Hiya, I have had no experience of this particular problem, but with a bit of luck you will have caught it early enough and the medication may help him regain partial sight, if not completely.
I have had a cat that needed an enucleation (sp?) eye out in other words, and she has adapted amazingly to just having sight in one eye. With indoor cats their quality of life need not be any different if they get disabilities like this. You hear of cats having a leg amputated and then running around playing with the other cats quite normally. So think positive and even if worse comes to worse you can still give your cat a happy lifestyle
