Objectives: Our study investigates measurement, correlates, and functional associations of vision impairment (VI) in an aging population in rural South Africa. Methods: 1582 participants aged 40-69 reported on near (NVI) and distance vision impairment (DVI) and completed objective vision tests. Logistic and linear regression were used to evaluate sociodemographic, health, and psychosocial correlates of VI and assess relationships between VI and cognitive and physical function. Results: VI prevalence was considerably higher according to objective testing (56%) versus self-reports (18%). Older adults were especially likely to underreport impairment. Objective VI was associated with age, education, cardiometabolic disease, and female sex. Conversely, self-reported VI was associated with psychosocial factors. Objective NVI and both types of DVI were associated with worse visual cognition and slower gait speed, respectively. Discussion: Self-reported and objective VI measures should not be used interchangeably in this context. Our findings highlight extensive burden of untreated VI in this region.
Keywords: cognitive function; measurement; physical function; sub-Saharan Africa; vision impairment.