The ultrastructural alterations in rat corneas with experimentally-induced diabetes mellitus

Objectives: To examine the ultrastructural changes of rat comeas in streptozotocin (STZ) induced diabetes mellitus and the follow-up insulin treatment. Methods: Sprague-Dawley type rats was used for experimental procedures during the period from January to April 2003 at Baskent University, Ankara, Turkey. Rats were studied in 4 groups; group 1: controls, group 2: sham controls (single dose IV sodium citrate), group 3: STZ-induced diabetes mellitus (single dose 45 mg/kg STZ intravenously), group 4: diabetes mellitus + insulin treatment (8 U/day). Results: We observed degenerative changes in the epithelial layer, stromal keratocytes and endothelial cells in diabetic group. In contrast, the comeal layers have revealed positive alterations in the insulin-treated group. The statistical analyses showed significant narrowing in the epithelial layer in the diabetic group (p=0.002), whereas thickening was observed in the epithelial basement membrane and Descemet's membrane (p=0.002). Conclusion: It was determined that diabetes mellitus causes degenerative changes in cornea, which are positively influenced by short-term insulin treatment.