Which wavelength is the most desaturated for a patient with Protanopia?

The most desaturated wavelength for a patient with Protanopia occurs at 492 nm. Protanopia is a type of red color deficiency where individuals lack the long-wavelength sensitive cone photoreceptors, which are primarily responsible for detecting red hues. As a result, these individuals have difficulty perceiving colors in the red to green spectrum.

At around 492 nm, which falls within the blue-green region of the visible spectrum, colors appear less saturated to individuals with Protanopia because they have a diminished ability to distinguish colors that rely heavily on red light. This wavelength tends to register as a more neutral color, lacking the intensity or vibrancy that individuals with normal color vision experience.

In contrast, wavelengths such as those around 570 nm and 450 nm would typically showcase more pronounced saturation levels, particularly in hues perceived as yellowish-green and blue respectively. Thus, 492 nm stands out as the point where desaturation occurs for someone with Protanopia, making this answer the most appropriate given the characteristics of the condition.