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Eye expert offers advice about safe eclipse viewing

Helen Adams | | Updated August 10, 2017

sun during an eclipse
Photo illustration
Looking at the sun without protection, even when just a sliver is showing as it is here, can damage the eye. The only time to safely view the August 21 solar eclipse without eye protection will be during "totality," the brief period when the moon completely covers the sun.

NASA is advising people who want to view the August 21 total solar eclipse to check out the American Astronomical Society's list of reputable vendors of solar filters and viewers before buying eclipse glasses. There is concern that other, unscrupulous sellers are falsely claiming their glasses meet International Organization for Standardization, or ISO, guidelines.

Those glasses are big business, as people across the country gear up for what might be a once-in-a-lifetime chance to see a total solar eclipse. MUSC will hold a viewing event for employees on campus that day, as will some other employers and organizations.

eclipse glassesPhoto by Sarah Pack 
NASA recommends that people who want to buy eclipse glasses choose ones that meet International Organization for Standardization, or ISO, guidelines. 

The total eclipse is expected to be visible from Charleston at 2:46 on the afternoon of August 21, according to the National Weather Service. NASA has posted maps showing its predicted path across 14 states, including South Carolina. People are taking notice in a big way. The Post and Courier reported that one million people are expected to visit the state for the event. Those who don’t can still see the eclipse from a Charleston vantage point, because NASA plans to offer live video of the event from the College of Charleston campus.

If you’re planning to be among the millions who will watch the eclipse in person, MUSC Health ophthalmologist Emil Say has some advice about how to do it safely.

Q: Do I really need special glasses to see the August 21 eclipse, or will my regular sunglasses be enough to protect me?

A: Homemade filters, sunglasses and other glasses will not suffice unless they meet the International Organization for Standardization requirements. 

NASA also has printable pinhole projectors that you may want to take a look at.

Q: What about the time when the eclipse is total — can I view it without protection then?

A: The brief period when the sun is totally covered by the moon is safe, but that’s only predicted to last about 2 minutes and 40 seconds. All other points in time before or after this period of total eclipse are unsafe without special protection. 

Q:  Just how dangerous is it to look directly at the sun without protection? 

A: Staring at the sun for a prolonged period damages the retina, a condition known as solar retinopathy. A very quick glance likely will not cause damage, but prolonged sun gazing can do permanent harm. 

Q: How long does it take for an unprotected eye to be burned by the sun?

A: This would vary according to how dilated your pupils are at that time, your refractive error and your age. There are a few reports indicating that people who don’t wear glasses or contacts and are a bit farsighted are at greater risk. Young people are also at greater risk, probably because they have clear lenses with no cataracts.

Dr. Emil SayPhoto by Brennan Wesley 
Dr. Emil Say, left, says looking at the sun without protection during an eclipse can damage retinal tissue, a condition known as eclipse retinopathy. 

There is a condition called eclipse retinopathy that is similar to solar retinopathy that occurs in the setting of an eclipse rather than direct sun gazing. In both conditions, however, you suffer photochemical toxicity from the sun and damage your retinal tissue. This is not a common condition. However, it’s worth noting that in one study, 39 percent of the patients who were diagnosed with this condition said they looked at the sun for less than one minute.

Q:  What kind of eye protection will you be wearing to view the eclipse?

A: For myself, and probably my family, I probably would just wait for a video of the eclipse and not look at it directly at any point. Indirect viewing through a camera or an older technique using a pinhole or mirror to form an indirect image of the sun is safe.

General eye care questions

Q: During the regular summer season, what should people do to protect their eyes? 

A: Ultraviolet protection is generally recommended. Buy sunglasses with UV protection from reputable companies.

Q: What do you wish people knew about proper eye care? 

A: They should have their eyes checked at least once every year or two. For instance, people may not realize that 10 to 15 percent of the population will carry a nevus, or freckle, in the eye. These nevi, like any other freckle in your skin, should be followed because there is a chance that they could turn into melanoma. 

Q: Is there a difference in sunglasses? What’s worth the extra cost?

A: Definitely! UV protection should be 100 percent, or UV 400, as there are different types of ultraviolet rays, such as UVA and UVB. The extra cost of having UV protection is definitely worth it, because UV light is known to contribute to cataracts and age-related macular degeneration. And by the way, not all dark tinted glasses are UV protected, so check the labels.

Q: How will eye care change in the future?

A: I think there will be greater awareness of eye cancer in general, whether it is retinoblastoma in children, or more common, ocular melanoma in adults.  People don’t realize that only 95 percent of melanomas occur in the skin, and 5 percent that can occur in the eye.  

Risk factors for developing melanoma in the eye include having fair skin and blue eyes, and having a prior nevus. The most worrisome aspect of this is that most people don’t know they have a nevus in the back of the eye until they see an ophthalmologist who finds it, or they develop blurry vision or other symptoms from it.  

I think we need a more proactive approach to screening. This would mean more patient education and also telemedicine. We currently have ultra-wide field cameras that can capture over 90 percent of the retina through an undilated pupil in seconds.  These cameras are widely available through optometrists and ophthalmologists, as well as here at the MUSC Storm Eye Institute.

Story originally published July 9, 2017.
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