A:
Doctors use the terms optical or visual migraine when a person experiences the vision changes (aura) that are typical of a migraine, but has no headache. Other terms for this condition include migraine aura without headache, and acephalic headache.
An aura is an alteration of the senses that is a typical part of a migraine headache. (A migraine preceded by an aura is called a "classic" migraine; a migraine headache without an aura is called a "common" migraine). Most auras affect the vision, but can also cause changes in hearing, smell or taste. These symptoms occur within 30 to 60 minutes of the beginning of a migraine headache. They increase slowly over about five to 10 minutes, reach a maximum intensity, then gradually fade away.
Migraine sufferers, or "migraneurs," usually describe their visual auras as flashing, pulsing or wavering lights. The visual changes often have a zig-zag or geometric pattern, and that may "march" slowly from one side of the vision to the other. Some individuals develop a blind spot during the attack. The location of the aura is usually opposite the side of the head where the migraine headache will later occur.
Only about one in three migraine sufferers experience auras. More importantly, not all auras are caused by migraine. It is believed that an aura is produced when there is a decrease in blood flow to a part of the brain that is responsible for vision. Any process that affects blood flow or electrical signals in the brain can produce an aura, including:
The fact that your symptoms last only for seconds also raises the possibility that they are caused by a problem in the eye, rather than the brain. Medical problems affecting the eyes — such as a detached retina — can mimic a migraine aura. However, these usually affect only one eye (an aura affects the vision in both eyes), are very brief, and have a less "geometric" pattern than an aura.
