Two recurring motifs in Sophocles' Oedipus Rex are references to both sight and blindness. Sophocles uses the motifs to represent Oedipus's own blindness and naivete.
Sophocles especially uses sight to refer to the things that Oedipus should be able to notice, thereby contrasting his ability to see what's going on around him with his inability to see what is going on in his own life. In particular it is pointed out that Oedipus should be able to see the suffering that is taking place in Thebes due to the plague. At the very beginning of the play, the priest points out that Oedipus should be able to see their suffering in his lines, "You see how many of us sit here at your alters" (15-16). Oedipus even confirms that he sees his citizens' suffering in his lines:
My poor children, what you desire is known to me and not unknown, for I see well that everyone is sick. (63-65)
However, the fact that Oedipus is able to see his citizens' suffering is ironic because he is unable to see that his own transgressions are actually the cause of their suffering. We later learn it has been prophesied that Oedipus will kill his own father and sleep with his own mother. Oedipus thinks he has escaped his horrific fate by fleeing Corinth and living in Thebes. Ironically, he does not realize that his real father is not the king of Corinth, but rather King Laius of Thebes, whom he killed on his journey to Thebes many years ago. Therefore, ironically, Oedipus does not realize he has actually fulfilled the prophecy rather than escape it; he is blind to what he has done and it's ramifications. The seer Tiresias points out Oedipus's naivete or ignorance and relates it to blindness, as we see in his lines:
I will reply, since you reproach me as blind: You, even though you see clearly, do not see the scope of your evil, nor where you live, nor with whom you dwell. (432-435)
Hence, we see that Sophocles' recurring motif of sight and blindness serves to illustrate Oedipus's own blindness and lack of understanding.