Abstract
Purpose: :
To examine incidence of visually–significant age–related cataract and extraction in a randomized trial of vitamin E.
Methods: :
The Women's Health Study was a randomized, double–blind, placebo–controlled trial of vitamin E (600 IU of natural–source vitamin E taken on alternate days) and low–dose aspirin (50 mg on alternate days) in the prevention of cancer and cardiovascular disease among 39,876 women aged 45 years or older. A total of 37,688 participants did not report cataract at baseline and were included in this analysis. Age–related cataract was defined as an incident, age–related lens opacity, responsible for a reduction in best–corrected visual acuity to 20/30 or worse, based on self–report confirmed by medical record review.
Results: :
During an average of 10 years of treatment and follow–up, a total of 2,378 cataracts and 1,554 cataract extractions were confirmed. There were 1,160 cataracts in the vitamin E group and 1,218 cataracts in the placebo group (relative risk [RR], 0.96; 95% confidence interval [CI], 0.88–1.04). In analyses of cataract subtypes, there were no significant effects of vitamin E on incidence of nuclear (RR, 0.94; CI, 0.87–1.03), cortical (RR, 0.93; CI, 0.82–1.06), or posterior subcapsular cataract (RR, 1.00; CI, 0.87–1.16). For cataract extraction, there were 775 in the vitamin E group and 779 in the placebo group (RR, 1.01; CI, 0.91–1.11). In analyses of subtypes, there were no significant effects of vitamin E on extraction of nuclear (RR, 1.00; CI, 0.90–1.11), cortical (RR, 0.92; CI, 0.78–1.08), or posterior subcapsular cataract (RR, 1.08; CI, 0.92–1.27). For both cataract and cataract extraction, RRs did not vary significantly according to known risk factors for cataract including age, smoking, body mass index, and diabetes.
Conclusions: :
These randomized trial data from a very large cohort of women indicate that ten years of alternate–day supplementation with 600 IU of natural–source vitamin E has no material beneficial or harmful effect on age–related cataract or cataract extraction.
Keywords: cataract • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • antioxidants