Reliability of computerized eye-tracking reaction time tests in non-athletes, athletes, and individuals with traumatic brain injury

Background: Eye tracking technologies and methodologies have advanced significantly in recent years. Specifically, the use of eye tracking to quantitatively measure oculomotor and psychophysiological constructs is gaining momentum. Reaction time has been measured in a number of different ways from a simple response to a stimulus to more challenging choice or discrimination responses to stimuli. Traditionally, reaction time is measured from the beginning of a stimulus event to a response event and includes both visual and motor response times. Eye tracking technology can provide a more discrete measurement of reaction time to include visual components such as visual latencies and visual speed, and can identify if the person was looking at the target area when a stimulus is presented. The aim of this paper was to examine the reliability of the simple reaction time, choice reaction time, and discriminate reaction time tests measured using eye tracking technology. Additionally, we sought to establish performance norms and examine gender differences in reaction time in the general population. A final objective was to conduct a preliminary comparison of reaction time measures across different populations including non-athletes, athletes, and individuals that had sustained a traumatic brain injury. Methods: A sample of 125 participants were recruited to undertake test-retest reliability, analysed using Cronbach’s alpha and intraclass correlation coefficients. A different data set of 1893 individuals, including athletes (n = 635), non-athletes (n = 627) and people with traumatic brain injury (n = 631) were compared using MANOVA to explore group differences in reaction time. Results: Results demonstrated that overall, the tests had good test-retest reliability. No significant differences were found for gender. Significant differences were found between groups with athletes performing best overall. Reaction times of people with traumatic brain injury were overall much more variable, showing very large standard deviations, than those of the non-athletes and athletes. Conclusions: Future research should consider the accuracy of eye movements and various demographic variables within groups

Horizontal and vertical self-paced saccades as a diagnostic marker of traumatic brain injury

Aim: Eye tracking tests to measure horizontal and vertical saccades as a proxy for neural deficits associated with traumatic brain injury (TBI) were evaluated in the present study. Methodology: A total of 287 participants reporting either no TBI, mild, moderate or severe TBI participated in a suite of eye tracking tests to measure horizontal and vertical saccadic performance. Results: The horizontal saccades test offered a sensitivity of 0.77 and a specificity of 0.78, similarly the vertical saccades tests offered a sensitivity of 0.64 and a specificity of 0.65. Conclusion: The results indicated that using eye-tracking technology to measure these metrics offers an objective, reliable and quantifiable way of differentiating between individuals with different severities of TBI, and those without a TBI

An examination of the oculomotor behavior metrics within a suite of digitized eye tracking tests

Eye tracking has recently been used to examine oculomotor behavior (OMB) for visual and neurological health and wellness with promise in determining characteristics of healthy eyes and in turn a healthy brain. Recent research has demonstrated that human eye movements reflect individual and group differences, however, clinical evaluations of eye movements often lack test-retest reliability. The purpose of this study was to examine the reliability of oculomotor behavior metrics in healthy individuals, to determine the normative values through cluster analysis, and to compare oculomotor behavior metrics by age groups in a suite of digitized eye tracking tests. A large sample of 2993 participants completed RightEye tests. These tests demonstrated acceptable or higher reliability on 85% of the eye movement metrics and the clustering analysis distinguished 5 distinct age groups. Furthermore, group differences were found between age clusters. Overall, the findings represent the reliability of a computerized oculomotor behavior measure and the importance to consider individual and group characteristics for clinical applications as well as applied settings

Head Position and Posturography: A Novel Biomarker to Identify Concussion Sufferers.

Balance control systems involve complex systems directing muscle activity to prevent internal and external influences that destabilize posture, especially when body positions change. The computerized dynamic posturography stability score has been established to be the most repeatable posturographic measure using variations of the modified Clinical Test of Sensory Integration in Balance (mCTSIB). However, the mCTSIB is a standard group of tests relying largely on eyes-open and -closed standing positions with the head in a neutral position, associated with probability of missing postural instabilities associated with head positions off the neutral plane. Postural stability scores are compromised with changes in head positions after concussion. The position of the head and neck induced by statically maintained head turns is associated with significantly lower stability scores than the standardized head neutral position of the mCTSIB in Post-Concussion Syndrome (PCS) subjects but not in normal healthy controls. This phenomenon may serve as a diagnostic biomarker to differentiate PCS subjects from normal ones as well as serving as a measurement with which to quantify function or the success or failure of a treatment. Head positions off the neutral plane provide novel biomarkers that identify and differentiate subjects suffering from PCS from healthy normal subjects

Oculomotor Behavior Predict Professional Cricket Batting and Bowling Performance

Importance: A new, shorter version of cricket was introduced recently (Twenty20; T20). Since its inception, T20 cricket has rapidly become a popular and exciting format of cricket. However, there is little understanding of factors such as visual-motor control that influence expert performance. Objective: The purpose of this project is to determine if a series of oculomotor measures can predict batting and bowling performance in professional cricket players. Design: This study used a cross-sectional design. Each participant took part in a suite of eye-tracking tests to measure oculomotor behavior compared to their performance data. Participants: This study used a sample of 59 male T20 league professional cricket players (30 Bowlers and 29 Batsman). Results: One-way univariate analyses of variance examined the differences in oculomotor behavior between batsman and bowlers. A series of multiple regression analyses was conducted to evaluate how well the visual variables predict bowling and batting performance variables. Results demonstrate that several oculomotor eye tracking measures were good predictors of run performance and strike rate, including sports total score, sports on-field score, and sports functional score. Likewise, several of the same metrics predicted Runs and Wicket performance for bowlers. Overall, results provided further validation to a growing body of literature supporting the use of eye-tracking technology in performance evaluation

The Pupillary Light Reflex as a Biomarker of Concussion.

The size of our pupils changes continuously in response to variations in ambient light levels, a process known as the pupillary light reflex (PLR). The PLR is not a simple reflex as its function is modulated by cognitive brain function and any long-term changes in brain function secondary to injury should cause a change in the parameters of the PLR. We performed a retrospective clinical review of the PLR of our patients using the BrightLamp Reflex iPhone app. The PLR variables of latency, maximum pupil diameter (MaxPD), minimum pupil diameter (MinPD), maximum constriction velocity (MCV), and the 75% recovery time (75% PRT) were associated with significant differences between subjects who had suffered a concussion and those that had not. There were also significant differences in PLR metrics over the life span and between genders and those subjects with and without symptoms. The differences in PLR metrics are modulated not only by concussion history but also by gender and whether or not the person has symptoms associated with a head injury. A concussive injury to the brain is associated with changes in the PLR that persist over the life span, representing biomarkers that might be used in clinical diagnosis, treatment, and decision making

Vertical smooth pursuit as a diagnostic marker of traumatic brain injury.

AIM: Neural deficits were measured via the eye tracking of vertical smooth pursuit (VSP) as markers of traumatic brain injury (TBI). The present study evaluated the ability of the eye tracking tests to differentiate between different levels of TBI severity and healthy controls. METHODOLOGY: Ninety-two individuals divided into four groups (those with mild, moderate or severe TBI and healthy controls) participated in a computerized test of VSP eye movement using a remote eye tracker. RESULTS: The VSP eye tracking test was able to distinguish between severe and moderate levels of TBI but unable to detect differences in the performance of participants with mild TBI and healthy controls. CONCLUSION: The eye-tracking technology used to measure VSP eye movements is able to provide a timely and objective method of differentiating between individuals with moderate and severe levels of TBI

Oculomotor Behavior as a Biomarker for Differentiating Pediatric Patients With Mild Traumatic Brain Injury and Age Matched Controls.

IMPORTANCE: Children have the highest incidence of mild traumatic brain injury (mTBI) in the United States. However, mTBI, specifically pediatric patients with mTBI, are notoriously difficult to detect, and with a reliance on traditional, subjective measurements of eye movements, the subtle but key oculomotor deficits are often missed. OBJECTIVE: The purpose of this project is to determine if the combined measurement of saccades, smooth pursuit, fixations and reaction time represent a biomarker for differentiating pediatric patients with mild traumatic brain injury compared to age matched controls. DESIGN: This study used cross-sectional design. Each participant took part in a suite of tests collectively labeled the "Brain Health EyeQ" to measure saccades, smooth pursuit, fixations and reaction time. PARTICIPANTS: The present study recruited 231 participants - 91 clinically diagnosed with a single incident mTBI in the last 2 days as assessed by both the Glasgow Coma Scale (GCS) and Graded Symptoms Checklist (GSC), and 140 age and gender-matched controls (n = 165 male, n = 66 female, M age = 14.20, SD = 2.78). RESULTS: One-way univariate analyses of variance examined the differences in performance on the tests between participants with mTBI and controls. ROC curve analysis examined the sensitivity and specificity of the tests. Results indicated that together, the "Brain Health EyeQ" tests were successfully able to identify participants with mTBI 75.3% of the time, providing further validation to a growing body of literature supporting the use of eye tracking technology for mTBI identification and diagnosis

Brain Vital Signs in Elite Ice Hockey: Towards Characterizing Objective and Specific Neurophysiological Reference Values for Concussion Management.

Background: Prior concussion studies have shown that objective neurophysiological measures are sensitive to detecting concussive and subconcussive impairments in youth ice-hockey. These studies monitored brain vital signs at rink-side using a within-subjects design to demonstrate significant changes from pre-season baseline scans. However, practical clinical implementation must overcome inherent challenges related to any dependence on a baseline. This requires establishing the start of normative reference data sets. Methods: The current study collected specific reference data for N = 58 elite, youth, male ice-hockey players and compared these with a general reference dataset from N = 135 of males and females across the lifespan. The elite hockey players were recruited to a select training camp through CAA Hockey, a management agency for players drafted to leagues such as the National Hockey League (NHL). The statistical analysis included a test-retest comparison to establish reliability, and a multivariate analysis of covariance to evaluate differences in brain vital signs between groups with age as a covariate. Findings: Test-retest assessments for brain vital signs evoked potentials showed moderate-to-good reliability (Cronbach's Alpha > 0.7, Intraclass correlation coefficient > 0.5) in five out of six measures. The multivariate analysis of covariance showed no overall effect for group (p = 0.105), and a significant effect of age as a covariate was observed (p < 0.001). Adjusting for the effect of age, a significant difference was observed in the measure of N100 latency (p = 0.022) between elite hockey players and the heterogeneous control group. Interpretation: The findings support the concept that normative physiological data can be used in brain vital signs evaluation in athletes, and should additionally be stratified for age, skill level, and experience. These can be combined with general norms and/or individual baseline assessments where appropriate and/or possible. The current results allow for brain vital sign evaluation independent of baseline assessment, therefore enabling objective neurophysiological evaluation of concussion management and cognitive performance optimization in ice-hockey