When it comes to sunglasses you can either choose between regular lenses or polarized lenses. While everyone has a vague idea that polarized sunglasses are better, very few people actually understand why.
To first understand why polarized sunglasses are superior, it is important to understand what regular lenses do and why they have a problem. Regular lenses only block UV light.
In regular conditions, light is reflected off polished surfaces and when it does so, it is reflected in horizontal light waves. Horizontal light waves are the ones that we perceive as light glares or flashes. They can become annoying and can obstruct vision. Regular sunglasses, do not block these rays of light thus not addressing this problem. Imagine being a driver and having the Sun right in front of you. Regular sunglasses will allow the light glares to pass through, reducing your ability to see ahead.
Polarized sunglasses use chemistry and optics to address the issue of light glare and flashes. Because these are concentrated only in horizontal light waves, polarized sunglasses use special lenses that block them. They do allow softer vertical light waves to pass. The result is a lens that reduces light glares considerably and protects your eyes from UV light.
If you own a pair of sunglasses but do not know if they are polarized or not, you can do some simple tests.
The easiest test is to stare briefly at the Sun. You will notice that it is much more bearable to look at and there are no glares. Another easy test you can do on polarized sunglasses is to put them on and look at your smartphone screen. You should then slowly rotate the smartphone and observe the colors on your screen. If the colors change as you rotate the display, then your sunglasses have polarized lenses. You can perform the same test in regular brick-and-mortar shops to see if polarized sunglasses are actually polarized.