Originally Posted by
Robert Martellaro
DrK,
I believe that finished poly is available in 1mm (probably 1.2mm in low powers), 1.5mm, and 2.0mm CT.
Sometimes it's not possible to use extremely thin centers even on lenses as strong as -3.75 because the superior and inferior edges of the lens would be too thin for grooved rimless, or because of lens flexure with full metal frames. This is especially true with frames with a very narrow B measurement. Using a 1.67 lens in this situation would be a waste of money because it will have to be surfaced to allow more "beef" for grooving or for stability at the thin edges, and with 1.67's higher density the lenses would be heavier than less expensive low density materials (poly, trivex, spectralite). Less for more so to speak.
However, I'll use 1.67 at this power in drill mounts to minimize temporal thickness for the reason you stated...Minus looks thicker in rimless compared to full metal frames.
Regards,
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