We have all heard that it is very dangerous to look at an eclipse. Have you ever wondered why looking at an eclipse is so bad? Can someone really go blind from doing it, or is that just a myth?
Viewing an eclipse or even the sun can lead to a condition called solar retinopathy. The effects of solar retinopathy have been known for centuries. The great scientist Galileo described his own sufferings from this condition, which developed after he viewed the sun through his telescope. The condition has been reported in sailors, military lookouts, members of sun cults, sunbathers, and people under the influence of psychogenic drugs, such as LSD.
Solar retinopathy occurs when the sun damages the retina. High-energy ultraviolet light striking the retina creates dangerous particles called free radicals. These free radicals damage the photoreceptors in the back of the eye. The photoreceptors are the structures that allow the eye to detect light, so photoreceptor damage results in decreased vision.
This damage can occur in as little as 30 seconds in some individuals, but almost everyone will be affected by 90 seconds of looking at the sun. This is especially a problem with eclipses for two reasons. solar-eclipse First, when we look at the sun, most of us will feel uncomfortable because of the intense brightness and look away. During an eclipse, the visible light is blocked but the more dangerous ultraviolet light is not. So when we view an eclipse, we get a large dose of ultraviolet light but not the discomfort of the bright light that would ordinarily cause us to look away. Second, when we look at a bright light, our pupil constricts. The constriction of the pupil protects our eye from potential damage in addition to making us more comfortable. During an eclipse the sky becomes darker, so our pupils dilate; this allows a lot more of the dangerous ultraviolet light to enter our eyes and damage the photoreceptors.
Several very good studies have been performed after eclipses to try to determine the seriousness of solar retinopathy after individuals look at an eclipse. A study performed in Pakistan following a total solar eclipse in April of 1995 followed 36 patients for 7 years who presented with decreased vision after viewing the eclipse. Over the course of the 7 years, 26 patients fully recovered, 7 partially recovered, and 3 showed no recovery.
Most studies show similar findings. So while most patients recover, viewing an eclipse is still extremely dangerous. Some patients do not recover, and we do not yet know what caused some people to recover fully while others did not. Also, there is no treatment for solar retinopathy, so if you happen to be one of the unlucky ones who suffers permanent damage, there is no way to fix it. Therefore, we cannot stress enough that staring at an eclipse, or the sun for that matter, should be avoided.
There are safe methods to view an eclipse. Most involve viewing a projection of the eclipse rather than viewing the event directly. However, because of the danger of solar retinopathy, this should only be done by children under adult supervision and only by someone who knows what they are doing.
Conclusion: Myth Confirmed
Do you have an eye question you have always wondered the answer to? Have you ever heard someone say something about eyes and wanted to know if it was true? Then email the Eye Mythbusters, Dr. Patty and Dr. Benfield at eyemythbusters@gmail.com to find out the answer. A new myth will be examined every month.
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