You pop a compact disc into your stereo for some crisp, clear musical enjoyment... or a CD-ROM into the computer for your kids to play a game. These discs are made of polycarbonate. You are preparing a cake recipe in your mixer...or a fruit shake in your blender. The bases of both of these kitchen appliances are most likely made of polycarbonate.

Super-strong polycarbonate is, in fact, used in a variety of everyday products. From its use in plugs and switches to lamp bodies, helmets for biking and motorcycling, and even some automobile interiors, the material serves consumers well. But long before it was ever used for consumer products or spectacle lenses, polycarbonate played an important role in space exploration. The material was used in astronaut face shields and windows in space shuttles.

The first real use of polycarbonate as an ophthalmic lens material was when 3M used plano polycarbonate lenses in safety goggles for industrial plants. The excellent performance of the lenses for eye protection in these situations led to a call for the use of the material for prescription safety eyewear...and soon for prescription eyewear.

Initial Challenges

Today, according to the Polycarbonate Lens Council (PLC), the material accounts for about 20 percent of total lens sales in the United States. While it is currently seeing stellar growth--and future growth is expected for the category because of technological advances and its availability in more lens designs--polycarbonate had its challenges when it first entered the optical industry. 

Labs had a difficult time adjusting to the material because of its soft nature. Trad-itional diamond wheels could not edge the soft polycarbonate material. But soon it was found that special edgers, featuring custom router blades designed to shape and bevel polycarbonate, worked. Next, specialized edgers were made for edging the material. Additionally, the labs also found that once the back of the lens had been surfaced and polished, a protective scratch coating had to be applied.

Another challenge facing the acceptance of the material was that while polycarbonate was, according to the PLC, the first plastic lens with high index properties, not much mention was made of this benefit to the dispenser or consumer. Because of this, and the fact that dispensers felt plastic lenses had adequate resistance to breakage, the amount of labs putting out the material never topped five percent in its early years, says the PLC.

As the industry and the consumer grew more and more interested in thinner and lighter lenses, polycarbonate sales started to pick up. And today, it is one of the fastest-growing alternative lens materials.

Today's Benefits

GIts fast growth can be attributed to the fact that not only is the material thin, light, and high-index, but it also has built-in scratch resistance and UV protection, and is so safe and tough that dispensers feel comfortable recommending it for children.

According to the PLC, the rule of thumb is to dispense only polycarbonate lenses until the wearer reaches the age of 18. And the legal implications of the Duty to Warn responsibility have also pressed the sales of the material. Through the legal principle of "informed choice," dispensers must provide their patients with enough information to make an informed choice of lens materials.

Added benefits surrounding the material also include a greater availability. In fact, more lens designs are produced in polycarbonate than any other high-index lens material. Some of the more progressive designs (and those which are sought after by consumers) include polarized sunlenses and photochromics. 

Additionally, polycarbonate has a price advantage because while it has a relatively high index, it costs significantly less than most high-index materials. This means a lower cost for patients and better margins for dispensers. 

Because materials that have a higher index than glass (including polycarbonate) transmit less light than other lens materials, this can show up as a reflection from the surface of the lens. Thus, polycarbonate is a prime candidate for AR coating.

Chain retailers have also embraced the category and promoted it through widespread advertising, which has helped sales. And with the improved lab equipment, the sky is the limit for this lens material. EB