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.
|Title of host publication||Investigative Ophthalmology and Visual Science|
|Publication status||Published - Jun 2021|
|Event||Association for Research in Vision and Ophthalmology (ARVO) Annual Meeting - |
Duration: 1 May 2021 → 7 May 2021
|Conference||Association for Research in Vision and Ophthalmology (ARVO) Annual Meeting|
|Period||1/05/21 → 7/05/21|