Jack our black toy poodle only had one eye (some rotton breeder poked his other out) and when he lost his sight in the other i think i was more bothered than he was!
its right,just letting them know you are around or approaching them and i think they take it all in their stride,and we also had a sighted poodle (first Frankie then Christie) and like the previous reply the sighted dog does lend a hand and help their pal.
Its always a big desision to take a 'dig dog' into your home and if you have got the love and paitence to start off with then your nearly home dry!...
Please let us know what you decide,and remember it has to feel 'right' for you.