When shopping for sunglasses, you might come across the option for polarized or non-polarized lenses. But what exactly does that mean?
What’s the difference?
Polarized lenses can be made with or without a prescription. They have a special chemical film applied to filter light differently than a normal lens. The chemical’s molecules naturally align in vertical striations. When the light bounces off a flat surface, it becomes horizontally polarized–that is, it’s travelling more uniformly in a horizontal direction. The molecules will filter out light that doesn’t match its alignment, so only vertically polarized light may pass through. Think of the process like venetian blinds over a window.
Normal sunglasses work by reducing the intensities of all light in the spectrum equally. Polarized are designed to reduce the selective horizontal intensities that cause glares. You can check to see if a pair of sunglasses are polarized or non-polarized by putting them on, focusing on a reflective surface, and turning your head slowly while looking at the same spot. If the intensity of the reflected light changes at certain angles, your lenses are polarized. If the intensity remains constant, they are not. When purchasing polarized sunglasses, be sure to do so from a reliable brand, as poor-quality ones may not effectively eliminate glare.
How do polarized lenses affect your vision?
Usually light scatters in all directions. But an annoying and sometimes dangerous glare occurs when light is reflected from flat surfaces, especially snow and water. If you are wearing polarized lenses, the images you’ll see will appear darker than usual, but the lines will be crisper and more detailed, and the glare will be drastically reduced.
Who should use polarized lenses?
Polarized sunglasses are particularly popular among people who partake in water sports, such as boaters and fishermen, and winter sports, like cross-country skiing. The popularity of polarized lenses has expanded in recent years for just about anyone spending time outside. They can be helpful for drivers as well because they reduce glare from road surfaces, rooftops, car hoods, et cetera. They have also proven to be useful indoors, especially for light-sensitive people who suffer from migraines or are recovering from cataract surgery.
Who should NOT use polarized lenses?
In some instances, polarized lenses are impractical. Downhill skiers, for example, wouldn’t want to block light reflecting off icy patches at the risk of encountering hazards that otherwise could have been avoided. For more common everyday use, it’s important to note that polarized lenses reduce visibility of liquid crystal displays (LCDs) or light-emitting diode displays (LEDs). This can cause vision impairments when looking at cell phones, laptops, tablets, GPS devices, ATMs, self-service gas pumps, and instrument panels, which can put pilots at an increased risk.
Are polarized lenses the right fit for you? If you haven’t tried polarized sunglasses before, give them a shot! You might be pleasantly surprised by how the world looks on your next beach day!