How to Watch the Solar Eclipse Without Damaging Your Eyes

Fact checked by Nick Blackmer

Key Takeaways

• During a solar eclipse, the moon blocks the sun from Earth's view.

• If you look directly at an eclipse, your pupil will expand to accommodate for low light even though the UV radiation from the sub remains high. This can cause damage to the cornea and retina. That damage can be permanent.

• You need special glasses or viewers to watch the eclipse. Don't attempt to make your own.

On April 8, a total solar eclipse will sweep across North America, passing through parts of Missouri, Illinois, Kentucky, Vermont, New York, and Maine.

Since total solar eclipses require precise alignment of the sun, the moon, and the earth, they only happen about once every year or two. But they aren’t visible from the same place every time. In fact, the next total solar eclipse that will be visible from the U.S. won’t be until 2044.

What Is a Solar Eclipse?

A total solar eclipse occurs when the moon passes between the sun and Earth, blocking out some or all of the sun’s light from reaching certain areas on Earth. This can make it look like the sun is partially or completely covered by the moon, creating a temporary darkening of the sky.

If you plan on trying to catch a glimpse of the solar eclipse this year, it’s important to learn how to do so safely, James Kelly, MD, an ophthalmologist at the Kelly Vision Center in New York, told Verywell in an email. Looking directly at the sun during a solar eclipse can cause temporary or even permanent damage to your eyes.

“It’s never safe to look at a solar eclipse. Depending on the time of the eclipse, even looking at it for a few seconds can damage the eye and the fovea,” Kelly said.

Why Can Looking at a Solar Eclipse Damage Your Eyes?

Looking directly at the sun with your naked eye, particularly during a solar eclipse, can cause solar keratopathy, or mild corneal burning (photokeratitis), Bryce St. Clair, OD, FAAO, assistant professor in the Department of Ophthalmology at the Wilmer Eye Institute, Johns Hopkins Medicine, told Verywell in an email.

This eye condition usually develops after unprotected exposure to ultraviolet (UV) rays. According to the American Academy of Ophthalmology, photokeratitis damages and exposes the underlying corneal nerves, potentially causing intense pain, sensitivity to light (photophobia), and a sensation of foreign objects in the eye.

Takeaway

Looking at the solar eclipse isn’t the only thing that can burn your cornea. Direct sunlight, welding arcs, tanning beds, and even reflections off of snow can cause the same damage.

Viewing the solar eclipse may also cause solar retinopathy, damage to the light-sensitive tissue at the back of the eye, Ron Benner, OD, President of the American Optometric Association, told Verywell in an email.

“When exposed to intense sunlight like during a solar eclipse, the cells in the retina can become damaged and cause long-term vision issues,” Benner said. “Essentially, it’s like getting a sunburn on the most sensitive spot of the retina.”

Even brief exposure lasting just a few seconds can cause solar retinopathy, resulting in mild to moderate loss of central vision. It can be permanent in some cases, Kasra Rezaei, MD, associate professor in the Department of Ophthalmology at the University of Washington, told Verywell in an email.

Wondering why this can happen when the sun is blocked from your view? When there isn’t much light around, as is the case during an eclipse, the pupil expands to allow in more light. Even though there will be less visible light from the sun during a solar eclipse, the amount of UV radiation remains high. When the pupil expands to accommodate for low light, the UV radiation can cause damage to cells in the eye.

How to Safely Watch the Solar Eclipse

To safely watch the solar eclipse, make sure you wear certified eclipse glasses or viewers, which are designed to block out harmful UV rays, St. Clair said. Certification comes from the International Organization for Standardization (ISO) and means that the glasses meet an international safety standard to protect your eyes, he added.

It’s important to purchase products from a reputable vendor or reliable source, Benner said, since there are many counterfeit products on the market that might not be safe. The American Astronomical Society (AAS) has a list of reputable manufacturers and authorized dealers on its website that people can search from. Make sure you read and follow all directions that come with eclipse glasses or viewers.

If you normally wear eyeglasses, Benner recommends wearing your eclipse glasses over them or holding your handheld viewer in front of them.

Do not attempt to make our own glasses.

“ISO eclipse spectacles go through rigorous, international accredited safety standards that most people are not able to reproduce in their own homes,” St. Clair said.

Even during the brief “period of totality” when the sun is completely blocked, which only lasts for two to four minutes depending on where you are, it’s still essential to wear proper eye protection, Benner said.

“There’s never a safe time to view the eclipse outside the path of totality and eclipse glasses are required for the entire duration,” Benner said. “Parents should also observe their children carefully while watching the eclipse so that they don’t sneak a view without their eclipse glasses.”

What Is the Path of Totality?

The path of totality refers to the specific area on Earth where the total phase of a solar eclipse can be observed. Within this path, the moon completely covers the sun, resulting in a brief period of darkness. This year, the path of totality will be visible along a narrow track across 13 U.S. states stretching from Texas to Maine.

If you don’t get eclipse glasses in time for April 8, it’s important not to turn to regular sunglasses as an alternative.

“Regular sunglasses, no matter how dark, are not safe for viewing the sun. Smoked glass, unfiltered telescopes or magnifiers, and polarizing filters are also unsafe,” Benner said.

In the absence of any safe viewing tools, consider the pinhole method if you still want to participate in the eclipse. With the sun to your back, you can use your hands to cast a shadow that displays the crescent shape of the eclipse.

How to Know If You Have Eye Damage

Most of the time, people watching the eclipse without proper eye protection will not experience any symptoms or damage at first. That’s because the eyes have no pain receptors, St. Clair said. However, they may see a central “blind spot” seconds to minutes after their exposure, depending on how long the exposure lasts.

Benner added that it can take a few hours to a few days after viewing the solar eclipse to realize the damage that has occurred.

“The time it could take for damage to occur depends on several factors, such as the dilation of the pupil and the sun’s intensity on that specific day,” he said.

Some common symptoms of eye damage from an eclipse include:

• Loss of central vision

• Distorted vision (e.g., a straight line looks bent)

• Color changes

• Blurry vision

• Headache

• Increased sensitivity to light

If you experience discomfort or vision problems following the eclipse, Benner recommends visiting your local doctor of optometry for an in-person, comprehensive eye exam. In the meantime, avoid touching, rubbing, or applying pressure to your eyes.

“All symptoms should be treated as urgent until viewed by a doctor of optometry,” he said. “Steroids have been tried to improve and reverse symptoms, but there is no proof that they work for solar retinopathy.”

How Long Does Eye Damage Last?

The duration of any eye damage from an eclipse depends on its severity. For most people, it will resolve in several months. But for others, Kelly said it might never get better.

Solar keratopathy is usually minor and is likely to heal in a day or so. St. Clair says complete recovery is likely. Artificial tears can help with lubrication and comfort as the cornea heals.

Solar retinopathy, on the other hand, is more likely to persist. Benner said vision may return to normal about three to six months after experiencing retinal damage. But in some cases, it can cause permanent vision loss in the form of small blind spots and distortion.

“Someone with even mild solar retinopathy can then have, at best, corrected vision of no better than about 20/40—sometimes worse in more serious cases,” Benner said.

With these risks in mind, experts want to remind people that they should never look directly at the sun—eclipse or otherwise.

“When in doubt, play it safe. There will always be other solar eclipses that you watch, but you only have one set of eyes,” St. Clair said. “It’s important to protect them with proper spectacles and preventative routine eye examinations.”

What This Means For You

If you plan on watching the solar eclipse, experts say you should wear certified solar eclipse glasses or viewers. To find a list of reputable manufacturers for eclipse glasses and viewers, visit the American Astronomical Society’s website.

Read the original article on Verywell Health.