Angle-supported Phakic Intraocular LensesFollowed by Laser-assisted In Situ

Keratomileusis for the Correction ofHigh Myopia

GONZALO MUNOZ, MD, PHD, JORGE L. ALIO, MD, PHD,ROBERT MONTES-MICO, OD, MPHIL, AND JOSE I. BELDA, MD, PHD

● PURPOSE: To evaluate the safety, effectiveness, pre-dictability, and stability of the combination of angle-supported phakic intraocular lens (PIOL) implantationand laser-assisted in situ keratomileusis (LASIK) for thecorrection of high myopia.● DESIGN: Noncomparative interventional case series.● METHODS: At the Instituto Oftalmologico de Alicante,Spain, 24 consecutive eyes of 12 patients with a preop-erative spherical equivalent between �9 and �26 diopt-ers were studied. Implantation of an angle-supportedPIOL was done as the first surgery. Laser-assisted in situkeratomileusis was performed at least 6 months afterPIOL surgery, once stability of topography and refractionwere proved. Main outcome measures were uncorrectedvisual acuity (UCVA), best-corrected visual acuity(BCVA), refraction, applanation tonometry, and cornealendothelial study (cell density, hexagonality, and coeffi-cient of variation), with a minimum follow-up of 12months after LASIK.● RESULTS: The mean spherical equivalent refractiondecreased from �15.17 � 5.15 diopters before PIOLimplantation to �1.33 � 1.18 diopters after PIOLsurgery and to 0.01 � 0.53 12 months after LASIK.Uncorrected visual acuity was 0.39 � 0.12 after PIOLsurgery, increasing to 0.65 � 0.23 12 months afterLASIK. There was an increase in 20/40 or better UCVAfrom 16.6% after PIOL surgery alone to 83.3% afteraddition of LASIK. At final follow-up, spherical equiva-lent was within � 1 diopter of emmetropia in 22 eyes(91.7%) and in 18 eyes (75%) within � 0.50 diopters.Vector analysis demonstrated that astigmatic components

of refractive error after PIOL surgery were well cor-rected by LASIK. At final follow-up the mean endothe-lial cell loss was 4.88% (P < .001). There were nostatistically significant differences between mean endo-thelial cell count, percentage of hexagonality, or coeffi-cient of variation before LASIK and 12 months afterLASIK, suggesting that no corneal endothelial damagewas produced by LASIK itself. No sight-threateningcomplications occurred through the follow-up period.● CONCLUSION: The combination of angle-supportedPIOL implantation and LASIK appears to be a safe,effective, predictable, and stable procedure for the cor-rection of high myopia. This paper emphasizes the ben-efits of adding LASIK to the use of PIOL alone. (Am JOphthalmol 2003;136:490–499. © 2003 by ElsevierInc. All rights reserved.)

T HE IMPLANTATION OF A PHAKIC INTRAOCULAR

lens (PIOL) for the correction of high myopia hastheoretical advantages in comparison with corneal

procedures and clear lens extraction, such as precision andstability not dependent on the corneal healing process, awider range of correction, magnification of the intraocularimage, and preservation of accommodation.1–7 However,potential complications of PIOL such as uveitis, endoph-thalmitis, glaucoma, corneal damage, cataract, retinal de-tachment, and pupil ovalization limit their use at thepresent moment.8–15

Laser-assisted in situ keratomileusis (LASIK) has beenused for the correction of residual refractive errors after avariety of surgical procedures, including laser thermalkeratoplasty, penetrating keratoplasty, radial keratotomy,clear lens extraction, and photorefractive keratecto-my.16–26 There are few studies in the literature regardingthe use of LASIK to enhance the refractive results afterPIOL implantation for high myopia, and none of them hasbeen performed in eyes containing an angle-supported

Accepted for publication Feb 20, 2003.InternetAdvance publication at ajo.com March 6, 2003.From the Refractive Surgery Department, Instituto Oftalmologico de

Alicante, and the Division of Ophthalmology, Miguel Hernandez Uni-versity, Alicante, Spain.

Inquiries to Gonzalo Munoz, MD, Instituto Oftalmologico de Alicante,Avda. Denia 111, 03015 Alicante, Spain; e-mail: gon.munoz@terra.es

© 2003 BY ELSEVIER INC. ALL RIGHTS RESERVED.490 0002-9394/03/$30.00doi:10.1016/S0002-9394(03)00240-X

PIOL.27–31 The aim of this study was to evaluate the safety,effectiveness, predictability, and stability of the combina-tion of angle-supported PIOL implantation followed byLASIK for the correction of high myopia, with specialattention to the effects on the corneal endothelium.

METHODS

TWENTY-FOUR CONSECUTIVE EYES OF 12 PATIENTS WERE

enrolled in this prospective study (6 men, 6 women), withages ranging from 25 to 33 years (27.3 � 4.2). Thepreoperative spherical equivalent (SE) ranged from �9.75diopters (D) to �26.0 diopters (D) (mean �15.17 �5.15). All the patients were informed about the details andrisks of both the PIOL and LASIK procedures and awritten informed consent was obtained in accordance withthe Helsinki Declaration. No Institutional Review Boardapproval was required for this study.

Inclusion criteria were eyes with SE higher than �12 Dwith or without astigmatism or eyes with SE between�9.75 D and �12 D in which corneas were thinner than500 �m. Exclusion criteria were best-corrected visualacuity (BCVA) less than 20/80, pupillary diameter largerthan 5 mm under dim illumination, evidence of develop-ing cataract, history of uveitis or posterior synechiae,corneal dystrophy or endothelial cell count of less than2,250 cells/mm2, intraocular pressure higher than 20 mmHg, and presence of retinal or optic disk pathology.

Preoperative evaluation included uncorrected visualacuity (UCVA), BCVA with contact lens overrefraction,refraction, slit-lamp biomicroscopy, applanation tonome-try, fundus examination, ultrasonic pachymetry, keratom-etry, and corneal topography. A corneal endothelial studyof the central cornea was performed by the same physicianusing a Konan SP5500 (Konan Camera Research Institute,Hyogo, Japan) contact endothelial cell meter. Cell density,percentage of hexagonality, and coefficient of variationwere documented. Three specular microscopic images ofthe central portion of the cornea were taken using videospecular endothelioscopy. The images were analyzed afterdigitization by a Konan KC-87 A image analysis system(Konan Camera Research Institute). For each cornea, 100to 150 cells were digitized and analyzed using the mor-phometry program of the software. Cell density was calcu-lated automatically by the computer Cell Analyzer Version4.00 (Konan Camera Research Institute). The endothelialstudy was done before PIOL implantation, immediatelybefore LASIK, and repeated at 12 months after LASIK.Endothelial cell count before PIOL surgery was used inevery case as reference to calculate endothelial cell loss.

The first surgery consisted on the implantation of anangle-supported IOL into the anterior chamber through a6-mm posterior corneal incision under peribulbar anesthe-sia.8 The IOL used in this study was a the ZSAL-4 model(Morcher, Stuttgart, Germany). This is a single-piece

polymethylmethacrylate (PMMA) anterior chamber an-gle-supported IOL with Kelman-type design of the haptics,19-degree haptic angulation to reduce potential iris orcrystalline lens contact, and a total length of 12.5, 13 or13.5 mm. The optic is flat at the anterior surface andconcave at the posterior surface, with a diameter of 5.5 mm(effective diameter, 5.0 mm). The optic has a transitionaledge with a three-sided design to reduce glare. The lens issupplied in powers ranging from �10 to �23 diopters.

The LASIK was performed at least 6 months after PIOLsurgery. Both surgeries were done between January 1998and June 1999, and all the patients were consecutivelyoperated on and followed up by the same physician (GM)at Instituto Oftalmologico de Alicante, Spain. All thesutures had been removed at least 3 months before LASIK,and all the eyes showed a stable refraction and cornealtopographic pattern for at least 3 months before perform-ing LASIK. The mean interval between PIOL surgery andLASIK was 7.3 � 4.6 months (range 6–14). Sixteen eyeshad residual myopia or myopic astigmatism, and 8 eyes hadmixed astigmatism after PIOL surgery. All the patientsunderwent LASIK surgery using the the Chiron TechnolasKeracor 117 excimer laser with the PlanoScan program(Bausch & Lomb Surgical, Munich, Germany), and a2-mm flying spot. Lamellar keratotomy was performedusing the Automated Corneal Shaper (ALK-E; ChironVision, Irvine, California, USA) to create a flap of 8.5 mmand 160 �m. In the case of myopic astigmatism, ablationwas performed in the steep meridian (negative cylinderablation). In the case of mixed astigmatism, half of theablation was performed in the steep meridian (negativecylinder ablation) and half in the flat meridian (positivecylinder ablation), the so-called cross-cylinder tech-nique.32,33

Both after PIOL surgery and after LASIK all the patientsfulfilled the follow-up protocol in which the examinationvisits were carried out at 1 day, 1 week, and 1 month,and then every 3 months as necessary. Data concerningpostoperative visits included UCVA, BCVA, refraction,slit-lamp examination, applanation tonometry, cornealtopography, and corneal endothelial study as mentionedpreviously. All the eyes fulfilled a follow-up period of atleast 12 months after LASIK. Data were extracted foranalysis from chart review, and both eyes of the samepatient were analyzed separately.

Following the power vector method the refractionsobtained before and 12 months after LASIK were assessedfor astigmatism analysis.34,35 Any spherocylindrical refrac-tive error was expressed by three dioptric powers: M, J0, J45;with M being a spherical lens equal to the sphericalequivalent of the given refractive error, and J0 and J45 twoJackson crossed cylinders equivalent to the conventionalcylinder. These numbers are the coordinates of a point ina three-dimensional dioptric space, being the power vectorthe vector originated from the origin of this space to thepoint (M, J0, J45). Consequently, the length of this vector

CORRECTION OF HIGH MYOPIAVOL. 136, NO. 3 491

is a measure of the overall blurring strength B of aspherocylindrical refractive error.34,35 Manifest refractionsin conventional script notation [S (sphere), C (cylinder)� � (axis)] were converted to power vectors coordinatesand overall blurring strength by the following formulas: M� S � C/2; J0 � (�C/2) cos (2�); J45 � (�C/2) sin (2�);B � (M2 � J0

2 � J452)1/2.

A scale from 1 (very poor) to 5 (excellent) was used toevaluate patient satisfaction at final follow-up. The follow-ing symptoms were also evaluated: glare, halos, pain, andforeign body sensation; and they were rated as 1 (veryintense), 2 (intense), 3 (moderate), 4 (few), and 5 (none).

Statistical analysis was performed with the SPSS statis-tics software package SPSS/Pc � 10.1 for Windows (SPSS,Chicago, Illinois, USA). Normality of the data in eachgroup was confirmed by the normal probability plots. TheStudent t test for paired data were used for comparison, anddifferences were considered statistically significant whenthe probability value was less than 0.05. Monovariate t testand Hotelling T2 test of multivariate satitistics were usedfor astigmatism analysis before and after LASIK.

RESULTSA SUMMARY OF THE RESULTS IS SHOWN IN TABLES 1 AND 2.

Safety, efficacy, predictability, and stability of the com-bined procedures are shown in Figures 1 to 4.

Preoperative UCVA was 0.02 � 0.02 (range, 0.01–0.05). After PIOL implantation but before LASIK, UCVAsignificantly improved to 0.39 � 0.12 (range, 0.20–0.60;Student t test for paired data, P � .001). Twelve months afterLASIK, UCVA was 0.65 � 0.23 (range, 0.30–1.00). Uncor-rected visual acuity after LASIK was significantly better thanbefore LASIK (Student t test for paired data, P � .001).

At final follow-up 20 eyes (83.3%) achieved UCVA of20/40 or better, and 6 eyes (25.0%) achieved UCVA of20/20. No eyes had an UCVA worse than 20/80. Regard-ing BCVA, one eye (4.2%) lost 1 Snellen line of BCVA,9 eyes (37.5%) gained 1 line of BCVA, 7 eyes (29.2%)gained 2 lines, and 2 eyes (8.3%) gained 3 lines of vision12 months after LASIK compared with the preoperativevalues.

The mean preoperative spherical equivalent refractionwas �15.17 � 5.15 (�9.75 to �26.00). The meanpostoperative spherical equivalent refraction before theLASIK procedure was �1.33 � 1.18 (�4.00 to 0), and itwas 0.33 � 0.48 (�0.75–1.00), 0.17 � 0.48 (�1–1.00),and 0.01 � 0.53 (�1.25 to 0.75), respectively, at 1, 3, and12 months after LASIK. There were statistically significantdifferences among months 1, 3, and 12 postoperativelyusing the Student t test for paired data (P � .005). Threeeyes (12.5%) showed a change in spherical equivalenthigher than 1 D over the follow-up period after LASIK.

TABLE 1. Preoperative and Postoperative Results of the Combination of Angle-supportedPhakic Intraocular Lens (PIOL) Implantation Followed by Laser-Assisted In Situ

Keratomileusis (LASIK) in Eyes With High Myopia

Before PIOL Surgery

After PIOL Surgery and

Before LASIK

Twelve Months

After LASIK

UCVA 0.02 � 0.02 0.39 � 0.12 0.65 � 0.23

BCVA 0.63 � 0.23 0.71 � 0.18 0.74 � 0.20

�1.00 D of emmetropic SE (%) — 66.6 91.7

�0.50 D of emmetropic SE (%) — 16.6 75.0

UCVA � 20/40 (%) — 16.6 83.3

Loss � 2 lines BCVA (%) — 0 0

Gain � 1 line BCVA (%) — 66.6 75.0

BCVA � best-corrected visual acuity; D � diopter; SE � spherical equivalent; UCVA � uncorrected

visual acuity.

TABLE 2. Preoperative and Postoperative Refractive Results of the Combination of Angle-supported Phakic Intraocular Lens (PIOL) Implantation Followed by Laser-Assisted In Situ

Keratomileusis (LASIK) in Eyes With High Myopia

Before PIOL Surgery

After PIOL Surgery and

Before LASIK

Twelve Months

After LASIK

Sphere �14.25 � 5.13 �0.47 � 1.42 0.20 � 0.45

Cylinder �1.83 � 1.31 �1.73 � 1.28 �0.33 � 0.50

Spherical equivalent �15.17 � 5.15 �1.33 � 1.18 0.01 � 0.53

AMERICAN JOURNAL OF OPHTHALMOLOGY492 SEPTEMBER 2003

Twelve months after LASIK 22 eyes (91.7%) werewithin �1.00 D of emmetropia, and 18 eyes (75.0%)were within �0.50 D. The mean preoperative sphericalcomponent of the refractive error was �14.25 � 5.13

(�26.00 to �9.00) and decreased to �0.47 � 1.42(�3.50 to 1.50) after PIOL implantation. Twelvemonths after LASIK, it decreased to 0.20 � 0.45 D(�0.75 to 1.00).

FIGURE 1. Safety: best-corrected visual acuity (BCVA) before phakic intraocular implantation vs best-corrected visual acuity 1year after laser-assisted in situ keratomileusis.

FIGURE 2. Efficacy: best-corrected visual acuity (BCVA) before phakic intraocular implantation vs uncorrected visual acuity(UCVA) 1 year after laser-assisted in situ keratomileusis.

CORRECTION OF HIGH MYOPIAVOL. 136, NO. 3 493

The mean preoperative astigmatism was �1.83 � 1.31D (0 to �4.00). The mean postoperative astigmatism afterPIOL implantation was �1.73 � 1.28 (0 to �5.00). At 12months after LASIK, it was �0.33 � 0.50 (0 to �1.50).

Eighteen eyes (75.0%) were within � 0.5 D of astigmaticintended correction, and 22 eyes (91.7%) were within � 1 D.

A statistical summary of the distribution of manifestrefractive errors after vector conversion before and after

FIGURE 3. Predictability: attempted correction spherical equivalent (SE) before phakic intraocular lens surgery vs achievedcorrection SE 1 year after laser-assisted in situ keratomileusis.

FIGURE 4. Stability: mean spherical equivalent before phakic intraocular implantation (PREPIOL), before laser-assisted in situkeratomileusis (LASIK [PRELSK]) and at 1 month after LASIK (POSTLK1), 3 months after LASIK (POSTLK3), and 12 monthsafter LASIK (POSTLK12).

AMERICAN JOURNAL OF OPHTHALMOLOGY494 SEPTEMBER 2003

LASIK is shown in Table 3. To view the change inastigmatism caused by LASIK, Figure 5 shows the astig-matic component of the power vector as represented by thetwo-dimensional vector (J0, J45). The origin in this graphrepresents an eye free of astigmatism. We expected to seethe cluster of points collapse around the origin aftersurgery, and this was the result obtained.

Twelve months after the second surgery (LASIK), themean subjective response was 4.33 � 0.70 in the scalepreviously mentioned. Glare was given 4.29 � 0.75; halos3.83 � 0.82; pain 4.29 � 0.69; and foreign body sensation4.04 � 0.86.

A summary of the corneal endothelium results is shownin Table 4. The mean preoperative endothelial cell densitywas 2,976 � 184 cells/mm2 (range, 2,708–3,318 cells/mm2), which significantly decreased to 2,836 � 202cells/mm2 (range, 2,524–3,200 cells/mm2) after PIOL sur-gery (Student t test for paired data, P � .001). The PIOLsurgery produced a 4.77% mean loss of endothelial cellsmeasured at 6 to 14 months after PIOL implantation.Twelve months after LASIK, mean endothelial cell countremained nearly unchanged: 2,833 � 201 cells/mm2 (range2,542–3,204 cells/mm2). There were no statistically signif-icant differences between mean endothelial cell countbefore LASIK and 12 months after LASIK (Student t testfor paired data, P � .457). The mean cell loss after PIOLbut before LASIK was 142 � 61 cells/mm2 (range, 44–264cells/mm2). The mean cell loss 12 months after LASIK was145 � 67 cells/mm2 (range, 34–274 cells/mm2).

Regarding endothelial morphometric data, percentageof hexagonality was 68.9 � 6.7 before PIOL surgery, 63.2� 6.9 inmediately before LASIK (Student t test for paireddata, P � .001), and 62.8 � 5.3 12 months after LASIK(Student t test for paired data, P � .001). The meanbaseline coefficient of variation in cell size was 0.274 �0.034 before PIOL implantation, 0.310 � 0.032 beforeLASIK (Student t test for paired data, P � .001), and0.309 � 0.034 12 months after LASIK (Student t test forpaired data, P � .001). There were no statistically signif-icative differences between percentages of hexagonality(Student t test for paired data, P � .47) or coefficients ofvariation (Student t test for paired data, P � .60) beforeLASIK and 12 months after LASIK.

No sight-threatening complications occurred during thestudy. A mild anterior chamber reaction was detected infour eyes (16.7%) after PIOL implantation, and intraocularpressure higher than 22 mm Hg was detected in five eyes(20.8%). Discrete pupil ovalization was present in threeeyes (12.5%). There were no complications related to themicrokeratome lamellar cut. After LASIK all the corneasremained clear since the first postoperative day. No cor-neal edema, intraocular lens displacement, pupillary block,cataract, or retinal complications were observed during thefollow-up period.

DISCUSSION

THE TREATMENT OF HIGH MYOPIA FREQUENTLY NEEDS THE

combined use of different surgical techniques to achieveoptimal refactive results. Concepts such as bioptics andadjustable refractive surgery refer to this combination.27–31,36

The present study emphasizes the benefits of addingLASIK to the use of PIOL alone. To the best of ourknowledge no previous study regarding the combined useof angle-supported PIOLs and LASIK has been publishedin the literature. Concerning efficacy, the present studyshowed an increase in 20/40 or better UCVA from 16.6%after PIOL surgery alone to 83.3% after addition of LASIK.High predictabiliy was shown in the present study, with75% of eyes within �0.5 D of emmetropia and 91.7% ofeyes within �1 D. These results are similar to thosereported in other studies in which the combination ofPIOL and LASIK has been used for the surgical correctionof high myopia.27–31 Zaldivar and associates27 used LASIKto correct the residual refractive defect after posteriorchamber PIOL implantation for high myopia. They re-ported a mean postoperative spherical equivalent andcylinder power of �0.20 � 0.90 and �0.50 � 0.50 D,respectively. In this group of patients, 85% of eyesachieved a postoperative spherical equivalent refractionwithin �1.00 D and 67% of eyes within �0.5 D ofemmetropia.27 Guell and associates28 in a series of eighteyes with iris-fixated PIOL for high myopia and residualrefractive error treated by LASIK reported 62.5% of theeyes within �0.5 diopters of emmetropia and 100% within

TABLE 3. Summary of Distribution of Manifest Refractive Errors Before and After Laser-assisted In Situ Keratomileusis (LASIK) inEyes Containing an Angle-Supported Phakic Intraocular Lens for High Myopia, Following the Power Vector Method34,35

Before LASIK After LASIK

M J0 J45 B M J0 J45 B

Mean �1.333 �0.459 0.125 1.790 0.032 �0.043 0.030 0.387

SD 1.176 0.789 0.422 1.038 0.522 0.195 0.197 0.458

Manifest refractions in conventional script notation [S (sphere), C (cylinder) � � (axis)] were converted to power vectors coordinates (M, J0,

J45) and overall blurring strength (B) by the following formulas: M�S�C/2;J0�(�C/2)cos(2�);J45�(�C/2)sin(2�);B�(M2�J02�J45

2)1/2

CORRECTION OF HIGH MYOPIAVOL. 136, NO. 3 495

�1 D. Guell and coworkers30 used a combination ofiris-fixated PIOL surgery followed by LASIK for the cor-rection of 26 eyes with myopia ranging from �16 to �23

D. All of the eyes were within �1.00 D of emmetropia,and 80.7% were within �0.50 D. These results were betterthan those of previous studies, in which only the implan-

FIGURE 5. Manifest astigmatism before laser–assisted in situ keratomileusis (A) is reduced on average after surgery (B). Each datapoint represents the astigmatism component of a power vector for one eye.

AMERICAN JOURNAL OF OPHTHALMOLOGY496 SEPTEMBER 2003

tation of the same PIOL was used.37 Sanchez-Galeana andassociates29 performed LASIK or photorefractive keratec-tomy in 37 eyes containing a posterior chamber PIOL forhigh myopia. Final refraction after LASIK was within �0.5D in 83.7% of eyes and within �1 D in 97.2%.29 In termsof stability, our study showed a slight regression of effectbetween the third month and 1 year of follow-up afterLASIK, with �0.15 D of spherical equivalent change.Mean regression of �0.15 D was also found by Perez-Santonja and coworkers38 after primary LASIK for myopiaranging from �8 to �12 D.

No sight-threatening complications were observed inthe present study. Mild anterior uveitis in the earlypostoperative period after PIOL implantation was observedin four eyes (16.7%), which was controlled with topicalcorticosteroids in less than 2 to 3 weeks. Phakic IOLsurgery has been associated previously with anterior uve-itis,8 whereas LASIK performed on normal eyes is notusually associated with inflammation in the anterior cham-ber.39 Ocular hypertension was detected in five eyes(20.8%), but discontinuation of topical corticosteroids andthe use of topical -blockers resulted in returning thepressure under the baseline level before surgery in all thecases. No cases of chronic glaucoma were detected in thepresent study, but the relatively short follow-up mayexplain this finding in eyes with high myopia and ananterior chamber PIOL. Postoperative anterior uveitis andocular hypertension have been previously reported afterangle-supported PIOL surgery, but no cases of chronicglaucoma induced by this procedure were reported in thesame study.8 In our experience no corneal edema, intraoc-ular lens displacement or decentration, pupillary block,cataract, or retinal complications were observed. Alio andassociates8 reported 4.56% incidence of acute iritis, 7.2%of high intraocular pressure requiring treatment, 5.9% ofsignificant pupil ovalization, 3.42% of cataract develop-ment, and 3% of retinal detachment in a group of 263 eyeswith angle-supported PIOLs and a long follow-up of 7years. The younger mean age of the population of thepresent study together with the shorter follow-up mayexplain the lower incidence of cataract development incomparison with the study by Alio and associates.8Sanchez-Galeana and coworkers29 reported the develop-ment of anterior subcapsular opacities in three eyes several

weeks after excimer laser surgery in eyes containing pos-terior chamber PIOLs for high myopia. They also reportedocular hypertension and macular hemorrhage in one eyeeach. Anterior subcapsular opacities is a well-known com-plication of posterior chamber PIOL.11–13 Macular hemor-rhage is another complication that has been previouslyreported in association with LASIK.40

One of the main problems with anterior chamber PIOLimplantation is the potential for damage to the anteriorsegment structures, especially the corneal endothelium.However, recent studies indicate that new models ofangle-supported and iris-fixated PIOL are well tolerated bythe corneal endothelium as improvement in IOL designand quality of surgery is made.3,8 Conversely, primaryLASIK has been shown to cause no damage to the centralcorneal endothelium.41–42 The present study showed a4.77% mean loss of endothelial cells 7.3 � 4.6 months(range, 6–14 months) after PIOL surgery, and 4.87% meanloss 12 months after LASIK. As the mean endothelial cellcount before LASIK and 12 months after LASIK remainednearly unchanged, it seems that no endothelial cell dam-age was caused by LASIK in this group of eyes containingan angle-supported PIOL. Alio and associates8 reported apercentage of cell loss of 3.76% at 3 months and 5.59% at1 year after implantation of an angle-supported PIOL,percentages similar to the findings of the present study.Total cumulative loss of central endothelial cells after 7years of follow-up was 8.37% in the same study.8 Weperformed morphometric analysis of the corneal endothe-lium because variation in the shape and size of theendothelial cells is considered a more specific sign ofendothelial damage than quantitative variation in celldensity alone.43 Polymegethism or variation in cell size isquantitatively measured by the coefficient of variationwith a normal value of less than 0.33.44 An increase in thisvalue points toward endothelial instability, an indirect signof cell damage. Pleomorphism or variation in cell shape isquantitatively measured by the percentage of hexagonalitywith a value higher than 60% in normal corneas.44 In thepresent study percentage of hexagonality and coefficient ofvariation showed statistically significant differences beforeand after PIOL surgery but no statistically significantdifferences before and 12 months after LASIK, suggesting

TABLE 4. Corneal Endothelial Parameters Before Phakic Intraocular Lens (PIOL) Surgery, Immediately Before Laser–assisted InSitu Keratomileusis (LASIK) and 12 Months After LASIK in Eyes With Angle-supported PIOL for High Myopia

Before PIOL

Before LASIK (7.3 � 4.6

Months After PIOL Surgery)

12 Months

After LASIK

Endothelial cell density (cells/mm2) 2976 � 184 2836 � 202 2833 � 201

Hexagonality (%) 68.91 � 6.68 63.25 � 6.90 62.79 � 5.30

Coefficient of variation 0.274 � 0.035 0.310 � 0.032 0.309 � 0.034

Mean loss (%) — 4.77 4.87

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no additional damage caused by LASIK over that causedby PIOL surgery itself.

There have been concerns about the use of the micro-keratome in eyes containing a PIOL. Guell and cowork-ers28,30 proposed a two-step LASIK consisting of makingthe corneal flap at the time of PIOL implantation anddoing the laser ablation several months later to avoid anypossible contact between the PIOL and the corneal endo-thelium at the time of the keratome pass. However, Guelland associates28 showed no change in endothelial celldensity before and after LASIK in a series of eight eyescontaining iris-fixated PIOLs for the correction of highmyopia. Conversely, specific complications of LASIK suchas epithelial ingrowth and peripheral flap melting are morecommon after LASIK retreatments than after primaryLASIK.45 The epithelium debridement and the interfacedissection made when the flap is lifted several months afterthe microkeratome cut create an irregular epithelial borderand epithelial defects that may facilitate epithelial growthbeneath the flap edge. One could expect a higher inci-dence of epithelial ingrowth and peripheral flap meltingafter LASIK enhancement of a PIOL surgery with thetwo-step approach. In our opinion it is necessary todemonstrate evidence of endothelial damage caused byLASIK in an eye containing a PIOL to recommendperforming the corneal flap before the PIOL surgery. Thetheoretical endothelial cell protective effect of performingthe corneal flap before PIOL implantation should beweighed against the possibility of having a higher inci-dence of peripheral flap melting and epithelial ingrowthwith this two-step approach for LASIK.

In summary, the combination of angle-supported PIOLimplantation and LASIK appears to be a safe, effective,predictable, and stable method for the correction of highmyopia. The LASIK surgery did not add corneal endothe-lial cell damage to that produced by PIOL surgery, suggest-ing that making the corneal flap in an eye containing anangle-supported PIOL is a safe procedure. Preservation ofaccommodation, better quality of vision in dim illumina-tion, good predictability, and safety are factors that en-courage the use of PIOL implantation followed by LASIKwhen evaluating the surgical options for subjects with highmyopia. Further studies with a larger number of patientsand longer follow-up period are needed to determine therisk of complications associated with angle-supported PI-OLs such as cataract, uveitis, glaucoma, corneal endothe-lium damage, and retinal detachment.

REFERENCES

1. Baikoff G, Arne JL, Bokobza Y, et al. Angle-fixated anteriorchamber phakic intraocular lens for myopia of �7 to �19diopters. J Refract Surg 1998;14:282–293.

2. Allemann N, Chamon W, Tanaka HM, et al. Myopic

angle-supported intraocular lenses. Two-year follow-up.Ophthalmology 2000;107:1549–1554.

3. Menezo JL, Avino JA, Cisneros A, et al. Iris claw phakicintraocular lens for high myopia. J Refract Surg 1997;13:545–555.

4. Fechner PU, Haubitz I, Wichmann W, Wulff K. Worst-Fechner biconcave minus power phakic iris-claw lens. JRefract Surg 1999;15:93–105.

5. Zaldivar R, Davidorf JM, Oscherow S. Posterior chamberphakic intraocular lens for myopia of �8 to �19 diopters. JRefract Surg 1998;14:294–305.

6. Davidorf JM, Zaldivar R, Oscherow S. Posterior chamberphakic intraocular lens for hyperopia of �4 to �11 diopters.J Refract Surg 1998;14:306–311.

7. Colin J, Robinet A. Clear lensectomy and implantation oflow-power posterior chamber intraocular lens for the correc-tion of high myopia: a four-year follow-up. Ophthalmology1997;104:73–77.

8. Alio JL, de la Hoz F, Perez-Santonja JJ, et al. Phakic anteriorchamber lenses for the correction of myopia: a 7-yearcumulative analysis of complications in 263 cases. Ophthal-mology 1999;106:458–466.

9. Risco JM, Cameron JA. Dislocation of a phakic intraocularlens. Am J Ophthalmol 1994;118:666–667.

10. Menezo JL, Cisneros AL, Rodriguez-Salvador V. Removal ofage-related cataract and iris claw phakic intraocular lens. JRefract Surg 1997;13:589–590.

11. Trindade F, Pereira F. Cataract formation after posteriorchamber phakic intraocular lens implantation. J CataractRefract Surg 1998;24:1661–1663.

12. Fink AM, Gore C, Rosen E. Cataract development afterimplantation of the Staar collamer posterior chamber phakiclens. J Cataract Refract Surg 1999;25:278–282.

13. Pesando PM, Ghiringhello MP, Tagliavacche P. Posteriorchamber collamer phakic intraocular lens for myopia andhyperopia. J Refract Surg 1999;15:415–423.

14. Perez-Santonja JJ, Ruiz-Moreno JM, de la Hoz F, et al.Endophthalmitis after phakic intraocular lens implantationto correct high myopia. J Cataract Refract Surg 1999;25:1295–1298.

15. Ruiz-Moreno JM, Alio JL, Perez-Santonja JJ, de la Hoz F.Retinal detachment in phakic eyes with anterior chamberintraocular lenses to correct severe myopia. Am J Ophthal-mol 1999;127:270–275.

16. Attia W, Perez-Santonja JJ, Alio JL. Laser in situ keratom-ileusis for recurrent hyperopia following laser thermal kera-toplasty. J Refract Surg 2000;16:163–169.

17. Portellinha W, Nakano K, Oliveira M, et al. Laser in situkeratomileusis for hyperopia after thermal keratoplasty. JRefract Surg 1999;15(Suppl):S218–220.

18. Donnenfeld ED, Kornstein HS, Amin A, et al. Laser in situkeratomileusis for correction of myopia and astigmatism afterpenetrating keratoplasty. Ophthalmology 1999;106:1966–1974.

19. Spadea L, Mosca L, Balestrazzi E. Effectiveness of LASIK tocorrect refractive error after penetrating keratoplasty. Oph-thalmic Surg Lasers 2000;31:111–120.

20. Attia WH, Alio JL, Artola A, et al. Laser in situ keratom-ileusis for undercorrection and overcorrection after radialkeratotomy. J Cataract Refract Surg 2001;27:267–272.

21. Francesconi CM, Nose RA, Nose W. Hyperopic laser-assisted in situ keratomileusis for radial keratotomy inducedhyperopia. Ophthalmology 2002;109:602–605.

22. Artola A, Ayala MJ, Claramonte P, et al. Photorefractivekeratectomy for residual myopia after cataract surgery. JCataract Refract Surg 1999;25:1456–1460.

AMERICAN JOURNAL OF OPHTHALMOLOGY498 SEPTEMBER 2003

23. Sakarya Y, Isik EC, Ermis SS. LASIK after PRK for myopicregression. J Cataract Refract Surg 1999;25:879.

24. Alio JL, Artola A, Attia WH, et al. Laser in situ keratom-ileusis for treatment of residual myopia after photorefractivekeratectomy. Am J Ophthalmol 2001;132:196–203.

25. Lazaro C, Castillo A, Hernandez-Matamoros JL, et al. Laserin situ keratomileusis enhancement after photorefractivekeratectomy. Ophthalmology 2001;108:1423–1429.

26. Guell JL, Gris O, de Muller A, Corcostegui B. LASIK for thecorrection of residual refractive errors from previous surgicalprocedures. Ophthalmic Surg Lasers 1999;30:341–349.

27. Zaldivar R, Davidorf JM, Oscherow S, et al. Combinedposterior chamber phakic intraocular lens and laser in situkeratomileusis: bioptics for extreme myopia. J Refract Surg1999;15:299–308.

28. Guell JL, Vazquez M, Gris O, et al. Combined surgery tocorrect high myopia: iris claw phakic intraocular lens andlaser in situ keratomileusis. J Refract Surg 1999;15:529–537.

29. Sanchez-Galeana CA, Smith RJ, Rodrıguez X, et al. Laser insitu keratomileusis and photorefractive keratectomy for re-sidual refractive error after phakic intraocular lens implan-tation. J Refract Surg 2001;17:299–304.

30. Guell JL, Vazquez M, Gris O. Adjustable refractive surgery:6-mm Artisan lens plus laser in situ keratomileusis for thecorrection of high myopia. Ophthalmology 2001;108:945–952.

31. Zaldivar R, Oscherow S, Piezzi V. Bioptics in phakic andpseudophakic intraocular lens with the Nidek EC-5000excimer laser. J Refract Surg 2002;18(Suppl):S336–339.

32. Chayet AS, Magallanes R, Montes M, et al. Laser in situkeratomileusis for simple myopic, mixed, and simple hyper-opic astigmatism. J Refract Surg 1998;14(Suppl):S175–176.

33. Molina R, Monasterio R, Soliz E, Foianini J. Correction ofastigmatism using positive and negative cylinder programswith the Nidek EC-5000 excimer laser. J Refract Surg1999;15(Suppl):S195–196.

34. Thibos LN, Wheeler W, Horner DG. Power vectors: anapplication of Fourier analysis to the description and statis-tical analysis of refractive error. Optom Vis Sci 1997;74:367–375.

35. Thibos LN, Horner DG. Power vector analysis of the opticaloutcome of refractive surgery. J Cataract Refract Surg 2001;27:80–85.

36. Guell J. The adjustable refractive surgery concept. J RefractSurg 1998;14:271.

37. Perez-Santonja JJ, Bueno JL, Zato MA. Surgical correction ofhigh myopia in phakic eyes with Worst-Fechner myopiaintraocular lenses. J Refract Surg 1997;13:268–281.

38. Perez-Santonja JJ, Bellot J, Claramonte P, et al. Laser in situkeratomileusis to correct high myopia. J Cataract RefractSurg 1997;23:372–385.

39. Perez-Santonja JJ, Sakla HF, Cardona C, et al. Subclinicalinflammation after laser in situ keratomileusis. J CataractRefract Surg 1998;24:1059–1063.

40. Luna JD, Reviglio VE, Juarez CP. Bilateral macular hemor-rhage after laser in situ keratomileusis. Graefes Arch ClinExp Ophthalmol 1999;237:611–613.

41. Perez-Santonja-JJ, Sahla HF, Alio JL. Evaluation of endo-thelial cell changes 1 year after excimer laser in situ kerato-mileusis. Arch Ophthalmol 1997;115841–846.

42. Jones SS, Azar RG, Cristol SM, et al. Effects of laser in situkeratomileusis (LASIK) on the corneal endothelium. Am JOphthalmol 1998;125:465–471.

43. Skaw EL, Rao GN, Arthur EJ, Aquavella JV. The functionreserve of corneal endothelium. Trans Am Acad Ophthal-mol Otolaryngol 1978;85:640–645.

44. Yee RW, Matsuda M, Schultz RO, Edelhauser RF. Changesin the normal corneal endothelium cellular pattern as afunction of age. Curr Eye Res 1985;4:671–677.

45. Perez-Santonja JJ, Ayala MJ, Sakla HF, et al. Retreatmentafter laser in situ keratomileusis. Ophthalmology 1999;106:21–28.

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