According to Ovid, Tiresias was changed from a man to a woman for disrupting two mating snakes (Ovid 108-109). When the film introduces Tiresia she appears as a transsexual. This is an obvious allusion to the transformation and we can account for Tiresias being a transsexual, instead of a woman, since it is being told in a modern setting and someone who changes sex is at some point a transsexual.
Inventively playing with the myth, about halfway through the film Bonello shows us a dead beaver that was presumably killed by Terranova, who immediately after killing the beaver blinds Tiresia.
Bonello's film is not to be missed.
Harris, Stephen, and Gloria Platzner. "The Tragic House of Laius: Tiresias." Classical Mythology: Images and Insights. 5th ed. New York: McGraw-Hill Higher Education, 2008. 650-51. Print.
Ovid. Metamorphoses (Penguin Classics). New York: Penguin Classics, 2004. Print.
Sophocles. Oedipus Rex. Classical Mythology: Images and Insights. 5th ed. New York: McGraw-Hill Higher Education, 2008. 666-714. Print.