Protect those peepers: 4 tips for safe solar eclipse viewing

July 5, 2017
Don’t stare at the sun—except maybe this once.

Nine times out of 10, doctors of optometry aren't on board with their patients staring at the sun, but this August is that one rare exception.

"In fact, it's a tragedy not to look," Myron Wasiuta, O.D., rather emphatically points out. "It needs to be looked at because it's one of the most impressive and memorable sights you'll ever see."

Let's be clear: Staring at the sun is still bad for your eyes in virtually all circumstances, but this particular concession is reserved for one of nature's most remarkable phenomena—a total solar eclipse. This Aug. 21, 2017, a solar eclipse will envelop the entire nation, but it's a narrow, 70-mile-wide band stretching from Oregon to South Carolina where the exception to the rule applies. And even then, only for a few minutes at most.

The 2017 Eclipse Across America is noteworthy for a path that makes it visible from most Americans' backyards; 500 million people across North America will see at least a partial eclipse, yet only about 12 million live within the path of totality. That means it's especially important for Americans to clearly understand how to safely view the eclipse.

What to expect from the eclipse

First things first, it's important that patients are aware of the distinction between a 'partial' and 'total' solar eclipse, says Dr. Wasiuta, an amateur astronomer and eclipse aficionado. Unless inside the band of totality, Americans must use special eclipse viewers to protect their eyes from the sun's harmful rays at all times. Those inside totality also must use eclipse viewers until the sun is entirely blocked by the moon, and then the eclipse is safe to the naked eye for a few brief moments.  

"Once the total eclipse starts, there's only about 30 seconds to a minute of prime viewing, and it's over before you know it," Dr. Wasiuta says. "It's an utterly bewildering and awe-inspiring occurrence: birds begin to roost, streetlights come on, the temperature drops and it's as if the whole Earth is confused about what it should be doing.  

"But you've got to be careful. Just before it's over, you'll see beads of light starting to form on the trailing edge—Baily's Beads—and that's the sign that you need to avert your eyes. The sun can be bright enough to cause retinal damage."  

Captain Tyson Brunstetter, O.D., Ph.D., a U.S. Navy doctor of optometry working with astronauts at NASA's Johnson Space Center, says the single greatest risk to viewing a solar eclipse comes from low energy radiation that passes through the eye and onto the retina. This solar retinopathy causes damage to the fovea and can cost people their visual acuity.  

"Think about how a spectacle lens can be used to tightly concentrate sunlight to start a fire," Dr. Brunstetter says. "The same thing happens when viewing the sun with the naked eye."  

How to: 4 tips for viewing a solar eclipse   

Given the vast numbers of Americans able to view the solar eclipse, this eye safety message is critical, and AOA is helping lead that charge. Partnering with the American Astronomical Society (AAS), NASA and others, AOA is helping push this awareness with safe viewing tips.  

Here are four ways to safely view a solar eclipse:  

  1. Use approved solar eclipse viewers. The only safe way to view a partially eclipsed sun is through special-purpose solar filters, such as "eclipse glasses" or viewers that meet international standard ISO 12312-2 for safe viewing. Sunglasses, smoked glass, unfiltered telescopes or magnifiers, and polarizing filters are unsafe. If you can't find eclipse viewers, build a pinhole projector to watch the eclipse.

  2. Technique of the pros. Before looking at the sun, cover your eyes with the eclipse viewers while standing still. Glance at the sun, turn away and then remove your filter. Do not remove the filter while looking at the sun.

  3. Totality awesome. Only within the path of totality—and once the moon completely blocks the sun—can eclipse viewers safely be removed to view totality. Once the sun begins reappearing, however, viewers must be replaced.

  4. Visit your doctor of optometry. If you should experience discomfort or vision problems following the eclipse, visit your local doctor of optometry for a comprehensive eye examination. 

Read "Solar Safety & Ecliptic Intrigue" in the May 2017 edition of AOA Focus.

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