Geographic concordance of cataract and glaucoma burden and associated country-level exposures across 204 countries and territories

Background Cataract and glaucoma are major causes of vision loss, but their shared geographic burden and potentially modifiable population-level exposures remain incompletely characterized. Methods This cross-sectional study included adults aged 55 years and older across 204 countries and territories, using data from the Global Burden of Disease Study (GBD). For both outcomes, national prevalence was age-standardized using the 2021 global population aged 55 years and older as the reference. Based on quartiles of national age-standardized prevalence for both outcomes, we classified the 204 countries and territories into three geographic concordance categories: Concordant, Cataract-dominant, and Glaucoma-dominant. For 2021, we modeled each of 26 literature-informed candidate summary exposure values (SEVs) separately against log age-standardized prevalence, adjusting for the Socio-demographic Index (SDI) with a three-degree-of-freedom natural spline. Benjamini–Hochberg (BH) correction was applied within each outcome, with additional regional and spatial models used to assess sensitivity. Results In 2021, 89 countries (43.6%) were Concordant, 52 (25.5%) were Cataract-dominant, and 63 (30.9%) were Glaucoma-dominant. Fifteen countries were in the highest quartile for both outcomes, mainly in North Africa, the Middle East, and parts of sub-Saharan Africa. Five exposures—ambient particulate matter pollution, ambient ozone pollution, high body-mass index, low bone mineral density, and high temperature—had positive coefficients with outcome-specific BH q < 0.05 for both outcomes in the primary SDI-adjusted models. After adjustment for GBD super-region, only high temperature remained positive for both outcomes with BH q < 0.05. In both spatial-error models, only ambient particulate matter pollution met this standard. Conclusion National cataract- and glaucoma-related vision-loss burdens showed geographic concordance. The exposure findings were country-level associations, and their statistical support varied across regional and spatial models. These geographic patterns may help inform planning for cataract and glaucoma services in settings where both contribute substantially to vision-loss burden. Further individual-level research is needed to clarify the relationships suggested by these country-level findings.