The play is full of references to seeing and vision, and it is perhaps ironic that Oedipus is famed as a man who is perceptive and able to see things clearly. Eventually, he blinds himself after he faces the incontrovertible truth of who he is, who his wife is and who his children are. Sophocles seems to be suggesting that no matter how intelligent someone may feel that they are, all humans are prone to blindness or to errors that can have serious consequences without them being aware of them. By making himself blind, Oedipus is only making his blindness physical in addition to the psychological and mental blindness that he suffers from throughout the play. Note how Oedipus himself explains his blindness:
What I did was best--don't lecture me,
no more advice. I, with my eyes,
how could I look my father in the eyes
when I go down to death? Or mother, so abused...
Oedipus therefore says that he is not able to physically look at the people he has "so abused" through his ignorance. He blinds himself ironically after he is made to finally see, and through seeing he decides that it is better to be blind.