Shane,

A round lens will be about 5.2mm for the 1.60 index and about 4.6mm for 1.70,
assuming a 1.5mm center thickness. Your frame is rectangular, increasing the
thickness .5mm to 1.00mm, more if there are very sharp corners, or has a shape
that requires an unusually long diagonal length.

Hope this helps,

Robert Martellaro
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Optician/Owner
Roberts Optical
Wauwatosa Wi.
~~~~~~~~~~~~~~~~~~
"Science is a way of trying not to fool yourself."
- Richard Feynman