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Prepare your eyes for the solar eclipse

From Spectrum Health Beat • Aug 19, 2017 at 12:00 PM

Looking forward to a once-in-a-lifetime chance to see a total solar eclipse without having to travel far?

So are millions of other people.

Don’t understand what the hubbub is all about? Well, a solar eclipse is when our planet, moon and sun align in such a way that the moon blocks out a portion of the sun from a vantage point on Earth. Sometimes the sun is completely hidden by the moon. and that’s called a total solar eclipse. 

On Monday, Aug. 21, for the first time in 40 years, there will be a total eclipse visible in the continental United States.

But before you get caught up in the frenzy, make plans to protect your eyes for years to come.

“Most often, common sense causes people to look away from the bright sun,” said Dr. Brooke Geddie, pedatric ophthalmology section chief for Spectrum Health Helen DeVos Children’s Hospital in Grand Rapids. “However, in the amazement of visualizing a solar eclipse, we can forget to look away.”

With this in mind, Geddie shares five simple do’s and don’ts:

1. Do make plans in advance (now is good).

So, as you may have heard, hotels and campgrounds are nearly booked in the 70-mile-wide swath of the United States that will see a total solar eclipse. Areas north and south of this path, which swings down from Oregon to South Carolina, will see varying degrees of a partial solar eclipse. The closer you are to the path, the more sun will be covered by the moon during the eclipse.

No matter where you are viewing the eclipse, eye protection is a must. And the time to purchase that protection is now.

“Observing the sun can be hazardous to your vision if the proper precautions are not taken,” Geddie said, adding that there will only be a few minutes of the total solar eclipse (when the sun is completely covered by the moon, about 2 minutes, 40 seconds this year — depending on your exact location) for those in the path of totality, and this is not the harmful phase.

“But as soon as a small sliver of the sun begins to appear, the risk of harm to the eyes begins,” the doctor said. “The solar radiation from the sun has been known to damage the cornea, accelerate the development of cataracts — but the largest risk is to the retina, the inner layer of the eye.”

Exposure to intense light causes damage to the light-sensitive rod and cone cells of the retina, essentially creating a hole in the retina, which can lead to temporary or permanent loss of vision dependent on the severity of the solar injury.

2. Do wear proper eye protection.

If you look at the solar eclipse, you must use proper eye protection.

Glasses with a special filter, ISO12312-2, are required to safely view the uneclipsed or partially eclipsed sun. Ordinary sunglasses, even very dark sunglasses, are not safe for looking at the sun.

“Even when 99 percent of the sun’s surface is obscured during the partial phases of the solar eclipse, the visualized crescent of sunlight is still intense enough to cause retinal injury,” Geddie said.

For information regarding protective eyewear or handheld filters to experience the eclipse, refer to the American Astronomical Society.

3. Don’t remove your glasses or filter while still looking at the sun.

As recommended by the American Academy of Ophthalmology, before looking up at the sun, cover your eyes with your eclipse glasses.

After glancing at the partially eclipsed or uneclipsed sun, turn away to remove your filter. Do not remove it while looking at the sun.

The only time you can look at the sun without the special solar filter is during a total eclipse.

“When the moon completely covers the sun (and it is suddenly very dark), you can remove your solar filtered glasses to watch,” Geddie said. “Then, as soon as the bright sun begins to reappear slightly, use your solar glasses again to watch the remaining partial phase of the eclipse experience.”

4. Do supervise children during the eclipse.

“Very close adult supervision is recommended if children will be viewing the eclipse to assure they keep the eclipse glasses on,” Geddie said.

There are also ways to create a projected image of the partial solar eclipse onto a piece of paper to safely, indirectly experience the eclipse. This is particularly helpful for children who might be tempted to take off their glasses or look directly at the sun.

And although it probably doesn’t replace the personal viewing experience, the event can be viewed live on NASA’s website.

5. Don’t view the eclipse with devices unless you have an extra filter.

If you’re viewing the eclipse with anything but your eyeballs, make sure to go the distance and get another filter.

“Many people like to visualize the eclipse via a telescope, and without a special filter for protection, this can cause an immediate retinal injury because of the high irradiance level in the magnified image,” Geddie said.

If you plan to use a camera, telescope or binoculars, you need a special solar filter on the front of these devices.

“This is important as, even if you are wearing the special filtered eclipse glasses, the intense solar rays coming through these magnifying devices can damage your glasses and then your eyes,” Geddie said.

If you would like to use a camera, telescope or binoculars, consult with an expert astronomer.

This article first appeared on spectrumhealthbeat.org.

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