Uveitis-associated glaucoma is a secondary form of glaucoma. It can be caused by alteration of the protein content of the aqueous fluid - resembling undiluted serum - which may be a cause of elevated intraocular pressure; or by the use of corticosteroids (a hormone produced by the adrenal gland or a synthetic substitute) used to treat inflammation in uveitis. Inflammation of the ciliary body usually leads to reduced aqueous production, and combined with increased outflow, low intraocular pressure (hypotony) often is a consequence.
Uveitis refers to inflammation of any part of the uvea - the pigmented middle coat of the eye containing the iris and ciliary body (the anterior) and the choroid (the posterior) segment of the eye. Its exact cause is unknown, but a wide variety of medical conditions can lead to the development of uveitis, including
Autoimmune disease
viral (eg herpes)
fungal (eg histoplasmosis)
parasitic (eg toxoplasmosis)
eye trauma
inflammatory bowel disease
Reiter's syndrome (an arthritis-like syndrome)
ankylosing spondylitis (where some or all of the joints and bones of the spine fuse together)
psoriasis
Lyme disease
lens-associated uveitis
masquerade syndrome - (eye disorders that are clinically present as either an anterior or posterior uveitis, but are not primarily inflammatory). These include: foreign body; juvenile xanthogranuloma; leukaemia; malignant melanoma; retinoblastoma; retinal detachment; lymphoma; malignant melanoma; multiple sclerosis; reticulum cell sarcoma; and retinitis pigmentosa.
Uveitis is more common in the 20 to 50 age group - equally in male and female - and can affect one eye (unilateral) or both eyes (bilateral). It is thought to be responsible for around 10% of blindness in the USA.
Anterior uveitis is commonly known as iridocyclitis. Infection can be acute (resolving in a few days or weeks) or chronic (lasting months or years). Symptoms may include moderate to severe pain, redness, blurred vision, excessive secretion of tears (lacrimation) and abnormal sensitivity to light (photophobia). In severe cases, adhesions form between the iris and lens capsule, preventing the flow of aqueous fluid in the posterior and anterior chambers. The lens will bulge and subsequently block the canal of Schlemm, resulting in elevated intraocular pressure and chronic closed-angle glaucoma.
Intermediate uveitis (vitritis) affects the ciliary body, vitreous (the transparent jelly-like substance filling the posterior cavity of the eye) and retina. In severe cases, loss of vision can occur. Signs include the presence of whitish-yellow deposits of inflammatory cells (called 'snowballs') on the most forward edge of the retina and the pars plana (the flattened back portion of the ciliary body), floaters (opaque specks in the vitreous space) and blurred vision.
Posterior uveitis is the more common condition. The retina and the choroid (a layer of blood vessels which supplies the retina) become inflamed (choroidoretinitis). The cause may be from the spread of infection associated with the front of the eye (anterior segment) or may be secondary to a very wide variety of systemic conditions (related to a particular system of the body). Pan-uveitis occurs when all layers of the uvea become inflamed
Signs and symptoms
Symptoms may vary. Anterior uveitis may present acute symptoms of unilateral (one eye) painful red eye, blurred vision, sensitivity to light, and excessive tearing. Symptoms of chronic uveitis may produce recurrent episodes, with few or no acute symptoms. Posterior uveitis may present symptoms including blurred vision, floaters, occasional pain, and occasional light sensitivity.
Diagnosis
To diagnose uveitis, the ophthalmologist may perform the following examinations:
• check for inflammation to the front of the eye with an intense beam of light using a slit-lamp
• check visual acuity (which may be decreased in the affected eye)
• perform a funduscopic exam to the back of the eye
• measure intraocular pressure
• measure eye movements
• check for corneal swelling (oedema) and ulcers
• check for clumps of white blood cells on the back of the cornea and look for signs of "mutton-fat" granular appearance.
The anterior chamber is filled with aqueous humor. Normally, the aqueous humor is optically clear, but in uveitis an increase in the protein content of the aqueous causes an effect upon examination known as 'flare', which is similar to that produced by a moving projector beam in a dark smoky room.
Opacities of the lens (cataracts) may be present but are not specific for uveitis.
Intraocular pressure may be normal or slightly decreased in the acute phase due to decreased aqueous humor production; however, pressure may become elevated as the inflammation subsides.
Treatment
Treatment of uveitis depends on the cause of the disease. The main aim is to prevent sight loss by regulating intraocular pressure, and relieve pain and discomfort. Treatment in the form of topical (surface) eye drops such as steroids and cyloplegic drugs (to paralyse the ciliary muscles of the eye) may be recommended.
Outcome
Generally, the prognosis is good with appropriate treatment. During the acute phase of uveitis, the ophthalmologist may perform a slit-lamp examination every 1-7 days and measure intraocular pressure. Once the condition is stable, follow-up may only be necessary every six months.
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