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Personal Sunglass Science, GOLF
Introducing the New Shamir Golf Progressive

By Barry E. Santini, ABOM, and Mark Mattison-Shupnick, ABOM

Personalization looks beyond the fundamentals of general purpose lens designs and gray lenses. Today, delivering the right eyewear to every patient requires that your choices be more advanced, activity-specific and age understanding when determining the lens design and sun filtration that works best. In this case, personalization is key to one of the most important leisure activities—golf. Introducing the Shamir Golf progressive, a unique way to think about the sport and the presbyope.

This goes well beyond our old, one-type-fits-all approach of tinting an old pair of prescription lenses. The dawn of the Golf Performance Sunglass has arrived, and golfing numbers about 27 million people—nearly 10 percent of the domestic population. With a proven record to willingly spend discretionary dollars in pursuit of just a hint of improved performance, it's time to take an in-depth examination of that individual known as the American golfer.

THE GOLF OPPORTUNITY

A "core" golfer is defined as one who plays an average of 37 full rounds a year and is primarily male with a mean age of 40. That says that a good majority is presbyopic. Therefore, they are part of the Rx population that mostly owns only one pair of glasses, in this case, either a general purpose progressive or a bifocal. For them, it's time to consider a progressive designed especially for the golfer.

Professionally educated with an average income of $104,000, core golfers are focused on any product that promises improvement or enhancement of their favorite pastime.

Core golfers are responsible for 87 percent of all rounds played and the same amount in money spent on equipment. With an average round lasting four hours, core golfers can spend almost 150 hours per year under the intense rays of the sun. Addressing the negative effects this much solar exposure can deliver has been the primary reason eyecare professionals have advised golfers to wear a proper sunglass. But ensuring proper eye health alone is no longer enough. First, there are significant numbers of golfing presbyopes, typically struggling with their progressives or bifocals resorting to single vision to get the blur out of the putt. Single vision lenses can create discomfort and frustration when the right power they're used to is not there. This gets worse as add power increases. Next, the improper use of sun tints, such as blue or very dark gray, may actually impede their performance.

Research completed in 2008 by a major athletic outfitter concluded that golf is the most visually demanding of all sports. Common lens designs create problems; new Shamir Golf meets the unique needs of the golfer. Then, consider the visual, color metrics, glare and environmental challenges faced by a golfer to best match filtration, polarization and coatings.

VISION, ENVIRONMENT AND LENS DEMANDS

Varying distances: The golfer's focus moves from the ball to its destination; every stroke, whether a drive or a putt, requires concentration. From teeing off on a 500-yard Par 5 hole, to the sinking of a 5-footer on the green, very few sports require such critical visual evaluations across distances that can vary by a factor of up to 300 times. He or she calculates distances and terrain. The accuracy of visual input is crucial to the hand-eye coordination needed for winning results.

Variable lighting conditions: As an outdoor sports activity, the conditions that make up the visual environment on the golf course change constantly. During a four to five hour round of golf, ambient lighting levels often vary from bright and sunny to darkly overcast. Especially as low-level clouds move past the bright sun, the golfer's eye has to contend with a wide dynamic range of both illumination and shadow.

Varying backgrounds: The task of distinguishing and following a white 1.68-inch ball against backgrounds that include light sand, green grass, brown trees and overcast to bright blue skies, poses challenges near the limit of human visual sensitivity.

Varying ground contours and conditions: Local variations in the elevation, pitch, contour, grass height and wetness of the course all must be properly factored and evaluated to control the path of the ball.

Varying wind conditions: The amplitude and direction of ambient wind influence all aspects of ball control in a round of golf. It's time for completely redesigned golf eyewear, both in design and color.

There are six areas of concern and of prime importance when prescribing and recommending the right golf lens. Three are visual; the balance is environmental.

NEW GOLF PROGRESSIVE MEETS THREE KEY VISION DEMANDS

The visual demands placed on a golfer dictate the importance of lenses that are as absolutely free of any distortion or power errors as possible. Particularly with wrap sunwear, it is the responsibility of you—the eyecare professional—to deliver the right vision, in all the right places with the least blur. That ensures that as little as possible visually gets in the way of peak performance.

After studying the eye movements of golfers, Shamir's development team identified three vital areas of focus for golf: far (viewing the distant green), midrange (looking down at the ball on the tee, fairway or green) and close (filling in the score card). Distance, mid-range and near aren't any different from the vision that any other progressive supplies but it's the way Shamir Golf does it that counts. In this new design, the size of the lens zones and the resulting management of the periphery have changed. Overall, distance is wider, with midrange redesigned to be longer with a stable plateau of power and near smaller.

In an everyday, general use progressive, distance vision and near are typically maximized. The large near facilitates excellent reading in all instances; a clear, wide distance ensures good driving and mobility. As a result, the midrange is narrower, usable for on demand arm's length vision but for special tasks, it is often too narrow. As the add power increases it gets narrower. In fact, many higher add wearers (adds greater than 2.00) complain of the narrow intermediate at the computer or when using a tablet. In that lies the opportunity for this new progressive. These higher add wearers are a large part of the golf demographic. For them, it means that conventional progressive lenses don't deliver the optical power needed for focusing on the ball where it's needed most. First, presbyopic golfers require clear vision at the tee and when putting. This requires a change to the way the intermediate or corridor is constructed. From a need point of view, the add doesn't have to be as large since the reading demand is for a scorecard and menu rather than sustained reading. Therefore the near size can be sacrificed. Secondly, golfers make more than average use of their peripheral field of vision as they focus on the ball, look out sideways to where they want the ball to go and back down at the ball. Then when swinging, this rapid motion requires overall peripheral clarity to easily track the ball. As a result, when balancing the design attributes of a progressive, if additional clarity is required for the periphery, the designer must consider that when thinking of the final size of the viewing zones required, especially the near and corridor design.

REDESIGNED DISTANCE

Distance vision is critical to the golfer. General use progressives narrow the distance field, especially as add power increases. It's a method used by designers to improve overall lens clarity by allowing a small amount of peripheral blur above the 180. Haven't you had patients complain about the peripheral clarity of the distance when they look straight ahead but turn their head? Our answer has always been "point your nose." However, narrowing any of the field of view can be problematic since the game of golf involves so many distances in specific postures. As a result, having the distance be as wide as possible facilitates dynamic eye movement for the golfer. The distance power of Shamir Golf has been optimized using free-form techniques and the "funnel" has been widened, i.e., peripheral blur is reduced in magnitude while the location is pushed down. The result is a wider, clearer distance. This is especially true along the 180 where a golfer's sight crosses when viewing the flag and when following the ball from the tee. The reduction in blur perceived by the golfer is a result of slowing the rate of change of unwanted astigmatism and locating it farther down the lens. It should be noted that this can't occur in isolation. Distance redesign must be accompanied by a redesign of the intermediate and near.

CORRIDOR AND NEAR

Redesigning the corridor and near zone is the key, then using the prescription, continue with optimization of the near periphery. The pres-byopic golfer requires clear vision of the ball at the tee and while putting. That's about 5 feet away, not the usual intermediate distance. Only a small near is required for scorecard visibility. Ordinary progressive lenses don't provide golfers with the extra help needed for the intermediate and peripheral viewing. The too large near adds peripheral blur just when focus and concentration are most important; the lenses let the golfer down.

Shamir Golf has an intermediate with a slower rate of power change in the initial corridor, the power held stable for a part of the corridor ending in a small near. In this way, the rest of the design can be balanced to provide increased clarity across the distance horizon especially the periphery along and just below the 180 line. In cross-section, Fig. 1 shows how the power is moderated to better suit the golfer's vision demands. It's easy to see how a regular progressive quickly becomes unusable for the golfer, delivering too much midrange power too soon.

OPTIMIZING THE RX FOR THE GOLFER

At the same time, your lab creates the prescription centrally as a golf lens; the periphery is redesigned for the Rx and the frame chosen using Shamir Prescriptor software. By customizing the lens' power edge to edge, using the actual vertex, tilt and wrap or optimizing it with the factory default values, overall lens clarity is improved. Golf optimizes vision and provides a more comfortable golfing experience by ensuring sharp viewing in all three critical focal areas—the far distant green, the ball at the player's feet and the scorecard, as well as enhanced peripheral vision.

The compensated power for the prescription ordered is evidence that the lens has been redesigned for the frame worn. In addition, the design of the lens periphery has also been compensated to provide better vision, reducing swim and blur. This can ensure a golfer's eye maintains optimal depth perception and contrast sensitivity because even minor prescription corrections can influence whether a challenging hole ends up scored with a birdie, par or bogey. Even when a patient declares, "I see just fine without glasses," an ECP should take the time to demonstrate how minor prescriptions can significantly improve their vision especially while wearing sunglasses.

MEETING THE THREE KEY ENVIRONMENTAL DEMANDS

Variable light levels, varying focal distances requiring central peripheral clarity for instant cues, contrast levels and topographical considerations dictate that maximizing depth perception, enhancing contrast and reducing haze are the remaining three visual challenges in golf. They are:

Depth perception: To facilitate tracking a golf ball against varying backgrounds and ground contours, maintaining a good depth of field is essential. Therefore dark lenses, with low transmittance levels, are not conducive to maintaining good depth perception. Most performance lenses designed for golf feature transmittance levels approximately 15 percent to 20 percent greater than typical general purpose sunglasses. Higher transmittance ensures a smaller pupil for increased depth of field. See the recommended transmittance and colors in the online version of this course.

Contrast enhancement: Improving the eye's ability to see and track a golf ball against varying backgrounds and light levels requires enhancing the edge of the ball. To help make a golf ball more distinct and easier to follow, changing the eye's habitual color response is necessary. In our vision, everything we see is compared against our experience, i.e., what we already know or are familiar with. The color response changes are accomplished through modification of the eye's tristimulus curve, or firing profile of the conical color receptors, is called chromatic contrast. The altered tristimulus response curve improves the eye's ability to distinguish and discriminate colors, as well as object edges, by alerting our eye and vision that "something's been changed." For the optician, it means using some colors that are outside your comfort level. It should come as no surprise then, to discover that gray—the most recommended general purpose sunglass color—is NOT favored for golf, precisely because it is fundamentally a neutral filter, and therefore will not affect a change in chromatic contrast. Where increased visibility or edge enhancement of an object is the goal, a changeup in chromatic contrast helps follow the ball better, and is described by sunglass engineers as "ball pop."

Blue light filtering: With the long expanses of grass found on a typical course, overcoming the haze created from evaporation requires suppressing blue, the color most scattered by the evaporating water vapor hanging in the air. For this reason, a performance golf lens will include colors such as amber, brown, purple and green, to suppress the blue spectrum (Shamir Golf is available in brown and green). Reducing blue light scatter is also advantageous when tracking a ball against the sky. In addition, the damage from the accu mulation of high energy visible (blue light) has been linked to macular degeneration.

Polarized lenses? Visual evaluation of these factors is enhanced through discrimination of the difference in the amount of light reflected by individual grass blades. Therefore a substantial reason why most performance golf sunglasses don't feature polarization is that these reflections from the blades are important in discerning the grain and contour of a green. The golfer's eye may use both grass blade reflection and deflection to assess ground contour as well as wind direction. The size, angle, wetness and sway of a blade of grass are visually enhanced, by allowing its full reflectivity. With polarized lenses so well-accepted and proven superior for glare reduction effectively sent to the bench in competitive golf, how can we design a lens to otherwise reduce glare and prevent eye fatigue on the course?

COLOR, GLARE AND THE GOLFER'S EYE

Because most golf course real estate is grass, you might think that a sunglass that emphasizes green above all other colors should prove superior for golf. But shifting our tristimulus curve with too much green may actually impede discriminating ground contours.

Therefore golf specific tints are simultaneously designed to: As we said, shifting the tristimulus curve with too much green may actually impede discriminating ground contours. Therefore golf specific tints are simultaneously designed to: Filter short visible blue light, which reduces haze, allow some long-wavelength blue light, which improves ball color (blue white) visibility. They typically allow just enough green to enhance visibility of ground contours. Transmission curves can be seen to suppress peak yellow wavelengths to reduce dazzle the eye and contributes to eye fatigue. Lastly, these lenses allow more red wavelengths, which helps the eye to distinguish the tones of green and grassy contours.

Indeed, a lens featuring a very saturated green color might highlight grass as a whole, but the cues a golfer seeks are actually much more subtle. When a golfer "reads" a green, they're trying to subconsciously process all the factors that will combine to influence both ball speed and trajectory during a put: A green lens might highlight grass as a whole, but hide the cues a golfer seeks since they are actually much more subtle. When a golfer "reads" a green, they're trying to subconsciously process all the factors that will combine to influence both ball speed and trajectory during a put i.e., slope, grass length, moisture Level (in and on the grass), base (firmness of green), wind and grain, blades facing the same direction (Source: The PGA Professional).

Sunglass engineers can approach this through different strategies. Some try suppressing yellow, the color to which our eyes are most sensitive. Others favor blocking more of the blue wavelengths, which our eyes have the most trouble focusing. Each approach has its own merit. But even as one company's golf recipe will often yield a different color profile from their competitors, all types are designed to enhance the visual performance of the golfer.

Brown or deep rose (sunny days), orange/amber (low light) and purple/lavender in photochromics (handles the varying light intensity during 18 holes) are colors specially suited to golf. Review the transmission curves of the variety of lenses available. Golf's variable lighting conditions favor lenses, which employ the convenience of photochromic properties.

Frames featuring interchangeable lenses of varying densities may appeal or prove better suited to particular players. Another approach has been using a flip-up style sunglass. However, golf research has shown that the all-or-nothing nature of flip-up suns may actually compound visual fatigue.

Consistent with avoiding abrupt changes to the golfer's eye, gradient-density lenses have proven to be less desirable. A player's dynamic eye and head motions may interact with the lens's gradient density area, and can result in decreased performance on the course.

See Graph 2 as an example of a transmission curve and its color properties as a golf lens. Polarized Lenses? - Visual evaluation of these factors is enhanced through discrimination of the difference in the amount of light reflected by individual grass blades. So a substantial reason why most performance golf sunglasses don‘t feature polarization is that these reflections from the blades are important on discerning the grain and contour of a green. The golfer's eye may use both grass blade reflection and deflection to assess ground contour as well as wind direction. The size, angle, wetness and sway of a blade of grass are visually enhanced, by allowing its full reflectivity. With polarized lenses, so well accepted and proven superior for superior glare reduction effectively sent to the bench in competitive golf, how can we design a lens to otherwise reduce glare and prevent eye fatigue on the course?

YOUR LENS CADDY, THE FRAME

Golf performance also depends on the engineering of the frame. These characteristics have been found to be essential in a frame specifically designed for golf:

Lightweight: A core golfer spends an average of four to five hours on the course during a typical round; comfort is a major issue. Not only should the frame be lightweight, it should fit snugly, stay in place and resist slippage, even in hot and humid weather. The best models feature rubberized nose-pieces and temple grips. Stability is also ultra-important, as players do not want their eyewear to distract them from their game. Choose heat resistant materials. Composite plastics and titanium-nickel metals are favored for their ability to retain their original shape and to resist heat absorption.

Wraparound construction: Since golfing depends so much on peripheral vision, non-distorting lenses that fully wrap around the eyes are important to block glare and deliver a wide, unobstructed field of view. Most purpose-built golf frames feature 8 D to 9 D base lenses in a semi-rimless construction. When addressing the ball, the frame's rim shouldn't distract a golfer's eye or influence their head position. Ideally, frames should also place the lenses close to the face—but not too close—in order to facilitate air circulation and prevent the appearance of a bogey-making fog.

Deep lenses for looking down: When looking downward, nothing should distract or require a golfer to modify or depart from their favored head, neck and shoulder posture. Avoid any style with lower lens edges that lay at or near the gaze angle. Advanced golf styles can address this problem by employing adjustable temples and bridges, to help tailor fit an uneven head or optimize the pantoscopic tilt of the lenses.

CHOOSE THE RIGHT EQUIPMENT

Consumer choice in sunglasses reveals a picture often centered most on cost and style, sometimes UV protection or "disposability"—in other words, every factor except task-specific or high performance considerations. For the golfer, this is a mistake. They spend significant time vetting both equipment and technique to extract every ounce of advantage for their game. Help the presbyopic golfer choose sunglasses in the same way that they select the best driver or iron. Consider the right equipment for the job; choose a separate pair specifically for golf—new and unique Shamir Golf progressive.

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