LASIK Hyperopic Astig

Ophthalmic Technology Assessment

LASIK for Hyperopia, HyperopicAstigmatism, and Mixed AstigmatismA Report by the American Academy of Ophthalmology

Gary A. Varley, MD, David Huang, MD, PhD, Christopher J. Rapuano, MD, Steven Schallhorn, MD,Brian S. Boxer Wachler, MD, Alan Sugar, MD, MS

Objective: To describe LASIK for hyperopia, hyperopia with astigmatism, and mixed astigmatism and toexamine the evidence to answer questions about the safety and efficacy of the procedure.

Methods: A literature search conducted for the years 1968 to 2002 retrieved 118 citations. During reviewand preparation of this article, an additional 2 articles were included. The panel members selected 36 articles forthe panel methodologist to review and rate according to the strength of evidence. A level I rating is assigned toproperly conducted, well-designed, randomized clinical trials; a level II rating to well-designed cohort andcase–control studies; and a level III rating to case series, case reports, and poorly designed prospective andretrospective studies.

Results: This assessment describes 5 nonrandomized interventional trials (level II), 3 nonrandomized com-parative trials (level III), and 20 noncomparative case series (level III). Additionally, 6 single-case reports (level III)were included because they reported relevant complications, and 2 theoretical analyses (level III) were alsoconsidered. This assessment does not compare studies because many variables such as range of hyperopia,follow-up periods, lasers, microkeratomes, techniques, and surgeon experience have not been controlled.

Conclusions: For low (�3 diopters [D]) to moderate (3–5 D) hyperopia, results from published studies (levelsII and III evidence) have shown that LASIK is effective and predictable in achieving very good to excellentuncorrected visual acuity, achieving postoperative refractions within 1 D of emmetropia, and is safe in terms ofminimal loss of best-corrected spectacle vision. Although there are fewer data for hyperopic astigmatism, theresults available seem to mirror the data for low to moderate hyperopia (levels II and III evidence). Thepostoperative results for both uncorrected vision and safety are less compelling, as greater amounts of hyperopiaare treated (�4 to 5 D). Utilizing hyperopic LASIK for the treatment of consecutive hyperopia and astigmatism isalso effective, although the ability to reduce hyperopic astigmatism after radial keratotomy is limited. Although avariety of ablation profiles can be used to treat mixed astigmatism, very good visual results have been reported(levels II and III evidence). Serious adverse complications leading to permanent visual loss are possible but,fortunately, very rare. There are insufficient data to compare one laser system with another or one ablation profilewith another. Ophthalmology 2004;111:1604–1617 © 2004 by the American Academy of Ophthalmology.

Introduction

The American Academy of Ophthalmology prepares Oph-thalmic Technology Assessments to evaluate new and ex-isting procedures, drugs, and diagnostic and screening tests.The goal of an assessment is to review systematically theavailable research for clinical efficacy, effectiveness, andsafety. After review by members of the Ophthalmic Tech-nology Assessment Committee, other Academy commit-tees, relevant subspecialty societies, and legal counsel, as-

Manuscript no. 240408.

Prepared by the Ophthalmic Technology Assessment Committee Refrac-tive Surgery Panel and approved by the American Academy of Ophthal-mology’s Board of Trustees November 15, 2003.

1604 © 2004 by the American Academy of OphthalmologyPublished by Elsevier Inc.

sessments are submitted to the Academy’s Board ofTrustees for consideration as official Academy statements.

Background

Laser in situ keratomileusis is commonly known as LASIK,a term used by Pallikaris et al1,2 to describe a new techniqueto correct myopia and astigmatism. It is a procedure that hasevolved from a variety of techniques in refractive surgery.

Keratomileusis, including both freeze and nonfreezetechniques, was first used in the United States in the 1970s.Its refractive effect is achieved on the removed disc of theanterior corneal stroma and requires resuturing the disc tothe corneal surface. These procedures were followed byautomated lamellar keratoplasty, in which a microkeratome

ISSN 0161-6420/04/$–see front matterdoi:10.1016/j.ophtha.2004.05.016

American Academy of Ophthalmology � Ophthalmic Technology Assessment

is used to create a free, or hinged, corneal flap or cap. Tissuefrom the corneal bed is removed to alter the refractive error,and the corneal flap is repositioned.

After the ophthalmic excimer laser was developed, it wasused to reshape the surface of the cornea in a techniquecalled photorefractive keratectomy.3 Laser keratomileusiswas initially performed on an excised corneal cap, but thisproved to be problematic. In LASIK, a corneal flap iscreated using a microkeratome, after which excimer laserablation of the stromal bed reshapes the cornea, and the flapis replaced.4 This technique, which has been developed asan alternative to photorefractive keratectomy, has the fol-lowing potential advantages:

● Earlier postoperative stabilization of refraction● Less postoperative patient discomfort● Faster improvement in visual acuity (VA)● Less stromal haze formation● Possibly improved predictability, stability, and corneal

clarity in higher correction groups● Shorter duration of postoperative medication use● Easier enhancement procedures

The surgical correction of hyperopia has lagged behindthat of myopia. Early attempts at hyperopic correction withprocedures such as hexagonal keratotomy, automated la-mellar keratoplasty, epikeratophakia, thermokeratoplasty,and keratophakia have had limited success. Most of theseprocedures have been abandoned.

With the success of excimer laser ablation for the treat-ment of myopia and astigmatism, investigation into theability to treat hyperopia was a logical step. To steepen thecentral cornea, however, improvements in laser technologywere required to treat the peripheral cornea. This occurredwith scanning laser delivery systems.

Preoperative Evaluation

The preoperative evaluation of a potential refractive surgerypatient consists of a comprehensive ophthalmologic exam-ination and begins with a complete medical and ophthalmo-logic history.5,6 The medical history may identify one ofseveral systemic conditions that may represent relative orabsolute contraindications to surgery. For example, a his-tory of uncontrolled connective tissue disease such as rheu-matoid arthritis is considered a contraindication for LASIK.Other conditions such as diabetes mellitus represent poten-tial problems for the LASIK patient and need to be dis-cussed in advance. An occupational history should be in-cluded in the medical history, because patients requiringperfect night vision may be poor candidates, depending ontheir scotopic pupil size and refractive error. Certain sys-temic medications may also represent a contraindication toLASIK.

The ophthalmic history is as important as the medicalhistory. A history of herpes simplex or zoster keratitis is arelative contraindication for LASIK. Patients with a historyof recurrent corneal erosions may do better with photore-fractive keratectomy than with LASIK. The history of re-fractive status and previous refractive correction is alsoimportant to consider. For example, patients who wear

contact lenses should discontinue their use before the pre-operative examination and procedure. As a general guide-line, spherical soft contact lenses should be discontinued forat least 1 week, and toric soft lenses and rigid lenses shouldbe discontinued until refractive and keratometric stabilityhas been documented.7 Corneal topography and repeat re-fractive measurements will help to identify any evidence ofcorneal warpage or refractive instability. Documentation ofrefractive stability may be obtained in the ocular history andis usually considered �0.5 diopters (D) of change over �1years.

The comprehensive ophthalmologic examination of thepotential refractive surgery patient includes some elementsnot always performed in a routine eye examination:

● Visual acuity with and without correction. Althoughbest-corrected VA (BCVA) is typically determined inany comprehensive eye examination, vision withoutcorrection should also be included.

● External examination. Periocular anatomy may impactthe ability to make a corneal flap and should be eval-uated in the preoperative examination. In addition,periocular abnormalities such as a chalazion may in-duce refractive changes.8

● Pupil examination with documentation of scotopic pu-pil size. Because increasing pupil size may be corre-lated with increased postoperative vision disturbancessuch as halos and glare, this measurement must beperformed and the results discussed before the proce-dure.9 Differences in glare complaints in hyperopicLASIK as compared with myopic LASIK have notbeen well established. In addition, the relationshipbetween pupil diameter and visual disturbances suchas halos and glare is controversial.10,11

● Ocular motility and alignment assessment. An unrec-ognized, minor strabismus controlled with a prism inglasses can be associated with an exacerbation ofdiplopic symptoms after LASIK surgery.

● Refractions both undilated and under cycloplegic con-ditions. To uncover any latent hyperopia, the cyclo-plegic refraction is especially important.

● Slit-lamp biomicroscopy with careful attention to thecornea, anterior chamber depth, and lens. Becausepatients who undergo LASIK for hyperopia are, onaverage, older than their myopic counterparts, thepresence of cataracts may be more likely. Anatomi-cally narrow angles may be more frequent because ofhyperopia and older age. Examination of the cornea isintended to detect any pathology that may represent acontraindication to LASIK. For example, Fuchs’ en-dothelial dystrophy has been associated with poor flapadhesion and corneal decompensation. Patients withanterior basement membrane dystrophy have an in-creased risk of epithelial sloughing at the time ofsurgery and later epithelial ingrowth and diffuse la-mellar keratitis, which may be an indication for pho-torefractive keratectomy rather than LASIK.12 Signif-icant blepharitis should be treated preoperatively todecrease the risks of infection and interface inflamma-tion after surgery. The ocular surface should be eval-

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Ophthalmology Volume 111, Number 8, August 2004

uated carefully before surgery, and patients should bewarned about the potential postoperative developmentor exacerbation of dry eye symptoms.13,14

● Fundus examination. Although retinal detachments areless common in the hyperopic patient group than inmyopic patients, the retina should be evaluated beforeany LASIK procedure.

● Corneal topography. Corneal topography measure-ment to assess corneal shape is a critical feature of thepre-LASIK evaluation. It can detect irregular astigma-tism, whether from contact lens warpage or from othercauses, which, if significant, is a contraindication tospherocylindrical LASIK. Additionally, corneal to-pography is used to screen for keratoconus or asym-metrical steepening, which may be associated withunpredictable refractive outcomes and progressive ec-tasia after LASIK.15 Inferior corneal steepening,sometimes designated as forme fruste keratoconus, is afrequent finding in corneas that appear normal onslit-lamp biomicroscopy. Mathematical indices to de-tect subtle keratoconus topographically have been de-veloped.16 Flat corneas are important to note preoper-atively, because they are associated with smallmicrokeratome flaps and free caps, and steep corneasare associated with flap buttonholes.17 Corneal topog-raphy is also useful in predicting the final keratometryafter refractive surgery. Central keratometry steeperthan 49 to 50 D after LASIK may be associated witha decrease in quality of vision.

● Corneal pachymetry. Although the depth of the abla-tion is rarely a problem in hyperopic patients, normalcorneas may be as thin as 450 �m centrally. In thesethin corneas it may be unsafe to make a corneal flap.

The preoperative evaluation of a potential LASIK patientconcludes with a discussion of goals and expectations of theprocedure as well as with obtaining informed consent aftera discussion of the potential risks, benefits, and alternatives.The discussion of risks should include not only potentialcomplications but also possible side effects such as dry eyeand night vision disturbance. There should be sufficienttime to answer all of the patient’s questions. The surgeon isresponsible for obtaining the patient’s informed consent.

Microkeratome IssuesIdeally, the microkeratome should cut flaps within a narrowrange of acceptable thickness. A microkeratome that tendsto cut thin flaps is more likely to produce buttonholes. Onthe other hand, thick flaps leave a thinner corneal bed andlimit the amount of ablation that can be performed safely.Based on case reports and biomechanical considerations, aresidual posterior stromal thickness of at least 250 �m hasbeen recommended to reduce the risk of post-LASIK kera-tectasia18–20; however, there is no absolute value that guar-antees that ectasia cannot occur. In addition to this mini-mum stromal bed thickness, Joo and Kim21 suggest that thestromal bed should be at least over half of the originalcorneal thickness. In calculating expected residual thick-ness, the average flap thickness and its range of variation aswell as the estimated ablation depth should be considered.

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To help ensure an acceptable final postoperative residualstromal thickness, flap thickness is often measured by in-traoperative subtractive pachymetry, taking the differencebetween ultrasound pachymetry measurements of the intactcornea and the posterior stromal thickness after the micro-keratome cut.22–28 Although corneal thickness issues areless of a concern with hyperopic LASIK, they should beconsidered in any lamellar treatment.

Because the ablation diameter is much greater with hy-peropic corrections, the flap diameter becomes an importantissue. The diameters of flaps are typically reproduciblewithin a standard deviation of �0.4 mm.22,27 Steeper cor-neas are associated with larger flaps.27 Manufacturers des-ignate predicted flap diameters for each suction ring, pro-vide nomograms for predicted flap diameters givenkeratometry and suction ring designation (e.g., the Carriazo-Barraquer and M2 [Moria, Doylestown, PA]), or provideintraoperative flap diameter estimation (e.g., SummitKrumeich-Barraquer, Alcon, Fort Worth, TX). In choosinga microkeratome for a hyperopic LASIK procedure, oneshould be confident that the ablation will fit into the stromalbed made by the microkeratome. When dealing with an eyethat has hyperopia as a result of a myopic LASIK procedureperformed with a smaller flap diameter, Jacobs et al29 havedemonstrated safe and effective results without recutting alarger flap.

Alternatively, the flap can be created with a femtosecondlaser. Potential advantages and disadvantages of this tech-nology are being studied.

Operative Technique

Before surgery, the technician and the surgeon should checkthe excimer laser, suction ring, microkeratome, and blade.The surgeon should confirm the identity of the patient, theoperative eye, and that the correct treatment parametershave been entered into the laser computer. An eye drapemay be used as necessary to keep the eyelashes out of thesurgical field. An eyelid speculum is inserted in the opera-tive eye, which has been anesthetized topically, and thefellow eye is covered. The cornea is marked with an instru-ment and dye to aid in postoperative flap or free-cap align-ment. To raise the intraocular pressure (IOP), a suction ringis placed on the eye, and the surgeon verifies adequateelevation using a combination of techniques that includenoting pupil dilation; using finger tension, a contact appla-nation device, or a pneumotonometer; and the patient’sreport of dimming of vision. The microkeratome is used toperform a lamellar keratotomy and create a hinged cornealflap with adequate central clearance for the treatment zoneof the excimer laser ablation. To achieve an adequate stro-mal bed, decentration of the flap toward the hinge may benecessary. Depending on the microkeratome used, the flaphinge may be superior, nasal, or oblique. Depending on totalcorneal thickness, the flap thickness chosen for a particularmicrokeratome may be between 110 and 180 �m.

After the flap has been created, it is reflected above andaway from the cut exposed surface, and the stromal bed isexamined for regularity and size. The location and size ofthe hinge should be inspected, as it may need to be protected


during the ablation. If the quality of the flap and stromal bedare adequate, the excimer laser ablation is performed cen-tered on the entrance pupil, the corneal light reflex, or apoint in between. Studies are currently under way to deter-mine which point is best to center the hyperopic treatment.Centration seems to be more important in the correction ofhyperopia than myopia, and an eye tracker is helpful tomaintain centration. After ablation, the flap is repositionedwith irrigation of the interface. Once flap alignment isverified and the peripheral gutters are inspected and foundto be minimal and symmetric, the flap is allowed sufficienttime to adhere. The eyelid speculum is carefully removedwithout disturbing the flap. The eye may be examined at aslit-lamp biomicroscope after the procedure to verify flapposition and appearance.

If the flap created during the LASIK procedure is irreg-ular, incomplete, or buttonholed, or if there is inadequatestromal exposure, laser treatment often cannot be performedsafely in the same session. However, after a healing period,a recut and ablation may subsequently be performed suc-cessfully in some cases.30

Postoperative Management

Patients may have mild postoperative discomfort for a fewhours after LASIK treatment, during which time they can beadvised to rest with their eyes closed. Patients should beadvised to refrain from rubbing their eyes for at least severaldays or, preferably, several weeks after surgery. Topicalantibiotics and corticosteroids usually are prescribed aftersurgery, and frequent supplemental lubrication is recom-mended in the postoperative period. Patients should returnfor examination on the day after surgery. In general, patientsare then examined approximately 1 week after surgery andthereafter as appropriate. If dry eye symptoms persist, punc-tal occlusion, nutrient therapy, or topical cyclosporine eyedrops may be considered.

Refractive stabilization for hyperopes may require 3 to 6months, depending on the amount of treatment performed.Reoperations (enhancements) can be considered once therefraction is stable.

Table 1. Food and Drug Administrat

Company and Model Approved Indications for Hypero

Summit Autonomous*LADARVision

Hyperopia �6.0 D with or without a��6.0-D (P970043/S7; Septembe

VISX Star S2/S3(Santa Clara, CA)

Hyperopia between �0.5 and �5.0 Dastigmatism up to �3.0 D (P930016

Bausch & LombTechnolas 217a(Rochester, NY)

Hyperopia between 1.0 and 4.0 D wiastigmatism up to 2.0 D (P990027/S

WaveLight Allegretto Wave(North Reading, MA)

Hyperopia up to �6.0 D with or witho�5.0 D (P030008; October 10, 2003

D � diopters.Source: http://www.fda.gov/cdrh, accessed April 23, 2004.*Now owned by Alcon (Fort Worth, TX).

Food and Drug Administration StatusTable 1 lists the excimer lasers and indications for LASIKthat have been approved by the Food and Drug Adminis-tration (FDA) for the correction of hyperopia, hyperopicastigmatism, and mixed astigmatism.

Microkeratome manufacturers are required to submit a510(k) premarket notification to the FDA to demonstratethat the device to be marketed is as safe and effective as(substantially equivalent to) a legally marketed device thatis not subject to premarket approval. Premarket notificationis required at least 90 days before marketing, unless thedevice is exempt from 510(k) requirements. The FDAdeemed that the microkeratome device is “substantiallyequivalent (for the indications for use stated in the enclo-sure) to devices marketed in interstate commerce beforeMay 28, 1976, the enactment date of the Medical DevicesAmendments, or to devices that have been reclassified inaccordance with the provisions of the Food, Drug, andCosmetics Act (Act).” As a consequence, the microkera-tome manufacturers were given FDA clearance to “marketthe device, subject to the general controls provisions of theAct. The general controls provisions of the Act includerequirements for annual registration, listing of devices, goodmanufacturing practice, labeling, and prohibitions againstmisbranding and adulteration.”

Resource RequirementsTo perform LASIK a surgeon needs to be trained in the useof a microkeratome or a femtosecond laser to create acorneal flap, and an excimer laser to perform the refractiveablation. Each laser company requires that the surgeonsuccessfully complete a course specific to each particularexcimer laser. These courses may be given for free or for afee of upwards of $1000 each.

Most surgeons who perform LASIK do not own a mi-crokeratome or excimer laser. The equipment is typicallyowned by a corporate laser center or a hospital. In somecases, a company will deliver a microkeratome set, mobileexcimer laser, and technical staff to the surgeon so thesurgery can be performed in his or her office. In these cases,the surgeon has minimal startup costs to perform LASIK.

Approved Excimer Lasers for LASIK

d Astigmatism Approved Indications for Mixed Astigmatism

atism of2000)

Mixed astigmatism ��6.0-D sphere with a ��6.0-Dcylinder (P970043/S7; September 22, 2000)

or withoutApril 27, 2001)

Mixed astigmatism up to 6.0 D; cylinder is greaterthan sphere and of opposite sign (P930016/S14;November 16, 2001)

withoutruary 25, 2003)

tigmatism up to

ion–

pia an

stigmr 22,

with/S12;

th or4; Feb

ut as)

1607


Surgeons who wish to have more control over the global feethe patient is charged can lease or buy their own equipment.A microkeratome set costs approximately $40 000 to$60 000, and an excimer laser costs $250 000 to $550 000.

The cost of LASIK surgery to the patient variesgreatly, between approximately $500 per eye and $3000per eye. Depending on the cost, this fee may or may notinclude initial medications, follow-up care, and enhance-ments.

Questions for Assessment

The focus of this assessment is to address the followingquestions:

● What is the efficacy (predictability, stability) ofLASIK for hyperopia and astigmatism and for mixedastigmatism?

FirstAuthor

YearPublished

Level ofEvidence Laser

Follow-up(mos)

No

Ey

Esquenazi* 1999 III Keracor 117 24 1010

233

Argento† 2000 II Keracor 117 12 202225463

el-Agha§ 2000 III VISX S2 12 2Zadok� 2000 III EC-5000 6 4

2Davidorf¶ 2001 II VISX S2 3–6 1

11

Rashad# 2001 III Keracor 117 12 8Tabbara** 2001 III Keracor 117 6 8Cobo-Soriano†† 2002 III Keracor 217C 12 10

9754

Salz‡‡ 2002 II LADARVision 12 14116

AZ � ablation zone; BSCVA � best-spectacle-corrected visual acuity; D �*Esquenazi S, Mendoza A. Two-year follow-up of laser in situ keratomile†Argento CJ, Cosentino MJ. Comparison of optical zones in hyperopic lase‡Value read from a bar graph.§el-Agha MS, Johnston EW, Bowman RW, et al. Excimer laser treat�Zadok D, Maskaleris G, Montes M, et al. Hyperopic laser in situ keratomil¶Davidorf JM, Eghbali F, Onclinx T, Maloney RK. Effect of varying the#Rashad KM. Laser in situ keratomileusis for the correction of hyperopia f**Tabbara KF, El-Sheikh HF, Islam SM. Laser in situ keratomileusis for the††Cobo-Soriano R, Llovet F, Gonzalez-Lopez F, et al. Factors that influen‡‡Salz JJ, Stevens CA, LADARVision LASIK Hyperopia Study Group.

1608

● What are the complications of LASIK for hyperopiaand astigmatism?

Description of Evidence

A literature search was conducted on February 28, 2002using the key words laser in situ keratomileusis and hyper-opia or astigmatism in the MEDLINE and Cochrane Librarydatabases. Publications from 1968 to 2002 in English withonline abstracts were included, and 118 references wereretrieved. Panel members included 2 additional studies thatwere published after the literature search date.

Ophthalmic Technology Assessment Refractive SurgeryPanel members selected 36 articles that they considered tobe of sufficient clinical relevance to submit to the panelmethodologist for review. The methodologist rated the ar-ticles according to the strength of evidence. A level I ratingwas assigned to well-designed and well-conducted random-

Table 2. Recent Publications

OZ(mm)

AZ(mm)

SEChange

Achieved/Entered

Preoperative SE (D)Peoperative

Cylinder(D)

MeanRange Mean

5–7.5 1.25–8.50 4.505–7.5 1.00–4.00 2.75

4.25–8.50 5.235.0 4.186.0 4.057.0 4.12

�2.00 1.31 1.164.4–5.5 7.0–9.1 2.00–3.00 2.56 1.89

�3.00 5.28 2.68�2.00 1.47 1.13

5.9 9.5 2.00–3.00 2.98 1.74�3.00 5.13 1.89

5.0 9.0 0.83 0.88–5.00 1.81 0.215.5 7.5 �3.00 2.02 0.315.5 7.5 3.00–5.00 3.785.0 9.0 0.97 0.38–5.50 2.61 0.535.5 8.5 1.04 0.63–4.13 2.58 0.336.0 9.0 1.12 1.25–3.50 2.28 0.406.0 9.0 1.25–5.00 3.31 0.91

0.50–11.50 3.401.0–2.9 2.003.0–3.9 3.40

5.5–6.0 4.0–4.9 4.40 1.585.0–5.9 5.306.0–7.9 6.50

0.88–6.00 2.56 0.246.0 9.0 0.50–5.75 2.84 1.62

�1.75–2.38 0.23 3.26

ters; OZ � optical zone; SE � spherical equivalent; UCVA � uncorrectedr hyperopia. J Refract Surg 1999;15:648–52.

itu keratomileusis: 5.9 mm versus smaller optical zones. J Cataract Refract

of spherical hyperopia: PRK or LASIK? Trans Am Ophthalmol Socwith the Nidek EC-5000 excimer laser. Ophthalmology 2000;107:1132–7.al zone diameter on the results of hyperopic laser in situ keratomileusis.1.25 to �5.00 diopters with the Technolas Keracor 117C laser. J Refractction of hyperopia from �0.50 to �11.50 diopters with the Keracor 117Ctcomes of hyperopic laser in situ keratomileusis. J Cataract Refract SurgK correction of spherical hyperopia, hyperopic astigmatism, and mixed

o.fes

00

1303516926576585072467375

diopusis for in s

menteusisoptic

rom �corre

ce ouLASI


ized clinical trials, a level II rating was assigned to well-designed case–control and cohort studies, and a level IIIrating was assigned to case series, case reports, and poorlydesigned prospective and retrospective studies.

There were no randomized controlled trials found and,thus, no level I evidence. Five nonrandomized comparativeinterventional trials were given a rating of level II.14,31–34

The majority of the literature, 20 articles, reported noncom-parative case series, which were graded as level III. Sixsingle-case reports, graded level III, were included becausethey reported relevant complications. Two theoretical anal-yses35,36 were also considered to present level III evidence.

The literature on hyperopic LASIK was not as extensiveas that reviewed in the past on myopic LASIK,4 reflectingthe more recent approval of hyperopic LASIK in the UnitedStates (2000, 2001, 2003). This relatively recent experienceis also seen in the inclusion of 9 studies29,37–44 that reporthyperopic LASIK treatment of secondary hyperopia afterother refractive surgical procedures, mostly performed for

on Primary Hyperopic LASIK

DeviationSE (D)

(Mean � SD)

PostoperativeSE (D)

(Mean � SD)

PostoperativeCylinder (D)

Mean

PostoperativeSE within1.0 D (%)

PostoperaSE with0.5 D (%

�0.85�1.74 74 67�0.50�0.50 �0.48�1.10�2.00�1.00 �1.12�1.98

�0.75�1.75�0.47�1.59�0.38�1.57�0.39�0.70 100�0.48�0.75 95�0.88�0.96 71�0.09�0.29 100�0.10�0.31 100�0.48�0.45 94

�0.37�0.44 0.36 92 62�0.30�0.71 89�1.09�0.92 52�0.30�0.92�0.34�0.57�0.82�0.77�0.43�0.57 0.36 89 61�0.26�0.80 84 58

9387

0.13�0.8 0.60 828080

0.05�0.71 91 740.06�0.78 89 73

�0.45�0.64 95 88

visual acuity.

Surg 2000;26:1137–46.

2000;98:59–66, discussion 66–9.

Ophthalmology 2001;108:1261–5.Surg 2001;17:113–22.laser. J Refract Surg 2001;17:123–8.2002;28:1530–8.astigmatism with the LADARVision excimer laser system. Ophthalmolog

myopia initially. Nine studies reported case series of pri-mary hyperopia treatment, and 2 case series described re-treatment of prior hyperopic LASIK eyes.

Published Results: Outcomes of LASIKSurgery

Recent studies on primary and secondary hyperopic LASIKare summarized in Tables 2 and 3, respectively. Table 4summarizes the safety and effectiveness data submitted tothe FDA for premarket approval applications.

LASIK for Hyperopia

In reviewing the literature, it is difficult to compare studiesbecause of variations in the range of preoperative hyperopia,follow-up periods, lasers, nomograms, and microkeratomes.Based on the studies reviewed, hyperopic LASIK in the

UCVA>20/40

(%)

UCVA>20/20

(%)

Loss ofBSCVAof 1 line

(%)

Loss ofBSCVAof >2

lines (%)

Loss ofBSCVAof >2

lines (%)

Time toStability(mos)

82 37 6 5.0 6

82 20‡ 0‡ 6100 28‡ 2‡ 678 5‡ 0‡ �1292 6‡ 0‡ 695 6‡ 0‡ 677 6‡ 0‡ �12

100 55 25 10.0 196 42 0.0 378 26 1.4 �692 34 19 0.0 193 43 13 0.0 188 38 6 0.0 193 25 11 1.2 398 44 1.3

1.81.82.85.8

16.694 54 3.4 394 58 1.4 194 52 0.0 1

2;109:1647–56, discussion 1657–8.

tivein

)

y 200

1609


lower dioptric ranges provides effective correction withgood predictability in terms of obtaining very good uncor-rected VA, and it provides safe treatment in terms of min-imal loss of VA (Tables 2–4).

The correction of high hyperopia is less predictable andless safe than for lower ranges of hyperopia. The cutoffappears to be between 4 and 5 D. Cobo-Soriano et al45

(Table 2) stratified the results of LASIK between 1.0 and7.9 D and found that predictability was significantly worsebeyond 4.0 D and that loss of best spectacle-corrected VA(BSCVA) of �2 lines became significantly more frequentbeyond 6.0 D (level III evidence). A comparative study(level III evidence) by Esquenazi and Mendoza46 (Table 2)concluded that “over 5.00 D, safety and predictability of theprocedure were reduced, and reduction in spectacle-cor-rected visual acuity and undercorrection should be expectedto occur.” Choi and Wilson38 (Table 3) found that primary

YearApproved Laser

Follow-upAvailable

(mos)

Follow-upShown(mos)

2000 Alcon LADARVision 9 6

2001 VISX S2/3 6 62003 Bausch & Lomb

Technolas 217a12 6

AZ � ablation zone; BSCVA � best spectacle-corrected visual acuity; D �

FirstAuthor

YearPublished

Level ofEvidence Laser

PreviousSurgery

Choi* 2000 III VISX S2 NoneM-LASIK

Jacobs† 2001 III VISX Star M-LASIKLindstrom‡ 2000 III VISX S2 LASIK, PRK,

ALK, RKLindstrom� 1999 III VISX S2 None

M-LASIKRojas¶ 2002 III VISX S2 M-LASIKMulhern# 2001 III Keracor 116 H-LASIKAttia** 2000 III Keracor 217 Sunrise LTKFrancesconi†† 2002 III Keracor 217 RKLipshitz‡‡ 2001 III EC-5000 RK

ALK � automated lamellar keratoplasty; AZ � ablation zone; BSCVA � bespherical equivalent; UCVA � uncorrected visual acuity.*Choi YI, Park SJ, Song BJ. Corneal flap dimensions in laser in situ kerato†Jacobs JM, Sanderson MC, Spivack LD, et al. Hyperopic laser in situ‡Lindstrom RL, Linebarger EJ, Hardten DR, et al. Early results of hyperop§Value read from bar graph.�Lindstrom RL, Hardten DR, Houtman DM, et al. Six-month results of h¶Rojas MC, Haw WW, Manche EE. Laser in situ keratomileusis enhance#Mulhern MG, Condon PI, O’Keefe M. Myopic and hyperopic laser in s**Attia W, Perez-Santonja JJ, Alio JL. Laser in situ keratomileusis f††Francesconi CM, Nose RA, Nose W. Hyperopic laser-assisted in s‡‡Lipshitz I, Man O, Shemesh G, et al. Laser in situ keratomileusis

1610

hyperopic LASIK treatments for 5.00 to 8.75 D resulted inloss of 2 lines of BSCVA in 50% of eyes (level III evi-dence). The FDA trial data for the VISX S2/3 (VISX, Inc.,Santa Clara, CA) and the Alcon LADARVision systemswere both limited to eyes with a preoperative sphere of �6D (Table 4). In both series, the percentage that lost �2 linesof BSCVA was at least 10% in eyes with a �4-D preoper-ative spherical equivalent (SE). This contrasted with thegood overall safety profile. Predictability of correction wasalso notably reduced above 5 D in these series, leading to alabeling precaution for �5-D SE for the LADARVision anda voluntary truncation of data for �5-D sphere for the VISXsystems. Given the available data, LASIK for hyperopia of�4- to 5-D SE should be approached with caution.

As laser technology has progressed, there has been agradual increase in the diameters of the optical and ablationzones. The optical zone is usually defined as the zone within

Table 4. Brief Summary of Premarket Data Submitted by

. ofyes

OZ(mm)

AZ(mm)

PreoperativeSphere (D)

(Range)

PreoperativeCylinder (D)

(Range)

43 6.0 9.0 1.00–6.00 0.00 to �0.7524 1.00–6.00 0.00 to �6.0057 0.00–6.00 0.00 to �6.0069 0.50–6.00 0.00–6.0033 0.50–4.00 0.00–2.00

ters; OZ � optical zone; SE � spherical equivalent; UCVA � uncorrected

Table 3. Recent Publications

ow-upos)

No. ofEyes

OZ(mm)

AZ(mm)

SEChange

Achieved/Entered

Preoperative SE(D)

Range Mean

6 32 1.50–8.75 4.0037 5.0 9.0 0.13–2.75 1.5854 8.5–9.0 1.18 0.25–2.25 1.21

12 30 0.50–6.00 1.73

6 46 0.50–6.00 2.5029 5.0 9.0 1.70

3 36 5.0 9.0 1.07 0.63–2.63 1.5212 17 1.75–8.12 3.796 50 1.00–11.5

–12 69 5.8 1.00–7.12 3.40–42 15 5.5 7.5 1.00–5.25 3.08

ctacle-corrected visual acuity; D � diopters; H-LASIK � hyperopic LASIK;

sis using the Innovatome automatic microkeratome. Korean J Ophthalmolmileusis to treat overcorrected myopic LASIK. J Cataract Refract Surg

d astigmatic laser in situ keratomileusis in eyes with secondary hyperopia.

pic and astigmatic LASIK in eyes with primary and secondary hyperopia.for consecutive hyperopia after myopic overcorrection. J Cataract Refractratomileusis retreatments: indications, techniques, limitations, and results.current hyperopia following laser thermal keratoplasty. J Refract Surgeratomileusis for radial keratotomy induced hyperopia. Ophthalmologyrrect hyperopic shift after radial keratotomy. J Cataract Refract Surg

NoE

11

12

diop

Foll(m

31

st spe

mileukeratoic an

yperomentitu keor reitu kto co

P


the ring of deepest ablation. The ablation zone is usuallydefined as the entire ablated area, including both the opticalzone and the transition zone. There is a clear trend towardimproved predictability and visual outcome using a largeroptical zone and ablation zone (Table 2). In a comparativestudy using 5.0-, 5.5-, and 6.0-mm optical zone diameters,Davidorf et al32 reported that larger optical zones resulted insignificantly higher achieved hyperopic correction relativeto the laser setting (level II evidence). Davidorf et al alsofound a trend for better postoperative BSCVA with thelarger optical zones. Argento and Cosentino31 comparedhyperopic LASIK with a 5.9-mm optical zone and that witha 4.4- to 5.5-mm optical zone. They found that the largeroptical zone resulted in better predictability and postopera-tive BSCVA (level II evidence). They noted that in thesmaller optical zone group, 53% of eyes that lost 1 or 2 linesof BSCVA did not have intraoperative complications. Es-

Laser Manufacturers to the Food and Drug Administration

ostoperativeSE within1.0 D (%)

PostoperativeSE within0.5 D (%)

PostoperativeCylinder %Reduction

PostoperativeCylinder Index

of Success

88 6589 61 0.4988 65 0.1791 76 6787 60

visual acuity.

on Secondary LASIK

PreoperativeCylinder (D)

(Mean)

PostoperativeSE (D)

(Mean �SD)

PostoperativeCylinder (D)

(Mean)

PostoperativeSE within

1.0 D(%)

PostoperSE wit

0.5 D(%)

0.70 �0.26�1.74 1.10 53 340.70 �0.48�0.46 0.70 86 70

�0.38�0.50 96 690.60 �0.18�1.08 0.48 85

0.60 �0.70�1.19 63 470.53 �0.27�0.95 74 52

�0.10�0.52 94 561.14 �1.11�2.02 1.60

0.36�1.48 60 420.87 �0.32�1.20 0.76 801.20 �0.16�0.73 80

LTK � laser thermal keratoplasty; M-LASIK � myopic LASIK; OZ � opt

2000;14:7–11.2001;27:389–95.Ophthalmology 2000;107:1858–63, discussion 1863.

Trans Am Ophthalmol Soc 1999;97:241–55, discussion 255–60.Surg 2002;28:37–43.J Cataract Refract Surg 2001;27:1278–87.2000;16:163–9.2002;109:602–5.2001;27:273–6.

quenazi and Mendoza46 compared 5-, 6-, and 7-mm opticalzone diameters on the Chiron/Technolas (Claremont, CA)Keracor 117 and found that larger optical zones producedlarger and more predictable hyperopic corrections.

The aggregate clinical results suggest that small opticalzones may produce less predictable correction due to greaterand more variable regression. Smaller optical zones appearto yield lower quality of vision, possibly by induction ofaberration in the peripheral ablation area and an exaggeratedeffect from any decentration. Based on these levels II and IIIstudies, larger optical zones, preferably �5.5 mm, should beused when possible. If variable optical zone diameters areused, nomogram adjustment should be made to account forthe greater effects produced with larger optical zones.

Compared with hyperopic photorefractive keratectomy,hyperopic LASIK achieves quicker stabilization of refrac-tion. In a comparative study, el-Agha et al found that

operativeder withinD (%)

UCVA>20/40

(%)

UCVA>20/20

(%)

Loss ofBSCVA of

>2 lines (%)


93 49 3.5 660 91 37 5.8 3

93 46 1.9 397 48 3.8 395 61 2.8 6

UCVA>20/40

(%)

UCVA>20/20

(%)

Loss ofBSCVA of1 line (%)

Loss ofBSCVA

of >2 lines(%)


66 25 9.0 384 14 2.7 196 42 19 0.085 38 20§ 0.0 6

79 18§ 0.0 �683 16§ 0.0 �694 67 28 0.035 29 0.0 �1272 12 14 16.0 �696 55 22 6 1–6

0 13.3

one; PRK � photorefractive keratectomy; RK � radial keratectomy; SE �

PostCylin

0.5

ativehin

ical z

1611


refractive stability is achieved 1 month after LASIK but 6months after photorefractive keratectomy (level III evi-dence).47 Strictly speaking, stability should be assessed bystatistical analysis of the interval refractive change of indi-vidual cases.33 However, most studies only present thecohort mean SE over time. If we apply a simplistic test (notstatistically rigorous) that defines stability as no more than0.1 D of change in mean SE over an interval, then LASIKfor mild to moderate hyperopia seems to stabilize between1 and 6 months (Tables 2–4). Data from the FDA trials doprovide analysis of the percentage of eyes with an intervalchange of �1 D. In both the LADARVision and VISX FDAtrials, more than 95% of eyes passed this test of stability inthe 3- to 6-month postoperative interval. Therefore, hyper-opic LASIK can be generally considered stable after 3months. Laser in situ keratomileusis for high hyperopia maytake longer to stabilize.31,48 Laser in situ keratomileusis isalso associated with less postoperative discomfort andquicker visual recovery than photorefractive keratectomy.

Publications on secondary hyperopic LASIK after vari-ous procedures are summarized in Table 3. SecondaryLASIK after a first LASIK procedure seems to be safe,based on level III evidence. There are a tendency towardovercorrection in the treatment of consecutive hyperopiaafter primary myopic LASIK38,40,41,43 and a tendency to-ward undercorrection in the treatment of residual hyperopiaafter primary hyperopic LASIK.49 Nomogram adjustmentsare necessary in these circumstances. For example, whentreating consecutive hyperopia after a myopic LASIK pro-cedure, less than a full correction is needed. Treatment ofresidual hyperopia may require a longer time to stabilize.49

There are increased incidences of loss of �2 lines of BCVAin LASIK after radial keratotomy and laser thermal kerato-plasty. Incision opening, diffuse lamellar keratitis, and ep-ithelial ingrowth are possible complications of LASIK afterradial keratotomy.39 Decentration, irregular astigmatism,and haze are possible complications of LASIK after laserthermal keratoplasty.37

LASIK for Hyperopic Astigmatism

In limited published studies, the use of LASIK to correctprimary hyperopic astigmatism has been reported to be safeand effective. However, the effectiveness of LASIK tocorrect secondary hyperopic astigmatism remains unknown.A variety of excimer laser ablation profiles can be used tocorrect the spherical and astigmatic components of com-pound hyperopia. One of the first techniques used was aminus-cylinder format combining an annular peripheral ab-lation to correct the sphere and a centrally applied myopiccylinder to correct the astigmatism. However, Azar andPrimack36 demonstrated that this technique required thegreatest amount of tissue removal. Current laser ablationprofiles use the most tissue-sparing method in a plus-cylin-der format treatment by combining a hyperopic sphere witha hyperopic cylinder. Both the flat and steep meridiansundergo peripheral ablation, but the flat meridian is prefer-entially steepened more.

Most studies of primary and secondary hyperopicLASIK either did not treat astigmatism or combined the

1612

results of spherical hyperopia and astigmatic hyperopiatreatment cohorts in their analysis.32,40,41,48,50 In addition,few studies have performed a rigorous analysis of astigma-tism results using vector analysis. Therefore, it is difficult todetermine the true safety and effectiveness of the astigma-tism treatment.

The few studies that have analyzed astigmatism suggestthat the use of LASIK to correct low to moderate levels ofprimary hyperopia and astigmatism is safe and effective.Salz et al33 reported on 124 hyperopic astigmatic eyes thatunderwent LASIK using a 6.0-mm optical zone with a9.0-mm ablation zone using the LADARVision excimerlaser system (level II evidence). The preoperative sphereand cylinder were �3.65�1.45 D (range, �1.00–6.00) and�1.62�1.24 D (range, �0.50 to �6.00). At 12 monthspostoperatively, 73% and 89% of eyes were within 0.50 Dand 1.00 D of intended manifest refraction SE, respectively.Uncorrected VAs of 20/20 and 20/40 or better wereachieved in 53.1% and 93.8% of eyes, respectively, whereasno eye lost �2 lines of BCVA. These results were similar tothose of their cohort of 152 eyes that underwent hyperopicspherical treatment. Using vector analysis, an average of109% of the intended cylinder correction was achieved at 12months, indicating a slight overcorrection of the cylinder.There was an 8.5�13.7° average angle of error.

The results of treating lower levels of spherical correc-tion (�0.88–2.9D) were better than for treating higherlevels (�3.0–6.0 D). Fewer eyes achieved 20/20 uncor-rected VA (59.6% vs. 35.3% for lower and higher levels ofpreoperative sphere, respectively), and fewer were within0.50 D of intended manifest refraction SE (77.8% vs. 60.0%for higher and lower levels, respectively). Reviglio et al51

studied 50 eyes that underwent hyperopic LASIK, some ofwhich also had astigmatism treated (level III evidence).Using a 6.0-mm optical zone with an 8.5-mm ablation zone,the mean preoperative astigmatism was reduced from�1.19�0.72 D (range, 0.50–3.00) to �0.18�0.25 D(range, 0.00–0.75) at 6 months postoperatively. At 6months, 62% of eyes achieved 20/20 uncorrected VA, 62%were within 0.50 D of intended refraction, and no eye lostBSCVA. Rashad52 performed hyperopic LASIK on 85 eyeswith a preoperative manifest refraction SE of �3.31�0.69D (range, �1.25–5.00) and astigmatism of �0.91�1.06 D(range, 0.00 to �3.00). Although no separate analysis wasperformed on the astigmatic cohort, at 12 months postop-eratively the overall mean astigmatism was reduced to�0.36�0.30 D (range, 0.00 to �1.00) (level III evidence).Argento and Cosentino31 included astigmatism treatment intheir comparison of different optical zone sizes for hyper-opic LASIK (Table 2). The vector change in cylinder inrelation to the magnitude of the preoperative cylinderranged from 86% to 101% for the different analysis cate-gories, indicating that LASIK was effective for astigmatismtreatment (level II evidence).31 No eye lost more than 1 lineof BSCVA at 12 months postoperatively. Although thelarger optical zone improved the effectiveness of the SEresult, as noted in several other studies, it did not seem toimprove the effectiveness of cylinder correction.

Laser in situ keratomileusis has been performed to cor-rect secondary compound hyperopia after previous LASIK,


radial keratotomy, or laser thermal keratoplasty. Althoughthe spherical component can be effectively reduced, there isdifficulty correcting the cylinder component, which resultsin significant variability in outcome. In a study by Francesconiet al39 reporting on LASIK for radial keratotomy–inducedhyperopia in 69 eyes, there was no reduction in mean cylinder,despite an attempt to correct all of the astigmatism (level IIIevidence). The preoperative mean refractive cylinder was0.87�0.92 D (range, 0.00–4.50), and at the final follow-up thecylinder was 0.75�1.03 D (range, 0.00–6.00). This was sim-ilar to 12 cases of secondary compound hyperopia from pre-vious LASIK surgery reported by Mulhern et al,49 in which noreduction of the cylinder after retreatment was observed (levelIII evidence). This was in contrast to their secondary com-pound myopia treatments, in which the astigmatism was moreeffectively reduced from a preoperative mean of 1.87�0.98 D(range, 0.50–3.5) to 0.76�0.66 D (range, 0.00–2.5). Rojas etal43 reported better success at treating secondary compoundhyperopia in 19 eyes whose original surgery was myopicLASIK (level III evidence). Using vector analysis, the meantarget-induced astigmatism before retreatment was1.11�0.38 D, and the mean surgically induced astigmatismwas 1.11�0.45 D. There was still variability in the outcomeof cylinder correction because the index of success was0.44, which indicates 56% success in achieving the surgicalcorrection of astigmatism.

Esquenazi and Mendoza46 found that in eyes with base-line keratometry of �45 D, hyperopic correction was lesseffective and predictable. However, Cobo-Soriano et al45

did not find that baseline keratometry influenced the post-operative results. Higher levels of hyperopia have beenassociated with less predictable results.

LASIK for Mixed Astigmatism

Mixed astigmatism exists when one meridian is in focus infront of the retina and the other meridian is in focus behindthe retina (e.g., �2.00 �3.00 �180 or �1.00 �3.00 �90).To correct mixed astigmatism with LASIK, the cornea mustbe steepened in one meridian and flattened in the other.Levels II and III evidence has demonstrated very goodvisual results, and the risk of complications seems to besimilar to that of other LASIK procedures.

The laser can be programmed to perform a variety ofpotential ablation profiles to achieve mixed astigmatismcorrection. They include a combination of hyperopic sphere,myopic cylinder, hyperopic cylinder, and myopic spherecorrections.

Azar and Primack36 published a theoretical analysis of 4different laser ablation profiles to correct mixed astigma-tism, especially evaluating ablation depth. They concludedthat combinations of hyperopic cylinder and myopic spheretreatments and hyperopic cylinder and myopic cylinder treat-ments resulted in the lowest degrees of stromal ablation.

Argento et al53 used a hyperopic cylindrical ablationprofile to correct mixed astigmatism in 73 eyes with LASIKusing a Chiron/Technolas Keracor 116/117 excimer laser.With a preoperative SE of �0.15�1.59 D (range, –0.88 to4.25) and a mean preoperative cylinder of �3.45�2.15 D(range, �0.50–7.25), the 6-month postoperative mean SE

was �0.01�0.52 D, and the mean cylinder was �0.11�1.28D (level III evidence). Uncorrected vision of 20/40 or betterincreased from 45% to 92% of eyes at 6 months.

Chayet et al54 performed LASIK using an EC-5000(Nidek, Pasadena, CA) excimer laser on 41 eyes of 26patients with simple myopic astigmatism, mixed astigma-tism, and hyperopic astigmatism. For simple myopic andmixed astigmatism, ablations were performed in both thesteep and flat meridians, calculating a certain percentage(33%) hyperopic shift when treating in the steep meridian.Overall, 78% of eyes were within 0.5 D and 90% werewithin 1.0 D of intended SE correction at 3 months (level IIIevidence). Of mixed astigmatism eyes, 73% were within 1.0D of intended correction. In 1 eye, an incorrect axis (90°away) was programmed for the steep axis correction, result-ing in a poor refractive result.

Sheludchenko and Fadeykina55 performed LASIK usinga Nidek EC-5000 excimer laser on 46 eyes with mixedastigmatism. In 28 eyes they used a bitoric ablation, whichis a combined hyperopic and myopic astigmatism correc-tion, with additional spherical correction if necessary. In 18eyes they used a monotoric ablation, which combines ahyperopic cylinder with a hyperopic sphere. The 2 groupshad similar preoperative visual, SE, and astigmatism values.At 6 months, there was a trend toward less residual cylinderin the bitoric group (level III evidence). There was statisti-cally significantly better uncorrected vision in the bitoricgroup relative to the monotoric group. Additionally, 7 of 28(25%) eyes in the bitoric group and 8 of 18 (44%) eyes inthe monotoric group underwent an enhancement procedure.

More recently, Chayet et al56 reported results of LASIKusing a Nidek EC-5000 excimer laser on 47 eyes withmixed astigmatism. They used a bitoric ablation profile,combining hyperopic cylinder and myopic cylinder correc-tions. The mean preoperative sphere was �1.31�0.95 D,and the mean preoperative cylinder was –4.02�1.22 D. At3 months, before any enhancements, the mean sphere was�0.18�0.58 D, and the mean cylinder was –0.49�0.46 D(level III evidence). Approximately 13% required an en-hancement procedure. The authors noted that bitoric abla-tions conserve more tissue than myopic cylindrical ablationcombined with hyperopic spherical ablations (the mostcommon method used before the wide availability of mixedastigmatism treatments), allowing safer treatments and po-tentially larger ablation zones and decreasing patients’ com-plaints of nighttime symptoms. Of note, 2 of the eyes in thisstudy also had the axis of astigmatism misaligned by 90°due to incorrect data input into the laser computer.

In 2002, Salz et al33 reported on 65 eyes that had under-gone LASIK for mixed astigmatism with the Alcon LA-DARVision excimer laser (Table 2). An optical zone of 6mm and a total ablation zone of 9 mm were used. Six-monthfollow-up data were available on 57 eyes (88%), and 1-yeardata were available on 38 eyes (58%). Uncorrected visionwas 20/20 or better in 45% of eyes at 6 months and 52% ofeyes at 1 year. Uncorrected VA was 20/40 or better in 93%of eyes at 6 months and 94% of eyes at 1 year (level IIevidence). Stability of refraction was excellent between 1and 12 months. One eye lost 1 line of BSCVA at 6 months,and no eyes lost �2 lines of BSCVA at 1 year. At 6 months,

1613


7.5% of patients reported significant worsening of nightdriving ability, whereas 6.1% reported these symptoms at 1year; 6.1% reported significantly worse halos at 1 year.Three eyes were excluded from this study because of an“incorrect surgical procedure or incorrect data entry ofrefractive information into the laser by the surgeon.”

Complications

Complications can occur after hyperopic LASIK, as theycan after myopic LASIK. Both procedures have severalcomplications in common; however, some are unique tohyperopic treatments. It is difficult to know the exact inci-dence of complications because definitions vary in differentreports. For the purposes of this discussion, any outcomenot considered part of a routine operative or postoperativecourse will be considered a complication.

Primary hyperopic LASIK was initially performed withearly-model microkeratomes developed for myopic LASIK.The Automated Corneal Shaper (Chiron Vision, Irvine, CA)typically created small-diameter flaps of approximately 8.5mm. Due to the limited stromal bed exposure of smallerflaps, peripheral laser pulses often were applied to intactepithelium outside of the keratectomy bed. Such cases wereassociated with higher rates of epithelial ingrowth comparedwith cases in which larger diameter flaps were created withother microkeratomes.49,57 It is hypothesized that ablationof the peripheral epithelium stimulated mitotic activity,which increased the risk of growth under the flap in thepostoperative period. It is advised to use larger diameterflaps and to decenter the flap toward the hinge to providemore stromal clearance.46 If laser pulses are being deliveredoutside the flap area, it is important to mask the peripheralepithelium.

Flap complications, such as free caps, can occur inLASIK procedures. The incidence of free caps, or button-holes, may be higher in hyperopic LASIK than in myopicLASIK because larger flaps are attempted to accommodatelarger ablation diameters. Irregular46 and incomplete31 flapcuts have also been reported. Microstriae and folds in theflap may occur.51 Epithelial defects and diffuse lamellarkeratitis have been reported as well.41 Patients may experi-ence dry eye, halos, glare, irregular astigmatism, and de-creased night vision after hyperopic LASIK52 as well asdecentered ablations, which may be amenable to recenteringtreatments.49

The common denominator for any visually significantcomplication is loss of BSCVA. Small optical zones (4.4–5.5 mm) are associated with greater loss of BSCVA com-pared with large optical zones (5.9 mm).31,32 The highestincidence of loss of BSCVA (10%) occurred with use of5.0-mm optical zones.47 Hyperopia of �5 D was associatedwith greater loss of BSCVA.38 Use of large optical zonesseems to minimize loss of BSCVA and allows for safertreatments of hyperopia of �5 D.50,51

Residual hyperopia after primary hyperopic LASIK canbe treated with the laser either by recutting a flap andapplying the laser (repeat LASIK) or by lifting the primary

1614

flap and applying the laser (flap lift). Recutting a flap entailsthe risk that the second keratectomy plane will intersect theprimary keratectomy plane, which may lead to the creationof free stromal pieces or irregular attached stromal sections.Therefore, it is best to avoid recutting a flap if possible.58

Even with flap-lift retreatments, however, flap complica-tions such as diffuse lamellar keratitis, epithelial defects,epithelial ingrowth, peripheral scarring at flap edge, Bow-man’s folds, keratectasia, and interface haze can oc-cur.29,38,43,49 Hyperopic flap-lift retreatment for undercor-rected primary hyperopic LASIK seems safe, with noreported loss of BSCVA or flap complications reported inone study.48 Overcorrected hyperopic LASIK leads to post-operative myopia. Myopic flap-lift retreatments are gener-ally safe, with no loss of �2 lines of BSCVA reported.Hyperopic LASIK can be used to correct consecutive hy-peropia resulting from primary myopic LASIK procedures.The procedure seems to be safe, because a few studiesreported that no eyes lost �2 lines of BSCVA,29,43,49 andanother study reported a 3% incidence of a 2-line loss ofBSCVA.38

Consecutive hyperopia after radial keratotomy has beentreated with hyperopic LASIK. A concern is that creatingand lifting a flap may increase the risk of dehiscence ofradial incisions within the flap. Researchers in one seriesreported incision separation during flap lifting in 8 of 69eyes (11.6%), but there were no postoperative complica-tions or losses of BSCVA in those patients.39 In the sameseries, however, 4 of 69 eyes (6%) lost 2 Snellen VA linesof BSCVA due to diffuse lamellar keratitis and epithelialingrowth.39 In another study, no intraoperative or postoper-ative complications were reported.42 Primary hyperopicLASIK has also been used for consecutive hyperopia aftermyopic photorefractive keratectomy and automated lamel-lar keratoplasty without loss of �2 lines of BSCVA.40

Hyperopic LASIK after undercorrected laser thermokerato-plasty has been associated with 16% loss of �2 lines ofBSCVA.37 Other complications reported in this series aredecentrations and ring-shaped haze when the edge of theflap coincided with the thermal keratoplasty spots.

Since the publication of the Ophthalmic TechnologyAssessment on LASIK for myopia,4 2 complications de-serve emphasis. Severe corneal infections may occur afterhyperopic LASIK when a contact lens is used to mask aphototherapeutic ablation of the stromal bed.59 In Chandraet al’s report, 7 eyes developed Mycobacterium chelonaekeratitis. Topical azithromycin drops were added to theregimen in 3 eyes, and upon resolution all eyes had stromalscars with superficial vascularization, and many patientsexperienced significant loss of BSCVA.

Steroid-induced glaucoma may be misdiagnosed afterLASIK.60,61 In patients who experience increased IOP fromsteroids after LASIK, the pressure gradient leads to transu-dation of aqueous across the endothelium. Fluid accumu-lates in the interface under the flap, which often leads to anoptically clear space below the flap. Measuring IOP on theflap leads to falsely low measurements because the readingreflects the pressure of the clear space, not the IOP.62


Conclusions

This Ophthalmic Technology Assessment reviewed the lit-erature to evaluate the safety and efficacy of LASIK forhyperopia, hyperopia with astigmatism, and mixed astigma-tism. Nonrandomized interventional comparative trials(level II) and noncomparative case series (level III) haveshown that LASIK is effective and predictable in achievingvery good uncorrected VA results. However, as with myo-pic LASIK, the results are superior for low amounts ofhyperopia (�3 D) when compared with higher amounts ofhyperopia (�4 to 5 D). In addition, the possibility of loss ofBSCVA is greater when treating high levels of hyperopia.Although outcome data on the treatment of hyperopic astig-matism were not as plentiful, the findings seemed to mirrorthose for spherical hyperopia.

Laser in situ keratomileusis for the treatment of sphericalhyperopia after previous refractive surgery, either radialkeratotomy or myopic LASIK, has also demonstrated effi-cacy. The correction of hyperopic astigmatism is less effec-tive when treating astigmatism induced by radial keratot-omy. There is a higher incidence of loss of BSCVA whentreating hyperopia after radial keratotomy and laser thermalkeratoplasty.

When correcting mixed astigmatism, several ablationprofiles have been used. Treating the hyperopic cylindercombined with myopic sphere or cylinder treatments results

Preparation was coordinated by the Ophthalmic Tec

Ophthalmic Technology Assessment Alan Sugar,Committee Refractive Surgery Panel Brian S. Box

David HuanChristopherSteven SchaGary A. Var

Edited by: Susan GarraManaging Editors: Nancy Colli

Flora Lum, MApproved by: Board of Tru*Proprietary interests stated.

Category Abbreviation Speci

Product P FinanPc Such

Investor I Finanor

Ic SuchConsultant C_ Com

theCc_ Such

equExam

C1 or Cc1 1. ReC2 or Cc2 2. CoC3 or Cc3 3. AdC4 or Cc4 4. SuC5 or Cc5 5. CoC6 or Cc6 6. CoC7 or Cc7 7. ReC8 or Cc8 8. Re

None N No fisus

in the lowest ablation depth. Despite the variety of ablationprofiles used to treat mixed astigmatism, very good visualresults have been reported.

Although complications after LASIK for hyperopia arerare, they can occur. Prevention of many of these compli-cations starts with assessing candidacy and excluding pa-tients who are not good candidates. Because the ablationdiameter is greater in hyperopic treatments, more attentionneeds to be paid to many microkeratome issues. Reportedcomplications seem to be rare, and hyperopic patients typ-ically are very satisfied refractive patients.

References

1. Pallikaris IG, Papatzanaki ME, Siganos DS, Tsilimbaris MK.A corneal flap technique for laser in situ keratomileusis.Human studies. Arch Ophthalmol 1991;109:1699–702.

2. Pallikaris IG, Papatzanaki ME, Stathi EZ, et al. Laser in situkeratomileusis. Lasers Surg Med 1990;10:463–8.

3. American Academy of Ophthalmology. Excimer laser pho-torefractive keratectomy (PRK) for myopia and astigmatism.Ophthalmology 1999;106:422–37.

4. Sugar A, Rapuano CJ, Culbertson WW, et al. Laser in situkeratomileusis for myopia and astigmatism: safety and effi-cacy. Ophthalmology 2002;109:175–87.

5. American Academy of Ophthalmology Refractive ErrorsPanel. Preferred practice pattern: refractive errors. San Fran-

gy Assessment Committee Refractive Surgery Panel

Proprietary Interests*MS, Chair, Methodologist Cc2, Cc7achler, MD C1, PhD N

puano, MD C3, C7, MD ND N

NN, MPH N

N, November 15, 2003

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nterest in equipment, process, or product presented.est in potentially competing equipment, process, or product.nterest in a company or companies supplying the equipment, process,ct presented.est in a potentially competing company.tion received within the past 3 years for consulting services regardingpment, process, or product presented.ensation received for consulting services regarding potentially competingnt, process, or product.f compensation received include:

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