Q: I have used regular sunglasses all my life, but recently bought “polarized” sunglasses. They seem to do a lot more than just darken sunshine…..how do they work?
A: Glad to hear that you are enjoying your new polarized lenses, and indeed, they do a lot more than just darken your view of the world. This is a bit complicated, light from the sun actually comes to us as waves in 360 degrees. Hard to imagine, but think of a rope held between two people that move it up and down at opposite times….it is waving in one direction or one plane, usually just up and down. Light waves are like that, but they are waving in all directions at once! Imagine that rope waving up and down, then side to side, then on an angle, and so on……..but happening all at once!
Whenever sunlight strikes a surface, some is absorbed by the surface material and some is reflected. How much of each occurs depends on the surface. Smoother surfaces reflect more, while rougher surfaces reflect less. The most reflection likely comes from smooth water, which is why people fishing have long favored polarized lenses to see better down into the water, not just the surface.
The reflected light from a smooth surface is called “polarized light”. This means that only light waves in one direction, or one plane, is actually bounced off the surface. All the other waves are absorbed by the surface. Here is the “magic” of polarized lenses…..they absorb only the polarized light waves! The reflected light waves are actually what we would describe as “glare”. So your new polarized lenses are absorbing the reflected light, absorbing all the glare, and allowing only clear non-glare light through.
So yes the view we get through polarized lenses is darker, but more importantly, the glare has been removed. The result? Our vision is much, much sharper and more comfortable than with merely darker lenses. Because we do get a lot of reflected light from the highway and other vehicles….especially when driving into the sun…..erasing the glare gives us much sharper and safer vision for driving. Many accidents are due to “blinding glare” causing drivers to not really see the hazard in time to react.
Here is a fun way to “test” your polarized lenses: take them off and hold out in front of your eyes about a foot away. Hold them in the same way they sit on your face…..horizontally. While holding this way notice that any reflected light or glare on a surface in the distance is blocked. Then rotate your glasses ninety degrees..... to the vertical position. What do you see? All the glare comes back! They only work when you look through then in the horizontal position…..just the way they sit on our nose!
Eliminating blinding glare gives us better, safer driving vision. We generally recommend and prescribe polarized sunglasses……with the patient’s vision correction….in addition to regular indoor lenses. Most people, once they have this option, simply love their vision!