Noncombustible Nicotine or Tobacco Product Use After Smoking Cessation and Major Vision-Impairing Diseases: A Nationwide Cohort Study.
OBJECTIVE: We assessed the risk of major vision-impairing eye diseases among smokers who quit combustible cigarettes (CC) and switch to noncombustible nicotine or tobacco products (NNTPs) compared with those who completely quit using tobacco. DESIGN: Retrospective cohort study. PARTICIPANTS: About 179 273 adults from the Korean National Health Insurance Service who smoked CC in 2011 to 2012 and reported cessation in 2018 to 2019, classified into complete quitters and NNTP switchers. METHODS: This nationwide longitudinal cohort study followed participants for up to 6 years and identified incident major vision-impairing eye diseases (cataract, glaucoma, age-related macular degeneration, diabetic retinopathy, and refractive and accommodation disorders) using standardized diagnostic codes. Propensity score matching was applied to emulate a pseudo-randomized comparison, balanced on key demographic, clinical, comorbidity, and lifestyle characteristics. Subdistribution hazard ratios (SHRs) were evaluated using the Fine-Gray subdistribution hazards model accounting for all-cause mortality as a competing risk. MAIN OUTCOME MEASURES: Adjusted SHRs for incident major vision-impairing eye diseases. RESULTS: Among 32 316 matched participants followed for a mean of 4.6 years, 6328 incident major vision-impairing eye disease events occurred. The incidence was 41.1 and 44.0 per 1000 person-years for complete quitters and NNTP switchers, respectively. Switching to NNTPs was associated with an increased risk of major vision-impairing eye disease (SHR, 1.07; 95% CI, 1.02-1.13). The risk elevation was most pronounced for diabetic retinopathy (SHR, 1.24; 95% CI, 1.00-1.53) and refractive and accommodation disorders (SHR, 1.07; 95% CI, 1.01-1.12). These findings were robust across inverse probability-weighted and Cox proportional hazards models. The association remained consistent in sensitivity analyses and across clinical subgroups. CONCLUSIONS: Transitioning from CC to NNTPs is associated with a modest but consistent increase in the risk of major vision-impairing eye diseases compared with complete nicotine abstinence. These findings challenge the assumption that substituting NNTPs for CCs is visually harmless and indicate that, from an ophthalmic perspective, complete cessation of all nicotine products should remain the preferred cessation goal.