August 2, 2017

The eclipse and your eye health: What you need to know

Lee Schelonka, MD, a Kaiser Permanente Ophthalmologist in Lone Tree, Colorado, shares tips for safely viewing a solar eclipse.

It’s been almost 4 decades since the Lower 48 states have experienced a total solar eclipse. That streak will be broken this August 21 when the moon blocks the path of the sun’s rays to Earth. While Colorado is not in the path of totality, thousands will flock north to Wyoming to witness this rare, beautiful and dangerous phenomenon.

I say dangerous because, as an ophthalmologist, I know what staring at an eclipse without proper protection can do to the human eye. To help alleviate concerns, dispel myths, and educate eclipse viewers young and old, here are some tips on how to protect your vision and prevent an unnecessary trip to the emergency room:

Can I look at the eclipse with my bare eyes?

If you’re in the path of totality, it is safe to look at the total eclipse with your bare eyes — although I don’t recommend it. Even in the path of totality, there is only a two-minute period when you can safely look directly at the eclipse, and the path of totality for the total eclipse is only 80 miles wide. That’s a small window for safe viewing.

If you’re not in the path of totality, like here in Colorado, you’ll likely see a partial eclipse. It’s not safe to look at the partial solar eclipse with just your bare eyes. And no, stacking three sunglasses on top of each other won’t be enough protection either. You need specially made eclipse glasses designed and tested to have enough safe filtering of the sun’s light in order for you to look at the eclipse.

NASA and the American Astronomical Society recommend your glasses have the ISO Certified seal of approval, or ISO 12312-2 printed on them. This ensures the glasses were made safely and will protect your eyes. Many major local retailers provide these glasses online or in-store.

Why don’t regular sunglasses protect my eyes from the eclipse?

Regular sunglasses don’t block enough of the ultraviolet (or UV), infrared or even the visible light. Solar eclipse viewing glasses are made to reduce the brightness of the sun by a factor 10,000. Comparatively, regular sunglasses block the sun by a factor of 10.

If you look at the sun while you can see the partial eclipse, you can damage your retina and potentially end up in the hospital or emergency room. The part that is damaging to the retina is the ultraviolet light, which also causes skin cancer.

By wearing or using the proper eye protection, you’re keeping your retinas safe. The retina is the inner lining of the back of the eye — it’s similar to the thin lining of your smartphone’s camera. You can damage your retinas by looking at the sun without proper eye wear and you can also damage your camera if you’re taking direct photos of the eclipse.

How can I look at the eclipse without hurting myself?

You wouldn’t likely feel any pain when you’re looking at the partial eclipse, but after you look away, you can see an after image of the sun —  a ghost image. This can lead to a shadow in your vision that can be permanent.

It’s best to never look directly at any eclipse and always use the proper, safety-rated eclipse glasses. You can also build your own eclipse viewer. This DIY project comes from NASA. Once you build it, you point the box toward the sun and you’ll see an image projected back to you in the box.

Adults and children all over the United States will be curious to view the eclipse. Parents can prevent eye damage in their kids by educating them ahead of time of the dangers and making sure their kids are wearing the glasses or using the DIY viewer. This is a rare event, happening once maybe twice in a lifetime. So, get out and enjoy it. Just please protect your eyes!

Dr. Schelonka works for the Colorado Permanente Medical Group, one of the state’s largest multispecialty physician groups.