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Planning to watch the total solar eclipse? Here's how to protect your eyes

Wearing their solar eclipse glasses, residents react as they gather at the Denver Museum of Nature and Science to observe the peak moment of the partial solar eclipse as it passes over City Park in east Denver on Monday, Aug. 21, 2017. While only a partial eclipse in Denver--92 percent--other parts of the intermountain West experienced a total eclipse. The last time a total eclipse crossed the entire continental United States was June 8, 1918. (AP Photo/David Zalubowski)
David Zalubowski
/
AP
Wearing their solar eclipse glasses, residents react as they gather at the Denver Museum of Nature and Science to observe the peak moment of the partial solar eclipse as it passes over City Park in east Denver on Monday, Aug. 21, 2017. While only a partial eclipse in Denver--92 percent--other parts of the intermountain West experienced a total eclipse. The last time a total eclipse crossed the entire continental United States was June 8, 1918. (AP Photo/David Zalubowski)

The total solar eclipse that will cross a swath of western and northern Maine on April 8 could be a feast for the eyes. But those eyes will need protection from damaging radiation that can cause long-term vision problems.

On a typical sunny day, we naturally avoid looking straight at the sun. It's just too bright. But during an eclipse, when the moon gradually obscures the sun, it's a lot more tempting to take a peek, said Edward Herrick-Gleason. He's the director of the Southworth Planetarium at the University of Southern Maine.

"When you have an eclipse, especially when you have a high obscuration, it won't be as painful to observe the eclipse," he said. "However, that energy will still be going into your retina. That's why you have to be very careful."

That energy beams down in the form of ultraviolet and infrared radiation that can cause damage to the retina, resulting in blurry vision and blind spots. Damage to the retina can happen within seconds, says Dr. Jessilin Quint, the president of the Maine Optometric Association. But she said you won't necessarily know right away. Symptoms usually appear hours, or even days later.

"And so most people, when they think about symptoms, they're thinking about pain or discomfort," she said. "And usually with a solar retinopathy, it's going to be more vision. So, blurry vision. Oftentimes, it's more of the center vision."

And vision problems can last from three to six months or even be permanent, Quint says. That's why it's important to protect your eyes. The best way to do that, she says, is to wear special eclipse glasses that block out both sun and ultraviolet light. And optometrists, astronomers, even community organizations are trying to spread the word.

Why the total solar eclipse is such a big deal

The Southern Aroostook Development Corporation produced this PSA for local radio stations.

"Before you look up, listen up! Regular sunglasses aren't enough. You've gotta use special glasses called solar viewing glasses. They're like magic shields for your eyes," a kid in the commercial said.

Solar eclipse glasses have flexible lenses made of black polymer infused with carbon particles. They're at least a thousand times darker than ordinary sunglasses and block nearly all visible light so all you should see is the sun, or say, a bare lightbulb. That also means that a camera lens, cell phone or telescope offers no protection, unless you use a special filter.

"There are solar filters for telescopes, you want to make sure it's at the end of the tube, you do not want to have that filter in the eyepiece itself, because that's where the light is focused. I would never trust a filter in an eyepiece," said Herrick-Gleason with the USM Planetarium.

He said there is one short period of time during an eclipse when it's safe to view the sun with the naked eye.

"If you are in a totality path, you may remove the glasses only during totality, provided that you will put them back on just before totality ends, you have to be very careful of that sliver of sun," he said.

It's critical to know the exact duration of totality in your location and to keep a watchful eye on the time. And, by the way, there's an app for that.

"That's why we went ahead and partnered with the Eclipse Company," said Johanna Johnston, executive director of the Southern Aroostook Development Corporation. The group is organizing a multi-day eclipse festival in Houlton, and offering the Eclipse Company app for free for attendees.

"It has an eclipse timer that has the vibration and sound alarms that will notify you when it's safe to take off your glasses and put them back on."

Legitimate glasses are labeled with a special ISO safety code, 12312-2, but there are plenty of counterfeits on the market. The American Astronomical Society has a list of safe suppliers on its website.

The website also has instructions on how to view the eclipse indirectly with a pinhole projection made from common household items. For those with no special equipment, there will be opportunities to watch livestreams at the USM Planetarium and The Temple Theater in Houlton. And the University of Maine will livestream the event on YouTube. However you choose to watch it, says Herrick-Gleason, it will be spectacular.

"If you have the ability to see a total solar eclipse, you'll never forget it," he said.