ABSTRACT

The iris in the human eye is exposed to UV and visible light transmitted by the cornea. This pigmented tissue is bathed with the aqueous humor (AqH), which contains high concentration of ascorbate. It has been postulated that the presence of ascorbate in AqH can contribute to increased photoproduction of H^sub 2^O^sub 2^ mediated by the iris melanin. In this study, we monitored generation of H^sub 2^O^sub 2^ induced by UV-VIS irradiation of bovine indes, bovine and human iris homogenates and iris melanin. Our data show that exogenous ascorbate significantly amplified the rate of H^sub 2^O^sub 2^ photoformation in all melanotic samples. Deactivation of endogenous catalase with ...