Subclinical diabetic macular edema and mild non-proliferative diabetic retinopathy - Data correlation with the retinal thickness analyzer (RTA)

Purpose: To measure, using the retinal thickness analyzer, the mean foveal thickness and the mean perifoveal thickness values on patients suffering from mild non-proliferative diabetic retinopathy without clinically detectable macular edema (classified by the ETDRS study), and compare them with healthy individuals. Methods: Observational analytical retrospective case-controlled study, on a sample of 79 eyes (39 affected and 40 control). The sample was selected from by exams previously taken at Centro Brasileiro de Cirurgia de Olhos (CBCO) (from 1999 to 2003) stored in the retinal thickness analyzer. The control group was selected according to specific criteria. The affected group was formed according to the research inclusive and exclusive criteria. The results were submitted to statistical tests for reliability. Results: In the control group the values obtained for mean foveal thickness were around (mean=147.4 micra +/- 15.4 micra standard deviation) and for mean perifoveal thickness were around (mean=193.8 micra +/- 24.6 micra standard deviation). Patients with mild non-proliferative diabetic retinopathy presented foveal thickness around (mean=198.9 micra +/- 48.3 micra standard deviation) and perifoveal thickness around (mean=194.2 micra +/- 26.4 micra standard deviation). Conclusion: An increase of mean foveal thickness on diabetic patients who have not shown clinical signs of macular edema was noted, which was proved by statistical tests. Such results are similar to the values found in medical literature.