Most are idiopathic
Juvenile Idiopathic Arthritis common
Infections
Lyme disease (antibody test)
toxocariasis (antibody test)
syphilis (antibody test)
HTLV-1 (antibody test)
Bartonellosis (antibody test)
Multiple sclerosis (MRI brain, HLA-DR2 and HLA-DR15)
Sarcoidosis (ACE may be elevated normally, Chest Xray)
Necrotizing systemic vasculitis
Collagen vascular diseases (HLA-B27)
Endophthalmitis- suspect in the setting of recent surgery or intraocular injection, immunocompromised or parenteral nutrition or central line
Intraocular lymphoma. (CBC with differential)