Changes of electroretinogram without improvement of retinal circulation after radial optic neurotomy for central retinal vein occlusion. ERG changes after RON for CRVO.

PURPOSE:To evaluate the efficacy of radial optic neurotomy (RON) on retinal function in patients with central retinal vein occlusion (CRVO). METHODS:Ten eyes of 10 patients with CRVO underwent pars plana vitrectomy and RON. Standardized combined electroretinograms (ERGs) to full-field bright-flash stimuli were recorded preoperatively and, 3 months postoperatively. The best-corrected visual acuity and foveal thickness were also determined, before and 3 months postoperatively. RESULTS:The mean best-corrected visual acuity and mean foveal thickness were both significantly improved after vitrectomy and RON. The mean amplitudes of a- and b-waves did not change significantly, but the mean b/a wave ratio was increased significantly after vitrectomy and RON. An improvement of the b/a ratio was observed in six eyes, however, an improvement of retinal circulation was confirmed on postoperative fluorescein angiograms in two of these six eyes. CONCLUSIONS:Significant improvements were observed in the b/a wave ratio of the standard combined ERGs after surgery in eyes with CRVO. The improvement of retinal function was most likely due to improved oxygenation of retina caused by vitrectomy and not by RON.