眼科文献--PENTACAM眼前节参数测量

AnteriorchamberparametersmeasuredbythePentacamCESafteruneventful

phacoemulsificationinnormotensiveeyes

zlenenO.Uczkan2andAyferKanpolat1Oakhan,1MuhipO

1DepartmentofOphthalmology,FacultyofMedicine,AnkaraUniversity,Ankara,Turkey2DepartmentofBiometryandGeneticAnimalHusbandry,UniversityofAnkara,Ankara,Turkey

ABSTRACT.

Purpose:Wesetouttoquantifychangesintheanteriorchambervolume(ACV),anteriorchamberdepth(ACD)andanteriorchamberangle(ACA)measurementsobtainedbythePentacamrotatingScheimpflugcamerafollowinguneventfulphacoemulsificationsurgeryinnormotensiveeyeswithopeniridocornealangles.Methods:Weenrolled44eyesof44consecutivepatientsundergoingcataractextractioninthisprospectivestudy.Patientswithahistoryofglaucoma,angle-closureglaucomaoranyotherconcurrentoculardiseasewereexcluded.Adetailedeyeexaminationincludingintraocularpressure(IOP)measurementwasperformedandACV,ACDandinferior,superior,temporalandnasalACAmea-surementswereobtainedineachpatienteyeusingthePentacamComprehensiveEyeScanner(PentacamCES)beforeand3monthsafterphacoemulsificationandintraocularlens(IOL)implantationwithtemporalclearcornealincision.Datawerecomparedusingpairedt-testandone-wayanova.

Results:MeanpreoperativeACV,ACD,ACAandIOPmeasurementswere1.7±49.8mm3,3.0±0.8mm,35.7±10.2°and15.8±3.7mmHg,respec-tively.Threemonthspostoperatively,meanACV,ACD,ACAandIOPmeasure-mentswere200.9±33.3mm3,3.9±0.9mm,41.5±6.5°and13.2±3.9mmHg,respectively.PostoperativemeanACV,ACDandACAvaluesinallfourquadrantsweresignificantlyincreased(p<0.0001,p<0.0001,p<0.0001,respectively),whereasIOPwassignificantlyreduced(p<0.0001).Conclusions:ThePentacamCESallowedveryeasy,fast,automaticandnon-contactquantificationoftheanteriorchamberparameterspre-andpostopera-tivelyinallpatienteyes.Measurementsobtainedconfirmthatinnormotensiveeyeswithopeniridocornealangles,theACVandACDincreaseandtheACAwidensinallquadrants3monthsafteruneventfulphacoemulsificationandIOLimplantation.ThesechangesareaccompaniedbyasignificantfallinIOPintheshortterm.

Keywords:anteriorchamber–cornealtopography–diagnosticimaging–intraocularpressure–iridocornealangle–phacoemulsification

Introduction

Althoughcataractsurgeryandintra-ocularlens(IOL)implantationleadtoclinicallyevidentdeepeningoftheanteriorchamberandwideningoftheiridocornealangle,quantificationofthesechangeshasbeenlimitedbytheavailabilityofinstrumentsandmeth-odswithwhichtoassessthem.

Traditionalevaluationoftheante-riorchamberangle(ACA)bytheShaf-fer,SheieorHerickmethodsdependsonsubjectiveassessment.ApplanationorimmersionA-scanultrasoundhasshownconsiderablevariabilitybetweenmeasurements(Giers&Epple1990),betweenobservers(Norrby2001)andbetweenmanufacturers(Norrbyetal.2003),primarilyasaresultofapplana-tioneffectsandmisalignmentofthehand-heldprobe.MoreaccurateandquantitativeevaluationoftheACAoranteriorchamberdepth(ACD)withbetterresolutionhasbeenmadepossi-blebytheuseofultrasoundbiomicro-scopy(UBM).TheresolutionofUBMismuchhigherthanthatofconventionalultrasound.However,althoughintraobserverreproducibilityofitsquantitativemeasurementswerereportedtobegood,interobserverreproducibilitywaspoorandobserverexperiencewasreportedtoinfluencethemeasurements(Telloetal.1994;Kurimotoetal.1997;Spaethetal.1997;Urbaketal.1998).

ActaOphthalmol.2009:87:4–8

ª2008TheAuthors

Journalcompilationª2008ActaOphthalmol

doi:10.1111/j.1755-3768.2008.01305.x

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Postop/preop ACVRelativelynewnon-contactmethodsrecentlyreportedtoprovideaccurate,repeatableandcomparableACDmea-surementsincludeopticalmethodssuchastheOrbscan(Bausch&Lomb,Rochester,NY,USA)(Lackneretal.2005;Rabsilberetal.2006),thePen-tacamComprehensiveEyeScanner(PentacamCES;OculusGmbH,Wetzlar,Germany)(Lackneretal.2005;Rabsilberetal.2006),partialcoherenceinterferometrymethodssuchastheIOLMaster(ZeissMedi-tec,Inc.,Dublin,CA,USA)(Buehletal.2006;Olsen2007)andopticalcoherencetomography(OCT)technol-ogy(Altanetal.2004;Wirbelaueretal.2005;Kalev-Landoyetal.2007).PreviousstudiesusingA-scanultra-sonographyorUBMhaveshownthatphacoemulsificationwithorwithoutIOLimplantationresultsinwideningoftheACAanddeepeningoftheanteriorchamberinbothnormalandglaucomatouseyes(Kurimotoetal.1997;Pereira&Cronemberger2003;Altanetal.2004;Nonakaetal.2006).Furthermore,thesechangeshavebeenreportedtobeaccompaniedbysignifi-cantdecreasesinintraocularpressure(IOP)intheseeyes(Altanetal.2004).Scheimpflugvideophotography(EAS-1000;NidekInc.,Gamagori,Japan)hasalsobeenusedtoevaluatetheanteriorchamberangleandwidthfol-lowingcataractsurgery;however,thissystemrequiresquantitativemeasure-mentstobemademanuallyandcanbetime-consuming(Yang&Hung1997;Hayashietal.2000).

ThepurposeofthisstudywastoinvestigatetheuseofthePentacamrotatingScheimpflugcamerainthequantificationofanteriorchamberparametersfollowinguneventfulphac-oemulsificationsurgeryinnormo-tensiveeyeswithopeniridocornealangles.

ThestudyprotocoladheredtothetenetsoftheDeclarationofHelsinki.Informedconsentwasobtainedfromeachpatientpriortoanyprocedures.Beforesurgery,uncorrectedandbestspectacle-correctedvisualacuity(VA)wasmeasured,followedbyslit-lampexamination,PentacamCES(OculusGmbH),IOPmeasurement(Goldmannapplanationtonometry)andfunduscopy.

PentacamCESmeasurementwasperformedwiththepatientseatedusingachinrestandforeheadstrap.Allmeasurementswereperformedinaroomwithastandarddimillumina-tion.Thepatientwasaskedtofixateonablackfixationtargetoverabluebackgroundillumination.ThePenta-camCESsystemusesarotatingSche-impflugcameraandamonochromaticslit-lightsourcethattogetherrotate360°aroundtheopticalaxisoftheeye.Thesystemthusacquires25or50imagesoftheanteriorsegmentoftheeyein2secondsandthesoftwareenablesevaluationandquantificationofanteriorandposteriorcornealele-vationdata,cornealthickness,ante-riorchambervolume(ACV),ACD(notincludingthecornealthickness),ACAandlensvolumeandopacityfromtheacquiredimages.Inthisstudy,thesystemwassettoacquire25imagesperscanattheautomaticreleasemode(imagescapturedauto-matically)andsoftwareVersion1.16wasused.Threemeasurementswereobtainedineachpatienteyeandthebestwasusedinquantitativeanalysis.FortheACAevaluation,thevalueautomaticallyderivedbythesoftwarefromall25imagesacquiredineachpatienteyewasnoted.Additionally,

Table1.Meanpre-andpostoperativeanteriorchamberandiridocornealangleparameters.

Preoperativeratio

ACV(mm3)ACD(mm)ACA(°)Temporal(°)Nasal(°)Superior(°)Inferior(°)

1.73.035.733.035.332.336.3

±±±±±±±49.80.810.28.38.78.79.5

Postoperativedifference200.93.941.539.942.437.3.8

±±±±±±±33.3*0.9*6.5*7.1*7.9*7.6*6.1*

Postoperative:preoperative1.3001.3401.2301.2601.2301.1901.270

±±±±±±±0.3410.3630.3500.3030.2090.1960.310

Postoperative–preoperative36.2000.8705.7606.9107.1405.1807.480

*Statisticallysignificant(p<0.05,pairedt-test).

ACV=anteriorchambervolume;ACD=anteriorchamberdepth;ACA=anteriorchamberangle.

2.52.01.5MaterialsandMethods

Atotalof44eyesof44consecutivepatientsundergoingcataractextractionwereenrolledinthisprospectivestudy.Patientswithglaucoma,pseudo-exfoliationsyndrome,historyofangleclosure,anypreviousocularsurgery,oranypreviousorconcurrentoculardis-easewereexcluded.Whenbotheyesofonepatientunderwentsurgery,thefirstoperatedeyewasincludedinthestudy.

1.00.5050100150Preop ACV200250300r = –0.8103. p = 0.0000009Fig.1.Anteriorchambervolume(ACV):correlationbetweenpreoperativevaluesandpostoper-ative:preoperativeratios.5

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theACAsatthesiteoftheincision(temporal),oppositetheincision(nasal),superiorlyandinferiorlywererecordedbyviewingtheimagesanddataobtainedatthosespecificloca-tions.TheACVandACDmeasure-mentswerecalculatedautomaticallyfromthe25imagesobtainedbythesoftware.TheACDmeasurementsobtainedbythePentacamsystemdonotincludecornealthicknessandaremeasuredfromtheendotheliumtotheanteriorcrystallineorIOLsurface.Pre-andpostoperativeACV,ACDandACAdatawerecomparedusingpairedt-test.

TodeterminewhetherthechangeinACVwasdependentonthecorre-spondingpreoperativevalues,wetookthemeanofthepreoperativeACVmeasurements,andcategorizedtheeyesasthosewithpreoperativeACVlessthanthemeanvalue(subgroupACV1)andthosewithpreoperativeACVmorethanthemeanvalue(ACV2).ThenweinvestigatedwhetherthepostoperativeincreaseintheACVofsubgroupACV1wassignificantlymorethanthatofsubgroupACV2.WerepeatedthesameanalysisforACDandACAvaluesandanalysedthesedatabyone-wayanova.

Allsurgerieswereperformedbyone

OU)undertopicalanaes-surgeon(O

thesia,usingatemporalclearcornealincision.Acapsulorhexissizeof6mmwasensuredbyacalliperduringeachsurgery.Trypanbluewasutilizedinmaturecataractswhenneeded.Fol-lowingcorticalcleavinghydrodissec-tion,thenucleuswasemulsifiedusingthekaratechoptechnique,corticalclean-upwasperformed,andathree-piecefoldablehydrophobicacrylicIOLwitha6-mmopticand13-mmtotaldiameter(Sensar;AdvancedMedicalOptics,Inc.,SantaAna,CA,USA)wasinserted.Theincisionwasclosedwithstromalhydration.

Postoperatively,patientswerepre-scribedtopicalantibioticsandsteroidsfourtimesdailyfor2weeksandnon-steroidanti-inflammatorydropstwicedailyforamonth.

Patientswerere-examinedatpost-operativemonth3,whenallmeasure-mentswererepeated.

ThemeanpowerofIOLusedduringsurgerieswas22.6±1.1D.Table1showsthemeanACV,ACD,ACAandIOPmeasurementstakenbythePentacamCESpreoperativelyandatpostoperativemonth3.

ThemeanpostoperativeACV,ACDandACAwerestatisticallysig-nificantlyincreasedwhencomparedwithcorrespondingpreoperativeval-ues(p<0.0001,p<0.0001,p=0.003,respectively,pairedt-test).MeanpostoperativeACAvaluesmea-suredseparatelyattheincisionsite(temporal),nasally,superiorlyandinferiorlywerealsosignificantlyincreasedcomparedwithpreoperativevalues(p<0.0001,pairedt-test)(Table1).

Thelowerthechambervolume,theshallowertheanteriorchamberorthechamberanglepreoperatively,themoresignificantweretheincreasesintheACV,ACDorACApostopera-

2.52.0Postop/preop ACD1.51.00.50.01234r = –0.4907. p = 0.0127Preop ACDFig.2.Anteriorchamberdepth(ACD):correlationbetweenpreoperativevaluesandpostopera-tive:preoperativeratios.3.02.5Postop/preop ACA2.01.51.00.50.001020Results

Themeanageofthepatientswas65.8±8.3years(range50–81years).

3040Preop ACA506070r = –0.7618. p = 0.000010Fig.3.Anteriorchamberangle(ACA):correlationbetweenpreoperativevaluesandpostopera-tive:preoperativeratios.6

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tively(p=0.006,p=0.043,p=0.001,respectively,one-wayanova)(Figs1–3).Similarly,thewiden-ingofthetemporal,nasal,superiororinferioranglewidthwasmoresignifi-cantineyeswithshallowerpreopera-tivecorrespondingangles(p=0.014,p=0.041,p=0.028,p=0.042,res-pectively,one-wayanova).

MeanIOPwas15.8±3.7mmHgatthepreoperativeexaminationand13.2±3.9mmHgatpostoperativemonth3.Thisdifferencewasstatisti-callysignificant(p<0.0001,pairedt-test).

Discussion

ThePentacamisaneasy-to-use,non-contactbiometrysystemthatusesaScheimpflugrotatingcamerafortheanalysisoftheanteriorsegment.Themeasurementstakenbythesystemarefastanduser-independent.Recently,Pentacamhasbeenreportedtocalcu-lateACDwithameanstandarddevi-ationof20lminhealthyeyes(Rabsilberetal.2006).Previously,anotherScheimpflugvideophoto-graphysystem(EAS-1000)wasusedtoevaluateACAchangesfollowingcataractsurgery,butitrequiredthatquantitativemeasurementsbemademanually(Hayashietal.2000).Toourknowledge,thisisthefirststudytoevaluatethechangesinanteriorchamberparametersfollowingphaco-emulsificationsurgeryusingthePenta-camCESsystem.

Wedemonstratedsignificantdeep-eningoftheanteriorchamberandopeningoftheiridocornealangleinallfourquadrants(temporal,nasal,superiorandinferior),witharesultantincreaseinACVat3monthsaftersurgery.MeanACVincreased1.22times;meanACDincreased1.34times,andmeanACAincreased1.23times.Aswellasquantitativelydocu-mentingthewideningoftheiridocor-nealangle,wealsonotedanobviousbackwardshiftoftheirisintheSche-impflugimages,especiallyineyeswithveryshallowanteriorchambers(Fig.4).

MarkedanteriorchamberchangeshavebeenreportedfollowingcataractsurgerywithphacoemulsificationandfoldableIOLimplantation,usingA-scanultrasonography,UBMandScheimpflugphotography(Kurimotoetal.1997;Hayashietal.2000;Pere-

Fig.4.PentacamScheimpflugphotographyshowingthequalitativeandquantitativechangesintheanteriorchamberconfigurationinducedbycataractsurgeryinonepatienteye.Inthiscase,theanteriorchambervolume,depthandmeananteriorchamberanglewere,respectively,176mm3,2.97mmand41.2°preoperatively,and224mm3,4.92mmand53.9°postopera-tively.

ira&Cronemberger2003;Altanetal.2004;Nonakaetal.2006).UsingUBM,Kurimotoetal.(1997)reportedthattheanteriorchamberwas1.37timesdeeperandthetempo-ralanteriorchamberanglewas1.57timeswiderat3monthsaftersurgery.InanotherUBMstudy,Pereira&Cronemberger(2003)reportedtheACDtoincrease1.31timesandtheangletowiden1.26,1.53,1.36and1.52timestemporally,nasally,superi-orlyandinferiorly,respectively.Boththelatterstudiesattributedtheante-riorchamberchangestoabackwardshiftoftheiriswithapproximately10°angularmovementaftercrystal-linelensremoval,andthereliefofpossibleaccompanyingrelativepupil-laryblockineyeswithashallowante-riorchamber.TheScheimpflugvideophotographysystem(EAS-1000)Hayashietal.(2000)demonstratedthatACAandACDatthevertical

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axisincreasedsignificantlyafterphac-oemulsificationandIOLimplantationineyeswithangle-closureglaucoma(ACG),open-angleglaucoma(OAG)andinnormaleyes.

Theresultsofourstudywerecom-parablewiththoseoftheaforemen-tionedstudies.LikeKurimotoetal.(1997),wewereabletodemonstratesignificantcorrelationbetweenpre-operativevaluesandpostoperativechanges:theshallowerthepreopera-tiveanteriorchamber,thedeeperitbecamepostoperatively,andthenar-rowerthepreoperativeangle,thewideritbecamepostoperativelyatanyofthefourquadrantsmeasured.

Documentedchangesinanteriorchamberparametersfollowingphaco-emulsificationandfoldableIOLimplantationhavebeenreportedtobeaccompaniedbysignificantdecreasesinIOPinseveralstudiesinbothnor-motensiveeyes(Cekicetal.1998;Hayashietal.2000)andineyeswithOAG(Hayashietal.2000)orACG(Cekicetal.1998;Hayashietal.2000).Asinthesestudies,meanIOPmeasuredatpostoperativemonth3inourstudywassignificantlylowercom-paredwiththemeanpreoperativemeasurement.Hayashietal.(2000)attributedthisIOP-reducingeffecttothewideningoftheACA.AsACGisconsideredtobetheresultofanabnormalconfigurationoftheante-riorsegmentandangle,ithasbeenproposedthatcataractsurgerymayimproveIOPpermanentlyineyeswithnarrowangles,whereas,inOAGeyes,inwhichtheoutflowsystemiscom-promised,theIOP-loweringeffectmaybetransient.

LimitationsofthePentacamCESScheimpflugtechniqueforACAimag-ingincludelight-scatteringattheangleregion,whichmayleadtoreducedvisualizationoftheanglestructuresandthereforemightincreasetheriskofmeasurementerrors.Furtherrefine-mentsininstrumentationmayimprovesuchlimitations.

Inconclusion,thepresentstudyperformedwiththePentacamrotatingScheimpflugcamerasystemconfirmedthatinnormotensiveeyeswithopeniridocornealangles,theACVandACDincreaseandtheACAwidensin

allquadrantsfollowinguneventfulphacoemulsificationandIOLimplan-tation.Thesechangesareaccompa-niedbyasignificantfallinIOP3monthspostoperatively.ThePenta-camCESallowedtheveryeasy,fast,automaticandnon-contactquantifica-tionofanteriorchamberparameterspre-andpostoperativelyinallpatienteyes.

Acknowledgements

ThisstudywassupportedbyagrantfromAnkaraUniversity,Ankara,Turkey.

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ReceivedonNovember9th,2007.AcceptedonMarch21st,2008.Correspondence:mu.UcOakhanMDrO

DepartmentofOphthalmology

AnkaraUniversityFacultyofMedicineMamakCaddesi

Cebeci06100AnkaraTurkey

Tel:+903124480141Fax:+903124673044Email:omuru@yahoo.com

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