Which type of color deficiency has poor color discrimination at wavelengths around 495 nm?

The type of color deficiency characterized by poor color discrimination at wavelengths around 495 nm is known as tritanopia. Tritanopes have difficulty distinguishing colors in the blue-yellow spectrum due to a lack of functioning S-cones (short-wavelength cones) responsible for detecting blue light. This is specifically where discrimination at the 495 nm wavelength falls, which is closer to the blue region of the visible spectrum.

Tritanopia leads to a confusion of blue shades with green and yellow, impacting the perception of colors that involve these wavelengths. The S-cones are less sensitive in tritanopes, which contributes to their challenges in color discrimination. In contrast, protanopes and deuteranopes primarily have issues with the red-green spectrum, which is noticeably different from the blue-yellow challenges faced by tritanopes. Therefore, the correct answer firmly aligns with the characteristics of tritanopia in terms of wavelength sensitivity.