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What is Iritis? or
Anterior uveitis?efinition
Anterior Uveitis is the most common form
of uveitis, accounting for 75% of cases of Uveitis. It will often be
referred to as Iritis as the iris is the part of the uvea that is
usually inflammed. (the ciliary body may also be involved and this
would be termed iridocyclitis).
The iris is the coloured part of the eye which has a hole (the pupil)
in the middle of it. The iris is a muscle which dilates the
pupil,letting more light into the eye, or constricts it cutting down
the amount of light that enters the eye. Behind this is another
circular structure, the ciliary body. This produces the clear fluid
which fills the eye, passing through the pupil and draining away near
the edge of the iris. It also changes the eye’s focus via muscles
attached to the lens.
Anterior Uveitis occurs when the iris and \ or the ciliary body become
inflamed.
SYMPTOMS
-
Redness of the eye.
-
Pain
-
Photophobia (a need to avoid bright light)
- the iris muscles shrink the pupil size in bright light and this
movement in the inflamed iris causes pain.
-
Blurring of vision (if the inflammation is
severe).
N.B. Some or all of these symptoms may not
be present at all.
Fortunately, for most people, Anterior Uveitis is the most readily
treated of the uveitis conditions. It usually responds to treatment
quickly but it often recurs regularly. It will usually not lead to any
significant vision loss. However the condition must be carefully
monitored because some people may:
Suffer from complications
Have other medical conditions known to be well associated with
Anterior Uveitis.
COMPLICATIONS
Raised Eye Pressure
This occurs when the pressure of the fluid inside the eye is
increased. This can threaten the eyesight and may cause glaucoma, but
it can be monitored with a simple test and be treated with tablets or
drops. In Ant. Uveitis the pressure can be raised due to the inflamed
iris "sticking" to the lens (adhesions or synechiae) preventing the
fluid from passing through the pupil. It can also be due to the
inflammation of the area where the fluid drains out of the the area
where the fluid drains out of the eye. The other possible cause of a
raised pressure is as a side-effect of the steroids used in the
treatment.
Cataracts
These are more likely to occur due to the Uveitis and also long term
use of steroids.
Macular Oedema
The Macula is the tiny part of the retina that is responsible for our
central, or detailed part of our vision. Fluid (oedema) in this area
may cause problems with central vision. This can mean difficulty
making out people’s faces, reading, driving and finding that straight
lines appear distorted.
It is wise to be aware of these complications but they are not usually
present in most cases.
CAUSES
After a thorough medical history, eye and general examination is
complete; no cause is found or known for approx 75% of Anterior
Uveitis cases. This is called Idiopathic Anterior Uveitis.
Other forms of Ant. Uveitis are then grouped according to the
different medical conditions that are found to exist. Associated
medical conditions include Ankylosing Spondylitis, Juvenile rheumatoid
arthritis or (Juvenile chronic arthritis) and inflammatory bowel
disease. There are several more and more information about any
specific condition can be provided on request.
Treatment
1. To relieve pain and photophobia
Mydriatic eye drops, such as atropine or cyclopentolate are used.
These may be short or long acting and may be used for variable lengths
of time depending on individual cases. The way a mydriatic works is
that it "paralyses" the muscles of the iris and ciliary body. (It is
the movement of these inflammed muscles that causes the pain.) When
these drops have taken their effect the pupils will be dilated.
These mydriatics are also useful because they help prevent the
complication mentioned earlier where the iris "sticks" to the lens.
2. To treat the inflammation
Steroids are used in the form of eye drops. Occasionally, but not
often, injections of steroids are used around the eye. These may be
uncomfortable but are straightforward and are done at the Eye
Outpatient Clinics.
Even more rarely steroid tablets are used.
The type of steroid treatment and the length it is used will, again
vary a lot for different people. Side effects of steroid drops can
include raised eye pressure which may cause glaucoma and cataracts.
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 urea becomes inflammed then 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:
1. 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.
2. 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.
3. Next there are a large number of medical conditions where Uveitis
is a feature amongst the other symptoms of the disease. e.g. Behcet’s
Disease, Sarcoidosis and Toxoplasmosis, to name just three of them.
4.There are many different types of causes of Uveitis [see under
Causes].
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 visual impairment 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 your own particular case. It is,
of course, very important, for both patients and doctors, to establish
the exact type of Uveitis that exists, as far as it is possible, early
on.
What causes Uveitis?
As just suggested, there are a number of
quite different types of causes 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 recognises a part of our own body as foreign (albeit a small
part, like one type of protein).
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. 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 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. Having said that, iritis is
something that needs quite close monitoring because complications such
as raised eye pressure and cataracts can occur.
See also: What is Iritis or Anterior Uveitis?
Intermediate Uveitis
This 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 is 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 the retina.
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, then 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, e.g. 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.
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 varied nature of uveitis, the
treatment of it may differ from case to case quite considerably.
Corticosteroids are often the mainstay of treatment but now are,
importantly, being joined by some other newer drugs, usually used
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 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 can not be
controlled.
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