Many of us in optometric practice have received calls through the years from patients in a state of anxiety about potentially going blind. Their loss of vision is transient, and the description is nearly always the same: There is a visual disturbance along the line of sight that obscures what they’re trying to look at. The diagnostic giveaway is that the perception builds over the course of 10 or 15 minutes, and subsides in a similar time frame. There is a vibratory pulse to the pattern, which is called an aura, and it may occur with or without a migraine. Here is a slide show depicting what auras look like.
Although I learned about auras as a student at the Pennsylvania College of Optometry, like so many other phenomena it wasn’t until I personally experienced one with its temporal time frame and jagged edges that I fully grasped what patients were perceiving. Nor was what I learned in school necessarily the best source of information. For that I highly commend the book Migraine by Oliver Sacks. A blog written by Dr. Sacks on the subject about 5 years ago revisits his personal experiences as a migraineur with auras.
So-called mini-strokes, or TIAs, are different strokes than most people think of, being relatively silent in nature. Ischemia or a disruption in blood flow has been the best guess through the years as to what causes the pattern of disturbance in aura, but where exactly in the brain this took place has been obscure. Turns out it may have something to do with regional blood flow disruption through the Circle of Willis, which does seem plausible based on the relative location of the disturbance in the visual field.
For more about this fascinating topic and a tour of the Circle of Willis, see this Science Daily piece shared with us by Dr. Michael Margareten.