Avoiding ‘eclipse burn’: Where to find protective glasses before the big celestial event

“It’s such an amazing natural phenomenon, I’m sure everyone would love to see it,” said Dr. Michael Migliori, chief of ophthalmology at Rhode Island Hospital and ophthalmologist-in-chief at Brown University’s Warren Alpert Medical School. “The problem during an eclipse is that the light is actually much more concentrated. When you were a kid you could take a magnifying glass and burn leaves. The light from a solar eclipse can cause really significant damage to the back of the eye, unrepairable damage.”

During a total solar eclipse, the moon passes between the sun and Earth and eventually fully blocks the face of the sun (”totality”), causing dramatic daytime darkness along the path of totality for about 3 to 4 minutes. In New England, the totality path of the April 8 eclipse will cover northwestern Vermont and parts of New Hampshire and Maine. Eclipse watchers from Boston to Providence and elsewhere in New England not in the total eclipse path will see roughly 90 percent of the sun covered.

It’s during these partial eclipse phases that doctors and scientists warn that safe viewing glasses with special sun-blocking material are critical and must be worn — as the moon slowly moves across to cover the sun and then again as it begins to move off the sun’s face.

“During the partial phase, the sun is still extremely bright. Even at ½ percent of brightness, you can damage your eye looking at it,” said Ian Dell’Antonio, a physics professor at Brown University.

“Because it’s coming from a small region it will still burn into your retina,” Dell’Antonio said. “You don’t want to stare a lot. Looking for a fraction of a second — your eyes can recover from that — but you don’t want to have people looking at it for many seconds unless it’s under totality.”

Nimesh Patel, director of pediatric retina at Mass Eye and Ear, said the darkness caused by an eclipse dilates the eyes and allows more light in. That makes eclipse watchers unknowingly want to spend more time looking at the sun during an eclipse than they normally would on a typical day.

So how do you know which eclipse glasses will shield you against the sun’s harmful rays?

According to the American Astronomical Society, dampening the sun’s ultraviolet radiation requires solar viewers or eclipse glasses that comply with the International Organization for Standardization or ISO 12312-2 international standard for filters. The ISO certification should be marked on the side of the glasses. Experts said the verification is crucial to protect your eyes from significant damage because they filter out not only the sun’s damaging ultraviolet and infrared rays but also 99.9% of the sun’s intense visible light.

“Such filters are at least 1,000 times darker than even the darkest sunglasses,” said Rick Fienberg, project manager of the AAS Solar Eclipse Task Force and a veteran of 14 total solar eclipses.

The AAS recommends using trusted vendors and retailers where you can buy anywhere from low-cost safety glasses made of paper to sturdier, more expensive kinds of eye shields. Many low-cost paper glasses have been widely available online and in stores for weeks but they are quickly selling out.

• Great American Eclipse

• American Paper Optics

• Rainbow Symphony

• Exploratorium Store

• DayStar Filters

• Thousand Oaks Optical — Solar viewers and filter sheets.

• Flip’n Shades — Offer clip-ons for baseball caps and visors.

• Seymour Solar — Solar filter film sheets that are safe for direct solar viewing and use with any telescope, refractor, binoculars, view finders, spotting scopes, cameras, or cellphone camera.

• Halo Eclipse Spectacles — For die-hard solar eclipse viewers willing to spend a bit more, there are solar viewers that cost over $80.

Retailers that carry ISO-certified eclipse glasses include:

• Walmart

• Target

• Lowes

• Staples

• Warby Parker -- The eyewear retailer will have a limited supply of free eclipse glasses available in their stores starting April 1, with a limit of two per person.

The AAS said people should be aware of counterfeit glasses marked with the ISO rating that are being sold at low prices via large online sites like Amazon, eBay and Temu.

Eclipse glasses don’t expire so if you have a pair from the last total solar eclipse in 2017, you can use them as long as they don’t have any scratches or tears, experts said.

Patel said people also should avoid using unfiltered binoculars or telescopes to watch the eclipse. Special kits are also available for your smartphone, telescopes, and cameras.

“Concentrated rays could burn through the lenses, potentially causing more damage,” said Patel, who himself is skipping the April 8 eclipse as a matter of eye safety. “I’m too scared. You never know. As an eye doctor, I won’t stare at the sun.”

Dell’Antonio said a group of students at Brown University is planning to drive over six hours to experience the eclipse totality.

“I have seen two total eclipses in my life and they were both spectacular things,” Dell’Antonio said. “There’s something about being under the darkness of totality. Partial eclipses are great and neat. There will be other partial eclipses that you will see, but total eclipses are something to chase. I know people who plan all their vacations around them.”

It will be a long wait for the next total solar eclipse, which will take place on Aug. 23, 2044, in the contiguous US.

Carlos Muñoz can be reached at carlos.munoz@globe.com. Follow him @ReadCarlos and on Instagram @Carlosbrknews.