Why So Many Insist on Wearing Polarized Sunglasses All Year

A pair of polarized lenses will ease eye strain and instantly improve your visibility.

Fashion statements aside, we know that wearing sunglasses with UV protection is vital to shield against damaging UV rays. To further protect our eye health, many people insist on sunglasses with polarized lenses that reduce glare and ease eye strain. But why is that exactly, and is polarization a feature you could benefit from?

A polarized lens acts like a filter or lattice which only allows the useful light traveling from the object viewed to reach the eye, while blocking all the glare caused by the scattered light traveling in many random directions. Objects then appear sharper. Colors are more vivid and in true natural proportion due to the removal of scattered white light.

Regular sunglasses, regardless of the cost, are only colored plastic or glass and cannot block out glare. These ordinary sunglasses just reduce the amount of visible light the eye sees, but the problem of glare still remains. Austin Diagnostic¹

By choosing polarized shades, you're improving what you see and giving your eyes a break any time there is light bouncing upwards into your eyes. That means any activities or situations where light is being reflected off of snow, water or even asphalt – including driving, fishing, skiing, and snowball fighting. 

In order to understand when it's important to wear polarized sunglasses, you can think about how the polarization is actually working to filter light:

A polarized filter passes only the light that does not match its orientation. Most of the glare that causes you to wear sunglasses comes from horizontal surfaces, such as water or a highway. When light strikes a surface, the reflected waves are polarized to match the angle of that surface. So, a highly reflective horizontal surface, such as a lake, will produce a lot of horizontally polarized light. Therefore, the polarized lenses in sunglasses are fixed at an angle that only allows vertically polarized light to enter. How Stuff Works²

To check that your sunglasses are polarized, simply tilt your head at an angle while looking at your computer monitor or phone; the screen will appear to darken on most devices if you're looking through polarized lenses:

It's important to note that not all screens behave the same — a true test of polarization³ would be to verify that light is blocked by the lenses of two pairs of sunglasses overlapped at a 90º angle (in this case, you need two identical pairs, or one is already known to be polarized).

Because glass is treated in different ways for various applications, this also explains why you may notice a rainbow, stripes or checkered pattern when looking through car windows through your polarized pair:

What you’re experiencing is just a simple matter of physics. Many rear and side car windows are tempered. What you’re seeing when you notice a checkerboard or rainbow pattern in a car window is an effect called stressed birefringence. Stress on optically clear materials often produces birefringence, which basically means that the material changes the polarization of the light. Revant Optics⁴

In fact, the only time polarized lenses aren't recommended is if you're a pilot since visibility of gauges and instruments that use treated glass can be affected. Otherwise, polarized sunglasses are a popular choice for good reason! This is why all styles of MagLock Sunglasses feature polarized lenses for enhanced eye protection from sea to snow. 

Sources:

1. Austin Diagnostic Clinic: "Why Choose Polarized Lenses for your Sunglasses."
2. How Stuff Works "How Sunglasses Work: Polarization."
3. Lifehacker "Find Out if Sunglasses are Polarized by Looking Through Two Pairs."
4. Revant Optics "Why You're Seeing Rainbows In Car Windows."