Global, regional, and national burden of refraction disorders: findings from the global burden of disease study 2021 and projections to 2050.

Background: Refraction disorders are the leading cause of visual impairment worldwide. This study investigates the global burden and trends of refraction disorders from 1990 to 2021, with projections extending to 2050.

Methods: Data on prevalence and disability-adjusted life years (DALYs) for refraction disorders, along with their 95% uncertainty intervals (UIs), were obtained from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021. The study provides a comprehensive analysis of the epidemiology of refraction disorders at global, regional, and national levels. It examines trends from 1990 to 2021 from multiple dimensions, including overall and localized changes. Burden decomposition was performed to assess contributions from population size, age structure, and epidemiological changes. Cross-country inequalities were quantified using standard health equity methods recommended by the World Health Organization. Future changes in the burden of refraction disorders were also projected through 2050.

Results: According to GBD 2021 estimates, there were 159,765,917 prevalent cases (95% UI: 142,526,915-178,698,348) and 6,618,600 DALYs (95% UI: 4,599,082-9,528,676) due to refraction disorders globally in 2021. From 1990 to 2021, prevalence and DALYs rates demonstrated a steady decline, although prevalence numbers, incidence numbers, and rates were consistently higher among females compared to males. Decomposition analysis showed that aging, population growth, and epidemiological changes contributed 36.25%, 76.92%, and - 13.18%, respectively, to changes in the age-standardized prevalence rate (ASR). The concentration index declined from - 0.17 (95% CI: -0.21 to - 0.13) in 1990 to - 0.10 (95% CI: -0.13 to - 0.07) in 2021, indicating a reduction in SDI-related inequalities. By 2050, the ASR for prevalence and DALYs is projected to decline to 1815.27 (95% UI: 534.15-3096.40) and 69.11 (95% UI: 21.45-116.77), respectively.

Conclusion: The global burden of refraction disorders decreased significantly from 1990 to 2021 and is expected to decline further by 2050. Females continue to experience a greater burden compared to males. Population growth emerged as the primary driver of changes in the ASR of prevalence and DALYs. While countries with low socio-demographic index (SDI) face a disproportionately high burden, SDI-related inequalities have gradually lessened over time.