re: #423 steve_davis

navigating stairs blind isn’t a problem. navigating them with bifocals is what kills thousands of people every year.

Many years ago - when I was a teenager - I switched from glasses to contact lenses and I admit that for the first few hours in contacts, I wasn’t too good on stairs, owing to the prismatic distortion that occurs when you’re used to wearing eyeglasses. I have a strong prescription (-9.75 L eye, -8.15 R eye, and with astigmatism).

Even now, though I mostly wear glasses, when I pop in contacts, it slightly changes my depth perception.