Electroretinography and macular edema in diabetic retinopathy

Abstract

Abstract Purpose To examine the electrophysiological symptoms in patients with preproliferative and proliferative diabetic retinopathy (PPDR, PDR) with macular edema (ME). Methods 24 patients with type II diabetes were investigated. OCT presented a focal, diffuse and clinically significant ME. ISCEV standard ERG methods, as well as chromatic macular and multifocal ERG (mf ERG), long‐duration flash ERG, pattern ERG (PERG) and retinocortical time (RTT) were performed. Results ERG changes were similar in PPDR and PDR with ME. Full‐field and flicker ERG were normal or subnormal depending on the localization of the pathological process in retina. The amplitude and interpeak latency of OPs were significantly changed. A different amplitude reduction of macular chromatic ERG to red, green and blue stimuli and prolonged b‐wave latency to green and blue stimuli were revealed. The retinal density of bioelectrical activity and amplitudes of N1, P1 components were decreased. A long‐duration flash ERG showed normal or subnormal ON‐response and diminished OFF‐response. The pathological macular and mf ERG were attended by pathological full‐field and flicker ERG in certain cases. N95 component oPERG was changed in amplitude and implicit time. The RTT was prolonged in most of the patients. Conclusion The ERG signs point to extent inclusion in pathological process of different retinal structures and layers. PERG and RTT changes indicate initial functional damage of the optic nerve. It is necessary to compare OCT and ERG data for understanding of mechanisms of visual disturbance in DR. The number of cases in which clinical and functional signs did not correspond to each other must be a subject to deep analysis before choosing a medical or laser treatment.