What are Polarized Sunglasses?

I have found throughout my many years in this industry that many patients still do not have a clear understanding of the difference between a tinted and a polarized sunglass. So, the big question you’re probably asking yourself is, “why do I want over another?”
For the vasty majority of patients, the polarized makes more sense. I hope to explain why here.

Tinted Vs. Polarized – Why one over the other?

The two ways a sunglass lens can be created are vastly different. Tinting is perhaps a bit more straight forward and easier to understand, so I’ll address this first.

When tinting a lens, we start with a perfectly clear lens, and dip it into a hot dye until we get to the color, density, and pattern you desire. The advantage on a tinted lens is that it can be as dark or as light as you’d like. It can be gradient or solid, and it can be pretty much any color under the rainbow (including having mixes of color).

TintedGradient

Gradient Tinted lenses

Based on the above, it sounds like a tinted sun lens is the smartest way to approach it, right? I mean, why discuss anything else??

But what does tinting do for glare? That is the question…and that question is answered with polarized lenses.

Polarized lenses are created in a completely different fashion. There is actually a film sandwiched inside the clear lens (for most versions of polarized…see Maui Jim below). This film is actually made of thousands of microscopic lines packed so closely together they give the appearance of color. These lines are placed so closely together to handle the glare.

polardemo

microscopic lines in a polarizing film removed out-of-phase wavelengths of light

How Polarized Works

Polarized lens technology takes advantage of the wave nature of light. When light reaches us from the sun, it folows a unifom wave pattern, wherein all the light is in phase–that is to say all the wavelengths of light are in the same plane. When the light hits a surface, it scatters in multiples angles, creating the flare of glare.  This is where the polarized film in your sunglasses comes in.  All those lines, packed so tightly together, prevent all the scattered light from passing through the lens.  Only the original wavelengths, continuing in their original straight path, are let through.  This dramatically reduced the reflected glare and increases visual comfort, even on a lens with less tint.

Sounds great right?  You must be asking yourself, “Whats the catch?” Well, I wouldn’t call it a catch, but there are a couple of things to be aware of with polarized lenses.  LCD displays use polarized film to work.  When two polarizing films are set 90 degrees apart, all visibility is blacked out.  So this means, if you look at a digital calculator, as an example, it could be black and impossible to see any image displayed.  This is rare, and can be fixed by tilting your head slightly.  In my experience, there can be issues with clarity on the LCD displays for some cars (i.e. BMW’s from the early 2000’s).  This can include your odometer or even your GPS navigation system.  Pretty much all smart phones post version 5 (iPhone, Galaxy) this is a non issue.  But the older devices can have a soap bubble appearance.

Is Polarized Right for You?

For the vast majority of patients, Polarized lenses will be more comfortable and functional. But there are some lifestyles, and work environments where polarized lenses don’t make a lot of sense.

  • Pilots: you’d think this was a perfect case for polarized making sense, but the Shatter resistant windscreens of planes can create tremendous rainbow distortions which are only clearly visible when looking through a polarized lens.
  • Photographers:  The viewfinder on most SLR and DSLR cameras are LCD, which can have terrible rainbow distortions when viewed through a polarized lens (think of the earlier example of soap bubbles).
LCDPolar

LCD through Polar

Maui Jim polarized lenses are a little different in that their polarizing film is fused directly into the lens so delamination is a non-issue and colors are enhanced in a substantial way.  I have worn polarized lenses from at least a half dozen lens manufacturers and I always fall back on Maui Jim’s as my go-to pair–even when the prescription is out of date.

mj-3719-mauibrilliant-web-612x612-r1.png

Take Away

Polarized lenses dramatically reduced your perception of reflected light/glare while wearing them.  The technology does allow you to see chromatic structures and other things not normally visible with the naked eye.  This is less of a problem, than something to be aware of, and to know how to get around it.  While polarized lenses make the most sense for most patients, there are subsets of the population where polarized just doesn’t make sense, such as photographers and pilots.

UPDATE

A couple of comments I’ve received led to this note. Since there is an angle to the Way polar film removes glare, both eyes must be on the same angle, or plane. If they are off, they can give you a very odd sensation. In fact, 3D glasses work by having the polar film at 90 degree angle to each other, giving each eye a different image to create the 3D effect. If you have inexpensive sunglasses you can sometimes get this experience.


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3 thoughts on “What are Polarized Sunglasses?

  1. Pingback: 3D Glasses. How Do They Work Anyway? | The Optical Jedi: a guide to the mysteries of glasses

  2. Pingback: Questions on Light Sensitivity | The Optical Jedi: a guide to the mysteries of glasses

  3. Pingback: Review: Maui Jim High Contrast Lens | THE OPTICAL JEDI: A GUIDE TO THE MYSTERIES OF GLASSES

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