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What are Polycarbonate Glasses?

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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.

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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.

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anon352464
Post 10

I bought some reading glasses for my folks online and was really disappointed when they came with a warning saying that they were made out of materials that could cause cancer or damaged the reproductive system! We wear glasses or sunglasses all the time, even often falling asleep with them on.

I don't want BPA and other toxic elements in the plastic. Why can't manufacturers ever say exactly what is in these materials? Many plastic products produce a toxic dust on the surface, but I don't know if that applies here. but I recall that BPA can be absorbed by skin contact from receipts and CDs. these things should at the very least be disclosed on item descriptions before you buy stuff!

anon341938
Post 9

The blog is really giving people the benefit of using polycarbonate sunglasses. The best part is that its good for the eyes and do not break easily, so it's advisable to use them.

anon250910
Post 8

This is great to know because when ordering glasses online. You can choose options such as UV block added. If you are already getting polycarbonate, that would be a waste of money since they already block out 99 percent. Of course, the seller doesn't bother telling you that.

ahain
Post 7

@Malka - That did clear up my original question -- thanks. Now it's making me curious about some other things, though, like whether polycarbonate glasses lenses are made out of pure polycarbonate. Is that what pure polycarbonate looks like?

Maybe if you heat it at a different temperature before molding it, it will turn out more cloudy. That sounds reasonable. And if glasses lenses aren't made of pure polycarbonate, I kind of wonder what other materials are mixed in with it.

Hawthorne
Post 6

Judging by the information about the FDA and the individual group of scientists researching the safety of polycarbonate being used for food container products, I'd say somebody thinks of polycarbonate as too good a material to make things out of to worry about the safety.

I mean, the individual group of scientists found the BPA levels in food containers to be dangerous, but the FDA won't acknowledge it because of "lack of research" -- if the FDA really cared to prove them wrong, though, they would actually conduct their own study.

Studies these days are usually funded by one side or the other in the debate of whether something is safe; it's typical for them to be funded by the side they end up supporting, and definitely no coincidence.

Anyway, polycarbonate still has a market in being made into glasses lenses and other items that don't involve food, even if they do ultimately prove that it's unhealthy to have in food containers.

Until they make up their minds either way and present some definite research, I'm going to avoid using polycarbonate items that come in contact with my food or drinks.

Malka
Post 5

@ahain - Polycarbonate is a kind of plastic; like any plastic, it can be opaque or transparent depending on a bunch of different factors while molding and heating it.

CD-ROMs are also opaque -- and all shiny with iridescent rainbows in them at different angles -- because of the other materials that are put into them when they are made. CD-ROMs aren't made out of just polycarbonate, see, and I think they are made of much less polycarbonate than glasses lenses are.

Did you know that if you microwave a CD-ROM, a good amount of the surface will burn away in a burst of sparks, leaving holes and transparent spots? This was demonstrated on the Mythbusters tv show. The parts that burn away are actually metal, which burns and sparks in a microwave -- if the CD-ROM was solid plastic, it wouldn't make any sparks.

Keep in mind also that CD-ROM data is "written" on by burning tiny rows of dots onto the surface. This is why CD-ROMs have that circular direction to the lines when you look at the bottoms, and may contribute to the opaque look.

So in short, polycarbonate glasses lenses are probably more transparent than CD-ROMs because the CDs have markings on them and also because the glasses lenses are made out of more pure polycarbonate, while the CD-ROMs are a mixture of materials. Hope that helps clear things up -- no pun intended!

ahain
Post 4

So the same stuff that my glasses are made out of is also what my CD-ROMs are made of? That's kind of cool. I wonder why the CDs aren't transparent like the glasses lenses then?

gimbell
Post 3

I didn't know polycarbonate lenses have 99% UV protection! That's just another reason to love my new glasses. I got them last month, and since I used to wear glasses with actual glass lenses, I decided to look up the new material online to see what I'm dealing with.

It sounds like I need to watch out for scratches on my lenses, though. I didn't know anything about polycarbonate when I got these glasses, so I'm not sure if they have a shielding coating to prevent scratches like the article talks about.

Is there any way to look at your glasses and tell if they have the protective coating? Most likely since I went for the most affordable kind of lens, I probably skipped the coating...

If they don't have the scratch resistance already, is there any way you could go back to the optometrist and pay to get them coated with the scratch safe stuff?

I want my glasses to be as tough as they can be -- I can't afford to buy new lenses very often, and I think the scratch resistance would be worth the extra money in the long run.

RequiredFun
Post 2

@dobie - While you make an excellent point in terms of long term replacement costs, let us not forget that polycarbonate glasses perform far better in safety glasses than traditional lenses. Therefore, if a person works in an environment requiring safety glasses, polycarb is really the only way to go.

dobie
Post 1

My daughter has a rather strong prescription so as a result we always pay the little extra to get polycarbonate eye glasses for her. I can testify that they do seem to scratch easier, but we've never had a lens break. Since she's so young and her prescription tends to change every year, I don't find the scratching to be that big of a con.

However, I can see where if a person kept the same prescription over the course of several years it might be inconvenient to have the polycarbonate plastic glasses. I mean, what good is having unbreakable polycarbonate glasses in the long term if they become so scratched that you can't see through them anymore after a year or so?

So, I would say that for a child, these glasses are ideal. Especially for strong prescriptions like my daughter's because it eliminates the "coke bottle" look. But for adults, I'm not sure. I purchased traditional glass lenses in mine 5 years ago and they still don't have a scratch.

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