June 2021
Volume 62, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2021
How does lighting and visual task affect gait performance in patients with severe peripheral visual field loss?
Author Affiliations & Notes
  • Allen M Y Cheong
    The Hong Kong Polytechnic University, Kowloon, Hong Kong
  • Hiu-Yan Lam
    The Hong Kong Polytechnic University, Kowloon, Hong Kong
  • Venus Suen
    The Hong Kong Polytechnic University, Kowloon, Hong Kong
  • Celia Tsang
    The Hong Kong Polytechnic University, Kowloon, Hong Kong
  • Man Cheung
    The Hong Kong Polytechnic University, Kowloon, Hong Kong
  • George Woo
    The Hong Kong Polytechnic University, Kowloon, Hong Kong
  • Joseph Cho
    Hong Kong Scoiety for the Blind, Hong Kong
  • Joseph Kwan
    UDA Consultants Ltd, Hong Kong
  • Larry Allen Abel
    Deakin University, Burwood, Victoria, Australia
  • William Tsang
    The Open University of Hong Kong, Hong Kong, Hong Kong
  • Footnotes
    Commercial Relationships   Allen Cheong, None; Hiu-Yan Lam, None; Venus Suen, None; Celia Tsang, None; Man Cheung, None; George Woo, None; Joseph Cho, None; Joseph Kwan, None; Larry Abel, None; William Tsang, None
  • Footnotes
    Support  Health Medical Research Grant #14150211, HKSAR
Investigative Ophthalmology & Visual Science June 2021, Vol.62, 3564. doi:
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      Allen M Y Cheong, Hiu-Yan Lam, Venus Suen, Celia Tsang, Man Cheung, George Woo, Joseph Cho, Joseph Kwan, Larry Allen Abel, William Tsang; How does lighting and visual task affect gait performance in patients with severe peripheral visual field loss?. Invest. Ophthalmol. Vis. Sci. 2021;62(8):3564.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : In our daily life, we might walk under different challenging conditions, such as engaging in visual search or adapting to different lighting levels. These challenges might impose more fall risk to visually-impaired patients. This study was aimed to investigate the possible impact of visual search and lighting on walking in patients with peripheral field loss (PFL).

Methods : Five participants with binocular visual field less than 10° and 5 age-matched healthy controls were recruited. All participants were required to walk a 4-metres obstacle-free pathway at self-pace and step on a force platform at the end of pathway under 3 different lighting levels (100, 520 and 2100 lux). Six monitors were placed at two-metres away from the force platform in an arc-shape to cover ~120° field of view. While walking, they either fixated at a stationary cross or performed a visual search task by identifying a target among 5 distractors shown on the monitors. Inertial measurement unit synchronized with a high-speed camera were used to measure the changes of gait pattern in temporal parameters, including swing phase (%), double support (%), cadence (step/min) and average walking speed (cm/sec).

Results : Visual search task significantly affected the gait pattern, with reduced swing phase (Fix: 36.0%±1.8 vs Search: 35.3%±2.0; p<0.01) and increased double support (Fix: 26.7%±3.4 vs Search: 28.2%±3.8; p=0.01). It also significantly decreased cadence (Fix: 106±11 vs Search: 103±13 step/min) and average walking speed (Fix: 88.8±12.1 vs Search: 82.2±13.8 cm/s; p<0.01). Furthermore, significant interaction effects between group and visual task were found in cadence and average walking speed (p<0.05), showing that search task affected the temporal domain of gait in patients with PFL. However, no significant effect of lighting or interaction effect between lighting and group (p>0.05).

Conclusions : In this preliminary study, search task caused significant changes in the walking pattern in people with PFL. In contrast, environmental changes due to different lighting conditions did not show significant impact on the gait. Further study is needed to examine the causal relationship between the change of the walking pattern due to search task and the incidence of falls in this population and whether the mobility performance will be further compromised when patients need to negotiate obstacles during walking.

This is a 2021 ARVO Annual Meeting abstract.

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