Scotopic vision Scotopic vision Scotopic vision is the vision of the eye under low-light levels. The term comes from Greek "skotos", meaning "darkness", and "-opia", meaning "a condition of sight". In the human eye, cone cells are nonfunctional in low visible light. Scotopic vision is produced exclusively through rod cells, which are most sensitive to wavelengths of around 498 nm (green–blue) and are insensitive to wavelengths longer than about 640 nm (red). This condition is called the Purkinje effect. Scotopic vision is dominated by retina amacrine cells, specifically AII-amacrine cells. AII-amacrine cells capture rod bipolar cell input and redistribute it to cone
Color is based upon the varying sensitivity of different cells in the retina to light of different wavelengths. Humans are trichromatic—the retina contains three types of color receptor cells, or cones. One type, relatively distinct from the other two, is most responsive to light that is perceived as blue or blue-violet, with wavelengths around 450 nm; cones of this type are sometimes called "short-wavelength cones", "S cones", or "blue cones". The other two types are closely related genetically and chemically: "middle-wavelength cones", "M cones", or "green cones" are most sensitive to light perceived as green, with wavelengths around 540 nm, while