How do our eyes work?

 

Our eyes are pretty amazing parts of our body. They let us see things by collecting energy from the world around us. That energy is light! Everything that we can see, we see because it either gives off light, like the Sun or a lamp, or because light bounces off of it, like a mirror, or a tree, or a person!  

Light enters our eyeballs through the round black part, which is called the "pupil." The colorful circle around the pupil is called the “iris,” and that controls how much light is let in by making your pupil bigger or smaller. Since too much light can actually hurt our eyes, our irises will make our pupils shrink up to tiny dots on bright, sunny days!

After the pupil, light goes through a special part of your eye called the "lens." It's just like the lens of a camera or telescope! The lens focuses the light onto the back of the eyeball. This part is called the "retina." The retina has a lot of special nerve cells which sense the light and carry signals to the brain to let us know what we're seeing! 

 

You might not be aware of it, but everyone has a certain point in their vision where they are unable to see! It's called a blind spot. You might not notice it because your brain likes to guess what's in the missing space.

Each eye has a blind spot because there is an area on the retina (the back of your eyeball) that is covered by the nerve that sends the signals to your brain. The nerve is actually getting in the way of the very thing it's trying to sense! 

If you want to see where your blind spot is, all you need is a blank sheet of paper, a ruler and a marker. Draw an X on the paper and about six inches to the right of it, draw an O, not too big, about the size of a dime. Now cover your left eye and look at the X with your right eye. Hold the paper close to your face and slowly pull it away. Eventually you'll reach a point where the O seems to disappear! That's your blind spot. You'll be able to find it with your other eye too! Pretty weird, right?!

If you have trouble finding your blind spot, try extra hard to focus only on the X. If you try to focus on the O at all, it won’t disappear in your blind spot!