Neuro-Rehab

Vision Therapy and Neuro Rehab

Vision is our dominant sense.

More than just sight is measured in terms of visual acuity, vision is the process of deriving meaning from what is seen. It is a complex, learned and developed set of functions that involve a multitude of skills. Research estimates that eighty to eighty five percent of our perception, learning, cognition and activities are mediated through vision. In fact 65% of the brain is wired for vision!

The ultimate purpose of the visual process is to arrive at an appropriate motor, and/or cognitive response.

"There is an extremely high incidence (greater than 50%) of visual and visual-cognitive disorders in neurologically impaired patients" (traumatic brain injury, cerebral vascular accidents, multiple sclerosis etc.) Rosalind Gianutsos, Ph.D.

"Visual-perceptual dysfunction is one of the most common devastating residual impairments of head injury". Barbara Zoltan, M.A., O.T.R.

"The majority of individuals that recover from a traumatic brain injury will have binocular function difficulties in the form of strabismus, phoria, oculomotor dysfunction, convergence and accommodative abnormalities". William Padula, O.D.

VISUAL ACUITY and VISUAL FIELD

Visual Acuity - This refers to clarity of sight. It is commonly measured using the Snellen chart and noted, for example, as 20/20, 20/50, 20/200 etc. Visual acuity becomes blurred in various refractive conditions, for example, myopia (nearsighted), hyperopia (far-sighted), astigmatism (mixed), and presbyopia (age related loss of focusing).

Visual Field - This is the complete central and peripheral range, or paNORAma of vision. Various neurologic conditions, such as stroke, cause characteristic losses of the visual field, for example hemianopsia. The person may, or may not, concurrently demonstrate a visual neglect which is a perceptual loss of vision and visual motor integration to the side of the visual field loss.

VISUAL MOTOR ABILITIES

Alignment - This refers to eye posture. If the eyes are straight and aligned the eye posture is termed phoric. If an eye turns in, out, up or down compared to the other eye then the eyes are not straight or aligned and the condition is termed strabismus. Exotropia is a form of strabismus where an eye turns out, esotropia is where an eye turns in, hypertropia is where an eye turns up, and hypotropia is where an eye turns down. These can also occur in combination, such as hyper- exotropia, or hypo-esotropia.
Fixation - The ability to steadily and accurately gaze at an object of regard. This is most dysfunctional in nystagmus which is an uncontrollable shaking of the eyes.
Pursuits - The ability to smoothly and accurately track, or follow, a moving object
Saccades - The ability to quickly and accurately look, or scan, from one object to another
Accommodation - The ability to accurately focus on an object of regard, sustain that focusing of the eyes, and to change focusing when looking at different distances
Convergence - The ability to accurately aim the eyes at an object of regard and to track an object as it moves towards and away from the person
Binocularity - The integration of accommodation and convergence
Stereopsis - Depth perception

VISUAL PERCEPTION

Visual-Motor Integration - Eye-hand, eye-foot, and eye-body coordination
Visual-Auditory Integration - The ability to relate and associate what is seen and heard
Visual Memory - The ability to remember and recall information that is seen
Visual Closure - The ability "to fill in the gaps", or complete a visual picture based on seeing only some of the parts
Spatial Relationships - The ability to know "where I am" in relation to objects and space around me and to know where objects are in relation to one another
Figure-Ground Discrimination - The ability to discern form and object from background

Post Trauma Vision Syndrome, Visual Midline Shift Syndrome

Following a neurological event such as a traumatic brain injury, cerebrovascular accident, multiple sclerosis, cerebral palsy, etc., it has been noted by clinicians that persons frequently will report visual problems such as seeing objects appearing to move that are known to be stationary; seeing words in print run together; and experiencing intermittent blurring. 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 type of symptoms are not uncommon. Frequently, persons reporting these symptoms to eye care professionals (optometrists and ophthalmologists) have been told that their problems are not in their eyes and that their eyes appear to be healthy. What is often overlooked is dysfunction of the visual process causing one of two syndromes: Post Trauma Vision Syndrome (PTVS) and/or Visual Midline Shift Syndrome (VMSS).

Recent research has documented PTVS utilizing Visual Evoked Potentials (VEP). This documentation concludes that the ambient visual process frequently becomes dysfunctional after a neurological event such as a TBI or CVA. Persons can often have visual symptoms that are related to dysfunction between one of two visual processes: ambient process and focal process. These two systems are responsible for the ability to organize ourselves in space for balance and movement, as well as to focalize on detail such as looking at a traffic light. Post Trauma Vision Syndrome results when there is dysfunction between the ambient and focal process causing the person to over emphasize the details. Essentially individuals with PTVS begin to look at paragraphs of print almost as isolated letters on a page and have great difficulty organizing their reading ability. It has been found that the use of prisms and binasal occlusion can effectively demonstrate functional improvement, while also being documented on brain wave studies by increasing the amplitude (this is like turning up the volume on your radio).

Visual Midline Shift Syndrome 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 causes a shift in their concept of their perceived visual midline. This will frequently cause the person to lean to one side, forward and/or backward. It frequently can occur in conjunction with individuals that have had a hemiparesis (paralysis to one side following a TBI or CVA). The shifting concept of visual midline actually reinforces the paralysis, by using specially designed yoked prisms that can be prescribed, the midline is shifted to a more centered position thereby enabling individuals to frequently begin weight bearing on their affected side. This works very effectively in conjunction with physical and occupational therapy attempting to rehabilitate weight bearing for ambulation.

The Neuro-Optometric Rehabilitation Association (NORA)offers referrals to our member doctors to treat individuals who may suffer from the symptoms of PTVS or VMSS. For further questions concerning these syndromes and/or referral sources, please contact NORA.

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