When doctors diagnose and treat uveitis, they may group it in different ways. Uveitis is often grouped by the part of the uvea it affects.
Anterior uveitis affects the front of the eye. It is often called iritis because it mainly affects the area around the eye’s iris. Anterior uveitis is the most common kind of uveitis in children and adults making up 40-70% of all uveitis. It is usually acute (i.e. comes on suddenly and lasts for less than six weeks) and is associated with pain, light sensitivity and redness. Although it can be caused by a number of diseases which affect the body, such as Ankylosing Spondylitis or Juvenile Rheumatoid Arthritis, most of the cases are of unknown origin.
Intermediate uveitis is inflammation of the ciliary body, the front end of the retina, and the vitreous. The vitreous body is a clear gel-like substance that fills the inside of the eyeball between the lens and the retina. Intermediate uveitis is the least common type of uveitis, making up only 7-15% of cases. It is also known as cyclitis, pars planitis or vitritis. In most of the cases, the cause is unknown. Symptoms include floaters and blurry vision. People with intermediate uveitis are more likely to have chronic inflammation. Chronic uveitis is defined as uveitis lasting longer than six weeks.
Posterior uveitis is inflammation of the choroid, retina and optic nerve. The optic nerve is the path that carries images from the retina to the brain. It can be seen in 15 to 22% of uveitis types. Generally it is chronic (long standing – can last weeks to months to years), recurrent (in which a patient has multiple flare-ups between periods of a quiet eye) and affects both eyes. The underlying cause is often a result of an abnormal immune disease. Infections caused by the organism toxoplasmosis are the most common cause of posterior uveitis.
Sometimes inflammation can affect the entire uvea. This inflammation is sometimes called panuveitis. People with panuveitis may be more likely to experience vision loss from the condition. Symptoms include floaters, blurred or loss of vision.