Viewing Target Distance Influences the Vestibulo-Ocular Reflex Gain when Assessed Using the Video Head Impulse Test
Journal
Audiology and Neurotology
ISSN
1420-3030
1421-9700
Date Issued
2019
Author(s)
Sara Sena Esteves
Florencia Lerchundi
David Buckwell
Michael A. Gresty
Adolfo M. Bronstein
Qadeer Arshad
Type
Resource Types::text::journal::journal article
URL Institutional Repository
Abstract
<jats:p>Gaze stabilization during head movements is provided by the vestibulo-ocular reflex (VOR). Clinical assessment of this reflex is performed using the video Head Impulse Test (vHIT). To date, the influence of different fixation distances on VOR gain using the vHIT has not been explored. We assessed the effect of target proximity on the horizontal VOR using the vHIT. Firstly, we assessed the VOR gain in 18 healthy subjects with 5 viewing target distances (150, 40, 30, 20, and 10 cm). The gain increased significantly as the viewing target distance decreased. A second experiment on 10 subjects was performed in darkness whilst the subjects were imagining targets at different distances. There were significant inverse relationships between gain and distance for both the real and the imaginary targets. There was a statistically significant difference between light and dark gains for the 20- and 40-cm distances, but not for the 150-cm distance. Theoretical VOR gains for different target distances were calculated and compared with those found in light and darkness. The increase in gain observed for near targets was lower than predicted by geometrical calculations, implying a physiological ceiling effect on the VOR. The VOR gain in the dark, as assessed with the vHIT, demonstrates an enhancement associated with a reduced target distance.</jats:p>
Subjects
video head impulse test
;
convergence
;
vestibulo-ocular reflex
;
adult
;
female
;
head impulse test
;
head movements
;
healthy volunteers
;
humans
;
male
;
reflex, vestibulo-ocular
;
young adult
;
adult
;
article
;
calculation
;
clinical article
;
controlled study
;
cornea reflex
;
darkness
;
female
;
head impulse test
;
human
;
human experiment
;
male
;
theoretical study
;
videorecording
;
head impulse test
;
head movement
;
normal human
;
physiology
;
vestibuloocular reflex
;
young adult