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The eye is made up of three coats, or layers, enclosing various anatomical structures. The outermost layer, known as the fibrous tunic , is composed of the cornea and sclera , which provide shape to the eye and support the deeper structures.
The macula (/ˈmakjʊlə/) [1] or macula lutea is an oval-shaped pigmented area in the center of the retina of the human eye and in other animals. The macula in humans has a diameter of around 5.5 mm (0.22 in) and is subdivided into the umbo, foveola, foveal avascular zone, fovea, parafovea, and perifovea areas.
The uvea (/ ˈ j uː v i ə /; [1] 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.
The resulting eye is a mixture of a simple eye within a compound eye. Another version is a compound eye often referred to as "pseudofaceted", as seen in Scutigera . [ 28 ] This type of eye consists of a cluster of numerous ommatidia on each side of the head, organised in a way that resembles a true compound eye.
The human choroid is thickest at the far extreme rear of the eye (at 0.2 mm), while in the outlying areas it narrows to 0.1 mm. [1] The choroid provides oxygen and nourishment to the outer layers of the retina. Along with the ciliary body and iris, the choroid forms the uveal tract.
The foveola is located within a region called the macula, a yellowish, cone photoreceptor filled portion of the human retina.Approximately 0.35 mm in diameter, the foveola lies in the center of the fovea and contains only cone cells and a cone-shaped zone of Müller cells. [1]
The anterior segment or anterior cavity [1] is the front third of the eye that includes the structures in front of the vitreous humour: the cornea, iris, ciliary body, and lens. [2] [3] Within the anterior segment are two fluid-filled spaces: the anterior chamber between the posterior surface of the cornea (i.e. the corneal endothelium) and the ...
Different species are able to see different parts of the light spectrum; for example, bees can see into the ultraviolet, [55] while pit vipers can accurately target prey with their pit organs, which are sensitive to infrared radiation. [56] The mantis shrimp possesses arguably the most complex visual system of any species. The eye of the mantis ...