The Influence of Lower Limb Somatosensory Weighting on Visual Dependency Reduction Following Virtual Reality-Based Optokinetic Stimulation in Healthy Adults

Purpose: This study sets out to investigate the hypothesis that differences in lower-limb somatosensory weighting influence the improvement in visual dependency after single-session optokinetic stimulation (OKS) using virtual reality (VR) in healthy adults. Methods: The study population comprised 30 young, healthy adults without musculoskeletal or neurological disorders. Visual dependency was measured pre- and post-OKS using the Romberg ratio (open-eye to closed-eye postural sway ratio). Somatosensory weighting was assessed using sway differences on a foam pad compared to a firm surface, with participants categorized into high somatosensory weighting (HSS) or baseline somatosensory weighting (BSS) groups. The OKS involved wearing VR goggles and viewing rotating visual stimuli for a period of two minutes. Results: In the BSS group, the closed-eye postural sway area and velocity significantly decreased post-OKS, along with reductions in Romberg ratios, indicating reduced visual dependency. In contrast, the HSS group showed no significant changes in postural sway or visual dependency metrics post-OKS. Conclusions: VR-based OKS effectively reduced visual dependency in individuals with baseline somatosensory weighting but had limited impact on those with high somatosensory weighting due to a ceiling effect. These findings underscore the necessity of considering individual sensory weighting when implementing VR balance training for rehabilitation purposes.