Cause-specific visual impairment and mortality - Results from a population-based study of older people in the United Kingdom

Objective: To assess the association between mortality and cause-specific visual impairment in older people. Methods: Visual acuity and causes of visual impairment were collected in 13 569 participants 75 years and older participating in a randomized trial of health screening. Participants were followed up for mortality for a median of 6.1 years. Results: Compared with those with 6/6 (or 20/20 Snellen) or better visual acuity, the age- and sex-adjusted rate ratio for visually impaired people (binocular visual acuity < 6/18 or < 20/60 Snellen) was 1.60 (95% confidence interval, 1.47-1.74), which was markedly attenuated (rate ratio, 1.17; 95% confidence interval, 1.07-1.27) after adjustment for confounding factors. People whose visual impairment was due to cataract or age-related macular degeneration had excess risks of all-cause and cardiovascular mortality, which disappeared after adjustment. People with refractive error remained at small risk, despite adjustment, probably owing to residual confounding from factors associated with minimal use of eye services rather than underlying eye disease. There were no associations with cancer mortality. Conclusion: Associations reported for visual impairment and mortality or for specific causes of visual impairment reflect confounding by comorbidities, risk factors, and other factors related to susceptibility to death rather than an independent biological association of vision problems or specific eye diseases.