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	Polarized Lenses

When ordering from the lab, many opticians will request "Polaroid" lenses. This is usually a mistake. While the Polaroid company does manufacture some ophthalmic lenses, there are many other companies that make them as well. What they mean to order is "polarized" lenses. But the mistake is an easy one to make. It was Edwin Herbert Land (1909-1991), who first had the idea for polarization. His most famous invention was the Polaroid Land Camera, the first to develop its own prints in mere minutes. It first went on sale at Jordan Marsh Department Store in Boston in 1948. It sold for $89.95.

Nineteen years earlier (in 1929), he began to develop a process of polarizing plastic sheets in order to prevent glare. In 1934 he dubbed the revolutionary product "Polaroid." His original concept was to incorporate the technology in automobile manufacturing, by placing polarizing filters over car headlights and then even windshields. When the automobile industry rejected his proposal, his next idea was to incorporate polarization in sunglasses. Three years later (1937) Land pitched his idea to executives from American Optical (the largest optical company in the world at that time) in Boston. His demonstration was simple, yet powerful. Land placed a large goldfish bowl in direct sunlight, and asked the AO executives to view the tank. Even with sunglasses, all they could see was the bright sunlight being reflected by the glass tank and the water. Then Land handed them sheets of polarizing film and asked them to view the tank again.

Of course, they could now clearly see the colorful fish swimming in the tank. Soon thereafter, AO began to manufacture the first polarized sunglasses. These first lenses were nothing more than the polarized film laminated between two sheets of flat glass. The optical quality of the lenses was not great, and delamination was a frequent problem. Despite these initial shortcomings, polarized sunglasses grew in popularity.

Some opticians still resist dispensing polarized lenses because they worry about delamination, which was one of the most significant problems of polarized lenses in their early days. This is an unfounded fear. Today, all plastic polarized lenses are no longer laminated. They are manufactured with a thin polarizing sheet suspended between two molds. Plastic monomer is then poured around the film. As the monomer hardens around the film, the lens becomes a high-quality, integrated unit, which makes delamination impossible.

The brightness and intensity of light is measured in lumens. Artificial indoor lighting (whether incandescent or fluorescent), ranges between 400-600 lumens. If you go outside on a sunny day, you will experience @900 lumens in the shade to nearly 6,000 lumens reflected off concrete or asphalt. Every person is different, but most people begin to feel discomfort somewhere between 3,000-4,000 lumens. When brightness reaches the 4,000 lumens level, our eyes have difficulty absorbing and dealing with the light – regardless of whether it from a direct source (like the sun) or a reflected source (like the road). What we will begin to experience are flashes of white, which is called glare. Without proper protection (quality sunglasses and/or a wide-brimmed hat), all we can do to deal with this annoying glare is squint. When brightness approaches 10,000 lumens, your eyes will automatically block out the light. Prolonged exposure to light at this level can cause damage that could cause temporary, and in some cases, permanent blindness. That is why viewing a wide snowfield on a bright day without proper eye protection, sometimes results in snow-blindness.

The sun is the greatest source of harmful UV radiation in our environment. The sun provides visible light, heat, and ultraviolet radiation. Visible light consists of different colors of the rainbow (think R-O-Y-G-B-I-V – red, orange, yellow, green, blue, indigo and violet). The UV spectrum is divided into three parts, which have been dubbed UVA, UVB, and UVC. This classification is based on their respective wavelength. They differ also, in how they can adversely affect our skin and eyes. Remember, the shorter the wavelength, the more harmful the UV radiation. However, the shorter the wavelength the more difficult it is for the UV to penetrate the skin and cornea.

It is important for opticians to realize that the harmful effects of UV exposure are cumulative. That is why we should stress proper sunglasses to children. Their eyes are very susceptible to the sun's UV rays, because they have not fully developed their natural filtering capabilities. We also need to communicate to our patients that even on hazy, overcast days they are in danger from UV. Additionally, lighter-eyed people have less pigmentation and are in greater danger than dark-eyed people are.

UVA Radiation: The relatively long-wavelength UVA accounts for nearly 95% of the UV radiation that reaches the Earth's surface. It is mostly absorbed within the cornea. For many years, it was thought that UVA could not cause any lasting damage. Recent research, however, suggests that UVA in fact, does enhance the damage done by UVB.

UVB Radiation: Medium-wavelength UVB rays are the most worrisome. They burn the skin and damage the eyes.

UVC Radiation: On the one hand, these short-wavelength rays are technically the strongest. On the other, they are not a practical problem because they are absorbed by the upper atmosphere and do not reach the Earth's surface.

Let's look at how polarization actually works. As light travels from its source, its waves are not restricted to one direction of vibration. As illustrated below, light from a single source can vibrate in the vertical plane, the horizontal plane, and in any plane in between – all at the same time. However, upon passing through the polarizing filter, light is only allowed to pass through in one plane. The remaining light, manifested as glare, is absorbed by the filter.

Some people prefer to think of the polarization process as a 'Venetian blind process.' To think of polarization in this way, think of the polarizing film as a Venetian blind oriented so that the vertical light rays (reflections coming from horizontal surfaces) are blocked. Sunglass wearers' main concern is with horizontally reflected glare from surfaces such as snow, water, car hoods and bumpers, etc.

Because the main job of polarized sunglasses is to deal with horizontally reflected light, it is imperative that the polarizing film be properly oriented within the lens. Unless you are involved in surfacing your own lenses, this is the responsibility of the lens manufacturer and wholesale lab.

Many opticians do not realize that polarized lenses are available in a variety of densities and colors. Plastic, high-index, and glass lenses are all available in gray A and C, brown A and C, yellow, orange, red, violet, blue, and green. Polycarbonate lenses – which are becoming more popular for their durability and comfort – are only available in gray C or brown C. A and C are indicators of densities; A is used to designate the lightest shade; C is used to designate the darkest shade.

Gray is generally considered the color of choice because of its neutrality. Gray A can be tinted a little darker – or even made gradient. Gray A is good for dealing with surface glare on overcast days. The most popular choice of polarized lenses is Gray C. Nearly two-thirds (65%) of all polarized lenses sold in the United States are Gray C. Some people prefer the brown shades of polarization. Because they provide an excellent contrast against green backgrounds, avid golfers and fisherman swear by the brown shades. Additionally, those who are concerned with fashion mostly agree that the brown tones are more flattering against the skin.

Red and orange have many of the same characteristics of the brown lenses, but are especially appreciated by hunters, shooters, bikers, and skiers. Violet, blue and green have specific applications relating to specific colored targets and backgrounds.

Yellow is shown to give maximum contrast and is used to filter out blue light. The polarized, yellow lens is the best choice for low light conditions, such as driving in fog, or on cloudy, overcast days. Adding a backside anti-reflective coating to a polarized yellow lens makes it an ideal night driving spectacle. Some people request polarized lenses in clear lenses. With current technology, polarization is only possible with a film of some color, so clear polarized lenses are not possible.

You should check with your wholesale lab, but polarized lenses are available in single vision, FT-28, FT-35, 7X28 and 8X35 trifocals, and several progressive addition lens designs.

How do we best present the features and benefits of polarized lenses to our patients and customers? First, we need to understand the three basic benefits:

1. Elimination of Glare. The elimination of glare from surfaces such as water, snow, chrome bumpers, car hoods, and other horizontal surfaces produces two other benefits, namely:
   

2. Increased Comfort. One of the most widely reported benefits from polarized lenses is reduced squinting. Squinting can cause increases in tension and eyestrain, which sometimes leads to headaches.
   

3. Increase in Visual Acuity. Glare can reduce vision and is sometimes intense enough that whole objects are unable to be seen, or at the very least, obstructed.

Once you have convinced yourself of the advantages of polarized lenses, you must establish a routine that will increase your patient acceptance. What that routine is may be different for each individual dispenser, but for consistent success, you must consistently make the presentation. While it cannot be guaranteed that every patient who is presented with the advantages of polarization will order a pair, I can guarantee you that every patient who is NOT presented with the idea will NOT order a pair. So while every dispenser's routine may vary, it should include one key component: Present the option of polarized sunglasses to EVERY patient who enters your dispensary.

Prominent point-of-purchase posters and patients brochures can help raise awareness; another major factor in acceptance is an effective hands-on demonstration. Be sure to have a 'regular' (non-polarized) pair of plano sunglasses with a dark tint on hand. If you have easy access to a parking lot, locate an automobile that has glare reflecting off its hood. Have the patient view the car through the 'regular' sunglasses and ask her what she sees. Now repeat the demonstration using a pair of polarized lenses. The difference will be dramatic. If you do not have access to the outside, be sure to have a polarized display unit available. All of the major lens manufacturers offer very effective demonstration kits. Some even offer rebate coupons with the kit, so that they pay for themselves after a few pairs of lenses have been sold.

Two other characteristics of polarized lenses should be explained to the patients before they order their polarized lenses. The first is an additional benefit or selling point. Specifically, it should be explained that polarized lenses offer permanent UV protection. Many patients understand that overexposure to the ultraviolet rays of the sun can cause skin damage; some are still unaware of the potential danger that UV radiation can have on their eyes. According to Prevent Blindness America and the American Academy of Ophthalmology, "Ultraviolet radiation can play a contributory role in the development of various eye disorders including cataracts, pterygium, cancer of the skin around the eye, photokeratitis, and corneal degeneration." UV from the sun reaches us from reflective surfaces such as water, snow, and sand. Polarized lenses are the best, if not only way, to protect patients from BOTH ultraviolet and reflections. Some people think that a dark sunglass is the only protection they need. Actually, lenses that are simply tinted dark (and not treated for UV or polarized) can be MORE harmful than good. The dark tinted lens will cause the pupil to dilate, thus allowing MORE harmful UV light rays to reach the retina. It is imperative that the benefits of UV protection (present in polarized lenses) be impressed on all eyeglass wearers.

The second thing you must explain to your patients is the fact that polarized lenses possess two characteristics that are sometimes seen as negative. However if effectively explained on the front end of the dispensing process, they should not cause rejection or ill will on the back end. One of these is sometimes referred to as "cross hatching." It is called cross-hatching because of the pattern that can sometimes be seen in automobile windows. This is because the car's side windows are tempered to make them less likely to shatter in an accident. However, any tempering induces internal stresses that can be 'seen' when viewed through polarized lenses. The resulting pattern is similar to the one that is seen when checking ophthalmic lenses for stress through a colmascope. Effective explanations of this phenomenon will alleviate any problems. The cross hatching is simply a characteristic of the lens; once explained it will readily be accepted by your customer

The other phenomenon is related to electronic items or instrumentation that is made with LCD (liquid crystal diodes) displays. When viewed through polarized lenses these readouts can be obscured or even completely blacked out. Most commonly this is a problem with certain automobile instruments and even the readouts on many gas pumps. Opticians must describe this characteristic, and explain to the patients that this can be dealt with by simply tilting their head @ 45 degrees. The numbers will then be visible. Manufacturers are finally becoming aware of this 'problem' and are dealing with it by orienting the angle of their readouts so that they will not be obscured when viewed through the ever-popular polarized sunglasses. In years to come, this will not be a problem.

One of the newest additions to the family of polarized lenses is Drivewear^®. Made in partnership between Transitions^® and Younger Optics, it is, of course, photochromic. What makes it different is that it is also polarized. And more incredible, it not only darkens from exposure to ultraviolet light, it is affected by ambient light as well. This makes it the first such lens that changes color behind the windshield of a car. Some of its other characteristics are that it is never clear. It starts out a light yellow-green. Behind the wheel of a car it turns to @ brown 2. In bright sunlight it turns a darker, brown-orange color – similar to a Serengeti sunglass. While its popularity is gaining (they are currently available in single vision and progressive designs), they are not recommended for driving at night.