i'm sorry to hear this.

I have a completely blind dog. Preacher has progressive retinal atrophy. He's been completely blind for over a year now. You'd never know unless I point it out. He gets around just fine. I can't rearrange my furniture, but that's about it. Preacher finds his way around using his ears and whiskers. He plays with squeaky toys occasionally (he's an older dog so he doesn't play much). I keep his food and water dishes in the same spots. It's fairly remarkable to watch. I was much more upset about him loosing his sight than Preacher was. He just kept going. I bet Onyx will adjust too. I've heard that cats adjust even better than dogs since their whiskers are more sensitive and provide more guidance. I hope Onyx makes a smooth adjustment.