Smoking and the long-term incidence of cataract: the Blue Mountains Eye Study

To assess the association between smoking and the long-term incidence of cataract and cataract surgery.

In a population-based cohort of Australians aged 49 years and over, 3654 participants were seen at baseline (1992-94) and 2406 were seen after 5- and/or 10-years and had photographs taken to assess incident cataract. Smoking status was recorded at interview. History, physical examination and fasting blood samples provided data on possible risk factors. Cataract incidence was calculated using the Kaplan-Meier survival approach. Discrete linear logistic models were used to assess risk of incident cataract.

After controlling for age, sex and other factors, ever smokers had an increased risk of developing nuclear cataract compared to never smokers (relative risk (RR) 1.41; 95% confidence interval (CI) 1.09-1.83; RR 1.37, CI 1.04-1.81 for past smoking and RR 1.57, CI 1.06-2.31 for current smoking). The effect of smoking was strongest in ever smokers reporting 36 + pack-years of smoking compared to never smokers (RR 1.46; CI, 1.02-2.08). Current smokers also developed nuclear cataract slightly younger than non-smokers (mean age 65.2 versus 67.5 years, p = 0.049). No statistically significant associations were found between smoking status and the incidence of cortical or posterior subcapsular cataract, or cataract surgery.

These epidemiological data confirm smoking as a modest risk factor for the development of nuclear cataract.