I have a quivering, very infrequently, in my right eye. I don't get double vision, but, at times, it is very difficult for me to read. For a certain period of time, I don't read very much. And, then, just like that the difficulty disappears and I am reading again. My understanding from my neurologist is that this is PD-related and that my eye muscles don't drag my eye properly along the line of print. I have read about this also; it is in the literature about PD. If I recall properly, it is not uncommon for PWP to have double vision such as yours when he/she has this difficulty reading. If I manage to locate a reference, I will send it to you. Katie