An eye exam might find it, depending on the form:
https://www.mayoclinic.org/diseases-conditions/uveitis/symptoms-causes/syc-20378734
here are some blood tests..which cover a lot of things
https://www.reviewofoptometry.com/article/practical-pearls-for-managing-anterior-uveitis
in my recent hellish experience of dealing with medical profession somehow I doubt whatever eye doctor I choose would be willing to do those tests
Heck, I just had a idiot dermatologist tell me psoriasis has nothing to do with the immune system.
Sometimes it is cheaper to just order the tests you want from Directlabs.
But next time I get it I guess I will head to the eye doctor. One of those fast clinics just gave me some kind of antibiotic