眼科学教学课件：眼视光学

眼视光学Optometry

andOphthalmology

眼的屈光和调节OcularRefractionandaccommodation

BasicconceptofrefractionEssentialcharacteroflight:ElectromagneticwaveAbsorbreflectionrefraction

Thecontents:BasicconceptofrefractionTheturningorbendingofanywave,suchasalightorsoundwave,whenitpassesfromonemediumintoanotherofdifferentdensity.Thecontents:OcularrefractionTheabilityoftheeyetobendlightsothatanimageisfocusedontheretina.Thecontents:FocallengthThedistancefromthesurfaceofalensormirrortoitsfocalpoint.Thecontents:Diopter(D)Thediopterisameasureoflenspowerderivedfromthealgebraicmethodofopticalcalculations.Itisdefinedasthereciprocalofthefocallengthofalensinairmeasuredinmeters.D=1/f(m)orD=100/f(cm)InordertoanalyzetheImageandCalculationofeyeconveniently,weusuallyuseGullstrandsimplifiedeye

(orschematiceyeofGullstrand).

GullstrandsimplifiedeyeInthereducedschematiceye,thecorneaisassumedtobetheonlyrefractingsurface,theprincipalplane(H)beingplacedatitsapexandasinglenodalpoint(n)atitscenterofcurvature.

GullstrandsimplifiedeyeTheglobehasanaxiallengthof22.5mm,andtherefractiveindexoftheeyeissaidtobe1.33.

GullstrandsimplifiedeyeTheprimaryfocalpoint(F)isthatpointalongtheopticalaxiswhereanobjectmustbeplacedtoformanimageatinfinity.GullstrandsimplifiedeyeThesecondaryfocalpoint(F’)isthatpointalongtheopticalaxiswhereparallelincidentraysarebroughttoafocus.FFOcularrefractionRefractivesystemofeyeCornea43DaqueoushumorLens19DVitreousbodyTotalrefractivepowerofeye58.64D70.57D

OcularaccommodationAccommodation

Theeyechangesrefractivepowertofocusonnearobjectsbyaprocesscalledaccommodation.

Studyhasshownthataccommodationresultsfromchangesinthecrystallinelens.Contractionoftheciliarymuscleresultinthickeningandincreasedcurvatureofthelens,probablyduetorelaxationofthelenscapsule.

ThemechanismofaccommodationAccommdatelensUnaccommdatelensAge(years)Meanaccommodation(Diopters)813.8259.9357.3405.8453.6501.9551.3Refractiveerror

EmmetropiaAbsenceofrefractiveerrorAmetropiaPresenceofrefractiveerrorClassificationMyopia(shortsight)Hyperopia(longsight)AstigmatismAnisometropia

Myopia

Definition:theimageofdistantobjectsfocusesinfrontoftheretinaintheunaccommodatedeye.

ClassificationAccordingtokindofrefraction

axial(>95%)Iftheeyeislongerthanaverage,theerroriscalledaxialmyopia

RefractiveIftherefractiveelementsaremorerefractivethanaverage,theerroriscalledrefractivemyopia

ClassificationofmyopiaAccordingtodiopter

lower<–3.00Dmiddle–3.00D~-6.00Dhigh>–6.00D

Clinicalmanifestationsvision:distanceisblurednearvisionisclear

DistanceisbluredClearnearvisionHyperopiaDefinition:hyperopiaisthestateinwhichtheunaccommodatedeyewouldfocustheimagebehindtheretina.ClassificationAccordingtodiopter

lower<+3.00Dmiddle+3.00D~+5.00Dhigh>+5.00D

HyperopiaClinicalmanifestations

Ifhyperopiaisnottoogreat,a

young

personmayobtainbothasharpdistantimageandasharpnearimagebyaccommodating.However,theamountdecreaseswithageaspresbyopia(decreaseinabilitytoaccommodate)increases.

HyperopiaClinicalmanifestationsDependonthe

degree

(diopter)

ofhyperopiaand

ageVision:

threestates

normal/normalnormal/abnormalabnormal/abnormalHyperopiamanifestationsAccommodativeesotropiaThereisareflexcorrelationbetweenaccommodationandconvergenceoftwoeyes,thereforehyperopiaisafrequentcauseofesotropiaAmblyopiaAheadofpresbyopiaAstigmatismDefinition:Inastigmatism,theeyeproducesanimagewithmultiplefocalpointorlines.AstigmatismClassificationIrregularAstigmatismwiththeruleRegularAstigmatismagainsttheruleObliqueastigmatism

AstigmatismManifestationsvisionofastigmatism

Normal(slightastigmatism)Poorvision(markedastigmatism)

forbothdistanceandnearAmblyopia

AnisometropiaDefinitionAnisometropiaisadifferenceinrefractiveerrorbetweenthetwoeyes

If>2.5D

BlurFusiondifficultNosinglebinocularvisionAmblyopia

PresbyopiaDefinitionThelossofaccommodationthatcomeswithagingtoallpeopleiscalledpresbyopia.(Old-age-sight)ManifestationsThenearvisionbecomesprogressivelyworseCorrectionofpresbyopiaFirst:correctionofrefractiveerrorSecond:theglassesfornearsight

CorrectionofametropiaTheprincipleofcorrectionSufficientcomfortable

GlassesMyopia:

concavelensHyperopia:

convexlensAstigmatism:cylindricallensCorrectionofametropiaContactlens

SoftlensHardlens

Beacauseusingcontactlenshasalatentriskofinfection,weusuallyrecommendglassesinsteadofcontactlens.Usingcontactlenscanreducethedifferenceinimagesize,sowesuggestanisometropicpatienttousecontactlensCorrectionofametropiaIntraocularLensImplantationofanintraocularlenshasbecomethepreferredmethodofrefractivecorrectionforaphakiaCorrectionofametropiakeratorefractivesurgery

RK(radialkeratotomy)

PRK(photorefractivekeratectomy)

LASIK(laserinsitukeratomileusis)Allkindsofkeratorefractivesurgeryencompassesarangeofmethodsforchangingthecurvatureoftheanteriorsurfaceoftheeyes

Amblyopia

弱

视Amblyopia

ThewordcomesfromtheGreek[ambly-(dull)+-opia(vision)].Amblyopiaisoftenreferredtoas"lazyeye."AmblyopiaDefinitionAmblyopiaisimpairedfovealvisionintheabsenceoforganicdiseaseandismostlikelytheresultoflackofcontin-uoususeofoneorbothfoveasforvisualfixation.AmblyopiaNewborninfantsareabletosee,butastheyusetheireyesduringthefirstmonthsoflife,visionimproves.Duringearlychildhoodyears,thevisualsystemchangesquicklyandvisioncontinuestodevelop.

AmblyopiaIfachildcannotusehisorhereyesnormally,visiondoesnotdevelopproperlyandmayevendecrease.Afterthefirst9~11yearsoflife,thevisualsystemisnormallyfullydevelopedandusuallycannotbechanged.Amblyopia

Ifcaughtearly,theproblemcanoftenbecorrectedandthevisionpreserved.

However,afteraboutage11,itisdifficultifnotimpossibletotrainthebraintousetheeyenormally.

AmblyopiaEtiologyStrabismus(misalignedeyes)

UnequalFocus/RefractiveError

CloudinessinthenormallyclearEyetissues

EtiologyAmblyopiaoccursmostcommonlywithmisalignedorcrossedeyes.Thecrossedeye"turnsoff"toavoiddoublevision,andthechildusesonlythebettereye.Themisalignedeyethenfailstodevelopgoodvision.EtiologyRefractiveerrorsareeyeconditionsthatarecorrectedbywearingglasses.Amblyopiaoccurswhenoneeyeisoutoffocusbecauseitismorenearsighted,farsightedorastigmaticthantheother.EtiologyTheunfocused(blurred)eye"turnsoff"andbecomesamblyopic.Theeyescanlooknormal,butoneeyehaspoorvision.Thisisthemostdifficulttypeofamblyopiatodetectsincethechildappearstohavenormalvisionwhenbotheyesareopen.

EtiologyAmblyopiaalsocanoccurinbotheyesifbotheyesareveryblurred.Thiscanhappenwhenthereisahighamountofnearsightedness,farsightednessorastigmatism.ThisiscalledbilateralrefractiveamblyopiaEtiologyAneyediseasesuchasacataractmayleadtoamblyopia.Anyfactorthatpreventsaclearimagefrombeingfocusedinsidetheeyecanleadtothedevelopmentofamblyopiainachild.Thisisoftenthemostsevereformofamblyopia.

ClassificationstrabismicamblyopiaanisometropicamblyopiaametropicamblyopiadeprivationamblyopiaSymptoms

·

Poorvisioninoneorbotheyes·

Squintingorclosingoneeyewhilereadingorwatchingtelevision·

Crossedorturnedeye·

TurningortiltingtheheadwhenlookingatanobjectExaminationofamplyopiaVisualfunctionParentsmustbeveryobservantofyoungchildrenandshouldhavearoutineeyeexamperformedbytheageof2-3todetectpotentialproblems.ExaminationofamplyopiaDoctoroftenestimatesvisualacuitybywatchinghowwellababyfollowsobjectswithoneeyewhentheothereyeiscovered.Ifoneeyeisamblyopicandthegoodeyeiscovered,thebabymayattempttolookaroundthepatch,trytopullitoff,orcry.Examinationofamplyopia

Refractivestatusoptometry

Itisnecessarytoovercomechildren-accommodationbyusingCycloplegicdrugs.1%atropineeyedrop,appliedthreetimesadayfor3days.Examinationofamplyopia

CheckstrabismusOthers

Slit-lampandfunduscopeEliminatingorganicdiseaseofeye

TreatmentEarlytreatment

Successinthetreatmentofamblyopiadependsupontwofactors:Howseveretheamblyopiais;andHowoldthechildiswhentreatmentisbegun.Iftheproblemisdetectedandtreatedearly,visioncanimproveformostchildren.

TreatmentCorrectionofrefractiveerrorswithGlasses

Forchildrenwithproblemsrelatingtoarefractiveerror,glassesmaybenecessarytocorrectvision.Treatment

SurgeryProblemsthatimpairvisionsuchascataractsordroopyeyelidsoftenrequiresurgery.

TreatmentOcclusionAmblyopiacannotusuallybecuredbytreatingthecausealone.Prescribingglassesorperformingsurgerycancorrectthecauseofamblyopia,butyourophthalmologistmustalsotreattheamblyopiaitself.Treatment

OcclusionAcommontreatmentforamblyopiaistopatchthestrongeyetoencouragethedevelopmentofthevisualpathwayoftheweakeye.

斜视strabismus掌握共同性斜视与非共同性斜视的诊断

及鉴别诊断

了解眼外肌与斜视的关系了解斜视与弱视的治疗原则目的要求第一节

概

述双眼单视或双眼视觉双眼单视或双眼视1.定义

双眼共同注视的目标同时成像在视网膜的黄斑区中心凹，通过大脑融像作用成为单一清晰的像，这种功能称为双眼单视。2.双眼单视是正常视功能的标志，分为三级：

笫一级：同时知觉

笫二级：融合

笫三级：立体视觉产生双眼单视的三个条件１、视网膜对应点：两眼视网膜黄斑中心凹具有共同视觉方向，在两眼黄斑周围视网膜上有许多成对的具有共同视觉方向的点称为视网膜对应点，只有落在视网膜对应点上的物像，才能形成双眼单视。２、两眼外肌必须平衡协调，并具有双眼固视能力,若一眼偏斜，物像则不能投射到视网膜对应点上，出现复视