How does lighting and visual task affect gait performance in patients with severe peripheral visual field loss?

Allen Ming Yan Cheong, Hiu Yan Lam, Bik Chi Suen, Lai Lin Tsang, Yat Man Cheung, George Woo, Joseph Cho, Joseph Kwan, Larry Abel, William Tsang

Research output: Chapter in book / Conference proceedingConference article published in proceeding or bookAcademic researchpeer-review

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.
Original languageEnglish
Title of host publicationInvestigative Ophthalmology and Visual Science
Pages3564
Volume62
ISBN (Electronic)1552-5783
Publication statusPublished - Jun 2021
EventAssociation for Research in Vision and Ophthalmology (ARVO) Annual Meeting -
Duration: 1 May 20217 May 2021

Conference

ConferenceAssociation for Research in Vision and Ophthalmology (ARVO) Annual Meeting
Period1/05/217/05/21

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