Sudden eye problem, help?

My mother adopted two of my foster kittens, they're now a year old. She messaged me today saying the one had a glazed over eye. I work at an SPCA and thought I had seen it all but I have never seen something like this. Her eye is a completely different color and it seems like the iris itself is swollen inside the eye. No discharge or third eyelid present. My mother won't take her to the vet or listen to me (I honestly shouldn't have allowed her to adopt them because her mental state is deteriorating). I most likely will take her to work with me but I wanted to see if anyone here has ever had this happen before.

That appears to be uveitis.  Uveitis is inflammation of the uveal tract, which is the pigmented, vascular part of the eye. Uveitis in cats can be caused by serious or life-threatening generalized disease in the cat’s body. Therefore, feline uveitis is an important disease to diagnose and treat correctly, to decrease the chances of the eye being blinded and possibly removed, or even of the cat dying from the disease that caused the uveitis.  The cat needs to see a vet right away.  Treatment may be as simple as eye drops twice a day, or the uveitis may indicate a more serious disease condition, but your mother's refusal to take the cat to a vet is unacceptable, so I guess you will have to do it.  I hope everything turns out  OK.  Do let us know how things are going after you see the vet.

My work vet confirmed that she has uveitis. She also has enlarged kidneys and a large mass in her abdomen. Vet thinks it's FIP
I'm a mess. She's only 11 months old and I raised her from the time she was 2 weeks old.
She's going to my regular vet on Thursday for further testing, right now she's only on eye meds.

Oh, dear.  It does sound like it could be FIP.  Is the other cat safe with your mother?  Do you plan to keep this one while she undergoes testing and treatment?

I didn't mention what nasty diseases uveitis accompanies, but FIP was at the top of my list.  As many people here know, FIP and I are too well acquainted, and already I was concerned about it here because of the history (being a foster kitten) and age (under 18 months) and then the appearance of uveitis.   The other thing to test her for, if she has not already been tested, is leukemia.  That would also be consistent with the enlarged kidneys and mass in the abdomen.  I'm really sorry it didn't turn out to be one of those "unknown cause" cases of uveitis where the eye drops fix it, or at least keep it under control.  I'm glad you were able to take her right away.  The eye drops will get rid of the pain and probably get rid of the uveitis itself, but unfortunately they can't treat the underlying condition that caused it. 

I had her combo tested and it came back negative. I'm taking her to my vet for a blood test tonight. She still has her other cat, he seems fine. I can't take him because I have 6 cats (3 older girls and my mom's cats triplet brothers) my oldest bas about everything wrong with her so I can't risk her getting sick. It would be possible for my mom to quarantine the sick one though, although her brother loves her.

FIP was one of those things I was hoping to never have to de with