Macular function in prediabetic and diabetic omani adults: A microperimetric evaluation

Purpose. To assess if functional visual loss preceded structural changes or vice versa in diabetic patients by evaluating the macular function in prediabetic patients and in diabetic patients with varying grades of retinopathy and comparing the findings with those of age-matched healthy controls by means of microperimetry. Methods. Retinal sensitivity, fixation pattern, and test response were evaluated in 25 prediabetic patients (50 eyes), 25 diabetic patients (50 eyes), and 25 age-related normal nondiabetic patients (50 eyes) using Nidek microperimetry. The diabetic patients were classified into 3 groups on the basis of clinical and fundus fluorescein angiographic evidence: group 1 = no clinical or angiographic evidence of retinopathy, group 2 = background retinopathy only, group 3 = with macular edema. Classification of retinopathy was based on Early Treatment Diabetic Retinopathy Study standards. Statistical analysis was conducted by Fisher exact test. Results. In diabetic patients, 20 eyes (40%) had no clinical or angiographic evidence of retinopathy, 13 eyes (26%) had background changes, and 17 eyes (34%) had macular edema. Statistically significant difference in the fixation pattern, test response, and retinal sensitivity was noted in the diabetic and the prediabetic patients when compared to the controls. Conclusions. Significant loss of macular function in the eyes of prediabetic subjects was noted. These preliminary findings probably support the hypothesis that neurodegeneration precedes microangiopathy.