![]() Light absorption: the uvea improves the contrast of the retinal image by reducing reflected light within the eye (analogous to the black paint inside a camera), and also absorbs outside light transmitted through the sclera, which is not fully opaque.(The cornea has no adjacent blood vessels and is oxygenated by direct gas exchange with the environment.) Nutrition and gas exchange: uveal vessels directly perfuse the ciliary body and iris, to support their metabolic needs, and indirectly supply diffusible nutrients to the outer retina, sclera, and lens, which lack any intrinsic blood supply.The prime functions of the uveal tract as a unit are: ![]() It is traditionally divided into three areas, from front to back: The uvea is the vascular middle layer of the eye. Its use as a technical term for part of the eye is ancient, but it only referred to the choroid in Middle English and before. In fact, it is a partial loan translation of the Ancient Greek term for the choroid, which literally means “covering resembling a grape”. The originally medieval Latin term comes from the Latin word uva ("grape") and is a reference to its grape-like appearance (reddish-blue or almost black colour, wrinkled appearance and grape-like size and shape when stripped intact from a cadaveric eye). The uvea ( / ˈ j uː v i ə/ derived from Latin: uva meaning "grape"), also called the uveal layer, uveal coat, uveal tract, vascular tunic or vascular layer is the pigmented middle layer of the three concentric layers that make up an eye, precisely between the inner retina and the outer fibrous layer composed of the sclera and cornea.
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