Effect of long-term hyperglycemia on cornea and retina morphology in rats with streptozotocin-induced diabetes mellitus

Abstract

The aim was to study morphological changes in the cornea and the posterior part of rat eye during prolonged hyperglycemia. Methods. The study was performed on 36 Wistar male rats. Diabetes mellitus was induced by an injection of streptozotocin (65 mg/kg, i.p.) followed by daily injections of low doses of insulin (2 U/kg, s.c.). Eyes were enucleated from deeply anesthetized rats on days 50, 58, and 66 of the experiment. Histologic sections were stained with hematoxylin-eosin, and morphometry of the cornea and the retina was performed. Results. Mean blood concentrations of glucose and ketone bodies were 29.8 mmol/L and 0.889 mmol/L, respectively, in the diabetic group and 6.2 mmol/L and 0.847 mmol/L, respectively, in the control group. The histological analysis revealed signs of edema in the cornea, choroid and outer layers of the central retina, which preceded other morphological changes. Conclusion. Evaluating thickness of the cornea, choroid and outer layers of the central retina may serve for prediction of diabetic retinopathy.