The effect of total-body irradiation on corneal neovascularization in the Fischer 344 rat after chemical cauterization.

Previous investigations of corneal neovascularization after irradiation yielded discordant results. Most studies indicated that new blood vessel formation in the cornea is inhibited by irradiation. However, others reported that angiogenesis after corneal cauterization is similar in both irradiated and nonirradiated animals. To assess the effect of total-body irradiation on neovascularization further, the amount of angiogenesis was determined in irradiated rats after chemically induced corneal injury. Corneal tissue was evaluated quantitatively with computerized image analysis 2, 3, or 4 days postcautery in rats perfused with India ink and gelatin immediately after death. The rats were exposed to a single dose (9 Gy) of total-body irradiation 6 days before corneal cauterization. In both the nonirradiated and irradiated rats, neovascularization increased with the duration of the postcautery interval. The amount of corneal neovascularization was not significantly different in the irradiated and nonirradiated rats at any of the postcautery intervals studied. This investigation suggests that endothelial cell migration plays a more important role than cell replication in the pathogenesis of corneal angiogenesis in the Fischer 344 rat. Moreover, the suppression of corneal angiogenesis by irradiation may be dependent on the experimental conditions and species examined.