Effect of topically applied 0.1% dexamethasone on endothelial healing and aqueous composition during the repair process of rabbit corneal alkali wounds

Abstract

Purpose. The effects of topical dexamethasone on the endothelial healing and the change of aqueous compositions were investigated during the repair process of alkali-wounded rabbit cornea. Methods. A central corneal alkali wound was produced by a 60 sec application of a 5.5 mm round filter paper soaked in 1 N NaOH onto one eye of each rabbit. The eyes subsequently were treated topically with either 0.1% dexamethasone or a balanced salt solution (BSS) 4 times per day for 8 weeks. Endothelial wound morphometry was performed after alizarin red and trypan blue staining. The concentrations of ascorbic acid, glucose, and the ions, Na+, K+, Ca2+ and Mg2+, were measured in the aqueous humor. Results. Endothelial healing in control (alkali-wounded but not treated with dexamethasone) corneas showed a biphasic pattern of healing: an initial short-term healing for the first week and then a late long-term healing following the secondary endothelial breakdown. Topical administration of 0.1% dexamethasone deterred endothelial healing during the early period and prevented the secondary endothelial breakdown. However, the total repair process of endothelium was accelerated by the dexamethasone-treatment. Among the various components of the aqueous humor examined, ascorbic acid seemed the most sensitive to change caused by the alkali injury and dexamethasone treatment. Conclusions. The present data indicate that dexamethasone may have a therapeutic potential in the management of endothelial healing after corneal alkali injury.