Assistive technology that supports functional usage of computer technology by people with visual disabilities usually comes in two distinct varieties. Either the technology alters the way that the visual information is presented or it translates the visual information into data that can be received by a different sense, like hearing or touch. The first type of assistive technology is aimed at persons with low vision or visual acuity disabilities. This population can also utilize the second variety of assistive technologies though persons who are blind are the primary users.
Visual acuity and low vision deficits manifest themselves in the inability to focus on small objects. The adaptation for this deficit would be to make the objects larger. By increasing the size of the text on the screen, information that was initially not readable can be read. An easy way to increase the size of text on a computer is to set the resolution of the screen or monitor to a low number. If your monitor is usually set at 1024x768, try setting it to 640x480. The font should now show up as larger on the monitor. If this does not provide enough text size increase, Microsoft has included a program named Magnifier in the current MS Windows® operating system (Start button > Programs > Accessories > Accessibility > Magnifier). There are also specialty programs that can adjust onscreen font size even more if needed.
Besides being able to adjust the size of the information on the screen, being able to increase the contrast of the information allows improved readability for certain people with low vision. This process strips out background colors and changes the color of text. Bright white text on a black background or black text on a bright white background will usually be easier to read than gray text on a parchment colored background. To see what this looks like on an MS Windows XP® computer, click Start > Settings > Control Panel > Accessibility Options. Then click on the Display tab and check the "Use High Contrast" checkbox. After clicking Apply, your screen will change to a high contrast version.
The second variety of adaptation is to translate the visual information into a form accessible by a different sense. The most common is hearing. In this process, text that would normally be read on the screen is read by the computer through its speakers. Here is an example of a common software package known as Jaws® reading the opening page of this article. As you can tell, while this is very understandable, it requires a lot of concentration to follow the computerized voice.
Another sense that is used to replace vision is touch. The Braille language does this by representing text as bumps that are identified by the reader's fingers. Information can be printed on a piece of paper but as you can imagine, this would get fairly expensive in paper costs. Printers too that are used to do this, known as embossers, are louder than current inkjet and laser printers, sometimes much louder. Another tool that can be used is known as a Braille display. This device actually has little bumps that move up and down to form Braille letters or words. The bumps are electronically controlled so that text can be passed under the fingers of the reader. While this is usually a good solution for a person with blindness to interface with a computer, they are fairly expensive.
So what makes web pages easier to read for someone using an alternate means of reading? Lots of times it will be the same things that will make them easier to read for persons without a disability. Clear, structured sentences that present information in a logical manner helps everyone. There are, however, some things that make web pages more accessible to alternate reading methods.
When making a web page, put a hidden link at the top of each page that has navigation links on it. This link needs to be named something like "skip navigation" and it allows someone listening to a screen reader to skip the reading of the navigation section and go directly to the content of the page. Can you imagine how tiring it would be to have to listen to, or feel a Braille display presenting, all the navigation links every time you clicked on a new page? It is also customary to have the navigation links at the top of the page so that a person can hear them first if they actually want to jump to another area. How is the "skip navigation" link hidden? By making it the same color as the background of the web page.
With the above requirements to put the navigation at the top of each page, it might seem a little limiting to your page design. If we only had straight HTML on the web it really would be limiting. However, with the advent of Cascading Style Sheets (CSS) you can actually have the menus at the top of the page yet have them displayed anywhere on the page. With CSS, the page changes the way it looks depending on how it is being viewed. This page is an example. It has a header across the top, the navigation links on the left, and the content on the right. However, click here to see what the layout would look like to a text-based device such as a screen reader or a Braille display. The first thing you see is the hidden link, followed by the navigation links and finally, the main content of the page.
Another action that assists the readability of a web page on a text-based system is the use of structured formatting. Instead of just changing the font size and type to indicate topics and headings, use the built-in delineators that have always been part of HTML. The largest is H1. This is the first order heading and can be set at the beginning to be whatever size and type of font you want. Heading information can be identified as different level of subheading from H1 through H6.