Several people have very kindly inquired about Buster, so here's an update.
We took the B-boy for a second opinion, and confirmed that we're on a good course. The two treatable conditions - glaucoma and uveitis (inflammation of the eye tissue) - are under control, and the long list of untreatable conditions are stable for now.
We're going to continue using the various medications indefinitely, as long as they keep working. There's a good chance that at some point, they will stop working, and Buster will lose his eyesight. If that happens, there's a simple laser surgery procedure that can alleviate any pain, but not save his vision.
We also learned about surgical options, which are a big gamble. Apparently surgery works brilliantly in humans, but in dogs, not so much. The same surgery might work permanently, or the condition might return in a matter of months, or even days. Surgery that worked would save money (and effort) in the long run, but there's no indicator of whether or not there would be lasting gains. It's really a crapshoot.
We decided we're staying with the new doctor until we move. The first doc, while very thorough and experienced (she's supposed to be the best veterinary ophthalmologist in the city), is brusque and unpleasant. I never really understood the diagnosis or treatment; she either purposely keeps things mysterious, or she just has zero communication skills. The new doc explained everything clearly and gave us reading material describing the condition and the various options.
Also, the first doc was testing for everything under the sun, no matter how remote the chances. There's a line between thorough and recklessly expensive. When our last visit cost $450 extra in obscure blood tests, I signed off.
The new doc agrees with a re-check every two months, and that seems fair for now.
So we have a dog who can still see, but who will probably be blind one day, and a whole bunch of money that I'd rather be saving for Canada being spent on tiny little bottles of eye drops. On the other hand, the drops are working, Buster is happy as a clam, and I'm very grateful I can afford to keep him that way.