Moderate Impairment in Binocular Contrast Sensitivity Predicts Faster Mobility Decline in Cognitively Unimpaired Older Adults.

BACKGROUND

Impaired contrast sensitivity (CS) commonly occurs in older adults but has been largely overlooked as a contributing factor to functional impairment and decline. We examined if CS impairment predicts decline in performance on the expanded short physical performance battery (eSPPB) over 30 months of follow-up in cognitively healthy older adults.

METHODS

Single center prospective cohort study of 192 cognitively unimpaired older adults with good visual acuity and self-reported visual function. Linear mixed models examined the difference in the association of moderately impaired baseline CS (logCS < 1.55) with performance on the eSPPB and its components-balance, 4 m gait speed, narrow walk, and chair pace-over 30 months. Multivariable models adjusted for the effect of age, race, and sex on the slopes over time.

RESULTS

At baseline, the mean participant age was 76.5 ± 4.7 years, with 56.5% (N = 108) female and 9.4% (N = 18) black. Participants with moderately impaired CS at baseline had a significantly faster decline in eSPPB over a 30-month period (Beta: -0.115, 95% CI (-0.180, -0.050), p < 0.001) compared with those with normal CS (Beta: -0.022, 95% CI (-0.044, -0.001), p = 0.042). There was a difference in slopes of -0.093 units/year ((95% CI, -0.161, -0.024), p = 0.009) between groups. This difference in slopes remained significant after adjusting for the effect of age, sex, and race (difference in slopes -0.086, 95% CI (-0.155, -0.016), p = 0.016). Impaired CS predicted significantly greater declines in balance over 30 months (difference in slopes -3.512 (-6.826, -0.199), p = 0.0378), but the differences in gait speed, narrow walk, and chair pace were not significant.

CONCLUSIONS

In cognitively intact older adults with good visual acuity, moderately impaired CS was associated with a significantly faster decline in eSPPB, especially balance, over 30 months of follow-up. A relatively simple test of vision may identify a subset of older adults without cognitive dysfunction who are at risk for mobility decline.