Your eyes can reveal a lot about whether you’ve had a concussion. Visual disturbances occur in up to 69% of people after a mild traumatic brain injury, making eye-related symptoms one of the most reliable indicators that something is wrong. These range from light sensitivity and blurred vision to trouble focusing on nearby objects and difficulty tracking movement. Knowing what to look for in your eyes can help you recognize a concussion early.
Why Concussions Affect Your Eyes
The visual system relies on widely distributed networks throughout the brain. Unlike a broken bone that damages one spot, a concussion causes neurological changes that ripple across these networks, disrupting the coordinated signals your brain uses to control eye movement, focus, and light processing. That’s why eye symptoms are so common after a head impact: your brain is struggling to manage the complex tasks your visual system normally handles automatically.
This affects everything from how quickly your pupils respond to light, to how smoothly your eyes track a moving object, to how well both eyes work together to focus on something close to your face. Even a “mild” concussion can produce noticeable changes in how your eyes function.
Light Sensitivity
Sensitivity to light is one of the most common and noticeable eye symptoms after a concussion. In a study of 300 people with mild traumatic brain injuries, 54% experienced visual light sensitivity. If bright rooms, sunlight, or screens suddenly feel harsh or painful when they didn’t before your injury, that’s a significant clue.
The good news is that this symptom typically resolves on its own. About two-thirds of people with post-concussion light sensitivity recover within three months. In the meantime, you may find that screens, fluorescent lighting, and driving at night are particularly uncomfortable.
Blurred Vision and Trouble Focusing
Blurred vision after a head injury often points to problems with accommodation, your eye’s ability to shift focus between near and far objects. A concussion can impair this process, making close-up tasks like reading feel strained or impossible. You might also notice that text seems to swim on the page, or that you keep losing your place while reading.
Convergence insufficiency is another common issue. This is when your eyes struggle to work together to focus on something close to you. Clinicians screen for this by measuring how close you can bring a small object to your nose before your vision doubles or one eye drifts outward. A result beyond about 6 centimeters is considered abnormal. You can try a rough version of this yourself: slowly bring a pen toward your nose while keeping it in focus. If your vision doubles unusually far from your face, or if one eye seems to give up and drift, that’s a potential sign of a concussion-related focusing problem.
People with convergence or focusing problems after a concussion commonly report headaches, eye pain, and double vision at close range.
Difficulty Tracking Moving Objects
Smooth pursuit is the ability to follow a moving object with your eyes without your gaze jumping around. After a concussion, this ability is often impaired. Research comparing concussed athletes to healthy controls found that concussed individuals had significantly slower smooth pursuit eye movements. To compensate, their eyes made more frequent and larger corrective jumps (called saccades) to keep up with moving targets.
You might notice this as difficulty following a ball during sports, trouble keeping your eyes on a moving car, or a general sense that your vision “lags” behind what’s happening around you. Some people describe it as feeling like their eyes can’t keep up with the world. This can also contribute to dizziness and nausea, especially during movement or in visually busy environments like grocery stores or crowded streets.
Pupil Changes
Impaired pupil function is a recognized sign of concussion, and checking your pupils is one of the first things a medical professional will do after a head injury. Your pupils should be roughly equal in size and should both constrict briskly when you shine a light into either eye.
A small difference in pupil size isn’t always dangerous on its own. Some people naturally have slightly unequal pupils. But certain patterns after a head injury are red flags that signal something more serious than a typical concussion. If one pupil is significantly larger than the other and doesn’t react to light, especially if paired with a drooping eyelid and an eye that drifts outward and downward, that can indicate pressure on a cranial nerve. This pattern requires emergency medical attention because it can signal bleeding or swelling inside the skull.
Similarly, if you develop a sudden severe headache alongside unequal pupils, or sudden blurring of vision with a noticeable size difference between your pupils, treat it as an emergency.
Dizziness Triggered by Eye Movement
The vestibular-ocular reflex is the system that keeps your vision stable while your head moves. Think of it as the brain’s image stabilization. When a concussion disrupts this reflex, you may experience dizziness triggered by head movement, a sensation that objects are bouncing or sliding in your visual field, blurred vision when you turn your head, and difficulty balancing.
Visual motion sensitivity is related. This is when busy visual environments, scrolling on a phone, or watching action scenes on TV make you feel dizzy or nauseated. If you find yourself suddenly unable to tolerate visual stimulation that never bothered you before, that’s a meaningful symptom.
What These Signs Look Like in Children
Young children can’t always describe what they’re seeing or feeling, which makes eye-related concussion signs harder to spot. A child with visual symptoms after a head injury might not say “everything looks blurry.” Instead, you might notice them squinting or closing one eye, refusing to look at screens or books, becoming unusually clumsy or unsteady, appearing dazed or confused, or showing irritability and crying more than usual.
Children under four may seek more comfort than normal, refuse to eat, show changes in sleep patterns, lose interest in play, or display more temper tantrums. These behavioral shifts can be the only visible signs that something is wrong with how their brain is processing visual information. If a young child has taken a hit to the head and shows these changes, the absence of a specific complaint about their eyes doesn’t rule out a concussion.
What You Can Check at Home
While a proper concussion evaluation requires a trained professional, you can look for several things on your own after a head injury:
- Pupil size: Look in a mirror or have someone check whether your pupils are equal. Shine a flashlight into each eye and watch for a quick, symmetrical constriction.
- Light tolerance: Step into a bright room or look toward a window. If the light feels painful or overwhelming in a way it normally wouldn’t, note that.
- Near focus: Slowly bring a pen toward your nose. If your vision doubles more than a few inches from your face, or one eye visibly drifts, that suggests a focusing problem.
- Tracking: Have someone slowly move a finger side to side and up and down about two feet from your face. Follow it with your eyes without moving your head. If your eyes jump rather than moving smoothly, or if this triggers a headache, dizziness, or nausea, that’s a concern.
- Head movement: Turn your head side to side while focusing on a stationary object. If this makes you dizzy or the object appears to blur or bounce, your vestibular-ocular reflex may be affected.
These checks are not a substitute for clinical assessment. Healthcare providers use a formal screening tool called the Vestibular/Ocular Motor Screening, which systematically tests smooth pursuit, saccades, convergence, vestibular-ocular reflex, and visual motion sensitivity. Each test is scored based on whether it provokes symptoms like headache, dizziness, or nausea. If your at-home checks raise concerns, this kind of professional evaluation can confirm what’s going on and guide your recovery.
When Eye Symptoms Don’t Go Away
Most concussion-related visual problems resolve within seven to ten days without treatment. But a subset of people continue to experience symptoms for weeks or months. Persistent light sensitivity, reading difficulty, trouble with screens, and dizziness in visually stimulating environments can linger and significantly affect daily life.
If your eye symptoms haven’t improved after two to three weeks, a vision evaluation by a provider experienced with concussion-related visual disorders can identify specific problems like convergence insufficiency or accommodative dysfunction. These conditions often respond well to targeted vision therapy, which retrains the eye coordination and focusing skills that the concussion disrupted.