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Neuro Vision Rehabilitation Services

Neuro Vision Rehabilitation is an individualized treatment regimen for patients with visual deficits as a direct result of physical disabilities, traumatic and / or acquired brain injuries. Neuro-Optometric Therapy is a process for the rehabilitation of visual / perceptual / motor disorders. It includes, but is not limited to, acquired strabismus, diplopia, binocular dysfunction, convergence, and / or accommodation, paresis / paralysis, oculomotor dysfunction, visual spatial dysfunction, visual perceptual and cognitive deficits, and traumatic visual acuity loss.

Patients of all ages who experienced neurological insults require Neuro-Optometric Rehabilitation. Visual problems caused by Traumatic Brain Injury, Cerebrovascular Accidents, Cerebral Palsy, Multiple Sclerosis, etc. may interfere with performance causing the person to be identified as Learning Disabled or as having Attention Deficits Disorder. These visual dysfunctions can manifest themselves as psychological sequela such as anxiety and panic disorders as well as spatial dysfunctions affecting balance and posture.

A Neuro-Optometric Rehabilitation treatment plan improves specific acquired vision dysfunction determined by standardized diagnostic criteria. Treatment regimens encompass medically necessary noncompensatory lenses and prisms with and without occlusion and other appropriate medical rehabilitation strategies.                      

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.

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.

The process of vision can be broken down into three general categories; 1) visual acuity and visual field, 2) visual motor abilities and 3) visual perception.

1) 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 neurological 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.

2) 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 hyper-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

3) 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

THE THREE MOST DEVASTATING AND INTOLERABLE VISUAL PROBLEMS RESULTING FROM BRAIN INJURY AND STROKE

Although there are many visual problems that arise from brain injury and stroke, three are more devastating and impairing than the rest. These are visual field loss, intractable double vision, and visual / balance disorders.

Visual Field Loss

With a visual field loss the patient is literally blind to half of their field of vision. This places the person at increased risk of further injury and harm from bumping into objects, being struck by approaching objects, and falls.

A two fold approach is used to treat visual field loss. Visual rehabilitation activities are prescribed by the doctor and administered by the therapist to teach scanning of the hemianopic field loss. This is a difficult task. It is the act of seeing something that brings our visual attention and scanning to bear. However, these patients do not see to the field they are being trained to scan and attend. Therapy is aimed at teaching that and several approaches have been developed to assist in this, but remediation still requires a lot of effort and patience.

Special visual field awareness prism lenses are used in treating visual field loss. As the patient scans into the prism the optics are shifted so as to perceptually gain about 15 to 20 degrees of visual field recognition. Since diplopia is perceived when scanning into the prism, fixation in the prism must be brief. These are used as spotting devices only to determine if there is an object in the periphery that deserves further visual attention. When such an object is spotted, the patient turns their head to view it in detail with their intact central vision.

Double Vision (Diplopia)

Double vision (diplopia) is a serious and intolerable condition that can be caused by strabismus, ophthalmoplegia, gaze palsy, and decompensated binocular skills in patients with brain injury, stroke and other neurologically compromising conditions. Prisms, lenses and / or vision therapy can oftentimes help the patient achieve fusion (alignment of the eyes) and alleviate the diplopia. If and when these means are not employed, the patient may adapt by suppressing the vision of one eye to eliminate the diplopia. If lenses, prisms, and / or therapy are not successful and the patient does not suppress, intractable diplopia ensues.

In this population of patients, patching has frequently been used to eliminate the diplopia. Although patching is effective in eliminating diplopia it causes the patient to become monocular. Monocular as opposed to binocular vision will affect the individual primarily in two ways; absence of stereopsis and reduction of the peripheral field of vision. These limitations will directly cause problems in eye hand coordination, depth judgments, orientation, balance, mobility, and activities of daily living such as playing sports, driving, climbing stairs, crossing the street, threading a needle etc.

A new method of treating diplopia that does not have these limitations has been successfully evaluated. It is called the “spot patch” (invented and named by this author) and is a method to eliminate intractable diplopia without compromising peripheral vision. It is a small, usually round or oval, patch made of dermacil tape, 3-M blurring film (or another such translucent tape). It is placed on the inside of the lenses of glasses and directly in the line of sight contributing to the diplopia. The diameter is generally about one centimeter, but will vary on the individual angular subtense required for the particular strabismus, or gaze palsy.

Visual balance disorders can be caused by a Visual Midline Shift Syndrome (VMSS), oculo-motor dysfunction in fixations, nystagmus, and disruptions of central and peripheral visual processing. A full description of these disorders is beyond the scope of this paper. The treatment will depend on the visual diagnosis and etiology. Lenses, prisms and visual rehabilitation activities are used in the remediation of these disorders.Visual Balance Disorders

OVERVIEW OF THE PATHOPHYSIOLOGY OF VISION PROBLEMS FOLLOWING BRAIN INJURY OR STROKE

Traumatic Brain Injury can have devastating effects on the visual system. Vision is frequently disrupted following head injury, stroke and other neurologically compromising conditions (e.g. multiple sclerosis, cerebral vasculitis, aneurysm, hypoxia etc). The anatomy and physiology of the visual system, the vascular network of the brain, and the dynamics of head trauma all contribute to the incidence of ocular trauma and visual dysfunction.

Injury to the visual system can be diffuse and / or focal and can localize to any, or a combination of the ocular structures, cortical areas, mid brain, or nerve nuclei. Brain injuries affecting vision typically occur via axonal shearing, hemorrhage, infarct, inflammation, and / or compression.

The third cranial nerve and third nerve nuclei seem to be particularly vulnerable to injury following trauma and stroke. These innervate eight of the twelve extra-ocular muscles (the medial, inferior and superior recti, and inferior oblique muscles), the ciliary (focusing) muscle inside of the eye, the levator (eyelid) muscle, and the pupillary sphincter muscle. Consequently, injury to this area causes some classic signs and symptoms that will manifest as:

  • Exotropia
  • Exophoria
  • Convergence Insufficiency
  • Convergence Infacility
  • Accommodative Insufficiency
  • Accommodative Infacility
  • Ptosis
  • Fixed and Dilated Pupil

Limited Motility (Abduction, Sursumduction, Infraduction) of the affected eye

The sixth cranial nerve and nuclei are also prone to injury in TBI and stroke. These control two of the twelve extra-ocular muscles (the lateral recti muscles) which are responsible for abduction of the eye. Injury to the communication pathways between sixth nerve nuclei and their paired third nerve nuclei can also occur. This is termed an internuclear ophthalmoplegia (INO). Sixth nerve problems will manifest as:

  • Esotropia
  • Esophoria
  • Divergence Insufficiency
  • Divergence Infacility
  • Limited Abduction of the Affected Eye
  • Internuclear Ophthalmoplegia will manifest as:
  • Exotropia
  • Limited Adduction of the Affected Eye
  • Paralysis of Gaze to the Affected Side

The fourth cranial nerve is less frequently injured in TBI and stroke. It is more frequently injured by direct trauma. The fourth nerve and nucleus control two of the twelve extra-ocular muscles, the superior obliques. These muscles are responsible for inferior gaze of the eye when it is adducted. Damage to this area will manifest as:

  • Hypertropia
  • Limited Down Gaze of the Affected Eye when      Adducted

The optic nerve (second cranial nerve) and its radiations and pathway back to the occipital and associated corticies can be injured in TBI and stroke. The location of the injury will determine the nature of the deficit. Visual field loss is the manifestation of these injuries.

If the optic nerve is damaged between the eye itself and the optic chiasm, there will be a monocular loss of sight and a pupillary defect. This is seen in direct trauma and multiple sclerosis.

When the damage is at the chiasm there will be a classic bi-temporal visual field loss. This is found frequently in pituitary disorders.

If the injury occurs in the optic radiations coursing back from the chiasm to the lateral geniculate nucleus (LGN), there will be an incongruous (unequal) bilateral visual field loss. Although this can be a hemianopsia (half visual field loss) or quadrantanopsia (quarter field loss), it will more frequently show as a quadrantanopsia.

When the injury is posterior to the LGN and ranging back to the occipital cortex there will be a homonymous bilateral visual field loss. The visual field loss will show more frequently as a hemianopsia, but can also be a quadrantanopsia.

Visual fibers feed forward to other areas of the brain. One in particular is the parietal cortex which is frequently referred to as the association cortex. It is called this because it integrates information from the various senses in an attempt to derive meaning from the “whole picture”. When there is damage to this area, one will frequently find a visual neglect.

Visual neglect is a perceptual loss of vision. The person is unaware of their sight, or lack of sight to the affected side. If the nerve pathways and occipital cortex are spared and only the parietal cortex is affected there will a sparing of vision (to a good degree), but the person will “ignore” and not attend to vision on the affected side. If the pathways and / or occipital cortex are injured as well as the parietal cortex, then there will be an actual visual field loss in addition to the person having a neglect, and / or denial of loss of vision.

Injury to the frontal cortex can affect vision. The frontal eye fields are in the frontal cortex and so eye movement disorders can occur from injury here. This can also cause a perceptual deficit in visual memory.

Parietal and occipital-parietal injuries can cause visual perceptual deficits. These include visual-motor integration, figure-ground discrimination, spatial relations, topographic orientation and form perception and constancy.

Vision integrates with and affects balance. Approximately twenty percent of the visual fibers are involved in this process. Following brain injury and stroke problems with nystagmus, ocular motor control and strabismus will disrupt balance and can cause dizziness and vertigo.

Visual Midline Shift Syndrome {(VMSS) Padula}, is a condition that affects balance, posture, orientation and mobility can occur following TBI and stroke In VMSS the persons’ visual perception of the world will appear compressed in one portion and expanded in another. Their perception of the world will therefore appear slanted, or tipped, and walls may appear bowed and distorted. Balance is disrupted when attempts are made to orient to that perception of the visual world. For example, imagine a patient who has suffered a left cerebral vascular accident (CVA) with right hemiparesis and right hemianopsia. This patient will be observed to weight bear left. A shift of the visual perception of their midline to the non-affected side will often be found. A mismatch results between the visual perception of self, spatial relations and the physical and kinesthetic feedback received. Since vision is the dominant sense attempts are to orient to the visual perception. As a result, VMSS will cause, and / or, exacerbate problems with balance, orientation and mobility. VMSS can also be found in patients showing extensor and flexor postures. In these cases the VMSS will be shifted either up, or down.

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