Hi I'm Anderson Schrader and today I'll be talking about the paper that I worked on with the rest of our team listed here entitled "Toward Eye-Tracked Sideline Concussion Assessment in eXtended Reality."
This project was funded by the RHB Sports Science Institute at Clemson University.
And this was done in collaboration with SWPS University in Poland doing biostatistics, University of Missouri assisting with creating the stimulus in Unity 3D, and 6D Simulations which aided in translating the work to the HoloLens2.
Recently there's been increasing public interest in sports concussions. This stemmed from the movie "Concussion" that was released in 2015 in addition to growing knowledge of the long term effects of mild traumatic brain injury or mTBI.
The gaining interest is valid because of the high prevalence of concussions that occur in sports.
As shown in the figure to the right provided by the NCAA, concussions occur widely in a variety of sports, not only football, showing that nearly any athlete is at risk of concussion when playing their sport.
The need for a new diagnostic tool arises since they're currently no available, portable, visuomotor assessments of concussions that are made specifically for the sidelines.
The typical method that's used on the sidelines currently are paper forms which diagnose based on self reported symptoms, so there's a need for a test that will use objective diagnostic biomarkers.
Lastly, this fits into a broader range of concussion management processes, including education, diagnosis, recovery, and return to sport.
There's a lot of international interest on this topic, for example, the photo shown here is from a conference in Berlin, which determined the consensus statement on concussion in sports and a concussion is briefly defined as a traumatic brain injury induced by biomechanical forces.
Now we'll dive in a little deeper into what the problems are with the current methods of diagnosing. The first point is that many of the current methods are too subjective.
There are several different paper forms that ask athletes or patients to report their symptoms, such as the SAC, SCAT and PCSS.
These are frequently falsified due to an athlete just wanting to be able to return to play as quickly as possible.
There are some software based diagnosing tools which record reaction time and memory, such as the ImPACT, but these are also tricked by athletes who underperform at the baseline so that, once a concussion happens, they won't be as far off of their baseline and can then return to play.
Moving away from paper test we have the vestibular ocular motor assessment, and this is the one that's more commonly associated with the doctor's office and is that follow my finger tests that many of us have experienced.
This can also be subjective from the perspective of the doctor because it relies on their ability to see irregular eye movements, and not all doctors are able to detect the most minute irregularities.
Eye tracking has been shown to be an effective proxy for assessing neural deficits that are associated with brain injuries and a now there are a few companies using eye tracking as a means to objectively diagnose concussion or impairments.
The first is Oculogica with their device the EyeBOX, this is the only device FDA cleared to aid in concussion diagnosis, but is a very large tabletop setup that's impractical for use directly on the sidelines.
To the right of that we have Right Eye with the EyeQ suite. This device is still a table top display, although slightly smaller.
However, it is only indicated to show eye movement impairments, not specifically for concussion. Down from that we have the I-PAS made by Neuro-Kinetics.
It is closer to an ideal sideline device with a head mounted display, but it is still tethered to a computer.
It's also a VR headset which makes it fully immersive, and immersive headsets are known to cause dizziness and disorientation for some users, which can be especially harmful for someone who just sustained a head injury.
Then, lastly, we have Eye Sync by SyncThink, which is a cordless head mounted display but, again, it is fully immersive which is not ideal for head injury patients.
Our work is primarily based on the work that was done by Maruta et al. in 2013, '14 and '18.
The work that they did was implementing predictive visual tracking for an orbital target. They described a circular test stimulus that we have incorporated into our display.
Our work built on this by implementing many of their metrics into VR and AR and we're also incorporating baseline related metrics that will determine local and global error.
In our study we started with the HTC Vive Pro Eye VR headset that is headlocked, fully immersive, and must be tethered to a computer.
This was driven by Unity 3D for proof of concept testing in a pilot study. From there, we made a switch to the HoloLens2 AR headset.
And the benefits of eventually switching to this hardware, is that the user can see their surroundings, which limits motion sickness.
It's also cordless, which makes it ideal for the sidelines, and it has the capability of making personalized profiles which can store each individual athletes baseline.
There were 13 participants in the study with six female, six male, and one non-binary. The average age was 23.7 and average interpupillary distance was 63.12.
Each participant read the information letter and familiarized themselves with the equipment prior to testing.
Each subject donned the headset and calibrated it to their eye positioning. Then they recorded a baseline for two different stimuli.
After that, the subject spun themselves 10 times until they were dizzy and then recorded again for each stimuli.
The eye movements that are experienced after rotation are very similar to those observed post concussion and last throughout the duration of the concussion.
This was a modified two by two within subjects design with the stimulus and rotary test block as fixed factors. We counterbalanced the stimulus, but we always recorded baseline before post-rotary recording.
There were two stimuli that were tested on each patient: a circular orbit and a horizontal pendulum.
The circular path has been used in other eye tracking devices to gauge impairments, because it can detect problems in both the vertical and horizontal directions, as was described by Maruta.
The pendulum path is especially important because it mimics the vestibular ocular motor screening that's already clinically used.
The display extends to 10 meters at a 16 meter viewing distance in the VR headset. The circular stimulus runs counterclockwise and completes the cycle in two and a half seconds. The pendulum functions similarly moving from left to right and back at the same rate.
On the left are the metrics that are calculated by Maruta. They computed tangential error and radial error, with respect to the origin at the middle of the circle.
Aside from what was done by them, we also computed local error, meaning that the origin was at the target point so we use the distance error and angular error as new metrics.
Here's an example of the data that was gathered from one subject in the study. As you can see in the baseline on the top, this subject was able to accurately track both the pendulum and the circle.
After being spun, the subject could clearly not follow the pendulum or the circle accurately and deviated from the path.
Statistical analysis was performed to determine which error calculations showed a significant difference between the baseline and post simulated concussion trials.
The two error types that were most significant where the mean of the distance error and the standard deviation of radial error.
After promising results from the VR headset, we adapted the process to use the AR headset. The results here are similar as shown for the circle test with the grey line being the baseline and the yellow line being after spinning.
Future work will further be implementing and testing with the HoloLens2, and once we're able to test this prototype on more subjects, we'll attempt to estimate the sensitivity and specificity of each measure to really hone in on which are the most indicative of concussion.
And then, lastly, here are the sources that were used in this presentation. Thank you for listening.