Ah, that's one of the problems I am having. My brother is
visually impaired. He lost his eyesight in an accident. One day, he
was on his way to somewhere after it had rained and he slipped and
fell on algae/moss. When he came home his entire backside was wet
and dirty with some mud. There have been a few more incidents
relating to water puddles. I felt pitiful and responible for
him. Since then I accompany
him whenever he goes out. So many engineers in this world and they
come up with all this iPhone, iPad, massage chair. But none of them
spared a thought for people like my brother. Oh, so to answer your
question, they walk through it unless there is someone guiding them
away from it. By the way, he uses a white cane which is the stick
that the visually handicapped use to feel around to get from place
to place.