andpatients with the acute retinal necrosis syndrome.although any patient with intraocular oozing ofblood in the immediate postoperative period maymanifest this response. In this instance, treatment isnot required unless either secondary complicationsof the fibrin ensue (such as pupillary block) or clearvisualization of the posterior segment is requiredfor additional maneuvers such as laser photocoagu-lation. The intracameral injection of 10-25 micro-grams of recombinant tissue plasminogen activator(!PA) is the preferred treatment for this condition,if severe. Mild cases of pupillary fibrin usuallyresolve spontaneously without serious sequelae.

Cataract

The development of acute cataractous change in theimmediate postoperative period following scleralbuckling is uncommon and almost invariablyrelated to the use of intraocular gas in the absenceof signs of anterior segment ischemia. The mecha-nism may be either through mechanical damageduring intravitreal gas injection or the indirecteffects of gas on the lens. In general. in eyes notundergoing vitrectomy with injection of a subtotalgas bubble, these effects are transient and not asso-ciated with an unfavorable long-term prognosis. Ineyes with larger, long-acting bubbles of perfluoro-propane gas, especially after vitrectomy. featheryposterior cortical opacities or vacuolar posteriorepithelial changes resembling fish scales may occur.These are also generally transient although they fre-quently herald the development of a late posteriorsubcapsular or nuclear sclerotic cataract. Latenuclear sclerosis is a very frequent complication inpatients over the age of 40 undergoing vitrectomyalone or in conjunction with scleral buckling,whether or not intraocular gas has been used.

If cataract is not accompanied by acute lensswelling and compromise of anterior segment struc-tures, treatment is not required immediately unlessclear visualization of the posterior segment isrequired for additional postoperative maneuvers. Ininstances where there is accidental mechanicaltrauma to the lens. acute swelling of the lens mayoccur with resultant shallowing of the anteriorchamber, corneal touch. and corneal decompensa-tion requiring immediate surgical intervention.

Macular Displacement and Fold

Occasionally following scleral buckling surgeryemploying an intravitreal air or gas bubble and a highlybullous retinal detachment, the macula may be hetero-topically displaced due to shortening of sclera. In someinstances the fold may course directly through thefovea, causing distortion, vision loss, or monoculardiplopia. This complication can be avoided by mini-mizing scleral shortening and maximizing subretinalfluid drainage during surgery. Foveal displacementsymptoms may be ameliorated by the use of prisms. Insevere cases, or when a frank fold is present, if thesymptoms are disabling, removal of the buckle andredetachment temporarily may be required.

I nfectious Complications

Infectious endophthalmitis following scleral bucklingand vitrectomy surgery is a very uncommon compli-cation and almost invariably. in my experience, theresult of intravitreal injection in the phakic nonvitrec-tomized eye as a postoperative maneuver. As a result.great pains should be taken to use sterile technique,including the administration of pre- and postinjectiontopical antibiotics. when administering or supple-menting gas intraoperatively or postoperatively. Treat-ment of endophthalmitis must be considered anextreme ophthalmic emergency and must include vit-reous aspiration for culture and injection of intravit-real antibiotics. with or without vitrectomy.

Although scleral implant and explant materialmay occasionally become infected (1--4% of cases).this invariably occurs later in the postoperativeperiod (6 weeks up to 20 years). Rarely, a scleralabscess may occur in the immediate postoperativeperiod. heralded by the development of severe ocularpain, orbital swelling out of proportion to the surgicalprocedure, and purulent discharge. Appropriate ther-apy fof this disorder includes prompt diagnosis,removal of the buckling material, intraoperativeorbital and scleral antibiotic lavage, and high-doseintravenous antibiotic therapy after appropriate cul-ture and sensitivity studies have been performed.

Lid Swelling

Lid swelling following scleral buckling occurs fre-quently enough to be considered an expected phe-


nomenon rather than a true complication. Nonetheless,it is a source of discomfort to the patient and maycause ptosis and limitation of extraocular movement.The incidence and severity of the swelling can bereduced by choosing appropriately sized bucklingmaterial, atraurnatic surgical technique. and possibleuse of solid rather than bulky silicone sponge explantmaterial. Orbital swelling is exacerbated by pronepositioning (required for patients with intraocular gasbubbles). Icc packs can be used to treat the swelling;systemic steroids are reserved for severe cases.

When lid swelling is severe, or accompanied bysigns of severe orbital inflammation including ten-derness and redness, the possibility of scleralabscess or a buckle infection should be considered.

Muscle Imbalance

Mild paresis of the extraocular muscles is a commonphenomenon during the first 24-72 hours after scle-ral buckling surgery, particularly when largeexplarns are used, or there has been extensive dis-section or revision of buckling material. TIle use oflong-acting local anesthetics for retinal detachmentsurgery may also contribute to this problem. Motil-ity almost invariably returns to normal within 2weeks after surgery and symptomatic diplopia canbe treated in the intervening time by patching. Up to5% of patients may have some degree of permanentmuscle dysfunction. usually correctable with prisms.The likelihood of this complication is increased bythe temporary disinsertion of muscles during scleralbuckling. a technique that is rarely indicated. Incases of prolonged motil ity imbalance, which areuncommon, buckle removal or muscle surgery maybe required with or without prism therapy.

Late Postoperative Complications

Infection or Erosion oj Implant

The principal late complication of scleral buckling isinfection of the implant or explant associated with thedevelopment of a fistulous tract. This complication isoften heralded by the development of ocular pain, ten-derness to palpation over the buckle, conjunctivalinjection, and lid crusting of a mucoid or frequentlypurulent nature. This is especially noticeable to thepatient upon awakening in the morning. The clinician


may determine the site of infection by palpating theglobe through the lids, and identifying the tender area.Occasionally, a fistulous tract may develop in theabsence of frank clinical infection, although it shouldbe assumed for all practical purposes that the devel-opment of a fistula signifies the development of aclinical buckle infection. The likelihood of this com-plication is increased by poor lid hygiene, possiblythe use of sponge rather than solid silicone bucklingmaterial. and failure to soak the buckling materialintraoperatively (prior to insertion) in an~antibioticsolution such as fortified ccfuzolin or Neosporin.Meticulous closure of Tenon's capsule and conjunc-tiva and irrigation of the subconjunctival space priorto closure with a topical antibiotic may also reducethe frequency of this complication. Once the patientshows signs and symptoms of an infected explant.removal of the explant is almost always inevitable. Ininstances in which the buckle has been present forless than 6 weeks and the severity of ocular inflarn-marion is mild. serious consideration should be givento conservative therapy with topical and/or oralantibiotic coverage as well as meticulous lid hygieneto allow Iormatiou of a mature choriorctinal adhesionthut will muiutuin retinal reattachment after buckleremoval. In the majority of cases, removal of thebuckling material is not accompanied by retinal rede-tachrncnt after this time. provided that all the retinalbreaks have been sealed by a thermal modality andthere is not extensive residual vitreoretinal traction. Ifavor supplemental photocoJgulation to areas of reti-nal breaks and/or vitrcoretinul traction in instanceswhere the buckle must be removed approximately1-2 weeks prior to buckle removal.

In some cases, erosion of the conjunct! va andTenon's capsule tissue overlying the buckle mayoccur without other clinica! signs of infection suchas mucopurulent discharge or conjunctival injec-·tion. In such cases, a culture should be taken toascertain that there is no evidence of a conjunctivalinfection. In some instances, the situation may bestabilized by placement of a homologous scleral orper icardial patch graft over the exposed buckle,over which conjunctiva is then reclosed with anabsorbable suture after the edges are trimmed. Itcan be categorically stated that once a fistulous tractor area of erosion has occurred, reclosing the eon-junctiva in that area without placement of additionalhomologous tissue either in the form of scleralpatch graft or autologous donor conjunctiva is

likely to be unsuccessful. Most buckle infectionsare caused by staphylococcal species and tend torun an indolent course. Occasionally gram-negativeinfections (including Pseudomonas) produce a morefulminant picture and may be associated with thedevelopment of scleral ectasia and frank stuphy-lorna beneath the buckl ing material. Great careshould be exercised in removing buckles in suchareas because of the risk of accidental perforation.especially in cases of gram-negative infection. It isalso important to remove scleral sutures from allquadrants at the time of buckle removal. since theymay contribute to the persistence of infection.

Other Late Complications

A multitude of other complications may occur thatare beyond the scope of this chapter. These includedevelopment of proliferative changes of the vitreousas manifest by macular pucker or PVR. ln general.the likelihood of these complications is increased byany of the other inrraoperative or early postoperativecomplications including scleral perforation. subrcti-na! hemorrhage, choroidal detachment. and fibrinoidsyndrome. The reader is advised to consult the chap-ter on vitrectorny in this and other excellent bookson vitrectorny methods for the surgical managementof these proliferative complications.

Postoperative-Management Techniques

Fluid-Gas Exchange

Fluid-gas exchange is an extremely valuable tech-nique that is applicable to eyes that have previouslyundergone vitrectomy with the following indications:residual or recurrent subretinal fluid accumulation;persistent intraocular media opacity; evidence ofsevere intraocular inflammation as manifest by a mas-sive protein deposition (with or without fibrin) in theocular compartment; to facilitate or prolong intraocu-lar tamponade in eyes with appropriate indications(large retinal tears, proliferative vitreoretinopathy, andoccasionally unresolved vitreoretinal traction). Fluid-gas exchange can be performed at the bedside or in aminor surgical suite with either topical or retrobulbaranesthesia, although the latter is recommended inphakic and most pseudophakic patients. Following

instillation of topical anesthesia, conjunctival surfacesare prepared with several drops of povidone-iodine(5%) and/or topical antibiotic solution. A lightweightwire speculum is then inserted and the patient rotatedinto the prone position if aphakic, or the lateral decu-bitus position with the temporal aspect of the eye tobe treated down if phakic or pseudophakic. Fluid-gasexchange is performed with a lO-ce syringe and ashort 26- or 27-gauge needle. Sterile air, sulfur hexa-fluoride (SF6) gas, or perfluoropropane (PFP) isdrawn up into the syringe through a 0.22-mm sterilefilter. The gas mixture is then diluted to the appropri-ate concentration through the filter and the plunger ofthe syringe ultimately returned to the 8-cc marking onthe barrel to allow for adequate excursion of theplunger during the first phase of the exchange, whichis initiated by withdrawal.

In phak ic or pseudophakic patients, the needle isintroduced into the vitreous cavity via the temporalpars plana 4 mm. posterior to the limbus, which is inthe dependent position with the patient in the lateraldecubitus position. The needle tip is brought intoview in the midvitreous cavity well clear of the lensand withdrawal initiated. Incremental exchange of0.5-1.0 ml of fluid is made followed by incrementalinjections of a similar volume of air or gas leavingthe plunger of the syringe in the most dependentposition (Figure 10-1). This has the effect of causingfluid to sink gravitationally toward the dependentplunger while keeping air or gas near the hub whereit can be continually introduced without the creationof "fish eggs." Care is taken not to incarcerate resid-ual vitreous base by reducing suction as the needleis slowly withdrawn inferiorly during the final stagesof phakic exchange (Figure 10-2).


Figure 10-2. Later phase of Figure 10-1. Note lateraldecubitus position.

In aphakic patients, the needle is introducedthrough the nasal or temporal limbus with the dorn-inant hand, depending on which eye is beingexchanged, and brought into the midpupillaryplane. A similar sequence of small withdrawals andinjections is completed until fluid equal in volumeto the gas to be injected has been evacuated fromthe eye and replaced by air or gas (Figure 10-3).Remaining intraocular fluid can be aspirated fromthe anterior chamber by gently redirecting the nee-dle anteriorly at the end of the procedure (Figure10-4). lOP at [he termination of the exchangeshould be left in the low-normal range in any eyein which expansile gas is used.

The distinction should be made between the useof expansile gas ill general. and the use of an

Figure 10-3. Injection of air or gas in aphakic previouslyvitreciornizcd eye via limbus. Note prone position.

figure 10-\' Injection of air or gas in phakic previouslyvitrectornized eye via pars plana. .


Figure lO-~. Later phase of Figure 10-3. Note face-downposition that facilitates complete removal of intraocularfluid.

expansile concentration of an expansile gas. The con-centration of 20% (SF6) and 14% PFP are nonexpan-site concentrations of expansile gases; hence nosevere increases in lOP should be anticipatedalthough the lOP can be measured in such eyes 4--8hours after exchange to exclude this potentially cata-strophic complication. In some cases, it is advanta-geous to use an expansile concentration of anexpansile gas such as 30-50% SF6, or 20-25% PFP.This is particularly true in eyes with a large amountof subretinal fluid or eyes in which a total fluid-gasexchange cannot be performed. In these instances, itis especially critical that the closing intraocular pres-sure be left in the low-normal to soft range; lOP mea-surements in the first 6-12 hours after injection canavoid major problems. Pressure rises with expansileconcentrations of expansile gas can be unpredictableand severe, hence due caution must be exercised.This complication is particularly troublesome in eyesin which an encircling scleral buckle has beenapplied immediately prior to the fluid-gas exchange,in patients who received nitrous oxide anesthesia(without adequate washout), and in eyes with preex-isting rubeosis or open or closed angle glaucoma. Insuch circumstances, the use of an expansile concen-tration of gas is strongly discouraged.

When an expansile concentration is used, I cur-rently favor the use of 30% SF6 or 20% PFP,although the patient must be advised that a subse-quent aspiration of gas may be required. These con-centrations can help to provide tamponade ofinferior retinal breaks and minimize leakage of

mitogenic blood retinal breakdown products (whichfavor the development of postoperative re-prolifer-ation) into the intraocular compartment. Our previ-ous studies indicate that when fluid-gas exchangeis performed in eyes with recurrent, subtotal, ortotal detachment of the retina, 80-85% of patientswill demonstrate total or near total reattachmentwithin 24 hours after exchange, with 70% of reti-nas remaining totally or mostly reattached at 6months. The long-term results of retinal reattach-ment in this circumstance appear to be favorablyinfluenced by supplemental photocoagulationthrough the gas bubble.

[ntravitreal Gas Injection

In patients who have not undergone vitrectomy,intravitreal gas may be used for recurrent or resid-ual subretinal fluid, or for extended internal tam-ponade, although a different technique must beused, and a total gas fill cannot be achieved safely.The risk of intraocular infection appears to besubstantially greater in phakic nonvitrectomizedpatients than in the previous group and, hence, addi-tional caution should be exercised in performingthis technique. In contrast to fluid-gas exchange,intravitreal gas injection is generally performedusing expansile concentrations of expansile gas,generally 100% SF6 or PFP, since only small quan-tities can be injected in the absence of a concomi-tant release of-vitreous fluid.

The technique is virtually the same as thatdescribed in Chapter 5. The patient is positionedeither supine or in the sitting position with supportbehind the head and neck. Retrobulbar anesthesia isrecommended for instillation of the gas via the parsplana. The lids are separated with a lightweightwire speculum and topical anesthesia and povidone-iodine 5% and topical antibiotics are administeredprior to the injection of the gas, which is performedunder indirect ophthalmoscopic control to avoidaccidental damage to either the lens or detachedretina. Premedication with topical lOP loweringmedications, osmoglyn, or oral acetazolamide (250mg) I hour prior to the injection and mild digitalmassage prior to injection are helpful in reducingthe severity of the lOP rise immediately after injec-tion. Either 0.3 or 0.4 cc of intravitreal gas isinjected, with attempts made to produce a single gas

bubble by a smooth uniform movement, leaving thetip of the needle in the already partially injected gasbubble to reduce the likelihood of "fish eggs."Depending on the desired longevity of the gas bub-ble as well as the maximal degree of expansion,either SF6 (two and one-half times expansion), orPFP (four times expansion) may be used. As a gen-eral rule, postoperative injection of air is not rec-ommended because of the volume limits imposed.Immediately following injection of gas, the IOPmay be elevated in excess of 50 mm Hg and associ-ated with pulsation (and in some cases closure) ofthe central retinal artery.

I generally perform paracenteses immediatelyfollowing gas injections to normalize the pressureto approximately 30 mm Hg or less, using full per-fusion of the optic nerve as a clinical endpoint.Paracentesis can be dangerous in aphakic and pseudo-phakic eyes if the posterior capsule is not intact.

Following gas injection, the fundus should beinspected to ascertain that the optic nerve is wellperfused and that no gas bubbles have migrated intothe subrerinal space. The likelihood of this compli-cation can be reduced by avoiding gas injection ineyes with very large open tears, and positioning thehead prior to injection in such a way that the largetears are in a dependent position relative to the siteof the gas injection.

Previous studies in humans and experimentalanimals indicate that the injection of a 0.3-D.4 ccvolume of expansile intraocular gas is well toler-ated, with normalization of the lOP within 40 min-utes after injection and no appreciable rise duringthe period of maximal expansion. In patients withpreexisting glaucoma or the recent placement of anencircling buckle, lOP may rise unpredictably andadditional caution is thus warranted.

Suggested ReadingI

Aaberg TM. Pawlowski GJ. Exudative retinal detachmentsfollowing scleral buckling with cryotherapy. Am J Oph-rhalmoI1972;74:245.


Blumenkranz MS. Management of complicated retinaldetachment. In: Tso M, ed. Retinal Diseases. Philadel-phia: JB Lippincott; 1985.

Blumenkranz MS. Gardner T, Blankenship G. Fluid gasexchange after vitrectorny. I. Indications, technique andresults. Arch OphthalmoI1986;104:291.

Charles S. Vitreous Microsurgery. 8th Ed. Baltimore:Williams & Wilkins; 1987:207-214.

Chignell A. Retinal Detachment Surgery. Ber lin/Heidel-berg/New York: Springer-Verlag; 1980: 139-162.

Fison PN. Chignell AH. Diplopia after retinal detachmentsurgery. Br J Ophihalmo! 1987;71 (7):521-525.

Grizzard WS. Hilton GF. Hammer ME. Taren D. A multi-variate analysis of anatomic success of retinal detach-:rnents treated with scleral buckling. Graefes Arch ClinExp Ophthalmol 1994;232( 1): 1-7.

Hay A, Flynn HW Jr.• Hoffman JI, Rivera AH. Needle pene-tration of the globe during retrobulbar and peribulbarinjections. Optuhalmotogy 1991;98(7): 1017-1024.

Kanski J. Retinal Dctachment: A Colour Manual of Diagno-sis and Treatment. Oxford: Butterworth: 1986: 129-154.

Levkovitch-Verbin H. Treister G. Moisse iev J. Pneumaticretinopexy as supplemental therapy for persistent reti-nal detachment after scleral buckling operation. AcraOphthalmol Scand 1998:76(3):353-355.

Maeno T. Maeda N. Ikeda T. Tano Y. Tissue plasminogen acti-vator treatment of postvitrectorny pupillary fibrin mem-brane. Nippon Ganka Gakkai Zasshi 1991 ;95( 11):1124-1128.

Packer A, Maggiano J. Aaberg T. et al, Serous choroidaldetachment after retinal detachment surgery. Arch Oph-thalmol 1983; 101: 1221.

Regillo CD. Benson WE. Retinal Dctochment: Diagnosisand Monagement, 3rd Ed. Philadelphia: Lippincott-Raven; 1998.

Schepens C. Retinal Detachment and Allied Diseases. Vol.I. Philadelphia: WB Saunders; 1983: 1024-1086.

Tabandeh H. Flaxel C. Sullivan PM. Leaver PK. Flynn HWJr. Schiffman J. Scleral rupture during retinal detach-ment surgery: risk factors. management options. andoutcomes. Ophrhalmology May 2000: 107(5):848-852.

van Meurs JC, Humalda D. Mertens DA, Peperkamp E. Reti-nal folds through the macula. Doc Ophrhalmol199J ;78(3-4):335-340.

Wade E. Flynn HW Jr. Olsen KR. Blumenkranz MS. Nichol-son D. Subretina] hemorrhage management by parsplana vitrectorny and internal drainage. Arch Ophtha}:mol 1990;108:973-978.

Wilkenson CPo Rice TA. Michels Retinal Detochment , 2nded. Philadelphia: Mosby; 1997.

Index

Note: Page numbers followed by "t' indicate tables; page numbers followed by 'T' indicate figures.

Adjuvant therapy. in macular hole surgery, 112-113Anesthesia

agents. ~8-l9anatomic considerations, 44-48general

description of, 43, 53-54local anesthesia and, 54

localcomplications of. 51,53description of, 43, 48general anesthesia and, 54technique for, 50-51, 52f

minimal, 5~monitoring during. 50needles. 49-50patient selection considerations, 43-44, 44tpharmacologic considerations, 48-49premedication age nts, 50techniques

Atkinson, 43, 47-48, 48flocal, 50-51, 52fretrobulbar injection, 50, 52f

Annulus ofZinn, 45Aphakia, retinal detachment associated with, 25Atkinson technique, 43, 47-48, 48fAtrophic retina, 9Autologous serum, 113a-wave (ERG), 19-20

dosing of, 49tlidocaine and, 51 t

b-wave (ERG), 19-20, zorCarbonic anhydrase inhibitors, 38Cataracts, macular hole surgery as cause of, l l SCentral retinal artery occlusion, 21Central retinal vein occlusion. 21Choriocapillaris. 1, 2fChorioretinal pigmentation. 7Choroid

anatomy of, 2fdetachment of

echographic imaging of. 17hemorrhagic, 17, 18fscleral buckling as cause, 123-124serous, 17

Circumferential traction lines, 7Complications, of vitreoretinal surgery

anterior segment ischemia, l24cataract, 124choroidal detachment, 123-124classification of, 119description of, I Wexudative retinal detachment, 123eyelid swelling, 125fibrinoid reaction, 124globe rupture, 120infections, 125macular displacement and fold, 125muscle imbalance, 125ocular hypertension, 121-123postoperative management of

fluid-gas exchange, 126-128intravitreal gas injection, 128-129

131

Biomicroscopy, fundal examination using, 9Breaks. See Retinal breaksBruch's membrane, 2fBupivacaine

advantages and disadvantages of, Sitdescription of, 43, 48


Complications, of vitreoretinal surgery (continued)retinal folds, 122retinal incarceration in sclerotomy site,

102-103,120-12\scleral suture penetration, 119-120subretinal hemorrhage, 121

Conjunctiva, 6Contact lens examination, 9Corneal erosions, 103Cryopexy

advantages of, 27 ~complications associated with, 27-28description of, 27disadvantages of, 27laser photocoagulation vs., comparisons

between, 28-29for retinal incarceration, 120technique, 29-30

c-wave (ERG), 19-20Cyclopentolate hydrochloride, 6

Diabetic retinopathydescription of, 69membrane removal

indications, 98surgical technique, 98-100

silicone oil for, 95vitrectomy for, 99f

Duranest. See Etidocaine

EchographyA-scan, 12B-scan, 11-12diagnostic and evaluative uses of

choroidal detachment, 17foreign bodies, 17-18, 19fposterior segment, 12retinal detachment

closed-funnel, 13, l4fdiabetic tractional, 13, 15fnonrhegmatogenous, 15-17open-funnel, 13, 14frhegmatogenous, 12-13

trauma, 17-18history of, II

Ehlers-Danlos syndrome, 26Electrophysiology

description of, 18electroretinogram. See Electroretinogramvisually evoked potential, 2\-22

Electroretinogrambright-flash, 19-21description of, 19-21, 20fdiagnostic and evaluative uses

central retinal artery occlusion, 21central retinal vein occlusion, 21partial retinal detachment, 21proliferative diabetic retinopathy, 21

Endophthalmitisafter scleral buckling, 125vitrectomy for, 70

Epinephrine, 49Epiretinal membranes

description of, 85-86macular, 69-70, 110membrane peeling for. See Membrane peelingremoval of, during macular hole surgery, 110

Ethmoidal nerve, 46fEtidocaine, 48, 49tExplants, for scleral buckling

description of, 5infections in, 124selection of, 60silicone bands, 60, 60f

External limiting membrane, 2fEyelids

evaluation of, 6swelling of, after scleral buckling, 125

Fibrinoid reaction, 124Fluid-gas exchange, 126-128Forceps,73fForeign bodies, 17-18, 19fFovea

descri ption of, 1limited translocation of, 101

Frontal nerve, 45Fundus

examination of, 6-9peripheral changes in, 9scleral buckling evaluations, 67

Ganglion layer, 2fGas injections

fluid-gas exchange, 126-128intravitreal, 128-129for scleral buckling, 68tamponade use. See Intraocular tamponade

General anesthesiadescription of, 43, 53-54local anesthesia and, 54

Giant retinal teardefinition of, 96treatment of

perfluorocarbon liquid, 95-96silicone oil, 95surgical,96-98

Glaucoma, 96

Hemorrhageretinal, 9subretinal. See Subretinal hemorrhagesurgical onset of, 103

Hyaluronidase, 49

Indirect ophthalmoscopyfundal examination using, 6-7retinal breaks detected usinz 24subretinal fluid drainage, 6~7technique for, 6

Informed consent, 10Infraorbital nerve, 46f-47fInfratrochlear nerve, 47fInner limiting membrane

anatomy of, 2fremoval during macular hole surgery, 110, 111f

Inner nuclear layer. 2fInner plexiform layer, 2fIntraocular pressure, increased

in macular hole surgery, 114ocular hypertension secondary to, 121-122in scleral buckling, 56

Intraocular tamponadegases

description of, 112, 114indications, 94ocular hypertension caused by, 95perfluoropropane, 94, 127-128sulfur hexafluoride, 94, 127types of, 94vitrectomy use, 94-95

for macular hole surgery, 105, 112for retinal detachments, 103for scleral buckling, 68silicone oil, 112

Intravitreal gas injection, 128-129

Lacrimal nerve, 45, 46f-47fLaser photocoagulation

advantages of, 28cryopexy VS., comparisons between, 28-29description of, 28disadvantages of, 28for pneumatic retinopexy, 35, 37fposterior retinal break treated using, 90ftechnique,3G-31wavelength setting, 28

Lattice degenerationdescri ption of, 7retinal detachment risks, 26

Index 133

Lenssubluxation of, 6vitrectomy-induced damage, 103

Lensectomy, 83-85Lidocaine

advantages and disadvantages of, 51 tbupivacaine and, 51tcomplications associated with, 53description of, 49tdosing of, 49t

Lids. See EyelidsLocal anesthesia

complications of, 51,53description of, 43, 48general anesthesia and, 54technique for, 5G-51, 52f

Maculaanatomy of, Idisplacement of, after scleral buckling, 125

Macular holeclassification of, 106tclinical findings, 107fdifferential diagnosis, 106surgery for

case selection, 106cataract formation after, 113complications associated with, 114-115,

liStgoals of, 105, 116indications, 105-106instrumentation, 108tpatient positioning after, 113-114postoperative care, 113-114preoperative evaluation, 106, 108prognostic factors, 106, 106tsuccess rates, 107fsummary overview of, 115-116technique

adjuvants, 112-113air-fluid exchange, 111-112epiretinal membrane removal, 110internal lirniting membrane removal, l l O,

IIIftamponade, 112, 114vitrectomy,108-110

techniques for assessing, 106, 108traumatic, 106

Marcaine. See BupivacaineMarfan's syndrome, 6Membrane peeling

epiretinal membranewith attached retina, 86with retinal detachment, 86-88


Membrane peeling (conti/lued)indications, 85-86instrumentation, 86peripheral membrane. 88retinal breaks during, 103technique, 86-89

Membranesepiretinal. See Epiretinal membranesinner limiting

anatomy of. 2fn:l11oval during macular hole surgery. 110.

1 I I f ~peeling of. See Membrune peeling

. peripheral. 88removal of

in diabetic retinopathy. 98-100in macular hole surgery. 110. 111f

suhfoveal neovusculurdescription of. 70surgical removal of. 100-1 () I

:Vliosis. ~6. 67Muscle cone . .+-l--+5i\lyopia. retinal detachment risks associateu with.

25-26

N~lsociliary nerve. '+5. 461'Needles. for retrobulbar anesthesia. 49-50Nervc(s)

ciliary.3feth rnoidul. '+6 ffrontal. .+5inl·raorhilal. -I6f-47fint'ratroch1car. 47flacrimal. 45. 47fnasociliary. 45. 46foculomotor. 47oplic.45supraorbital, 45. 46f-47fsupratrochlear. 45. 47ftrigeminal. 45zygomalic, 46f-47fzygomaticofacial. 46fzygomaticotemporal. 46f-47f

Ocular coherence tomography. for macular holeevaluations, lOR

Ocular examinationin retinal detachment patient, 5-6in vitrectorny patient, 72-74

Ocular histoplasmosis syndrome, 100Ocular hypertension. 95, 103. 121-123Oculomotor nerve, 47Ophthalmic artery. 45

Ophthalmoscopy. See Indirect ophthalmoscopyOptic canal, 45Optic foramen, 45Optic nerve, 45Orbit, anterior, 44Outer nuclear layer, 2fOuter plexiform layer, 2f

Pan funduscopic lenses, 9Pars plana vitrectorny, IIPerfluorocarbon liquid

giant retinal tears treated using. 95-98proliferative vitreoretinopathy treated using .

91-92during virrectorny, 81

Perfluoropropane.9-1, 117-128Peripheral membrane. 88Peripheral retinal dialysis. 102Phak ic retinal detachment. 25Phenylephrine hydrochloride. 6Photocoagulation. See Laser photocoagulatiunPhotoreceptors. IPlatelet concentrates. 113Pneumatic retinopexy

bubblecharacteristics of. 34-35complications associated with, 40mechanism of action. 33pertluoropropane, 3..+selection of, 34-35

complications of. 40history of. 33mech~nism of action. 33patient selection. 33-34phakic status and, 40postoperative care, 3R-39scleral buckling vs., comparisons between. 41success criteria, 40-41technique

antibiotic use, 37-38laser photocoagulation, 35, 37fsteamroller, 37-38, 39fsummary overview of, 36t

Posterior segment vitrectorny, See VitrectornyPosterior uveal melanoma

echographic imaging of, 16. 16fretinal detachment vs., 16

Posterior vitreous detachmentdescription of. 3echographic imaging of, 13-14surgical methods for creating, in macular hole:

surgery, 109total retinal detachment vs., 13-14

Posterior vitreous separation, 3, 4fProliferative diabetic retinopathy, 21

vitrectomy for, 98-100Proliferative vitreoretinopathy

anterior, 13, 15ftreatment of

perfluorocarbon liquid, 91 fpneumatic retinopexy, 34silicone oil, 95-96

Proparacainc. 9Pseudophakia, 25Pulse oximeter, for anesthesia monitoring, 50

Radial sponges, 63Rectus muscles, 47Relaxing retinotornies

indications, 92technique, 92-94

Retinaanatomy of. 1-3, 2ffolds, 122hemorrhage of. 9incarceration in sclerotomy site, 102-103,

120-12!translocation or. 101

Retinal breaksasymptomatic, 23atrophic. 25clussification of, 26definition or. 3-4detection of. 10. 23-24. 58-59fellow eyes, 26indirect ophthalmoscopy evaluations, 6. 24, 58lesions that simulate, 9macular hole surgery <IS cause of. 114membrane peeling-induced, 103operculated. 4, 25subrctinal fluid and, treatment decisions

regardingcryopexy, 30decision-making criteria, 26laser photocoagulation, 31

symptoms of, 23-24tractional, 25treatment of

cryopexy. Sec Cryopexydecisions regarding, 24-27follow-up care, 31-32laser photocoagulation. Sec Laser photoco-

agulationsuccess rate, 31during vitrectoruy, 89-90

vitrectomy-induced, 103without scleral depression, 7

lndcx 135

Retinal detachmentin aphakic patient. 25closed-funnel, 13, 14fdiabetic tractional, 13, 15felectroretinogram evaluations of, 21epiretinal membrane with, 86-88exudative, 123factors that cause, 4in fellow eyes, 26incidence of, 24Lincoff's rules. 9-10myopia and, 25-26open-funnel. 13, 14fin phakic patient, 25pneumatic retinope xy for, 34preoperative evaluations

description of, 5fundal examination. 6-9history-taking.finformed consent, 10ocular examination. 5-6retinal breaks, 9

rhcgrnarogcnousdescription of. I. 55macular hole surgery as cause of. 114

serous, 17vitrectorny for. SCi' Viircctorny

Retinal pigment cpithc iiurnanatomy of. 1-3.2fdescription of. Imacular hole surgery effects. 115retina attachment 10, 4

Retinal tears. Sec Giant retinal tear; Retinal breaksRetinal tufts. 9Relinectol1ly,93-94Retinopathy of prematurity. 70Retinoschisis

acquired, 9atrophic retina \'s .. 9congenital. 9

Retrobulbar injectioncomplications associated with. :i3technique, 50, 52f

RPE. Sec Retinal pigment epithelium

Scissors, 72fSclera, I, 3Scleral buckling

anesthesia, 44, 56complications of

choroidal detachment. 123-124exudative retinal detachment, 119-120eyelid swelling, 125fibrinoid reaction, 124

Scleral buckling. complications of (continlled)macular displacement and fold, 125penetration with scleral sutures. 119-120

cryopexy use, 59-60description of, 55explant selection. 5. 6Q--64, 124gas injections, 68intraocular pressure concerns, 56intrascleral suture placement, 64-65laser photocoagulation use, 60opening conjunctiva, 56-58pneumatic retinopexy vs., bmparisons

between, 41preoperative managemeRt, 55-56retinal break localization, 58-59retinal detachment categorization for, 55-56subretinal fluid drainage. 61, 65-68sutures. 64-65vitrectomy and, 90

Scleral implantdescription of. 5erosion of, 125-l26infections in. 124-126

Sclerotomyfor lensectomy. 84for vitrectomy. 76-78

Silicone oilcomplications associated with. 96description of. 95indications. 95-96injection techniques for. 96tamponade uses, 112

Slit-lamp examinationin retin<.lldet<.lchment patient. 6in vitrectomy patient. 72

Stickler's syndrome, 26Subfoveal neovascular membranes, surgical

removal of, lOo-\01

Subretina\ fluiddrainage of

complic<.ltions associated withretinal folLls. l22subretinal hemorrhage, 121

inability to complete successfully, 120persistence of fluid after

description of, 122-123intravitreal gas injection for, 128-129

in scleral buckling, 61, 65-68retinal breaks and, treatment decisions regarding

cryopexy, 30decision-making criteria, 26laser photocoagul<.ltion, 3l

retinal detachment accumulation of, 10

136 MANUAL OF RETINAL SURGERYSubretinal hemorrhage

disciform scar. 15fecho graphic imaging of, 13, 15fpredisposing factors, 121during subretinal fluid drainage, 121

Subretinal spaceechography evaluations of. 13in retinal detachment, 13

Sulfur hexafluoride, 94. 127Suprachoroidal hemorrhage, 17Supraorbital nerve, 45. 46f-47fSupratrochlear nerve, 45. 47fSurgery. See specific sllrgery

Tamponade. See Intraocular tamponadeTenon's space, 56, 57f, l26Tissue manipulator, 72fTransforming growth factor-beta, 113

Traumaechographic evaluations of. 17-18. 19fmacular holes caused by. 106vitrectomy for. 70

Trigeminal nerve, 45

VEP. See Visually evoked potentialVisual fieid evaluation. 5-6Visually evokeLl potential. 2l-22

Vitrectomyanesthesia, M. 74complications of, 102-l03diabetic retinopathy treated using. 98-100. 99:fluid-gas exchange after, 126--128giant retinal tear, 96-98goals of, 69, 69tindications. 69-71instrumentation

arranging of, 74, 75ftypes of, 7l, 72f-73f

intraocular gases used during. 94-95intraocular infusion solutions. 75-76lensectomy, 83-85in macular hole surgery, 108-110membrane peeling

with attached retina, 86indications, 85-86instrumentation, 86peripheral membrane. 88with retinal detachment, 86-88technique, 86-89

ocular examination before, 72-74ocular histoplasmosis syndrome treated using. 1patient preparation for, 74

perfluorocarbon liquid, 91-92relaxing retinotomies, 92-94retinal breaks treated during, 89-90retinal detachment treated during, 90retinectomy during, 93-94scleral buckling during, 90silicone oil use, 95-96subfoveal neovascular membrane removal,

100-101surgical planning for, 74technique

description of, 78-83entrance into the e,ye, 76-78incisions, 76perfluorocarbon liquid, 81posterior hyaloid incision, 79-80posterior vitreous removal, 79-80sclerotomy, 76-78suturing, 83vitreous separation, 81-82

Index 137

Vitreoretinal forceps, 73fVitreoretinal scissors, 72fVitreous

anatomy of, 3-4incarceration in sclerotomy site, during vitrec-

tomy, 102-103separation of, 3

Vortex veins, 1, 3f

Watzke-Allen test, 108Wydase. See Hyaluronidase

Xylocaine. See Lidocaine

Zygomatic nerve, 46f-47fZygomaticofacial nerve, 46fZygomaticotemporal nerve, 46f-47f

Ophthal mology

Manual ofRetinal Surgery

Second Edition

Andrew]. Packer, M.D."Dr. Andrew J, Packer and his cl)lIeague,., h;I\'l' upd,lled ,111.1exp;lI1lbl rhc topics Ill' rhi: edition\\'hile retaining the concise technique descriprion» that will pr. ivc remarbhly useful f(lr student-of oJ1ht halm(ll(lgy a~ well a, practicing ophthaltnolugists \\'JlIl wish I I) hrin,L: 1heir uudcrsraruliru;nf current virrcorerinal techniques tI' current fn inticr-,"

- From rhl' Fllrl'tmrd hy Thoma- M, Aah,'rg, Sr., 1\/1.1l.

Praisl' fill' till! First Edilir)J1"J t is a \\TlI'llrgani:e,l <lnd concise "how t\ t I •10k, an up-to-dare sUIl1Ill"ry .)f current virrcorcrinal,urgical procedures well-suited f(lr tN' in te,llhing resident. , The chapler" arc writ ten hy author»well known iri the fieH The hl10k is full of 'pearl.,' f"l' l-oth rhe heginning and thc e,tah\ishedvitrcorctinal surucon. Ahhough concise, it: hre;ldth is remarkable.'

-O/,hllllllm;c SlIrgn'j'

This unique .md informative manual introduces rcsidcnt« nn.l fcll,l\\'s to vit rcorct inu] ,urgeryand i" abo an ideal source III ai,lth c experienced surgeon in refining technique- and bll'l1ing»lrcrn.u ivc rnerhod-.

• Incorporates new ,urgicd procedures, including macular hok' slll'gcry• Conrain« nurncrou- nn.iromic l.kl\\'ings illu,tr:ning the SUI',L:il':t!procedures• Benefit lrom contrihurors' clinical expertise

. Wirh ch.rprers on macular hole, j'neum;ltic rcrinopcxv, prcopcr.u ive 1IItra,(lund and electro-phy,iu!llgy, ,tlkl scleral huck ling surgl'1'y, this manual providcs n rimelv prirucr on currentvirrcorct inal ~l1fgical procedures.

Related Title ...:Schepens' Retinal Detachment and Allied Diseases, Second EditionCharle, L. Scheper», 1\1:11')' Elic.rbcrh ) larrncrr. and Tarsuo HinN:lSI) 0-7'i06-9837-3,) IardcO\'l'1', 7KH pp,

Macular Hole: Pcthogenesis, Diagnusis, and TreatmentSteven A. Madreperla and Bnl"ks W, McCuen IIISBN 0-7506-1)1)60-4, Paperback, 171 pp,

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22963536 Manual of Retinal Surgery 2nd Edition 2001