Discoveries in research on diabetic keratopathy.

Background Researchers exploring the mechanisms of diabetic changes in numerous body tissues have evidence that the complications may result from the consequences of increased aldose reductase activity. Aldose reductase is the rate-limiting enzyme in the polyol pathway in which glucose is converted to sorbitol. Method Sorbitol accumulation from increased aldose reductase activity may play a role in diabetic corneal pathology as well. Studies of animals involving diabetic models have shown both structural (polymegathism, pleomorphism) and functional (increased permeability, slower recovery from induced edema) changes in the diabetic corneal epithelium and endothelium. Some studies of human beings have confirmed these findings. However, differences in the groups of human subjects between studies (such as age, type of diabetes, state of glycemia. duration of disease, etc.) may account for the sometimes conflicting results. Results Treatment with aldose reductase inhibitors has been shown both to reduce corneal changes after they have occurred and to limit the development of these corneal changes when compared to untreated controls in both animals and human beings. Conclusion The mechanism by which increased aldose reductase activity contributes to diabetic corneal pathology remains unknown.