Abstract
Diabetic retinopathy (DR) significantly impacts vision and quality of life in diabetic patients. This study aimed to evaluate multifocal electroretinogram (mfERG) changes in long-term type 1 diabetes mellitus (T1DM) patients without clinical signs of DR to detect early functional retinal alterations. A prospective observational study was conducted involving 46 eyes from 23 T1DM patients and 46 eyes from 23 age-matched healthy controls. mfERG was assessed using the RETI-port/scan21 following ISCEV protocols. T1DM patients exhibited significantly decreased mfERG response amplitude density (RAD) in all the retinal rings except R2 (R1, p = 0.003; R3, p = 0.006, R4, p = 0.023 and R5, p = 0,027) and in the inferior quadrants Q2 and Q3 (p = 0.030 and p = 0.004, respectively) compared to controls. Minimal differences in implicit time (IT) were observed between both groups. Age correlated positively with different ITs, and HbA1c showed a significant negative correlation with various RADs. T1DM patients show early retinal dysfunction, as indicated by reduced RAD in mfERG, even without clinical signs of DR. These findings highlight the importance of early functional testing and metabolic control in preventing DR progression. RAD may serve as a subclinical marker of bipolar cell and photoreceptor damage in long-term T1DM patients prior to the onset of clinical DR.