Red Blind

A misleading name for Protanopia.

The name derives probably from the red-green opponent channel, which is – by definition – skewed permanently to the far green side in Protanopes, typically because they are missing the L-Cones that balance the channel.

“Red blind” infers that the individual sees any shade of red as white, black, gray, or transparent. While Protanopes typically see all reds as darker, and deep reds (i.e. Wavelengths longer than 670nm) as black (regardless of brightness), they still perceive reds as a color, even if that color is a confusion pair with Orange / Yellow / Green / Brown. In fact, Protanopes are more likely to see Cyan as White/Gray than Red.

See Red Weak.