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What is Uveitis?
Uveitis is inflammation of a part of the eye called the uvea. The uvea (pronounced “You-Vay-Uh”) is a layer of the eye made up of three parts. These are the iris, the ciliary body, and the choroid.
Uveitis can occur in one eye or both eyes. Inflammation of the uvea may involve other parts of the eye, or any part of the eye, including the cornea (the clear, curved front of the eye), the sclera (the white outer part of the eye), the vitreous body, the retina and the optic nerve.
The iris is the colored part of the front of the eye. It controls light that enters the eye by controlling the size of the eye’s opening (the pupil).
The ciliary body is a group of muscles and blood vessels that changes the shape of the lens so the eye can focus. It also makes a fluid called aqueous humor. Aqueous humor is a clear, watery fluid that fills and circulates through parts of the front of the eye.
The choroid is a middle layer of the eye. It holds blood vessels that feed other parts of the eye, especially the retina. The retina is the inner layer of the eye. It contains nerve cells that sense color and light and send image information to the brain.
What is Inflammation?
“Inflammation” is the body’s response to injury. This injury, or trauma, may be caused by a blow or wound, eye surgery, a disease such as a virus, bacteria infection, or a parasite. It may be caused by problems with the body’s immune system or genetic disease. For many people with uveitis, the exact cause of their inflammation is unknown.
Inflammation is the body’s attempt to rid itself of the cause of trauma, and to heal any damage caused by it. Often, however, the inflammation itself can damage the body. In the case of uveitis, the inflammation can lead to problems that cause loss of vision, or even blindness.
What are the Types of Uveitis?
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.
Who is at Risk for Uveitis?
Uveitis can affect anyone at any age, but it is most commonly seen in the forth decade of life. It affects children, working adults, and senior citizens. There is a higher prevalence in women. It is a leading cause of blindness in the United States and in the world. Working age Americans are most likely to get uveitis. As we age, however, we are more likely to get uveitis in both eyes and panuveitis (uveitis that affects all of the uvea).