motion sickness
"My friend and I both used the patch to prevent motion sickness on our first cruise.  By day 3 of the cruise, I had double vision, and could not even read the menu at dinner.  I also began to get a horrible migraine, complete with flashes of light in my vision.  I assumed the patch was wearing off, so I removed the old one and put on a new one.  By the morning of day 4, we removed the patch after reading possible side effects on the box.  My vision did not return to normal until day 6.  I spoke with the doctors in the infirmary, and they said they often see this as a side effect to the medication.  My friend experienced the same double vision, although hers began a day behind mine.  "