Fitness Blog-November 1, 2008-Vision Wellness: What you should know about polarized sunglasses

Taken from: http://www.spectacleworld.co.za/products05.htm

Imagine you are standing on the shore of a calm lake in early morning. What you see is a bright, glasslike mirrored surface on the water, with no detail, little contrast, and poor color saturation. As you slip on your polarized glasses, the bright, glasslike mirror is replaced with a scene that shows detail and has deep colors and good contrast. That’s what polarized lenses can do. Photo-graphers use them to add bolder colors and deeper contrast to their photographs. The polarized lenses remove the glare and improve the visual quality of the picture, much the same way polarized ophthalmic lenses perform for the patients who wear them.

Polarized lenses are made from a special polarizing film that is applied in the factory on the front surface of the lens. This film allows light rays to be filtered, consequently improving the vision in strong light conditions. Polarized lenses will protect you from UV rays, glare and intense light. In combination with a reflection-free coating, polarized lenses are ideal for fishing and driving.

Polarized Sunglasses
For years, boaters and fishermen have used polarized sunglasses to reduce glare from the water that they spend so much time on. In the past few years, however, the benefits of polarized sunglasses have been realized by a variety of other outdoor sports enthusiasts as well as by drivers and general use wearers. The popularity of polarized lenses has increased dramatically, as has availability.

Besides boaters, people that benefit most from polarized sunglasses include skiers, golfers, bikers, and joggers, who enjoy a clearer view and elimination of glare.

These sunglasses can be used for driving and in fact can reduce the glare that comes off a long, flat surface such as the hood of the car or the surface of a road. Polarized sunglasses can also be used indoors by light-sensitive people such as post-cataract surgery patients or by those exposed to bright light through windows.

How Do Polarized Lenses Work?
Light reflected from surfaces like a flat road or smooth water is generally horizontally polarized. This horizontally polarized light is blocked by the vertically oriented polarizers in the lenses.

The result: a reduction in annoying and sometimes dangerous glare. There is some debate on the effects of polarized lenses on snow-covered surfaces. Some experts say they can reduce the intense glare that is caused by sunlight reflecting off snow.

Others purport that the lenses are not satisfactory for sports such as downhill skiing because they may not provide the contrast the eye needs to distinguish ice patches or moguls. In addition, polarized lenses may also react adversely with liquid crystal displays (LCDs) found on the dashboards of some cars or in other places such as the digital screens on automatic teller (bank) machines. The problem with LCDs is that when viewed through polarized lenses from a certain angle, they can be invisible. (This is how you can check if it can be a real or a fake polarized sunglass)

However, for most other sports and activities, polarized sunglasses can offer great advantages. And today, many types of polarized lenses are available on the market.
Whether you spend your time boating or waterskiing, inline skating or mountain biking, driving or jogging, polarized sunglasses are an excellent choice.

Understanding Polarized Light and Polarized Lenses
While they enjoyed only limited use among optical professionals for many years, polarized lenses have become the first choice for anyone interested in a comfortable and attractive sun lens.
The principle of polarized light reduction is best illustrated by thinking of a polarized lens as a Venetian blind. The blind blocks light at certain angles while allowing light to transmit through selected angles. Polarizing filters are aligned 90° to the angle of the polarized light. As spectacle lenses are designed to eliminate the polarized light in the horizontal plane, the filter is placed vertically in the eyewire or eyerim. This means that the filter must be properly aligned during surfacing and edging layout, otherwise the filter will not work properly.

 

Tint vs. Polarized
Although darkly tinted sunglasses may reduce brightness, they do not remove glare like a polarized lens. In addition, dark sunglasses without added ultraviolet protection may cause more damage to the patient’s eyes than not wearing sunglasses at all. The darkness of the lens can cause the pupil to dilate, letting more ultraviolet rays into the inner parts of the eye. Polarized lenses solve both problems by eliminating glare and filtering out harmful ultraviolet light because the filter reduces the polarized glare and also has ultraviolet absorbing properties.
Today’s polarized lenses represent the best sunwear and outdoor lifestyle options available. With a little explanation and demonstration on your part, your patients will enjoy the benefits of these lenses for years to come.

Advantages of Polarized Lenses

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