Validity, reliability and precision of a novel virtual reality rod and disk test to assess visual dependence

Visual dependence (VD) is heightened in pathologies where balance is compromised. It is measured using the Rod and Disk Test (RDT), traditionally delivered through a personal computer (PC). This restricts settings under which the test can be taken. This study aimed to evaluate validity, reliability and measurement precision of a novel virtual reality (VR) RDT. VD of 15 healthy participants and 15 people with symptomatic hypermobility was assessed using VR- and PC-based RDT to evaluate convergent validity. Assessments were conducted in three head positions. Intra-rater reliability was assessed by measuring VD of 15 healthy participants seven days apart. Convergent validity was evaluated using correlation analysis; intra-rater reliability using intraclass correlation coefficients. Bland-Altman plots assessed agreement, and measurement precision was reported as standard error of measurement (SEM) and minimal detectable change (MDC). Weak to moderate convergent validity was seen between VR- and PC-based tests, with coefficients of 0.3, 0.4 and 0.3. PC-based RDT showed poor to moderate ICCs; the VR-based RDT demonstrated poor ICCs. SEM and MDC for PC ranged from 0.44-0.47° and 1.23-1.30° respectively; for VR they ranged from 0.65-0.78° and 1.81-2.17° respectively. VR-based RDT demonstrated weak to moderate convergent validity and poor intra-rater reliability.