I recall a thread where someone pulled out one of many pages from the manga to support their claim about Kakashi knowing about his MS from the start. It was the scene where Kakashi asks Itachi "How's your sight these days" or something, and Itachi is surprised that Kakashi has gained the MS. So from the context, it can be read that Kakashi is going partially blind as any other Uchiha from the MS, which is what he was alluding to when he said that to itachi, b/c Itachi would know what he was actually referring to, which in that case, was to let Itachi know that he too had the MS, and shared the same after effect.
So both Kakashi and Obito should be going blind, as Kakashi has alluded to his own blindness via the manga. But in Obito's case...Senju DNA.
