People commonly get skin rashes for unknown reasons. Likewise inflammation may occur inside the eye. The the uvea becomes inflamed, then the patient has uveitis. (Much like when the skin is inflamed, the patient has dermatitis, or when the appendix becomes inflamed there is appendicitis.)
The following has been modified from the websites of the American Uveitis Society and the Mayo Clinic.
WHAT IS THE UVEA?: The uvea is the pigmented (coloured), middle layer of the eye located between the sclera (white of the eye) and retina. The front (anterior) part of the uvea is visible in the front of the eye as the iris. The uvea also extends all the way to the back of the eye as the ciliary body and choroid. When inflammation involves the uvea, the term “uveitis” is used.
WHAT IS THE DIFFERENCE BETWEEN INFLAMMATION AND INFECTION? Inflammation is a process mounted by the body in response to a triggering event which is interpreted to be harmful to the body. This inflammatory response uses white blood cells (leukocytes) as well as other substances in the body to attempt to control the harmful process. As an example, when a splinter lodges in someone’s finger, an inflammatory response occurs. This is why the area around the splinter becomes swollen, sore, red, and warm. The inflammatory response not only helps to control the harmful process, but to repair any damage which occurred, by scar tissue formation. An Infection is an invasion of the body by germs, which may be bacteria, viruses, parasites, fungi, or other organisms. An infection causes an inflammatory response, but the trigger is different than in noninfectious disease, in this case being a germ. Inflammatory diseases can occur without being caused by an infection, and in fact this is the typical situation in Uveitis, most of which are currently considered to be autoimmune in nature. Therefore inflammation may occur without infection, but rarely does infection occur without inflammation. Uveitis is an inflammatory disease that can be caused by infectious OR noninfectious processes.
WHAT CAUSES UVEITIS? Uveitis may be caused by infectious and noninfectious processes. There are hundreds of possible causes of uveitis, and sometimes the ophthalmologist has to ask personal questions to try and diagnose the problem (see below).
The specific cause of uveitis often can’t be determined. However, in some people, uveitis is associated with:
- Autoimmune disorders, such as rheumatoid arthritis or ankylosing spondylitis
- Inflammatory disorders, such as Crohn’s disease or ulcerative colitis
- Infections such as cat-scratch disease, herpes, syphilis, toxoplasmosis, tuberculosis or West Nile virus
- Eye injury
- Certain cancers, such as lymphoma, that have an indirect effect on the eye
Blood tests and X-rays can sometimes help delineate the cause of iritis. Many cases of iritis do not have a definitive diagnosis though.
WHAT PROBLEMS CAN UVEITIS CAUSE?
Uveitis can cause the following problems:
- Abnormally high pressure inside the eye (glaucoma)
- Damage to the optic nerve
- Clouding of the lens (cataract) or cornea
- Retinal problems, such as fluid within the retina or retinal detachment
- Vision loss
Unfortunately uveitis can be chronic, or can recur.
HOW MANY PEOPLE GET UVEITIS? It is currently estimated that each year in the United States, approximately 15 new cases of uveitis will develop out of every 100,000 people, for a total of 38,000 people per year. One can extrapolate this to 4,000 cases of uveitis in Canada per year.
IS UVEITIS CONTAGIOUS? In general, you cannot “catch” uveitis from someone else, no matter how close your contact with that person. Uveitis is an inflammatory disease within the eye. However, certain infections which can cause uveitis are transmissible from person to person, such as Tuberculosis and Syphilis.
HOW IS UVEITIS TREATED? The treatment of uveitis depends on each patient’s unique situation, so there is no one complete answer to this question. Antibiotics, or antivirals may be required if the patient has an infection. Steroids are usually the first-line treatment given either by drop, injection around the eye, pill form, or through the vein in severe cases. When corticosteroids are ineffective; a dose too high to be safe is required; or long-term medication usage is required; then steroid-sparing therapy may be used. Uveitis patients may need to use additional dilating (red top) drops to prevent their iris from becoming “sticky”, glaucoma drops, and occasionally surgery is requried, such as cataract extraction, glaucoma surgery and vitrectomy.
QUESTIONS you might be asked to help sort out the cause of your uveitis:
- When did you first develop vision problems, red eye eye discomfort, floaters, increased light senstivity?
- What, if anything, appears to worsen your symptoms?
- Have you had any eye trauma or eye surgery in the past?
- Do you have any other medical problems?
- Do you have arthritis or lupus?
- Do you have back problems?
- Do you have any gastrointestinal problems e.g. Crohns or ulcerative colitis?
- Do you have any kidney problems?
- Have you had any recent skin rashes or psoriasis?
- Have you had any ulcerated sores in your mouth or on your genitalia? Does it burn when you urinate? Have you ever had a sexually transmitted disease?
- Have you had a recent upper respiratory infection or cold symptoms?
- Have you travelled to a foreign country, or had tuberculosis?
- Have you ever had cancer of any type?
- Do you have sarcoidosis?
- Do you eat or taste rare meat?
- What pets or animals do you have at home?