Not every visually-impaired individual is blind-- a large number of people just need larger print to see well. Most computer operating systems have some form of magnification program and a number of keyboards and other peripherals come with additional software which can help magnify images and text.
Some websites (especially those with multiple columns) look perfect on the screen on which they were designed, but if viewed on another computer monitor, or at a different screen resolution "fall apart" (i.e., the text or graphics superimpose on top of one another). A very simple test is to view your website at different screen resolutions. In Windows, for example, you can simply right-click on the desktop, click on "Properties" or "Personalize" and then select "Display Settings." On the "Display Settings" page, you can change the resolution of your screen by sliding the pointer to the left or right in the "Resolution" section of the page.
Example Four discussed font size, which is an independent, and equally relevant consideration; we suggest that you consider each of these variables and view your website on different computer monitors, with different operating systems, at different magnifications and with different size fonts (both the size of the fonts you choose for your website and the size of the fonts the user has enabled in their computer will have relevance on this issue.