Changes in visual function in long‐term type 1 diabetic patients without diabetic retinopathy using full‐field electroretinogram

Abstract

Aims/Purpose: To evaluate changes in retinal function in type 1 diabetic patients (DM1) without diabetic retinopathy (DR) using full‐field electroretinogram (ffERG).Methods: Forty‐six eyes of long term DM1 patients without DR were compared to 46 eyes of healthy subjects. None of them had any ophthalmic pathology that could alter the findings. All the subjects were evaluated following the standardized international ISCEV guidelines. The amplitude and implicit time (IT) of each component of scotopic and photopic responses were evaluated, along with interocular differences.Results: There were no age differences between groups. A significant increase in the rod response IT of the DM1 patients was observed compared to the control group (p = 0.0012). The b wave amplitude in the mixed response was statistically reduced in the DM1 group compared to the control group (p = 0.03). There was an increase in the IT of both a and b‐wave in the mixed response at the higher stimulus intensity in the DM1 compared to control (p = 0.023 and p = 0.004 respectively). b/a rate was similar in both groups. The oscillatory potentials (OPs) showed an increase in their IT (p = 0.008) and a decrease in OP2 amplitude in the DM1 group. Cone mediated b‐wave was diminished in DM1.Conclusions: Full‐field electroretinogram enables the detection of subclinical findings in long term DM1 patients suggesting the existence of neurodegeneration prior the appearance of DR, particularly in the rod system and OPs.