During the first week of last September, a group of big wave surfers sponsored by Red Bull took over a stretch of beach on the Pacific coast of Mexico. They were there for a series of exotic-sounding tests, from having their brain activity read as they chose waves, to riding on 3D-printed surf boards.

When Red Bull invited neuroscientist David Putrino to join the study, he was intrigued, but didn't see enough value to warrant taking a week off from his day job at the Burke Medical Research Institute in White Plains, New York, where he is the director of telemedicine and virtual rehabilitation. In fact, Putrino only agreed to join on one condition: the excursion had to add experiments that would eventually help the general public.

What if, Putrino wondered, the group took all of the high-tech devices they were using to test the brains of surfers and figured out a way to better protect those brains? Specifically, he wanted to see if they could use the technology to create a portable concussion-testing device.

Just like that, the pristine beaches of Salina Cruz, Oaxaca, became the testing grounds for technology that could, at long last, change the way athletes are evaluated immediately following a possible concussion.

The Centers for Disease Control and Prevention reported in 2006 that there are an estimated 1.6 million to 3.8 million sports and recreation-related concussions each year. The earlier a concussion is spotted, the better the chance of mitigating long-term damage—only the CDC also found that many go undetected, because current testing methods are too rudimentary. Advanced tests exist, but they require large medical devices that could never be used on the sideline at a game.

With more sensitive and smaller, more affordable electronic testing, Putrino and others hope to significantly increase the detection rate.

One of the challenges in developing these tests, though, is that there is no definitive biological metric or neurological sign that a person has sustained a concussion. Several startups and established companies have also promised quick sideline and in-game concussion detection methods, from mouth guards to helmets that light up when an athlete takes a particularly forceful hit, but these miss the mark because there isn't an accepted benchmark, like the force or speed of a hit, that can predict if a concussion will result.

A concussion can be the result of one hit or many, with the damage building up over the course of several hits, also known as sub-concussive blows. A study of concussions diagnosed in college athletes in 2012 found that a third were not related to a specific hit. In addition, every brain reacts differently to sudden acceleration and deceleration, and a hit that leaves one football player concussed can have no apparent effect on another.

The key to concussion recognition, then, is the change in individual brain function. At Burke, Putrino and colleagues were already using eye-tracking technology to test the neurological function of stroke patients. "It requires many parts of the brain in order to produce accurate eye movements," says Burke neurologist Jason Carmel. If any of these parts of the brain are impacted, the changes will show in the eye movements.

Putrino concluded that in Mexico, he could apply the same technology to concussion detection.

"A concussion is not localized to one part of the brain like with a stroke," he says. "It affects many different parts of the brain, so if you can use a distributed function like eye movements, attention, perception, then I think you have a better chance of picking up the subtle signs of concussion.

"[The eye-tracker] is tracking smooth pursuit. When you're hit in the head, that's one of the first things you lose. You can't coordinate eye movements."

Research has long shown this connection between the visual system and concussions—the King-Devick concussion test, designed in 1976, requires reading numbers on a sheet of paper while being timed by a stopwatch—yet a recent review article found that eye tests are rarely performed on sports sidelines. This could be because not enough coaches and trainers are licensed to administer the tests, and not all schools have a medical professional on the sidelines. It could also be that existing tests are easy enough for athletes to sandbag, the better to stay on the field despite suffering concussions.

Athletes take the King-Devick test before the season starts, for baseline measurements, then repeat the test after a hit. Studies show that athletes sometimes intentionally botch the baseline measurements by reading slowly, so that there isn't as much of a difference in function after a hit.

It's nearly impossible to fake electronic eye-tracking tests, because a highly sensitive electronic device reads the results, rather than a coach, parent, or physician. The question is how to make electronic eye-tracking systems both portable and affordable enough to be available on the sidelines. Putrino's team toyed with several options before he left for Mexico. Eventually, they decided to try mounting eye-tracking technology from SensoMotoric Instruments (SMI)—a medical and commercial research company—onto an Oculus Rift virtual reality headset.

Taking the test is simple: wearing the headset, athletes track a small dot across the screen. As their eyes move, the SMI technology reads how their pupils respond to light and the speed of the movement. They're also shown a series of dots, and the SMI tracks how quickly they are able to focus on them. Baseline results are compared to post-hit results, and any change indicates a concussion or pre-concussion symptoms.

Mounting SMI in an Oculus Rift allows researchers to test for a second marker: balance. Concussions cause a change in balance that is sometimes too minute for a physician to detect, but hard for the Oculus Rift to miss.

"[The headset] has a sensitive accelerometer gyroscope in it," Putrino explains. "That's how it knows to change the scene of what you're looking at [when playing a virtual reality game]. So what we're really doing is we're repurposing that, to give us information on how much the person is swaying in space."

The person administering the test can also do things like tip the virtual reality scene that is being shown in the headset. If the athlete doesn't think the scene is askew, it's an indication that his or her balance is off.

The current test for balance is asking a person to close their eyes, blocking out light, which helps with balance, and stand with their feet together. Athletes trying to hide their concussions can fool this test, by either slightly opening one eye or not keeping their feet close enough together. But there's no faking it when wearing an Oculus Rift, which blocks outside light.

Putrino and other scientists brought in by Red Bull spent the week in Mexico testing out the hardware. They wanted to know if the Oculus Rift and SMI could withstand extreme conditions, like constant exposure to sand and salt water, and could be used repeatedly in a short period of time.

"It was basically play time," says Putrino, adding that none of the surfers actually sustained a concussion that week. The system held up well, and upon returning, Putrino reported his findings to his colleagues at Burke. They have since been tinkering with the technology to cut the costs as much as possible, as well as setting up a clinical trial.

Researchers at the Stanford Concussion and Brain Performance Center and at Indiana University are separately developing similar eye-tracking systems. According to a recent article in Stanford Magazine, Stanford clinical professor of neurosurgery Jamshid Ghajar has found that modified VR gaming goggles are sensitive enough to notice the difference between a concussion and sleep deprivation. His team will be testing the method with Stanford athletes in the coming months. Meanwhile, Indiana's Nicholas Port and Steven A. Hitzeman have been using eye-tracking to measure concussions in a pilot study with the school's men's football and soccer teams and the women's soccer team since 2013.

New York University's Langone Medical Center recently heralded the King-Devick eye test as a useful diagnostic tool. Their next step? Test an electronic eye tracker.

The system Putrino and his colleagues plan to introduce to the public will be different than the one used in Mexico. They won't be adding SMI technology to the Oculus Rift, because the cost—about $19,000—is prohibitive. Instead, they're using a combination of a desktop or tablet computer, an Oculus Rift, and a less expensive eye-tracking device. They've tried the Tobii EyeX, the Tobii Rex, and the Eye Tribe so far. These are similar to SMI, with athletes tracking a dot across the screen, and each lasts about five minutes.

It will cost about $1,000 to collect the parts ($300 for the Oculus Rift, $150 for the Tobii EyeX, and the cost of a tablet or computer). The computer or tablet would be set up in the arena or somewhere very close to the field—as long as it is indoors—with the eye-tracker mounted along the bottom of the desktop screen. The Oculus Rift is being used separately, to measure balance.

Athletes would do baseline testing at the beginning of the season. Then, after a big hit or if a coach, trainer or teammate suspects they've suffered a concussion, they'd go to the testing station. After 10-15 minutes of eye and balance testing, a physician, EMT, or certified trainer would analyze the results and determine if the athletes should seek further medical attention. The system doesn't take away the job of the clinician, but it would give them more accurate metrics on which to base their decision.

"I think this has the potential to be the most sensitive thing that we have," Putrino says.

Because the system is so sensitive, it even may be able to detect concussions that doctors or trainers often miss, coming from those aforementioned sub-concussive blows. "Right now what we do to test the concussion is so poor," Putrino says. With sub-concussive blows, "it may be you have symptoms of a concussion that are not being picked up by insensitive techniques. We may even start to redefine what we are calling sub-concussive."

The Burke neurologists will test the system this summer in a clinical trial with an Australian rugby team, comparing the results with the results of individual DTI (diffusor tensor imaging) scans. DTIs are a type of MRI that indicates if axons in the brain--basically, the signaling wires between nerve cells--have been damaged. Studies in 2010 and 2011 showed that DTI exams are one of the best ways to detect concussions and brain injury. The tests must be performed at a hospital or other properly licensed facility because they require an MRI machine. They are still considered state-of-the-art and have yet to be offered on a wide scale basis. If the new Burke system detects concussions at rates similar to the DTI, Putrino and his colleagues will know that it is valid.

The clinical trial in Australia will be followed by smaller studies with youth teams in the U.S. Hosting these concurrently should speed up the pace of the research and data collection. From there, it will have to go through FDA approval, and, Putrino hopes, spark an overall change in policy. He'd like to see the entire country follow New York City's lead in requiring that a qualified medical professional—either an EMT, physician or athletic trainer—be present at every high school game played. Burke would license these professionals to use the software associated with the institute's system, or any eye-tracking system that would help detect concussions earlier and more often.

The technology is still very much in the early stages, just as it is at Stanford and Indiana University, but the science behind it has been trusted for years. Eye-tracking is a valid way to test neurological function, and therefore concussion symptoms. Size and cost have been limiting factors, but if Putrino and others are right, that may change in the near future.

"People deserve a better standard of care if they're playing a competitive sport," Putrino says. "If they injure themselves while playing, they have a right to receive an informative, objective assessment. They deserve to be seated at a computer and have a quantitative evaluation done. Especially since we have the technology to provide it now at extremely low cost. No football club or rugby club is going to go bankrupt paying $1,000 for a setup. It's the standard of care that people deserve."