Visual acuity and mortality in older people and factors on the pathway

Purpose: To examine vision as a predictor of mortality in older people and the role of mobility, depressed mood, chronic diseases, body mass index, physical activity and injurious accidents in this possible association. Methods: 223 persons aged 75 and 193 persons aged 80 years at the baseline participated in visual acuity measurements. Visual acuity (VA) of 0.3 in the better eye was defined as visual impairment, VA of 0.3 but 0.5 as lowered vision and VA 0.5 as normal VA. Death dates were received from the official register. Cox regression models were used to determine the relative risks of mortality and to study what factors lie on the pathway from poor vision to mortality. Results: Over the 10-year follow-up, 107 (48%) persons aged 75 years and 138 (72%) aged 80 years at the baseline died. The risk for mortality among the 75-year-olds with lowered vision was 1.98 (95 % CI 1.25-3.13) and with visual impairment 1.90 (95% CI 1.12-3.20) compared to those with normal VA. Lower walking speed, physical inactivity, cardiovascular diseases, injurious accidents, diabetes and depressed mood each attenuated the risk markedly. Nevertheless, lowered vision remained a significant predictor of mortality even after including all these variables in the model. Among the 80-year-olds vision did not correlate with mortality. Conclusions: Lowered vision and severe visual impairment predicted mortality in the 75-year-old but not 80-year-old population. The increased risk was partially explained by lower walking speed, physical inactivity, cardiovascular diseases, depressed mood, diabetes and injurious accidents.