How Does Vision Work

Eyesight 101 – Get to know your eyes.

The human eye and a camera work in similar ways. A camera allows light in through an aperture, focuses an image with a lens which then projects and records an image on film located at the rear of the camera. Your eye works basically the same way. Rather than film, at the back of the eye is the retina onto which the image is projected. From there the image is conveyed via the optic nerve to the brain which interprets the image by shape, color and dimension. If the proper amount of light enters the eye, the image perceived will strike the retina, resulting in normal vision. If, however, light entering the eye does not focus on the retina, the result is distorted vision.

Sclera

The largest, opaque, white part of the outer layer of the eyeball which provides shape and protection.

Cornea

How the Eye Works The transparent dome on the front of the eyeball. About the size of a dime, its shape and curvature affect the eye’s focusing ability.
The cornea has five distinct layers:
Epithelium – outer protective layer that continually renews itself
Bowman’s Membrane
Stroma – strongest, thickest fibrous layer of the cornea that gives it shape
Descemet’s Membrane
Endothelium – single cell, inside lining of the cornea, regulates cornea’s fluid content

Iris

Colored portion of the eye behind the cornea made of connective tissue and muscle that controls the amount of light that passes through to the retina.

Pupil

The opening of the eye that appears as the eye’s center black circle and serves much like a camera shutter. In bright light the muscles of the iris make the pupil constrict so that only a small amount of light can enter the eye. In dim light, the iris relaxes and the pupil dilates to allow in more light.

Lens

The lens is located behind the pupil and fine-tunes the angle of light passing through the cornea to the retina.

Vitreous Humor

This clear gel-like substance fills the space in the eye between the lens and the retina.

Retina

Lining the inner back wall of the eyeball, the retina’s layers of nerve tissue “captures” images as viewed through the eye, creating an electrochemical reaction that creates impulses that are transmitted via the optic nerve to the brain, which interprets the image.