I did the single lens thing for a while. A place where I worked required safety glasses in the shop - where I went occasionally. The real problem was that you had to go through the shop to get to the potty, so they were essential. I had the safety glasses made to the mid-range of my trifocals. Since they were used only "indoors" I didn't really need the distance lens, and the mid range was about right for the computer.

The only real problem is that safety glasses (in my prescription) are very heavy and I ended up with lumbago of the nose bridge if I wore them too long at a time.

John