Ocular Migraine

Visual aura of migraine without headache

Overview

Ocular migraine is an informal term most often used for the visual aura of migraine, sometimes occurring without a following headache, a pattern also called migraine aura without headache. The typical visual aura is a scintillating scotoma, a shimmering, flickering spot that gradually enlarges and moves across the visual field, often with a zigzag edge known as a fortification spectrum, and it usually lasts from a few minutes up to about an hour before resolving. Because it originates in the visual cortex, it affects the visual field of both eyes. It is thought to reflect cortical spreading depression, a slowly advancing wave of neuronal activity across the surface of the brain. The gradual spread and positive visual phenomena help distinguish migraine aura from transient ischemic attacks, which typically cause sudden loss of vision. The term is also used for retinal migraine, a much rarer condition causing temporary visual disturbance or loss in one eye only, which is diagnosed after other causes of transient monocular vision loss are excluded.