What are Polycarbonate Glasses?
Polycarbonate is a moldable, durable, inexpensive form of plastic that is used in a wide variety of consumer products. Frequently used to make eyeglass lenses, compact disks (CDs), house wares, drinking glasses, water and baby bottles as well as numerous industrial products. Polycarbonate is valued for its impact resistance, optical clarity and temperature tolerance. Polycarbonate was developed in the 1950s and was soon recognized as a dynamic substitute for glass. In the 1980s, polycarbonate glasses were introduced to consumers as a safe, affordable alternative to standard plastic or glass eyeglass lenses.
Polycarbonate lenses have significant benefits over other forms of lenses on the market. In addition to their excellent impact resistance, polycarbonate glasses are up to 40% thinner and one-third lighter than standard plastic lenses. These properties make polycarbonate glasses ideal for people with high prescriptions. Polycarbonate glasses, however, are not perfect. As a result of their ability to absorb impact, the lenses are soft and therefore more susceptible to scratches. To compensate for this, scratch-resistant coatings have been developed and can be added to polycarbonate glasses to provide added durability.
All safety eye wear is made from polycarbonate material as it provides the best impact resistance of any eyeglass materials available. Polycarbonate glasses are 10 times more resistant to breakage than plastic lenses. Lenses made of polycarbonate are highly recommended for children due to this safety benefit. Additionally, polycarbonate blocks 99% of UV light. This ability is an important feature, especially for children and individuals who work outdoors, as UV light is known to contribute to the development of cataracts.
Although the safety features of polycarbonate for eyeglasses are undisputed the use of polycarbonate in consumer products has been in question. The polycarbonate used to make items such as baby bottles, polycarbonate drinking glasses and re-usable water bottles contains a chemical called bisphenol-A, or BPA. In 2007, an independent group of scientists reviewed the body of data available on the safety of BPA and determined that polycarbonate products made with BPA presented a safety concern for humans. Bottle manufactures promptly responded by eliminating the manufacture of BPA containing products. Although there are currently no restrictions on the use of polycarbonate in drinking glasses and bottles the use of this material in food containers has declined. As of September 2008 the U.S. Food and Drug Administration has resisted a ban on products made with BPA, maintaining that further data is needed on the safety of the material.