Effects of subjective visual verticality and visual dependence on balance function in older adults using a smartphone-based virtual reality system

Abstract

Balance is controlled by visual, somatosensory, and vestibular sensory inputs. Older adults rely on visual information for balance control, and those with a history of falls have been reported to exhibit higher visual dependence. Additionally, high visual dependence may affect velocity-related parameters, such as gait speed. However, whether visual dependence is related to specific measures of postural control in older adults remains unclear. This study aimed to investigate the relationship between visual dependence and balance in older adults. This was a single-center, cross-sectional, observational study involving 50 healthy older adults with a mean age of 72.0 ± 4.6 years. Visual dependence was assessed by measuring the static and dynamic subjective visual vertical (SVV) using a smartphone-based virtual reality method. Balance function was assessed using stabilometry and the mini-balance evaluation systems test (Mini-BESTest). The main outcome was medial-lateral sway velocity. Multivariate analysis was performed with each balance function (Mini-BESTest score, sway path, amplitude, and mean sway velocity) as the dependent variable and age, height, static SVV, and visual dependence as the independent variables. The results indicated that visual dependence was significantly associated with medial-lateral mean sway velocity in the eyes-closed foam surface condition (β = 0.41, p = .011, R² = 0.19). This suggests that older adults with high visual dependence may experience reduced static balance under conditions of limited visual and somatosensory inputs. These findings highlight the importance of considering visual dependence in balance assessment and rehabilitation programs for older adults with balance disorders.