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The Sun's Amazing Disappearing Act

Publish Date: 8/14/2017

solar eclipseUnless you’ve been marooned on a deserted island or living in a cave for the past several weeks, it is impossible not to have heard about one of the biggest astronomical events of the decade.  The “Great American Eclipse”, or total solar eclipse, will take place on August 21, 2017.

 For those in the band of totality, this means the Moon passes directly between the Earth and the Sun on its orbit around the Earth, and the Sun will go dark. The shadow of this eclipse will pass through 14 states from the west coast of Oregon to the east coast of South Carolina.

The temptation to look at the sun during this phenomenon will be understandable. However, doing so will cause permanent damage to the retina of your eyes.

Washington University ophthalmologist, P. Kumar Rao, MD, explains why retina damage can occur when looking at the sun during the eclipse and how to prevent vision loss. “Sun rays are strong enough to damage and destroy the retina with prolonged direct exposure. The retina is like film in a camera – if the film is damaged, you will lose your vision. This damage is called solar retinopathy – and is permanent.”


Solar eclipse viewing glasses make it safe to look at the sun during the eclipse. Dr. Rao says, “These glasses filter all the wave lengths of light and diminish the amount of light passing into your eyes. To make sure you have the proper solar filters, they should be ISO rated to the 12312-2 international standard. They should also have the manufacturer’s name and address printed on them.

It can be safe to look at the sun during the totality – when the sun is completely blocked by the moon. However, depending on your location, the totality may only last for a moment.  So the length of totality is hard to estimate.”

Dr. Rao also says that even if it is overcast, it is not safe to look at the eclipse without the proper viewing glasses.

For a list of reputable vendors of solar filters and viewers, click here. 

Dr. Rao's areas of specialty include the retina, ocular oncology, diabetic retinopathy and uveitis. He sees patients at two convenient locations.

Center for Advanced Medicine, Eye Center
4921 Parkview Place, Suite 12C
St. Louis, MO 63110
(314) 362-3725

Center for Advanced Medicine – South County
5201 Midamerica Plaza, Suite 2500
St. Louis, MO 63129
 (314) 272-0020


General Health
Ophthalmology, Retina
P. Kumar Rao