Age–period–cohort analysis of the global burden of visual impairment according to major causes: an analysis of the Global Burden of Disease Study 2019

Background Cataract, glaucoma and age-related macular degeneration (AMD) are major causes of visual impairment. As these are age-related conditions, the prevalence of associated visual impairment is anticipated to increase as the population ages. However, age–period–cohort effects on the disease burden have not been investigated. Methods This was a population-based study using aggregated data from the Global Burden of Disease Study 2019. Age–period–cohort analysis was conducted using age-standardised prevalence rates (ASPRs) of visual impairment caused by cataract, glaucoma and AMD as disease burden indicator. Results In 2019, the estimated global ASPRs of visual impairment due to cataract, glaucoma and AMD were 1207.9, 94.7 and 96.8 per 100 000 people, respectively. Between 1990 and 2019, the global visual impairment ASPRs for glaucoma and AMD declined by 15.4% and 2.0%, respectively, whereas that for cataract increased by 5.0%. Wide heterogeneity was observed in age–period–cohort effects on ASPRs across different Sociodemographic Index (SDI) regions. Low-middle SDI regions had the largest ASPR reductions for all three eye diseases and showed improvement in both period and cohort effects. In contrast, in high-middle SDI regions, visual impairment ASPRs significantly increased during the study period with unfavourable patterns. Conclusions The wide heterogeneity in age–period–cohort effects reflects different stages of societal transition and vision health. The unfavourable trends in age–period–cohort effects on disease prevalence identified in specific groups provide key information that may be used to identify priority groups in need of treatment and prevention.