About King-Devick Test

The King–Devick Test (K–D Test) is defined by Mosby’s Medical Dictionary as a tool for evaluation of saccade, consisting of a series of test cards of numbers. The test cards become progressively more difficult to read due to variability of spacing between the numbers. Both errors in reading and speed of reading are included in deriving a score. Saccades are quick, simultaneous movements of both eyes.

The King–Devick Test was developed in 1976 by Alan King, O.D. and Steven Devick, O.D. as an indicator of saccadic performance as it relates to reading ability. In 1983, a sample of 1202 children ages six to fourteen was screened using the K–D Test. The study done by the State University of New York (SUNY) concluded that the test was quick and easy to score and could be administered by non-eye care practitioners. For more than 30 years, the King–Devick Test has been a proven indicator of oculomotor inefficiencies regarding eye movements during reading. The King–Devick Test (K–D Test) is utilized as a tool in schools, eye care and psychologist offices to help detect learning disabilities, including dyslexia.

As defined in Dorland's Medical Dictionary, 31st Edition and Mosby’s Medical Dictionary, 8th Edition:King-Devick Test /kingdev’ik/: a tool for evaluation of saccade, consisting of a series of charts of numbers. The charts become progressively more difficult to read in a flowing manner because of increasingly more difficult spacing between the numbers. Both errors in reading and speed of reading are included in deriving a score. Developed by Drs. King and Devick-1976.


In 2011, researchers from the University of Pennsylvania Perelman School of Medicine published a study in Neurology 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.

Since the Neurology study was published in early 2011, there have been over 50 peer-reviewed studies published supporting King-Devick Test as a quick, objective indicator of suboptimal brain function and correlates with indicators of neurological conditions such as: concussion, reading disabilities, hypoxia, multiple sclerosis, Parkinson’s disease, and extreme sleep deprivation.

How King-Devick Test Works

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The King-Devick Test is an objective, physical method of evaluating visual tracking and saccadic eye movements. King-Devick Test is based on the time to perform rapid number naming. It involves reading aloud a series of single digit numbers from left to right on three test cards. Participants are asked to read the numbers on each card from left to right as quickly as possible but without making any errors. The sum of the three test card time scores constitutes the summary score for the entire test.