Eyeglass Lenses Coatings and Frames

October 16, 2014 by Debra Lynn Dadd

Question from Cindy

Hi Debra,

My husband and I both need to get glasses and are having a hard time finding the frames and lenses we believe would be non or least toxic. Please help!

Lenses

Regarding eyeglass lenses, in a 2008 post you said, “The thing to remember about polycarbonate is that the concern is not outgassing, but leaching into food and water from contact. Since our skin does not contact the eyeglass lens, I don’t believe there is a problem with toxicity during use.”

Wikipedia states that “CR-39 should not be confused with polycarbonate, a tough homopolymer usually made from bisphenol A.[3]” BPA? Wouldn’t wearing BPA be a concern even if there’s no skin contact?

Do you still believe that all of the following lens materials are relatively nontoxic: high Index plastic, Tribrid, Trivex and CR-39 plastic?

And or true of all eyeglass lenses since they’re not touching the skin? Do any outgass or pose other toxicity hazards?

I’ve listed below what I could find on the above materials in case you’re unfamiliar with them.

Tribrid. All about vision’s site says, “Tribrid lenses were created by merging elements of PPG's lightweight, impact-resistant Trivex lens material with those of established high-index plastic lenses.”

Trivex. I’ve read that “Trivex lenses are composed of a newer plastic that has the same characteristics as polycarbonate lenses.” all about vision’s site says, “Trivex lenses, however, are composed of a urethane-based monomer and are made from a cast molding process similar to how regular plastic lenses are made…”

CR-39 Wikipedia says, “The abbreviation stands for "Columbia Resin #39… CR-39 is made by polymerization of diethyleneglycol bis allylcarbonate (ADC) in presence of diisopropyl peroxydicarbonate (IPP) initiator. The presence of the allyl groups allows the polymer to form cross-links; thus, it is a thermoset resin…

The polymerization schedule of ADC monomers using IPP is generally 20 hours long with a maximum temperature of 95°C. The elevated temperatures can be supplied using a water bath or a forced air oven.
Benzoyl peroxide (BPO) is an alternative organic peroxide that may be used to polymerize ADC. Pure benzoyl peroxide is crystalline and less volatile than diisopropyl peroxydicarbonate. Using BPO results in a polymer that has a higher yellowness index, and the peroxide takes longer to dissolve into ADC at room temperature than IPP.”

Coatings

Regarding RX eyeglass coatings UV protection, anti-glare and anti-scratch are widely recommended and seem sensible. Do you know if they are generally safe or which are more or less toxic?

Frames

Debra, after reading your 2008 post about eyeglass frames and looking further into them, I agree that zyl (zylonite, or cellulose acetate) or frames made from propionate, a nylon-based plastic seem like good choices.

But in terms of finding the styles we like and hopefully frames covered by our insurance plan, we’d like some additional options. What do you think of aluminum, titanium, nickel or stainless steel frames? Many are blends of these-- any thoughts on blends?

Also, you said you wear metal frames, do you think they’re a less toxic choice than plastic? Any long term health concerns with EMFs from metal frames? We would be wearing our RX glasses most of the day.

Thank you. Anything you can do to allay our anxiety on picking out the least toxic glasses would be greatly appreciated!

Debra's Answer

Lenses

OK. To start, I haven't been able to find anything which states that BPA is a hazard from outgassing, only ingestion. Recommendations are to not eat canned food or beverages, or drinking water from polycarbonate bottles. Also don't allow your dentists to apply dental sealants made from BPA (BADGE). But there are no warnings about not wearing polycarbonate glasses.

Polycarbonate is a very hard plastic, and these don't outgas the way soft plastics do. So I have no reason to believe that you would have any exposure to BPA from wearing the glasses. That said, you would probably get some exposure to BPA from touching the glasses, so when cleaning them, touch them only with the cleaning cloth and not your bare fingers.

All of the plastics you mention are hard plastics, so they would not outgas much, if at all. I couldn't get any more information that you got on the exact materials, but I would say they probably don't contain BPA as polycarbonate does, so any one of them would be better in that regard.

Coatings

Like lenses, it's difficult to find information on the materials used to make coatings.

I was abole to find that Teflon is use to make coatings that are scratch-resistant, anti-static, and reduced-glare.

Anti-reflective coatings may contain magnesium fluoride or fluoropolymers.

But whether or not the presence of these chemicals would result in an actual exposure, I don't know. Teflon needs to be heated to cooking temperature to release it's toxic gas. Fluoride is a particle that is likely bound up in the coating and would not offgas.

Regardless, these exposures would be extremely small, if any.

Frames

Metal vs plastic frames?

In 2008, when I wrote my last post on this subject, I preferred metal frames over plastic. But after researching the plastic used to make frames, and finding that it is usually plant based, I've been wearing plastic frames. As stated before, metal frames were giving my skin a rash at the points where they touched my face.

At the moment I am wearing my favorite glasses of all time, a pair of readers with bamboo temples that I got from Peepers. A number of companies are making them now. There's quite a selection online.

A reader posted a study that looked at a group of individuals that had skin lesions at the point where eyeglasses rest on the nose. The study hypothesized that the lesions were due to constant pressure at the point of contact rather than the materials used in the glasses. More research in needed in this area.