Also known as vision therapy, neurovision rehabilitation can benefit individuals with traumatic and acquired brain injuries.
To understand the visual impacts of a brain injury, it is important to know the functions of the visual system. Areas that are most involved in the visual processes include the primary visual cortex and the midbrain.
The Brain & Your Vision
The primary visual cortex is responsible for
- conscious and unconscious visual processing
- color vision
- contour detection
- visual acuity
- voluntary eye pursuits
- binocular integration.
The midbrain, specifically the superior colliculus and pulvinar are responsible for
- motion detection
- spatial orientation
- figure-ground differentiation
The midbrain is also where information from the visual system is matched with information gathered from proprioceptive and vestibular systems to impact balance, posture, and function.
Because of the widespread area of the brain dedicated to visual processing in some form, presentation of brain injuries varies greatly. In a whiplash injury, the occipital lobe rocks against the back of the skull, damaging the primary occipital lobe, and there is a shearing injury to the brain stem, resulting in damage to the midbrain. In a stroke, the damage is more localized to one area.
Symptoms of Concussions & Traumatic Brain Injuries (TBI)
Some symptoms of concussions that indicate visual processing damage are the same as symptoms with vestibular or proprioceptive input damages, including vertigo, lack of spatial localization, and nausea. An optometrist practicing neuro-visual rehabilitation is able to distinguish the source of the symptoms.
Other symptoms, including being overwhelmed with visual input in busy settings, such as in the grocery store or driving, are unique to visual system damage. This symptom happens due to focal binding, the inability to release the peripheral vision and hyper fixating on every object in their visual field. This is a very common symptom following concussions.
Other common ocular symptoms include headaches, double vision in all or some directions, difficulty reading, difficulty concentrating, eye strain, peripheral motion sensitivity, light sensitivity, visual field loss, visual neglect, and difficulty watching moving objects or screens.
Neuro-visual rehabilitation techniques can be broken into passive and active treatments.
Passive treatments include lens techniques, such as prisms, binasal occlusion, and selected tints. Binasal occlusion is especially effective in patients with focal binding as it reduces the overall stimulation. Selected therapeutic tints reduce overall stimulation without reducing the clarity of vision.
Active treatments are exercises done in the office and at home to re-learn visual processing skills that were compromised by the brain injury. Often this includes processing skills that are learned in early development, including appropriate use of peripheral vision, tracking moving objects, smoothly and accurately moving eyes, and distinguishing figure-ground. During active therapy, it is important to build visual skills from the most basic skills to the more complex skills.
Assessments for Post Concussion or Traumatic Brain Injury
Ideally, everyone who has had a brain injury should be assessed as early as possible for a visual component in order to minimize the impact on quality of life. Visual rehabilitation and physiotherapy are complementary, with maximum benefit coming from a team of health care providers working together.
About our Vision Therapy Eye Doctor
Rebecca Lamhonwah is a Doctor of Optometry and a member of the Canadian Optometrists in Vision Therapy and Rehabilitation (COVT&R) and the Optometric Extension Program Foundation (OEPF.) She is pleased to bring neuro-visual rehabilitation to the valley.