A screen magnifier can make a document readable to a person with low vision.
Low vision encompasses a variety of issues, including problems with focus or clarity, farsightedness, nearsightedness, and tunnel vision.
If people have low vision, they will probably have their computer display set up in the best way for them. This could include high contrast color schemes, large fonts, and large icons. They might also be using devices such as magnifiers.
Therefore, it is important that your document displays in the reader's selected contrast and display settings. As you saw in the last practice session, the screen appearance can change drastically. Don't rely on your choices of font, size, and color being displayed with the document—or displayed at all if a text-only setting or screen reader is being used.
Even if your readers can adjust their computer display settings, you should avoid using too small a font for all of your readers. As a general practice, the smallest font size you should use is 10 points.
Some color combinations are very difficult to see. This is not just for people who are color blind but for everyone reading your document. If you can't read something clearly, then don't use it. For example, avoid yellow text on a white background; pale blue is also problematic as blue is the first range of vision to deteriorate with age. Although you might be able to read a blue font, an older person might not be able to. Remember your older readers and avoid pale blue text.