LOUISVILLE, Ky. — With only one weekend to go, the total solar eclipse is almost here.
As the moon passes in front of the sun on Monday, it's important to be prepared to view the once-in-a-lifetime spectacle safely.
And eclipse glasses are a necessity in order to do so!
In the path of totality, you can take your glasses off only during the 100% totality phase, but that only lasts for a few minutes. Once the sun begins to show again, you'll need to put them back on.
For the 2017 eclipse, Louisville was in the path of totality so it was safe to look at the eclipse since the sun was completely blocked out by the shadow of the moon. However, since Louisville isn't in the path of totality this year, if you don't wear the proper eyewear the light that's coming from the sun can be toxic to your eyes.
Dr. Patrick Scott, optometrist with UofL Physicians, said the damage doesn't happen as a "thermal burn," but the light would cause photo toxicity to the retina.
"Basically, it overwhelms [the eye] and causes what we call 'free radical species' which can make it sick and cause permanent damage to the receptive cells of the retina," Scott said.
He said if solar retinopathy (also known as eclipse retinopathy) occurs, a patient may notice that they are missing a small portion of their central vision and they may have some blurred vision. It may take a day or so after this onset where they notice it immediately.
"Unfortunately, there is no treatments to alleviate these symptoms that can occur," Scott said.
There have been multiple studies for patients with solar retinopathy that show it can resolve in one to six months, but Scott said that's not always the case. Sometimes there is some permanent vision damage that occurs.
Scott said eclipse glasses or a welders mask with a filter of 12 or greater are two safe eyewear options for the eclipse.
Regular sunglasses simply aren't going to cut it.
"Eclipse glasses should be the only type of viewing glasses that you would use to look at the eclipse," Scott said. "Regular sunglasses don't block out enough of the sun's rays."
He said eclipse glasses block out "99.9999% of the sun's rays" whereas regular sunglasses don't have that type of filter.
"People may be tempted to look up with their sunglasses because it's not hurting the eye to look at [the eclipse]; however, you're not aware of the damage that is occurring," Scott said.
He noted that children are especially at risk because they have "very clear lenses" inside their eyes, whereas when adults age their lenses start to yellow and they become a better filter for the ultraviolet light.
What you should look for on your eclipse glasses to ensure they are certified is an "ISO" label.
The American Astronomical Society Solar Eclipse Task Force vetted sellers and compiled a list of trusted manufacturers and suppliers of eclipse glasses here.
If your glasses from the previous eclipse have any any scratches or blemishes that could allow the sun's rays to get through, Scott doesn't advise using those.
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