Visual contributions to postural stability in older adults

With advancing age, there is a generalized reduction in visual functioning which has been associated with impaired postural stability and increased risk of falls. However, little is known about which visual abilities are the most important in the control of postural sway when standing.

To determine whether specific visual abilities predict stability when standing on firm and compliant surfaces.

Tests of visual function, peripheral sensation, strength, reaction time and sway were administered 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.

On the firm surface, sway was significantly associated with only one sensorimotor measure: proprioception in the lower limbs. In contrast, on the compliant surface, sway was associated with all of the visual measures, quadriceps strength and reaction time. Multiple regression analysis revealed that contrast sensitivity, stereopsis and quadriceps strength were significant independent predictors of total sway when subjects stood on the compliant surface.

The study findings confirm the importance of vision, in particular contrast sensitivity and stereopsis, in the control of posture under challenging conditions, and suggest some mechanisms for the association between impaired vision and falls in older people.