Oxidative stress and cataract format ion: horizons on its medical prevention

Cataract is one of the most widely prevalent vision-impairing manifestations worldwide. Currently, the only available treatment for the disease is the surgical extraction of the cataractous lens with replacement by a synthetic implant. Although such a surgical replacement of the natural lens with an artificial lens is significantly effective in restoring vision to most patients, it is not free of complications. The difficulties encountered are further exacerbated in diabetic and relatively older patients. Operationally, the prevalence of the disease is so high that surgery alone is not able to effectively reduce the global cataract burden; the old cases are continually replaced by new ones. It is therefore highly desirable to explore avenues for preventing and treating this disease via nonsurgical medical measures. Several studies suggest that medical prevention of cataracts using oxyradical scavengers acting as antioxidants is a strong possibility. This review focuses on the potential use of various nutritional and metabolically derived antioxidants for this purpose, particularly emphasizing the use of endogenously derived compounds. The latter would be beneficial in avoiding toxicity in long-term use. It is also desirable that they can act as metabolic agonists so as to facilitate various bioenergetic processes responsible for survival of the tissue and its maintenance in a transparent state. We postulate that alpha-ketocarboxylic acid metabolites, such as pyruvate and alpha-ketoglutarate, are likely to be very suitable from this point of view.