Ask the Eye Docs: Why Can’t You Look Directly at an Eclipse?
For more than a decade, the dedicated specialists at Georgia Eye Physicians and Surgeons have provided patients from all across Georgia with an array of eye care services, ranging from routine vision exams for prescription eyewear and comprehensive medical eye exams to advanced eye disease treatment and even refractive laser eye surgery. In the latest installment of our ongoing blog feature, board-certified ophthalmologist Dr. William Segal and licensed consultative optometrist Dr. Marc Lay will answer some of the most commonly asked questions about eyesight and vision care.
Just a few months from now, on August 21, 2017, there will be a total solar eclipse. This will be the first total eclipse that will be visible from within the southeastern United States since 1970, and even though the full effect will only be experienced by people along a very narrow path, those of us in Atlanta will be able to see at least a partial eclipse during that time. You have probably heard, at some point, that it is dangerous to look directly at a solar eclipse, but many people are not sure why this is the case. After all, we go out in the sun almost every day, and many people assume that it must be safer to look at it when it is covered up than when it is at its brightest. Unfortunately, that assumption is not entirely correct. Looking directly at a solar eclipse can potentially cause serious damage to your eyes. Here’s why:
The sun is basically a gigantic, continuous thermonuclear explosion that radiates tremendous amounts of radiation. While the most harmful of this radiation is blocked by our planet’s electromagnetic field and the upper layers of the atmosphere, some still manages to get through and can potentially cause damage. The ultraviolet light (or UV radiation), in particular, can cause photokeratitis, a painful inflammation of the cornea somewhat similar to sunburn on the surface of the eye. Moreover, the damage caused by ultraviolet radiation gradually accumulates over time and has been linked to the development of certain types of cataracts as well as age-related macular degeneration.
Normally, the eye naturally adjusts to filter a good deal of this radiation out, by altering the size of the pupil. In dim conditions, the pupil grows larger to allow more light in, and in bright conditions the pupil shrinks to keep more light out. This natural response is what makes looking at an eclipse so dangerous. While the sun is obscured behind the moon, the conditions are dark, so the pupil expands to its maximum size. If you are still staring at the sun when the moon moves, your eyes do not have time to adjust and so are directly exposed to a flood of radiation. According to scientists at NASA, even when 99% of the Sun’s surface (the photosphere) is obscured during the partial phases of a solar eclipse, the remaining crescent of light is still intense enough to cause a retinal burn, even though illumination levels are comparable to twilight. Excessive exposure without protection is what makes this potentially so much more damaging than typical, everyday exposure would be.
The eyes are very sensitive organs, which is why it is so important to wear proper eye protection, even though it might be inconvenient. Taking a few simple precautions while enjoying the outdoors can go a long way towards preserving your vision and avoiding future difficulties. If you have any concerns about your vision, or any questions about how to best maintain the health of your eyes, please contact Georgia Eye Physicians and Surgeons to schedule an eye exam with Dr. William Segal or Dr. Marc Lay. Be sure to follow us on Facebook, Twitter, and Google+ for more information on how to keep your vision clear and healthy.