Various diseases can be diagnosed by testing for biomarkers, a particular substance in the blood or tissue (e.g. troponin to determine whether someone has had a recent heart attack). So far there are no specific biomarkers for determining whether a patient has non-infectious uveitis. Using a mouse model of autoimmune uveitis, Mattapallil et al. found T-cells activated against a particular protein in the retina (retinal arrestin). This provides support for the theory that autoimmune uveitis is caused by the body attacking the retina and may lead the way to developing a blood test for diagnosing this disease.

Uveitis-Associated Epitopes of Retinal Antigens Are Pathogenic in the Humanized Mouse Model of Uveitis and Identify Autoaggressive T Cells.  (Journal of immunology (Baltimore, Md. : 1950). 2011 Jul 15;PMID: 21765017)

URL – http://www.ncbi.nlm.nih.gov/pubmed/21765017?dopt=Citation