Polarized Lenses – What are they?
If you’ve looked into getting a new pair of sunglasses, whether for sport or fashionable eyeglasses, no doubt the option of polarized lenses has come up. But exactly what are they? How do they work, and what benefits do they provide over regular sunglasses?
From a technical point of view, polarized lenses are made with a special filter that blocks horizontal bands of light. The lenses are created by adding a layer of polyvinyl alcohol, stretched out to coax the molecules into long microscopic rows, and then treated with light-blocking iodine to create horizontal filters in the lenses. The end result is an effect similar to the way Venetian blinds block light coming through a window. While at first this may not seem that useful, it’s important to know that glare, the squint-inducing light reflected off of surfaces like car windows in summertime traffic, is transmitted in these same horizontal bands of light! In effect, polarized lenses block that glare, creating what I liken to a “cooling” effect on the eyes, allowing comfortable and relaxed eyesight.
Another added benefit: fisherman and boaters prize polarized sunglasses since they provide the ability to see details above and beneath the water, blocking out reflections from the water surface. Automobile drivers too like the way polarized sunglasses block out glare reflected off of cars, windows, even the road ahead. For general use, polarized lenses are virtually unmatched in providing more comfortable, clearer and even more detailed vision than with other types of sunglass lenses.
So, polarized lenses are just plain great, right? Almost, but there are a couple of instances where they may not be ideal. Skiers should definitely wear sunglasses or goggles to protect their eyes, and polarized lenses hit the mark in reducing the light reflected off the snow. However, as polarized lenses block horizontal bands of light, and skiers often descend more vertical terrain, polarized lenses may reduce a skier’s ability to see some different terrain contours on the steep slopes. One other factor worth considering with polarized lenses is found in viewing LCD displays. Seen through polarized lenses, LCD’s such as those at ATM’s appear rainbow-smeared or “tie-dyed”. This means you’ve got to remove your polarized sunglasses to see LCD displays properly.
Even with these limitations, polarized lenses are an outstanding sunglass option for most people. Typically an expensive eyeglass feature, polarized lenses can be found in Zenni’s clip-on sunshades, the magnetic clip-on’s of the Sunshade models or chosen as a lens option with Zenni’s inexpensive frames to create very affordable eyewear.
If you wear polarized lens sunglasses, you already know what great features they have, but if not, give them a try!
Example of a Sunshade models (frames 500318 and 587515 ) with polarized magnetic clip-ons:
http://www.zennioptical.com/500318-acetate-frame-with-polarized-magnetic-snap-on-sunlens.html