The Association of Ambient Air Pollution With Cataract Surgery in UK Biobank Participants: Prospective Cohort Study

PURPOSE: Air pollution is associated with chronic diseases of later life. Cataract is the most common cause of blindess globally. It is biologically plausible that cataract risk is increased by pollution exposure. Therefore, the relationship between air pollution and incident cataract surgery was examined. METHODS: This was a prospective, observational study involving 433,727 UK Biobank participants. Ambient air pollution measures included particulates, nitrogen dioxide (NO(2)) and nitrogen oxides (NO(x)). Outdoor air pollution was estimated based on land use regression models. Participants undergoing cataract surgery in either eye were ascertained via data linkage to the National Health Service procedure statistics. Those undergoing cataract surgery within 1 year of baseline assessment and those reporting cataract at baseline were excluded. Cox proportional hazards models were used to examine the associations between air pollutants and incident cataract surgery, adjusting for sociodemographic and lifestyle factors. RESULTS: There were 16,307 incident cases of cataract surgery. Higher exposure to PM(2.5) was associated with a 5% increased risk of incident cataract surgery (per interquartile range [IQR] increase). Compared to the lowest quartile, participants with exposures to PM(2.5), NO(2), and NO(x) in the highest quartile were 14%, 11%, and 9% more likely to undergo cataract surgery, respectively. A continuous exposure-response relationship was observed, with the likelihood of undergoing cataract surgery being progressively higher with greater levels of PM(2.5), NO(2), and NO(x) (P for trend P < 0.001). CONCLUSIONS: Although the results of our study showed a 5% increased risk of future cataract surgery following an exposure to PM(2.5), NO(2), and NO(x), the effect estimates were relatively small. Further research is required to determine if the associations identified are causal.