Anne Marie Yeboah: Using the eyes to gain insight into concussions

By Tienna Schade 

Originally from Richmond Hill, Ontario, PhD candidate Anne Marie Yeboah earned her Bachelor of Science from McMaster University in 2018. Afterward, she completed her master's degree in vision science at the University of Waterloo School of Optometry and Vision Science, which almost seamlessly led her into her PhD studies. 

With her supervisors, Drs. Kristine Dalton and Elizabeth Irving, Yeboah is looking to build our understanding of how eye movements and visual performance may be impacted by concussion. The eyes often provide clues to what is going on inside the brain, so understanding how they’re affected by concussion may help doctors diagnose patients faster and more accurately.  

In Canada, it’s estimated that over 200,000 concussions occur annually. However, under-reporting means this figure likely underestimates the true number of concussions that occur each year. 

Recently, Yeboah’s work has been recognized with several awards, including: 

• Dorrie Morrow Fund Award from the Canadian Optometric Education Trust Fund 

• Natural Sciences and Engineering Research Council of Canada (NSERC) Canada Graduate Scholarship – Doctoral 

• University of Waterloo President’s Graduate Scholarship 

I played soccer growing up, which eventually led me to playing varsity soccer during my undergraduate studies. In the varsity setting, concussions were so common, and it was then that my interest started.   During this time, I also had the opportunity to volunteer at an ophthalmology office where I encountered several patients with concussions. I became incredibly interested in the concussion-related visual deficits these patients exhibited.

To further our understanding, we’re conducting projects that compare the visual performance and eye movements between concussed and non-concussed groups. In a retrospective study, we’ve compared visual performance between the two groups by collecting data from the School’s optometry clinic.   

In an ongoing eye tracking study, we’re comparing the eye movements of people with and without concussion. There are several types of movements and parameters we track. A few examples of eye movements would include:

• Saccades:  a quick movement or jump of the eyes from one point of focus to another (e.g.  when you’re reading)  
• Pursuits:  eye movements that track a moving object (e.g.  tracking an airplane flying in the sky)
• Vergence: teaming of the eyes to view near and far objects (e.g.  viewing a finger nearing your nose)

In our retrospective review, we found that the near point of convergence in the concussion group was about twice as far from the eyes than in the than in the non-concussed group.

The near point of convergence is the closest distance the eyes can maintain a single image of an object. After the near point of convergence, you may start to see a double image. Although existing literature already indicated impaired near point of convergence is common following concussion, the magnitude of the difference between the two groups was surprising.

Right now, there are no objective measures to diagnose a concussion. Medical professionals largely rely on a subjective symptom survey and their clinical judgment to make a diagnosis.   

Another branch of my research involves validating a small and compact eye tracking system embedded in glasses.  Many research-grade eye trackers are cumbersome and immobile. If we can validate this new and portable eye tracker, then it could potentially be a tool utilized in concussion management. With further research, it may even eventually become an objective diagnostic tool. 

Yes! I hope to complete a postdoctoral fellowship. I’m really enjoying my area of research, and it would be great to find myself in a position where I can continue researching concussion and focusing on ways to optimize the care for individuals with concussion.