How Traumatic Brain Injuries Affect the Eyes
Have you or someone you know ever experienced a traumatic brain injury (TBI) from falling? Perhaps a concussion from an impact sport injury or car accident? Whatever the root cause, TBI’s can range from mildly to severely impacting a person’s everyday life. The brain is a fragile organ and the main command centre of our bodies. Any damage to any part of the brain can have severe effects on how the rest of our body functions as a whole. The eyes especially – since they are directly connected to the brain via the optic nerve.
How the eyes function is controlled by different areas of the brain. Although the occipital lobe is located in the back of our heads (right below the bump on the back of our heads), there are other connections/areas in the brain responsible for simple eye movements that we use everyday. Damage to any part of this complicated pathway can result in slowed or the inability to perform these simple eye movements. These movements are utilized for target localization, tracking, and our general proprioception (awareness of where our bodies are in space).
What we experience when these systems are affected is a confused/foggy feeling, a feeling of being over-whelmed in busy/bright environments (ie. grocery stores), the inability to track, difficulty reading, difficulty focusing (near or far), light sensitivity, inability to walk in a straight line, inability to balance (one or both legs) with eyes closed, or an intolerance to “action movies” (loud scenes/environments). Some or all of these symptoms may be present when someone has a TBI and they are all due to damage to the visual system.
Many of the symptoms stated above don’t seem like eye problems – since most people only associate blurry vision with eye problems. Most concussed people can see perfectly fine (20/20) but still are not able to function normally on a day to day basis. To break down how this is related to the eyes, we need to think of the visual system in two parts: the WHAT system and the WHERE/HOW system. TBI’s don’t normally affect the what system too much – it is mostly the where/how system. Although small prescriptions can often improve some symptoms, it is not usually the major issue for most people.
The what system is the detail gathering system. It tells us what we’re looking at – the colour, the shape, the text, or the details. It’s our identifying system. The where/how system is the locating system. It tells us where something is in space, how fast/if it is moving, where it is moving to/from, and helps with our general proprioception of our bodies in space. Essentially, it is the GPS system for our eyes. These two systems work together to help us function in our everyday lives. And it is a disconnect between these two systems that TBI individuals are healing from. Imagine viewing an object through only a small peep hole. You can see all the details and identify what it is, but you have no information about where it is. The information to tell you where the item is located is missing or incomplete. This jumbled information causes confusion for your brain because it can’t make sense of the information – thus you feel dizzy, foggy, over-whelmed, or uncomfortable with where/what you’re doing.
It is our goal at Wink Optometry to help concussion patients rehabilitate their where/how system back to what it was prior to the injury so they can get back to their regular lives. At Wink we are utilizing RightEye eye tracking technology to help diagnose how severely a patient’s visual system has been affected. It is an objective test that shows exactly how a person’s eyes are moving and gathering information. We can play back the results to help show patients what their eyes are doing and help them rehabilitate these simple eye movements to aid in their TBI recovery journey.