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You are watching: The innermost layer of the eye that contains the vision receptors is called the

Purves D, Augustine GJ, Fitzpatrick D, et al., editors. Neuroscience. 2nd edition. Sunderland (MA): Sinauer Associates; 2001.


By covenant with the publisher, this book is accessible by the find feature, however cannot be browsed.
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The eye is a fluid-filled ball enclosed by three layers of organization (Figure 11.1). Most of the outer layer is composed of a tough white fibrous tissue, the sclera. In ~ the front of the eye, however, this opaque outer layer is transformed right into the cornea, a devoted transparent tissue that permits irradiate rays to go into the eye. The middle layer the tissue has three unique but constant structures: the iris, the ciliary body, and also the choroid. The iris is the colored part of the eye that have the right to be seen with the cornea. It has two sets of muscles through opposing actions, which allow the dimension of the pupil (the opened in the center) come be adjusted under neural control. The ciliary human body is a ring of organization that encircles the lens and also includes a muscular component the is crucial for adjusting the refractive strength of the lens, and a vascular component (the so-called ciliary processes) that produces the fluid that filling the front of the eye. The choroid is created of a rich capillary bed the serves as the main resource of blood supply because that the photoreceptors of the retina. Just the innermost class of the eye, the retina, has neurons that room sensitive come light and also are qualified of transmitting intuitive signals to central targets.


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En route to the retina, light passes v the cornea, the lens, and two unique fluid environments. The anterior chamber, the room between the lens and the cornea, is filled with aqueous humor, a clear, watery liquid that gives nutrients to these structures as well as to the lens. Aqueous humor is developed by the ciliary processes in the posterior chamber (the region between the lens and also the iris) and also flows right into the anterior chamber with the pupil. A devoted meshwork the cells the lies in ~ the junction of the iris and also the cornea is responsible because that its uptake. Under common conditions, the rates of aqueous humor production and uptake room in equilibrium, ensuring a continuous intraocular pressure. Abnormally high levels of intraocular pressure, which occur in glaucoma, can reduce the blood it is provided to the eye and eventually damage retinal neurons.

The room between the earlier of the lens and the surface of the retina is filled with a thick, gelatinous substance referred to as the vitreous humor, which account for about 80% that the volume of the eye. In addition to keeping the form of the eye, the vitreous humor has phagocytic cells that eliminate blood and other debris that can otherwise interfere v light transmission. The housekeeping abilities of the vitreous humor are limited, however, as a large number the middle-aged and also elderly individuals with vitreal “floaters” will attest. Floaters space collections of debris too big for phagocytic usage that thus remain to actors annoying shadows top top the retina; they commonly arise once the aging vitreous membrane pulls away from the overly long eyeball the myopic people (Box A).

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By commitment with the publisher, this book is obtainable by the find feature, but cannot be browsed.