The Waterloo Vision and Mobility Study: Vision Impairment in the Control of Posture

Abstract

The control of stable upright posture is a prerequisite for many tasks of daily living. The transition from quadrupedal to bipedal stance has made this seemingly simple task far more challenging. The base of support has been reduced and the large mass of upper body is balanced high above the ground. The upright stance is regulated by three major sensory modalities, vision, vestibular and the kinesthetic system. Vision provides expropioceptive information about body movements and their relation to the environment. The vestibular system provides a gravio-inertial reference frame, detecting angular and linear accelerations of the head. The kinesthetic system is the source of information about body movements and is referred to the support surface. It is evident that there is overlapping information amongst these three modalities. When one is comprised, the other systems can compensate.