Oedipus stabs his eyes and blinds himself because, as Teiresias has said, he has been the one who is blind. In his arrogance, his tragic ignorance, Oedipus refused to believe that he could be the cause of the plague besetting the city of Thebes. He arrogantly believed that he escaped fate by having left Corinth where his supposed parents live. However, in a strange twist of fate, he encountered his real father who had insulted him. In anger, Oedipus knocked this man out of his carriage and killed him.
Oedipus blinds himself in order to humble himself; he will be led by another for the rest of his life. Understanding that his arrogance has been his tragic mistake, Oedipus now forces himself to learn humility. He will remember the words of Kreon:
Think no longer/That you are in command here, but rather think/How, when you were, you served your own destruction.