Human eye decorated with cosmetics

Light from a single point of a distant object and light from a single point of a near object being brought to a focus

The eye of a hawk

The eye is a round organ for sensing light so organisms can see. It is the first part of the visual system. About 97 percent of animal species have eyes. Image-resolving eyes are present in cnidaria, molluscs, vertebrates,annelids and arthropods.

In mammals, two kinds of cells, rods and cones, allow sight by sending signals through the optic nerve to the brain.

Some animals can see light that humans cannot see. They can see ultraviolet or infrared light.