Journal of ophthalmic and Vision research 2014; Vol. 9, No. 4 427

INTRODUCTION

Limitations exist for corneal refractive surgeriessuch as laser in situ keratomileusis (LASIK) andphotorefractivekeratectomy(PRK)forcorrectionofhighmyopic refractive errors.[1,2] These limitations includebiomechanical changes and irregular cornealhealing

ComparisonofThreePhakicIntraocularLensesforCorrectionofMyopia

Farid Karimian1, MD; Alireza Baradaran‑Rafii1, MD; Seyed Javad Hashemian2, MD; Ali Hashemloo1, MD Mohammad Ebrahim Jafari2, MD; Mehdi Yaseri1,3, PhD; Elham Ghahari1, MD; Shadi Akbarian1, MS

1 Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2Department of Ophthalmology, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran

3Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran

AbstractPurpose:Tocomparethevisualoutcomesandcomplicationsofthreedifferenttypesofphakicintraocularlenses(PIOLs),forcorrectionofmoderatetohighmyopia.Methods:Wereviewed112myopiceyesundergoingPIOLimplantationusingArtisan(40eyes),Artiflex(36eyes),andimplantablecollamerlens(ICL,36eyes).Bestcorrectedvisualacuity(BCVA),intraocularpressure(IOP),pachymetry,cornealendothelialcell(CEC)loss,andhigherorderaberrations(HOA)werecompared.Results:Meanfollow‑upperiodwas30±11months.Preoperatively,sphericalequivalent(SE)refractiveerrorwas−11.6±3.7,−9.59±1.97,and−12.3±4.8DintheArtisan,ArtiflexandICLgroups,respectively.SEwascomparableamongthestudygroupsatfinal follow‑up(P=0.237).Meanastigmatic reductionwas0.31±0.72,0.45±0.62,and0.0±0.57intheArtisan,ArtiflexandICLgroups,respectively(P=0.007).Emmetropia(±1D)wasachievedin60%,91.7%and77.8%ofeyesintheArtisan,ArtiflexandICLgroups,respectively, thedifferencewassignificantbetweentheArtisanandArtiflexgroups(P=0.017).BCVAimprovementmorethanonelineoccurredin25%,19.4%and38.9%ofeyes(P=0.158);pachymetricchangeswereminimalwithnodifferenceamongthethreegroups(P=0.754),andmeanCEClosswas10±9%,9±6%and9±10%intheArtisan,ArtiflexandICLgroups,respectively(P=0.694).HOAs(P=0.039),vertical trefoil (P=0.032)andsphericalaberration(P=0.001)werehigherwithArtisangroupascomparedtoICL.Totalaberrations(P=0.028)andsphericalaberration(P=0.001)wasalsohigherwithArtisangroupascomparedtoArtiflex.Conclusion:VisualandrefractiveoutcomeswerecomparablewithArtisan,ArtiflexandICL.IntermsofHOAsandqualityofvision,ICLandArtiflexseemtobebetterchoicesinhighlymyopiceyes.

Keywords:Artiflex;Artisan;ImplantableCollamerLens;PhakicIntraocularLens

which can result in corneal thinningandpost‑LASIKectasia, less predictable results, prolonged recoverytime, refractive instability and even thepotential forvisuallossduetoinducedastigmatismorcornealulcers.On theotherhand, intraocular refractiveproceduresentailadvantagessuchastheabilitytocorrectawider

J Ophthalmic Vis Res2014;9(4):427‑433.

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DOI: 10.4103/2008‑322X.150805

Original Article

Correspondence to: FaridKarimian,MD.DepartmentofOphthalmology,LabbafinejadMedicalCenter,Boostan9, PasdaranAve.,Tehran16666,Iran. E‑mail:karimianf@yahoo.com

Received:25‑07‑2013 Accepted:13‑09‑2013

Comparison of Three Phakic IOLs; Karimian et al

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rangeofrefractiveerrors,shortervisualrecoverytimes,morestablerefractiveoutcomesandsuperiorqualityofvision.[3,4]

Comparedtootherrefractivesurgeries,implantationofphakicintraocularlenses(PIOLs)havemoredesirableresults andarepotentially reversibleproceduresdueto thepossibility of explanting these lenses.[5] These methodsusuallydonot require expensiveor specialsurgical equipment andmost ophthalmologists areabletoperformtheseprocedures;howeverdisabilitiesresulting fromPIOLs aremore severe compared tocornealrefractivesurgery.[6]

Due to the potential risk of damage to anteriorsegment structures, especially corneal endothelialcell loss, PIOL implantation is subject to debate.ComplicationsofPIOLimplantationincludeglaucoma,iridocorneal angle damage, synechiae formation,cataract, corneal decompensation, pupil ovalization,uveitisandendophthamititis.[7]

Initially angle‑supportedPIOLswere introduced;theseimplantshadlongtermcomplicationsandwerethereforesubstitutedwithiris‑fixatedPIOLswhichentailfewercomplications.Astimepassed,posteriorchamberlenses such as the implantable collamer lens (ICL)weredevelopedwhichwere better compatiblewithdelicateeyestructuresandinducedfewercomplicationssuch as cataracts.[8] Currently, three types of PIOLsincludingtheArtisan(Ophtec,Groningen,Netherlands),Artiflex(Ophtec,Groningen,Netherlands)andICL(StaarSurgical,Monrovia,CA,USA) are themostpopularPIOLsusedforcorrectionofrefractiveerrors.ThecurrentstudywasperformedtocompareArtisan,

Artiflex and ICL in terms of visual and refractiveoutcomes,qualityofvisionandcomplications,especiallychanges incornealendothelialcelldensity,aswellasintra‑andpostoperative safetyandefficacy inmyopiceyes.

METHODS

Inthishistoricalcohortstudy,allhighlymyopicpatientswhohadundergonePIOL implantation from2006 to2010atLabbafinejadMedicalCenterorRassoulAkramHospital, Tehran‑Iranwere recalled for evaluation.Basedonthe typeofPIOL, thepatientsweredividedintothreegroups:Artisan,ArtiflexandICL.Allpatientsunderwent a complete ophthalmologic examinationincludingrefraction,determinationofuncorrectedvisualacuity (UCVA), best correctedvisual acuity (BCVA),intraocularpressure (IOP)measurement,presenceofcorneal edema, corneal clarity and cataracts.Centralcorneal thickness (CCT)wasmeasured (UP‑1000Pachymeter,Nidek,Gamagori, Japan), and centralcornealendothelialcellcountwasevaluated(SpecularMicroscopeSP‑2000P,Topcon,Tokyo,Japan).Theresultswerecomparedwithcorrespondingpreoperativevalues.

Optical aberrationswere alsomeasured at the recallexamination(ZywaveIIAberrometer,BauschandLomb,TechnolasPerfectVision,Munich,Germany).Intra‑andpostoperative complications suchas inflammationorinfectionwereassessedbasedonhospitalrecords.Age at the time of operation was 21 years or

more. Exclusion criteriawere as follows:Correctedanterior chamberdepth (from the endothelium) lessthan 3mm, central endothelial celldensity less than2500/mm2, keratoconus, corneal astigmatismhigherthan2diopters(D),previouscataractsurgery,glaucoma,uveitis,andanyhistoryofsignificantretinalpathologyor detachment.All procedureswere performed bythree expert anterior segment surgeons (FK,SJHandARBR).Toreduceastigmatismbasedonpreoperativekeratometry,incisionsweremadeonthesteepcornealmeridian.TheArtisanandArtiflexLenspowerswerecalculated based on theVanderHeijd formula, asrecommendedbythemanufacturer.

Artisan LensThemyopicmodel 206was used formyopia lessthan−15.5Dandmodel204wasusedforhighermyopia.Under general anesthesia and based on the opticdiameterofthelens,anincision5.5–6.5mminlengthwasmadeonthecorneaat12o'clockpositiontogetherwith two 1.5mm stab incisions at 2 and 10 o' clockpositions.Acetylcholinewas injected intracamerallyandthentheanteriorchamberwasfilledwithsodiumhyaluronate 1% (Microvisc, Bohus, BioTechAB,Strömstad,Sweden).TheArtisanlenswasintroducedinsidetheeyethroughthe12o'clockincisionandwasrotated into horizontal position.After grasping thelensbyaspecialfixationforceps,thelenshapticswereenclavatedtothemid‑peripheralirisstromaat3and9o'clockpositions.Finally,aperipheraliridotomywasperformedat12o'clock.Theviscoelasticmaterialwaswashedout and the incisionwas suturedusing10–0nylonsuture.

Artiflex LensTheprocedurewassimilartothatoftheArtisanlens.A3.2mmclearcornealincisionat12o'clockandtwolateralstabincisionsat2and10o'clockpositionsweremade.Afterfillingtheanteriorchamberwithviscoelasticmaterial,thelenswasinsertedintotheanteriorchamberafter being loaded onto the special spatula. Afterpositioningthe lens in theproper location, itshapticswereenclavated,peripheraliridotomywasperformedandtheviscoelasticmaterialwasirrigated.

ICLType V4 ICL was employed in all subjects. Thesulcus‑to‑sulcusdiameterwasdeterminedbyultrasonic

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biomicroscopy (Sonomed, Lake Success,NY,USA)for ICL sizing. Two peripheral iridotomies usingNd‑YAGlaserwereperformed2weeksbeforesurgery.For completemydriasis, topical tropicamide 1%andphenylephrine 2.5% eye dropswere used 1 hourpreoperatively.Usinga3.2mmkeratome,oneincisionwasmadeonthetemporalsideofcorneaandanother1.0mmone at 12 o’clock position.Methylcellulosewas injected into the anterior chamber followedbyintroductionofthelens,loadedonitsspecialcartridge,intotheeye.Ablunttippedmanipulatorwasusedtoplacethelenshapticsundertheiris.Acetylcholine1%wasinjectedthereafterandtheviscoelasticmaterialwasirrigatedcompletely.Thecorneal incisionswere thenclosedbystromalhydration.Attheconclusionofallprocedures,subconjunctival

injectionof4mgbetamethasoneand100mgcephazolinwasperformed.Topical0.1%betamethasoneand0.5%ciprofloxacin(Sina‑Darou,Tehran,Iran)eyedropswereprescribedevery4hoursfor1‑weekandlaterthesteroiddropsweretaperedoffgraduallyover1‑month.We used safety and efficacy indices to consider

differencesinpreoperativeBCVAamongthe3groups;“efficacyindex”wastheratioofpostoperativeUCVAtopreoperativeBCVAand“safetyindex”wastheratioofpost‑topre‑operativeBCVA.StatisticalanalysiswasperformedusingSPSSsoftware

version17.0 (SPSS Inc.,Chicago, Il,USA). Inorder tocomparedata among the studygroups, consideringthefactthattheoperationswereperformedbilaterallyandconsideringbaselinevalues,generalizedestimatingequation (GEE)analysiswasused.Dual comparisonsusingtheBonferonimethodwasalsousedtofindthedifferencesbetweenthegroupswhenthegroupeffectwasstatisticallysignificant. P valueslessthan5%wereconsideredasstatisticallysignificant.

RESULTS

Of 74 recalledpatients, 61 (including 36 female and25male) subjectswere enrolled; a total of 112 eyesincluding40eyesintheArtisangroup,36eyesintheArtiflex group and 36 eyes in the ICL groupwereevaluatedandanalyzed.Meanagewas28±5(range,20–42) years andmean follow‑up duration was30±11(range,12–56)months.Therewerestatisticallysignificantdifferences in termsof age and follow‑upperiodamong thegroups,but thesedifferenceswerenotclinicallysignificant[Table1].

Visual AcuityMeanpreoperativeBCVAwas0.16±0.2,0.08±0.11and0.27±0.34LogMAR in theArtisan,Artiflexand ICLgroups(equivalentto20/30,20/50and20/40Snellenacuity, respectively, P = 0.037).Meanpostoperative

UCVAwas 0.22± 0.21, 0.07 ± 0.14, and 0.24± 0.25LogMAR (equivalent to 20/33, 20/22 and 20/35Snellenacuity)intheArtisan,ArtiflexandICLgroups,respectively.ThedifferencebetweentheICLgroupandtwoothersgroupswasstatisticallysignificant(P=0.039).MeanpostoperativeBCVAvalueswere 0.07± 0.13,0.02± 0.06 and 0.17± 0.25LogMAR in theArtisan,Artiflexand ICLgroups, respectively.Thedifferencebetween theArtisanand ICLgroupswas statisticallysignificant (P = 0.009). BCVAbetter than 20/40wasseen in 90%, 97.2% and 75%of eyes in theArtisan,ArtiflexandICLgroups,respectivelyandthedifferencebetween theArtiflexand ICLgroupswasstatisticallysignificant (P = 0.049). Safety andEfficacy indices inthese threegroupsare compared inTable 2 showingnosignificantdifferenceamongthethreestudygroups.The rate of at least one line improvement in

BCVApostoperativelywas75%,80.6%and61.1% intheArtisan,Artiflex and ICL groups, respectively.Also,more than one line of improvement occurredin 25%, 19.4% and 38.9% of the abovementionedgroups,respectively(P=0.158).IntheArtisangroup,3eyes(7.5%)experiencedmorethanoneSnellenlinedecrease inBCVAandone eye (2.5%)demonstratedmorethan2linesofdecreasedvision.Noneoftheeyesintheotherstudygroupsdevelopedmorethanonelineofdecreasedvision.

Refractive ErrorsNosignificantdifferencewasnotedamongthe3groupsin termsofsphericalequivalent (SE)andastigmatismpreoperatively[Table3].Aftersurgery,24eyes(60%)intheArtisangroup,33eyes(91.7%)intheArtiflexgroupand28eyes(77.8%)intheICLgroupwerewithin1Dofemmetropia.Thedifferencebetween theArtisanandArtiflexgroupswasstatisticallysignificant(P=0.017).

Table 1. Mean age and follow‑up duration in the study subgroups

Groups Artisan (1)

Artiflex (2)

ICL (3)

P

Age(year)SD±mean 27±3 30±5 27±6 0.018(1and2)

Follow‑up(month)SD±mean 29±13 31±9 29±11 0.013(2and3)

SD,standarddeviation;ICL,implantablecollamerlens

Table 2. Efficacy and safety indices among the study groups

SD±mean P*

Artisan Artiflex ICL

Efficacyindex 1.09±0.56 1.19±0.55 1.21±0.52 0.38Safetyindex 1.2±0.54 1.3±0.42 1.23±0.40 0.68*BasedonGEEanalysis.SD,standarddeviation;ICL,implantablecollamerlens;GEE,generalizedestimatingequation

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ComplicationsNosignificant complicationwasnoted in anygroupduringoraftersurgery.Nocaseofsevereuveitisleadingtoprolongationof steroidusage, fibrin formationorprecipitationonphakic lenseswas found inanyof thepatients.Twoeyes(5.6%)intheICLgroupshowedtransientIOPrisewhichwerecontrolledwithoneanti‑glaucomamedication.Nocaseofprolonged increase in IOPwasnotedinanyofthetwoothergroups.Table4showsIOPchangesinthesethreegroups.AlthoughIOPchangesintheICLgroupweresignificantlylowerthantheothergroups,thisdifferencewasclinicallynegligible.Permanent IOPchangesanddevelopmentofglaucomarequiringmedicalornon‑medicaltreatmentdidnotoccurinanygroup.

Regarding corneal complications, therewere nosignificantdifferencesinendothelialcellchanges,andcornealthicknessbetweenthethreegroups[Table5].Twoeyes(5.6%)intheICLgroupdevelopednuclear

cataracts, but thisproblemdidnot causeany changein visual acuity during the follow‑up period. Foureyes(11.1%)intheArtiflexgroupand2eyes(5%)intheArtisangroupmanifestedlocalirisatrophyatthesiteofhapticenclavationtotheiris.Twelve eyes (33.3%) in the Artiflex group, 4

eyes(10%)intheArtisangroupand2eyes(5.6%)intheICLgroupcomplainedofglarenon‑relatedtocataracts.Although, initialanalysisshowedthat thedifferenceis significant, a second evaluation considering both

Table 3. Changes in SE and astigmatism in the study groups

SD±mean Total P* Compared groups**

Adjusted P used as base valueArtisan (1) Artiflex (2) ICL (3)

SE(diopter)Presurgery −11.6±3.7 −9.59±1.97 −12.3±4.8 0.005 (2and3) 0.237Postsurgery −0.76±0.55 −0.38±0.36 −0.57±1 0.008 (2and3)Changes −10.86±3.7 −9.21±2 −11.8±4.3 0.013 (1and3)

Astigmatism(diopter)Presurgery 1.45±0.57 1.13±0.58 0.86±0.7 0.003 (1and3) 0.07Postsurgery 1.14±0.6 0.67±0.55 0.87±0.54 0.009 (1and2)Changes 0.31±0.72 0.45±0.62 0±0.57 0.008 (2and3)

*BasedonGEEanalysis;**BasedonBonferonimethod.GEE,generalizedestimatingequation;SE,sphericalequivalent;ICL,implantablecollamerlens;SD,standarddeviation

Table 4. Pre and postoperative intraocular pressure in the study groups

SD±mean Total P* Comparing couples**

Adjusted P used as a base valueArtisan (1) Artiflex (2) ICL (3)

Intraocularpressure(mmHg)Presurgery 12±3 13±2 13±2 0.007 (1and3) 0.042Postsurgery 13±2 14±2 13±2 0.317Changes −1.7±3.2 −1.1±2.2 0.4±1.7 0.001 (1and3)(2and3)

*BasedonGEEanalysis;**BasedonBonferonimethod.SD,standarddeviation;ICL,implantablecollamerlens;GEE,generalizedestimatingequation

Table 5. Changes in corneal endothelial cell counts and corneal thickness

SD±mean Total P* Adjusted P used as a base value*Artisan (1) Artiflex (2) ICL (3)

CEC(mm2)Presurgery 2825±359 2813±364 2848±325 0.926 0.694Postsurgery 2541±319 2573±366 2589±295 0.846Changes 283±276 241±176 258±279 0.703Change% 10±9 9±6 9±10 0.95

CCT(microns)Presurgery 516±44 503±41 507±32 0.58 0.754Postsurgery 521±46 506±40 510±35 0.48Changes −5±25 −3±0.13 −3±0.22 0.91Change% −1±5 0±3 0±4 0.90

*BasedonGEEanalysis.CCT,centralcornealthickness;SD,standarddeviation;ICL,implantablecollamerlens;GEE,generalizedestimatingequation;CEC,cornealendothelialcell

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eyesofeachpatientrevealedthedifferencetobenotsignificant(P=0.084).

Higher Order AberrationsTotalandhigherorderopticalaberrationsaftersurgeryforeachstudygroupareshowninTable6.Thesevaluesweremeasuredfora6mmpupil.HOA’sbetweenthreegroupswereleastinICLgroup(P=0.039).Verticaltrefoilwashighest inArtisangroupwhichcanbeexplainedby incisionposition at 12 o’clockposition. SphericalaberrationwasalsohighestinArtisangroup,whichmaybeduetodifferentcompositionofthislens(i.e.PMMA)incomparisontoothertwolenses.

DISCUSSION

Thisretrospectivecomparativestudyincluded112eyesundergoing implantationof3popular typesofPIOLsincludingArtisan,ArtiflexandICLforthecorrectionofmoderate tohighmyopia.Mean follow‑upperiodwas30monthsandmeanmyopic refractionbeforesurgerywas−11.2D.ThedegreeofmyopiawassignificantlyhigherintheICLgroupascomparedtoArtifleximplantedeyes.Thenumberofsurgeonsinthisstudywassimilarto

thestudybyCoulletetal[7]whoevaluatedtheresultsof3contributingsurgeons.Menezoetal[6] recalled all implantedcasesbetween1992and2001intheircenter,butdidnotmentionthenumberofsurgeons.Whilethecontributionof3surgeonsincreasestheexternalvalidityofthestudy,itmaydecreaseitsinternalvalidity.InaprospectivestudybyCoulletetal[7]on31patients,

the patients were followed for 12 months afterimplantationofArtisaninoneeyeandArtiflexintheothereye.Meanrefractionwas−10.3Dand−9.5DintheArtisanandArtiflexgroups,respectively.InanotherresearchMenezo et al[6] retrospectively compared theresultsofimplantationofArtisan,ICLandAdatomedPIOLs. In theArtisan and ICLgroups,meanvaluesof refractive errorwere−16.2 and−16D andmeanfollow‑upperiodwas96and18months,respectively.Ourstudyiscomparabletopreviousstudiesregardingthemagnitudeofrefractiveerrorandfollow‑upduration.

In thepresent study,BCVA improved in all threePIOL groups to a similar extent and therewas nosignificantdifferenceamongthemintermsofefficacyindex(P=0.687). Improvement invisualacuity,afterPIOLimplantationhasbeenreportedinotherstudies.[8‑10] This canbedue toneutralizationof theminificationeffect of the concave spectacle lenses inhighmyopicsubjects.[9,10]

In our study, postoperative SE within 1D ofemmetropiawas achieved in 60%, 91.7% and 77.8%of cases in the Artisan, Artiflex and ICL groups,respectively.ThedifferencewasstatisticallysignificantbetweentheArtisanandArtiflexgroups(P=0.017).Thehigher rate in theArtiflex group can bedue todifferences in surgical techniquewith these twolenses.Comparisonofvisualacuitydidnotshowanysignificant difference between the groups; in otherwords efficacy indexwas comparable (P = 0.380).ImprovementofmorethanoneSnellenlineinBCVAinallthreegroupswascomparable(P=0.158).Cornealastigmatismdecreased postoperatively in a similarmagnitude in all three groups (P = 0.07). Coulletet al[7] reported that83.9%ofeyeswithArtiflexand58%of eyeswithArtisan lenseswerewithin 1D ofemmetropiawhich are similar to findings in ourstudy.TheysuggestedthatthisoutcomeseemstobeduetothefactthatArtiflexpowercanbecalculatedwithmore accuracy and predictability. They alsobelieved that this difference cannot be explainedupondifferentincisiontechniquesforsurgery.Duetocornealcouplingeffect,changesincornealcurvatureintheincisionmeridianandtheaxisperpendiculartoitdonotleadtosignificantchangeinSEIntheirstudy,similartothepresentstudy,nostatisticallysignificantdifferencewasobservedbetweenthesafetyindicesofthese two lenses. In thepresent study, it seems thatresidualrefractionintheArtisangroupwasaresultofinadequateaccuracyoflenspowercalculationviatheformularecommendedbythemanufacturer.ThesafetyandefficacyoftoricICLtocorrectawide

range of astigmatismalongwithmyopiahave beenstudied.[9]ToricICLwasnotavailableinourregionat

Table 6. Postoperative total and higher order aberrations in the study groups

SD±mean Total P* Compared groups**

Artisan (1) Artiflex (2) ICL (3)

Generalresults 1.79±0.74 1.41±0.51 1.31±0.91 0.028 (1and2)Higherorderaberrations 0.45±0.22 0.45±0.23 0.33±0.15 0.039 (1and3)(2and3)Vertical trefoil 0.15±0.28 −0.09±0.37 0.04±0.22 0.32 (1and3)Verticalcoma −0.12±0.38 0.07±0.33 0.05±0.24 0.08 ‑Horizontalcoma 0.02±0.23 −0.07±0.18 −0.006±0.19 0.094 ‑Horizontal trefoil 0.07±0.28 0.16±0.33 0.01±0.25 0.07 ‑Sphericalaberration −0.25±0.28 0.01±0.35 0±0.19 0.001 (1and2)(1and3)*BasedonGEEanalysis;**BasedonBonferonimethod.SD,standarddeviation;ICL,implantablecollamerlens;GEE,generalizedestimatingequation

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thetimeofthestudy.Inthecurrentseries,thechangeinastigmatismwasnilintheICLgroupascomparedtothetwoothergroups.ThelengthofthemainincisionforICLwasonly3.2mm,thereforeastigmaticchangeisnegligible.Theincisionwaslongerintwoothergroupsandgreaterastigmaticchangewasexpected.Inourstudy,similartostudiesbyCoulletetal[7] and

Menezoetal[6,8]noimportantintraoperativecomplicationwasnoted.Oneofthemajor long‑termconcernsafterimplantationofPIOLs, specificallyposterior chamberlenses (i.e. ICL) is the development of cataracts.[10] In ameta‑analysis including 6,338 eyes undergoingICL implantation, the risk of developing cataractswasreportedtobeashighas9.6%.[11]Uusitolo et al[12] observed lensopacities in2.6%of ICLcases.Menezoet al[6]reportedarateof17%forcataractformationinthe ICLgroup.Theybelieved that thishigh ratewasdue tousing theV3model (Version3) in their studywhichisanoldmodel.ComparedtotheV4model,theV3ICLhadasmallervault (thedistancebetweentheICLand the anterior lens capsule) resulting inmorecontactbetweentheICLandthecrystallinelens.Onlytwoeyes(5.6%)intheICLgroupinourstudydevelopednuclearcataracts.Thislowratemaybeduetothelimitedfollow‑upperiod inour studybutmay increasewithlongerfollow‑up.Oneimportantriskfactorforcataractformationistheareaofcontactbetweentheanteriorlenscapsule and the ICL; thegreater the contact area, thehighertheriskofcataractdevelopment.[13,14]AllICLcasesinourstudyhadadequatevaultingasrecommendedbymanufacturerandnoICLwasexplantedorexchangeddue to sizemeasurement errors. This canprobablybetheotherexplanationforthe lowerrateofcataractformation.Appropriatelensvaultdecreasestheriskofcataractformation,butexcessivevaultingontheotherhandcancausecontactwiththeirispigmentepitheliumleadingtoreleaseofirispigmenttogetherwithanteriorchambershallowingandocclusionoftheiridocornealangle.Atthepresenttime,inordertopreciselychoosetheposteriorchamberPIOLdiameter,sulcus‑to‑sulcusdistancemeasurementbyultrasoundbiomicroscopyisrecommended.Intermsofcornealcomplicationssuchasdecreased

endothelialcellcountsandchangesincornealthickness,no significant differencewas observed among thestudygroupsinourseries.Attheendofthefollow‑upperiod,thelevelofdecreaseinendothelialcellcountswas10%,9%and9%in theArtisan,ArtiflexandICLgroups,respectively.Similarly,Coulletetal[7]reportedadecreaseof 9.4%and9% in endothelial cell countsfollowingArtisanandArtifleximplantationafter1‑year,respectively.Inourstudy,endothelialcellcountsinthesuperiorcornealquadrantsweresimilarintheArtisanandArtiflexgroups indicatingno significant contactbetween theArtiflex lenses and the superior cornealendotheliumwherethelensisunfoldedinsidetheeye

duringimplantation.Inaprospectivestudy,Ruhswurm et al[15]reported34casesofICLimplantation.Endothelialcell counts decreased about 7.9% and 12.9% after 2and3years,respectively.Theirrateishigherthanthecorrespondingrateinourseries.Theylinkedthishighrateofendothelialcelllosstothefirstexperiencesofthissurgeryintheircenterandtotheeffectoflearningcurveinadditiontodurationandmethodofsurgery.PIOLmayalsocausechroniclossofendothelialcellbydevelopinguveitis.ThepresenceofiristissuebetweentheICLandendotheliummaydecreasetherateofendothelialcellloss inaprotectiveway,butaccording toEdelhauseret al[16] themostacceptable theory forendothelial cellloss1–3yearsafterthesurgeryisintraoperativetraumaandsubsequentendothelialcellremodeling.SubclinicalchronicinflammationduetothePIOLitself

hasalsobeenobserved.[17,18]Ghoreishietal[18]reportedmoreflareintheanteriorchamberwithArtiflexwhichisdiscordantwithourfindings;nocaseofsubclinicalinflammation and chronicflarewasobserved in ourseriesduringfollow‑up.IOPaveragelyincreased1mmHgintheArtisanand

ArtiflexgroupswithoutanyincreaseintheICLgroup.Despitethedifferencebeingstatisticallysignificant,itisnotclinicallysignificant.Otherstudiesfoundnochangein IOPfollowingArtisan, ICLorAdatomed lenses.[6,7] Weperformedperipheral iridectomy in all patientspre‑orintraoperativelyandnocasedevelopedanacuteriseinIOP;therefore,wehighlyrecommendperipheraliridectomy.Similar toCoullet et al[7]we foundno statistically

significantdifferenceamongthestudygroupsintermsofglare(P=0.084).Toevaluatequalityofvisionafterimplantationof these 3 typesofPIOL,wemeasuredpostoperativehigherorderaberrationsandfoundthattotal higher order aberrationwas lower in the ICLgroup(P=0.039),sphericalaberrationwashigherintheArtisangroup(P=0.001),andalsoverticaltrefoilwashigherintheArtisangroup(P=0.032)ascomparedtotheotherstudygroups.Visualsystemaberrationswerenotavailablepreoperativelybutthestudygroupswerecomparableintermsofageandseverityofmyopiaandastigmatism.Therefore,postoperativecomparisonoftheaberrationsseemsappropriate.Tahzib et al[19]comparedhigherorder aberrations before and after surgery in27eyeswithArtiflexand22eyeswithArtisan.TheyconcludedthatArtiflexPIOLdecreaseswhileArtisanPIOLincreasessphericalaberrations.Theybelievedthattheseeffectsareduetodifferencesinopticaldesignofthese twoPIOLs.Also, vertical trefoilwas increasedinbothgroupswhichwas attributed to thedifferentlengthofcornealincisions.Ghoreishietal[17]comparedArtiflexwith ICL in terms of visual outcomes andcontrast sensitivity and reported comparable results.Sarver et al[5] evaluated quality of vision inmyopiceyes corrected by ICL implantation or LASIK by

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comparinghigherorder aberrationspostoperatively.They concluded that spherical aberrations and comawerelowerafterICLimplantation.Ourstudyshowedthat ICLandArtiflex implantation resulted in loweraberrationsascomparedtoArtisanPIOL.Itseemsthatmyopicpatientsbenefit frombetterqualityofvisionafterimplantationofPIOLs.We believe that the present study is the first

independent, unsponsored study comparing theresults and complicationsof implanting these threetypes of PIOL.Many of the previous studieswerefinancialsupportedbyPIOLmanufacturers,oronlycomparedtwotypesofPIOLs.Consideringthefinalvisual outcomes and complications, no obvioussuperioritywas noted among these lenses in ourstudy.TheArtisangroupshowedgreaterhigherorderaberrationsandahigherrateofproblemsregardingqualityofvisionascomparedtotheothertwogroups.Drawbacks to our study include its retrospectivenature, lack of randomization, limited number ofcases andnotmeasuringpreoperative higher orderaberrations.

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How to cite this article: Karimian F, Baradaran-Rafii A, Hashemian SJ, Hashemloo A, Jafari ME, Yaseri M, et al. Comparison of three phakic intraocular lenses for correction of myopia. J Ophthalmic Vis Res 2014;9:427-33.

Source of Support: Nil. Conflict of Interest: None declared.