It is indeed difficult but not impossible although it will require a text-to-speech if the visually impaired person is using. Of course, there's always a way to make things possible for them but someone should fund this kind of project to let the blind people to do trading. The fact that it looks as a handicap already to them I won't say that a blind traders won't make a mistake if the voice is unclear. I can only think a lot of trial and errors for this to possibly happen in the future.