An approximate sketch of a migraine aura.

This is a neurological phenomenon, occurring somewhere within my nervous sysem, probably the visual cortex. It is not to be confused with other claimed phenomena supposed to happen in the outside world. It is probably related to migraine headaches, which fortunately I'm not subject to. For me the aura is a purely visual experience, not accompanied by pain, dizziness or other symptoms. It doesn't interfere with normal vision, but is distracting. Your mileage may vary; for some people, it's a prelude to an actual headache.

I never saw an aura, so far as I can recall, until about age 38. After that it occurred at intervals of several years, and thereafter with increasing frequency.

The phenomenon is a process that takes perhaps 5 to 15 minutes to complete. It starts small and gradually expands to span the visual field. It is impossible to examine in detail because it is always at a fixed, off-center location within the visual field; if I try to look at it, it moves away. (That is one clear demonstration that it is internal, not in the outside world.)

The background color is the dark, nondescript color I see when I close my eyes. It may include afterimages from whatever I was looking at just previously. The brightly colored bands are not stationary but move like ripples in water. The separation into triangular regions with ripples moving in orthogonal directions is interesting; I have no explanation for it (except that the phenomenon is clearly a kind of oscillation, similar to the squeal of an audio system with feedback from speaker to microphone). The pattern is sometimes described as a zigzag line, but to me that description is inadequate. Among the moving bands of light there is often a brightest band, which may accidentally connect with the brightest band in an adjacent triangle, giving rise to the the impression of a zigzag line, but that ignores most of what is happening.

For a long time I didn't know what the phenomenon was called, but then came across a description of it somewhere on the web.

Having learned the medical term for it, I can easily find other attempts to represent it artistically. Here's the closest I've found to my own experience, shown with the eye open:

[link]

Here's another. Here it's call ophthalmic migraine:

[link]

It is always represented as a C-shaped region containing angular shapes. It may or may not be significant that all images I've seen so far show it curving the opposite way from mine, i.e. around the left side of the visual field.

I have to suspect those drawings were made by someone other than the person who had actually seen the aura, working from a verbal description.

Best drawing yet:

[link]