Altered Visual Reliance Induced by Stroboscopic Glasses during Postural Control

Abstract

Little is known about how disrupted vision affects visual reliance during postural control. postural control. Twenty-four physically active adults volunteered to participate in the study. Static postural control was quantified with center of pressure measures during a one-legged balance test with four different visual inputs (eyes-open (EO), high frequency of strobe vision (HSV), low frequency of strobe vision (LSV), and eyes-closed (EC)) and on two different surfaces (firm and foam). Dynamic postural control was calculated by the dynamic postural stability index and the Y-Balance test for three different visual inputs (EO, HSV, and LSV) and the two different surfaces. Romberg ratios (HSV/EO, LSV/EO, and EC/EO) were then calculated and used for statistical analysis to assess visual contribution during postural control. In the results, Romberg ratios were higher when people were on the foam surface than the firm surface in center of pressure total path in medial-lateral and anterior-posterior directions (p < 0.05, both directions). Similarly, Romberg ratios were higher on the foam surface than the firm surface in dynamic stability index in medial-lateral and anterior-posterior directions (p < 0.05, both directions). Stroboscopic glasses could alter visual reliance when the somatosensory system is disturbed by a foam pad during both static and dynamic postural control. Clinicians could use the glasses to manipulate visual reliance during dynamic balance training for patients with musculoskeletal injuries.

Visual reweighting using stroboscopic vision in healthy individuals

“…This intermediate level of visual condition can be utilized to create a more specific rehabilitation by providing a medium level of condition between two extremes. Indeed, a recent study comparing the effects of different levels of SV in rehabilitation in patients with CAI (i.e., higher reliance on visual cues) revealed better outcomes in both static and dynamic balance than those without SV (Lee et al, 2022). No participants in our investigation lost their balance completely, fell, or scored so poorly on a trial that they had an equilibrium score of 0.…”

“…Yet, when the reliability of somatosensory cues was reduced by standing on a foam surface, SV balance and eyes-closed balance were significantly worse than eyes-open balance (Kim et al, 2017). Similarly, uninjured individuals exhibit higher reliance on vision when somatosensory inputs were disturbed during single leg balance (Lee et al, 2022). This follows the idea that balance degrades further when multiple sensory modalities are disrupted or become unreliable.…”

Evaluating Visual Dependence in Postural Stability Using Smartphone and Stroboscopic Glasses

“…Conversely, when vision is obstructed, or when eyes are closed, the vestibular system predominantly facilitates postural stability. The inclusion of different conditions in the testing protocol, such as eyes open (EO), eyes closed (EC), and the inclusion of strobe vision, was designed to determine the degree of visual dependency required for balance maintenance [5]. Introducing a strobe condition could elucidate the reliance on visual input for maintaining upright posture during static and dynamic tasks, potentially highlighting dysfunction in the integration between vestibular and visual feedback systems [8].…”

“…For example, modifying the flickering rate of stroboscopic glasses-by increasing the duration of opaque phases-may improve proprioceptive and vestibular functions. Conversely, a higher flicker rate could enhance visual system training [5]. Thus, this protocol, utilizing an app paired with stroboscopic glasses, proves valuable for both assessment and training purposes.…”

“…Altered visual conditions, such as eyes closed, dim lighting, or visual perturbations, significantly increase the risk of injuries due to compromised postural stability [2]. These conditions necessitate greater contributions from the vestibular and proprioceptive systems to maintain balance, especially on unstable surfaces like foam, which distorts proprioceptive feedback and increases the difficulty of maintaining postural control [5]. This is particularly evident in athletes who have suffered from musculoskeletal injuries, such as chronic ankle instability [6,7], or neurological impairments, like concussions [8,9], where an increased reliance on visual input for balance has been documented.…”