Visual Impairment

Visual Impairment

Total blindness is the inability to tell light from dark, or the total inability to see. Visual impairment or low vision is a severe reduction in vision that cannot be corrected with standard glasses or contact lenses and reduces a person's ability to function at certain or all tasks. Legal blindness (which is actually a severe visual impairment) refers to a best-corrected central vision of 20/200 or worse in the better eye or a visual acuity of better than 20/200 but with a visual field no greater than 20° (e.g., side vision that is so reduced that it appears as if the person is looking through a tunnel).

Description

Vision is normally measured using a Snellen chart. A Snellen chart has letters of different sizes that are read, one eye at a time, from a distance of 20 ft. People with normal vision are able to read the 20 ft line at 20 ft-20/20 vision—or the 40 ft line at 40 ft, the 100 ft line at 100 ft, and so forth. If at 20 ft the smallest readable letter is larger, vision is designated as the distance from the chart over the size of the smallest letter that can be read.

Eye care professionals measure vision in many ways. Clarity (sharpness) of vision indicates how well a person's central visual status is. The diopter is the unit of measure for refractive errors such as nearsightedness, farsightedness, and astigmatism and indicates the strength of corrective lenses needed. People do not just see straight ahead; the entire area of vision is called the visual field. Some people have good vision (e.g., see clearly) but have areas of reduced or no vision (blind spots) in parts of their visual field. Others have good vision in the center but poor vision around the edges (peripheral visual field). People with very poor vision may be able only to count fingers at a given distance from their eyes. This distance becomes the measure of their ability to see.

The World Health Organization (WHO) defines impaired vision in five categories:

• Low vision 1 is a best corrected visual acuity of 20/70.
• Low vision 2 starts at 20/200.
• Blindness 3 is below 20/400.
• Blindness 4 is worse than 5/300
• Blindness 5 is no light perception at all.
• A visual field between 5° and 10° (compared with a normal visual field of about 120°) goes into category 3; less than 5° into category 4, even if the tiny spot of central vision is perfect.

Color blindness is the reduced ability to perceive certain colors, usually red and green. It is a hereditary defect and affects very few tasks. Contrast sensitivity describes the ability to distinguish one object from another. A person with reduced contrast sensitivity may have problems seeing things in the fog because of the decrease in contrast between the object and the fog.

According to the WHO there are over forty million people worldwide whose vision is category 3 or worse, 80% of whom live in developing countries. Half of the blind population in the United States is over 65 years of age.

Causes and symptoms

The leading causes of blindness include:

• macular degeneration
• glaucoma
• cataracts
• diabetes mellitus

Other possible causes include infections, injury, or nutrition.

Infections

Most infectious eye diseases have been eliminated in the industrialized nations by sanitation, medication, and public health measures. Viral infections are the main exception to this statement. Some infections that may lead to visual impairment include:

• Herpes simplex keratitis. A viral infection of the cornea. Repeated occurrences may lead to corneal scarring.
• Trachoma. This disease is responsible for six to nine million cases of blindness around the world, of the third of a billion who have the disease. Trachoma is caused by an incomplete bacterium, Chlamydia trachomatis, that is easily treated with standard antibiotics. It is transmitted directly from eye to eye, mostly by flies. The chlamydia gradually destroy the cornea.
• Leprosy (Hansen's disease). This is another bacterial disease that has a high affinity for the eyes. It, too, can be effectively treated with medicines.
• River blindness. Much of the tropics of the Eastern Hemisphere are infested with Onchocerca volvulus, a worm that causes "river blindness." This worm is transmitted by fly bites and can be treated with a drug called ivermectin. Nevertheless, twenty-eight million people have the disease, and 40% of them are blind from it.

Other causes

Exposure of a pregnant woman to certain diseases (e.g., rubella or toxoplasmosis) can cause congenital eye problems. Injuries to the eyes can result in blindness. Very little blindness is due to disease in the brain or the optic nerves. Multiple sclerosis and similar nervous system diseases, brain tumors, diseases of the eye sockets, and head injuries are rare causes of blindness.

Nutrition

Vitamin A deficiency is a widespread cause of corneal degeneration in children in developing nations. As many as five million children develop xerophthalmia from this deficiency each year. Five percent end up blind.

Diagnosis

A low vision exam is slightly different from a general exam. While a case history, visual status, and eye health evaluation are common to both exams, some things do differ. Eye charts other than a Snellen eye chart will be used. Testing distance will vary. A trial frame worn by the patient is usually used instead of the instrument containing the lenses the patient sits behind (phoropter). Because the low vision exam is slightly more goal oriented than a general exam, for example, what specifically is the patient having trouble with (reading, seeing street signs, etc.) different optical and nonoptical aids will generally be tried. Eye health is the last thing to be checked so that the lights necessary to examine the eyes will not interfere with the rest of the testing.

Treatment

There are many options for patients with visual impairment. There are optical and nonoptical aids. Optical aids include:

• Telescopes. May be used to read street signs.
• Hand magnifiers. May be used to read labels on things at the store.
• Stand magnifiers. May be used to read.
• Prisms. May be used to move the image onto a healthy part of the retina in some eye diseases.
• Closed circuit television (CCTV). For large magnification (e.g., for reading).

Nonoptical aids can include large print books and magazines, check-writing guides, large print dials on the telephone, and more.

For those who are blind, there are enormous resources available to improve the quality of life. For the legally blind, financial assistance for help may be possible. Braille and audio books are increasingly available. Guide dogs provide well-trained eyes and independence. Orientation and mobility training is available. There are special schools for blind children and access to disability support through Social Security and private institutions.

Prognosis

The prognosis generally relates to the severity of the impairment and the ability of the aids to correct it. A good low vision exam is important to be aware of the latest low vision aids.

Prevention

Regular eye exams are important to detect silent eye problems (e.g., glaucoma). Left untreated, glaucoma can result in blindness.

Corneal infections can be treated with effective antibiotics. When a cornea has become opaque beyond recovery it must be transplanted. Good hygiene (e.g., washing hands frequently) to prevent infection, proper use of contact lenses, and not sharing makeup are just some ways to guard against corneal infections.

Cataracts should be removed when they interfere with a person's quality of life.

Primary prevention addresses the causes before they ever begin. Fly control can be accomplished by simple sanitation methods. Public health measures can reduce the incidence of many infectious diseases. Vitamin A supplementation (when appropriate) will eliminate xerophthalmia completely. It is possible that protecting the eyes against ultraviolet (UV) light will reduce the incidence of cataracts, macular degeneration, and some other eye diseases. UV coatings can be placed on regular glasses, sunglasses, and ski goggles. Patients should ask their eye care professional about UV coatings. Protective goggles should also be worn in certain situations (e.g., certain jobs, sports, even mowing the lawn).

Secondary prevention addresses treating established diseases before they cause irreversible eye damage. Having general physical checkups can also detect systemic diseases such as diabetes or high blood pressure. Control of diabetes is very important in preserving sight.

Key terms

Cornea — The clear dome-shaped structure that is part of the front of the eye. It lies in front of the colored part of the eye (iris).

Diabetic retinopathy — Retinal disease caused by the damage diabetes does to small blood vessels.

Phoropter — The instrument used to measure refractive status of the eyes. It contains many lenses which are then changed in front of the eyes while the patient is looking at an eye chart. This is when the doctor usually asks, "Which is better, one or two?"

Xerophthalmia — A drying of the cornea and conjunctiva.

Common causes of visual impairment

Myopia (Nearsightedness): The image of distant objects is not focused on the retina but rather in front of it, making it appear blurry. The child can see objects that are near but not at a distance. Myopia can result from an elongated eyeball, a lens that is too strong, or a cornea that is excessively curved.

Hyperopia (Farsightedness): The focusing point is behind the retina resulting in straining to focus correctly, particularly at close distances. Therefore the child can see well at a distance but not at near. Hyperopia can result from shortness of the eyeball, a lens that is weak, or a cornea that is relatively flat.

Astigmatism: A cylindrical curvature of the cornea which prevents light rays from focusing on one point on the retina. The result is both near and far objects may appear blurry. Astigmatism often occurs in combination with myopia and hyperopia.

Eye-Conditions
 Albinism: Inherited condition resulting in decreased pigment which causes abnormal optic nerve development. Nystagmus (see below) and refractive errors are also often present with this condition. In addition to a decreased visual acuity, children with albinism may be sensitive to light. Tinted lenses can relieve light sensitivity and glasses or low vision aids can help maximize vision.

Amblyopia (“lazy eye”): The suppression of the image of one eye usually due to that eye having a significantly poorer acuity or being turned in/out. Children with amblyopia can have some functional field loss and poor or absent depth perception. Patching of the stronger eye and/or the use of glasses may be prescribed.

Cataracts: Opacity or cloudiness of the lens. Because light cannot pass through the lens, vision is affected. Some types of cataracts progressively worsen, while others remain unchanged. Cataracts can be found in one eye (unilateral) or both eyes (bilateral). Children with cataracts may have reduced visual acuity, blurred vision, poor color vision, light sensitivity, or nystagmus. Depending on the size and severity of the cataract, surgery to remove it may be recommended.

 

Coloboma: A birth defect which causes a cleft in the pupil, iris, lens, retina, choroid, or optic nerve. It can result in reduced acuity and field loss if the damage extends to the retina.

Glaucoma: Increased pressure in the eye due to blockage of normal flow of fluid in the eye. The vision of children with glaucoma can fluctuate based on changes in pressure. A child with glaucoma may also have peripheral field loss, poor night vision, and light sensitivity. If not treated, damage to the optic nerve can result.

Nystagmus: Involuntary movement of the eye. This can be horizontal, vertical, circular or mixed. Because the eyes are moving, a child with nystagmus has difficulty maintaining fixation on objects resulting in reduced visual acuity and fatigue. Nystagmus can be minimized by turning the head or eyes in a certain position, called the “null point.” The null point differs from person to person, but is often discovered by the child.

Optic Nerve Atrophy: Damage or degeneration to the optic nerve which carries visual signals to the brain. Vision loss will be dependent on the amount of damage, but may include blurred vision, poor color and night vision, and light sensitivity.

Optic Nerve Hypoplasia: Underdevelopment of the optic nerve in utero, resulting in a small optic nerve and visual impairment. The degree of visual impairment varies significantly but there is usually an acuity loss. Optic nerve hypoplasia may be associated with other conditions.

Retinitis Pigmentosa (RP): a hereditary, degenerative condition of the retina which results in loss of peripheral vision or “tunnel vision”. Initially starts with difficulty in seeing in dimly lit settings and progresses to a significant visual impairment.

Retinoblastoma: A cancerous tumor of the retina which requires vigorous treatment of all tumors through laser, radiation, and/or chemotherapy. Progression of retinoblastoma may result in enucleation (removal) of the eye. If one eye is removed, the child will not have depth perception.

Retinopathy of Prematurity (ROP): Disruption in the normal development of blood vessels of the retina in premature infants which can result in scarring and detachment of the retina. Children with ROP may have a decreased visual acuity and refractive errors.

Strabismus: A muscle imbalance resulting in the inability of both eyes to look directly at an object at the same time. Types of strabismus include: esotropia (an inward turn), exotropia (an outward turn), hypertropia (an upward turn), and hypotropia (a downward turn).

CorticalVisualImpairment
 

Unlike refractive errors and structural impairments, cortical visual impairment is not caused by any condition of the eye. Rather, it is due to damage to the visual cortex of the brain or the visual pathways which results in the brain not adequately receiving or interpreting visual information.

Children with cortical visual impairment often also have cerebral palsy, seizure disorder, and developmental delays as a result of the damage to the brain. They may exhibit inattention to visual stimuli, preference for touch over vision when exploring objects, and difficulty visually discriminating objects that are placed close together or in front of a visually complex background.

Because this visual impairment is due to the neurological processing of visual information, visual performance may fluctuate slightly or significantly from day to day, or even from moment to moment depending upon the environment and the seizure activity, motor position, general health, and mood of the child.

some considerations when working with children with multiple disabilities

Be sure that your child is in a comfortable position before beginning visual activities. It is difficult for a child to look when he/she is working on balance and motor control.

	Place your child so that the light is coming in from behind so that it highlights the object being presented. Many children with cortical visual impairments gaze a light sources and it could be distracting to your child.
	Many children with cortical visual impairments will respond to objects presented in the periphery and not to objects directly in the center. Children may respond best to movement, light sources, or reflective materials. It may also be difficult for your child to combine vision with other sensory information (touching or listening).
	Vary the distance which you present objects, many young children will respond best at a slight distance (18 inches to 2 feet) but not at objects that are too close or too far. By varying the distance you can determine at what distance your child best responds.

ways to stimulate child's vision & development

Use of vision is a developmental skill just like learning to walk or to sit, and this is especially true for young children with visual impairments.

Playing with your child can be one of the most important and rewarding experiences that a parent can have. It is important to play and interact with your child using a variety of age-appropriate materials and toys.

Things need to move very slowly to give your child time to look and respond. Your child needs to “learn” how to look and explore toys and objects, so be patient when trying the following helpful ideas.

The following suggestions are intended for children up to 5 years of age.
 

Young children respond best to objects with high contrast, those things that are shiny and reflect light, and light-oriented toys. This is also true of children with visual impairments. Using things that are “easy to see” is the best place to start when stimulating your child’s vision. There are many things available at regular toy stores which include black/white/red infant stimulation toys, toys with large buttons that activate lights and sounds, mirrors, pinwheels, shiny mylar balloons, etc. Have your child try to look at these toys/materials and gradually and slowly move the items from side to side.

Puppets are wonderful for visual stimulation because they have bright colors, movement, and are fun. Children of all ages will respond to the use of a puppet, especially if it makes funny sounds, “eats fingers or toes,” and does everyday things like jumping, sleeping, eating, etc.

It is very important for your child to use touch to help with all areas of play. Give your child a wide variety of touching experiences and start this as early as possible. There are wonderful textures all over your house: bath scrubbies, a pot scrubber, soft materials, textured squeak toys, rough scrub brushes, and beans/rice/water for older children. Playing with food, especially for those new finger feeders, is messy but a very important experience.

Most children with visual impairments are good listeners, but the sounds, voices, and language that they hear has to be meaningful. It is important to have some quiet times in the house with no television, radio, or excessive background noise so that your child can hear the house sounds. All houses make wonderful sounds and children with visual impairments can use those cues in order to understand the areas of the home and be comfortable in moving within the house. It is often scary for children with visual impairments to move through space because they are not certain what is “out there.” Carrying your child from room to room as a baby and talking about/touching all things in the kitchen, living room, bedroom, etc. is a good beginning, but it is critical to let your child move on his/her own as soon as possible. That is why it is important to have him/her playing on the floor. Use of a blanket with toys all around to “define the space” may be helpful. Later, as a beginning walker, your child can push toys or objects to “find things” before he/she touches them.

It is very important for you for you to talk to your child about everything. Use clear and consistent language with very good descriptions in order to help your child. Avoid words like “over there” and use words like “the ball is next to the chair.” Even if your child does not understand these words yet, it begins to build a foundation for descriptive language, and before you know it your child will understand and use this type of description. It is also important to tell your child what is about to happen (precueing) so he/she can be “ready” for the event (“I’m going to pick you up”). Describing something that has happened suddenly “after the fact” is also helpful (“Johnny dropped the bucket”) so that your child is not scared by loud events.

Your child with a visual impairment needs to be shown how to explore the world. Try to imagine how an activity feels or sounds. Sometimes it is good to close your eyes to experience what the toy/activity might mean to your child. There are also simulators available (glasses that may demonstrate what your child sees) to give you a better understanding of how to present and modify activities for your child. Ask your service providers or eye doctor for the opportunity to use these simulators.

There are many other techniques, specialized equipment, and control of lighting that may be helpful specifically for your child. This information can be provided by a Teacher of the Blind and Visually Impaired (TBVI) or an Orientation and Mobility (O&M) Specialist.

Be sure to …

	use objects that are fun and easy to see
	encourage touch and the exploration of various textures
	provide exposure to meaningful language and sounds and give your child quiet time to hear naturally-occurring sounds
	let your child move and explore on his/her own
	give your child time to look and respond
	try to imagine how your child is relating to a toy or activity
	talk to your doctor and service providers for more information

 What to do if you have concerns

If you have concerns regarding your child’s vision, it is very important to discuss your concerns with your pediatrician. Your pediatrician can evaluate your child’s eyes for general health and make recommendations of eye care specialists.

Ophthalmologists are medical doctors who specialize in the diagnosis of eye pathology and medical treatment. The ophthalmologist can also make a determination of your child’s visual acuity, eye alignment issues, and evaluate the structure of your child’s eyes. The ophthalmologist can prescribe glasses; do surgical intervention, if needed; as well as other medical treatment as necessary to address your child’s visual condition.

Optometrists are specifically trained to examine the eyes and determine the presence of vision problems. Optometrists, although not medical doctors, specialize in the determination of visual acuity, prescribe glasses/contact lenses, and can prescribe some medications. Some optometrists specialize in low vision evaluation and can prescribe low vision aids while others might specialize in developmental optometry which evaluates and treats children with ocular motor problems through “vision therapy”.

Opticians are technicians who make glasses. They grind the lenses to the appropriate prescription and fabricate the glasses or contact lenses.

Low Vision Specialists are usually optometrists who specialize in the evaluation of visual acuity loss and prescriptive devices that may enhance vision. Low vision devices may include use of telescopes, magnification, close-circuit televisions (CCTV), bioptics, etc. A thorough assessment is done of the patient’s vision and various devices are used in the process to determine the need for prescriptive low vision aids and the best device for the individual.
 

glossary
 

Adaptive Technology (AT)
“Any item, piece of equipment or product system, whether acquired commercially off the shelf, modified or customized, that is used to increase, maintain, or improve functional capabilities of individuals with disabilities.” (from IDEA, see below). Examples of AT for children who are visually impaired includes, but is not limited to, braille writers, low vision devices, “talking computers,” etc.

ASSETT
Assistive Services to Schools for Education, Technology, and Training. A Statewide support program for students with sensory disabilities and/or augmentative communication needs.

Braille
A system of reading and writing in which letters and word are formed by patterns of raised dots that are felt with the fingers.

Cognitive Development
The acquisition of the ability to think, reason, and problem solve.

Convergence
The movement, as an object approaches, of both eyes toward each other in an effort to see a single image of that object.

Early Supports & Services (Early Intervention)
Individualized programs of instruction and therapy developed for children younger than 3 years old who have a disability, developmental delay, or are at risk for a developmental delay

Fine Motor Skills
The ability to use small muscles such as those in the hands and the face (e.g. drawing, using a fork, drinking from a straw).

Fixate
Focus on an object

Gross Motor Skills
Skills that involve large muscles such as those in the arms, legs, and abdomen (for example, throwing a ball, walking, sitting up).

IDEA
Individuals with Disabilities Education Act.

IEP
Individual Education Plan. The education plan developed by the team for students who are in need of special education and/or related services due to a disability.

IFSP
Individual Family Service Plan. The service plan developed by the early intervention team for children ages 0 to 3.

Intake
Initial interview to gather information from the family prior to beginning Early Supports and Services.

Independent Living Skills
Skills needed to take care of oneself and become more independent (e.g. eating, dressing, etc.) Also referred to as Self Help skills and Activities of Daily Living (ADLs).

Learning Media Assessment
Evaluation to determine the most effective instructional materials and methods to facilitate learning for a student with a visual impairment. The individual child's learning style, preferred mode of communication and use of sensory channels should be considered.

Literacy Media Assessment
Evaluation to determine the most effective and appropriate reading and writing media for a child. Media considered should include Braille, large print, regular print, print with low vision devices, auditory media, or a combination of these.

Low Vision Services
Services designed to help an individual maximize the use of his/her vision through optical and non-optical devices and strategies.

MICE
Multi-Sensory Intervention through Consultation and Education. NH Program that provides statewide support services to Early Intervention Programs and direct services to families with children who have sensory impairments.

NAPVI
National Association of Parents of Children with Visual Impairments. New Hampshire has an active chapter.

NFB
National Federation of the Blind. A consumer organization. NFB has an active chapter in New Hampshire.

NOAH
National Organization for Albinism and Hypopigmentation. New Hampshire has an active chapter.

Object Permanence
The concept that things continue to exist even when they can no longer be seen, heard, or touched.

Orientation & Mobility (O&M)
The educationally related service by which a child develops body image, spatial organization, safety, independent travel skills. Instruction is provided by qualified Orientation & Mobility Instructor.

SBVI
Services for Blind and Visually Impaired. Division of the NH Department of Education-Adult Learning and Rehabilitation. Provides statewide services to adults who are blind and visually impaired

Self-Help Skills
Skills needed to take care of oneself and become more independent (e.g. eating, dressing, etc.) Also referred to as Independent Living (IL) skills and Activities of Daily Living (ADLs).

Teacher of the Blind and Visually Impaired (TBVI)
A certified teacher who has received specialized training in meeting the educational needs of children who are blind or visually impaired. Sometimes referred to as Teacher of the Visually Impaired (TVI).

Educating Students With Visual Impairments for Inclusion in Society

"Inclusion," "full inclusion" and "inclusive education" are terms which recently have been narrowly defined by some (primarily educators of students with severe disabilities) to espouse the philosophy that ALL students with disabilities, regardless of the nature or the severity of their disability, receive their TOTAL education within the regular education environment. This philosophy is based on the relatively recent placement of a limited number of students with severe disabilities in regular classrooms. Research conducted by proponents of this philosophy lacks empirical evidence that this practice results in programs which are better able to prepare ALL students with visual impairments to be more fully included in society than the current practice, required by federal law, of providing a full range of program options.

Educators and parents of students with visual impairments have pioneered special education and inclusive program options, for over 164 years. It is significant that the field of education of visually impaired students was the first to develop a range of special education program options, beginning with specialized schools in 1829 and extending to inclusive (including "full inclusion") public school program options since 1900.

Experience and research clearly support the following three position statements outlining the essential elements which must be in place in order to provide an appropriate education in the least restrictive environment for students with visual impairments. This document also contains papers which provide additional information supporting each of these position statements and a list of selected readings on inclusion for students with visual impairments.

I. Students with visual impairments have unique educational needs which are most effectively met using a team approach of professionals, parents and students. In order to meet their unique needs, students must have specialized services, books and materials in appropriate media (including braille), as well as specialized equipment and technology to assure equal access to the core and specialized curricula, and to enable them to most effectively compete with their peers in school and ultimately in society.

II. There must be a full range of program options and support services so that the Individualized Education Program (IEP) team can select the most appropriate placement in the least restrictive environment for each individual student with a visual impairment.

III. There must be adequate personnel preparation programs to train staff to provide specialized services which address the unique academic and non-academic curriculum needs of students with visual impairments. There must also be ongoing specialized personnel development opportunities for all staff working with these students as well as specialized parent education.

Providing equal access to all individuals with disabilities is the key element of the Rehabilitation Act of 1973 and the Americans with Disabilities Act of 1992. Access involves much more than providing ramps. Access is also the key element of inclusion, which involves much more than placement in a particular setting. The relationship of access and inclusion may not be obvious to individuals who are not familiar with the educational and social impact of a vision loss. Placing a student with a visual impairment in a regular classroom does not, necessarily, provide access and the student is not, necessarily, included. A student with a visual impairment who does not have access to social and physical information because of the visual impairment, is not included, regardless of the physical setting. Students with visual impairments will not be included unless their unique educational needs for access are addressed by specially trained personnel in appropriate environments and unless these students are provided with equal access to core and specialized curricula through appropriate specialized books, materials and equipment.

Conclusion: Students with visual impairments need an educational system that meets the individual needs of ALL students, fosters independence, and is measured by the success of each individual in the school and community. Vision is fundamental to the learning process and is the primary basis upon which most traditional education strategies are based. Students who are visually impaired are most likely to succeed in educational systems where appropriate instruction and services provided in a full array of program options by qualified staff to address each student's unique educational needs, as required by Public Law 101-476, The Individuals with Disabilities Education Act (IDEA).

The Unique Educational Needs Of Students With Visual Impairments

Students with visual impairments have unique educational needs which are most effectively met using a team approach of professionals, parents and students. In order to meet their unique needs, students must have specialized services, books and instructional materials in appropriate media (including braille), as well as specialized equipment and technology so they can have equal access to the core and specialized curricula, and to enable them to most effectively compete with their peers in school and ultimately in society.

The majority of learning in infants and young children occurs through vision. Soon after the birth of an infant who is visually impaired, families may become aware that their child does not respond to them in the same way as an infant who is sighted. In order to ensure a healthy bonding process and emotional growth, early intervention is essential for both the child and the family.

Vision is the primary sense upon which most traditional education strategies are based. These strategies must be modified to reflect the child's visual, auditory and tactile/vision capabilities. A child with a severe visual loss can directly experience only what is within arm's reach and can be safely touched, and in most cases, what can be heard. To ensure an appropriate education, families and staff with special training must work together to bring the world of experiences to the child in a meaningful manner.

As the child grows, the absence or reduction of vision dramatically limits understanding of the world. No other sense can stimulate curiosity, combine information, or invite exploration in the same way, or as efficiently and fully as vision. Students with visual impairments can and do succeed, but at different rates and often in different sequences. There must be significant intervention, coordinated by an educational team to ensure that appropriate development does occur.

It is important to remember that education goals for students with visual impairments are essentially the same as those for all students. The goals are: effective communication, social competence, employability, and personal independence. In order to accomplish these goals, however, students with visual impairments require specific interventions and modifications of their educational programs. An appropriate assessment of these unique educational needs in all areas related to the disability and instruction adapted to meet these needs is essential to ensure appropriate educational programming.

Clearly, the lack of vision significantly affects learning. The unique educational needs created by a visual impairment may be summarized as follows:

• Vision loss can result in delayed concept development which, without effective intervention, severely impacts the student's social, emotional, academic, and vocational development.
• Students with visual impairments often must learn through alternate mediums, using their other senses.
• Students with visual impairments often require individualized instruction since group instruction for learning specialized skills may not be provided in a meaningful manner.
• Students with visual impairments often need specialized skills as well as specialized books, materials and equipment for learning through alternate modes.
• Students with visual impairments are limited in acquiring information through incidental learning since they are often unaware of subtle activities in their environment.
• Curriculum areas that require unique strategies or adaptations for students with visual impairments include concept development, academic functioning,communication skills, sensory/motor skills, social/emotional skills, orientation and mobility, daily living skills, career/vocational skills and utilization of low vision.

The more intensive and unique needs associated with visual impairment must also be addressed in educating students who are visually impaired and have one or more additional disabilities, including specialized health care needs. The education of students with multiple disabilities or other special needs must involve a team approach, combining the expertise of specialists to competently address the complex needs of these students. Educators of students with visual impairments possess unique competencies needed by the team. Therefore, to achieve quality education for students with multiple disabilities or other special needs, services must be provided using a team approach, including members with disability-specific expertise in educating students with visual impairments.

Conclusion: The unique educational needs of all students with visual impairments cannot be met in a single environment, even with unlimited funding. It is critical that a team approach be used in identifying and meeting these needs and that the team must include staff who have specific expertise in educating students with visual impairments. The proposal that ALL of the needs of ALL students can be met in one environment, the regular classroom, violates the spirit as well as the letter of the law - IDEA.

The Full Range Of Program Options And Support Services For Students With Visual Impairments

There must be a full range of program options and support services so that the Individualized Education Program (IEP) team can select the most appropriate placement in the least restrictive environment for each individual student with a visual impairment.

In order to meet the individual and disability-specific needs of students with visual impairments, there must be a full array of program options and services. Educational needs that are specific to these students must be addressed throughout their school experience. Educators of students who are visually impaired recognized long ago that the only manner in which the unique, individual needs of students could be met was to provide choices for delivering specialized services.

Efforts throughout the history of education for students with visual impairments have been focused on the right of these persons to full participation in an inclusive society. Quality education was acknowledged as the first step toward that goal. In the early 1800s, schools for the blind were founded in the United States, in recognition of the fact that children who were blind had the capability of learning and becoming independent. In 1900, the first class for blind students in a regular day school was established in Chicago, to meet the individual needs of these students. By 1950, about 15 urban areas were serving students with visual impairments in their local schools. The decades of the 1950s and 1960s marked a period of time when parents and educators first became aware of the need for an array of service options for students with visual impairments, and efforts to provide services based on the assessed needs of individual students began.

Currently most students with visual impairments are served in their home schools by itinerant personnel. There is increasing concern, however, that students are not receiving the intensity of services needed, particularly in the primary grades, to provide them with the skills (including braille, daily living, and social skills) necessary to be successfully integrated in school. Because students are expected to learn the core curriculum and meet graduation requirements, it is very difficult to provide these additional specialized skills when the student is fully included, particularly in a time when specialized support services have been reduced because of funding cuts and teacher shortages. In addition, funds are often not available to provide the specialized books, materials and technology required by students. Students cannot be successfully included without the necessary support.

The Pinebrook Report (American Foundation for the Blind, 1953) provided the first written definition of local school service delivery systems for students with visual impairments. Clearly described in this booklet are itinerant services, resource room services, and cooperative efforts between classroom teachers and teachers of students with visual impairments. This landmark publication appeared long before IDEA, but its content clearly reflects the intent of federal legislation. In the years since The Pinebrook Report, educators of students with visual impairments and their parents have expanded the appropriate array of service options.

Selection from this array must be driven by the assessed needs of each individual student; no delivery option within the array of services has more or less value. Each option may be the best for different periods of a student's schooling. The array that should be available to students with visual impairments includes, but is not limited to, the following:

The educational needs of students with visual impairments will vary, depending on the age and development of the student. Therefore, services needed will vary. There will be periods of time for most students when time outside the regular classroom will be extensive, such as beginning braille reading, expansion of orientation and mobility skills, career education, social skills, or times when independent living skills need to be emphasized. Such opportunities for learning may require pull-out time, or a special class placement, or a residential school placement for a period of time.

IDEA requires a "continuum" of placement options. This is often interpreted as a hierarchy of options from most desirable (least restrictive) to least desirable (most restrictive). Students who are visually impaired require an "array" of service delivery systems, which means a choice of the best option to meet each student's needs. The appropriate placement for each individual student is determined by educational goals and objectives, based on assessment, that are identified in the IEP, and is thus the most desirable (and least restrictive) for the student at that time.

Conclusion: The right of every student with a visual impairment to an appropriate placement in the least restrictive environment, selected by the IEP team from a full range of program options and based upon each student's needs, is nothing more or less than is mandated by federal law.

Personnel Development For Staff And Parents Of Students With Visual Impairments

There must be adequate personnel preparation programs to train staff to provide specialized services which address the unique academic and non-academic curriculum needs of students with visual impairments. There must also be ongoing specialized personnel development opportunities for all staff working with students with visual impairments as well as specialized parent education.

Preparation Of Specially Trained Staff

Instruction, regardless of setting, must be provided by professionals thoroughly prepared and qualified to teach students with visual impairments. The skills and knowledge needed by these staff can be defined with three classifications. First, the teacher must have a foundation in regular education, including methodology in teaching reading, mathematics, and other areas of subject matter. Second, the teacher must learn the techniques for curriculum adaptation for visual learning experiences so that the concepts taught remain the same with adapted teaching methodology and materials. Third, the teacher must know how to assess skills and deliver instruction in the specialized areas of independent living skills, social skills, career education, and specific areas of academics.

The combination of knowledge and skills needed in order to provide appropriate educational services to students who are visually impaired requires intensive preparation in a teacher training program. Most often, these programs are offered at colleges and universities, either at the undergraduate or graduate level. Experience has shown that at least one school year of preparation is necessary in order to possess entry level skills as a teacher of students with visual impairments.

Programs that prepare teachers of students with visual impairments contain curricula that is not found in general teacher preparation or generic programs in special education. Competencies for special teachers of students who are visually impaired include:

• Development patterns in students with visual impairments
• Comprehensive assessments of the students with visual impairment in all areas related to the disability
• Ability to design and modify core and specialized curricula for the student with visual impairment
• Knowledge of specialized technology
• Special instructional strategies for the student with a visual impairment
• Specialized books, materials and equipment used by the student with a visual impairment
• Appropriate specialized counseling and guidance services
• Knowledge of specific local, state and national legal requirements, policies and specialized resources
• Knowledge of and need for research in the field
• Understanding vision loss and other related impairments
• Collaboration with families and other professionals

Another important unique need area is orientation and mobility which must be provided by trained and qualified orientation and mobility specialists. The teacher of students with visual impairments may share in the responsibility for reinforcing learned skills in orientation and mobility, but educational programs must offer instructional services of appropriate frequency and duration from both a specially trained teacher and an orientation and mobility specialist.

Staff Development, Including Parent Education

Because of the low incidence of visual impairments, many students and adults have never been exposed to individuals who function without vision or with limited vision. Therefore, although individuals often want to be helpful to the student with a visual impairment, they often do not know what to do. Some do nothing at all. Others use a trial and error strategy, sometimes being helpful and, other times failing to accomplish much that is productive. Still others do too much, creating a debilitating dependence. In order for professionals, peers, or parents to assist a student who is visually impaired, they must have a realistic picture of what the student can do and of those situations in which help is really needed. Then they must be provided with guidance and special techniques for providing appropriate assistance.

For example, it is important to realize that the student who is visually impaired must accomplish the same work as his sighted peers using disability-specific skills which generally require greater time to master and, often, more time to use in completing the same tasks. Both the reading and writing of braille, even by a proficient braille user, requires more time.

In an integrated setting, the vision teacher often has limited time that can be spent with a student who is visually impaired. This necessitates the development of a support team which includes professionals, paraprofessionals, peers, and parents with a unified philosophy and strategies for assisting the student to learn and develop.

Therefore, it is important that all individuals who will be interacting with the student who is visually impaired receive specialized in-service training:

• Specialist staff serving visually impaired students with a wide range of cognitive abilities and, perhaps, additional disabilities and special needs will need opportunities to sharpen skills that may not be used for significant periods of time. For example for the vision teacher, advanced braille math (Nemeth Code) skills may be called upon only when a particular student required assistance with higher level mathematics courses. Specialist staff, including the orientation and mobility specialist, will also need to develop skills to remain current with advances in the field, such as the rapid advances in technology that are critical to the student with a visual impairment.
• Regular educators and other special educators, who may not have had any prior training or experience in teaching students with visual impairments, will need in-service regarding the impact of visual impairment on learning and development. They will also need to be assisted in applying strategies for teaching that address the unique educational needs of the student with limited or no vision.
• Paraprofessionals, including transcribers, readers and aides, who facilitate the education of students who are visually impaired within the regular classroom will need training to assist the student to develop skills for independence rather than dependence.
• Administrators who are responsible for providing appropriate facilities, technical assistance, and educational service delivery to students with visual impairments, need training related to the specific needs and essential interventions associated with blindness and visual impairment. They also need assistance in locating the resources needed to implement high quality programs.
• Parents of children who are blind or visually impaired need critical information to fulfill their natural role as their child's best and only lifetime advocate. Federal law not only encourages their participation in the educational process, but identifies the key roles they must play if their children are going to reach their full potential and their maximum level of independence. Quality parent education on an ongoing basis will provide the tools for parents to understand their child's individual needs and how those needs can best be met in both the home and school environments.

Conclusion: Students with visual impairments have the right to an appropriate education that is guided by knowledgeable specialists who work collaboratively with parents, the student and other education team members. Access to training on an ongoing basis is essential for all team members, especially parents who provide the necessary continuity and support in their child's education.

REHABILITATION

Accommodations / Modifications

• General Accommodations
• PDF file of accommodations
• Word doc. file of accommodations
• academic accommodations

Advocacy Information

• advocacy-how to do it- a primer

Anatomy/Physiology

• Diagram of the Eye (National Eye Institute)
  Also available in: Spanish
• Normal Eye Anatomy (National Eye Institute)

Assessment

• Assessment tools

Assistive Technology

• Braille and Speak and e-mail FAQ
• Connecting a Braille Lite or Braille ‘N Speak notetaker to a desktop PC
• technology links
• various types explained

Audio/Video

Books and Publications

• books with visually impaired characters

Causes

• Graph
• causes
• neurological Visual Impairment

Characteristics

• General characteristics, incidence, educational implications, resources and organizations.
• characteristics of cortical visual impairment

Children

• "Vision Impairment" Quest
• My Friend Jodi Is Blind (Lighthouse International)
• Signs of Possible Eye Trouble in Children (Prevent Blindness America)
• Task Force Recommends Vision Screening for Children Younger Than 5 Years Old (Agency for Healthcare Research and Quality)
  Also available in: Spanish
• What Is a Pediatric Ophthalmologist?
• Your Child's Vision (Nemours Foundation)
  Also available in: Spanish

Classifications or Types of

• types and degrees of visual impairments

Classroom Management

• helpful tips and suggestions for teachers
• checklist for cortical visual loss
• early intervention
• magnification
• readers with visual impairments
• glossary
• community based instruction
• in the regular classroom
• orientation and mobility resources
• dealing with students with low vision
• social skills
• materials adaptations
• large print books
• electronic format
• curriculum adaptations
• challenges in teaching math to the visually impaired
• ideas for vision stimulation activities
• communicating with a blind person-first person article
• questions kids ask about blindness
• orientation and mobility resources
• inclusive strategies for math
• inclusion-good overview of preparation

Clinical Trials

• ClinicalTrials.gov: Blindness (National Institutes of Health)
• ClinicalTrials.gov: Vision Disorders (National Institutes of Health)
• Clinical Trials in Vision Research (National Eye Institute)

Coping

• Family and Friends Can Make a Difference! How to Help When Someone Close to You Is Visually Impaired (Lighthouse International)
• Frequently Asked Questions about FCC Provisions for People with Disabilities (Federal Communications Commission)
• Introduction to Adaptive Computer Technology (Lighthouse International)
• Living with Low Vision? 10 Steps to Ensure Your Independence (Prevent Blindness America)
• Low Vision Coping Resources: Adjustment Process (Foundation Fighting Blindness)
• Low Vision Coping Resources: Watching TV with Low Vision (Foundation Fighting Blindness)
• What Do You Do When You Meet Someone Who Can't See? (Lighthouse International)
• What Is Braille? (American Foundation for the Blind)

Definition

• definition of vision therapy
• definitions

Diagnosis/Symptoms

• Do You Have Low Vision? (National Eye Institute)
• Signs of Possible Eye Trouble in Adults (Prevent Blindness America)
  Also available in: Spanish

Disease Management

• Getting the Most Out of Your Low Vision Experience (Foundation Fighting Blindness)
• Maintaining Quality of Life with Low Vision (American Occupational Therapy Association)

Frequently Asked Questions

• Low vision FAQ

From the National Institutes of Health

• Frequently Asked Questions about Low Vision (National Eye Institute)
  Also available in: Spanish
• Questions to Ask about Low Vision (National Eye Institute)
  Also available in: Spanish
• What You Should Know about Low Vision (National Eye Institute)
  Also available in: Spanish

Genetics

• Genetics Home Reference: Alström syndrome (National Library of Medicine)

Miscellaneous Topics

• Teaching math to visually impaired students
• Resources for Parents and Teachers for children who are blind
• Eye Disorders
• Syndromes and Rare Diseases
• Preschool Children with Visual Impairments
• Links for Parents and Family
• Downloadable Braille Materials
• Selected Anomalies and Diseases of the Eye
• Calendar of Events
• Schools for the blind

Organizations

• American Council of the Blind
• Lighthouse International
• National Federation of the Blind
• Prevent Blindness America
• American Foundation for the Blind
• Canine Companions for Independence
• National Library Service for the Blind
• National Association for Parents of Children with Visual Imparments
• American Foundation for the Blind
• American Optometric Association
• Foundation Fighting Blindness
• National Eye Institute
• Prevent Blindness America

Overview and General Information

• ERIC overview
• fact sheet
• Vision Impairment (National Center on Birth Defects and Developmental Disabilities)

Parent Information

• glossary of terms
• vision therapy
• organizing your kitchen
• participating in your child’s IEP meeting
• Vision related services-Braille
• orientation and mobility resources
• recreation resources

Pictures/Diagrams

• Eye Disease Simulations (National Eye Institute)
• Eye Examinations (National Eye Institute)
• Impairments to Vision (National Weather Service)
• Low Vision Devices (National Eye Institute)
• Low Vision Simulations (National Weather Service)

Prevalence

• How common is vision impairment?

Prevention/Screening

• Checklist for Your Eye Doctor Appointment (Prevent Blindness America)
• Ergonomics Approach to Avoiding Workplace Injury (American Industrial Hygiene Association) Also available in: Spanish
• Healthy Vision
• How Often to Have an Eye Exam

Research

• Statement on the Prevalence of Visual Impairment and How It Affects Quality of Life Among Hispanic/Latino Americans (National Eye Institute)
• U.S. Latinos Have High Rates of Eye Disease and Visual Impairment

Resources for Parents and Teachers on Braille

• Resources for Parents and Teachers on Home School
• Resources for Parents and Teachers on Toys
• Resources for Parents and Teachers on Math
• Resources for Parents and Teachers on Orientation and Mobility
• Resources for Parents and Teachers on Recreation
• Resources for Parents and Teachers on Technology

Seniors

• Creating a Comfortable Environment for Older Individuals Who Are Visually Impaired (American Foundation for the Blind)
• Saving Your Sight--Early Detection Is Critical (Food and Drug Administration)
• Services for Older Persons Who Are Blind or Visually Impaired (American Foundation for the Blind)
• Vision Loss is Not a Normal Part of Aging (Lighthouse International)

Specific Conditions

• Common Eye Myths (Prevent Blindness America)
• Going to a Low Vision Center - What You Should Know and What to Expect (Foundation Fighting Blindness)
• Illuminating Solutions: Lighting and Low Vision (Lighthouse International)
• JAMA Patient Page:Causes of Visual Impairment (American Medical Association)
• Onchocerciasis (River Blindness) (National Institute of Allergy and Infectious Diseases)

Statistics

• Quick Facts and Figures on Blindness and Low Vision (American Foundation for the Blind)
• Vision Problems in the U.S. (National Eye Institute) - Links to PDF File

Teaching Strategies for Students with Visual Impairments

• General Courtesy
• General Strategies
• Teacher Presentation
• Group Interaction and Discussion
• Text Reading Systems
• Field Experiences
• Research
• Testing

Teenagers

• Blindness Awareness (Dept. of Health and Human Services)
• Visual Impairment (Nemours Foundation)
• Visual Impairments

Treatment

• Eye Drops to Treat Childhood Eye Disorder Work As Well As Patching the Eye (National Eye Institute)

Teaching Students with Visual Impairments

About two-thirds of children with vision impairments also have one or

more other disabilities. Children with severe vision impairments are more

likely to have additional disabilities.

When a child is born with a visual impairment it is called congenital

blindness. This may be inherited or may be from an infection passed on

from mother to child.

It is very rare that people lose their sight during their teen years. When

they do, it is usually some sort of accident that results in some sort of

head trauma.

The degrees of vision difficulties are measured with an eye

chart and as a ratio (eg. 20/20 vision)

Top number = distance in feet of how close a person must

be to see an object compared to

Bottom number = the distance in feet a regular sighted

person can see that object

Examples:

A person with 20/400 vision must stand 20 feet away from an

object that a sighted person can see from 400 feet away

A person with 20/70 vision must stand 20 feet away from an

object that a sighted person can see from 70 feet away

A person with 20/20 vision must stand 20 feet away from an

object that a sighted person can see from 20 feet away,

therefore, that person has what we consider “perfect” vision

Visual Impairment is a generic term

It covers a broad range including

• Blind = 20/400 down to complete sightlessness with the best possible

correction. Most people with a visual impairment have at least some sight like

lights and shadows.

• Legally Blind = 20/200 down to complete sightlessness with the best

possible correction.

• Partially-sighted = when a person cannot, after eye correction, read,

travel and see normally. People who are partially sighted often need vision

aids and special education.

• Low Vision = visual acuity between 20/70 and 20/400 after all

corrective possibilities. People with low vision cannot read the newspaper at a

normal viewing distance, even with glasses.

Students with visual impairments live normal lives. They go to

school, have after-school jobs, date, play sports, and socialize.

How well they function with the vision that they do have is called

their functional vision. The same as people don’t think every day

about their eye color, people with a visual impairment don’t think

about their condition every day either. Blindness just becomes part

of who they are.

Since a child with a visual impairment may not be able to see

his/her parents or peers, imitating social norms may be difficult.

Some problems may include:

• Looking at with whom they are speaking or listening

• Allowing for proper personal space to the other students

Teacher’s Tips

Whatever the degree of impairment, students who are visually impaired

should be expected to participate fully in classroom activities. Although they

may confront limitations, with proper planning and adaptive equipment their

participation can be maximized. Students should not be exempt from test

taking or expected to master less or perform at a lower scholastic level

because of a visual impairment. Here are some tips from the University of

Rochester Disability Resource website that may give teachers some good

ideas when they have a student with a vision impairment in their class.

The Classroom

• Reserve a seat in the front row

• Have room for seeing eye dog

• Keep isles clear and drawers and cabinets closed

The Teacher

• Face the class while speaking

• Permit lectures to be taped

• Provide large print versions of classroom materials

• Be flexible with assignment deadlines

• Consider alternative assignments

• Consider alternative measures of assessing achievements

• Translate material to Braille and adaptive electronic media

• Be specific with directions

• Provide “hands on” learning experiences

• Use real objects so the student can experience them by touch

• Supply students with tactile diagrams and graphs ( by outlining them

with liquid glue)

• Use appropriate scale when possible

• Ask the student if they have any suggestions

• Keep communications open

The Rest of the Class

• Instruct others to yield the right of way

• Instruct students to help when asked

• Instruct students to ask if help is needed

• Instruct students not to harass seeing eye dog

Cortical Visual Impairment

What is Cortical Visual Impairment (CVI)? CVI refers to a brain condition, not an eye condition and results from damage to the visual systems in the brain that deal with processing and integrating visual information. CVI can be a temporary or permanent impairment and can range from severe visual impairment to total blindness. Because CVI is a neurological impairment, vision is more severely reduced than can be explained by an eye exam. The degree of the impairment depends on the age of onset as well as the location and severity of the impairment in the visual pathway. CVI is referred to by many different names including cortical blindness, cerebral blindness, central visual disturbance, and cerebral visual impairment.

Causes of CVI

The causes of CVI are varied (see Figure 1) with the most common causes being hypoxic or anoxic brain damage. Hypoxic brain damage results from the reduction of oxygen supply to a tissue, which can occur from cardiac arrest, resuscitated drowning, near miss S.I.D.S. (Sudden Infant Death Syndrome), and prolonged epileptic seizures. Anoxic brain damage results from the absence of oxygen supply to tissues and can result from asphyxia.

 Associated Diagnoses

 Most children with CVI have other associated neurological problems. The most common of these include cerebral palsy, epilepsy, hydrocephalus, severe to mild learning difficulties, and seizures.

Characteristics of CVI

Children with CVI display a number of specific behaviors. Understanding these specific behaviors will assist individuals in appropriate interactions and interventions with children who have CVI. The following checklist will help to identify these specific behaviors; however, it is important to remember that children with other types of visual impairments may exhibit some of these characteristics as well. Please review Figure 2 on page 3 for characteristic differences between “pure” ocular and cortical visual disorders. While reviewing the checklist, here are some important facts to keep in mind about CVI

 • CVI can range from mild to severe.

• CVI can range from temporary to permanent.

 • Many children experience improvement.

 • Children with CVI can also have ocular (or eye) difficulties as well.

 • Fluctuation is common.

 • Characteristics can vary from child to child.

 • A single approach does not work for all children.

 • Children with CVI typically have some vision.

Common Causes of CVI

 Hypoxic brain damage

• Anoxic brain damage

• Developmental brain defects

• Head injury

• Infections of the central nervous system (e.g., meningitis & encephalitis)

 • Intrauterine infections (i.e., STORCH)

• Progressive disorders (e.g., Tay Sachs

Characteristics of CVI
Appearance
. Does not look blind	. Blank facial expression
. Lack of visual communication skills	. Eye movements smooth, but aimless
. Nystagmus (rapid eye movement) rarely seen
Vision Function
. Visual function varies day to day/hour to hour	. Balance improved with eyes closed
. Limited visual attention & lack visual curiosity	. Looks away from people and objects
. Aware of distant object, but cannot identify	. Spontaneous visual activity has short duration
. Consistently looks to either side when visual looking	. When visually reaching, looks with a slight downward gaze
. Visual learning tiring	. Uses touch to identify objects
. Closes eyes when listening	. Turns head to side when reaching, as if using peripheral fields, or motion detection
Mobility Skills
. Occasionally sees better traveling in a car	. Unable to estimate distances
. Difficulties with spatial interpretation	. Difficulties with depth perception, inaccurate reach
. Avoids obstacles, but unable to use vision for close work
Improved Visual Performance When . . .
. In familiar environments	. Using familiar objects
. Told what to look for & where to look	. Objects are held close to eyes when  viewing
. Objects are widely spaced	. Looking at one object vs. a group  of objects
. Color is used to assist in identification of objects or shapes	. Objects are against a plain background and paired with movement and sound

Strategies for Interacting with a Child Who Has CVI

Research has shown that visual attention is trainable where there is usable vision. In other words, children with vision impairments whose development is delayed need increased stimulation and interaction based on their residual vision. Strategies that can be adapted to the specific needs of children who have CVI include:

 • Use simple cues (e.g., touch cues, object cues).*

 • Avoid figure-ground clutter.

• Use repetition & familiar routines.

 • Avoid extra, unnecessary stimulation.

• If possible, pair visual information with other sensory cues.

 • Do not over-stimulate the child with visual clutter • Be aware of visual preferences.

 • Allow the child to avoid visual gaze if necessary.

 • Be aware of other “drains” on energy.

• If needed, adapt the setting to reduce noise clutter, over-stimulating lighting, & other distracters.

 • Sometimes moving an object will help the child to see the object better.

 • Use real objects rather than abstract symbols (e.g., an orange vs. a circle).

• Use active rather than passive learning.

• Five environmental areas that can be changed to encourage children to use their vision:

♦ Color (bright vs. bland)

 ♦ Contrast (high vs. low)

♦ Lighting (use lighting cues--e.g., shining a flashlight on an object)

 ♦ Space/Distance

 ♦ Time (wait!)

Human Eye Physiology

History of Eye Understanding

•         Plato, 427-347 B.C.

               inner fire in the eye + emanated ray

•         Epicurus, 341-270 B.C., replicas of the object into the mind

      Galen, 130-200, physiological details, rays out and in

•          

•         Alhazen, Arabic philospopher, 965-1040, idea of pinhole camera

•         Jonannes Kepler, 1571-1630, knew lens, put it into an initial theory close to current

•          

Human Visual System

Visual Areas of the Human Cortex

Human Eye – cross section

Visual Fields

                     Rabbit                                                                        Human

Directional sensitivity

Retina 1

Retina 2

Retina 3

Neuron

Neuron 2

Iris – smoothing