简介:AIM:Todescribethecharacteristicsofmodulationtransferfunction(MTF)ofanteriorcornealsurface,andobtainthethenormalreferencerangeofMTFatdifferentspatialfrequenciesandopticalzonesoftheanteriorcornealsurfaceinmyopes.·METHODS:Fourhundredeyesfrom200patientswereexaminedunderSIRIUScornealtopographysystem.PhoenisanalysissoftwarewasappliedtosimulatetheMTFcurvesofanteriorcornealsurfaceatverticalandhorizontalmeridiansatthe3,4,5,6,7mmopticalzonesofcornea.TheMTFvaluesatspatialfrequenciesof5,10,15,20,25,30,35,40,45,50,55and60cycles/degree(c/d)wereselected.·RESULTS:TheMTFcurveofanteriorcornealsurfacedecreasedrapidlyfromlowtointermediatefrequency(0-15cpd)atvariousopticalzonesofcornea,thevaluedecreasedto0slowlyathigherfrequency(>15cpd).Withtheincreaseoftheopticalzonesofcornea,MTFcurvedecreasedgradually.3)Intherangeof3mm-6mmopticalzonesofthecornea,theMTFvaluesmeasuredathorizontalmeridianweregreaterthanthecorrespondingvaluesathorizontalmeridianofeachspatialfrequency,thedifferencewasstatisticallysignificant(P<0.05).At7mmopticalzonesofcornea,theMTFvaluesmeasuredathorizontalmeridianwerelessthanthecorrespondingvaluesatverticalmeridianat10-60spatialfrequencies(cpd),andthedifferencewasstatisticallysignificantin25,30,35,40,45,50cpd(P<0.05).·CONCLUSION:MTFcanbeusedtodescribetheimagingqualityofopticalsystemsatanteriorcornealsurfaceobjectivelyindetail.
简介:AIM:Tostudythedistributionofocularhigher-orderaberrations(HOAs)andmesopicpupilsizeinindividualsscreenedforrefractivesurgery.·METHODS:OcularHOAsandmesopicpupilsizewerestudiedin2458eyesof1240patientswithmyopia,myopicastigmatismandcompoundmyopicastigmatismand215eyesof110patientswithhyperopia,hyperopicastigmatismandcompoundhyperopicastigmatismusingtheZywaveaberrometer(Busch&Lomb).Allpatientshadcorrectablerefractiveerrorswithoutahistoryofrefractivesurgeryorunderlyingdiseases.Root-mean-squarevaluesofHOAs,totalsphericalaberration,totalcomaandmesopicpupilsizewereanalyzed.OcularHOAsweremeasuredacrossa≥6.0mmpupil,andpupilsizemeasurementswereperformedunderthemesopiccondition.·RESULTS:ThemeanvaluesofHOAs,totalsphericalaberrationandtotalcomainthemyopicgroupwere0.369μm,±0.233,0.133±0.112μmand0.330±0.188μm,respectively.InthehyperopicgroupthemeanvaluesofHOAs,totalsphericalaberrationandtotalcomawere0.418μm±0.214,0.202±0.209μmand0.343±0.201μm,respectively.HyperopesshowedgreatertotalHOAs(P<0.01)andtotalsphericalaberration(P<0.01)comparedtomyopes.Inage-matchedanalysis,onlytheamountoftotalsphericalaberrationwashigherinthehyperopicgroup(P=0.05).Mesopicpupilsizeinthemyopicgroupwaslarger(P≤0.05).·CONCLUSION:TheresultssuggestedthatsignificantlevelsofHOAswerefoundinbothgroupswhichareimportantforplanningrefractivesurgeriesonIranians.Thereweresignificantlyhigherlevelsoftotalsphericalaberrationinhyperopescomparedtomyopes.Mesopicpupilsizewaslargerinmyopicgroup.