I called Kaiser as soon as the meeting ended and they wanted me to see an opthamologist immediately. The opthamologist, in fact, was going to work late so that he could see me tonight. I hurried over to Kaiser Interstate on my bike. The opthamologist explained that probably what was happening was that my vitreous humor was shifting around and putting occasional pressure on the retina, something that is fairly common and nothing to worry about. However, it was also possible it was a migraine and it was also possible that my retina was tearing or detaching. That last possibility--retinal detachment--was the reason they wanted to see me immediately.
The examination wasn't too fun. (Warning: the squeamish should probably skip this paragraph) It started with drops in my eye to dilate my pupils and then shining a bright light into my eye while looking through a complicated instrument. I've had that done before and it was no big deal. Then he looked into the corners of my visual field with an extremely bright light, much brighter than I had ever experienced at an eye doctor before. That left me seeing spots at the edge of my visual field for several minutes. Finally, to look at the very periphery of my retina, he wanted to use a special lens that physically touches your eyeball. He explained that this wasn't completely necessary if I couldn't handle it, but that it would help him make a better diagnosis. I figured I would gladly trade just about any amount of short-term discomfort for the long-term preservation of one of my five senses, so I told him to go ahead. The lens was huge--it seemed like something out of the movie Brazil. And it stung, even though he had put in some anesthetic drops to numb my eye. After it was over, my vision was extremely cloudy because of the gel he used to lubricate the lens.
He told me that I was fine--no retinal tearing and no retinal detachment. However, he said, the flashing lights I'd been seeing clearly meant that something was up, so he wanted to see me again in a few weeks. And he cautioned me to come back in at the slightest indication that the symptoms were getting worse.
Since the examination had left me with extremely blurry vision, he cautioned me to wait around for about 20 minutes before biking home. I passed the time in the lobby of the otherwise-closed building, playing a piano that I never would have expected to be there. Once I was done, one of the janitorial staff had to show me the way out, since the doors were locked, and she complemented my profusely on my playing. It was a nice end to an otherwise lousy evening.
The anesthetic wore off soon after, leaving my eye pretty sore. The dilation lasted a lot longer, so I have been unable to focus on closeup objects until just recently. And the soreness is just now beginning to fade.
So that's why I still haven't pulled out my viola, in spite of symphony rehearsals starting up again in two days.