Gait Alterations Negotiating A Raised Surface Induced by Monocular Blur
Vale, Anna
Vale, Anna
Publication Date
01/12/2008
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Abstract
Falls in the elderly are a major cause of serious injury and mortality. Impaired and absent stereopsis may be a
significant risk factor for falls or hip fracture, although data from epidemiological studies are not consistent. Previous
laboratory based studies, however, do suggest that stereoacuity is an important factor in adaptive gait. The present study
investigates how acute impairment of stereopsis, through monocular blur of differing levels, ranging from 0.50 diopter (D)
to a monovision correction affected gait when negotiating a raised surface in elderly subjects.
Eleven elderly subjects (73.3 3.6 years) walked up to and negotiated a raised surface under nine visual
conditions, binocular vision, one eye occluded and 0.50 D, 1.00 D and monovision correction (mean 2.50 D 0.20 D)
with blur and occlusion either over the dominant or non-dominant eye. Analysis focused on foot positioning and toe
clearance parameters.
There was no effect of ocular dominance on any parameters. Monocular blur impaired stereopsis (p 0.01), with
more minor effects on high and low contrast acuity. Vertical and horizontal lead limb toe clearance both increased under
all levels of monocular blur including the lowest level of 0.50 DBlur (p 0.03) and monovision correction led to toe
clearance levels similar to that found with occlusion of one eye.
Findings demonstrated that even small amounts of monocular blur can lead to a change in gait when
negotiating a raised surface, suggesting acute monocular blur affected the ability to accurately judge the height of a step
in the travel path. Further work is required to investigate if similar adaptations are used by patients with chronic
monocular blur.
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Vale A, Buckley JG and Elliott DB (2008) Gait Alterations Negotiating A Raised Surface Induced by Monocular Blur. 85(12): 1128-1134.
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