Ask the Labs – Identity Crisis
Eyecare Business – Karlen McLean, ABOC, NCLC
Published November 2006
Q: I have a new patient who got her last eyewear elsewhere. I can’t get the place to verify what lens material she’s wearing. How do I tell the difference between polycarbonate, Trivex, and high-index lenses?
A: You can tell the difference between poly and high-index by dropping the lens a few inches onto a table and listening to the sound. Poly has a sharper and more hollow sound than high-index. High-index has a flatter sound.
It’s difficult to tell if a lens is poly or Trivex. If the patient is getting a smaller frame, you can rub a little acetone onto the edge of the lens. Acetone will damage poly but will not affect Trivex.
If you have a roughing wheel or hand-stone, you can shave a little off the lens edge. Poly will gum up where Trivex will shave off. We don’t recommend either of these methods because they will alter the original lens.
If you aren’t careful, these methods can make the lens unusable. It’s always best to find out the original order and see what was originally dispensed.
– Glenn Hollingsworth, General Manager, Robertson Optical Laboratories, Inc., Atlanta