I have to say i wonder why your vet came out with that as a suspicion, cats taken to the vets with suspected FIP generally dont have eye issues (mine cried in pain when her tummy was touched, my neighbours was sickness and diarrhea - we have both only dealt with it once, and I have had nearly 50 cats in 5 years, nto sure on my neighbour, but she did rescue for 9 years and has owned cats for 25). I personally wouldnt have the test done, i had 2 cats when I dealt with it, and despite having one pts due to it, they told me it wasn't worth testing Ginger - and they shared a tray, which is the most common way of catching it. Tig went down very quick, I had 2 weeks with her, but I have read that cats with dry FIP (the 'better') kind, can have up to a year. Good luck with her - neither me nor my neighbour had cats of 'typical' age for it, although when I Read up on it for my neighbour, some sites did mention the young and elderly being the most common groups (Tig was only 5, the only young cat I have owned)