What is the cause of Creon's change of heart in Antigone?

The exchange between Creon and Tiresias is compelling
enough for Creon to change over the course of the drama.  Tiresias enters the court and
tells Creon of all that has happened in response to him not honoring the dead son of
Oedipus.  Tiresias enters to help the king, as he has done in the past.  Yet, Creon's
arrogance gets the best of him and he hurls insults to the blind seer, prompting lines
like this to be uttered before he leaves:

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And you—know well that before the sun
has
run a few laps more, you will give one from
your loins, a corpse
for corpses, in exchange
for those you have sent from above the
earth(1075)
to below it, the living soul you have
lodged
dishonorably in a tomb, and the
unhappy, unburied, unholy
corpse
you hold back from the gods below.

The idea of Creon having to
"exchange" a "corpse for corpses" is fairly telling.  The fact that Creon's refusal to
honor one dead will result in multiple is something that dislodges him.  The stunning
rebuke of "you will give one from your loins" points to Haemon, and helps to cause a
change in Creon.  Yet, Tiresias continues:

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....this violence comes from you.
For these things,
however, the destroying avengers
of Hell and the
Furies of
the gods are
lying wait for you, that you may be taken
in these same
evils. Consider also(1085)
if I say these things as a hired
accuser,
for a short time will reveal the wailing
of men and women
in your house.

It is
interesting to note that while Creon has acted in the name of the public, as the king,
Tiresias predicts doom on the personal level.  It is not as king where he strikes, but
rather in the idea of the "wailing of men and women in your house" and that the powers
of the divine have aligned against him, Creon, as a person and not as a king. 
Sophocles' inclusions on this point help to bring out that while the Greek rulers were
seen as kings and political heads of city- states, they broke and feared as human beings
would.  Tiresias' prophecies on this level is what haunts Creon and terrifies
him.

Upon such doomsday predictions, the Chorus, assuming a
fairly active role throughout the drama, but really so here, is alarmed at what Tiresias
has said.  Creon's response demonstrates the first moment of his change and why it has
happened:

I
know, and I, too, am shaking in my
heart,(1105)

This is the
moment when the reader understands that Creon has changed.  The prophecies of doom on a
personal level have caused a shift in Creon's perception of himself and his actions.  He
no longer is willing to identify his own belief system as absolute.  Whether he changes
out of a sense of the sincere and genuine, or if he has changed out of fear in the
predictions of Tiresias, Creon has changed in that he is "shaking in" his "heart."  Here
is where transformation has happened in him, but several moments too
late.