How to protect your eyes while watching Monday's solar eclipse

NASA map, adapted by Kentucky Health News

Journal of the American Medical Association

On Monday, April 8, a solar eclipse will pass over Mexico, the U.S., and Canada. The eclipse will be total in parts of Kentucky along the lower Ohio and Mississippi rivers. In Paducah, totality will last about 1 minute and 45 seconds, starting just after 2 p.m. Central Time; in Henderson, it will last 2 minutes and 10 seconds, starting at 2:02 p.m. CT. Maximum totality, at the center of the eclipse path, will exceed 4 minutes. A NASA map is here.

A total solar eclipse occurs when the moon completely blocks the view of the sun in a narrow path across the earth’s surface. In a partial solar eclipse, the moon only partially blocks the sun, so it can be observed an area that is thousands of miles wide. But clouds can obscure it; the National Weather Service is updating Monday's cloud forecast daily.

What Are the Dangers of Watching a Solar Eclipse? Watching a solar eclipse without proper eye protection can cause vision loss, including blindness, due to burning of the macula, which is part of the retina, the light-sensitive tissue at the back of the eye that enables people to read and recognize faces. Some individuals mistakenly believe that it is safe to view a total eclipse without eye protection during the time when the moon completely blocks the sun. However, totality of this eclipse will last from a few seconds to more than 4 minutes, based on geographic location, and bright sunlight will suddenly appear as the moon moves. Even a few seconds of viewing the sun can temporarily or permanently burn the macula. Once retina tissue is destroyed, it cannot regenerate, resulting in permanent central vision loss.

Safe Ways to Watch a Solar Eclipse: Exact times and locations of the upcoming solar eclipse can be found at science.nasa.gov/eclipses/future-eclipses/eclipse-2024/where-when/. Worldwide, 8 total solar eclipses will occur in the next decade.

Never view the sun or a total solar eclipse with the naked eye or by looking through binoculars, telescopes, or a phone camera. Sunglasses alone also are not safe. Make sure to supervise children using solar filters. Some safe ways to view an eclipse include:

• Direct viewing through shade No. 14 welder’s glasses
• Direct viewing through aluminized Mylar filters: These plastic sheets can be used for viewing an eclipse but should be used only if totally intact, with NO scratches.
• Pinhole projector: Make a pinhole in a piece of cardboard; hold it in front of the sun just before the eclipse. With your back to the sun, focus the light going through the pinhole onto another piece of cardboard beyond the pinhole so that you see the sunlight focused onto the second piece of cardboard. As the eclipse occurs, you can see the focused sunlight become blocked by a dark circle (the shadow of the moon). Look only at the image on the paper. Do not turn around and view the eclipse with the naked eye.

A list of recommended solar filter vendors can be found at the American Astronomical Society’s website.

If Vision Loss Occurs After Viewing a Solar Eclipse: Individuals with vision loss after viewing a solar eclipse should promptly visit an ophthalmologist, an eye doctor who can recognize symptoms and signs of solar burns on the retina. The diagnosis might be made on clinical evaluation or with diagnostic tests such as optical coherence tomography, a noninvasive imaging technique that can identify solar damage to the retina. There is no definitive treatment other than observation; sometimes individuals have partial recovery of vision.