The more smoking the more cataract: A study on smoking, snus use and cataract in a Swedish population.

Purpose: To examine the prevalence of self-reported cataract and cataract surgery, and the incidence of cataract surgery, in relation to smoking and use of the moist smokeless tobacco product snus.

Methods: In 2014/2015, individuals born in 1951 (n = 18 055) in the Västra Götaland County, Sweden, were invited to participate. Of these, 9743 (54%) accepted participation and 9316 (52%) remained after exclusion criteria were applied. Participants answered a questionnaire with items about eye conditions, smoking, snus, gender, education, asthma, chronic obstructive pulmonary disease, corticosteroid use, diabetes mellitus, weight and height. Prevalence ratios (PRs) for self-reported cataract and cataract surgery were calculated. The incidence of cataract surgery was assessed, and hazard ratios (HRs) were presented.

Results: Having ever smoked was associated with a higher prevalence ratio of self-reported cataract (PR 1.19, 95% confidence interval [CI] 1.04-1.35) and cataract surgery (PR 1.27, 95% CI 1.06-1.53), compared to those who had never been daily smokers. Currently, a smoker was associated with a higher HR of cataract surgery (HR 1.34, 95% CI 1.04-1.74), as well as having been a former smoker (HR 1.27, 95% CI 1.03-1.56). Total years of smoking were associated with an increased risk for cataract surgery (HR 1.05, 95% CI 1.02-1.08 for 5 years of smoking). Snus use was not associated with an increased prevalence of cataract or incidence of cataract surgery, except among women who were current snus users (HR for cataract surgery 2.04, 95% CI 1.16-3.60 n = 108).

Conclusion: Smoking is associated with a higher prevalence of cataracts, and a higher incidence of cataract surgery, indicating a dose-response relationship. However, there was no firm association between snus use and cataract.