Contrast sensitivity and its determinants in people with diabetes: SN-DREAMS-II, Report No 6.

PurposeTo assess contrast sensitivity (CS) and to elucidate the factors associated with CS among subjects with type 2 diabetes in a cross-sectional population-based study.Patients and methodsSubjects were recruited from a follow-up cohort, Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular genetics Study (SN-DREAMS II). Of 958 subjects who were followed up in SN-DREAMS II, a subset of 653 subjects was included in the analysis. All subjects underwent a comprehensive eye examination, which included CS assessment using the Pelli-Robson chart. The cross-sectional association between CS and independent variables was assessed using stepwise linear regression analysis. A P-value of <0.05 was considered statistically significant.ResultsThe mean age of the study sample was 58.7±9.41 (44-87) years. Mean CS of the study sample was 1.32±0.20 (range: 0-1.65) log units. CS was negatively and significantly correlated with age, duration of diabetes, hemoglobin level, vibration perception threshold (VPT) value, albuminuria, best corrected visual acuity (BCVA), refractive error, total error score (TEM) of FM 100 hue test, and mean retinal sensitivity. In multiple regression analysis, after adjusting for all the related factors, CS was significantly associated with BCVA (β=-0.575; P<0.001), VPT (β=-0.003; P=0.010), severity of cataract (β=-0.018; P=0.032), diabetic retinopathy (β=-0.016; P=0.019), and age (β=-0.002; P=0.029). These factors explained about 29.3% of the variation in CS.ConclusionAmong the factors evaluated, differences in BCVA were associated with the largest predicted differences in CS. This association of CS with visual acuity highlights the important role of visual assessment in type 2 diabetes.