Functional assessment of early retinal changes in diabetic patients without clinical retinopathy using multifocal electroretinogram

BACKGROUND: We aimed to assess early retinal changes in diabetic subjects without clinical retinopathy using multifocal electroretinogram (mfERG). METHODS: Twenty eyes of 20 diabetic subjects type 2 without retinopathy and 20 eyes of 20 healthy controls of the same age and sex were eligible for our study and underwent mfERG. MfERG responses were recorded; N1-P1 amplitude and P1 implicit time of the 5 rings recorded were measured and analyzed. RESULTS: The reduction in N1-P1 amplitude and the delay in P1-implicit time in type 2 diabetic subjects were statistically significant in most of the assessed rings compared to controls (p < 0.001). Moreover, N1-P1 amplitude was negatively correlated with diabetes duration. However, there was a positive correlation between P1-implicit time and diabetes duration in type 2 diabetic subjects in four out of five rings (p < 0.001). CONCLUSIONS: Our study showed reduced mfERG N1-P1 amplitude and delayed P1-implicit time indiabetic patients without retinopathy compared to normal controls. Implicit time andamplitude were significantly affected by diabetes duration. These results propose a valuable role of mfERG in evaluating the expected neuroretinal dysfunction before the clinical development of diabetic retinopathy. Early detection of functional abnormalities indicates that the patients need more tight medical control of diabetes. More well-designed studies are needed to assert upon these results.