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
Objective To examine the association between smoking cessation and incidence of
Design Prospective cohort study conducted from 1982 through 1997, with an average
follow-up of 13.6 years.
Setting and Participants A total of 20,907 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 smokers 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.