眼科学教学课件：屈光不正与弱视

Refraction

Optometry?

眼视光学屈光（refraction)TheopticalsystemoftheeyeConsistsofCorneaaqueoushumorLensvitreoushumorDiopters屈光度:Powerofrefraction

Diopters=1/focallength(m)Focallength

焦距：注视物体和眼球表面的距离focallength=0.25m，R=4Dfocallength=0.50m，R=2DF前焦点H主点n结点F’后焦点Thereducedschematiceye：

1principalplane(H)主点

1singlenodalpoint(n)结点

Simplifytheopticalsystemofeye简化眼17mm22.5mmPower=60DNearpoint:

经过眼的调节所能看清楚的最近距离。Farpoint:

无调节作用下所能看清楚的最远距离。调节范围:

远点与近点距离之差称为调节范围。调节范围

调节远点调节近点

AccomodationAccommodationTheeyechangesrefractivepowertofocusonnearobjectsbyaprocesscalledaccommodationAccommodationresultsfromchangesinthecrystallinelens.Contractionofthecilliarymuscleresultsinthickeningandincreasedcurvatureofthelens调节AccomodationPartThree

Refractiveerror

Emmetropia正视眼Reractiveerror

Myopia

Classification

按屈光成份axialmyopia

refractivemyopia

按近视程度mild

<-3.00Dmoderate-3.00D—-6.00Dsevere

>-6.00DmyopiaDegenerativeretinalchanges

inhighmyopiaMaculardegenerationPeripheralretinaldegenerationRetinaldetachment临床表现FundusofhighmyopiaCorrection

concavespherical(minus)lenses近视Hyperopia远视远点

classification

按屈光成份axial

reducedaxiallength

refractive

aphakia

按远视程度mild

<+3.00Dmoderate

+3.00D—+5.00Dsevere

>+5.00Dhyperopiacorrection凸透镜远视Astigmatism

定义：在调节静止时，平行光线经过眼屈光系统后，在不同的子午线上屈光力不同，形成前后两条（不能在网膜上形成焦点）焦线，称为散光。

Regularastigmatism最大屈光力和最小屈光力主子午线相互垂直

病因：

角膜、晶体各经线曲率半径不同。

规则性不规则性单纯近视散光单纯远视散光复性近视散光复性远视散光混合性散光圆锥角膜角膜斑翳多发性角膜异物分类散光

Cylindricallenses柱镜矫正。CombinedwithsphericallensesCorrection散光Anisometropia

Differenceinrefractiveerrorbetweenthetwoeyes

Thedifferencebetweentwoeyesismorethan2.50D

RefractivecorrectionDifferenceinsizeoftheretinalimageSpectaclecorrection:<2.75DContactlenscorrection:≥3DPresbyopia

Thelossofaccommodationthatcomeswithaginginallpeople.。

Inabilitytoreadsmallprintordiscriminatefinecloseobjects老视Ataboutage44-46+1.50D；

age50

+2.00D；

age60+3.00Dcorrection：pluslens，bifocallens,progressivemultifocallensMethodsofrefraction

一、Objectiverefraction客观验光法

二、Subjectiverefraction主觉验光法

三、cycloplegicrefraction

CorrectionofrefractiveerrorsA.Spectaclelenses

B.Contactlenses

Softcontactlensesragidgas-permeablecontactlens,RGPorthokeratology

C.keratorefractivesurgery角膜屈光手术RK:PRK（屈光性角膜切削术）LASIK（准分子激光角膜原位磨镶术）LASEK（准分子激光上皮瓣下角膜磨镶术）：EPI-LASIK飞秒IntraocularlensesPHACO+IOL,ICL巩膜屈光手术后巩膜加固术Amblyopia

Binocularvisualdevelopmentoccursinthebrain(nottheeyes)Amblyopia:DefinitionAbnormalvisualdevelopmentTypicallyonlycentralacuityisdecreasedUnilateralorbilateralDecreasedvisualacuityevenwhenallothereyeproblemshavebeencorrectedSeveritymild

visualacuity0.6-0.8moderate

visualacuity0.2-0.5severe

visualacuity≤0.1BinocularvisualdevelopmentTypesofproblemsNoimageBlurryimageConfusingimageTypesStrabismusAnisometropiaRefractiveerrorFormdeprivation弱视Amblyopia:CausesCause#1:Noimage“Formdeprivation”Visualimagecan’tgettotheretinaWilliamN.Clarke,MDAmblyopia:CausesCause#2:BlurryimageRefractiveerror=patientneedsglasses!UnequalrefractiveerrorsarepoorlytoleratedEqualrefractiveerrorsarebettertoleratedWilliamN.Clarke,MDAmblyopia:CausesCause#3:‘Confusingimage’PooraimTomakesenseofthevisualworld,theimagesfromeacheyemustmatchupAmblyopia:CausesCause#3:‘Confusingimage’TheimagesdonotmatchupwhentheeyesaremisalignedAmblyopia:CausesCause#3:‘Confusingimage’Misalignmentoftheeyes=strabismusAmblyopia:CausesCause#3:‘Confusingimage’=StrabismusThebrainignoresvisualinputfromoneeyeAmblyopia:SignificancePrevalence2-4%UsuallyunilateralMostcommoncauseofunilateralvisuallossinchildhoodSeverebilateralamblyopia=blindnessAmblyopiaScreening:ImportanceAlmostalwayspreventable/treatableEarlydetectioniskeyLife-treateningdisordersmaypresentasamblyopiaAmblyopiaTreatmentClearingthemediaTheimportanceofearlydetectionandtreatmentcannotbeoveremphasizedTimelyreferralisthekey!AmblyopiaTreatmentFocusingtheimageAllpediatricpatientsrequireacycloplegicrefractiontoaccuratelydeterminerefractiveerrorAmblyopiaTreatment“Penalization”of