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Tuesday, August 22, 2017

Eclipse - Damaged Your Eyes ?

How To Tell If
Watching The Eclipse
Damaged Your Eyes
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August 21, 2017
Andrea Hsu
Less than an hour after the Great American Eclipse completed its coast-to-coast show on Monday, people's fascination with the sun and the moon quickly turned to concern about their eyes.

But if you did steal unprotected glances skyward, and especially if your eyes felt funny or hurt a little afterward, you might be wondering how you'll know if you've done any long-term damage.

To answer that question, we once again turned to Ralph Chou, a professor emeritus of optometry and vision science at the University of Waterloo, in Ontario, Canada, and a leading authority on the damage the sun's rays can do to the eye's retina.

This interview has been edited for length and clarity.
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Interview Highlights

How would somebody know if they've done any damage?
It takes at least 12 hours before we can tell if anything has happened. The thing is, if people just saw the sun briefly without a protective filter — just a fraction of a second — the chances they've hurt themselves are very low.
If they looked at the display of a camera or a smartphone but didn't look through the optics at the sun, they're in no danger. While it may look bright, it isn't all that bright by comparison. They were not getting direct optical radiation from the sun in that case. It's just a duplicate of whatever the sensors see, and there's no danger in that.
If, for some reason, they forgot to use their filters entirely — well, [permanent damage is] always a possibility, but I would hope that after all the publicity, that that didn't happen.


What might someone's symptoms be if they didn't use any filters and looked at the sun?
It wouldn't be until 12 hours later that they would even notice their vision was changing. It might not be until [the next] morning when they wake up and realize that they can't see that well.
[The symptoms would be] blurred vision, where the very center of the vision might have a spot, or multiple spots, that were missing in their vision — that were very, very blurred. Around it, there might be some clear spots. It really depends on exactly what happened, and what kind of injury there is at the back of the eye. [As Chou told us earlier, this kind of vision loss can get better over several months to a year. But about half the time, it's permanent.]

What should someone do if they're worried there could be damage? Should they stay indoors or wear sunglasses?
Seeing an optometrist is faster than getting to see an ophthalmologist. If there is damage, the optometrist would refer the individual to the ophthalmologist for further assessment and management in any case.
The damage, if any, would not be mitigated by staying indoors or wearing sunglasses, but these are ways to make vision more comfortable as the individual recovers.

I used an eclipse viewer that came from a reputable seller. But even after looking at the sun for a few seconds through that, I felt like my eyes felt weird and needed time to adjust.
The thing is, if you look for a sustained period through the filter, you're stimulating only one set of color-sensitive receptors at the back of the eye. So they'll get more work than, say, the receptors that are responsible for green and blue light. And the result will be that for a brief time, you'll suffer the same kind of after-image effects that you get from looking at a very bright headlight or flash from a camera.
You'll recall how you'll have spots in your vision that are sort of the opposite effect of what you normally see. That kind of thing will happen if you look at the sun for an extended period of time. It'll feel a bit weird as your eyes recover from that. It doesn't mean you've hurt yourself. It's just that you've overloaded some of the photo receptors, and it takes a while to get back to full function. In most cases, it's going to be just a few minutes. There's no lasting damage from that. You would have to be staring at an extremely bright image for minutes at a time before you started to get any clinically significant damage.

So what did you think about the eclipse?
For me, this was Total Eclipse No. 19. It was an extremely good eclipse. We had really beautifully clear sky [in Salem, Ore.]. It was just a beautiful sight. So, wow. It was great.

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Signs of damage to watch for include sensitivity to light, eye pain or loss of vision in one or both eyes, according to vision experts.
Everyone's googling "my eyes hurt" today

However, even in the absence of eye pain, it is still likely that the eyes have experienced some level of damage, said Dr. Howard Purcell, senior vice president of customer development at Essilor of America.

“With some diseases like glaucoma, there’s no pain associated with it,” he said. “The same thing [applies] here; the individual is unlikely to feel any pain at all.”

Following a solar eclipse in the United Kingdom in 1999, public health officials reported a surge of calls from those with apparent eye injuries. A week after the eclipse, at least 14 cases of permanent damage were confirmed. 

It has been stressed countless times that ISO-approved glasses are the only kind that should be worn while viewing the main event.
The American Academy of Ophthalmology and the American Astronomical Society recommend wearing eclipse glasses that are ISO 12312-2 certified.

“Be aware that it doesn't matter if glasses are darker or polarized,” said Dr. Lisa Park, ophthalmologist and associate professor of ophthalmology. 

“The most important criteria is that the wavelengths of light are blocked by the filter, which is why the certification is relevant,” Park said.
The only period in which it’s safe to remove protective eye gear is during the few brief minutes of totality, when the moon eclipses the sun completely.
“Even if there’s an edge of the sun that’s still visible, you’re still at risk,” Purcell said.
While viewing the eclipse without proper eye gear may not completely blind you, the sudden flood of light can cause long-term conditions, including solar retinopathy.
It happens when a sun burns a hole in the retinal tissues.
“This is a permanent damage that can be created on the retina, the back of the eye – kind of [like] the film of the camera, if you will,” Purcell said.

The eyes can also be impacted in the short term by the sunburnlike photokeratitis, which occurs when the cornea is scorched from the intensity of the sun, according to vision experts.
In the wake of recent reports of fake solar eclipse glasses being sold, it’s essential that spectators ensure that their eyes are properly protected.

“There are about 13 different brands that are ISO approved,” said Purcell. “It’s really important that you’re making sure you’re getting them from those particular brands.”
 
Ophthalmologists recommend that those impacted by any sun-related vision damage visit an eye care professional immediately.

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So you looked directly at the sun while trying to watch the solar eclipse. Maybe you didn't read the warnings or couldn't get your hands on a pair of eclipse glasses. Or maybe you did have them but couldn't resist, just for a few seconds, staring straight at the sun with your naked eyes, experts be darned.

Did you cause damage to your eyes? It's hard to tell immediately, experts say.
“Short-term issues can include solar keratitis, which is similar to sunburn of the cornea (the front part of the eye)," UnitedHealthcare Vision chief executive Linda Chous told NBC News. “This can cause eye pain and light sensitivity, with symptoms often occurring within 24 hours after exposure.”

Trickier to detect right away is any long-term damage to the retina in the back of the eye. Staring straight at the sun can cause a condition called solar retinopathy, which leads to a decrease or distortion of a person's central vision, said Sveta Kavali, an ophthalmologist and retina specialist at Saint Louis University.

“That damage is typically irreversible, and there's no treatment for this,” Kavali said in a video about viewing the eclipse safely. “The way the damage occurs on a cellular basis is that the UV rays from the sun induces a photochemical reaction that damages the photo receptors of the retina, and the part of the retina that's damaged is the part that's responsible for your central vision.”
However, because the retina has no pain receptors, you may not realize you've damaged your eyes until the symptoms appear, anywhere from a few hours to a few days after the event, according to PreventBlindness.org. Signs to look out for include loss of central vision, distorted vision or altered colors.

Only time can tell if one's retina is permanently damaged. Jacob Chung, the chief of ophthalmology at Englewood Hospital and Medical Center in New Jersey, told USA Today that it doesn't take much time staring at the sun — “10 seconds is probably too long and 20 seconds is definitely too long” — for the sun's rays to damage uncovered or improperly covered eyes. He recounted one particularly egregious case of solar retinopathy.

“I don't know if it was during an eclipse, but he said he was on LSD and looked at the sun for four straight hours,” Chung told the newspaper. “In his retina there was a pigmented spot, and his vision was very poor, needless to say. He was basically legally blind.”

Michael Schecter, an optometrist in Columbus, warned of the dangers of watching the eclipse without proper eye protection two weeks ago in a widely shared Facebook post. He was especially worried about people using phony glasses or children who were tempted to remove their eclipse glasses.
“Just like sunburn to the skin, the effects are not felt or noticed immediately,” Schecter wrote. “I have a great fear that I will have patients in my office on Tuesday, Aug 22 who woke up with hazy, blurry vision that I cannot fix.”
If you're concerned about your vision, experts say, make an appointment with an eye doctor, who will likely immediately be able to tell if you have damage related to the Great American Eclipse of 2017. (We don't recommend trying this tongue-in-cheek “simple test” from the Guardian.)

In the 1960s, Louis Tomososki, then 16, partially blinded his right eye after he and his friend stared at a partial eclipse without wearing proper glasses. More than 50 years later, every eye doctor he has visited has made the same observation a few minutes into the examination.
“The first thing each one of them says is, oh, you looked at a solar eclipse sometime in your life,” Tomososki said.


Read more:
‘20 seconds of burning’: Friends partly blinded after watching solar eclipse warn of dangers

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