Retinol is a chemical used in the [[Human Eye]], specifically the [[Eye Rod Cell]] and [[Eye Cone Cell]] that is used to detect intensity of light. Retinol has a sensitivity to light of [[Wavelength|wavelengths]] from $400\pu{nm}$ to $700\pu{nm}$. The wavelength that retinol mostly absorbs though is $\color{green }\mathcal{green}$ light.