An innovative technology, known as the Fusion Brain Assessment System, tracks eye movements in individuals and shows promise as an objective measure to diagnose and manage service members with concussions, and enhance force readiness, according to ongoing studies by researchers from the Defense and Veterans Brain Injury Center (DVBIC).
Diagnosing a concussion, also known as a mild traumatic brain injury, usually relies on a screening tool, such as the Military Acute Concussion Evaluation (MACE 2), used by the Department of Defense (DOD). These types of tools have a strong subjective element based on patient recall of past traumatic events.
By contrast, the Fusion technology is more objective by assessing eye reaction time that is often slower or more erratic for those who have experienced brain trauma. More than 400,000 active-duty service members have been diagnosed with TBI since 2000, according to figures from DVBIC.
“Through this program of research, we've developed and validated novel methods using eye tracking and measuring electrical brain signals to objectively measure effects of TBI on service members' cognitive, sensory and motor abilities,” said Mark Ettenhofer, a neuropsychologist at DVBIC’s Naval Medical Center San Diego research site in California, and one of the technology’s principal developers. DVBIC is the DOD’s traumatic brain injury center of excellence and a division of the Defense Health Agency Research and Development Directorate.
Ettenhofer and his colleagues tested eye movements to determine whether effects of brain injury among study participants would become more pronounced when performing more intellectually demanding tasks. All participants made eye movements as quickly as possible to look at circular images that appeared on a computer screen. As the tasks became more challenging, those with long-term effects from TBIs had greater difficulties than those without them. When combined with other tools, the eye-tracking system could help improve the accuracy of TBI diagnoses.
In the past, research psychologists have measured how quickly the brain processes visual images primarily by having subjects push a button in response. This requires the brain first to see the image, and then send a message to the finger to push the button.
“There is a lot that can happen between visual recognition of a signal [through images] and the pressing of a button,” said Army Major David Barry, a clinical psychologist and the co-inventor of the eye-tracker. He added, “If you are measuring how long it takes a person to look at something versus how long it takes a person to press a button, the eyes are always going to be faster and a more reliable indicator of neural activity.”
The Fusion technology has been used by TBI researchers at other institutions to assess a wide range of brain function. They have studied how TBI and PTSD affect the brain differently, how veterans’ brains changed over time during rehabilitation, and whether various therapies could improve cognition among military personnel and veterans with TBIs.
The DVBIC team in San Diego plans to further test the eye-tracking technology in a virtual reality setting. Participants would complete military-related tasks, such as walking and shooting, while in an immersive 3-D environment. Simultaneously, their eye movements, accuracy, and brain activities would be measured. Subjects with concussions would be compared to others who had not sustained TBIs to develop an objective measure of recovery. Researchers hope to develop tools that military commanders can use in the field to predict whether a service member is ready to return to duty or requires additional rest.
“Our goal is to use this technology to detect TBI-related problems earlier and more accurately, and to be able to track recovery over time to help injured service members return to duty when they're ready,” Ettenhofer said.