Uveitis is the swelling and irritation of the uvea, or the middle layer of the eye which provides most of the blood supply to the retina. It can be caused by autoimmune disorders like rheumatoid arthritis, infection, or exposure to toxins, but in many cases the cause is unknown. The most common form is anterior uveitis which involves inflammation in the front part of the eye. This is called iritis, as it involves the iris. Posterior uveitis affects the back part of the eye and involves the choroid which is a layer of blood vessels and connective tissue in the middle part of the eye. Individuals may develop this condition following a body-wide (systemic) infection or an autoimmune disease. Symptoms of uveitis can include blurred vision, dark or floating spots in the vision, eye pain, redness of the eye, and sensitivity to light.
Facts About Uveitis. National Eye Institute (May 22, 2018), https://nei.nih.gov/health/uveitis/uveitis