I’ve had to let my eyes “learn” how to automatically deal with my un-lined trifocals. I’ve been wearing them for forty five plus years now, and occasionally still stumble when looking down into the water, especially while wading. I just need to be extra mindful of it.
I agree with what @IveofIone said though. We’re all really fortunate to live in a time when our sight can usually be corrected at nominal cost, giving us years of wonderful improved sight. It wasn’t always this way and I for one, am grateful.
Same as using “zincs” on boats ... cool adaptation for vehicles. I wonder if that would solve the galvanic problem on VW Vanagons. I owned several in my early years and it was a common problem on them.
On glasses with the lines. The Bifocal and the trifocals only take a little portion of the lens. As the Progressive ones go all the way across the lens. After you have been wearing these kinds of glasses for over 70 years, you learn how to see out of them.