I don't think it's possible for them to play on this site without assistance. For what it's worth, there are softwares like JAWS to help vision impaired people use windows. It reads selected text, window titles, warnings, etc, but not sure how it could help with the whole site. For example, I don't see a possible way for any software to read aloud the move your opponent has played.
The chess program Chessmaster is a lot easier for the vision impaired to play chess: it tells what move is played out loud, and you can type in the move you want to play. I'm not sure how it will tell you how much time you have left, though.
Anyone member is a blind chess player?
Which is the better way to play chess for him?
How to select a match from the online chess list?
How to get the opponent move?
How to move?
How to select the moves tab and the get pgn button?
Is it possible to write the move textually?
and many, many other questions. Thx to all.