I have a strong Rx -15 with astigmatism. I had 1.6 index glasses. I had a
problem with the anti reflection coating and got the lenses replaced a year
later but something was wrong. These lenses had nearly no fringing and lower
distortion in the corner. I figured they came out with some new high Abbe
material. it was awesome!

A year after that, I went in to have my eyes checked because the inside
coating was scratched. I figured I'd get my Rx updated with the new lenses.
I tried this 1.66 index material. When I got my glasses, it was like tunnel
vision. Rx seemed perfect in the center, but only a few degrees off axis,
every thing blurred into a rainbow of color. Monochromatic light sources
like LEDs were still sharp of axis, so the lenses seemed aligned. It was the
intense color fringing of this high index material.

I told them this is horrid. I can't wear these! They worked with the lab and
after a few days determined that the lenses that replaced the scratched ones
before were CR-39. Another week later I got my glasses. Beautiful vision!
with some creative non invasive grinding, the lenses are not much thicker
than the 1.66 index material. $150 less too. I'll never sacrifice my vision
just to have thinner looking lenses again.

-S