For much of this fall, as in falls past, a Friday night crowd comes out for the weekly football game and likely witnesses the star running back getting rattled by a hard tackle. The coach faces a decision: keep the player in the game and risk serious head injury or pull him and face the wrath of the player, the team and the crowd. What the coach needs is a way to accurately assess the player’s status – right now.

This scenario is being played out at sports fields around the world. How do we make objective decisions about a player’s health in the heat of competition?

The problem intrigues UC Davis physician Khizer Khaderi. A neuro-ophthalmologist, Khaderi is applying his expertise in the eye-brain connection to investigate traumatic brain injury (TBI). Whether the result of a car accident, explosion, skiing or a tackle, TBI can affect vision, memory and even mental health.

Imperfect solutions

Khaderi and colleagues are developing a system that will take the guesswork out of assessing an on-field concussion, an early form of TBI.

It would replace a system of neurocognitive tests that many teams use now. In these tests, a player is asked a number of questions, of which answers are compared to baseline results recorded earlier. However, with players’ strong incentive to stay in the game, some have learned to circumvent the system.

“One of the problems with the neurocognitive approach is that it’s very subjective,” says Khaderi, an assistant professor of Clinical Ophthalmology and head of the Sports Vision Lab. “Players will intentionally do poorly on the baseline test, so if they do get injured, it won’t look as severe.”

Khaderi’s solution focuses on the eyes. A third of the brain is devoted to the visual system, making the eyes an ideal window on brain health. Several biometric tests exist but Khaderi’s team has found that relying on three established biometric tests greatly increases the chances of accurately assessing TBI risk on the field in real time.

Eyes, pupils and brain waves

Using eye movements to assess TBI has advantages. For example, researchers have measured how long the eye takes to move from a central to peripheral focus. This would be the motion a driver would make when shifting attention from the road to a child crossing it. This motion takes less than seven-tenths of a second for a healthy person, but much longer for those who’ve experienced a brain injury.

The opposite motion is also informative. In the same scenario, the driver could make the decision to look away from the child stepping into the road.

“The natural reaction is to look at the child,” says Khaderi, “but instead you look away. This involves cognition, so it’s a good measure of executive function.”

Pupil function can also measure an injury’s severity. A coach could use a flashlight to assess dilation, but background light can skew results. To combat this, Khaderi has adopted a psychological method called the International Affective Picture System, which uses pictures to make the pupil respond.

The third metric measures brain waves. When they’re awake, people generally have a higher ratio of fast alpha waves to slow theta waves. However, that ratio is reversed after a brain injury. High theta waves indicate a dreamy state of mind.

Moving forward

Khaderi plans to bring these tools to playing fields everywhere. Fortunately, much of this technology is being used for other purposes and can be repurposed for TBI detection.

“Our goal is to create a platform that integrates commercially available eye tracking hardware and EEG (brain wave) systems,” says Khaderi.

The group has found a development partner and is working with the UC Davis athletic department to set up clinical trials. The ultimate goal is to create a system that could be accessed through a tablet computer or other device.

“These injuries don’t just strike kids who are playing sports, but anyone who leads an active life,” says Khaderi. “Our brains are precious and we need to do all we can to protect them.”