Nicole Bajic was a medical resident at the University of Chicago when she took a short break from surgery training classes to watch the 2017 solar eclipse darken the skies. At that time, she didn't fully understand how much excitement surrounded the event.
Bajic, now an ophthalmologist at the Cleveland Clinic Cole Eye Institute in Ohio, is one of the eye doctors, specialists, and eclipse experts advising eager viewers across the country on how they can make April’s total solar eclipse as safe and enjoyable as possible.
“I’m so surprised by how big of a phenomenon this is. I feel like this is a frenzy,” she told the Tribune, in what she said was perhaps her 20th interview about eye safety.
During a total solar eclipse, the moon seems to completely cover the sun, casting its shadow along its path above the Earth. This year’s eclipse will be the second of its kind in the 21st century to touch the contiguous United States. There won’t be another one until 2044. The first one was the 2017 eclipse, which Bajic saw partially from Chicago.
This time, Bajic has carefully planned her upcoming eclipse experience instead of leaving it to chance. She plans to attend a viewing party and then head to the Cleveland Guardians home opener two hours later.
Experts say those who want to watch the eclipse on April 8 should also prepare.
Regular sunglasses are not sufficient that day. Anyone looking up at the sky should wear a pair of safe solar viewing glasses to protect from the sun’s ultraviolet radiation and infrared light, which can cause serious eye damage and potentially blindness. Even a quick look at the sun can be dangerous.
“You might not realize the harm you’re causing to your eyes until it's too late,” Bajic said.
Although most people in the United States will be able to see at least a partial solar eclipse that day, only those in the 115-mile wide path of totality — right under the moon’s shadow — will be able to briefly remove their glasses for approximately four minutes. Cleveland and parts of southern Illinois will be in this path.
“The recommendation is that the absolute only time you can look at the eclipse during totality is when the moon is completely blocking the sun,” Bajic said. “The second that it’s moving, and you might see a tiny glimpse of the sun peeking out, it’s not safe any longer. So you need to look away immediately, and put back the eclipse glasses.”
An eerie change
For specialists, safety is their main concern. However, understanding how the eyes absorb light and perceive color can help viewers enjoy a brief, possibly once-in-a-lifetime stargazing event.
The eye will notice light start to dim five to 10 minutes before the eclipse’s totality. Two minutes before the main event, red colors will fade and contrast with greens and blues in a biological phenomenon known as the Purkinje effect.
“It’s very eerie,” said NASA volunteer educator and eclipse chaser Gordon Telepun. “It’s unexplainable because there’s not really another situation where your total ambience lighting can change so it looks like everything is gray or silvery.”
Usually, when the day turns into night, the eyes get used to the darkness as rod cells become more active than cone cells. This adjustment, called dark adaptation, can take anywhere from 30 minutes to two hours.
“But during the eclipse, this happens too fast,” said Bajic from the Cleveland Clinic. “You don’t have enough time.”
So the retina takes time to adapt to the quick change. This part of the eye has two types of light-sensitive cells that change light into signals sent to the brain to enable humans to see. Cones are the cells responsible for colorful vision in the daytime. Rods are the cells that work in low-light conditions and enable nighttime vision.
This effect, known after the Czech physiologist who found it, happens as cones struggle to absorb light under the moon’s shadow and rods start activating nighttime vision. This reduces the colors the human eye sees, decreasing the reds, slightly increasing the greens and blues, and creating a gray color.
During the 2017 total solar eclipse, which he saw from Tennessee, Telepun noticed the summer created great conditions that intensified the contrast: green grass and trees and people in colorful clothes.
“It was amazing. It was really, really strong,” he said. “It’s extremely dramatic in the right situation.”
Two years later, when he saw a total solar eclipse from Argentina during the Southern Hemisphere’s winter in July, the effect was unnoticeable due to the gray landscape and the muted colors people wore.
“Inform your friends and family who you’re going to go to the eclipse with to wear bright colors — extremely bright colors,” he said. “A combination of reds and greens, maybe some blues and some yellows, if you want to see the Purkinje effect.”
Sitting on a lush lawn or green grass would also provide a more intense experience from the ground, he added. Telepun said while the main event is happening up in the sky, he would encourage eclipse viewers to also look around before totality.
“The last five minutes before totality is (an exciting) time. And there’s a lot to look at, because the crescent in the sky is getting very thin, and it’s kind of exciting to look at this really thin banana up there,” he said. “But look at your surroundings. … There’s a lot of things to look at: For some of the stuff, you have to look at the sky. For some of the stuff, you have to look at your neighbors for the colors. For some of it, you have to look to the ground, like shadow bands.”
Telepun has created a phone app called Solar Eclipse Timer to enable observers to know the exact time of totality based on their location and let them follow the different stages of the eclipse through a series of announcements so they don’t miss anything, like the Purkinje effect or the shadow bands — thin, wavy lines of light and dark that can be seen on white surfaces just before and after totality.
Eye health and safety
Those who want to look at the sun as the moon partially or completely hides it from view should secure a pair of safe solar glasses in advance. But there are other things for eclipse viewers to keep in mind, especially if they have eye conditions.
Bajic said that vision can be different from person to person, and this can be due to eye problems like reduced contrast sensitivity or macular degeneration. These problems can make people experience things differently from each other.
Watching an eclipse can cause serious damage to the retina, leading to temporary or permanent blurry vision after just a few seconds of looking at the sun. People taking certain medications like tetracycline for acne are at higher risk for this retinal burn, called solar retinopathy.
On the other hand, Bajic noted that people with cataracts might be less sensitive to the sun because their cloudy vision can act as a filter. However, they should still wear viewing glasses to protect their eyes.
Being under the influence of psychoactive drugs can make eclipse viewers more sensitive to tissue damage from direct light absorption.
She finds the eclipse to be interesting, but warns that using substances to alter the mind can put people at greater risk.
Those who don't want to look at the eclipse directly can use the easy pinhole projection method during a partial eclipse or before a total solar eclipse reaches totality.
When sunlight goes through small holes and lands on a flat surface, it will project the sun’s crescent shape in a grid pattern. Spaces between tree leaves can also create pinhole projections.
Importantly, this method does not require spectators to look directly at the sun through these holes, but rather at its projections as they face away from the star. An Adler Planetarium blog post at adlerplanetarium.org/blog provides instructions on making a projector with a cardboard box.
Finding glasses
The American Astronomical Association website at eclipse.aas.org/eye-safety/viewers-filters has a list of North American vendors and manufacturers that sell safe solar glasses or handheld viewers. The association said the list is not exhaustive, so caution should be used if sellers are not included.
Bajic stressed the importance of getting solar viewing glasses from verified sources because there are many counterfeit ones out there.
According to the association, some locations of certain retail chains such as Lowe’s, Menards, Meijer, Kroger, and Cracker Barrel sell safe solar viewing glasses in-store. Warby Parker stores across the country will also be giving away free, certified solar viewing glasses. from the first of April through April eighth or until the stock runs out. The company has locations in six Chicago neighborhoods: Andersonville, Lincoln Park, West Loop, Gold Coast, Wicker Park and Lakeview, as well as suburban locations in Naperville, Oak Brook, Schaumburg and Skokie.
People who buy or renew a $65 individual or $180 family Adler Planetarium Star Pass from April 8 will get up to one free solar eclipse viewer, while supplies last. The planetarium will also give away glasses during a free outdoor event from 12:30 to 3:30 p.m. on eclipse day.
Some Chicago Public Library branches and public libraries in the suburbs will also offer programs where participants can get free eclipse glasses or make their own viewers. For more details, go to the Chicago events page at chipublib.bibliocommons.com/v2/events or suburban library map at scigames.org/eclipse/map.
As the big day gets closer and excitement grows across the country, veteran eclipse viewers and eye doctors suggest getting a pair of viewing glasses sooner rather than later — and start planning to wear Christmas colors in April.
