Eye Anatomy – how the eye works

Let’s explore the eye and get a closer look at how the anatomy of the eye allows us to see.

Eye anatomy - how the eye worksAbout the eye and vision.

Vision is one of our most important senses. The eye’s main function is to detect light patterns and partner with the brain to translate light into images that we see and perceive.

The eye is a complex optical system – very similar to a camera. Much like a camera lens, the lens in the eye focuses light onto the retina, at the back of the eye. The retina functions as the film in the eye’s camera, capturing incoming light rays from objects and sending them to the brain to be developed as an image.

Let’s explore the eye’s “lens” and “film” and get a closer look at the structures in between that allow us to see.

The process of vision begins when light rays bounce off an object and enter the eye through the cornea, the clear, dome-shaped front window of the eye. Similar to a lens on a camera, the cornea is a powerful refractive surface responsible for about 70% of the eye’s focusing power. It is the cornea that enables us to see clearly.

After traveling through the clear cornea, the light rays reach the iris and pupil. The iris is that distinctively colored part of your eye that you see in the mirror. The pupil is the small opening in the center of the iris that acts like an aperture in a camera. As muscles in the iris relax and constrict, the pupil changes size to adjust the amount of light entering the eye. The more light your eye is exposed to, the smaller the pupil gets. If there is low light, the pupil enlarges to allow more light in.

After passing through the pupil opening, the light rays reach the lens. This transparent, flexible structure uses tiny muscles and fibers to change its shape and thickness, allowing the eye to converge the light rays. This refractive power gives us the ability to change our focus from objects close to us, to far away in the distance, then back again.

After the light rays exit the back side of the lens, they proceed through a clear gel-like substance in the center of the eye called the vitreous humor. The vitreous helps the eye maintain its spherical form and shape.

Finally, the light rays converge to a focal point on the retina’s surface. The retina is the part of the eye similar to film in a camera. It is a very light-sensitive and complex tissue, wallpapering most of the inner wall of the eyeball. It is filled with hundreds of millions of receptor cells that capture the light rays, convert them into electrical impulses and transmit them through an intricate system of nerve fibers to the optic nerve.

These electrical impulses then travel along the optic nerve to the brain, where they are interpreted as the images we see.

Mark Erickson

Working as an Ophthalmic Photographer since 1988, Mark Erickson has examined and photographed virtually every type of eye condition there is through various high-powered microscopes and cameras. This experience has given him a unique and intimate understanding of the eye and its various anatomical structures, diseases and surgical procedures. In 1998, Mark started coupling this medical photography experience with his artistic and creative abilities. The result is a vast gallery of various eye anatomy, eye conditions & diseases and surgical illustrations. Mark’s work has been published on the front cover of numerous, top eye care industry magazines and books. His work frequently illustrates the front cover of industry journals. Mark’s work has been commissioned by National Geographic, Bausch & Lomb, Johnson & Johnson and Transition Lenses, to name a few. Mark Erickson’s artwork and story were published in The National Association of Photoshop Professionals monthly publication, “Photoshop User” and “Layers” magazines. Mark now focuses his creative energy on his website, JirehDesign.com, and creating and licensing stock and custom ophthalmic illustrations and animations for use in pharmaceutical marketing, legal cases, product marketing, websites and patient education materials.