Uveitis refers to inflammation of the uveal tract. It has many diverse causes, but the vast majority are due to either infection or autoimmunity. It can affect people of any age but most commonly presents in people between 20 and 60 years of age. The causes of uveitis vary from one part of the world to another and in patients of different ages. At least half of all cases are deemed to be “idiopathic”. This means that it is autoimmune in nature and caused by the immune system mistakenly identifying part of the uveal tract as foreign, leading to inflammation in the eye.

Uveitis can be divided into different types based on which part of the uveal tract is affected. In anterior uveitis the inflammation is confined to the anterior chamber. Typically, anterior uveitis is acute in onset over 1-2 days and causes pain, redness of eye, light sensitivity and blurring of vision. Intermediate uveitis is characterised by inflammation in the vitreous associated with mild anterior chamber inflammation. It commonly causes water logging of the retina too, known as cystoid macular oedema. Intermediate uveitis usually develops slowly over many months and runs a chronic relapsing course, with cystoid macular oedema as the main cause of blurring of vision. Patients with intermediate uveitis complain of floaters and slow onset blurring of vision over months. Posterior uveitis is characterised by inflammation of the retina and/or choroid at the back of the eye. It may develop rapidly or slowly, depending on the cause. It is usually painless and the main complaint caused by posterior uveitis is blurring of vision. In panuveitis all three parts of the uveal tract are involved. The symptoms are a combination of anterior and posterior uveitis, often with pain, light sensitivity and blurring of vision with a variable time of onset.