Supernormal Flicker ERGs in Eyes With Central Retinal Vein Occlusion: Clinical Characteristics, Prognosis, and Effects of Anti-VEGF Agent

Purpose: To determine the clinical characteristics, prognosis, and effect of anti-vascular endothelial growth factor (VEGF) agents on eyes with a central retinal vein occlusion (CRVO) with and without supernormal flicker ERG amplitudes. Methods: Forty-eight eyes of 48 patients with a CRVO were studied. Flicker ERGs were recorded from fully dilated eyes with the RETeval system. The amplitudes and implicit times of the fundamental component were analyzed. "Supernormal flicker ERGs" were defined as those whose amplitudes were ≥117% of the unaffected fellow eyes. Results: Ten of the 48 eyes (20.8%) with a CRVO showed supernormal flicker ERGs before the treatment. The difference in the implicit times of these 10 CRVO eyes and those of normal fellow eyes was <4 millisecond. There was a significant correlation between the implicit time delay and the relative amplitude in the 48 CRVO eyes. All 10 CRVO eyes with supernormal flicker ERGs had the nonischemic type of CRVO and tended to have better visual acuities than did the 28 nonischemic CRVO eyes without supernormal flicker ERGs at 12 months after the treatment (P = 0.058). The CRVO eyes with supernormal flicker ERGs had a significant amplitude reduction after a single injection of an anti-VEGF agent. Conclusions: These results indicated that the supernormal flicker ERGs can be a sign of a mild degree of ischemia, and these eyes have a better prognosis. The results also suggest that the supernormal flicker ERG may be caused by changes in the electrical activities of retinal cells following a mild increase in the VEGF levels in eyes with CRVO.