Elevated serum uric acid levels mediate the associations of ambient PM2.5 and its components with glaucoma

Limited epidemiological information exists on the relationships between fine particulate matter (PM2.5) components and glaucoma risk. Moreover, the potential mediation effect of serum uric acid (UA) levels remains unexplored. Data from the China Health and Retirement Longitudinal Survey (CHARLS) spanning 2011–2020 were analyzed. Cox proportional hazard models and quantile-based g-computation (qg-computation) models were applied to determine the associations of PM2.5 and its five components (including sulfate [SO₄2⁻], nitrate [NO₃⁻], ammonium [NH₄⁺], organic matter [OM], and black carbon [BC]) with glaucoma risk. A causal mediation model was applied to assess the mediation effect of serum UA. Individual exposure to PM2.5 mass and its five components was positively associated with glaucoma risk, respectively. The mixture of PM2.5 components were significantly and positively associated with glaucoma risk (hazard ratio [HR] = 1.31, 95% confidence interval [CI]: 1.18–1.45), with NH₄⁺ and BC contributing the most (proportions: 81% and 19%, respectively). These associations were modified by sex and residence. Elevated serum UA levels played a mediated role in the association between PM2.5 mass and its five chemical components and glaucoma, with mediated proportions ranging from 12% to 15%. Prolonged exposure to PM2.5 components, especially NH4+ and BC, may elevate the glaucoma risk among Chinese middle-aged and older people, and elevated serum UA levels may play a key mediating role. [Display omitted] •Exposure to PM2.5 and its constituents were positively associated with glaucoma risk.•The joint effect and relative importance of PM2.5 constituents were assessed.•BC and NH4+ are the main PM2.5 constituents contributing to glaucoma risk.•A roughly linear concentration-response association was found for PM2.5.•Elevated serum uric acid level may play a key mediated effect.