The_Eye

The Eye The eye is a light-sensitive organ of vision. The eyes of various species vary from simple structures that are capable only of differentiating between light and dark to complex organs, such as those of humans and other mammals, that can distinguish variations of shape, color, brightness, and distance. The actual process of seeing is performed by the brain rather than by the eye. The function of the eye is to translate the electromagnetic vibrations of light into patterns of nerve impulses that are transmitted to the brain(Sams 11). The eyeball is a spherical structure approximately about 1 in. in diameter. The outer part of the eye is composed of three layers of tissue. The outside layer is the sclera, a protective coating. It covers about five-sixths of the surface of the eye. At the front of the eyeball, it is continuous with the bulging, transparent cornea. The middle layer of the coating of the eye is the choroid, a vascular layer lining the posterior three-fifths of the eyeball. The choroid is continuous with the ciliary body and with the iris, which lies at the front of the eye. The innermost eye, layer, cells, muscle, lens, eyeball, cornea, light-sensitive, light, front, fovea, ciliary, behind, transparent, retina, pupil, outer, nerve, humor, cone-shaped, composed, center, body, area, vitreous, tissue, surface, spot, spherical, small, rod-shaped, pigmented, optic, opening, membrane