Approximately 60% of the brain is required for visual processing. When brain damage occurs from a laceration, concussion, neuro-degeneration, stroke or even surgery there is a likelihood that part of the visual process is affected. Some problems are irreversible while others can be improved thanks to neuro-plasticity.
Vision guides and directs almost every motor action we do. Reading, walking, catching a ball, reaching for a glass of water, and writing all require vision to guide and direct hand movements, leg movements and balance. When visual coordination is affected a brain injured patient will often struggle with vision heavy tasks. They may struggle with reading, computer work, have light sensitivity, difficulty with visual motion, driving, or poor balance when walking.
Good coordination is required for ocular motor skills such as fixations, tracking and saccadic eye movements. Coordination is also required for the eyes to quickly and accurately, change focus when looking near and far. Binocular Vision requires both eyes to work together as a team to point at the same location in space and allow the brain to see a 3-dimensional image.
Vision Rehabilitation is evidence-based. The Ontario Neurotrauma Foundation released Guidelines for Concussion/Mild Traumatic Brain Injury & Persistent Symptoms (Adults). Within this guideline, it is recommended that patients with persistent visual symptoms resulting from head injury undergo vision therapy for treatment (www.onf.org).
Post Traumatic Vision Syndrome (PTVS)
PTVS is a dysfunction between ambient and focal vision processes. The ambient process is responsible to organize ourselves in space for balance and movement. The focal process is responsible to help us focus and attend to detail. When there is an imbalance there is a tendency to overemphasize the focal process and leave a person with poor balance and poor perception of space and movement.
Visual Evoked Potential (VEP) test measure the signal as it travels from the eyes to the brain. A person with PTVS will often have an abnormal signal and the use of prisms or bi-nasal occlusion will often normalize the signal. Vision Rehabilitation has been shown to re-establish a balance between ambient and focal processes and VEP results become normal without the use of prisms or bi-nasal occlusion.
Visual Midline Shift (VMS)
VMS results from a dysfunctional ambient visual process that causes a misperception of space and a person’s position in space. Patients will often describe seeing distortions in space, such as slanted walls or floors and they may stand or walk with a lean or veering in one direction. Yoked prisms are used to realign this shift in perception. Vision Rehabilitation will help a person re-establish their true perception of space.