Effect of topically applied 0.1% dexamethasone on endothelial healing of rabbit corneal alkali wounds

Abstract

Purpose. The healing of rabbit corneal endothelium following a standardized alkali wound has two phases, i.e. a rapid initial healing phase which ended one week after the initial wounding, and a long-term late healing phase which lasted at least for 6 months. The endothelium play a key role on corneal alkali wound healing. In this study, the effect of topically applied dexamethasone on initial endothelial healing was evaluated. Methods. 105 NewZealand white rabbits weighing 2.5 Kg were divided in 3 groups. By using a 5.5 mm round filter paper, soaked in 1 N NaOH for 60 sec. application, a central corneal alkali damage was produced in one eye of each animal. Group A treated with 0.1% Dexamethasone, 4 x/day, for 4 weeks continuosely. Group B received 0.1% Dexamethasone, 4 x/day, for the first 1 week and then followed another 3 weeks without treatment. Group C served as control. Five animals in each treatment group were killed at 0 hr, 3, 5 days, 1, 2, 3, and 4 weeks. The endothelium was stained with alizarin red/tryphan blue and morphometric determination was performed in LM. Endothelial healing rates were calculated by linear regression analysis. Results. The endothelial healing rates of group A, B, and C were 0.51, 1.08, and 3.31 mm 2/day, respectively. Conclusions. The results suggest that the topically applied 0.1% Dexamethasone retarded the initial endothelial healing process and thus can delay the occurrence of the late endothelial healing phase in rabbit corneal alkali wounds.