i had double vision due to lack of proper treatment for a couple of months, once my prednisone level hit 30... it went away for me.  I have read from people who have high prednisone levels who still have double vision thought.  Also that pry drug made the double vision go away earlier, but i had an allergic reaction to that so i had to stop taking it.  Took me a couple months to get the prednisone to a level where it fixed it, plus i get IVIG treatments now as well, probably both prednisone and the ivig both help to stop the double vision.