Persons with a TBI or CVA frequently will experience symptoms of double vision, movement of print or stationary objects such as walls and floor, eye strain, visual fatigue, headaches and problems with balance, to name several. Frequently, people will report problems with their vision to rehabilitation professionals and be referred for eye examination. Unfortunately, many will be told that there is nothing wrong with their eye and that it is the effects of their TBI or CVA. Others will be told that their symptoms are not related to their vision. More interesting symptoms are sometimes reported such as: attempting to walk on a floor that appears tilted and having significant difficulties with balance and spatial orientation when in crowded, moving environments.
These types of symptoms are not uncommon. Frequently, persons reporting these symptoms to eyecare professionals (optometrists and ophthalmologists) have been told that their problems are ‘not in their eyes’ and that their eyes appear to be healthy. In many instances persons experiencing these difficulties also experience anxiety with these symptoms and are often referred to psychologists or psychiatrists in an attempt to treat their anxiety. The referral for psychological or psychiatric care is sometimes made based on a diagnosis of hysteria without recognizing that many of these individuals are suffering from syndromes affecting the visual process in the brain.
Visual problems are among the most common sequella following a TBI or CVA, but frequently not dealt with in a rehabilitation. Persons may often experience difficulties with balance, spatial orientation, coordination, cognitive function, and speech.
Vision imbalances can occur between the focal and ambient visual process that can affect balance, posture, ambulation, reading, attention, concentration and cognitive function in general. Post Trauma Vision Syndrome (PTVS) and Visual Midline Shift Syndrome (VMSS) can be the cause of these difficulties.
Post Trauma Vision Syndrome
Sensory problems are common after traumatic brain injury. The problems these patient’s have with their vision is referred to as Post Trauma Vision Syndrome or PTVS. Over half who have experienced brain injury have vision problems, such as blurred or double vision and visual field defects. Blurred or double vision may improve during the first six months after the trauma event, but the field abnormalities are more likely to persist (Mira, Tucker, & Tyler, 1992)
Binocular vision is what allows us to blend the two images seen by each of the eyes into only one perceived image. Long-term difficulties with binocular vision are common. In post trauma vision syndrome the condition occurs abruptly. The brain does not have a chance to adapt gradually and abnormal vision persists. It is important that any patient who suffers traumatic brain injury receive a comprehensive ophthalmologic exam (Mira, Tucker, & Tyler, 1992).
Double vision in particular interferes with depth perception, locating objects, and the ability to match visual information with kinesthetic, proprioceptive, and vestibular experiences.
MRI findings are usually negative in post-trauma vision syndrome. The injuries suffered are most often diffuse and are caused by shearing and stretching of the brain fibers, as well as the neurotoxic cascade induced by the injury.
Midline Shift Syndrome
Visual Midline Shift Syndrome (VMMS) also results from dysfunction of the ambient visual process. It is caused by distortions of the spatial system causing the individual to misperceive their position in their spatial environment. This will frequently cause the person to lean to one side, forward and/or backward. Visual Midline Shift Syndrome also results from dysfunction of the ambient visual process. This causes a shift in their concept of their perceived visual midline.
The midline with VMSS affects not only persons who are attempting to ambulate, but also those individuals that are wheelchair bound causing them to lean to the side, forward or backward. Yoked prism therapeutic lenses can make significant changes in concept of midline, thereby affecting posture, balance and movement. The use of these yoked prisms can be developed in a transdisciplinary approach, so that they may be incorporated into existing physical and/or occupational therapy programs. The authors again emphasize that neuro-optometric rehabilitation should support the overall rehabilitation of the individual prior to and/or concurrently being given physical and or occupational therapy.
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