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Trivex Material– Unique Attributes Make it More Than a Niche Material

By Mark Mattison-Shupnick, ABOM

Sometimes when a new product is launched, it is placed in a specific niche based on the one or two successful applications for that product. Remember when "polarized" was mostly a fisherman's lens? The same thing is currently happening with Trivex material.

Ask ECPs why they choose Trivex material and you'll hear:

• "I prefer Trivex material for kids' eyewear."
• "I use Trivex material when I have a drilled rim-less because it doesn't crack around the holes."
• "I have a patient that appreciates clear vision."

When a material has a unique combination of properties, why limit its use to only special cases? Who wouldn't benefit from impact resistance, resistance to cracking and clearer vision? Even though the combination of properties of Trivex material exceeds those of standard plastic, CR-39 material is still a first choice for many.

While Trivex material is often used to make kids lenses, because of its extreme impact resistance and UV absorption, many opticians have yet to think of Trivex material as an everyday material. Understanding the properties, benefits and advantages can move Trivex material from a niche product to an everyday choice.

MATERIAL ATTRIBUTES—
A FOUNDATION

The lens material and its characteristics become the foundation on which all lenses and their final properties are built. A material's attributes form the final product that is delivered to the patient. However, no lens is the result of only one of its properties (index or impact or specific gravity, etc.). In fact, choosing a lens material because of one attribute, such as index, can often create a lens that isn't what the optician or the patient expected. Lens attributes work in combination.

For example, a lens' final thinness, a major patient benefit, is determined not only by index, but more importantly, by the material's impact resistance (for the frame style, size and shape chosen by the patient). The extreme impact strength of Trivex material significantly exceeds FDA impact requirements. This allows minus lenses with thinner centers to be sold. Unlike lenses made with CR-39 monomer (from PPG Industries), which are produced to 2.0mm centers, lenses made with Trivex material are produced to about 1.2mm centers. This 0.8mm reduction in thickness is possible in all but the powers near plano. In addition, that also means an equal reduction in edge thickness of almost a millimeter. When combined with the index of 1.53, lenses are thinner yet. In plus lenses, edges can be made thinner, since the material is not prone to flaking or chipping (due to tensile strength, notch sensitivity) especially when grooved.

This benefit of lens thinness is typically combined with lightness in the sales process. That's because thinness reduces lens volume and creates the final weight of the lens. However, the real lens weight is a function of volume and the material's specific gravity. In this case, Trivex material was engineered to be the lightest material (1.11g/cm3). In the same Rxs, lenses with Trivex material are always thinner and lighter than CR-39 monomer due to its index, extreme impact resistance and specific gravity.

Patient Benefit—Thin and Light: When compared to CR-39 monomer, lenses made with Trivex material are up to 15 to 20 percent thinner and always about a third lighter. An aspheric design will further reduce thickness and weight. While there are other higher index materials that can make lenses even thinner, lightness depends on final lens volume and its specific gravity. Some high-index materials have much higher specific gravities so the weight savings when compared to Trivex material is less than you might think. While the highest index lens of equal power is another 15 to 20 percent thinner, within the core range, lenses made with Trivex material are still 10 percent lighter. For the core range of lens prescriptions (-4.00 to +3.00), having a lighter lens is always a selling benefit. VisionWatch patient surveys report that patients value the lightness of their eyewear the most.

Patient Benefit—Clear Vision: Material choice also affects the clarity of vision. A lens' clarity is a product of Abbe, glare-free (anti-reflective) coating and the type of lens design used. Prism, off-center in prescription lenses, creates power errors and blur, the result of chromatic aberration and the lens design. Manufacturers work hard to create lens designs that reduce off-center power errors but the material still contributes clarity based on its abbe. The higher the abbe, the less chromatic blur. The result is a larger, clearer field-of-view (for the same prescription, material-to-material).

CR-39 material and glass lenses have the best Abbe. To support a choice of Trivex material as a replacement for CR-39 material, lens clarity should be equivalent. After all, crisp vision is an expectation of your patients, not something that you sell as an added benefit.

Abbe values are a relative measure of clarity and are not linear. Trivex material has an Abbe value of 45 which produces lens clarity virtually equivalent to CR-39 material.

Patient Benefit—Protection: The protective qualities of eyewear are an everyday benefit that is seldom discussed unless the subject is children's eyewear or sports lenses. The protection provided by eyewear should be a discussion every time eyewear is sold. Lenses can provide a shield against the damage from ultraviolet (UV) radiation and protect the eyes from impact from random accidents.

Patient Benefit—UV Protection:
UV radiation is a recognized contributor to the formation of cataracts. As a result, lenses sold in eyewear should always provide 100 percent UV protection. Any choice for an everyday lens material must provide 100 percent UV protection. CR-39 monomer, depending on specific lens manufacturer processes, absorbs between 85 to 90 percent of UV radiation while Trivex material provides 100 percent UV protection. While a UV dye can be applied to CR-39 material for added absorption, this dye can compromise the long term adhesion of anti-reflective coatings and result in delamination. Therefore, it is more practical to choose a material that provides 100 percent UV protection without additional processing. Every lens made with Trivex material automatically provides protection from the effects of UVA and UVB radiation.

Patient Benefit—Impact Protection:
According to The Bureau of Labor Statistics (BLS), almost 70 percent of the eye injuries studied occurred from falling or flying objects, or sparks striking the eye. The best way to prevent eye injuries is to always wear the appropriate eye protection. Since no one can predict when they will need eye protection, it makes sense to have eyewear, even everyday glasses that provide impact resistance at all times. While it may be easier to bring up the subject of impact resistance when talking about kids' eyewear or sports specific eyewear, the truth is that everyone needs to protect their eyes and their vision, all the time.

By providing patients with an everyday lens that offers extreme impact resistance, you are making sure that their eyes receive the best protection no matter the activity. Providing this protection is even more important today, when patients are less likely to purchase more than one pair of glasses due to financial reasons. This means they are more likely to wear their everyday glasses while playing sports, working in the yard or around the house. Lenses made with Trivex material have 62-times the impact resistance of ordinary plastic lenses.

One office uses this statement to get across the message of eye protection for everyday lenses: "Our office recommends Trivex material as our standard lens material of choice because it provides the visual armor to protect your eyes from both UV light, while providing the ultimate in impact resistance, no matter what you are doing."

FRAME CHOICE

Frame choice also drives material choice. Usually the patient will select their frames first and then the lenses. This can present a problem with some lens materials. Consider the combination of a plus lens and a grooved semi-rimless frame. With lenses made from CR-39 material, there can be flaking at the thinnest corner. Oftentimes, patients will return a pair of rimless glasses because of star cracks around the drilled holes or flaking at the edges.

Patient Benefit—Frame Choice Freedom:
Lenses that retain their looks and safety regardless of frame style allow patients to select the frame of their choice knowing that the lenses will not be affected. By selecting a lens material that doesn't flake or crack, opticians can feel confident that no matter the frame choice of the patient, the lenses will be suitable for the frame.

Trivex material is unique in that it has extremely high strength and virtually no notch sensitivity. This means that the lenses won't develop edge flakes or chips, and when used for drilled rimless, won't star crack. This is particularly important in drilled polarized lenses. Polarization efficiency is affected by compression at the drill points. Choosing Trivex material solves many problems before they start by reducing breakage and remakes.

WHAT TO SAY

When making a lens recommendation, include the patient benefits of the lens along with the lens attributes. The more "true-tolife" the description, the more it will resonate with the patient. Suggesting a change to Trivex material as a replacement for CR-39 material might sound like this:

1. I'm recommending lenses made from Trivex material because it delivers crisp, clear vision with exceptional optical performance.
2. Your lenses will be ultra-lightweight, providing added comfort since Trivex material is one of the lightest lens materials available.
3. This material automatically provides 100 percent UV protection and is unsurpassed in impact resistance and durability, meaning your eyes will always be protected.

Consider creating a set of index cards that have material attributes and benefits listed for each optician to use as a reference. Opticians that use the same words add continuity of message throughout the office. When patients hear the same message from everyone in the office, it reduces confusion.

PREMIUM OR EVERYDAY?

Should Trivex material be considered as a premium or everyday lens material? Perhaps this is the wrong question to ask. The correct question should be, "What is the best material for the patient's Rx and vision requirements?"

Remember, the Rx is the driver with the balance of lens properties completing the requirements. If a patient with a -2.00D Rx requires lightweight lenses and protection in a rimless frame, Trivex material may be the best solution especially if the patient had a bad experience with star cracks in a previous pair of rimless glasses. If the Rx is -6.00D and thinness is the number-one consideration, then a higher index material is probably the better choice for this patient.

Deliver the best eyewear for the patient, which includes being selective when it comes to recommending the lens material.

TRIVEX MATERIAL FOR SUNWEAR? IT'S THE RIGHT CHOICE

"High velocity impact resistance" (Z87.1 that is) says it all. A lens material that can meet Z87.1 high velocity impact standards ensures that eye injuries are lessened and your patient's vision will be protected. The wrap shape of many of today's sports sunwear also helps to reduce dust, dirt and wind from getting to the eyes. The steepness of the 8 base lens shape adds to the impact resistance structurally, while a polarized lens eliminates blinding glare. Since sunwear is worn outdoors during activities such as cycling, skiing, jogging, fishing and golf, the likelihood of eye injury increases with these types of activities. Providing your patients with sunwear made with an extremely impact resistant material like Trivex material will provide the optimum protection for their eyes.

TRICKS OF THE TRADE

When converting from a well-known material like CR-39 material to Trivex material, there are a few tricks-of-the-trade that savvy labs and opticians have adopted to make their lives easier and the results predictable.

• Let the lab choose the correct base curve, especially when lenses are aspheric in design. This is extremely important since good peripheral vision through lenses is index and base curve dependent. Manufacturers have calculated the correct base curve to choose to provide best vision and labs store those tables for lens choice when completing an Rx order.

• For the office that does its own edging: It is easier today to edge Trivex material since edger manufacturers have modified their systems to add Trivex material capability. Direct drive motors get instructions on speed and torque from a sophisticated internal software module by simply pushing the Trivex material mode with the Lens Type button. The edger automatically adjusts wheel speed and the torque for which the lens is rotated on the wheel. The drain that carries away waste material (swarf) has been increased in size so any heat induced material “clumping" washes down the drain without a clog. Water, as coolant, also washes/cools the back of the grinding chamber so there is little effect from the heat generated as the material is cut dry during the initial edging cycle.

• For drilled rimless: Trivex material is the least affected by drilling, so it reduces or eliminates the possibility of star cracks or breakage. That same tensile strength and lack of notch sensitivity allows thinner edges on grooved semi-rimless since the groove wall is unlikely to chip or flake. In both frames styles, it reduces the number of remakes and improves patient satisfaction.

• Build on Trivex material: To provide an ultimate in vision enhancement, combine the benefits of Trivex material with advanced lens designs, treatments and additional options that fit your patient's vision and lifestyle needs and exceed their expectations.

AVAILABILITY

Making a global change to a material that can be used everyday requires good availability in the styles and designs you routinely dispense. The optical business is slow to use a product when there is minimal availability. Initially, the lack of breadth of designs and suppliers was limited in Trivex material and so the ECP had fewer choices, which made the adoption of this material a slow process.

However, that is no longer the case. This is especially true with the advantages of free form manufacturing in the laboratory. Virtually any of the newer optimized and/or personalized progressives and single vision lenses can be created in Trivex material.

Virtually all lens manufacturers offer lenses made in Trivex material, available also as Transitions lenses and a variety of polarized designs. You'll find that Trivex material is manufactured under a variety of trade names. They include: Centurion and Trinity from Augen; Phoenix from HOYA Vision Care; Excelite TVX from Thai Optical; Aris from X-Cel Optical; Trilogy from Younger Optics; NXT from Intercast Europe; and Trivex material from Essilor, SEIKO, Shamir, Shore, Signet Armorlite and Carl Zeiss. Each manufacturer offers this material category in their proprietary designs.

LEARNING TOOLS AND RESOURCES

As with any lens material, you'll find that there are best uses for Trivex material while other situations may call for a different material for a particular patient's needs. Your optical laboratory is a great resource for lens information and education.

Visit www.ppgtrivex.com for Trivex material availability from the manufacturers mentioned above. The Trivex material web site has tips for processing as well as a complete e-learning module at www.ppgtrivex.com/ education. Review other CE courses at 2020mag.com/CE for additional information about material choices.

CONCLUSION

By considering the interaction of the lens attributes with material properties, opticians can offer a better choice for everyday eyewear for their patients. Consider replacing CR-39 monomer as the standard lens material with Trivex material and provide increased patient benefits.

An appreciation of the material's attribute interactions is required knowledge to make that decision. Since the material is the foundation on which lens styles and designs are built, it's important to start with the best combination of lens material attributes to provide the most benefits for each patient.

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