The wavelength of light that human eyes can sense is primarily determined by the photoreceptor cells in the retina called cones. Cones are responsible for color vision and are sensitive to different ranges of wavelengths.
In humans, there are three types of cones, each with a peak sensitivity to a particular range of wavelengths. These cones are often referred to as "red," "green," and "blue" cones, although their sensitivity ranges extend beyond just those colors.
The "red" cones have peak sensitivity to longer wavelengths, around 564–580 nanometers (nm). The "green" cones are most sensitive to medium wavelengths, around 534–545 nm. Finally, the "blue" cones have peak sensitivity to shorter wavelengths, around 420–440 nm.
These three types of cones work together and their responses combine to give us the perception of a wide range of colors. By detecting the intensity of light across different wavelengths, our eyes can perceive the visible spectrum, which spans from approximately 380 nm (violet) to 700 nm (red).
It's important to note that the exact sensitivity ranges of cones can vary slightly among individuals, leading to differences in color perception and color blindness.