Wednesday, April 8, 2009

Uveal Tract

The uveal tract is the inner membrane which lines the back of the retina. The uveal tract is also known as the vascular tunic which extends forward to include the iris. It is divided into three parts; the choroid, the ciliary body, and the iris.

The uveal tract consists of a pigmented, highly vascular loose fibrous tissue. The prime functions of the uveal tract as a unit are nutrition, gas exchange, and light absorption. Uveal vessels perfuse the ciliary body and iris, to support their metabolic needs, and indirectly supply diffusible nutrients to the outer retina, cornea, and lens, which lack any intrinsic blood supply. The uveal tract improves the contrast of the retinal image by reducing reflected light within the eye, and also absorbs outside light transmitted through the sclera, which is by no means opaque.