Focal macular electroretinograms before and after removal of choroidal neovascular lesions

PURPOSE. To evaluate the changes in focal macular electroretinograms (fmERGs) after surgical removal of choroidal neovascular (CNV) lesions. METHODS. Fourteen patients (14 eyes) with subfoveal or juxtafoveal CNV associated with age-related macular degeneration and 1 patient with idiopathic CNV underwent vitrectomy and removal of the lesions. fmERGs elicited by a 15° stimulus were recorded before and 3 months after surgery. Optical coherence tomography (OCT) was performed to measure the foveal and parafoveal thickness before and 3 months after surgery. RESULTS. Preoperative fmERGs were markedly reduced in all eyes. The mean amplitude of the b-wave in 15 eyes recorded 3 months after surgery increased significantly (P = 0.0022, Wilcoxon signed rank test). In all eyes except two with nearly nonrecordable a- and b- waves, the mean b-wave-to-a-wave ratio after surgery increased significantly in all eyes (P = 0.0330, Wilcoxon signed rank test). The percentage increase in the b-wave amplitude correlated significantly with the percentage decrease in the mean parafoveal retinal thickness (r = 0.688, P = 0.0076). CONCLUSIONS. The decreased macular ERGs were partially recoverable in the early postoperative period. The decreased retinal edema after surgery may have contributed to this recovery.