I have tri-focals. My first pair. I'm short sighted and can read perfectly well. But now that I'm in my late 40s, my eyes can no longer accommodate sufficiently to my distance prescription to allow me to focus at short distances. That makes reading difficult now, unfortunately.
I've always liked glasses with good height (I don't like having a frame or lens edge in my field of view) so decided to try bi- or tri-focals. I wanted to be able to see documents & charts in my lap & the instrument panel (duh...), distance vision for outside, and the overhead panel. Bi-focals would be fine except for o'head panels hence tri-focals. Vari-focals don't seem to be available as a replacement for tri-focals so tri-focals it had to be.
I've had them for about a year now and am fairly used to them. We mucked around a bit deciding just where the cut-offs should be and what focal length I wanted. I was told that there were certain limits on where the top lens would be depending on where the bottom one was. If I could do it over, I'd insist (or find a different supplier) that the top lens be higher ie about 1/2 its current height. The bottom isn't too bad though. Maybe tweak it to be a bit lower but not much. The end result would be to increase the height of of the distance prescription lens. I find that I have to crane my neck too often to get the upper lense out of the way when trying to look up eg at traffic lights.