Abstract
Purpose:
Deteriorated visual function is one important risk factor for the detrimental balance control in older adults. Most studies examined the relationship between static visual and balance functions, largely ignoring that between dynamic vision and balance. In this study, we examined dynamic visual function and its interaction with balance in young and old people.
Methods:
Fifteen younger (aged 21-40 years) and twelve community-dwelling participants (60 years or above) with normal vision were recruited. Visual acuity (VA) and contrast sensitivity (CS) were measured by Psykinematix for stimuli of different optotypes or gratings moving at 5 different speeds (0, 15, 30, 60 and 90 deg/sec). Static balance was measured by a force platform when the participant stood on a firm or foam surface while fixating at different targets. Dynamic balance was measured by limits of stability test where the participants were asked to make a corresponding weight shift as maximal as possible within their base of support to 8 positions whenever individual stimulus representing the weight shift at a particular position showed in the monitor.
Results:
VA and CS significantly deteriorated for recognizing moving objects as the speed increased. However, such deterioration became plateau when the moving speed reached 30 deg/sec, where the young group performed better (p<0.05). Age-related decline was only found in CS (p<0.001), but not in VA. Standing on a compliant foam surface imposed significant impediment on postural control (p<0.05). Both static (in terms of total sway area) and dynamic balance (in terms of averaged maximum excursion at 8 orientations) were significantly impaired in the older group (p<0.05), however the extent of deterioration was much stronger in the dynamic (rs=-0.682) than static balance (rs=0.10). Multivariate analyses showed that dynamic vision could weakly correlate with static balance (rs= 0.01), but significantly correlate with dynamic balance (rs=-0.514).
Conclusions:
As a consequence of aging, both visual and balance functions were significantly deteriorated. However, stronger age-related decline occurred when both vision and balance were measured in dynamic perspective. In addition to age, a much stronger relationship was established between dynamic vision and dynamic balance, implying that a person with poorer dynamic vision has weaker dynamic balance control.
Keywords: 413 aging •
414 aging: visual performance •
753 vision and action