Get Out of the Dark about New Sun Lens Technologies And Exceed Patient Expectations

By Mark Mattison-Shupnick, ABOM

Adding new sun lens products and technologies better meets patient’s expectations. Why? Patients are consumers and consumers like what’s “new” and are intrigued by new technologies, or products. That’s especially true today if they are more personalized for their needs.

Technology is a driving force of change and a source of optimism in these challenging economic times. From computers to flat screen TVs, new innovations in consumer electronics are driving consumer demand for high-performance, value-added products. Consumers are spending more time evaluating their potential purchases, looking not only for competitive prices but also for the best, products that exceed their expectations in overall quality and performance.

This trend is no different for optical products. Digital surfacing and advanced coating technologies are building awareness and momentum of high-performance, value-added optical products. Nowhere is this more evident than in innovative sun lens technologies. These innovations provide the same opportunity to exceed patient expectations and differentiate your business from the competitive landscape of standard sun lens offerings. Harnessing the power of new sun lens technologies can help guide your business through this period of economic uncertainty.

Technology Equals Advantages

At its most basic, a suns lens is a clear lens that has been enhanced to improve visual performance and comfort in outdoor environments. There are two main categories of sun lens technologies that contribute to the overall performance and quality of sun lenses: Light Management Technology and Lens Material Technology. By combining the latest innovations in both categories, you can provide your patients with sunwear that exceeds their expectations.

LIGHT MANAGEMENT TECHNOLOGY

Controlling how the retina receives light is the goal of all optical lenses whether clear or tinted. With sun lenses, the need for specialized light control is even more important to allow the right amount and quality of light through the lens. There are three main categories of Light Management Technology featured in sun lenses that contribute to overall visual performance, comfort and exceeding patient expectations.

Lens Color & Tinting

While many patients assume that the color of a sun lens is merely cosmetic, lens color greatly affects the filtration of light through the lens. Transmission is the physical process of light passing through the lens to the eye and is measured in terms of transmittance. Indoors and at night, it is imperative for the retina to receive as much light as possible. Therefore, the application of anti-reflective treatments is recommended for all clear lenses to improve transmission. However, the intensity of light is much greater outdoors, which creates the need for a lens that limits the amount of light that passes through it. Tints (or pigments) are added to sun lenses to filter the light through selective absorption. Through specialized tint formulations, sun lenses can optimize the wavelengths of light that are both transmitted and absorbed by the lens. For example, gray lenses absorb all wavelengths of light evenly, providing natural color contrast and low color distortion. Conversely, brown lenses absorb wavelengths differently, filtering out more blue light and providing enhanced color contrast and depth perception. So, a sun lens can be characterized by color, transmittance or absorption. Therefore, a typical Gray 3 or G-15 lens passes about 15 percent light or is 85 percent absorptive.

By informing patients about the different visual performance experienced through various sun lens tints, you can offer a personalized sunwear recommendation based on your patient’s interests and activities.

There are various methods used to incorporate color into sun lenses. Surface Tinting is a fast and inexpensive way to tint sun lenses. However, the tint molecules are typically only slightly below the surface of the lens and, as a result, the color can fade over time. For example, gray lenses can become redder or magenta in color as the blue component of the gray dye fades faster than the red component. This results in a product that can no longer meet the needs of the patient and therefore reflect poorly on the quality of your business. In- Mass Tinting is another production method in which the dyes are mixed into the lens material during casting. This process creates more stable color performance over the life of the lenses. However, after surfacing minus power in-mass tinted lenses can be lighter in the center than on the edges; plus power in- mass tinted lenses can be darker in the center. These are sometimes referred to as the “raccoon” and “bulls-eye” effects, respectively.

High-performance sun lenses should offer enhanced visual quality through exceptional light filtration and uniform lens color, and they should not lose their color or ability to filter light over the life of the sunwear. To solve the problem of lens color fading and uniformity, an innovative new sun lens technology called Confined Tinting has been developed to create a fixed tint that has a depth of 0.9 mm from the front surface of the lens. This process allows for deeper dye penetration than surface tinting so the color and light filtration do not change over the life of the lens.

At the same time, because the dyes are not mixed throughout the entire lens, the color is uniform across the entire lens after surfacing. Final prescription and thickness profile do not affect light filtration and visual appearance. Confined Tinting is newer technology and is currently being used in the manufacturing of NXT Rx sun lenses.

Polarization

Polarization is an increasingly popular method of light management. A polarizing filter is incorporated into the lens to block blinding glare by filtering out polarized light that is reflected off non-metallic shiny surfaces, such as pavement, water, sand or snow. In certain situations such as driving, blinding glare can hide people or objects, creating a safety hazard and reducing reaction time. By blocking blinding glare, polarized sun lenses improve patients’ visual performance and comfort. Polarized sun lenses are available from most lens manufacturers and optical laboratories and should be recommended to every patient.

Traditional plano polarized lens construction involves the use of a film adhered to or encapsulated within two lenses. While traditional polarized lenses provide outstanding visual performance by blocking blinding glare, many customers purchasing cheap plano sunglasses may have experienced lenses where the film has deteriorated, discolored or delaminated over time. A new innovation in polarization technology completely removes the film from the system. Through a complex process called Advanced Polarized Surface Technology, the polarizing element is infused directly onto the back surface of the lens. The process is similar to anti-reflective and super hydrophobic coatings. By removing the film, lenses can be as thin as non-polarized lenses and do not run the risk of delaminating. This technology is available exclusively on plano NXT sun lenses featured in Serengeti Polar PhD eyewear. Plano sunwear that makes a difference can differentiate the professional office from the drug store. Exceed expectations for non-prescription sunwear customers.

Photochromics

Photochromic dyes can also be incorporated into sun lenses to further enhance light management in changing light conditions. The tint of photochromic sun lenses automatically adjusts based on exposure to UV and/or visible light. Comfort and convenience are the benefits to describe when recommending photochromic sun lenses. They allow the appropriate amount of light through the lens whether it’s bright and sunny in San Diego or partly cloudy in Chicago. Photochromic sun lenses provide one pair of sunwear that offers visual performance and comfort in any outdoor environment. The availability of photochromic sun lenses is increasing in both prescription and non-prescription lens offerings.

LENS MATERIAL TECHNOLOGY

Lens material has a dramatic influence on the overall lens performance characteristics and benefits. Glass sun lenses continue to be used in some sunwear applications. However, the performance characteristics offered by new plastic lens materials provide optical clarity consistent with glass but with drastically improved weight and impact-resistance properties. Understanding the interrelation of different lens material properties will allow you to balance the benefits of visual quality, comfort and protection in your sun lens recommendations. This section reviews key performance properties of the five main categories of lens materials: Glass, Hard Resin (CR-39 monomer), Polycarbonate, High-Index materials and Trivex material.

Lightweight Comfort

According to VisionWatch, a study conducted by Jobson Medical Information and the Vision Council, “Lightweight” is a consistent patient response as the most important “extra lens quality” when purchasing lenses. The prescription, lens size, shape, minimum center or edge thickness and specific gravity of the lens material are factors that determine the final weight of the lens.

Specific Gravity is the relative density of an object to an equal volume of water. The lower the number, typically, the lighter and more comfortable the lens will be. Lightness is the result of lens volume (thinness) and the material’s specific gravity.

Thinness is improved by using highly impact resistant materials that allow thinner centers or edges and materials of higher refractive index. Although high-index lenses appear to be thin and light, they actually have a higher specific gravity because they are made from more dense materials. Consider NXT sun lenses made with Trivex material that are capable of 1.0mm center thicknesses. For the power range +3 to -3, Trivex material will produce the lightest lenses. For higher prescriptions, consider sun lenses made with polycarbonate, also capable of 1.0mm center thicknesses, and high-index materials that include an impact enhancing primer. By understanding the inter-relationship of specific gravity, refractive index and impact resistance, you can exceed patient expectations for lightweight sunwear. (Chart 2.)

Optical Quality, Lens Clarity

For all activities, sports and lifestyles, visual performance requires clear, comfortable vision in every situation. Sun lenses with high optical quality ensure that patient demand for visual performance across the entire lens is delivered. Lens surface design, Abbe value and material clarity contribute to the overall clarity of vision for wearers.

Abbe Value is a measure of the optical quality of a lens material. In prescription lenses, clear or sun, the higher the Abbe Value, the clearer the lens periphery, all other characteristics being equal. Lens materials with lower Abbe Values produce off-center “chromatic aberration,” increasing with lens power and distance from center. This blur is a result of color fringes around objects seen peripherally. While many wearers learn to ignore or tolerate this effect, improved contrast and clarity can improve visual performance for all patients. Abbe Values above 40 produce a clearer periphery and clearer vision across the entire lens (designs being equal). To exceed patient visual performance expectations, recommend prescription sun lenses made with materials that feature higher Abbe Values.

UV Protection

By its very nature, sunwear is intended to be worn in the sun. While most patients expect their sunwear to help them look good and see well, another critical requirement of all sunwear is to provide 100 percent UV protection. Protection from harmful UV rays is vital to long-term eye health. Most patients are aware of the dangerous effects UV rays have on their skin, but few realize the danger imposed on their eyes. Reinforce to your patients the importance of wearing UV blocking eyewear at all times—no matter how bright and sunny, or gray and overcast the weather may be. With more time and effort in educating patients about the absolute need for UV protection, patients will begin to accept it as a requirement of all eyewear.

Recommend lenses that automatically absorb 100 percent of UV radiation. Hard resin (or standard plastic) lenses block most UV light, but adding a UV-blocking dye boosts UV protection to 100 percent for added safety. New technology plastic lens materials—such as polycarbonate, high index and Trivex materials—have 100 percent UV protection built-in, so an extra lens treatment is not required for these lenses.

Impact Resistance, Durability and Toughness

All lenses dispensed must meet basic impact resistance as directed by the U.S. Food and Drug Administration (FDA). The drop ball test is applied for standard dress eyewear in which a 5/8" steel ball is dropped 50 inches onto the surface of the lens. To pass, a lens must not chip, flake or break into two or more pieces after impact. Manufacturers and laboratories test lenses for impact resistance compliance.

Sunwear may be subjected to extreme stresses caused by weather, activity or sports-related hazards more often than standard dress eyewear. Having a sun lens that exceeds basic impact standards would offer additional protection and durability for patients. The American National Standards Institute (ANSI) publishes additional standards for eyewear. The ANSI Z87.1-2003 standard for occupational and educational personal eye protection devices (“safety eyewear”) includes requirements for high-impact resistance in which both the frame and lens require certification. While this standard is intended for safety eyewear applications, high-impact resistance offers value added protection that should be recommended for all children’s sunwear and for those who participate in demanding activities and extreme sports. The standard provides direction on the high velocity impact test in which prescription lenses must be capable of resisting impact from a 1/4" diameter steel ball traveling at a velocity of 150 feet per second. To pass, no piece of the lens can become detached from the inner surface of the lens and the lens cannot fracture. Sun lenses made from polycarbonate and Trivex material meet these standards for high velocity impact resistance. (For additional information, see “Eye Protective Sunwear: Why It Should Be ANSI Z87 Safety Certified” at 2020mag.com.)

Lens durability and toughness are other lens properties that contribute to the overall performance of a complete pair of glasses. New frame technologies featuring high wrap designs and complex lens mounting techniques such as drilled, grooved, or shelf-beveled, these new frame styles demand sun lenses that offer robust durability and toughness. Notch sensitivity is a material property that can provide some insight into how a lens will hold up to these complex-mounting techniques.

Notch sensitivity is a measure of the reduction of strength in a material caused by the presence of stress concentration or surface inhomogeneity, such as a notch, crack and scratch. In other words, notch sensitivity indicates the susceptibility of a microscopic nick or chip to continue to fracture into a crack when pressure or tension is applied. “Star cracks” are an example of the notch sensitivity of polycarbonate that can result from improper drill speeds, dull drill bits, over tightening of screws, excessive flexing by the patient, chemical attack (e.g. nail polish remover) or any combination thereof. While the lens may not actually break, the patient experiences the dissatisfaction of a “defective” product. Since new sunwear frame styles require unique lens edging/mounting expertise and equipment, most of these remakes must be sent to a lab and the patient will have to give up their glasses for a week or more until the lenses are replaced. To avoid the costly distractions of re-makes, consider sun lenses with Trivex material that have virtually no notch sensitivity, meaning that there are fewer incidences of small microchips or cracks and, when present, do not continue to fracture and create star cracks.

SUMMARY

Recent advances in both Light Management and Lens Material Technologies provide eyecare professionals with a unique opportunity to provide high-performance, value-added sunwear that can exceed patient expectations. By optimizing the combination of Light Management and Lens Material technologies, eyecare professionals can feature differentiated sunwear that delivers an advantage over their competitors and resounding patient satisfaction. For example, high-contrast polarized photochromic sun lenses made with performance lens materials mounted in high wrap semi-rimless frames can far exceed patient expectations for what a “standard” pair of sunglasses can do. By embracing these new sun lens technologies, eyecare professionals can expand their sunwear offerings, continue to bring patients back for the most advanced products available and position their business for success in any economic environment.