Surgeries in open angle glaucoma

Presenter: Dr.Aditi Singh 

Indications:

1.Documented visual field and optic nerve damage, despite maximum

tolerated medications and laser therapy.

2. Anticipated progressive damage or intolerably high IOP.

3. Combined with cataract procedure if there is borderline IOP control or advanced damage,.

:

guarded (trabeculectomy)

Penetrating filterationg surgeries

full-thickness

Nonpenetrating filtration surgery(NPFS)

Glaucoma Drainage Devices (GDD)

Recent advances in glaucoma surgeries

Full-Thickness Filtration Procedures

1.Thermal sclerostomy (scheie Procedure).

2.Sclerectomy

3.Trephination

4.Iridencleisis

Rarely performed today.

1.Thermal sclerostomy (scheie Procedure): • Limbal-based conjunctival flap.

• Light cautery applied to the sclera in 1X 5 mm area , behind corneolimbal junction.

• 5 mm limbal scratch incision is made through the cauterized area.

• Cautery is applied to the lips of the incision , until the wound edges separate by atleast 1 mm.

2. Sclerectomy: Posterior lip sclerectomy:• Ab-externo incision- just behind the point of

reflection (using a limbal-• based flap) of the conjunctiva at the anterior

limbus.• Length - 3–4 mm• Sclerectomy - 1-mm scleral punch • Peripheral iridectomy• Closure

Anterior lip sclerectomy:• Incision - at the corneoscleral sulcus • Excise the 1-mm semicircle of tissue.• Button holing of the conjunctival flap .

• 3.Trephination:•  Corneoscleral trephination, using a 1–2-

mm glaucoma trephine, is a difficult procedure.

• Performed only occasionally.

4.Iridencleisis:• Wedge of iris is incarcerated into the

limbal tissue . The presumed mechanism was a ‘wicking’ of aqueous by the iris tissue.

 • However, reports of chronic iritis, infection,

and sympathetic ophthalmia led to other techniques being explored

Complications:

• Shallow (or flat) anterior chambers:

• Peripheral anterior synichae,

• Corneal decompensation.

• Premature cataract formation,

• and infections.

Guarded Filtration Procedure: Trabeculectomy :

Introduced by: Cairns in the 1960s. Indications: • Intraocular pressure too high to prevent

further glaucoma damage and• functional visual loss.• Documented progression of glaucoma damage

at current level of intraocular• pressure with treatment.• Presumed rapid rate of progression of

glaucoma damage without intervention.• Poor compliance with medical therapy: cost,

inconvenience, understanding of• disease, refusal.• Intolerance to medical therapy due to side

effects.•

Anesthesia

• General anesthesia

• Local : Retrobulbar local block, peribulbar block , subtenon’s, or

• Topical anesthesia in selected cases.

Technique Clear corneal traction suture: • 7-0/ 8-0 vicryl• half thickness • 2 mm anterior to the limbus.

The Conjunctival Flap:

Site: Superior and slightly nasal.

Both limbus and fornix based conjunctival flaps

Limbus-Based FlapAdvantages:•  allows tight wound

closure.•  relatively easy to

master.

 Disadvantages:• ‘migrates’ towards

the limbus.

• more chances of incapsulated bleb. 

Fornix-Based Flap

Advantages: • easier exposure of

the surgical site • reduced handling of

the conjunctival flap.

 Disadvantages: • longer operative

time.

•  may leak in the postoperative period and fail to retain aqueous, so that the bleb flattens.

Antimetabolites :

Agents 5-FU inhibits DNA synthesis and RNA

function; usual intraoperative dose is 50 mg/mL.

 MMC alkylates DNA and inhibits DNA and RNA synthesis; usual dose is 0.2–0.4 mg/mL.

Prepare sponges: cut to size and then soaked in the antimetabolite

Place sponge under the conjunctival flap (and under scleral flap in resistant cases) for appropriate duration (5 min for 5-FU; 2–4 min for MMC)

Scleral Flap

The anterior chamber is entered under the flap, and a block of tissue

approximately 1.5–2.5 mm wide is removed with a Descemet’s punch just

anterior to the scleral spur.

Removal of the trabeculectomy block too posterior to the scleral spur offers no

advantage and increases the risk of hemorrhage

Peripheral iridectomy.

Flap Suturing

The scleral flap is reapproximated with 9-0 or 10-0 nylon sutures .

Releasable suture

Peng Khaw’s adjustable suture technique allows a titrated outflow

A careful running suture in two layers, first closing Tenon’s and then its overlying conjunctiva at the limbus.

Postoperative lasering, adjustment, or release of sutures :Argon green, argon blue-green, diode, YAG

laser or krypton red laser. Four-mirror Zeiss gonioprism or with the

Hoskins laser suture lens .

 High-magnification suture lysis contact

lenses are commercially available (e.g., Mandlekorn lens or Blumenthal lens )

 

Complications and management: 

Complications

Intra-operative Post-operative

Early Late

Intraoperative Complications

Conjunctival button hole

Scleral flap damage

Vitreous loss

Flat anterior chamber:choroidal hemorrhage , choroidal

expansion,aqueous misdirection

Bleeding:Conjunctiva, sclera,iris or

suprachoroidal

Prevention: non toothed forceps

Management: small : spontaneous healing (with hold steroid drops)focal (1-2mm) : closure with 10-0 nylon

Before or after sclerostomy

Management: Before sclerostomy: new siteAfter sclerostomy : Minor : suturing with 10-0 nylonSevere : scleral patch graft , tenon’s capsule , fascia lata

Causes: thin sclera( buphthalmic eye), aphakia, post trauma, lens dislocation.

Management : anterior vitrectomy

Preoperatively:Identify the risk factors.

Discontinuation of anticoagulants.

Intraoperatively:Topical apraclonidine 1 % or adrenaline

Minimal handling of tissues

Maintain intraoperative IOP.

Management :All wounds should be promptly closed

Reformation of the anterior chamber

SCH extensive: drainage of blood by

emergency

pars plana sclerostomy

• Choroidal expansion: secure the wound; Perform posterior sclerotomy that does not perforate choroid , administer atropine.• Suprachoroidal hemorrhage:Recognize vitreous loss; secure the wound; perform posterior sclerotomy over choroidal elevation area to drain blood; administer atropine

Postoperative complications

Early

Shallow AC

High IOP

Low IOP

Infection

Blebitis Endophthalmitis

Wipe out phenomenon

Early

Shallow AC

Low IOP

Formed Bleb

Flat Bleb

Over filtration

Causes:• Antimetabolites • Loose sceral flap sutures• Full thickness procedures

Management :• Cycloplegics • +/- aqueous suppressants• Decrease steroids• Pressure patching• Simmons shell, SCL

Flat AC:• Reformation :• Visoelastics / BSS• Large choroidal effusions may need drainage

Shallow AC

Low IOP

Flat Bleb

Wound LeakPressure patch Temporary tapering of

topical steroids Large diameter SCL Cyanoacrylate Glue Injection of autologous

bloodSurgical repair (larger

holes)Conjunctival autograft

Indian J Ophthalmol. 2011 January; 59

Shallow AC

Low IOP

Serous choroidal detachment

• Due to Hypotony

• Prolongs the hypotony

• Vicious cycle

Management :• Cycloplegics , topical steroids• Surgery :• Kissing choroidals• Flat AC , compromised cornea• Eyes with chronic angle closure glaucoma with extremely shallow AC, after trabeculectomyDellaporta Technique

Low IOP

CB Shutdown

• Excessive inflammation Steroids Atropine• Avoid beta blockers, CAI

inhibitors

Cyclodialysis cleft

• Identify with gonio or UBM• Atropine, decrease steroids• Argon laser with Goldmann

lens• Treat the scleral region of

the cleft• For large cleft, definitive

management is surgical repair

Shallow AC

High IOP

Pupillary block Suprachoroi

dal heamorrhag

e

Malignant glauma

• Non patent PI

• Management:

Laser PI

Mydriasis

Topical steroids

• Dark choroidal swelling

• Typical symptoms:

• sudden loss of visionpainnausea and/or

vomiting

• Diagnosis• Indirect • B-scan

• Management• Aqueous

suppressants,• Hyperosmotics ,

Pain relief,• Drainage

• Very shallow or flat central AC

• Look for patent iridotomy

• Aqueous suppressants

• Cycloplegics, topical steroids

• YAG anterior vitreous face (aphakic/pseudophakic)

• Pars plana vitrectomy

• Vigorous surveillance

• Attention to the fellow eye.

• Filtration failure:• Obstruction of the sclerostomy and scleral

flap may be internal (incarceration of iris, ciliary processes, or vitreous), scleral (fibrin, blood),

• or external (overly tight scleral flap sutures). • Consider bleb massage, removal of

releasable suture(s), loosening of adjustable suture(s), and argon laser lysis of fixed suture(s).

• Visual loss: • Wipe-out of the remaining field may occur in

the presence of a vulnerable optic nerve (associated with increased IOP or hypotony) or

• Hypotonous changes may lead to reduced acuity (e.g., from maculopathy).

  

Infection 

Blebitis: - a painful red eye, possibly with mucus discharge and photophobia.

 The bleb is milky with loculations of pus,

conjunctival injection (especially around thebleb), and increasing IOP.

 Identify organism with culture/swab of bleb. Treat with intensive topical antibiotics and systemic

antibiotics.

Consider addition of topical steroids after 24 hours and add mydriatic if AC activity is present.

    

Endophthalmitis:

Clinical features are the same as for blebitis but are more severe, with decreased VA and vitritis.  Investigate and treat as for other postoperative endophthalmitis.

However, endophthalmitis occurring after trabeculectomy tends to run a more aggressive course with a worse prognosis than after cataract surgery. 

c

Late postoperative complications

a)Leaking bleb: antimetabolite-associated or nonguarded filtration surgery

Small leaks : often resolvesOtherwise, : consider bandage contact lens,

autologous blood injection, compression sutures, or refashioning of bleb.

 b)Infection:(blebitis/endophthalmitis). c)Visual loss: Cataract .There can also be

induced astigmatism, maculopathy, and glaucomatous progression.

   

Failure of the Filtering Bleb:Early Failure of Filtering Bleb:Presentation: high IOP, deep anterior chamber,

and low and hyperemic bleb.

Preventive measures:

Postoperative topical steroids are routinely used. The use of antifibrotic agents.

Manoeuvres to improve bleb function:Digital ocular compression and focal compression Laser suture lysis or removal of an externalized

releasable suture

Late Failure of Filtering Bleb:

Most common cause : subconjunctival-episcleral fibrosis .

Factors accelerating fibrosis are: black race, childhood, postoperative

subconjunctival hemorrhage, the presence of reactive sutures, and inflammation.

“Warning signs” - increased bleb vascularization, bleb inflammation, and/or bleb thickening, high IOP.

Treatment : In cases of subconjunctival-episcleral fibrosis

- an external revision or blebneedling can be tried along with

antimetabolites.

Encapsulated Blebs:Localized, elevated, and tense filtering blebs,

with vascular engorgement of the overlying conjunctiva and a thick connective tissue

Tenon’s cystSecond to fourth postoperative week as a

tense, “tight-appearing”bleb. 

Temporary IOP reduction : aqueous suppressants .

Bleb needling with antimetabolites is an option in case of sustained raised IOP.

Failing all measures, a surgical bleb revision (partial/ complete cyst excision) or repeat trabeculectomy may be required, especially in cases of multiloculated cysts.

Other bleb related complications:

Complications….Cataract: flat anterior chamber

reformation of the anterior chamber with air lens trauma inflammation the use of – steroids , intraoperative

MMC

Ptosis : superior rectus bridle suture MMC damage to superior rectus.

Astigmatism: large scleral flaps. radial flap sutures.

Glaucoma Drainage Devices

Indications:• Failed trabeculectomy• Extensive conjunctival scarring• Likely failure of trabeculectomy, including - • Neovascular glaucoma• Uveitic glaucoma• Glaucoma associated with penetrating

keratoplasty• ICE syndrome• Epithelial downgrowth• Refractory pediatric glaucoma

Valved

• Only drains fluid at a certain IOP.

• Valve opens and fluid is drained into a reservoir where it is absorbed by surrounding tissues(e.g., Krupin or Ahmed valves).

Non- Valved

• Nonvalved implants or open tube drainage devices provide little resistance to aqueous flow during the early postoperative period until a fibrous capsule forms around the plate.(e.g., Molteno or Baerveldt implants).

Two main classifications of implants

RESERVOIR PLACEMENT

• The scleral bed is exposed with a fornix-based conjunctival flap.

• Superior quadrant (supero temporal quadrant) is preferred.

• All plates have eyelets on the anterior edge for securing the

implant to the sclera with a non-absorbable (suture#6-0 Mersilene ).

• The plate should be positioned posterior to the insertion of the rectus muscles; 8–10 mm is measured with calipers from the limbus to the central plate edge.

TUBE ENTRY.

The tube is trimmed so that there is a bevel facing anteriorly and 2 to 3 mm will appear within the anterior chamber .

• After scrutiny for the ideal tube entry site, a 23-gauge needle is passed through the limbus to create a tight entry site. The tube tip should not be touching either the cornea or lens.

• Tube is secured to sclera using 9-0/10-0 nylon suture.

Some surgeons construct a scleral tunnel to cover the tube.

Usually the tube is covered with some sterile biodegradable tissue, such as donor sclera, pericardium, or dura, all of which seem to be equally efficacious.

The conjunctiva is repositioned to carefully cover the tube and overlying patch graft.

WOUND CLOSURE

Modifications

• To avoid overfiltration and hypotony in the early postoperative period, a two-stage implantation or temporary ligation of the tube may be utilized.

• Two-stage implantation: • Tube is folded back and placed under the patch graft

or beneath an adjacent rectus muscle and can be attached to the episclera with a nylon or silk suture to facilitate identification.

• In the second stage, the tube is inserted 4–6 weeks later after a fibrous capsule (pseudocyst) has formed around the plate.

Modifications…….

• Transient flow restriction techniques :• Aqueous flow can be limited in the early

postoperative period by internal and external occlusion techniques.

Rip-cord suture

Prolene suture ligature at tip of tube

Complications

Excessive drainage : leakage around or down the tube if the occluding suture is loose and results in hypotony and a shallow anterior chamber.

Malposition : endothelial or lenticular touch .

Tube erosion : through the sclera and conjunctiva .

Early drainage failure : blockage of the end of the tube by vitreous, blood or iris tissue .

Late drainage failure : Excessively thick fibrous capsule.

Indian J Ophthalmol. 2011 January; 59

Complications………….

Diplopia: mechanical involvement of the superior oblique muscle if the implant impinges on the superonasal quadrant, or to the elevated space-occupying bleb that can form over the plate, causing restriction and muscular limitation.

NONPENETRATING GLAUMA SURGERY(NPGS)

Indications1.All open-angle glaucomas (especially if): Early surgical intervention required.Monocular patient.Large diurnal fluctuations .2.High risk of choroidal effusions or

hemorrhages. 3.High risk of postoperative hypotony. 4.Uveitic glaucoma without extensive PAS.5.Congenital glaucoma.

NPGS

Deep Sclerectomy Viscocanalostomy

Deep sclerectomy:

The sclera is exposed and a superficial scleralflap measuring 5 5 mm is dissected, including one-third of the scleral thickness

The superficial scleral flap is one-third of the scleral thickness and is dissected 1--1.5 mm into clear cornea.

The deep sclerectomy measures 4 4 mm and the sclera isdissected, leaving about 5% of sclera over the choroidand ciliary body.

The Schlemm’s canal is identified.The sclerocorneal dissection is prolonged anteriorly 1--1.5 mm using a ruby blade or a crescent knife, in order to remove the sclerocorneal tissue behind the anterior trabeculum and Descemet’s membrane.

When the anterior dissection is completed, thedeep scleral flap is removed by cutting anteriorly first with the diamond blade.

The inner wall of the Sclemm’s canal and the juxtacanalicular trabeculum are peeled off using fineforceps.

A collagen implant is sutured in the scleral bed.

Surv Ophthalmol 53 (6) November--December 2008

After excision of the deep tissue containing a portion of Schlemm’s canal, the remainder of Schlemm’s canal can be accessed by insertinga fine-tipped cannula into the exposed ostia of Schlemm’s canal.

Injection of viscoelastic material into Schlemm’s .

Repeated 6-7 times.

Injection of viscoelastic beneath the superficial scleral flap.

Suture the superficial scleral flap tightly.

Viscocanalostomy

Advantages Disadvantages

No sudden decompression of anterior chamber

Suprachoroidal hemorrhage less likely

Serous choroidal detachment less likely

Reduced risk of prolonged hypotony

Less likely to get filtering bleb

Less chance of bleb leak – early or late

Less chance of blebitis, endophthalmitis

Contact lens wear less likely to be problematic

Bleb dysthesia rareLess intraocular

inflammationLess chance of intraocular

bleedingMore rapid visual

rehabilitation postoperatively

Technically more difficult.Takes longer in the operating

roomRequires some specialized

instrumentation.About 10% have actual

perforation into anterior chamber requiring iridectomy.

Intraocular pressure less likely to be lowered sufficiently in advanced glaucoma.

Pressure lowering may not last as long

It is important to remember that these procedures are in evolution and refinements are necessary.

Complications of deep sclerectomy

Conversion to trabeculectomy because of penetration through trabecular meshwork.

Scleral ectasia.Iris incarceration, prolapse or peripheral

anterior synechiae.Descemet’s detachment.Hypotony.Hyphema.Serous choroidal detachment.Vitreous hemorrhage.Late anterior chamber bleeding during

gonioscopy.

Contraindications:

1.Trabecular meshwork obstructed:• Extensive synicheal angle closure.• Neovascular glaucoma.• Occludable angle.

2.Altered anatomy:• Thin sclera.• Significant limbal scarring.

3. Post laser trabeculoplasty.

4.Angle recession glaucoma.

I. The Ex-Press mini glaucoma shunt

II.Nonpenetrating Ab Externo Schlemm’s Canaloplasty

III. Ab Interno Devices: The Trabectome and Micro-bypass Stent

IV.The Gold Microshunt: A Suprachoroidal Device

Recent advances in glaucoma surgeries

The Ex-Press mini glaucoma shunt

Originally developed to be implanted subconjunctivally through the limbusRedesigned - trabeculectomy style scleral flap.

Long term success – yet to be established.

Canaloplasty

Nonpenetrating Ab Externo Schlemm’s Canaloplasty

A superficial parabolic flap of approximately 250- to 300-2m thickness, 4.5 _ 4.5 mm, is made.

Deeper scleral flap is created with slightly smaller dimensions than that of the superficial flap.

Schlemm’s canal is exposed with a crescent blade

the trabeculodescemet window (TDW) can be seen.

Once the entire circumference of the canal has been cannulated with the iScience microcatheter, the device is primed with ophthalmic viscosurgical device, which can be seen emerging from the tip of the device on the right.

A 10–0 Prolene suture is tied around the end of the deviceprior to its retraction.

Once the suture has been delivered and cut away from the microcatheter, the two cut ends must be matched and tied together.

• The superficial scleral flap is then placed back into position and sutured interrupted 10–0 nylon sutures.

• High viscosity sodium hyaluronate is then injected under the superficial scleral flap using the viscocanalostomy cannula in order to maintain the scleral lake – the space where aqueous humor that has percolated through the TDW accumulates and is then absorbed into episcleral, scleral, and choroidal circulation.

• The conjunctiva is then closed with a 10–0 Vicryl suture.

Techniques in Ophthalmology 5(3):102–106, 2007

Advantages: Drawbacks:

• Absence of vision-threatening

complications such as:

• Choroidal detachments,

• Shallow or collapsed anterior chambers, and

• Prolonged hypotensive

periods.

Descemet’s tear.

Elevated postoperative pressure

( possible inflammatory changes in the canalicular structures).

Difficult procedure, which needs an experienced deep sclerectomy or viscocanalostomy surgeon.

Shunts into

schlemm’s canal

The Trabecto

me

Micro- bypass Stent

Ab Interno Devices: The Trabectome and Micro- bypass Stent

 

Trans Am Ophthalmol Soc v.104; Dec 2006 

Microelectrocautery handpiece designed to ablate trabecular meshwork and Schlemm’s canal inner wall tissue over an area of several clock hours..The device is a disposable handpiece that is activated by foot pedal control connected to a console that allows the surgeon to adjust infusion, aspiration, and dissipated electrosurgical energy.

• A clear corneal near-limbal 1.6-mm keratome incision is made. Viscoelastic may or may not be necessary to allow safe insertion of the instrument tip to allow infusion flow and anterior chamber stability.

• Surgical tip is advanced under gonioscopic control to engage nasal meshwork before activating aspiration and ablation by progressively depressing the foot pedal and rotating the tip parallel to the iris just anterior to the scleral spur.

• Ablation with continual infusion and aspiration is performed along an arc of 30 ° to 60°.

Two functions: 1. providing direct access of aqueous into the schlemm’s from the anterior chamber (the snorkel effect) and 2. pushing the anterior trabecular meshwork away from the posterior wall of Schlemm’s canal.

Click icon to add picture

The Gold Microshunt: A Suprachoroidal Device

Click icon to add picture

Arch Ophthalmol. 2009;127(3):264-269.

Postoperative clinical image of a patient after Gold Micro Shunt implantation. Note the good position of the shunt in the anterior chamber (A), with no shunt-corneal or shunt-iris touching, as seen in the gonioscopic view (B).

Arch Ophthalmol. 2009;127(3):264-269.

Endoscopic Cyclophotocoagulation:

Indications:•In cases of refractory glaucoma•Patients on maximum medical therapy showing continued progression of disease were often considered as appropriate candidates.•Patients who had failed filtration surgery or were considered at high risk for failure or complications post-traditional filtration procedures.

•Better visualization of the tissue being treated •Less destructive method of applying the laser,

ECP employs - 810-nm diode laser,

allows the surgeon to precisely

aim and deploy the laser to cause

effective cycloablation while

avoiding damage to adjacent

structures.

Extensive contraction of the ciliary processes was observed as well as changes to the ciliary body epithelium.

There was much less destruction (if any) to the ciliary body muscle

Procedures of historical importance:

Cyclodialysis was once a mainstay in the management of aphakic glaucoma. Its principle was to mechanically disrupt the iris root at its scleral spur attachment so that a cleft was created between the anterior chamber and suprachoroidal space.

Significant hemorrhage was almost unavoidable, as was hypotony resulting from an overfunctioning cleft, which if spontaneously healed would lead to a precipitous rise in IOP.

Other common complications included cataract and stripping of Descemet’s membrane. With so many more physiologic options for surgical control of the IOP, this procedure is now of historical relevance only.

References1.Becker-Shaffer's Diagnosis and Therapy of the Glaucomas, 8e 

Robert L. Stamper MD , Marc F. Lieberman MD , Michael V. Drake MD 

 2. Shields Textbook of Glaucoma (Allingham, Shields' Textbook of Glaucoma) Karim F. Damji , Sharon Freedman , Sayoko E. Moroi (Editor),  M. Bruce Shields. 

 3. Kanski's Clinical Opthalmology: A Systematic Approach 6th Ed .Mohd Zafrullan Zamberi Ophthalmology.

 4. Oxford American Handbook of Ophthalmology. James C. Tsai, MD, MBA.

 5. The glaucomas:  concepts and fundamentals.Tarek M. Eid ,George L. Spaeth.

6. The Glaucoma Book A Practical, Evidence-Based Approach to Patient Care Editors

Paul N. Schacknow , John R. Samples

 7. Yanoff & Duker: Ophthalmology, 3rd

8. The role of artificial drainage devices in glaucoma surgery(Indian Journal of Ophtahlmology.)1998(46):1,41-46.R Thomas, A Braganza, G Chandrasekhar, S Honavar, AK Mandal, R Ramakrishnan, BS Rao, R Sihota, NN Sood, B Shantha, L Vijaya .Christian Medical College, Vellore, Chennai, India.

9. Nonpenetrating Glaucoma Surgery.Efstratios Mendrinos, Andre´ Mermoud, and Tarek Shaarawy, Surv Ophthalmol 53:592--630, 2008.