Human eyesight

The human eye, also named eyeball, is the organ of vision, which allows us to see the real world around us in its different forms and colours. Consists of a set of parts and specialized cells sensitive to changes in light and are able to transform light images into electrical impulses which are sent to the brain for interpretation on the optic nerve Primates have the two eyeballs each other, allowing them to see a three-dimensional world. This is called stereoscopic vision. It is so that we can see the height, width, and depth of things, posibilitandonos calculate the distance of objects and be aware of our location in the space that surrounds us.

The human eye, or eyeball, has a roughly spherical shape, 25 mm in diameter and is filled with a transparent gel called vitreous humor which fills the space between the lens and the retina. It is composed basically by three layers of tissues that perform different functions: escelerotica, which is the outermost layer and is composed of fibrous connective tissue, which is the protecting and shaping of the eyeball; chlorid, the middle layer vascularizada, being its function nourish and oxygenate the retina; retina, layer sensitive internal light, being a kind of covered where the images are recorded.The choroid, next to the iris and ciliary body shape which is known as uveal tract, or uvea.

The eye has two solid transparent bodies that projects images on the retina: the cornea and the lens.The anterior eye are two small spaces, anterior chamber which is located between the cornea and the lens and the camera later, much smaller, which is located between the lens and iris. These cameras are filled with a liquid called aqueous humor, whose pressure level called intraocular pressure is very important for the proper functioning of the eye.

Thanks to the ciliary muscles and suspendory ligament, the lens is adjustable depending on the distance, a diaphragm called pupil diameter is regulated by the iris and a sensitive light which is retinal tissue.Light penetrates the cornea and pupil, passes through the lens, and is projected onto the retina, where is transformed thanks to a few cells called (rods and cones) photoreceptor in nerve impulses that are transferred from the optic nerve to the brain.

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