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Why you should protect your eyes while watching the eclipse

What you need to know about the coming 'Great American Eclipse'

The U.S. is in for a rare astrological treat on August 21, 2017 — that's the day of the "Great American Eclipse." It's the first total solar eclipse to cross the entire U.S. in 99 years, and more than 12 million Americans live in its path.
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The U.S. is in for a rare astrological treat on August 21, 2017 — that's the day of the "Great American Eclipse." It's the first total solar eclipse to cross the entire U.S. in 99 years, and more than 12 million Americans live in its path.

Let’s make sure one thing is clear: Here in Sacramento, you should not look at the sun without eclipse glasses at any point during the upcoming solar eclipse on Aug. 21.

People in Oregon and points southeast on the totality path, where the total eclipse will be visible, will be able to watch it safely without protective glasses after the last bit of the sun’s photosphere has disappeared behind the moon.

Here in Sacramento, however, the sun will be around 80 percent obscured at the maximum eclipse, and peering at it will still be dangerous.

To view the eclipse safely, you must use special glasses that will block the sun’s UV radiation. But beware of fakes. Glasses that are certified for solar viewing are marked with ISO 12312-2

Regular sunglasses are not a good substitute because they don’t sufficiently protect against the sun’s radiation.

The intense radiation emitted by the sun can damage the retina, located at the back of your eyes where images are translated to signals that are sent through the optic nerve to the brain.

Normally, when we glance at the sun our instinct is to look away before damage occurs. During an eclipse, this impulse might not be triggered because the light could be dimmed relative to a normal sunny day. Worse, this dimness may cause your pupils to dilate and actually let in more sunlight.

Failing to protect your eyes when watching the eclipse can cause blindness because the radiation can destroy the photoreceptors in your retina, said Dr. V. Nicholas Batra, an ophthalmologist and president of the California Academy of Eye Physicians and Surgeons.

Batra has seen patients whose vision was damaged from the last total eclipse nearly 40 years ago.

“I'm a little nervous about the eclipse, because I know we're going to end up seeing people that end up having damage from it,” Batra said.

Damage to photoreceptors is generally permanent. Still, if you’re worried you may been exposed, you should see a doctor. Although most solar damage to the eyes can’t be treated, damage related to ruptured blood vessels may be treatable, Batra said.

Depending on the duration of exposure and the intensity of the light, the damage can happen suddenly or gradually, with vision problems appearing up to a few weeks later, said Dr. Melissa Barnett, a principal optometrist at UC Davis Eye Center.

Vision problems can include loss of vision sharpness, a change in perception of colors, a blind spot in or near the center of the field of view or objects appearing smaller in one eye than the other, said Barnett.

Other safety tips: Don’t look through your camera’s viewfinder or a telescope that isn’t equipped with a proper solar filter. More guidelines on eclipse safety can be found at NASA’s website.

You can even enjoy the eclipse without looking directly at the sun, by viewing projections through a pinhole camera or on the ground through the holes of a colander or cheese grater while facing away from the sun.

Here’s what to expect when the solar eclipse occurs in Sacramento on August 21, 2017. Views from other Northern California locations will be similar.

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