We had a few people who had visual imparments in a club I trained in a few years back. As far as I rember once they were orientated in the dojo they used to just turn up like the rest of us. As far as training goes they only trained with some of the senior students So that they got more focused attention. All there instruction was either verbal or through touch (touch the leg you want them to move, uke would lead their arm movement.). Also as far as I rember if they had a colapseable cane they used this some times (folded) as a guide for their hand coordination (like we would use a bokken). The ukemi practice was broken down a lot, how to kneel down, how to sit down, how to lie back, that tyoe of thing. There was also a big point made about ensuring that they had a big input about how they learnt. Oh and they may have had some private lessons with the sensei before hand (not sure about this) and the first time they oriented them selves in the dojo there may only have been them and the sensei there.
Contact the woman at this dojo. She works for the blind council of Ireland http://www.herondojo.com/
Good luck with it.