Difficult at dusk? Illuminating the debate on cricket ball visibility.

OBJECTIVES: Investigate the visibility of new and old red, white and pink cricket balls under lighting and background conditions experienced during a day-night cricket match. DESIGN: We modelled the luminance contrast signals available for a typical observer for a ball against backgrounds in a professional cricket ground, at different times of day. METHODS: Spectral reflectance (light reflected as a function of wavelength) was derived from laboratory measurements of new and old red, white and pink balls. We also gathered spectral measurements from backgrounds (pitch, grass, sightscreens, crowd, sky) and spectral illuminance during a day-night match (natural afternoon light, through dusk to night under floodlights) from Lord's Cricket Ground (London, UK). The luminance contrast of the ball relative to the background was calculated for each combination of ball, time of day, and background surface. RESULTS: Old red and old pink balls may offer little or no contrast against the grass, pitch and crowd. New pink balls can also be of low contrast against the crowd at dusk, as can pink and white balls (of any age) against the sky at dusk. CONCLUSIONS: Reports of difficulties with visibility of the pink ball are supported by our data. However, our modelling also shows that difficulties with visibility may also be expected under certain circumstances for red and white balls. The variable conditions in a cricket ground and the changing colour of an ageing ball make maintaining good visibility of the ball a challenge when playing day-night matches.

Evaluating consistency of physical activity and exercise prescription in the UK for people with diabetes - a Delphi study.

Introduction: Increased physical activity is recommended as a cost-effective measure to tackle long-term management of people with diabetes, but research on interventions lacks consistency in terms of effective duration and modality. Methods: The aim of this study was to evaluate expert consensus on exercise and physical activity prescription via a three-round Delphi study conducted with 45 UK-based health and fitness professionals experienced in prescribing exercise or physical activity to people with diabetes. Results: The majority of items put forward to the panel reached consensus with 70% or above voting these items as important, but the details of the type, duration and/or modality of exercise or physical activity prescription within these items often contradicted each other, suggesting that patients are receiving inconsistent advice. The range of different exercise prescription found in this study suggests that patients are being given inconsistent and potentially confusing advice, which may affect their participation in exercise and long-term lifestyle change. Conclusion: More consistent promotion of advice from healthcare and fitness professionals may help with increasing physical activity in this participant group and achieving long term behavior change, reducing patient symptoms as well as reducing the cost to the National Health Service (NHS).

A Scoping Review of the Validity and Reliability of Smartphone Accelerometers When Collecting Kinematic Gait Data.

The aim of this scoping review is to evaluate and summarize the existing literature that considers the validity and/or reliability of smartphone accelerometer applications when compared to 'gold standard' kinematic data collection (for example, motion capture). An electronic keyword search was performed on three databases to identify appropriate research. This research was then examined for details of measures and methodology and general study characteristics to identify related themes. No restrictions were placed on the date of publication, type of smartphone, or participant demographics. In total, 21 papers were reviewed to synthesize themes and approaches used and to identify future research priorities. The validity and reliability of smartphone-based accelerometry data have been assessed against motion capture, pressure walkways, and IMUs as 'gold standard' technology and they have been found to be accurate and reliable. This suggests that smartphone accelerometers can provide a cheap and accurate alternative to gather kinematic data, which can be used in ecologically valid environments to potentially increase diversity in research participation. However, some studies suggest that body placement may affect the accuracy of the result, and that position data correlate better than actual acceleration values, which should be considered in any future implementation of smartphone technology. Future research comparing different capture frequencies and resulting noise, and different walking surfaces, would be useful.

The effects of age and central field loss on maintaining balance control when stepping up to a new level under time-pressure.

Objective: To investigate the effects of age and central field loss on the landing mechanics and balance control when stepping up to a new level under time-pressure. Methods: Eight older individuals with age-related macular degeneration (AMD), eight visually normal older and eight visually normal younger individuals negotiated a floor-based obstacle followed by a 'step-up to a new level' task. The task was performed under (1) no-pressure; (2) time-pressure: an intermittent tone was played that increased in frequency and participants had to complete the task before the tone ceased. Landing mechanics and balance control for the step-up task was assessed with a floor-mounted force plate on the step. Results: Increased ground reaction forces and loading rates were observed under time-pressure for young and older visual normals but not for AMD participants. Across conditions, loading rates and ground reaction forces were higher in young normals compared to older normals and AMD participants. Young visual normals also demonstrated 35-39% shorter double support times prior to and during the step-up compared to older normals and AMD participants. All groups shortened their double support times (31-40%) and single support times (7-9%) in the time-pressure compared to no-pressure condition. Regarding balance control, the centre-of-pressure displacement and velocity in the anterior-poster direction were increased under time-pressure for young and older visual normals but not for AMD participants. The centre-of-pressure displacement and velocity in the medial-lateral direction were decreased for the AMD participants under time-pressure but not for young and older visual normals. Conclusions: Despite walking faster, AMD participants did not adapt their landing mechanics under time-pressure (i.e., they remained more cautious), whilst older and young adults with normal vision demonstrated more forceful landing mechanics with the young being most forceful. A more controlled landing might be a safety strategy to maintain balance control during the step-up, especially in time-pressure conditions when balance control in the anterior-posterior direction is more challenged.

Adaptations in Visual Search Behaviour as a Function of Expertise in Rugby Union Players Completing Attacking Scenarios.

The current study investigated the adaptations which occur in visual search behaviour as a function of expertise in rugby union players when completing attacking scenarios. Ten experienced players (EP) and ten novice players (NP) completed 2 vs. 1 attacking game scenarios. Starting with the ball in hand and wearing a mobile eye tracker throughout, participants were required to score a try against a defender. The scenarios allowed for a pass to their supporting player (Spin Pass or Switch) or trying to run past the defender (Take-Player-On or Dummy Switch). No between group differences were found in fixating on the supporting attacking player (p > 0.05). However, EP increased the length (p = 0.008) and frequency (p = 0.004) looking at the area immediately ahead of the supporting player, particularly when executing a spin pass. NP fixated longer (p = 0.005) and more frequently (p = 0.032) at the defender, whilst EP fixated more frequently in the space the supporting player would run into in Switch and Dummy Switch scenarios (p = 0.025). More successful passes were completed and tries scored by EP compared to NP (p = 0.001). Differences in visual search behaviour between experienced and NP suggest that the experts extract information from areas directly related to guiding the motor action; the space immediately ahead of the support player to pass the ball in. Contrastingly, novices use a more allocentric perspective where the actions from the defender are used to guide their motor actions.

Visual Strategies Underpinning the Spatiotemporal Demands During Visuomotor Tasks in Predicting Ball Direction.

We investigated gaze behavior of expert goalkeepers during the prediction of penalty kicks in different spatiotemporal constraints: penalties taken from 11 and 6 m. From 11 m, goalkeepers were more successful in predicting ball direction, with longer movement time initiation and a visual strategy with more fixations and greater saccade rates than penalties from 6 m, where they exhibited fewer fixations with higher microsaccade rates. As long as the opponent's distance is large and time pressure low, gaze can be frequently shifted between the kicker's body and the ball, due to the low cost of saccades. Conversely, when the objects are close, there is increased reliance on foveal and parafoveal information. In conclusion, when the spatiotemporal constraint is less severe, goalkeepers adopt a visual strategy with more fixations and small saccades. When the spatiotemporal constraint is more severe, they rely on peripheral vision to monitor kickers' movements through the use of microsaccades.

Development and Evaluation of a Virtual Environment to Assess Cycling Hazard Perception Skills.

Safe cycling requires situational awareness to identify and perceive hazards in the environment to react to and avoid dangerous situations. Concurrently, tending to external distractions leads to a failure to identify hazards or to respond appropriately in a time-constrained manner. Hazard perception training can enhance the ability to identify and react to potential dangers while cycling. Although cycling on the road in the presence of driving cars provides an excellent opportunity to develop and evaluate hazard perception skills, there are obvious ethical and practical risks, requiring extensive resources to facilitate safety, particularly when involving children. Therefore, we developed a Cycling and Hazard Perception virtual reality (VR) simulator (CHP-VR simulator) to create a safe environment where hazard perception can be evaluated and/or trained in a real-time setting. The player interacts in the virtual environment through a stationary bike, where sensors on the bike transfer the player's position and actions (speed and road positioning) into the virtual environment. A VR headset provides a real-world experience for the player, and a procedural content generation (PCG) algorithm enables the generation of playable artifacts. Pilot data using experienced adult cyclists was collected to develop and evaluate the VR simulator through measuring gaze behavior, both in VR and in situ. A comparable scene (cycling past a parked bus) in VR and in situ was used. In this scenario, cyclists fixated 20% longer at the bus in VR compared to in situ. However, limited agreement identified that the mean differences fell within 95% confidence intervals. The observed differences were likely attributed to a lower number of concurrently appearing elements (i.e., cars) in the VR environment compared with in situ. Future work will explore feasibility testing in young children by increasing assets and incorporating a game scoring system to direct attention to overt and covert hazards.

How Is Jump Performance Affected in Male Athletes when Completed with a Visual Impairment?

SIGNIFICANCE: High-, long-, and triple-jump athletic events may need to consider whether it is appropriate to group vision-impaired athletes in the same classification with loss of different visual functions, and a greater emphasis may need to be placed on the visual field (VF) within the current classification system used. PURPOSE: Athletes with vision impairment are grouped, based on their visual function, into one of three different classes (B1, B2, and B3, with B1 being the most severe). Athletes in class B2 have loss in visual acuity (VA; range, 1.50 to 2.60 logMAR) or VF (constricted to a diameter of <10°). The current study investigated how loss of different visual function (VA or VF) within the same class impacts jumping performance, a fundamental component in long-, triple-, and high-jump athletic events. METHODS: Ten subelite male athletes (age, 21.6 ± 0.96 years; height, 178.8 ± 2.97 cm; mass, 82.2 ± 10.58 kg) with normal vision who participate in athletics were recruited. Participants completed drop jumps in four vision conditions: habitual vision condition (Full), VA no better than 1.60 logMAR (B2-VA), VF restricted to <10° (B2-VF), and VA no better than 1.30 logMAR (B3-VA). RESULTS: Meaningful differences were observed between Full and B2-VF conditions. After rebound, vertical velocity at take-off was highest in Full condition (2.84 ± 0.35 m · s-1; 95% confidence interval [CI], 2.68 to 2.99 m · s-1) and was lowest in B2-VF condition (20% reduction; 2.32 ± 0.29 m · s-1; 95% CI, 2.16 to 2.48 m · s-1). Peak vertical jump height was highest in Full (0.42 ± 0.10 m; 95% CI, 0.38 to 0.46 m) and reduced by 40% in B2-VF (0.28 ± 0.07 m; 95% CI, 0.24 to 0.32 m). Minimal differences were found between Full and B2-VA, or B3-VA conditions. CONCLUSIONS: Jump performance is compromised in athletes with simulated vision impairment. However, decrements in performance seem specific to those with severely constricted VF. Those with reduced VA (in B2-VA and B3-VA classes) seem to produce performance comparable to those with normal vision.

Do visual fields need to be considered in classification criteria within visually impaired shooting?

Classification within the sport of vision impairment (VI) shooting is based upon the athlete's visual function. This study aimed to determine whether more than one class of competition is needed within VI shooting on the basis of visual field loss. Qualification scores of 23 elite athletes were obtained at World Championship events in prone and standing shooting disciplines. Visual field data were obtained from classification data and from assessment at events. A standardized scoring protocol determined whether athletes had function (≥10 dB) or no function (<10 dB) at locations between 0-60 degrees eccentricity along 10 meridia. Visual field function was not associated with shooting performance in prone or standing disciplines (p > 0.05). Having measurable visual field function beyond 30 degrees made no difference to athletes' ability to shoot competitively in prone (p = 0.65) or standing disciplines (p = 0.47), although a potential impact on qualification was observed in the standing discipline. There was no evidence that loss of visual field function at any specific location adversely affected ability to shoot competitively. There is currently no evidence to consider visual fields in classification within prone or standing VI shooting, although further research is needed as the sport grows.

Is the pink ball still under review? Cricket umpires' perceptions of the pink ball for day/night matches.

OBJECTIVES: The visibility of the pink ball used in day/night Test cricket has been under scrutiny, with recent research suggesting cricketers find the pink ball less visible at dusk under floodlights. With increasing interest in this match format, this study sought to investigate elite umpires' opinions pertaining to the visibility of the pink cricket ball during day/night matches. DESIGN: Purposeful sampling of a cross-section of elite umpires with experience adjudicating matches played using a pink cricket ball. METHODS: Twenty-seven international/first-class umpires completed a questionnaire consisting of Likert scale and free text responses covering perceptions of the pink cricket ball, with a particular emphasis on visibility. RESULTS: The pink ball when viewed at night under floodlights was rated as being significantly more visible than the red ball during natural lighting (ps<0.050). Umpires who actively participated in training reported a significantly higher rating of the visibility of the pink ball (mean -3.14) at night under floodlights compared to those who didn't (mean p=0.010). No significant difference was reported in visibility in natural light or dusk under floodlights. Free text responses (n=10) revealed the following themes: use of eyewear (coverage 0.30), and adjustment to positioning (coverage 0.20) to improve visibility of the pink ball. CONCLUSIONS: Umpires report the visibility of the pink ball is equal to the red in natural light and at dusk but is significantly better at night. Preference for the pink ball is likely due to the predominantly perceptual nature of visual tasks performed by umpires.

Cricketers are not tickled pink by the new coloured ball.

OBJECTIVES: Cricket administrators have started scheduling long-form matches which finish at night and are played with a pink as opposed to a red ball. However, there are reports that the pink ball may introduce new dangers and alter performance. The aim of this study was to investigate professional cricketers' opinions about the visibility of the pink ball whilst playing in different lighting conditions (afternoon, dusk and night). DESIGN: Purposeful sampling of a cross-section of elite cricketers with pink ball experiences playing in the United Kingdom. METHODS: Eighty-eight international or first-class professional cricketers completed a questionnaire consisting of Likert scale and free text responses to questions covering perceptions of the pink ball, with a particular emphasis on visibility. RESULTS: The pink ball was reported as less visible than the red ball when batting (p<0.001) and fielding (p<0.001). Within the three lighting conditions the pink ball was significantly less visible at dusk under floodlights compared to afternoon and night both when batting and fielding (ps<0.001). Free text comments confirmed that visibility of the pink cricket ball was most challenging at dusk (coverage 0.37), and that players sometimes experienced a blurring sensation with the pink ball leaving a visual 'trail' when viewed under floodlights (coverage 0.24). CONCLUSIONS: Results advocate that governing bodies should consider the inclusion of a break in play during dusk to enhance player safety and performance. Empirical research is needed to quantify the risks to player safety in different lighting conditions.

The effects of temporal pressure on obstacle negotiation and gaze behaviour in young adults with simulated vision loss.

Individuals with vision loss adapt their locomotion and gaze behaviour to safely negotiate objects in temporally unconstrained situations. However, everyday activities are often performed under time-pressure. We investigated the effects of blur on anxiety, movement kinematics and gaze behaviour during the negotiation of a floor-based obstacle under three amounts of pressure: 1) no-pressure; 2) tonal-pressure: an intermittent tone was played at a constant frequency; 3) tonal + time pressure: the intermittent tone increased in frequency and participants had to walk 20% faster to reach the end of the lab. Irrespective of the amount of pressure, the blurred vs. normal vision group reported 32% more anxiety, lifted the lead foot 43% higher and 10% slower over the obstacle, and looked 6% longer and 6% more frequently ahead of the obstacle. In the tonal + time pressure vs. no-pressure condition, both groups were more anxious, showed adaptations in movement kinematics related to walking faster, and adopted a 'checking strategy' by shortening their fixation durations at the obstacle. These results show that irrespective of temporal pressure, the blurred vision group remained more cautious as to how the lead foot negotiated the obstacle, in order to reduce the chance of tripping during crossing.

Keep Your Eye on the Ball; the Impact of an Anticipatory Fixation During Successful and Unsuccessful Soccer Penalty Kicks.

The success of a sporting task requiring an object to be kicked or hit toward a target (e.g., kicking a ball into a goal) is impacted by the length of the Quiet Eye (QE). Limitations in the ocular motor system mean that after impact, these fast moving objects are not tracked using smooth pursuit eye movements. Rather, anticipatory fixations are used to re-fixate ahead of the moving object.Using a soccer penalty kick, the current study investigated whether striking a stationary object to generate high ball velocity results in an anticipatory fixation prior to ball contact and if this occurs at detriment to the QE period and task success.Facing a goalkeeper, 12 participants produced a successful (scored) and unsuccessful (saved) penalty whilst wearing a mobile eye tracker.QE was longer in the successful compared to unsuccessful penalty (p = 0.036) and was due to QE offset ending later in the successful compared to unsuccessful penalty (p = 0.008). An anticipatory fixation occurred later (p = 0.025) and was shorter (p = 0.005) in successful compared to unsuccessful penalties. The football was kicked wider (more accurately) within the goal during the successful compared to unsuccessful penalty (p < 0.001). Results highlight the importance of the QE period in successfully executing a soccer penalty kick. Unsuccessful penalties were associated with shorter QE length and earlier QE offset, which was due to initiating an anticipatory fixation in prediction of tracking the fast moving football, resulting in kicking the ball more centrally in the goal, making it easier for the goalkeeper to save.

The anticipatory stress response to sport competition; a systematic review with meta-analysis of cortisol reactivity.

OBJECTIVE: Athletes anticipating sport competition regularly experience distinct emotional and physiological responses as a result of the expected psychosocial and physical stress. Specifically, cortisol, an indicator of hypothalamic-pituitary-adrenal axis activation, prepares the athlete for the psychological and physiological demands of competition. The objective of this meta-analysis is to analyse the magnitude of the anticipatory cortisol response in athletes preparing to participate in sport competition and to examine the influence of gender, level of competition and data collection time. DESIGN: Systematic review with meta-analysis. DATA SOURCES: Four electronic databases were searched to March 2017: PubMed, PsycINFO, SPORTDiscus and Scopus. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: (1) Athletes participating in real sport competition;(2) salivary cortisol concentration collected before competition in addition to baseline sample(s);(3) original research article published in English language. RESULTS: Data from 25 studies provided 27 effect sizes. A significant anticipatory cortisol response of g=0.85, p<0.001 was identified. Males had a stronger trend for greater cortisol reactivity (g=1.07) than females (g=0.56, p=0.07). Females and athletes competing at international level did not demonstrate a significant anticipatory stress response. There were no significant differences between level of competition, type of sport or time of competition. Meta-regression indicated that the anticipatory cortisol response is greater when assessed closer to the start of competition (Q=6.85, p=0.009). SUMMARY/CONCLUSION: The anticipatory cortisol response before sport competition reflects moderate cortisol reactivity that prepares athletes optimally for the demands of sport competition via the influence on cognitive processes and attentional control. However, both female athletes and international competitors did not demonstrate a significant anticipatory cortisol response, possibly due to differences in appraisal of the stress of sport competition.

Visual Search Behavior in Individuals With Retinitis Pigmentosa During Level Walking and Obstacle Crossing.

Purpose: Investigate the visual search strategy of individuals with retinitis pigmentosa (RP) when negotiating a floor-based obstacle compared with level walking, and compared with those with normal vision. Methods: Wearing a mobile eye tracker, individuals with RP and normal vision walked along a level walkway or walked along the walkway negotiating a floor-based obstacle. In the level walking condition, tape was placed on the floor to act as an object attracting visual attention. Analysis compared where individuals looked within the environment. Results: In the obstacle compared with level walking condition: (1) the RP group reduced the length of time and the number of times they looked Ahead, and increased the time and how often they looked at features on the ground (Object and Down, P < 0.05); and (2) the visual normal group reduced the time (by 19%) they looked Ahead (P = 0.076), and increased the time and how often they looked at the Object (P < 0.05). Compared with the normal vision group, in both level walking and obstacle conditions, the RP group reduced the time looking Ahead and looked for longer and more often Down (P < 0.05). Conclusions: The RP group demonstrated a more active visual search pattern, looking at more areas on the ground in both level walking and obstacle crossing compared with visual normals. This gaze strategy was invariant across conditions. This is most likely due to the constricted visual field and inability to rely on inferior peripheral vision to acquire information from the floor within the environment when walking.

The impact of mobile phone use on where we look and how we walk when negotiating floor based obstacles.

Pedestrians regularly engage with their mobile phone whilst walking. The current study investigated how mobile phone use affects where people look (visual search behaviour) and how they negotiate a floor based hazard placed along the walking path. Whilst wearing a mobile eye tracker and motion analysis sensors, participants walked up to and negotiated a surface height change whilst writing a text, reading a text, talking on the phone, or without a phone. Differences in gait and visual search behaviour were found when using a mobile phone compared to when not using a phone. Using a phone resulted in looking less frequently and for less time at the surface height change, which led to adaptations in gait by negotiating it in a manner consistent with adopting an increasingly cautious stepping strategy. When using a mobile phone, writing a text whilst walking resulted in the greatest adaptions in gait and visual search behaviour compared to reading a text and talking on a mobile phone. Findings indicate that mobile phone users were able to adapt their visual search behaviour and gait to incorporate mobile phone use in a safe manner when negotiating floor based obstacles.

Relative Difficulties of Daily Living Tasks with Retinitis Pigmentosa.

PURPOSE: To determine the relative difficulty of activity of daily living tasks for people with retinitis pigmentosa (RP). METHODS: Participants with RP (n = 166) rated the difficulty of tasks (n = 43) underpinning the Dutch Activity Inventory goals of mobility indoors and outdoors, shopping, and using public transport. Demographic characteristics were also determined. Responses were Rasch analyzed to determine properties of the scale, derive unidimensional subscales, and consider differential item functioning (DIF). RESULTS: After removal of one ill-fitting item, the remaining 42 tasks formed a scale with reasonable Rasch parameters but poor unidimensionality. The most difficult tasks were orienting in poor and bright light both indoors and outdoors, and avoiding peripheral obstacles outdoors. Eight subscales were derived with unidimensional properties, each of which could be considered as requiring similar skills. DIF identified that tasks from the "poor light and obstacles" subscale were more difficult for those younger than the median age, nonusers of mobility aids, and those not registered or registered sight impaired. Tasks from the "finding products" and "public transport" subscales were more difficult for those older than the median age, with longer duration of visual loss, users of mobility aids, and those registered severely sight impaired. CONCLUSIONS: The most difficult tasks for people with RP of orienting in poor light and avoiding peripheral obstacles are relatively more difficult for those not registered as "severely sight impaired," but are less difficult for those who use mobility aids. Mobility aids (guide dog or cane), therefore, do benefit users in their perceived ability in these particular tasks. The derived unidimensional subscales reorganize the tasks from those grouped together by goal (researcher driven) to those perceived as requiring similar skills by people with RP (patient driven) and can be used as an evidence base for orientation and mobility training protocols.

Physical inactivity in relation to self-rated eyesight: cross-sectional analysis from the English Longitudinal Study of Ageing.

BACKGROUND: To assess the cross-sectional association between self-rated eyesight and physical activity behaviour in a large general population sample of older English adults. METHODS: Analyses of data from the English Longitudinal Study of Ageing. Participants provided information on self-rated eyesight (categorised as: excellent/very good/good/fair-poor) and their own physical activity levels (categorised as: inactive/moderate only at least 1/week, vigorous at least 1/week). Associations between self-rated eyesight and physical activity levels were examined using logistic regression. RESULTS: A total of 6634 participants (mean age 65.0±9.2 years) were included in the analyses. In adjusted logistic regression models, those with fair-poor and good eyesight were significantly more likely to be inactive than those who reported excellent eyesight (OR 2.07, 95% CI 1.58 to 2.72; OR 1.59, 1.27 to 1.99, respectively). CONCLUSION: In this sample of older English adults, those with self-rated fair-poor vision were over twice as likely to be physically inactive than those who reported having excellent vision. When consistent data have emerged, interventions to increase physical activity in those who have poor eyesight are needed.

How does the extent of central visual field loss affect adaptive gait?

Visual impairment is one of the most important clinical risk factors associated with falls. Currently it remains unclear whether adaptive gait is progressively affected as the extent of central visual field loss (CFL) increases, or when CFL exceeds a certain size. 10 participants (aged 22 ± 3 years) negotiated a floor based obstacle in full vision (no occlusion) and wearing custom made contact lenses which simulated 10° CFL and 20° CFL. Movement kinematics assessed the period immediately prior to and during obstacle crossing. In the 20° CFL condition, participants exhibited adaptations in gait which were consistent with being more cautious and more variable during the approach to and crossing of the obstacle, when compared to both 10° CFL and full vision conditions. Specifically, in the 20° CFL condition participants placed their lead foot further from the obstacle, lifted both their lead and trail feet higher and slower over the obstacle, and took longer to negotiate the obstacle when compared to the 10° CFL and full vision conditions. Data highlights differences in adaptive gait as a function of the extent of CFL when compared to full vision. More importantly, these adaptations were only associated with loss of the central 20° of the visual field, suggesting that gait is compromised only after central visual field loss exceeds a certain level.