You probably already know that sunglasses protect your eyes from the sun's damaging rays, but not all glasses are created equal. So, what should you look for in a great pair of sunglasses? Can you still look fashionable while properly protecting your eyes? What does UVR mean? Should you buy wrap arounds? And what does polarization mean?

UVR and Sun Protection

If you're going to look good while wearing sunglasses (and really, would you wear a pair that make you look horrible?), it should protect your eyes to the max at the same time. UVR means ultra-violet rays, and if you've ever watched any sort of weather report, you'll have probably seen the term UV index.

The light you see from the sun is composed of an entire range of rays. The visible rays you see is just a small component. UV rays are invisible that is, they are at a spectrum beyond the range your eyes can see. The sun's spectrum has a range from weak to strong radiation, with infra-red weak, visible light normal, and UV rays strong and damaging. Anything above visible light can cause premature wrinkling, skin cancer and, in the eyes, cataracts, retinal damage, and eyelid cancer. There are rays even stronger than UV, but the earth's atmosphere completely blocks them nothing on earth would survive if they got through.

With that in mind, do sunglasses block UV rays? You bet! However, some do not completely block them, and it might not be related to price. Tests have found that a $1 pair of sunglasses could block out 100% of the sun's UV rays, while a $300 only blocks 95%. Fortunately, there is an industry standard, called ANSI, and sunglasses at least 99% effective will be labeled Meets ANSI UV Requirements. Another measurement you might see is protection up to 400 nm, which is the measure of the sun's wavelength in nanometers. Ultraviolet rays are between 380 200 nm. The smaller the number, the more hot and dangerous the rays are. (Now you know why that little appliance in your kitchen is called a microwave!) If you're unsure about the protection of your new pair of sunglasses, simply go to most optical stores, where an employee can use a photometer to test their blocking properties.

Wrap-arounds offer the best UV protection, for they block the rays from entering the sides of your eyes. They have a very curved lens, and you will often see them as one solid piece curving from one side of your head to the other. It's a very slick, sporty look. However, because of their special construction, you won't be able to get them in a custom prescription.

Does the Color of the Lens Determine Sun Protection?

No. They are purely cosmetic. UV-block on the lens is mainly an invisible coating. However, they do distort visible light, and when used on high-end, specialty sports sunglasses, this color distortion allows greater clarity while participating in extreme sports. Below is a quick list of how the color affects you:

• Gray: no color distortion, great for everyday use
• Brown: High contrast and depth perception, slightly distorts color
• Yellow: High contrast, but creates harsh visible light
• Green: little color distortion, some color contrast, excellent for everyday and sports use
• Blue: Best for skiing as it filters the white, but also causes large color distortion
• Pink: Great for viewing computer screens, but causes large color distortion
• Vermillion (purplish-red): Best for water sports, but huge color distortion

These sunglasses block the glare. They have been used by pilots and fishermen for years, and were specifically developed for American pilots in World War II. On a sunny day, sunlight hits a flat surface like snow, water or pavement, and bounces back up into your eyes. Because the light is so concentrated, it can be quite painful over long periods, and is the cause of snow blindness. Lens treated with polarizers block this light, reducing or completely eliminating this glare.

If you're spending a long time on the bike trails, driving, playing watersports, inline skating or simply jogging, polarized sunglasses will greatly help. Be aware, though, that LCD displays use a similar light technique, and so they will be invisible in polarized lens if seen at a certain angle.

In the last few years, different types of polarizers have been developed for certain sports, after research on how the light bounces off different surfaces. Thus, you'll now see sunglasses specifically for skiing, biking, golfing, driving and boating.

Now You Have the Knowledge!

With your newfound knowledge, it's time to find those perfect pair of sunglasses. Using them for simple everyday fashion or for a specific use like driving or golfing? You now know what to browse for. Look cool, and protect your eyes at the same time!