Have you ever wondered if it is possible for "blind" people to see anything? It has to do with the phenomenon of Blindsight, the instance in which blind people that have damaged a specific area of their cortex still have the ability of guessing correctly about their visual surroundings.
The man in the above picture has the psychological condition of Blindsight. The man started at the end of the hallway and proceeded to walk down the hallway, all the while maneuvering around placed obstacles on the ground. Also, a psychologist asked some "cortically blind" subjects to identify stimuli as either vertical stripes or horizontal stripes. These same subjects were able to answer with "better-than-chance" levels correctly, even after reporting they saw nothing at all.
But How? How are they able to do this? It is because these people have suffered damage to their primary visual cortex, stopping the route to visual association. "Coarser visual information still reaches the visual association cortex through an alternative pathway that bypasses V1. This visual information probably accounts for blindsight"(Moore et al., 1995; Stoerig & Cowey, 1997; Weiskrantz, 1986). It is this info that passes through the alternative pathways that allow for people like the man in the image to do the things they do.