I've only been wearing them for 4 years, and just for reading/computer etc., but I reckon I need a new pair already.
There I was, just about to screwcut a 3/8th BSF thread, checked the thread depth on the Zeus charts, then indexed it in over a couple of passes to 0.052" deep.
Of course when I tried the nut on, the fit was like the proverbial in a top hat. Looking back in the good book again I saw the depth should have been 0.032" and I read it as 0.052".....
Time for an eye test methinks.