Wald, George (1906-1997), an American biochemist, determined how chemical changes in the retina enable a person to see. He shared the 1967 Nobel Prize for physiology or medicine.
Wald analyzed the pigment (coloring matter) of rods, the cells in the retina that respond to dim light. He found that light causes certain changes in retinene, a chemical in the pigment. These changes trigger a nerve impulse that transmits to the brain an image of what is seen. Wald discovered that the body makes retinene from vitamin A. This discovery explained why a deficiency of vitamin A reduces vision at night.
Wald was born on Nov. 18, 1906, in New York City. He earned a Ph.D. at Columbia University. He joined the faculty of Harvard University in 1934. He was an outspoken opponent of the Vietnam War (1957-1975). He died on April 12, 1997.
