The point I was trying to make, and which zoobyshoe has done a better job of, was that there is no new sense. The patient is using his vision. Because of brain damage, he cannot process most of what his eyes see, and none of it is conscious, but he's still just using light bouncing off of a...
There's nothing supernatural about this phenomenon. It is (or is related to) "blindsight". The subject, "patient X", has damage to his visual cortex, but not his eyes. In other words, his eyes work fine, but the area of the brain responsible for processing the visual input isn't working...