Eye Care > Common Terms > Parts of the eye

Parts of the eye

The eye is one of the most complex organs in the human body. It works through the combined functions of many, interconnected parts. Some of the more common terms your eyecare professional will refer to are defined on this page.

Cones

Cones are light-sensitive receptors in your retina that help you see color.

Cornea

The clear part of the eye covering the iris and pupil; it lets light into the eye, permitting sight.

Iris

This is the diaphragm that controls the size of your pupil. It is the blue part of blue eyes, the green in green eyes, etc. The iris helps regulate how much light enters your eye by controlling the size of your pupil.

Lens

The nearly spherical body in the eye, located behind the iris (or pupil), that focuses light rays onto the retina.

Optic nerve

The optic nerve is the part of the eye that carries stimuli from the eye’s rods and cones to the brain.

Pupil

This is the dark, round center of the eye. It opens and closes to regulate the amount of light the retina receives.

Retina

The retina is the nerve layer that lines the eye. It receives images formed by the lens and then converts them into signals that reach the brain using the optic nerve.

Rods

Rods are light-sensitive receptors in your retina that help you see in low light.