Unfortunately, head injuries and strokes can cause blindness. On occasion, however, the individual struck with blindness will deny any implications that this may be true. This condition is called Anton-Babinski Syndrome and there are no widely-accepted theories for why it occurs.
Macdonald Critchley wrote of the phenomenon in his article “Modes of Reaction to Central Blindness”
It may be some days before the relatives, or the nursing staff, stumble onto the fact that the patient has actually become sightless. This is not only because the patient ordinarily does not volunteer the information that he has become blind, but he furthermore misleads his entourage by behaving and talking as though he were sighted. Attention is aroused however when the patient is found to collide with pieces of furniture, to fall over objects, and to experience difficulty in finding his way around. He may try to walk through a wall or through a closed door on his way from one room to another. Suspicion is still further alerted when he begins to describe people and objects around him which, as a matter of fact, are not there at all. Thus we have the twin symptoms of anosognosia (or lack of awareness of defect) and confabulation, the latter affecting both speech and behaviour.
It can be seen that, when given evidence toward the true nature of their sight, sufferers confabulate a response that try to explain their mishaps.