Abstract
Purpose: :
To characterize in a two year cohort, prospective, longitudinal study, retinal thickness changes occurring in subjects with type 2 diabetes and mild nonproliferative retinopathy.
Methods: :
Thirty five eyes from 35 patients with type 2 diabetes and mild nonproliferative retinopathy were examined five times, at 6 month intervals, during a two year period with the Retinal Thickness Analyser (Talia Technology, Mevaseret, Zion, Israel). Maps of retinal thickness were obtained in the fovea (500 µm) and in a ring around the fovea (500–1500 µm) and computed using a software programme in order to give measurements of the area, volume and mean/maximum height of the locations where abnormal retinal thickness values were detected. Data from the group of individuals with diabetes were compared with those of a healthy control population (N–50; mean age 52.2±6.1 years; range 40–65).
Results: :
Focal areas of abnormally increased retinal thickness in the perifoveal ring were detected in at least one examination in 26 of the 35 eyes (74%). Ten of the 35 eyes (29%) showed increases in retinal thickness in the perifoveal ring (500–1500 µm) in every one of the 5 visits performed at six–month intervals. Involvement of the central foveal region (500 µm) was present in the 17 of 35 eyes (49%) in one visit and the 5 of 35 (14%) in every visit, only in eyes that had increased retinal thickness in the perifoveal ring. The mean retinal height in the fovea and in perifoveal ring in the eyes with increased retinal thickness were, respectively, 205.5 µm and 213.9 µm, representing an increase of 52.9% and 37.2% over the normal control population, respectively.
Conclusions: :
Focal areas of subretinal macular edema are a frequent finding in mild nonproliferative retinopathy with diabetes type 2.These areas of increased retinal thickness showed reversibility within the 2 year period. Increases in retinal thickness within the perifoveal ring appear to precede the increases in central foveal thickness.
Keywords: diabetic retinopathy • macula/fovea • retina