Within the eye, the uveal tract consists of the iris, the ciliary body and the choroid. Uveitis is the inflammation of the uveal tract and panuveitis refers to inflammation of all three areas.
Inflammation of the choroid and the retina behind the base of the vitreous is known as posterior uveitis and inflammation of the posterior section of the ciliary body is called an intermediate uveitis.
Inflammation of the iris and anterior chamber of the eye, with no other ocular abnormality, is called anterior uveitis. Anterior uveitis may be further subdivided into iritis and iridocyclitis, when both the iris and the anterior ciliary body are involved.
Acute uveitis is when symptoms develop quickly, within hours or days. This episode of relative sudden onset usually lasts for up to three months.
A more gradual onset is associated with a chronic uveitis which tends to be more persistent and typically lasts longer than three months.
Relapses of the condition can occur.
Anterior uveitis/iritis accounts for the vast majority of uveitis seen in primary care. It usually, but not always, affects only one eye.
In about half of cases, iritis is idiopathic but there are some known causes. These include injury (including postoperative), infections (systemic and local) and autoimmune causes.
Infections are associated with posterior uveitis. Seronegative spondyloarthropathies, such as ankylosing spondylitis, psoriatic arthritis, inflammatory bowel disease and reactive arthritis, are more commonly associated with anterior uveitis.
Other associations with uveitis include juvenile rheumatoid arthritis and sarcoidosis.
2. Clinical features
Anterior uveitis tends to affect patients middle aged or younger.
Acute anterior uveitis can be more symptomatic compared with other versions of uveitis.
Symptoms and signs include pain, red eye, photophobia and reduced vision. There may also be lacrimation and while anterior uveitis often only affects one eye, it can be bilateral.
Any form of uveitis should be considered when faced with ocular pathology that includes pain, reduced vision, redness and photophobia. Differential diagnosis is varied and includes scleritis, keratitis, corneal ulceration and acute glaucoma.
Anterior uveitis is associated with inflammatory changes found in the anterior chamber. In more active forms, there may be a hypopyon which is a collection of inflammatory cells.
Cells known as keratic precipitates may be found on the inner corneal surface and their features may give diagnostic clues as to the type of uveitis.
Aqueous flare is caused by light scattering from proteins leaking into the aqueous humour as a result of the inflammatory reaction.
An ocular complication of anterior uveitis is the creation of posterior synechiae. These are adhesions between the anterior surface of the capsule of the lens and the iris.
If these are extensive they may impede the normal flow of aqueous leading to the peripheral iris being pushed forwards and causing iris bombe, raising intraocular pressure.
Within primary care, the GP's role is to consider the diagnosis of anterior uveitis and refer appropriately.
This is because anterior uveitis cannot be diagnosed without the use of a slit lamp examination. All patients with a painful, red eye with altered vision or photophobia without an adequate explanation should be referred for emergency ophthalmology opinion. Ideally, suspected uveitis should be seen by a specialist the same day.
A GP should not start treatment until the patient has been seen by the ophthalmologist, unless directed to do so. It is also important to remember that untreated uveitis can lead to visual loss. The aims of treatment are to preserve vision, relieve symptoms and identify and treat any underlying or associated conditions.
Dilating the pupil by application of eye drops, such as tropicamide, helps relieve some of the symptoms as well as reducing the chances of posterior synechiae being created. Steroids are one of the main therapeutic interventions for anterior uveitis and can be given as drops.
If there is a poor therapeutic response to treatment or if there is a relapse after reducing or stopping the treatment, then a periocular injection of steroids may be used. Oral steroids can also be used. Other medication, such as immunosuppressive drugs, may be used in more resistant cases.
It should be remembered that regular topical steroid use can lead to cataract formation and ultimately glaucoma, as well as leading to infection of the cornea.
It is very likely that treatment will be initiated and/or maintained by specialist services and any GP prescribing should be carefully coordinated with the specialist team.
- Dr Brown is a GP in Leeds
American Optometric Association. www.aoa.org/documents/CPG-7.pdf
Patient UK. www.patient.co.uk/health/uveitis-and-iritis.htm
Clinical Knowledge Summaries. www.cks.nhs.uk/uveitis/management/scenario_uveitis
Uveitis Information Group. www.uveitis.net/patient/anterior.php