Tips for Low Vision People to Use Computers
Tip No.1--Powerful Tools-Screen Magnifiers
The most common technology that people with low vision use is the screen magnifier. This is a software program that zooms in on a small area of the screen, allowing people with low vision to see it more clearly. Common screen magnifiers include ZoomText and MAGic.
Some kinds of content are difficult to interpret when enlarged. For example, graphics that contain text can become blocky and pixilated, making the text difficult to understand. Take a look at the two images below. The one on the left is a screenshot of text that has been enlarged. The image on the right is a screenshot of text within a graphic that has been enlarged.
To make text more legible when enlarged, use true text as much as possible, rather than text in graphics.
Tip No.2—Adjust to High Contrast
Sites with low contrast can be difficult to read for people with low vision. Some poorly designed sites on the web have bad color combinations such as blue links on black backgrounds, red text on green backgrounds, or other combinations that are not easy on the eyes for anyone, but especially not for people with low vision. There's no hard rule as to how much contrast is enough, but use your best judgment. However, it's usually not too difficult to tell when color combinations do not contrast adequately.
Experience it for yourself
Here are some ideas for roughly simulating low contrast vision:
• turn down the contrast on your monitor
• look at your monitor through a tissue or a piece of tracing paper (this technique is more successful on laptop and flat LCD monitors than on full-size monitors)
To the extent possible, maximize the contrast of your web pages, including graphics, fonts, and backgrounds.
Tip No.3--Overriding Font and Background Colors
Some people with low vision will change the settings in their operating system and/or browser to not only enlarge the text, but to increase the contrast of the text in relation to the background. Some people like to have a black background with white or yellow text. Others prefer to have a white or yellow background with black text. These are the most common settings, but there other people prefer other high contrast settings. See the images below for examples of how these settings can appear:
Here's something to remember:
To allow people to customize their contrast settings, it is better to put as much text as possible in true text format, rather than in graphics.
Tip No.4--Horizontal Scrolling
This last point is not so much a matter of accessibility as it is usability. You have probably come across web sites that require you to use your horizontal scrollbar to see the content on the right of the screen, even though you had your browser window maximized. This can be a bit annoying to people with perfect vision, but it is even more so for people who use screen magnifiers and are forced to scroll even further to the left and right inside of the small enlarged space they are viewing.
To the extent possible, use percentages, rather than absolute units (e.g. pixels), in your document layout.
The general rule when designing for low vision is to make everything configurable. If the text is real text, users can enlarge it, change its color, and change the background color. If the layout is in percentages, the screen can be widened or narrowed to meet the user's needs. Configurability is the key.