Postural stability requires an interaction between cognitive, perceptual, sensory, and motor functions. Thus, impairment in any of these systems may affect postural balance. This study assessed the effect of visual input and surface slope on postural stability. The study was conducted on healthy participants, 11 females and 11 males who were 24-34 years of age. They were asked to perform still upright bipedal standing on flat and +/-20° sloped surfaces with eyes open (EO) and closed (EC). Six center of pressure (COP) parameters were measured by posturography. A significant relationship was observed between COP parameters, standing conditions, and body mass index. Gender had no significant effect on the COP. The loss of visual input within each standing condition did not affect the COP parameters. In contrast, differences were observed between standing on a flat surface and uphill with EC and between standing on a flat surface and downhill with EC and EO. When the participants were standing on inclined surfaces, the loss of vision significantly increased the postural instability. Young healthy adults demonstrated the greatest difficulty in standing uphill with EC. This was followed by standing downhill with EC and standing downhill with EO.
Keywords: balance control; body oscillation; center of pressure; inclined surface; postural stability; posturography.