Polycarbonate Lenses: Affordable and Practically Indestructible
According to the Optical Manufacturers Association, an estimated 60% of Americans wear prescription lenses. However, at the same time, according to 2002 statistics, there were an estimated 262,000 product-related eye injuries treated in U.S. hospital emergency rooms alone. These alarming figures significantly highlight the importance and the need of protection, safety and durability in all eye wears. Today, several types of materials are currently used to make lenses. The most common are treated glass, alloy resin plastic and polycarbonate.
While considered highly recommended for the children, polycarbonate lenses are not only for children and are equally beneficial for the use in adults and elderly.
What is polycarbonate?
Polycarbonate is a special kind of plastic that can be molded into very complex shapes. This increased design freedom makes more lenses designs possible. It is also the lightest lens material made and yet offers four to five times the impact resistance of glass or plastic.
History of polycarbonate lenses
First introduced in plano safety goggles in industry, polycarbonate lenses are one the most impact resistant lenses now available in the market. They were first developed in the 1970's for use in space related programs like visors on space suites and shuttle wind shields. In 1983, polycarbonate lenses were formally introduced to the marketplace by Gentex Corporation to address a demand for tougher and lighter lenses.
Today, because of their safety and resistance, they outperform other plastic and glass heat-treated or chemically treated lenses. They are particularly ideal for sports glasses, safety glasses, and children's glasses.
How are polycarbonate lenses made?
Polycarbonate lenses are made by an injection molding process. Tiny, BB-sized thermoplastic pellets are heated to above 500 degrees Fahrenheit and melted into a liquid, then cooled and molded into lenses.
What are the average costs of polycarbonate lenses?
While the polycarbonate lenses costs vary from place to place, depending on the prescription and power of the glasses, the average price is about $70 to $80 for a pair of glasses that includes features like non glare, UV protection and scratch resistance.
Advantages of polycarbonate lenses
Greater protection: Polycarbonate lenses in your glasses protect your vision by holding up to rough play or sports practice. With high impact resistance, polycarbonate lenses provide greater protection against eye damage and vision loss from broken or shattered lenses.
Lighter weight: Polycarbonate material is lighter than standard plastic or glass, which is highly suitable for people with strong prescriptions. As well as being lighter, polycarbonate lenses are thinner than standard plastic or glass, which contributes to the lighter weight.
Scratch-resistant: Although no lens is scratch proof, polycarbonate lenses come with a scratch-resistant coating to keep them clear as long as possible, even when worn by children. Experts believe that a polycarbonate lens is significantly more shatter-resistant than glass or regular plastic lenses.
UV protection: Polycarbonate lenses also offer inherent ultraviolet protection. About 99 percent of potentially damaging UV rays are filtered out by these lenses, whether the rays come from sunlight, fluorescent lights or a computer screen.
Safety: Currently, the lenses and frames made from polycarbonate materials provide the highest level of impact protection. When glass or plastic lenses break, they do not break into harmless granules, but can break into sharp shards that can enter your eye and destroy your vision. That is why polycarbonate is far and away the safest of all the lenses made.
Polycarbonate lenses for children
We all know the kid: The one who could be in a void and still find something to throw or some way to rip and stain clothing. It never fails; there’s one in every crowd. If that child is yours, then you probably know that that bones and glasses usually break when it most inconvenient for them to be broken. While there is really nothing you can do, short of wrapping your children in bubble wrap, to keep them from scraping their knees, you can help keep your child’s eyes and his glasses safer by choosing polycarbonate.
Think about it - when plastic or glass lenses are hit by whatever projectile is hurled at them, they shatter, which can cause serious injuries to your child’s face and eyes. Polycarbonate lenses are far more shatter-resistant than other materials, absorb some of the impact and, in many cases, won’t break, saving both the glasses and your little ruffian’s face and eyesight. As a bonus, your child won’t have to walk around squinting while waiting for new glasses.
But make sure you don't skimp on the frames. You know what your child is capable of and what the potential for mayhem might be. If your child is in involved in any kind of organized sport (or disorganized mischief) on a regular basis, you should upgrade to a sports-rated frame to hold the polycarbonate lenses.
Regular frames are meant for regular wear; they are not designed to take an impact of any kind. Simply dropping a pair of regular frames just right can cause tiny breaks or spell all out disaster, if they’re dropped on a hard surface. What good are impact resistant lenses if the frames are shot? If your child is likely to be hit in the face with any kind of fast moving object, you’ll need not only the shatter-resistant polycarbonate lenses but the sports frames that can take it as well.
Are there any cons?
One of the very few weaknesses or drawbacks of polycarbonate lenses is that they are not as good optically as high index or plastic lenses. Hence, the light does not diffuse through them quickly so the optics are a little bit poorer. While most people will say they did not notice that difference, you may notice it if you go from a high index plastic to a polycarbonate lens.
Likewise, people in prescriptions with higher powers sometimes have trouble seeing out the edges of the lenses -- your clear field of vision is not as wide as with glass or plastic lenses.
Similarly, you should also remember that polycarbonate lenses bend light differently. As your vision is corrected by light passing through a prescription lens and focusing an image on your retina, polycarbonate bends light to a greater degree than glass or plastic lenses of equal thickness.
Therefore, if you previously wore a glass or plastic lens, there may be an adjustment period needed to adapt to polycarbonate lenses.
You should also remember that certain lens coatings may reduce the impact effectiveness of polycarbonate and some lens tints may be difficult or impossible to apply. In these and other such situations, alternative lens materials should be used. Additionally scratch-resistant coating is essential if you have opted for polycarbonate lenses. While polycarbonate lenses will not shatter, they are more prone to scratching than other materials if not protected with scratch-resistant coating.
Finally, as polycarbonate lenses are harder to make, they require more time to manufacture, and can be more expensive.
All in all, while widely regarded as the safest lens for children, adults can also consider polycarbonate lenses and will also be just as happy as the children. Polycarbonate lenses offer 10 times the impact resistance of most plastic lenses, with the added advantages of being thinner, lighter and featuring UV and scratch resistant qualities. Based on these features and benefits, polycarbonate lenses should meet or exceed the requirements of ANSI (American National Standards Institute) for both prescription and Non-prescription lenses, sunglasses and Fashion Eyewear.
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