Cats eye worries?

Hello, I am looking for advice on my new cat. For starters I just recently took her in from someone who was re-homing a bunch of cats and kittens about 2 weeks ago. The person I got her from stated the cat had no health issues or anything, just a small flea problem and shes not updated on her shots. (not an issue i can deal with that)  However after showing some pictures of Marcy (the cat) to my sister they pointed out to me that one of her pupils is larger than the other, I had already noticed her eyes were a bit crossed eyed but i hadnt noticed her pupils. I did some research and learned that it could be a symptom of ALOT of different things. I know it could be nothing, but I also know it could be something serious, and not knowing her past or medical history worries me a little more. Marcy doesnt really display any symptoms of being sick or injured in any way but i’m not 100% sure what to be looking out for. Shes been adjusting well to her new environment, shes been eating well, shes playing, shes been loving pets and attention, she seems to be doing pretty good to me but i’m still just a little worried because I’m genuinely not sure if its just a weird quirk of hers or if its serious. Is there anything i can do? Or anything to look out for? Should i treat this as an emergency and have her seen as soon as possible? She is not my first pet/cat but she is the first cat i’ve owned while on my own so i could very well just be over-paranoid about it, but i would hate for anything to happen to her shes a super sweet baby and we’re already bonding very well. Thank you in advance.  :)   PS: I DO plan on taking her to the vet regardless! Because like i said i dont know any of her medical history and of course her shots, however i am not in the position where i can just get up and go spend a few hundred dollars at a vet. it will not be months before i get her into an actual appointment i can assure that, but if this is an emergency and she should be seen asap  then of course i will treat it as such and do everything i can.

Hello!  Thankyou for this tricky question.  I will rely on what you explained as a given, that one pupil is bigger than the other. This could be an old problem that is not changing / worrying the kitten at present, BUT it could also be a sign of a very severe underlying disease and I have no way of knowing which is causing it, from here - it could also be both (and old problem AND threatening the kitten) at this stage.   The pupil being the black part in the centre of the eye, is actually a 'hole' in the centre of the iris, which lets light in (with some clear fluid and then the front of the eye, the clear cornea, over the top).  In a healthy eye, the iris changes size to control the shape of the pupil;  the pupil gets bigger to let more light in or smaller to restrict light from entering.

In a cat, the pupil is more of a slit, or tall oval, than a round 'hole' which is normal in the human eye.

If one eye is bigger than the other, it suggests that one of the following may be true:   a) the eye might be blind, so the light is either not hitting the retina or not being detected or that message not being sent to the brain. Any of these result in not sending feedback to the iris to constrict or dilate the pupil accordingly.   2) There is some problem to the nerve / brain 'telling' the iris to dilate or constrict the pupil, 3) or some damage to the ability of the iris to constrict.  4) You could be mistaken as to what you are looking at.  Just for completeness.  Eg if there is a cancer or badly formed pupil distorting the picture.   These things don't tell you causes, but rather explain mechanisms for what you may be seeing.

My apologies, that should obviously read 'if one PUPIL is bigger than the other.'

Because there are no many potential causes, it is difficult to promise you that this case is urgent.  However, a lot of the causes certainly could be, especially if the signs have developed quickly, which they seem to have done.

Therefore, please do speak to your veterinary team right away for the situation to be triaged as they might want to see your cat right away.  If you have a phone or similar full of photographs, particularly taken day / hours apart, take it with you when you see your vet - it will help to guage the progression of the problem.

Triage will often be carried out over the phone at first.