A study from researchers at the CU Anschutz Marcus Institute for Brain Health suggests that veterans with concussions may continue to show subtle but measurable brain function differences more than a decade after their injury. Researchers found these differences can be detected through specialized eye movement testing.
The findings were recently published in the Journal of Neuro-Ophthalmology .
Mild traumatic brain injuries are common among military service members and occur in athletes and civilians through sports impacts, car accidents and falls. While most individuals recover within weeks or months, the new research indicates that some may experience lingering changes in attention, processing speed and impulse control long after symptoms appear to resolve.
Eye Movements Reveal Subtle Brain Changes
"The eyes are directly connected to brain networks that control attention, information processing and decision-making," said the study's lead investigator Jeffrey Hebert, PhD, PT , associate professor at the CU Anschutz School of Medicine and director of research for the CU Anschutz Marcus Institute for Brain Health. "By studying how someone's eyes move during a cognitively demanding task, we can detect subtle brain changes that might not appear on a standard bedside exam or brain scan."
The study evaluated 78 military veterans, including 38 with a history of mild traumatic brain injury and 40 without. Participants completed a series of eye movement tasks and cognitive tests designed to measure executive function of attention, processing speed and self-control.
Researchers found that veterans with prior concussions were more likely to demonstrate slower and less accurate eye movements along with reduced performance on certain attention-based tasks. Some of these differences were still measurable more than 10 years after the original injury.
Hebert said eye movements rely on complex networks across multiple regions of the brain. Tasks that require individuals to quickly look away from a visual target and tasks that require rapid visual recognition and verbalization of a viewed object test not only visual function but also cognitive control. This includes the ability to focus, suppress impulses and respond quickly and accurately. Because these processes depend on widespread neural connections, several mild injuries may leave lasting but difficult to detect effects.
"Even when someone feels recovered, their brain may still be working differently behind the scenes, especially during visually demanding tasks and in busy environments" Hebert said. "Objective eye movement testing gives us a measurable way to assess these often covert problems."
Implications for Concussion Care
The findings could have important implications for long term concussion care.
"Standard imaging tools such as MRI scans often appear normal after mild brain injury, making persistent symptoms difficult to verify objectively," Hebert said. "Cognitively challenging eye movement assessments may provide clinicians with an additional tool to better understand ongoing cognitive concerns and more precisely tailor rehabilitation strategies.
Although the study focused on military veterans, the results may apply more broadly to athletes, first responders and civilians who have experienced concussions.
The team emphasizes that most individuals recover well from mild traumatic brain injury. However, identifying those who continue to experience subtle effects could improve follow up care, long term monitoring and treatment planning optimizing healthier brain adaptation.
Future studies will explore whether incorporating cognitively challenging eye movement testing into routine concussion evaluations could help clinicians better identify traumatic brain injury, track recovery and guide treatment decisions.
The research was funded by the Congressionally Directed Medical Research Programs, U.S. Army Medical Research Acquisition Activity, Department of Defense, Vision Research Program Award.
