Iritis

Iritis

Introduction

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
  • headaches

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.

Read more about the causes of uveitis.

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.

Read more about treating uveitis.

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

Complications

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.

Read more about the possible complications of uveitis.

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:

Infection

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

Other 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.

Treating uveitis

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.

Glaucoma

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)
  • laser treatment
  • surgery

Read more about treating glaucoma.

Cataracts

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
  • glare

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.

See cataracts and cataract surgery for more information.

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.

Detatched retina

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.

Posterior synechiae

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.

Diagnosing uveitis

Symptoms of uveitis

One or both eyes may be affected by uveitis. The symptoms can develop suddenly or gradually over a few days.

Signs of uveitis include:

  • a painful red eye – the pain can range from mild aching to intense discomfort, and reading or other tasks that require you to focus your eye can make the pain worse
  • blurred or cloudy vision
  • sensitivity to light (photophobia)
  • floaters – shadows that move across the field of vision
  • loss of peripheral vision – the ability to see objects at the side of your field of vision
  • seeing flashing lights

However, symptoms of pain and redness are usually only present in the most common form of uveitis affecting the front of the eye (anterior uveitis).

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 less likely it is that a person will have permanent problems with their vision.