Eye Anatomy – how the eye works

About 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.