How dangerous is it to look at the solar eclipse with the naked eye?

AUSTIN (KXAN) — Monday marks one week until the total solar eclipse on April 8, a celestial event that’ll attract countless visitors to Central Texas and the Hill Country region to bask in the sights. But before viewers get a glimpse of the eclipse, they need to make sure they have proper eye care — and know the risks of what happens when you look at the eclipse with the naked eye.

Dr. Robert Wong is a physician at Austin Retina Associates and an affiliate faculty member at the University of Texas at Austin’s Dell Medical School, where he serves in the Department of Ophthalmology. He said it’s critical people are mindful of protecting their eyes in the few moments before and after the eclipse when a sliver of sunlight will still sneak through.

ICYMI: When to view April solar eclipse in your Central Texas city

“The time right before and right after the eclipse, there’ll be just a little bit of sunlight that still comes through, and looking directly at the sunlight can certainly harm the tissues in the back of the eye,” Wong said.

How can the eclipse damage a person’s eyesight?

He described the human eye as a camera: the retina is the tissue that takes in light from the outside world. The way the human eye’s optical system works is that it focuses on light most intensely at the center of the retina, known as the fovea.

“Now sunlight is very, very harmful when you look directly at it because it can actually cause both a burn and what’s called coagulation of these tissues,” he said. “And what results with coagulation of these tissues is that you can get some inflammation and what’s called ‘oxidative stress’ of those tissues.”

That oxidative stress can result in damage to the eye’s photoreceptors, which are tasked with helping the eye absorb light. As a result of that damage, patients can struggle with blurry vision, distortion or, in some cases, permanent vision loss.

Therein comes the importance of solar eclipse glasses. Wong said it’s vital people only wear protective glasses that have received an ISO 12312-2 certification, which is an international safety standard to ensure they contain a specialty filter critical for the eclipse.

“These contain a special filter that contains silver, that block out almost all visible light, allowing just a tiny amount of light that we can safely view the eclipse through,” he said.

But what if you don’t have glasses? You can still enjoy the eclipse in other ways, Wong said.

Am I in the total or partial eclipse zone in Texas?

If you have a piece of paper, you can take a thumbtack or pin and create a tiny hole through the paper. You then have your back to the sun — it’s vital to not be facing it, Wong said — and hold out the paper, where a tiny bit of light will pass through the punctured hole and project on the ground.

What happens then is that you’ll be able to see the moon’s path in front of the sun illuminated on the ground, allowing you to experience its journey without putting your eyesight at risk, he said.

Since Central Texas is in the solar eclipse’s path of totality, there will be just shy of two minutes here in Austin where the moon entirely blocks out the sun. That’ll be the one time viewers can safely take off their glasses and stare directly at it.

What is solar retinopathy?

This isn’t the first eclipse to pass over Central Texas within the past year. Back on Oct. 14, Central Texas was in the path of totality for the annular solar eclipse, where the moon passed in front of the sun and left a “ring of fire” visible.

Thankfully, Wong said there weren’t many cases of “solar retinopathy” as a result of that celestial event here in Central Texas. He credited better education and public awareness around the necessity of eclipse viewing glasses for the event.

However, during the last total solar eclipse to pass through North America in August 2017, he said people weren’t as prepared with preventative measures.

Wong is a member of a consortium of retina specialists in the United States and Canada and said the group saw approximately 20 cases of solar retinopathy following that eclipse. Many of those patients had distorted vision and developed a small, yellow burn in the center of their fovea.

After tracking those patients for a few weeks, Wong said many of those patients recovered the majority of their vision, while some remained with small distortion to the vision.

For anyone who might experience vision problems this go around, he said early intervention is important.

“If you do have problems with your vision, consult your eye doctor immediately for them to take a look and refer you on the way to a retina specialist — we may be able to help,” Wong said.

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