Simulated examples of vision under low light. Top: human; bottom: cat In the study of human visual perception,<unk>  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.<unk>  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 (reddish orange). This condition is called the Purkinje effect.
Scotopic vision
Photopic vision
Mesopic vision
Monocular vision
Binocular vision
Retinal summation
Visual temporal integration
Underwater vision