Purpose: Cataract is the leading cause of blindness worldwide. Blood pressure has been identified as a risk factor in some, but not all, previous studies. We aimed to test prospectively the hypothesis that high blood pressure increases risk of age-related cataract.
Methods: Participants in the Physicians' Health Study of 22,071 men aged 40 to 84 years in 1982 completed annual questionnaires that provided medical history including self-reported blood pressure, treatment for hypertension, and cataract. Over 12 years, 1392 cataracts were confirmed by medical record review among 17,762 physicians with complete data and no reported cataract at baseline. We used proportional hazards regression models to examine relations of systolic blood pressure (SBP), diastolic blood pressure (DBP), hypertension, as well as antihypertensive medications with cataract, after control for potential confounding factors.
Results: In models adjusting for age and randomized treatment assignment, there was a significant relationship of SBP, but not DBP, hypertension, or antihypertensive medications (each p > or = 0.23) with incident cataract. Estimates were attenuated after adjusting for multiple potential confounders, although the relationship of SBP with incident cataract remained significant. The multivariate adjusted rate ratio (95% confidence interval) of cataract for SBP > or = 150 versus < 120 mm Hg was 1.31 (1.04-1.66), p for trend = 0.04. For DBP > or = 90 versus < 70 mm Hg, the estimate was 1.11 (0.84-1.45), p for trend = 0.33.
Conclusions: Overall, these data suggest that the relationship of blood pressure with cataract is not strong, and is subject to confounding by other risk factors. The modest magnitude of the association with SBP and lack of significant relationships with DBP and hypertension may suggest a non-causal relationship of blood pressure with cataract.