Had these for a couple for years now. Just took them to my optometrist when I got them and they got them ground to my script for me. Found using an insert was A LOT cheaper than getting proper prescription sports safety glasses.
Took a little getting used to at first, but that may have been how I was wearing my Bolle Combats. The prescription compatible nosepiece had bad nose padsarms that were to weak and flexible to hold the lenses in a suitable position and I had difficulties with depth perception. Those eventually broke off and I replaced them with a piece of neoprene which work much better. Have noticed that they move around a little more in the nose piece, due to the metal clip wearing away at the plastic. The outer sides of the RX lenses contact the Combat lenses which helps to stop them from just rattling out and off, but might leave a little mark on the Combat lenses after a while. Sweat had caused a little bit of discolouring on the metal frame, but so far its only affect is aesthetic.