For more information about the total solar eclipse on April 8, including where to watch, start time and events happening around San Antonio, check out our guide.
If you plan to cast your eyes toward the skies Monday to catch a glimpse of the total solar eclipse, don’t go staring at the sun without eye protection, San Antonio eye doctors are warning eclipse chasers.
Ahead of Monday’s rare celestial event, local ophthalmologists and optometrists are reminding residents and visitors who plan to watch the total solar eclipse to use eclipse glasses certified by the International Organization for Standardization (ISO) to look at the sun before and after totality. Those who don’t could risk permanent damage to their eyesight.
Staring directly at the sun — even during a solar eclipse when some of the sun’s light is being blocked out by the moon — can have serious lasting effects on a viewer’s retinas, said Dr. Daniel Johnson, an ophthalmology professor and the chair of the Department of Ophthalmology at the University of Texas Health Science Center at San Antonio.
“You absolutely cannot use regular sunglasses — even multiple layers of sunglasses,” he said. He added photo film, welding headgear and camera lenses are also off the table for safely viewing the eclipse. “Really what has been recommended by the American Academy of Ophthalmology and the American Astronomical Association and NASA are eclipse glasses that have an ISO rating.”
Certified eclipse glasses will be labeled with “ISO 12312-2:2015,” Johnson said, although he added folks should beware of scam glasses that look like they’re certified but are fakes.
“If you have some and you look through it at a light bulb, or anything bright that you’re going to see around the house, you should not see anything,” he said. “If you see anything, throw them out.”
The best way to be sure you get real eclipse glasses is to buy from reputable vendors, such as academic institutions, astronomical societies and libraries, Johnson said. That, or you can create a pinhole projector to view the eclipse safely as well, he added.
Viewers will be able to take off their eclipse glasses during totality — when the moon completely blocks out the sun, leaving only the star’s corona showing — but should put their glasses back on once totality ends, Johnson said.
Our eyes work like complex magnifying glasses that focus light to a fine point on the retina, Johnson explained. In the retina, the most important point is the fovea, which is where that light gets focused. Looking into the sun is bad for this part of your eye, he said.
“What happens is you essentially cook your fovea,” Johnson said. “So that causes structural damage.”
Following a total solar eclipse in the United Kingdom in 1999, ophthalmologists reported 70 patients with retinal lesions, Johnson noted, which is why local eye doctors are hoping to get out the message to local viewers to protect their eyes.
“The only way to really address it is to prevent it,” he said. “So prevention is the most important thing.”
