I use full frame tri-focals. The bottom lense is for reading, middle for panel and overhead panel and top for outside. They work very well at night and solved the problem of the dim lighting on the O/H panel. You never have to take them off - when flying of course, not when emulating Michael Caine in Ipcress mode.
They are expensive and, of course, you need two pairs to fly commercial? Well, I have to admit that my spare pair is not quite of the same standard as the master spectacle.
Puss in B**** sorted them out for me.
Varifocals just bounce your head around which on a long duty day leads to a headache, to say the least.
I don't like the concept of contact lenses in cockpits and besides that professional opinion, they jump out when the trolley girl smacks you.
