Assessment of vestibulo-ocular function without measuring eye movements.
BACKGROUND
The vestibulo-ocular reflex (VOR) maintains stable gaze during head motion. Deficiencies lead to apparent world motion due to incomplete stabilization of eyes in space. VOR measurement requires specialized apparatus, trained operators, and significant setup time.


METHODS
We present a system (VON: vestibulo-ocular nulling) for rapid vestibulo-ocular assessment without measuring eye movements per se. VON uses a head-mounted motion sensor, laptop computer with user input control, and laser target whose position is controlled by the computer. As the head moves, the target is made to move in the same manner with a gain set by the subject. When the subject sets the gain so the target appears stationary in space, it is stationary on the retinas. One can determine from this gain the extent to which the eyes move in space when the head moves, which is the amount by which the VOR is deficient. From this the gain of the compensatory eye movements is derived.


RESULTS
VON was compared with conventional video-based VOR measures. Both methods track expected changes in gain over 20min of adaptation to minifying spectacles. VON measures are more consistent across subjects, and pre-adaptation values are closer to compensatory.


METHODS
VON is a rapid means to assess vestibulo-ocular performance. As a functional perceptual measure, it accounts for gaze-stabilizing contributions that are not apparent in the standard VOR, such as pursuit and perceptual tolerance.


CONCLUSIONS
VON assesses functional VOR performance. Future implementations will make VOR assessment widely available to investigators and clinicians.
Department of Otolaryngology - Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, United States.
Kara H
KH
Beaton
Department of Otolaryngology - Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, United States; Department of Physical Medicine and Rehabilitation, The Johns Hopkins University School of Medicine, Baltimore, MD, United States.
Michael
M
Schubert
Department of Otolaryngology - Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, United States; Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, United States. Electronic address: mshelhamer@jhu.edu.
Mark
M
Shelhamer
D000328:Adult; D001676:Biofeedback, Psychology / Q000295:instrumentation* / Q000502:physiology; D004867:Equipment Design; D019544:Equipment Failure Analysis; D053483:Eye Movement Measurements / Q000295:instrumentation*; D005133:Eye Movements / Q000502:physiology; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology*; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation / Q000295:instrumentation*; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014584:User-Computer Interface
Oculomotor; Perceptual nulling; Rapid assessment; Vestibular; Vestibulo-ocular reflex (VOR)