Sunlight's hidden hazard: Unveiling the link between solar radiation and suspected presbyopia risk

Presbyopia, a common age-related visual impairment, characterized by difficulty focusing on near objects. Environmental factors, particularly solar radiation, in accelerating presbyopia have not been fully explored. This study examined the longitudinal relationship between solar radiation exposure (specifically top-of-atmosphere shortwave radiation (rsdt), surface solar radiation (SSR), and ultraviolet radiation (UVR)) and the risk of developing suspected presbyopia in Chinese adults aged ≥ 45 years.

Data from 14 058 participants in the China Health and Retirement Longitudinal Study (CHARLS) were analyzed over 2015 to 2018. Solar radiation exposure data were obtained from the National Environmental Ecological Science Data Center. Suspected presbyopia was identified via self-rated near vision difficulty (score 4-5 on a five-point scale). Time-varying Cox proportional hazards models were employed to estimate hazard ratios for the association between solar radiation metrics and the incidence of suspected presbyopia, adjusting for demographic, socioeconomic, and health-related variables.

During follow-up, higher rsdt, SSR, and UVR exposures were each associated with increased suspected presbyopia risk (rsdt: HR 1.47, 95% CI 1.39-1.55; SSR: HR 1.18, 95% CI 1.11-1.25; UVR: HR 1.15, 95% CI 1.11-1.19). Splines indicated linear associations for rsdt (P > 0.05) and nonlinear trends for SSR and UVR (P < 0.001). Subgroup analyses indicated stronger associations in rural residents and smokers. Multi-exposure models confirmed the independent effects of each type of radiation on presbyopia risk.

Higher exposure to solar radiation, including both UV and visible light components, significantly increases the risk of suspected presbyopia in middle-aged and older Chinese adults. These findings highlight the importance of photoprotection strategies, especially for vulnerable subgroups such as rural residents and smokers.