ERG: Reduced dark-adapted b-wave amplitude

What it means

A dark-adapted bright flash electroretinogram in which the b-wave that is of markedly lower amplitude than the associated a-wave.

Flashes will elicit an a-wave with an initial negative deflection followed by a b-wave with positive deflection. This feature refers to a reduction in the amplitude primarily of the b-wave.

Rare diseases that can present with this5

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Electronegative ERG · Electroretinogram: reduced b-wave amplitude · Reduced amplitude of dark-adapted bright flash electroretinogram b-wave · Reduced electroretinogram rod b-wave · Reduced ERG amplitude of b-wave