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138 Journal of Refractive Surgery Volume 17 March/April 2001

ABSTRACTPURPOSE: Pene t ra t ing ke ra top las ty and ep ike r-

a top las ty have been u t i l i zed in the su rg ica l t r ea t -ment o f ke ra toconus . Compar i son o f the re l a t ivee ffi cacy o f each p rocedure in ach iev ing v i sua l ou t -comes has no t been ach ieved due to l imi ted num-bers o f cases and fo l low-up in p rev ious se r i e s .

METHODS: All pat ients who underwent e i therpene t ra t ing ke ra top las ty o r ep ike ra top las ty fo r

ke ra toconus be tween January 1987 and December1997 , and fo r whom a t l eas t 24 month s o f pos toper-a t ive fo l low-up da ta fo r v i sua l acu i ty was docu-mented in th e medica l r ecord , were inc luded in th i sre t rospec t ive , nonrandom ized , sequen t i a l compar-at ive t r ia l . The sole cr i ter ia for outcome in eachgroup , a s we l l a s fo r compar i son o f the two g roups ,was Sne l l en v i sua l acu i ty measured a t the t ime o f each fo l low-up w i th the p resen t ing op t i ca l a id .

R E S U LT S : I n c l u s i o n c r i t e r i a w e r e m e t f o r443 eyes t r ea ted w i th pene t ra t ing ke ra top las ty and161 eyes t reated with epikeratoplasty. Mean fol low-up w as 4 .3 yea r s fo r pene t ra t ing ke ra top las ty and4 . 5 y e a r s f o r e p i k e r a t o p l a s t y. I n e a c h g r o u p ,approxim ately 50% of the pat ien ts chos e rehabi l i ta-

t ion wi th op t i ca l co r rec t ion wi th e i the r spec tac lesor contact len ses an d 50% chos e no opt ical correc-t ion. Final median logMAR visual acui ty for a l lpa t i en t s , i rr e spec t ive o f mea ns o f v i sua l r ehab i l i ta -t ion, was 0.30 (20/40) for penetrat ing keratoplastyand 0.40 (20/50) for epikeratop lasty ( P < .00005). In209 pene t ra t ing ke ra top las ty and 77 ep ike ra to -p l a s t y e y e s w i t h o p t i c a l c o r r e c t i o n , t h e f i n a lmedian logMAR visual acui ty was 0.18 (20/30) forpenetrat ing keratoplasty and 0.40 (20/50) for epi-ke ra top las ty ( P < .00005) . The f ina l me dian logMAR

visua l acu i ty in 234 pene t ra t ing ke ra top las ty and84 ep ike ra top las ty eyes w i thou t op t i ca l co r rec t ionwas 0.48 (20/60) in both groups ( P -va lue was no ts ta t is t ical ly s ignif icant) .

CONCLUSIONS: Although penetrat ing kerato-p las ty wa s s t a t i s t i ca l ly sup er io r to ep ike ra top las tywi th respec t to v i sua l ou tcome, r e su l ts wi th e p ike r-a top las ty were adequa te to r ecomme nd i t s use as as u r g i c a l a l t e r n a t i v e i n c a s e s w h e n i t i s n o t

d e s i r a b l e t o p e r f o r m p e n e t r a t i n g k e r a t o p l a s t y.[ J R ef r a ct S u r g 2001;17:138-146]

Keratoconus is a bilateral, non-inflammatorycentral corneal thinning disorder character-ized by the development of a corresponding

protrusion (cone) with an apex often located in aninferior eccent ric position. 1 The treat ment of kerato-conus depends upon the severity of the disease andincludes t he following options: specta cles, rigid gas -permeable corneal or scleral contact lens, andsur gical t hera py. 2

Lamellar keratoplasty was once the surgical

treatment of choice for keratoconus.3

Techn ical d iffi-culties with lamellar keratoplasty, as well as sub-optimal visual outcomes due to interface opacifica-tion and irregular astigmatism, led to virtual aban-donment of this t hera peutic option. 4

Penetrating keratoplasty, which is technicallyeasier to perform than lamellar keratoplasty, has abetter visual prognosis and has been the surgicaltr eatm ent of choice for contact lens-intoleran t kera -toconus. 5-10 The visual outcomes of penetr at ing ker-at oplast y for kera toconus h ave been excellent, withuniformly low complication rates in all reportedseries. 5-10 Stil l , there are concerns about

immunologically-mediated graft rejection andfailure 5-9,11-13 , microbial kera titis 14-16 , and t raumat icwound dehiscence with loss of intraocularcontents. 17

Epikeratoplasty is a form of onlay lamellar ker-atoplasty in which a lens made of human cornealtissue is sutured onto the anterior surface of thecornea to change i t s anter ior curvature andrefractive properties. 18 This procedure combines

Penetrating Keratoplasty vs. Epikeratoplasty forthe Surgical Treatment of Keratoconus

Michael D. Wagoner, MD; Scott D. Smith, MD, MPH; Wilfried J. Rademaker, MD, MPH;Muneera A. Mahmood, MD

From the Anterior Segment/External Disease Division, Department of Ophthalmology and the Department of Research, King Khaled Eye

Specialist Hospital, Riyadh, Kingdom of Saudi Arabia (Rademaker, Mahmood, Smith, Wagoner), the Department of Ophthalmology and VisualSciences, University of Iowa Hospitals and Clinics, Iowa City, Iowa,(Wagoner), and the Division of Ophthalmology, Department of Surgery,Cleveland Clinic, Cleveland, Ohio (Smith).

The authors have no proprietary interest in the materials mentioned herein.

Correspondence: Michael D. Wagoner, MD, Department of Ophthalmology and Visual Sciences, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, Iowa, 52242-1091.

Received: June 20, 2000 Accepted: December 12, 2000

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some of the advantages of lamellar keratoplasty(extraocular procedure, preservation of hostendothelium, reduced or eliminated risk of graftrejection, normal postoperative activity, and elimi-na tion of risk of tr au ma tic dehiscence of the globe) 3,4

an d pen etra ting ker at oplast y (less inter face opacifi-cation and irregular astigmatism than with lamel-lar keratoplasty). 4-6 Although a number of authorshave described short 19,20 and long-term 21,22 successwith epikeratoplasty for keratoconus, and a fewnonrandomized studies have compared epikerato-plasty with penetrating keratoplasty for kerato-conus 23-26 , these studies have an inadequate num berof cases and/or insufficient long-term follow-up toallow definitive conclusions regarding the potentialrole of epikeratoplasty in the surgical managementof keratoconus.

This study an alyzes the r esults of a large nu mberof penetrating keratoplasty and epikeratoplastyprocedures performed at a single institution by arelatively small group of sur geons for pa tients withkeratoconus in whom long-term follow-up wasavailable.

PATIENTS AND METHODSAll patients who underwent either penetrating

keratoplasty or epikeratoplasty for keratoconus bymembers of the Anterior Segment Division at theKing Khaled Eye Specialist Hospital (KKESH)between 1 January 1987 and 31 December 1997,and for whom at least 24 months of postoperative

visual acuity follow-up dat a were docum ented in t hemedical record, were included in this retrospective,nonrandomized, sequential comparative trial. Nopatients who met these minimal inclusion criteriawere excluded from the study.

Study DesignThis study was a retrospective, nonrandomized,

sequential compara tive trial . Eyes that underwent aprimary penetrating keratoplasty procedure andmet the inclusion criteria were categorized in thepenetrating keratoplasty group (443 eyes). Eyesthat underwent a primary epikeratoplasty proce-

dur e an d met th e inclusion criteria wer e cat egorizedin t he epikera toplasty group (161 eyes).

The study tracked the visual outcome based onth e original decision to first perform either a pene-t ra t ing kera toplas ty or an epikera toplas ty.Subsequent procedures and interventions, if any,did not affect the group assignment. Seven pene-tra ting keratoplasty patients who un derwent repeatpenetrating keratoplasty remained in the penetrat -

ing keratoplasty group. Two epikeratoplastypatients who underwent repeat epikeratoplasty andtwo epikeratoplasty patients who underwent sec-ondary penetrating keratoplasty remained in theepikeratoplasty group. Because these cases repre-sented a sma ll minority of cases r elative to the sizeof the study group, the decision to include them inthe final analysis did not have any impact on thefinal median S nellen visua l acuity at an y time pointin either group.

The criteria for outcome of each group, as well asfor compar ison of th e two groups, wa s solely Snellenvisua l acuity as m easur ed at the time of each follow-up examination by E-optotype orientation underdim examination room conditions with the present-ing optical aid (without correction, with spectacles,or with cont act lens) being utilized by th e pat ient forvisual rehabilitation. The endpoint for observationwas th e most recent patient examination.

Selection of ProcedureThe choice of surgical intervention (penetrating

keratoplasty or epikeratoplasty) was at the discre-tion of individual surgeons. Some surgeons selectedepikeratoplasty in cases of mild to moderat e apicalcorneal scars if they felt th at these scars would notsignificantly affect the final visual outcome (ie,visual acuity of >20/40 expected); other surgeonsselected only penetrating keratoplasty in eyes withapical corneal scars. If dense apical corneal scarswere present, and the surgeon felt they would

adversely affect the visual prognosis (ie, visualacuity of

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Postoperatively, all patients were treated asinpatients with topical antibiotics until re-epithe-lialization was complete. Depending on surgeonpreference, pressure patching, bandage contactlens, or no occlusive therapy was used to facilitatere-epithelialization. Following discharge thepat ients were followed as outp atient s at 2 weeks, 1,3, 6, 12 months, and twice yearly thereafter. Topicalcorticosteroids were used four to six times dailyimmediately postoperatively and tapered graduallyover a 1-year period. Loose sutures were removedwhen identified. Approximately 20% of eyes had allsutu res removed by 12 months, 55% ha d all sutur esremoved by 24 months, and 85% had all suturesremoved by 36 month s.

Surgical Technique for EpikeratoplastyEpikeratoplasty lenticules of between 6.5 to

9.5 mm diamet er (median, 8.5 mm) and plan o powerwere obtained from two different sources(lyophilized KERATOLENS from Allergan MedicalOpt ics , I rvine , CA from Sep tember 1986 toSeptember 1993; fresh BIO-LENS, from Cryo-OpticInc., Houston, TX from February 1993 to December1997). Epikera toplasty lenticules were prepa red forsurgical use by previously described methods. 18 Allcases were performed by experienced surgeons of the Anterior Segment Division of KKESH using apreviously described technique. 19

Postoperatively, all patients were t reat ed as inpa -tients with topical antibiotics and corticosteroids,

and a bandage contact lens, pressure patching, ortemporary tarsorrhaphy until re-epithelializationwas complete. Following re-epithelialization, theywere discharged and followed as outpatients at2 weeks, 1, 3, 6, 12 month s, and twice yearly there-after. Topical corticosteroids (eg, prednisoloneacetate 1% three times a day or a weaker corticos-teroid) were used postoperat ively to prevent pr ema-tur e sutu re vascularization an d loosening, and weretap ered gra dua lly over 3 to 6 mont hs. Topical a ntibi-

otics were used postoperatively four times a dayuntil re-epithelialization was complete and weretapered over 3 to 6 months. Suture removal wasdelayed until 3 to 6 months, with the exception of removal of sutures that loosened or vascularizedprematurely.

Outcome MeasuresData collected from medical records included

demographic data (age, sex); date of examinationclosest t o the point in time pr ior t o the su rgical pro-cedur e (preoperat ive examina tion); date of th e finaldocumented postoperative examination; preopera-tive visual acuity (with presenting type of correc-tion, where available), presence or absence of apicalcornea l scar s; postoperative visual acuity at 2 years(6 mo), each year (6 mo) thereafter, and the finalrecorded examination; the means by which therecorded visual a cuity was achieved at each exami-nation (with spectacles, contact lens, or no correc-tion); early and late postoperative complicationsresulting in graft or lenticule failure; and subse-quent surgical in tervent ion wi th f inal v isualoutcome.

Statistical AnalysisData were an alyzed using STATA 6.0 (College

Station, TX) statistical software. Visual acuityresults at each follow-up time point were convertedto logMAR scale and treated as continuous vari-ables. Comparison of the distribution of postopera-

tive visua l acuity by procedure t ype was done u singthe Mann-Whitney test. Analysis of results, otherth an visual acuity, was perform ed using th e Fisher sexact or chi-square test for categorical variables,an d two-sam ple t -test for continuous variables.

RESULTSA total of 604 patients qua lified for the stud y;

443 in the penetrating keratoplasty group and 161in t he epiker at oplasty (Table 1). Ninety-four (21.2%)


Penetrating Keratoplasty vs. Epikeratoplasty for Keratoconus/Wagoner et al

Table 1Comparison of Penetrating Keratoplasty and Epikeratoplasty Patient Groups

Penetrating Keratoplasty Epikeratoplasty P -valueTotal patients 443 161

Male (%) 274 (61.9) 99 (61.5) N.S*Female (%) 169 (38.1) 62 (38.5) N.S.

Apical scar (%) 439 (99.1) 84 (52.2) .001Vernal keratoconjunctivitis (%) 94 (21.2) 25 (15.5) N.S.Median age (yr) at surgery (%) 21.5 (8.6) 20.3 (5.8) N.S.Median follow-up in years (%) 4.3 (2.0) 4.5 (2.1) N.S.

*Not statistically significant

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patients in th e penetrating keratoplasty group a nd25 (15.5%) patients in the epikeratoplasty groupha d concomita nt vernal kera toconjun ctivitis. Apical

scars were pr esent in 439 (99.1%) eyes in t he pen e-trating keratoplasty group and 84 (52.2%) eyes inthe epikeratoplasty group ( P < .001). No patients ineither group h ad a ny other significan t ocular abnor-malities including glaucoma, cataract, or retinalpathology. There was no statistically significant dif-ference in the gender of th e patient s, median lengthof follow-up, or media n a ge at th e tim e of sur gery.

At least one dat a point wa s ava ilable for a ll eyesat or beyond the 2-year follow-up criteria. Visualacuity was not available within the 3-month timeinterval a round t he 2-year t ime point for 24 epiker-atoplasty eyes and 33 penetrating keratoplasty

eyes, but subsequent documentation of visual out-come was available. Mean follow-up was 4.3 yearsfor th e penetra ting kerat oplast y group and 4.5 yearsfor t he epikerat oplast y group.

The method of optical management selected byth e patient for each group dur ing the stu dy period issum mar ized in Table 2. During t he first 3 postoper-ative years, patients in the epikeratoplasty groupwere significantly more likely to choose optical cor-

rection (either spectacles or contact lenses) thanthose in the penetra t ing kera toplas ty group(P = .019). At 4 postoperat ive years an d at the fina l

follow-up exam ina tion, th e preferr ed mode of opticalcorrection was almost identical in both groups;approximately half of each group selected opticalcorrection and half preferred no optical correction.

The cumu lative visua l acuity for each group, irre-spective of the chosen method of rehabilitation (nocorrection, spectacles, or contact lenses), is summa-rized in Table 3. The median logMAR visual acuityat the final examination was 0.30 (20/40) for pene-tra ting ker atoplasty a nd 0.40 (20/50) for epikerat o-plasty ( P < .00005). There was no statisticallysignificant difference in visual outcome between thetwo groups a t 2 year s. Beginning at 3 years postop-

erat ively, an d cont inuing t o the fina l postoperat iveexamination, the visual outcome was significantlybetter with penetrating keratoplasty than epiker-atoplasty. The difference in statistical significancebetween penetrating keratoplasty and epikerato-plasty was progressively greater at each time point(3-year, 4-year, and final examination). There wasno statistically significant difference in the finalvisual resul ts wi th epikera toplas ty u t i l iz ing

Journal of Refractive Surgery Volume 17 March/April 2001 141


Table 2Penetrating Keratoplasty vs. Epikeratoplasty: Postoperative Method

of Optical ManagementPenetrating Keratoplasty Epikeratoplasty

Time N None Spectacles Contact Lens N None Spectacles Contact LensPatients (%) (%) (%) Patients (%) (%) (%)

Preoperative 443 383 (86) 35 (8) 25 (6) 161 88 (55) 29 (18) 44 (27)2 years 410 305 (74) 91 (22) 14 (3 137 71 (52) 54 (39) 12 (9)3 years 297 185 (62) 85 (29) 27 (9) 109 52 (48) 47 (43) 10 (9)4 years 215 117 (54) 76 (35) 22 (10) 79 41 (52) 29 (37) 9 (11)Final examination 443 234 (53) 160 (36) 49 (11) 161 84 (52) 66 (41) 11 (7)

Table 3Penetrating Keratoplasty vs. Epikeratoplasty: Visual Acuity (Percentile)*

Irrespective of Method of Optical ManagementPenetrating Keratoplasty Epikeratoplasty

Time N 10th 25th 50th 75th 90th N 10th 25th 50th 75th 90th P -valuePatients Patients

Pre-op 443 20/800 20/800 20/800 20/200 20/100 161 20/2000 20/400 20/125 20/60 20/40

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lyophilized vs. fresh tissue or when performed ineyes with or without apical corneal scars ( P = .4).

The visual acuity for patients in each group whochose rehabilitation with optical aids (spectacles orcontact lens) is su mma rized in Table 4. Among th issubset of 209 penetrating keratoplasty and 77 epi-kera toplasty eyes, the median logMAR visual acuityat the final follow-up examination was 0.18 (20/30)for penetrating keratoplasty and 0.40 (20/50) forepikeratoplasty ( P

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decision to proceed with surgical intervention is notalways straightforward because the same factorsth at compromise access to pr eoperat ive cont act lenstherapy also compromise access to postoperativesur gical car e.

Even a mong those patient s with a ccess to contactlens facilities, many Saudi Arabian patients areunwilling to attempt contact lens therapy. Those

th at do find th eir comfort an d wearing t ime are com-promised by the dry and dusty environment. Manypatients who att empt conta ct lens t herapy aban donit relatively early.

The lack of acceptance and/or availability of hardconta ct lenses as a major form of visual reha bilita-tion for keratoconus in Saudi Arabia creates adilemma of how best to deal with the patient withkeratoconus, especially if the cornea is clear or hasvisually insignificant apical scarring. The problemis compounded by the fact that many of thesepatients are still in secondary school and are hand-icapped by poor functional visual acuity. It has been

unclear whether it is better to offer these patientsepikeratoplasty with its relative safety but pre-sumptive slightly less visual potential, or penetrat-ing keratoplasty with its greater risks but potentialfor better visual acuity.

Although no randomized prospective study wasever designed at KKESH to systematically addressthis issue, decisions were made on a case-by-casebasis over th e 11-year p eriod described in th is stu dy,

providing the opportunity to make a retrospectivecomparison of a large number of patients undergo-ing either penetrating keratoplasty or epikerato-plasty with the availability of long-term follow-up.

Visual Results: Penetrating Keratoplasty

The literature on penetrating keratoplasty forkeratoconus supports a high rate of graft claritywith stable visual acuity and little tendency forrecurrent disease during the first postoperativedecade. 5-10 Two recent studies demonstrated thatgood results similar to those achieved in Westerncenters could be achieved with penetrating kerato-plasty in Sau di Ara bia, despite concerns a bout com-pliance, promp t a vailability of follow-up care, a nd asubsta ntial percenta ge of pat ients with concomita ntvernal kera toconjun ctivitis. 10,28

The only parameter studied in detail in the pre-sent stud y was final visual out come, which reflects

the cumulative impact of all adverse events thatoccurred from the primary procedure to the mostrecent patient follow-up examination. Among theentire keratoconus group, a final median visualacuity of 20/40 was achieved despite the fact thatslightly less than half the eyes were rehabilitatedwith spectacles or contact lenses. Among patientselecting to use spectacle or contact lenses, themedian visual acuity of 20/30, with 25% of patients



Table 6Penetrating Keratoplasty: Course of

Eyes With Graft FailureCase Etiology Intervention Final Best

Spectacle-correctedVisualAcuity

1. Immune rejection None Count fingers2. Immune rejection None Count fingers3. Immune rejection None Count fingers4. Primary graft failure Repeat PKP* 20/305. Traumatic dehiscence

with endothelialfailure Repeat PKP 20/25

6. Sterile ulcerationat graft-host

junction Repeat PKP 20/1607. Microbial kerati tis Repeat PKP 20/258. Microbial kerati tis Repeat PKP 20/509. Microbial kerati tis Repeat PKP 20/6010. Microbial keratitis Repeat PKP 20/80

*Penetrating keratoplasty

Table 7Epikeratoplasty: Course of Eyes With

Lenticule FailureCase Etiology Intervention Final Best

Spectacle-correctedVisualAcuity

1. Persistent epithelial Remove lenticule; Countdefect* not repeated fingers

2. Persistent epithelial Remove lenticule; Countdefect* not repeated fingers

3. Persistent epithelial Remove lenticule; 20/40defect* not repeated

4. Persistent epithelial Remove lenticule; 20/80defect* repeat EKP

5. Sterile Mooren-like Remove lenticule; 20/125ulcer not repeated

6. Microbial keratitis Remove lenticule; 20/60repeat EKP

7. High cylinder Secondary PKP** 20/30

8. High cylinder Secondary PKP 20/300

*Primary lenticule failure due to initial failure to re-epithelialize After successful contact lens fit Epikeratoplasty **Penetrating keratoplasty

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20/25 or better, was comparable to published serieswhere best spectacle-corrected or contact lens-corrected visual acuity was the major criteria forsurgical success. 5 Although a median visual acuityof 20/60 was achieved in patients who chose no cor-rection, there was some selection bias towardpatients who were satisfied with their visual out-comes and did not r equire furth er corr ection, as wellas t he sma ll number of patients with major compli-cat ions an d a visual outcome that was not am enableto optical correction.

Visual Results: EpikeratoplastyThe literature on visual outcomes following epi-

keratoplasty for keratoconus is less complete thanthat for penetrating keratoplasty, with most serieslimited by either small numbers 20,21 or limitedfollow-up. 19 The Nationwide Study for Epikerato-plasty, the largest published series to date with177 cases performed by 69 surgeons, has onlyfollow-up after su tur e removal of more th an 30 daysfor 82 eyes. 19 In a series with median follow-up of 21 months 20 and 67 months 21 , there were only40 cases an d 11 cases report ed, respectively. 20,21 Th ecur rent series includes 161 cases performed at a sin-gle center in which a minimum of 24 months and amedia n of 52 month s of follow-up wa s ava ilable.

Overall, previous visual outcomes have beenreported t o be sat isfactory with epikeratoplasty. 19-21

The percentage of eyes with a best spectacle-corrected visual acuity of 20/40 or better ranged

from 78% to 92%.19-21

The median best spectacle-corrected visual acuity ranged from 20/25 to20/30. 20,21 A consistent featu re of th ese studies wasthe infrequency with which a best spectacle-corr ected acuit y of 20/20 was a chieved. 19-21

It is difficult to compare t he r esults in t he pr esentseries to previous studies. Patients with someamount of apical scarring (52% of cases) wereincluded in the present series, whereas this was acontraindication to epikeratoplasty in the previousstudies. Although there was no significant differ-ence between visual outcome in eyes with or with outapical scarring ( P = .4), the inclusion of cases with

mild apical scarring undoubtedly contributed tosome decrease in t he median visual acuity comparedto previous series 19-22 , as well as furth er redu ction inthe percentage of eyes that achieved a final visualacuity of 20/20 or bet ter. 19-22

Irrespective of the limitations in comparing theresults in this study of epikeratoplasty for kerato-conus with those previously published, the current

series is sufficiently large with enough patients ineach category of visual rehabilitation to draw rea-sonable conclusions rega rdin g th e efficacy of epiker-atoplasty in achieving satisfactory visual outcomes.Among a ll 161 eyes, the fina l median visual acuitywas 20/50, despite the fact that slightly less thanhalf the eyes were rehabilitated with spectacles orcontact lenses. Among patients electing to usespectacles or contact lenses, the median visualacuity was a lso 20/50, and in pat ients who chose nocorr ection, it was 20/60.

Visual Results: Penetrating Keratoplasty vs.Epikeratoplasty

Comparative studies of visual outcome of pene-trating keratoplasty vs. epikeratoplasty are rela-tively limited. 23-26 As with visual acuity outcomes of epikeratoplasty, these studies have unsatisfactorypat ient nu mbers, follow-up period, or both, t o drawfirm conclusions.

Fronterre reported 30 eyes that received eitherpenetrating keratoplasty or epikeratoplasty duringthe same t ime in terval and in which 36 to72 mont hs of follow-up wa s ava ilable. 24 The patientswere matched for age, sex, refractive astigmatism,mean keratometric power, and spherical refractiveerror. Only those penetrating keratoplasty patientswho would have met criteria for inclusion in theepikeratoplasty study were included. Patients inboth groups had a similar mean uncorrected visualacuity (penetrating keratoplasty, 20/63; epikerato-

plast y, 20/52), best specta cle-corrected visu al a cuity(penetrating keratoplasty, 20/22; epikeratoplasty,20/23), and contact lens visual acuity (penetratingker at oplasty, 20/20; epiker at oplasty, 20/21).

Steinert compared 20 contemporous eyes thatunderwent penetrating keratoplasty or epikerato-plasty. 25 With a mean follow-up period of 33 monthsfor penetrating keratoplasty and 25 months forepikeratoplasty, the mean best spectacle-correctedvisual acuity was 20/27 after penetrating kerato-plasty and 20/32 after epikeratoplasty. No eyesachieved a best spectacle-corrected visual acuity of 20/20 or better with epikeratoplasty.

Goosey reported 16 nonrandomized eyes treatedwith penetrating keratoplasty (mean follow-up of 20 mo) and 31 treated with epikeratoplasty (meanfollow-up 19 mo). 26 Although 93% of eyes in eachgroup had a best spectacle-corrected visual acuitywith contact lenses of 20/40 or better, a higher per-centa ge of eyes th at h ad un dergone penetr at ing ker-atoplasty achieved visual acuity of 20/40 or better



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with spectacles (93% vs. 76%) or a best spectacle-corrected visual acuity of 20/20 or better with eitherspecta cles or conta ct lens (73% vs. 24%).

The curren t st udy provides more cases and longerfollow-up than previously published series to makea valid comparison of the visual outcome of pene-trating keratoplasty vs. epikeratoplasty in the sur-gical treatment of keratoconus. The data is furtherstr engthen ed becau se: (1) the stu dy involved a largenumber of patients treated by a relatively smallnumber of surgeons at a single institution usingsimilar protocols, (2) variability between the twogroups that might have been induced by mitigatingcircumstances such as compliance, distance fromthe treating center, and other socioeconomic circum-stances were eliminated by selection of patientsfrom the same pool, and (3) the similar percentageof type of ocula r r eha bilita tion chosen by pat ient s inboth groups.

When the data were analyzed irrespective of thepreferred meth od of visual reh abilitat ion, th ere wasno significant difference in visual acuity betweenpenetrating keratoplasty and epikeratoplasty forthe first 2 postoperative years. Beginning with theth ird postoperative year, th e st atistical significan ceof better visual acuity with penetrating keratoplas-ty than epikeratoplasty increased with progressive-ly longer follow-up. This may have been due to therelatively low percenta ge of penetra ting ker at oplas-ty eyes with optical correction after 2 years (26%),and the subsequent increase in percentage of pene-

trating keratoplasty eyes with spectacle or contactlens reha bilitat ion a t t he end of th e stud y (47%), asopposed to the relatively fixed percentage of epiker-atoplasty eyes with optical correction at 2 years(45%) and at the end of the study (48%). The finalmedian visual acuity was one Snellen line betterwith pen etra ting ker at oplast y (20/40 vs. 20/50) andwas highly sta tistically significan t ( P < .00005).

The difference in visual outcome between pene-trating keratoplasty and epikeratoplasty was evenmore str iking among pa tients who chose optical cor-rection. Corrected visual outcomes were availablefor 209 (47%) penetrating keratoplasty eyes and

77 (48%) epikeratoplasty eyes. Although this repre-sents less than 50% of each group, the absolutenumber of patients available for analysis of long-term outcome is larger than any existing compara-tive series. 24-26 Significant ly better median correctedvisual acuity was achieved with penetr at ing kerat o-plasty at 2 years and maintained thereafter. Thefinal median corrected visual acuity was two

Snellen lines better with penetrating keratoplasty(20/30 vs. 20/50) and was highly statistically signif-ican t ( P < .00005).

As with previous st udies, in most pa tients excel-lent vision was achieved with penetrating kerato-plasty, and satisfactory vision with epikeratoplasty.Although penetra ting keratoplasty rema ins the sur-gical pr ocedur e of choice for ker at oconus, ep ikera to-plasty may be selected as an entry level procedurein some situations. These include cases where(1) professional or athletic demands preclude a pro-longed period of restricted activity or pose a threatof wound d ehiscence (eg, conta ct sports s uch a s box-ing), (2) the visual demands are reduced and/orsafety concerns weigh h eavily (eg, Downs syn -drome), or (3) the patient is willing to undergo apotential sta ged approach to visua l reha bilitation inreturn for the added safety and reduced restrictionof epikeratoplasty, holding secondary penetratingkera toplasty in reserve if initial results ar e unsa tis-factory. The large n umber of pat ients en rolled in t hecur rent stu dy, along with th e str atification of visualacuity results into percentiles at each time point,provide dat a t ha t can be used t o provide prospectivesur gical can didates with reasonable expecta tions of sur gical outcome with eith er p rocedure.

REFERENCES1. Krachmer J H, Feder FS, Belin MW. Kerat oconus and relat-

ed noninflammatory corneal thinning disorders. SurvOpht ha lmol 1984;28:293-322.

2. Lass JH , Lembach RAG, Park SB, Hom DL, Fri tz ME,Svilar GM, Nuamah IF, Reinhart WJ, Stocker EG, KeatesRH. Clinical man agement of kera toconus. A multicenteran alysis. Oph th almology 1990;97:433-435.

3. Wood TO. Lamellar kera toplasty in kerat oconus. Am JOpht ha lmol 1971;86:543-536.

4. Richar d JM, Paton D, Gasset AR. A compar ison of penetra t-ing keratoplasty and lamellar keratoplasty in the surgicalmanagement of kera toconus . Am J Ophtha lmol1978;86:807-810.

5. Kirkness CM, Ficker LA, Steele AD, Rice NS. The success of penetrat ing keratoplasty for keratoconus. Eye 1990;4:673-688.

6. Shar if KW, Casey TA. Penetr ating kera toplasty for kerato-conus: complications and long-term success. Br JOpht ha lmol 1991;75:142-146.

7. Tuft SJ , Gregory WM, Davison CR. Bilateral penetr atingkeratoplasty for keratoconus. Ophthalmology 1995;102:462-468.

8. Paglen P G, Fine M, Abbott RL, Webster RG. The pr ognosisfor keratoplasty in keratoconus. Ophthalmology1982;89:651-654.

9. Price FW Jr, Whitson WE, Mark s RG. Graft sur vival in fourcommon groups of patients undergoing penetrating kerato-plast y. Oph th alm ology 1991;98:322-328.

10. Mahmood MA, Wagoner MD. Penetra ting kera toplasty forkerat oconus: Long-term resu lts in 38 eyes with an d 202 eyeswithout vernal kera toconjunctivitis. Mid East J Ophtha lmol1999;7:26-35.



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9/9

11. Chandler J W, Kaufma n HE. Graft rejections after kera to-plasty for keratoconus. Am J Ophthalmol 1974;77:543-537.

12. Epstein RJ, Seedor J A, Dreizen NG. Penetrat ing kerato-plasty for herpes simplex keratitis and keratoconus: allo-graft rejection and survival . Ophthalmology 1987;94:935-942.

13. Girard LJ , Esnaola N, Rao R, Barn ett L, el-Maghra by A,Canizales R. Allograft rejection after penetrating kerato-

plasty for keratoconus. Ophthalmic Surg 1993;24:40-43.14. Fong LP, Ormerod LD, Kenyon KR, Foster CS. Microbial

kerati t is complicating penetrat ing keratoplasty.Opht ha lmology 1988;95:1269-1275.

15. Var ley GA, Meisler DM. Complications of penet ra tingkeratoplasty: graft infections. Refract Corneal Surg 1991;7:62-66.

16. al-Hazaa S, Tabbara K. Bacterial kerati t is after penetrat ingkera toplast y. Opht ha lmology 1988;95:1504-1508.

17. Rehany U, Rumelt S. Ocular trau ma following penetra tingkeratoplasty: incidence, outcome, and postoperative recom-mendations. Arch Ophthalmol 1998;116:1282-1286.

18. Kaufman HE , Werblin TP. Epikeratophakia for the tr eat-ment of keratoconus. Am J Ophthalmol 1982;93:342-347.

19. McDonald MB, Kaufman HE, Durrie DS, Keates RH,Sanders DR. Epikeratophakia for keratoconus: the nation-wide st udy. Arch Opht ha lmol 1986;104:1294-1300.

20. Fronterr e A, Portesa ni GP. Epikeratoplasty for keratoconus.Report of 40 cases . Cornea 1989;8:236-239.

21. Waller SG, Steinert RF, Wagoner MD. Long-term resu lts of epikeratoplasty for keratoconus. Cornea 1995;14:84-88.

22. Radema ker WJ, Wagoner MD. Epikeratoplasty for kerato-conus: long-term results in 114 eyes with and 108 eyes with-out apical corneal scarring. Middle East J Ophthalmology1999;7:36-47.

23. McDona ld MB, Safir A, War ing GO, Schlichtem eier WR,Kissl ing GE, Kaufman HE. A preliminary comparat ive

study of epikeratophakia or penetrating keratoplasty forkeratoconus. Am J Ophthalmol 1987;103:467.

24. Fronter re A, Portesani GP. Comparison of epikeratoplastyand penetrat ing keratoplasty for keratoconus. RefractCornea l Sur g 1991;7:167-173.

25. Steinert RF, Wagoner MD. Long term compar ison of epiker-atoplasty and penetrating keratoplasty for keratoconus.Arch Oph th almol 1988;106:493-496.

26. Goosey JD, Prager TC, Goosey CB, Bird E F, Sanderson J C.A compar ison of penetra ting kerat oplasty to epikeratoplastyin the management of keratoconus. Am J Ophthalmol1991;111:145-151.

27. Teichma nn KD, Wagoner MD. Mooren ulcer after epikera to-plasty for keratoconus. Arch Ophthalmol 1998;116:1381-1382.

28. Mahm ood M, Wagoner MD. Penetr ating kerat oplasty ineyes with keratoconus and vernal keratoconjunctivitis.

Cornea 2000;19:468-470.



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