Smoking cessation and risk of age-related cataract in men

Context Although cigarette smoking has been shown to be a risk factor for age-related cataract, data are inconclusive on the risk of cataract in individuals who quit smoking. Objective To examine the association between smoking cessation and incidence of age-related cataract. Design Prospective cohort study conducted from 1982 through 1997, with an average follow-up of 13.6 years. Setting and Participants A total of 20907 US male physicians participating in the Physicians' Health Study I who did not have a diagnosis of age-related cataract at baseline and had reported their level of smoking at baseline. Main Outcome Measures Incident age-related cataract defined as self-report confirmed by medical record review, diagnosed after study randomization and responsible for vision loss to 20/30 or worse, and surgical extraction of incident age-related cataract, in relation to smoking status and years since quitting smoking. Results At baseline, 11% were current smokers, 39% were past smokers, and 50% were never smokers. Average reported cumulative dose of smoking at baseline was approximately 2-fold greater in current than in past smokers (35.8 vs 20.5 pack-years). Two thousand seventy-four incident cases of age-related cataract and 1193 cataract extractions were confirmed during follow-up. Compared with current smokers, multivariate relative risks (RRs) of cataract in past smokers who quit smoking fewer than 10 years, 10 to fewer than 20 years, and 20 or more years before the study were 0.79 (95% confidence interval [CI], 0.64-0.98), 0.73 (95% CI, 0.61-0.88), and 0.74 (95% CI, 0.63-0.87), respectively, after adjustment for other risk factors for cataract and age at smoking inception. The RR for never smelters was 0.64 (95% CI, 0.54-0.76). The reduced risk in past smokers was principally due to a lower total cumulative dose (RR of cataract for increase of 10 pack-years of smoking, 1.07; 95% CI, 1.04-1.10). A benefit of stopping smoking independent of cumulative dose was suggested in some analyses. Results for cataract extraction were similar. Conclusion These prospective data indicate that while some smoking-related damage to the lens may be reversible, smoking cessation reduces the risk of cataract primarily by limiting total dose-related damage to the lens.