Posterior uveitis is the inflammation of the posterior part of the middle layer of the eye known as the uvea.
The middle layer of the eye is coloured and it consists of the following from the front to the back of the eye:
- Iris – The coloured part of the eye seen behind the transparent cornea. It contains muscles that constrict and dilate the pupil (the black space seen in the middle of the eye behind the cornea)
- Ciliary body – The extension of the iris that contains muscle that controls the shape of the lens as the eyes change focus from a far object to a near one.
- Choroid – The vascular part of the uvea that lies between the sclera and retina. It supplies oxygen and nutrients to the outer part of the retina
In posterior uveitis, the choroid is affected. The surrounding structures such as the retina may also be affected leading to a condition known as chorioretinitis.