Aliza Maqsood¹, Lisa Lavalle², Taylor Cleworth¹; ¹School of Kinesiology and Health Science, York University, ²School of Medicine, Queen's University

INTRODUCTION: Falls caused by balance deficits are a major concern among older adults. Visual feedback provides a crucial source of sensory information to maintain postural control. Optimizing the visual environment could help support postural control among populations with an increased fall risk. Previous work has shown that both contrast and spatial frequency changes can contribute to postural instability in patients with cataracts. Therefore, the aim of this study was to explore the effect of modifying contrast and spatial frequency intensities in a virtual environment on upright stance. METHODS: 28 healthy participants stood quietly on a force plate with feet together while wearing a virtual reality (VR) headset. Four conditions modified the level of contrast (low or high) and/or spatial frequency (high or low) of the wallpaper surrounding a virtual room. Each trial was 60s and each of the four conditions were completed on both a firm and foam surface. Anteroposterior (AP) and mediolateral (ML) center of pressure (COP) was calculated from ground reaction forces and moments, and AP head displacement (HD) was captured from the VR headset. Root mean square (RMS) was calculated to quantify amplitude for all variables. RESULTS: There was a significant main effect of contrast on COP AP RMS and HD AP RMS for firm and foam conditions, and COP ML RMS on foam only, where RMS increased as contrast decreased. There was also a significant main effect of spatial frequency on COP ML RMS for foam conditions only, where RMS increased as spatial frequency decreased. No other interactions or main effects were observed. CONCLUSIONS: Overall, participants postural stability decreased when exposed to lower levels of contrast and spatial frequency. Therefore, visual cues in the environment should be taken into consideration when designing environments for older adults, such as residential and long-term care facilities.

Acknowledgements: Vista at York University and Natural Sciences and Engineering Research Council of Canada (NSERC)