When i was in my 30s migraine auras were common.
Starts out like a spot on the field of vision, as if i had been staring at the sun, then it grows to a half circle appearing mostly on the left side, then it grow so big that it passes beyond what i can see. I remember that the half circle is filled with patterns and colours that repeat and move in multiple directions, i cannot focus on it to see details. I can still see, walk around and grab objects etc, it's just annoying when it happens.
I get no headaches, just the temporary partial visual impairment. Haven't had one for years. I have read about them and it seems related to the visual centre in the back of the brain and pressure or something like that.
Found a good animation of what it looks like.
Yes, that is very close to what mine look like but there is no normal vision left, it is my whole field of vision.