ERG: Reduced dark-adapted b-wave amplitude Reduced ERG amplitude of b-wave UMLS:C4021561 HP:0007984 Electronegative ERG 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. Reduced amplitude of dark-adapted bright flash electroretinogram b-wave Electroretinogram: reduced b-wave amplitude Reduced electroretinogram rod b-wave Abnormal amplitude of dark-adapted bright flash electroretinogram