A head injury can disrupt vision even when eyesight looks “perfect.” Learn the signs to watch for and how vision care can help recovery.
Headaches, dizziness, and light sensitivity are common after a concussion. But here’s one of the biggest misconceptions: if you can see 20/20 on an eye chart, your vision must be fine. In reality, eyesight and vision are not the same.
Eyesight is the ability to see an image clearly. Vision is how your brain processes and understands what you see. More than half of your brain is involved in visual processing, so even a mild concussion can affect vision.
How Concussion Affects Vision
1. Light Sensitivity and Brain Filtering
After a concussion, many people struggle with bright lights, busy patterns, or screen glare. This is often because the brain’s filtering system, the thalamus, does not regulate incoming information as well after an injury. The result? Environments that were once easy, like classrooms, arenas, or grocery stores, suddenly feel overwhelming.
Specialized lenses, such as tints or prisms, can help reduce this “visual noise,” giving the brain extra support while it heals.
2. Reading and Eye Teaming
Concussions can also disrupt how the eyes move and work together. Precise eye movements, such as saccades (the small, quick jumps used for reading), rely on multiple areas of the brain. When these systems are injured, people may lose their place, skip words, or feel dizzy while scrolling or reading.
It is not just fatigue, it is the brain struggling to coordinate eye movements. This explains why tasks like studying, driving, or even looking at a phone can suddenly become difficult after a concussion.
3. Real World vs. Exam Room
A routine eye exam is important, but it does not always capture the full picture after a concussion. Reading black letters on a white chart in a quiet room is very different from functioning in the real world, where lights are bright, environments are colorful, and people and objects are in constant motion. It is also a short task, often lasting only a few seconds, compared to real life where reading or screen use may demand 15 to 20 minutes or more of sustained focus.
That is why a functional vision assessment is often needed after a concussion. These evaluations look at how the eyes and brain are working together in dynamic conditions, which better reflects the challenges patients face every day.
Why This Matters
Unaddressed vision problems after concussion do not just slow recovery, they can make everyday life harder. Students may struggle to read, athletes may feel off-balance, and adults may find work tasks exhausting. Too often, people are told they are “fine” because they see clearly, when in fact their vision system is still under strain.
The good news is that help is available. Through customized lenses, filters, and vision therapy, optometrists can support the brain’s recovery and help patients return to comfort and confidence.
Takeaway
The biggest misconception is that 20/20 eyesight equals healthy vision. In reality, concussions often disrupt how the brain processes what the eyes see, even when the chart looks perfect.
If you or someone you know is recovering from a concussion and noticing light sensitivity, difficulty reading, dizziness, or discomfort in busy environments, consider seeing an optometrist trained in concussion care. Eyesight may be clear, but vision may still need healing.
Dr. Sarah Hutchens, OD, FOVDR*
*Board Certified in Vision Therapy, Vision Development and Vision Rehabilitation
Your support for sport in Newfoundland and Labrador.