Thanks for the complement. I found a website that touches on the ideas, but without detail:
http://-kickin.com/apps/opticalbasic...ens_basics.php
I went through the math from finding PD using my camera. Computing the focal length from the prescription. Learning about frame dimensions and type of lenses and the index of refraction from the materials.
I got 3 pairs of glasses. Two were standard bifocals, one glass, one Trivex.
Trivex is veru close to glass. You'll see the best using glass lenses, but they will be heavy. Trivex is next providing your prescription will allow them. Then I got my weird pair of bifocals in glass.