The main function of the eye is to convert light into electrochemical impulses that the brain can interpret as visual images. The various parts of the eye perform different functions that contribute to this purpose.
The eye is roughly analogous to a self-regulating, self-cleaning camera. The lens of the eye bends and refracts light, directing it toward the retina. The iris contracts or dilates to control the amount of light entering the eye. The cornea provides a clear shell that protects the eye without interfering with vision. The tear ducts and the eyelids work together to lubricate the eye and to wash away dust and other particles that might irritate or damage the eye.