Polarized Sunglasses: What for?
One of the most frequent questions I am asked when discussing sunglasses is why polarize my lenses? What is this for? What will it do for me? While there are many pros to wearing polarized sunglasses, there are certain cons as well. Considering what activities you participate in and your environment is a key factor when deciding if polarized lenses are for you.
Fact: Sunglasses are no longer just an accessory, but an essential piece of equipment. Long-term effects of UV exposure to the eye can result in cataracts, pingueculae, pterygia, skin cancers, and definite damage to the eye. Not only do your sunglasses help protect your eyes from damaging UV light, they also help protect the bones forming your eye socket from projectiles. According to the National Eye Institute, approximately 800,000 eye injuries occur in the United States annually. It is estimated that 90 percent of these injuries could have been prevented with proper eyewear. Think of sunglasses and polarized lenses like this - we wear sunscreen to protect our body from sunburn and we should wear sunglasses as sunscreen for the eyes.
Ultraviolet light is invisible electromagnetic radiation outside the human visible spectrum. Light can act as both a particle and a wave. When sunlight reaches the earth from the sun, bundles of light are received at all angles. Some of this light is received directly by the eye whereas some light is reflected off of surfaces like roadways, water, ice, etc. When a bundle of light hit a flat surface it becomes polarized. This intense reflection is commonly referred to as blinding glare. While reflections can be uniform (such as the reflection off of the road or on a car's hood), reflections can also be non-uniform (such as on a changing surface like running water or patches of ice). The purpose of polarized sunglasses is therefore, to filter out distracting reflected light.
Whether you are an athlete hoping to perform your best without distraction or just the average consumer taking a hike, driving down a sun light road or relaxing with a good book on the beach, polarized sunglasses can eliminate that glare causing visual discomfort. Other advantages of polarization is it can create a better visual experience during daytime activities. The Raliegh Effect is the scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation. Polarized lenses remove reflections in the form of scatter or "visual noise". Another advantage to these type lenses is the increase of color saturation, causing environments to look more vivid (vibrant and darker colors). By eliminating blinding glare, polarized sunglasses provide visibility otherwise hidden. This is important for spotting debris and road imperfections possibly on a bicycle, motorcycle or while driving a car. Depth perception and horizon differentiation is improved due to this filtration. For most of us, polarized lenses help to reduce eye fatigue from long term viewing of "noisy light". Relaxing the eye and making the wearer more comfortable.
Disadvantages of polarized lenses vary depending on the wearer. The Federal Aviation Administration advises pilots again wearing polarized sunglasses due to the striations and decreased visibility through aircraft windshields. Some skiers prefer tinted lenses instead of polarized lenses due to reduced visibility of ice. Since reflections are eliminated, skiers might recognize ice until it is too late. To the average consumer, the largest drawback is the disappearance of LCD screens like smartphones, car gauges, radio displays, and gas pumps while wearing polarized sunglasses. Despite these cautions, the advantages of wearing polarized sunglass lenses outweigh the disadvantages. It is important to consider overall use and lifestyle in order to make the most appropriate decision concerning your choice in lens selection. Polarized or non-polarized, UV protection of the eye essential for all of us.
(Information gathered from SunVision 2016, Polarized sunglasses: Everyone's most important piece of equipment outdoors by Alexander Bennett).