2 ms·
Not optically worse. CR39 has lower index of refraction (1.498 vs 1.54) and so it is heavier. It has worse chromatic aberration (Abbe 58 vs Trivex 45). So it's
by CalChris 9y ago
Not optically worse.
CR39 has lower index of refraction (1.498 vs 1.54) and so it is heavier. It has worse chromatic aberration (Abbe 58 vs Trivex 45). So it's really only good for light prescriptions.
Trivex is also easily drillable making rimless easy, rimless->lighter; PC tends to crack easily.
But yes Trivex is a little more expensive than CR39 but in my experience a lot better. If your lenses last 2 years, lenses are not where you should save money.
http://www.mastereyeassociates.com/eyeglass-lens-materials http://www.mastereyeassociates.com/eyeglass-lens-materials
- mrob 9y agoCR39 has better chromatic aberration. Higher Abbe number means less aberration. CR39 has the lowest chromatic aberration of any material commonly used to make glasses.
- CalChris 9y agoYeah, I got that backwards. Point is that CR39 is not exactly better optically. Trivex is significantly better chromatically than PC, 1.60, ... In addition, Trivex acts as a UV cutoff filter. What I couldn't figure out is whether a CR39 lens' comparative thickness (prism length) vs a thinner Trivex lens degrades its chromatic aberration advantage in practice. http://eclecticeyewearaustin.com/wp-content/uploads/2016/05/Lens-thickness.jpg http://eclecticeyewearaustin.com/wp-content/uploads/2016/05/...
- boptom 9y agoGenerally, you would expect lenses with a higher refractive index to be thinner. However, due to the selling point of Trivex being "shatter proof" it has a greater centre thickness (to pass safety lens regulations), and thus the edge thickness is also comparable to CR-39.