You do not have to have 20/20 corrected.
It depends on what your AME thinks.
I have an unrestricted FAA Class 1 but my right eye is uncorrectable to 20.
I requested a SODA (statement of demonstrated ability) however, when my medical was issued, I was told that I did not require one.
All I need now is for a JAA state to give me a class 1 for Europe when I have about 500 hours ME - thereby showing that I can fly safely.