“It’s about that Jell-O within that cranium,” says Dennis Cardone, an associate professor of orthopedic surgery at Langone Medical Center, and co-director of NYU’s Concussion Center. “How it moves around, and how it collides with the cranium itself.” Because a significant proportion of our brains is used to process visual information, many of the symptoms that can be used to diagnose concussions affect vision. Cardone uses a screening test called the King-Devick test, which was developed in 1976 to measure deficiencies in eye movement during reading.