The American Foundation for the Blind describes eyes as structures that gather, focus and transmit light to the brain, so the information can be deciphered into an image. The human eye is frequently compared to a camera, which functions similarly.
The Merck Manual Home Health Handbook lists the cornea, pupil, iris, lens, retina and optic nerve as the primary structures of the eye. Light enters the eye through the cornea, which serves as a protective layer for the eye's inner structures and aids in light focusing. The pupil is a black dot in the center of the eye; it is surrounded by the iris, which constricts and dilates the size of the pupil. The iris functions like the aperture on a camera, regulating the amount of light that enters the pupil.
According to The Merck Manual Home Health Handbook, the lens sits directly behind the pupil. It focuses light onto the retina by altering its shape. The lens thickens and thins, bending light at the correct angles to create the clearest image. The retina is a surface at the back of the eye that is covered in photoreceptors that sense different types and wavelengths of light. Photoreceptors convert information into electric impulses that are fed to the brain via the optic nerve. Once at the brain, these impulses are processed and decoded into an image.