Visual aura is commonly associated with migraine, although not everyone with migraine has aura and not all auras are visual. A recent article intended as an overview for health care providers offers interesting insights for migraine with aura, which I've highlighted below.
People with migraine may only have one visual aura in their entire lives, while others have visual symptoms with every migraine.
Visual aura typically occurs before the headache phase of a migraine attack, but can happen during the headache phase or even after the headache is over.
Some people experience only visual aura and no other migraine symptoms at all.
The intensity and appears of visual aura also varies widely. The range runs from brief, tiny light spots to complex and long-lasting visual experiences.
The typical aura pattern is teichopsia (also called a scintillating scotoma). It is “a slowly expanding luminous horseshoe-shaped zigzag perception” that may be followed by “a bean-shaped area with low visual acuity.” Teichopsias often start in the center of a person’s vision, then progress to the peripheral vision over about 20 minutes, though the reverse can also happen. It may include a complex pattern of interlaced shining lines, which are unlikely to be in color.
Although teichopsia is the typical pattern, it is not the most frequent visual disturbance in an aura. In one study, the most common symptoms were:
- blurry vision (54.1%)
- small bright dots (47.5%)
- zigzagged lines (41.8%)
- C or crescent shape (16.4%)
In another study, participants reported additional aura disturbances, including:
- seeing small bright dots (42%)
- light flashes or white spots (39%)
- blind spots (32%)
- foggy vision (27%)
- zigzags (20%)
People sometimes describe visual auras as like looking through semi-transparent glass, waves of heat over asphalt on a sunny day, or falling water.
Most auras are black-and-white. Color-filled auras are reported by approximately 20-30% of people.
A change in color perception may accompany an aura. Colors can either appear faded or brighter than usual. People may not even notice a change in color perception until a health care provider asks them about it.
Complex visual hallucinations may be part of an aura. This can include distortions in body image (like arms or hair being two or three times longer than normal), a feeling that the body is split into two halves, alien hand syndrome (feeling like your hand doesn’t belong to you), a sense of being too big or too small, a change in how objects appear (closer, farther, smaller, bigger), distortions of faces and images, an inability to recognize faces, misperception of color, and changed vision (mosaic, kaleidoscopic, or cubist), as well as other visual distortions. Visual snow may also be related to these hallucinations.
Why visual changes are so prominent in migraine compared to other sensory changes is not fully understood. It is likely related to the amount of the brain that is involved in vision.
Cortical spreading depression is the currently the most accepted explanation for migraine aura. CSD is a disturbance in brain function caused by a temporary, slow-spreading suppression of the electrical activity in the brain region called the cortex. “Cortical” means that it’s in the cortex, “depression” is the suppression of electrical activity, and “spreading” indicates that the depression spreads through the region of the brain.
Vincent, M. B. (2015). Vision and Migraine. Headache: The Journal of Head and Face Pain.