Visual impairment and incident mobility limitations: The health, aging and body composition study

OBJECTIVES: To examine the association between multiple measures of visual impairment (VI) and incident mobility limitations in older adults. DESIGN: Prospective observational cohort study. SETTING: Memphis, Tennessee, and Pittsburgh, Pennsylvania. PARTICIPANTS: Health, Aging and Body Composition study participants aged 70 to 79 without mobility limitations at the Year 3 visit (N = 1,862). MEASUREMENTS: Vision was measured at the Year 3 visit, and VI was defined as distance visual acuity (VA) worse than 20/40, contrast sensitivity (CS) less than 1.55 log Contrast, and stereoacuity (SA) greater than 85 arcsec. Incident persistent walking and stair climbing limitation was defined as two consecutive 6-month reports of any difficulty walking one-quarter of a mile or walking up 10 steps after 1, 3, and 5 years of follow-up. RESULTS: At Year 3 (baseline for these analyses), 7.4% had impaired VA, 27.2% had impaired CS, and 29.2% had impaired SA. At all follow-up times, the incidence of walking and stair climbing limitations was higher in participants with VA, CS, or SA impairment. After 5 years, impaired CS and SA were independently associated with greater risk of walking limitation (hazard ratio (HR)_CS = 1.3, 95% confidence interval (CI) = 1.1-1.7; HR_SA = 1.3, 95% CI = 1.1-1.6) and stair climbing limitation (HR_CS = 1.4, 95% CI = 1.1-1.8; HR_SA = 1.3, 95% CI=1.1-1.7). Having impaired CS and SA was associated with greater risk of mobility limitations (HR_{walking limitations} = 2.0, 95% CI = 1.6-2.5; HR_{stair limitation} = 2.1, 95% CI = 1.6-2.8). CONCLUSION: Multiple aspects of VI may contribute to mobility limitations in older adults. Addressing more than one component of vision may be needed to reduce the effect of vision impairment on functional decline.