Uveitis is inflammation of the middle layer of the eye, which is called the uvea (or uveal tract).
The uvea is made up of the iris (coloured part of the eye), the ciliary body (ring of muscle behind the iris) and the choroid (layer of tissue that supports the retina).
Inflammation of the uvea usually causes a red eye, sometimes with cloudy vision, and it may be painful (see Symptoms, above, for more information).
Uveitis may be caused by an injury, infection or underlying disease (see Causes). If it is not treated, the eyesight can be seriously damaged.
Uveitis can affect anyone. It particularly affects people of working age but can also occur in children.
The type of uveitis depends on which part of the eye is affected:
Acute uveitis lasts for a few weeks and can recur, whereas chronic uveitis lasts for more than three months, with symptoms that can vary from day to day.
If you have uveitis, it may have implications on your fitness to drive.
The cause of uveitis is often unknown, but it may result from:
Uveitis may be associated with the following conditions:
Your GP or ophthalmologist (eye specialist) will be able to diagnose uveitis based on your symptoms.
The eye is examined with a slit lamp (a microscope designed for eye examination). White blood cells and protein in the eye fluid can be seen through the microscope if you have uveitis. As the light beam passes through the eye, the fluid inside is seen to be hazy instead of clear.
A light will be shone into the unaffected eye and this will cause both pupils to constrict. If one eye is affected by uveitis, there will be a slight pain in the eye as the pupil constricts.
There will normally be an examination of the inside of the eye to see if other parts of the eye are affected.
Uveitis must be distinguished from conjunctivitis. Conjunctivitis never affects vision (although it may cause clouding of vision if pus briefly gets onto the cornea) and it does not affect the inside of the eye, just the outside.
Blood tests, X-rays and other tests may be done to establish the cause of the uveitis.
If you have uveitis, you will have some or all of the following symptoms.
Anterior uveitis affects the front of the eye (usually the iris) and is the most common type. Only one eye is usually affected. Symptoms include:
These symptoms may develop gradually over hours or days. They may be acute (lasting a few weeks) or chronic (lasting for more than three months).
Intermediate uveitis is the second most common type, affecting the area just behind the ciliary body and part of the retina. Both eyes tend to be affected and it is usually painless.
Symptoms can include:
There is usually no redness or only mild redness associated with intermediate uveitis.
Posterior uveitis affects the back of the eye (the choroid) where your blood vessels supply the retina. One or both eyes may be affected and it is usually painless.
Posterior uveitis usually causes decreased vision and floaters, and sometimes retinal detachment (see Useful links) These symptoms are slower to develop and often last longer than those of anterior uveitis.
Posterior uveitis can be more damaging to the eye than other types of uveitis. It sometimes causes visual loss.
Treatment of uveitis will depend on the type of uveitis, how serious it is and the cause. Some cases will clear up with the use of eyedrops. Others may need steroid injections into the eye.
The aim of treatment is to:
If you have recurrent uveitis, it is important to get it treated quickly. You may be advised to keep steroid eyedrops to hand at all times.
The different treatments are outlined below.
Mydriatic eye drops, such as atropine or cyclopentolate, dilate (widen) the pupil. This helps the eye to heal, prevents the pupil from getting stuck to the lens and decreases the eye pain. Your doctor will advise how often you should use these.
Mydriatic eye drops may cause blurred vision, difficulty focusing and an increased sensitivity to light, but they are a vital part of treatment.
If the condition is diagnosed early and treated with eye drops, no visual loss should occur.
Steroid eyedrops help decrease the inflammation of the iris. They will be used frequently at first and then tapered off, to prevent the uveitis recurring.
Steroid eyedrops are usually not used if a virus or bacteria caused the condition.
Steroid tablets (such as prednisolone) or a steroid injection into the eye may be recommended in severe cases of uveitis, when eye drops have no effect. The injection is done under local anaesthetic and you can go home on the same day.
In some cases, a steroid drip (methylprednisolone) may be given in hospital.
Prolonged steroid treatment needs to be carefully monitored for side effects (see Complications).
Immunosuppressants are drugs that suppress the body's immune system. Examples are:
These tablets can be used alongside steroids to treat some types of uveitis.