What is uveitis?
Uveitis is a general term that refers to inflammation (swelling, irritation) of the middle layer of the eye (the uvea). In common usage, it refers to all inflammatory processes inside the eye.
The eye is shaped like a tennis ball, with three different layers surrounding a gel-filled cavity (the vitreous). The innermost layer is the retina. The middle layer, between the sclera and the retina, is called the uvea. The outermost layer is the sclera, the strong white part of the eye.
The uvea includes the iris (colored part of the eye), choroid (a thin membrane containing many blood vessels) and ciliary body (the part of the eye that joins these together). The uvea is very important because its many veins and arteries transport blood to the parts of the eye that are necessary for vision.
What are the symptoms of uveitis?
Symptoms of uveitis may include:
- Eye redness
- Blurred vision
- Pain in the eye
- Light sensitivity
Uveitis can permanently damage your eyesight and even cause blindness. Uveitis may develop rapidly. It is very important that you see your ophthalmologist for a complete eye examination if you develop these symptoms, especially if a painful, red eye does not clear up quickly. If it is not treated, uveitis can damage your vision permanently.
What causes uveitis?
Uveitis has many potential causes, including infections by virus, fungus, bacteria, or parasites. It may be associated with systemic inflammatory diseases (those that affect the whole body), or can develop after an injury to the eye. In a large number of cases, the cause of uveitis is not known.
There are several types of uveitis, depending on which part of the eye is inflamed:
- Iritis, the most common form of uveitis, affects the iris. This condition is often associated with autoimmune disorders (in which the body attacks itself) such as arthritis. Iritis may develop suddenly and may last up to eight weeks, even with treatment.
- Cyclitis is inflammation of the middle portion of the eye and may affect the muscle that focuses the lens. This also may develop suddenly and can last several months.
- Retinitis affects the back of the eye. It may develop quickly, making it difficult to treat. Retinitis may be caused by viruses such as herpes zoster or herpes simplex, bacterial infections such as syphilis, or parasitic infections such as toxoplasmosis or autoimmune diseases.
- Choroiditis, or inflammation of the layer beneath the retina, may also be caused by an infection such as tuberculosis, or may be caused by autoimmune diseases.
- Panuveitis is an inflammation of the entire interior of the eye.
- Scleritis is inflammation of the sclera (the white part of the eye).