High correlation of scotopic and photopic electroretinogram components with severity of central retinal artery occlusion

PURPOSE: The aim of this study was to determine whether a significant correlation exists between the scotopic and photopic components of electroretinograms (ERGs) and the degree of circulation disturbances caused by a central retinal artery occlusion (CRAO). DESIGN: Observational clinical study. PARTICIPANTS: Sixteen patients with a CRAO (16 eyes). METHODS: The circulatory disturbance in eyes with CRAO was graded as mild (group 1) when the arm-to-retina transmission time was <30 sec and severe (group 2) when the arm-to-retina transmission time was ≥30 sec. Scotopic and photopic ERG components in eyes with CRAO were compared with those in healthy fellow eyes with respect to the degree of circulation disturbance. RESULTS: The scotopic and photopic b-waves were significantly reduced only in group 2, whereas the amplitudes of the photopic negative response (PhNR) of the photopic cone ERGs were significantly reduced in both groups. The amplitudes of each ERG component, except for the a-wave of the mixed rod-cone ERG, were significantly smaller in group 2 than in group 1. CONCLUSIONS: The PhNR was reduced even in group 1 with minimal circulatory disturbance and thus may be a good functional indicator.