Assessment of functional changes in long‐standing type 1 diabetic patients without diabetic retinopathy with multifocal electroretinogram

Abstract

Aims/Purpose: To early evaluate local functional changes in the retina of long‐standing type 1 diabetic patients (DM1) without diabetic retinopathy (DR) through the use of multifocal electroretinogram (mfERG).Methods: 46 eyes of 46 long‐standing DM1 patients without DR and 46 eyes of 46 healthy subjects were studied. Eyes with previous history of ocular diseases that could alter mfERG results were excluded. Participants were evaluated using mfERG with RETIscan recording system by Roland, following the standardized international guidelines of the International Society for Clinical Electrophysiology of Vision (ISCEV). The electrical density and implicit time of each first‐order response (K1) were measured and analysed in both study groups, as well as interocular differences.Results: Mean age was 48.00 ± 9.77 years in the DM1 group and 51.69 ± 4.75 years in the control group. The average duration of diabetes was 29.19 ± 7.85 years and the mean HbA1c level was 7.33 ± 0.9%. No statistically significant differences were found between the ages of the groups. In mfERG, a statistically significant decrease in P1 response density was recorded in the R1 ring (central 0°‐2°) in the DM1 group compared to the control subjects (p = 0.029). Additionally, the R1/R2 ratio was significantly lower in diabetic patients than in the control group (p = 0.009). There was also a statistically significant increase in the implicit time of P1 in the R5 ring (central >15°) in the DM1 group compared to the control group (p = 0.027). No interocular differences were found in the DM1 group. Regarding quadrant analysis, no statistically significant differences were found in the DM1 group.Conclusions: In patients with long‐standing DM1 without RD, mfERG enables the detection of subclinical and local findings, which indicates the presence of a pre‐existing neurodegenerative process prior to the onset of retinal lesions.