Low Vision and Blindness: Causes and Prevention

Causes

Almost half of the children who are blind have the disability because of prenatal factors, mostly hereditary. Researchers are working to identify genes that cause some forms of blindness. The gene that causes retinitis pigmentosa has now been located and isolated, and there is hope for a cure in the near future. Other medical advances—such as laser treatment, surgery, and corneal implants—also help to reduce the incidence of visual disabilities among children or to lessen their severity. Although medical advances have reduced the prevalence of visual disabilities in children, medical technology can cause increases in this disability as well. Today more infants survive premature birth and very low birth weights of even less than two pounds. The result, however, is often the child having multiple disabilities, frequently including visual disabilities (Dote-Kwan, Chen, & Hughes, 2001; Hatton, 2001).

Prevention

In many cases visual disabilities can now be prevented, but a great deal more could be done. For example, the incidence of visual disabilities can be greatly reduced by protecting against eye injuries (Prevent Blindness America, 2005a & b). In many cases, prevention is truly the application of common sense and reasonable safety measures. Each year thousands of children under the age of five have eye injuries (Prevent Blindness America, 2005a). These accidents occur at home, at school, or in the car, and many of them could be prevented. Putting sharp objects (even pencils) out of the reach of children, being certain that toys are safe, and getting help as soon as possible when injuries do happen can make all the difference. Early treatment can avoid a lifetime of visual problems.

For those visual disabilities that cannot be avoided, their impact can be lessened through early and consistent treatment. Unfortunately, not all U.S. children have early access to health care. In fact, poor children are between 1.2 and 1.8 times more likely to have visual disabilities (Sherman, 1994). Considering the long-term costs to society and to these individuals, the problem of access to health care must be addressed.

Overcoming Challenges: Technology

The telephone and the phonograph are examples of technological advances that were created for the general population but have special benefits for people with visual disabilities because they offer inexpensive access to both entertainment and information. Large-print books, computerized versions of popular novels, audio versions of books, and computers are other examples of items developed for the general population that have increased the access of people with visual disabilities to mainstream society. Everyone now has greater access to printed information through electronic books and laptop computers that enable the reader to increase the size of print or to switch from print to voice easily.

These exciting technological advances open up a new world for people with visual disabilities. Clearly, these advances facilitate their participation and give them independence in all aspects of modern society. However, three major barriers inhibit their access: cost, complexity, and information. With the average costs of assistive devices ranging from $1,000 to $10,000 and the vast number of options available, careful selection of the right equipment is important. However, as we noted earlier, when equipment is developed for the mass market (cell phones are a good example), people with disabilities also benefit because the devices are both accessible and affordable (Fruchterman, 2003). Assistive devices can be grouped into three categories:

• Visual input devices
• Audio input devices
• Tactile input devices

Visual Input Devices

Visual input devices are equipment or technologies that help people with visual loss access visual information in the environment. Many of these devices are used to enlarge print so that it is easier for a person with visual loss to see and read. For example, closed-circuit television (CCTV) technology allows video magnifiers to enlarge the print found in printed texts and books (American Association of Retired Persons [AARP], 2002; Lighthouse International, 2005). By means of a small television camera with a zoom lens and a sliding reading stand on which the printed materials are placed, greatly enlarged printed material (up to 60 times the original size) can be viewed on a television monitor. Another version, the Magni-Cam, has a TV camera embedded in something that looks like a computer mouse and can roll aver printed pages. Such equipment provides immediate access to all types of printed materials, such as magazines, textbooks, and photocopied handouts.

Other equipment can also' increase print size. Far example, overhead projectors, although they are not useful to most individuals with low vision, can be used to enlarge printed materials. Personal computers can produce large-print displays on the computers' screens, allowing persons with low vision to adjust the size and style of print to match their own visual efficiencies. Accompanying printers permit the user to select different sizes of print far hard-copy printout. These features enable teachers to prepare different versions of handouts—one version for students with visual disabilities and one for sighted classmates. Remember that most standard copy machines can also adjust print size.

Audio Input Devices

Audio input devices are equipment or technologies that enable people to hear what otherwise would be read or seen. An example is "talking ATMs." Despite much controversy nationally, Bank of America in California is making these audio-capable banking machines available (Grupe, 2000). Talking books have been available through the Library of Congress since 1934 and today can be found at mast bookstores. The American Printing House for the Blind provides compressed-speech (eliminating natural pauses and accelerating speech) versions recorded on tape and CDs; these can be ordered from regional resource and materials centers. Developed far the general public, audio versions of many classics and current best-sellers offer people with visual disabilities greater access to books and print materials.

Another technique enables people with limited vision to enjoy plays, movies, television, and home videos. Audiodescriptions are orally presented narrations of nonverbal cues and visual information presented an the screen or stage. This system, initially developed for television by Margaret Pfanstiehl, uses the added sound track available in stereo' televisions to describe aspects (such as costumes, scenes, sets, and body language) important to a fuller understanding of the story. A similar system has been devised for theaters; it uses an earphone and a tiny FM receiver. The explanations occur in the speech pauses or otherwise silent parts of the film or play. This accommodation is not so common in movie theaters, because many owners of cinema chains do not want to spend the $15,000 it takes to equip a theater, even though new systems, allowing far both captions for deaf movie-goers and audiodescriptions for blind patrons, are now available (McMahon, 2000). TV shows that have audiodescription versions are becoming more common, because the second audio track that is necessary to play the descriptions is now included an most TV sets (Descriptive Video Service [DVS] , 2005).

Tactile Input Devices

Tactile input devices are equipment or technologies that allow people to use touch to gain information. For example, a well-known tactile system is braille, which allows people to read by feeling letters that have been translated into patterns of dots raised or embossed on a flat surface such as paper. Those people who use braille as their preferred reading method find the Perkins Brailler to be a compact and portable machine that embosses special paper with the braille code. The Perkins Brailler is inexpensive but less efficient than electronic versions that use microprocessors to store and retrieve information. For example, Braille 'n Speak functions as an organizer, note taker, calendar, and talking clock. The new (though expensive, costing almost $6,000) braille PDA gives its users, through wireless technology, access to the Internet, a planner, speech output, and phone service.

Personal computers with special printers transform print into braille. When a specially designed braille printer is attached to a microcomputer, standard text can be translated into braille, allowing a teacher who does not know how to use braille to produce braille copies of handouts, tests, maps, charts, and other class materials. And some new printers, such as the ones made by American Thermoform, even produce braille and print on the same page.

Another limitation of braille versions of text has also been overcome. Only a few years ago, diagrams and illustrations were omitted from braille versions because there were obstacles to producing them. Today one system, Tactile Access to Education for Visually Impaired Students (TAEVIS), uses a special type of paper, backed with plastic and coated with a heat-sensitive chemical, to produce raised versions of diagrams (Tennessean, 1999). Clearly, technology continues to improve access to the world of print for individuals with visual disabilities.