CR39

Are most basic plastic lenses made of CR39, or is there another basic
plastic that's significantly thicker? I've just bought some glasses and
I think the lenses are polycarbonate because the chromatic aberration is
quite severe and they're definitely thinner than my old glasses (even
though the new frame is larger you can still see a clear difference at
the edges) which have Transitions from Dollond & Aitchison, made by
Nikon I think. The optician I ordered them from seems to think they're
CR39 though.

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TH * http://www.realh.co.uk
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