We can only surmise that he is too busy doing the greatest of deeds to notice trivial matters, too busy to look anywhere but straight ahead. There then seems to be some connection between knowing oneself and physical blindness. Yet when one is blind, he must rely upon his other senses, especially touch. Touch is the sense of certitude, it is touch that is the basis of knowing. In fact one is aware of his own existence through touch.
Touch then is the primary sense of self- knowledge.
Teiresias in Antigone says that he sees through another's eyes. This is what Oidipous clearly fails to do in his dealings with Teiresias and Kreon. He sees no need to look through any pair of eyes other than his own. Hence he can reflect upon himself and others insofar as he is not distracted by the dazzling amount of princely duties. That is, he seems to be indifferent to the plight of the city.