Rod photoreceptor transduction is affected in central retinal vein occlusion associated with iris neovascularization

Patients with central retinal vein occlusion who later develop iris neovascularization show changes in the amplitude, the timing, and the sensitivity of the electroretinogram beta wave. We determined the extent to which rod photoreceptor dysfunction contributes to these changes by recording single-flash electroretinograms from both eyes of 52 patients with unilateral central retinal vein occlusion and fitting the leading edges of alpha waves with a model of rod phototransduction. Eyes with central retinal vein occlusion showed reductions in photoreceptor gain but no changes in photoreceptor amplitude when compared with the fellow eyes. The reductions were larger in eyes that developed iris neovascularization and were predictive of this complication. Photoreceptor gain reductions accounted for only part of the beta-wave timing delays and sensitive loss; the remainder is attributed to functional loss in the inner nuclear layer.