Uveitis
Uveal tract is the vascular middle coat of the eye ball. Inflammation of the uveal tract is called uveitis. Uveitis, usually occurs if there is associated systemic disease in the patient either an autoimmune disease or an infectious disease.
What is Uveitis?
If we think of the eye as a hollow, fluid-filled, 3-layered ball then the outer layer is the sclera a tough coat, the innermost is the retina the thin light-gathering layer and the middle layer is the Uvea. The Uvea is made up of the iris, the ciliary body and the choroid (see diagram). When any part of the uvea becomes inflamed then it is called Uveitis. A big dilemma, when trying to understand Uveitis for patients and doctors alike is that there are many different types of Uveitis. This is because the Uvea is made up of different parts. So if the iris is affected the condition and its treatment could be totally different to when the choroid is affected. The inflammation in the Uvea very often affects other parts of the eye such as the retina so a variety of other problems can occur and complicate the picture. . Also there are a large number of medical conditions where Uveitis features amongst the symptoms of other diseases, for instance; Behcet's Disease, Sarcoidosis and Toxoplasmosis to name just three. So as can be seen there are many different types of causes of Uveitis. The term intraocular inflammation is often used to cover the spectrum of uveitis conditions. As there is a wide variety of different conditions and complications, it follows that there are numerous ways that it presents itself. The degree and type of sight loss and the type of treatment may vary considerably from patient to patient. Although the potential for confusion sounds high, as long as it is remembered that Uveitis is actually a number of different conditions then it is possible to find out about each individual case. It is of course very important for both patients and doctors to establish the exact type of Uveitis as far as possible and as early as possible
What causes Uveitis?
As mentioned, there are a number of very different types of Uveitis. It may result from an infection such as a virus (e.g. herpes) or a fungus (e.g. histoplasmosis). It may be due to a parasite such as toxoplasmosis. It may be related to Autoimmune Disease (with or without involvement of other parts of the body). This, essentially is when our immune system recognizes a part of our own body as foreign (albeit a small part like one type of protein). Trauma to the eye even if it was in the past can lead to Uveitis. In many cases the cause is said to be unknown. This may well mean that the Uveitis is of the autoimmune type. The word ‘idiopathic’ may often be used to describe this group. Another important way of classifying the different types of Uveitis is by describing the part of the eye that is affected
Very simply there may be:
- Anterior Uveitis : This type affects the front of the eye, normally the iris (iritis) or the ciliary body (iridocyclitis). Iritis, strictly speaking is an older term for Anterior Uveitis but is still used frequently. Iritis is by far the most common type of Uveitis and also the most readily treated. Iritis is something that needs close monitoring because complications such as raised eye pressure and cataracts can occur.
- Intermediate Uveitis : This type affects the area just behind the ciliary body (pars plana) and also the most forward edge of the retina (see the diagram above). This is the next most common type of Uveitis.
- Posterior Uveitis : This type occurs when the inflammation affects the part of the Uvea at the back of the eye, the choroid. Often the retina is affected much more in this group.The choroid is basically a layer rich in small blood vessels which supplies blood to the retina
Tests and Investigations
When you visit an ophthalmologist, he or she will likely conduct a complete eye exam and gather a thorough health history.
- Blood tests
- Analysis of fluid from the eye
- Photography to evaluate the retinal blood flow (angiography)
- Photography to measure the thickness of the retinal tissue and to determine the presence or absence of fluid in or under the retina.
If the ophthalmologist thinks an underlying condition may be the cause of your uveitis, you may be referred to another doctor for a general medical examination and laboratory tests. Sometimes, it's difficult to find a specific cause for uveitis. However, your doctor will try to determine whether your uveitis is caused by an infection or another condition.
How is Uveitis treated?
The treatment of Uveitis aims to achieve the following:
- Relief of pain and discomfort (where present).
- To prevent sight loss due to the disease or its complications.
- To treat the cause of the disease where possible.
Like the diverse nature of uveitis, the treatment may differ from case to case quite considerably. Corticosteroids are often the mainstay of treatment but newer drugs are also being administered usually along with the steroids. Various eye-drops are used particularly to treat anterior uveitis.
What will happen to my eyes (prognosis)?
This, once again, varies considerably but there is a growing confidence especially with newer drug treatments that eyesight can be stabilized over the long term. Uveitis as a disease should be regarded as incurable in the sense that it will never completely go away but it can definitely be controlled.
