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Anatomy and Physiology of the Eye

Eye Anatomy Facts

Vision is by far the most used of the five senses and is one of the primary means that we use to gather information from our surroundings. More than 75% of the information we receive about the world around us consists of visual information.

The eye is often compared to a camera. Each gathers light and then transforms that light into a "picture." Both also have lenses to focus the incoming light. Just as a camera focuses light onto the film to create a picture, the eye focuses light onto a specialized layer of cells, called the retina, to produce an image.

Parts of the eye.
Parts of the eye. Although the eye is small, only about 1 inch in diameter, each part plays an important role in allowing people to see the world.
Anatomy of the eye.
Anatomy of the eye. The eye is surrounded by the orbital bones and is cushioned by pads of fat within the orbital socket. Extraocular muscles help move the eye in different directions. Nerve signals that contain visual information are transmitted through the optic nerve to the brain.

Orbit

The orbit is the bony eye socket of the skull. The orbit is formed by the cheekbone, the forehead, the temple, and the side of the nose. The eye is cushioned within the orbit by pads of fat. In addition to the eyeball itself, the orbit contains the muscles that move the eye, blood vessels, and nerves.

The orbit also contains the lacrimal gland that is located underneath the outer portion of the upper eyelid. The lacrimal gland produces tears that help lubricate and moisten the eye, as well as flush away any foreign matter that may enter the eye. The tears drain away from the eye through the nasolacrimal duct, which is located at the inner corner of the eye.

Eyelids and Eyelashes

The eyelids serve to protect the eye from foreign matter, such as dust, dirt, and other debris, as well as bright light that might damage the eye. When you blink, the eyelids also help spread tears over the surface of your eye, keeping the eye moist and comfortable.

The eyelashes help filter out foreign matter, including dust and debris, and prevent these from getting into the eye.

Conjunctiva

The conjunctiva is a thin, transparent layer of tissues covering the front of the eye, including the sclera and the inside of the eyelids. The conjunctiva keeps bacteria and foreign material from getting behind the eye. The conjunctiva contains visible blood vessels that are visible against the white background of the sclera.

Sclera

The white part of the eye that one sees when looking at oneself in the mirror is the front part of the sclera. However, the sclera, a tough, leather-like tissue, also extends around the eye. Just like an eggshell surrounds an egg and gives an egg its shape, the sclera surrounds the eye and gives the eye its shape.

The extraocular muscles attach to the sclera. These muscles pull on the sclera causing the eye to look left or right, up or down, and diagonally.

Cornea

The cornea is the transparent, clear layer at the front and center of the eye. In fact, the cornea is so clear that one may not even realize it is there. The cornea is located just in front of the iris, which is the colored part of the eye. The main purpose of the cornea is to help focus light as it enters the eye. If one wears contact lenses, the contact lens rests on the cornea.

Medically Reviewed by a Doctor on 4/7/2016

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