Oxidation and aspects of ocular pathology

Hydrogen peroxide (H2O2), a relatively stable oxidant, is present at low concentrations in the normal eye and is found at elevated concentrations in some patients with maturity-onset cataract. Recently, this laboratory has shown that H2O2 concentrations at levels only slightly above normal physiologic levels cause single-strand breaks in DNA within cultured lens epithelial cells obtained from calf lenses. It is hypothesized that such damage may contribute to the onset of cataract. The major enzyme which metabolizes H2O2 at the concentrations found in the eye is glutathione peroxidase. Since older individuals may have reduced activities of this enzyme and other enzymes involved in oxidative defense, this laboratory is synthesizing low-molecular-weight glutathione peroxidase mimics. It is possible that development of such compounds may improve the capacity of the lens to withstand oxidative stress in vitro.