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EyeDiseases:DiagnosisandDetec0on

LearningObjec0ves

ThroughexaminingimagesfromtheMementoMü)erexhibit(memento.mu?ermuseum.org),readingmaterials,andhands-onac0vi0es,studentswill

• Understandhowaberra0onsintheeye’shomeostasisaffecttheeye’sabilitytofunc0on.

• Understandthecausesofthemostcommonformsofeyedisordersandhowthesedisordersaffectvision.

• Learnandapplythetoolsandtechniquesphysiciansusetoassessanddetecteyedisorders.

TimeRequiredforLesson:Theoverviewandin-classac0vityshouldtakeanhour.StudentsaretoreadtheaCachedhandoutinadvanceoftheclasssession.

ClassPrepara0on

Inadvanceofthelesson,theinstructorshouldpreparethefollowingmaterials:

Handouts:

• ACachedmodelSnellenEyeChart(modifiedforuseinasmallerspacethanthestandard20foot/6meterchart),enoughtoallowforgroupsof2-4.ItcanalsobedownloadedathCp://visionsource.com/site/assets/files/1192/free_eye_chart.pdf.

• ACached“OcularDisorderOverview”readingmaterial,tobereadinadvanceoftheclasssession.

• Printoutone“EyeExamina0onSheet”foreachstudenttakingpartintheEyeExamina0onandEyeDisorderAssessmentac0vity.

EyeDisorderDemonstra<onGlasses(Madeinadvancebyinstructor) 1 Thesegoggles,designedbyAnn-MarieRaphail,EmilyBach,andRobertHallock,aredesignedtoprovideahands-onsimula0onoftheeffectsofvariouseyedisorders.Theinstructorshouldmakeenoughtoaccommodategroupsof2-4students.

SuppliesNeeded:

• Plas0cprotec0vegoggles(suchaslaboratoryglasses):Thenumberofgogglesdependsonhowmanydemonstra0onsofvariouscondi0onsyouwouldliketoconduct.

• Blackelectricaltape

• Plas0csandwichbags

• Cleartape

• Op0onal:Permanentmarkerorconstruc0onpaper

AssemblyInstruc<ons:

Ann-MarieRaphail,EmilyC.Bach,andRobertM.Hallock,“ClassroomDemonstra0onoftheVisualEffectsofEye1

Diseases,”JournalofUndergraduateNeuroscienceEduca<on,Vol.12,No.2(Spring2014),A150-A153.

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Eachpairofgogglesisdesignedtosimulateoneofthreekindsofvisualdisorders:tunnelvision(asinglaucoma),scotoma(adistor<onincentralvision,asinmaculardegenera<on),andblurredvision(asinrefrac<veerrorsandcataracts).

Fortunnelvision:

Coverasetofsafetygogglesinblackelectricaltape,leavingopenasmallcircleroughlyaninch(2.5cm)indiameterinthemiddleofeachlens.Coverthesidesaswell.Nextcovertheedgesofeachcirclewithalayerofcleartape(accordingtoRaphailet.Al.thismeasureis“tosimulatethegradualchangefromnormalvisioninthecentertodarknessintheperiphery”).

Forscotoma(blindspot):

Coverablackcircleofelectricaltapeatthecenterofeachlensonasetofsafetygoggles.Acircleofblackconstruc0onpaperorpermanentmarkercanalsobeused.

Forblurredvision:

Tapeseveralplas0csandwichbagsoverthetopsofthelensesofasetofsafetygoggles.ThemorebagsaCached,theblurrierthevision.

AnswerstoStudentWorksheets:Emailmailto:info@collegeofphysicians.org

AcademicStandards(Lesson,Ac0vity,andAssignments):

Next-Genera0onScienceStandards:HS-LS1-2,HS-LS1-3

CommonCore:

ScienceandTechnicalSubjects:CCSS.ELA-Literacy.RST.9-10.1,CCSS.ELA-Literacy.RST.9-10.2,CCSS.ELA-Literacy.RST.9-10.3,CCSS.ELA-Literacy.RST.9-10.4,CCSS.ELA-Literacy.RST.9-10.5,CCSS.ELA-Literacy.RST.9-10.6,CCSS.ELA-Literacy.RST.9-10.8,CCSS.ELA-Literacy.RST.9-10.10,CCSS.ELA-Literacy.RST.11-12.2,CCSS.ELA-Literacy.RST.11-12.3,CCSS.ELA-Literacy.RST.11-12.4,CCSS.ELA-Literacy.RST.11-12.5,CCSS.ELA-Literacy.RST.11-12.6,CCSS.ELA-Literacy.RST.11-12.7,CCSS.ELA-Literacy.RST.11-12.9,CCSS.ELA-Literacy.RST.11-12.10

Wri0ng:CCSS.ELA-Literacy.WHST.9-10.2,CCSS.ELA-Literacy.WHST.9-10.4,CCSS.ELA-Literacy.WHST.9-10.6,CCSS.ELA-Literacy.WHST.9-10.7,CCSS.ELA-Literacy.WHST.9-10.8,CCSS.ELA-Literacy.WHST.9-10.9,CCSS.ELA-Literacy.WHST.11-12.2,CCSS.ELA-Literacy.WHST.11-12.4,CCSS.ELA-Literacy.WHST.11-12.6,CCSS.ELA-Literacy.WHST.11-12.7,CCSS.ELA-Literacy.WHST.11-12.8,CCSS.ELA-Literacy.WHST.11-12.9

KeyTerms

Age-RelatedMacularDegenera0on:Eyedisorderwherethemacula’sconnec0ontothere0nabeginstodeteriorate,resul0nginagradualdeteriora0onofcentralvision.

Amblyopia:Eyedisorderwhererefrac0veerrorsaremoresignificantinoneeyethantheother.Alsoknownas“lazyeye.”

As0gma0sm:Refrac0veerrorcausedwheneitherthecorneaorthelensareirregularly-shaped,causingblurredvisionatnearbyandfardistances.

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Cataract:Eyedisorderwherethelensbecomescloudy,resul0nginblurredvision.

Congenital:Condi0ondevelopedatbirthorduringearlydevelopment.

Diabe0cRe0nopathy:Eyedisorderwherebloodvesselsinthere0nabecomedamaged,leakingbloodandotherfluidsintotheeye.

Drusen:Depositsthatformunderthemaculaduring“dry”maculardegenera0on.

Esotropia:Crossedeyeswhereoneorbotheyesturninwardtowardthenose.

Exotropia:Crossedeyeswhereoneorbotheyesturnoutwardtowardthetemple.

FundusoftheEye:Theinteriorsurfaceoftheeye.

Glaucoma:Eyedisorderwhereabuildupofaqueoushumorintheeye,createspressureontheop0cnerve.Thispressurecausesthefieldofvisiontonarrow.

Hyperopia:Refrac0veerrorwherelightenteringtheeyeisprojectedontoafixedpointjustbehindofthere0na,causingnearbyobjectstoappearblurry.Alsoknownasfarsightedness.

Macula:Thecentralpointofthere0nathatallowsforcentral(focused)vision.

MacularEdema:Theswellingorthickeningofthemaculacausedbydiabe0cre0nopathy.

Myopia:Refrac0veerrorwherelightenteringtheeyeisprojectedontoafixedpointjustaheadofthere0na,causingdistantobjectstoappearblurry.Alsoknownasnearsightedness.

Ophthalmoscope:Eyeexamina0ondevicethatusesalightsource,lensesandmirrorstoexaminethefundusoftheeye.

Presbyopia:Refrac0veerrorcausedwhenthelenslosesitsflexibility.

Refrac0veError:Eyedisordersthataffecttheeye’sabilitytoproperlyfocusonobjects.Causedbyirregulari0esinthecornea,thelens,ortheeyeitself.

Strabismus:Eyedisorderacondi0onwheretheeyescannotproperlyalign.Alsoknownas“crossedeyes.”

Victrectomy:Eyedisordertreatmentinwhichthevitreoushumorisdrainedfromtheeyeandreplacedwithaclearsaltsolu0on.

LectureMaterial

Part1:BasicOverviewoftheEyeandEyeDisorders

Organismshaveevolvedtomaintainastateofstabilityknownashomeostasis.However,variousfactorscaninfluencethehomeostasisofbodilysystemsandupsetthisbalance.Eyedisorders,causedeitherthroughgene0corenvironmentalfactors,candisrupttheeye’sabilitytofunc0onproperly.DoctorshavedevelopedmethodstoaCempttodetectdisorderssoastominimizeorpreventpermanentdamage.

Eyedisorderscanbetheresultofnumerousfactors:imperfec0onsdevelopedintheeyeduringbirthorearlydevelopment(congenital),injuriestotheeyeorbrain,sideeffectsofdiseases,orthe

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naturaldeteriora0onofthebodyasitages.Whateverthecause,itisimportantfordoctorstoiden0fywhatisgoingonintheeyetoensurethepropertreatmentscantakeplace.

VisualDemonstra4on:EyePathologiesImagefromMemento.Mu)erMuseum.org

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Figure1.EyePathologies,AccessionNo.9201-9301.

Teacher’sNote:Showzoomed-inimagesofthewaxmodelsofeyepathologiestodemonstratetheeffectsofavarietyofeyediseases.

Thesewaxmodelsdemonstrateavarietyofeyeinjuriesanddiseases,fromthecommon(suchasthe“black”eye,thesecondeyefromtherightintheboComrow)totheextreme(suchasthepolypthathasforcedtheeyefromitssocketandtheeyesocketdestroyedbycancer,thefirstandsecondfromtherightinthetoprow,respec0vely).

Physicianslearnabouttheeyethroughdissec0onofspecimens,analyzingmodels,andexamininglivepa0ents.

VisualDemonstra4on:Papier-mâchéEyeballModelfromMemento.Mu)erMuseum.org

Teacher’sNote:Rotatethemodeltodemonstratethepartsoftheeye.Instructstudentstoiden4fythevariousparts.

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Figure2.Papier-MâchéEyeballModel,withlabeledparts,AccessionNo.F1993.701.

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Figure3.DrawingoftheEye.Source:Na<onalEyeIns<tute,Na<onalIns<tutesofHealth.UsedunderCrea<veCommonlicense2.0.Nochangeshavebeenmade.

Part2:OverviewofEyeExamina0ons

Becausemanyeyediseasesexhibitnosymptoms,theNa0onalIns0tuteofHealthrecommendsregularcheckupsasameansofdetec0ngeyediseasesearly.Indiseasessuchasdiabe0cre0nopathyand

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glaucoma,earlydetec0onisessen0altoensurepropertreatment.Earlydetec<oncanbethedifferencebetweenmaintainingorlosingsight! 2

Duringarou0neeyeexamina0on,anphysicianconductsaseriesofteststoassesschangesinapa0ent’svisualacuityandcheckforthesignsofeyedisorders.AccordingtotheAmericanAcademyofOphthalmology,arou0neeyeexamina0onconsistsofeightparts:

• VisualAcuityTest(usingeyechartstotestapa0ent’svision)

• PupilExamina0on(tes0ngpupilsize,shape,andresponsivenesstolight)

• ExtraocularMo0lityandAlignment(tes0ngwhethertheeyescanmoveandalignproperlybyhavingapa0entfollowanobjectwithhisorhereyes)hCps://www.nlm.nih.gov/medlineplus/ency/ar0cle/003397.htm

• IntraocularPressure(tes0ngforglaucomabymeasuringtheeye’sinternalpressure)

• VisualFieldAssessment(tes0ngthepa0ent’scentralandperipheralvision)

• ExternalExamina0on(visuallycheckingeyelids,skin,headandlymphnodes)

• SlitLampExamina0on(closeexamina0onofop0cnerve,macula,sclera,cornea,anteriorchamber,iris,andlensthroughaspecializedmicroscopecalledaslitlamp)

• Fundoscopy(usinganophthalmoscopetoexaminethefundus) 3

Theresultscollectedfromeachofthesetestsarethencomparedtopastresultsfrompreviousexamina0ons.Thephysicianusestheseresultstodiagnoseaneyedisorder.

Part3:TheOphthalmoscope,aRevolu0onaryTool

Oneofthemostrevolu0onarydevelopmentsinthehistoryofdiagnosingeyediseaseswastheinven0onoftheophthalmoscope.

VisualDemonstra4on:Ophthalmoscopeand“Anearlyophthalmoscopewithsourceoflightshown”

Teacher’sNote:NavigatetotheophthalmoscopeonMemento.Mu)erMuseum.org.

hCps://www.nlm.nih.gov/medlineplus/eyediseases.html.2

hCp://www.aao.org/young-ophthalmologists/yo-info/ar0cle/how-to-conduct-eight-point-ophthalmology-exam.3

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Figure4.Ophthalmoscope,AccessionNo.17647.16

Note:Asyouexplainthefunc4onoftheophthalmoscope,movethroughtheslidesoftheimage,focusingonthemechanismandlenses.

HowtheOphthalmoscopeWorks

Theophthalmoscopeworksbyshiningalightsourceontoamirror.Themirrorreflectsthelightthroughthepupilofasubject’seye.Thelightreflectsontothere0na,illumina0ngthefundus,orinteriorsurface,oftheeye.Thisillumina0onallowstheobservertoexaminethefundus,usinglensestoenhancetheimage,thusallowingtheobservertoexaminetheeye. 4

HistoricalOverview:Thepupilperplexedeighteenthandnineteenthcenturyscien0sts.Theyobservedthatunderlowlightcondi0onsthattheeyesofcertainanimalsappearedtoglow.Whatcouldbethesourceofthisillumina0on?Didtheeyeactasitsownlightsourceindarkness?Didtheeyeabsorblightduringtheday?Wasthereachemicalprocessgoingonintheeyethatallowedittoglow,asinthecaseoffireflies?Diditemititsownelectricity?

Ul0mately,experimentsconductedinthe1800sprovedtheanswertobe“NoneoftheAbove.”In1810,Frenchscien0stBénédictPrévostdeterminedthere0naonlyrespondedtolightenteringthepupil,andtheeyewasnotgenera0nglightonitsown.Laterscien0stsdiscoveredthattheinterioroftheeyecouldbeseenwhileflashingalightthroughthepupil. In1823,Czechscien0stJanPurkyne5

determinedtheeyedidnotgenerateitsownlightintotaldarkness;instead,the“illumina0on”wastheresultoflightreflec0nguponthere0na.Helearnedthisbyconduc0ngexperimentsinvolvingshiningacandlelightontoasetoflensesintothepupilofadog’seye.Thisledotherscien0ststoexplorethepossibilityusingacombina0onofmirrorsandalightsourcelighttoexaminethefundus.

Duringthemid-1800s,therewereseveralaCemptstocreateadeviceforexaminingtheeye.Perhapstheearliestcamein1847whenAmericaninventorCharlesBabbagedesignedasimple

GeorgeT.TimberlakeandMichaelKennedy,TheDirectOphthalmoscope:HowItWorksandHowtoUseIt4

(UniversityofKansasMedicalCenter,2005),11-13.

StanleyJoelReiser,MedicineandtheReignofTechnology(Cambridge,UK:CambridgeUP,1981),45-47.5

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ophthalmoscopebyplacingamirroratanangleinasmallmetaltube.Alightsourcecouldthenbereflectedontothemirrorandintotheeye.However,duringthetes0ngofhisdevice,Babbagefoundhewasunabletoobservetheinterioroftheeyeandheabandonedhisdesign.

Thesolu0ontotheophthalmoscopecameseveralyearslater.In1851,ayoungGermanscien0stnamedHermannvonHelmholtzdevelopedasimilardevice,whichhecalledAugenspiegel(Germanfor“eyemirror”).Itcontainedasetof0ltedglassplateswhichwhenexposedtoalightsourceallowedtheusertoviewtheinteriorofasubject’seye.Thedeviceeventuallycametobeknownasthe“ophthalmoscope.”Theophthalmoscoperemainsastandardtoolineyeexamina0ontothisday,withfewaltera0onstoHelmholtz’soriginaldesign. In1892,ophthalmologistEdwardLoringcommentedon6

theophthalmoscope:“Inthewholehistoryofmedicinethereisnomorebeau0fulepisodethantheinven0onoftheophthalmoscope,andphysiologyhasfewgreatertriumphs.”

WebResourcesRelatedtotheEyeandEyeDisorders:

hCp://www.aao.org/

hCps://www.nlm.nih.gov/medlineplus/eyediseases.html

hCp://www.aoa.org/pa0ents-and-public/eye-and-vision-problems?sso=y

ClassroomAc0vity:EyeExamina0onandEyeDisorderAssessment

Inthisac4vity,studentswillexaminetheeffectsofeyedisordersonregularvision.Workinginpairs(orsmallgroupsdependingonaccesstosupplies),studentswillconducttwotestsperformedduringarou4neeyeexamina4on:avisualacuitytestandavisualfieldassessment.Thegroupswillusetheseteststocomparevisionundernormal(unimpeded)circumstancestovisionimpairedbythreedifferentkindsofvisualdisorders:tunnelvision(asinglaucoma),blurredvision(asinrefrac4veerrorsandcataracts),anddistortedcentralvision(asinmaculardegenera4on).

Ac4vity

Part1:Prepara0on

1) Studentsbreakintogroupsoftwo.EachgrouptakesacopyoftheSnellenchart,asetofgoggles,andanexamina0onsheet.Ifsuppliesarelimitedhavethembreakintogroupsofthreeorfour.

2) First,haveeachstudentsetupacontrolbymeasuringeachother’svisualacuity.Useatapemeasuretomeasureadistanceoftenfeet.Dependingonthesizeoftheclassroomthismayneedtobeconductedinthehallway.Floor0lesmayalsobeusedtomeasureoutthenecessarydistance.Onestudentwillserveas“thepa0ent”andtheother“theobserver.”

3) Havetheobserverstandatoneend,holdinguptheSnellenchart,whilethepa0entstandsattheoppositeend.

4) Instructthepa0enttocoveroneeyeandaCempttoreadthesmallestrowofleCershe/shecansee,thenrepeatthiswiththeoppositeeye.Ifthestudentwearscorrec0velenses,havethemkeepthemonduringthisprocess.

CRKeeler,“ABriefHistoryoftheOphthalmoscope,”OptometryinPrac<ceVol.4(2003),137-145;CRKeeler,6

“BabbagetheUnfortunate,”JournalofOphthalmologyVol.88No.6(June2004),730-732..

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5) Theobserverthendocumentsthefrac0onnexttotherowthepa0entcouldreadontheirexamina0onchart.Thenthestudentsswitchrolesandrepeattheprocess.

6) Next,eachstudentwillconductavisualfieldassessment.Instructeachstudenttostandfacetofaceroughlytwofeetapart.

7) Havethepa0entstarestraightahead.Theobserverwillthenholdupfingers(theamountisuptothem)infrontofthepa0entwhothentellstheobserverhowmanyfingerstheysee.Theobserverthenholdsupfingersandmoveshis/herhandtothelerofthepa0ent’sheadjustattheedgeoftheirperiphery.Thepa0entagainsayshowmanyfingershe/shesees.Theobserverthendoesthesametotherightofthepa0ent.

8) Theobserverrecordswhetherornotthepa0entcouldcorrectlyiden0fythenumberoffingersontheexamina0onsheet.Thestudentsthenswitchroles.

Thedatacollectedfromthevisualacuityandvisualfieldassessmentswillserveasacontrol.

9) Repeatthevisualacuityandvisualfieldassessmentswhilethepa0entwearseachofthesetsofgoggles,makingnoteoftheresultsontheexamina0onsheet.

10) Onceallstudentshavecompletedtheirexamina0ons,theclassreconvenesandhavestudentsexplaintheirresults.

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EyeExamina0onSheet

Observer’sName:_________________________________________________________________

Pa0ent’sName:___________________________________________________________________

DateofExamina0on:_______________________________________________________________

-------------------------------------------------------------------------------------------------------------------------------

Test#1(ControlGroup):

VisualAcuityTest: LerEye:20/__________ RightEye:20/_________

VisualFieldAssessment:

CentralVision(Canseenumbersinfrontofface): YES NO

PeripheralVision

Canseenumberstothelerofface: YES NO

Canseenumberstotherightofface:YES NO

-------------------------------------------------------------------------------------------------------------------------------

Test#2(Glaucoma)

VisualAcuityTest: LerEye:20/__________ RightEye:20/_________

VisualFieldAssessment:

CentralVision(Canseenumbersinfrontofface): YES NO

PeripheralVision

Successfullyseesfingerstothelerofface: YES NO

Successfullyseesfingerstotherightofface:YES NO

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Test#3(MacularDegenera0on)

VisualAcuityTest: LerEye:20/__________ RightEye:20/_________

VisualFieldAssessment:

CentralVision(Canseenumbersinfrontofface): YES NO

PeripheralVision

Successfullyseesfingerstothelerofface: YES NO

Successfullyseesfingerstotherightofface:YES NO

-------------------------------------------------------------------------------------------------------------------------------

Test#4(Cataracts)

VisualAcuityTest: LerEye:20/__________ RightEye:20/_________

VisualFieldAssessment:

CentralVision(Canseenumbersinfrontofface): YES NO

PeripheralVision

Successfullyseesfingerstothelerofface: YES NO

Successfullyseesfingerstotherightofface:YES NO

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StudentHandout:OverviewofOcularDisorders

Overview:

AccordingtotheCentersforDiseaseControlandPreven0on,roughly14millionpeopleovertheageoftwelvehavesomekindofvisualimpairment.TheCDCreportsthemostcommoneyedisordersareRefrac4veErrors,Age-RelatedMacularDegenera4on,Cataracts,Diabe4cRe4nopathy,Glaucoma,Amblyopia,andStrabismus. 7

Refrac0veErrors:

Refrac0veerrorsarethemostcommoneyedisorders.Refrac0veerrorsarecommonlycausedbyirregulari0esinthecornea,thelens,ortheeyeitself;theseirregulari0esaffecttheabilityoftheeyetoproperlyfocusonobjects.Theycanexhibitatayoungage(myopia,hyperopia,as0gma0sm)orlaterinlifeasaresultofaging(presbyopia).Refrac0veerrorsarecommonlycorrectedthroughtheuseofcorrec0velenses(glassesorcontactlenses)orsurgery.

CommonRefrac0veErrors:

Myopia(Nearsightedness):Innormalvision,lightisprojectedontothere0naandisprocessedbythephotoreceptors.Inthecaseofpa0entswithmyopia,thelightisprojectedontoafixedpointjustaheadofthere0na,causingdistantobjectstoappearblurry.AccordingtotheAmericanOptometricAssocia0on,nearlythirtypercentofAmericanshavemyopia. 8

Hyperopia(Farsightedness):Innormalvision,lightisprojectedontothere0naandisprocessedbythephotoreceptors.Inthecaseofpa0entswithhyperopia,thelightisprojectedontoafixedpointjustbehindofthere0na,causingnearbyobjectstoappearblurry. 9

As4gma4sm:As0gma0smiscausedwheneitherthecornea(theprotec0vecoveroftheeye)orthelensareirregularly-shaped.Thiscausesblurredvisionatnearbyandfardistances. 10

Presbyopia:Presbyopiaiscausedwhenthelenslosesitsflexibility.Itappearsmostcommonlyinpa0entsovertheageoffortyasvisionnaturallydeteriorates. 11

Age-RelatedMacularDegenera0on(AMD):

hCp://www.cdc.gov/visionhealth/basic_informa0on/fast_facts.htm;hCp://www.cdc.gov/visionhealth/7

basic_informa0on/eye_disorders.htm.

hCp://www.aoa.org/pa0ents-and-public/eye-and-vision-problems/glossary-of-eye-and-vision-condi0ons/myopia?8

sso=y.

hCps://www.aoa.org/pa0ents-and-public/eye-and-vision-problems/glossary-of-eye-and-vision-condi0ons/9

hyperopia?sso=y.

hCps://www.aoa.org/pa0ents-and-public/eye-and-vision-problems/glossary-of-eye-and-vision-condi0ons/10

as0gma0sm?sso=y.

hCps://www.aoa.org/pa0ents-and-public/eye-and-vision-problems/glossary-of-eye-and-vision-condi0ons/11

presbyopia?sso=y.

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Themaculaisthecentralpointofthere0naandallowsforfocusedvision.AMDiscausedwhenthemacula’sconnec0ontothere0nabeginstodeteriorate,resul0nginagradualdeteriora0onofvision.Thisusuallystartsasablurrypointinthecenterofapa0ent’svisionwhichgraduallyincreasesinsizeastheyage.Maculardegenera0oncomesintwovarie0es:wetanddry.Dryisthemostcommonformandiscausedwhendepositscalleddrusenformunderthemacula,causingittobecomethin.Wetiscausedwhenbloodvesselsformunderthemaculaandbegintoleakfluids.ThereiscurrentlynocureforAMD.

Asthenamesuggests,AMDismostcommonlyexhibitedinagingpa0ents(usuallyagedfiryandolder),anditistheleadingcauseofvisionlossinpa0entsovertheageoffiry,accordingtotheCDC. 12

Cataracts:

Cataractsarecausedwhenthelensbecomescloudy,resul0nginblurredvision.Theyaremostcommonamongelderlypa0ents.AccordingtotheNa0onalEyeIns0tuteoftheNa0onalIns0tuteofHealth,overhalfthepeopleovertheageofeightyhavecataracts.However,cataractscanappearatbirthorearlyinlife(congenitalcataracts);developduetoeyetrauma(trauma0ccataracts)orradia0onexposure(radia0oncataracts);oroccurastheresultofotherdiseasessuchasglaucomaordiabetes(secondarycataracts). 13

Cataractscanbemanagedthroughcorrec0velenses.Ifvisionissignificantlydeterioratedthedamagedlenscanbesurgicallyremovedandreplacedwithanar0ficialone.

Diabe0cRe0nopathy:

Certaindiseaseswhentheyprogressorwhenleruntreatedcaneventuallyaffectvision.ThemostcommonoftheseintheUnitedStatesiscausedbyadvanceddiabetes.AccordingtotheCDC,Diabe0cRe0nopathyistheleadingcauseofblindnessinadultsintheUSbetweentheagesof20and74.

Diabe0cRe0nopathyoccursintwostages:nonprolifera0veandprolifera0ve.InNonprolifera0veDiabe0cRe0nopathy(NPDR),theearliestphase,bloodvesselsinthere0nabecomedamaged,leakingbloodandotherfluidsintotheeye.AsNPDRadvances,themaculacanbegintoswellorthickeninaprocessknownasmacularedema.Thisswellingofthemacularesultsinblurredvision.Thecondi0oncanthenadvancetoProlifera0veDiabe0cRe0nopathy(PDR),wherethebloodvesselsinthere0naclose.There0naaCemptstocompensatebygrowingnewvessels.However,thesenewvesselsgrowabnormally,causingthemtoleakmorefluidintothevitreoushumor.Scar0ssuecausedasaresultcanleadtothere0nadetachingwhichcanleadtoblindness.

hCps://www.macular.org/what-macular-degenera0on;hCps://www.aoa.org/pa0ents-and-public/eye-and-vision-12

problems/glossary-of-eye-and-vision-condi0ons/macular-degenera0on?sso=y;hCps://nei.nih.gov/health/maculardegen/armd_facts;DeborahPavan-Langston,ManualofOcularDiagnosisandTherapy,FourthEdi0on(Boston:LiCle,BrownandCompany,1996),168-169.

hCps://nei.nih.gov/health/cataract/cataract_facts.13

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Medica0onandlasertreatmenttoeliminatedefec0vebloodcellscanbeusedtominimizetheeffectsofmacularedema.Doctorscanalsoperformaprocedurecalledavictrectomyinwhichthevitreoushumorisdrainedfromtheeyeandreplacedwithaclearsaltsolu0on. 14

Glaucoma:

Glaucomaisanameforcollec0onofeyediseases.Collec0velytheyarecausedbyanexcessbuildupofaqueoushumorintheeye,crea0ngaddi0onalpressureontheop0cnerve.Thisbuildupinpressurecanleadtodamagetotheop0cnerve.Asthediseaseprogressives,pa0entswillgraduallyloseperipheralvisioninoneorbotheyes,followedbytunnelvisionastheperipheralvisioncon0nuestonarrow.Thisnarrowingcanadvanceun0lthepa0entislercompletelyblind.

Themostcommonformofthediseaseisknownasprimaryopenangleglaucoma.Inthisversionofglaucoma,thebuildupinaqueoushumoriscausedwhenthevesselsresponsiblefordrainingthefluidbecomeblocked.AccordingtotheGlaucomaResearchFounda0on,aboutthreemillionpeopleintheUSsufferfromprimaryopen-angleglaucoma.

Currentlythereisnocureforglaucomabuttherearemedica0onsavailabletohelpreduceeyepressure.Laserandtradi0onalsurgerymayalsobeusedtodrainexcessaqueoushumor. 15

Strabismus:

Commonlyknownas“crossedeyes,”strabismusisacondi0onwheretheeyescannotproperlyalign.Itiscausedwhenthemusclessurroundingtheeyearenotworkingproperly.Themisalignmentcanresultinoneorbotheyesleaninginwardtowardthenose(esotropia)oroutwardtowardthetemple(exotropia).Thiscanresultindoublevision,lackofdepthpercep0on,andamblyopia(seebelow).Strabismusmanifestsmostcommonlyinchildrenundertheageofthree.However,avarietyoffactors,includingcertaindiseases(suchasbotulismanddiabetes)andocularorneurologicaldamage(asaresultoftraumaorstroke),cancausestrabismusinadults.Thecondi0onistreatedthroughcorrec0velenses,eyemuscleexercises,orsurgery. 16

Amblyopia:

Commonlyknownas“lazyeye,”amblyopiaisacondi0onwhererefrac0veerrorsaremoresignificantinoneeyethantheother,causingthebraintofavoroneeyeovertheother.Thiscondi0onmanifestsduringinfancyorearlychildhood.

Contrarytopopularbelief,amblyopiadoesnotcausemisalignmentoftheeye(strabismus).However,amblyopiacandevelopinpa0entswithstrabismusthatisnotproperlytreated.Amblyopiacanalsobebroughtuponbyacataract.

hCps://nei.nih.gov/health/diabe0c/re0nopathy;hCp://www.aoa.org/pa0ents-and-public/eye-and-vision-14

problems/glossary-of-eye-and-vision-condi0ons/diabe0c-re0nopathy?sso=y;hCp://www.aao.org/eye-health/0ps-preven0on/what-is-diabe0c-re0nopathy.

hCp://www.aao.org/eye-health/diseases/what-is-glaucoma;hCp://www.glaucoma.org/glaucoma/primary-open-15

angle-glaucoma.php;hCps://nei.nih.gov/health/glaucoma/glaucoma_facts.

hCps://www.nlm.nih.gov/medlineplus/ency/ar0cle/001004.htm;hCp://www.aoa.org/pa0ents-and-public/eye-16

and-vision-problems/glossary-of-eye-and-vision-condi0ons/strabismus?sso=y.

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Amblyopiacanbestbecorrectediftreatedatanearlyagewhiletheeyesares0lldeveloping(usuallybetweentheagesofsevenandtenyearsold).Themostcommontreatmentistoacceleratethegrowthoftheweakereyebyinhibi0ngthevisionofthestrongereyethroughatropineeyedropsoraneyepatch. 17

hCps://nei.nih.gov/health/amblyopia/amblyopia_guide;hCp://www.aapos.org/terms/condi0ons/21.17

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NAME_____________________________________________ DATE:______________Assignment:ReadtheaCachedOverviewofOcularDisordersandcompletethesec0onsbelow.

Part1:Usethereadingsampletocompletethefollowingsentences.

1. ________________________isadisorderwherethemacula’sconnec0ontothere0nabeginstodeteriorate.

2. Arefrac0veerrorcausedbyeitheranirregularly-shapedcorneaorlens,causingblurredvisionatnearbyandfardistancesisknownas________________________.

3. Onetreatmentfordiabe0cre0nopathyis________________________inwhichthevitreoushumorisdrainedfromtheeyeandreplacedwithaclearsaltsolu0on.

4. ________________________,or“nearsightedness,”isarefrac0veerrorwheredistantobjectsappearblurry.

5. Ifapa0enthascrossedeyeswhereoneorbotheyesturninwardtowardthenose,he/shesuffersfrom________________________.

6. ________________________,or“crossedeyes,”isadisorderwheretheeyescannotproperlyalign.

7. Ifapa0entviewsnearbyobjectsasblurry,itispossiblehe/shesuffersfrom________________________,alsoknownas“farsightedness.”

8. The________________________isthepartoftheeyethatallowsforcentral(focused)vision.

9. ________________________isadisordercausedwhenanexcessbuildupofaqueoushumorcreatesgreaterpressureontheeye,causingthepa0ent’svisiontonarrow.

10. Acondi0onwheretherefrac0veerrorinoneeyeisgreaterthantheotherisknownas________________________,or“lazyeye.”

11. Duringdrymaculardegenera0on,depositsknownas________________________formunderthemacula,causingittobecomethin.

12. Apa0entissufferingfrom________________________whenthelensinoneorbotheyesbecomescloudy,resul0nginblurredvision.

13. ________________________isarefrac0veerrorcausedwhenthelenslosesitsflexibility.

14. Apersonwith“crossedeyes”whereeitheroneorbotheyesturnoutwardtowardthetemplesuffersfrom________________________.

15. Untreateddiabetesmaybringabout________________________,adisorderwherebloodvesselsinthere0nabecomedamagedandleakbloodandotherfluidsintotheeye.

Part2:Listonetreatmentforthefollowingeyedisorders:

1. Refrac0veErrors

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2. Diabe0cRe0nopathy

3. Amblyopia

4. Glaucoma

5. Cataracts

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NAME_____________________________________________ DATE:______________ReadingScien0fic/TechnicalSubjectTake-HomeAssignment:

ReadthesampleofHermannvonHelmholtz’sexplana0onoftheophthalmoscope,andanswerthefollowingques0onsonaseparatesheetofpaper.

1) Summarizethepassage.Whatisthecentralthemeofthepassage?

2) Definethefollowingtermsusedinthetext:

Choroid:

Sclero0c:

Re0na:

LuminousObject:

Fundus:

Ophthalmoscope:

3) Usingtextualevidence,answerthefollowingques0ons:

a) WhatdoesHelmholtzviewasanobstacletoobserversexamininganilluminatedre0na?

b) WhatisHelmholtz’sproposedsolu0ontothisproblem?

c) Whenthisobstacleisovercome,accordingtoHelmholtz,howshouldthere0naappearto

theobserver?

d) HowdoesHelmholtzproposegetngaclearerviewoftheinsideofthere0na?

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HermanVonHelmholtz’sExplana0onofHisOphthalmoscope(1857)

HermannvonHelmholtz,trans.JamesP.C.Southall,HelmholtzTrea<seonPhysiologicalOp<csOp0calSocietyofAmerica,1924.226-229.

Accordingtotheprincipleofthereversibilityofthelightpath,lightwilltraversepreciselythe

sameroutethroughanop0calinstrumentfromoneendtotheotherineitherdirec0on.Thus,for

example,sofarasthisprincipleisconcerned,itmakesnodifferencewhichoneofapairofconjugate

pointsisregardedasthesourceofthelightandwhichoneastheimage,becauseinthisrespectobject

andimageareinterchangeable.Suppose,therefore,thattheeyeisaccommodatedtofocusonthere0na

anexactimageofanexternalluminousobject;andsupposethatweregardtheilluminatedpartofthe

re0naasbeingitselfaluminousobject:thenitsimageprojectedbytheocularmediawillcoincide

exactlywiththeexternalobject.Inotherwords,allthelightproceedingfromthere0nathroughtheeye

willreturnpunctuallytotheoutsideluminousbody.Inordertogetsomeofthislight,anobserverwould

havetoinserthiseyebetweentheluminousbodyandtheilluminatedeye,whichofcourse,cannotbe

donewithoutsomeauxiliarycontrivancetopreventtheillumina0nglightfrombeingintercepted.

…Thus,underordinarycircumstances,eventhepartsofthefundusoftheeyethatreflectlight

beCerthantheotherplaces,as,forexample,thewhiteareawheretheop0cnerveenterstheeyeand

thebloodvessels,arenotvisibletoanoutsideobserver…Butiftheilluminatedeyeisnotaccommodated

exactlyeitherfortheluminousobjectorforthepupiloftheobserver’seye,itmaybepossibleforthe

observertogetsomeofthelightreturningfromthepupiloftheotherperson’seye;andthenthepupil

willlookbrighttohim.

It’snothardtounderstandhowtheobservercangetlightfromallthosepartsofthere0naof

anotherperson’seye,thatarecomprisedwithintheareacoveredbytheblurredimageofthepupilofhis

owneye.Suppose,foramoment,thatthepupiloftheobserver’seyeisreplacedbyaluminousdisc

whoseblurredimageintheotherperson’seyecoincidedexactlywithwhatwastherebefore.Nowinthis

caseraysoflightproceedfromoneormorepointsoftheilluminateddisctoallthepointsofitsblurred

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image.Accordingly,raysoflightmaycomebackfromallpartsoftheilluminatedareaonthere0natothe

correspondingpointorpointsonthedisc;thatis,totheplacewheretheobserver’spupilis.Thusthe

observerwillseetheotherperson’seyeasluminous,whenevertheblurredimageofhisownpupilin

thateyepartlyoverlapstheblurredimageofaluminousobject.

Suppose,therefore,thattheobserverlooksrightpasttheedgeofalight,thatisscreenedfrom

hisowneyesoasnottoblindhim,intoanotherperson’seye;andsupposethatthislaCereyeis

accommodatedforapointbetweenthetwoeyesorforapointmuchfartherawaythantheopposite

eye:underthesecircumstances,theobserverwillseethepupiloftheothereyeshiningred….The

experimentisusuallysuccessfulalsowithouttakingaccountoftheaccommoda0onoftheilluminated

eye,providedtheobserverisfaraway,orprovidedthepa0entlookstooneside…becausethenthe

imageofthelightandthatofthepupiloftheobserver’seyeareprojectedonthelateralpartsofthe

re0nawheretheimagesaregenerallynotclear-cut.Theillumina0onisbrightestwhenthelightfallsat

theplacewheretheop0cnerveenterstheeye,becausethelightishighlyreflectedfromthiswhite

substance,andalsobecauseitstranslucencyissuchthatitdoesnotofferanydefinitesurfaceforthe

projec0onofaclear-cutimage.

Itmaybenotedthatwithsufficientlystrongillumina0onenoughlightgoesthroughthechoroid

tothesclero0ctobepercep0blewhenitisdiffuselyreflectedbackagain….Hence,withstrong

illumina0on,evenwhenthepa0ent’seyeisexactlyaccommodatedforthepupiloftheobserver’seye,

theluminositymaybefeeble,especiallyifthereisnotmuchpigmentintheeye….

Theluminosityoftheeyecanbeobserveds0llbeCer,provided[thelightsource]isnot

permiCedtofalldirectlyontheeye,butisreflectedonitfromaglassplatethroughwhichtheobserver

canlookintoit

[….]

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Nowalthoughunderthesecircumstancestheobserverbeholdstheilluminatedfundusofthe

eye,asarule,perhaps,hecannotmakeoutanyofitsdetails,becauseheisunabletoaccommodatefor

theimageofthefundusthatisproducedbytheocularmedia.Todothis,hemustuseappropriateglass

lenses.Thecombina0onofanillumina0onapparatuswithglasslensesinthiswaycons0tutesan

instrumentcalledanophthalmoscope(or“ocularmirror”),whichenablestheobservertoseedis0nctly

theimagesonthere0naandthedetailsofthere0naonanotherperson’seye,andtoinves0gatethem.

©2016TheCollegeofPhysiciansofPhiladelphia

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EyeDisorderResearchAssignment:

Selectaneyediseaseorcondi0onlistedbelowtouseasatopicofaresearchproject. 18

Gatherresearchfromreliableprintandweb-basedsourcesandanswerthefollowingques0ons:

1) Whatisthecause(orcauses)ofthedisorder?

Albinism CytomegalovirusRe0ni0s MarfanSyndrome

Anisocoria DetachedorTornRe0na MicrovascularCranialNervePalsy

BacterialKera00s DryEye MyastheniaGravis

Bell’sPalsy EyeCancer Nevus

BlackEye EyeLymphoma Nystagmus

Blephari0s Floaters OcularHypertension

BlockedTearDuct Fuchs’Dystrophy OcularMelanoma

BranchRe0nalVeinOcclusion(BRVO)

GiantCellArteri0s Onchocerciasis(AfricanRiverBlindness)

Celluli0s GravesDisease Op0cNeuri0s

CentralRe0nalVeinOcclusion Hemangioma PigmentDispersionSyndrome

ChalaziaandStye HerpesZoster(Shingles) Pinguecula

ChoroidalNeovascularMembranes

Histoplasmosis Ptosis

Coloboma Hyphema Scleri0s

ColorBlindness(ColorVisionDeficiency)

IridocornealEndothelialSyndrome

StargardtDisease

Conunc0vi0s(PinkEye) IschemicOp0cNeuropathy S0cklerSyndrome

CornealAbrasion Kera00s Trachoma

CornealDystrophies Keratoconus Trichiasis

CornealErosion MacularHole UsherSyndrome

CornealLacera0on MacularPucker Uvei0s

CornealUlcer MacularTelangiectasia MarfanSyndrome

hCp://www.aao.org/eye-health/a-z.18

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2) Istheredebateamongscien0stsoveritscauses?Ifso,brieflyexplainthedifferencesinopinion.

3) Whateffectsdoesthedisorderhaveonthepartsoftheeye?

4) WhatarethesymptomsaCributedtothisdisorder?

5) Whatareitsshortandlongtermeffects?

6) Arethereanyavailablecuresortreatments?Isthedisorderpreventable?Arethereanydisagreementsinthescien0ficcommunityoverwhicharethemosteffec0ve?

©2016TheCollegeofPhysiciansofPhiladelphia