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The uveal tract comprises the iris, ciliary body, and the choroid. It is the middle vascular layer of the eye and is protected externally by the sclera and the cornea. The choroid is designated as the posterior part of the tract; structures preceding it, as the anterior part.
Uveitis is a general term for inflammatory disorders of the uveal tract (occasionally adjacent structures like retina, optic nerve, and vitreous humor may also be involved) (1).
It is commonly seen in people between the ages of 20-50 but can occur at any age. Around 5% of the uveitis patients are children younger than 16 years (2). One or both eyes may be affected (1).
The annual incidence is around 14-17 per 100,000. In the developed world it is the fifth commonest cause of visual loss with 10-15% of cases becoming totally blind (3).
The Systematic Uveitis Nomenclature (SUN) working group classifies uveitis according to anatomical location of the inflammation:
- anterior uveitis – commonest sub type, there is inflammation of the anterior chamber
- intermediate uveitis – vitreous is inflamed
- posterior uveitis – inflammation of the retina or choroids
- panuveitis – inflammation of the anterior chamber, vitreous, retina or choroids (1)
Anterior uveitis is the preferred term for iritis and iridocyclitis; posterior uveitis for choroiditis, and since the retina is almost always secondarily affected, chorioretinitis. Iritis describes an acute non-granulomatous anterior uveitis.
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