ABSTRACT
The visual influence on upright posture was studied in seven patients with Parkinson's disease (PD), Yahr stage III to IV, and seven age-matched controls. The position of the center of contact pressure (CCP) between the feet and floor was analyzed by a photoelastic method. When the patients' eyes were closed, the CCP position shifted significantly backward in PD (open, 48.6 +/- 7.6%; closed, 45.0 +/- 4.8%; p < 0.01), whereas in controls, it shifted significantly forward (open, 45.5 +/- 5.8%; closed, 48.9 +/- 2.8%; p < 0.05). PD patients put their body weight less on the more affected foot (open, 49.6 +/- 4.5%; closed, 47.0 +/- 4.8%; p < 0.01) and more on the less affected foot (open, 50.4 +/- 4.5%; closed, 53.0 +/- 4.8%; p < 0.005), when the eyes were closed. Visual information is important in maintaining the upright posture in PD patients.
