Hydrogen peroxide in anterior segment physiology: a literature review

The role of hydrogen peroxide when it is physiologically produced or when it is applied externally to the eye is examined in this review. Three enzymes deal with the endogenously produced H2O2. They are catalase, superoxide dismutase, and glutathione peroxidase. These enzymes are present at different concentrations in ocular tissues and function most efficiently at different concentrations of H2O2. For H2O2 which contacts the external surface of the eye, the same enzymes also seem to act to metabolize the H2O2. In general the eye is more sensitive to changes in pH than to low concentrations of topically applied H2O2 at concentrations less than about 400 ppm. So, the small amounts of residual H2O2 which remain on contact lenses after disinfection in H2O2 solutions do not pose a great risk to the eyes.