I bought a pair or Rudy Project sunnies with the changeable lenses and RX clip-in frame. Went to a bike shop then took the frame to my optometrist to have the script fitted.
Having put them in before Christmas, I finally got them back yesterday because of "technical difficulties". I'm long sighted with a very strong (+6) prescription with some astygmatism (the focal length of my eye's lens varies slightly depending on which you rotate it. This meant that they had to use glass with the highest available refractive index ( 1.8 ) to grind the lens and, apparently, they broke it a couple of times (a bit steep for them at $360 a pair). The 1.7 glass is only $180 a pair but there's not enough room in the frame to fit the thickness of lens required for that script. Luckily they'd quoted on the 1.7 glass knowing the script and so I got the lenses for the quoted price.
There was a label saying that the frames were recommended not to exceed -4 dioptres but, since my script was +6 I thought I'd be OK and the bike shop rang the distributor who referred them to an optometrist who said it would be OK.
So, the moral here, is that you should check whether the frame can take your prescription before you buy. I'd suggest buying through an optometrist specialising in cycling eyewear - they'll tell you what can work. It seems to finally work out to be about the same price anyway.
The other shock I got was when I put them on. I could read the receptionist's desk pad but the poster behind her was very fuzzy. Remember that these are supposed to give me clear vision for riding on the road and anything more than a metre away was blurry! The optometrist checked the script in the lenses and then rechecked me with the reading chart and suggested I try going for a walk wearing them to see if I just needed to adapt to the new lens. When I did this it was awful until I tipped my head back and found the whole world snapped into focus. I haven't tested them on the bike yet but I think you need to consider that the lens frames are set for a cycling head position (body leaning forward, head tipped up) and, at least for my strength of script, that doesn't work very well when you're standing looking straight ahead.
My brother, who started wearing glasses long before I did and had surgery and remedial exercises as a kid and now only occasionally wears glasses
bought some BBS sunnies at Annaconda. I think these wrap over his specs if he wears them riding.
Here endeth the sermon.