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

Abstract

Objective: To evaluate the effect of topical ascorbic acid on oxygen free radical tissue damage and the inflammatory cell influx in the cornea after excimer laser keratectomy.

Methods: Five New Zealand white rabbits underwent bilateral phototherapeutic keratectomy with the 193-nm argon fluoride excimer laser. Following treatment, 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, all animals were killed and their corneas were trephined and processed. Sections were stained with fast blue B and with hematoxylin-eosin. Oxidative tissue damage in the form of lipid peroxidation was detected by fluorescent peroxidized carbonyl compounds using a confocal laser scanning microscope. The quantity of these compounds was determined using the National Institutes of Health digital image analysis system. Statistical comparisons of lipid peroxidation and polymorphonuclear cell count between the ascorbic acid groups and the controls were performed using the Student t test.

Results: Lipid peroxidation and polymorphonuclear cell counts were significantly decreased in the superficial cornea of ascorbic acid-treated eyes compared with control eyes (P <.03 and <.02, respectively).

Conclusions: Topical ascorbic acid application decreased oxygen radical tissue damage following excimer keratectomy; moreover, topical application of ascorbic acid was shown to reduce the acute inflammatory reaction efficiently. This suggests that topical ascorbic acid could be considered a complementary treatment in the pharmacological modulation after excimer laser corneal surgery.

Clinical relevance: Corneal opacity may complicate excimer keratectomy. The use of an antioxidant to reduce tissue damage could help minimize postoperative stromal opacification.