Uveitis is inflammation of the uvea, one of the layers enclosing the eyeball.
Uveitis has many different causes, including infection, autoimmune disease and trauma.
Anterior uveitis, which affects the parts of the uvea at the front of the eye, notably the iris, is the most common type of uveitis.
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Symptoms vary and may be subtle, but can include red, painful eyes and vision problems.
Depending on the type of uveitis present, treatment may involve antibiotics, antiviral drugs, steroids, immunosuppressants or mydriatics.
What is uveitis?
Uveitis is inflammation of a part of the eye called the uvea.
The uvea
The eyeball is enclosed within three layers: the uvea is the layer lying between the outer layer (the sclera) and the inner (the retina, the light-gathering nerve layer). The uvea consists of the iris (coloured structure surrounding the pupil), the ciliary body (located behind the iris, this structure focuses the lens) and the choroid (layer rich in blood vessels that lines the back of the eye and supplies blood to the retina).
Uveitis: underlying causes and risk factors
The many different causes of uveitis include the following:
An infection such as a virus (e.g. herpes) or a fungus (e.g. histoplasmosis)
A parasite (e.g. toxoplasmosis)
An autoimmune disease (when your immune system attacks a part of your own body), such as ankylosing spondylitis
Trauma to the eye, or even previous trauma to the other eye
Chemical exposure
Cataract
Corneal ulcer (the cornea is the transparent anterior portion of the sclera)
In many cases (up to 75%), the cause cannot be determined. This may mean that the uveitis is of the autoimmune type.
Types of uveitis
Uveitis is classified depending on the structure affected:
Anterior uveitis: affects the parts of the uvea at the front of the eye, the iris and the ciliary body.
Iritis: inflammation of the iris
Iridocyclitis: inflammation of both iris and ciliary body.
Anterior uveitis is the most common form of uveitis. As the iris is the structure most usually affected, "anterior uveitis" and "iritis" are often used synonymously. The inflammation is often associated with autoimmune diseases, and a history of these is a risk factor. The disorder may affect only one eye and is most common in young and middle-aged people.
Intermediate uveitis (or peripheral uveitis): the next most common type. It affects the area immediately behind the ciliary body (pars plana) and the most forward edge of the retina.
Posterior uveitis: inflammation of the choroid, the part of the uvea at the back of the eye. It may involve the choroid cell layer (choroiditis), the retinal cell layer (retinitis) or both (choroidoretinitis). Posterior uveitis usually follows a systemic infection.
Diffuse uveitis (or panuveitis): inflammation of all three structures (iris, ciliary body and choroid)
Symptoms and signs of uveitis
Symptoms and signs of uveitis may be subtle, and vary depending on the site and severity of the inflammation. Symptoms may include:
Red, painful eye
Watery eye
Blurred vision
Photophobia (sensitivity to light)
Dark, floating spots ("floaters") in your vision (posterior uveitis)
Small pupils
Excessive blinking and squinting
Normally clear cornea may appear dull or cloudy
How is uveitis diagnosed?
Uveitis is usually diagnosed by ophthalmic examination, consisting of a visual inspection of the internal and external structures of the eye using instruments that magnify and illuminate, such as the slit lamp. In more advanced cases, changes may be visible without special instruments. The examination may also include the measurement of intra-ocular pressure (pressure within the eyeball).
If your doctor diagnoses uveitis and suspects that it is a sign of underlying disease, blood samples may be taken and other tests performed to ascertain the cause.
How is uveitis treated?
Treatment of uveitis aims to:
Relieve pain and discomfort
Prevent sight loss due to the disease or its complications
Treat the cause of the disease where possible.
If the inflammation is caused by an infection, treatment will involve antibiotics or antiviral drugs. Other drugs used to treat uveitis fall into three main groups: steroids, immunosuppressants and mydriatics (pupil dilators).
Steroids
Steroids make up the major part of uveitis treatment. They act as anti-inflammatory and immunosuppressant agents.
The method used to deliver the steroid depends on the severity and location of the inflammation. Different forms used include:
Eyedrops, used for anterior uveitis.
Peri-ocular injections (local injections around the eye), used as follows:
for severe anterior uveitis that cannot be controlled by drops alone
for intermediate uveitis
to avoid or limit the use of systemic steroids in children, in whom the side-effects are more significant.
Systemically, via the bloodstream, either orally (usually prednisolone tablets) or by intravenous infusion (drip). Intravenous infusion (usually of methylprednisolone) is used if rapid control of acute inflammation is needed and sight is threatened. The procedure is normally done in a hospital ward to allow close monitoring of reactions and side-effects.
Systemic steroids are mainly used to treat posterior uveitis, but may be considered if anterior uveitis is particularly severe or resistant to treatment with drops or injections.
Follow the instructions for taking steroid tablets conscientiously. The consequences of missing steroid dosages can be severe. Never stop taking steroids or reduce their dosage without your doctor's permission.
Although most people taking systemic steroids only experience a few, if any, significant side-effects, these can be serious and may include:
Nausea and heartburn
Increased appetite, weight gain and fluid retention
Mood changes
High blood pressure
Increased hair growth
Diabetes
Osteoporosis
Bruising and delayed wound healing
Growth suppression in children
Cataract
Glaucoma
Immunosuppressants
Immunosuppressants, usually used in conjunction with steroids, tend to target the immune system more precisely than the latter. However, side-effects of immunosuppressants can be more severe, so careful monitoring is essential. Examples of immunosuppressants: cyclosporin, azathioprine, methohextrate.
Mydriatics
Mydriatic eyedrops, such as atropine and cyclopentolate, are used to treat anterior uveitis by relieving pain and preventing sight-threatening complications.
Mydriatics work by temporarily paralysing the muscles of the iris and the ciliary body (it is the movement of these inflamed muscles that causes pain). When the drops have taken effect, the pupils will be dilated and this may cause temporary blurring of vision.
These drugs also help to prevent a complication of anterior uveitis called synechiae. The inflamed iris sticks to the lens and can cause raised intra-ocular pressure, which may be sight-threatening if left untreated.
What is the outcome of uveitis?
The outcome varies quite considerably from person to person. Uveitis may persist for days to years, but with treatment it can be well controlled. The course of the condition may be characterised by recurrent flare-ups. Early intervention will limit or prevent complications.
Possible complications of uveitis include:
Glaucoma
Cataract
Fluid in the retina
Retinal detachment
Vision loss
Can uveitis be prevented?
Timely treatment of known causative disorders may help to prevent uveitis.
When to call the doctor
Call your doctor if you experience any symptoms of uveitis. If these include eye pain or reduced vision, contact your doctor immediately.
If you are taking systemic steroids, consult your doctor if you develop any illness, especially an infection, or if you are concerned about side-effects.
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