Let's "look" at the eye 👁️

00:00:01
Speaker 1: I'd like to say a special thank you to Shuma for this week's questions about the eye. I would also like to thank James, Jay, Stephen, Elsie, druva Ivy, and Jonah for sending in questions for our next episodes of sleep Tite Science. You're listening to sleep Tight Science. Did you know the human eye blinks between fifteen and twenty times a minute? What that means you blink up to one thousand, two hundred times per day and over ten point five million times a year.

00:01:10
Speaker 2: Wow, how do you see things?

00:01:23
Speaker 1: When you see something, you are really seeing the light that has bounced off of the object which has entered your eyes. Light enters our eyes through the small black part of our eye, or the pupil. The pupil can change size, which controls how much light gets it. The iris, which is the colored part around the pupil, is a muscle which helps the pupil to dilate or open or constrict close. If the light is too bright, the iris will help the pupil to constrict or close and let less light in. If the light is not bright enough, the iris will help the pupil to dilate or open up and let more light in. After the light has passed through the pupil and has entered our eye, it goes through some liquids or fluids until it reaches the retina at the back of our eye. The front part of our eye is curved, and this makes the light bend so the image appears upside down on the retina. The retina helps our brain by turning the light into a signal that the brain can recognize. The retina gets some help changing the light from the light sensitive rods and cones. The rods help us to see when it is dark, and the cones help with the color. After the rods and cones have helped the retina, the signal gets delivered to the brain by the optic nerve. The brain controls our eyes and helps us to move them to where we want to see and then to focus on the image.

00:03:32
Speaker 2: What happens when you read in dark places?

00:03:38
Speaker 1: That's an interesting question, Schuma. Lots of people believe that reading in dark places will make you need to wear glasses. Some scientists say this is a myth, while others believe that there is some truth to this, but not for the reasons that we think when we read in dark places our eyes need to adjust to the low level of light. The muscles around the iris relax and let the pupil open up to let more light in. The rods and cones that we talked about earlier take this extra light and turn it into information that the brain can use. When there is less light, the rods and cones need to work harder to make it possible for us to read the words. When reading in the dark, we will usually hold the book closer to our eyes as well. Both of these things low light and holding the book closer to see cause our eyes to work harder and they may get strained, or it could even cause a headache. Some scientists say that this may cause you to need to wear glasses later in life, but there is no definite proof.

00:05:37
Speaker 2: Or small electronic devices like smophones really bad for your eyes.

00:05:46
Speaker 1: I think a lot of people might like to hear the answer to this question, Schuma. Here is what I found out. There seem to be many things that can happen to our eyes from using small electronic devices too much or the wrong way. They're mostly bad, but can be balanced out and watched carefully. For example, some problems that show up when you use your device too much, are dry eyes and squinting because we don't blink as much as we should when we are using our devices. Blue light is another problem, especially for children, but it can easily be taken care of by regularly taking a break from the screen. Not going outside, but staying inside too much to use our device is another big problem. All of these problems with devices can be treated. Scientists believe that children's eyes, because they are still growing and developing, are more at risk or damage from blue light. So staring at the screen, not blinking, and holding the screen too close to our eyes makes a smartphone the worst choice of all the devices. So how can we help our eyes? You need to make sure that your screen is in a good position for your odds. The top of your screen should be at about eye level and about an arms distance away from you. You might also want to tip the screen slightly or check the brightness of the screen. Try to get rid of any glare from the lights around you. If you can use a bigger screen, maybe you should watch the show or play the game on the TV instead of on your smartphone. Most importantly is to take breaks and blink when you are looking at the screen. There is a rule that I read about called the twenty twenty twenty rule, which says take a twenty second break to look at objects twenty feet away every twenty minutes, and of course, go outside. I read many different times that spending too much time inside on our devices is bad. Take a break and get outside. Experts believe there is something about natural light that is good for our eyes. So today we learned that our eyes need to be taken care of. We spend a lot more time now looking at screens, and we need to remember to take breaks to take care of our eyes. Keep your screens at arm's length, and try using a bigger screen rather than a smaller one. Getting outside and looking around at things that are farther away helps keep our eyes healthy. It allows them to take a break from the squinting, the not blinking, and all the blue light of the screen. Fun facts about the eye. It is impossible to sneeze with your eyes open. Sailors once thought wearing a gold earring would improve their eyesight. People read about twenty five percent slower on a screen than a paper book. Hawks and eagles see about eight times better than humans. The human eye has about two million working parts to help us see. Our eye reaches its full size by about age twelve. The most common eye color is brown. Blind people can see dreams as long as they weren't born blind. In the right conditions and lighting, we can see the light of a candle from fourteen miles away. Thank you for listening to this episode of sleep Tight Science, where we investigate the questions you have about anything science related. Our podcast starts with a question like did you know, and throughout that episode we will try to answer the question. If you have a question or there is something you would like to know more about, send us your questions or comments at hello at sleep tightscience dot com. I look forward to hearing from you soon.