Trends in the prevalence of vision impairment among the oldest-old Chinese population from 1998 to 2018

Background Vision impairment has become a prominent public health issue worldwide. However, little is known about vision impairment prevalence trends among the oldest-old adults in China. This study aimed to examine 20-year trends in the prevalence of vision impairment among the oldest-old Chinese adults and explore the contributions of sociodemographic variables, health behaviours, and chronic conditions to the trends. Methods This retrospective longitudinal study used data from the Chinese Longi-tudinal Healthy Longevity Survey during 1998-2018. A total of 45 849 participants aged >= 80 years at study entry were included. Vision impairment was assessed by an adapted Landolt-C chart at each wave. We examined unadjusted and adjust-ed nonlinear trends using generalized estimating equation models incorporating a natural cubic spline. We conducted linear regression models to estimate absolute annual prevalence changes and determine the contributions of sociodemographic variables, health behaviours, and chronic conditions to the trends. Results The fully adjusted prevalence doubled from 5.5% (95% confidence interval (CI) = 5.1%-6.0%) in 1998 to 10.7% (95% CI = 9.9%-11.5%) in 2011 and slightly increased to 11.1% (95% CI = 10.3%-12.0%) in 2018 among the oldest-old Chinese population. Glaucoma, cataracts, cognitive impairment, hearing impairment, and urban residence were significant contributors to changes in vision impairment prev-alence during 1998-2018. Differences in vision impairment prevalence associated with glaucoma and cataracts narrowed since 2005. Disparities in the trends among cognitively impaired and unimpaired older adults remained unchanged over time. Similar results were observed in older people with and without hearing impairment. Conclusions Vision impairment prevalence among the oldest-old Chinese popula-tion increased from 1998 to 2011 and remained stable from 2011 to 2018. Future work is needed to improve the prevention and management of chronic diseases associated with vision impairment to reduce its prevalence.