Uveitis: Types, Causes, Warning Signs and Treatment

Uveitis is inflammation of the uvea, the middle layer of the eye wall, and often of nearby structures such as the retina, vitreous gel and optic nerve. The uvea is made up of the iris (the coloured part of the eye), the ciliary body (which produces the fluid inside the eye and helps focus) and the choroid (a layer of blood vessels that nourishes the retina). Because it is so richly supplied with blood, the uvea is a common site for the immune system to cause inflammation.

Uveitis is less common than conditions such as conjunctivitis, but it is far more serious. It is a significant cause of preventable sight loss, particularly in working-age adults, and can lead to complications such as glaucoma, cataract and swelling of the retina. The key message is simple: a painful red eye with light sensitivity or blurred vision needs prompt assessment by an eye specialist. This guide explains the types of uveitis, its causes and associations, the symptoms that should prompt urgent care and how it is treated.

Types of uveitis

Specialists classify uveitis mainly by the part of the eye that is inflamed, using criteria from the international Standardization of Uveitis Nomenclature (SUN) working group. The type gives clues to the cause, symptoms, treatment and outlook.

Uveitis is also described by its course: acute (sudden onset, limited duration), recurrent (repeated episodes separated by periods without inflammation) or chronic (persistent inflammation, or relapse within three months of stopping treatment).

Symptoms

Symptoms depend on the type of uveitis. They can affect one or both eyes and can develop suddenly or gradually.

• Eye pain, often a deep ache, which may worsen when focusing on near objects.
• Redness, typically most intense in a ring around the cornea (ciliary flush).
• Sensitivity to light (photophobia), sometimes severe.
• Blurred or cloudy vision.
• Floaters: dark spots or cobwebs drifting across vision, especially in intermediate and posterior uveitis. See our guide to floaters and flashes.
• A small or irregular pupil.
• Headache in some cases.

How uveitis differs from conjunctivitis

Uveitis is sometimes mistaken for conjunctivitis, which can delay treatment. Conjunctivitis typically causes grittiness, itching and discharge with normal vision, whereas anterior uveitis causes pain, light sensitivity and blurred vision without significant discharge. Read our guide to conjunctivitis and the article red eye: harmless or an emergency? for more on telling red eyes apart.

Causes and associations

In a large proportion of cases, no specific cause is found; this is called idiopathic uveitis. In others, uveitis is linked to a condition elsewhere in the body, an infection, an injury or, rarely, a medicine.

HLA-B27 and autoimmune associations

HLA-B27 is a genetic marker carried by a minority of the general population. People who carry it have a higher risk of acute anterior uveitis and of a group of inflammatory conditions called spondyloarthropathies. HLA-B27-associated uveitis typically affects one eye at a time, starts suddenly, is quite painful and tends to recur, sometimes alternating between eyes. Associated conditions include:

• Ankylosing spondylitis (axial spondyloarthritis): inflammatory back pain and stiffness, typically worse in the morning and improving with movement.
• Reactive arthritis, which can follow certain gut or genital infections.
• Psoriatic arthritis.
• Inflammatory bowel disease, including Crohn's disease and ulcerative colitis.

If you have recurrent acute anterior uveitis, your doctor may test for HLA-B27 and ask about back pain, joint pain, skin rashes and bowel symptoms. Diagnosing an associated condition can lead to treatment that protects both your eyes and your joints.

Other systemic conditions

• Juvenile idiopathic arthritis in children.
• Sarcoidosis, which can affect the lungs, skin, lymph nodes and eyes.
• Behçet's disease, with mouth and genital ulcers, more common in people from Turkey, the Middle East and East Asia.
• Multiple sclerosis, associated with intermediate uveitis. See also optic neuritis.
• Vogt-Koyanagi-Harada disease and other rarer autoimmune conditions.

Infections

Infections can cause uveitis directly. Important examples include toxoplasmosis (a parasite and a leading cause of posterior uveitis worldwide), herpes simplex and herpes zoster viruses, cytomegalovirus in people with weakened immune systems, tuberculosis, syphilis and Lyme disease. Identifying an infection is vital because steroids alone can make an infection worse; specific antimicrobial treatment is needed.

Other causes

Eye injury or surgery can trigger inflammation (traumatic uveitis). Rarely, certain medicines cause uveitis. In older people, some cancers such as intraocular lymphoma can masquerade as chronic uveitis.

Why uveitis needs urgent care

Uveitis can damage delicate structures inside the eye quickly. Without treatment, inflammation can cause the iris to stick to the lens (posterior synechiae), raise or occasionally lower eye pressure, lead to swelling at the centre of the retina (macular oedema) and cause scarring. Prompt treatment reduces pain and the risk of permanent damage. If you have a painful red eye with light sensitivity or blurred vision, you should be seen the same day or within 24 hours, ideally at an eye casualty department or by an ophthalmologist. If you have had uveitis before and recognise the symptoms, contact your eye clinic quickly; many services offer rapid access for known patients.

How uveitis is diagnosed

An ophthalmologist examines the eye with a slit lamp microscope and can see inflammatory cells floating in the fluid at the front of the eye or in the vitreous. They will measure eye pressure and examine the retina and optic nerve through a dilated pupil. Optical coherence tomography (OCT) scans detect macular oedema, and angiography may be used for posterior uveitis. Depending on the type and history, blood tests (including HLA-B27, markers of infection such as syphilis and tuberculosis, and markers of sarcoidosis), a chest X-ray or scans may be arranged. A single, first mild episode of typical anterior uveitis may not need extensive tests. Learn more about eye examinations.

Treatment

Treatment aims to control inflammation quickly, relieve pain, prevent complications and treat any underlying cause. The choice depends on the type, severity and cause of uveitis. Your ophthalmologist determines the medicine, strength and schedule; never adjust or stop steroid treatment on your own.

Steroid eye drops

For anterior uveitis, corticosteroid eye drops are the mainstay of treatment. They are often used very frequently at first, then reduced gradually over weeks as the inflammation settles. Stopping too quickly can cause the inflammation to rebound. Shake the bottle well, as many steroid drops are suspensions.

Dilating drops

Drops that dilate the pupil and relax the focusing muscle (cycloplegics) relieve pain and help prevent the iris from sticking to the lens. They cause blurred near vision and light sensitivity while in use.

Steroid injections, implants and tablets

For intermediate, posterior or severe uveitis, steroids may be given as injections around or into the eye, as slow-release implants inside the eye, or as tablets or intravenous treatment. These are effective but carry more risk of side effects.

Immunosuppressive and biologic medicines

When uveitis is chronic, recurrent, affects both eyes severely or needs long-term high-dose steroids, specialists use steroid-sparing medicines. These include conventional immunosuppressants such as methotrexate, mycophenolate and azathioprine, and biologic medicines that block TNF-alpha, such as adalimumab, which is approved for certain forms of non-infectious uveitis. They require regular blood tests and close monitoring, often in collaboration with a rheumatologist.

Treating infections

Infectious uveitis is treated with specific antimicrobial medicines, sometimes combined with steroids under careful supervision once the infection is controlled.

Side effects and complications to watch for

For more on these conditions, see our guides to glaucoma and cataract. Systemic steroids can also affect blood sugar, blood pressure, bones, mood and sleep, which is one reason steroid-sparing medicines are used for long-term control.

Living with uveitis

Many people have a single episode that settles completely with treatment. Others experience recurrences or chronic disease that needs long-term care. Helpful habits include:

• Learn to recognise early symptoms of a flare and seek help promptly.
• Use drops exactly as prescribed, including the gradual taper; set reminders if needed.
• Attend all follow-up appointments, even when your eyes feel fine, to monitor eye pressure and catch complications early.
• Tell your rheumatologist, gastroenterologist or GP about eye flares, and tell your eye doctor about joint, bowel or skin symptoms.
• Wear sunglasses to ease light sensitivity during flares.
• Do not smoke; smoking has been linked with a higher risk and severity of uveitis.

Eye exercises do not treat uveitis and should never delay medical care.

When to see a doctor

Parents of children with juvenile idiopathic arthritis should make sure their child is enrolled in regular eye screening, as uveitis in these children is often silent. For general guidance on eye emergencies, see eye emergencies and first aid.