Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more.
As the total solar eclipse, occurring across Mexico, the United States and Canada on April 8, draws near, experts are reminding spectators to grab a pair of eclipse glasses to view the celestial event safely — and to make sure they aren’t fake.
Counterfeit eclipse glasses are “polluting the marketplace,” according to a release shared by the American Astronomical Society, or AAS.
A total solar eclipse occurs when the moon passes between Earth and the sun, completely blocking the sun’s face from view for a few moments. About 32 million people in the US live within the 115-mile-wide (185-kilometer-wide) path of totality, or locations where the moon will appear to completely cover the sun and the lunar shadow falls on the Earth’s surface. People outside the path of totality will still be able to see a partial solar eclipse in which the moon only blocks part of the sun’s face.
The only time it’s safe to view the sun without eye protection is during the totality of a total solar eclipse, or the brief period when the moon completely blocks the light of the sun, according to NASA.
Otherwise, experts say it’s absolutely necessary to wear certified eclipse glasses or use handheld solar viewers that meet a specific safety standard, known as ISO 12312-2, when watching all other phases of a total or partial solar eclipse. The safety standard means that the lenses meet international requirements for direct solar viewing, according to the AAS.
The lenses of solar eclipse glasses are made of black polymer, or resin infused with carbon particles, that blocks nearly all visible, infrared and ultraviolet light, according to The Planetary Society. And sunglasses won’t work in place of eclipse glasses or solar viewers.
“Sunglasses, smoked glass, unfiltered telescopes or magnifiers, and polarizing filters are unsafe. Inspect your eclipse glasses or handheld viewer before use — if torn, scratched, or otherwise damaged, discard the device,” according to a release by the American Optometric Association.
Looking at the sun without properly made eclipse glasses can result in severe eye injury, from temporary vision impairment to permanent blindness. But the AAS has discovered the production of fraudulent eclipse glasses that won’t provide the necessary protection needed to view the sun safely without incurring eye damage.
How to spot fake eclipse glasses
The counterfeit glasses might be hard to spot because they include information and even original artwork that suggest they were made by a known reputable manufacturer of the products, but different factories that have yet to be identified actually made them, according to the AAS.
“Until recently, the only counterfeit products we knew of were cardboard-frame eclipse glasses made by an unidentified factory in China but printed with ‘Mfg. by: American Paper Optics’ (APO) on them,” the AAS shared in a news release. “APO is one of the major U.S. manufacturers of safe solar viewers and prints its name and address on its eclipse glasses, whereas the Chinese copycat products have APO’s name but not its address. Thankfully, these particular counterfeits appear to be safe.”
But close tracking by the AAS has revealed that more unidentified factories are producing counterfeit glasses printed with the name and address of a Chinese factory called Cangnan County Qiwei Craft Co., which creates safe products. Some of the fake glasses also include the name or logo of Solar Eclipse International, Canada, which is Qiwei’s North American distributor.
While some of the glasses appear to be safe and are virtually indistinguishable from actual Qiwei products, others have lenses about as dark as sunglasses, which means they aren’t safe to use, according to the AAS.
“Filters that provide safe, comfortable views of the Sun generally transmit between 1 part in 100,000 (0.001%) and 1 part in 2,000,000 (0.00005%) of its visible light,” said Rick Fienberg, project manager of the AAS Solar Eclipse Task Force, in a statement. “Solar filters are at least 1,000 times darker than even the darkest regular sunglasses.”
The AAS has curated a list of safe manufacturers and resellers of eclipse glasses and filters for optical devices, including cameras and smartphones. The AAS task force for the eclipse has confirmed that solar viewers and glasses made by all known manufacturers of the products in the US and across Europe, as well as some Chinese manufacturers, have been tested in a lab.
“We now recommend that if you want to buy solar viewers online, buy only from sites you reach by clicking on the links from our list, or from a seller whose identity you can verify and whose name appears on our list,” according to the AAS. “We recommend not buying eclipse glasses from random sellers in online marketplaces, even if they claim to get their products from a supplier on our list or to be approved by the AAS or NASA. The U.S. space agency doesn’t approve or endorse commercial products, so any claim to the contrary is a warning sign that you’re not dealing with a trustworthy seller. Similarly, if a vendor claims to be on the AAS suppliers list but you can’t find it there, you shouldn’t trust them.”
Tips for safely viewing the eclipse and testing your glasses
For those who didn’t purchase their glasses directly from a vetted vendor on the list, there are ways to test eclipse glasses before April 8.
“There’s no way to tell just by looking at them whether eclipse glasses are genuinely safe,” Fienberg said, “but it’s easy to tell if they are not safe.”
Try on the glasses indoors first. Nothing should be visible through the lenses, and even the brightest lights should only appear very faintly. If furnishings or wall decor are visible through the lenses, these glasses aren’t safe to view the sun.
But if the glasses pass the indoor test, the AAS recommends putting them on outside during a sunny day and looking around. Again, nothing should be visible through the lenses, unless the sun is reflecting off an exceptionally shiny surface, and even then the light will appear faint if the glasses are safe.
If the glasses pass that second test, try looking at the sun through them for less than a second. If the glasses are safe, the sun will appear comfortably bright and likely white, yellow, orange or bluish white.
On the day of the eclipse, stand still and cover your eyes with the glasses or solar viewer before looking up. And never remove the glasses while looking at the sun. For those who wear eyeglasses, wear eclipse glasses on top of them or hold up a handheld viewer in front of them.
And remember to outfit any camera lenses, binoculars or telescopes used to observe the eclipse with the proper solar filters. Never look through an unfiltered optical device of any kind in this situation, even while wearing eclipse glasses.
Avoid eclipse eye damage
It’s only safe to view the eclipse without eye protection when the moon completely blocks the sun from view and no light is visible — and be sure to put your eclipse glasses back on before any light reappears.
Looking at the sun without proper eye protection can result in solar retinopathy, or retinal damage from exposure to solar radiation. While the highly specialized cells inside our eyes don’t feel any pain, the rods and cones and photochemical reactors become inflamed and damaged when looking at the sun, said Ronald Benner, an optometrist and president of the American Optometric Association.
It’s a bit like the effect that occurs when we see a camera flash go off, which can distort our vision for a few minutes before it goes away. But the intensity of solar retinopathy causes permanent damage that won’t be immediately apparent. Overnight, the cells can die, and they won’t be replaced. There is no treatment for solar retinopathy. It can improve or worsen, but it is a permanent condition.
The changes in a person’s vision depend on the type of damage that is done, and these can occur in one or both eyes.
“The retina is an extension of the brain, so it’s actually neurological tissue, and when you damage that, it doesn’t always come back,” Benner said. “If you damage one cell, that cell may never be the same. But if you damage a group of cells, then you’re going to end up with blotchy vision, like having someone dab oil on your windshield. If you just kind of damage them and they don’t completely die, then color vision is going to be altered. What can you do about it? Absolutely nothing other than prevent it.”
If the damage occurs in the center of someone’s vision, it can affect the ability to read or recognize faces, Benner said.
If you experience vision issues or eye discomfort after viewing the eclipse, Benner recommends booking an appointment immediately using the American Optometric Association’s doctor locator. Symptoms may take hours to a few days to manifest, and they include loss of central vision, altered color vision or distorted vision.
“For most people, it’s an alteration of color vision,” Benner said. “The next morning, colors just don’t look right, or it may be bleached out it or just kind of hazy all the time. For others, it may be that they actually have holes in their vision.”
And always keep an eye on children wearing eclipse glasses to make sure they don’t take them off and look directly at the sun. Benner advises that parents talk to their children on how and when they can view the eclipse and when they can take their glasses on and off. And if parents worry that their kids may take off their glasses at the wrong moment, make plans to watch the eclipse on TV or use the pinhole projection method to view the eclipse indirectly.
“Make sure that you’re protecting not just yourself, but more importantly your children,” Benner said. “If your child experiences eye damage, they have to live with it the rest of their life. And they may not be able to tell you, ‘I’m not seeing clearly out of one eye.’”