- For the Pacific island, see Wallis Island.
The uvea (Lat. uva, grape), also called the uveal layer, uveal coat, uveal tract, or vascular tunic, is the pigmented middle of the three concentric layers that make up an eye. The name is possibly a reference to its almost black colour, wrinkled appearance and grape-like size and shape when stripped intact from a cadaveric eye. Its use as a technical term in anatomy and ophthalmology is relatively modern. Image File history File links Gray869. ...
The human iris The iris is the green/grey/brown area. ...
Schematic diagram of the human eye The ciliary body is the part of the eye containing the ciliary muscle and ciliary processes. ...
The choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye lying between the retina and the sclera. ...
Image File history File links Schematic_diagram_of_the_human_eye_en. ...
Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ...
Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ...
Elseviers logo. ...
Wallis (Uvea) is an island in the Pacific Ocean belonging to the French territory of Wallis and Futuna. ...
Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ...
// A human eye. ...
Human heart and lungs, from an older edition of Grays Anatomy. ...
This does not adequately cite its references or sources. ...
Anatomy
Regions The uvea lies between the corneosclera (outermost layer of the eye) and the retina (innermost layer/in the back of the eye). It is traditionally divided into 3 or 4 regions, the iris, ciliary body, pars plana and choroid. These distinctions are based on their different structures as seen under light microscopy, and continued use of these terms is appropriate in anatomical studies. For clinical use, the terms anterior uvea (ie, iris and ciliary body) and posterior uvea (ie, choroid) are now in common use, since diseases often spread beyond a single anatomical region of the uvea. The sclera and cornea form the fibrous tunic of the bulb of the eye; the sclera is opaque, and constitutes the posterior five-sixths of the tunic; the cornea is transparent, and forms the anterior sixth. ...
Human eye cross-sectional view. ...
The human iris The iris is the green/grey/brown area. ...
Schematic diagram of the human eye The ciliary body is the part of the eye containing the ciliary muscle and ciliary processes. ...
The pars plana is part of the uvea, one of the three layers that comprise the eye. ...
The choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye lying between the retina and the sclera. ...
Histology In general the uvea consists of a pigmented, highly vascular loose fibrous tissue. The pigment is produced and held in numerous dendritic melanocytes, similar to normal dermal melanocytes. The blood vessels show patterns which are specific to the region of the uvea, and are described in more detail under iris, ciliary body, pars plana and choroid. The stroma also contains large nerves, which are branches of the posterior ciliary nerves. They enter the eye around the optic nerve, and run forwards in the uvea to reach their termination in the cilary body or iris. These parts of the uvea also contain smooth muscle. Melanocytes are cells located in the bottom layer of the skins epidermis. ...
The human iris The iris is the green/grey/brown area. ...
Schematic diagram of the human eye The ciliary body is the part of the eye containing the ciliary muscle and ciliary processes. ...
The pars plana is part of the uvea, one of the three layers that comprise the eye. ...
The choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye lying between the retina and the sclera. ...
This article is about the anatomical structure. ...
External and internal relations These are described in more detail under the anatomic regions, as above.
Broadly, the outer aspect of the posterior uvea lies directly against the sclera, but at the root of the iris, the uvea is reflected sharply towards the central axis, so that its outer surface becomes the anterior surface of the iris, which is in contact only with the aqueous humour. The aqueous humour is a a thick watery substance that is located in the eye. ...
The inner aspect of the posterior uvea lies against Bruch's membrane, which separates it from the retina. On passing forwards beyond the ora serrata, Bruch's membrane and the retina are no longer present, and the inner relation of the uvea is a continuous epithelial sheet, represented in turn by the pars plana epithelium, the ciliary epithelium and the iris pigment epithelium. Bruchs membrane is the innermost layer of the choroid. ...
Human eye cross-sectional view. ...
The pars plana is part of the uvea, one of the three layers that comprise the eye. ...
Anatomy The iris pigment epithelium (IPE) is a two-cell thick layer of cuboidal cells lying behind the iris. ...
Physiology The prime functions of the uveal tract as a unit are:
1. 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, cornea & lens, which lack any intrinsic blood supply.
2. 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 by no means opaque.
In addition, some uveal regions have special functions of great importance, particularly secretion of the aqueous humour by the ciliary processes, control of accommodation (focus) by the ciliary body, and optimisation of retinal illumination by the iris's control over the pupil. Many of these functions are under the control of the autonomic nervous system. The ciliary processes are formed by the inward folding of the various layers of the choroid, i. ...
Human eye The Accommodation Reflex is a reflex action of the eye, in response to focusing on a near object, then looking at distant object (and vice versa). ...
The human eye The pupil is the central transparent area (showing as black). ...
This article or section is in need of attention from an expert on the subject. ...
Pharmacology The pupil provides the neatest and most visible example of the neural feedback control in the body. This is subserved by a balance between the antagonistic sympathetic and parasympathetic 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 drugs, even crude plant extracts, applied to the cornea. Pharmacological control over pupil size continues to be an important part of the treatment of some ocular diseases - see pupil, uveitis, acute glaucoma, chronic glaucoma. Grays FIG. 838– The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses. ...
Autonomic nervous system innervation, showing the sympathetic and parasympathetic (craniosacral) systems, in red and blue, respectively The parasympathetic nervous system is one of three divisions of the autonomic nervous system. ...
The human eye The pupil is the central transparent area (showing as black). ...
Uveitis specifically refers to inflammation of the middle layer of the eye, termed the uvea but in common usage may refer to any inflammatory process involving the interior of the eye. ...
Human eye cross-sectional view. ...
The metabolically-active process of secreting aqueous humour can also be reduced by drugs, which is important in treating both acute and chronic glaucoma. Human eye cross-sectional view. ...
Immunology The normal uvea contains immune competent cells, particularly lymphocytes, and is prone to respond to inflammation by developing lymphocytic infiltrates. A rare disease called sympathetic ophthalmia may represent 'cross-reaction' between the uveal and retinal antigens (ie, the body's inability to distinguish between them, with resulting misdirected inflammatory reactions). Sympathetic ophthalmia (SO) is a granulomatous uveitis (a kind of inflammation) of both eyes following trauma to one eye. ...
An antigen is any molecule that is recognized by antibodies. ...
Pathology See uveitis, choroiditis, iritis, anterior uveitis, sympathetic ophthalmia, uveal melanoma. Uveitis specifically refers to inflammation of the middle layer of the eye, termed the uvea but in common usage may refer to any inflammatory process involving the interior of the eye. ...
Iritis is a form of anterior uveitis and refers to the inflammation of the iris of the eye. ...
Sympathetic ophthalmia (SO) is a granulomatous uveitis (a kind of inflammation) of both eyes following trauma to one eye. ...
Uveal Melanoma is cancer (melanoma) of the colored part of your eye and the surrounding areas (uvea). ...
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