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Article disclaimer

This page contains and edited (by Lahle Wolfe) version of an article on Blindness from Wikipedia.com


Diabetes Resources 2004-2005: Equipment, Services, Information - Published by the Diabetes Action Network of the National Federation of the Blind

$5 per copy, available in large print, 15/16 IPS audiocassette, or Braille

Order from:

National Federation of the Blind
Materials Center
1800 Johnson Street
Baltimore, MD 21230-4998
Telephone: (410) 659-9314

(Materials Center is open 8:00 a.m. to 5:00 p.m. EST, weekdays)


Support, Information and Resources

Access Watch: Blind users review accessibility of mainstream software

A Comprehensive Directory of Blindness Information

American Council of the Blind

American Foundation for the Blind

Blind Access Journal: Visual impairment in the real world

VISION 2020: The Right to Sight

International Agency for the Prevention of Blindness (IAPB)

International Braille Research Center

Literature Bibliography and Resources List

National Braille Press

National Federation of the Blind: Civil rights and consumer advocacy

National Library for the Blind

National Library Service for the Blind and Physically Handicapped

Recording for the Blind and Dyslexic

Royal National Institute for the Blind

Scottish Sensory Centre

WHO Fact Sheet on Visual Impairment

 

islets of hope diabetes medical library                      back to main "Complications" page
Long-Term Complications of Diabetes                                                    Also, see Diabetic Retinopathy

Blindness and Diabetes
Causes, Aids & Tools for The Blind


Mini Site Index
What is the Definition of Blind?
Causes of Blindness
Adaptive Techniques
Tools and Aids for the Blind
Social Attitudes About the Blind
Resources

What is the Definition of Blind?

Blindness can be defined physiologically as the condition of lacking visual perception. The definition as it applies to people thus legally classified is, however, more complex.

"Blindness" also applies to partial visual impairment: In North America and most of Europe, legal blindness is defined as visual acuity (vision) of 20/200 (6/60) or less in the better eye with best correction possible. This means that a legally blind individual would have to stand 20 feet from an object to see it with the same degree of clarity as a normally sighted person could from 200 feet. In many areas, people with average acuity who nonetheless have a visual field of less than 20 degrees (the norm being 180 degrees) are also classified as being legally blind.

Approximately ten percent of those deemed legally blind, by any measure, are fully sightless. The rest have some vision, from light perception alone to relatively good acuity. Those who are not legally blind, but nonetheless have serious visual impairments, possess low vision.

By the 10th Revision of the WHO International Statistical Classification of Diseases, Injuries and Causes of Death, low vision is defined as visual acuity of less than 6/18, but equal to or better than 3/60, or corresponding visual field loss to less than 20 degrees, in the better eye with best possible correction. Blindness is defined as visual acuity of less than 3/60, or corresponding visual field loss to less than 10 degrees, in the better eye with best possible correction. Visual impairment includes low vision as well as blindness.  

    


Causes of blindness

Serious visual impairment has a variety of causes:

Diseases

Most visual impairment is caused by disease and malnutrition. According to WHO estimates in 2002, the most common causes of blindness around the world are:

  • cataracts(47.8%),
  • glaucoma(12.3%),
  • age-related macular degeneration (AMD) (8.7%),
  • trachoma(3.6%),
  • cornealopacity (5.1%), and
  • diabetic retinopathy (4.8%), among other causes.

People in developing countries are significantly more likely to experience visual impairment as a consequence of treatable or preventable conditions than are their counterparts in the developed world. While vision impairment is most common in people over age 60 across all regions, children in poorer communities are more likely to be affected by blinding diseases than are their more affluent peers.

The link between poverty and treatable visual impairment is most obvious when conducting regional comparisons of cause. Most adult visual impairment in North America and Western Europe is related to age-related macular degeneration and diabetic retinopathy. While both of these conditions are subject to treatment, neither can be cured.

In developing countries, wherein people have shorter life expectancies, cataracts and water-borne parasites—both of which can be treated effectively—are most often the culprits. Of the estimated 40 million blind people located around the world, 70–80% can have some or all of their sight restored through treatment.  


Adaptive Techniques

Visually impaired and blind people have devised a number of techniques that allow them to complete daily activities using their remaining senses. These might include the following:

  • Adaptations of banknotes so that the value can be determined by touch. For example:
    • In some currencies, such as the euro and pound sterling, the physical size of a note increases with value.
    • A lot of banknotes from around the world have a tactile feature to indicate denomination in the upper right corner. This tactile feature is a series of raised dots, but it is not standard Braille [1].
    • It is also possible to fold notes in different ways to assist recognition.
  • Labeling and tagging clothing and other personal items
  • Placing different types of food at different positions on a dinner plate
  • Marking oven, dishwasher, and dryer dials for ease of use

Most people, once they have been visually impaired for long enough, devise their own adaptive strategies in all areas of personal and professional management.  

    

Tools and Aids for the Blind

Designers, both visually impaired and sighted, have developed a number of tools for use by blind people.

Mobility

People with serious visual impairments can travel independently using a white cane, the international symbol of blindness.

A long cane is used to extend the user's range of touch sensation, swung in a low sweeping motion across the intended path of travel to detect obstacles. However, some visually impaired persons do not carry these kinds of canes, opting instead for the shorter, lighter identification (ID) cane. Still others require a support cane.

Each of these is painted white for maximum visibility, and to denote visual impairment on the part of the user. In addition to making rules about who can and cannot use a cane, some governments mandate the right-of-way be given to users of white canes or guide dogs.

A small number of people, about one percent, employ guide dogs. These companions are trained to lead blind individuals around obstacles on the ground and overhead. Though highly intelligent, guide dogs neither interpret street signs nor determine when the team ought to cross a street. Visually impaired people who employ these animals must already be competent travelers.

Reading and Magnification

Most blind and visually impaired people read print, either of a regular size or enlarged through the use of magnification devices. A variety of magnifying glasses, some of which are handheld while others rest on desktops, can make reading easier for those with decreased visual acuity.

The rest read Braille and Moon type or rely on talking books and readers. They use computers with special hardware such as scanners and refreshable Braille displays as well as software written specifically for the blind, like optical character recognition applications and screen reading software.

Some people access these materials through agencies for the blind, such as the National Library Service for the Blind and Physically Handicapped in the United States, the National Library for the Blind or the RNIB in the United Kingdom.

Closed-Circuit Televisions, equipment that enlarge and contrast textual items, are a more high-tech alternative to traditional magnification devices. So too are modern web browsers, which can increase the size of text on some web pages through browser controls or through user-controlled style sheets.

Computers

Access technology such as Freedom Scientific's JAWS for Windows, screen reading software enable the blind to use mainstream computer applications. Most legally blind people (70% of them across all ages, according to the Lighthouse for the Blind) do not use computers. Only a small fraction of this population, when compared to the sighted community, have Internet access. This bleak outlook is changing, however, as availability of assistive technology increases, accompanied by concerted efforts to insure the accessibility of information technology to all potential users, including the blind.

The movement towards greater web accessibility is opening a far wider number of websites to adaptive technology, making the web a more inviting place for visually impaired surfers.

Experimental approaches such as the seeing with sound project are beginning to provide access to arbitrary live views from a camera.

Other aids

People may use talking thermometers, enlarged or marked oven dials, talking watches, talking clocks, talking scales, talking calculators, talking compasses and other talking equipment.  

    


Social Attitudes Towards The Blind

Historically, blind and visually impaired people have either been treated as if their lack of sight were an outward manifestation of some internal lack of reason, or as if they possessed extrasensory abilities. Stories such as The Cricket on the Hearth by Charles Dickens provided yet another view of blindness, wherein those affected by it were ignorant of their surroundings and easily deceived.

The authors of modern educational materials (see: blindness and education for further reading on that subject), as well as those treating blindness in literature, have worked to paint a truer picture of blind people as three-dimensional individuals with a range of abilities, talents, and even character flaws. Certain individuals are gifted, and others licentious, but nothing definitive can be said of the blind as a class but that they cannot see well.  

    


Resources

National Federation for the Blind - The Federation's primary national publication, the monthly Braille Monitor, deals with all aspects of blindness and is offered in print, Braille, and on audiocassette. The NFB is also the only national organization of the blind with a publication about diabetes and blindness—Voice of the Diabetic. The NFB's many divisions focus on specific aspects of blindness, and its Aids, Appliances, and Materials Center functions as a low-cost outlet for equipment and information for the blind (hours of operation are 8:00 a.m. to 5:00 p.m. EST, weekdays). To learn more about the National Federation of the Blind and its divisions, or to obtain copies of the Materials Center's free catalogs (in large print or Braille), contact the address above or find many of its publications on the World Wide Web, or on their BBS: www.nfbnet.org.  (The Voice can also be accessed on the World Wide Web at: http://www.nfb.org/voice.htm)

NFB-NEWSLINE®  - A unique NFB service that collects electronic versions of both national and many local newspapers (on the day of publication), alters them to simple text-only format, and electronically distributes them to local centers. Registered blind people can telephone local numbers, follow a pushbutton phone menu, and have the DECtalk speech synthesizer read them all or any part they choose of any available publication. It is not the Internet and does not require a computer or other hardware—just a touch-tone telephone. Newsline provides immediate access to major newspapers for the blind—more efficient than "human reader" services, and much faster than waiting for a recorded tape to arrive in the mail. Newsline costs the blind user nothing. For more information, contact the NFB at the address above, or call: 1-888-882-1629.

International Braille and Technology Center for the Blind (IBTC)  - The National Federation of the Blind maintains, as a public service, examples of every adaptive computer with speech or Braille output. The IBTC, the world's largest computerized technology demonstration and evaluation center for blind people, offers expert advice on choice of computer hardware and programs. It is open to both agencies and individuals. No products are sold at the Technology Center, so equipment is judged impartially. For information contact the IBTC Director, at the NFB address above.

    

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Page Updated 03/06/2006