I just have Rayban curved polarized w/ my prescription lenses in them... bifocals too.
My Ranbans are two prescriptions out of date (7.5 years old now) and at that time, I didn't really need bifocals. I seem to remember them also saying they couldn't put bifocals in them back then. I can't remember for sure (since it didn't matter to me at that time). I DO remember they were incredibly expensive... I had never spent that much on glasses before ($450?? or something insane). But I have to admit, they were actually worth it. Best glasses/frames ever.
Thanks for the info. I am due now for my next eye exam, and I think it is time to consider a new pair of those, and with bifocals!
Back to the bike.... I have moderate astigmatism in both eyes, but my distance vision is still good enough that I can, THANKFULLY, get away with not wearing them on the bike. The bike dashboard is just far enough and big enough that I can also read it. But I admit am having a lot of trouble with the Zumo 450 now, which is much closer to me and much smaller text/info
It already takes me so long to get ready to ride now, I deplore the idea of having to fool with glasses too.
BTW- there is another option too, Optix also makes a larger version of their stick-ons that might work on the helmet visor:
http://optx2020.com/p-23-hydrotac-diveoptx-stick-on-lenses-for-divers-large.aspx A little pricey as an experiment, but maybe worth considering. And one can probably get by with just one lens, so the other can be saved for when the first gets lost or damaged.