I drove to my "primary physician" one afternoon in mid-February, 2016. On the way, my vision got rapidly wierd. Instead of one Dunkin' Donuts on my left, there were two. Instead of one truck in the lane ahead of me, there were two.
My primary doc is not an eye guy and recommended that I see an eye guy. Conveniently I had an appointment scheduled with my opthalmologist for the very next morning.
I went home and indulged in some 21-st century medical education (i.e. Googling). I also designed some self-testing procedures. I determined that I was suffering from binocular duopoly (double vision when I used both eyes).
Comments on the website of a medical school advised me that the problem could be caused by one eye, both eyes or my brain, and cautioned that an opthalmologist might not be able to provide a proper diagnosis.
So... the next morning I canceled my optho appointment and got a ride to the wonderful Yale-New Haven Hoispital. I stayed for two days, had lots of tests and was examined by lots of docs.
The food at Yale is superb. They call it "room service and you can get pretty much whatever you want in any quantity at any time, delivered quickly at optimum eating temperature. I used the opportunity to experiment and discovered the joys of the "patty melt," a previously unknown joy.
The diagnosis was that there was damage to one of the nerves that controls movement of one of my eyes, caused by a "diabetic palsy." Years ago I had Bell's Palsy, so all I need to add is Cerebral Palsy and I'll have the complete set.
There was no treatment for my condition but special "prism" eyeglass lenses might help to converge the two images so I could see better.
I saw multiple fancy docs including an optho-neurologist (or maybe a neuro-opthalmologist). None were encouraging. It seemed like I had a life sentence. I started buying eye patches in three-packs, got two pirate shirts and a stuffed parrot, and said "aaarrrggghhh" a lot.
My local opthalmologist, however, was optimistic (an optimistic opthalmologist—imagine that!). He said the problem would probably clear up with no treatment. He was right. After four months, my vision was normal again.