Novel gaze stability training improves dynamic visual acuity for 6 months

ObjectivesPeripheral vestibular hypofunction (PVH) affects a significant portion of the population and impairs visual acuity during head motion (dynamic visual acuity, DVA). This study compared the effectiveness of a novel gaze stability training called Incremental VOR Adaptation (IVA) versus traditional vestibular physical therapy (VPT) for improving DVA.MethodsThe Incremental Velocity Error as a New Treatment in Vestibular Rehabilitation (INVENT) trial is a randomized, controlled, cross-over study involving 24 participants with chronic unilateral or bilateral PVH. Participants underwent either IVA or VPT for 3 weeks, followed by a washout period and then the alternate intervention (IVA-VPT or VPT-IVA). DVA was measured at baseline, after each intervention, at the completion of the washout period, and at 6-month follow-up.ResultsThere was a significant main effect of treatment Group, F (1,19) = 7.75, p = 0.012, with (IVA-VPT) consistently demonstrating lower DVA scores than VPT-IVA. A significant main effect of Side was also observed, F (1,19) = 13.35, p = 0.0017, indicating lower DVA scores for contralesional compared to ipsilesional head rotation. We found no effect of Time (F (4,76) = 1.44, p = 0.23), suggesting that scores remained stable from baseline through the 6-months follow-up. There were no significant interactions, including Group × Side (F (1,19) = 0.11, p = 0.74), Group × Time (F (4,76) = 1.33, p = 0.27), or Group × Side × Time (F (4,76) = 0.59, p = 0.67).ConclusionDVA scores were consistently better at all time points after participants completed IVA. Using an intent to treat analysis, with no baseline demographic differences between groups, our data support that exposure to the first gaze stability training type exerts a stable influence on DVA that persisted to 6-month follow-up. Clinically, this implies that once DVA improvements are established through either IVA or VPT, they tend to remain stable over 6 months.Level of EvidenceLevel 2.