From visual physiology to chemistry
Wald studied with Selig Hecht at Columbia, receiving his doctorate in zoology in 1932. A fellowship then took him to Europe, including Otto Warburg’s Berlin laboratory. Investigating retinal substances turned questions about light sensitivity into problems of chemical isolation and identification.
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Identifying vitamin A in the retina
After detecting vitamin A in retinal extracts, Wald continued its identification in Paul Karrer’s Zurich laboratory. This connected vitamin A directly with processes inside the light-sensitive eye and supplied a biochemical subject for investigating the already recognized relationship between vitamin A deficiency and night blindness.
Light-induced changes in rhodopsin
Wald investigated how light breaks down rhodopsin, identifying the protein opsin and a substance he called retinene, subsequently called retinaldehyde, and examining its relationship with vitamin A. His continuing pigment research helped explain the initial chemical steps by which light starts visual signaling.
A long research career at Harvard
Wald joined Harvard in 1934 and became professor of biology in 1948. He shared the 1967 Nobel Prize with Hartline and Granit, whose work approached early visual processes through physiological and chemical investigations. Wald died in 1997.