Effect of topical ascorbic acid on free radical tissue damage and inflammatory cell influx in the cornea after excimer laser corneal surgery

Objective: To evaluate the effect of topical ascorbic acid on oxygen free r adical tissue damage and the inflammatory cell influx in the cornea after e xcimer laser keratectomy. Methods: Five New Zealand white rabbits underwent bilateral phototherapeuti c keratectomy with the 193-nm argon fluoride excimer laser. Following treat ment, the right eye of each rabbit was treated with 10% ascorbic acid every 3 hours for 24 hours. The left eyes served as controls. After 24 hours, al l animals were killed and their corneas were trephined and processed. Secti ons were stained with fast blue B and with hematoxylin-eosin. Oxidative tis sue damage in the form of lipid peroxidation was detected by fluorescent pe roxidized carbonyl compounds using a confocal laser scanning microscope. Th e quantity of these compounds was determined using the National Institutes of Health digital image analysis system. Statistical comparisons of lipid p eroxidation and polymorphonuclear cell count between the ascorbic acid grou ps and the controls were performed using the Student t test. Results: Lipid peroxidation and polymorphonuclear cell counts were signific antly decreased in the superficial cornea of ascorbic acid-treated eyes com pared with control eyes (P <.03 and <.02, respectively). Conclusions: Topical ascorbic acid application decreased oxygen radical tis sue damage following excimer keratectomy; moreover, topical application of ascorbic acid was shown to reduce the acute inflammatory reaction efficient ly. This suggests that topical ascorbic acid could be considered a compleme ntary treatment in the pharmacological modulation after excimer laser corne al surgery. Clinical Relevance: Corneal opacity may complicate excimer keratectomy. The use of an antioxidant to reduce tissue damage could help minimize postoper ative stromal opacification.