The eye

Essay by nikitalolHigh School, 12th grade February 2004

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The Eye

A person's eyes are his or her windows to the world. Sight is one of the most important senses a human being may have. There are several components involved in vision that help us perceive our surroundings. These parts work together to focus light so that one is able to see the images in his or her environment.

Light enters the eye through a transparent shield called the cornea. It is attached to the outer wall of the eye. The cornea focuses light rays so that they go in a straight line into the rest of the eye. It is also very tough and durable so that it can help protect the eye from any particles that may get in.

After going through the cornea, light rays have to pass through the pupil. It is an adjustable opening that is controlled by the iris. The iris (the colored part of the eye) decides how much or how little light will be passed through.

The pupil is the dark spot in the center of the eye which leads to the lens.

The lens is a flexible, elastic structure that bends and adjusts to focus light onto the retina. The lens is the last structure to focus light rays; therefore it does the most converging. The focus of the lens is comparable to that of a camera, which can change the focal point for objects close up and far away. The process of the lens bending and changing shape is called accommodation. Abnormalities in the eye can interfere with the way the lens is able to focus light. This can cause the individual to be nearsighted or farsighted, in which case the object is focuses either behind or in front of the retina.

The retina is located at the back...