How does the eye work?

Once the wonder of a beautiful landscape has faded, have you ever had the thought of how amazing it is that we are able to see? Has that ever led you to ask how our eyes even work? It’s a pretty incredible process that has multiple fields of medical study focused on it! 

When you look at something, you don’t actually see the object, rather you “see” the light that reflects off these objects. White light contains every possible color of light and different objects absorb and reflect different colors of that light. When the reflected light hits our eyes, it passes through our cornea, the clear front layer of the eye, which concentrates that light onto our pupil. Our iris, the colorful part of our eyes, can expand and contract the pupil to let the perfect amount of light enter the eyes. Next, the light passes through our lens, which directs the light to the retina located at the back of the eyeball.

The retina contains millions of light sensitive cells that convert light signals to electrical signals and deliver those to our brain. The picture that is put on our retina is actually upside down and our brain is trained to flip it the right way! There are two main categories of sensors in our retina, rods and cones. Rods help our night vision and the cones are what let us see in color. The earliest eyes didn’t have these fancy sensors and were mostly used by microscopic life looking for sunlight to convert into energy. Without those rods and cones, they couldn’t see the vibrant colors of fruit or meat that humans and other animals relied on to find safe food to eat.

Hopefully this short explanation shows why even Charles Darwin thought the eye was an incredible and barely believable organ. Be sure to take care of these gifts by eating a healthy diet and taking breaks during extended screen time. If you want to know more about how the eyes work, the study of optometry focuses on the mechanisms of the eyes. 

By Dr. Yanyu Wu