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Vision

Valuable Vision

Our memory and mental processes rely heavily on sight. There are more neurons in the nervous system dedicated to vision than to any other of the five senses, indicating vision's importance in our lives. The almost immediate interaction between the eye and the brain in producing vision makes even the most intricate computer program pale in comparison. Although we seldom pause to imagine life without sight, vision is the most precious of all our senses. Without it, our relationship to the world about us, and our ability to interact with our environment, would diminish immeasurably.

See also Blindness and visual impairments; Brain; Color; Depth perception; Vision disorders.


Resources

Books

Hart, William M., Jr., ed. Adler's Physiology of the Eye. St. Louis: Mosby Year Book, 1992.

Hubel, David H. Eye, Brain, and Vision. New York: Scientific American Library, 1988.

Leibovic, K. N., ed. Science of Vision. New York: Springer-Verlag, 1990.

Lent, Roberto, ed. The Visual System-From Genesis to Maturity. Boston: Birkhauser, 1992.

Moller, Aage R. Sensory Systems: Anatomy and Physiology. New York: Academic Press, 2002.

von Noorden, Gunter K. Binocular Vision and Ocular Motility-Theory and Management of Strabismus. St. Louis: The C.V. Mosby Company, 1990.

Marie L. Thompson

KEY TERMS


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Accommodation

—Changes in the curvature of the eye lens to form sharp retinal images of near and far objects.

Cones

—Photoreceptors for daylight and color vision are found in three types, each type detecting visible wavelengths in either the short, medium, or long, (blue, green, or red) spectrum.

Ganglion cells

—Neurons in the retina whose axons form the optic nerves.

Ocular dominance

—Cells in the striate cortex which respond more to input from one eye than from the other.

Optic pathway

—The neuronal pathway leading from the eye to the visual cortex. It includes the eye, optic nerve, optic chiasm, optic tract, geniculate nucleus, optic radiations, and striate cortex.

Rods

—Photoreceptors which allow vision in dim light but do not facilitate color.

Stereopsis

—The blending of two different images into one single image, resulting in a three-dimensional image.

Suppression

—A "blocking out" by the brain of unwanted images from one or both eyes. Prolonged, abnormal suppression will result in underdevelopment of neurons in the visual pathway.

Synapse

—Junction between cells where the exchange of electrical or chemical information takes place.

Visual acuity

—Keenness of sight and the ability to focus sharply on small objects.

Visual field

—The entire image seen with both eyes, divided into the left and right visual fields.

Additional topics

Science EncyclopediaScience & Philosophy: Verbena Family (Verbenaceae) - Tropical Hardwoods In The Verbena Family to WelfarismVision - Our 3-d View Of The World, Ocular Dominance, Memory, Electrochemical Messengers, Color Vision - Optic pathway, Visual field, Accommodation, Common visual problems, Amblyopia, Other common visual problems