Infection of the uvea; I rely heavily on my ophthalmologist to tell me exactly where it is and draw me a picture.
AIDS, IVDA, life.
Syphilis, Tuberculosis, Toxoplasmosis, CMV (HIV), Herpes simplex and Varicella-zoster virus (Acute Retinal Necrosis), Candida, Toxocara, Leptospirosis, Lyme Borrelia, Brucellosis (PubMed), Whipple's disease, and Bartonella (cat-scratch disease).
Sarcoid is the (perhaps) important non-infectious disease.
Depends on the organism.