A strange prodigy likewise happened at this fight. Epizelus, the son of Cuphagoras, an Athenian, was in the thick of the fray, and behaving himself as a brave man should, when suddenly he was stricken with blindness, without blow of sword or dart; and this blindness continued thenceforth during the whole of his after life. The following is the account which he himself, as I have heard, gave of the matter: he said that a gigantic warrior, with a huge beard, which shaded all his shield, stood over against him; but the ghostly semblance passed him by, and slew the man at his side. Such, as I understand, was the tale which Epizelus told.
I did a quick bit of googling and found that yes, this is indeed widely accepted by psychologists as one of the oldest known descriptions of what we would now recognize as an extreme case of post traumatic stress disorder.