Oxidative Stress And Cataract

Age —related cataract has been studied extensively over the past two decades, however,the mechanism of cataract formation remains unclear. Accumulated evidences based on basic research suggest that oxidative stress may play an important role in cataractogenesis,and that antioxidants including those micronutrients with antioxidant capacity may protect the lens from oxidative damage.To determine whether use of vitamin/mineral supplements affected the risk of developing age —related cataract, data collected in two randomized, double—masked nutrition intervention trials in Linxian were analysed. Lens status was evaluated with the Lens Opacity Classification System II (LOC-SII). In one trial,eye examinations were conducted on 2141 subjects supplemented with vitamins/minerals or placebo for six years. Among persons receiving the supplements, there was a 36% reduction in the prevalence of nuclear cataract for persons aged 65 — 74 years. P<0.01. In the second trial, 3249 subjects were examined after five years of intervention. A factorial design was used to test the effect of four different vitamin/mineral combinations. The prevalence of nuclear cataract was significantly lower in persons receiving riboflavin/niacin, compared with persons not receiving these vitamins. Again persons in the oldest group 65 — 74 years benefitted most, with 45% reduction in prevalence (P<0. 001). No treatment effect was noted for cortical cataract in either trial.Findings from the two trials suggest that vitamin/mineral supplements may decrease the risk of nuclear cataract. However, these trials were conducted in such a population suffering from long and chronic nutrition defi-...