Protective Effect of Ascorbic Acid Against Corneal Damage by Ultraviolet B Irradiation

Abstract

To determine the protective effect of ascorbic acid (ASA) against corneal damage by ultraviolet B (UVB) irradiation. Eight rabbits weighing 2.1-2.5 kg were randomly divided into 3 groups: a UVB group, an ASA group, and a control group. The UVB group was made up of 2 rabbits that were exposed to 6.84 J/cm of UVB irradiation at a peak wavelength of 306 nm for 17 min/d for 7 days. The ASA group was made up of 4 rabbits that were pretreated intravenously with ASA before being subjected to UVB irradiation. The control group was made up of 2 rabbits that were not subjected to ASA treatment or UVB exposure. After 7 days, the corneas were clinically evaluated for signs of epithelial damage, corneal haze, and neovascularization. After evaluation, the enucleated eyes were analyzed pathologically for signs of proliferation, nuclear change, inflammation, edema, and neovascularization. More damage was observed in the irradiation groups (UVB and ASA groups) than in the control group for all clinical and pathologic parameters (P < 0.0001). Also, when each of the parameters was considered, more severe changes were observed in the UVB group than the ASA group (P < 0.0001), with the exception of nuclear changes, for which the comparison was not applicable. ASA protected the cornea against UVB irradiation in this pilot study; however, further evaluation using many animals is needed to establish its efficacy.