眼科學(xué)教學(xué)課件：眼視光學(xué)

眼視光學(xué)Optometry

andOphthalmology

眼的屈光和調(diào)節(jié)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

視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.

斜視strabismus掌握共同性斜視與非共同性斜視的診斷

及鑒別診斷

了解眼外肌與斜視的關(guān)系了解斜視與弱視的治療原則目的要求第一節(jié)

概

述雙眼單視或雙眼視覺(jué)雙眼單視或雙眼視1.定義

雙眼共同注視的目標(biāo)同時(shí)成像在視網(wǎng)膜的黃斑區(qū)中心凹，通過(guò)大腦融像作用成為單一清晰的像，這種功能稱(chēng)為雙眼單視。2.雙眼單視是正常視功能的標(biāo)志，分為三級(jí)：

笫一級(jí)：同時(shí)知覺(jué)

笫二級(jí)：融合

笫三級(jí)：立體視覺(jué)產(chǎn)生雙眼單視的三個(gè)條件１、視網(wǎng)膜對(duì)應(yīng)點(diǎn)：兩眼視網(wǎng)膜黃斑中心凹具有共同視覺(jué)方向，在兩眼黃斑周?chē)暰W(wǎng)膜上有許多成對(duì)的具有共同視覺(jué)方向的點(diǎn)稱(chēng)為視網(wǎng)膜對(duì)應(yīng)點(diǎn)，只有落在視網(wǎng)膜對(duì)應(yīng)點(diǎn)上的物像，才能形成雙眼單視。２、兩眼外肌必須平衡協(xié)調(diào)，并具有雙眼固視能力,若一眼偏斜，物像則不能投射到視網(wǎng)膜對(duì)應(yīng)點(diǎn)上，出現(xiàn)復(fù)視