Vision Related Side Effects of Traumatic Head Injury

• Field Loss
• Hemianopsia (Loss of half of the field of view to the right or left
• Quadranopsias ( Loss of about 1/4 sector of the visual field)
• Central Loss
• Sector Loss
• Peripheral Loss
• Total Loss of Visual Field
• Attitudinal Losses
• Photophobia
• Reading Disorders
• Diplopia - Exotropia, Esotropia and Hypertropia
• Cranial Nerve Paresis / Paralysis III ,IV, VI , VII
• Small changes in refractive errors more significant
• Nystagmus
• Lagophthalmos
• Dry Eye - Decreased Blink Rate
• Visual Hallucinations
• Formed - Objects
• Unformed - Stars, Lightning Bolts
• Anisocoria
• Accommodative Problems
• Convergence Problems
• Eye Movement Disorders, Fixation, Pursuits
• Frequent Headaches
• Unstable Ambient Vision
• Visual Perceptual Disturbances
• Disturbances in body image
• Disturbances of spatial relationships
• Right - Left discrimination problems
• Agnosia - difficulty in object recognition
• Apraxia - difficulty in manipulation of objects
• Memory Loss
• Psychological problems

Modified from a list by Allen Cohen, O.D. and Lynn Rein, O.D.

Reading Problems & Traumatic Brain Injury

Reading problems may occur from various problems after a stroke or head injury. It is crucial that the type of reading problem be diagnosed. The list below contains some of the more common causes of reading problems after brain injury with introduction to how they may be treated. The problems may occur individually or be part of a constellation of problems related to Post Trauma Vision Syndrome. Treatment of PTVS through various neuro-optometric rehabilitative interventions may resolve many of the problems below.

Post Trauma Vision Syndrome

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 bi-nasal 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).

Reading Problems Due to Visual Field Loss Field loss patients often lose their place in reading. Simple techniques, like boundary marking, sticking a Post-it note along the side of a column of print, can mark the beginning or end of the column and reduce confusion. A right hemianopsia patient may lose his or her place at the end of a line. The right hemianopsia patient may leave off words at the end of a line. A left hemianopsia patient may have difficulty at the start of each line and may not return to the very beginning of the line. Convergence Disorders Affecting Reading Patients may experience reduced convergence after stroke or head injury. Our eyes must turn in together accurately as a team to prevent double vision and eye fatigue in reading. Prisms may aid some patients. Orthoptic therapy may aid some, but not all patients with convergence insufficiency will respond fully to therapy due to the variation in the extent of trauma which may be present.

Loss of Accommodation (Focusing) Affecting Reading

Young head injury patients may experience decreased focusing ability. It is often missed because at an early age doctors don't expect loss of accommodation. It happens naturally at about age 42. Individual with reduced accommodation may benefit from bifocals. Alexias /Word Blindness Affecting the Ability to Read If the patient is unable to read due to damage to areas which process reading, but can understand verbal reading, electronic machines are available such as the Kurzweil Omni 1000 and 3000 and the Zerox Expert Reader. These machines scan all typed print, interpret it and read it aloud to the patient. Talking books and reading radio are also very helpful. Loss of Cognitive Skills May Affect Reading and Comprehension Patients may need to relearn their reading skills developed in childhood or the damage may online pokies be so severe as to preclude reading. Therapists may be able to re-establish reading over time. Low Vision Causing Reading Problems When visual acuity is significantly impaired, high add bifocals or low vision devices may be indicated. Magnifiers, Electronic Magnification CCTVs, special and microscopic eye wear may help the patient read again. Diplopia Causing Disruptions to Reading If the binocular vision problem can be treated, therapy, surgery or prisms may be used to re-establish binocular vision. If the double vision is not curable, then occlusion may be required. Partialsemi-opaque occlusion may reduce diplopia while minimizing the disruption to to ambient vision caused by total opaque. Eye Gaze Disorders Patients with inferior gaze paresis may not be able to look down into the bifocal, but may read with single vision reading eyewear. Clip on reading lenses or single vision reading lenses may also employed. Eye Movement /Tracking Disorders Affecting Reading Eye movement disorders may also interfere with reading. As we read down a line of words, we must make a series of accurate saccades or jumps from one group of words to another. As our head or the paper moves, we must make rapid adjustments of our eye position called pursuit movements. These rapid eye movements are mediated by the vestibular system. Failure of these movements to work smoothly may impair smooth comfortable and may cause vertigo effects.

Unstable Ambient Vision Brain injury patients may present with vertigo, sensitivity to light and extreme sensitivity to motion around them. Trying to sustain reading becomes very difficult. The patient may experience nausea, loss of attention, difficulty fixating on the words and fatigue. Unstable ambient vision is a hallmark of Post Trauma Vision Syndrome.

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.

The Phyisiology of Double Vision New Occlusion Techniques

Thomas Politzer, O.D., FCOVD, FAAO

Diplopia is a serious and intolerable sequelae to the problems of strabismus, ophthalmoplegia, gaze palsy, and decompensated binocular skills that occur in patients with head injury, stroke and other neurologically compromising conditions.

According to Morgan (1948) diplopia is, "the ocular condition characterized by the use of one eye for fixation while the other eye is directed to some other point in the field of vison." According to Gunter von Noorden (1990), "Heterotropias are manifest deviations not kept in check by fusion."

Etiology and incidence of diplopia

Causes of Strabismic Deviation

1. Donders: Abnormal accommodative /convergence ratio and hyperopia

2. Duke-Elder: Failure in the development of the secondary fixation reflex; disruptions of the central, peripheral and postural oculomotor mechanisms; and impaired development of the optical, sensory or motor systems

3. Scobee: Innervational, accommodative, mechanical, functional, sensory and motor anomalies
Factors Responsible for Devaiations (von Noorden 1990)
Disruptions of Motor and Sensory Fusion
Mechanical / muscular anomalies
Structural anomalies
Accommodative and refractive factorsNeurologic factors
Paretic elements Anomalies of the brainstem
Anomalies of convergence and divergence
Vestibular abnormalities
Anomalies of the visual pathways
Brain damage
Facial and orbital deformities
Causes of paralysis of CN III, NIV, and N VI palsies (%) (Rush and Younge 1981)
Cause III IV VI
Undetermined 23 36 27
Head Trauma 16 32 17
Neoplasm 12 4 15
Vascular 21 19 18
Aneurysm 14 2 4
Other 15 8 18
Acquired third nerve palsy (Parks 1990)
Brainstem lesion
Inflammatory conditions (meningitis, encephalitis)
Vascular (Aneurysm)
Tumor
Demyelinating disease
Trauma
CN III paralysis

The eye will be in a position of abduction, slight depression, and intorsion. Ptosis from paralysis of the levator palpebrae and possible slight proptosis. Motility limited abduction, small degrees of depression while abducted, incycloduction, and adduction that does not go beyond the primary position.
CN IV paralysis
Vertical deviation. No motility of depression when adducted. Head tilt.
CN VI paralysis
Vertical deviation. No motility of depression when adducted. Head tilt.
CN VI paralysis
INO (Internuclear ophthalmoplegia)
Esotropia and loss of lateral gaze to the contraleteral side. Binocular internuclear ophthalmoplegia causes
esotropia and bilateral loss of lateral gaze.
Strabismus can result from an injury or anomaly of the visual cortex and pathways; midbrain nuclei; cranial nerves (III, IV, and VI); brainstem; origin, insertion and/or innervation of the extraocular muscles; vestibular system; refraction; orbital deformities and the effects of orbital space occupying lesions. Acquired nerve palsies which cause strabismus and diplopia can result from head trauma, neoplasm, vascular disease, aneurysm, brainstem lesions, inflammatory conditions (e.g. meningitis and encephalitis) and demyelinating disease.
Historical treatment of diplopia
Methods
Efficacy
Ramifications of patching
Prisms, lenses, vision therapy, surgery and pharmacologic measures have been used to help patients achieve fusion (alignment of the eyes) and alleviate diplopia. Some patients will adapt by suppressing the vision of one eye to eliminate their diplopia. If treatment is not successful and the patient does not suppress vision in one eye, intractable diplopia ensues.

Although several treatment modalities (refractive, orthoptic, surgical, and pharmacologic) are available for strabismus, the treatment of third nerve palsy and paralytic strabismus remains a challenge. von Noorden, writes, "The surgical management of a complete N III paralysis is a formidable challenge to the ophthalmologist, and the therapeutic possibilities are limited. At best, the surgeon will succeed only in moving the paretic eye into the primary position without restoring adduction, elevation, or depression to a significant degree." Parks, regarding treatment for third nerve palsy says, "Treatment involves relief of the patients diplopia. Occlusion is the best solution for the patient's diplopia."

In the population of neurologically compromised patients, patching has frequently been used to eliminate diplopia. Although patching is effective in eliminating diplopia, it creates problems by rendering the patient monocular. The chief problems of monocular vision are loss of stereopsis and reduction of peripheral visual field.

Compared to binocular vision, monocular vision results in roughly a 25% decrease in the field of vision, absence of stereopsis, decreased visual acuity (due to a lack of binocular summation) and impaired spatial orientation. Monocular individuals are disadvantaged in visual motor skills, exteroception of form and color, and appreciation of the dynamic relationship of the body to the environment, which facilitates control of manipulation, reaching and balance.
Problems from monocular vision will manifest as difficulties in eye hand coordination, clumsiness, bumping into objects and / or people, ascending or descending stairs or curbs, crossing the street, driving, various sports and other activities of daily living which require stereopsis and peripheral vision.

Preferred methods of treatment
Prisms
Fusion training
Selective partial occlusion (spot patch)
A new method of treating diplopia that does not have the limitations of traditional patching has been successfully evaluated. The "spot patch" is a procedure that eliminates diplopia without compromising peripheral vision. It is a small, usually round or oval, patch made of 3-M TransporeTM 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, ophthalmoplegia, or gaze palsy. Final size and placement is determined by evaluating different sizes and shapes to arrive at the smallest one, which effectively eliminates the diplopia.
The "spot patch" works because it effectively eliminates central vision in the partially occluded eye. Diplopia is perceived as a central visual phenomena when the visual axes do not align. The size of the diplopic zone is not known for certain, but is believed by this author to correspond to Panum's fusional area, which is approximately 25 by 25 minutes of arc. Diplopia does not seem to be perceived outside of this zone.
Central vision is necessary for examining small areas of detail, visual acuity and stereopsis. Peripheral vision is necessary for evaluating space in general around the body, motion detection, orientation and mobility. With the "spot patch" central vision is sufficiently blurred so as to eliminate the diplopic image, but not so much as to completely eliminate vision. Since peripheral vision is not eliminated with the "spot patch" the patient does not lose peripheral fusion, visual field, or many of the visual components of orientation, balance and mobility.

Double Vision - Treatment Options

Double vision (diplopia) is one of the most troublesome visual disorders a patient can experience. The ability to read, walk and perform common activities is suddenly disrupted. The management of double vision may include prisms, orthoptics, therapy, eye muscle surgery and occlusion. The goal is to establish clear binocular single vision. Double vision management may require any combination of these therapies.Since some patients may recover function over time, surgery may be not be considered initially. Prisms should be used when it aids the patient in eliminating double vision. Press-on prisms may be applied to the patient's lenses toreduce double vision. Orthoptic therapy may be indicated in many cases. When diplopia causes significant discomfort, and is not responsive to other therapies, occlusion may be used. Unfortunately many clinicians are still prescribing black "pirate" patches. These are rarely required. New methods of occlusion are now available

Double Vision Unresponsive to Orthoptics, Prism and Surgery While the goal is always to reform comfortable, functional binocular vision, this is not always possible. Some patients experience severe functional problems due to constant or intermittement double vision.

• The Phyisiology of Double Vision New Occlusion Techniques

More Articles...

• Light Sensitivity and Brain Injury
• Eye Movement / Tracking Disorders
• Implications of Acquired Monocular Vision (Loss of one eye)

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