Lutein and other antioxidants have been hypothesized to have beneficial effects for visual function. Another coroborating research report on the long-term effect of lutein on the visual function amoung cataracts patients has been published.

In the study published in Janurary 2003 [Olmedilla B, Granado F, Blanco I, Vaquero M., Lutein, but not alpha-tocopherol, supplementation improves visual function in patients with age-related cataracts: a 2-y double-blind, placebo-controlled pilot study. Nutrition 2003 Jan;19(1):21-4.], the authors reported the results from an investigation on the effect of long-term antioxidant supplementation (lutein and alpha-tocopherol) on serum levels and visual performance in patients with cataracts. Seventeen patients clinically diagnosed with age-related cataracts were randomized in a double-blind study involving dietary supplementation with lutein (15 mg; n = 5), alpha-tocopherol (100 mg; n = 6), or placebo (n = 6), three times a week for up to 2 years. Serum carotenoid and tocopherol concentrations were determined with quality-controlled high-performance liquid chromatography, and visual performance (visual acuity and glare sensitivity) and biochemical and hematologic indexes were monitored every 3 mo throughout the study. Changes in these parameters were assessed by General Linear Model (GLM) repeated measures analysis. Serum concentrations of lutein and alpha-tocopherol increased with supplementation, although statistical significance was reached only in the lutein group. Visual performance (visual acuity and glare sensitivity) improved in the lutein group, whereas there was a trend toward the maintenance of and decrease in visual acuity with alpha-tocopherol and placebo supplementation, respectively. No significant side effects or changes in biochemical or hematologic profiles were observed in any of the subjects during the study.Visual function in patients with age-related cataracts who received the lutein supplements improved, suggesting that a higher intake of lutein, through lutein-rich fruit and vegetables or supplements, may have beneficial effects on the visual performance of people with age-related cataracts.