Scientists Say: Myopia | Science News for Students

Scientists Say: Myopia

This is the scientific term for nearsightedness, in which people have trouble seeing distant objects
Jun 3, 2019 — 6:30 am EST
a smiling kid wearing glasses standing outside in front of a lake

People sometimes have to wear glasses because they have myopia — a condition where distant objects appear fuzzy.

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Myopia (noun, “My-OH-pee-ah”)

This term describes a condition called nearsightedness — when someone has trouble seeing objects that are far away. Usually, someone with myopia can read a book or smartphone without trouble. But they might view objects even an arm’s length away as fuzzy and out of focus.

When light enters the eye, it passes through the outer layers — the cornea — and then through a lens. The lens focuses the light to a point on the back of the eyeball in an area called the retina.  There, nerve cells process the information and pass it on to the brain.

When the eyeball is a perfect sphere, the light becomes focused on just a small point on the retina. That produces perfect vision. But if the eyeball is slightly too long from front to back, the light will focus to a point before it hits the retina. Then, the light spreads out again. The more the light spreads out before it hits the retina, the fuzzier the image will appear to the viewer. A too-thick cornea will also make the light focus too early. Both of these changes can produce myopia.

Glasses and contact lenses can help people with myopia. These objects help focus light when the eyes aren’t quite up to the job.

a diagram showing how light is focused in a normal eye and a myopic eye
The eye on the left is a perfect sphere. When light enters, it focuses, or narrows, to a point on the retina at the back of the eye. This produces normal vision. The eye on the right is slightly elongated. When light enters, it focuses in front of the retina, then it spreads out again. This produces a fuzzy-looking image to the viewer. The person on the right would have myopia.
National Eye Institute/NIH/Flickr (CC-BY-2.0)

In a sentence

Spending time outdoors as a kid might help reduce the risk for myopia.

Check out the full list of Scientists Say.

Power Words

(more about Power Words)

cornea     The transparent front section of the eye. The shape of the cornea allows our eyes to bring objects at many distances into focus.

develop     To emerge or come into being, either naturally or through human intervention, such as by manufacturing. (in biology) To grow as an organism from conception through adulthood, often undergoing changes in chemistry, size and sometimes even shape. (as with towns) The conversion of wildland to host communities of people. This development can include the building of roads, homes, stores, schools and more. Usually, trees and grasslands are cut down and replaced with structures or landscaped yards and parks.

focus  A point at which rays (of light or heat for example), converge to. (In vision) The quality of producing a clear image.     

lens     (in biology) A transparent part of the eye behind the colored iris that focuses incoming light onto the light-absorbing membrane at the back of the eyeball. (in physics) A transparent material that can either focus or spread out parallel rays of light as they pass through it. (in optics) A curved piece of transparent material (such as glass) that bends incoming light in such a way as to focus it at a particular point in space. Or something, such as gravity, that can mimic some of the light bending attributes of a physical lens.

myopia     The medical term for nearsightedness. An inability to focus on anything much more than an arm’s length away.

nearsighted    An inability to focus anything that isn’t nearby. It’s due to an elongation of the eyeball. Many factors can contribute to this inappropriate elongation, and so the cause of nearsightedness is still under debate.

point     (in mathematics) A precise point in space that is so small that it has no size. It merely has an address.

retina     A layer at the back of the eyeball containing cells that are sensitive to light and that trigger nerve impulses that travel along the optic nerve to the brain, where a visual image is formed.

risk     The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. (For instance: Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.)

smartphone     A cell (or mobile) phone that can perform a host of functions, including search for information on the internet.