Have you ever been on a long road trip with your family? It can be exciting to stop at interesting places along the way, but the hours spent on the highway between stops can become tedious.
Many children play games with their friends and family to pass the time. Have you ever played a game called “License Plate Bingo”? The goal is to spot as many different state license plates as possible during the journey.
Alternatively, you might prefer playing “I Spy.” One person says, “I spy with my little eye…something red!” and the others have to guess whether they are referring to a stop sign, a fire truck, a red Corvette, or something else entirely.
Playing “I Spy” makes you appreciate how incredible your eyes are. They can scan in all directions, quickly focusing on objects both near and far. They work tirelessly, allowing you to experience the world from the moment you wake up until you go to sleep.
But how exactly do our eyes enable us to see? What roles do the different parts of the eye play? And how do they perform tasks that even the most advanced cameras cannot?
Human vision is all about light. This may seem obvious, as it is nearly impossible to see in the dark. However, it is the light reflecting off objects and entering our eyes that allows us to see them.
When light reflects off an object in our field of vision and enters the eye, it first passes through a thin layer of tears that cover the eye’s clear outer layer, known as the cornea. The cornea helps to focus the light as it enters the eye.
Behind the cornea is a liquid called the aqueous humor, which maintains the proper pressure inside the eye. After passing through the aqueous humor, the light enters the pupil, the round opening in the colored part of our eye known as the iris.
The iris adjusts the size of the pupil to control the amount of light entering the eye. In the dark, the iris makes the pupil larger to allow more light in for better visibility. In bright light, the iris makes the pupil smaller to reduce the amount of light entering and protect the eye from damage.
Once the light passes through the pupil, it travels through the lens. The lens focuses the light onto the retina, which is located at the back of the eye. The retina can be compared to a movie theater screen or a camera film.
Ligaments inside the eye adjust the shape of the lens to ensure that the light is properly focused on the retina. However, some people may need additional assistance for their eyes. This is why some individuals wear glasses, which help to bend light so that it is perfectly focused on the retina.
When light reaches the retina, it activates photoreceptor cells called rods and cones. These specialized nerve cells convert light into electrochemical signals, which then travel along the optic nerve to the brain.
The image that the brain receives from the eyes is actually upside-down. However, as the brain processes the image, it turns it around so that we perceive objects as they truly are.
Although the process may appear simple, the coordination of all the different components of the eye, including the optic nerve and the brain, requires numerous adjustments that occur in milliseconds as we look around.
If you consider everything that is happening when you look at something as small as a human hair and then gaze into the sky at something as large and distant as the Moon, you will realize the incredible nature of your eyes!
Give it a Try
Are you prepared to DISCOVER what else you can learn about your eyes? Enlist the help of a friend or family member to explore the following activities:
- Do you have any idea how remarkable your eyes are? Expand your knowledge by visiting National Geographic to explore Your Amazing Eyes! Take note of at least three interesting facts that you learn and share them with a friend or family member.
- Have you ever pondered what it would be like if you were unable to see? How would your life differ? Use a bandana to create a blindfold and wear it around the house for a few minutes. What do you believe you would miss the most about not being able to see? Discuss your thoughts with a friend or family member.
- We are accustomed to having our eyes open for most of the day. However, you can have fun and learn fascinating things even with your eyes closed. Take a look at Top 10 Things To Do with Your Eyes Closed to try out various activities that will teach you more about your incredible eyes!
Sources of Wonder
- http://www.sciencemadesimple.co.uk/curriculum-blogs/biology-blogs/how-do-our-eyes-work
- http://www.webmd.com/eye-health/amazing-human-eye
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