A family wears special glasses to protect their eyes during an eclipse. (Ben Curtis/Associated Press)

Parents often warn kids about hurting their eyes. Some warnings are more myth than reality: Spending hours staring at a computer screen won’t ruin your eyes. Others are so obvious — “don’t run with scissors” — that they probably make you want to, well, roll your eyes.

Kids who plan to view the solar eclipse on August 21 are being urged to protect their eyes. It’s no myth that staring at the sun during an eclipse can damage your eyes, and it’s not exactly obvious why you shouldn’t do it.

Let’s consider how your eyes normally react to the sun.

Solar eclipses occur when the moon passes between the sun and Earth. (NASA/Reuters)

On a sunny day, if you were to look directly at the sun, you would know to look away after a split second because of the pain caused by the brightness. During most of a solar eclipse, the sun will be partly blocked by the moon, making it less bright. This tricks your eyes into being able to look at the sun for an extended period of time.

“You can stare at the sun during an eclipse for 10 minutes, and it doesn’t hurt. You can just look at it, and it’s really cool to look at it, but that whole time you’re literally burning the cells off your retina,” said Vike Vicente, a Washington pediatric ophthalmologist, which means an eye doctor for kids. “And once they’re burned, there’s no repair, there’s no fix for it.”

This condition caused by staring at the sun is known as solar retinopathy. The sun damages the retina, which is the part of your eye that transmits information to the brain. Long exposure to the sun without proper protection will cause scarring of the retina from burns and lead to partial, or even permanent, blindness.

An added risk during the eclipse is for those who try to look at the sun through binoculars, a camera or a telescope.

Using any of these tools can be dangerous because they can increase the damage done to your eyes by acting as a magnifying glass for the sun’s rays, speeding up the burning of your retinas.

If you want to snap a picture of the solar eclipse or look at it through binoculars or a telescope, you must use a specialized solar filter for your lens. The American Astronomical Society (AAS) has a list of recommendations at eclipse.aas.org/resources/solar-filters.

Those who want to look with their own eyes must wear eclipse glasses. The AAS site also offers a list of companies that make glasses that have been lab-tested to protect wearers from sun damage.

Binoculars are used to project an image of an eclipse onto a wall. (Miguel Riopa/Agence France-Presse/Getty Images)

Some eclipse watchers will get up to a few minutes to take off those glasses. If you’re in the path of totality — a 70-mile-wide band that stretches from Oregon to South Carolina — you will be able to look directly at the sun when the moon has completely covered the sun’s face. Once the sun’s face starts to reappear, the glasses must go back on.

The key at all times, eclipse day or not, is to be aware and to not look at the sun unless you are sure that you have taken the proper steps to protect your eyes.

Eclipse-watchers view a projected image of the sun. (Joshua Trujillo/AP)

Vicente wants to make sure that everyone knows the risks. But he figures that even with warnings, some who can see the eclipse will look at it with their bare eyes anyway.

“It happens,” he said. “And it breaks your heart.”