About two years ago, I put up this post about cycling glasses. Those Serfas Gladiators are the glasses I've been using.
I broke a prescription insert a few weeks ago. I'd bought an extra, but when I went back to the manufacturer's site, I see that Serfas no longer sells glasses; they're only selling off the parts for glasses they used to sell. Correspondence with the company indicates the decision to stop selling glasses was based on the fact that there are too many cheaper alternatives.
One of those alternatives is safety glasses. SafetyGlassesUSA has the UVEX Genesis models (there are at least three). The prescription insert apparently fits any of them. Since they are so cheap, I bought a pair, and the insert, to see how they work. The prescription insert fits; changing the colored wraparound lens is a pain with the insert in place, but it's doable.
You can still get your prescription lenses from LensesRx, who will put lenses into the insert for a reasonable cost (go with the progressives).
I know it's a business decision by Serfas, but I'm still disappointed that they've stopped selling the glasses I liked. I won't link to 'em, and I probably won't get that Variable II saddle I was considering.