Uveitis () is inflammation of the uvea, the pigmented layer of the eye between the inner retina and the outer fibrous layer composed of the sclera and cornea. The uvea consists of the middle layer of pigmented vascular structures of the eye and includes the iris, ciliary body, and choroid. Uveitis is described anatomically, by the part of the eye affected, as anterior, intermediate or posterior, or panuveitic if all parts are involved. Anterior uveitis (iridocyclytis) is the most common, with the incidence of uveitis overall affecting approximately 1:4500, most commonly those between the ages of 20-60. Symptoms include eye pain, eye redness, floaters and blurred vision, and ophthalmic examination may show dilated ciliary blood vessels and the presence of cells in the anterior chamber. Uveitis may arise spontaneously, have a genetic component, or be associated with an autoimmune disease or infection. While the eye is a relatively protected environment, its immune mechanisms may be overcome resulting in inflammation and tissue destruction associated with T-cell activation. Uveitis is an ophthalmic emergency that requires urgent control of the inflammation to prevent vision loss. Treatment typically involves the use of topical eye drop steroids, intravitreal injection, newer biologics, and treating any underlying disease. While initial treatment is usually successful, complications include other ocular disorders, such as uveitic glaucoma, retinal detachment, optic nerve damage, cataracts, and in some cases, a permanent loss of vision. In the United States uveitis accounts for about 10%-20% of cases of blindness. Classification Uveitis is classified anatomically into anterior, intermediate, posterior, and panuveitic forms—based on the part of the eye primarily affected. Prior to the twentieth century, uveitis was typically referred to in English as "ophthalmia." Anterior uveitis includes iridocyclitis and iritis. Iritis is the inflammation of the anterior chamber and iris. Iridocyclitis is inflammation of the iris and ciliary body with inflammation predominantly confined to the ciliary body. Between 66% and 90% of uveitis cases are anterior in location (iritis). This condition can occur as a single episode and subside with proper treatment or may take on a recurrent or chronic nature. Intermediate uveitis, also known as pars planitis, consists of vitritis—which is inflammation of cells in the vitreous cavity, sometimes with snowbanking, or deposition of inflammatory material on the pars plana. There are also "snowballs," which are inflammatory cells in the vitreous. Posterior uveitis or chorioretinitis is the inflammation of the retina and choroid. Panuveitis is