How your Eyes Work

Eye Anatomy: Eyes.com For an organ that’s only about an inch in diameter, the eye is incredibly complex. Some of the structures involved in making your eyes work include:

The cornea
The lens
The iris and pupil
The retina and macula
The optic nerve
The eye fluids – aqueous and vitreous humor

Let the Light in

Light enters the eye through the cornea, which acts like a transparent window. The pupil is the black circle in the middle of the colored iris and works like the aperture of a camera to open or close the size of the pupil. The iris controls the size of the pupil, which gets bigger or smaller to let in more or less light.

After light passes through the pupil, it is bent by the lens to focus on objects that are near or far, depending on your visual needs. Once light passes through the lens, it travels through the vitreous humor, a clear, gel-like substance that fills the middle of the eye. Light then hits the retina at the back of the eye, which can be compared to the film in a camera. This is where the picture is received based on the amount of light and focus from the front of the eye.

Perception, Color, and Image

The retina contains cells called rods and cones. Each has a different purpose and is based on a series of chemical reactions.

Rods – Function in less light than cones and are responsible for night vision
Cones – Function in brighter light and are responsible for color and detail

There are approximately 100 million rods and seven million cones in the retina. The central part of the retina, and the area where most of the cones are located, is about the size of a pencil eraser and is called the macula. The macula processes the details caught by the cones. It is this area that gives us central vision needed for activities like reading, driving, and working on the computer.

The optic nerve collects the images from the macula and sends them to the brain for further processing and to create one composite image in the brain’s vision center. This is done by converting the information from the retina and macula into electrical energy and then interpreting it as an image.

If you have questions about your vision or would like to consult with an experienced ophthalmologist in your area, please visit our Eye Doctor Directory.