Virtual Reality–Based Subjective Visual Vertical Testing: A Scoping Review of Measurement Methods

Virtual reality–based subjective visual vertical (VR-SVV) testing is a portable method for assessing verticality perception relative to gravity, but its protocols remain inconsistent. This scoping review examined the basic VR-SVV outcomes, reliability, validity, and implementation of head-mounted display–based VR-SVV testing in healthy adults. Six databases and two trial registries were searched through 14 January 2025 and updated on 8 July 2026. Twenty-seven studies involving 1289 participants and 12 VR-SVV systems were included. Protocols comprised static upright, head-tilt, dynamic-background, and study-specific paradigms. Group-level static upright values ranged from −1.58° to 2.2°, within the commonly used ±2.5° SVV reference range. However, 2.1–13.3% of participants had signed mean values outside the ±2.5° reference range. Six studies reported reliability for static upright testing using intraclass correlation coefficients (0.38–0.85), including within-session repeatability; five reported standard errors of measurement and minimal detectable changes; and six performed Bland–Altman analyses. Head-tilt results varied widely across studies, while differences in protocols and calculation methods limited comparisons of both head-tilt and dynamic SVV results. VR-induced symptoms were reported mainly during dynamic or demanding protocols. VR-SVV appears feasible and potentially useful; however, standardized procedures, outcomes, reference values, and adverse-event reporting are still required to enable reliable comparisons across systems and populations.