What is Uveitis?
Uveitis is a term that we use to mean inflammation within the eye. The uvea is a layer of tissue composed largely of blood vessels that support and nourish many important parts of the eye including the retina (the light sensing layer of tissue that lines the inside back part of the eye). The uvea also includes the iris, which is the tissue that gives the eye its distinctive color and functions to regulate the amount of light reaching the retina. Inflammation involving this tissue can damage those structures it supports, and therefore, lead to vision loss.
What are the symptoms of uveitis?
- Blurred vision is the most common symptom of inflammation within the eye. It may be due to swelling of the retina or to inflammatory cells floating inside the eye.
- Pain occurs when the iris becomes involved. The iris contains muscle fibers and, like an inflamed muscle elsewhere in the body, contraction of this muscle can be painful.
- Light Sensitivity. Light causes the iris muscle to contract, which is why we are often light sensitive when the eye is inflamed.
- Redness of the eye will also accompany acute uveitis.
What causes uveitis?
Because the uvea provides blood to the eye, it is often the pathway for inflammation from other parts of the body to gain access to the eye itself.
- Infection is one cause of uveitis and can arise from any bacteria or virus such as herpes (the cause of chicken pox and shingles). A fungus called histoplasmosis or even a parasite called toxoplasmosis can access the eye and cause damage from associated inflammation.
- Inflammation is not always from an infection. Arthritis is an example of inflammation within joints that is not infectious and can affect the eye as well. Certain cancers such as lymphoma or leukemia can also lead to uveitis. The abnormal cancer cells from the blood can collect and float inside the eye or deposit within the tissue.
- Finally, direct injury to the eye can illicit inflammation; however, in most cases of uveitis the actual cause of the inflammation is never known.
How is uveitis diagnosed?
The most important step in diagnosing uveitis is a careful examination of the eye coupled with a careful medical history. Because uveitis is often associated with diseases affecting other parts of the body, you need to be open with your physician about your overall health. Blood testing and even x-rays may be necessary to collect clues to the cause of inflammation in the eye. We will generally classify inflammation depending on the layer of the eye affected. The specific location of inflammation within the eye helps to determine the cause.
When the front part of the eye is the only part involved, we call it iritis. This is commonly associated with pain and light sensitivity. Intermediate uveitis involves the middle of the eye and is characterized predominantly by floaters and blurred vision. Posterior uveitis is inflammation of the retina itself or its underlying blood supply called the choroid.
How is uveitis treated?
It is important to treat uveitis quickly as it is a serious condition which can cause permanent damage to the eye. Treatment generally begins with medication. Corticosteroids are the mainstay of treatment and may be delivered as drops or as injections next to the eye or even into the eye. It may also be necessary to treat with oral or even intravenous medications to control the inflammation. Dilating drops can often alleviate the pain associated with acute iritis.
Surgery may be needed for both diagnosis and therapy. Samples of intraocular fluid can be taken and analyzed for bacteria or even cancer cells to guide treatment. Constant opacities within the eye can be removed to clear vision, and complications of uveitis such as glaucoma, cataract or retinal detachment may also be treated surgically.