Corneal endothelial morphology in the rat. Effects of aging, diabetes, and topical aldose reductase inhibitor treatment.

Increases in corneal endothelial cell polymegathism and pleomorphism are characteristic of diabetic human and dog corneas. This study investigated the rat as a model for age- and diabetes-related changes in endothelial cell morphology. As in most mammals, aging of the normal rat results in a progressive decrease in cell density as well as reduced numbers of hexagonal endothelial cells and increased coefficient of variation of cell size after age 34 weeks. Streptozotocin-induced diabetes produced an early progressive increase in the coefficient of variation of cell size and decrease in percentage of hexagonal cells so that diabetic rats were significantly different from age-matched normal rats by 24 weeks of age. Topical treatment with the aldose reductase inhibitor, AL 1576, begun immediately after diabetes induction, prevents endothelial cell changes and cataract formation. Topical aldose reductase inhibition also reverses endothelial cell changes when treatment is begun 8 weeks after streptozotocin injection. These results indicate that the rat is a good model for studying diabetes-induced corneal endothelial changes and that topical aldose reductase inhibitors may be effective in preventing or reversing diabetic corneal endothelial cell changes.