The Inner Workings of Your Eye

CORNEA

Sight begins here: Light bounces off whatever you’re looking at and enters this transparent tissue on the orb’s surface, and the cornea bends the light to make the image clearer.

IRIS

The colored part of the eye (surrounded by the bright white sclera) doesn’t just look beautiful—it’s in charge of changing the size of the pupil.

PUPIL

This opening in the iris’s center widens to welcome light when it’s dark and narrows to restrict light when there’s too much, letting us see objects both in daytime and at dusk.

LENS

The light bends even more once it hits the lens, which is situated behind the iris.This structure controls focus, letting us take in, say, a field of flowers from far away or a single blossom up close.

VITREOUS HUMOR

Taking up most of the space between the back of the lens and the retina, this clear gel helps keep the eye rounded and nourished.

RETINA

The light that comes in via the cornea and through the lens winds up at this tissue in the back. Here, photoreceptor cells (including rods and cones) transform light into electrical pulses. The tiny area in the center of the retina called the macula is responsible for our central vision, giving us the ability to see what’s directly in front of us.

OPTIC NERVE

The electrical signals travel through the million-plus fibers of this nerve to enter the brain, which identifies the pulses as whatever object we’re viewing.