A concussion, medically classified as a mild traumatic brain injury (mTBI), is a temporary disruption of normal brain function. Vision problems are among the most frequently reported symptoms following this injury, affecting up to 85% of those who sustain a concussion. These visual changes occur because the brain is the primary organ for vision, utilizing nearly half of its neural pathways for processing visual information and controlling eye movements. The eyes themselves may be structurally healthy, but the injury impairs the brain’s ability to interpret and coordinate the information received.
How Concussions Disrupt Visual Processing
A concussion is caused by rapid movement of the brain within the skull, creating shearing and stretching forces on neurons. This physical jarring triggers a complex sequence of events known as the neurometabolic cascade, which temporarily alters brain chemistry and cellular function. The resulting energy crisis and inflammation disrupt the communication networks that link various brain regions responsible for sight.
Visual function is distributed across multiple lobes, including the occipital lobe for initial image processing, the parietal lobe for spatial awareness, and the temporal lobe for object recognition. Dysfunction in these areas impairs the brain’s ability to coordinate visual input. This means that while a standard eye chart test may show normal visual acuity—how clearly you see—the brain’s ability to perform visual processing is compromised.
Identifying Common Visual Symptoms
The disruption to the brain’s visual pathways manifests in several distinct symptoms. One common issue is convergence insufficiency, where the eyes struggle to turn inward together to focus on a nearby object, making reading or close work difficult. This lack of proper eye teaming can lead to eye strain, headaches, and the perception of double vision, known as diplopia.
Another frequent complaint is photophobia, a heightened sensitivity to light that makes bright environments intolerable. This is often due to an inability of the brain to properly filter visual stimuli, overwhelming the system. Difficulties with accommodation, the eye’s ability to rapidly change focus between near and distant targets, cause persistent blurriness, especially when switching attention between tasks.
Oculomotor dysfunction, relating to the control of eye movements, is also highly prevalent. This includes problems with smooth pursuits, which are needed to follow a moving object, and saccades, the quick, precise jumps the eyes make between words while reading. When these movements are impaired, individuals may lose their place frequently, skip lines, or struggle to track a ball in sports.
Recovery Timelines and Long-Term Visual Dysfunction
For the majority of people who sustain a concussion, visual symptoms are temporary, often resolving spontaneously within days to a few weeks as the brain recovers. When symptoms persist beyond the acute recovery phase, usually past three months, the condition is often referred to as Post-Concussion Vision Syndrome (PCVS). PCVS represents a sustained functional disruption in the brain’s visual system, rather than a problem with the physical eye structure.
While a complete and permanent loss of vision is rare after a concussion, the functional visual changes associated with PCVS can become chronic. Approximately 10% to 30% of people with mTBI experience symptoms that last longer than three months. In these cases, the visual system adapts to the injury by developing faulty visual habits, and without targeted intervention, these maladaptations can become entrenched.
Specialized Vision Rehabilitation
When visual dysfunction persists beyond the expected recovery timeline, specialized intervention is necessary to retrain the brain’s visual pathways. The appropriate medical professional for this is often a neuro-optometrist, who focuses on the relationship between the eyes and the brain. They prescribe a personalized treatment program called vision therapy (VT), which is distinct from simply getting a new pair of glasses.
Vision therapy is a structured regimen of exercises designed to rebuild the neural connections that were disrupted by the injury. These exercises may involve specialized lenses, prisms, filters, and computer programs to challenge and refine eye-brain communication. For example, specific activities might target oculomotor function by forcing the eyes to track targets or perform rapid shifts of gaze with improved accuracy.
Other exercises combine visual tasks with balance and movement to improve the integration between the visual and vestibular systems. Because the visual system is closely linked with balance and cognitive function, a comprehensive rehabilitation plan often involves a multidisciplinary approach. This includes collaboration with neurologists and physical therapists to achieve a more complete recovery.