The only place I routinely encounter stairs recently is the hospital, when I go in for an appointment. A while back, coming down the stairs, I decided my feet were too big for the steps. I do have biggish feet, size 11 1/2 in Freedom Units, but I've never had any issues with stairs before this. Suddenly, looking down at my feet, I decided I needed to twist my feet sideways on the steps to get a good purchase and not fall over, face-first, down the steps. I do wear glasses, but nothing is new about that. I have no idea what happened that day, that made me fear going down the steps.
I have since navigated those same steps, both up and down, without problems. I do, however, avoid looking down at my feet.