THE VESTIBULO-OCULAR REFLEX IN CHILDREN

Background and objectives: The vestibulo-ocular reflex (VOR) stabilizes images on the retina and maintains clear vision during head movements. Little information is available on the horizontal and vertical VOR in children. The study aims were to determine VOR characteristics in typically developing children and to investigate the effects of age or gender on VOR.

Methods: We recorded the angular VOR using an infrared eye tracker and magnetic head tracker in 38 typically developing children, aged 8–19 years (21 males). Participants made active sinusoidal head-on-body rotations in yaw (side-to-side) and pitch (up-down) at about 0.5Hz and 2Hz frequencies in darkness (the VOR) while viewing an imaginary target 25cm away, and in the light while viewing an earth-fixed target 57cm away to assess the visually enhanced VOR (the VVOR).

Results: The mean horizontal VOR gain, the ratio of eye to head velocity at 0.5Hz head rotation (head velocities of 18.5–23.4°/s) was 1.28 in the light and 1.06 in the dark. VVOR gains greater than one are attributed to near viewing. Mean horizontal VOR gain was higher than vertical VOR gain at both frequencies of head rotations (p=0.016) in the dark. Median horizontal VOR phase, the lag between eye and head velocities, was 0.6–3.3° at 0.5Hz head rotations. VOR gain did not vary with age or gender.

Conclusion: VOR gains and phases in children were similar to reported adult values. This implies functional maturity of the VOR arc in children 8 years old or older.

Keywords: vestibulo-ocular reflex, development, eye movements