Partial Blindness

While driving today, suddenly a dark disc descended over my vision field in my right eye.  I wiped, blinked repeatedly, winced,...everything I could imagine, but the obstruction remained.  I had to rear my head back in order to see properly with the eye.  It was as though someone had lowered a dark spoon partially over the iris.
The condition persisted for ten minutes, then cleared as suddenly as it came.  
What happened?  
Does it foreshadow further such occurrences?
Might it come again permanently?
Thanks for any help.

[Michael J Kutryb, MD]

It sounds most suspicious of amarosis fugax (a transient ischemic attack where one eye goes partially or totally blind for a few minutes then returns to normal.)  A visual migraine can sometimes act similarly but usually there is a bright shiny aura with zig zag lines.  I would call  your doctor right away or seek emergency care even if you have to since you could be at significant risk for a stroke.

MJK MD