Accumulating evidence on the long-term damage of repeated concussive injuries is strengthening the need for pitch-side recognition and immediate removal of players from the arena of play if a concussion is suspected. However, current guidelines fall short of providing any practical guidance for the withdrawal of a player to seek further clinical assessment, and the letter of these are not adhered to in many cases.1The Lancet NeurologyTime for a gamechanger in the management of concussion.Lancet Neurol. 2013; 12: 415Summary Full Text Full Text PDF PubMed Scopus (1) Google Scholar, 2The Lancet NeurologyTackling the sports-related concussion crisis.Lancet Neurol. 2014; 13: 747Summary Full Text Full Text PDF PubMed Scopus (5) Google Scholar As more than half of pathways in the brain are involved in visual processing, these systems are particularly susceptible to the effects of traumatic brain injury; therefore, tests that evaluate the integrity of the visual systems provide a potentially useful surrogate to screen for and monitor the effects of concussion.3Ventura RE Balcer LJ Galetta AL The neuro-ophthalmology of head trauma.Lancet Neurol. 2014; 13: 1006-1016Summary Full Text Full Text PDF Scopus (128) Google Scholar The King-Devick (K-D) test has been used in this context in several sports, including rugby, boxing, mixed martial arts, American football, soccer, basketball, and ice hockey.4King D Brughelli M Hume P Gissane C Assessment, management and knowledge of sport-related concussion: systematic review.Sports Med. 2014; 44: 449-471Crossref PubMed Scopus (83) Google Scholar It was first developed to investigate the relation between poor oculomotor function and learning disabilities.4King D Brughelli M Hume P Gissane C Assessment, management and knowledge of sport-related concussion: systematic review.Sports Med. 2014; 44: 449-471Crossref PubMed Scopus (83) Google Scholar The time taken to correctly read out numbers on cards, which progressively become more difficult to read in a flowing manner, measures alterations in saccades, attention, concentration, speech and language, and other correlates of brain function. In the sporting context, any increase in the time taken to complete the test from a predetermined baseline might indicate a concussive event requiring immediate withdrawal from play and referral for medical evaluation. The K-D test can be done in minutes and does not necessarily need to be administered by medically trained personnel;5Leong DF Balcer LJ Galetta SL Liu Z Master CL The King-Devick test as a concussion screening tool administered by sports parents.J Sports Med Phys Fit. 2014; 54: 70-77PubMed Google Scholar however, it is only one of several potential tests, and further validation—in longitudinal studies and in cohorts of different ages—is required before we know if it is generalisable in different populations and could form part of assessment strategies for a wider range of sports.