PREVENTION OF CATARACTS BY NUTRITIONAL AND METABOLIC ANTIOXIDANTS

Among aging disabilities, the one associated with the progressive decl ine of vision is functionally most disadvantageous. Cataracts are one of the more common causes of such visual disability. Several predispos ing factors have been identified in the genesis of this disease. While it is perhaps a multifactorial process, significant developments have taken place in recent yeats suggesting that oxygen radicals are invol ved in the development of this aging manifestation. Antioxidant enzyme s, such as catalase and superoxide dismutase, have been demonstrated t o protect the lens cell membrane from oxidative stress as reflected by the prevention of the Na+-K+-ATPase-dependent pump deterioration due to oxyradical-dependent oxidation of its proteins and lipids. From the nutritional point of view, antioxidants such as ascorbate and vitamin E also offer significant protection to the lens against damage due to oxidative stress. Evidence regarding the protective effect of these n utrients has been based on lens organ culture studies in the presence of active oxygen, generated photochemically as well as enzymatically. The experiment involving photochemical environs simulate the status of the eye during the photopic vision. In vivo, the effectiveness of asc orbate against cataracts has been tested in rat pups developing catara cts under the oxidative influence of sodium selenite. Certain antioxid ants produced metabolically also may be useful in protecting against c ataracts. Pyruvate produced in glucose metabolism seems to be an impor tant antioxidant. The efficacy of this compound has been tested within in vitro organ culture as well as in vivo, the latter experiments bei ng done with selenite-treated rats. There is a hope that these and oth er nutritional and metabolic antioxidants may one day be useful in del aying or even preventing cataract formation in human beings.