I make a lot of Chemistrie custom magnetic sunglasses. The claim of the technology is that it fits any eyewear, but I don't think they were envisioning this when they said that. Still, I made it work
A recent customer of mine had an extremely high power Rx, so strong that
to mitigate the thickness on the lens some of the power had to be split
onto the front surface, which made the lens bi-concave (concave on both
front and back surfaces, instead of the usual concave back and convex
front of most lenses). That's all fine and good, I've dealt with such
powers and lenses before. But this customer also wanted the magnetic
sunglasses, and the technology certainly wasn't designed with this lens
in mind.
The basic Chemistrie lens is a simple polarized film laminated between their "Hivex" optical material; the front and back sides are identical, differentiated only by curvature. Since the lens is reversible, I just thought why not turn the lens around to have the convex surface match the concave lens front? The sunglasses will be the same concave front curve as the Rx lenses.
Extremely high power eyewear like this is never elegant, but I think they turned out pretty neat. It's cool unique solution that this customer could only get from a few opticians, and I'm glad I was able to do it.