Prompted by a link from JV over at Orbx, I purchased a set of VR Lens Lab prescription lens inserts for my Oculus Rift. http://vr-lens-lab.com/product/oculus-rift-lens-inserts/
I've been very happy with them, and it's made using my Oculus much less of a chore, since I no longer have to wedge my glasses awkwardly into the HMD, risking scratches to my glasses, the HMD lenses or both. Plus, yanking off the headset for a quick breather or to go check on something is significantly easier.
However, the one small issue is that the lenses can wriggle loose and or become misaligned occasionally with the Oculus lenses. Not a deal breaker or even very common, but it can make one wonder if there might not be a better solution.
Now VR Lens Lab is back with a possibly better solution capable of not only working with all HMDs but also being worn as sport glasses. I've just ordered a pair, and I expect to be very happy with them. I will also report back when they arrive. In the meantime, consider this a heads up!