Abstract
Abstract: :
Purpose: To evaluate the long-term effect of photocoagulation on foveal and macular retinal thickness. Methods: Twenty-five eyes with CSME were re-examined 6 years after initial diagnosis and photocoagulation treatment. The re-examination included visual acuity (ETDRS), biomicroscopy and retinal thickness quantitated with optical coherence tomography (OCT). Retinal thickness of the fovea, where no laser scars are present (within 500 microns from the center), was calculated from horisontal and vertical scans. Macular thickness (within 2 disc diameters from the fovea) was calculated from 6 circular scans centered at the fovea and with a 500 micron increase in radius for each scan. A significant change in retinal thickness was defined as being outside normal range (mean +/- 2SD) of healthy controls. Results: The mean thickness of the fovea and the macula was 216.2 and 246.6 microns for diabetic patients; 189.7 and 242.1 microns for healthy controls. The difference was significant for the fovea (p=0.04) not for the macula (p=0.7). The isolated effect of laser treatment on retinal retinal thickness was evaluated from the temporal retina in eyes with many evenly spaced laser scars (n=7) compared to healthy subjects in the same region, the laser treated regions was significantly thinned (p < 0.001). CSME was present in 16 % (4/25) as defined by biomicroscopy, and the foveal thickness measured with OCT in these eyes were significantly increased compared to healthy controls. 6 additional eyes were thickened significantly in the fovea defined from the OCT, though the clinical evaluation did not identify edema. Mean visual acuity was 0.5 (n=25) and foveal thickness and visual acuity was highly correlated (r=0.78, p<0.001), no correlation was found to HbA1c. Conclusion: At follow-up 6 years after baseline 16 % had CSME as defined by biomicroscopy, however OCT showed that significant foveal thickening was present in 40 % of the eyes examined. The retinal thickness of the macular region was not significantly thickened probably due to retinal atrophy after photocoagulation. OCT seems to be more sensitive in the detection of foveal thickening than the clinical examination in these patients.
Keywords: 432 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 388 diabetic retinopathy