Dynamic visual acuity in bilateral vestibulopathy and healthy age-sex-matched participants

Dynamic visual acuity (DVA) can be assessed on a treadmill while walking at different speeds and is used to assess people with bilateral vestibulopathy (BVP). However, the effects and interactions of age, BVP, and walking speed on DVA loss and assessment dropout are unclear. Our objective was to investigate the effects of BVP, age, and walking speed on DVA loss and assessment dropout in participants with BVP and healthy age-sex-matched participants.

41 participants with BVP and 41 age-sex-matched healthy participants completed a treadmill-based DVA assessment, including a static condition at 0 km/h and walking conditions at 2, 4, and 6 km/h. DVA loss was measured as the visual acuity difference between static and walking conditions. The drop-out rate, handrail use, and DVA loss were examined in relation to BVP, age, and walking speed.

Age significantly increased the odds of dropping out (odds ratio = 1.160, p < 0.001), while BVP did not increase the odds of dropping out (odds ratio = 0.792, p = 0.733). A significant Group*Speed (p = 0.004) interaction effect was found for DVA loss, with DVA loss being significantly worse in people with BVP across all walking speeds, getting progressively worse as speed increased, which was not seen in the healthy participants. Age did not have a significant effect on DVA loss (p = 0.06).

BVP does not appear to restrict the ability to walk at the higher speeds of a DVA assessment and cause an increase in dropout rate, whereas age does. BVP significantly impacts DVA, with increasing impact at increasing walking speeds.