Visual contributions to postural stability in older adults

Background: With advancing age, there is a generalized reduction in visual functioning wt-rich has been associated with impaired postural stability an d increased risk of falls. However, little is known about which visual abil ities are the most important in the control of postural sway when standing. Objective: To determine whether specific visual abilities predict stabilit y when standing on firm and compliant surfaces. Methods: Tests of visual fu nction, peripheral sensation, strength, reaction time and sway were adminis tered to 156 community-dwelling men and women aged 63-90 years. The visual tests included high- and low-contrast visual acuity, contrast sensitivity, depth perception, stereopsis and lower visual field size. Postural sway was measured with eyes open on a firm and a compliant foam rubber surface. Res ults;: On the firm surface, sway was significantly associated with only one sensorimotor measure: proprioception in the lower limbs. In contrast, on t he compliant surface, sway was associated with all of the visual measures, quadriceps strength and reaction time. Multiple regression analysis reveale d that contrast sensitivity, stereopsis and quadriceps strength were signif icant independent predictors of total sway when subjects stood on the compl iant surface. Conclusion: The study findings confirm the importance of visi on, in particular contrast sensitivity and stereopsis, in the control of po sture under challenging conditions, and suggest some mechanisms for the ass ociation between impaired vision and falls in older people. Copyright (C) 2 000 S. Karger AG, Basel.