Our hypothesis are that infections are a frequent cause of severe uveitis in Denmark, and that by using a broad diagnostic approach it is possible to identify new or less recognized infections agents that are associated with uveitis. By this study we want to describe the prevalence and distribution of infections among patients with severe uveitis. In this study are we only including patients with a severe form of uveitis from a referral-hospital setting, where vitrectomy is done for a diagnostic purpose.