Vision neophyte? Here, we break down the eye and its incredible functions so you have the backstory in sight

new to eyecare? If you’re delving into dispensing for the first time, you’re likely learning more about eyewear than vision’s big enchilada—the eyeball.

To give you some insight (pun intended), here’s an easy-to-decipher diagram of the eyeball, plus the Cliffs Notes version of what each of its parts do.

CORNEA: Like a window, this clear, transparent front covering admits light, begins the refractive process, and keeps foreign particles out.

IRIS: Picture this! This flat, colored part of the eye divides the eye’s anterior chamber (front) from its posterior chamber (back) and controls light levels much like the aperture on a camera.

THE CILIARY BODY: A circular band of connected muscle that sits immediately behind the iris, the ciliary body does double duty. It controls the lens and produces aqueous humor…and that’s no joke.

AQUEOUS HUMOR: A thin, transparent fluid that nourishes vascular tissues like the cornea (produced by the ciliary body).

CHOROID: A real multitasker, the choroid’s biggest job is as a vascular structure supplying the outer retina.

SUSPENSORY LIGAMENT: Serving as the eye’s hammock, the suspensory ligament is a series of fibers that connect the ciliary body with the lens, holding it in place.

PUPIL: The black circular opening in the center of the iris that lets in light, the pupil has an adjustable opening. Light projects through the pupil, controlling the intensity of light allowed to strike the lens.

SCLERA: The white of the eye—or a white sac, to be more precise. The sclera provides strength, structure, and protection for the eye. It also attaches to the optic nerve.

LENS: Right behind the iris and pupil, the lens helps focus light on the back of the eye. In a constant state of adjustment, it allows you to see small details. Any presbyope can tell you what happens when it loses elasticity.

RETINA: The area at the back of the eye, the retina receives the refined, visual message from the front of the eye and uses electrical signals to transmit it along the optic nerve to the brain.

FOVEA: A small depression in the retina where visual acuity is highest.

CENTRAL RETINAL ARTERY + VEIN: The eye’s delivery services, they carry blood to and from the retina.

OPTIC DISC + NERVE: The optic disc is called the blind spot, because there are no receptors in this part of the retina. This is where all axons of the ganglion cells leave the retina to form the optic nerve. The eye’s carrier pigeon, the optic nerve carries impulses converted in the retina to the brain.

—Stephanie K. De Long

Special thanks to VSP, Vision Eye Institute, Web MD, and the National Keratoconus Foundation for sharing their “insights” for this article.