Anna Brouwer

11 General introduction, aims and scope 1 Causes of uveitis and associations with systemic diseases The term ‘uveitis’ comprises about 30 disease entities. Each of these individual diagnoses have certain typical characteristics, but there are also overlapping aspects. This makes it sometimes quite difficult to distinguish the different uveitis diagnoses from one-another. Uveitis may be caused by infectious agents, which may be identified by serology, or analyzing ocular fluids, or both. 2–4 However, many forms of uveitis are non-infectious. These non-infectious cases are often assumed to be auto-immune. However, in only about 5% of non-infectious uveitis cases, specific auto-antibodies can be found. 5 Many forms of uveitis have an association with systemic diseases including sarcoidosis, Bechterew, psoriasis, Behçet’s disease, multiple sclerosis (MS) and juvenile idiopathic arthritis (JIA). 6–11 Sometimes the systemic disease is present prior to the uveitis, but in other cases the uveitis may be the first sign of the underlying systemic disease. Uveitis also has several associations with certain human leukocyte antigen (HLA) types, including HLA-A29 (birdshot uveitis), 12,13 HLA-B27 (HLA-B27 associated Figure 1: Illustration of the anatomy of the eye and it’s relation to the different anatomical localizations of uveitis. Illustration recreated from: https://vsp.postclickmarketing.com/EyeAnatomyQuiz/eye-anatomy- review-dynamic-200WM-3388L1.html Abbreviations: AU = anterior uveitis, UI = intermediate uveitis, PU = posterior uveitis, PAN = panuveitis. Ciliary body Iris Lens Anterior chamber Cornea Retina Choroid Sclera Macula Optic nerve Pars plana Pupil Vitreous cavity AU IU PU PAN