The Association of Socioeconomic Status with the Burden of Cataract-related Blindness and the Effect of Ultraviolet Radiation Exposure: An Ecological Study.

Objective To assess the association of socioeconomic status with the burden of cataract blindness in terms of year lived with disability (YLD) rates and to determine whether ultraviolet radiation (UVR) levels modify the effect of socioeconomic status on this health burden. Methods National and subnational age-standardized YLD rates associated with cataract-related blindness were derived from the Global Burden of Disease (GBD) study 2017. The human development index (HDI) from the Human Development Report was used as a measure of socioeconomic status. Estimated ground-level UVR exposure was obtained from the Ozone Monitoring Instrument (OMI) dataset of the National Aeronautics and Space Administration (NASA). Results Across 185 countries, socioeconomic status was inversely associated with the burden of cataract blindness. Countries with a very high HDI had an 84% lower age-standardized YLD rate [95% confidence interval ( CI): 60%-93%, P < 0.001] than countries with a low HDI; for high-HDI countries, the proportion was 76% (95% CI: 53%-88%, P < 0.001), and for medium-HDI countries, the proportion was 48% (95% CI: 15%-68%, P = 0.010; P for trend < 0.001). The interaction analysis showed that UVR exposure played an interactive role in the association between socioeconomic status and cataract blindness burden ( P value for interaction = 0.047). Conclusion Long-term high-UVR exposure amplifies the association of poor socioeconomic status with the burden of cataract-related blindness. The findings emphasize the need for strengthening UVR exposure protection interventions in developing countries with high-UVR exposure.