Effects of acetylcysteine and dexamethasone on experimental corneal wounds in rabbits.

Corneal wound healing often leads to the development of scar tissue with loss of transparency. Reconstitution of transparent corneal stroma depends on the regulation of the biosynthetic activities of post-lesional keratocytes as well as to a large extent on the limitation of matrix degradation. It has been shown that 3% concentration of N-acetylcysteine (NAC) improves the healing time of corneal wounds but some corneal haze remains. On the other hand, topical corticosteroids may retard the corneal wound healing but decrease the haze. Thus, the aim of the study was to evaluate whether adding dexamethasone to NAC could reduce the side effects of the two drugs. In this study, experimental corneal wounds were created surgically, up to the depth of one half of the stroma in the center of both eyes of all rabbits. The left eyes were treated topically with 0.9% NaCl as controls and the right eyes were treated with a combination of one drop of 3% NAC and one drop of 0.1% dexamethasone, 6 times per day. Corneal wounds were measured by fluorescein staining every day. The results indicated that the combination of acetylcysteine and dexamethasone significantly increased the mean healing time compared to the control group (p < 0.05). Clinical and histopathologic examinations revealed that the corneal haze in the treatment group was greater than in the control group. It is concluded that treatment of the eyes by a combination of 3% acetylcysteine and 0.1% dexamethasone (if used from the first day of ulceration) may retard the corneal wound healing in rabbits.