Blindness isn’t always related to malfunction in a person’s eyes. There is a condition known as “cortical blindness,” in which the optical nerves and eyes are physically intact, but the visual processing areas on both sides of the brain are damaged. There is a game you can try, the results of which might indicate the presence of blindsightedness.

There is also a condition known as Anton-Babinski syndrome, in which a person is not able to process visual images in the brain, but the psychological parts of the brain act as though the body can see. This results in the person denying the fact of blindess and acting as though they can see, and when they bump into something, explaining it by saying things like, “My glasses are dirty,” or “That wasn’t there before.”