shape of the human eye is spherical.The average diameter of the body of the order of two and a half centimeters.
anatomy of the human eye
Outside eyesight surrounded by three membranes.
First, durable and firm (external) is called the sclera (or protein shell).It provides protection from mechanical damage.The front area of the sclera and transparent cornea called (the cornea).In the rest of the surface of the eye, it is not transparent and is called protein (is white).
By sclera inside the adjacent choroid.It is formed of a fairly complex web of vessels feeding the eye.This shell becomes iridescent shell, painted in different people in different colors and having in the center of the hole.It is called the pupil.Iris has the ability to deform and change the diameter of the pupil.Changes made at reflexes related to the amount of light entering the eye.In bright light the pupil narrows to two millimeters, with little coverage extends, in some cases up to eight millimeters.
On choroid is the inner side of the retina (retina).It covers all eyeground, except for the front region.The optic nerve, the brain provides a connection with the eye, the retina in the back part.The shell consists essentially of branched nerve fibers and nerve endings.Thus formed hypersensitive surface of the eye.
between the cornea and the iris is the anterior chamber, the chamber filled with moisture.
Directly behind the pupil is the lens.It contains a transparent elastic body having the form of a biconvex lens.The surface of the lens may have a different curvature, depending on the impact of muscles, fitting it on all sides.
With the change in the curvature of the image is carried out to bring objects at different distances, well to the surface of the sensing layer of the retina.The described process is called accommodation.Eye cavity behind the lens is filled with a transparent gelatinous liquid.It forms the vitreous.
optical system of the eye is similar to the corresponding structure in the camera.The lens acts as a lens in conjunction with the anterior chamber and the vitreous body having refractive properties.
image is projected onto the photosensitive surface of the retina.Sharpness is achieved by means of accommodation.
optical system of the eye includes (as a camera system) aperture, capable of changing the diameter.The role played by the pupil aperture.
capacity for accommodation on the retina produces sharp images of objects located at different distances.
At rest the eye optical system allows you effortlessly accommodation clear image of distant objects (stars, for example).With the efforts of the muscles, increases the curvature of the lens and reducing its focal length, eye body performs sharpening on the desired object.
optical system of the eye with age is changing.By age decreases the ability of the accommodation.The closest distance at which the optical system of the eye can provide a clear image, ranging from ten (aged up to twenty years) to twenty-two centimeters (up to forty years).With age the shortest distance increases to thirty centimeters and more - developed age farsightedness.
optical system of the eye contains a point, passing through which the rays are refracted almost.This is a point inside the lens, near the back of the plane.
