Iritis (Anterior Uveitis)

Causes

• Autoimmune diseases: Iritis is often linked to systemic autoimmune or inflammatory diseases, including:
  • Ankylosing spondylitis
  • Rheumatoid arthritis
  • Psoriatic arthritis
  • Inflammatory bowel diseases (Crohn's disease, ulcerative colitis)
  • Sarcoidosis
  • Lupus

• Infections:
  • Viral infections (e.g., herpes simplex, herpes zoster, cytomegalovirus)
  • Bacterial infections (e.g., tuberculosis, syphilis, Lyme disease)
  • Fungal infections
  • Parasitic infections

• Eye injury or trauma: A blunt force injury to the eye can trigger iritis.
• Certain medications: Rarely, some medications can cause drug-induced iritis.
• Genetic factors: Individuals with certain genetic markers (e.g., HLA-B27) are more prone to developing iritis, especially when associated with autoimmune conditions.

Symptoms

• Eye pain: Often a deep, aching pain inside the eye, which can worsen with exposure to light or when pressing on the eye.
• Redness of the eye: Particularly around the iris and pupil.
• Photophobia (light sensitivity): Discomfort or pain when exposed to bright light.
• Blurred or hazy vision.
• Small or irregularly shaped pupil: The pupil may appear smaller than the other eye or have an irregular shape due to inflammation.
• Headache: May accompany eye pain.
• Tearing.

Diagnosis

• Medical history and physical exam: The doctor will ask about your symptoms, any underlying medical conditions, and family history.
• Slit-lamp examination: This is the primary diagnostic tool. The ophthalmologist uses a special microscope to examine the front structures of the eye (cornea, anterior chamber, iris, lens) for signs of inflammation, such as:
  • Cells and flare (protein leakage) in the anterior chamber.
  • Keratic precipitates (inflammatory cells deposited on the back of the cornea).
  • Posterior synechiae (adhesions between the iris and the lens).
• Intraocular pressure (IOP) measurement: Eye pressure may be normal, low, or elevated in iritis.
• Dilated fundus examination: To examine the back of the eye (retina and optic nerve) to rule out inflammation in other parts of the uvea (intermediate or posterior uveitis).
• Blood tests and imaging: If an underlying systemic disease or infection is suspected, the doctor may order blood tests (e.g., ESR, CRP, HLA-B27, tests for specific infections) or imaging (e.g., X-rays, MRI).

Treatment

• Corticosteroid eye drops: These are the primary treatment to reduce inflammation in the eye (e.g., prednisolone acetate, dexamethasone).
• Pupil-dilating eye drops (cycloplegics): These drops (e.g., cyclopentolate, atropine) help to relieve pain by relaxing the ciliary muscle, prevent the iris from forming adhesions (synechiae) to the lens, and reduce light sensitivity.
• Oral corticosteroids: For severe cases or if there is significant inflammation in other parts of the eye, oral corticosteroids may be prescribed.
• Immunosuppressants: For chronic, severe, or recurrent iritis associated with systemic autoimmune diseases, other immunosuppressive medications may be used to control the underlying condition and reduce inflammation.
• Treatment of underlying cause: If an infection is identified, appropriate antiviral, antibacterial, or antifungal medications will be prescribed. If an autoimmune disease is the cause, managing that condition is crucial.
• Pain relievers: Over-the-counter pain medications (e.g., ibuprofen) can help manage eye pain.

Treating Iritis So It Settles and Stays Away

Iritis responds well to steroid drops, but only when they are used far more often than most eye drops and tapered more slowly than feels necessary. Recurrences and complications usually trace back to how the drops were used or to a systemic cause that was never looked for.

Using the drops so they work

Steroid drops are typically started at a high frequency, sometimes every hour while awake in a severe attack, and reduced step by step over weeks as the inflammation clears on the slit lamp, not as the eye feels better. Stopping early or tapering fast is the most common cause of rebound. Prednisolone acetate is a suspension and must be shaken before each drop. Dilating drops blur near vision and enlarge the pupil while they last; they are continued because they prevent the iris from sticking to the lens, the complication that causes lasting damage. Sunglasses help meanwhile; our sun safety for eyes article covers choosing them.

The pressure check is part of the treatment

Steroid drops raise eye pressure in a minority of people, and the inflammation itself can too, so pressure is measured at every follow-up. A rise is treated with a pressure-lowering drop such as timolol rather than by abandoning the steroid, and it usually settles once the course ends. Long or repeated courses add to the risk of glaucoma and cataracts, which is why the taper is supervised.

When to look for a cause beyond the eye

A first episode in one eye that clears completely is usually not investigated. A second episode, both eyes, or an attack in someone with back stiffness in the morning, psoriasis, or diarrhea prompts blood tests including HLA-B27 and a search for psoriatic arthritis, ankylosing spondylitis, Crohn's disease, or ulcerative colitis. Iritis after shingles on the face or scalp is treated with an antiviral such as valacyclovir alongside the drops. For frequent or steroid-dependent disease, an immune-modulating treatment such as methotrexate or the biologic adalimumab, which is approved for non-infectious uveitis, controls attacks without repeated steroid courses.

What it is mistaken for

Pink eye causes a gritty, sticky eye without the deep ache, light sensitivity, or small pupil of iritis, and does not need steroids. A sudden painful red eye with a fixed mid-sized pupil, halos, and nausea is acute angle-closure glaucoma, an emergency. Herpes infection of the cornea can be made dramatically worse by steroid drops, which is why leftover drops are never used for a new red eye.

Recurrences and when to be seen

Starting treatment on the first day of an attack shortens it and reduces the chance of adhesions. New floaters or a fall in vision during an attack mean the inflammation may involve the back of the eye and are reported the same day; our floaters and flashes article covers those signs. Our ophthalmology team coordinates the systemic workup with the treating eye specialist. The National Eye Institute and MedlinePlus publish patient guidance on uveitis.

If you have had more than one episode of iritis and no one has looked for a cause, schedule a visit.