Hormone replacement therapy, reproductive factors, and cataract. The Blue Mountains Eye Study.

The relation between estrogen (endogenous and exogenous) and cataract is unclear, with one large population-based study recently suggesting a protective effect of estrogen replacement therapy. The study reported in this paper, the Blue Mountains Eye Study, was conducted in Australia in 1992-1993 and involved 2,072 women aged 49-97 years. Subjects were recruited from a defined geographic area; the participation rate was 83 percent. Eye examination included photographs of the lens, which were graded for presence and severity of cortical, nuclear, and posterior subcapsular cataracts. Later age at menarche was associated with increased prevalence of all three types of cataract, but there were no associations with age at menopause, number of children, or use of the oral contraceptive pill. Among all women, there was no association between hormone replacement therapy and cataract. However, current users of hormone replacement therapy aged 65 years and over, among whom the duration of use was likely to have been longer than in younger current users, had lower prevalence of cortical cataract than did never users; the odds ratio adjusted for numerous potential confounders was 0.4 (95 percent confidence interval 0.2-0.8). The prevalence of posterior subcapsular cataract was increased in current users of hormone replacement therapy who had had a nonsurgical menopause; the adjusted odds ratio was 2.1 (95 percent confidence interval 1.1-4.1). The results of this study support the hypothesis that estrogen and/or progestin may be involved in cataract development. The effect of hormone replacement therapy on the lens needs to be evaluated in the laboratory and in further observational epidemiologic studies.