UNDERSTANDING THE RELATIONSHIP BETWEEN ......Rubs eyes Eyes water Complaints of blurred vision Relationship of Optical Problems to Learning Nearsighted children tend to be the best - [PDF Document] (2024)

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UNDERSTANDING THE RELATIONSHIP

BETWEEN

VISION DEVELOPMENT AND LEARNING

SHARON L. SNIDER, O.D., F.C.O.V.D.

Fellow, College of Optometrist in Vision Development

4000 Meadow Lake Drive; Suite 121 Birmingham, AL. 35242

Snider Therapy Centers, Inc.

www.snidertherapy.com

(205) 408-4414

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Section 1

Vision: A Clinical Model

Three Component Model of Vision

Refractive Skills

Visual Information Processing Skills

Visual Efficiency Skills

I. Refractive (Optical) Skills

This component of the three-part model of vision deals with the ability of the eyes

to see clearly at all distances. This refers to optical conditions which may cause

blurred vision at distance, near, or both distance and near.

1. Nearsightedness (myopia) is a condition in which vision is blurred at distance

but clear at near. Unless severe, myopia generally doesn’t interfere with

learning. It may interfere with motor development and difficulty

interacting with the environment in very young children if not identified

early.

2. Farsightedness (hyperopia) is a condition in which the individual must use

more effort to see at near. To see clearly a person with hyperopia must

contract the ciliary muscle to change the shape of the lens in the eye and

regain clarity.

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Very high degrees of hyperopia cannot be overcome and result in blurred

vision. If not corrected early such problems can lead to amblyopia (loss of

vision) and difficulty interacting with the environment.

3. Astigmatism is a condition in which vision is blurred and distorted at both

distance and near. Low degrees of astigmatism can be overcome by

focusing the eyes. High degrees of astigmatism cannot be overcome.

If not detected and corrected early, significant degrees of astigmatism can

lead to amblyopia and difficulty interacting with the environment.

Symptoms of Optical Problems

Nearsightedness

Squints

Complains of blurred vision far away

Gets close to board

Farsightedness and astigmatism

Discomfort associated with reading

Rubs eyes

Eyes water

Complaints of blurred vision

Relationship of Optical Problems to Learning

Nearsighted children tend to be the best readers and learners in

school. Their vision is clear when reading and because they

complain about not being able to see the board well, their needs

are usually quickly addressed.

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Children with farsightedness and astigmatism often go undetected

because they have relatively clear vision. Because of the effort

needed for them to see clearly, however, they can experience

eyestrain, blurred vision when reading, inability to attend and

concentrate for adequate periods of time, and reduced reading

comprehension.

Note: Hyperopic children, even those with moderate hyperopia, are much

more susceptible to delays in visual perceptual skills development than

emmetropic children, and the latter in turn, are more susceptible than

myopic children.1

Treatment

Eyeglasses to correct the refractive error

Related Condition

Amblyopia – When the two eyes have significantly different refractive

errors, the brain may respond by suppressing the information

received from one eye producing an eye with decreased acuity.

This is called refractive amblyopia.

Treatment – 1. Eye glasses to correct the refractive error

2. Vision therapy to restore visual acuity to potential

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II. Visual Information Processing Problems

These are problems that interfere with an individual’s ability to analyze and

interpret visual information.

Visual processing disorders include:

Laterality and directionality disorders

Visual form perception disorders

Visual memory disorders

Visual motor integration disorders

A. Laterality and Directionality Disorders

Laterality relates to the internal awareness of the two sides of the body,

directionality to projecting this awareness into external space.

Symptoms

1. difficulty learning right and left

2. reverses letters and words when writing or copying

3. may read either left to right or right to left

B. Visual Form Perception and Discrimination Disorders

This involves the ability to discriminate dominant features in different

objects: for example, the ability to discriminate position, shapes and

forms.

Symptoms

1. confusion of likenesses and minor differences

2. mistakes words with similar beginnings

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3. difficulty recognizing the same word repeated on the same page

4. difficulty recognizing letters or even simple forms

5. difficulty determining what is significant from what is insignificant

C. Visual Memory

This is the ability to recall dominant features of a stimulus item or to

remember the sequence of several items.

Symptoms:

1. difficulty visualizing what is read

2. poor comprehension

3. difficulty learning new material

4. poor spelling

5. poor recall of visually presented material

6. difficulty with tasks that require more than one step

7. difficulty with mathematical concepts

D. Visual Motor Integration

The ability to integrate visual discrimination with the eye-hand

coordination system to motorically reproduce a pattern from a model.

Symptoms:

1. sloppy writing or drawing skills

2. poor spacing and inability to stay on lines

3. excessive erasures when doing written work

4. can respond orally but cannot get answers on paper

5. seems to know material but does poorly when tested

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Relationship of Visual Processing Problems to Learning

Children with visual perceptual problems may be difficult to teach, failing

to understand and grasp basic concepts and ideas. These problems

interfere with efficient learning and may seriously impair an individual’s

ability to respond to standard instruction.

1. Visual processing problems tend to interfere with performance in the

early grades. Even in kindergarten and first grade it becomes

apparent that these children are experiencing difficulty.

2. Children with visual perceptual problems may be difficult to teach,

failing to understand and grasp basic concepts and ideas.

3. Poorly developed laterality and directionality may result in significant

problems with reversals.

4. Form perception and discrimination problems may result in the child

having difficulty learning the alphabet, word recognition and basic

math concepts of size, magnitude and position.

5. Visual memory problems may contribute to poor comprehension,

spelling, and sight vocabulary.

6. Visual motor integration difficulties may manifest in poor written work

or unusually long periods of time necessary to complete written a

assignments.

Treatment

Vision therapy to remediate the visual aspects of processing dysfunction

Occupational therapy to remediate fine and gross motor movements of the

body

III. Visual Efficiency Problems

These are problems that interfere with an individual’s ability to clearly and

comfortably gather information through the visual system over long periods of

time.

Visual efficiency disorders include:

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Binocular vision (eyeteaming) problems

Accommodative (focusing) problems

Ocular motility (tracking) disorders

A. Eyeteaming Disorders (Binocular Vision Disorders)

Binocular vision or eyeteaming disorders refer to a variety of conditions in

which the eyes drift inward, outward, upward, or downward. If such a

turning occurs it may result in the experience of double vision. To prevent

this double vision form occurring, the child will use excessive muscular

effort. This muscular effort can lead to eyestrain, blurry vision,

discomfort, inability to attend/concentrate, and poor reading

comprehension.

Symptoms of Eye Teaming Problems

Discomfort associated with reading

Intermittent double vision

Closes or covers one eye

Letters or words appear to move

Loss of place

Inattentiveness

Rubs eyes

Complaints of blurred vision

Eyes water

Relationship of Eye Teaming Problems to Learning

The effort associated with trying to overcome eyeteaming

problems can lead to eyestrain, blurry vision, discomfort, inability

to attend and concentrate and poor reading comprehension.

Binocular vision problems are more common in physically,

mentally, and developmentally delayed children, learning disabled

children and adults and children who have had CVA or TBI.2

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B. Focusing Problems (Accommodative)

Focusing problems refer to a set of conditions in which the person has

difficulty focusing or relaxing the focusing system of the eyes. There are

three primary types of focusing disorders:

Focusing insufficiency – an inability to focus the eyes to see small

detail at a close working distance.

Focusing excess – a condition in which the person is unable to relax

the focusing system.

Focusing infacility – a condition in which both focusing and relaxing

are difficult for the patient.

Symptoms of Focusing Problems

Blurred vision when looking from board to book or book to board

Holds things very close

Headaches when reading

Fatigue at end of day

Discomfort associated with reading

Rubs eyes

Eyes water

Complains of blurred vision

Relationship of Focusing Problems to Learning

Focusing disorders generally cause inattentiveness, eyestrain, and

discomfort when involved in any task requiring precise vision.

C. Tracking or Eye Movement Disorders

The primary type of eye movement problem that relates to school

performance is called saccadic dysfunction. This refers to a condition in

which the person’s ability to scan along a line of print and to move his

eyes from one point in space to another is inadequate.

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Symptoms of Tracking Problems

Excessive head movement when reading

Frequent loss of place

Skips lines when reading

Uses finger to maintain place

Poor comprehension when reading

Short attention span

Relationship of Tracking Problems to Learning

Eye movement problems can interfere with almost any school

activity requiring vision. Performance will be affected because the

child will be unable to consistently make accurate eye movements

to look from one point in space to another. This will affect his

ability to gather information and respond correctly.

Summary of Effect of Visual Efficiency Problems on Learning

1. All of these conditions have the potential to interfere with the ability to

concentrate and sustain at any visual task such as reading. Children with

visual efficiency problems complain of eyestrain, headaches when

reading, blurred vision and occasional double vision.

2. Visual efficiency problems tend to interfere from grades 3 and older when

children have already learned to read and are now reading in order to

learn.

3. Children who only have these problems tend to perform acceptably for the first

few grades.

Treatment

Vision Therapy

Adjunctive Occupational Therapy

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Related Conditions

Strabismus – Strabismus is the name of the condition when a manifest (or

cosmetically noticeable) eye turn is present. One or both eyes may

be involved. The eye turn can be intermittent or constant. If

constant, strabismic amblyopia may develop. Depth perception

will be reduced or nonexistent.

Treatment:

1. Eye glasses if indicated

2. Vision therapy for amblyopia when present

3. Vision therapy to correct eye turn when indicated

Exotropia (outward eye turn) – high success rate

with vision therapy alone

Esotropia (inward eye turn) – moderate success rate

with vision therapy alone

4. Surgery – when indicated

Functional success rate – 11%

Cosmetic success rate – approximately 40%

Roughly 40-50 % of strabismic surgeries have to

be repeated at least once.

IV. Prevalence of Ocular Conditions for the Pediatric Population

Study Methods

Mitchell Scheiman, OD, Journal of the American Optometric Association, April 1996

Conducted at Eye Institute of the Pennsylvania College of Optometry 6-month period of time 2,023 consecutive patients Age range: 6 months and 18 years

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Prevalence of ocular conditions for the pediatric population as a whole

Hyperopia (24.8%)

Astigmatism (22.5%)

Myopia (17.6%)

Non-strabismic binocular disorders (eye teaming, focusing, tracking)

(14.3%)

Strabismus (11.9%)

Amblyopia (7.1%)

Ocular disease (3.4%)

Conditions with significant difference by race

Caucasian Black Astigmatism 20.0% 24.3%

Convergence excess 8.4% 6.0%

Intermittent exotropia 2.8% 5.0%

Corneal problems 0.1% 0.8%

Retinal problems 1.1% 2.4%

Conditions with significant difference by age

below age 6 greater than age 6 Hyperopia 33.0% 23.0%

Myopia 9.4% 19.6%

Convergence insufficiency 1.6% 5.3%

Convergence excess 2.1% 8.2%

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Accommodative infacility 0% 1.5%

Accommodative excess 0.3% 2.2%

Intermittent esotropia 5.4% 1.4%

Intermittent exotropia 5.6% 3.3%

Constant esotropia 7.5% 3.9%

Retinal problems 0.5% 2.1%

V. Optometric Treatment Methods

A. Uses of Lenses

When are lenses effective?

a. refractive error: nearsightedness, farsightedness, astigmatism

b. some types of focusing disorders

c. some types of eyeteaming disorders

B. Use of Prism

When is prism effective?

a. some eyeteaming disorders

b. used primarily during aggressive vision therapy procedures

C. Vision Therapy

What is vision therapy?

Vision therapy (also known as orthoptics, vision training, visual training,

eye training) is an organized therapeutic regimen utilized to treat a number

of neuromuscular, neurophysiological, and neurosensory conditions which

interfere with visual function.

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Vision therapy encompasses a wide variety of procedures to improve a

diagnosed neuromuscular, or neurophysiological visual dysfunction. The

treatment can be relatively simple such as patching an eye as part of

amblyopia therapy, or it may be complex involving sophisticated

instrumentation and computers.

Vision therapy usually involves a series of treatment visits during which

carefully planned functional activities are carried out by the patient under

close supervision in order to relieve the visual problem. The specific

activated and instrumentation are determined by the nature and severity of

the condition. The frequency and duration of treatments are dictated by the

individual situation, although established guidelines are available

suggestions appropriate length of therapy for various diagnoses.

When is vision therapy necessary?

Most vision problems can be very easily corrected with eyeglasses. In fact

about 90% of the people who complain of vision problems are treated with

glasses or contact lenses which enable them to feel and see better.

However, approximately 10% of the population with symptoms of blurred

vision and eyestrain have vision problems which cannot be treated

successfully with eyeglasses alone. It is this group of people who need

vision therapy. Vision therapy is generally required to treat problems of

eye teaming, focusing, tracking, lazy eye, strabismus (crossed eyes), and

visual perception. Individuals with these problems experience eyestrain

when reading or doing other close work, inability to work quickly,

sleepiness, inability to attend and concentrate, double vision, and loss of

vision. Even more significantly, children with “lazy eye” and strabismus

face the possible loss of vision if an appropriate vision therapy program is

not initiated in a timely fashion. Children with visual perceptual problems

may have difficulty learning.

Is vision therapy effective?

There is extensive clinical and scientific support for vision therapy as a

treatment modality. Most of this support is in the optometric literature

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since most of the development of vision therapy has been done by

optometrists. An article entitled “The Efficacy of Optometric Vision

Therapy” addresses this issue. This study includes over 200 supporting

studies of vision therapy. (If you would like a copy of this article, contact

me at 408-4414).

This article and many others indicate that there is sufficient scientific

support for the effectiveness of vision therapy in modifying and improving

oculomotor (eye movement), accommodative (eye focusing), and

binocular (eye coordination) disorders. Such improvement can be

measured using standardized clinical and laboratory testing methods.

Visual skills

like all physical skills

can be taught, trained, practiced, and enhanced.

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Directories of Optometrists with Expertise in Vision Therapy

College of Optometrists in Vision Development (COVD)

243 N. Lindbergh Blvd., Suite310

St. Louis, MO 63141-7851

314-991-4007

www.optom3.com/covd/index.html

COVD is a professional organization of behavioral and developmental optometrists and has the

authority to board-certify doctors of optometry in this field. A Fellow with the College of Optometrists

in Vision Development, has proven his/her level of clinical expertise in the area of vision

development.

American Academy of Optometry

4330 East West Highway, Suite 1117

Bethesda, MD 20814

301-718-6500

AAO is a professional organization of optometrists with the authority to test and board

certify doctors in various areas of expertise including binocular vision and visual perception

disorders. A Diplomate in Binocular Vision is earned by those doctors who have proven their level

of expertise in the field of binocular vision and vision therapy.

Neuro-Optometric Rehabilitation Association, International (NORA)

3956 J Street, Suite 4

Sacramento, CA 95819

www.nora.cc

NORA is a group of professionals with the mission of increasing the awareness of the art and

science of rehabilitation for the neurologically-challenged patient.

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Parents Active for Vision Education (P.A.V.E.)

9620 Chesapeake Drive, Suite 105

San Diego, CA 92123-1324

619-467-9620

www.pave-eye.com/vision

PAVE is a non-profit resource and support organization whose mission is to raise public

awareness of the crucial relationship between vision and achievement.

Optometric Extension Program Foundation (O.E.P.)

1921 E. Carnegie Ave., Suite 3-L

Santa Ana, CA 92705-5510

714-250-8070

www.healthy.net/oep

OEP is one of the main suppliers of brochures, textbooks and testing materials for vision and

vision therapy related subjects in the optometric field.

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Section 2

Vision: The Process - A Developmental/Behavioral Model

Goal: To understand that visual skills like all physical skills can be taught, trained,

practiced, and enhanced.

Vision is learned!

Developmental Anatomy

The nerve layer of the eyeball develops from the same tissue as the brain cortex

(neuroectoderm) which means that the eyeball is neurologically the end

result of developing brain tissue.

The study of neurology has shown that there are more than one million nerve

fibers that exit each eye.

This represents approximately 70% of the sensory nerve fibers in the entire body.

A major amount of information is received by the cortex through the eyeballs

each second.

From this information, we can begin to understand the profound importance of vision as a

process affecting the development of the child and the learning process.

Note: The term “vision” does not mean “eyesight”. Eyesight is an innate, physical

characteristic of an individual. Eyesight simply means the level of visual acuity

present with best optical correction.

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Developmental Model of Vision

In the previous section, a clinical model of vision was presented. That model is useful in

understanding the various anatomical components of the eye and associated visual

dysfunctions as well as the affect of developing visual information processing skills.

Vision is an entity however that can be explored and evaluated using another model. The next

model which will be presented is that of a developmental or behavioral model of the vision

process.

According to researchers in the field of developmental psychology, the visual system is

composed of not one but two components:

a focal process

an ambient process

The focal process also can be subdivided into two components – a central

pathway and a peripheral pathway.

The central focal process is mediated primarily through an area of the

retina termed the macula which has the potential for the highest visual

acuity due to the high concentration of cone cells in this area whose

primary function is in color detection. Nerve fibers from the central

retinal leave the eye and emanate to central areas of the visual cortex.

The peripheral focal process is mediated by the peripheral area of the

retina which is mainly composed of rod cells. The rod cells are more

important in lower light situations and movement detection. Nerve fibers

from the peripheral retina proceed to the peripheral areas of the visual

cortex.

(To borrow a line from an infomercial - But Wait! There’s More!)

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The ambient process unlike the focal process is a subcortical pathway.

Eighteen percent (18%) of the nerve fibers from the retina do not proceed

to the visual cortex of the brain but instead proceed to an area of the brain

termed the midbrain and then continue to the higher areas of the cortex.

This means one –fifth of the retinal fibers are not involved with the

process of eyesight! Instead, these fibers link up with nerve fibers from

both the inner ear and somato-sensory signals. (In plain English)This

means that signals from the eyes, ears, balance and muscle systems merge

at this level of the brain. The body uses this information to orient itself in

space through posture and movement.

The discovery of the ambient process with its sensory-motor feedback

loop matching information from the eye to information from kinesthetic,

proprioceptive, vestibular, and tactile systems reveals the intimate

relationship that the visual process has with posture, movement, balance,

and spatial orientation.

Why does an individual need three different retinal pathways?

For an individual to interact efficiently with his environment, three questions must be

answered:

Where am I?

Where is it?

What is it?

“Where am I?” is answered by the ambient system for awareness of body sense.

“Where is it?” is answered by the peripheral focal system to make judgments of

speed, movement, location, size, and shape.

“What is it?” is answered by the central focal system to make judgments of

detail and color.

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Each retinal pathway answers a separate question by electrical signals that travel at different

speeds. Therefore, the sensory visual cortex receives three retinal pieces of information.

The first piece is a reflex creating stability.

The second is peripheral information helping organize space and time.

The third piece of information regards detail and color.

Balance Pathway Peripheral Pathway Central Pathway

Ambient Peripheral Focal Central Focal

Where am I? Where is it? What is it?

Subcortical Reflex Unconscious Cortical Conscious Cortical

The fastest reflex signal Fairly fast pathway Slower pathway

Clinical Pearl: In learning-related vision disorders and dyslexia for example, the peripheral and

central signal speeds are not in synchrony which impairs the individual’s judgment ability.

Neuro-optometric rehabilitation can alter this asynchrony through the use of lenses,

filters, and prisms.

(Because I have an intact visual system, I can use my ambient and focal vision to deal with the

world around me, paying attention to a peripheral or a central stimulus according to my need at

the moment. An example of this is being able to spot a garage sale sign while driving and

carrying on a conversation with my mother-in-law at the same time.)

(Let me give you another example of the interrelationships between the various systems in the

brain. How many of you have noticed that when you take your glasses off, you have a difficult

time hearing? I know I do. This is an indication that the vision process is needed in order to

match information coming in from the auditory process.)

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(Another example concerns balance. I would like for you to all stand and balance on one foot.

Now, I want you to close your eyes and continue balancing on one foot. Did the act of balancing

become more difficult for any of you? It does for many people because the ambient visual

system is such an important part of balance.

(As a child during church services, I loved to peek whenever the pastor asked us to close our eyes

during prayer because suddenly a good many of the adults would start to sway. They couldn’t

maintain their balance with their eyes closed. All right, I’ll admit it – I still occasionally peek!)

Example of child with poor ambient system – the child is unable to walk backwards/ no concept

of the world that surrounds them.

Another example of the effect of the ambient system on the body. Research conducted on blind

individuals has shown that even though blind their biological clocks are intact. However, if the

blind individual’s eyeballs were also removed, the biological clock malfunctions. This also is an

indication of the importance of the ambient system on body function, even though sight was not

present.

(OK, let’s continue with how all of this information relates to vision development in the child.)

Normal Vision Development in the Child

The process of vision is established through the motor system. It is the motor component of

vision that develops first and provides information about spatial position. The kinesthetic and

vestibular systems are very important in developing ocular-motor control. This loop begins

development at 4 months in utero with the development of the ambient visual system.

The eye is constantly in movement due to constant minor flicks and tremors of the ocular

muscles. As a result, the image of the environment on the retina is never stable.

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Researchers found that if the eye muscles are temporarily paralyzed with a drug, sensory

imagery ceases. This is yet another proof that the sensory function of vision (eyesight) ceases

when the motor component of vision is paralyzed.

An infant’s earliest visual attention is normally directed at fixating a light source utilizing the

focal system. The ambient visual process matches information in the sensory motor feedback

loop and provides spatial orientation which enables the infant to develop a focalization on the

outstretched hand. This is the first time the infant is able to match information received

through one sensory modality (vision) with another (kinesthesia and proprioception). This

begins process where the infant begins to develop the process of restricting visual awareness to

a particular aspect of time and space rather than operating in a continued state of sensory scan.

With time, an ability to control the ambient and focal states will develop.

In a newborn infant, the vision signals from the macula (focal system) are not as distinct as they

will become several weeks later. Instead it is the infant’s ambient system that is allowing the

child to organize his motor function to gain control of limbs, head movements, etc.

As motor function becomes organized, the focal process of vision develops in an attempt to

refine motor function. These motor experiences in turn later provide a base for higher level

sensory discrimination. The ability to match information between the senses and the motor

processes yields coordination of motor function.

Normal development continues in a series of cycles. When a cycle is repeated, the infant uses

his newly acquired abilities to examine his environment in a new way.

Note: When development is abnormal, whether due to conditions such as chronic ear

infections, trauma, disease, or structural defects, there is a mismatch between the ambient and

focal systems. The two systems are not balanced.

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Time, Space, and Movement

The development of concepts of space and timing are important to the overall development of

the child. Depth perception has been studied for years, certain factors are innate (Kitten-plexi

glass experiment) Other experiments showed that the visual process of depth perception was

established through the structure and reinforcement of the motor system.

Movement is critical to the development of spatial-visual relationships. Movement must also

be related to the development of time relationships. Time is represented by how long it takes

the child to go from one point to the next. This information is then matched with new auditory

and/or visual information to enable him to judge how long it will take to move from one point

to another. This process uses higher level sensory processing. However, the basis of this

interpretation lies in the experiences that were matched between motor and sensory

processes. Once again, this shows that vision is learned.

A multi-handicapped child who has lacked the appropriate experiences with time and space will

not be able to match information appropriately between the motor and sensory process,

particularly vision.

Posture and Vision

In order for the eyes to develop good-quality movement, they also need a stable base which is

provided by motor control of the neck in all positions of space. The growing ability of the baby

to monitor the position of the head permits more consistent visual examination of interesting

objects in the environment. As adults, we adapt the head position to meet our visual needs by

means of change in the neck alignment.

As the infant is more upright in space, vestibular reactions begin to lead the balance or

equilibrium together with the ambient visual process. A child with impaired vision or with

distorted functional vision will not exhibit proper postural control and may experience fear of

new situations that lack predictability for the child. This in turn may reduce the child’s

desire/ability to experiment with postural control which is a part of normal development. The

world does not automatically beckon such children to participate. These children need to be

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given vestibular proprioceptive experiences in play that stimulate their interest in movement

and build confidence in their own body.

Without an organized postural system, the sensory-motor data acquired by the child from his

environment remains fragmented and fairly disorganized. The problem is seen clearly in

children with learning problems who demonstrate postural disorganization. Their central

nervous system has never succeeded in relegating postural reactions to the automatic level.

These youngsters are constantly distracted from an immediate task by their need to

concentrate on maintaining body balance on a chair or moving themselves across the room.

The child’s style of vision continues throughout life. Whatever patterns are established by the

way a person utilizes the focal and ambient functions are reinforced through motor

relationships. Perceptual aspects of vision are very much influenced by the motor functions of

this process. This creates a dynamic model of vision which is quite different from the sensory

or classic medical model which is often used to describe vision.

(Actually, the medical model does not describe “vision”, but “eyesight”.)

What is the benefit of understanding this model of the vision system?

(To paraphrase, why have you sat through this lecture)

This dynamic model of vision, which is a developmental or behavioral model, can provide us

with new insights into posture and movement which are of primary importance when

considering the development of a child or of multi-handicapped and traumatic brain injured

individuals.

The medical model of vision (which has reigned for decades) categorizes vision and visual

deficits based on the structure of the eye and its affect on eyesight without taking into

consideration the function of the eye as a part of the whole body.

For example, using a medical model, the condition of strabismus is generally described as an

eye turn due to an over- or underacting eye muscle. Therefore, the only obvious treatment to

correct a structural defect is surgery. Never mind that strabismics surgery is functionally

successful in only one of ten patients!

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A medical model is unable to explain the following scenario. It has been noted that many times

a strabismic eye will straighten for a short period of time when the child grasps the examiner’s

hand and is lifted off his feet. What happened to the over- or underacting eye muscle that

supposedly required surgery? A developmental model, being aware of the relationship

between balance and function, would suggest that an anomaly of visual development had

occurred and can possibly be treated by changing sensory and motor relationships.

Of Clinical Interest: Many individuals with acquired brain-injury suddenly develop

strabismus and eye teaming disorders. Rarely were the ocular muscles actually injured,

instead the injury occurred in an area of the brain vision involved with vision processing.

Obviously, strabismic surgery would not (or should not) be indicated for these patients.

The same holds true however for most strabismic patients, whether acquired during

normal development or from prenatal/postnatal brain injury.

Facilitating Understanding through the Manipulation of the Visual System

The ambient visual process first facilitates postural information matching with kinesthetic,

proprioceptive and vestibular information. The focal visual process then offers higher sensory

reinforcement together with vestibular orientation.

Understanding time and space relationships is important in understanding the concept of

neuro-optometric rehabilitation. When a mismatch of information occurs between the sensory

and motor processing, particularly vision and motor processing, distortions in experience occur.

When any type of impairment, particularly a motor impairment is involved, processing of

information will be interfered with or distorted. Therefore experience concerning time and

space for a multi-handicapped child will be affected because he will not be able to match

information appropriately between the motor and sensory processes, particularly vision.

Any distortions that occur between time and space relationships due to mismatches with the

visual system may manifest as anomalies in the visual processing system. With time, these

distortions affect future judgments.

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However, since the vision process is learned, this means that vision can also be trained.

(Remember, we are not talking about eyesight, but vision.) Vision therapy as discussed in the

first lecture is one such means of intervention used to train certain aspects of vision. Neuro-

optometric intervention uses vision therapy techniques as well as other procedures which can

change an individuals perception of space, orientation, and time in an effort to rehabilitate the

neurologically-challenged patient.

In discussing neuro-optometric intervention, an important aspect is the use of guided activities

using specific lenses and prisms that will activate and develop the potential to learn through

vision. The concept of the total person is given priority so it is important to provide

opportunities to integrate responses that demand more and better function of the somatic-

proprioceptive-vestibular experiences that can be linked to vision. Vision is not an isolated

function.

When a person is given a guided experience in which the body has to make a postural change

for a brief period of time, therapy is challenging the adaptability of the balance and equilibrium

systems which intensifies the visual-motor learning process.

Therapy directed to the organization of postural responses results in positive behavioral

changes as well as improved fine motor coordination. For example, handwriting control and

better organization of school work is often noted after therapy to correct postural control.

Persons who have suffered a traumatic brain injury (TBI), cerebrovascular accident, aneurysm,

cerebral palsy, autism, multiple sclerosis, etc. will frequently have associated neurological and

physical disabilities. These disabilities may be in the form of a hemiparesis (a dysfunction of the

right or left neuro-motor components of their body) or a hemiplegia (a total dysfunction of one

side of the body). States of flexion (a tendency for persons to lean forward and contract the

anterior portion of their body) or states of extension (a tendency to lean backwards) are

common observations of persons who have a physical diability.

Persons with such affected neuro-motor impairment have been viewed as having a dysfunction

of neurological impairment. Due to the research on the focal and ambient visual systems, it has

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become apparent that after neurological impairment such as a TBI or CVA, mismatches in

neuro-motor/ambient visual processing centers result in what has been termed the Visual

Midline Shift Syndrome.

An individual’s concept of his/her visual midline can shift laterally or anteriorly/posteriorly. This

in turn will cause the person to visually attempt to shift their own body to a point in space

either laterally or anteriorly/posteriorly affecting his/her balance and posture.

One of the most valuable tools for neuro-optometric rehabilitation is yoked prism. Yoked prism

are a type of lens system that when placed over a person’s eyes have the effect of shifting the

person’s center of gravity. The hips shift and the person leans toward or away from objects

depending on the type of yoked prism used. Therefore, yoked prism can be used to counter the

effects of a visual midline shift when used in a prudent, therapeutic program prescribed by a

optometrist trained in neuro-optometric rehabilitation.

Prism also has the effect of altering space. Depending upon the orientation of prism, prisms

make the perception of space appear to constrict or to expand. This optical characteristic of

prism makes yoked prism a useful tool in the neuro-optometric rehabilitation of the individual

with a mismatch in perception of time-spatial relationships.

Of Clinical Interest:

Neuro-optometric rehabilitation should be undertaken in conjunction with

physical and occupation therapy programs, causing rehabilitation potentials to be

maximized. Many occupational therapists have noted that an individual’s balance

greatly improved once neuro-optometric rehabilitation was initiated which greatly

aided the OT’s ability to train the child how to jump and hop.

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Actual cases:

EC, a 4 year old girl diagnosed with autism, had been a toe walker since 3 years old, viewed out

of the side of her eye, unable to color, was clumsy, could not catch or throw a ball. Upon

initiating neuro-optometric intervention, the following changes in behavior were noted:

While wearing yoked prisms, EC can catch and throw a ball

Within two weeks, EC’s mother reported that the child was now starting to draw

and to color independently.

By the 6th session, EC voluntarily jumped over the balance beam in the therapy

room. Mother reports that EC can now hop, a skill that the OT had been

unable to develop until yoked prism therapy was initiated.

KA – is a 6 year old boy tentatively diagnosed with pervasive developmental delay. Easily

distractible by any noise or activity in the room, he was diagnosed with accommodative

insufficiency, overconvergence, and developmental visual information processing delays. KA

rarely communicates with more than a grunt or a clearing of the throat.

After a session where yoked prisms were utilized, KA suddenly began to speak in a normal

conversational fashion with complete sentences for the remainder of the therapy session.

SP – a 6 year old girl with cerebral palsy has farsightedness and strabismus. With the correct

optical prescription, the strabismus had been controlled. However, the glasses no longer had

the same affect, nor did a subsequent pair. Upon the addition of yoked prism to the prescription

to correct for a midline shift noted during a neuro-optometric eval, the strabismus once again

was controlled.

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Summary

Visual disability is the fourth largest handicap in the United States.

Vision is not just 20/20 eyesight and healthy eyes.

The ambient visual process first facilitates postural information matching with kinesthetic, proprioceptive and vestibular information. The focal visual process then offers higher sensory reinforcement together with vestibular orientation.

Vision affects the child’s overall development. Vision is a dynamic, interactive process of motor and sensory function mediated by the eyes for the purpose of simultaneous organization of posture, movement, spatial orientation, manipulation of the environment and to its highest degree, perception and thought.

Neuro-optometric remediation, through the use of guided activities with specific lenses and prisms, can alter the relationship between the central, peripheral, and balance pathways to activate and develop the potential to learn through vision.

Since vision is learned, visual skills skills like all physical skills can be taught, trained, practiced, and enhanced.

Neuro-optometric Rehabilitation/Remediation

Neuro-optometric intervention has been shown to be effective in the treatment of vision and

vision-mediated dysfunctions related to the following conditions:

Amblyopia – refractive and strabismic

Accommodative dysfunctions

Autism

Binocular vision disorders

Cerebral palsy

Developmental Visual Information Processing Delays

Down’s syndrome

Ocular motor dysfunction

Nystagmus

Strabismus

Traumatic brain injury

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Appendix A

Additional Visual Developmental Milestones in the Young Child

When an infant seizes an object with his hands, it is drawn immediately to his mouth –

response indicating the development of form and substance perception. The infant is using

tactile information to reinforce vision. As his visual experiences are reinforced by other senses,

he will no longer need this added tactile input to derive meaningful information about an

object.

24 weeks - the infant immediately releases the object upon touching it to his lips as he now

relies on his visual interpretation of the object and has less need for other sensory

reinforcement.

32 weeks - the infant is able to localize sounds beyond his reach which reinforces the

infant’s visual projections into his space environment. Depth perception however

will need additional experiences in order to develop, which is evident when four weeks

later the infant now has better orientation in space.

Development continues in a series of cycles. When a cycle is repeated, the infant uses his

newly acquired abilities to examine his environment in a new way.

40 weeks - the infant begins to explore the relationships of three dimensions and by one

year the child shows a basic understanding of his three dimensional domain. At this

age, he also shows auditory perception of distant objects. The basic understanding of

three-dimensional space develops through an interweaving of multisensory experiences.

For example, the child sights an object visually, reinforces this sighting with motor

movement involving tactile and kinesthetic input, while integrating auditory

perception of sounds with visual and motor perception of distance. The child’s perception

of space is also observed with the child’s ability to move objects alongside or above another

object.

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15 months - the awareness of the relationships between sights and sounds becomes more

acute as evidenced by a child demonstrating interest in a moving toy especially if

accompanied by sounds. Also by this age, the child is able to grasp an object but look

towards the point at which he is directing his movement instead of having the keep his

eyes on the object the entire time.

VISION AS THE DOMINANT SENSE LEADS MOTOR DEVELOPMENT.

Vision allows the child maximum efficiency and a conservation of energy in his movements.

18 months - the child is strongly driven by motor movement. In fact this drive is so strong

that it would appear that motor is leading vision.

2 years - the child may use words such as “where” to gain information concerning spatial

perception. Language skills have developed to a point which allows the child to

reinforce visual experiences. There is also increased eye-hand coordination.

2 ½ years – the child is easily distracted by the slightest movement in his peripheral vision,

thus to keep a child’s attention to a task, the child has to stay involved manually and visually.

He also has difficulty planning ahead. This age child demonstrates increasing ability to

discern differences through vision and the other senses.

3 years - eye-hand coordination is more accurate, the child is not as easily distractible, and

the ability to plan and organize in advance has developed significantly. The 3 year old tries

to organize things in symmetrical relationships, becomes upset when organization is

broken, and shows a preoccupation with the wholeness of things – a concept called

perceptual closure.

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Appendix B

Recommended Childhood Routine Eye Examination Schedule (American Optometric

Association):

6 months of age - First dilated eye exam with an optometrist or ophthalmologist

(not a semi-professional at the pediatrician’s office or a school nurse)

3 years old – Dilated eye examination with an optometrist or ophthalmologist

5 years old – Dilated eye examination with an optometrist or ophthalmologist

Biannual exams thereafter

(Note: this schedule would be modified as necessary depending on the result of

the eye examination)

Visual skills

like all physical skills

can be taught, trained, practiced, and enhanced.

1. Garzia, R, Vision and Reading, Missouri, 1996, Mosby-Year Book, Inc.

2. Scheiman, M, Understanding and Managing Vision Deficits, New Jersey, 1997, SLACK

Incorporated, 70

Padula