I spotted this article about blindsightedness at Seed:

TN’s rare condition is known as blindsight. Because his stroke damaged only his visual cortex, his eyes remain functional and as a result can still gather information from his environment. He simply lacks the visual cortex to process and interpret it. Sight has changed for TN from a conscious to a largely subconscious experience. He no longer has a definitive picture of his surroundings, but he has retained an innate awareness of his position in the world. He is, to some degree, able to see without being aware that he is seeing.