'How do I know if my solar eclipse glasses are legitimate?' 4 eye safety tips to know before Aug. 21 | St. Louis Public Radio

'How do I know if my solar eclipse glasses are legitimate?' 4 eye safety tips to know before Aug. 21

Aug 7, 2017

We all know staring directly in the sun is a bad thing, right? But, on the other hand, we’re told that viewing the total solar eclipse on Aug. 21 will be an awesome sight to behold. How do you reconcile the two?

On Monday’s St. Louis on the Air, we discussed proper eye safety for the upcoming eclipse and answered your questions. Joining the program to share their insight were Dr. Carl Bassi, director of research for the UMSL College of Optometry, and Dr. Larry Davis, dean of the UMSL College of Optometry. 

Here’s what you need to know:

1. The only time it is safe to view the eclipse without eye protection is during totality (when the moon completely covers the sun).

“Even a few seconds with looking at the sun without a filter, there’s a possibility of damage happening in your eye in the lead up to totality,” said Dr. Davis. “In the city of St. Louis, there is no totality, so it is not safe to take your eye protection. If you go 30 miles south, or 35 to 40 miles west, it is safe to take glasses off during totality. Totality will be brief in some areas and the longest you’ll be able to take your glasses off is for two minutes. If you’re not close to the center, it will be much shorter.”

2. Looking directly at the sun before or after totality can cause permanent eye damage.

If you look directly at the sun before or after totality, Davis said that patients might experience changes in color, the addition of wavy lines to vision, loss of central vision and watery eyes.

Dr. Carl Bassi and Dr. Larry Davis, the director of research and dean of the UMSL College of Optometry, demonstrate how to properly wear solar eclipse glasses at the St. Louis Public Radio studios.
Credit Kelly Moffitt | St. Louis Public Radio

The condition is called solar retinopathy. Essentially the high-intensity visible light causes retinal burns. Exposure of the retina to intense visible light damages light-sensitive rod and cone cells in the eye, triggering chemical reactions that damage the cells’ ability to respond to visual stimuli, which results in loss of vision for short or long period of time (depending on the severity).

“Damage happens to photo receptors, which provide vision,” said Davis. “When you look at something, there’s a chemical reaction that transmits lights into an impulse, transmitted into the brain, and interpreted by visual cortex.”

Damage to the eye from an eclipse impacts the most acute, precise vision in the central part of the eye, what you would use to read.

Bassi said that in many cases, “eclipse blindness” is a transient process and can clear up after a few months, but that there are certainly some people who have permanent loss of vision from it.

A recent NPR story on the subject, cited a doctor who said half the time, eye damage is permanent.

3. What can you use to protect your eyes and view the eclipse as it approaches totality?

Your safest bet is solar eclipse glasses, unless you have a bunch of aluminized polyester lying about. You can also use Welders’ filters graded 12 to 14 from welding supply companies.

Do not wear sunglasses: they do not block the right wavelengths of light.

Do not try to view the eclipse through your camera lens: it actually magnifies the damage without a proper filter.

“Eclipse glasses” or “eclipse viewers” use black polymer or aluminized polyester as a filter material to view the eclipse through, blocking visible and near-infrared radiation from reaching the eye, and are shaped like glasses to fit over the ear.

Your only other option to view the eclipse is to view it non-directly using a pinhole (here’s how).

You can make a pinhole in a piece of paper, hold it up and have sun project through the ground, leaving a shadow of the eclipse at different stages,” Bassi said. “I’ve seen people use colanders, so you can see multiple eclipses.”

4. How do I know my eclipse glasses are legitimate? Remember the letters and numbers “ISO: 12312-2.”

What solar eclipse glasses look like, including the proper ISO designation on them.
Credit Kelly Moffitt | St. Louis Public Radio

Of course, there are some scammers out there trying to sell eclipse glasses that are not safe for eclipse viewing. Here are some ways to tell the glasses are legitimate:

  • Look on the glasses for a number preceded by the letters “ISO,” which stands for International Organization for Standardization, reading “12312-2” or “12312-2:2015.” This means requirements have been met by the glasses to protect your eye.
  • There’s no way to check if the glasses’ filter meets the ISO standard for yourself and some bad seeds may try to sell glasses with a fake label on them. The AAS Solar Eclipse Task Force has compiled this list to see if the seller you’re buying the glasses from is reputable.
  • Make sure the glasses do not have scratches or wrinkles on them.
  • If you can see anything through the eclipse filter, including the sun or something that is comparably bright, and the light coming through the filter is not dim, you likely have a pair of fraudulent or damaged solar eclipse glasses. Safe glasses would produce a view of the eclipse that is about as bright as the moon.  

St. Louis on the Air brings you the stories of St. Louis and the people who live, work and create in our region. St. Louis on the Air host Don Marsh and producers Mary EdwardsAlex Heuer and Kelly Moffitt give you the information you need to make informed decisions and stay in touch with our diverse and vibrant St. Louis region.