Retinal sensitivity in diabetic macular edema, with and without decreased visual acuity

Objective: To compare retinal sensitivity in diabetics with macular edema, with and without decreased visual acuity. Methods: An observational, prospective, cross-sectional comparative study in eyes with diabetic macular edema. The sample was divided into two groups: eyes with visual acuity "">= 0.5 (group 1) and < 0.5 (group 2). Foveal sensitivity was compared between groups (Mann-Whitney's U), stratified according to the center point thickness. Correlations between visual acuity and retinal sensitivity and between visual acuity and macular volume were identified. Results: 81 eyes, 59 from group 1 and 22 from group 2. The mean of retinal sensitivity in group 2 (24.4 +/- 6.9 dB) was significantly lower than in group 1 (30.8 +/- 3.4; p < 0.001). The correlation between visual acuity and retinal sensitivity was 0.49 (r(2) = 0.25), and it was 0.37 in eyes with center point thickness within one standard deviation above the mean and 0.40 in eyes within two standard deviations (p < 0.001). The correlation between visual acuity and macular volume was -0.108 (r(2) = 0.026). Conclusions: Retinal sensitivity in eyes with clinically significant macular edema and decreased visual acuity before treatment was significantly lower than in eyes with normal visual acuity; the difference did not change as center point thickness increased.