Polarized Sunglasses: The Best Choice for Sun Wear?

Woman jumping with sunglasses on
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Are sunglasses all the same as long as they provide shade? Absolutely not. Nothing provides a high level visual experience when outdoors in bright sunlight like a polarized sun lens. Polarized sunglasses are so popular because they provide the wearer increased visibility and performance when simply at the beach, or performing during intense athletic outdoor activities.

Before we realize why a high quality polarized lens provides a much better sun wear experience than just a tinted lens, however, we need to understand the qualities of light in general.

Back in high school or college physics classes, we learned that light can act both like a particle and a wave. Photons, a packet of light energy, can move in a certain direction, like a particle. However, while moving in that direction, it also can move up and down, giving light the quality of a transverse wave. Photons from the sun shine down on the Earth in all types of angles and directions. Some go directly into our eyes while others reflect off of surfaces such as water and highways. This unwanted reflected light and glare can cause distraction, decreased vision, and tremendous eye fatigue.

What Is Polarized Light?

When light photons hit a flat surface, the reflected light is said to become polarized. This means that it reflects in a horizontal direction only and becomes difficult to look at. This horizontal light becomes debilitating to the viewer. This is what most of us refer to as "glare."

What Is a Polarized Filter?

Polarized filters act to block polarized light. These filters block horizontal glare but also allow the vertical packets of light to be viewed clearly. This concept is similar to looking through horizontal blinds on a window. They allow enough light in to give you a clear view out the window but also block the unwanted light that degrades quality of vision.

A common example of how filtering polarized light can affect vision is in the case of an avid fisherman. Polarized light reflects off of the water, which virtually allows no view into the water. By eliminating this detrimental glare, the fisherman can see clearly below the surface of the water. Fish, plants, or rocks can be viewed in detail. Most fishermen are known to always carry high quality polarized lenses in their boat at all times.

Another common example that most of us can identify with is how we are affected by polarized light while driving. Polarized light while driving is an extreme hazard that we deal with on a daily basis while driving during the day. A polarized lens can eliminate the debilitating glare from the road and other oncoming cars while allowing a clear view of what is transpiring on the road. The metallic finish on cars is highly reflective. Once you combine this metallic reflectivity with rain, these surfaces reflect light in all sorts of directions. A polarized sunglass lens can allow the driver’s eyes to remain relaxed and unstrained and provide a much safer drive to work or school.

Disadvantages of Polarized Sunglasses

While there are not many disadvantages of polarized lenses, it is important to point out a couple of very important situations where a polarized lens is not recommended. First, a polarized lens is not recommended for pilots. The FAA (Federal Aviation Administration) recommends that pilots avoid wearing polarized sunglasses. A polarized lens can sometimes produce visual phenomena such as striations and rainbow effects when viewing through an aircraft windscreen. This can create obstructions when viewing other flying aircraft. Polarized lenses can also reduce light from other aircraft that alert other pilots they are nearby. The other reason why the FAA discourages polarized sun wear is because they can make it difficult to properly view instruments in the cockpit that incorporate LCD technology in a digital format.

For the general public, the biggest disadvantage is similar to the LCD problem in the cockpit. Certain phone displays, radio displays, and digital numbers at the gas pump will virtually disappear while wearing polarized lenses. An LCD display contains a polarized filter that when viewed at a certain angle, causes the display to turn black. You can simulate this effect by holding two polarized lenses together with one turned 90 degrees. They cancel each other out and block all light. While newer displays have incorporated technology that can be viewable from various angles, they can still cause displays to dim. This may be a concern for certain occupations which use digital displays daily.

Another cause for concern is for snow skiers. Polarized lenses can cut reflections from the snow, improving visual acuity. However, because reflections are almost eliminated, it makes it difficult at places where snow and ice texture change, causing great difficulty for skiers to navigate their speeds in slalom racing. A tinted lens is recommended over a polarized lens for snow skiers for this reason.

Albeit rare, there is a very small percentage of the population that does not adapt well to wearing polarized lenses. Sometimes, these people complain of being very disoriented and dizzy. Sometimes they complain that some objects have a 3D effect while wearing polarized lenses. For the most part, this is often due to the manufacturing process. Some patients have a difficult time getting used to wearing their new polarized sunglasses, but upon closer inspection, the optical laboratory is often to blame. Sometimes one lens is made properly, limiting horizontal light, and the other lens is accidentally made with the polarization situated so that vertical light is limited in the other eye. A good optometrist will be able to notice the mistake. 

Advantages of Polarized Lenses

For most of us, the advantages of polarized lenses far outweigh any disadvantages. Without question, they provide the wearer a better visual experience during outdoor, sun-exposed activities by reducing several distracting visual phenomena. First, they reduce “light scatter.” Scatter refers to visual noise where shorter wavelengths of light are polarized and crisscross over each other. Second, polarized lenses increase color saturation by increasing contrast of light and dark objects. Our world appears much more vivid than compared to only wearing a tinted lens or wearing no lens at all. To further improve the visual experience, high quality polarized sunglasses add an anti-reflective coating to the back side of the lens. This further improves vision by reducing reflections from objects behind us. It also reduces reflections of our own eyeball that sometimes can be seen while wearing the lenses.

Another advantage of wearing a polarized lens is that they reduce debilitating glare and light scatter, thus reducing general eye fatigue. They also provide visual comfort. Have you ever been driving for several hours in the sunlight and by the time you got to your destination, you felt exhausted and had to close your eyes? Much of that fatigue is caused by experiencing noisy light. Polarized lenses cause the eye to relax, reducing eye strain and making the wearer more comfortable.

Another often overlooked advantage of a polarized lens is skin and eye protection. Polarized lenses block UVA and UVB light and act like sunscreen for the eyes and skin around the eyes by blocking damaging higher frequencies of light. Polarized lenses will protect against photokeratitis (sunburn on the cornea) and reduce the risk for developing more severe cataracts and common growths on the eye such as pinguecula, pterygia and eyelid skin cancers.

What You Should Know

The bottom line is that for outdoor activities, high quality polarized lenses provide the very best visual acuity and visual experience. Colors appear rich and objects look sharp. Moreover, they can save your life by eliminating distractions while driving on a crowded highway in bright sunlight and days when it suddenly rains. Next time you consider sun wear, consider a polarized lens.

Source:

20/20 Vision, Sunvision, May 2016, Bennet, Alexander, Polarized Sunglasses: Everyone’s Most Important Piece of Equipment Outdoors

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