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| Uvea | |
|---|---|
 Graphical representation of an eyeball. The constituents of the uvea follow:iris (labeled as 9),ciliary body (labeled as 3), andchoroid (labeled as 28.) | |
 Horizontal section of the eyeball. The constituents of the uvea follow: iris labeled at top, ciliary body labeled at upper right, and choroid labeled at center right.) | |
| Details | |
| Part of | The human eye |
| System | Sensory nervous system |
| Location | Lies between the corneosclera (outermost layer of the eye) and the retina (innermost layer/in the back of the eye |
| Identifiers | |
| Latin | tunica vasculosa bulbi |
| MeSH | D014602 |
| TA98 | A15.2.03.001 |
| TA2 | 6752 |
| FMA | 58103 |
| Anatomical terminology | |
Theuvea (/ˈjuːviə/;[1] derived fromLatin:uva meaning "grape"), also called theuveal layer,uveal coat,uveal tract,vascular tunic orvascular layer, is the pigmented middle layer of the three concentric layers that make up aneye, precisely between the innerretina and the outer fibrous layer composed of thesclera andcornea.
The originally medieval Latin term comes from the Latin worduva ("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). In fact, it is a partial loan translation of the Ancient Greek term for thechoroid, which literally means “covering resembling a grape”.[2][3] 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.[4][5]
The uvea is the vascular middle layer of the eye. It is traditionally divided into three areas, from front to back:
The prime functions of the uveal tract as a unit are:
In addition, some uveal regions have special functions of great importance, including secretion of the aqueous humour by theciliary processes, control ofaccommodation (focus) by the ciliary body, and optimisation of retinal illumination by the iris's control over thepupil. Many of these functions are under the control of theautonomic nervous system.
The pupil provides a visible example of the neural feedback control in the body. This is subserved by a balance between the antagonisticsympathetic andparasympathetic divisions of the autonomic nervous system. Informal pharmacological experiments have been performed on the pupil for centuries, since the pupil is readily visible, and its size can be readily altered by applying drugs—even crude plant extracts—to the cornea. Pharmacological control over pupil size remains an important part of the treatment of some ocular diseases.
Drugs can also reduce the metabolically active process of secreting aqueous humour, which is important in treating both acute and chronicglaucoma.
The normal uvea consists of immune competent cells, particularly lymphocytes, and is prone to respond to inflammation by developing lymphocytic infiltrates. A rare disease calledsympathetic ophthalmia may represent 'cross-reaction' between the uveal and retinalantigens (i.e., the body's inability to distinguish between them, with resulting misdirected inflammatory reactions).
Seeuveitis,choroiditis,iritis,iridocyclitis,anterior uveitis,sympathetic ophthalmia, anduveal melanoma.
| Fibrous tunic (outer) |
|  | |||||
|---|---|---|---|---|---|---|---|
| Uvea / vascular tunic (middle) |
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| Retina (inner) |
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| Anatomical regions of the eye |
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| Other | |||||||
