What is a visual impairment?
A visual impairment is the consequence of a functional loss of vision, rather than the eye disorder itself. Eye disorders, which can lead to visual impairments, can include retinal degeneration, albinism, cataracts, glaucoma, and muscular problems that result in visual disturbances, corneal disorders, diabetic retinopathy, congenital disorders, and infection.
The effect of visual problems on a child’s development depends on the severity, type of loss, age at which the condition appears, and the overall functioning level of the child. Many children who have multiple disabilities may also have visual impairments resulting in motor, cognitive, and/or social developmental delays.
How is it manifested?
The terms partially sighted, low vision, legally blind, and totally blind are used in the educational context to describe children with visual impairments. They are defined as follows:
- Partially sighted indicates some type of visual problem has resulted in a need for specialized consultation.
- Low vision generally refers to a severe visual impairment (not necessarily limited to distance vision). It applies to all individuals with sight who are unable to read the newspaper at a normal viewing distance, even with the aid of eyeglasses or contact lenses. They use a combination of vision and other senses to learn, although they may require adaptations in lighting or the size of print, and, sometimes, Braille.
- Legally blind indicates that a person has less than 20/200 vision in the better eye or a very limited field of vision (20 degrees at its widest point). Totally blind students learn via Braille or other non-visual media.
Who is affected?
The rate at which visual impairments occur in individuals under the age of 18 is 12.2 per 1000. Legal or total blindness occurs at a rate of 0.06 over 1000. According to the World Health Organization, an estimated 19 million children under age 15 are visually impaired. Of these, 12 million children are visually impaired due to refractive errors, a condition that could be easily diagnosed and corrected.
How is it diagnosed or detected?
Some disorders will be discovered at birth if the vision impairment has observable characteristics such as cataracts or congenital glaucoma. Many, however, go undetected until the child does not meet certain visual milestones.
Generally, if the child is not meeting typical vision milestones by around three or four years, they can be referred to an ophthalmologist. Proper diagnosis cannot be made without a thorough exam from an ophthalmologist.
Canadian National Institute for the Blind (CNIB) – www.cnib.ca
The CNIB provides relevant, specialized services nationwide. They support and/or conduct research about vision to ensure the continued development of services. The CNIB also supports medical research and influences public policy, and the development of technology that helps people who are blind or visually impaired lead independent lives.
Vision Institute of Canada – https://www.visioninstitutecanada.com
The Vision Institute is a not-for-profit optometry clinic. Regular and specialized eye care services are provided to the general public and to persons with special needs. All funds raised support services to persons in chronic care facilities and to persons with visual impairments, brain injuries, developmental disabilities and unique vision problems.
Persons with Disabilities Online – www.pwd-online.gc.ca/
It provides access to services and information for persons with disabilities, family members, caregivers and all Canadians.
Books and Literature:
Essential Elements in Early Intervention: Visual Impairment and Multiple Disabilities
By Deborah Chen
Children with Visual Impairments: A Parents’ Guide
By M. Clay Holbrook