I remember vividly when I had my first migraine. I was standing for hours at a time, taking tickets at a movie theater. I figured out a way that enabled me to stand for long periods by putting one knee behind the other - I didn't think about blocking blood flow. Maybe the issue was circulatory, maybe bright relections of the sun from the windows of passing cars were the trigger, but the aura, then the pain, began.
It happened a few other times when I was doorman at the theater - again, possibly from standing for so long -- and could have been related to my bileaflet valve, undetected blood pressure issues, circulatory issues (from restricting blood flow in one leg), but, in retrospect, I don't think it was neurological at all. Over the years, the painful migraines gave way to the auras that usually last about 30 minutes.
Sometimes a few bites of a chocolate bar can stop the auras dead in their tracks (but I haven't tried this), sometimes a caffeinated drink will stop them. I don't have either in my house anymore, so I just put up with these.
I'm not sure what triggers them, or what causes them -- althugh bright lights ARE definitely one cause. I try to close my eyes or move into a dark area until these things are done.
No - as far as the vision in an eye turning black for a few seconds - in my case, and the case of a friend who had the same symptom, we both discovered a sensitivity to Zyrtec. This sometimes was accompanied by numbness of the tongue and lips and fingers - scary, but they went away. When we stopped taking Zyrtec, these things went away.
This problem may be more pervasive than we think - if you are taking Zyrtec and having these symptoms, try dicontinuing it and see if the symtoms don't recur.
The ocular migraines may not be a big enough issue for doctors or drug companies to be concerned about. In my experience, doctors will listen, nod their heads, and give no answers. They may perscribe tests that don't show anything relevant.
I've seen ads for a recently released (and probably quite expensive) medication for migraine headaches. Although the auras are probably not enough (unless you're driving, and can't see enough around the auras to drive safely) and usually don't last very long, this medication may be overkill - but for some brave person, it may be worth a try (these are, after all, a symptom of migraine - or so they're called).