What are some diseases of the uvea of the eye?

Many. The uvea is the pigmented layer of the eye behind the iris and behind the retina. It is subject to inflammation, usually non-infectious termed uveitis (or iritis if only in the front). Sometimes this can be associated with systemic diseases like arthritis. The uvea can be traumatized and infected. There are some inherited diseases that cause uveal problems and melanoma can arise in the uvea.