Temporal aspects of the electroretinogram in cone-rod dystrophy.

Twelve patients with cone-rod dystrophy were studied in terms of the temporal aspects of electroretinography (ERG). The peak time of scotopic b-wave was within normal limits in all patients, while the amplitude was reduced in nine patients. The normal peak time of the scotopic-b wave may help explain rod involvement with normal or only slightly elevated final rod thresholds of subjective dark adaptation. The peak time of photopic b-wave and 30-Hz flicker response was normal in four patients and significantly delayed or nonrecordable in eight patients. Such variations of peak time in photopic and 30-Hz flicker ERG may reflect the stage of the disease or may be caused by the different hereditary mode.