Tritanopes are missing which photopigment?

Tritanopes are individuals who lack the blue photopigment known as cyanolabe. This absence leads to difficulties in perceiving blue light and can affect color discrimination, especially distinguishing between colors that involve blue hues. The condition is a type of color vision deficiency where the S-cones, which are most sensitive to short wavelengths (blue light), are absent or non-functional. This creates a gap in the visual spectrum that is typically covered by cyanolabe.

In contrast, erythrolabe (red-sensitive pigment) and chlorolabe (green-sensitive pigment) are associated with different types of color vision deficiencies, such as protanopia and deuteranopia, which involve red and green perceptions, respectively. Melanopsin, on the other hand, is not a photopigment used for color vision but is involved in circadian rhythms and non-image-forming visual functions. Therefore, the correct answer, focusing on the deficiency specific to tritanopes, is indeed cyanolabe.