Age.docx
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Age.docx
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Age
Age-RelatedMacularDegeneration:
UpdateforPrimaryCare
DONALDS.FONG,M.D.,M.P.H.,
SouthernCaliforniaPermanenteMedicalGroup,BaldwinPark,California,and
UniversityofCalifornia,LosAngeles,SchoolofMedicine,LosAngeles,California
Age-relatedmaculardegenerationistheleadingcauseofseverevisionlossamongtheelderly.Inthiscondition,centralvisionislost,butperipheralvisionalmostalwaysremainsintact.Affectedpersonsrarelyrequirecanesorguidedogs.Thediagnosisofage-relatedmaculardegenerationisbasedonsymptomsandophthalmoscopicfindings,andthediseasecanbeclassifiedintoatrophicandexudativeforms.Thetwocurrentlyproventreatmentsarelaserphotocoagulationandphotodynamictherapy,butthesemeasuresareeffectiveinonlyasmallfractionofeyeswiththeexudativeformofmaculardegeneration.Visionrehabilitationcanhelppatientsmaximizetheirremainingvisionandadaptsothattheycanperformactivitiesofdailyliving.Familiesneedencouragementinprovidingsupportandhelpingpatientsadjusttobeingpartiallysighted.(AmFamPhysician2000;61:
3035-42.)
Elderlypersonsareconcernedaboutlosingindependenceandmobility.Studieshaveshownthatlossofcentralvisualacuityleadstoareductionofdailyactivitiesandmobilityintheelderly.1Lossofcentralvisualacuityalsoincreasestherisksoffalls,fracturesanddepressioninthispopulation.2
Patientswithage-relatedmaculardegenerationhavethemostdifficultywithactivitiesthatrequire"high-definition"vision,suchasdrivingandreading.
Age-relatedmaculardegenerationistheleadingcauseofseverevisionlossinolderAmericans.3,4Inthiscondition,thecentralportionoftheretina(themacula)deteriorates,andcentralvisioncanbelost.Centralvisionisthe"high-definition"visionthatisrequiredforreading,driving,watchingtelevision,recognizingpeopleandperformingmanyotheractivitiesofdailyofliving.Peripheralvisiongenerallyremainsintact,andelderlypersonswithage-relatedmaculardegenerationrarelyrequirecanesorguidedogs.However,theyhavebeenfoundtohavelowerquality-of-lifescoresthanpersonswithchronicobstructivepulmonarydiseaseoracquiredimmunodeficiencysyndrome.5-8
WiththecontinuedgrowthoftheelderlypopulationintheUnitedStates,familyphysiciansarefrequentlyaskedaboutvisionandmaculardegeneration.Aslifeexpectancycontinuestoincrease,age-relatedmaculardegenerationwillbecomeanincreasinglyimportantproblem.
Epidemiology
FIGURE1.Maculaofthelefteye.Theyellowish-coloredsubretinallesionsinthemacularepresentdrusen,whichareacommonophthalmoscopicfindinginpatientswithearlyage-relatedmaculardegeneration.
Age-relatedmaculardegenerationhasbeenexaminedinmanypopulation-basedepidemiologicstudies.9-12TheThirdNationalHealthandNutritionExaminationSurvey10wasapopulation-basedsurveyofarepresentativesampleoftheU.S.population40yearsofageandolder.Forthissurvey,thepresenceofage-relatedmaculardegenerationwasbasedonthegradingoffundusphotographs.Theestimatedprevalenceofthediseasewas9.2percentamongcivilian,noninstitutionalizedpersons40yearsofageandolder.Maculardegenerationwasnotedtobemoreprevalentinnon-Hispanicwhites(9.3percent)thaninblacks(7.4percent)orMexicanAmericans(7.1percent).ThesurveyalsoincludedotherHispanicgroups,aswellasAsianAmericansandNativeAmericans,buttheirnumbersweretoosmallformeaningfulcomparisons.Earlyage-relatedmaculardegenerationwasfoundtobemoreprevalentinpersons60yearsofageandolderthaninpersons40to59yearsofage.Latediseasewasonlyfoundinpersons60yearsofageandolder.
Fewstudieshaveevaluatedtheincidenceofage-relatedmaculardegeneration.IntheBeaverDamEyeStudy,13puregeographicatrophy(lateage-relatedmaculardegeneration)was16.6timesmorelikelytodevelopinpersons75yearsofagethaninpersonswhowereyoungeratbaseline.Theincidenceofexudativechangesincreasedfromzeropercentinpersonslessthan55yearsofageto1.8percentinpersons75yearsorolderatbaseline.
Pathophysiology
Thepathophysiologyofage-relatedmaculardegenerationisstillunderinvestigation.Thelocationofthediseasealsoremainsasubjectofdebate.Someinvestigatorsbelievethatthediseaseresidesintheneuralretina(rodsandcones),whereasothersarestudyingtheretinalpigmentepithelium(thelayerofcellsthatprovidenutritiontotherodsandcones).
Potentialriskfactorsforage-relatedmaculardegenerationarepresentedinTable1.10-19
TABLE1RiskFactorsforAge-RelatedMacularDegeneration
Riskfactor
Comments
Age
Theprevalenceofmaculardegenerationincreaseswithage.10-13
Cardiovasculardisease
Age-relatedmaculardegenerationhasaweakassociationwithcardiovasculardisease.14
Laserphotocoagulationasatreatmentforthediseaseislesslikelytobesuccessfulinpatientswhoalsohavehypertension.15
Theriskofdevelopingexudativemaculardegenerationisthreetimeshigherincigarettesmokersthaninnonsmokers.16
Ethnicity
TheThirdNationalHealthandNutritionExaminationSurveyindicatedthatage-relatedmaculardegenerationismoreprevalentinnon-HispanicwhitesthaninblacksorMexicanAmericans.10
Gender
Exudativediseaseisprobablymorecommoninwomenthaninmen.12
Genetics
Geneticpredispositionhasbeeninvestigated,butitsroleisnotdefined.17-19Geneticfactorsappeartobemoredirectlyrelatedtoearly-onsetmaculardegenerations(entitiesthataredifferentfromage-relatedmaculardegeneration).
VisionScreening
TheAmericanAcademyofFamilyPhysiciansrecommendsSnellenacuitytestinginasymptomaticelderlypatients.20TheU.S.PreventiveServicesTaskForcealsorecommendsSnellenacuitytestingfortheelderlybutnotesthatinsufficientevidenceisavailabletorecommendaspecificfrequencyofscreening,specificscreeningquestionsorroutineuseofscreeningophthalmoscopy.21TheAmericanAcademyofOphthalmologyrecommendscomprehensiveeyeexaminationseveryonetotwoyearsinpatientsmorethan65yearsofagewhodonothaveconditionsrequiringintervention.22
Diagnosis
Patientswithage-relatedmaculardegenerationmaycomplainofacutelossofvision,blurredvision,scotomas(areasoflostvision)orchronicdistortionofvision.Allpatientswithvisionlossshouldbereferredtoanophthalmologist;thosewithacutelossofvisionshouldbereferredurgently.
Thediagnosisofage-relatedmaculardegenerationisbasedonthepresenceofvisualdisturbancesandcharacteristicfindingsonophthalmoscopy.
Age-relatedmaculardegenerationisaclinicaldiagnosisthatisusuallybasedonthepresenceofvisualdisturbancesandcharacteristicfindingsondilatedexaminationofthemacula.Thediseaseisusuallyclassifiedasearlyorlate.Latediseasecanbedividedintoatrophic(dry)andexudative(wet)forms.23
Inearlydisease,themaculashowsyellowish-coloredsubretinaldepositscalled"drusen"(Figure1)and/orincreasedpigment.Drusenarethoughttobebyproductsofretinalpigmentepitheliumdysfunction.Inmosteyeswithearlydisease,visualacuityremainsstableformanyyears,andlossofvisionisusuallygradual.
Latedisease(atrophicandexudative)canleadtosignificantlossofvision.Exudativediseaseoccursinonly10percentofpatientswithage-relatedmaculardegeneration,butitisresponsiblefor80to90percentofcasesofseverevisionlossrelatedtothedisease.24
Inatrophicdisease,themaculausuallyshowsareasofdepigmentation(Figure2).Intheexudativeform,fluidcanaccumulateunderneaththeretina,aspigmentepithelialdetachmentsorsubretinalneovascularization(Figure3),andlossofvisionisusuallysudden.
Fluoresceinangiographycanbeusedtoconfirmthediagnosisandtohelpdeterminewhetherapatienthastheatrophicorexudativeformofthedisease(Figure4).Inmostinstances,thismodalityisemployedtodeterminewhetheraneyewithexudativediseaseiseligibleforlasertreatment.
FIGURE2.Maculaofaneyewithgeographicatrophy(lateage-relatedmaculardegeneration).Theyellowish-coloredspotinthecenterofthemacularepresentslossofretinaltissue,retinalpigmentepitheliumandchoriocapillaris.Theunderlyinglargechoroidalbloodvesselsarevisiblethroughthisareaofretinalatrophy.
FIGURE3.Maculaofaneyewithexudativeage-relatedmaculardegeneration.Thebrownish-coloredmembraneinthecenterofthemaculaissubretinalneovascularization.
FIGURE4.Angiogramofaneyewithfluoresceindyeleakingfromasubretinalneovascularmembrane.
TheAmsler'sgrid(Figure5)isaneffectivetoolfordetectingtheprogressionofage-relatedmaculardegeneration.Thepatientisgivenacopyofthegridandisinstructedtofocusoneeyeonthecenterdotinthegridfromadistanceof35cm(12in)withtheothereyecovered;theprocedureisthenrepeatedforevaluationoftheothereye.Thepatientperformsthistestdailyathomeandisinstructedtocallthephysicianiflinedistortionsorscotomasaredetectedandpersistforoneortwodays.
TreatmentswithProvenEffectiveness
Laserphotocoagulationcanslowtheprogressionofvisionlossincertainpatientswithexudativeage-relatedmaculardegeneration.
LaserPhotocoagulation
Laserphotocoagulationhasbeenshowntobeeffectiveinthetreatmentofeyeswithexudativediseaseandwell-defined,or"classic,"subretinalneovascularization.25-27Unfortunately,well-definedsubretinalneovascularizationispresentinonlyabout15percentofeyeswithexudativedisease.Mostpatientshavesubretinalneovascularizationthatis"oc
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