When sunlight strikes flat surfaces, the light reflected by those surfaces tends to become polarized and creates a beam effect that can be quite intense, making it difficult to see. Sometimes this is just uncomfortable or annoying, but in some cases the glare and decreased visibility can even be dangerous – especially when driving. Polarized sunglasses have a special filter that blocks this type of intense reflected light.
Think of polarized lenses as a tool for fine-tuning your vision while wearing sunglasses. They are especially useful if you are an avid outdoorsman, an active athlete, or find yourself in high-glare situations.
Before we dig into the benefits of polarized lenses, let's step back for a minute and focus on the most important reason for wearing sunglasses - UV protection. UV rays can be just as harmful to the eyes as they are to the skin. For that reason, it's very important to select sunglasses that have this protection.
But what about polarized lenses? Are they even safer? Not exactly.
While they do sharpen your vision in situations where glare can be distracting or even dangerous, they don't offer any additional protection from UV light. So in other words, they're not healthier for your eyes, but they do improve your vision for many outdoor activities.
How Polarized Lenses Work
Sunlight scatters in all directions. But when it strikes flat surfaces, the light that is reflected by the surfaces tends to become polarized - meaning the reflected light beams travel in a more uniform (usually horizontal) direction. This creates an annoying and sometimes dangerous intensity of light that causes glare and reduces visibility.
Polarized lenses have a special filter that blocks this type of intense reflected light, reducing glare and discomfort.
Brought to You by NASA
Polarized lenses were actually a brainchild from NASA Jet Propulsion Laboratory scientists who studied eagles' eyes to uncover clues about their exceptionally sharp vision.
What they found is that a naturally occurring oil in an eagle's eye controls certain properties of light scattering and limiting certain wavelengths.
Scattering, which you have experienced when light bounces off the surface of a lake, can really keep you from seeing things both above and below the surface. Eagles rely on the oil to overcome these challenges and maintain razor sharp vision.
Sharpen Your Vision in High-glare Situations
Scientists adapted this discovery to create special polarized filters that are applied to the sunglass lenses. These filters absorb light reflected or scattered from horizontal surfaces. We cal this glare and it can impede our vision especially in dangerous or fast moving situations.
Polarized glasses come in handy in high glare situations such as light reflecting off of roads, cars, or water.
So when you are picking out sunglasses, the first thing you should check for is UV protection. But if you drive, are active, or often find yourself on or near the water, you may want to pick sunglasses with polarized lenses also to give you the sharpest vision possible.