In this sense, Blanche is blind to the world of reality as she is still trying to live her fantasy. The doctor can see this and acts as a gentleman to her to help lead her through the chaos of both her fantasy and the real world interfering with each other.
"As a matter of fact there wasn't no wire at all!" Stanley can see through Blanche and tell that she is lying again to make it sound like everything will be fine when she leaves.
"I've been on to you from the start! Not once did you pull any wool over this boy's eyes! You come in here and sprinkle the place with powder and spray perfume and cover the light bulb with a paper lantern, and lo and behold the place has turned into Egypt and you are the Queen of the Nile! Sitting on your throne nd
Blanche is more of a round character because at first she seemed fine but them the lies and fantasies were revealed completely changing one's prospective on her.