Effect of topical steroids on the healing of corneal endothelium.

The central portions of the cornea of adult rabbits were injured with a cryocautery and the rate of endothelial healing was compared between untreated and topical dexamethasone-treated corneas. Regenerating cells were labeled with daily injections of tritiated thymidine until the fifth day, when healing occurred. Control eyes showed 90 per cent label, but the number of labeled cells was less in steroid-treated corneas. The circular area of injured endothelium showed a slower healing rate in the first three days of steroid treatment. From then on, the progression of healing was similar to that of the control eyes. When the healing endothelium was studied with the scanning electron microscope, endothelial cells with a predominant fibroblastic shape were found in untreated corneas, while steroid-treated eyes showed fibroblastic and flattened cells with large cytoplasm.