A treadmill running research protocol to assess dynamic visual acuity and balance for athletes with and without recent concussion history.

Athletes interpret dynamic visual scenes quickly and accurately during physical exertion. It is important to understand how increased exertion may impact vision and cognition following sport-related concussion (SRC).Purpose To examine the effect of a treadmill running research protocol on the assessment of dynamic visual acuity (DVA) and balance for athletes with and without recent history of SRC.Methods Varsity athletes following recent SRC (CONC=12) were compared to athletes without SRC (ATHLETE=19). The DVA task presented a Tumbling 'E' target in four possible orientations during random walk (RW) or horizontal (H) motion at a speed of 30°/s. Participants performed DVA trials standing on a force plate (1000Hz) at four time points: 1) pre-exercise (PRE-EX), 2) immediately (POST1), 3) 10-minutes (POST10), and 4) 20-minutes post- exercise (POST20). Performance was calculated as a change in DVA score from PRE-EX and median response time (RT, ms). Balance control was analyzed using the root mean square of centre of pressure displacement (dCOP).Results Both groups maintained DVA scores for both motion types and exhibited immediate exercise-induced benefits on RT. Both groups had similar change in balance control strategy following treadmill exercise.Conclusion Both groups elicited similar exercise-induced benefits on DVA following exercise. A repeated measures assessment following vigorous exercise may provide meaningful insights about visual and neurocognitive functions for athletes returning to sport following concussion.

An Urgent Call for Concussion Incidence Measures in Para Sport for Athletes with Vision Impairment: A Narrative Review.

Concussion in para athletes with vision impairment (VI) is poorly understood. Recently published studies have suggested that athletes with VI may be more likely to sustain sport-related concussions compared to non-disabled athletes and athletes with other impairment types. There is a critical need for objective concussion incidence measures to determine concussion injury rates and risks more accurately. The aim of this review was to examine the limited available evidence of concussion incidence rates across six different para sports for athletes with VI and encourage the future collection of concussion incidence data and the adoption of injury prevention strategies in VI para sport. A literature search was conducted using four unique databases, which formed the basis of this narrative review. Injury prevention strategies such as modifying sport rules, introducing protective equipment, and incorporating additional safety measures into the field of play have been introduced sporadically, but the effectiveness of most strategies remains unknown. More prospective, sport-specific research examining mechanisms of injury and risk factors for concussion injuries in athletes with VI in both training and competition is needed. This research will help inform the development of targeted injury prevention strategies to reduce the likelihood of concussion for athletes with VI.

Investigation of Camera-Free Eye-Tracking Glasses Compared to a Video-Based System.

Technological advances in eye-tracking have resulted in lightweight, portable solutions that are capable of capturing eye movements beyond laboratory settings. Eye-tracking devices have typically relied on heavier, video-based systems to detect pupil and corneal reflections. Advances in mobile eye-tracking technology could facilitate research and its application in ecological settings; more traditional laboratory research methods are able to be modified and transferred to real-world scenarios. One recent technology, the AdHawk MindLink, introduced a novel camera-free system embedded in typical eyeglass frames. This paper evaluates the AdHawk MindLink by comparing the eye-tracking recordings with a research "gold standard", the EyeLink II. By concurrently capturing data from both eyes, we compare the capability of each eye tracker to quantify metrics from fixation, saccade, and smooth pursuit tasks-typical elements in eye movement research-across a sample of 13 adults. The MindLink system was capable of capturing fixation stability within a radius of less than 0.5∘, estimating horizontal saccade amplitudes with an accuracy of 0.04∘± 2.3∘, vertical saccade amplitudes with an accuracy of 0.32∘± 2.3∘, and smooth pursuit speeds with an accuracy of 0.5 to 3∘s, depending on the pursuit speed. While the performance of the MindLink system in measuring fixation stability, saccade amplitude, and smooth pursuit eye movements were slightly inferior to the video-based system, MindLink provides sufficient gaze-tracking capabilities for dynamic settings and experiments.

Classification in Para skiing: do better performing skiers have better visual functions?

Introduction: Currently, Paralympic skiers with vision impairment are allocated to classes based only on their better eye static visual acuity and visual field diameter. These studies were conducted to investigate whether a broad range of visual functions were different among groups of skiers with different levels of skiing performance. Methods: Static and dynamic visual acuities, contrast sensitivity, light and glare sensitivity, glare recovery, motion perception, and visual field were assessed binocularly in elite Para nordic (n = 26) and Para alpine skiers (n = 15) at 3 international Paralympic events. Skiing performances were calculated using modified skiing points systems based on skiers' raw race times. Clusters of skiers with similar performances were identified in each sport, and their vision and non-vision variables were compared. Results: Skiers in the best performing Para nordic clusters (1 and 2) had better static visual acuities (p = 0.041) and larger visual fields (p = 0.004) compared to cluster 3. In Para alpine slalom (p = 0.019), giant slalom (p = 0.019), and Super-G (p = 0.039) the average static visual acuities among the better performing clusters were significantly better compared to the worst performing cluster. In slalom, the cluster with better performance also had a significantly larger visual field (p = 0.038). In downhill, the better performance cluster demonstrated better dynamic visual acuity (p = 0.029). Discussion: Clusters with better performing skiers appear to have better visual function in both sports. The results of this study would suggest that Para nordic and Para alpine skiers with light perception or no light perception vision should be in one class and that the skiers with quantifiable static VA should be in a different class.

Aerobic Exercise and Human Visual Cortex Neuroplasticity: A Narrative Review.

There is compelling evidence from animal models that physical exercise can enhance visual cortex neuroplasticity. In this narrative review, we explored whether exercise has the same effect in humans. We found that while some studies report evidence consistent with exercise-induced enhancement of human visual cortex neuroplasticity, others report no effect or even reduced neuroplasticity following exercise. Differences in study methodology may partially explain these varying results. Because the prospect of exercise increasing human visual cortex neuroplasticity has important implications for vision rehabilitation, additional research is required to resolve this discrepancy in the literature.

Relationship between dynamic visual acuity and multiple object tracking performance.

We assessed the association between measures of dynamic visual acuity and a multiple object tracking task in physically active young adults. Ninety-four young adults performed the dynamic visual acuity and multiple object tracking tasks. Dynamic visual acuity was measured for horizontal and random walk motion paths at four target speeds (5, 10, 20, and 30°/s). For the multiple object tracking task, participants had to track three out of eight balls for 10 s, and the object speed was adjusted by a staircase procedure. We found that multiple object tracking performance was associated with better identification of horizontally and randomly moving targets in the dynamic visual acuity test (p < .001, r = -.35 [-.52, -.16]; and p < .001, r = -.52 [-.65, -.35]; respectively). This effect was consistent across all target speeds (all p-values<0.05). However, static visual acuity did not correlate with any measure of dynamic visual acuity or multiple object tracking (p > 0.170 in all cases). This study provides novel insights into the association between the ability to identify horizontally and randomly moving targets and track multiple objects. Future studies are needed to determine the potential utility of dynamic visual acuity for talent identification and predicting sports performance in real-game situations.

Effects of caffeine ingestion on dynamic visual acuity: a placebo-controlled, double-blind, balanced-crossover study in low caffeine consumers.

BACKGROUND: Acute caffeine ingestion has been associated with improvements in cognitive performance and visual functioning. The main objective of this study was to determine the effects of caffeine intake on dynamic visual acuity (DVA). METHODS: Twenty-one low caffeine consumers (22.5 ± 1.6 years) took part in this placebo-controlled, double-blind, and balanced crossover study. In two different days and following a random order, participants ingested either caffeine (4 mg/kg) or placebo, and DVA was measured after 60 min of ingesting the corresponding capsule. A recently developed and validated software (moV& test, V&mp Vision Suite, Waterloo, Canada) was used to assess DVA. RESULTS: We found a greater accuracy for both the horizontal and random motion paths of DVA after caffeine ingestion (p < 0.001 and p = 0.002, respectively). In regard to the speed of the response, our data revealed that caffeine intake was associated with a faster reaction time for horizontally (p = 0.012) but not for randomly (p = 0.846) moving targets. Also, participants reported higher levels of perceived activation after consuming caffeine in comparison to placebo (p < 0.001). CONCLUSIONS: Our data suggest that caffeine intake (i.e., a capsule containing 4 mg/kg) has an ergogenic effect on DVA, which may be of special relevance in real-word contexts that require to accurately and rapidly detect moving targets (e.g., sports, driving, or piloting).

Athletes Demonstrate Superior Dynamic Visual Acuity.

SIGNIFICANCE: Athletes exhibit better dynamic visual acuity (DVA) compared with nonathletes, whereas action video game players (VGPs) perform more similarly to controls despite having similar static visual acuity and refractive errors. The differences in DVA between groups were not related to differences in static visual acuity, refractive error, or smooth pursuit gain. PURPOSE: The purpose of the study was to examine whether athletes and VGPs have superior DVA than controls (nonathletes, nongamers). METHODS: Forty-six participants (15 athletes, 11 VGPs, 20 controls) aged 21.7 years (standard deviation, 2.8 years) were recruited. Participants were emmetropic with equivalent monocular and binocular static visual acuity between groups. Dynamic visual acuity was assessed using predictable (horizontal) and unpredictable (random) motion targets at velocities of 5, 10, 20, and 30°/s. Smooth pursuit eye movements were assessed using a horizontal motion step-ramp stimulus at the same speeds. This study was pre-registered with the Center for Open Science (https://osf.io/eu7qc). RESULTS: At 30°/s, there were significant main effects of group (F = 4.762, P = .01) and motion type (F = 9.538, P = .004). Tukey post hoc analysis for groups indicated that athletes performed better than did the control group (t = -2.919, P < .02). An omnibus (group × motion type × speed) repeated measures ANOVA showed a main effect of speed (F = 110.137, P < .001) and a speed × motion-type interaction (F = 27.825, P < .001). Dynamic visual acuity decreased as speed increased, and the slope of the change was greater for random than for horizontal motion. Smooth pursuit gains were not significantly different between groups (P > .05). CONCLUSIONS: Athletes have superior dynamic visual acuity performance compared with controls at 30°/s. This between-group difference cannot be fully explained by differences in smooth pursuit eye movements and therefore may reflect other differences between the groups.

Review: The Quiet Eye in Sports Performance-Is the Quiet Eye the Ultimate Explanation or Only the Beginning?

SIGNIFICANCE: The quiet eye is a gaze behavior that seems to differentiate both expert-novice performance and successful and unsuccessful performance in experts; however, the quiet eye may only represent one aspect of the perceptual-cognitive expertise differences that exist between athletes and nonathletes.Research suggests that expert-novice differences in vision and visual-motor coordination skills exist between athletes and nonathletes, although the underlying mechanisms driving these differences are not well understood. The quiet eye is the final fixation or tracking gaze made before the initiation of the action of importance in a motor coordination task and is quite possibly the most well-studied vision strategy variable in sport. The quiet eye has been shown to be a key component of both expert ability and successful performance. However, the quiet eye is not without its criticisms, and the perceptual mechanisms underlying this unique gaze behavior are not yet well understood. The question that remains to be answered is whether the differences in vision and visual-motor coordination skills that exist between athletes and nonathletes can be explained by the quiet eye alone or if the explanation is more complicated.

Do Impairments in Visual Functions Affect Skiing Performance?

Nordic and alpine skiing-related visual tasks such as identifying hill contours, slope characteristics, and snow conditions increase demands on contrast processing and other visual functions. Prospective observational studies were conducted to assess the relationships between skiing performance and a broad range of visual functions in nordic and alpine skiers with vision impairments. The study hypothesized that contrast sensitivity (CS), visual acuity (VA), and visual field (VF) would be predictive of skiing performance. Binocular static VA, CS, light sensitivity, glare sensitivity, glare recovery, dynamic VA, translational and radial motion perception, and VF were assessed in elite Para nordic (n = 26) and Para alpine (n = 15) skiers. Skiing performance was assessed based on skiers' raw race times. Performance on the visual function tests was compared with skiing performances using Kendall's correlations (with and without Bonferroni-Holm corrections) and linear multivariable regressions (p < 0.05 considered significant). None of the vision variables were significantly correlated with performance in Para nordic or Para alpine skiing after Bonferroni-Holm corrections were applied. Before applying the corrections, VF extent (ρ = -0.37, p = 0.011), and static VA (ρ = 0.26, p = 0.066) demonstrated the strongest correlations with Para nordic skiing performance; in Para alpine skiing, static VA and CS demonstrated the strongest correlations with downhill (static VA: ρ = 0.54, p = 0.046, CS: ρ = -0.50, p = 0.06), super G (static VA: ρ = 0.50, p = 0.007, CS: ρ = -0.51, p = 0.017), and giant slalom (static VA: ρ = 0.57, p = 0.01, CS: ρ = -0.46, p = 0.017) performance. Dynamic VA and VF were significantly associated with downhill (ρ = 0.593, p = 0.04) and slalom (ρ = -0.49, p = 0.013) performances, respectively. Static VA was a significant predictor of giant slalom [(F(3,11) = 24.71, p < 0.001), and R of 0.87], super G [(F(3,9) = 17.34, p = 0.002), and R of 0.85], and slalom [(F(3,11) = 11.8, p = 0.002), and R of 0.80] performance, but CS and VF were not. Interestingly, static VA and CS were highly correlated in both Para nordic (ρ = -0.60, p < 0.001) and Para alpine (ρ = -0.80, p < 0.001) skiers. Of the vision variables, only static VA and VF were associated with skiing performance and should be included as the in Para nordic and Para alpine classifications. The strong correlations between static VA and CS in these skiers with vision impairment may have masked relationships between CS and skiing performance.

Concussion in para sport: the first position statement of the Concussion in Para Sport (CIPS) Group.

Concussion is a frequent injury in many sports and is also common in para athletes. However, there is a paucity of concussion research related to para sport, and prior International Concussion in Sport (CIS) consensus papers have not substantively addressed this population. To remedy this and to improve concussion care provided to para athletes, the concussion in para sport (CIPS) multidisciplinary expert group was created. This group analysed and discussed in-depth para athlete-specific issues within the established key clinical domains of the current (2017) consensus statement on CIS. Due to the onset of the COVID-19 pandemic, the group held all meetings by video conferencing. The existing Sport Concussion Assessment Tool 5 (SCAT5) for the immediate on-field and office-based off-field assessment of concussion was evaluated as part of this process, to identify any para athlete-specific concerns. Regular preparticipation and periodic health examinations are essential to determine a baseline reference point for concussion symptoms but pose additional challenges for the interpreting clinician. Further considerations for concussion management for the para athlete are required within the remove, rest, reconsider and refer consensus statement framework. Considering return to sport (RTS), the 2017 CIS consensus statement has limitations when considering the RTS of the para athlete. Case-by-case decision making related to RTS following concussion is imperative for para athletes. Additional challenges exist for the evaluation and management of concussion in para athletes. There is a need for greater understanding of existing knowledge gaps and attitudes towards concussion among athlete medical staff, coaches and para athletes. Future research should investigate the use and performance of common assessment tools in the para athlete population to better guide their clinical application and inform potential modifications. Concussion prevention strategies and sport-specific rule changes, such as in Para Alpine Skiing and Cerebral Palsy Football, also should be carefully considered to reduce the occurrence of concussion in para athletes.

Exploration of the minimum visual disability criteria for Para nordic and Para alpine skiing using simulated vision impairments.

The International Paralympic Committee Classification Code requires sports to develop evidence-based, sports-specific classification systems. This project aimed to determine the minimum eligibility criteria for Para nordic and Para alpine skiing by simulating vision impairments and measuring the impact of the impairments on performance in twenty-two nordic (28.09 ± 9.68 years; 16 male) and eleven alpine (37.91 ± 18.9 years, 11 male) able-sighted skiers. Eight visual acuity (VA)/contrast sensitivity (CS) (Cambridge Simulation Glasses, University of Cambridge) and six visual field (VF) impairments (bespoke goggles; University of Waterloo) were simulated. VA, CS and VF were measured in each participant before they completed an on-snow session, skiing short competition-style courses with each of the 14 simulated impairments in a randomized order. Clear goggle (no impairment) trials were used as controls. Receiver Operating Characteristic (ROC) and decision tree analyses were conducted to determine the optimum VA, CS and VF cut-offs for classifying performance based on differences from baseline in real time. Moderate impairments in VA, CS and VF negatively affect skiing performance. The recommended cut-off criteria based on both analyses were VA ≥0.90 logMAR and ≤48% VF extent for nordic and VA of ≥0.60 logMAR and VF extent of ≤59.0% for alpine.

Relationship of Contrast Sensitivity Measured Using Quick Contrast Sensitivity Function With Other Visual Functions in a Low Vision Population.

Purpose: Contrast sensitivity (CS) is predictive of various aspects of an individual's functional vision, such as recognizing faces and driving. Currently available CS charts are limited in terms of the spatial frequencies they can test and/or the contrast resolution of the targets they present. The traditional methods for measuring full CS functions (CSFs) are time consuming. The purpose of this study was to examine the feasibility of using the quick CSF method in a low vision population and to assess the relationships of CS with other visual functions, which can contribute to the understanding of the functional vision. Methods: Static visual acuity, dynamic visual acuity, CS, global motion perception thresholds, and visual field were measured binocularly in 53 individuals with low vision. The number of participants who could complete each assessment was used to assess feasibility. The relationships between CS and other visual functions were assessed using linear regressions and multiple regressions. Results: The quick CSF was quantifiable in 34 participants of the 42 with quantifiable visual acuities. The area under the log CSF-the summary statistic of CSF-was significantly correlated with static visual acuity and dynamic visual acuity (r = -0.79 and r = -0.63, respectively; P < 0.001). Conclusions: The qCSF is capable of measuring CS in a wide range of visual impairment severities. area under the log CSF only correlates with measures of visual acuity.

Towards developing a test of global motion for use with Paralympic athletes.

The Paralympic classification system for visual impairment only assesses static visual acuity and static visual field despite many Paralympic sports being dynamic in nature. As a first step towards determining whether motion perception tests should be used in Paralympic classification, we assessed whether motion coherence thresholds could be measured when visual acuity or visual fields were impaired at levels consistent with the current Paralympic classification criteria. Visual acuity and visual field impairments corresponding to Paralympic classification criteria were simulated in normally sighted individuals and motion coherence thresholds were measured. Mild-to-moderate visual acuity impairments had no effect on motion coherence thresholds. The most severe Paralympic class of acuity impairment (≥2.6 logMAR) significantly elevated thresholds. A trend towards superior motion coherence thresholds in the peripheral visual field compared to the central visual field was also present. Global motion perception appears to be measurable under simulated visual impairments that are consistent with the Paralympic classification. Poorer global motion perception was found for visual acuities >2.6 logMAR and visual fields <10° in diameter. Further research is needed to investigate the relationship between global motion perception and sports performance in athletes with real visual impairment.

Post-stroke visual midline shift syndrome.

The state of research on the topic of visual midline shift syndrome following a cerebrovascular accident is unknown. A scoping review was conducted using the search terms of 'visual midline shift' (or equivalent) and 'cerebrovascular accident' (or equivalent). Articles were selected from eight academic and one grey literature database, and went through two levels of review, as per Arksey and O'Malley, before being deemed acceptable for inclusion. Of the 931 abstracts reviewed, 27 articles met the criteria for inclusion. Data extracted from the selected articles included terminology and definition, symptoms, underlying pathophysiology, duration, assessment method, and management of visual midline shift syndrome following cerebrovascular accident. There is agreement on the existence of a midline shift following a cerebrovascular accident resulting in poor posture and imbalance. Much uncertainty exists in the literature regarding terminology, underlying pathophysiology, assessment method and management of this condition. Further research is required.

The effect of mild traumatic brain injury on the visual processing of global form and motion.

Cortical visual processing involves the ventral stream (form perception) and the dorsal stream (motion perception). We assessed whether mild traumatic brain injury (TBI) differentially affects these two streams. Eleven adults with mild TBI (28 ± 9 yrs, 17 ± 5 months post injury) and 25 controls (25 ± 5 yrs) participated. Participants completed tests of global processing involving Glass patterns (form) and random dot kinematograms (motion), measurement of contrast thresholds for motion direction discrimination, a comprehensive vision screening and the Post-Concussion Symptom Inventory (PCSI). Our results showed that the mild TBI group had significantly higher (worse) global form (mean ± SD: TBI 25 ± 6%, control 21 ± 5%) and motion (TBI 14 ± 7%, control 11 ± 3%) coherence thresholds than controls. The magnitude of the mild TBI group deficit did not differ between the two tasks. Contrast thresholds for motion direction discrimination did not differ between the groups, but were positively correlated with PCSI score (r2 = 0.51. p = 0.01) in the mild TBI group. The mild TBI group had worse outcomes than controls for all clinical measurements of vision except distance visual acuity. In conclusion, mild TBI affects processing in both the dorsal and ventral cortical processing streams equally. In addition, spatiotemporal contrast sensitivity may be related to the symptoms of mild TBI.

Sighting ocular dominance magnitude varies with test distance.

BACKGROUND: Ocular dominance can be defined as the preference of an individual for viewing with one eye over the other for particular visual tasks. It is relevant to monovision contact lens wear, cataract surgery and sports vision. Clinically, the measurement of ocular dominance is typically done at an arbitrary distance using a sighting test, such as the hole-in-card method that has a binary outcome. We investigated the effect of test distance on ocular dominance measured using a binocular sighting test that provided a continuous measurement of dominance. METHODS: Ten participants with normal binocular vision took part in this study. Their binocular sighting ocular dominance and phorias were measured at one, two, four, eight and 10 metres. During the dominance tests participants made a binocular alignment judgment and then were asked to indicate the relative alignment of each eye using a visual analogue scale as a reference. RESULTS: Eight participants had strong ocular dominance (five right, three left). For these participants, there was a significant increase in the magnitude of dominance with increasing test distance (p < 0.001). This could not be fully explained by changes in convergence demand. Two participants showed very weak ocular dominance across all test distances (p > 0.05), despite changes in convergence demand. CONCLUSION: When ocular dominance is present, its magnitude varies significantly with test distance. This has significant implications for the accurate measurement of ocular dominance in the clinic and may reflect the neural processes that influence eye preference.

Validity and Repeatability of a Novel Dynamic Visual Acuity System.

PURPOSE: In many sports, athletes rely on visual information from the environment to perform. Some literature suggests athletes have superior visual abilities to non-athletes, particularly on tasks representative of the visual demands of their sport, such as dynamic acuity, eye movement accuracy and speed, and peripheral vision. Other literature suggests there is no difference between athletes and non-athletes, at least when standard clinical assessments are employed. A limitation of the literature is that almost none of the research has been conducted with standardized, validated tools. This is partly caused by a lack of readily available tools to measure tasks representative of the visual demands of sport, and available tests have typically not been validated against current clinical standards. The purpose of this study is to examine the validity and repeatability of a novel visual acuity system (moV&; V&MP Vision Suite) recently developed in the Vision & Motor Performance Lab (V&MP). moV& permits the measurement of many visual function parameters including dynamic visual acuity with predictable, random, and jittering target motion. METHODS: Twenty-five participants attended two study visits, separated by a minimum of 2 weeks. At each visit, static and dynamic visual acuity was measured using Snellen, ETDRS, and moV& charts. Static visual acuities were compared to determine the validity of moV&, and both static and dynamic visual acuities were compared between visits to determine the test-retest repeatability. RESULTS: moV& static visual acuities are clinically similar to visual acuities measured with the ETDRS chart (moV&, -0.09 ± 0.13; ETDRS, -0.03 ± 0.11, concordance correlation coefficient 0.726). Additionally, all static, dynamic, and jitter visual acuities demonstrate good test-retest repeatability (Lin's concordance correlation coefficient range 0.451-0.953). CONCLUSIONS: moV& provides good clinical measures of static visual acuity that are comparable to both Snellen and ETDRS measures. Dynamic visual acuity measures demonstrate good test-retest repeatability.