Findings from the 45 and Up Study: smoking is not associated with the risk of early-onset cataract.

Background To determine if tobacco smoking is a risk factor for early-onset cataracts. Methods This was a prospective population-based cohort study. A total of 70,886 participants aged 45-55 years in the 45 and Up Study were included in our analysis. Early-onset cataracts (EOC) were defined as cataract surgeries performed before 65 years old, based on participant data linked to the Medicare Benefits Schedule (MBS). Smoking habits were assessed at baseline, based on a self-administered questionnaire. A Cox proportional hazards model was used to evaluate the association between tobacco smoking and the risk of early-onset cataracts over the follow-up period. Results At baseline recruitment, 59.9% of study participants never smoked, 30.5% were former smokers, and 9.6% were current smokers. A total of 1,713 participants underwent cataract surgery over a mean follow-up of 625,042 person-years, with an incidence of 2.74 cases per 1,000 person-years. For current smokers, patients with EOC had longer smoking durations (P=0.019). For former smokers, patients with EOC had higher smoking intensities (P=0.001), were older at smoking commencement (P=0.011), and longer times since quitting (P=0.04). The risk of EOC was not found to be significantly different between current smokers or former smokers, compared to those who had never smoked. Both stratification and sensitivity analyses by gender, surgery year, alcohol intake, physical activity, and income yielded similar results. Conclusions Smoking has neither a beneficial nor harmful effect on the long-term incidence of EOC.