ERG Flashcards
What are the 3 components of a full field ERG
a wave - photoreceptors (negative)
b wave - inner retinal cells - muller and bipolar cells (positive)
c wave - RPE and photoreceptors
What are the adaptation types in full field ERG
Dark adapted DA 0.01
Dark adapted DA 3.0
Dark adapted 10.0/30.0
Light adapted (LA) 3.0
Light adapted (LA) 30Hz flicker
What is DA 0.01
Rod specific
B-wave originates from on-bipolar cells
Inner retinal response - cannot differentiate if the problem is at the level of the photoreceptor or inner retina
What is DA 3.0
Mixed cone/rod response
a wave and b wave
What is dark adapted 10.0/30.0
a wave primarily reflexts photoreceptor funciton - localise dysfunction to photoreceptor/inner retina
Interprest along with DA 0.01
If both reduced - photoreceptor dysfunction
If DA 0.01 reduced but normal 10.0/30.0 - inner retinal dysfunction
A DOWN B UP
What is LA 3.0
Photopic single flash ERG
a wave cone photoreceptors
b wave - on and off bipolar cells
LA 30Hz flicker
Delat indicates heneral cone proble
No delay but reduced amplitude - focal cone problem
What is the multifocal ERG
Topographical map of central retinal function
Central 30 degrees / central cones
Light adapted test
For central vision problems or outer retinal problems
What is pattern ERG
Stimuli - alternating contrast
Normal a wave and reduced b wave (negative ERG with b wave lower than a wave
CRAO
CRVO
Congenital stationary night blindness
X linked juvenile retinoschisis
Negative ERG seen in what conditiosn
XCCC
CRAO
CRVO
Congenital stationary night blindness
X linked juvenile retinoschisis
First step for interpreting ERG
DA 0.01
Primarily just b wave
If reduced then this is a rod photoreceptor or rod inner retinal problem
Second step
Da 10.0/30.0
If a wave reduced - photoreceptor problem - if DA 0.01 was reduced - rod problem
If a wave normal and b wave reduced - inner retinal problem
Third step
30Hz flicker
If delay - general cone problem
If no delay but reduced amplitude - focal cone problem
