The eye has many functions. Unless an organism lives in total darkness, the eye has its use. In broad categories, it can either distinguish: light & dark, shape, colour, brightness and distance or can do all of the above.

• nervous response ---a brief introduction to the terms used in explaining about the nervous system

The following is what people mean when they talk about the physiology of the mammalian eye:

• Light perception and adaptation --- the involvement of photopigments in vision
• Image formation --- our interpretation of the sensation of light
• Accommodation --- how the eye see objects at different distances from us
• Colour vision --- recognition of different colours
• Light intensity control --- pupil reflex controlling the amount of light entry into eye
• Binocular & Stereoscopic vision --- how we can see 3D