i have the same issue? apple genius wanted a price for a new macbook ( mine is a mid 2013 macbook air). I got a new screen, switched it but it gave the same result. The guy at apple said they might need to change the logic board or tiny piece of it! I wonder if there is a tiny piece to change or is it the whole logic board.
I will order a new logic board and change it my self and will keep you posted!
if anyone else had this issue please let us know.
P.S. I can see everything and use the macbook normally when i shine a light source on it real close, like an iPhone flash!