Jamieson, Fausset and Brown on Mark 8:24

24. And he looked up, and said, I see men as trees, walking--This is one of the cases in which one edition of what is called the received text differs from another. That which is decidedly the best supported, and has also internal evidence on its side is this: "I see men; for I see [them] as trees walking"--that is, he could distinguish them from trees only by their motion; a minute mark of truth in the narrative, as Alford observes, describing how human objects had appeared to him during that gradual failing of sight which had ended in blindness.