Quantitative analysis of foveal retinal thickness in diabetic retinopathy with the scanning retinal thickness analyzer

Purpose: This study sought to measure foveal retinal thickness in patients with diabetic retinopathy and to investigate the relationship between foveal thickness and visual acuity, biomicroscopic findings, and angiographic features. Methods: A commercial scanning retinal thickness analyzer was used to measure retinal thickness. A laser slit was projected onto the retina and scanned in 400 milliseconds across the central area of the fundus. The image where the laser slit intersects with the retina was digitally recorded and analyzed. Retinal thickness was measured in 35 patients (35 eyes; patient age, 57 +/- 13 years) with diabetic retinopathy. Patients also were examined by fluorescein angiography and slit-lamp biomicroscopy to detect foveal thickening. Results: Linear regression analysis indicated a significant correlation between foveal thickness and visual acuity (adjusted R-2 = 0.72, P < 0.001). Foveal thickness was abnormal in 6 (100%) of 6 eyes in which foveal thickening was detected with slit-lamp biomicroscopy. Foveal thickness also was abnormal in 9 (31%) of 29 eyes that appeared normal by biomicroscopic examination. Foveal thickness was 136 +/- 65 mu m in 7 eyes without leakage, 175 +/- 35 mu m in 13 eyes with questionable leakage, and 291 +/- 120 mu m in 7 eyes with definite leakage (P = 0.0075). Conclusions: Retinal thickness analysis is shown to be more sensitive than slit-lamp biomicroscopy for detecting small changes in retinal thickness. Retinal thickness analysis may prove to be a useful, noninvasive modality for the development or regression of macular edema.