Researchers at the University of Nevada recently tracked the eye movement of athletes in different sports to learn how head impacts that don’t meet the criteria for concussions may still harm the brain.
According to a university release, Nicholas Murray, an associate professor in the School of Public Health and director of the Neuromechanics Laboratory, was curious how slow eye movements, called smooth pursuits, would be affected by repetitive head impacts. A key aspect of athletics is knowing where to look next, which is related to smooth pursuit velocity.
“Talented athletes have superior eye movements and ability to look ahead, especially for sports like football where the athletes have trained on a specific drill and can anticipate what will happen next,” said Murray, who collaborated with Marian Berryhill, a cognitive neuroscientist and professor in the College of Science’s Department of Psychology, and their findings were recently published in JAMA Ophthalmology.
Murray specifically wanted to investigate repeated head impacts, a technical term for impacts that do not meet the clinical threshold for a concussion. He collaborated with Berryhill, whose research area includes studying eye movement, because postural stability and eye movement are the two most sensitive measures of potential injury to the brain after a head impact, the release states.
The study compared eye-tracking at the beginning of the season for athletes in a contact sport (football) and in a non-contact sport (swimming) to their eye-tracking again at the end of the season. Football players were divided into high-dose groups and low-dose groups depending on how many hits they were expected to take depending on the position they played. Repeated head impacts were recorded with custom mouth guards the athletes had to wear for a season.
The study showed there were no significant differences between the non-contact athletes and the low- and high-dose football players in their smooth pursuit eye movements at the end of the season, though the high-dose athletes did experience a decline. The scientists said this isn’t surprising, partially because the low- and high-dose athletes are constantly working on improving their smooth pursuit velocity by drilling football plays.
“Despite the fact that they probably have more exposure to that training, they’re still seeing a decline by the end of the season,” Berryhill said.
Murray admitted this study merely scratches the surface. He hopes to develop a model for understanding what impacts athletes can withstand without injury, obvious or not.
“Then, take that model and move it out of the college space and go down to Pop Warner, go down to high school, go to the actual largest stakeholder population for contact sports in the world,” he said.
The effects of receiving an impact can vary heavily based on all sorts of variables, like neck strength, neck height, torsion, age, hormones and more. With the current available data, coming up with a standard rule for what happens after a player takes a hit is impossible.
“You need oceans of data to make those little simple rules,” Berryhill said. “And so, it's contingent upon access, funding, time and having a good array of players in different sports.”
Murray said these initial results may ease the fears of football players and their parents.
“Hitting your head is bad, but we're also not eggshells,” Berryhill added.
