If we think of the eye as a hollow, fluid-filled, three-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 and when any part of the uvea becomes inflamed it is called Uveitis.
A big problem, 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 and so a variety of other problems can be present to complicate the picture.
- There are a large number of medical conditions where Uveitis is a feature amongst the other symptoms of the disease, eg Behcet's Disease, Sarcoidosis and Toxoplasmosis.
- There are many different causes of Uveitis (see Causes of Uveitis below).
The term intraocular inflammation is often used to cover the spectrum of uveitis conditions. As there is this 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 there is potential for confusion, as long as it is remembered that Uveitis is actually a number of different conditions, then it is possible to find out about your own particular case. It is very important for both patients and doctors to establish the exact type of Uveitis that exists early on.
Causes of Uveitis
There are a number of quite different types of causes of Uveitis. It may result from an infection such as a virus (eg herpes) or a fungus (eg 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 recognises a part of our own body as foreign (albeit a small part, like one type of protein).
Also, trauma to the eye, or even the other eye 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. This group is described as "idiopathic".
Another important way of classifying the different types of Uveitis is by describing the part of the eye that is affected.
Tests and examinations
Because of the quite diverse types of causes of Uveitis and also due to the many other medical conditions associated with it, you can expect to receive a number of tests and thorough questioning. All these are straightforward and painless enough but may seem far removed from your eye problem, eg back X-rays, but as said before, it is important to establish the correct type of Uveitis so that the best treatment can be planned.
In the long term
This, once again, varies considerably, but there is a growing confidence, especially with the newer drug treatments, that the eyesight can be stabilised over the long term. Uveitis as a disease should be regarded as incurable in the sense that it will never completely go away, but that is not to say that it cannot be controlled.