SPORTS SUNGLASSES - ZERO DISTORTION DUAL ZONE VISION
By Dr. Craig Farnsworth, O.D., Developmental Optometrist - The Putt Doctor
1. FACES, FASHION & THE FUNCTION OF SUNGLASSES
For many decades, the eyewear industry has been first and foremost about fashion. Sunglass companies define their brands by focusing on ever-changing, fashion-forward frame designs that invariably make the sunglasses you purchased only last year, out-of-date today. While lip service is given to lens technology and vision, more energy and resources are devoted to coming up with new marketing slogans and catchy names for old science than actually innovating vision performance.
By contrast, one company, PeakVision, starts with the “business-end” of the sunglass - the optical performance of the lens. In fact, PeakVision invests 4-8x the cost of the lenses used in the mass-produced, famous brand sunglasses. Of course, frame fit, function and fashion design must also be integral components of the finished product, because nobody wants to look goofy out on the golf course or in their sport. PeakVision sunglasses have been performance-validated in numerous outdoor sports including golf, baseball, tennis, croquet, equestrian, cycling and motorsports. Though I have been impressed with how PeakVision’s frame line is designed to provide fashionable fit for the many face geometries out there, the great advantage of PeakVision eyewear is that their lens technology has effectively solved the three big problems athletes have with sunglasses; Distortion, Peripheral Vision and Filtration.
2. DISTORTION IN SUNGLASSES LENSES
Sixty years after its invention, most major sunglass brands are still using polycarbonate as their lens material. Invented in the 1950s when persimmon woods defined the state-of-the-art golf club technology found in every golf bag, polycarbonate became popular, not because of optical performance, but because of the safety benefits attributed to polycarbonate’s impact resistance. Manufactured using an injection molding process, the optical performance of polycarbonate is inferior because the polycarbonate material itself has an inherent optical problem. The very nature of polycarbonate causes multiple refractions of various wavelengths of light (colors).
3. LOW ABBE=DISTORTION
This lack of refraction uniformity, often observed as “rainbowing" results in distortion that is attributable to the inferior optical clarity of polycarbonate lenses. Of all of the properties of a particular lens material, the one that most closely relates to its optical performance is its dispersion, or chromatic aberration, which is specified by the Abbe Value - the higher the Abbe Value, the lower the chromatic aberration (visible as color fringing particularly in the periphery of the lens) and, therefore, the greater the resolution and clarity in the lens. As an example, a polycarbonate lens refracts red wavelengths differently than blue, than green, then yellow wavelengths. Because this optical error causes polycarbonate lenses to refract spectral wavelengths differently, the common complaint of “sunglass haze” is often observed as a lack of sharpness.
4. PERIPHERAL VISION & LENS DISTORTION
Another important aspect of golf sunglasses relates to peripheral vision. When playing golf, what your eyes are able to perceive with your peripheral vision is important information your brain uses to accurately locate the target. Furthermore, efficient, uninterrupted peripheral vision allows the eyes to operate efficiently and comfortably.
Therefore, it is important that the entire lens be free of distortion. Many sunglass companies will “center-grind” their polycarbonate lens in an effort to reduce the distortion in the front field-of-vision. However, this leaves the peripheral areas of a polycarbonate lens with significant distortion, particularly problematic when trying to properly read a putt. This is another reason golfers wearing sunglasses with polycarbonate sunglass lenses are compelled to remove them when putting on the green.
Polycarbonate lenses have an inferior, very low Abbe Value that ranges between 24 and 29.8; meaning the lens has very poor optical clarity compared to the more optically perfect Crown Glass lenses, which have a very high abbe value of 53.
5. WHAT IS A ZERO-DISTORTION LENS?
PeakVision utilizes a revolutionary, hybrid monomer that delivers an abbe value of 52…as clear as Crown Glass lenses! Even better, PeakVision lenses provide impact-resistant safety, lightweight fit and 100% UV400 protection.
With PeakVision’s frame styles that utilize larger 6-base and 8-base curve lenses, greater eye protection is provided with the increased wrap but without the additional distortion. Because PeakVision’s lens virtually eliminates the chromatic distortion that is universally found in polycarbonate lenses, the PeakVision lens not only protects the eyes, but also the peripheral vision of the golfer. When wearing PEAKS, a golfer can better assess the target line and have confidence the hole is actually where their eyes perceive the hole to be.
6. THE PROBLEM WITH SOLID-TINT FILTRATION
Initially, the primary problem golfers have had with sunglasses on the golf course is filtration. When the lighting conditions on the golf course were measured on a typical sunny day, the lighting extremes ranged from a high of 82,732 LUX for the sky down to only 3,122 LUX for the grass turf, less than 4% of the ambient brightness in the sky.
The workout that a golfer’s eyes endure for every shot is dramatic. When addressing the ball, the golfer is looking down at the dark turf (only 4% bright). After making contact with ball, the golfer immediately shifts his focus from the relatively dark turf to the bright sky (100% bright). When a golfer wears no eye protection, the range of light intensity that their eyes must operate in is approximately 84,000 LUX. These lighting extremes result in significantly increased eye fatigue, as the iris must constantly be adjusting from a bright sky to a dark green turf.
This condition is further exacerbated by the habit many golfers have developed, due to their single-tint sunglasses, of wearing sunglasses only between shots or for distance viewing and then taking them off for putting or shots around the green. This dramatic change in the amount of light entering the eye causes the iris to continually expand and contract through a wider range, resulting in increased eye strain and fatigue.
Unfortunately, as our eyes age, the accommodation for such abrupt light intensity changes becomes slower and the visual discomfort increases as you experience visual stress and strain for a more prolonged period of time.
Now, let’s analyze how different lens filters function on the golf course. The typical solid-tint AMBER lens is perfect for enlightened visualization of the putting surface and to enhance contrast sensitivity for improved green reading. But with the AMBER lens, the sky remains an uncomfortably bright 62,440 LUX...and colors are distorted, which negatively affects distance perception.
The typical solid-tint GRAY (neutral-density) lens effectively reduces the brightness of the sky down to a visually comfortable 14,460 LUX. But the solid GRAY lens also reduces the illumination of the putting surface to a mere 1,195 LUX, far too dark for accurate green reading.
7. THE PERFORMANCE BENEFIT OF DUAL-ZONE FILTRATION
PeakVision’s Dual-Zone golf lens integrates a neutral-density (gray) filter in the Upper Zone to manage the glare and brightness in the sky and bring it down to a comfortable 14,640 LUX. The amber-tuned Lower Zone maintains the illumination of the turf at 3,036 LUX and increases contrast sensitivity for enhanced vision of the putting green. The Dual-Zone lens perfectly balances the light intensity into the Ideal Range, whether you are looking up in the bright sky to track your ball in flight or looking down at the turf reading the green.
So even though the lighting extremes from turf to sky have a very wide range, PeakVision’s Dual Zone filtration delivers a balanced quantity of light to the eyes when you are looking up into the bright sky or down to dark turf. Therefore, the iris is required to open and close through a much smaller range of accommodation, and the golfer’s overall visual acuity and speed of perception are improved while experiencing greater visual comfort with significantly less eye fatigue.
8. LENS STYLE
Because PeakVision’s Dual Zone lens has a sophisticated and very fashionable double-gradient look, the lens also benefits teaching professionals by allowing students and others to see their coach’s eyes and make proper eye contact. Every golf professional knows that eye contact is extremely important in teaching and, for professional golfers, eye contact is important for connecting personally with the public. As evidenced by David Duval’s use of a dark gray lens, there’s nothing more impersonal than a black or mirrored sunglass lens that prevents eye contact. A dark lens tends to disconnect the wearer from the public and disguise one’s true personality.
Through the years I have seen far too many professional golfers’ careers end prematurely because of the years of UV exposure and resultant damage that has robbed them of visual acuity and the ability to read greens. Until eye transplants become possible, your eyes and vision cannot be replaced.
All golfers must protect their eyes for the 4-5 hours that a typical golf round takes. As an Eye Care Professional for more than 30 years, I can now say that finally, there is EYE PROTECTION AND VISION PROTECTION in a sunglass that will benefit every golfer from the first tee to the eighteenth green. PeakVision is the best sunglass lens I’ve ever seen and nothing short of revolutionary.
About Craig Farnsworth Developmental Optometrist
Dr. Craig Farnsworth is one of the world's foremost sports vision specialists. Since the 1970's, Dr. Farnsworth's principles have enhanced athletic performance and improved all phases of personal development. For the last three decades Dr. Farnsworth's research and inventive training methods on sports performance enhancement have gone through wide-scale testing, development and acceptance. Blending innovative training methods, solid philosophical and physiological concepts and methods to improve concentration and overall consistency of performance has enabled his See & Score Golf Schools to set the standard for performance enhancement with its eye-mind-body approach.
The See & Score philosophy revolves around 21 separate visual skills that represent most endeavors. Aiming, accuracy, eye-hand coordination, depth perception and rapid information processing are all but a few of the visual areas that are incorporated in our testing and training. See & Score consults with the Olympic Training Center, the Secret Service and Armed Forces elite troops. Additional information on Dr. Farnsworth’s vision programs is at www.PuttDoctor.com or you may contact him via e-mail at PuttDoctor@msn.com.
For more information visit www.PeakVision.com or call PeakVision at (772) 266-8787.