Are there any opticians here?

My wife has very sensitive eyes, and has a hard time getting sunglasses that are dark enough. Opticians always claim that "that's as dark as we can get them", the process clearly being dyeing.

Wouldn't it be possible to grind two polarized lenses and glue them together at a particular angle? It seems to me that you could pretty easily select 50% to nearly 100% with that method. I recognize that it would obviously be harder to accomplish than with dyeing, but it would solve her problem.

Anyone have any feedback?