Iritis is a type of uveitis — inflammation of the middle layer of the eye (uvea) — that affects your eye’s iris. The iris is the colored ring of tissue surrounding your pupil, which lies just behind the transparent cornea. Muscles controlling the iris change the size of the pupil to adjust to light conditions. Prolonged inflammation can lead to adhesions of the iris, causing your pupil to become smaller or irregularly shaped and predisposing you to glaucoma.
Iritis can be classified as acute when symptoms develop rapidly, or as chronic when symptoms develop gradually and tend to last over a period of weeks to months.
Known causes of iritis include:
Injury to the eye. Blunt force trauma, a penetrating injury or burn (chemical or thermal) to your eye can cause acute iritis.
Herpes infection. Infection with herpes zoster — commonly known as shingles — can cause iritis if you have a skin eruption on your face, especially your forehead or cheeks. Other infectious diseases, such as toxoplasmosis, histoplasmosis, tuberculosis and syphilis, may be linked to other types of uveitis.
Genetic predisposition. People with HLA-B27, a specific alteration of a gene that’s essential to immune system function, are more likely to develop certain autoimmune diseases, such as ankylosing spondylitis, Reiter’s syndrome, inflammatory bowel disease and psoriatic arthritis. Acute iritis may occur in these diseases.
Bechet’s disease. An uncommon cause of acute iritis in Western countries, this condition is also characterized by joint problems, mouth sores and genital lesions.
Juvenile rheumatoid arthritis. Chronic iritis can develop in children with juvenile rheumatoid arthritis. In cases where the condition is mild and affects only a few joints, iritis may be one of the first indications of the condition. Juvenile rheumatoid arthritis more commonly affects girls. Because the two conditions are so commonly associated with each other, doctors often routinely screen for iritis or other types of uveitis in kids with rheumatoid arthritis.
Posterior uveitis. Inflammation starting in the back part of your eye (posterior uveitis) can have a spillover effect on the parts of the uvea at the front of your eye.
Symptoms of iritis
Signs and symptoms of iritis may include:
- Eye redness, often seen as a blush pink color in the white of your eye (sclera) around the iris
- Discomfort or achiness in the affected eye
- Sensitivity to light (photophobia)
- Blurred vision
- Floating spots in the vision (eye floaters)
Iritis usually isn’t associated with eye discharge or increased tearing.
When symptoms of iritis develop suddenly, over a period of a few hours or days, this is referred to as acute iritis. Symptoms that develop gradually, or last longer than six weeks, indicate chronic iritis.
If not treated properly, iritis could lead to complications, including:
Cataracts. Development of a clouding of the lens of your eye (cataract) is a common complication, especially if you’ve experienced a long period of inflammation.
Calcium deposits on the cornea (band keratopathy). This condition results in degeneration of your cornea and could decrease your vision.
Swelling within the retina (cystoid macular edema). Swelling and fluid-filled cysts that develop in the retina at the back of the eye (macular retina) can blur or decrease your central vision.
Before diagnosing iritis, your eye doctor will conduct a complete eye exam, including:
External examination. During an external exam, your doctor may use a penlight to look at your pupils, observe the pattern of redness in your eye or eyes, and check for signs of discharge.
Visual acuity. Your doctor will note your visual acuity using an eye chart and other standard tests.
Slit-lamp examination. Using a special microscope with a light on it, your eye doctor views the inside of your eye looking for telltale signs of iritis, including the presence of white blood cells or hazy protein deposits (termed “flare”). To better view your eye’s interior, your doctor may give you eyedrops to dilate your pupil.
Glaucoma testing. During a glaucoma test, your eye doctor measures your intraocular pressure. Elevated intraocular pressure indicates that you may have glaucoma.
If your eye doctor suspects that a systemic condition is causing your iritis, he or she may work closely with your primary care provider to pinpoint the underlying cause. In that case, further testing may include blood tests or X-rays to identify or rule out specific causes.
Treatment for iritis
The main goals in treating iritis are to preserve vision and relieve any pain associated with the condition.
Most often, treatment for iritis involves:
Steroid eyedrops. Glucocorticoid medications, given as eyedrops, reduce inflammation associated with iritis. They work by stabilizing cell membranes in your eye and minimizing the circulation of white blood cells and other byproducts of the inflammatory process.
Dilating eyedrops. Cycloplegics are medicines that dilate your pupil. Given as eyedrops, they can reduce pain associated with iritis. Dilating eyedrops also protect you from developing adhesions underneath your iris, which can lead to potential complications, including glaucoma.
If your symptoms don’t clear up, or seem to get worse, your eye doctor might prescribe oral medications that may include steroids or other anti-inflammatory agents. However, taking the medicine orally has the potential to affect not only your eyes, but other parts of your body as well. Your doctor will consider your overall condition before prescribing oral medications to treat your iritis.