King–Devick Test

Concussion Testing

The King–Devick Test in association with Mayo Clinic, a remove-from-play concussion screening tool, is a two-minute test that requires an athlete to read single digit numbers displayed on an electronic device and can be administered by coaches, athletic trainers, medical professionals or parents. Athletes must establish an individual preseason or pregame baseline. A baseline score is the cumulative amount of time it takes to read the three test cards aloud. For baseline testing, the entire test should be administered twice. The fastest cumulative time of the two attempts with no errors is the baseline score. Immediately or soon after a suspected head trauma, the athlete is given the King–Devick Test once. If the time to complete the test is any worse (longer) than the athlete’s baseline test time and/or if there are errors, the athlete should be removed-from-play and should be evaluated by a licensed professional. The test has relevance to sports such as: football, hockey, soccer, boxing, lacrosse, rugby, basketball and all other contact or collision activities. The King–Devick Test in association with Mayo Clinic is used in youth leagues, high school and college athletic programs. The test is also used at the professional level in Arena Football League, the National Hockey League (NHL), Major League Soccer (MLS), Major League Lacrosse (MLL), Canadian Football League (CFL), and Rugby Football Union (RFU).

Research

A 2015 meta-analysis and systematic review of the literature on the King–Devick Test as a rapid sideline tool to aid in the detection of sports-related concussion was published in the first release of the journal Concussion. The study analyzed 15 published studies which looked at the effectivity of the K-D Test to differentiate concussed vs non-concussed athletes. Results demonstrated high test sensitivity and specificity (86% and 90% respectively). The use of the K-D Test, along with concussion screening tests, Standardized Assessment of Concussion (SAC) and Balance Error Scoring System (BESS), was shown to detect 100% of clinically diagnosed concussions in this meta-analysis. Any longer or worse score from baseline indicated a 5 times greater risk of a concussion. The K-D test has the potential to screen for unwitnessed, or sub-concussive neurologic impairment as the result of injury from impulsive forces. Baseline K-D Test times were shown to improve with increasing age among youth athletes highlighting the importance of annual baseline testing. In addition, studies showed that noise and exercise had no impact on K-D Test performance. The article concluded that the K-D Test contributes a critical dimension of vision-based performance testing to sports-related concussion screening.

In 2015, results of a 3-year prospective observational cohort study of amateur rugby were published in the Journal of the Neurological Sciences. Similar to previous studies of amateur rugby, the K-D Test was studied to determine if it could aid in identifying witnessed and unwitnessed concussive injury. A total of 52 concussions were identified over the duration of the study. Of the 52 concussions, 8 were witnessed and 44 were unwitnessed resulting in a six-fold difference between witnessed and unwitnessed concussions. This underscores the utility of the K-D Test in identifying neurologic impairment in players without clinically observable symptoms.

In 2016 researchers at NYU School of Medicine conducted a laboratory-based eye movement study of ocular motor behavior during the K-D Test in patients which chronic concussion to identify features associated with prolonged K-D reading times. Their results published in Annals of Clinical and Translational Neurology showed that average inter-saccadic intervals (ISI) time, which represents a combined measure of saccade latency and fixation duration, were significantly longer among concussed as compared to controls. Digitized K-D reading times were also prolonged in concussed vs. non-concussed controls. Concussion was also associated with a greater total number of saccades and larger average deviations of saccade endpoint distances from number targets. ISI and number of saccades correlated with K-D time as well as with post-concussion symptom inventory (PCSI) scores.

In 2016 the Journal of the Neurological Sciences published a study aimed to identify and validate the K-D test for screening acute mTBI in warfighters. Subjects diagnosed with mTBI (≤72 hours) performed the K-D Test approximately 36% slower than age-matched controls. Additionally, there was strong test-retest reliability in K-D tests in both groups. The results suggest acquiring K-D baselines prior to deployment and training. Having a validated, rapid, easy-to-assess mTBI brain screening test can assist frontline providers in screening for acute mTBI.

In 2014, the Journal of Sports Medicine and Physical Fitness published a study examining the K–D test as a screening tool for concussion when administered by layperson sports parents in a cohort of amateur boxers. The K–D Test was administered to each athlete pre- and post-fight by trained laypersons who were masked to the head trauma status of each athlete. The matches were watched by a ringside physician, who tested athletes with suspected head trauma with the Military Acute Concussion Evaluation (MACE). In the absence of concussion, post-fight KD scores were better than the best baseline score (41.0 vs 39.3s, p=0.34, Wilcoxon signed-rank test). One boxer sustained a concussion as determined by the ringside physician. This boxer was accurately identified by the layperson K–D testers due to a worsening in K–D Test compared to baseline and an increased number of errors. Additionally, test re-test reliability measures were high and comparable between layperson K-D Test administrators and previously reported reliability measures from medically trained K-D testers. This study supported the K–D test as a rapid sideline screening tool for concussion that can be effectively administered by non-medically trained laypersons.

A 2015 study published in the Journal of Neuro-Ophthalmology, investigated sideline concussion testing in 243 youth (ages 5–17) and 89 collegiate (ages 18–23) hockey and lacrosse athletes. Baseline assessments included the K-D Test, the SAC and the timed tandem gait. In the event of a concussion, injured athletes were re-tested on the sideline or rink-side. Non-concussed athletes were also assessed as control participants under the same testing conditions. The K-D test was validated in ages as young as 5. Among 12 athletes who sustained concussions during their athletic season, K-D Test scores worsened from baseline by an average of 5.2 seconds. The vision-based K-D Test showed the greatest capacity to distinguish concussed vs. control athletes based on changes from pre-season baseline to post-injury when compared with other concussion screening tests, timed tandem gait and SAC. The study concluded that adding a vision-based performance test to cognitive and balance testing enhances the detection capabilities of current sideline concussion assessment. In addition, the impact that mild traumatic brain injury has on K-D Test performance reflects the involvement and distribution of the brain pathways dedicated to vision.

In 2011, a longitudinal study published in the Journal of the Neurological Sciences was conducted involving 219 athletes from the University of Pennsylvania varsity football, sprint football, women’s and men’s soccer and basketball teams. Each subject underwent baseline King–Devick (K–D) testing prior to the start of the 2010-11 playing season. For athletes who had concussions during the season, K–D testing was administered immediately on the sidelines and changes in score from their baseline were determined. For the 10 athletes who had concussions, K–D testing showed worsening from their baseline score/time. Additionally, the effect of the physical exertion on K–D Test performance was studied in a subgroup analysis of men's basketball-players who received K–D testing immediately following an intense two hour scrimmage. These athletes, none of which sustained concussion, did not show any worsening of their K–D score, but instead showed improvement from baseline even in the setting of post-workout fatigue demonstrating that the K–D test is robust to physical fatigue. This study of collegiate athletes provided further evidence in support of the K–D Test as a strong candidate rapid sideline visual screening tool for concussion. In 2011, researchers from the University of Pennsylvania Perelman School of Medicine published a study in Neurology (journal) of an investigation of the King–Devick Test as a potential rapid sideline screening test for concussion in a cohort of 39 boxers and mixed martial arts (MMA) fighters. A pre-fight K-D Test baseline was determined and a post-fight K-D Test was also administered after bouts. Post-fight K–D time scores were significantly worse (higher) than pre-fight scores for participants who had sustained head trauma during the match. Additionally, statistical analysis showed that the K–D test had high test-retest reliability. The researchers concluded that the King–Devick Test is an accurate and reliable method for identifying athletes with head trauma, and is a strong candidate rapid sideline screening test for concussion.

In 2012, the K–D test was studied in the amateur New Zealand rugby athletes over the course of a competitive season. In this pilot study of 50 rugby athletes (mean age 19.3 years ± 4.0 standard deviation) published in Journal of the Neurological Sciences, the K–D test was able to accurately identify three players with witnessed head trauma who were subsequently diagnosed with concussion. By testing all athletes post-match, the K–D test was able to identify two players that had sustained a concussive injury that was neither reported nor witnessed. In this rugby cohort, the K-D Test was not only useful in identifying changes in players with witnessed head trauma, but in identifying changes in players with an un-witnessed, suspected concussion by simply testing all players after contact play.

In 2012, the K–D test was included in a comprehensive review published in Current Neurology & Neuroscience Reports comparing sports-concussion testing tools. The review stated that the K-D Test captures impaired eye movements and saccades, attention and language which involve the integration of functions of the brainstem, cerebellum and cerebral cortex and thus proposed that the K–D test has the potential to capture brain impairment not observed in standard neurocognitive testing. It reported that the K–D test can be administrated in the quickest amount of time (less than 2 minutes as compared to others requiring upwards of 20 minutes for test administration). The K–D test does not require a medical professional to administer, assesses more the 50% of the brain’s pathways and gives a definite and objective outcome measure making it practical for sideline use at all levels of sports. In 2013, the K–D test was investigated in a prospective observational cohort study of 37 (mean age 22.0 years ± 4.0 years) amateur New Zealand Rugby Union players across 24 games. There were 22 concussive incidents recorded over the duration of the competitive season. Five concussive incidents were witnessed and accurately identified by the K–D test. Routine post-match screening for concussion with the K–D test identified an additional 17 unrecognized incidents in which players had not shown, or reported, any signs or symptoms of a concussion but who had sustained meaningful head injury. This study further supports that the K–D test is sensitive to neurological changes such as those seen with sports-related concussion.

In 2013, a prospective study evaluated the K–D test in the Philadelphia Flyers professional ice hockey team. In this exploratory analysis of 27 athletes (mean age 28.0 years ± 5.0 years) two players tested rink side immediately following concussion demonstrated worsened K–D test scores from baseline. For Sport Concussion Assessment Tool 2's (SCAT2) Standardized Assessment of Concussion (SAC) components, however, these athletes showed no differences between baseline and rink side concussion testing, but reported symptoms of concussion. Additionally, at baseline testing for the cohort, lower scores for the SCAT2 SAC Immediate Memory Score and Overall SAC score were associated with greater (worse) times required to complete the K–D test. Both working and saccadic eye movements share closely related anatomical brain structures, including the Dorsolateral Prefrontal Cortex (DLPFC) an area vulnerable to injury in concussion and therefore may explain some of the eye movement and memory related symptoms in athletes and other patients with concussion.

In 2013, a study of the K–D test in a cohort of 47 high school football players during the 2012 football season was presented at the Association for Research in Vision and Ophthalmology (ARVO) annual meeting. During the season, three athletes sustained concussion and all demonstrated increased (worse) K-D Test performance times when tested shortly after the on-field injury. K–D test times were worsened by 41%, 100% and 143% respectively in these three athletes. Test-retest reliability was analyzed using intraclass correlation coefficients (ICC) between baseline and end of season data and demonstrated high test-retest reliability, supporting findings of previous studies showing high reliability of the K-D Test. This study showed that the K–D test is effective as a rapid sideline tool to identify concussion at the high school youth sports level.

In 2013, a study comparing the Symbol Digit Modalities Test (SDMT) and the K–D test in a cohort of 16 mixed martial arts (MMA) fighters was presented at the European Neurological Society and the American Academy of Neurology Annual Meetings. Fighters were given K-D Test at both pre-fight and post-fight by a single examiner. Changes in scores were compared for those with head trauma during the fight vs. those without. There was a modest correlation between head trauma during the match and worsening (increase) in K–D scores (r=0.54, p=0.015), the actual change (r=0.42, p=0.055) and the percentage change in K–D scores from pre to post-fight (r=0.50, p=0.025). There was only small to medium correlation between worsening of SDMT score (decrease) and K–D score. There was no correlation between SDMT scores and concussions during the match. This study concluded that the K-D Test is vastly superior to the SDMT as a sideline determinant of concussion in MMA fighters.

In 2013, Neurosurgery published an article underscoring the need for the K-D Test, a basic yet highly predictive sideline test that can be performed by laypersons during a game to determine concussive as well as sub-concussive events. Specifically stating, "The need for sideline rapid assessment of mild head injury is fundamental to limiting the deleterious effects of repeated impacts to the head. The great majority of athletes are at the youth sports level and not in collegiate or professional sports, which leaves many important decisions to be made by parents and coaches on the sideline. This structural element of sport is unlikely to change since allocating medically trained people to youth sports will require unavailable financial resources. Accordingly, empowering adults to administer a simple, rapid, yet effective test is paramount to preventing repeated head injury. As increasing evidence suggests that even mild impact to the head can lead to accruing neuropathology, it may be prudent to routinely perform sideline testing for players involved in even modest collisions. This could help avoid return to play of athletes with sub-concussive impacts as knowledge about head injury continues to evolve."

In 2013, the Journal of the Neurological Sciences published a study examining convenient tools to provide accurate and rapid information to assist in evaluating concussions as well as effective ways to assess and track recovery following the injury. The K–D test was compared with the Post-Concussion Symptom Scale (PCSS) and computerized neurocognitive composite scores in 35 adolescent concussion patients (age 16.1 ±1.7 years) over four clinical visits. K-D times improved with each visit during the period of concussion recovery and paralleled improvements in PCSS, reaction time and visual motor speed. The article concluded that the findings support the use of K-D testing in an acute setting and as part of a multidimensional approach to assessing concussion status during a potential long-term recovery period.

In 2013, the Journal of Child Neurology published a study assessing 10 youth football players immediately before and after their season to explore the effects of football participation on selected clinical measures of neurological function. Oculomotor performance was assessed by the K–D test, and was shown to improve moderately to significantly (P 1/4 .047-.115). This study showed that a 12-week season of youth football did not impair the postural stability, neurocognitive function or oculomotor performance measures of the participants.

In 2013, the National Institutes of Health funded a report, Sports-Related Concussions in Youth: Improving the Science, Changing the Culture. The report identified the K–D test as a tool designed to assess saccadic eye movements, measuring the speed of rapid number naming as well as errors made by the athlete, with the goal of detecting impairments of eye movement, attention, and language as well as impairments in other areas that would be indicative of suboptimal brain function. The K-D Test is further recommended to be used either by trained responders as part of an acute sideline or in-field assessment or by health care providers during subsequent clinical evaluation. In 2014, Sports Medicine published a systematic review of the literature in regard to the history, pathophysiology, recognition, assessment, management and knowledge of concussion. The review states that the task of the K-D Test requires integration of multiple sensory inputs, motor efforts and cognitive processes such as target selection, sustenance of attention, spatio-temporal memory and expectation. It highlighted that poor oculomotor function has been determined as one of the most robust discriminators for the identification of an mTBI (mild traumatic brain injury). The K–D test was recommended as part of the initial sideline assessment to identify athletes with concussion.

In 2014, Annals of Internal Medicine published a comprehensive clinical practice article, In the Clinic: Concussion to review the current evidence for prevention, diagnosis, treatment, and prognosis of concussion. The K-D Test was recommended as a tool for rapid oculomotor examination that can be used in the office or on the sideline to determine impairment of eye movements associated with an acute concussion and that the 1-minute test is useful to determine removal from play.

In 2014, The Sport Journal published a study, Baseline Concussion Testing in Different Environments: A Pilot Study, in order to examine the reliability of baseline testing with King–Devick Test in different environments. Participants were tested in both quiet and loud environments. They found that there were no significant changes in KD scores between quiet and loud environments.

In 2014, a retrospective study featured in Neurology Clinical Practice examined King–Devick Test as a complement to components of the SCAT3. Baseline and post injury testing from University of Florida athletes for King–Devick Test, Standardized Assessment of Concussions (SAC) and Balance Error Scoring System (BESS) were explored. Among 30 athletes with concussion, King–Devick Test identified 79% of concussions, and SAC showed a ≥ 2 point worsening in 52% of concussed athletes. Combining K–D and SAC captured abnormalities in 89%; adding the BESS identified 100% of concussions. The study highlights the value of adding a visual test that measures neurologic dysfunction not captured by sideline cognitive or balance tests. Additionally correlations in the study between K-D Test scores and ImPACT visual motor scores at baseline were similar to previous studies and support the validity of the K-D Test as a test that requires visual function.

In 2014, Mayo Clinic investigated the K-D Test in a study of 141 high school hockey players. Baseline, immediate post-concussion and post-season K-D Test administrations were completed. During the season, 20 athletes reported head injury. All 20 had immediate post-concussion K-D Test time higher (worse) from baseline and scores in concussed players remained abnormal over time as postseason assessments for all but 2 were worse. To determine the impacts of fatigue and sub concussive hits on KD scores a subgroup of 51 non-concussed players were assessed immediately before and after a game. After physical fatigue from game participation, these non-concussed athletes showed no significant worsening time change. The study also detected potential brain injuries in athletes who had not reported symptoms of concussion by demonstrating worsening K-Devick Test times at the end of the season. These findings were similar to previous studies that found the K-D Test useful in detecting unwitnessed, unreported concussion. “The King–Devick Test represents a rapid, accurate, and cost-effective tool to identify concussion on the sideline and make appropriate game-time, remove-from-play decisions,” said Dr. Amaal Starling, Mayo Clinic neurologist and co-investigator of the study. The study results were presented at the American Academy of Neurology Annual Meeting.

In 2014, researchers at New York University School of Medicine (NYU) presented a study of Vision-Based Performance Testing as a Complement to SCAT3/Child-SCAT3 in Youth and Collegiate Athletes at the American Academy of Neurology Sports Concussion Conference. Members of a youth ice hockey and lacrosse league (aged 5 to 17 years old) as well as collegiate athletes from NYU and Long Island University (LIU) were included in this prospective study examining the K-D Test, SAC (cognition) and time tandem-gait (balance) tests. Baseline K-D scores improved with increasing age in the youth cohort highlighting the need for establishing annual individual baselines. Among 12 athletes with concussion during the season, K-D Test time worsened from baseline by an average of 5.2 seconds and compared to an improvement of 6.4 seconds in non-concussed controls (n=14). K-D Test showed the greatest capacity to distinguish concussed vs. control groups based on changes from baseline (Receiver Operating Characteristic (ROC) curve areas from logistic regression models, accounting for age= 0.92 for K-D, 0.87 for tandem, 0.68 for SAC, p=0.0004 for comparison of areas). Researchers concluded that "adding a rapid simple vision-based performance measure to cognitive and balance tests enhances the detection capabilities of current sideline assessments for concussion. Because rapid number naming captures visual function, K-D is a useful tool to aid in the diagnosis of concussed athletes at all levels of sports." The study was published in the Journal of Neuro-Ophthalmology (journal) in 2015.

In 2014, King–Devick Test retest reliability was examined in elite youth athletes at the American Athletic Union AAU Junior Olympic Games and showed high levels of test-retest reliability in youth athletes age 6 to 17 years of age.

In 2014, the King–Devick Test was featured in The Lancet Neurology as a sideline test of visual functioning in the setting of sports-related concussion stating that, "because many aspects of vision relate to high cognitive functioning, which is characteristically compromised in mild TBI, and because many of the pathways in the brain are devoted to afferent and efferent vision, tests of visual function are promising candidates as rapid sideline tests." It goes on to review the neurology of the King–Devick Test stating that, "performance on the K-D Test partly shows how well the patient is able to perform anticipatory saccades; the origin of anticipatory saccades has been localized to the dorsolateral prefrontal cortex, an area susceptible to injury in TBI. The K-D Test also evaluates visual attention and language, which may be compromised in brain injury. The K-D Test is a visual performance measure and one advantage is that it does not require the clinical expertise to discern normal versus abnormal eye movements. The K-D Test was shown to take about 5–7 seconds longer to complete in concussed boxers, mixed-martial-arts fighters, collegiate athletes, professional ice hockey players, and rugby players, and was shown to be a sensitive measure of detecting concussions in these athletes."

A Countywide Concussion Program was implemented in 40 high schools in Miami-Dade County which was detailed in The Sport Journal in 2014. The Miami Concussion Model (MCM) trained 100 coaches and 40 athletic trainers who performed baseline testing for 18,357 athletes. The K-D test and SCAT2 were utilized in concussion detection. The MCM standard protocol effectively increased the number of identified concussions from 44 concussed athletes in 2010 to 155 athletes in 2012 following implementation. The MCM may be used as a model for other counties to implement a successful concussion management program.

For broader K-D test implementation, the feasibility of performing the sideline K-D Test at high school football games in Guam was evaluated and results were published in Surgical Neurology International. They highlighted the K-D Test stating that, "the value of the K-D Test is in its brevity (2-3 min) and ease of administration. In addition, post-injury recommendations are specific for each player, with respect to their established baseline, which means the test is more IQ‑independent and can be performed by most athletes. Furthermore, the test administrator needs no formal or extensive training to use the iPad application or to administer the physical test, which increases the value of KD. It is an SCT that can be administered by coaches, athletic trainers, or parents depending on the resources available to the team."

Neurologists presented a study at the American Academy of Neurology (AAN) 2014 Annual Meeting which examined the K-D Test as a concussion screening tool in high school hockey players. Twenty out of 141 players sustained head injuries and had immediate post-concussion K-D scores greater than 5 seconds from baseline scores. The K-D test accurately identified all diagnosed concussions immediately following the injury in these young athletes.

Also presented at AAN was a study comparing the K-D Test to the Symbol Digit Modalities Test (SDMT) as rapid sideline screening tools for concussion in mixed martial arts fighters. There was an overall worsening of K-D scores in fighters with head trauma. There was no correlation between SDMT scores and concussion during the match. The K-D Test was more reliable in identifying a change elicited by head trauma in this cohort compared to the SDMT.

In 2015, the Scandinavian Journal of Medicine & Science in Sports published a study of professional ice hockey players' baseline King–Devick Test performance in an effort to establish normative data. Among the 185 professional athletes aged 16 to 40 years the average K-D Test time was 40.0s with a standard deviation of 6.1s and ranged from 24.0 to 65.7 seconds. They concluded that, "without reliable baseline measurement, it is not possible to know if that score indicates a decline for that particular individual or not." This study emphasizes the need for an individual baseline for comparison when using the King–Devick Test as screening tool for concussion.

In 2015, the Journal of Optometry published a study of collegiate football and men's and women's basketball investigating the K–D test as a sideline screening tool examining the effect of concussion on K–D test performance and the effect of physical exercise on K–D scores in the absence of concussion. The participants underwent K–D baseline testing at pre-season physicals. Football players with suspected head injury were immediately tested using the K–D test on the sidelines. Post-season testing was also performed. Basketball players were tested immediately following an intense 2.5 hour workout to test the effects of physical exercise on K–D performance. Sideline scores of concussed athletes (n=11) were significantly higher than baseline (36.5±5.6s, vs. 31.3±4.5s, p<0.005, Wilcoxon signed-rank test). There was no worsening in K–D scores after physical fatigue. Rather, in basketball players, K-D scores post-workout showed improvement (31.8±4.9 vs. 34.5±4.8, p<0.05, Wilcoxon signed-rank test). Post-season testing showed improvement of scores consistent with known learning effects of the K-D Test as a performance measure (35.1±5.2s vs. 34.4±5.0s, p<0.05, Wilcoxon signed-rank test). Test-retest reliability was analyzed between baseline and post-season testing resulting in high levels of test-retest reliability. This study supports the K–D test as an accurate, reliable sideline tool to identify concussions.

In 2015, the K-D Test was featured in a review of neuro-ophthalmologic findings associated with concussion. Published in the Journal of Neuro-Ophthalmology, the review emphasizes that as a visual performance measure with an objective end point, the K-D Test can be administered at the sideline by a nonprofessional including parents of youth athletes. "Eye movement abnormalities commonly occur with concussion and the K–D test allows them to be assessed without the clinical expertise that would otherwise be required." It goes on to add that, "the K–D test complements components of the SCAT3 and improves the detection of concussions."

Similar to previous studies, the K-D Test was administered to amateur rugby players to determine its ability to detect both witnessed and unrecognized concussions. Routine post-match screening with K-D Test identified 44 unwitnessed concussions over the duration of the study, 6 times more than the 8 witnessed concussions identified pitch-side. According to the study, K-D Test resulted in concussion sensitivity and specificity rates of 100% and 94% respectively. K-D scores correlated with SAC scores for players with concussive injury. By using a return to play monitoring process with the K-D Test, the team medic was able to identify players that could commence graduated return-to-play activities while still monitoring the player's recovery. This underscores the utility of the K-D Test in identifying neurologic impairment in players without clinically observable symptoms. The results were published in the Journal of the Neurological Sciences

In 2015, the Journal of the Neurological Sciences published an article evaluating the K-D test in 343 high school football athletes. Nine concussions were diagnosed during season, and among all concussed athletes sideline K-D Test times were significantly worse compared to baseline. In addition, K-D scores in non-concussed athletes did not vary significantly from pre- to post-season. No non-concussed athletes increased or worsened K-D Test time compared to baseline, which supports the instruction that any increase in KD test time is indicative of a concussion.

In 2015, the Concussion Center at New York University Langone Medical Center examined a wide range of patients (ages 10–77) with concussions to investigate the utility of the SCAT3 symptoms evaluation, SAC, mBESS, and K-D Test. The results indicated correlations between K-D Test performance and other measures. Worse K-D Test and mBESS scores were associated with increasing age, worse K-D scores correlated with worse Immediate Memory scores on SAC testing, and worse K-D scores were associated with higher symptom severity scores. The dorsolateral prefrontal cortex plays a role in controlling working memory, saccadic function, motor planning, and emotions, which may, in part, explain the correlation. The results were published in the Journal of the Neurological Sciences.

A prospective study of youth rugby players, ages 9–10, evaluated the K-D test in detecting concussion in a junior rugby league. Routine post-match screening with K-D Test identified 7 unwitnessed, unreported concussions that were later diagnosed by a physician. The K-D Test was an effective tool to determine if a player should be removed from play and referred to a physician for further evaluation of both witnessed and unwitnessed concussions. The K-D Test was able to detect unwitnessed concussions, which would not have been diagnosed otherwise. This study, published in the Journal of the Neurological Sciences, concluded that the K-D Test is a reliable, effective concussion assessment tool.

The K-D Test was featured in a 2015 article published in Seminars in Neurology which detailed the role of vision in concussion diagnosis and management. The article confirms that the K-D Test evaluates brainstem, cerebellum, and cortical functioning using rapid number naming, saccadic eye movements, attention, and language components. When the K-D Test is combined with SAC and BESS testing, sensitivity of concussion testing is increased, and the K-D Test has the greatest ability to identify concussed individuals in comparison to timed tandem-gait and SAC testing.

King-Devick Test Online System (KDTOS)

The secure browser-based King–Devick Test Online System (KDTOS) allows users to administer the K-D Test from an internet connected computer or laptop. The KDTOS stores athletes' baseline data and unlimited test history. Features include conveniently organizing athletes by team, printing reports and assigning multiple administrator logins.

King-Devick Test in association with Mayo Clinic iPad & Android App

The King–Devick Test in association with Mayo Clinic App is a companion to the King–Devick Test Online System (KDTOS). K-D Test app is compatible with standard sized iPads and approved Android tablets and allows administration of the K-D Test on a tablet even when internet connection is not available. All offline user data can be synchronized to the secure KDTOS account once an internet connection is available. Other features include unlimited baseline and post-injury K-D Tests, symptoms checklist, and orientation questions.

In the News

In 2016 the Rugby Football Union (RFU) and the English professional club game announced a player safety initiate to improve the recognition of concussed players. “We have made huge progress on concussion management in the last few years but we know we have to continue to innovate and develop our systems as player welfare is our No 1 priority,” said Corin Palmer, Head of Rugby Operations at Premiership Rugby. The K-D Test is being investigated and conducted on all players in all Aviva Premiership Rugby and Green King IPA Championship. World Rugby, who are supportive of the initiative, have approved an extension of the current 10-minute Head Injury Assessment (HIA) to 13 minutes in these two competitions to allow the K-D Test to be performed. Because the test does not need to be supervised by a medical practitioner it has significant potential to improve concussion assessment in the future in both the professional and community games. “These projects show English professional rugby’s strategic commitment to concussion education, identification and research,” said Dr. Simon Kemp, chief medical officer for the RFU.

In 2016 the Canadian Football League (CFL) announced the extension of their breakthrough concussion screening study to all of its teams during the 2016 season. Kevin McDonald, Vice-President of Football Operations and Player Safety for the CFL stated, “Our research last year, conducted in concert with the National Football League, showed promising results and that has led the medical staffs from our clubs to conclude that the K-D Test is a viable tool and worth implementing across the CFL.”

In 2016 the National Hockey League announced the use of the K-D Test on the rink side medical staff of 12 NHL teams. Dr. Ruben Echemendia, Co-Chair of the NHL/NHLPA Concussion Subcommittee, added “We are constantly looking for new tests and procedures that may enhance our already comprehensive concussion assessment program and look forward to examining the results of this pilot project. It is our hope that the addition of the King-Devick Test will increase our ability to more-accurately diagnose concussions in NHL players.”

In the 2015 professional football preseason, the National Football League (NFL) announced a partnership with the Canadian Football League (CFL) on implementing additional concussion testing during CFL games and practices. Medical staff are currently using the K-D Test in training camps and throughout the 2015 season.

In the summer of 2015, the K-D Test was included in a concussion testing program provided to 70 Michigan state high schools by the Michigan High School Athletic Association (MHSAA) for the 2015-16 school year. As part of the program, the MHSAA also mandated record-keeping for member schools regarding potential concussive events from detection through to the athlete's return to play and will involve both genders and all levels of sports, from 7th through 12th grade.

Before the fall 2012 football season, King–Devick Test kits were donated to all Chicago Public Schools (CPS) high school football programs by the Dave Duerson Foundation to ensure that every CPS football team had an effective sideline remove-from-play concussion screening tool. The donation was made in an effort to contribute to a safer game of football in the memory of Dave Duerson who was a former Chicago Bears football player.

In August 2011, Ralph Nader publicly called for the mandatory implementation of the King–Devick Concussion test in high school and youth sports. “Too many sports organizations, from little leagues to the professional level, continue to have their heads in the sand when it comes to concussion safety and prevention measures," said Nader. “The growing mound of research showing the often devastating long-term effects of sports-related brain trauma demands that we take proactive measures to protect our young athletes’ brains. The King–Devick Test is a simple and objective sideline screening test that can be administered by coaches, trainers and parents.” Some sports medicine doctors and trainers have called the King–Devick Test the “missing link” for practical sideline management of concussions due to its simplicity, objectivity and effectiveness.

Reading Solutions

The King–Devick Test for Reading is a screening tool for eye movement disorders related to reading performance and is available on a standardized, electronic testing platform. The King–Devick Test is useful for measuring eye movement performance, and may be used for in-school eye movement screenings. The test is scored based on a child’s age, speed and accuracy. During testing, the individual is instructed to read numbers from left-to-right, beginning at the top of the screen, as quickly and accurately as possible. The score is timed and errors are recorded. Percentile rank score reflects test performance based on age-matched normative data for ages 6 through 14.

In an investigation of the King–Devick Test as a screening tool for reading and academic performance, children attending New York Public schools were screened using the King–Devick Test and there was a significant correlation with their citywide achievement test scores and was significant for predicting those students in the lower 25% of the class for all grades.

Additionally, the King–Devick Test may be used as a measure of reading ability in adults.

Increased awareness of learning-related vision disorders in schools improves outcomes as saccadic eye movement deficiencies can be remediated with training and correspondingly reading performance can be enhanced. Performance on the King–Devick Test is related to reading performance for as young as 5 and 6 year olds in kindergarten.

King-Devick Reading Acceleration Program

The King–Devick Reading Acceleration Program (K-D RAP) is an eye movement training program directed at improving reading-related eye movement efficiency and accuracy. K-D RAP has been implemented in schools to train and improve the physical, motor aspect of reading with the goal of improving reading fluency and comprehension. In 2016, The Journal of Child Neurology published a study further investigating the effect of in-school saccadic training on reading performance. The treatment group had significantly greater improvement compared to the control group in fluency outcomes (6.2% vs. 3.6%) and comprehension (7.5% vs. 1.5%). A subgroup analysis was performed on high needs students, who were students with an active Individualized Education Plan (IEP) or in reading recovery programs. Overall, high- needs students went from 26th to 40th national percentile rank in reading fluency and from 40th to 56th in comprehension after RAP. Results supports the K-D Test, as an eye movement test used for reading screening as useful in predicting below-average reading performance. In 2014, Clinical Pediatrics journal published a study evaluating the effect of saccadic training using the King–Devick Reading Acceleration Program (K-D RAP) on reading fluency. Participants in kindergarten through 3rd grade received standardized reading fluency testing pre and post training. Training consisted of saccadic (eye movement) training using the K-D RAP 20 minutes per day, three days a week for six weeks. Researchers found that those who received saccadic training scored significantly higher in reading fluency measures after training. Also, their post training scores were significantly higher than the control group. The study concluded that saccadic training with the K-D RAP can significantly improve reading fluency. Follow-up testing demonstrated the improvement in reading performance for students who performed eye movement training, persisted in the next school year.

In 2016, a poster presented at the College of Vision Development’s Annual Meeting showcases a study on the effect of an in-school eye movement training program on students’ reading performance. 327 Students in 1st and 2nd grade were enrolled in 6 weeks of eye movement training using the K-D Reading Acceleration Program. Results showed the treatment group scored significantly higher in reading fluency and comprehension compared with the control group. In addition, high needs students, who were students with an active IEP or in reading recovery programs, went from 26th to 40th national percentile rank in reading fluency and from 40th to 56th in comprehension after RAP. The study demonstrates the importance of eye movement performance in reading and the need for consideration of eye movement training in schools’ reading curricula.

In 2015, Vision Development and Rehabilitation published a study describing the effect of K-D RAP on reading performance in 1st through 4th grade students. All students significantly improved in reading fluency following 6 weeks of in-school K-D RAP. Authors stated that, "the improvement may be attributed to the rigorous practice of eye movements (saccades) and shifts in visuospatial attention, which are necessary reading skills. This study supports implementation of K-D Remediation to improve reading performance in early grade levels."

At the 2014 College of Optometrists in Vision Development Annual Meeting, a study of high school students in 9th and 10th grades enrolled in a supplemental reading course, which included Scholastic’s Reading 180 system, K-D RAP, and placebo, who were later crossed-over into treatment. Each student underwent standardized reading fluency testing over three test periods. There was a significant improvement in reading fluency scores with the addition of K-D RAP to students’ existing reading intervention (7.54% vs. 3.59% improvement, p=0.03). The greatest improvement occurred in the cross-over group. K-D RAP significantly improved reading fluency in this group of high school students.

A poster at the American Optometric Association’s 2012 Annual Meeting, presented a study which showed the effect of the King-Devick Reading Acceleration Program for students in grades 2-4. The students were screened for reading inefficiency using the King–Devick Test (K-D Test) and in reading fluency using the Scholastic Fluency Test pre- and post-treatment. The control group had a mean-word improvement of 13.11 words as compared to a 30.02 mean word improvement in the treatment group (p = 0.0413). Subgroup analysis of grades 2 and 3 showed a mean word improvement of 31.94 among the treatment group as compared to 13.11 for the placebo group (p = 0.0267). Reading fluency measures significantly improved following eye movement training.

Alzheimer’s Disease

In 2016, the journal Alzheimer Disease and Associated Disorders published a study of the K-D Test conducted by researchers at the Alzheimer’s Disease Center at Boston University with collaborators from Harvard Medical School and New York University School of Medicine. Researchers administered the K-D test to 206 study participants, including 135 cognitively healthy individuals, 39 people with mild cognitive impairment (MCI), and 32 Alzheimer’s Disease (AD) dementia patients, and found the test could accurately distinguish the controls from the cognitively impaired individuals more than 90 percent of the time. The K-D performed equally well in detecting participants with MCI from controls as it did detecting the more advanced AD dementia patients from controls, providing evidence for its utility in screening for more subtle cognitive impairment. It also correlated strongly with lengthier, standardize neuropsychological tests. “Alarmingly, AD is underdiagnosed in nearly half of the American population and the brain changes of AD may begin up to 20 years before clinical symptoms. There is a need, therefore, for sensitive and readily available screening tools that can detect AD in its early stages (such as MCI), particularly as potential disease-modifying therapies become available,” explained corresponding author Robert Stern, PhD, Director of the Clinical Core of the BU ADC and professor of neurology, neurosurgery and anatomy and neurobiology. “If replicated in larger samples, our findings suggest that the K-D may be an appropriate screening test in fast-paced clinical settings, such as primary care physician offices, to assist in the early detection of cognitive impairment and guide referral for more comprehensive evaluation to ultimately facilitate early intervention,” Stern added.

Multiple Sclerosis

In 2012, neurologists from the University of Pennsylvania presented work examining the role of the K-D Test as a measure of eye movements in multiple sclerosis (MS). In the distinguished presentation, The King–Devick Test of Rapid Eye Movements: A Bedside Correlate of Disability and Quality of Life in Multiple Sclerosis the relationship of rapid eye movements, visual function, retinal structure, and vision-specific quality of life status was compared in a cohort of MS patients to a group of disease-free controls. K-D scores in the MS group were significantly higher (worse) compared to the disease-free control group. The K-D Test was shown to correlate well with binocular visual function, disability and vision-specific quality of life in MS. It was recommended that the K-D Test be considered for inclusion in future MS trials as a rapid efferent visual function test.

In 2013, the King–Devick Test was further studied in a larger cohort of patients with Multiple Sclerosis (MS) and presented at the Association for Research in Vision and Ophthalmology. The results show that the K-D Test captures visual dysfunction, vision specific quality of life and neurology impairment in MS. K-D scores reflected work disability as well as retinal structure changes as measured by optical coherence tomography (OCT). Additionally, history of optic neuritis and abnormal binocular visual acuity, both common ocular complications of MS, were associated with worse K-D scores suggesting that the K-D Test captures both afferent and efferent components of vision. In 2014, the study was published in the Journal of the Neurological Sciences. Journal of the Neurological Sciences

In 2014, Brain journal published a review of literature on clinical measures of vision for patients with MS. Since visual symptoms are a common manifestation of MS, sensitive tests which can detect and monitor subtle changes in visual status benefit both individuals with MS and doctors. The review states, “The King-Devick Test is a potential quantitative bedside performance measure of efferent visual dysfunction. K-D Test scores are higher (worse) among patients with multiple sclerosis compared to disease-free controls.”,

Parkinson's disease

In 2013, the King–Devick Test was studied in a Parkinson's disease (PD) cohort at the Arizona Parkinson's Disease Consortium and the Mayo Clinic. PD patients were compared to patients with Essential Tremor (ET) and disease-free controls. K–D scores were significantly higher (worse) for the PD group as compared to the ET group and the control group even after adjusting for age and sex. This showed that the K–D test may be a quick tool for quantifying visual and cognitive function in Parkinson's disease at bedside. The study was published in Parkinsonism & Related Disorders.

Amyotrophic Lateral Sclerosis (ALS)

In 2014, the American Academy of Neurology featured a study investigating how oxygen consumption during cognitive tasks varies in individuals with Amyotrophic Lateral Sclerosis (ALS). ALS and control subjects performed three cognitive tasks. Researchers utilized the King–Devick Test as a measure for evaluating the significance of functional near infrared spectroscopy of the brain for patients with ALS. K-D Test performance revealed increased oxygen consumption, suggesting that for ALS subjects the task is more difficult and requires more effort. Furthermore, K-D Test scores were significantly worse in the ALS group verses controls. The authors concluded that, "the K-D Test is a useful tool in evaluating visual-cognitive changes related to ALS." The results were published in 2014 in the Journal of Neuroscience and Neuroengineering.

Severe Sleep Deprivation Functionality

In April 2012, a study was published in Neurology investigating the effect of severe sleep deprivation on the speed and accuracy of eye movements as measured by the King–Devick Test. Neurology residents and staff from the University of Pennsylvania Health System underwent baseline K–D testing followed by post call K–D testing. The study concluded that the K–D test is sensitive to the effects of severe sleep deprivation on cognitive functioning, including rapid eye movements, concentration, and language function.

Hypoxia

In 2013, Mayo Clinic studied the King–Devick Test as a tool for the early detection of hypoxia-induced cognitive impairment. The performance of 25 subjects on the K–D test was measured in normoxic (normoxia) conditions followed by hypoxic (hypoxia) conditions (8% O2 equivalent to 7101 m) and then again in normoxia. K–D test completion time after exposure to 3 minutes of hypoxia was significantly longer than the Baseline Test (54.5 ± 12.4 s hypoxic vs. 46.3 ± 10.4 s baseline). Upon returning to normoxia the completion time was significantly shorter than in hypoxia (47.6 ± 10.6 s post-test vs. 54.5 ± 12.4 s hypoxic). There was no statistically significant difference between baseline test and post-test times, indicating that all subjects returned to their normoxic baseline levels. SpO2 decreased from 98 ± 0.9% to 80 ± 7.8% after 3 min on hypoxic gas. During the hypoxic K–D test, SpO2 decreased further to 75.8 ± 8.3%. In this study the K–D test has been shown to be an effective test to detect hypoxic impairment at early pre-symptomatic stages. The K–D test may also be used to afford a reassessment of traditional measures used to determine hypoxic reserve time. The study was published in Aviation, Space, and Environmental Medicine.

In October 2013, a Mayo Clinic press release quoted principal investigator Jan Stepanek, M.D., the Aerospace Medicine Program Director and Co-Director of the Aerospace Medicine & Vestibular Research Laboratory. "This study provides an objective indication of hypoxia that is involuntary, reliable and repeatable," Dr. Stepanek said. "This means that people can be tested for cognitive declines before having symptoms, because often people won't have symptoms until it is too late."

Eye movement testing has been recognized as an indicator of estimating changes in brain activity that reflect altered cognitive performance. A 2014 study published in “Aviation Space Environmental Medicine”, investigated oculometric tests as cognitive indicators of early signs of hypoxia. Results showed blink rates increased, pupil size fluctuations increased, higher fixation times, and worse King–Devick Test scores (46.3 s, 0.4 errors at baseline, 54.5 s, 1.6 errors at hypoxia) under hypoxic conditions. The authors concluded that, "the K-D Test measures saccadic function, which may be a reliable marker in neuro-physiological changes induced by hypoxia, and useful in assessing early signs of hypoxia prior to cognitive impairment."

Stroke

In 2014, Neurorehabilitation and Neural Repair published a study evaluating the success of visual scanning exercises after four weeks in patients with Unilateral Spatial Neglect following a stroke. Post-stroke patients with the visual-perceptual disorder were evaluated pre- and post-training. The King–Devick Test was used to evaluate saccadic eye movement function. There was a significant difference in K-D Test scores following training. The K-D Test provides a useful clinical measure for monitoring progress in patients with visual-perceptual dysfunction following a stroke.

Attention Deficit Hyperactivity Disorder

At the 2015 American Academy of Neurology Meeting, researchers presented a study exploring if the King–Devick Test, a measure of eye movements, attention, language, and visual processing, differed in children (ages 5–21) with Attention Deficit Hyperactivity Disorder (ADHD). Subjects with ADHD showed significantly worse K-D scores compared to the controls. The K-D Test demonstrated a greater capacity to distinguish ADHD vs. control groups in youths older than 11 years of age (ROC curve areas from logistic regression models was, 0.55 for youths ≤11 years of age and 0.79 for youths ≥11 years of age), which may be a result of variations in reading ability in the younger age group. Patients with ADHD took an average of 14 seconds longer to complete the K-D Test, compared to control youth (p<0.001, two-sample t-test). ADHD medication was not associated with differences in K-D scores within the cohort. Since ADHD is a neuro-development disorder and more than 50% of the brain is devoted to vision, the K-D Test highlights aspects of vision which may be affected by ADHD.

K-D Balance

K-D Balance is a clinical balance test and available as a software application for Apple iOS mobile devices. K-D Balance utilizes the built-in accelerometers to calculate a quantitative balance performance score. The device is worn around the subject’s neck during testing with the K-D Balance holder. K-D Balance instructs the test administrator step-by-step through the testing procedure for usability and consistency between test administrations.

In 2015 Concussion published a study comparing K-D Balance and modified Balance Error Scoring System (mBESS), a frequently utilized balance measure. The balance tests were performed simultaneously at pre-season by non-concussed, asymptomatic collegiate football players. Results demonstrated that mBESS error scores were highly variable, particularly the single-leg stance which accounted for 74% of the errors and 21% of athletes committing the maximum error score at baseline. There was no significant correlation between mBESS and K-D Balance measures which authors contributed to the ceiling effect of the mBESS maximum score. Authors concluded that objective measures may improve postural assessments in the setting of concussion.

Variable Contrast Sensitivity Chart by King-Devick

The Journal of Parkinson’s Disease published a study in 2014 that demonstrated how contrast visual acuity measures differ in individuals with Parkinson’s Disease (PD). Contrast acuity was measured with the King-Devick Variable Contrast Sensitivity Chart as an application on the iPad. PD patients had significantly worse low contrast visual acuity at near and far and worse high contrast acuity at far, compared to those without PD. The K-D Variable Contrast Sensitivity Chart provides a portable, quantitative, adjustable measure of contrast visual acuity, and may reveal undiagnosed visual impairment in patients with PD.

A study evaluating the King-Devick (K-D) Variable Contrast Sensitivity Chart among patients with Amyotrophic Lateral Sclerosis (ALS) was presented at the American Academy of Neurology 2015 Annual Meeting. The study compared the K-D Contrast Sensitivity Chart to the retro-illuminated Sloan chart and found that the charts were comparable in both high and low contrast acuity testing (88% high, 75% low). The K-D Contrast Acuity Chart demonstrated an accurate measurement of contrast acuity, with the benefit of portability, illumination, and availability compared to retro-illuminated charts.