WHAT IS UVEITIS?
Uveitis is a name given to inflammation inside the eye that in some patients can lead to blindness. It can affect one or both eyes and the inflammation involves the uveal tract (iris, ciliary body, and choroid), although inflammation of adjacent tissues, such as vitreous humour, retina, and optic nerve also occurs.
Little is known about the causes of uveitis, but in cases of endogenous uveitis in which no link with an infectious agent can be identified, abnormalities of immune regulation have been invoked as the cause. Many cases are often labelled as idiopathic, but in some they 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.
The incidence of uveitis varies from 14 to 52.4/100,000 with the overall prevalence around the world up to 0.73%. In about half the patients the age of onset is in the third or fourth decade of life, so they are presenting at an age where they are in the most active period of their working life. This age distribution makes uveitis a group of ocular diseases with an important socioeconomic impact. There is a specific sub-group in children that is associated with juvenile idiopathic arthritis.
Many cases will resolve rapidly, some may have repeated attacks in one or both eyes, 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 edema, 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 where the back of the eye is involved.
In non-infectious causes, therapy is usually aimed at dampening down the immune response with corticosteroids being the first line treatment. For anterior uveitis eye drops are often the mainstay of treatment, but in sight threatening disease corticosteroid tablets then immunosuppressive agents and biologics may be required to improve or preserve sight.
