Binocular vHIT in Healthy Participants: An Optimized Strategy

The objectives of this study were to observe the differences between the left and right eyes in healthy individuals during binocular video head impulse testing (vHIT) and to identify the optimal eye for a more precise evaluation of the vestibulo-ocular reflex (VOR) gain.

This is a prospective two-center study involving 41 healthy individuals. All participants included in the study underwent binocular vHIT, which was performed by experienced technicians.

Significant differences in VOR gain were observed between the left and right eyes across all six semicircular canals when binocular vHIT was used (t ₁ = 3.621, P ₁ = 0.001; t ₂ = 13.929, P ₂ < 0.001; t ₃ = -3.598, P ₃ = 0.001; t ₄ = -3.929, P ₄ < 0.001; t ₅ = -14.380, P ₅ < 0.001; t ₆ = 5.507, P ₆ < 0.001). The gains were higher in the adduction eye than in the abduction eye (t ₁ = 13.929, P ₁ < 0.001; t ₂ = -14.38, P ₂ < 0.001). The gains were lower in the left eye than in the right eye when the left posterior-right anterior (LPRA) plane was tested (t ₁ = 5.507, P ₁ < 0.001; t ₂ = 3.621, P ₂ = 0.001) and the gains were lower in the right eye than in the left eye when the right posterior-left anterior (RPLA) plane was tested (t ₁ = -3.598, P ₁ = 0.001; t ₂ = -3.929, P ₂ < 0.001).

The binocular vHIT can be used as an optimization of monocular vHIT, assisting in selecting the ideal test eye in clinical protocols, aiming for a VOR gain closer to 1. We suggest using the anterior eye as the reference eye during testing of the vertical semicircular canal (SCC) plane and selecting the abducting eye as the reference when testing the horizontal SCC plane.

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