Good question, @windyh. Yes, PD does affect vision, including problems with double vision. Here is an article from the Davis Phinney Foundation website about vision problems with PD,
--Parkinson's and Vision
https://davisphinneyfoundation.org/parkinsons-and-vision/
Here is a quote from the article, "The primary purpose of the front part of our eyes (the cornea, lens, etc.) is to produce the clearest possible image, which is then transmitted to the back part of the eye, called the retina. The retina is made up of nerve cells that communicate via visual pathways using the neurotransmitter dopamine. In addition, we have two eyes with overlapping visual fields, which enables our brain to see the world in three dimensions and process complex visual information. "

How long have you been experiencing double vision, @windyh? Have you mentioned this to your neurologist or your opthamaologist during your annual eye exam?

PD can cause double vision and mine occurred while I have PD. So I thought it would be useful to mention my optometrist's treatment.