March 26, 2024

Keep an eye on safety during April 8 solar eclipse

Eye safety should be a priority when viewing the eclipse on April 8.

(photo by Anne Rayner) (photo by Anne Rayner)

On April 8 millions of people will watch as day turns into night during the 2024 total solar eclipse. According to NASA, it will be the last total solar eclipse visible from the contiguous United States until 2044.

Although many will want to view this celestial event, eye safety should be a priority, said Stephen Kim, MD, chief of the Retina Division at the Vanderbilt Eye Institute (VEI).

A solar eclipse is when the moon blocks any part of the sun from view. The bright face of the sun is covered gradually by the moon during a partial eclipse, lasting a few hours. In a total eclipse there is a brief period when the moon fully covers the sun for a few minutes.

In Tennessee only the northwest corner of the state will witness a total eclipse. The remainder of the state, including Nashville, will see a partial eclipse.

“Solar retinopathy, damage to the retina cause by extreme and prolonged light exposure, is a real risk, and many individuals remain completely unaware of the risks of gazing directly at the sun,” said Kim, Phyllis S. and William B. Snyder Professor of Ophthalmology and Visual Sciences.

According to the American Academy of Ophthalmology (AAO) looking directly at the sun can seriously damage your eyes. Staring at the sun for even a short time without wearing the right eye protection can damage your retina permanently and can even cause blindness.

Ordinary sunglasses, even very dark ones, or homemade filters are not safe for looking at the sun.

There is only one safe way to look directly at the sun, whether during an eclipse or not: through special-purpose solar filters, according to the AAO. These solar filters are used in “eclipse glasses” or in hand-held solar viewers. They must meet a very specific worldwide standard known as ISO 12312-2.

“There are risks of viewing the eclipse without any protection. Normally, if you look directly at the sun, the natural response is to squint, shield your eyes, blink or look away,” Kim said. “The concern with the eclipse is that when it is in the partial phase, the natural reflex to shy away from looking at the sun is reduced, and that is dangerous because of the possibility of developing solar retinopathy which can occur without the person knowing it.

“In most cases, retinal damage will result in blurred vision or the presence of blind spots which can be permanent. An ophthalmologist will be able to assess and determine the amount of damage during an eye exam, but there is no proven treatment, so prevention is paramount,” Kim said.

Tips from the AAO on how to safely watch a solar eclipse include:

  • Carefully look at your solar filter or eclipse glasses before using them. If you see any scratches or damage, do not use them.
  • Always read and follow all directions that come with the solar filter or eclipse glasses. Help children to be sure they use handheld solar viewers and eclipse glasses correctly.
  • Before looking up at the bright sun, stand still and cover your eyes with your eclipse glasses or solar viewer. After glancing at the sun, turn away and remove your filter — do not remove it while looking at the sun.
  • The only time that you can look at the sun without a solar viewer is during a total eclipse. When the moon completely covers the sun’s bright face and it suddenly gets dark, you can remove your solar filter to watch this unique experience. Then, as soon as the bright sun begins to reappear very slightly, immediately use your solar viewer again to watch the remaining partial phase of the eclipse.
  • Never look at the uneclipsed or partially eclipsed sun through an unfiltered camera, telescope, binoculars or other similar devices. This is important even if you are wearing eclipse glasses or holding a solar viewer at the same time. The intense solar rays coming through these devices will damage the solar filter and your eyes.