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Eye tracking may help quantify concussion, brain injury severity

Eye tracking may help quantify concussion, brain injury severity

J Neurotrauma. 2015; Epub ahead of print. doi: 10.1089/neu.2014.3687.

February 3, 2015

When someone suffers a brain injury, it affects the speed of eye movements when reading and the ability to absorb the information read.  In our office we have long used the ReadAlyzer, a highly sophisticated eye tracking device that measures eye movements while reading.  Using age appropriate reading passages, we can determine the number of words read per minute and the efficiency of reading.  This includes the number of fixations, regressions, fixation duration, and grade level equivalence.

  • A fixation is the number of times the eyes move when reading a sentence, for example, can you read a 3 word phrase in one glance or do you have to read each word individually.  Can you bring in the word “individually” in one glance, or do you have to read it as "in-div-id-ually", meaning 4 glances.
  • A regression means the number of times your eyes shift back and re-read the same material.
  • Fixation duration means the amount of time someone “sits” on each word or phrase.
  • It also evaluated the number of words someone read per minute, and ultimately determines the grade level that person reads at.

New technology may help measure ocular motility dysfunction associated with brain injury and concussion, according to a study in the Journal of Neurotrauma.

Samadani and colleagues developed a novel eye movement tracking algorithm to assess its efficacy in identifying the disconjugate gaze associated with concussion and structural brain injury.

Researchers conducted a prospective study of 75 trauma participants and 64 healthy non-injured control subjects who were between 18 and 60 years old. All participants watched a video while researchers tracked and compared the coordinates of both pupils. Researchers compared the tracking measurements of the trauma patients to Sport Concussion Assessment Tool – 3rd Edition (SCAT3) measurements and, if applicable, CT results.

Results showed that the severity of disconjugacy (the difficulty of the eye to move together as a unit) was correlated with the severity of concussive symptoms in all trauma patients. Additionally, trauma patients who had hit their heads and had CT scans that showed new brain damage or had normal CT scans showed significantly greater oculomotor disruption than the control subjects.

"Concussion is a condition that has been plagued by lack of clear definition and diagnostic," the authors concluded. "Establishment of eye tracking as an objective measure would enable testing of prophylactic devices for concussion (e.g., helmets) as well as of therapeutics. It would potentially enable informed decision making regarding return to baseline activity or sport play. In conjunction with devices such as accelerometers and other helmet sensors, eye tracking could be used to identify which impacts render the most disruptive blows and, thus, should be eliminated by ruling."