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

Abstract

By means of real-time infra-red video-oculography we studied eye torsion in 12 normal healthy subjects. Ocular torsion was induced by visual stimulation or static whole body roll with and without visual orientation ("head-fixed" or "earth-fixed"). Visual stimulation was achieved by a horizontal grating that oscillated sinusoidally in a frontal plane. The oscillation frequency varied from 0 to 0.6 Hz while amplitude varied from 6 degrees to 33 degrees. Visual orientation during whole body roll was established by mounting a 32 lx illuminated horizontal grating either on a tilting device (head-fixed) or on the wall in the frontal plane (earth-fixed). Maximum visual-induced eye torsion gain was reached at about 0.2 Hz. No eye torsion was observed in static (0 Hz) visual tilts of the grating. Maximum gain was about 0.36 at amplitudes between 6 degrees and 10 degrees. Eye torsion gain decreased with increasing amplitude and increasing frequency (> 0.2 Hz). Static whole body roll in the dark up to 180 degrees clockwise and counterclockwise induced static ocular counter rolling with a maximum amplitude of 12 degrees and a maximum gain of 0.22. Gain decreased with increasing roll down to zero at 180 degrees. Visual orientation with either head or earth fixed did not affect the amplitude or gain of the body roll induced ocular counter-rolling. The results are interpreted in terms of improving the reliability of clinical statolith testing and understanding the processes involved in motion sickness.

Understanding skew deviation and a new clinical test to differentiate it from trochlear nerve palsy

“…[38][39][40] This torsional vestibulo-ocular reflex, termed ocular counterroll, however, compensates for only about 10% to 20% of the head tilt (eg, a 20° head tilt toward the right shoulder will result in the upper pole of both eyes to rotate 2° to 4° toward the left shoulder). [38][39][40] Static ocular counterroll is important from a clinical standpoint because this otolith-driven reflex forms the basis of the Bielschowsky head-tilt test and it explains the compensatory head tilt in patients with trochlear nerve palsy. In normal humans, for example, during right head tilt, the static ocular counterroll activates the right superior oblique and superior rectus muscles, causing the right eye to incyclotort and elevate slightly.…”

Estudo dos movimentos torcionais em cirurgia refrativa

“…Este trabalho vem demonstrar que apesar de alguns trabalhos negarem a existência dos movimentos torcionais do globo ocular na mudança de decúbito (6)(7)(8) , eles não só ocorrem, como são de magnitude expressiva (com média de 3,5º; desvio padrão 1,9º; variando de zero grau no mínimo a 9º no máximo). Isto é especialmente relevante quando se analisa o exposto anteriormente em relação à eficácia do tratamento.…”

Evaluation of the Statolith Function by Measurement of Ocular Counterrolling?

“…Eye torsion can also be induced by dynamic visual stimulation rotating around the visual axis. However, visual-induced eye torsion is maximally only 3-4° and optimal at 0.2-0.3 Hz [25].…”

“…In the clinic, OCR is studied as a response to static head or body roll, as well as to slow dynamic whole body rolls [1,12,25,27,28]. To define normative data, Vogel et al [20] took OCR data from 12 publications, averaged all results (though the precise stimulus protocols and equipment differed from each other) and defined a borderline between normal and pathological OCR: minimal gain = 0.2991-0.1179 log (roll angle), maximum gain = 0.4623-0.2113 log (roll angle).…”