In Oedipus Rex, the main characters speak largely in extended prose monologues while the Chorus chant their lines in a Strophe (turn) and Antistrophe (turn back) structure.
Overall, dramatic irony is dominant dramatic device used by Sophocles. We, the audience, know that Oedipus killed his father and murdered his mother, but Oedipus and Jocasta remain oblivious, despite foreshadowing in their own dialogue, Tieresias' warnings, and testimony by first-hand witnesses.
Imagery related to sight and blindness, metaphors for knowledge and ignorance are also used frequently. "Sight" is used 14 times; "See" is used 19 times; "Eye" is used 16 times; "Blind" is used 16 times. For example, Oedipus tells Tieresias:
Thou knowest, though thy blinded eyes see naught,
What plague infects our city; and we turn
To thee, O seer, our one defense and shield.
Fate imagery is also prevalent. Imagery related to "oracles," "Delphi," "curses," "destiny," and the "stars" show the cruel suffering Oedipus' choices have caused.
Apostrophe (a speech made directly to a person or thing not present) is also used often for dramatic effect. In Oedipus' last monologue, he lists several:
O Polybus, O Corinth, O my home...
Why didst thou harbor me, Cithaeron, why
Didst thou not take and slay me?
Lastly, rhetorical questions are found in abundance, all related to man's questioning of himself, fate, and the gods:
How had I dared to look you in the face?
What, born as mine were born?
Say, friends, can any look or voice
Or touch of love henceforth my heart rejoice?