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Sunglasses and Your Eyes

We are frequently advised to wear sunglasses, but we are rarely told why.  We all know that sunglasses are “good for our eyes” but we don’t know what the Sun does to our eyes that’s so bad.  And what should we look for in sunglasses to get the maximum benefit from wearing them?  Read on to find out!

Sunglasses Protect Against:

Cataracts

Our eyes have 2 lenses: the cornea, which is in front, and the crystalline lens behind the iris (the colored part of the eye).  Cataracts are a progressive darkening of the crystalline lens.  They are the leading cause of blindness in the world.  Fortunately, sight can be restored with surgery.  Most people think cataracts are due to age, but that may be somewhat of a coincidence.  Ultraviolet (UV) light exposure seems to be the primary cause of cataracts and older people develop cataracts simply because they’ve had greater lifetime exposure to UV light.  Sunglasses block the UV rays that cause cataracts and have been proven to delay, and perhaps prevent, their onset.

Eye Yellowing

UV light is a primary cause of progressive yellowing and/or reddening of the white part of the eye.  Too much sun exposure irritates the eye and causes it to grow a new layer of tissue as a form of protection.  This tissue has a yellow, fatty appearance.  It also grows its own blood vessel supply that can cause chronic redness.  This tissue is referred to as a pinguecula if it is only over the white part of the eye and a pterygium if it grows over the cornea.  Sunglasses can slow or prevent the growth of these tissues.  If you have developed a pinguecular or pterygium, they can be reduced with prescription eyedrops and, if necessary, surgery.

Macular Degeneration

Macular Degeneration causes the loss of central vision:  the vision you use to read, recognize faces, and see detail.  It affects the macula, which is the center of the retina, the part of the eye that detects light and sends signals to your brain.  Macular degeneration is the leading cause of irreversible blindness in the United States.  While there are many factors, including genes, age and nutrition, that cause macular degeneration, protecting your eyes with sunglasses can slow its onset and progression.  Recent discoveries in drugs and nutritional supplements have also been proven to help prevent or delay blindness from macular degeneration.

Desirable Sunglass Features:

Ultraviolet Protection

Ultraviolet light (or “UV”) represents the rays that are the most damaging to the eye.  UV is divided into three ranges based on its wavelength, A, B, and C.  Good sunglasses must block all three.  Many sunglasses have a sticker that says “UV400,” which means they block 100% of all types of UV light.  The “400” refers to the wavelength, in nanometers, where UV-C begins (now you know).

Darkness

The darkness or density of a lens has no impact on how well it blocks UV light. Even lenses that are completely clear can be easily made to block 100% of UV.  So how dark a lens should be is mostly a matter of personal comfort and what you intend to use the lens for.  Most sunglasses block 85% of visible light (and 100% of UV).  But we often make lenses that block 50% light for general use or even 90% for people who are particularly sensitive to light.  Indoors, 30% darkness lenses are often greatly appreciated by computer users, people who work near windows, or people who are bothered by fluorescent lights.  Transitions® lenses are also very popular.  They are naturally transparent but get dark in proportion to the amount of ambient UV light.  So they are clear indoors but get dark outside, and they always block 100% of UV.

Color

As with density, the color or tint of a lens is mostly a matter of comfort and what you intend to use the lens for.  Gray lenses are the most popular and can be used for almost any application.  The dark green that was made famous by Ray-Ban® is still very popular, too.  Skiers like yellow or orange lenses because they eliminate glare from the sky and make contours in the slopes more obvious.  Golfers often appreciate amber or brown lenses because they make the ball easier to see both in the air and on the green.  There are also popular colors for fishing, computer use, shooting, hiking, sports, driving, and so on.  Ultimately, it comes down to personal preference, but our staff are trained and equipped with many samples to help you decide.  [perhaps I should make a little table with different colors and the applications they are well-suited for]

Polarization

Polarized lenses cancel out glare in a truly impressive fashion.  The classic example is water: with polarized lenses on, you can see straight through the surface at the fish and other wonders that lie below.  But it also makes driving a much more pleasurable experience.  Glare that you didn’t even realize bothered you—from windshields, bumpers, the sky, and even the road—disappear and give you crisp, comfortable vision.

Anti-Reflective Coatings

Do you ever notice reflections of your face or things behind you when you wear your sunglasses?  Do you feel compelled to put your hand on your forehead, like a visor, when you face the sun with your sunglasses on?  Putting an anti-reflective coating on the back of your glasses lenses eliminates these types of glare and makes wearing your sunglasses much more comfortable.

Sunglasses are important for your comfort and the long-term health of your eyes.  Selecting good lenses with the right features can not only protect your vision, but make your activities more fun.
Remember: never look directly at the Sun, even with sunglasses on!  It can cause permanent eye damage in seconds.