RESUMEN
BACKGROUND AND PURPOSE: The aim of the study was to evaluate the influence of visual control on parameters of postural stability among patients with Parkinson disease (PD) in comparison with control subjects. MATERIAL AND METHODS: Fifty patients diagnosed with idiopathic PD and 50 control subjects without features of central nervous system injury were selected for the study. The clinical diagnosis of idiopathic PD was established according to the clinical criteria of the United Kingdom Parkinson's Disease Society Brain Bank. Only patients in stages I-III according to the Hoehn-Yahr scale were included. The range of sway of the centre of foot pressure (COP) in the frontal plane (COPx) and in the sagittal plane (COPy), as well as the total path length in both axes (COPxy), was tested during quiet standing with and without visual control. RESULTS: COPxy with and without visual control was the smallest in the group of patients in stage II in comparison with patients in stage I and III according to Hoehn-Yahr and in comparison with the control group. CONCLUSIONS: Visual control significantly affects the parameters of postural stability in PD patients.