Reduced visual acuity and its effect on human postural control
Objectives: The goal of this study was to investigate the effect of visual acuity on the anticipatory (APAs) and compensatory (CPAs) components of postural control. Methods: Ten individuals participated in the experiments involving perturbations induced by a pendulum while their visual acuity was altered. The different visual acuity conditions were no glasses, blurred vision induced by wearing glasses with positive or negative lenses, and no vision. EMG activity of trunk and leg muscles and ground reaction forces were recorded during the typical anticipatory and compensatory periods. Results: In the no vision condition the subjects did not generate APAs, which resulted in the largest displacements of the center of pressure (COP) after the perturbation (p<0.01). In all other visual conditions APAs were present showing a distal to proximal order of muscle activation. The subjects wearing positive glasses showed earlier and larger anticipatory EMGs than while wearing negative glasses or no glasses at all. Moreover, the relationship between APAs and CPAs was influenced by differently powered glasses. Significance: The observed changes in APAs and CPAs in conditions with blurred vision induced by positive and negative glasses suggest the importance of individuals’ using glasses with an appropriate power. This outcome should be taken into consideration in balance rehabilitation of individuals wearing glasses.
Listed In: Biomechanics, Neuroscience, Physical Therapy,
Tagged In: Anticipatory Postural Adjustments, Posture, visual acuity
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