I also got a pair of Optilabs - the HLT ones - came in very handy for seeing the fly in poor light last week. Made a huge difference.
I have a varifocal prescription, which they made up for me, but I didn't have the measurement from pupil to pupil, so I measured it myself, and I don't think I got it quite right. I wouldn't sit and work at the computer screen with them... but they are fine for fishing. Anyway, when buying online, try to ensure you have all the details, including the pupil to pupil measurement.
Col