The sun’s radiation is damaging to the eyes year round. But during a solar eclipse, looking at the sun with a naked eye can be blinding or in the very least, cause permanent retinal damage and scarring.
In Trail, a partial solar eclipse is forecast to begin Monday, Aug. 21 at 9:14 a.m., which is the point when the moon touches the sun’s edge. The maximum eclipse – when the moon is closest the centre of the sun – is predicted to be at 10:27 a.m. The final phase – when the moon leaves the sun’s edge – is expected to end at 11:45 a.m.
So for two hours and 31 minutes on Monday, residents in the Trail area should not look up at the sun unless they have certified eclipse glasses or hand held filters.
With the media abuzz with solar eclipse stories this week – and the fact that Trail people shouldn’t look at the sun for two-plus hours on Aug. 21 – the Trail Times talked with Dr. Lindsay Geeraert OD from Trail Vision Care Clinic about eyes versus eclipses, and how locals can protect their sight come Monday morning.
Trail Times (TT): Is it true that a person should not look at the sun during an eclipse?
Dr. Geeraert (Dr. G): Yes it is true that the sun’s radiation is damaging to the tissues of the eyes, but not only during an eclipse. Protection from the sun is important at all times of the day. People are generally aware of this fact, and we see more and more people wearing sunglasses outdoors, but I believe that the allure of an eclipse is that it is rare and people want to witness these events firsthand, which can be dangerous, and people are not always properly prepared to witness these events safely.
TT: So sun rays are damaging, but why?
Dr. G: The range of electromagnetic energy visible to the eye is known as the ‘visible spectrum’. And this includes the wavelengths of light that we are able to see that are not harmful to our eyes. However, if you extend this and include the range of electromagnetic energy emitted by the sun, it is known as the ‘solar spectrum’ and it includes not only the visible spectrum, but also the ‘ultraviolet’ and ‘infrared’ spectrums. These are the wavelengths of light that can cause damage to the eye if unprotected.
Eye tissue is particularly sensitive to ultraviolet radiation. On a daily basis we protect our eyes from the sun’s rays through proper UV protected polarized sunglasses, which is sufficient to protect our eyes from the early onset of things like cataracts and macular degeneration. However, during a solar eclipse the electromagnetic radiation that is emitted can be harmful to the retina both due to the nature of the radiation that damages the retina and the location of the damage (i.e. people tend to look directly at the eclipse, and so the image of the eclipse as well as the location of the radiation falls directly onto our fovea, which is the part of the retina that we use to see most clearly and centrally).
If this area were to be damaged, it could significantly affect our visual acuity because our vision may then be compromised by the damage or scar located on the fovea. Fortunately, however, our natural reflex is to look away from the eclipse before damage occurs, but this is not a reliable and safe way to view a solar eclipse.”
TT: Because a solar eclipse presents in phases, is there a particular stage when a person can look up safely?
Dr. G: When the moon is completely covering the sun from our view on Earth, that is known as ‘totality’, and it is actually safe during that time period to view the eclipse with the naked eye. This phase, however, is brief and we do not often see it, as we typically view only partial solar eclipses. Again, it is important to be educated on when it is safe to remove the filters, and when again to put them back on, so that we don’t damage our retinal tissue.
TT: How then, can a person safely look at an eclipse?
Dr. G: The safest way to view an eclipse is through properly certified ISO 12312-2 standard solar filters, known as ‘eclipse glasses’ or ‘hand held filters. Sunglasses and other filters are not adequate, even if they are polarized. There are a number of reputable vendors that supply these filters, including some local retail changes as well as online vendors and astronomy-specific vendors that can be located online. Home-made filters are also not adequate.
TT: Not looking at the sun for 2.5 hours might be hard to resist for some, so what advice does she have for the curious?
Dr. G: It is very important to be prepared. Although a solar eclipse may seem to be an eye-catching, unique and an interesting thing to experience firsthand, it is more important to protect the eyes when viewing a solar eclipse. Retinal damage and scarring can be permanent, and does not improve once it has occurred. There is no way to guarantee that the eyes will not be damaged other than to wear the proper safety equipment when viewing an eclipse. Protecting our eyes is a big job, but damage can last a lifetime and it is our duty to be proactive and prevent unnecessary decreases in our visual acuity.
TT: Dr. Geeraert convocated from the University of Waterloo in 2011, and has practised with the Trail Vision Care Clinic since 2013. The Trail Times asked if, during her studies and practice, Dr. Geeraert had firsthand experience with the matter?
Dr. G: Yes. When I was in school, one of my professors that taught us the optical properties of light was very invested and interested in eclipses and he actually did this exact thing. He showed us the images of his retinae and where it had been scarred. He was fortunate that it did not drastically decrease his visual function, but he did have to live with a compromised visual acuity. He was in his mid 50’s and had burned his retinas when he was in his 20’s. His vision had been damaged and no improvements occurred in those three decades.
Other tips from Dr. Geeraert include:
• Always inspect your filters before use; if they are damaged or scratched, discard them and replace them before viewing the next eclipse
• Always supervise children when viewing an eclipse – they do not know not to view an eclipse with the naked eye as well as we do
• You may look at an eclipse as long as you like with the proper filters over the eyes
• Do not use binoculars or other devices over the eclipse as it may damage them
• Glasses underneath the filters is okay