Ocular torsion induced by static visual stimulation and static whole body roll

Abstract

Objective. This study was aimed to improve the reliability of clinical statolith testing by quantifying the influence of visual orientation and stimulation on the statolith-ocular reflex. Materials and methods. Ocular torsion was induced in 12 healthy adults by visual stimulation and by static whole body roll with and without simultaneous visual orientation. Visual stimulation was achieved by a horizontal grating oscillating sinusoidally in a frontal plane. Visual orientation during whole body roll was established by mounting an illuminated horizontal grating either on a tilting device (head-fixed) or on the wall in the frontal plane (earth-fixed). Results. No eye torsion was observed in static visual tilts of the grating. Dynamic visual stimulation elicited substantial eye torsion. Static whole body roll in the dark induced static ocular counter-rolling. Visual orientation either head- or earth-fixed did not affect the amplitude or gain of the body roll induced ocular counter-rolling. Conclusion. Dynamic visually induced torsional eye movements can be used to test the ability of the oculomotor system to generate torsional eye movements prior to quantifying the statolith-ocular reflex. Simultaneously visual information does not affect the gain of the static statolith-ocular reflex.