Morphologic and Functional Correlation in Diabetic Macular Edema

Abstract

Abstract: : Purpose:To determine if correlation between morphologic features and macular functional response exists in patients with non-proliferative diabetic retinopathy and focal clinically significant macular edema, and to correlate these morphologic and functional measurements with the visual acuity. Methods: A prospective, non interventional case series study was conducted. Patients with clinical and angiographic diagnosis of non-proliferative diabetic retinopathy and focal clinically significant macular edema (f CSME) were included. Macular thickness was determined by Optical Coherence Tomography (OCT) and measurement of macular function was obtained through multifocal electroretinography (mERG) performed in 61 points distributed in five concentric rings, considering only the seven central points included in the two central rings. Results: Twenty six eyes of thirteen patients were evaluated. Average age was 60.5 years (SD± 9.8). Nine patients were female (69.23%). Best corrected visual acuity (logMAR) in average was -0.34 (SD± 0.28) 0 to -1. Average macular thickness was 264.2 µm (SD± 36.23); macular central thickness 235.7 µm (SD± 61.3) and the average b-wave amplitude measured at the two central rings 25.07mV (SD±7.96). Pearson test showed no statistically significant correlation neither between average macular thickness and average b-wave amplitude (R = -0.56), nor between b-wave amplitude and visual acuity (R = 0.28). Statistically singificant negative correlation was found between visual acuity and macular central thickness (R = -0.48, p=0.002). Conclusions: Linear regression analysis showed that change in macular thickening at the central fovea can explain the 20% of the variations in visual acuity reported on Log-mar scale.

Keywords: retina • diabetic retinopathy • electroretinography: clinical