Anyone got any good comebacks?

I can understand that his remarks make you feel uncomfortable, but he is just showing his rudeness and lack of sensitivity. Believe me, people notice those things, and he, not you, is the actual target of ridicule. The best way to handle this is not to pull yourself down to his level. By making fun of his mother's blindness, you are playing to his tune, and making fun of the poor woman who isn't even there to defend herself. That's not fair, because she is innocent. Just ignore him completely, and pretend he doesn't exist. He will soon discover just what kind of loud-mouthed fool he is making of himself.