Because the Web does not explicitly support screen magnification, Low Vision users should use a third-party tool, such as ZoomText to enlarge the screen, and select the Accessibility settings in Internet Explorer to improve contrast.
The Web supports Low Vision users by:
Ignoring background bitmaps.
Supporting the color scheme defined on the client computer when Internet Explorer Accessibility settings are checked.
No Vision settings are also available to users who are logged in as Low Vision users.