I had them for years before I had cataract surgery. Flashes of light, swirly fans, and sometimes twitching in my eye. Most of the time they were in my left eye only, but sometimes in both at the same time. They usually went away if I stopped looking at the RADAR scope, or computer for about 10 minuets (rest my eyes).
They were gone almost immediately after the cataract surgery. I have been free of them since 2016. Well almost....
I just had YAG laser surgery on my left eye. Only recently my right eye has started to twitch, and I see flashes from time to time. I am afraid they are coming back. If I close my right eye and rest it for a few minuets they go away.