Iritis (also known as Anterior Uveitis) refers to an inflammation of the iris, which is the coloured part of the eye surrounding the pupil.
There are three main types of iritis:
- 1. Acute iritis
- Sudden onset and tends to resolve within 6 weeks with appropriate treatment.
- 2. Chronic iritis
- The inflammation does not respond so well to treatment and becomes persistent, often lasting more than 3 months.
- 3. Recurrent iritis
- The disease settles down before frequently relapsing (flares up).
Symptoms of iritis
Often the first sign of a problem is discomfort and tenderness around the affected eye. This may rapidly worsen over 24-48hrs. The eye becomes red and very sensitive to light (photophobia). Vision may be blurred for distance or near. The pupil may be smaller in the inflamed eye and can even become irregular in shape.
Cause of iritis
Iritis is a relatively uncommon condition and, in the vast majority of cases, the cause is unknown. It is thought that iritis is a type of autoimmune reaction, with something triggering the patients own immune system to set up an inflammatory reaction in the iris.
Much less commonly the inflammation can involve the middle part of the eye (Intermediate Uveitis) or even the back of the eye (Posterior Uveitis). Patients who have bilateral iritis (both eyes affected), recurrent iritis or intermediate/posterior uveitis are more likely to have a systemic condition which is either associated with, or causing, the inflammation. It is generally in these cases that investigations may be requested to look for an underlying problem.
Some of the possible rare causes or diseases associated with uveitis include:
- 1. Back and joint problems
- 50% of people with iritis are positive for a blood test that looks for a protein found on cell surfaces called "HLA-B27". This protein tissue marker is also associated with a number of conditions which cause back or joint pain including ankylosing spondylitis, psoriatic arthropathy and Reiter's syndrome. In children iritis can occur in cases of juvenile chronic arthritis.
- 2. Skin diseases
- Iritis has an association with herpes zoster (shingles), psoriasis and a skin rash called erythema nodosum which can occur in conditions like Sarcoidosis.
- 3. Respiratory conditions
- Inflammatory diseases such as Sarcoidosis and Wegeners granulomatosis, infections like Tuberculosis and blood disorders such as Non-Hodgkins lymphoma.
- 4. Neurological disease
- Rare conditions including syphilis and multiple sclerosis.
- 5. Gastrointestinal conditions
- Approximately 5% of patients suffering from Ulcerative colitis may develop iritis and 2.5% of those with Crohn's disease.
Treatment and prognosis
The outlook for iritis (anterior uveitis) is generally good. The inflammation usually settles down fairly quickly with intensive topical steroids. Occasionally dilating drops are also prescribed to relieve symptoms and avoid the pupil sticking to the lens sitting just behind the iris. Problems such as cataracts and glaucoma can occur in cases resistant to treatment.
Intermediate and posterior uveitis tend to be more serious and carry a greater chance of affecting vision. These conditions often require specialist treatment depending on the cause.