Standing balance assessment using a head-mounted wearable device

Background: The presence of accelerometers in smartphones has enabled low-cost balance assessment. Smartglasses, which contain an accelerometer similar to that of smartphones, could provide a safe and engaging platform for virtual and augmented reality balance rehabilitation; however, the validity of headmounted measurement of balance using smartglasses has not been investigated. Objective: To perform preliminary validation of a smartglasses-based balance accelerometry measure (BAM) compared with previously validated waist-based BAM. Methods: 42 healthy individuals (26 male, 16 female; mean age ± SD = 23.8 ± 5.2 years) participated in the study. Following the BAM protocol, each subject performed two trials of six balance stances while accelerometer and gyroscope data were recorded from smartglasses (Google Glass). Test-retest reliability and correlation were determined relative to waist-based BAM as used in the NIH Standing Balance Toolbox. Results: Balance measurements obtained using a head-mounted wearable were highly correlated with those obtained through a waist-mounted accelerometer (Spearman’s rank correlation coefficient = 0.85). Test-retest reliability was high (ICC = 0.85, 95% CI 0.81-0.88), and in good agreement with waist balance measurements (ICC = 0.84, 95% CI 0.80-0.88). Taking into account the total NPL magnitude improved inter-device correlation (0.90) while maintaining test-retest reliability (0.87, 95% CI 0.83-0.90). All subjects successfully completed the study, demonstrating the feasibility of using a head-mounted wearable to assess balance in a healthy population. Conclusion: Balance measurements derived from the smartglasses-based accelerometer were consistent with those obtained using a waist-mounted accelerometer. Given this and the potential for smartglasses in vestibular rehabilitation, the continued development and validation of balance assessment measurements obtained via smartglasses is warranted. This research was funded in part by Department of Defense/Defense Health Program (#W81XWH-14-C-0007, SBIR Phase II contract awarded to TIAX, LLC).