Why and how to protect your eyes during the eclipse

Whether partial or total, a solar eclipse is a rare and spectacular event to experience, provided that certain safety instructions are observed.

Why is it necessary to wear special sunglasses during an eclipse?

If you look directly at the Sun on an ordinary day, the pain caused by the glare quickly forces you to look away. But when the Sun’s light is partially blocked during an eclipse, infrared rays can cause damage before the pain forces you to close your eyelids. And since the point of an eclipse is to look directly at the Sun, wearing protective glasses becomes essential during the partial phases (before and after the total eclipse, if you are in the zone of totality).

What damage can be done to eyes that are not properly protected?

Light is first filtered by the eye’s lens, which acts as a magnifying lens, and focused on the retina. “In this case, it’s like focusing sunlight through a magnifying glass onto the retina,” says Dr.^D Cynthia Qian, spokesperson for the Association des médecins ophtalmologistes du Québec (AMOQ) and ophthalmologist specializing in retina at CHU Sainte-Justine and Maisonneuve-Rosemont Hospital. “It burns right in the center of the retina of the person looking at it, and it affects central vision.” This is what causes solar retinopathy. The damage can be temporary or permanent “because the retinal cells do not regenerate,” says Dr.^D Qian.

What kind of glasses are safe?

Regular sunglasses, even with the best UV protection, are not enough to protect your eyes when viewing the Sun directly. Eclipse glasses are equipped with a filter that is certified to ISO 12312-2. This filter is so opaque that only the light coming directly from the Sun is visible through it – it is 1,000 times darker than regular sunglass lenses. “You shouldn’t try to get creative with things that aren’t specifically designed for viewing the Sun or the solar eclipse,” says Dr.^D Cynthia Qian: “People ask us, for example, if they can take X-ray film or photo film negatives and make filters with layers of layers… The answer is no, it’s not safe.”

How can you be sure that these glasses are “real”?

If they are obtained from a reliable supplier—for example, an astronomy store or a government institution—and are marked ISO 12312-2, and are not scratched or damaged, there should be no problem. However, on March 22, the American Astronomy Society warned the public against selling counterfeit or non-compliant glasses on the Internet. If there is any doubt about the reliability of the filters, the organization suggests the following steps:

1. Try the glasses indoors. You should not see anything through them except the glow of very bright lights. If you can see other details through the filter of the glasses, such as furniture or picture frames on a wall, the filter is not opaque enough.

2. If the glasses pass the indoor test, you can try them on outdoors. Again, you should not see anything around you.

3. Looking up at the Sun quickly (less than a second), the Sun should appear as a sharp circle. Some filters make it look more orange, others whiter.

4. If the glasses pass all three tests, they are “probably safe,” according to the American Astronomy Society. As a precaution, it is suggested that you not look at the Sun during the partial eclipse for more than two or three seconds at a time, every five minutes.

Are eyes protected if viewing the eclipse through binoculars, a telescope or a camera?

Only if the device in question is equipped with a suitable solar filter. For example, do not look through an unprotected telescope while wearing eclipse viewing glasses.

What to do if you don’t have such glasses on the day of the eclipse?

It’s not the end of the world. You just have to avoid looking directly at the Sun during the partial eclipse. You can also follow the progress of the eclipse indirectly, by projecting the Sun’s light onto a wall or the floor through a hole in a piece of cardboard, or through other objects with holes, such as a colander. You can also make a darkroom out of a shoebox.

Watch the video from the Federation of Amateur Astronomers on ways to observe the eclipse

What if we are in the zone of totality? Can we look at the Sun without protective glasses?

Well, here’s some good news: during the total eclipse phase, and only when the Moon has completely covered the solar disk, you can look at the Sun without protective glasses. You can then admire the glow that surrounds a black circle.

The D^D Cynthia Qian, however, urges caution. “If people don’t know the exact time of totality and accidentally look at the Sun a few seconds too long after the total eclipse, that’s when they can hurt their eyes. It’s important to give yourself a good margin of safety if you decide to look at the Sun during the totality phase.”

Please note: the duration of a total eclipse varies greatly depending on the location of observation, from a few seconds to more than three minutes. During gatherings organized throughout the totality zone, the facilitators will inform participants when they can look at the Sun without glasses and when they must put them back on.

How do I know if I will be in the zone of totality?

There are several online geolocation tools available to help you know where you are in the path of the eclipse.

One of the easiest ways is to download the app My eclipsedesigned by the Federation of Amateur Astronomers of Quebec.

Download the app My eclipse

The Éclipse Québec site has also created a map with the main municipalities in the totality zone.

Check the map on Google

The Time and Date site also gives fairly precise indications on the start and end times of the eclipse, whether total or partial:

Visit the Time and Date website (in English)

“It’s a bit crazy at the moment”

In libraries, museums and specialty stores, they have been selling out quickly, sometimes within hours. To get your hands on a pair of eclipse viewing glasses less than two weeks before the big day, you now have to rely on a limited list of suppliers.

At least 20,000 pairs on March 21, then another 30,000 pairs on March 25. The company Cartouches Certifiées continues to replenish its warehouse to meet the demand for eclipse glasses. “We’re pretty much the only ones who have them,” says Francis Bernier, commercial accounts manager for the Longueuil distributor.

After successfully selling medical equipment during the pandemic, this printer cartridge supplier turned its attention to eclipse viewing glasses earlier this year. “We did an initial test, and we sold 40 pairs in two minutes.” An agreement was then reached with two American manufacturers specializing in this type of equipment. “As with medical equipment, we knew that our customers would want a certified supplier.”

Eclipse viewing glasses must be equipped with an ISO 12312-2 certified filter. This filter is so opaque that only the light coming directly from the Sun is visible – it is 1000 times darker than ordinary solar lenses. Direct observation of the Sun without proper protection can cause permanent damage to the retina of the eye.

On March 22, the American Astronomy Society warned the public against the sale of counterfeit or non-compliant glasses on the Internet.

Copies of protective glasses, imitating the graphics of certified glasses, have been spotted on online sales sites. For this reason, the Association of Ophthalmologists of Quebec (AMOQ) recommends avoiding buying glasses on general sales sites such as Amazon or eBay.

“The source of supply is difficult to verify,” explains AMOQ spokesperson, D^D Cynthia Qian.

Respond to the request

Of the dozen suppliers and institutions that the Fédération des astronomes amateurs du Québec recommends purchasing glasses from, the vast majority have sold out. “It’s a bit crazy right now,” admits Stéphane Maurais, president of Alco Prevention Canada. About 250 packages of glasses are shipped every day, and Mr. Maurais expects demand to increase further in the coming week. Three additional employees have been hired to handle orders for glasses.

Orders come from individuals, but also from businesses and institutions. “School boards, retirement homes, CEGEP co-ops, etc.,” lists Francis Bernier. Cartouches Certifiées sells the glasses in packs of 6, 50, 1,000 or 10,000 pairs. A pack of six pairs sells for $27, or $4.50 per pair. The larger the pack, the lower the unit price.

Despite the growing interest, both companies expect to have enough glasses in stock to meet demand through April 8. Both companies are accepting online orders for the glasses through Wednesday, April 3, to ensure mail delivery in time for the eclipse day.

After April 3, it will still be possible to purchase glasses directly from these suppliers’ premises, in Laval (for Alco Prevention Canada) and Longueuil (for Cartouches Certifiées). Other points of sale will also be supplied in Quebec.