A rare condition in which all or part of the uvea (middle layer of the wall of the eye) becomes inflamed. The uvea includes the choroid, the ciliary body, and the iris. Uveitis may also affect the lens, retina, optic nerve, and vitreous humor (the gel-like fluid inside the eye). It may be caused by an injury, infection, a tumor in the eye, or an autoimmune or inflammatory condition. One or both eyes may be affected. The signs and symptoms may occur suddenly and get worse quickly. They include redness and pain in the eye, sensitivity to light, blurred vision, dark floating spots in the vision, and vision loss. If not treated, uveitis can lead to tissue scarring and blindness.