Stepping accuracy and visuomotor control among older adults : effect of target contrast and refractive blur

Black, Alex A., Kimlin, Janessa A., & Wood, Joanne M. (2014) Stepping accuracy and visuomotor control among older adults : effect of target contrast and refractive blur. Ophthalmic and Physiological Optics, 34(4), pp. 470-478.

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Abstract

Purpose: Older adults have increased visual impairment, including refractive blur from presbyopic multifocal spectacle corrections, and are less able to extract visual information from the environment to plan and execute appropriate stepping actions; these factors may collectively contribute to their higher risk of falls. The aim of this study was to examine the effect of refractive blur and target visibility on the stepping accuracy and visuomotor stepping strategies of older adults during a precision stepping task.

Methods: Ten healthy, visually normal older adults (mean age 69.4 ± 5.2 years) walked up and down a 20 m indoor corridor stepping onto selected high and low-contrast targets while viewing under three visual conditions: best-corrected vision, +2.00 DS and +3.00 DS blur; the order of blur conditions was randomised between participants. Stepping accuracy and gaze behaviours were recorded using an eyetracker and a secondary hand-held camera.

Results: Older adults made significantly more stepping errors with increasing levels of blur, particularly exhibiting under-stepping (stepping more posteriorly) onto the targets (p<0.05), while visuomotor stepping strategies did not significantly alter. Stepping errors were also significantly greater for the low compared to the high contrast targets and differences in visuomotor stepping strategies were found, including increased duration of gaze and increased interval between gaze onset and initiation of the leg swing when stepping onto the low contrast targets.

Conclusions: These findings highlight that stepping accuracy is reduced for low visibility targets, and for high levels of refractive blur at levels typically present in multifocal spectacle corrections, despite significant changes in some of the visuomotor stepping strategies. These findings highlight the importance of maximising the contrast of objects in the environment, and may help explain why older adults wearing multifocal spectacle corrections exhibit an increased risk of falling.

Impact and interest:

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4 citations in Web of Science®

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ID Code: 78066
Item Type: Journal Article
Refereed: Yes
Keywords: falls, gaze behaviour, human locomotion, older adults, stepping accuracy, visuomotor control
DOI: 10.1111/opo.12141
ISSN: 1475-1313
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300) > Vision Science (111303)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Current > Schools > School of Optometry & Vision Science
Copyright Owner: Copyright 2014 The Authors
Copyright Statement: This is the accepted version of the following article: Black AA, Kimlin JA & Wood JM. Stepping accuracy and visuomotor control among older adults: effect of target contrast and refractive blur. Ophthalmic Physiol Opt 2014; 34: 470–478. doi: 10.1111/opo.12141, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1111/opo.12141/abstract
Deposited On: 27 Oct 2014 03:35
Last Modified: 04 Aug 2015 22:22

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