What Is Photic Retinopathy: How the Sun Burns Our Eyes During a Solar Eclipse or Any Other Day

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A woman looks up at the partial solar eclipse in downtown Washington, DC on August 21, 2017. ERIC BARADAT/AFP/Getty Images

Though there were a truckload of warnings about looking directly at the sun during the solar eclipse, some people—including President Trump—decided to risk it. Some people may have been lucky. However, the case of one woman, reported Thursday in JAMA Ophthalmology, shows that wasn't true for everyone. Her eyesight may have been permanently damaged because she looked at the sun without appropriate eye protection for just a few seconds.

Of course, the thing that really sets solar eclipse-induced eye damage apart from other forms is the name—solar retinopathy. It's still just a very bright light doing some major damage to a person's retina. And the sun is only one of the bright lights a human might encounter.

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Students at the Jennings School District view the solar eclipse with glasses donated by Mastercard on August 21, 2017 in St Louis, Missouri. Jeff Curry/Getty Images for Mastercard

Photic retinopathy is the more general term for retinal damage caused by light, and it is definitely not just a sun thing. According to the American Academy of Ophthalmology, light from the sun or from another source may cause free radicals to be created in a person's retinas, which can damage them on a cellular level. Certain parts of the cells might start swelling or changing their structure, for example.

One man, whose case was reported in the Korean Journal of Ophthalmology, damaged his retina while he was welding. Plasma arc welding uses superheated gas—temperatures can be higher than 50,000 degrees Fahrenheit. The 37-year-old was wearing protective gear but still developed a blind spot right in the middle of his field of vision—probably related to the yellow spot doctors found right in the middle of his retina.

"Photic retinal injury caused by welding is quite rare," the authors of that paper note. "The first case was reported in 1902, when Terrien studied subway construction workers." But others have also reported welding-related injuries—including one that happened because the protective goggles weren't actually very protective.

Both eclipse goggles and protective gear for welders is supposed to protect a person's eyes by blocking light. However, there's a big difference between the two. The American Astronomical Society noted in their guide to eclipse eye safety that the filters used for welding equipment are not typically dark enough to protect against the light from the sun. The eclipse glasses that meet international standards reduce visible light as well as blocking other types, including ultraviolet and infrared light. That's important, the society noted, because infrared radiation can "be cooking your retinas."

The case study didn't specify how long the welder had been working with the plasma. However, we know that looking at the sun for just a few seconds is enough to do some damage. The woman whose photic retinopathy was caused by the sun still had a blind spot—or, more accurately, a blind crescent—in her field of vision, even after six weeks. She had only looked at the partial eclipse for about six seconds without glasses; she'd also used eclipse glasses for another half-minute, but one of the researchers who shared her case told Newsweek that they may not have been legitimate glasses.

Welders, however, seem to be luckier. Their eyes do tend to recover from work-related injuries.