How Do Sunglasses Function?

We all know that sunglasses are important to protect our eyes from the sun's damaging UV rays and maintain eye health.  But have you ever thought about how these tinted lenses can do that?  Beyond being a fashion statement, sunglasses essentially provide four benefits.  It is helpful to know what these benefits are and how they are accomplished to be certain your sunglasses are doing their job.

As you no doubt already know, sunglasses provide protection from ultraviolet rays in sunlight.  UV rays can induce serious damage to the corneas. A good pair will block 100% of ultra violet rays.  A protective coating on the outside of the lenses acts as a filter.  While it allows visible light through, it filters out the high frequency light waves that can lead to so much damage to your eyes and vision.

Possibly the most common reason to wear sunglasses is to protect the eyes from intense light. Strong sunlight will cause you to squint, which is an automatic reaction to too much light entering the eyes.  If squinting does not provide enough protection, damage to the cornea can occur.  This is especially common when outdoors in the snow without sunglasses.  The bright white of the snow reflects and magnifies the intensity of the sunlight.

The tinting of your lenses will determine the amount of light reaching your eyes.  As there are as many wavelengths of visible light as there are colors of the rainbow, different shades of lenses will block different wavelengths.  Gray and almost black tinted lenses will offer the greatest protection from intense light while minimizing most color distortion.

Another benefit  of wearing sunglasses is protection from glare.  Water and other reflective surfaces can produce glare.  This glare can obscure other objects, like a car turning out of street just in front of you.  Good quality sunglasses can completely eliminate this kind of glare by using polarization.

Light waves vibrate just as sound waves do.  When a group of light waves come together but are scattering in different directions, a glare occurs.  When you are blinded by light glaring off of the water or another car's windshield, you are seeing a traffic jam of light waves.  Polarization filters built into lenses are made up of molecules that realign the light waves to eliminate the glare.

As noted before, Sunglasses can reduce or eliminate specific frequencies of light. Certain light wave frequencies can cause blurred vision, while other frequencies will enhance the contrast between colors. Selecting the right color for your particular activity and need will produce the best results

Yellow, gold, amber and brown tinted lenses are especially good for blocking blue light.  Blue light causes the most light scattering and causes blurred vision.  While the yellow shades will make the world look a strange color, you will see more clearly and in better detail.

Green tinted lenses are better for filtering some blue light and reducing the occurrence of glare. They also offer the highest contrast and greatest visual clarity of any other colored lens.  Because of this feature, green lenses are very popular.  Rose and purple tints offer the best contrast of objects on a green or blue background and make excellent sunglasses for hunting or water sports.

Now that you know how sunglasses work you can be a smart consumer.  You will know what to look for when shopping for your sunglasses.  It is a good idea to have more than one pair for different uses.  This is particularly true if you spend a lot of time outdoors with various activities.  Be responsible about your eye's health and learn to protect your vision.