Route previewing results in altered gaze behaviour, increased self-confidence and improved stepping safety in both young and older adults during adaptive locomotion

Age effects on predictive eye movements for action

When interacting with the environment, humans typically shift their gaze to where information is to be found that is useful for the upcoming action. With increasing age, people become slower both in processing sensory information and in performing their movements. One way to compensate for this slowing down could be to rely more on predictive strategies. To examine whether we could find evidence for this, we asked younger (19-29 years) and older (55-72 years) healthy adults to perform a reaching task wherein they hit a visual target that appeared at one of two possible locations. In separate blocks of trials, the target could appear always at the same location (predictable), mainly at one of the locations (biased), or at either location randomly (unpredictable). As one might expect, saccades toward predictable targets had shorter latencies than those toward less predictable targets, irrespective of age. Older adults took longer to initiate saccades toward the target location than younger adults, even when the likely target location could be deduced. Thus we found no evidence of them relying more on predictive gaze. Moreover, both younger and older participants performed more saccades when the target location was less predictable, but again no age-related differences were found. Thus we found no tendency for older adults to rely more on prediction.

Patients with knee osteoarthritis have altered gait and gaze patterns compared to age-matched controls: A pilot study

PURPOSE

Although knee Osteoarthritis (KOA) sufferers are at an increased risk of falls, possibly due to impaired gait function, the associated gaze behaviour in patients with KOA are largely unknown. Thus, we compared gait and gaze behaviours characteristics between KOA patients and asymptomatic age-matched controls.

RESULTS

For Timed Up and Go (TUG) and stair climb tasks, the KOA group demonstrated longer periods of gaze fixations with less frequency of fixations compared to the control group. Conversely, for the Timed up and Go Agility (TUGA) test shorter fixation and frequency patterns were observed. The KOA group presented a shorter final stride length prior to the initiation of the first step in the Stair climb assessment. In addition, for the 30m walk and dual task assessments, the average step length was significantly shorter in the KOA group compared to controls.

CONCLUSION

Overall, we found altered gait and gaze behaviours are evident in KOA patients which could relate to their increased falls risk.

A registered report of a crossover study on the effects of face masks on walking adaptability in people with Parkinson's disease and multiple sclerosis

BACKGROUND

Face masks protrude into the lower visual field causing reduced perception of visual stimuli, potentially making obstacle avoidance during walking more difficult and increasing fall risk. Recommendations on walking and mask wearing for older adults have been debated, with no clear consensus on the various factors interacting and influencing walking safety while wearing a face mask. It is particularly important to address this issue in populations at an increased risk of falls. Therefore, this study aims to investigate the effects of mask-wearing on objectively measured walking adaptability in people with Parkinson's disease and Multiple Sclerosis.

METHODS

50 patients with either Parkinson's disease or Multiple Sclerosis attending inpatient neurorehabilitation will be recruited to participate in this crossover study. Performance during a standardized gait adaptability (C-Gait) test on a VR-based treadmill (C-Mill+VR), as well as during clinical mobility tests (10-meter walk test, Timed Up & Go test, and stair ambulation) will be measured with and without an FFP2- mask (order randomized). In addition, participants will be asked about their perceived performance and perceived safety during the tests with and without a mask. Performance on the seven C-Gait subtests is based on centre of pressure-derived measures of foot placement in relation to the different tasks. These are averaged and added to a cognitive C-Gait task to give the overall composite score (primary outcome). Secondary outcomes will include the different subscores and clinical mobility tests.

POTENTIAL SIGNIFICANCE

This study will make an important contribution to an ongoing debate regarding recommendations persons with and without a neurological disease should be given regarding wearing a face mask while walking. Furthermore, the study will complement the existing scientific discourse with clinical data from people with a neurological disease for whom falls, mobility deficits and mask wearing may be more frequent, which can help inform evidence-based recommendations.

TRIAL REGISTRATION

German clinical trial register: DRKS00030207.

The effect of COVID-19 pandemic and wearing face masks on ophthalmology practice: What is known so far? A narrative review

Face masks, along with other preventive measures, can help slow the spread of COVID-19. Despite the positive effect of the mask in combating the virus, it has some negative effects on the human body that must be followed up on and reduced. In this study, we discuss the impact of wearing face masks on the eye and the common issues associated with using them. The literature search was conducted using electronic databases such as PubMed and Google Scholar. Only articles published in English were included. A total of 39 relevant articles were deemed eligible. After the duplicate articles were removed, the titles and abstracts of 20 papers underwent full-text screening. The review comprised both prospective and retrospective investigations, case reports, and a series of reporting ocular symptoms following the use of face masks. The COVID-19 pandemic affected ophthalmology practices in managing patients. New factors must be considered, especially when dealing with anti-VEGF injections, such as the risk of endophthalmitis, tests and symptoms of patients with glaucoma, and the emerging symptoms associated with the COVID-19 vaccination. The use of face masks and breathing aids seemed to influence the tear film.

Influence of step-surface visual properties on confidence, anxiety, dynamic stability, and gaze behaviour in young and older adults

BACKGROUND

Step-surface visual properties are often associated with stair falls. However, evidence for decorating stairs typically concerns the application of step-edge highlighters rather than the entire step-surface. Here we examine the influence of step-surface visual properties on stair descent safety, with a view to generating preliminary evidence for safe stair décor.

METHODS

Fourteen young (YA: 23.1 ± 3.7 years), 13 higher (HAOA: 67 ± 3.5) and 14 lower (LAOA: 73.4 ± 5.7) ability older adults descended a seven-step staircase. Older adults were stratified based on physiological/cognitive function. Step-surface décor patterns assessed were: Black and white (Busy); fine grey (Plain); and striped multicolour (Striped); each implemented with/without black edge-highlighters (5.5 cm width) totalling six conditions. Participants descended three times per condition. Confidence was assessed prior to, and anxiety following, the first descent in each condition. 3D kinematics (Vicon) quantified descent speed, margin of stability, and foot clearances with respect to step-edges. Eye tracking (Pupil-labs) recorded gaze. Data from three phases of descent (entry, middle, exit) were analysed. Linear mixed-effects models assessed within-subject effects of décor (×3) and edge highlighters (×2), between-subject effects of age (×3), and interactions between terms (α = p < .05).

RESULTS

Décor: Plain décor reduced anxiety in all ages and abilities (p = .032, effect size: g_av = 0.3), and increased foot clearances in YA and HAOA in the middle phase (p < .001, g_av = 0.53), thus improving safety. In contrast, LAOA exhibited no change in foot clearance with Plain décor. Patterned décor slowed descent (Busy: p < .001, g_av = 0.2), increased margins of stability (Busy: p < .001, g_av = 0.41; Striped: p < .001, gav = 0.25) and reduced steps looked ahead (Busy: p = .053, gav = 0.25; Striped: p = .039, gav = 0.28) in all ages and abilities. This reflects cautious descent, likely due to more challenging conditions for visually extracting information about the spatial characteristics of the steps useful to guide descent. Edge highlighters: Step-edge highlighters increased confidence (p < .001, g_av = 0.53) and reduced anxiety (p < .001, g_av = 0.45) in all ages and abilities and for all décor, whilst removing them slowed descent in HAOA (p = .01, g_av = 0.26) and LAOA (p = .003, g_av = 0.25). Step-edge highlighters also increased foot clearance in YA and HAOA (p = .003, g_av = 0.14), whilst LAOA older adults showed no adaptation. No change in foot clearances with décor or step-edge highlighters in LAOA suggests an inability to adapt to step-surface visual properties.

CONCLUSION

Patterned step surfaces can lead to more cautious and demanding stair negotiation from the perspective of visually extracting spatial information about the steps. In contrast, plain décor with step edge highlighters improves safety. We therefore suggest plain décor with edge highlighters is preferable for use on stairs.

Children With Developmental Coordination Disorder Exhibit Greater Stepping Error Despite Similar Gaze Patterns and State Anxiety Levels to Their Typically Developing Peers

This study examined stepping accuracy, gaze behavior, and state-anxiety in children with (N = 21, age M = 10.81, SD = 1.89) and without (N = 18, age M = 11.39, SD = 2.06) developmental coordination disorder (DCD) during an adaptive locomotion task. Participants walked at a self-selected pace along a pathway, placing their foot into a raised rectangular floor-based target box followed by either no obstacles, one obstacle, or two obstacles. Stepping kinematics and accuracy were determined using three-dimensional motion capture, whilst gaze was determined using mobile eye-tracking equipment. The children with DCD displayed greater foot placement error and variability when placing their foot within the target box and were more likely to make contact with its edges than their typically developing (TD) peers. The DCD group also displayed greater variability in the length and width of their steps in the approach to the target box. No differences were observed between groups in any of the gaze variables measured, in mediolateral velocity of the center of mass during the swing phase into the target box, or in the levels of self-reported state-anxiety experienced prior to facing each task. We therefore provide the first quantifiable evidence that deficits to foot placement accuracy and precision may be partially responsible for the increased incidence of trips and falls in DCD, and that these deficits are likely to occur independently from gaze behavior and state-anxiety.

Optimal lighting levels for stair safety: Influence of lightbulb type and brightness on confidence, dynamic balance and stepping characteristics

INTRODUCTION

Poor lighting has been associated with stair falls in young and older adults. However, current guidelines for illuminating stairs seem arbitrary, differ widely between sources, and are often difficult to interpret.

AIMS

Here we examined the influence of real-world bulb illumination properties on stair descent safety in young and older adults, with a view to generating preliminary evidence for appropriate lightbulb use/stair illumination.

METHODS

Stair tread illumination (lx) was measured in a standard UK home (2.23 m ceiling) from a low (50 W; 630 lm) and a high (103 W, 1450 lm) power compact fluorescent lamp (CFL) bulb from the time they were turned on until they reached full brightness. This enabled modelling of their illumination characteristics during warm up. Illumination was also measured from a low (40 W, 470 lm) and a high (100 W, 1521 lm) power LED bulb at first turn-on. Computer-controlled custom lighting then replicated these profiles, in addition to a Bright control (350 lx), on an instrumented staircase descended (3 × trials per light condition) by 12 young (25.3 ± 4.4 years; 5 males), 12 higher ability older (HAOA: 69.6 ± 4.7 years; 5 males) and 13 lower ability older (LAOA: 72.4 ± 4.2; 3 males) healthy adults. Older adults were allocated to ability groups based on physiological and cognitive function. Stair-specific confidence was assessed prior to the first descent in each new lighting condition, and whole-body 3D kinematics (Vicon) quantified margins of stability and foot clearances with respect to the step edges. Mixed ANOVAs examined these measures for within-subject effects of lighting (×5), between-subject effects of age (×3) and interactions between lighting and age.

RESULTS

Use of CFL bulbs led to lower self-reported confidence in older adults (20.37%, p = .01), and increased margins of stability (12.47%, p = .015) and foot clearances with respect to the step edges (10.36%, p = .003). Importantly, using CFL bulbs increased foot clearance variability with respect to the bottom step (32.74%, p = .046), which is where a high proportion of falls occur.

CONCLUSION

Stair-tread illumination from CFL bulbs at first turn on leads to less safe stair negotiation. We suggest high powered LED bulbs may offer a safer alternative.

Mobility-Related Gaze Training in Individuals With Glaucoma: A Proof-of-Concept Study

Purpose

Older adults with glaucoma show inappropriate gaze strategies during routine mobility tasks. Furthermore, glaucoma is a risk factor for falling and colliding with objects when walking. However, effective interventions to rectify these strategies and prevent these adverse events are scarce. We designed a gaze training program with the goal of providing proof-of-concept that we could modify mobility-related gaze behavior in this population.

Methods

A total of 13 individuals with moderate glaucoma participated in this study. We taught participants general and task-specific gaze strategies over two 1-hour sessions. To determine the efficacy of this gaze training program, participants performed walking tasks that required accurate foot placement onto targets and circumventing obstacles before and after training. We used a mobile eye tracker to quantify gaze and a motion-capture system to quantify body movement.

Results

After training, we found changes in the timing between gaze shifts away from targets relative to stepping on them (P < 0.05). In the obstacle negotiation task, we found a greater range of gaze shifts early in walking trials and changes in the timing between gaze shifts away from obstacles after training (P < 0.05), each suggesting better route planning. A posttraining reduction in foot-placement error and obstacle collisions accompanied these changes (P < 0.05).

Conclusions

Our results demonstrated that it is possible to modify mobility-related gaze behavior and mobility performance in older adults with glaucoma.

Translational Relevance

This study provides proof-of-concept for a gaze training program for glaucoma. A larger, randomized controlled trial is warranted.

Conscious motor control impairs attentional processing efficiency during precision stepping

BACKGROUND

Current evidence suggests that fall-related anxiety can impair attentional processing efficiency during gait in both young and older adults, reducing the cognitive resources available for carrying out concurrent tasks (i.e., holding a conversation whilst walking or planning the safest route for navigation).

RESEARCH QUESTION

It has been suggested that fall-related anxiety may impair processing efficiency by directing attention 'internally', towards consciously controlling and monitoring movement. The present study aimed to evaluate this interpretation.

METHODS

Fifteen healthy young adults performed a precision stepping task during both single- and dual-task (completing the stepping task while simultaneously performing an arithmetic task), under three conditions: (1) Baseline; (2) Threat (walking on a platform raised 1.1 m above ground), and; (3) Internal focus of attention (cues/instructions to direct attention towards movement processing).

RESULTS

We observed significantly greater cognitive dual-task costs (i.e., poorer performance on the arithmetic task) during Threat compared to Baseline, with the greatest costs observed in individuals reporting the highest levels of Threat-induced conscious motor processing. Significantly greater cognitive dual-task costs were also observed during the Internal condition, confirming the assumption that consciously attending to movement reduces cognitive resources available for carrying out a secondary task during gait. These results were accompanied with significantly poorer stepping accuracy in dual-task trials during both Threat and Internal.

SIGNIFICANCE

These findings support previous attempts to rationalise attentional processing inefficiencies observed in anxious walkers as being a consequence of an anxiety-induced internal focus of attention.