Howdy.
I have a theory, and I will describe it here.
But, fist of all, u may noticied my not so good english. So, please, make an effort to understand me ;_;
My theory is that, Madotsuki had a long term disease, at first make her go to hospitals and stuff, but nothing seemed to work. Then, the disease became worst and worst, till the ultimate state. The Blindness.
That's why she always keep her eyes closed, cuz she cannot see anymore. Also, that's becuz she refuses to leave her room, becuz she's affraid, and too depressed.
The only things she can remember are the things she saw while the disease hadn't take her vision. Such things like Seccom Masada-Sensei, Poniko, Mono-sister. each of then in different circustances.
Well, the only way she can see the world again, ir dreaming, becuz when she's as sleep yhr blackness disapear.
She have a TV with a game, but now it's useless.
She could only walk to her desk and write down her dreams.
But, one day, somehow she wake up and can barely see again, she didn't realize she was at real world, so she tried to explore a news path, and what we see at the balcony is what she thinks to be a ladder, but not necessarly a ladder, cuz her vision was just starting to recover.
Yeah, poor english I know, not so much clever theory too, but I just wanted to know if someone else thinked this way.