Dr. George Wald won the Noble Price in 1967 He gave the real understanding of role of Vitamin A in human visual sciences and he also identified the presence of Xanthophyll pigments at macula which plays a key role. But, for years together, there was no attention given to these macular pigments. Pigments in photo receptors produces neural response to light, hence it is considered very important.
Whereas, because macular pigments do not produce neural responses, historically it is/was considered to be secondary or of less importance, not only that at times even considered nuisance by many!