Ocular ascorbate transport and metabolism.

1. The concept is reviewed that the eye is subject to photo-oxidative damage through chemical free radical species that interact with sensitive tissue components. 2. The role of ascorbic acid may be to protect the eye by scavenging free radicals. 3. Ascorbic acid is present at a high concentration in various ocular compartments of diurnal animals, regardless of whether the animal synthesizes the compound or extracts it from the diet. 4. Ascorbic acid accumulates in the eye by active transport through the iris-ciliary body into aqueous humor, and subsequent transport into the lens and cornea. 5. Conservation of ascorbic acid occurs by reduction of dehydro-L-ascorbic acid and the ascorbate free radical through processes that appear to be enzymatic.