Using a tool designed at NYU Langone Medical Center, researchers there enlisted 169 veterans, 157 of whom were healthy. The remaining 12 had known weaknesses in the nerves that move the eyes up and down and side to side, or brain swelling adjacent to those nerves.
All the participants were asked to watch either a music video or TV for 3 and 1/2 minutes. In the healthy subjects the ratio of horizontal to vertical eye movements was close to one-to-one. In the dozen with known weakness or swelling in the nerves that control eye movement, the ratio was significantly skewed depending on the affected nerve. In each case, scientists were able to use the quantitative measurement to pinpoint the location of the injury or weakness.
"One of the reasons that clinical trials for treatment of brain injury have failed in the past is that brain injury is hard to classify and quantitate with existing technologies," said Uzma Samadani, co-director of the Steven & Alexandra Cohen Veterans Center for the Study of Post-Traumatic Stress and Brain Injury at NYU Langone, in a news release Tuesday. "This invention suggests a potential new method for classifying and quantitating the extent of injury. Once validated, it will both accelerate diagnosis and aid in the development of better treatments."
Though the participants in the clinical trial all had abnormal brain scans, the study suggests the eye-tracking test might be best used in diagnosing injuries, such as concussions, which often evade detection with traditional brain imaging.
Brain injury is the leading cause of death and disability in Americans under the age of 35, according to the Centers for Disease Control and Prevention. The simplicity of the eye-tracking tool means the test could become a critical aid in triage of the 1.4 million people who suffer a traumatic brain injury in the United States every year.
"When a person falls and hits their head, it can be difficult to determine whether the injury is life-threatening," Samadani said. "Eye tracking is potentially a simple, non-invasive and cost-effective way to determine quickly which patients need immediate attention."