Phakic Intraocular Lens Implantation for Treatment of ... - LaserMed

Phakic Intraocular Lens Implantation forTreatment of Anisometropia and Amblyopiain Children: 5-year Follow-upJorge L. Alió, MD, PhD; Bader T. Toffaha, MD; Carlos Laria, MD, PhD; David P. Piñero, PhDABSTRACTPURPOSE: To evaluate the safety and effi cacy during5-year follow-up of phakic intraocular lens (PIOL) implantationto correct high anisometropia in amblyopicchildren who were non-compliant with traditional medicaltreatment including spectacles or contact lenses.METHODS: Retrospective study of 10 eyes of 10 childrenwith high anisometropia who underwent PIOL implantation(9 with an iris-supported IOL and 1 with a posteriorchamber IOL). Patient age at the time of implantationranged from 2 to 15 years. Mean preoperative sphericalequivalent refraction was 10.146.96 diopters (D)(range: 8.00 to 18.00 D). Mean logMAR correcteddistance visual acuity (CDVA) was 0.840.52. Postoperativedata at 6, 24, and 60 months were evaluated.RESULTS: Corrected distance visual acuity improvedin all children. At 24 months, logMAR CDVA was0.390.35 and at 5 years was 0.360.38 (range forboth: 0.1 to 1.0) (P=.01). Improvement of more thanthree logMAR lines of CDVA was achieved in all childrenexcept for one (one line improvement) who was implantedwith a posterior chamber PIOL. No loss of CDVAwas detected in any patient. Five years after surgery,endothelial cell count was 2000 cells/mm 2 in eight(80%) patients; for the remaining two patients, onereported frequent eye rubbing and the other sufferedocular trauma.CONCLUSIONS: Phakic IOL implantation in childrenwith anisometropic amblyopia showed a positivelong-term impact on visual acuity. [J Refract Surg.2011;27(7):494-501.]doi:10.3928/1081597X-20110120-01Amblyopia refers to a decrease in best-correctedvisual acuity in an eye with no evident organiccause. 1 It is one of the most common causes of visualloss in childhood and is characterized by reduced spatialvision in the presence of strabismus, refractive error, or formdeprivation during the visually sensitive developmental period.Anisometropia is a difference in refractive error between thetwo eyes of an individual, which leads to a projection of unequalimages on the fovea (aniseikonia) and causes unilateralblur. If moderate to high anisometropia is left untreated, theimage of the eye providing the blurred image to the brainis suppressed and leads to the development of amblyopia.Amblyopia is directly related to the magnitude of anisometropia.1 A variety of treatments for anisometropic amblyopiahave been described, such as patching, refractive correctionwith spectacles or contact lenses, atropine penalization, andsome techniques of refractive surgery. 2-4Pediatric refractive surgery was developed with the aim offinding a solution for those cases of amblyopia where complianceis poor and/or conventional treatments are ineffective,such as high anisometropia and poor compliance due tosocial circumstances or neurobehavioral disorders. Indeed,the first studies of pediatric refractive surgery were of childrenwith neurobehavioral disorders for whom spectacles orcontact lenses were not a viable option. 5,6From Instituto Oftalmológico de Alicante, Vissum Corporation (Alió, Toffaha,Laria, Piñero); Division of Ophthalmology, Universidad Miguel Hernández(Alió, Toffaha); and Departamento de Óptica, Farmacología y Anatomía,Universidad de Alicante (Piñero), Alicante, Spain.This study has been supported in part by a grant from the Spanish Ministryof Health, Instituto Carlos III, Red Temática de Investigación Cooperativa enSalud “Patología ocular del envejecimiento, calidad visual y calidad de vida,”Subproyecto de Calidad Visual (RD07/0062).The authors have no proprietary or commercial interest in the materials presentedherein.Correspondence: Jorge L. Alió, MD, PhD, Avda de Denia s/n, Edificio Vissum,03016 Alicante, Spain. Tel: 34 90 233 3444; Fax: 34 96 516 0468; E-mail:jlalio@vissum.comReceived: July 7, 2010; Accepted: November 19, 2010Posted online: February 1, 2011494 Copyright © SLACK Incorporated

PIOL Implantation for Anisometropia in Amblyopic Children/Alió et alTwo types of pediatric refractive surgery can bedistinguished 7 : intraocular refractive surgery withintraocular lens (IOL) implantation and corneal refractivesurgery (photorefractive keratectomy andLASIK). In select cases, these types of surgery eliminateor reduce anisometropic ametropia, allowingthe correction of high myopia and astigmatism. Intraocularpediatric refractive surgery began with IOL implantationin children with congenital or traumaticcataract. Such children initially were left aphakicand were treated subsequently with contact lens wearor epikeratophakia. 8 Different models of phakic IOLs(PIOLs) implanted in children have been reported inthe literature. 2,9-15 In most of these cases, surgical refractivetreatment was used to reverse anisometropic ametropiaassociated with amblyopia, which had failedwith previous conventional treatments, and laser refractivesurgery was not possible mainly due to cornealthickness limitations. 2,10,12-15A controversy regarding the use of PIOLs in childrenis the potential development of complicationsover time (short- and long-term complications), 7 suchas cataract formation, PIOL dislocation, or endothelialcell count loss. However, the prevalence of these complicationsreported in the peer-reviewed literature islow. 2,9-15 To date, the maximum follow-up reported insuch cases is 48 months.In the current study, a series of 10 children implantedwith different PIOL models and with 60-month postoperativefollow-up is reported with the aim of analyzingthe visual changes achieved and the potential cornealand intraocular complications. All children presentedwith severe anisometropic ametropia and secondaryamblyopia that could not be reversed with spectacle orcontact lens correction and occlusion therapy.PATIENTS AND METHODSJournal of Refractive Surgery • Vol. 27, No. 7, 2011PATIENTSThis retrospective, interventional, consecutive caseseries comprised 10 children followed from early childhoodin the specialized pediatric unit of the Vissum/Instituto Oftalmológico de Alicante, Spain. A retrospectiveanalysis of the clinical histories of all childrenwith the diagnosis of anisometropic amblyopiawho underwent PIOL implantation in our clinic wasperformed. All patients fulfilled the following inclusioncriteria: refractive amblyopia, anisometropia,and unsuccessful conventional amblyopia therapyusing various combinations of spectacles, contactlenses, and occlusion therapy (contact lens intolerance,spectacle intolerance, patching therapy failure).The initial amblyopia treatment was performed by refractivecorrection and patching (occlusion) therapyfor 4 to 6 hours per day and was maintained as longas possible. Exclusion criteria for this retrospectiveanalysis were patients with anisometropic amblyopiaand PIOL implantation older than 16 years.Mean age of the eight boys and two girls includedin the study was 8 years (range: 2 to 15 years). Allcases presented with anisometropic ametropia associatedwith severe amblyopia (difference in logMARvisual acuity among eyes of five lines or more). In addition,three cases presented with strabismus (twocases of exotropia and one of esotropia). Preoperatively,mean spherical equivalent cycloplegic refraction(cyclopentolate 1%) was 9.50 diopters (D) (range:8.00 to 18.00 D). Preoperative logMAR correcteddistance visual acuity (CDVA) ranged from countingfingers to 1.0.EXAMINATION PROTOCOLPre- and postoperative clinical evaluation of all eyesincluded slit-lamp examination, intraocular pressure(IOP), uncorrected distance visual acuity (UDVA),CDVA, cycloplegic refraction, cover test, ocular motilityevaluation, corneal topography using the CornealAnalysis System (CAS; EyeSys Vision Inc, Houston,Texas), biometry (IOLMaster; Carl Zeiss Meditec, Jena,Germany), and endothelial cell count using the NoncomROBO-CA specular microscope (Konan MedicalInc, Hyogo, Japan) or the Topcon SP-3000P (TopconCorp, Tokyo, Japan). The Snellen or Pigassou visualacuity chart was used to determine preoperative visualacuity in eight children (5 years or older); two 2-yearoldchildren were evaluated by preferential lookingcharts. Retinoscopy was used in all cases for objectivepreoperative refraction; subjective refraction was determinedin the older patients. Refraction was alwaysperformed under cycloplegia. All examinations wereperformed by the pediatric and strabismus clinic consultant(C.L.) with the protocol described above.All data were recorded in a model database includingthe most relevant variables for evaluating theefficacy and safety of the treatment: UDVA, refraction,CDVA, endothelial changes, IOP, and complications.We evaluated the data at 6, 24, and 60 months afterPIOL implantation as all patients presented for followupat these time intervals. In all cases, PIOL implantationwas performed because corneal refractive surgerywas not possible due to corneal thickness limitations(myopic cases) or excimer laser limitations (hyperopiccases).Prior to surgery, all patients and their parents/guardians were informed about the procedure as wellas its risks and benefits and provided written informed495

PIOL Implantation for Anisometropia in Amblyopic Children/Alió et alconsent. The targeted postoperative refraction was emmetropiaor a certain residual power for the purpose ofisometropia with the other eye. In addition, patientsand parents were informed about this retrospectiveanalysis and signed informed consent was obtained inaccordance with the Declaration of Helsinki.SURGICAL PROCEDURENine eyes were implanted with an anterior chamber,iris-fixated PIOL (Artisan; Ophtec, Groningen, TheNetherlands) and one with a posterior chamber PIOL(PRL; CIBA Vision AG, Embrach, Switzerland). Theiris-supported PIOL was the preferred option in thesepatients to avoid the potential risk of complicationswith the angle-supported and posterior chamber PIOLs(eg, hypertension, cataract) in the immature child eye.A posterior chamber PIOL was required in one patientdue to the special anatomical features of the iris. Thepower of the IOL was calculated by the manufactureraccording to the refraction, keratometry, and anteriorchamber depth as well as the postoperative refractivetarget. No PIOL implantation was performed in anypatient with anterior chamber depth 3.0 mm.All surgeries were performed by the same experiencedsurgeon (J.L.A.). No intraoperative complicationsoccurred in any patient. The surgical procedurediffered depending on the type of PIOL implanted.ARTISAN PIOL IMPLANTATION TECHNIQUEA frown scleral tunnel incision (6.5 mm) was performed.A paracentesis was made at 3 o’clock and9 o’clock. The anterior chamber was filled with a sodiumhyaluronate high density viscoelastic. The ArtisanPIOL was implanted through the incision and rotatedand positioned in the horizontal meridian. Phakic IOLenclavation was done by the double-clamp techniqueusing specific microincision forceps. Once the PIOLwas positioned, the viscoelastic was removed, a smallperipheral iridectomy was performed, and the scleralincision was sutured with a 3-bite running nylon 10/0suture. The sutures were not removed. The 6.0-mmoptical zone Artisan PIOL was intended to be usedin all patients (largest optical zone to avoid photicphenomena). However, there were two patients inwhich the 5.0-mm model was implanted due to thelimitation in the optical zone according to the requiredPIOL power.PRL PIOL IMPLANTATION TECHNIQUEA clear corneal incision (3.0 mm) was created andthe anterior chamber was filled with viscoelastic(Healon; Abbott Medical Optics, Abbott Park, Illinois).The PIOL was loaded into the cartridge and injectedintraocularly, placing it within the posterior chamberby an iris manipulator. One milliliter of miochol chloride(CIBAVision, Claremont, California) was injectedinto the anterior chamber, and a small peripheral iridectomywas performed. The viscoelastic materialwas removed. No corneal sutures were required.POSTOPERATIVE PROTOCOLA cycloplegic agent (cyclopentolate 1%) wasprescribed to be applied twice a day for the first 5days after surgery as well as dexamethasone 0.1%drops (Maxidex; Alcon Laboratories Inc, Ft Worth,Texas) during the first 15 days. Patching occlusiontherapy was prescribed for all patients after the firstpostoperative month, once the residual refractionwas corrected by means of appropriate spectacles.The initial patching protocol was occlusion of 4 to6 hours per day and was modified according to theoutcomes.STATISTICAL ANALYSISData were collected in Excel (Microsoft Corp, Redmond,Washington) and exported to SPSS for Windows(version 15.0; SPSS Inc, Chicago, Illinios) fordata analysis. The analyzed data were CDVA, cycloplegicrefraction, endothelial cell count, keratometry,and complications. Differences between pre- and postoperativeoutcomes were analyzed using the pairedStudent t test or Wilcoxon test depending on whetherthe samples followed a normal distribution. A P value.05 was considered statistically significant. All variableswere described as meanstandard deviation(range).For an accurate statistical analysis of the visualacuity outcomes, decimal values were transformedto the logMAR scale, calculating the minus logarithmof the decimal visual acuity. 16 However, safety andefficacy indices were calculated with visual acuitydecimal values according to the standard definitionof these indices. 17 The efficacy index was calculatedas the ratio of postoperative uncorrected visual acuityto preoperative corrected visual acuity, and the safetyindex was calculated as the ratio of the postoperativecorrected visual acuity to the preoperative correctedvisual acuity.It should be noted that when reviewing the outcomesof the statistical analysis, the sample size wassmall and the power of statistical tests was limited.RESULTSMean patient age was 8 years, ranging from 2 to 15years. In all patients, occlusion therapy was appliedafter surgery. Strabismus surgery was necessary in three496 Copyright © SLACK Incorporated

PIOL Implantation for Anisometropia in Amblyopic Children/Alió et alTABLE 1Visual and Refractive Outcomes of 10 Eyes of 10 Children Implanted WithPhakic Intraocular Lens for Treatment of Anisometropic AmblyopiaSphere (D) Cylinder (D) LogMAR CDVAPatient (Age [y]) Preop 5 Years Postop Preop 5 Years Postop Preop 5 Years Postop1* (7) 10.75 2.00 2.25 3.50 0.40 0.402* (8) 9.50 2.50 2.00 3.50 1.00 0.403* (2) 18.00 0.50 0.00 1.00 2.00 1.004 (15) 11.00 1.25 2.00 1.00 1.30 1.005 (12) 9.00 1.50 1.00 0.75 0.22 0.106 (5) 8.00 2.75 0.00 1.75 1.00 0.107 (2) 12.00 1.50 0.00 2.00 0.80 0.108 (8) 16.00 0.00 0.00 0.00 0.70 0.229 (6) 8.00 3.00 3.00 3.00 0.50 0.1010 (15) 10.00 0.00 0.00 3.00 0.50 0.22CDVA = corrected distance visual acuity*Patients with associated strabismus.TABLE 2Statistical Analysis of Visual Outcomes of 10 Eyes of 10 Children Implanted WithPhakic Intraocular Lens for Treatment of Anisometropic AmblyopiaLogMAR UDVA [Snellen]Preoperative 1.100.17 (1.00 to 1.30)[20/250 (20/200 to 20/400)]6 months 0.900.46 (0.40 to 1.30)[20/160 (20/50 to 20/400)]24 months 0.610.56 (0.15 to 1.30)[20/80 (20/30 to 20/400)]60 months 0.650.49 (0.30 to 1.00)[20/80 (20/40 to 20/200)]MeanStandard Deviation (Range)UDVA = uncorrected distance visual acuity, CDVA = corrected distance visual acuityLogMAR CDVA [Snellen]0.840.52 (0.22 to 2.00)[20/120 (20/100 to 20/2000)]0.780.76 (0.10 to 1.82)[20/120 (20/25 to 20/2000)]0.390.35 (0.10 to 1.00)[20/50 (20/25 to 20/200)]0.360.38 (0.10 to 1.00)[20/30 (20/20 to 20/50)]Change in CDVA Over Time (mo)(P Value)Preop-24 (.01)Preop-6 (.35)6-24 (.27)24-60 (.99)Preop-60 (.01)patients (strabismus deviation 15 prism diopters) toachieve ortophoria and maintain binocular vision.VISUAL AND REFRACTIVE OUTCOMESTable 1 summarizes the pre- and postoperative visualand refractive outcomes. As shown, all patients experiencedvisual improvement, except one patient (no. 1)who presented with microtropia (exotropia).Table 2 summarizes the statistical analysis of thevisual outcomes achieved. Mean preoperative spherewas 9.636.94 D (range: 8.00 to 18.00 D). Cylinderranged from 0.00 to 3.00 D preoperatively andJournal of Refractive Surgery • Vol. 27, No. 7, 2011mean preoperative spherical equivalent refraction (SE)was 10.146.96 D (range: 8.00 to 18.00 D). Meanpostoperative sphere 6 months postoperatively was0.300.45 D (range: 1.00 to 0.00 D), and mean SEwas 1.300.45 D (range: 1.75 to 0.75 D). At 24months, mean sphere was 0.250.97 D (range: 1.75to 1.50 D), and SE was 1.161.03 D (range: 2.38to 0.75 D). Regarding the 60-month outcomes, meansphere was 1.061.70 D (range: 3.00 to 2.75 D)and mean cylinder was 2.171.11 D (range: 0.75 to3.00 D). The difference between preoperative and 6-month postoperative sphere and cylinder was statis-497

PIOL Implantation for Anisometropia in Amblyopic Children/Alió et alTABLE 3Endothelial Cell Count for 9 Eyes of9 Children* Implanted With PhakicIntraocular Lens for Treatment ofAnisometropic AmblyopiaEndothelial Cell Count(cells/mm 2 )Patient(Age [y])Preop5 YearsPostopEndothelialCell Loss (%)1 (7) 2245.39 2095.62 6.672 (8) 2624.72 2338.05 10.923 (2) 2423.96 2195.26 10.424 (15) 2396.90 2242.00 6.465 (12) 3165.80 2770.00 12.506 (5) 3567.00 3101.05 13.067 (2) 1832.29 1681.00 8.268 (8) 3100.00 2750.00 11.299 (6) 3100.00 2710.00 12.58Mean overall(SD)2717.34(549.92)2431.44(435.66)10.24(2.53)SD = standard deviation*Although 10 children were enrolled in the study, patient 10 was excludedfrom endothelial cell loss analysis due to ocular trauma during the postoperativefollow-up period.tically significant (P=.04), with no further significantchanges (P.23). An increase in refractive cylinder atthe end of follow-up was observed in six (60%) eyes.As shown in Table 2, statistically significant differenceswere found in logMAR CDVA between thepreoperative and 24-month postoperative values. Inaddition, a progressive improvement of CDVA wasobserved during follow-up, with the best mean valueat 60 months. Regarding UDVA, an improvement wasalso observed over time but it did not reach statisticalsignificance. A comparison between pre- and postoperativeUDVA values could not be done because preoperativevalues were not available due to the high refractiveerrors present (all patients had visual acuity ofcounting fingers).Safety and efficacy indices at 60 months postoperativewere 3.902.98 (range: 1.00 to 10.00) and1.420.82 (range: 0.83 to 2.00), respectively.POSTOPERATIVE ENDOTHELIAL CELL COUNTS ANDKERATOMETRYEndothelial cell count was 2000 cells/mm 2 inall patients 60 months after surgery, except in two(Table 3); one patient had reduced postoperative cornealendothelial cell count as a result of chronic eyerubbing due to long-standing spring catarrh allergicconjunctivitis (8.3% endothelial loss), and the otherpatient suffered an ocular trauma during the follow-upperiod (42% endothelial loss). Preoperatively, meanendothelial density was 2717.34549.92 cells/mm 2 ,whereas 60 months postoperatively, density was2431.44435.66 cells/mm 2 (P=.04). Mean endothelialcell loss was 4.256.29% (range: 1.57% to 10.92%) 2years after surgery whereas it was 10.242.53% (range:6.46% to 13.06%) 60 months after surgery. Endothelialcell count was 2000 cells/mm 2 in 90% of patientspreoperatively and at 5 years was 80% (Table 3). Thepatient who suffered ocular trauma was excluded fromthe endothelial cell loss statistics to evaluate the endothelialcell effect solely due to the PIOL implant.No significant changes in mean keratometry weredetected during follow-up (P=.69).COMPLICATIONSOne child developed acute iridocyclitis after implantation,which was detected 24 hours after surgery andresolved with steroid administration and follow-up.Otherwise, no major postoperative complications wereencountered, and the biomicroscopic appearance ofthe anterior segment at 60 months was excellent. Onepatient implanted with an Artisan lens suffered a bluntocular trauma during follow-up and it was necessaryto reposition the PIOL, resulting in residual astigmatism,coloboma of the iris, and a more significantendothelial cell loss (final endothelial count 1500cells/mm 2 ).CASES WITH LONGER FOLLOW-UPIn three patients, 84-month follow-up was completed.In these patients, postoperative UDVA andCDVA were excellent (0.850.21 [0.70 to 1.00] and0.220.25 [0.05 to 0.40] logMAR, respectively), thusmaintaining the improvement achieved in the previousvisits. Specifically, in one patient a gain of ninelines of logMAR CDVA was observed. The endothelialcell count in these three cases was 2000 cells/mm 2(endothelial cell loss was 8.67%, 20.24%, and 20.76%,respectively).DISCUSSIONTwenty percent of the general population with highrefractive errors develops visual impairment due tosevere anisometropic amblyopia. 18 Refractive surgerycan be useful in such cases for reducing the refractiveerror, creating isometropia, and then facilitating the visualrecovery with conventional amblyopic treatments.However, there is no clear consensus on pediatric refractivesurgery 19-22 and it is still considered controversial.498 Copyright © SLACK Incorporated

PIOL Implantation for Anisometropia in Amblyopic Children/Alió et alSeveral reports on this topic have been published butare limited in addressing the controversies, especiallyregarding the medium- to long-term outcomes. 2,3,5-7,9-15A number of recently published studies, some throughPediatric Eye Disease Investigator Group (PEDIG;National Eye Institute, Bethesda, Maryland) trials, havechallenged traditional thinking on the limitation of pediatricage in reversing amblyopia and gaining visualfunction in children aged 6 to 17 years. 23-27 Specifically,one PEDIG trial demonstrated that patching 2to 6 hours per day with near visual activities and atropinein amblyopic patients aged 7 to 12 years couldimprove visual acuity even if the amblyopia has beenpreviously treated. 25 However, the same authors demonstratedthat patching 2 to 6 hours per day with nearvisual activities could modestly improve visual acuityin patients aged 13 to 17 years when amblyopia has notbeen previously treated. 25When refractive surgery is considered for treating acase of anisometropic ametropia with severe amblyopia,the associated refractive error is normally high inthe affected eye (10.00 D of myopia or 6.00 D ofhyperopia). For this reason, excimer laser refractivesurgery is not possible in a great number of patientsbecause significantly large amounts of tissue ablationwould be necessary, which can lead to corneal weakeningand to an increase in corneal higher order aberrationsresulting in a decrease of visual quality. 28,29 Phakic IOLimplantation is a good option in such cases becausethese types of lenses have proven to provide excellentvisual recovery and postoperative visual quality. 30,31As stated previously, different models of IOLs havebeen successfully implanted in children with severeanisometropic amblyopia, but the concern remains regardingunforeseen long-term side effects.The postoperative functional visual results in these10 children were rewarding. As expected, better UDVAwas observed in all patients due to the effective correctionof the refractive error, although in some patientsthe target refraction was not zero. The CDVA in all10 operated eyes improved gradually over 60-monthfollow-up. One factor accounting for this visual improvementis the elimination of anisometropia, whichwas contributing to the development of amblyopia.Another factor was the application of additional treatmentssuch as patching therapy or strabismus surgery(eyes with a combined anisometropic and strabismicanisometropia) during postoperative follow-up. Ourvisual results are in concordance with those reportedpreviously for children with anisometropic amblyopiaimplanted with PIOLs. 2,9-15,32 In these previous seriesor case reports, small samples of eyes were also used,with larger samples only in the studies by LesueurJournal of Refractive Surgery • Vol. 27, No. 7, 2011and Arne 14 (11 eyes) and Tychsen et al 10 (12 eyes).The age range in these studies of PIOL implantation inchildren was also similar (3 to 16 years). A third potentialfactor for the improvement in CDVA is changein ocular magnification and higher order aberrationswith PIOL implantation. 33 Calculations performed byour group using the Kooijman eye model correctedwith spectacles and with a PIOL in high refractiveerrors proved that most of the increase in visual acuitycould be explained by the increase in magnification(a factor of 1.2) and reduction in the retinal spot size(a factor of 2). 33 Spherical refraction was reduced significantlyin all patients, which confirms the excellentcorrection potential of PIOLs, but cylinder increasedin some cases. It should be noted that the corneal incisionrequired for insertion of the angle-supported PIOLused in the current study was large, which is a factorthat could lead to unexpected astigmatic changes. 34 Infuture studies, flexible and toric angle-supported PIOLsshould be evaluated for the use in children to achievebetter control of postoperative cylinder.In the current study, the majority of patients (9 of 10)were implanted with the anterior chamber iris-fixatedArtisan lens. Iris-fixated PIOLs have been documentedto be well tolerated in the eyes of both adult 35-37 andpediatric patients with a maximum follow-up of 48months. 2,9-13 Specifically, the Artisan model seems agood option because the incidence of complications ofcataract or significant endothelial cell loss are rare 35if safety criteria are followed. Saxena et al 38 found anegative significant correlation between endothelialcell loss and anterior chamber depth. However, theuse of posterior chamber PIOLs in children seems to bemore concerning. Although the efficacy of the refractivecorrection in children with such lenses has beenconfirmed, 13,14 there is evidence of the higher risk ofcataract formation with this type of PIOL. 39,40 In thecurrent series, only one patient was implanted with aposterior chamber PIOL and no signs of cataract formationwere observed during 5-year follow-up. To thebest of our knowledge, this is the first pediatric casereported that was implanted with the PRL model ofposterior chamber PIOL. Previous reported cases wereall implanted with the Implantable Collamer Lens(ICL) posterior chamber PIOL (STAAR Surgical Co AG,Nidau, Switzerland). It should be noted that subluxationof a phakic refractive lens into the vitreous bodyhas been described and is considered the most seriouscomplication with this type of IOL. 41Regarding corneal endothelial changes, as expected, areduction in the endothelial cell density was observedin all cases. However, the values were not indicativeof the need for PIOL explantation in any patient and499

PIOL Implantation for Anisometropia in Amblyopic Children/Alió et alwere in the range of endothelial cell loss reported inadult patients 42-47 and pediatric patients 9-15 implantedwith PIOLs. One limitation of the current retrospectivestudy was the use of different instrumentation to measurethe endothelial cell count pre- and postoperatively.This could introduce some bias in the calculation ofthe endothelial cell loss. Future prospective studiesof endothelial damage in pediatric patients implantedwith PIOL are mandatory to confirm outcomes fromretrospective studies.Considering the outcomes obtained in the currentstudy, we can conclude that PIOL implantationappears to be an effective option in treating severe casesof anisometropia leading to amblyopia in children inwhom conventional treatment methods are not satisfactoryand laser refractive surgery is not possible. Abetter quality of vision compared with keratorefractivesurgery with excimer laser is achieved by implantingan anterior chamber PIOL in patients with moderateand high spherical refractive errors. 48,49 In 60-monthfollow-up as well as 84-month follow-up (three patientsonly), the complication rate in our series was very low,with no cataract formation or severe corneal endothelialcell loss requiring PIOL explantation. Few patientswere included and longer follow-up is necessary todetermine the potential longer term complications.However, our case series presents the longest followupthat has been reported to date. Regular follow-upis mandatory and eye patching therapy or strabismussurgery after PIOL implantation is crucial for achievingcomplete visual rehabilitation in these cases. Inaddition, endothelial cell density must be monitoredannually in these patients. Long-term monitoring forendothelial cell density and stability of eye alignmentfor both motor and sensory is indicated. A numberof factors, including proper amblyopia treatment followingPIOL implantation, are critical in achievingthe optimal clinical results in pediatric patients. Randomized,multicenter, prospective, clinical studies ofvarious ages would greatly enhance our understandingof the efficacy and safety of PIOL implantation in thetreatment of anisometropic ametropia in children.AUTHOR CONTRIBUTIONSStudy concept and design (J.L.A.); data collection (J.L.A., B.T.T.);analysis and interpretation of data (C.L., D.P.P.); drafting of themanuscript (B.T.T., D.P.P.); critical revision of the manuscript(J.L.A., C.L.); statistical expertise (D.P.P.); administrative, technical,or material support (J.L.A.); supervision (J.L.A., B.T.T., C.L.)REFERENCES1. von Noorden GK. Binocular Vision and Ocular Motility. 6th ed.St Louis, MO: CV Mosby; 2002.2. Chipont EM, García-Hermosa P, Alió JL. Reversal of myopic anisometropicamblyopia with phakic intraocular lens implantation.J Refract Surg. 2001;17(14):460-462.3. Alió JL, Artola A, Claramonte P, Ayala MJ, Chipont E. Photorefractivekeratectomy for pediatric myopic anisometropia.J Cataract Refract Surg. 1998;24(3):327-330.4. Alió J, Laria C. Diagnosis and treatment of amblyopia. In:Surgical and Medical Management of Pediatric Ophthalmology.New Dehli, India: Jaypee Brothers Medical Publishers Ltd;2007:855-874.5. Tychsen L, Hoekel J. Refractive surgery for high bilateral myopiain children with neurobehavioral disorders: 2. laser-assistedsubepithelial keratectomy (LASEK). J AAPOS. 2006;10(4):364-370.6. Tychsen L, Packwood E, Berdy G. Correction of large amblyopiogenicrefractive errors in children using the excimer laser.J AAPOS. 2005;9(3):224-233.7. Tychsen L. Refractive surgery for children: excimer laser,phakic intraocular lens, and clear lens extraction. Curr OpinOphthalmol. 2008;19(4):342-348.8. Uusitalo RJ, Uusitalo HM. Long-term follow-up of pediatric epikeratophakia.J Refract Surg. 1997;13(1):45-54.9. Pirouzian A, Ip KC. Anterior chamber phakic intraocular lensimplantation in children to treat severe anisometropic myopiaand amblyopia: 3-year clinical results. J Cataract Refract Surg.2010;36(9):1486-1493.10. Tychsen L, Hoekel J, Ghasia F, Yoon-Huang G. Phakic intraocularlens correction of high ametropia in children with neurobehavioraldisorders. J AAPOS. 2008;12(3):282-289.11. Assil KK, Sturm JM, Chang SH. Verisyse intraocular lens implantationin a child with anisometropic amblyopia: four-yearfollow-up. J Cataract Refract Surg. 2007;33(11):1985-1986.12. Lifshitz T, Levy J. Secondary artisan phakic intraocular lens forcorrection of progressive high myopia in a pseudophakic child.J AAPOS. 2005;9(5):497-498.13. Saxena R, van Minderhout HM, Luyten GP. Anterior chamberiris-fixated phakic intraocular lens for anisometropic amblyopia.J Cataract Refract Surg. 2003;29(4):835-838.14. Lesueur LC, Arne JL. Phakic intraocular lens to correct high myopicamblyopia in children. J Refract Surg. 2002;18(5):519-523.15. BenEzra D, Cohen E, Karshai I. Phakic posterior chamber intraocularlens for the correction of anisometropia and treatment ofamblyopia. Am J Ophthalmol. 2000;130(3):292-296.16. Holladay JT. Proper method for calculating average visual acuity.J Refract Surg. 1997;13(4):388-391.17. Waring GO III. Standard graphs for reporting refractive surgery.J Refract Surg. 2000;16(4):459-466. Erratum in J Refract Surg.2001;17(3):following table of contents.18. Chen PL, Chen JT, Tai MC, Fu JJ, Chang CC, Lu DW. Anisometropicamblyopia treated with spectacle correction alone: possiblefactors predicting success and time to start patching. Am JOphthalmol. 2007;143(1):54-60.19. Brown SM. Pediatric refractive surgery. Arch Ophthalmol.2009;127(6):807-809.20. Tychsen L. Refractive surgery for special needs children. ArchOphthalmol. 2009;127(6):810-813.21. Waring GO III. Pediatric refractive surgery review. Arch Ophthalmol.2009;127(6):814-815.22. Pirouzian A, Ip KC, Holz H. Refractive surgery in children. AmJ Ophthalmol. 2009;148(5):809-810.23. Menon V, Shailesh G, Sharma P, Saxena R. Clinical trialof patching versus atropine penalization for the treatment500 Copyright © SLACK Incorporated

PIOL Implantation for Anisometropia in Amblyopic Children/Alió et alof anisometropic amblyopia in older children. J AAPOS.2008;12(5):493-497.24. Scheiman MM, Hertle RW, Kraker RT, Beck RW, Birch EE,Felius J, Holmes JM, Kundart J, Morrison DG, Repka MX, TamkinsSM; Pediatric Eye Disease Investigator Group. Patching vsatropine to treat amblyopia in children aged 7 to 12 years: arandomized trial. Arch Ophthalmol. 2008;126(12):1634-1642.25. Scheiman MM, Hertle RW, Beck RW, Edwards AR, BirchE, Cotter SA, Crouch ER Jr, Cruz OA, Davitt BV, Donahue S,Holmes JM, Lyon DW, Repka MX, Sala NA, Silbert DI, SuhDW, Tamkins SM; Pediatric Eye Disease Investigator Group.Randomized trial of treatment of amblyopia in children aged 7to 17 years. Arch Ophthalmol. 2005;123(4):437-447.26. Pediatric Eye Disease Investigator Group. A prospective, pilotstudy of treatment of amblyopia in children 10 to