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VisuallyEvokedPoten2alreportby:SharonVaswani VEP

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WhatisaVisuallyEvokedPotenal

(VEP)?

AVEPisanevokedpoten.alcausedbyavisuals2mulus,suchasanalterna.ngcheckerboardpa9ernonacomputerscreen.Responsesarerecordedfromelectrodesthatareplacedonthebackofyourheadandareobservedasareadingonanelectroencephalogram(EEG)Theseresponsesusuallyoriginatefromtheoccipitalcortex,theareaofthebraininvolvedinreceivingandinterpre.ngvisualsignals

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WhenistheVEPused?

AdoctormayrecommendthatyougoforaVEPtestwhenyouareexperiencingchangesinyourvisionthatcanbeduetoproblemsalongthe

pathwaysofcertainnervesSomeofthesesymptomsmayinclude:

Lossofvision(thiscanbepainfulornon-painful);Doublevision;Blurredvision;Flashinglights;Altera.onsincolorvision;orWeaknessoftheeyes,armsorlegs

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WhenistheVEPused?

ThesechangesareoOentoosubtleornoteasilydetectedonclinicalexamina.oninthedoctor'ssurgeryIngeneralterms,thetestisusefulfor

detec.ngop2cnerveproblemsThisnervehelpstransfersignalstoallowustosee,sotes.ngthe

nerveallowsthedoctortoseehowyourvisualsystemrespondstolight

Thetestisalsousefulbecauseitcanbe

usedtocheckvisioninchildrenand

adultswhoareunabletoreadeyecharts

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WhatdoestheVEPdetect?

TheVEPmeasuresthe.methatittakesforavisuals.mulustotravelfromtheeyetotheoccipitalcortexItcangivethedoctor

anideaofwhetherthenervepathwaysareabnormalinanyway

Forexample,inmul.plesclerosis,theinsula.nglayeraround

nervecellsinthebrainandspinalcord(myelinsheath)canbe

affected

Thismeansthatittakeslonger.meforelectrical

signalstobeconductedtotheeyes,resul.nginabnormalVEPAnormalVEPissensi.vein

excludingalesionoftheop.cnerve,alongits

pathwaysintheanteriorpartofthebrain

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TheVEPisanimportantdiagnos.candprognos.ctoolforpredic.ngthe

developmentofvisioninprematureorsmallforgesta.onalageinfantswithgeneralized

delaysinmotordevelopment

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Whattheresultsofthetestmay

show...

TheVEPispar.cularlyusefulindetec.ngpastop2cneuri2s.Thisreferstoinflamma2onoftheop2cnerve,associatedwithswellingandprogressivedestruc.onofthesheathcovering

thenerve,andsome.mesthenervecableAsthenervesheathisdamaged,the.meittakesforelectricalsignalstobeconductedtotheeyesisprolonged,resul.nginanabnormalVEPThis

maybeseeninmul.plesclerosis-oneofthemostcommoncausesofop.cneuri.s(asabove)AbnormalVEP'sareseeninmul.plesclerosispa.entsduetothepresenceofop.cneuri.s

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Tumoursorlesionscompressingtheopcnerve-iftheop.cnerveiscompressed,thepathwayforconduc.onisaffectedandanabnormalVEPisseen

Glaucoma-pa.entswhosufferfromglaucomahaveincreasedintraocularpressure(iepressureinsidetheeye)Thiscanresult

indamagetotheop.cnerve,leadingtoprolongedVEPs Ocularhypertension(highpressure)-thisreferstoanysitua.on

inwhichthepressureintheeyeishigherthannormalThereare

nosignsofglaucoma,butpa.entsmaybeatincreasedriskof

developingglaucomalaterinlife

OpcNeuropathy-thiscanbeduetodamageoftheop.c

nervefromanumberofcauses,including:ablockageofthe

nerve'sbloodsupply,nutri.onaldeficiencies,ortoxinsAs

thenerveisdamaged,electricalsignalsdonotconductproperlyExamplesincludediabetes(advancedstages),toxic

amblyopia

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TheinfantsVAises.matedbydeterminingthe

smalleststripewidththats.mulates

preferen.alfixa.on

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