Uveitis
consists of
a group of diseases characterised by significant sight threatening
intraocular inflammation primarily involving the uveal tract (iris,
ciliary body, and choroid), although inflammation of adjacent
tissues, such as retina, optic nerve, and vitreous humour also
occurs.
Little is known about the pathogenesis of uveitis, but in cases of
endogenous uveitis in which no link with an infectious agent can be
identified, autoimmunity has been invoked as the cause. Many cases
are often labelled as idiopathic, but in some it may be part of
systemic disease process, such as sarcoidosis, multiple sclerosis,
and Behçet’s disease, or associated with the HLA-B27 positive group
of diseases. Infectious agents, such as the herpes group of
viruses, toxoplasma gondii, mycobacterium tuberculosis, and
treponema pallidum are also well-recognised causes.
Uveitis mainly occurs in the 20-50 year age group, and can affect
one or both eyes. The incidence of uveitis varies from 14 to
52.4/100,000 with the overall prevalence around the world is up to
0.73%. A recent study found that the extrapolated 10-year incidence
of uveitis was almost three times higher than that reported almost
40 years previously. Most uveitis patients present at an age where
they are in the most active period of their working life. In about
half the patients the age of onset is in the third or fourth decade
of life. This age distribution makes uveitis a group of ocular
diseases with an important socioeconomic impact.
Many cases will resolve rapidly, but a significant number of
patients develop persistent disease with inflammatory damage to
ocular structures resulting in severe visual impairment. The main
causes of sight loss are cystoid macular oedema, cataract, and
glaucoma.
Approximately 5-20% of legal blindness in developed countries is
due to uveitis, and it has been estimated that uveitis accounts for
10-15% of all cases of total blindness in the USA. Acute anterior
uveitis is the commonest subtype and carries the best visual
outcome, with a worse visual prognosis seen in patients with
posterior uveitis and panuveitis.
In non-infectious
causes, therapy is usually aimed at dampening down the immune
response with corticosteroids being the first line treatment. In
sight threatening disease immunosuppressive agents may need to be
added to improve or preserve sight.
For more information on uveitis please check out:
Uveitis Information
Group
Behçet’s Syndrome
Society
Birdshot
(chorioretinopathy) Uveitis Society