POLARIZED SUNGLASSES:

Everyone's Most Important Piece of Equipment Outdoors (Part 2)

By Alexander Bennett

When professional athletes are competing, they must take into account varying conditions that can affect their game play. Sailors and volleyball players need to consider wind direction and speed more so than someone on a tennis court. Consider lighting conditions: Trail runners and mountain bikers may be in and out of trees on a partly cloudy day. How do these conditions affect their visibility? And what sun lenses will help them best navigate the uneven terrains they are negotiating?

The proper lens selection can be critical when making important decisions in the situations described above (even lens size and shape for the wind). With all of the different lens colors available, how is a patient able to make the most informed decision? The knowledge and skill of the dispensing optician can ensure that a patient is able to maximize their experience for any lighting conditions. This part of the course investigates polarized lens colors, along with prescription options to help the consumer select the best polarized sunglass lenses for their needs.

TWO FACTORS AT WORK

There are two factors at work in a polarized sun lens that benefit the wearer. First, the polarized filter eliminates obstructive blinding glare for clear and uncompromised vision.

Then the color of the polarizing filter reduces transmission while selectively absorbing or transmitting colors. This allows the lenses to enhance or soften the effects of particular colors to the wearer. By selectively filtering particular wavelengths of light, the human eye can more accurately perceive outlines and sharpen the edges of a baseball, as an example.

Color differentiation creates a need for lenses tailored to specific situations where edge variations and contrast are important to the wearer. Proper color selection provides optimum vision and comfort in all bright environments encountered by the wearer. Care must be taken when selecting lens color, because certain lens colors might be detrimental to the wearer in certain instances.

Lens colors can alter the wearers’ view of their environment, and it is important to demonstrate how by providing samples. It should be noted that some patients can find these colors “strange” because they are not used to how the look of their surroundings change once worn. Show patients different color samples, and allow them to experience the outside world through these lenses. While some patients might resist, it is important to empha-size their benefits and allow the patient to choose what will work best for them.

Let’s think of the way that we discuss sunwear with patients and why we recommend certain colors. You could say: “Tell me your outdoor activities and/or sports.” If the patient replies with: “Early morning walks along the ocean, some deep sea fishing, driving on nice sunny days, I usually wear sunglasses all of the time.” What would you suggest? This is where an understanding of various lens tints will enable the optician to make the best recommendations for each case.

GRAY LENSES

As one of the most common polarized lens tints paired with plano sunglasses, gray is an all-around neutral lens. Gray lenses typically allow around 15 percent light transmission and filter all wavelengths of visual light evenly across the spectrum. By reducing light intensity, gray lenses keep colors true to the observer, thereby enhancing depth perception and reducing eye fatigue in overall bright light conditions. These lenses are best for bright, sunny days from morning until dusk. These lenses are not well-suited for overcast days with minimal sunlight; the deep density and darkness of the lenses can be a hindrance to the wearer and reduce overall acuity in these specific situations.

Gray polarized lenses are recommended for: running, cycling, skiing, baseball, deep-sea fishing, beach volleyball or sailing. These lenses are also highly recommended for anyone who spends a lot of time on or near the water. Gray lenses are well-suited for everyday wear and are a great option for a patient who needs versatility from a single set of sunglasses.

GRAY-GREEN LENSES

Pioneered by Bausch and Lomb, and touted as an exceptional lens for pilots, the gray-green lens option remains a popular lens color. Research conducted by Wilson Sterling, Ph.D., concluded that gray-green lenses are very pleasing to the majority of lens wearers due to the comfort of the hue of the filter as experienced by the observer. In his research, Sterling mentioned that gray-green lenses were preferred by the observer over a standard gray in most cases.

By combining a deep green lens with the deeper density of gray, these lenses offer the wearer superior protection in bright light environments. These lenses filter longer wavelengths of light from 550 to 700 nm, including yellow, orange and red. These colors allow for increased contrast from the lower wavelengths. Gray-green lenses include a peak transmittance around 500 nm, or the green wavelengths, to which the human eye is most sensitive. The edge enhancement capabilities of the gray-green lens have kept it a long-standing favorite for almost any sport or as a casual lens color.

BROWN LENSES

Similar to gray and gray-green tints, brown is one of the most common color tints paired with plano sunglasses. Polarized brown lenses block blue wavelengths of light from approxi-mately 400 to 500 nm. By blocking these specific wavelengths, the blue-violet and blues, brown lenses provide high-contrast and color enhancement to the wearer by maximizing detail from green wavelengths and reducing the scatter and haze that the shorter blue creates. This is especially true against green and blue backgrounds, such as grass and sky, making these lenses perfect for the active hiker or a patient looking for a comfortable all-purpose lens. Brown lenses are best on bright days or light overcast conditions, but provide excellent acuity in partially cloudy weather with reduced incident light due to the lenses’ ability to increase overall contrast.

Recommend brown polarized lenses for cycling, running, baseball, water sports or for casual wear. Many anglers tout this color of lens to help spot fish swimming in shallow waters, but they may be less effective for deep ocean fishing where the water is much darker. Care should be taken when recommending brown polarized lenses to golfers, especially if they are looking for one set of glasses for sport and recreation; some golfers prefer brown tinted, non-polarized lenses due to reduced visibility when “reading the green” as grass blades bend at different angles and scatter reflected light.

HIGH-ALPINE GRAY LENSES

High-alpine gray is an especially dark gray lens for use in high altitude environments. These gray lenses may or may not be polarized, depending on the wearer’s preferences; standard tinted lenses increase visibility around ice, which may be important in certain cases. These lenses, at 8 percent or less light transmission, are crucial for alpine enthusiasts who need maximum vision and eye protection in environments with extremely high levels of UV radiation. These lenses are usually considered a category 4 lens, referring to its density and light transmission, and by ANSI Z80.3 standards these lenses are considered unacceptable for driving; special consideration should be used when recommending these lenses.

ORANGE AND YELLOW LENSES

First, one must know that the density (darkness) of a polarized lens is directly related to polarizing efficiency, i.e., the lighter the lens, the less it polarizes light. Therefore, using colors such as orange, yellow, rose and light green lenses are a trade-off between the advantages of polarized lenses and the effects of the lens’ color. Some light-colored polarized lenses may be only 20 percent polarizing.

Orange and yellow lenses are quite similar, but each offer their own distinct advantages to the wearer. Orange lenses offer high-contrast for intermittent light conditions. These lenses can offer the wearer improved depth perception in overcast conditions, as well as rain, snow or fog; a light transmission of 70 percent offers good protection in most cases except for bright sun. Orange lenses block blue wavelengths of light (450 to 500 nm), which can make objects appear hazy. These lenses are recommended for sport shooters and skiers in low-light situations, especially in the mornings and evenings, but not as much light transmission as a yellow lens.

Yellow lenses, sometimes referred to as “blue-blockers,” greatly increase contrast and depth of vision. Yellow lens tints have the ability to filter out “hazy” light that is hard on the eyes and makes the wearers’ environment seem brighter. These tints are typically favored by shooters and skiers for the incredible acuity provided to the wearer in sports that demand the most precise vision. Due to a high light transmission, typically around 85 percent, these lenses excel early in the morning, around sunset, or on overcast days during rain, fog or snow; these lenses provide minimal relief during bright, sunny days.

Yellow lenses have been touted as a solution to night driving situations where the wearer needs increased contrast and illumination. The thought behind these glasses is that they might enhance contrast, helping to distinguish objects in the dark. The truth of the matter is that tinted lenses cut down on the amount of incident light reaching the retina and ultimately obscure conditions. Studies conducted by The Sunglass Association of America says that yellow lenses sold for night driving only make the wearer think that they are seeing better. The Federal Trade Commission has litigiously ruled against eyewear manufacturers on several occa-sions for improper claims that yellow-tinted “night driving” glasses actually help the wearer. The best solution to help with night driving remains a clear prescription lens with a quality anti-reflective treatment.

ROSE LENSES

Rose lenses sharpen focus and contrast for the viewer in a variety of light conditions. Another favorite color among skiers, mountain bikers, trail runners and baseball players in varying light, these lenses are excellent for activities where detail is important. With a light transmission around 30 percent, these lenses can be suitable even on sunny days, although an additional mirror might be preferred by the wearer to help reduce the over-all brightness of incoming light.

Rose colored lenses are also important for patients who suffer from migraine headaches. Researchers at the University of Utah have found that a specific rose tint, known as FL-41, may provide relief for these patients. Migraine sufferers can be extremely sensitive to stimulation such as odor, touch and sound, but intense light sensitivity can be one of the most debilitating side effects of these headaches. Research has shown that blue and green wavelengths of light (450 to 570 nm) are attributed to causing the most discomfort to these patients. FL-41 rose lenses filter these particular wavelengths, thereby making the wearer less sensitive to light. While these lenses are not touted as a “cure-all” for migraine sufferers, the effectiveness of these lenses have been demonstrated in certain cases to alleviate visual discomfort.

GOLF AND TENNIS LENSES

Golf and tennis-specific lenses are designed for high contrast and color differentiation when tracking a ball by blocking red wavelengths of light between 610 to 700 nm. These wave-lengths allow for improved contrast differentiating various cuts of grass and environmental haze to more accurately contrast the white ball. While not a polarized lens, the merits of this lens are important to understand and recom-mend when a golfer is looking for a lens designed specifically for the course. These green-based tints are designed to provide a balance of target and background brightness. A light transmission around 25 percent accom-modates for grass reflecting a low amount of incident light, while providing enhanced ball illumination. While generally referred to as “golf” tints, this color of lens is well-suited for tennis where precise vision is necessary for the split-second decision making. The lenses are also designed for a variety of light conditions, from bright light to overcast conditions. This lens may not be ideal for all-around wear and is typically recommended for the specific sports previously mentioned.

MIRROR COATINGS

Mirror lenses are a cosmetically appealing option for any sunglass, but provide several advantages to the wearer. These types of lenses can actually block incoming light, up to an additional 12 percent, depending on the type of mirror applied—whether a flash or solid mirror coating. Mirror coatings do not obstruct or add additional reflection for the wearer and can make lighter density lenses more comfortable for the viewer. Mirror coat ings also have the benefit of adding hydrophobic and oleophobic properties to the front of the lens, helping to repel dirt and dust while making the lenses easier to clean. These properties ensure unobstructed vision in competi-tive settings, but are beneficial to any wearer.

VARIABLE DENSITY AND PHOTO-CHROMIC POLARIZED OPTIONS

Patients who need versatility from a single set of lenses might benefit from a variable density polarized lens. There are two versions today—varying the polarizing efficiency by UV or creating a gradient of fixed polarization from top of lens to bottom. In the first instance, these lenses offer the advantage of a polarized sun tint while remaining virtually clear while inside or after dark. One example would include a patient who regularly attends football games, but does not want to carry a second set of sunglasses. As the sun sets and the day turns to dusk and into night, the lenses adapt to the varying light and turn from a polarized sun tint back into the patients’ clear lens without having to think about changing glasses. Skiers can also take advantage of similar technology in goggles from Zeal and Smith, for those opticians who have a high demand for prescription inserts for these sports.

The second variable density lens is a polarized gradient lens that includes a deep tint at the top and gradually lightens toward the bottom of the lens. These lenses, available from retailers including Maui Jim and Nike, provide the advantages of a polarized lens and the fashion of a gradient finish to provide the wearer the cosmetic appeal they desire in their sunglasses; prescription lens options are available from Younger Optics. Variable density/efficiency polarized lenses are available from specialty sunglass manufacturers such as Rudy Project, which are available in both prescription and nonprescription lenses. Variable polarization lenses are also available in the Transitions family of products (known as Transitions Vantage lenses) and are available in several material options for patients who want this feature in their ophthalmic frames.

PRESCRIPTION OPTIONS

For patients who need prescription lenses, there are several options to consider. What might be a suitable solution for one patient might not be useful to another, so getting a sense of how the wearer will use their sunglasses is essential. All patients want protective sun lenses for their daily activities, such as commuting, having lunch on a patio or walking around a pedestrian mall. However, if the wearer also intends to wear these lenses while cycling, golfing or skiing, lens consideration should be carefully examined.

One great option for patients is a prescription insert that adapts directly into a frame; popular options include the Rudy Project Rydon, Adidas Evil Eye Half Rim Pro and Wiley X Valor. With a prescription insert, the patient gains many advantages over a direct prescription lens including: interchangeable lenses for different types of lighting environments, a lower cost of investment and the ability to easily change prescription lenses in the future. The flatter curvature of the insert allows for a higher range of base curves to optimize the optics of the prescription lens and allows for a much higher range of prescriptions.

There are several disadvantages to prescription lens inserts including: increased fogging between lenses, they can be more difficult to clean, having to manually change the lenses to suit the conditions, carrying more gear to change lenses and disrupted vision if the insert rotates. The last point is especially problematic for progressive lens wearers and patients with a high degree of astigmatism correction.

Conversely, direct prescription lenses offer their own pros and cons. Advantages to the wearer include: carrying less gear, they are usually lighter in weight and have no need to realign after cleaning or moving the insert. Limitations can include the inability to change lens color depending on conditions, a more limited range of prescription availability and higher cost of replacing lenses. Polycarbonate, Trivex and high-index lenses each have limitations in their ability to be tinted, and polarized lenses are usually recommended to ensure the proper darkness is achieved for the wearer. This can prove problematic for a patient with a high power prescription desiring a prescription golf lens that is not polarized, as an example.

An alternative to both options listed above is a polarized photochromic lens such as Transitions Vantage or Rudy Project Polarized Pho-tochromic lenses. These lenses provide the adaptability of a light-dependent variable transmission lens with the comfort and clarity offered by ophthalmic frames. These lenses are great for patients who want versatility from a single set of glasses since the base curve of ophthalmic frames are optimized for any prescription. They also receive the benefit of a polarized lens in bright, direct sunlight without having to change to a different set of glasses. Currently, variable polarized lenses are only available in the gray color option, but are available in CR-39 and polycarbonate material options, which meet the prescription range of +3.00 to -4.00; more than 75 percent of the prescription population.

RECOMMENDING LENSES

Sunglasses are an important piece of equipment for every patient. Since the best recommendations come directly from the doctor, hopefully the conversation started in the exam lane. If not, it is up to the dispensing optician to recom-mend sunglasses to every patient, including plano options for contact lens wearers.

A good way to start the conversation is by simply asking a patient: “What glasses do you wear outside?” or “Do you have your most current set of sunglasses with you?” If patients bring in cheap gas station sunglasses, it is important to educate them about proper UV filtration. If those sunglasses do not properly filter UV light, the patient is flooding their unprotected and dilated eye with harmful radiation.

If a patient does not have any sunglasses, it is important to educate them about how sunglasses can help them perform their everyday tasks with increased comfort and make their recreational activities more enjoyable. Clips-on or fit-over style sunglasses are good accessories, but they can be cumbersome and may not provide enough protection when worn at the beach, for example. Educate the patient about how one set of glasses cannot meet all of their demands and reinforce that they are providing additional protection to the eyes and skin while increasing visual acuity.

Once the recommendation for sunglasses has been made, it is important to discuss how and where the patient will be using them. If a mountain biker needs a set of glasses for cycling, a high-wrap frame with a fixed amber or rose lens may be a good option. If the patient is OK with carrying extra gear, they might opt for a frame with interchangeable lenses. If the cyclist also wears contact lenses, they might want both plano and prescription lenses to enjoy the flexibility of choosing which lenses to wear on a particular day. Conversely, the patient might want a single casual, yet functional, set of sunglasses to use on the trails after a business lunch. Once prescription options have been discussed, the patient can choose the best frames for their needs. Finally, by understanding which lenses excel in particular environments, the dispensing optician can help guide the patient to select the appropriate lens color(s).

One last point: If at any time the patient expresses that they use their sunglasses for any sport, make sure to recommend a safety material for the lenses. In Part 1 of the course, it was stated that approximately 90,000 sport-related eye injuries could be prevented annually, so recommending a safety material such as Trivex or polycarbonate is absolutely essential. The wearer should always have maximum protection for their eyes, no matter what circumstances they are wearing them.

CONCLUSION

Sunglasses are an essential piece of equipment for any patient, not just competitive athletes. There are sun lenses for any use: from recreation to specific needs and everything in between. With product knowledge and by understanding a patient’s needs and expectations from their sunglasses, you can confidently recommend a lens to maximize a patients’ experience and provide the best solution for their lifestyle.