THE EXUDATIVE LESIONS IN DIABETIC RETINOPATHY WITH SPECIAL REGARD TO THE HARD EXUDATE

Histochemical techniques were used to study the hard exudates of diabetic retinopathy. Digested flat retinal preparations were examined for correlation between the frequency of these exudates and the degree of retinal capillary changes. The hard exudates in the retinae appear to be composed of a mixture of glycoproteins, lipoproteins and phospholipids with an admixture of neutral fats. Study of flat preparations showed that there was a correlation between the density of the exudates and the degree of capillary changes. There is no histological confirmation in the few circinate areas examined that the capillary lesion is predominantly in the central area of the circinate.