George Wald (1906-1997) was awarded one-third of the 1967 Nobel Prize in Physiology or Medicine for his discoveries concerning the primary physiological and chemical visual processes in the eye. Wald discovered that vitamin A is a vital ingredient of the pigments in the retina and is important in maintaining vision. Later, he elucidated the chemical reactions involved in the vision process of the eyeâ€™s rod cells. With Paul K. Brown, he identified the pigments in the retina that are sensitive to yellow-green, red, and blue light. Wald and Brown also discovered the role of vitamin A in forming the three color pigments and showed that color blindness is caused by the absence of one of them.