Vision impairment or even blindness should not (by itself) prevent someone from using a computer. Choosing the right assistive technology devices will depend on the type and extent of the vision impairment.
Screen magnification products enlarge text and pictures to a standard range of sizes more easily viewed by a person with limited vision. Although free standing magnifiers that attach to the computer monitor can be purchased, the most versatile technologies are software programs with features that allow for magnification of the full screen, parts of the screen or provide a magnifying glass view of the area around the cursor or pointer. These programs typically allow for changing the background and text colors in order to provide better contrast to maximize existing vision. Many of the commercially available screen magnification programs also offer speech output so the user can hear - as well as see - the text, menu items and message boxes.
A different approach to computer access is necessary when there is an absence of functional vision. These technologies rely on hearing and touch to compensate for the loss of sight. Screen reader programs convert text into speech so that the screen contents are spoken to the user. Screen reader programs designed for persons who are blind also provide navigational features so that the user can identify the location of the cursor on the screen. Proficient Braille users can utilize a refreshable Braille Display in conjunction with the screen reader program. These devices connect to the computer by a serial cable and produce a dynamic Braille display that changes with each new line of text.
Another type of assistive technology product beneficial to persons with vision loss is Optical Character Recognition (OCR) Software. OCR allows external documents such as newspaper articles, recipes, bills etc, to be scanned into the computer and the text electronically stored. It can then be edited and used by screen magnification and/or screen reader programs. Let's take the recipe as an example. Your neighbor tells you about an enticing recipe for brownies that she cut out of a magazine. OCR software allows you to scan it into your computer; the screen magnification program then enlarges to a size you can comfortably read and even edit.
Lastly, keyboards can be enhanced to provide higher contrast lettering for better visibility and less eyestrain caused by peering at your keyboard, even in low light conditions. The letters, symbols, and numbers are 43 percent larger than those on a standard keyboard, so you can see them better and more comfortably.
