King-Devick Test Follow Up: Science vs. Media

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Claudia Percifield, MS, ATC

The King-Devick Test for Concussion Evaluation has quickly been gaining popularity in the news.  A simple Google search for King-Devick Test will pull up pages upon pages of articles and blogs written just in the month of August alone.

Initially, media outlets were calling for it to be the answer to concussion testing. They sensationalized the speed and ease with which it could be administered, stated minimal training is involved in administering the test and boasted about the percentage of concussions it could correctly diagnose.  As a healthcare professional taught to critically evaluate research and not take things at face value, I was extremely skeptical.

My first thought was, “Would we as clinicians throw out every special test we had used for decades to evaluate ankle sprains if someone wrote a few news articles about 1 new quick test that could replace all ankle tests currently in practice?” This thought led to my first post, which can be found here.

News articles focused on promoting it as the test rather than as an additional resource. They promoted the use in situations where no Athletic Trainer may be present, while inferring those administering the test would in fact be diagnosing the test.  All of these things concerned me.

After my initial post, I was contacted by Danielle Leong, OD, FAAO, Senior Director of Research with King-Devick Test to discuss my article.  In light of our conversation, I was inspired to debunk myths and shine light on what may be a more scientific way to look at the test and the current research.  Leong spent time explaining from a neurological perspective the multiple cortexes the King-Devick Test evaluates during the exam, in addition to hitting the cerebellum and brain stem.

This test was previously used on military patients with traumatic brain injury (TBI). In this research, testers microscopically examined their patients’ eye movements and saw abnormalities in the movement patterns, leading to further research.  The size of the numbers used in testing are at a 20/100 level, minimizing the effect that not wearing corrective lenses could have on the exam.

Leong was quick to mention that while the King-Devick Test is able to be administered quickly and easily with minimal training, it is meant to be a screening tool, not a standalone resource for diagnosing concussion. She said non-healthcare professionals administering the test (especially in youth sports), should immediately remove these athletes from play and refer them to the appropriate healthcare professional for further evaluation, NOT diagnose these athletes as having a concussion.

Most notable to me, she cited a University of Florida study1 that examined the percentages of concussions captured using the King-Devick Test alone (79%); a modified SCAT3 that included the SAC, symptom checklist and the BESS alone (50%); and encompassing all testing (100%).  This study most directly addresses the call to incorporate both exams into our sideline arsenal to protect our athletes. Again, it’s one retrospective research study, but it is one with compelling results. Out of everything I’ve read and heard in researching for both of my posts, this is what stood out to me the most.  This is what calls me clinically to evaluate my methods of examination for concussion as I go forward in my clinical practice.

Science vs. Media. It’s a powerful thing these days; they can paint 2 different pictures.


1 Marinides Z, Galetta KM, Andrews CN, et al. Vision Testing is Additive to the Sideline Assessment of Sports-Related Concussion. Neurology: Clinical Practice. July 2014.

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