Effect of Topical Ascorbic Acid on Free Radical Tissue Damage and Inflammatory Cell Influx in the Cornea After Excimer Laser Corneal Surgery

Abstract

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 Ͻ.03 and Ͻ.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.

Antioxidant protection in cultured corneal cells and whole corneas submitted to UV-B exposure

“…Since corneal damage during inflammation is characterized by monocytes/macrophages and neutrophils invasion that can release ROS, proteolytic enzymes and arachidonic acid [25,60,62]. The indirect anti-inflammatory effect of pirenoxine and melatonin, dependent on their scavenger activities, can counteract several deleterious effects of inflammation.…”

“…Thus, physiological scavenging agents, such as superoxide dismutase (SOD), catalase, vitamin E, glutathione, ascorbic acid, as well as steroidal or non-steroidal anti-inflammatory molecules, have been tested in order to inhibit the harmful action of UV-B radiation or the side effects of excimer laser therapy on the cornea [20][21][22][23][24][25].…”

Keratocyte apoptosis and corneal antioxidant enzyme activities after refractive corneal surgery

“…ROS induce the peroxidation of fatty acids or lipids and proteins of the cell membranes, degrade corneal stromal tissue by scission of covalent bonds or enhancing their susceptibility to hydrolytic enzymes. 7,11 Previous studies have demonstrated that excimer laser keratectomy increases the corneal temperature, decreases the superoxide dismutase activity of the aqueous humour, and induces lipid peroxidation in the superficial corneal stroma. 7,8 Excimer laser treatment also changes the corneal activities of aldehyde dehydrogenase and glutathione S-transferase, these two enzymes play an important role in detoxification of aldehydes, which are generated from free radical reactions.…”

“…[6][7][8][9][10] The harmful effects of reactive oxygen species (ROS) are widely known, and the pharmacological treatments to reduce oxidative damage in corneal tissue after PRK is under investigation. 11,12 Superoxide dismutase (SOD) and glutathione peroxidase Eye (Gpx) are the main antioxidant enzymes which protect the cornea from radical injury. 13,14 Catalase which has little activity in the cornea is another antioxidant enzyme of it.…”

Pirenoxine prevents oxidative effects of argon fluoride excimer laser irradiation in rabbit corneas: biochemical, histological and cytofluorimetric evaluations

“…Since previous studies suggest the use of antioxidant enzymes and scavenger molecules to prevent the production of free radicals or neutralize their toxic action [28][29][30][31], the effectiveness of the scavenging molecule pirenoxine was tested contemporaneously.…”