Every summer, you hear the same thing: protect your eyes with sunglasses. It’s not just about comfort. It’s about filtering out harmful ultraviolet rays from the sun. Wearing sunglasses that offer 100%UVA and UVB protection could save you from cataracts, AMD, and other eye issues.
But of course, not all sunglasses are created equal. And as you’re shopping around for a good pair of sunglasses, you may notice pairs are advertised as “polarized.”
Is polarization the same as filtering UV light? Are polarized lenses better than other sunglasses? Should I invest in polarized lenses?
Let’s take a look at what exactly polarization means and whether polarized lenses are an option for you.
Ultraviolet light is a type of radiation that’s on the very end of the visible light spectrum. In the short-term, too much UV light can cause dryness, eye strain, or even temporary blindness (like snow blindness). In the long-term, too much exposure to UV light increases your chances of developing eye diseases like cataracts and macular degeneration.
Quality sunglass lenses and even some clear prescription lenses come with a UV coating, which absorbs ultraviolet light. This absorption prevents ultraviolet light from reaching your eyes and contributing to long-term damage.
Polarization is actually a very different process from ultraviolet filtering. In fact, on its own, the process of polarization will not protect against ultraviolet light. Instead, it reduces glare.
All light frequencies vibrate. Most light, such as sunlight, vibrates in all directions. However, when light bounces off a horizontal surface like pavement or the roof of a car, it only vibrates horizontally.
This horizontally reflected light is concentrated and can cause problems with glare, which can be quite disabling.
Polarized lenses are treated with a coating that absorbs visible light. The chemical is applied in a sort of vertical stripe pattern. As a result, some vertical light can pass through, but horizontal light is blocked.
Imagine this: you might be able to get your couch through your front door if you carry it through length-wise. But if you were to try width-wise, the door would be far too narrow to let you through.
That’s essentially how polarized lenses work. Any glare from horizontal light is unable to penetrate the vertical filters.
We understand now that polarized lenses reduce glare, allowing for more precise vision and less eye strain.
You can wear polarized sunglasses nearly any time you wear your normal UV filtering sunglasses. Athletes and hobbyists, in particular, find them most beneficial for activities like:
It’s worth noting that polarized sunglasses are not the best option for every activity. Many digital displays like phone screens and GPS screens emit horizontal light, which isn’t visible through polarized lenses.
If you like to spend a lot of time outside on the water or in the snow, you should absolutely invest in polarized lenses. You could also benefit from polarized sunglasses if you do a lot of driving or road work.
Ultimately, everyone could benefit from polarized lenses sometimes. If possible, it’s an excellent idea to have both polarized and non-polarized sunglasses so you can enjoy the benefits of polarization when appropriate.
Whether you wear polarized sunglasses or not, UV protection is really the most important thing. Invest in quality sunglasses with at least 100% UVA and UVB protection, and make sure you have them with you when you go outside. It could preserve your vision for years.
DR. KEVIN HESTERMAN
Dr. Hesterman was born in Regina, Saskatchewan. He graduated from optometry at Waterloo in 2000. He and his wife, Rhonda, have three children. He enjoys swimming, biking, and running, having completed several triathlons. Hiking, skiing, and playing the piano and guitar are other interests. He has volunteered with Big Brothers and Big Sisters and was on the executive committee for Optometry Giving Sight, a charity raising money for third world optometry. Dr. Hesterman is currently on the executive council for the Alberta Association of Optometrists.