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How to Safely Watch a Solar Eclipse

— The American Academy of Ophthalmology recommends glasses with a special ISO code

Ƶ MedicalToday
A photo of a young woman wearing eclipse glasses and looking at the sun

With the first total solar eclipse to cross the U.S. in 7 years just a few days away, experts are recommending that observers take some precautions to ensure safe viewing of the astronomical phenomenon.

On April 8, the path of the total solar eclipse will cross from Mexico to Maine, an area that is home to an estimated 31.6 million people, . However, 99% of people in the U.S. will be able to see either a partial or total eclipse.

With so many Americans residing in the path of the eclipse, the American Academy of Ophthalmology (AAO) recently released of precautions for safe eclipse viewing, noting that viewing the eclipse without proper eye protection can cause solar retinopathy, which can cause severe eye damage and blindness.

Special eclipse glasses with certified solar filters are necessary for viewing the partial eclipse directly, which can last for over an hour in many places. To ensure safety, observers should only purchase eclipse glasses that have been approved by (ISO), the AAO said. One of the oldest, non-governmental international organizations in the world, ISO regularly publishes the , providing specific safety requirements for a wide range of products.

Eclipse glasses that meet the ISO's standards will have the code ISO 12312-2 printed on them, but AAO warned that eclipse observers should be aware that are often sold online as well.

The glasses with certified solar filters are required for viewing all periods of partial eclipse. The only time they are not required for viewing is during the eclipse's brief totality phase, when the moon fully covers the sun, exposing its outer atmosphere or solar corona. Still, eclipse totality only lasts 1 to 2 minutes, which means viewers need to be careful about removing eye protection during those moments of the eclipse.

The AAO also recommended taking certain precautions with putting on the eclipse glasses before looking up at the sun and removing them only after looking away from it. The academy also noted that observers should never use "an unfiltered camera, telescope, binoculars, or other similar devices" to view the eclipse.

If eclipse glasses are not available, a safe homemade alternative to watch the eclipse is -- which can be made using paper, tape, aluminum foil, and a pencil.

If proper eyewear is not available or traveling to the path of totality is not possible, the AAO recommends using a live stream to safely view the eclipse. NASA will host , according to its website.

Eclipse observers who experience sensitive eyes, blurry vision, or blind spots, should see an ophthalmologist for an ocular examination, experts told Ƶ.

Additional safety precautions include choosing a safe location to take in the eclipse ahead of time. One little known danger of eclipse viewing is the notable increase in fatal traffic accidents. In fact, a recent study found a 31% increased risk of fatal crashes in the U.S. during a 3-day period around the 2017 eclipse.

The AAO recommended that anyone interested in viewing the eclipse, especially totality, should choose a safe location ahead of time, and make travel plans to arrive safely. They added that a backup location may be necessary if skies are not clear at the first location.

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    Michael DePeau-Wilson is a reporter on Ƶ’s enterprise & investigative team. He covers psychiatry, long covid, and infectious diseases, among other relevant U.S. clinical news.