What is uveitis?
Uveitis refers to inflammation of the middle layer of the eye
(the uvea), but 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 innermost layer is the retina, which is
like the film in a camera. The middle layer, between the sclera and the retina,
is called the uvea. The outermost layer is the sclera, the strong white wall 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 critical for vision.
What are the symptoms of uveitis?
Symptoms of uveitis may include eye redness, blurred vision,
pain, or light sensitivity. 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. Left
untreated, uveitis may permanently damage your vision.
What causes uveitis?
Uveitis has many potential causes, including viral, fungal,
bacterial, or parasitic infections. It may be associated with systemic diseases
or develop following an injury to the eye.
There are several types of uveitis categorized according to the
location of inflammation:
- Iritis, the most common form of uveitis, affects the iris. This
condition is often associated with autoimmune disorders 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
last several months.
- Retinitis affects the back of the eye. It may be rapidly
progressive, 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 inflections 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 be due to autoimmune
diseases.
- Panuveitis refers to inflammation involving the entire interior of
the eye.
Uveitis also may be caused by injury to the eye. In a large number of cases, the cause of uveitis is not known.