Accession Number : ADA316577

Title :   Visual Vestibular Interaction in the Dynamic Visual Acuity Test during Voluntary Head Rotation.

Descriptive Note : Final rept.,

Corporate Author : ARMY AEROMEDICAL RESEARCH LAB FORT RUCKER AL

Personal Author(s) : Lee, Moo H. ; Durnford, Simon ; Crowley, John ; Rupert, Angus

PDF Url : ADA316577

Report Date : AUG 1996

Pagination or Media Count : 32

Abstract : Although intact vestibular function is essential in maintaining spatial orientation, no good screening tests of vestibular function are available to the aviation community. High frequency voluntary head rotation was selected as a vestibular stimulus to isolate the vestibulo-ocular reflex (VOR) from visual influence. A dynamic visual acuity test that incorporates voluntary head rotation was evaluated as a potential vestibular function screening tool. Twenty-seven normal subjects performed voluntary sinusoidal head rotation at frequencies from 0.7-4.0 Hz under three different visual conditions: visually-enhanced VOR, normal VOR, and visually suppressed VOR. Standardized Baily-Lovie chart letters were presented on a computer monitor in front of the subject, who then was asked to read the letters while rotating his head horizontally. The electro-oculogram and dynamic visual acuity score were recorded and analyzed. There were no significant differences in gain or phase shift among three visual conditions in the frequency range of 2.8 to 4.0 Hz. The dynamic visual acuity score shifted less than 0.3 logMAR at frequencies under 2.0 Hz. The dynamic visual acuity test at frequencies around 2.0 Hz can be recommended for evaluating vestibular function.

Descriptors :   *SPATIAL DISTRIBUTION, *VESTIBULAR APPARATUS, *VISUAL ACUITY, *OCULOMOTOR NERVE, FREQUENCY, FUNCTIONS, HIGH FREQUENCY, COMMUNITIES, MONITORING, INTERACTIONS, COMPUTERS, DYNAMICS, ORIENTATION(DIRECTION), AERONAUTICS, VISION, STIMULI, ROTATION, DYNAMIC TESTS, PHASE SHIFT.

Subject Categories : Anatomy and Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE