Uveitis is inflammation (swelling) of the middle layer of the eye, called the uvea or uveal tract.
The uvea is made up of the iris (the coloured part of the eye), the ciliary body (the ring of muscle behind the iris), and the choroid (the layer of tissue that supports the retina).
Symptoms of uveitis include:
a painful red eye – the pain can range from mild aching to intense discomfort, and focusing your eye can make the pain worse; the eye can feel tender or bruised
blurred or cloudy vision – this may come after other symptoms
sensitivity to light (photophobia)
marked or new floaters – shadows, webs, dots or veils that move across the field of vision
loss of peripheral vision (the ability to see objects at the side of your field of vision)
a pupil shaped differently or that doesn't get smaller when reacting to light
One or both eyes may be affected by uveitis. The symptoms can develop suddenly or gradually over a few days.
People with long-term uveitis tend to have more visual symptoms and their eyes may look normal. Patients with sudden onset uveitis usually have more pain and tenderness.
When to seek medical advice
Contact your GP as soon as possible if you have persistent eye pain or you notice an unusual change in your vision, particularly if you've had previous episodes of uveitis. The sooner uveitis is treated, the more successful treatment is likely to be.
Your GP may refer you to an ophthalmologist, who is a specialist in eye conditions. An ophthalmologist will examine your eye in more detail with a microscope and light (a slit-lamp), and may suggest further tests if uveitis is diagnosed.
This may include scans of your eyes, X-rays and blood tests. Knowing the cause of your uveitis will help determine the treatment needed.
Why does uveitis happen?
There are a wide range of potential causes for uveitis, although a specific cause is not always identified.
Many cases are thought to be the result of a problem with the immune system (the body's defence against illness and infection). For unknown reasons, the immune system can become overactive in the eye.
Less commonly, uveitis can be caused by an infection or injury to the eye, and it can also happen after eye surgery.
Types of uveitis
There are different types of uveitis, depending on which part of the eye is affected:
anterior uveitis – inflammation of the iris (iritis) or inflammation of the iris and the ciliary body (iridocyclitis); this is the most common type of uveitis, accounting for about three out of four cases, tends to come on quickly, and can be recurrent, causing pain and redness
intermediate uveitis – inflammation of the area behind the ciliary body and the vitreous jelly; this can cause floaters and blurred vision
posterior uveitis – inflammation at the back of the eye, the choroid and the retina; this can cause problems with vision
In some cases, uveitis can affect the front and back of the eye. This is known as panuveitis.
How is uveitis treated?
The main treatment of uveitis is steroid medication (corticosteroids), which can reduce inflammation inside the eye.
The type of steroid medication used depends on the type of uveitis you have. Eye drops are often used for uveitis affecting the front of the eye, whereas injections, tablets and capsules are more often used to treat uveitis affecting the middle and back of the eye.
In some cases, additional treatment may be needed. This might be eye drops to relieve pain, a type of medicine called an immunosuppressant, and even surgery.
Uveitis caused by infection needs specific treatment.
How long can it last?
Uveitis can be:
acute – when it resolves quickly after treatment
recurrent – when repeated episodes are separated by gaps of several months
chronic – when the condition continues long-term or requires long-term medication to control it
Although most cases of uveitis respond quickly to treatment and cause no further problems, there is a risk of complications.
The risk is higher in people who have intermediate or posterior uveitis, or have repeated episodes of uveitis.
Complications of uveitis include permanent damage of the eye and some loss of vision.
It's estimated that the more serious types of uveitis are responsible for 1 in every 10 cases of visual impairment in the UK.
Who is affected?
Uveitis is uncommon. It's estimated that 2 to 5 in every 10,000 people will be affected by uveitis in the UK every year.
It usually affects people aged 20 to 59, but can also occur in children. Men and women are affected equally.
It's more likely to occur in people with other inflammatory or immune conditions.
Despite being uncommon, uveitis is a leading cause of visual impairment in the UK. This is why it's very important to diagnose and treat the condition as early as possible.
Causes of uveitis
Uveitis occurs when the eye becomes inflamed.
Inflammation is when areas of the body become warm, red and swollen in response to an illness or infection.
Most cases of uveitis are thought to be related to a problem with the immune system (the body's defence against infection and illness).
If the specific cause of uveitis is not identified, it is known as idiopathic uveitis. But most experts suspect idiopathic uveitis is also related to a problem with the immune system.
Immune system problems
Uveitis often develops in people who have an underlying autoimmune condition (where the immune system mistakenly attacks healthy tissue).
Autoimmune conditions known to cause uveitis in some people include:
ankylosing spondylitis – a condition mainly affecting the spine
reactive arthritis – a type of arthritis often affecting the joints, genitals and eyes
conditions that cause bowel inflammation – such as Crohn's disease and ulcerative colitis
psoriasis – a skin condition caused by the immune system disrupting the normal production of skin cells
multiple sclerosis – a condition mainly affecting the nerves
Behçet's disease – a rare condition that causes mouth ulcers and genital ulcers
sarcoidosis – a rare inflammatory condition affecting the lungs, skin and eyes
Uveitis can also be caused by an infection, such as:
toxoplasmosis – an infection caused by parasitic germs spread in raw meat and soil
herpes simplex virus – the virus responsible for cold sores
varicella-zoster virus – the virus that causes chickenpox and shingles
cytomegalovirus – a common infection that doesn't usually cause any noticeable symptoms in most people, but can cause sight-threatening uveitis in people with a lowered immune system
tuberculosis – this can lead to uveitis, either during the infection or after it's been treated
HIV and syphilis are rare causes
Uveitis can also be caused by:
trauma or injury to the eyes, or eye surgery
some types of cancers, such as lymphoma, although this is a very rare cause of uveitis
sometimes no cause can be found
Can I inherit uveitis?
Uveitis can't be passed down through the family because there's no gene that causes the condition.
However, your genes may make you more susceptible to developing the condition.
Treatment for uveitis will depend on which areas of the eye are affected and what caused the condition.
Medication is the main treatment, but surgery can be used in particularly severe cases.
Steroid medication (corticosteroids) is used to treat most cases of uveitis. A medicine called prednisolone is usually used.
Corticosteroids work by disrupting the normal function of the immune system so it no longer releases the chemicals that cause inflammation.
Corticosteroids are available in a number of forms, and the type used will often depend on the areas of your eye affected by uveitis.
Corticosteroid eye drops
Corticosteroid eye drops are usually the first treatment recommended for uveitis affecting the front of the eye (anterior uveitis) that is not caused by an infection.
Depending on the severity of your symptoms, the recommended dose can range from having to use eye drops every hour to once every two days.
You may experience temporary blurred vision after using corticosteroid eye drops. If this happens, don't drive or operate machinery until your vision returns to normal. In some people, steroid eye drops can increase pressure in the eye. The ophthalmologist will check for this, and advise you if it occurs.
Don't stop using your eye drops until your GP or ophthalmologist advises that it's safe to do so, even if your symptoms disappear. Stopping treatment too soon could lead to your symptoms returning. The frequency of drops is usually slowly reduced over a matter of weeks.
If the middle or back of your eye is affected (intermediate or posterior uveitis) or corticosteroid eye drops haven't worked, you may need corticosteroid injections.
The injection can be given to the side of the eye (subconjunctival) or around the eye (periocular). Local anaesthetic eye drops are used to numb your eye so you won't feel any pain or discomfort.
You'll usually only require one injection while your symptoms are at their worst.
Corticosteroid injections rarely cause significant side effects, but in some people they can make the pressure in the eye increase. The ophthalmologist will check for this and advise you if this happens.
Oral corticosteroids (tablets or capsules) are the strongest form of corticosteroids. They are usually used if steroid eye drops and injections haven't worked or are unsuitable, or for posterior uveitis.
Corticosteroids tablets can cause a wide range of side effects, so they may only be recommended if it's thought there is a risk of permanent damage to your vision without this treatment. See complications of uveitis for more information.
How long you'll have to take oral corticosteroids for depends on how well you respond to treatment and whether you have an underlying autoimmune condition. Some people only need a three- to six-week course, while others need to have a course lasting months or possibly years.
Short-term side effects of oral corticosteroids can include weight gain, increased appetite, mood changes such as feeling irritable or anxious, and insomnia. In the long-term they can cause osteoporosis (fragile bones), thinning of the skin, and an increased risk of infection.
To minimise the impact of side effects, you will be prescribed the lowest possible dose that's thought to be effective enough to control your symptoms.
Don't suddenly stop taking your oral corticosteroids. If your GP or ophthalmologist decides to end your treatment, they'll gradually reduce the amount of corticosteroids that you're taking.
Mydriatic eye drops
If you have uveitis affecting the front of your eye (anterior uveitis), you may be given special eye drops called mydriatic or dilating eye drops in addition to steroid medication.
These drops dilate your pupils and relieve pain by relaxing the muscles in your eye. They can also reduce the risk of the iris (the coloured part of the eye) "sticking" to the lens (the transparent section at the front of the eye). This can result in a condition called glaucoma, which affects vision.
However, these drops can cause some temporary blurring of your vision and problems focusing your eyes.
If the cause of your uveitis is known to be an underlying infection, the infection may also need to be treated.
Viruses can be treated with antiviral medication, bacterial infections can be treated with antibiotics, and fungal infections can be treated with antifungal medication.
The medications will usually be used alongside appropriate steroid medication and cycloplegic or mydriatic eye drops.
A very small number of people with uveitis fail to respond to the above treatments. In such circumstances, a type of medication called an immunosuppressant may be recommended.
Immunosuppressants are a type of medication that suppress (control) the immune system and disrupt the process of inflammation.
If you are having steroid treatment that is causing significant side effects, immunosuppressants can also be used to allow your dose of steroids to be reduced.
Possible side effects of immunosuppressants include:
numbness or tingling in different parts of your body
loss of appetite
nausea and vomiting
high blood pressure
Taking immunosuppressants will make you more vulnerable to infection, so you should try to avoid close contact with anyone who has a known infection.
You should also report any symptoms of a potential infection, such as a high temperature, cough or inflammation in other parts of your body, to your GP. You should also have the annual flu jab.
In rare cases, surgery may be needed to treat uveitis. However, this is usually only recommended if you have repeated or severe uveitis, or if the condition is caused by certain infections.
An operation called a vitrectomy can be used to treat uveitis. This involves gently sucking out the jelly-like substance that fills the inside of the eye (the vitreous humour). It can be carried out either using general anaesthetic or local anaesthetic.
The fluid inside the eye will be temporarily replaced during the operation with either a bubble of air or gas (or a mixture of the two), or a liquid substitute. Eventually, the eye will naturally replace the vitreous humour with a slightly different clear fluid called aqueous humour.
Like all operations, a vitrectomy carries a risk of complications. These include needing further surgery and an increased risk of developing cataracts (cloudy patches in the lens of the eye).
The following may help your symptoms
wear dark glasses if your eye becomes sensitive to light
place a warm flannel over the eye to soothe it
relieve pain by taking painkillers, such as ibuprofen
Complications of uveitis
Uveitis can sometimes lead to further problems, especially if it's not treated properly.
People with chronic (long-term) uveitis, or the less common types of uveitis affecting the middle or back of the eye (intermediate and posterior uveitis), are most at risk of developing complications.
Complications are also more likely to occur in adults who are over 60 years old.
Other eye conditions can sometimes be caused by the steroids used to treat the uveitis, such as secondary glaucoma and cataracts.
Some of the more common complications of uveitis are described below.
Untreated uveitis can cause the iris (the coloured part of the eye) to stick to the front surface of the lens (the transparent structure that focuses the light entering your eye). This prevents fluid draining through the pupil and increases the pressure inside the eye.
The raised pressure inside your eye can damage the optic nerve (the nerve at the back of the eye that transmits images to the brain) and disrupt your normal vision, such as causing misty vision and rings or halos to appear around lights. This is known as glaucoma.
Treatment options for glaucoma include:
eye drops (usually all that is required)
The inflammation inside the eye associated with uveitis can sometimes irritate the lens of the eye, causing cloudiness of the lens to develop. The cloudiness is known as cataracts. They can cause symptoms such as:
blurred, hazy vision
problems seeing clearly at night
Cataracts are usually treated using surgery to remove the affected lens and replace it with an artificial one. It's important that the uveitis is controlled and treated before considering cataract surgery.
Cystoid macular oedema
Cystoid macular oedema, or swelling of the retina, is a complication that can affect some people with chronic uveitis or uveitis that affects the back of the eye.
Prolonged inflammation can result in a build-up of fluid within the central retina (the macula). This can disrupt its ability to function normally and lead to a painless loss of central vision. You may notice a black spot in your central vision.
Cystoid macular oedema can be treated using corticosteroid injections or tablets.
In most cases, a person's vision will recover once treatment is initiated. However, this isn't always the case in severe prolonged cases of cystoid macular oedema. This is why the condition is a leading cause of visual impairment in people with uveitis.
Retinal detachment occurs when the thin lining at the back of your eye called the retina begins to pull away from the blood vessels that supply it with oxygen and nutrients.
It can also rarely be caused by inflammation related to uveitis, and is treated in the same way as the uveitis. It can also occur after an attack of posterior uveitis caused by viruses, in which case it may need urgent surgery.
Symptoms include progressive further deterioration in vision, floaters (dark spots that float in your field of vision) and flashing lights.
You should contact your GP or eye department straight away if you have these symptoms.
This is caused by the iris sticking to the lens of the eye as a result of inflammation. It's more likely if uveitis isn't treated quickly.