Definitions, Identification, and Professionals

Dolly Bhargava, M.Spec.Ed. and Elmwood Visual Resource Centre, Christchurch, NZ



Author: Dolly Bhargava

Vision plays an important role in student growth, development and daily performance.  Vision impairment is identified as one of the ten most prevalent causes of disability in the United States.  A fact sheet produced by the National Information Center for Children and Youth with Disabilities in 1997 stated that the prevalence of visual impairments in individuals under the age of 18 is 12.2 per 1,000.

There is a wide range of cause and type of vision impairment.  Although each student is unique, in general terms, a student is identified as having vision impairment when his or her vision disorder affects the ability to function in life to such a degree that the eyes cannot be corrected with glasses, contact lenses, medications or surgery.  In such cases special instructional techniques, materials or assistive devices are needed for optimum learning to take place (Miller & Levack, 1997).

To effectively teach students with vision impairment, teachers need to become familiar with vision-related concepts.  The information below will briefly outline the nature of vision impairment and provide you with useful current definitions, not only of blindness, but also of the related term vision impairment, and deal in particular with the educational requirements of students who have low vision. The chapter will provide you with information on ways of identifying students with vision impairments in the classroom, discuss their learning characteristics, and briefly focus on the several types of professionals who can be of assistance in their diagnosis and education.



Author: Mike Offord

Vision is a dynamic, always changing process of organizing, interpreting and understanding what is seen. It is a process that integrates sensory and motor information generated by the brain and body to derive meaning and direct movement.

The use of vision is actually developed like walking and talking. It is learned over time from birth on up by our experiences and how we react and solve problems. It differs from eyesight because eyesight is our ability to see, a sense that most of us are born with, and vision is actually a LEARNED process. The visual skills we learn early on provide the foundation for later visual complexities. Any weak link in the visual process can affect the outcome, especially if the visual system is under stress.

Basically, we use vision to guide motor behaviour, like catch a ball; interpret space and time, like when we give directions and say "it will take 10 minutes if we turn left at the light coming up in two blocks"; and integrate information from our other senses (hearing, touch, taste and smell), so we may think, understand and react to the world around us.

Vision allows us to take what we see and process this light information so we can -

Identify what we see by where it is, how far away it is, how big it is, how fast it is moving, what texture it has, etc. Store this current information for future retrieval. Integrate the sight information with all our other senses - touch, hearing, taste and smell. Compare this information to previously stored information in order to confirm prior experience or reconstruct a prior experience if necessary. Derive meaning from both the new information and past information. Decide the relationship between where we are and where it is, or find out where we are in space. Act on this new meaning. Use this new perception to direct movement or thought. 


Approximations of Vision with Different Acuities:
Distance Vision Acuity Image 6-12
Distance Vision Acuity Image 6-24
Distance Vision Acuity Image 6-60

Examples of what a person with different visual acuities may see for distance vision by Mike Offord. 

Definitions of Vision Impairment

Author: Dolly Bhargava

A student with a vision impairment is part of a heterogeneous group whose one common characteristic is some degree of vision loss. Vision is a perceptual process with three elements: the eye, the optic pathway and the brain (MacLean, 1998).  For vision to occur, all three elements must be functioning.  Educationally, there are three major groups of students (or learners) with vision impairments in our schools:

Learners who are “educationally blind”: These students have little or no functional vision for learning and primarily use Braille, audio and tactile aids in their learning. Learners with low vision: After correction (i.e., with glasses), these students  are able to  use vision for learning and are generally dependent on low-vision aids and environmental modifications for assistance;  

These three categories are helpful to you as a teacher as they suggest the teaching and learning frameworks that must be set in place so that each student can properly access the curriculum. 

  • Learners with correctable low vision.  These are students who, after correction, can use their vision effectively and without too much extra help (Kelley, Gale & Blatch, 1998, p. 35).

These three categories are helpful to you as a teacher as they suggest the teaching and learning frameworks that must be set in place so that each student can properly access the curriculum. 


Approximations of Vision with Different Acuities:

 Chart 6 Meters 6-12
The Spirit Of Inclusion: Sensory  Vision Impairment 6-24
Chart 6 Meters 6-60
Examples of what a person with different visual acuities may see at an eye chart at 6 metres by Mike Offord. 


Author: Dolly Bhargava

In two ways: First by measuring a students’ visual acuity and then their field of vision.

Visual Acuity

Visual acuity refers to the ability to see sharply and clearly at both short and long distances to distinguish detail and shape.  Each eye has its own level of visual acuity and the level of visual acuity of each eye can differ considerably.  Visual acuity is usually measured by determining the smallest letter or picture or symbol that a person can read on a standardized eye examination chart.

The visual acuity measurement is expressed as a fraction.  Normal vision is defined as a person having 20/20 or 6/6 visual acuity. The numerator (top number) refers to the distance a person stands from the eye examination chart.  In the United States this number generally represents a distance of about 20 feet.  In countries where meters are used, the distance is 6 meters long, approximately 20 feet.  The denominator (bottom number) indicates the smallest letter, number or symbol that the person can read. The lower the bottom number in the visual acuity ratio, the better the acuity.  The greater the bottom number, the worse the acuity.  For example, 20/100 is a better visual acuity than 20/200 acuity.

Field of Vision

Field of Vision refers to the area within the environment that a person can see when looking straight ahead.  If the field of vision is restricted then the person will miss seeing some parts of the whole scene or image (Orlansky, 1977).  The normal field of vision of is 180 degrees.

Certain measures of visual acuity and field of vision have special significance in terms of diagnosing vision impairments.  We will use these measurements to describe two types of vision impairment that are commonly used in the educational context: (a) low vision, and (b) legal blindness.  It is important to note that definitions of these terms may vary.  However, for the purposes of this handbook they are as follows: 

Legal Blindness

Students who are legally blind:

As an eligibility criterion for government assistance, a legal definition of blindness is used.  In the USA, to be considered legally blind, an individual's visual acuity must be equal to or less than 20/200 with the best possible correction, or a visual field of 10 degrees or less.  Someone with a visual acuity of 20/200 can see at 20 feet what someone without a vision impairment can see at 200 feet.  In countries where a metric system is used a student is considered "legally blind" when his/her visual acuity is 6/60 What a person without vision impairment vision would see at 60 meters is what the student who is legally blind sees at 6 meters or less in the better eye, even with correction. A person who is legally blind has a field of view which is 10 degrees or less in the better eye (Kelley & Gale, 1998).  Blindness cannot be corrected by medical or surgical means or corrective eye wear. The student needs instruction that emphasizes the use of his or her other senses, for example, touch (i.e., Braille) and hearing (i.e., auditory tapes) to learn about the world and complete tasks (Orlansky, 1977; Lewis & Allman, 2000).

Low Vision

Students who have Low Vision:

The definition of low vision for most legal purposes in the United State is a visual acuity between 20/70 and 20/200 with correction in the best eye, or a field of vision less than 20 degrees, compared to normal field of vision of 180 degrees.  In countries using a metric system low vision is denoted by a student having a visual acuity of less than 6/18 (what a person with normal vision would see at 18 meters is what the student with low vision sees at 6 meters) or less or if his/her field of view is 20 degrees or less (Best & Corn, 1993 cited in Kelley & Gale, 1998).   Low vision is not the same as blindness, as the person with low vision has some sight, yet has difficulty accomplishing visual tasks using  sight. “A student who has low vision can enhance his or her ability to accomplish tasks with the use of compensatory visual strategies, low vision devices, and environmental modifications” (Corn & Koenig, 1996, p.4).  This process includes the provision of visual strategies ( i.e., enlarged print); specialized optical devices ( i.e.,  magnifiers or telescopes); non-optical devices ( i.e., bold line black markers) and environmental modifications ( i.e., changing seating position in class) (Lewis & Allman, 2000).  

When determining the needs and abilities of a student with vision impairment it is important to look beyond the label e.g. ‘low vision’ or a numerical value e.g. 20/200.  Instead we need to appreciate the fact that there is no “typical” student with vision impairment.  The impact of the vision impairment on a student will depend upon on the following factors: type of eye condition age of onset degree of functional vision

To help explain this, let’s consider one of these factors. The age of onset of vision impairment has different effects on the child’s communication and cognitive development. Consider the cases of Joanne and Rita, both of whom are six years of age and have a vision impairment.  Joanne was born blind, whereas Rita was born with normal vision but became blind at the age of three as a result of a car accident. One of the areas of development effected by vision impairment is the development of self help skills.  Self-help includes self-routines such as eating, dressing, toileting and grooming. Many of these self-help skills are usually learned through observation.  There are qualitative differences between the self-help abilities of Rita and Joanne.  For example, Rita who became adventitiously blind had the opportunity to see different types of foods, eating utensils, mealtime locations and seen others eat.  Whereas, Joanne who was congenitally blind had never had sight required specific guidance and a variety of experiences in order to understand concepts related to eating.

Therefore, every student with vision impairment has unique needs and abilities. Understanding the background history will determine unique educational support needs and determine the best type of assistance (Anderson, 2003).

  • visual efficiency
  • type of intervention provided


Identify a Student With Vision Impairment

Author: Dolly Bhargava

Sometimes vision problems develop over time or they are so subtle that they have gone previously undiagnosed.  Often a student can have vision impairment, but it may have gone unnoticed.  The student is often the last one to recognize or report a loss in vision unless it has deteriorated.  If the vision impairment remains undetected, it can result in the student facing a substantial educational disadvantage because of adverse effects on the student’s academic, communication, and social development.  This can interfere with a student’s ability to reach full potential.  On a medical note, if the vision problem is left undetected and untreated, it can cause permanent loss of vision and the long-term consequences can be serious in terms of quality of life. 

Consider the case of Koby, a 14-year-old boy who had undiagnosed type 2 diabetes.  The undiagnosed diabetes led to many complications, including progressive cardiovascular disease, kidney disease, and vision impairment.  Sadly,  Koby’s teacher failed to recognize behaviors that were attributable to undiagnosed vision impairment.  Some of them included his constant complaining that the lights in the classroom were too bright, difficulties with copying work correctly from the board and bumping into things in the room.  The effects of the undiagnosed vision impairment were far-reaching and were responsible for reading and writing difficulties that he experienced throughout his schooling.

(Source:  Children with Low Vision: A Handbook for Schools Elmwood Visual Resource Centre, Christchurch, New Zealand)

Teachers need to be aware of the indicators that signal that a student has vision impairment.  Table 1 is a guide that you can use to identify whether  a child in your class has a vision impairment.  

Table 1

Appearance of Eyes
  • One eye turns in or out at any time
  • Reddened eyes or lids
  • Eyes tear excessively
  • Encrusted eyelids
  • Frequent styes on lids
Complaints When Using Eyes at Desk
  • Headaches in forehead or temples
  • ​Burning or itching after reading or desk work
  • Nausea or dizziness
  • Print blurs after reading a short time
Behavioral Signs of Visual Problems
Eye Movement Abilities (Ocular Motility)
  • Head turns as reads across page
  • Loses place often during reading
  • Needs finger or marker to keep place
  • Displays short attention span in reading or copying
  • Too frequently omits words
  • Repeatedly omits "small" words
  • Writes up or down hill on paper
  • Rereads or skips lines unknowingly
  • Orients drawings poorly on page
Eye Teaming Abilities (Binocularity)
  • Complains of seeing double (diplopia)
  • Repeats letters within words
  • Omits letters, numbers or phrases
  • Misaligns digits in number columns
  • Squints, closes or covers one eye
  • Tilts head extremely while working at desk
  • Consistently shows gross postural deviations at all desk activities
Eye-Hand Coordination Abilities
  • Must feel things to assist in any interpretation required
  • Eyes not used to "steer" hand movements (extreme lack of orientation, placement of words or drawings on page)
  • Writes crookedly, poorly spaced: cannot stay on ruled lines
  • Misaligns both horizontal and vertical series of numbers
  • Uses hand or fingers to keep his place on the page
  • Uses other hand as "spacer" to control spacing and alignment on page
  • Repeatedly confuses left-right directions
Visual Form Perception (Visual Comparison, Visual Imagery, Visualization)
  • Mistakes words with same or similar beginnings
  • Fails to recognize same word in next sentence
  • Reverses letters and/or words in writing and copying
  • Confuses likenesses and minor differences
  • Confuses same word in same sentence
  • Repeatedly confuses similar beginnings and endings of words
  • Fails to visualize what is read either silently or orally
  • Whispers to self for reinforcement while reading silently
  • Returns to "drawing with fingers" to decide likes and differences
Refractive Status (Nearsightness, Farsightedness, Focus Problems, etc.)
  • Comprehension reduces as reading continued; loses interest too quickly
  • Mispronounces similar words as continues reading
  • Blinks excessively at desk tasks and/or reading; not elsewhere
  • Holds book too closely; face too close to desk surface
  • Avoids all possible near-centered tasks
  • Complains of discomfort in tasks that demand visual interpretation
  • Closes or covers one eye when reading or doing desk work
  • Makes errors in copying from chalkboard to paper on desk
  • Makes errors in copying from reference book to notebook
  • Squints to see chalkboard, or requests to move nearer
  • Rubs eyes during or after short periods of visual activity
  • Fatigues easily; blinks to make chalkboard clear up after desk task

Students with sensory disabilities have a wide variety of ways to learn and benefit from a curriculum that is shaped to meet their unique needs, skills, interests and abilities.  They may need additional help in the form of special equipment and modifications in the typical curriculum to further develop listening skills, communication, orientation and mobility, vocational or career options, and daily living skills.  But it’s exciting to realize that once we make these modifications, students can become full participants in their classes, establishing lasting friendships, and develop the skills to continue individual growth and pursue knowledge.

Author: Dolly Bhargava

Vision is one of the most important senses.  It plays a vital part in the learning process.  It is held that more than 80% of education is presented through the visual senses (Pagliano, 1994).  Lowenfield (1983), one of the early educational writers in the field, stated that, blindness imposes three basic limitations on an individual in terms of Range and variety of experiences Ability to get about Control of the environment and the self in relation to it.

Many students who are blind or vision impaired experience difficulties with creating a mental map of their environment in order to figure out which direction to go or how to find their way round obstacles to reach their goal (Mason et al, 1997).  It is extremely important that students receive orientation and mobility training to develop concepts, skills, and techniques needed to travel safely, efficiently, and independently in environments.  Orientation skills refer to the thinking skills involved in knowing where we are in relation to the environment and the objects in it and how to find our way to the destination such as knowing that we are at the school bus stop and its location in relation to classroom or the assembly hall or the school office.  Mobility skills involve the actual movement to our destination independently, safely, and with confidence.   For example, if students want to get from their classroom to the school office, they need to be aware of the different clues or landmarks that they can use to independently get there.  A crucial point to keep in mind all of these skills will need to be directly taught. 

The extent to which a student is affected in these three areas will depend on the type and degree of vision impairment, resulting in the student having unique educational and learning needs.  The student with vision impairment may lag behind in achievement in comparison to sighted peers due to the impact of visual impairment on learning.  Therefore, the student will require skills to be specifically and explicitly taught, along with considerable additional time and opportunities to practice these skills.

How do students who are blind or vision impaired develop an understanding of concepts, communication, social, orientation and mobility skills?  How do they develop the ability to independently participate in everyday life activities?  

Understanding Concepts

Vision is the main sense that allows us organize, synthesize and integrate information received from the environment to help us develop concepts about the world and how it works.  In the absence of vision or in the situation of limited vision the student often has to rely on the remaining senses of hearing, touch, smell, movement and taste to help assign meaning to the world. However, learning through the other senses is not always accurate and can sometimes result in a fragmented or partial understanding of the total concept.  For example, feeling a raised outline of a tree is not the same in terms of the texture or size of a tree.  This results in the student developing concepts based on limited and fragmented information as the student is unable to use his or her sense of sight to unify the different parts of the world and develop a complete picture of what is happening.

Blindness and vision impairment result in a limited ability to explore the environment. In the absence of vision or in the situation of limited vision, the student cannot see classroom displays or range of activity options in the environment.  The student will need systematic instruction on how to explore the environment, given the time to explore it in a way that is meaningful.

The development of spatial concepts is also affected by vision impairment. This includes the ability to develop an understanding of where the body is positioned in relation to the classroom environment (Is the student in the front, back, or middle of the room?   What is the distance from classroom objects such as a bookshelf or the teacher’s desk?)  This further impacts understanding of directions such as up, down, right or left, in considering space and distance. 

Our sense of vision provides information on how we look and how others look and interact.  This information is then incorporated into our own interactions.  Students who are blind use other senses such as touch and sound to gain this information, limiting the extent of their knowledge.  For example, knowing what one looks like by feeling one body part at a time may cause “difficulties understanding how all the different parts related to each other” (Lewis, 2002, pp. 63).  And social appropriateness imposes restrictions on touching others. This inability to see others may provoke emotional responses and a sense of isolation.

Time concepts such as morning, afternoon, and night are learned through observation and use.  A child perceives differences between morning and night by seeing and making the connection between nighttime, associated with moon, stars, dark environment, whereas morning equates with sun and light.  For a student who is blind, understanding such environmental concepts is difficult because of limitations with visually associating the concept with the discussion.   We might consider the difficulty of explaining the concept of clouds or stars or the moon in the sky to someone who is blind.

Independent Living Skills

These areas include personal hygiene, food preparation, money management, time management, and skills related to organizing personal space so it is easily accessible.  For example, a child needing to prepare cereal for breakfast should  first be familiar with the kitchen environment in order to locate the cereals, milk, and utensils.  The child needs to know the process involved in preparing cereal, such as getting the bowl, spoon, cereal and milk. Next, it’s necessary to pour an adequate amount of cereal and milk into a bowl and take it to the dining table and afterwards wash and put things back in their original location.  Students who do not have vision impairment learn this incidentally by observing others.  However, students who are legally blind are unable to pick up these skills through observation and need direct teaching of these skills.  

Communication Skills

These areas include receptive and expressive language.  Communication is developed by having a variety of experiences where the involvement is as an active participant or learning by watching others.   Due to visual limitations, the student may have had a limited variety of experiences and missed out on incidental learning.  This effects the student’s understanding and expression.   For example, a student without a vision impairment who has never given a speech before but has watched  peers present would still  have learned how to stand in the front of the room, face the audience, and  speak in a loud voice.  However, a student who is legally blind’s knowledge of giving a speech might be limited to someone talking about a particular topic, requiring direct teaching of such skills. 

Often, students with vision impairments are unable to associate words with discussion topics.  For example, a student who is blind or has low vision may be hearing what the teacher is saying but cannot associate it with the drawing that the teacher has made on the blackboard or a demonstration of how to carry out an experiment.  This may result in the student using or appearing to be comprehending words without fully understanding them.

In the absence of vision, the student may have difficulty identifying the similarities between objects via visual information (Dunlea, 1989) and difficulty with categorization Tobin (1997).  For example, the student may know that an apple is a fruit.  Yet, knowing that bananas, pears, peaches and oranges all belong to the same category although they don’t feel, taste or smell the same is something that  would need to be taught explicitly.

Social Skill Development

The term “social skills” is an all - encompassing one, which includes conversation skills, making friendships, dealing with feelings and classroom skills.  We think of conversations as involving verbal and non-verbal communication.  Non-verbal communication includes body language, facial expressions, gestures, mannerisms, tone of voice and appearance.  A large part of messages is communicated non-verbally, such as through a nod, frown, smile, and shrug.  A great deal of our interaction is based not only on our ability to understand verbal communication, but also the ability to read and understand non - verbal communication. We learn appropriate social behaviours by watching what other people do and copying them. Therefore a student may have good oral language but may lack the more subtle communication skills of gesture, posture, facial expression and general body language, which are so important.

Students with legal blindness do not receive visual information from the environment to know where their friends are in the playground or how to read body language and facial expressions in order to judge how others are feeling or whether what they are saying is being understood or is of interest to others.

Orientation and Mobility Skills

Many students who are blind or vision impaired experience difficulties with creating a mental map of their environment in order to figure out which direction to go or how to find their way round obstacles to reach their goal (Mason et al, 1997).  It is extremely important that students receive orientation and mobility training to develop concepts, skills, and techniques needed to travel safely, efficiently, and independently in environments.  Orientation skills refer to the thinking skills involved in knowing where we are in relation to the environment and the objects in it and how to find our way to the destination such as knowing that we are at the school bus stop and its location in relation to classroom or the assembly hall or the school office.  Mobility skills involve the actual movement to our destination independently, safely, and with confidence.   For example, if students want to get from their classroom to the school office, they need to be aware of the different clues or landmarks that they can use to independently get there.  A crucial point to keep in mind all of these skills will need to be directly taught.


Professionals Who Diagnose and Treat Vision Impairment

Author: Dolly Bhargava

This section presents information on the assessment process and the various team members who can assist the student.  A comprehensive evaluation of the student’s functional vision should take place so that the student can receive appropriate intervention and services (Lewis & Allman, 2000).  To fully evaluate the visual condition, abilities and needs of the student, professionals should use a two - fold approach.   


This involves a vision examination by an eye-care professional (either an ophthalmologist or an optometrist) to verify that the student has a vision impairment.  Table 2 below describes the various roles of the professionals involved in this process.  

Table 2

Health Professionals
Doctor/General Practitioner

Examines the eyes by carrying out a basic visual screening.

Refers patients to the appropriate health care professionals, such as optometrists and ophthalmologists.

Ophthalmologist specializing in low vision

A medical doctor, who diagnoses and provides treatment for defects/diseases/injuries of the eye, performs surgery, prescribes and administers medication for the eye.

Optometrist specializing in low vision



Diagnoses, prescribes glasses, provides vision therapy and low-vision devices.  Provides functional instruction for defects/diseases/injuries of the eye without prescribing and administering medication or performing eye surgery.

Developing an Invention Plan

Once a visual impairment has been identified, step two involves creating a plan for action or the IEP that meets the abilities and needs of the student.  It is important to do this through a team approach.  Table 3 below describes the various team members. The team can be comprised of a variety of educational specialists, such as a certified teacher of students who are visually impaired, and orientation and mobility specialists.  The team also includes other health professionals such as occupational therapists, orthoptists and speech and language pathologists.  The membership of the team will depend on the needs and abilities of the student.  Therefore, your team may not always include all the people listed below. 

Table 3

Educational Staff


Orientation and Mobility Trainer

  •  Works with the vision support teacher to conduct the functional vision assessment as it relates to the student’s ability to travel independently 

  • Prepares sequential and meaningful instruction geared to the student’s assessed needs, IEP goals and objectives, functioning level, and motivational level

  • Teaches students to travel with proficiency, safety, and confidence in familiar and unfamiliar environments

  • Provides consultation and support services to teaching staff regarding classroom environmental modifications, adaptations, and considerations.

  • Encourages the student with a visual impairment to travel independently in these settings

Visiting Teacher for students with visual impairment/ Vision Support Teacher

  • Assesses and evaluates the needs of each child 
  • Explains the impact of visual impairment in terms of current and future implications
  • Offers support to the student (such as teaching Braille, and initiating orientation and mobility skills)
  • Provides advice on necessary adaptations to the school environment needed for the student
  • Assists with  educational programming for the student
  • Provides advice to teaching staff regarding instruction  and classroom management strategies 

Health Professional

  • Role

Occupational Therapist

  • Develops skills for activities for daily living (educational skills such as writing and self-help skills such as washing, dressing, eating)
  • Advises on special equipment, aids, and environmental adaptations that need to be made to maximize independence.

Orthoptist specializing in low vision


  • Works with ophthalmologists to examine the eyes Provides functional instruction for defects/diseases/injuries of the eye
  • Does not prescribe  or administer medication or perform eye surgery 


  • Provides information on options such as optical and non- optical devices, assistive and adaptive techniques for the student
  • Fits, adjusts, adapts and provides optical devices prescribed by an Ophthalmologist, Optometrist, or Orthoptist.

Physiotherapist/Physical Therapist

  • Assesses the student’s gross-motor skills, such as the ability to sit, stand, or walk)
  • Recommends exercises to develop motor skills, increase flexibility, balance and coordination
  • Provide mobility aids

School Psychologist/ Educational Diagnostician

  • Assesses cognitive abilities
  • Identifies student’s learning style and educational needs
  • Develops strategies to meet these needs
  • Works with students who have behavioral or emotional difficulties.

Social Worker

  • Provides family support and counseling
  • Supports the family to access community services
  • Assists the student  accessing programs in the community

Speech/ Language Pathologist

  • Assesses communication skills (receptive, expressive and social)
  •  Provides therapy in order to allow the student to communicate more effectively

As you can see, a variety of professionals can provide support and assistance to help the student participate successfully in the classroom. 


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