Today’s Wonder of the Day was inspired by Kittykat2314 from gainseville, GA. Kittykat2314 Wonders, “I wonder why do people have glasses?” Thanks for WONDERing with us, Kittykat2314!
Have you ever had an eye exam? If so, what do you remember about it? Your doctor probably asked you a lot of questions about your ability to see. They may have told you to cover one eye at a time and read letters from a special eye chart.
Eye charts usually contain several rows of letters. The top row begins with very large letters. They get smaller and smaller as you near the bottom of the chart.
What does identifying your ABCs have to do with eyeglasses? Each line of the chart has been assigned a number. During the test, patients read each line of the chart until the letters become too small to read easily.
If you can read line 20 from a distance of 20 feet, this means you have 20/20 vision. Doctors consider this normal vision with no need for glasses. In some cases, people can only see the giant letter at the top of the chart. That means they have 20/200 vision. People with 20/200 vision are considered legally blind.
There are many different medical reasons people wear glasses. The simple answer is that glasses help people see better. Some people wear glasses for reading things that are far away or for driving. Other people only wear glasses when they’re doing an up-close activity, like reading, writing, or knitting. Some people wear glasses all the time.
People who have difficulty seeing objects that are far away have myopia, or “nearsightedness.” This means they can easily see objects that are close to them. When viewing objects in the distance, though, they have more difficulty. The image can appear fuzzy. Nearsightedness occurs when the physical length of the eye is longer than the optical length. That means the visual image is focused in front of the retina, rather than directly on it.
People who have difficulty reading and seeing things close-up have hyperopia. This is also called “farsightedness.” It occurs when the visual image is focused behind the retina. It may be caused by weak focusing power or the eyeball being too small. Another condition that can cause people to need glasses is “astigmatism.” This occurs when part of the eye is irregularly shaped.
People with myopia, hyperopia, or astigmatism can use eyeglasses or contact lenses to see better. How do eyeglasses and contact lenses work? They use convex or concave lenses to bend the light entering the eye. This refocuses the eye, helping to correct vision problems.
Do you wear glasses? Do you have a friend or family member who does? Experts estimate that about 75 percent of people wear glasses or contact lenses as adults. They’re very common! When was the last time you had your eyes checked? Talk with a family member about your vision health today.
Standards: NGSS.LS1.A, CCRA.L.3, CCRA.L.6, CCRA.R.1, CCRA.R.2, CCRA.R.4, CCRA.R.10, CCRA.SL.1