Solar Eclipse is a Memorable Spectacle, But Here's How to Make it Safe On the Eyes

eclipse glasses
Without some eye protection the sun’s strong, hot rays during the eclipse can cause permanent damage to the retinas. Eye doctors have a fancy name for it: solar retinopathy. Stefan Wermuth/REUTERS

On Monday, millions of people will have the opportunity to view the Great American Solar Eclipse, a spectacular celestial event in which the moon passes through the middle orbit between planet Earth and the sun. As a result, the moon's diameter appears larger than the sun; this blocks direct sunlight and floods the area with darkness for more than two minutes. Some enthusiastic eclipse viewers may think the solar eclipse is a rare opportunity to safely view the sun. Quite the opposite is true.

During the time of the eclipse, one can catch a glimpse of the outer layer of the sun—known as the corona—since the moon will obscure its center. The moment will be dazzlingly beautiful. The problem is that the corona is made up of ionized gases that are very hot, which poses some risk for serious and irreversible damage to the eyes. Without some eye protection the sun's strong, hot rays can cause permanent damage to the retinas. Eye doctors have a fancy name for it: solar retinopathy.

A study conducted on 45 people who attended an eye clinic following the solar eclipse in the U.K. that occurred in August 1999, found only four people still had some eye problems seven months after viewing the event. According to a paper published in JAMA Ophthalmology on Friday, symptoms included eye discomfort and seeing "black spots" in the field of vision.

According to the authors of the JAMA paper, solar retinopathy most often occurs in young adults. "Although a clearer lens that is more permissive to transmitting visible light may contribute to this finding, a more likely explanation may be simple misunderstanding of the danger of viewing an eclipse without proper protection or misuse of that protection."

Eclipse viewing is also known to cause other eye conditions. Another paper published Friday in JAMA Ophthalmology reviews the case study of a 12-year-old girl with severe juvenile open-angle glaucoma, a common condition that typically affects older adults in which the eye canals fail to drain fluid, causing eye pressure and the gradual loss of vision. The girl arrived at the emergency room with blurred vision, and closer examination revealed she had structural changes to the macula, the area around the retina that is responsible for producing sharp, clear vision.

Shades, pinholes and other eye protection

Fear not: It is still possible to enjoy this once-in-a-lifetime experience without harming your eyes. Experts, such as the authors of the JAMA paper, recommend acquiring special glasses made specifically for eclipse-viewing. These spectacles, which are becoming increasingly challenging to find—they're selling out all over the U.S.—have darkened shades that include solar filters.

According to JAMA, only four companies currently make shades with filters that meet approved standards for safe viewing. Make sure the glasses you acquire are legit. Several reports of companies trying to peddle fake eclipse glasses that won't sufficiently protect one's vision have emerged in recent weeks. The official Solar Eclipse website has links to purchase glasses, although most accredited companies are already out of stock. Here's a source for reputable vendors.

There are still other methods for viewing while preserving your vision. The simplest method is the "pinhole projection," in which sunlight passes through a small opening, such as a tiny hole in a piece in an index card. Some household items make ready-to-use pinholes, such as the colander in the back cabinet of your kitchen that you haven't used in months. Or hold you fingers together to create a grid that can serve as a the pinhole. Consider a DIY project for Sunday afternoon to prepare.

The American Astronomical Society is also a great how-to resource for safe viewing sans eclipse glasses.

Some companies make souped-up solar telescopes specially for eclipse-viewing, such as the Sunspotter. However, if you happen to own a telescope already you can purchase a special aperture filter that will block out the Sun's light.

With so many safe viewing options there's no reason to feel too discouraged by the health risks. Nearly everyone who has experienced an eclipse viewing will say the preparation is worthwhile. "A total solar eclipse represents an exciting educational opportunity for everyone," the authors of the JAMA paper write. "With some simple preparation and instruction, the eclipse can represent the chance to participate in one of the most spectacular natural events our corner of the universe has to offer."