I try to make it a habit to look at people’s eyes whenever I talk to them so I don’t think I would stray from this even if I were talking to a blind person. Even if you don’t look at their eyes, they’re not going to know about in anyway, maybe.
I’ve been told that blind people have heightened senses of hearing to compensate for the loss of vision. If you’re talking to a blind person and you’re not looking at their eyes or even their face, they might be able to detect a change in volume in your voice and interpret this to mean that you’re not fully paying attention to them. This is speculation on my part but I think it could be accurate.