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.

How vision works | an animated guide to the human eye functions

The Eye and Vision – How vision works




How vision works in the human eye | an animationThe eye is a complex optical system – very similar to a camera.

Vision begins when light enters the eye through the cornea, a powerful focusing surface. The cornea is what gives us clear vision. From there, it travels through clear aqueous fluid, and passes through a small aperture in the iris called the pupil.

As muscles in the iris relax or constrict, the pupil changes size to adjust the amount of light entering the eye. Light rays are bent and focused through the lens, and proceed through a clear jelly-like substance in the center of the eye called vitreous humor, which helps give the eye form and shape. When light rays finally land on the retina, the part of the eye similar to film in a camera, they form an upside-down image. The retina converts the image into an electrical impulse that travels along the optic nerve to the brain, where it is interpreted as an upright image.



This animation above depicts the light rays’ path through the eyeball as they pass through the cornea, the eye’s lens and vitreous and striking the surface of the retina, the back inner “wallpaper” in the globe of the eyeball.

All of these structures of the eye mentioned here are critically important in the process of visual acuity. Any disease or condition that affects any of these eye components can cause vision decrease or loss, or even blindness.

Legal blindness is a very depressing and costly problem in the United States and the rest of the world. Low vision can lead to depression and decrease the ambulatory abilities of its victims. It is important to treat these secondary complications as well as the eye disease or conditions. Eye disease illustrations can be seen here.