No nothing is blurry. Everything seems to look ok. Its the same text/font as I had all the time. Since that this is a Notebook, I couldn't find an option where I can disable the Intel graphics controller.
Yes the problem occurs in every application, but due to the fact that I couldn't disable the Intel card I tried out starcraft 2 for a few hours, because the nvidia card is used at gaming - I hadn't any eye troubles or other issues then. So I really think, that the problem is the Intel HD 4600.