The electroretinogram in retinitis pigmentosa.

Examination of electroretinographic (ERG) reports from 70 consecutive patients with retinitis pigmentosa (RP) showed that photopic and scotopic B-wave amplitudes correlated with age and visual acuity, but not with dark adaptation threshold. No appreciable differences in ERG characteristics (including B-wave implicit time) were observed between recessive, dominant, and X-linked cases. However, the ERG findings from one group of patients stood out clearly from the rest, because of normal flicker B-wave implicit times (less than or equal to 32 ms) and large B-wave amplitudes (less than or equal to 100 muV under scotopic conditions). These patients constitute a recognizable subgroup of RP, independent of the mode of inheritance, which is characterized by delimited disease, mild functional symptoms, and a good visual prognosis.