Defensive Driving Just Got Easier
With Drivewear lenses anyone can feel more comfortable behind the wheel

By David Rips, President, Younger Optics

Today our lives are strongly influenced by the automobile, which has transformed the way we experience the world when we are outdoors. For commuting and pleasure driving, good sight has a significant effect on safety and comfort. Now for the first time, new Drivewear lenses are capable of sensing and reacting to varying light conditions both outside and inside the car to always provide a wearer the right visual solution. As a result, wearers receive the right sight.

In the past, clear eyewear was enough. In bright light conditions, polarized sunwear was enough. This is no longer true. We need a third category of lenses in our modern, automobile-centered world i.e., lenses that provide light-responsive protection so that varying intensities of light are filtered and polarized reflections are eliminated.

This new category of lenses, called Drivewear, is capable of sensing and reacting to varying light conditions both outside and behind the wind-shield of the car. From bright sunlight accompanied by intense, blinding glare, to overcast inclement conditions, these lenses provide the wearer with the appropriate visual solution.

Drivewear lenses provide glare protection through polarization and enhance and protect vision through photochromics, which respond to both visible and UV light. Combining the strengths of two of the most important technologies in sunwear today provides wearers a lens for tomorrow.

Life continues to increase in complexity and lenses must meet that complex need.

Milestones in Sunwear
� Sunglasses made from baleen, ivory, shells or wood by Inuit or Eskimos, predates eyewear, had small slits that only allowed a fraction of the light to come through to the wearer�s eyes preventing snow blindness. The inside of the groove was often charred for anti-reflective properties.
� G-15 became synonymous with high performance during WWII. Bausch and Lomb met the need to reduce glare and improve contrast for the critical vision of pilots.
� Edwin Land discovered that a pencil placed atop a plastic sheet would straighten out when the plastic was stretched. He realized that by stretching film embedded with iodine crystals, they would line up to create a polarized film. Originally, for auto headlights and windshields to block the glare of oncoming headlights, this idea was never economically or practically feasible. American Optical introduced Land�s polarizers as sunwear in 1939.
� Through the 1960s lifestyle changes demanded lighter lenses in colors. PPG introduced CR-39 and lenses have changed from a medical necessity to a fashion item.
� People�s lives indoors and outdoors became more intertwined. Photochromics improved comfort and protection both indoors and outdoors.
� As outdoor activity increased, tints were not enough. During the 1990s, polarized lenses became the norm for prescription sunglasses.
� Life continues to increase in complexity and lenses must meet that complex need.

AN EVOLUTION OF OUTDOOR ACTIVITY AND THE COMPLEXITY OF DRIVING DEMANDS BETTER VISION

Automobile drivers are still the largest untapped sunglass market, prescription or otherwise. In 2004 there were nearly 200 million U.S. drivers. Average commute times are growing longer� everywhere. There are 250 million total motor vehicles registered in the U.S. and more than one billion motor vehicles registered world-wide. Unfortunately, nearly twice as many people have been killed in the United States since 1920 in automobile accidents than soldiers were killed in all the wars in American history. So, constant improvement to the safety of the auto and the driver are critical.

Driving is an activity for which nearly everyone needs eyewear/sunwear. At every moment of the driving task we are constantly being challenged and assaulted by distractions attacking our ability to drive safely. While juggling a cell phone in one hand, adjusting the radio or CD in another, catching a quick lunch and trying to keep kids in the back seat quiet, it all just becomes too much to handle.

Making driving even more difficult are changing road and weather conditions, driving tired or just not feeling our best. Many people also cope with physical challenges or age that may slow driving reaction times. All this makes driving an extremely complex task even under the best of conditions. Sometimes it is a wonder we are able to arrive anywhere safely. Truly, we are bordering right on the edge of our ability to handle all these stimuli and when we go over that edge, we are in very real danger of having an accident.

The main tool used to cope with all driving challenges is vision. Yet vision is also pushed to the limits while driving. It takes about a quarter of a second to process and react to a driving visual incident, and if you are traveling at 60 mph, that translates to about 22 feet. Clearly we need all the visual crispness we can get to drive safely. The most common and dangerous visual assault, which is also unpredictable, comes from blinding glare.

This glare can be intense sunlight reflected from an endless variety of smooth surfaces such as the road, hood or dashboard of your car or even the bright chrome of the car in front of you. These conditions are especially harmful when the sun is low on the horizon, such as early mornings and late afternoons, which are also peak commuting times. Polarized lenses are the best solution to eliminate blinding glare.

While bright sun and glare are the most obvious visual dangers while driving, sometimes the conditions we drive in are the reverse: overcast, often with inclement weather, and less light. For these conditions we want a lens that is as light as possible and also of high contrast to help accent already hazed objects. Polarization protection is still important during these times because glare, particularly road glare, is random and can unexpectedly hit at any time; since the eye has accommodated to these overcast conditions (larger pupil) it is particularly susceptible to blinding, bright glare.

Drivewear lenses were developed to specifically address the driving task. They are polarized at all times and designed to shift between a lighter and darker color as visual conditions change, even within the car. Current clear-to-dark photochromics require UV to darken�but UV is absorbed by the car�s windshield preventing their reaction. By combining new photochromics and a special polarizing filter, a lens is available that is a significant improvement in driving eyewear.

A Short History � Vision Improvement and Protection
The appearance of written language challenged vision. Before that, if you didn�t see that saber toothed tiger before it was too late, oh well. So, creation of the written language actually signals the beginning of the need for eyewear.
Until printing and the Gutenberg Bible, no mass method for producing the written word existed. Manuscripts were written by hand, were in Latin, most were religious documents and had very small circulation. Within a generation of the printing press, the number of literate among the common man increased significantly. Over the next 200 years mass literacy grew, and as western culture experienced reading and writing, the privileged that lived into their 30s and older noticed their vision deteriorating over time. With the forces of a changing world leading to the Renaissance it is no coincidence that eyewear developed at about the same time.
No one can doubt the influence the automobile and its affect on expanding people�s ideas of life. With travel and the expansion of every-one�s world better vision and comfortable sight was a goal.
The postwar era of the 1950s increased leisure time and an enjoyment of the outdoors. As people had more free time, improvements to sunwear made being outside more enjoyable. Whether it was going to the beach, going for a hike or just taking a walk, people began to think about sunwear differently. Eyeglasses in general began to become more fun.
The carefree attitude that many of us had did not last long as we began to discover that being outside was not without its costs. Long-term exposure to sunlight has been linked to skin and eye diseases. While these studies are ongoing, the message is clear: If you are going to spend time outdoors in the sun your skin and your eyes need to be protected. This trend has led to a whole variety of optical products.

THREE UNIQUE LIGHTING DEMANDS

Single pairs of sunwear or eyewear are a compromise for all the needs of the wearer in any day. While lenses like photochromics worked well indoors and got darker outdoors, they did not work well behind the windshield of a car. They also did not provide polarization to block blinding glare, an essential part of any quality sunglasses.

Polarized lenses worked well in bright sunlight even behind the windshield of a car and did block blinding glare, but often were too dark during over-cast or inclement weather. In addition these lenses were always just one color, even though optimum vision would have been better if the lens were able to change during varying light conditions.

Different Conditions Making Driving Difficult Variable weather conditions, such as bright light, haze in the early morning or late afternoon when the sun is low on the horizon, bad weather or overcast skies cannot be served by just one pair of traditional eyewear.Direction, speed, other cars, traffic signals, signs, driving hazards (road debris, construction, people crossing, etc.), all contribute toward making the driving task exceedingly difficult.Add sound distractions (cell phones, radio, DVD players, kids yelling in the backseat, spouses giving directions), which are multiplying in number and leading to accidents. Blinding glare from highly polished dashboards that reflect images onto the windshield, car hoods that are highly angled, highly polished chrome both on the car and from the cars around the driver reflect sunlight into the driver�s eyes. Windshield tint and dirt can significantly reduce vision for the driver and spectacle lenses without AR contribute to a less than clear world. The opportunity is to attack conditions that can be changed to improve driving.

A more ideal solution is a lens that adjusts its filtering ability behind the wind-shield of a car and outside in the presence of bright light and which still works both outdoors and behind the windshield of a car when the weather is overcast.

At low light conditions, Drivewear lenses provide high transmission of light (37 percent VLT) to maximize the total information to all the eye�s visual receptors. The lens� optimized low light transmission curves allow visual comfort and a highlighting effect from the combination of contrast enhancement and higher starting transmission. The curve is designed to promote some contribution from the Blue (S-Types) visual receptor cones in the eye. This results in maximum visual acuity at low lighting levels. The high-contrast polarizer removes glare that would otherwise reduce discrimination and vision in low light conditions. In this stage the lenses are a high-contrast green/yellow color. This color is better designed for either outdoors or while driving under low light, overcast conditions.

Behind the windshield of a car, during bright light conditions, a special photochromic system from Transitions Optical reacts to visible light, activates and provides lower overall transmission to control light intensity for optimum visual acuity. This color and the selective transmission of the lenses promote preferential activation of the eye�s red cones (and to a lesser extent, green) and result in the optimized vision at these higher light levels. The high-contrast polarizer is absolutely essential behind the windshield of the car because it blocks the random and potentially catastrophic effects of blinding glare, one of the most dangerous of all driving hazards. Under these conditions, Drivewear lenses turn a copper color tuned for high contrast, comfort and optimum for a driving lens. This unique behind-the-windshield response protects against bright light and glare and provides better sensitivity to the �visual signal� that is vital for safe driving.

In outside bright light conditions, the eyes� visual receptors, the rods and cones, can easily get �overpowered� and �oversaturated� with light. Under these bright outside conditions the lens is designed for maximum filtration of excess light. It achieves its maximum dark color under these conditions. Here again, it is important to provide maximum protection from blinding glare and only polarized lenses can do this. They are designed to provide maximum comfort for the wearer in high outdoor light conditions.

Seniors are especially sensitive to glare and also because of a constricted pupil, cloudy media, the presence of cataracts and/or age-related macula degeneration (AMD) require good daytime sunwear. In addition, dark adaptation by the rods is significantly affected by their bleaching during the day, so the right density filter at the right time is critical. High-contrast colors and polarizers also enhance what might be a reduced acuity. Drivewear lenses are probably an ideal daytime lens for the senior.

THE DRIVEWEAR ENGINE�MULTIPLE ELEMENT SYSTEM

The Drivewear engine is a unique concept invented and patented by Younger Optics (patent number 6,926,405 B2). A high efficiency polarizing filter was developed and unlike other lighter density polarizers, the polarization efficiency is equivalent to dark polarizers. Younger Optics� realized that combining such polarizers with photochromics that are activated by visible light as well as UV would create a novel and needed product. They looked to Transitions Optical, one of the foremost innovators of photochromic technologies, for the latest developments in visible and UV activated dyes to enhance the Drivewear lens.

HIGH EFFICIENCY POLARIZERS

Typically, efficient polarization only occurs when there are large quantities of absorbers present�that is, when the lenses are dark. Low light and overcast conditions require higher transmission for better vision and a high-efficiency polarizer for safety. A high-efficiency polarizer that provides excellent polarizing properties was not available in such a high-contrast light color. A new polarizer was achieved by pushing the polarized manufacturing technologies and processes to achieve exceptional efficiency and light transmittance.

Polarized lenses are often described by wearers as �the most comfortable sunglasses I ever owned.� This is because polarizers are uniquely able to reduce glare from two widespread physical phenomena: Rayleigh scatter and Brewster�s angle reflections. In the 1800s Lord Rayleigh (Sir William Strut) described how molecular sized (really nano-sized) particles scatter light in the atmosphere, particularly the shorter blue wavelengths. This scatter causes the haze seen in foggy, smoky or smoggy skies. Polarized lenses significantly reduce this scatter by nearly eliminating the horizontally reflected rays. In addition, Drivewear lenses further reduce blue light because of their selective absorption dyes.

Blinding glare is caused by preferentially polarized reflections from surfaces and these reach their most intense level when light hits a surface at Brewster�s angle (named for the Scottish physicist who studied this phenomenon, Sir David Brewster). Polarized eyewear, including Drivewear, is specifically oriented to intercept this preferentially polarized, blinding light, thus reducing �noise� on our visual signal.

LOW LIGHT CONDITIONS � SINGLE ACTION

High-efficiency polarizers have not been available in light color lenses. By developing and featuring a high-efficiency polarizer never before found in such a high contrast and light color, the lens is designed to maximize the useful light reaching the eye in low light and/or overcast conditions. This polarized film is active in every lighting condition to block blinding glare and improve visual acuity.

At low light levels, the special photochromic molecules, by Transitions Optical, remain in an uninitialized or �resting� state. In this state, the polarizer is the main agent to control the visible light that comes through the lens.

Bright Light, Driving � Dual Action
One of the most unique and special attributes of this lens is that it is the only photochromic lens to darken behind the windshield of a car. Exposed to visible light, the lens changes to a copper color, which many drivers find is a more comfortable color for driving. This color was designed to both remove excess light and provide good traffic signal recognition.

When the photochromic molecules become exposed to an energy source (bright sunlight), a complex reaction occurs and changes the shape of the molecules. Uniquely in Drivewear, this activation is initiated not only by ultra violet (UV) light, but also by visible light so in the driving situation the molecule begins its bond breaking and reforms to a new structure that reduces transmission slightly.

In this mode, the lens provides glare protection (due to the polarizer) plus an intermediate level of transmission, consistent with the slightly reduced light entering the vehicle windows.

BRIGHT LIGHT, OUTDOORS � TRIPLE ACTION

Outdoors, the lens is activated by UV and visible light and deepens to a dark reddish-brown color. This color was designed for maximum filtration of excess light and to provide maximum protection from bright light and blinding glare. The reddish brown color of the lens provides excellent color recognition with a special emphasis on highlighting greens. Green is the most common color in the natural landscape.

In the fully activated state, the photochromic molecules are folded into new configurations. These configurations absorb light more effectively than the resting state, and therefore, the lens looks dark. When the energy source is removed, the molecule will return to its original position and the lens lightens in color. With Transitions Photochromic Technology, this process can be repeated over and over for the lifetime of the lens.

In addition, Drivewear lenses have been engineered to block 100 percent UV A and UV B under all lighting conditions. This is an advantage of being activated by Transitions.

SOME CURRENT CAVEATS

Drivewear lenses are optimized for sunlight response. They should not be used for night driving. Many vision and highway safety experts believe that no tint should ever be used at night. The driver needs all the light they can possibly get. AR lenses should be prescribed and recommended for night vision needs and driving.

Like all photochromic lenses, they will become much darker in cold, sunny weather, and this may limit visibility. Use special caution when operating open air vehicles such as convertibles, motorcycles, snowmobiles, or all terrain vehicles or engaging in activities such as skiing or snowboarding.

Mirrored surfaces make sun lenses look great and reduce or eliminate UV and infrared. However, Drivewear lenses should not be mirrored. Visible light is reduced by a mirrored surface reducing the photochromic action of the lens inside the car. This is very dependent upon the density of the mirror. A very light flash mirror may let enough visible light penetrate to activate the lens, but its response would probably be reduced. Remember, silver flash mirrors reduce transmission about 10 to 15 percent. Other very intense and reflective mirrors significantly reduce visible light, and will reduce the effectiveness of these lenses.

Anti-reflection coatings enhance any sun lens and the same is true of polarized and photochromic lenses. This is particularly true on the back surface as it reduces the mirror effect of a darkened lens and the magnification effects of a concave surface. Many coating laboratories prefer to coat both front and back of lenses and this is recommended.

Current Drivewear lens availability is single vision hard resin in a full range of base curves for virtually any prescription. Consult your laboratory for assistance.

DOES THE SUN BOTHER YOU WHEN YOU DRIVE?

This is a simple question to ask all patients to open the door for a discussion about sunwear for driving. If they are already wearing photochromics, you have had the discussion on the effectiveness of a polarized clip or pair of polarized prescription sunglasses. Having a lens that is specially designed for today�s driving experiences allows a discussion of the technologies so that patients understand the benefits and can agree that there is an advantage to them in having this type of lens in a pair of glasses.

Always ask the question and describe the benefits.