Glance at solar eclipse can lead to vision loss: Experts

WASHINGTON — Just a single, unguarded glance at a solar eclipse can result in a lifetime of vision loss, eye health experts warn.

On Monday, tens of millions of spectators across Canada, Mexico and the United States could witness the moon completely obscure the sun's light, a rare celestial spectacle that will not be visible for most of North America again until 2044.

Medical literature is teeming with examples of people who suffered damage to their retinas, and health professionals are offering advice on how to avoid similar injuries.

Aaron Zimmerman, a clinical professor of optometry at Ohio State University, said the dangers of sun-gazing during eclipses were discussed by the ancient Greek philosopher Socrates, but it was not until recently that science really caught up with how eye injury happened.

When it comes to eclipses, he said, the main damage comes from "photochemical toxicity", where short, high-energy wavelengths of light — blues, violets and nonvisible ultraviolets — trigger chemical reactions that damage the rods and cones of the retina.

Humans inherently look away from the sun because of the discomfort it causes, but during eclipses "you can psychologically override" that instinct, Zimmerman said.

The best way to view the eclipse is with genuine eclipse sunglasses, which block out 99.999 percent of light. To test that the glasses are up to standard, Zimmerman advises to "find the brightest light bulb in your home, and then look at that from up close and you should barely be able to see the light".

Those fortunate enough to be in the "path of totality", under which the moon will fully block out the sun, can look up without glasses and admire the sun's outer atmosphere, or corona, glowing from behind the silhouette of the moon.

Overcast skies are forecast for Monday's cosmic wonder across Texas, already packing in eclipse chasers to the delight of small town businesses.

Like other communities along the path of totality, Waxahachie is pulling out all the stops with a weekend full of concerts and other festivities.

"I feel so lucky that I don't have to go anywhere," Ellis County Museum's Suzette Pylant said as she welcomed visitors in town for the eclipse. "I get to just look out my window, walk out my door and look up."

Agencies via Xinhua