Many low vision patients have impaired central acuity but cannot successfully use telescopic spectacles despite the theoretical benefit from magnification. This may be because visual rehabilition with telescopic spectacles is limited by instability of the magnified retinal image during involuntary head movements, and during coordinated eye-head movements necessitated by visual search. Retinal image stability is ordinarily provided by the visual-vestibulo- ocular reflex (VVOR), produced by interaction of the vestibulo-ocular reflex with visual and predictive mechanisms (visual vestibular interaction VVI). VVOR performance with telescopic spectacles must be quantitatively appropriate to magnification to avoid substantial impairment of dynamic visual acuity during head movements. The overall aim is to quantitatively evaluate mechanisms of visual-vestibular interaction in the vertical plan, as determinants of useful vision with telescopic spectacles during physiologic head movements. Eye and head movements will be measured using magnetic search coils, supplemented by infrared oculography. The effect of telescopic spectacles on vertical VVOR will be quantitatively characterized in the physiologic range of active and passive head velocities and frequencies, in normally sighted and low vision adults. Predictable and unpredictable head movements will be studied with aid of mathematical modelling and simulation in order to ascertain the role of predictive, motor efference copy, and other ocular motor mechanisms in supplementing VVI. Findings will be correlated with separate measurements of visually guided tracking. The relationship between instantaneous vertical retinal image slip velocity, and dynamic visual acuity, will be studied in relation to viewing strategies employed with telescopic spectacles. By studying horizontal and vertical eye and head movements during unrestrained visual search, experiments will identify characteristics of optimal visual search strategies with telescopic spectacles. Modification of search strategy to minimize retinal image instability and search time will also be evaluated. These data will enhance basic understanding of human vertical eye movements, and provide clinical insight into an important problem in clinical low vision.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY008656-03
Application #
3265976
Study Section
Visual Sciences B Study Section (VISB)
Project Start
1990-08-01
Project End
1993-07-31
Budget Start
1992-08-01
Budget End
1993-07-31
Support Year
3
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of California Los Angeles
Department
Type
Schools of Medicine
DUNS #
119132785
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Crane, B T; Demer, J L (1999) Horizontal vestibulo-ocular reflex and head stability in response to torso perturbations during visual search. Exp Brain Res 125:335-43
Demer, J L; Crane, B T (1998) Vision and vestibular adaptation. Otolaryngol Head Neck Surg 119:78-88
Crane, B T; Viirre, E S; Demer, J L (1997) The human horizontal vestibulo-ocular reflex during combined linear and angular acceleration. Exp Brain Res 114:304-20
Rabiah, P K; Bateman, J B; Demer, J L et al. (1997) Ophthalmologic findings in patients with ataxia. Am J Ophthalmol 123:108-17
Crane, B T; Demer, J L (1997) Human gaze stabilization during natural activities: translation, rotation, magnification, and target distance effects. J Neurophysiol 78:2129-44
Foster, C A; Demer, J L; Morrow, M J et al. (1997) Deficits of gaze stability in multiple axes following unilateral vestibular lesions. Exp Brain Res 116:501-9
Demer, J L; Viirre, E S (1996) Visual-vestibular interaction during standing, walking, and running. J Vestib Res 6:295-313
Viirre, E S; Demer, J L (1996) The human vertical vestibulo-ocular reflex during combined linear and angular acceleration with near-target fixation. Exp Brain Res 112:313-24
Baloh, R W; Yue, Q; Demer, J L (1995) The linear vestibulo-ocular reflex in normal subjects and patients with vestibular and cerebellar lesions. J Vestib Res 5:349-61
Demer, J L (1995) Evaluation of vestibular and visual oculomotor function. Otolaryngol Head Neck Surg 112:16-35

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