This is a visual distortion that can occur during or before a migraine headache. Migraines are bad headaches associated with sensitivity to light or sound (and often nausea). Like most headaches, the underlying mechanism is not entirely understood but migraines may occur because of spasm of blood vessels in the brain. With some people, the spasming vessels occur at the back of the brain near the occipital cortex. This is the part of the brain that processes our vision, and when irritated, the occipital cortex can create visual hallucinations. Most people describe an “aura” to their vision where the center of their vision (or perhaps more to the side) becomes blurry. They may see lights, sparkles, or geometric distortions like a kaleidoscope. These visual changes tend to expand and spread to one side before subsiding after 15 to 30 minutes. Afterwards, some people get the traditional migraine headache, but other people have the visual symptoms alone with no residual discomfort. Migraine auras can be scary but are rarely serious. Some people are worried when their visual symptoms “change sides” and occur on the other half of the vision. This is actually a good sign, however, as variation is typical for migraines. It’s when you have the same visual phenomenon over and over, always in the same place that we have to consider other possibilities like a mass lesion that is tickling the occipital lobe in one spot. In these cases, an MRI is obtained.