[b said:Quote[/b] ]Scintillating scotoma usually begins as a shimmering arc of white or colored lights in the homonymous portion of the left or right visual field. The arc of light gradually enlarges, becomes more obvious, and may take the form of a definite zig-zag pattern. Additionally, the scintillating scotoma may demonstrate the following features:
a. It may be a single band of light.
b. It may take on a more complex pattern.
c. It may demonstrate a shimmering quality or flickering quality similar to that of a fluorescent light fixture that is close to failure.
d. The scintillating scotoma may gradually move over the course of a few minutes across the visual field to a point of fixation in the visual field.
On occasion, the positive scotoma is preceded or followed by a spreading zone of visual loss (known as a negative scotoma). As a means of differentiating a positive scotoma from a negative scotoma, the positive (bright) scotoma may be seen by the patient with the eyes closed or while in the dark. The negative scotoma disappears with the eyes closed or when the patient is in the dark. Even if there is no identifiable area of visual loss, the disturbance of vision created by the scintillating scotoma may make reading and driving difficult. Scintillating scotoma may also be accompanied by mild feelings of dizziness or vertigo.