What is the peak wavelength discrimination for a protanope or deuteranope?

The peak wavelength discrimination for a protanope or deuteranope is typically centered around 490 nm, which happens to be in the blue-green region of the spectrum. This group of individuals has a deficiency in red photoreceptors (for protanopes) or green photoreceptors (for deuteranopes), affecting their ability to discriminate between wavelengths in the red to green range.

The peak discrimination at 490 nm reflects the optimal sensitivity for distinguishing color differences in the absence of normal red or green sensitivity. This aligns with the characteristics of these color vision deficiencies. The wavelengths near this area allow for better perception of contrasts, as they rely more on the functioning of the remaining cone types (usually blue cones in this case). Therefore, 490 nm stands as the peak of their color discrimination abilities, as it is the area where they can still perceive color differences most effectively.