Solar eclipse: will I go blind if I stare at it?

Astronomy and eye care experts warn solar eclipse watchers to protect their eyes with specialized solar filters, portable solar viewers, or eclipse glasses.

People in the eastern provinces of Canada and parts of the United States and Mexico will have the opportunity to witness a rare total solar eclipse on Monday, April 8.


eclipse glassesand other safe solar visors, use special filters made of black polymer or aluminized polyester to reduce the intensity of sunlight. They block virtually all light and are thousands of times darker than regular sunglasses, according to NASA and other astronomy experts. Individuals must wear glasses certified by the International Organization for Standardization, labeled ISO-12312-2, that meet international safety requirements.

Dr. Shaina Nensi, vice-president of the Ontario Association of Optometrists in Toronto, recommends that people get their visors or eclipse glasses from the list of suppliers provided by the American Astronomical Society.

“If they have scratches or dents, there is a chance that the protective properties have been diminished,” he said in a phone interview with CTVNews.ca.

Sunscreen or glasses should only allow users to see the sun or light as bright as the sun, not ordinary objects. “If you can see normal light through eclipse glasses or filters, then they are not safe and put you at high risk of damaging your eyes,” Nensi said.

How to wear glasses

Eclipse glasses should fit snugly enough that wearers can shake their heads without falling off, according to Robert Cockcroft, an assistant professor in the department of physics and astronomy at McMaster University in Hamilton, Ont., and secretary of the Society. Canadian Astronomical. People who wear prescription glasses should make sure they fit well underneath.

He says people may want to experiment with using only eclipse glasses, and not their prescription glasses, if that makes them safer on their face. People can put filters on first before glasses if they better cover their eyes completely, Nensi says.

NASA says the only safe time to look at the sun with the naked eye is during the brief phase of totality when the moon completely covers the sun.

“You’ll know it’s safe when you can no longer see any part of the Sun through eclipse glasses or a solar viewer,” NASA wrote on its website. “As soon as you see even a little bit of bright sun reappearing after totality, immediately put your eclipse glasses “Turn it back on or use a portable solar viewer to watch the sun.”

However, Nensi says it’s never a good idea to look at the sun without protection, even during the totality of the eclipse. This is because he could develop solar retinopathy, a condition in which the retina is damaged by looking directly at the sun or another bright light source. Since retinas do not have pain receptors, people will not feel pain if they are damaged.


Retinopathy can cause permanent or temporary blind spots, distortions of vision and the way people see color, increased sensitivity to light, eye pain and grittiness (or a feeling of sand in the eye), and even complete blindness Nensi explained.

Nensi recommends that people see an optometrist immediately if they experience symptoms, even if they are mild. The symptoms can be irreversible, depending on how long the person watches the eclipse, she said.

Protecting your skin

If people watch the eclipse for hours, they may be exposed to direct sunlight during the phases of the partial eclipse. In that case, they should wear sunscreen, a hat, and protective clothing to avoid skin damage, according to NASA.

Warnings about cameras, telescopes and binoculars

Nensi says looking at the sun through cameras, telescopes and binoculars can also increase the chances of eye damage because the lenses intensify the light rays.

If people want to use those devices or take pictures, use a special lens filter.

“Viewing any part of the bright sun through the lens of a camera, binoculars, or telescope without a special solar filter secured to the front of the optics will instantly cause serious eye injuries,” NASA wrote on its website.

Additionally, it warned against viewing the sun through optical devices while using eclipse glasses or a portable solar viewer because the concentrated sun rays could burn the filter and cause serious eye injuries. According to NASA, if proper solar filters are attached to the front of a telescope, binoculars, or camera lenses, eclipse glasses are not needed.

The American Astronomical Society warns people to avoid using solar filters designed to go on the back of the telescope, where people place their eyes. Optics can magnify sunlight and instantly damage the eyes, he explained.

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