Cataracts riboflavin

Ascorbate is known to act as a water-soluble antioxidant, reacting rapidly with superoxide, hydroxyl and peroxyl radicals. However, reduced ascorbate can react non-enzymatically with molecular oxygen to produce dehydroascorbate and hydrogen peroxide. Also, ascorbate in the presence of light, hydrogen peroxide and riboflavin, or transition metals (e.g. Fe, Cu " ), can give rise to hydroxyl radicals (Delaye and Tardieu, 1983 Ueno et al., 1987). These phenomena may also be important in oxidative damage to the lens and subsequent cataract formation. 

Riboflavin deficiency is not associated with a specific disease per se (19,80,81). However, a lack of riboflavin in the diet produces changes in the eye, including photophobia, corneal opacity and ulceration, presenile cataracts, circumcomeal infections, and reduced tearing, as well as skin lesions, especially around the mouth, nose, and ears. 

Prchal JT, Conrad ME, Shalka HW. 1978. Association of presenile cataracts with heterozygosity for galactosaemic states and with riboflavin deficiency. Lancet 1 12-13. 

Corneal vascularization by outgrowth of new capillaries originating from the vessels of the limbic plexus has been described in rats, mice, and dogs. Leukocytes also appear in the cornea while the capillaries are being invaded. This cellular exudation is later followed by vascular degeneration of the superficial cell layer of the cornea, which becomes cloudy and ulcerates. All these changes recede rapidly after adequate doses of riboflavin are administered. Cataracts have been described in riboflavin-deficient rats and swine, but experimental riboflavin deficiency in man did not induce eye lesions. 

In addition to these changes a number of workers have found that cataracts develop in riboflavin-deficient animals. Day and co-workers,Win-trobe and co-workers,and Bourne and Pyke were able to confirm Day s work, but some other workers were not so successful. In the development of such cataracts the earliest signs of change were found to be epithelial proliferation and degeneration of fibers. Then the fibers broke down completely and the lens became an opaque amorphous mass. Pirie found that histological changes in the eyes in riboflavin deficiency were similar to those produced by tryptophan deficiency. 

Eyes. Extra blood vessels develop in the cornea (the eyes become bloodshot—a condition known as corneal vascularization), and the eyes become sensitive to light and easily fatigued. There is also blurring of the vision, and the eyes burn, itch, and tear. Cataracts have been observed in rats, mice, chickens, pigs, and monkeys after prolonged deficiency of riboflavin. 

Riboflavin may have some role in the prevention of migraine in combination with other dmgs. There is some evidence that riboflavin may be able to prevent cataract formation and for this reason the RDA for elderly people may be set at 1.7 mg per day. 

---