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The Conversation

  • Written by Jason Yosar, Associate Lecturer, School of Medicine, The University of Queensland

This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!

How do glasses help you see? – Andy, age 5, Vincentia.

Hi Andy, and thank you for your question about glasses.

You’ve asked this at a very good time because more and more people are needing to wear glasses, including young children, and we don’t really know why.

Our eyes let us see because light enters each eye, and the eye then creates a message that goes to the brain.

The eyeball itself doesn’t actually “see” – the brain sees. The eyeballs just take pictures, like two little cameras. To see properly, each eyeball needs to send the light that enters it onto a very exact spot inside the eyeball, called the retina. If the light falls onto the wrong place, your vision will be blurry.

Curious Kids: How do glasses help you see? Both shortsighted and farsighted people need glasses to help them see clearly. Wikimedia Commons/Hackfish, CC BY

Many people don’t need glasses and can see just fine. This is because their eyeballs are focusing light properly onto the retina.

However, some people have eyeballs that are too long. They are called “shortsighted”. For these people, things far away, like street signs or the classroom blackboard, can look blurry.

Other people have eyeballs that are too short. They are called “farsighted” and things close to them, like a book or a mobile phone, can look blurry.

Read more: Curious Kids: Why is the sky blue and where does it start?

Both shortsighted and farsighted people need glasses to help them see clearly.

They work by helping the eyeball to focus light onto the correct place, the retina. Only then can the eye see clearly.

Curious Kids: How do glasses help you see? They work by helping the eyeball to focus light onto the correct place, the retina. Marcella Cheng/The Conversation, CC BY-NC-ND

Maybe you have a grandma or grandpa who wears glasses whenever they are reading books or using their mobile phone. When people get older, they usually become a little bit farsighted because a part of their eye called the lens becomes stiff and doesn’t work properly.

Curious Kids: How do glasses help you see? More and more people, including young children, are needing to wear glasses. Flickr/Ryan McDonough, CC BY

More and more young people in the world are needing to wear glasses.

We’re not sure why, but some scientists think that children who spend too much time inside are more likely to need glasses. We don’t know if it’s because they aren’t getting enough sunlight or if they’re simply reading too much or playing too many video games when they get home.

Most children in China are shortsighted and need glasses to see things far away. The Chinese government is so worried about this that they are making sure all students spend some time outdoors instead of just being inside the classroom.

Read more: We can prevent an epidemic of short-sighted kids with more time outdoors

Glasses can cost lots of money, and children who need glasses but don’t wear them don’t do as well in school. Once you need glasses, you usually need them forever - your eyes won’t go back to normal on their own.

I hope that one day we can find out why people’s eyeballs become too long or too short and then we can stop people needing to wear glasses in the first place. Then people will never lose or forget their glasses ever again!

Curious Kids: How do glasses help you see? When people become older, they usually become a little bit farsighted because a part of their eye called the lens becomes stiff and doesn’t work properly. Marcella Cheng/The Conversation, CC BY-NC-ND

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. You can:

* Email your question to curiouskids@theconversation.edu.au * Tell us on Twitter by tagging @ConversationEDU with the hashtag #curiouskids, or * Tell us on Facebook

Curious Kids: How do glasses help you see? CC BY-ND Please tell us your name, age and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.

Authors: Jason Yosar, Associate Lecturer, School of Medicine, The University of Queensland

Read more http://theconversation.com/curious-kids-how-do-glasses-help-you-see-84363

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