Why has my cat's eye gone cloudy?

[epithet]

It looks like some kind of conjunctivitis thing - it's weepy as well.

Thing is, a couple of months ago, we came back from holiday to find that her other eye was virtually opaque (PILs had been looking after the cats), which we assumed must have been a sudden decline or they would have noticed (I'd hope). Vet was worried it might be serious, but when it cleared up very quickly she decided it was probably the result of a nasty scratch in a fight or similar.

But now the other eye is looking funny. Could it be something sinister?

This is probably not the case with your cat BUT...

My old cat (age 14) had something similar, a very cloudy looking eye which had come on very rapidly but didn't improve. The vet took a blood sample and it showed his renal function was very poor. We tried some medication but it didn't make any difference and we had him put to sleep.

You need to call the vet and get this looked at asap - it may, or not be related to what happened in the other eye.