Ocular Disease III: Lecture 3: Electrodiagnostics Flashcards
- ERG
- VEP
- mfERG
- EOG
- PERG
- Checks Retinal Function Health a. ERG response mostly comes from Photoreceptors and Bipolar cells (OUTER RETINA)
b. *Most important test in her opinion - Checks Health of VISUAL SYSTEM
- Health of Foveal Cones
- Health of RPE
- Health of Ganglion/Amacrine Cells (non linear and Spiking)
ERG Wave
- the First Dip (A-WAVE): Due to what cells?
- The bumps in the middle
- The peak?
- Photoreceptors
- Oscillatory Potentials (AMACRINES)
- B-Wave (BIPOLARS, GLIA)
Which wave would be SLOWER in time but LARGER in size?
- SCOTOPIC WAVE
How is the test done?
- Dilate
- Ground Electrode attached to EAR
- Dark Adapt
- Insert Lenses
- Run both eyes at ONE (SCOTOPIC TESTING)
- LIGHT ADAPT
- Run PHOTOPIC TESTING
- Check Fundus
When performing the ERG, if you were using a DIM LIGHT, what wave(s) would you expect on the graph?
- ONLY a B WAVE! (so not big enough to get an A Wave)
Everyone w/a NORMAL PERG, will have a PEAK when
- At 50 msec (P50) (stimulus is 50% light and 50% dark at every moment)
- When is a PERG good to use on a patient?
2. What other diseases?
- When they can’t do a VF
- NERVE TOXICITY, (Glaucoma…pts that cant do other functional tests)
* Usually used in Conjunction w/a VEP!
VEP
- What Electrical Potential does it measure?
- Check sizes are about what?
a. Gives response of what? - Does it localize the problem?
- At The OCCIPITAL CORTEX created by stimulus to the RETINA, especially the fovea. (Electrodes on the back of the head)
- 20/200 and 20/50 (pt fixates in the center)
a. of the ENTIRE PATHWAY - NO! It just tells us that there’s a problem somewhere.
EOG
- Dark Trough = ?
- Normal ARDEN Ratio is usually WHAT? (KNOW!)
- She said to go with what Arden Ratio?
- Patient looks back and forth..(eye acts like a battery, w/+ and - electrode on each side of the eye)
- ARDEN Ratio
- usually greater than 2/1
- 1.75! (Ratio from the number you get in the light, and the number you get in the dark)
1st Thing to ask EVERY PATIENT before doing an ERG?
- Is it PROGRESSIVE or STATIONARY
Stationary: Examples
- Born w/bad vision or early on has poor vision and stays the same
CSNB, Oguchi Disease,
Fundus Albipunctatus
Fleck Retina of Kandori
Achromatopsia
and LEBERS (Congenital Amarosis)
CSNB
- Genetic? (think who)
- What happens to the ERG?
a. ERG will be what?
- X-linked (think BOYS more likely)
* Normal Looking Retina (No RPE Changes)
* No photoreceptor to Bipolar Signaling - Decreased B Wave (Bipolar Cell), but Intact A wave (Photoreceptors)
* How they’re diagnoses
a. Will be Electro Negative
Lebers
- Not the same as what?
- Blind since when?
- Genetics?
- What does the retina look like?
- ERG?
- Lebers Optic Atrophy
- from Birth (FC to LP)
- Autosomal Recessive
- Normal, pigment changes w/aging (starts normal but starts to change as they get older)
- No/little measurable ERG
Progressive Retinal Dystrophies
- What one’s are Central? (5)
- Cone Dystrophy
- Stargardts
- Best Disease
- Pattern Dystrophies
- Macular Dystrophies
2 other questions to ask?
- dark or light problem, or both?
a. Scotomas…? - Who else in your family has this?
What are the first two things you would think of as a differential for night blindness?
- Cataracts and Glaucoma
- Inflammatory Disorders: Central or GENERAL?
- ALL GENERAL
(Birdshot, MEWS, AZOOR, ORV (Histoplasmosis common), Behcet’s Disease
Toxic Retinopathy: What major drug?
- PLAQUENIL
Best’s Disease
- 2 Types: When are they each diagnosed?
- Appearance of the Macula?
- WHAT TEST is ABNORMAL?
- What is the SAME GENE?
- AUTOSOMAL DOMINANT RPE Disorder (Childhood)
a. Vision loss not bad w/best until LATE STAGES (Age 50) - EGG Appearance
- EOG (ERG: A and B wave are normal, but c wave is reduced)
- PATTERN DYSTROPHY VITELLIFORM
Best Disease: 5 Stages
- Stage 1
- Stage 2
- Stage 3
- Stage 4
- Stage 5
- Normal fundus. Abnormal EOG
- EGG YOLK: sunny side up Vitelliform Lesion
- Pseudohypopyon (partly absorbed)
- Vitelliruptive (scrambled Egg)
- End Stage. Scarring, CNV, ATROPHY
2 Disorders that Best Disease tends to be confused with?
Central disorders that cause Scarring or Lipofuscin Changes (Mostly Stargardts)
Stargardts Disease
- AKA?
- Genetics?
- What age does this normally present?
- ERG Changes are correlated with change in what? Is this common?
- A and B wave amplitudes. What happens to them?
- What test is non-detectable, even though VAs are good?
- Mutations in what gene?
- ERG
- Fundus Flavimaculatus
- Autosomal Recessive
- 10-20 yrs
- In Fundus. It’s rare in early disease, except mfERG
- They decrease
- PERG
- ABCA4 gene
- ERG: centrally decreased…
* 20/30 is a best case scenario, but by age 30, they’re low vision patients (20/200)
Retinitis Pigmentosa
- Most common hereditary disorder of what?
- Needs to be on your RADAR for every case of what?
- Major patient complaints
- Is Central Blindness common?
- of RODS
- Night blindness
- PHOTOPHOBIA, Reduced Fields, and Nyctalopia (night blindness)
- No. RARE. But can come later on in late disease
Retinitis Pigmentosa
- Triad
- Arteriole Attenuation
- Bone Spicules
- Optic Atrophy
Toxic Retina: Plaquenil
- What is this taken for?
a. Where does it accumulate? - 4 Side effects from High Dosages
- NEW STANDARD OF CARE?
- RA and Lupus
a. Choroid, CB, RPE (binds melanin) - a. Attenuated Vessels
b. Depressed Peripheral Fields
c. Impaired Central Vision
d. Pigment changes (Bull’s eye macula) - mfERGS (for high risk patients: High daily doses, progressive vision loss, kidney issues, long term treatment)
New Exam for Plaquinil
1 What are the 3 BIG THINGS to do?
- VA; VF (Central: 10-2), and HD-OCT and/or mfERG/ or FAF
MEWS (white dot)
- UNI/BI?
- usually have what?
- Associated with what?
- ERG will show what?
- USUALLY UNILATERAL
- Vitritis but self limiting
- HLA-B51
- Decreased Photoreceptor over time
AZOOR
- Acts like MEWS (a White dot) but with no what?
- Blindspot?
- Uni/bi?
- in whom?
- with no actual dots
- Larger
- Uni
- young women
usually gets better over time
AMPPE
- common?
- UNI/BI?
- very uncommon
- Bilateral
* HLA-B27
Short term, active phase resolves quickly
MC (Multifocal choroiditis)
- Uni/bi?
- type of uveitis
- Short/long term?
- Bi
- Panuveitis
- middle aged women; LONG TERM
* anterior uveitis in 50%
Birdshot
- Typically presents with what?
- uni/bilateral lesions
- ERG in birdshot
- floaters (vitritis)
- bilateral creamy lesions
- usually found disc to equator and progresses inward
can lead to scarring and atrophy
HLA-A29
- gets more electronegative over time; B wave issues more common in birdshot