Migraine aura
A shimmering, expanding zigzag arc of light that grows across one half of vision over 5–30 minutes, often followed by a headache.
Try Migraine aura in the simulator →What it looks like
Migraine aura typically starts as a small, bright, flickering point near the center of vision. Over 5–60 minutes (most commonly 20–30), it slowly expands outward in a C-shape — into the left or right half of vision. The leading edge has a sparkling, zigzag pattern called the "fortification spectrum" (because it resembles castle walls seen from above). The trailing area is often dimmed or blurred (the scotoma). The aura affects both eyes the same way because it originates in the brain's visual cortex.
Why it expands
The expansion follows a wave of neural activity called cortical spreading depression, which moves across the brain's visual cortex at about 3 millimeters per minute. This matches the gradual outward growth of the aura that patients describe and draw.
After the aura
In about 70–80% of cases, a headache follows the aura. Some people have aura without any headache afterward (silent migraine).
When to see a doctor
If you're having auras for the first time — especially over age 40 — see a doctor to rule out other causes such as stroke or seizure. Sudden, severe headache with neurological changes is a medical emergency.
Also known as
Scintillating scotoma · Fortification spectrum · Visual aura