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How to Protect Your Vision While Viewing the Eclipse

Words courtesy of Seven Days
By Mary Ann Lickteig  

On April 8, a total solar eclipse — when the moon completely blocks the sun — will darken a 115-mile-wide swath from Mexico to eastern Canada. In Vermont, the path of totality will cover the upper third of the state. The time and duration of totality will vary from town to town. In Burlington, the eclipse will begin at 2:14 p.m., and the total eclipse will occur from 3:26 to 3:29 p.m., according to the University of Vermont. Thousands of people across northern Vermont will marvel as the skies go dark in the middle of the afternoon.  

One thing no one should be in the dark about: eye safety.  

The stakes are high. The sun can burn the retina in seconds. Looking at the sun without proper protection — even when it's partially blocked by the moon — can cause permanent blind spots, distorted vision and altered color perception. What's more, says Berlin ophthalmologist Jessica McNally, it won't be obvious that it's happening. Sun damage doesn't hurt, McNally said, and vision problems don't show up for hours.  

There is no treatment for such injury, called solar retinopathy.  

Most people know to wear eclipse glasses or use solar filters to protect their eyes. "I think the most important thing is to understand what kind of glasses you're getting," said McNally, president of the Vermont Ophthalmological Society.  

Eclipse glasses and their alternative — index-card-size, handheld eclipse viewers — need to meet international safety standard ISO 12312-2. However, some are stamped with that ISO number even though they haven't been tested or proven to meet that standard. Along with the American Academy of Ophthalmology, astronomers and other experts, McNally urges consumers to use only glasses and filters that come from the trusted suppliers vetted by the American Astronomical Society.  

That list — along with specific guidelines for use — can be found at Solar Eclipse Across America, a website devoted to the April eclipse.  

Among those guidelines is to always inspect your solar filter or glasses before use. If they're damaged, throw them out. Also, be sure to read and follow any accompanying instructions.  

At the risk of being obvious, put eclipse glasses on before looking up at the bright sun. If you normally wear eyeglasses, put your eclipse glasses on over them, or hold your handheld viewer in front of them. Turn away from the sun before removing your eclipse glasses or filter.  

Cameras, telescopes and binoculars need their own filters, which must be attached to the front — not the eyepiece — of each device. The American Astronomical Society suggests seeking expert advice from an astronomer before using a solar filter with these devices. Eclipse glasses will not protect your eyes if you look through an unfiltered camera, telescope, binoculars or any other optical device. The concentrated solar rays could damage the filter and injure your eyes. However, it is not necessary to wear eclipse glasses while looking through an optical device that has proper filters attached.  

Lastly, keep an eye on your kids while they watch the eclipse. "If a 4-year-old were to develop solar retinopathy, then that could be pretty devastating throughout that child's entire life," McNally said.  

The sun is about half a million times brighter than the full moon, and it emits potentially harmful ultraviolet and infrared radiation, according to the American Astronomical Society. Its rays don't change or become more dangerous during an eclipse, McNally said, but because the sun is partially obscured, it can be easier for people to look directly at it. What's more, she said, as the light around us grows darker, our pupils dilate to allow more light in, increasing the potential for damage to the retina, the layer of light-sensing cells that lines the back of the eye's interior. 

"You may have seen how sunlight can start a fire when focused through a magnifying glass," the American Academy of Ophthalmology says on its website. "The sun can do the same thing to your retina."  

The sun damages the center of the retina, called the macula, which can result in blurry or blind spots in the center of one's vision, McNally said. Straight lines, like those on a door frame, may appear wavy. Symptoms can arise more than 12 hours after damage occurs. The acute effects of this damage may be temporary, said McNally, who practices medicine at the University of Vermont Medical Center Ophthalmology in Berlin, but she suspects that full recovery isn't possible.  

Despite its dire warnings, the American Astronomical Society calls a solar eclipse "one of nature's grandest spectacles." Vermont last saw a total solar eclipse in 1932; the next one, which will cover the southern part of the state, won't arrive until 2079.  

On April 8, the Fairbanks Museum & Planetarium in St. Johnsbury will host one of the many eclipse celebrations throughout Vermont. Visitors to the free, daylong event will be able to view the eclipse through telescopes or glasses sold at the museum. American Paper Optics — on the list of vetted suppliers — manufactured the glasses, according to Mark Breen, the Fairbanks' senior meteorologist and planetarium director, who will cohost programming during the eclipse. 
 
Breen, who has worked at the Fairbanks for 42 years, has never seen a total solar eclipse. "I'm quite excited," he said.  

The museum will announce the beginning and end of totality in St. Johnsbury, which is expected to start at 3:28 p.m. At that point, people can take off their eclipse glasses — the only time it will be safe to do so — and look toward the sun. They will see its glowing corona, the superheated plasma that constitutes the outermost part of the sun's atmosphere.  

Ophthalmologist McNally said that's the only setting where she thinks eclipse observers should remove their protective eyewear: "Having to make that judgment call yourself, I think, is pretty dangerous."  

About the Series
Created by independent newsweekly Seven Days, the 2024 Vermont Solar Eclipse series is designed to help Vermonters and visitors enjoy all that the Green Mountain State has to offer leading up to the eclipse on April 8.