One of the mysteries of the English language finally explained.
A form of abnormal colour vision characterized by reduced perception of light at the red end of the spectrum; = "protanopia". Also: colour vision or photosensitivity of this kind as a normal characteristic of a species.
Mid 19th century. From red + blindness, after German Rothblindheit. Compare slightly later red-blind.
In this article we explore how to impress employers with a spot-on CV.