Comparison of Photopic Negative Response of Electroretinogram in Non-Diabetic and Diabetic Indian Subjects

Abstract

Purpose: To determine how photopic negative response (PhNR) of elctroretinogram (ERG) is affected in diabetes subjects with and without retinopathy and to compare it with the controls in Indian subjects. Methods: Fifty-nine subjects were divided into control, diabetes with no retinopathy, non-proliferative diabetic retinopathy (NPDR), and proliferative diabetic retinopathy (PDR) groups. All subjects photopic ERG parameters were measured using short duration (4 milli seconds) red flashes (1.7 cd..m-2 ) on blue background (8cd. m-2 ). Photopic ERG parameters, a-wave amplitude, a-wave implicit time, b-wave amplitude, b-wave implicit time and PhNR amplitudes were measured in all the subjects. Results: 25 eyes of 14 subjects with diabetes, 37 eyes of 30 subjects with various stages of diabetic retinopathy and 24 eyes of 15 age matched control subjects were studied. There is a significant reduction (p 0.05) in photopic ERG parameters between controls and diabetic subjects and also between NPDR and PDR subjects. Conclusion: PhNR amplitude along with the other photpic ERG parameters is useful for the evaluation of inner retinal function in cases of diabetic retinopathy when compared to early stages of diabetes.