User:JPeaksMoore
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Dual-Zone™ Sports Vision sunglass lenses have been developed to mitigate the poor visual performance that can occur from traditional solid-tint sunglass lenses. The lens technology is based on the principal that outdoor lighting conditions span a very wide illumination range from 80,000+ LUX in the very bright sun & sky overhead to a relatively dark illumination of 3,000 LUX for turf, grass, dirt or other terrain. To optimize an athlete’s vision for both lighting extremes, two different filters are required. Dual-Zone™ technology integrates two filters into one lens. Typically, the Upper Zone of the lens is appropriately tuned to manage the bright ambient lighting from the sun and sky. The Lower Zone of the Dual-Zone™ lens applies a different filtration system designed to transmit more light into the eye off the turf or terrain.
With continually increasing rates of UV-related eye disease, competitive athletes have known they should protect their eyes from prolonged sun & UV exposure, but top-performance in most sporting activities requires critical visual tasking. Many athletes complain that sunglasses lenses that have traditionally solid-tint neutral-density gray, brown or amber filtration and are produced from polycarbonate degrade their vision to a point where it negatively affects their performance. The fallout from this scenario is increased eye fatigue, risk of ocular injury and premature diseases of the eye attributable to excessive exposure to ultraviolet radiation.
Diseases or conditions of the eye that may result from UV radiation:
Dry-Eye Syndrome: A chronic condition that leads to unbalanced tear layers caused by extra oils being produced. This causes a “sticky” feeling when blinking that begins as an annoyance but can blur vision. Contact lens wearers and patients who have had LASIK vision-correction surgery are highly susceptible.
Cataracts: A yellowing and hardening of the crystalline, transparent lens inside the eye. Overexposure to UV radiation causes the lens first to become translucent and eventually opaque.
Presbyopia: A condition where the eye's ability to focus is diminished and commonly occurs with aging. The most widely held theory is that it arises from the loss of elasticity of the crystalline lens. Premature onset of presbyopia can be the result of excessive & prolonged exposure to UV-radiation as it can harden the crystalline lens.
Macular Degeneration: A medical condition predominantly found in elderly adults in which the center of the inner lining of the eye, known as the macula area of the retina, suffers thinning, atrophy, and in some cases bleeding. This can result in loss of central vision, which entails inability to see fine details, to read, or to recognize faces.
Pterygium: Associated with the conjunctiva, the mucous-like covering that covers the sclera or “whites” of the eye. A pterygium is related to ultraviolet-light exposure (e.g. sunlight), low humidity, and dust.
Ocular cancer: Tumors in the eye and orbit can be benign like dermoid cysts, or malignant like rhabdomyosarcoma and retinoblastoma. The most common eyelid tumor is called basal cell carcinoma. This tumor can grow around the eye but rarely spreads to other parts of the body. The most common eyelid cancers include squamous carcinoma, sebaceous carcinoma and malignant melanoma.
With the goal of reducing the risk of loss of sight due to UV exposure and/or impact trauma, Dual-Zone™ lens technology has effectively solved the three big problems athletes have with sunglasses; Filtration, Distortion and Peripheral Vision
Filtration: The primary problem athletes have with sunglasses is filtration. When the lighting conditions outdoors are 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 visual workout that an athlete endures in outdoor competition is dramatic. For ball sports, athletes must properly assess turf conditions and terrain when looking down towards the ground. The illumination of the turf can be as little as 4% of the ambient light in the sky. Athletes often shift their focus from the relatively dark turf to the bright sky (100% bright). When an athlete 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 turf or terrain.
This condition is further exacerbated when taking sunglasses off and on during an activity. 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.
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.
This chart describes how different lens filters function at the lighting extremes. The typical single-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.
Dual-Zone™ Light Metering on Grass Turf
No Filtration Dual-Zone Filters Amber Filter Neutral-Density Filter
The typical single-tint amber lens is perfect for enlightened visualization of green-grass turf and to enhance contrast sensitivity for improved visual acuity. But with the amber lens, the bright sky remains an uncomfortably bright 62,440 LUX and colors are distorted, which negatively affects distance perception.
The typical single-tint gray (neutral-density) lens effectively reduces the brightness of the sky down to a visually comfortable 14,460 LUX. But the gray lens also reduces the illumination of the terrain to a mere 1,195 LUX, far too dark for accurate visual tasking.
PeakVision Sports’ Dual-Zone 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 for optimized visualization. The amber-tuned Lower Zone maintains the illumination of turf and terrain at 3,036 LUX and increases contrast sensitivity for enhanced visual acuity. The Dual-Zone lens perfectly balances the light into the Ideal Range...whether you are looking up in the sky or looking down at the turf or ground.
Even though the lighting extremes from turf to sky have a very wide range, PeakVision’s Dual Zone™ lens delivers approximately the same quantity of light to the eyes in both extremes. Therefore, the iris is required to open and close through a much smaller range of accommodation, and the athlete’s overall visual acuity and speed of perception are improved while experiencing significantly less eye fatigue.
Distortion: The poor optical performance of sunglass lenses produced from polycarbonate has long been documented. When polycarbonate lenses were first developed in the early 1950s, they were successfully marketed not for their superior optics but for their superior impact resistance. Engaging in active sports while wearing lenses produced from glass had resulted in a countless number of individuals losing an eye or their eyesight when a glass lens would shatter from accidental impact. Being impact-resistant, polycarbonate lenses introduced significantly safer eyewear designed to protect eyes from extreme impact as opposed to shattered glass lenses that irreparably damaged eyes, often times to the point of loss of vision. Though this safety benefit was of tremendous value, the optical performance of polycarbonate lenses has been less than ideal.
Fifty years after its invention, most major sunglass brands are still using polycarbonate as their lens material. Manufactured using an injection molding process, the optical performance of polycarbonate is inferior because polycarbonate has an inherent optical problem called birefringence. The very nature of polycarbonate causes a double refraction of various wavelengths of light (colors). This lack of 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 or “rainbowing”, particularly in the periphery of the lens) and, therefore, the greater the resolution and clarity in the lens. As an example, a polycarbonate lens may refract 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.
As illustrated on this ABBE VALUE OPTICAL CLARITY SCALE, polycarbonate has inferior, low Abbe Value that ranges between 24 and 29.5; meaning the lens has poor optical clarity compared to gold-standard glass lenses with an abbe value in the 60s or CR-39 ophthalmic plastic lenses (breakable), usually with an Abbe Value in the 50s or 60s.
In 2002 a new lens material developed to provide superior optical performance for the windscreen of the Apache helicopter began to be used for optical lenses. Branded as NXT® it is the first shatterproof lens material that achieves the optical clarity and overall optical performance comparable to ophthalmic-grade lenses. Because this new lens material is manufactured with a “liquid-casting” process much like the process to produce a glass lens, the birefringence (rainbowing) and chromatic aberration that is inherent in polycarbonate lenses is no longer present and the NXT® lens has far superior optical clarity, with an impressively high Abbe value of 45.
Peripheral Vision Another important aspect of performance sport sunglasses relates to peripheral vision. For many sports what your eyes see with your peripheral vision is important information your brain uses to accurately locate the target or avoid impact that can lead to injury. 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 significantly distorting. This is another reason athletes wearing sunglasses with standard single-tint, polycarbonate lenses often have to remove them for certain tasks that require visual acuity.
Through the use of 8-base curve lenses produced from NXT®, greater eye protection is provided with the increased wrap but with no additional distortion. Because the NXT® lens material has mitigated or eliminated the chromatic distortion and birefringence that is universally found in polycarbonate lenses, the Dual-Zone NXT® lens not only protects the eyes, but also the peripheral vision of athletes thus contributing to an increased safety factor. When wearing PEAKS, an athlete can better assess target lines and have confidence their eyes are accurately perceiving the position of targets.
Far too many professional athletes’ 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.
Every athlete must properly protect their eyes from the numerous hours of UV exposure experienced on a daily basis while participating in outdoor activities.
