A concussion, defined as a mild traumatic brain injury (mTBI), often results in a temporary disruption of normal brain function. A concussion can definitively cause vision problems, as the visual system is highly sensitive to the forces of a head injury. Up to 90% of patients who experience a traumatic brain injury report some form of visual symptoms.
How Head Trauma Affects Vision Processing
The visual difficulties that occur after a concussion are typically not due to physical damage to the eye itself, but rather to the neural pathways and brain centers responsible for processing vision. Vision involves over 70% of the brain, making it susceptible to the shearing and twisting forces of a concussive event. These forces primarily affect the brain’s white matter, which comprises the communication networks that coordinate eye movement and visual interpretation.
Specific areas of the brain are particularly vulnerable. These include the occipital lobe, home to the primary visual cortex responsible for interpreting light signals into images. The brainstem, which controls basic reflexes like eye movement and pupil response, is also frequently disrupted, leading to difficulties in coordinating the eyes. The vestibular system, which manages balance and spatial orientation, works in close partnership with the visual system to stabilize images during movement, and its impairment contributes to visual instability.
Specific Visual Symptoms After Concussion
Visual disturbances following a head injury can be grouped into distinct categories related to the brain’s impaired functioning. These symptoms often compound each other, leading to significant challenges in daily life, such as reading or driving.
Oculomotor Dysfunction
One major category is oculomotor dysfunction, which involves issues with controlling and coordinating eye movements. This can manifest as difficulty tracking a moving object or accurately shifting gaze between targets, a problem known as saccadic dysfunction. Convergence insufficiency is a common finding, where the eyes struggle to turn inward to focus on near objects, causing double vision, eye strain, and the tendency to lose one’s place while reading.
Accommodative Dysfunction
Another frequent issue is accommodative dysfunction, which impairs the ability of the lens in the eye to change shape and maintain focus. This can result in blurred vision, particularly when trying to focus on material up close, a task demanding high visual effort. Patients with accommodative insufficiency may find that their vision blurs after only a short time of reading or screen use, leading to fatigue and headaches.
Sensory Issues
A third major area involves sensory issues related to visual perception and light. Photophobia, or extreme light sensitivity, is one of the most reported symptoms after a concussion, often forcing individuals to wear sunglasses indoors. People may also experience visual motion sensitivity, feeling overwhelmed or dizzy in visually complex environments like crowded grocery stores or busy traffic. This sensory overload is thought to be related to the disrupted processing between the visual and vestibular systems.
Diagnosis and Recovery Methods
The initial steps for addressing post-concussion vision problems involve seeking a specialized evaluation that goes beyond a standard eye exam. Specialists like neuro-optometrists or neuro-ophthalmologists are trained to assess the communication between the eyes and the brain. They use comprehensive tests, such as the Vestibular Ocular Motor Screening (VOMS) tool, to assess eye movements, balance, and symptom provocation.
Diagnosis often identifies specific functional deficits, which then guide a targeted rehabilitation program. A primary recovery method is prescription vision therapy, a customized regimen of eye exercises designed to redevelop the neural pathways for visual processing. These activities are comparable to physical therapy for the visual system, helping to stabilize eye tracking and focusing skills through repetitive tasks.
Therapeutic lenses are another common intervention used to manage symptoms while the brain heals. Prism lenses, which subtly bend incoming light, can compensate for slight eye misalignments and reduce symptoms like double vision and dizziness. By minimizing visual strain, these specialized glasses allow the brain to allocate more energy toward overall recovery. Most visual issues improve significantly with consistent, targeted treatment, providing a path toward returning to normal daily activities.