Iritis

Iritis is inflammation of the iris (the colored part of the eye).

White blood cells can be seen in the front part of the eye (anterior chamber) by an ophthalmologist using a microscope known as a slit lamp. 

The common symptoms of iritis are:

• eye pain (usually felt as a dull ache in and around the eye),
• redness of your eye,
• photophobia (which means you do not like bright light).

You may develop blurred vision or even some visual loss (usually temporary). You may develop headaches and notice that the pupil of the affected eye may change shape slightly.

The pupil may not react to light (normally becomes smaller) or it may lose its smooth round shape. Your eye may become watery.

The symptoms tend to develop over a few hours or days. 

The known causes and associations of iritis include the following:

Autoimmune and inflammatory diseases

Our immune system normally makes small proteins (antibodies) to attack bacteria, viruses, and other 'germs'. In people with autoimmune diseases, their immune system makes antibodies against the tissues of their body, causing damage and inflammation.

It is not clear why this happens. Some people have a tendency to develop autoimmune diseases. In such people, something might trigger the immune system to attack the body's own tissues. The 'trigger' is not known.

Autoimmune diseases that are associated with uveitis include rheumatoid arthritis and Behçet's disease. It is also thought that 'idiopathic' uveitis may actually have an autoimmune basis.

People with some other inflammatory diseases are also more prone to uveitis. Such diseases include

• ankylosing spondylitis,
• reactive arthritis (including Reiter's syndrome),
• sarcoidosis,
• psoriasis and inflammatory bowel disease (including Crohn's disease)
• ulcerative colitis.

Infection

Various types of infections caused by germs (bacterial, fungal and viral) can cause inflammation of your eye and iritis. Infections include:

• herpes simplex,
• herpes zoster,
• toxoplasmosis,
• cytomegalovirus,
• syphilis,
• gonorrhoea,
• tuberculosis
• Lyme disease.

Infections are a rare cause of uveitis.

Injury to the eye

Iritis can occur after injury to your eye.

Iatrogenic causes

'Iatrogenic' refers either to an unforeseen or to an inevitable side-effect from a medical treatment. In this case, iatrogenic iritis is usually iritis that has resulted from eye surgery.

Cancers

Some cancers are associated with inflammation and iritis. These include leukaemia, lymphoma and malignant melanoma.

The tests ordered when a child is diagnosed with iritis depend on clinical symptoms and signs. Testing is often not done for a first isolated case of iritis in one eye.

When iritis is recurrent or affecting both eyes, testing is usually recommended.

Testing may include

• blood tests for antinuclear antibodies (ANA),
• rheumatoid factor (RF),
• HLA-B27 haplotype,
• sedimentation rate,
• certain infections.

Imaging may include

• CT scan of the chest,
• gallium scan
• sacroiliac x rays.

In the case of suspected sarcoidosis, a tissue biopsy may be performed. There are many other tests that may be ordered to help identify a possible cause for the iritis. 

Treatment for iritis aims to help relieve pain and discomfort in the eye(s), treat any underlying cause (if possible), and to reduce the inflammation.

This may prevent permanent loss of vision or other complications. Treatment usually includes the following:

Steroid eye drops

Steroid eye drops are used to reduce the inflammation iniritis. Steroid drops are usually the main treatment for iritis and may be the only treatment for mild attacks. Examples of steroid drops include prednisolone and dexamethasone eye drops.

Although steroid eye drops usually work well, in some cases side-effects occur, which are sometimes serious. Therefore, steroid eye drops are usually only prescribed by an eye specialist (an ophthalmologist) who can monitor the situation.

Possible side-effects that sometimes occur include ulcers on the cornea of the eye, which can be very painful and affect your vision. If steroid eye drops are used for long periods of time, they can lead to clouding of your lenses (cataracts) or raised pressure in your eye (glaucoma).

Treatment to relieve pain and discomfort

Cycloplegic eye drops

These are special eye drops that can be used to relieve pain by causing the pupil in your eye to widen (dilate). The drops cause your pupil to dilate by relaxing the muscle in the ciliary body. As a result, pain reduces and the inflamed iris is able to rest and recover.

Examples include atropine and cyclopentolate eye drops. However, they can have some side-effects. They can make your pupil appear large; can cause temporary blurred vision and also difficulty with focusing. When the effect of the drops wears off, these side-effects will disappear. If these drops are not used, the inflammation in the iris may cause it to become 'stuck' to the lens causing permanent scarring.

Dark glasses

If your symptoms include sensitivity to bright light (photophobia), wearing dark glasses may be helpful.

Painkillers

Painkillers, such as paracetamol, may also help.

Steroids by mouth or injection

In severe iritis, steroids are sometimes given by injection into or around your eye. They can also be given by mouth. Again, these can have side-effects if used in the long term. The main side-effects from steroids taken by mouth occur when they are used for more than a few weeks. These include thinning of the bones (osteoporosis), thinning of the skin, weight gain, muscle wasting and an increased risk of serious infection.

Immunosuppressive drugs

If steroid treatment is needed in the longer term to treat iritis, a second drug known as an immunosuppressive drug may be used. This can help to reduce the amount of steroids needed and/or help to control the iritis if steroids are not working.

Treatment of underlying conditions and causes

Any underlying cause of your iritis also needs to be treated (if possible). This means treating any underlying infection, inflammatory disease or autoimmune disease.

Surgery

Occasionally, surgery is needed to treat iritis - usually persistent (chronic) iritis. Surgery is used in addition to the other treatments mentioned above. Iritis cannot be treated only by surgery.

For example, if someone has persistent floaters that are affecting their ability to see the vitreous humour in the eye can be removed. Floaters tend to develop because of inflammation causing damage to the vitreous humour.
Surgery may also be used to treat the complication of cataracts that can occur.

Newer treatments

There are a number of new treatments for uveitis that are currently being investigated. These include medicines called TNF-alpha blockers, such as etanercept and infliximab.

There are several complications associated with iritis.

If iritis is not treated quickly, it can have serious effects and can lead to permanent loss of vision. It may also lead to complications that can affect your eyesight.

If complications are not detected early, they can sometimes have a more harmful (detrimental) effect on your eyesight than the underlying iritis.

The complications of iritis may be caused by the effects of the inflammation inside the eye.

However, some of them may also be caused by the steroid treatment used to control the inflammation. Despite this, as a general rule, using enough steroids to control the iritis will generally give a better outcome than using too few steroids and not controlling the inflammation.

Complications that can sometimes occur with iritis include:

Formation of synechiae

Synechiae are the name given to the 'bands' of tissue that can form between the iris and the lens due to inflammation if iritis is not treated promptly.

Eye drops which cause the pupils to widen (dilate) can sometimes help to prevent synechiae.

Glaucoma

The pressure in your eye can increase suddenly and may cause glaucoma. The inflammation in your eye may cause the pressure in your eye to increase.

Using steroids can also cause a sudden increase in pressure in your eye, especially if you already have glaucoma. If glaucoma is not treated, it can lead to loss of vision.

Glaucoma can also be caused by repeated attacks of iritis or a side-effect of long-term steroid treatment.

Macular oedema

This is the term for fluid building up in the back of your eye around your macula on your retina. It may cause permanent visual loss.

Cataract formation

The inflammation can cause changes in the lens of your eye, and clouding of the lens (cataract formation).

Cataracts may also be caused by long-term steroid treatment. If a cataract worsens and is not treated, it can lead to visual loss.

Retinal detachment

The inflammation can cause 'pulling' on your retina so that it 'comes away' or is detached. This can cause you to experience flashing lights, floaters and problems with your vision.

If you suspect that you have a retinal detachment, contact your doctor immediately, as urgent surgery is often needed.