Wald, George (1906-1997) was an American biochemist who discovered how chemical changes in the retina enable a person to see. He also discovered the role of vitamin A in night blindness, and the chemical deficiencies that cause color blindness. For his work he shared the 1967 Nobel Prize in physiology or medicine with Ragnar Arthur Granit and Haldan Keffer Hartline.
Wald was born in New York City in 1906. He received a B.S. degree in zoology from New York University in 1927. After earning a Ph.D. degree in zoology from Columbia University in 1932, he received a National Research Council Fellowship in Biology. From 1932 to 1934, he studied with German biochemist Otto Heinrich Warburg in Berlin, with Swiss chemist Paul Karrer at Zurich, and German biochemist Otto Fritz Meyerhof in Heidelberg. Wald completed his fellowship at the University of Chicago. In 1934, he became a tutor in biochemistry at Harvard University and a full professor of biology in 1948. He remained at Harvard until 1977.
In Berlin, Wald discovered that vitamin A is an important component of the retina, particularly in the pigments in the retina's rods and cones. He continued this research at Harvard, and found a pigment called rhodopsin in the rods (the cells in the retina that enable night vision). Wald found that rhodopsin was composed of a colorless protein called opsin and a yellow substance called retinene, which proved to be a form of vitamin A. When stimulated by light, the rhodopsin molecule breaks down into its two component parts, and the retinene becomes vitamin A. Darkness reverses that process, and the components recombine into rhodopsin. These biochemical changes trigger electrical activity that stimulates the retinal and optic nerves, resulting in vision. Further research demonstrated that pigments in the retina's cones, also related to vitamin A, are responsible for color vision, and a lack of any of those pigments results in color blindness.
Wald also received the Albert and Mary Lasker Award of the American Public Health Association in 1953, the Rumford Premium of the American Academy of Arts and Sciences in 1959, and the Joseph Priestley Award in 1970.