In office electrodiagnostics: what can it do for you of neuro-visual function. 9/6/16 4 assessment...

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Inofficeelectrodiagnostics:whatcanitdoforyou

NathanLighthizer,O.D.,F.A.A.OAssistantProfessor,NSUOCOChiefofSpecialtyCareClinics

ChiefofElectrodiagnosticsClinic

CourseOutline/Objective

• Whatiselectrodiagnosticstesting?• VisualPathway– BasicUnderstanding• VEP• ERG

• Fullfieldflash• Pattern• mfERG

• EOG• ClinicalCases

VisualPathway• Upstream Photoreceptors

Mid-retinallayers

Ganglioncelllayer

NFL/OpticNerve

OpticChiasm

OpticTract

• Downstream LGN

VisualCortex

TheVisualEvokedPotential(VEP)OBJECTIVELYmeasuresthefunctionalityofwhichstructure?

A. PhotoreceptorsB. RPElayerC. GanglioncelllayerD. Nervefiberlayer&

opticnerveE. Entirevisualpathway

WhichofthefollowingisanindicationtoperformaVEP?A. GlaucomaB. TraumaticbraininjuryC. OpticneuritisD. AmblyopiaE. UnexplainedvisionlossF. VFdefectG. Alloftheabove

VisuallyEvokedPotential(VEP)

• AKAVisuallyEvokedResponse(VER)• Flashvs.Pattern

• Measurestheentirevisualpathway• Fromcorneatooccipitallobe

• 3electrodes• Ground• Reference• Measuring->occipitallobe

• 1”aboveinion

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Reference Ground Active

VEPElectrodes

LATENCY(ms)

AMPLITUDE(µv)

• Amplitudeusuallytranslatestotheamountofaxonsconductingalongthevisualpathway

• Latencyusuallytranslatestothemyelinstatusofthevisualpathway

VEP

WhyVEP?

• Manyopticnervediseasesareasymptomaticbecausecentralvisionisnotaffecteduntillateinthedisease1

• Diagnosisandmanagementofopticnervedisordersareoftenbasedonstructuralorsubjectivevisualfieldtests2

1 Glaucoma. American Optometric Association. www.aoa.org2 Prata, Tiago MD, G. De Moraes MD, J. Liebmann MD, R. Ritch, C. Tello MD. (2009). Diagnostic Ability of Fast Transient Visual Evoked Potential

for Glaucoma Assessment [Poster & Abstract] American Academy of Ophthalmology. 128

VEPisanobjective,functional testthatcanhelpdiscriminatebetweenhealthyandglaucomatouseyes2

VEPandGlaucoma:WellDefinedScience

TheVisualEvokedPotentialinGlaucomaandOcularHypertension:EffectsofCheckSize,FieldSize,andStimulationRate

InvestOphthalmol VisSci 24:175-183,1983

“IncreasedpatternVEPlatencywassignificantlycorrelatedwithboththeseverityandlocationofvisualfielddefectsandthedegreeofcuppingandpalloroftheopticdisc.”Theauthorsofthispaperareworldrecognized

electrophysiologyspecialistform NewEnglandMedicalCenterandUniversityofChicago

“ThefindingthatisofclinicalimportanceisthepresenceofabnormallylongVEPlatenciesinsomepatientswithocularhypertension.TheabnormalprolongationofVEPlatencyintheseeyesmayreflectsubclinicalopticnervelesionsthathavenotbeenuncoveredwithothertechniques.”

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AdditionalClinicalPapers

• Repeatabilityofshort-durationtransientvisualevokedpotentialsinnormalsubjects.TelloC,DeMoraesCG,PrataTS,DerrP,PatelJ,SiegfriedJ,LiebmannJM,RitchR.DocOphthalmol.2010Jun;120(3):219-28.Epub2010Jan29.

• ShortDurationTransientVisualEvokedPotentialsinGlaucomatousEyes.PrataTS,LimaVC,DeMoraesCG,TrubnikV,DerrP,LiebmannJM,RitchR,TelloC.JGlaucoma.2011May10.[Epubaheadofprint]

• Short-durationtransientvisualevokedpotentialforobjectivemeasurementofrefractiveerrors.AnandA,DeMoraesCG,TengCC,LiebmannJM,RitchR,TelloC.DocOphthalmol.2011Dec;123(3):141-7.Epub2011Sep20.

dead Suffering Alive

Glaucoma

VEP

OCTHRTGDX

BeforeTreatment

Effect of epigallocatechin-gallate on inner retinal function in ocular hypertension and glaucoma: a short-term study by pattern electroretinogram. Graefes Arch Clin Exp Ophthalmol. 2009 Sep;247(9):1223-33. Epub 2009 Mar 17.

Alive

Glaucoma

VEP

OCTHRTGDX

Alivedead

AfterTreatment


WhyVEP?

• Manyopticnervediseasesareasymptomaticbecausecentralvisionisnotaffecteduntillateinthedisease1

• Diagnosisandmanagementofopticnervedisordersareoftenbasedonstructuralorsubjectivevisualfieldtests2

1 Glaucoma. American Optometric Association. www.aoa.org2 Prata, Tiago MD, G. De Moraes MD, J. Liebmann MD, R. Ritch, C. Tello MD. (2009). Diagnostic Ability of Fast Transient Visual Evoked Potential

for Glaucoma Assessment [Poster & Abstract] American Academy of Ophthalmology. 128

VEPisanobjective,functional testthatcanhelpdiscriminatebetweenhealthyandglaucomatouseyes2

HowtheLXProtocolworks• Lowcontrasttestingdemonstratesdegradationofmagnocellularpathways

• Anearlyindicationofglaucoma

• Highcontrasttestingdemonstratesdegradationofparvocellularpathways

• Anearlyindicatorofcentralvisionlossandissuescausedbyproblemsbeforesignalreachesopticnerve

**patientshouldbetestedwithbestcorrectedvision**

MainIndications

• Glaucoma

•***Glaucomasuspects***

• MultipleSclerosis

• IschemicOpticNeuropathy

• TraumaticBrainInjury

• Amblyopia

• OtherNeuropathies

•Unexplainedvisionloss

•VFdefect

•FDT

ASSESSMENTOFNEURO-VISUALFUNCTION

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VEPReport


VEPReport


VEPReport


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VEPReport


VEPReport


VEPReport

ASSESSMENTOFNEURO-VISUALFUNCTION VEP- Normal

VEP- AbnormalVEP- Abnormal

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VEPabnormal- AsymmetryPatternERG(pERG)

• ERG’sareelectricalsignalsthatareameasureoftheelectrophysiologicalactivityattheretina

• ***Mid-retinallayers,ganglioncelllayer,andnervefiberlayer***

• Objectivelymeasuresretinalfunction**

• ERG’scanhelpimprovesensitivityandspecificityindiagnosingopticneuropathiesandmaculopathies likeglaucomaandmaculardegenerationwhenusedinconjunctionwithothertests

• CanalsohelpthecliniciandifferentiatebetweenretinalandopticnervedisorderswhenusedinconjunctionwithVisualEvokedPotential(VEP).

pERG AdvancedProtocols

1. ConcentricStimulusFields• Drugtoxicity• Diabeticmacularedema• AMD

2. ContrastSensitivity• Glaucoma• Diabeticretinopathy

pERG

1.ConcentricStimulusFields• Stimulusdeliveredat15flips/second• BCVA

• Pt shouldbeproperlyrefractedfor24”

• 24”testingdistance• 100%contrast

• Righteye(OD)thenLeftEye(OS)• 25secondsat24degrees• 25secondsat16degrees

pERG

2.ContrastSensitivity• Stimulusdeliveredat15flips/second• BCVA

• Pt shouldbeproperlyrefractedfor24”

• 24”testingdistance• 85%and15%

• Righteye(OD)thenLeftEye(OS)• 25secondsatHighContrast(Hc)• 25secondsatLowContrast(Lc)

PerNIHandBascom-Palmer:“Inpatientswhoareglaucomasuspects,pERGsignalanticipatesanequivalentlossofOCTsignalbyseveralyears(asmanyas8years).InvestOphthalmol VisSci.2013;54:2346-2352)DOI:10.1167/iovs.12-11026

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dead Suffering Alive

Glaucoma

VEP

OCTHRTGDX

BeforeTreatment


Alive

Glaucoma

VEP

OCTHRTGDX

Alivedead

AfterTreatment


PerNIHandBascom-Palmer:“Inpatientswhoareglaucomasuspects,pERGsignalanticipatesanequivalentlossofOCTsignalbyseveralyears(asmanyas8years).InvestOphthalmol VisSci.2013;54:2346-2352)DOI:10.1167/iovs.12-11026

pERG Indications

• Glaucoma• OpticNeuropathies• Maculopathies

• AMD• Diabeticretinopathy• Diabeticmacularedema• Maculartoxicity

pERG Testing PatternERG(pERG)

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PatternERG(pERG)

NormalPERGResponse

Magnitude,MagnitudeD andMagD/MagRatioarecolorized.

GreenindicateswithinnormallimitsYellowindicatesvaluesareborderlineRedindicatesoutsidenormallimits

3QuickStepsToReportInterpretationSignalQuality– Lookforagreensignal

SinusoidalPeaks– Lookfor3humps

PERGReport– DataTable

Magnitude(uV)isdefinedasthestrengthofthepatient’sresponseatareversalrateof15reversalspersecond.

Largermagnitudesaretypicallygeneratedfromnormaleyes.Smallermagnitudestypicallyindicatepathology.

Asthecontrastleveldropsorthestimulussizedecreases,themagnitudewilltypicallydecrease.


MagnitudeD averagesthesignalwithinthe25secondtesttimeandtakesintoaccountthemagnitudestrengthandthephasevariabilitythroughoutthetest.

Inahealthypatient,thephaseresponsetendstobeconsistentthroughoutthetest.Inthiscase,MagD iscloseinvaluetoMag.

Inapatientwithdisease,thephaseresponsetendstobeinconsistentthroughoutthetest-MagD willbesignificantlyreducedincomparisonwithMag.


MagD/MagRatioisthemostrepeatablemeasurementtest-over-test.Theclosertheratioisto1.0,thelowerthephasevariabilitythroughoutthetest,andthehealthierthepatient’sresponse.Variabilityinphasemayindicatepathology.

MagD/Magratiocanusedtomonitorpatientsovertime.

DataTable

SNR- SignaltoNoiseRatioshowshowstrongthesignalisat15Hzcomparedtonoiseat15Hz.LargernumbersindicatestrongerPERGsignalscomparedtothenoise.

SNRvalueslike5,15,>20showstrongPERGresponse.Numberslessthan2aretypicalofaweakresponse.

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DataTable

Artifactsarecausedbyblinkingorpatientmovement.Theyaredetectedandcounted.Ahighnumberofartifactswilleffecttheamountofdatathatcanbeanalyzed.

Thegoalistohavealownumberofartifacts.Wewantthepatienttobecomfortableandblinkwhennecessary,butnotexcessively.Thegoalislessthan10.IftestsresultsshowArtifactsgreaterthan10,thetestshouldberepeated.

AbnormalPERG

Missing3humps

Yellowindicatesvaluescomparedtonormalareborderline

Redindicatesvaluesareoutsidenormallimits

Operator: Salazar,Andres Eye Centers of Florida, PA #2 - 4771

Comments: - Grating Size: 64 Signature:

Diagnosis is doctor's responsibility. PERG recorded using skin electrodes. (16,12,23,15)Copyright © 2015 Diopsys, Inc. All Rights Reserved. Software Version: 2.18.5118-VX

First Name: Kathryn DOB: 11/16/1979Last Name: Coiro Age: 35Patient ID: Gender: FemaleExam Date: 2015-05-11 OD:+1.50 BCVA: 20/30Exam Time:03:32:10 PM OS:+1.50 BCVA: 20/15

OD Signal Quality:

OS 62dBµV 60Hz noise

Time (ms)0 20 40 60 80 100 120 140 160 180 200

24°

Am

plitu

de( u

V)

-4

-2

2

4

Time (ms)0 20 40 60 80 100 120 140 160 180 200

24°

Am

plitu

de(u

V)

-4

-2

2

4

Time (ms)0 20 40 60 80 100 120 140 160 180 200

16°

Am

plitu

de(u

V)

-4

-2

2

4

Time (ms)0 20 40 60 80 100 120 140 160 180 200

16°

Am

plitu

de(u

V)

-4

-2

2

4

Parameter OD 24° OD 16° OS 24° OS 16°

Magnitude (uV) 3.90 2.45 3.73 2.28

MagnitudeD 3.66 2.31 3.61 2.09

MagD/Mag Ratio 0.94 0.94 0.97 0.92

SNR (dB) 14.3 10.9 14.1 9.6

Artifacts 1 0 5 2

Scott Wehrly, MDOperator: Rivas,Nicole Lake Eye Associates - 9448

Comments: - Grating Size: 64 Signature:

Diagnosis is doctor's responsibility. PERG recorded using skin electrodes. (8,9,7,8)Copyright © 2015 Diopsys, Inc. All Rights Reserved. Software Version: 2.18.5218-VX

Last Name: ALLAIRE DOB: 1/9/1943First Name: SANDA Age: 72Patient ID: 460 Gender: FemaleExam Date: 2015-07-14 OD:+1.00 +0.75 x75 BCVA: 20/20Exam Time:01:16:32 PM OS:+1.00 +0.50 x95 BCVA: 20/20

OD Signal Quality:

OS 61dBµV 60Hz noise

Time (ms)0 20 40 60 80 100 120 140 160 180 200

24°

Am

plitu

de(u

V)

-1

1

2

Time (ms)0 20 40 60 80 100 120 140 160 180 200

24°

Am

plitu

de(u

V)

-1

1

2

Time (ms)0 20 40 60 80 100 120 140 160 180 200

16°

Am

plitu

de( u

V)

-1

1

2

Time (ms)0 20 40 60 80 100 120 140 160 180 200

16°

Am

plitu

de( u

V)

-1

1

2

Parameter OD 24° OD 16° OS 24° OS 16°

Magnitude (uV) 1.01 1.25 1.24 1.17

MagnitudeD 0.75 0.46 0.72 0.54

MagD/Mag Ratio 0.74 0.37 0.58 0.46

SNR (dB) 0.3 2.4 2.3 1.3

Artifacts 1 0 0 0

ApplyingtoYourPracticeVEP

1. Glaucoma&glaucomasuspects

2. Unexplainedvisionloss3. Transientvisionloss4. UnexplainedVF

defects5. UnreliableVF6. Opticneuropathies7. Opticneuritis/MS8. Amblyopia9. TBI

FlashERG1. RP&itsvariants2. Cone

dystrophies&Rodmonochromat

3. Symptoms:• “Night

blindness”• Restricted

peripheralfields

• Colorvisiondeficits

PERG1. Glaucoma&glaucoma

suspects2. UnexplainedVF

defects3. UnreliableVF4. Opticneuropathies5. Maculopathies

1. AMD2. Diabeticmacular

edema3. Highriskmeduse

(Plaquenil)4. GeneralizedDR

In office electrodiagnostics: what can it do for you of neuro-visual function. 9/6/16 4 assessment...

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