There was a physics professor at OSU who lost his sight some years ago. I once asked him if he thought a blind man [visually impaired] can learn complex mathematics. I am such a visual learner that it was hard for me to imagine learning math without having vision. He was admittedly quite perplexed by this question and said that he didn't know; he would have to think about it. But since then I have seen that at least a few people who have been blind from birth have obtained advanced degrees in mathematics and physics. But how they do it is a mystery to me.