He's only two, but we've noticed he seems a bit quiet for himself recently. He's not purring or exploring as much as he normally does. And DD said he had 'really big eyes' .
The vet says he's lost his sight. 
We are paying for some tests (blood pressure, eye pressure in case of glaucoma) that the vets can do, but will then have to consider whether to explore getting an opinion from a specialist, which will be pricey. Of course, he's not insured which is our own fault.
I'm feeling very sad for him. We hope he will adjust but don't know if he will.