Tuesday, 10 February 2015

Structure Of An Eye


The eye is a wonderful structure capable of generating the sense that the more we relate to the environment. Basically it is a kind of highly sophisticated camera so the aspect of vision as the ability to track an object with complex movements. Or objective lens of the camera is constituted by a set of tissues: cornea, lens, vitreous and aqueous humor. The diaphragm is located at the pupil center of the iris. The photographic film is represented by the retina.


The front part of the eye is a transparent dome, on which the contact lens is placed and Lasik is practiced.


The transparent membrane that lines the front of the balloon excluding the cornea. Within it are tiny glands that produce tears and mucus that help lubricate and disinfect the eyeball.


 The lens is precisely behind the iris, and its function is to achieve accurate focusing, which is known as accommodation. The shape of the lens is altered by a muscle which changes its curvature to focus on nearby objects and distant objects. When it loses its transparency, speaking of cataract.


 Behind the cornea is the iris: circular portion of pigmented tissue that gives color to the eye. The pupil, a circular is in the middle of the iris opening is enlarged and reduced to control the quantity of light entering the eye.


 The sclera (or eyes) is the white fibrous outer layer that covers the eyeball. Its function is to protect the sensitive structures of the eye.


 The choroid is the layer of blood vessels and lies between the retina and the sclera. It provides oxygen and nutrients to the retina. RETINA: The retina is a thin coat of multiple cell layers that is in the back of the eye. It is a membrane, light-harvesting antenna true. It functions as a screen on which the cornea and lens focus images. The macula, in the center of the retina, is the region that gives the vision of detail, allowing reading and color vision. There are two types of photoreceptor cells in the retina, cones and sticks, they transform images into nerve impulses sent to the brain. The cones require a relatively bright light (of day) for operation, but can detect many shades and nuances of color. By contrast, the rods require very low light (night), they allow viewing without colors, in black blue background.


 Is the fluid that fills the anterior part of the globe, between the cornea and iris. This is renewed permanently and drains into the bloodstream.


 The vitreous is the transparent mass occupying the space between the lens and the retina. It consists of a gelatinous substance that maintains the shape of the eyeball.