HbA1c and retinal sensitivity in diabetics using microperimetry

PURPOSE: The purpose of this study was to determine the relationship between HbA1c values and retinal sensitivity at central 10° using the MP-1 microperimeter. METHODS: A prospective study was carried out on 32 healthy subjects (control group) and 60 diabetic patients. The diabetic patients were divided into 2 groups. Group 1 comprised of 30 patients without diabetic retinopathy (DR) and group 2 had 30 patients with mild non-proliferative DR. A full-threshold microperimetry of the central 10° of retina (the macula) was performed on all subjects, utilizing 32 points with the MP-1. The relationship between light sensitivity and HbA1c value was calculated using linear regression analysis. RESULTS: Total mean sensitivity at 10° for group 1 without DR, group 2 with mild NPDR and control group were 18.67 ± 0.83, 17.98 ± 1.42 and 19.45 ± 0.34 (dB), respectively. There was a significant difference in total mean retinal sensitivity at 10° between the 3 groups (F(2,89) = 18.14, p = 0.001). A simple linear regression was calculated to predict HbA1c based on retinal sensitivity. A significant regression equation was found (F(1,90) = 107.61, p = 0.0001, with an R(2) of 0.545). The linear regression analysis revealed that there was a 0.64 dB decline in mean retinal sensitivity within the central 10° diameter with an increase of 1 mmHg of HbA1c. CONCLUSION: Retinal sensitivity at the central 10° of the macula is affected by changes in HbA1c values.