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Like a camera, an eye uses light to record images. The eye, like a camera, has a lens, a way to control the amount of light coming
through the lens, focusing mechanisms, and a place where light is focused to create images; however, eyes are much more complex and delicate than even the most
expensive and technically advanced camera.
At Spokane Eye Clinic, we believe that knowing how the eye works is important for a patient when they are making decisions about their eye care. In order for our patients to begin to understand their eyes, we present the following anatomy of the eye and definition of a few basic terms used in eye care. |
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The Cornea Light first enters the eye through the cornea, the clear front "window" of the eye. The cornea provides most of the focusing power of the eye. |
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The Pupil Light coming through the cornea then travels through the pupil, which regulates the amount of light allowed to reach the back of the eye. The pupil is the normally black portion in the center of the eye, which grows larger in low light situations and smaller when light is more bright and intense. |
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The Iris The colored portion of your eye is called the iris. The iris is not only pretty, it is the muscle which regulates the pupil, making it grow larger or smaller, depending upon the amount of light in any given situation. |
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The Retina The surface onto which light is focused is the retina. The retina is a “saran-wrap” thin membrane held to the inside back portion of the eye by a kind of suction force. Within the retina are light receptors called rods and cones. These nerves translate light into the information sent to the brain along the optic nerve, which is connected to the retina at the back of the eye. A special place on the retina, located just above the optic nerve, called the macula, is the most concentrated area of nerves. It is here that your most detailed central vision is created. |
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The Optic Nerve All information from the retina is sent along the optic nerve and into the brain, where it is translated into an image. |
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Rods and Cones The nerve receptors in the retina are called rods and cones. These are very specially adapted nerves, which are sensitive to different kinds of light. Cone cells provide detail and color or "day" vision and are located primarily in the macula, while rod cells are not color or detail sensitive and provide "night" vision. Rods can be found throughout the retina but are especially concentrated around its edges, where they help to create peripheral vision. |
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The Vitreous The gel-like fluid that fills the eye is called the vitreous. The main function of this fluid is to maintain the shape of the eye. Light coming into the eye through the cornea and lens has to travel through the vitreous before reaching the retina. |
