Rod and Cone a-Waves in Central Retinal Vein Occlusion

Abstract

To evaluate rod and cone a-waves in cases with unilateral central retinal vein occlusion (CRVO). Scotopic and photopic flash electroretinograms (ERGs) were recorded in seven patients aged 54-84 with unilateral hemorrhagic CRVO. Rod and cone a-waves were analyzed using photoreceptor models, and Rm(p3) (maximum a-wave amplitude) and S (sensitivity) were calculated. Decreased rod log S was found in all seven cases, and decreased cone log S was found in five cases. In only one case, rod log S in the fellow eye was decreased. The alterations in rod and cone log Rm(p3) were smaller than those in rod and cone log S. Of three cases in which ERGs could be recorded again after a certain follow-up period, rod log S and cone logS became larger in two cases and smaller in one case. The change in the phototransduction cascade was confirmed not only in rods but also in cones in five of our seven cases of CRVO. The ERG findings might reflect the functional change in the photoreceptor layer after the onset of CRVO.