I also suffered something similar on multiple occassions in my late 20s and early 30s - growing rainbow zig-zags accompanied by graduals loss of vision in both the center of my field of view and edges of my peripheral vision, although never to the point of total blindness. Incidents would last between one and two hours. But, after several ophatmologist and visits to other physicians, I finally found the trigger: it happened roughly 18 hours after consuming 2 or more glasses of absinthe. Stopped drinking absinthe, haven't had an aura in years.