Things you'd want to know about your lenses are presented in this order:

Lens Materials
Polycarbonate | Trivex | Glass | CR-39 Plastic | SR-91 (new)

Lens Coatings & Treatments
Polarization | AR or Anti Reflective Coatings | Flash & Mirror Coatings | Photochromic


Lens Materials

Polycarbonate:
Polycarbonate is virtually indestructible, and it is used exclusively by many of the world's finest sports glasses manufacturers. It is thinner, lighter, and stronger than glass. What's more, polycarbonate lenses can survive a 12-gauge shotgun blast from 10 yards away. (Warning!: If you try this at home, take the glasses off first.)

Polycarbonate naturally blocks almost all of the sun's harmful UV rays. No coatings are required to block UV rays on a polycarbonate lens, so don't let anyone sell you this option.

The strength of polycarbonate is partially derived from its flexibility. It is not brittle and will not shatter. This strength also contributes to its main weakness. Because polycarbonate is so flexible, it is also easily scratched. New lens coatings and hardeners have significantly improved polycarbonate's durability, but choosing a polycarbonate lens still requires an informed consumer. Quality lens treatments match the refractive index of the lens material and allow light to pass directly through. If light passes through the lens coating and the lens at two different speeds, vision will be blurred.

Every lens we offer is manufactured to improve vision. Our customers are never at risk of getting stuck with substandard eyewear.

Trivex:
Trivex is a new lens material that is quickly becoming the best thing that has ever happened to sports eyewear.  Originally developed for military applications, Trivex is stronger, clearer, and lighter than polycarbonate. Most importantly for sports applications, Trivex minimizes distortion called "chromatic aberration", which is distortion that occurs when objects are viewed away from the optical center.

Chromatic aberration is best measured by its "Abbe value." In prescription eyewear, a higher Abbe value indicates less distortion as your gaze moves away from the center of the lens. Trivex has an Abbe value of 43, while polycarbonate has a value of 30.

Trivex naturally blocks 100% of the sun's harmful UV rays, similar to polycarbonate. Trivex has better scratch resistance than polycarbonate.

Trivex has only been available to the general public since 2003, and is still not offered by most manufacturers as a lens choice. We offer Trivex as an option in most prescription lenses. Trivex is usually about $25 to $40 more expensive than polycarbonate. If you are ordering prescription glasses and you don't see Trivex listed as an option, give us a call or send an email to inquire about its availability. We are able to fit Trivex into more applications everyday.

Trivex is not currently available for large wrap frames like Panopx, or other motorcycle sunglasses, but it is available for any of the RecSpecs safety glasses.

Important note about scratched lenses:
If you scratch a polycarbonate or Trivex lens, you must choose one of two options. If you bought the glasses from us, send them back. We can usually replace the lens. If you can't replace the lens, THROW THEM AWAY! Polycarbonate and Trivex have amazing strength, until they are scratched. Once they are "scored" they lose their ability to protect your eyes. This is analogous to a carpenter using a razor knife to scratch, or score, a vinyl floor tile. As soon as he pops the tile over a straight edge, it will easily break along the scratch. Polycarbonate and Trivex will respond in a similar manner if a scratched lens receives an impact.

These are the two strongest lens materials in existence, but they are still not indestructible. Of the two, Trivex is stronger and more scratch resistant.

Glass:
Glass lenses provide excellent scratch resistance and clarity. They are also about 40% heavier than polycarbonate or Trivex. Unfortunately, glass is not shatterproof.

If impact could be an issue, glass lenses are not the best choice. Serengeti makes some impressive driving glasses with glass lenses, but none of our action-sport glasses come with glass lenses.

CR-39 Plastic:
CR-39 is the most frequently used lens material in prescription eyewear.  It is the least expensive, and it works fine in environments that are isolated from sports related impact.  For this reason, we hardly ever use it.  CR-39 lenses are fine for driving a car, lounging on a beach, or watching a sporting event.  But if you are an active participant in any sporting event you need a quality polycarbonate or Trivex lens in front of your eyes. 

SR-91: (New)

SR-91® is the perfect lens material for any sports eyewear.  The optical clarity surpasses every other lens material on the market; the strength is amazing; it is more scratch resistant than polycarbonate or Trivex; and it weighs almost nothing!  All SR-91 lenses are polarized to eliminate glare, and they block 100% of UV rays and Blue Light.

When we first heard about the strength and clarity of SR-91 we were a little skeptical.  So at a recent eyewear trade show in New York we borrowed an SR-91 lens blank and took it to a Drop-Ball chamber used to test lenses for ANSI compliance.  The normal 5/8-inch steel ball did nothing to the lens, so we put in a 4-inch solid steel ball bearing and dropped it 5 feet onto the lens.  We wanted to see if the lens would shatter into sharp pieces, or just split apart.  Not only did the lens stay in tact, there was not a single scratch on it.  We have never seen a lens respond this well to a Drop-Ball test.  We are now big fans of the new SR-91 lens material.

The limitations of SR-91 include availability and price.  The range of prescriptions blanks available is not as great as other materials that have been on the market for years.  Currently SR-91 presciption lenses are available from -3.00 to +5.00.  And as you would expect, this new, sharper lens material costs more than traditional lenses.  Single vision prescription lenses are about 30% more.  Progressive SR-91 lenses are bout 75% more expensive than polycarbonate. It takes about 2-weeks for us to process prescription SR-91 orders.  Other lenses take 2 - 5 days.  But if sharp, glare-free vision is a priority nothing is a better value than SR-91 lenses.

Kaenon is currently the only manufacturer using SR-91 as standard material in all their eyewear, including prescriptions. 

We can put SR-91 prescription lenses in almost any frame you choose, regardless of who the manufacturer is.  Call us for pricing if you do not see this option listed.

Lens Treatments and Coatings

Polarization:
Polarization is not a coating placed on the outside of the lens.  It is a thin layer of iodine crystals arranged in vertical rows and sandwiched into the middle of a lens.

Although it may seem a bit feeble to compare this lens to microscopic mini blinds, that's really the easiest way to illustrate how polarization works.  Light can pass straight through these crystals, but glare is completely blocked. ALL of our polarized glasses from every manufacturer can be found on our Polarized Sunglasses page.

Polarized lenses are absolutely the best way to eliminate glare.  Coatings can be added to the surface of a lens to reduce glare, but these coatings affect all light, not just glare.  A polarized lens will dramatically improve vision on sunny days near water, snow, or roadways.  Eliminating glare on water can even help you see below the surface.

The additional protection of polarized lenses is also important for refractive surgery patients and pre or post-op cataract surgery patients.  Anyone on UV sensitizing medications such as insulin or hormone replacements will also benefit greatly from polarized lenses.

Polarized lenses are the greatest use of technology in the optical industry.  But there are some limitations and even more myths that surround this material.  If you're a pilot, you probably already know that polarized lenses can make some LED instrumentation invisible. Most glass cockpits are not affected. (We recommend the Serengeti Drivers Gradient lens for pilots.) Skiers love polarized lenses in bright sunny conditions on fresh powder, but alleged experts have been telling us for years that icy or crusty spots could be harder to see. We found this to be blatantly false, but this long-standing misconception has kept many eyewear manufacturers from producing polarized ski glasses.

Lastly, golfers often believe that polarization is not needed on a golf course because grass and trees don’t produce glare.  The glare in wide-open sunny places is actually caused by the sun, not objects on the ground.  To illustrate how significant this is we often recommend that golfers compare their favorite golfing glasses to the Kaenon Kore with the polarized Copper-12 or Copper-28 lens.  If their vision is not twice as good with the Kaenon lens, they can simply send the glasses back.  We ship them at no charge, and there are no restocking fees. 

Anti-Reflective (AR) Coatings:
Typically, about 8% of the light that hits a lens is reflected off.  AR coatings allow much more of the light to pass through to your eye. Although it may seem a little oxymoronic to put an AR coating on sunglasses, there are at least a couple good reasons to do it.

Applying an AR coating to the front of a lens can help reduce glare, though polarization or a flash coating are more effective.  AR coatings on sunglasses have the most benefit on the back of the lens.  If the frame has a flatter design, sunlight can reflect off the back of the lens and into your eye. Sunglasses that claim to filter out 100% of UV rays will actually provide no protection at all if sunlight is reflecting off the backside of the lens directly into your eye.

Some of the newest AR coatings have also been better engineered to increase the scratch resistance of the lens.

The term "AR coating" is actually a bit misleading. It takes several metal oxide coatings to create the optical interference that counteracts reflected light waves and allows more light to be transmitted through the lens. Each layer is scientifically engineered to work with a specific segment of the color spectrum. So far, no one has figured out how to do this across the entire color spectrum without adding a slight tint to the lens. On clear dress eyewear, this might be a barely noticeable green or purple cast. If the coating is on the front of the lens, your eyes will be more visible because the lens is less perceptible.  AR coatings on sunglasses are just as effective, but less noticeable.

AR coated lenses seem to require more cleaning because smudges and fingerprints are more visible when glare is reduced, and you can see through the lens better. When you clean a lens that has an AR coating, USE A CLEANER THAT IS APPROVED FOR AR LENSES.  Many cleaners designed for regular glasses will wreck an AR coating. (See Accessories for AR-Safe lens cleaner.)

ADS Eyewear is an optical company, not just a sunglass distributor. ALL of the glasses on this site are selected to improve your vision and preserve your site. If an AR coating should be applied, it is. And when you receive an AR coating from us, it will be good one.

All glasses from Serengeti and Kaenon have an AR coating on the back of the lens, as does the Bolle Metals Collection.

Flash or Mirror Coatings:
A flash coating, also called mirror coating, is the opposite of an AR coating. Flash coatings reduce glare by reflecting it off the front of the lens before it can be amplified between the lens surfaces. The mirrored appearance will also prevent other people from seeing your eyes.

The color of a flash coating is only visible from the outside.  If a gold flash is put on a blue lens, it will appear blue to the person wearing it, and gold mirror to everyone else.  The color of the flash coat does not effect how color is perceived.  It only acts as a shield against glare.

Because flash coatings make such a bold fashion statement, they are usually selected for the look, not for functionality.  Two exceptions to this would include snow sports and clear lenses.  Reflections from new snow can be very intense. People who choose not to wear polarized lenses will benefit from the glare-reducing qualities of a flash coating. Glare can also be a factor under stadium lights or in an auditorium. Flash coatings on clear protective eyewear worn for soccer, baseball, or basketball can reduce glare without tinting the field of view.

Photochromic Lenses:
Photochromic lenses change from a light to a dark tint based on the amount of sunlight or UV exposure. Silver halide is mixed with the lens material to cause this transformation. This feature is very popular in driving glasses. When a driver or pilot is behind a windshield, UV rays are blocked and the glasses maintain a comfortable tint. When exposed to direct sunlight, they darken.

Special precautions must be taken when ordering prescription photochromic lenses. Silver halide is typically mixed evenly throughout the lens material. So in stronger prescriptions, the thickest part of the lens will get darker than the thinnest. And if your prescription is not the same in each eye, your expensive prescription glasses could end up looking really silly.

Fortunately the technology exists to rectify this problem.  And as you would expect, we would not sell you a pair of glasses that will make you look silly.

Important Note About Photochromic Lenses:

There is absolutely nothing that works better than the Transitions material that we use in all our photochromic prescriptions lenses.  BUT, there are a few important facts that you should know before purchasing them.