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Scintillating scotoma is the most common visual aura preceding migraine and was first described by 19th-century physician Hubert Airy (1838–1903). It is often confused with ocular migraine, which originates in the eyeball or socket. ==Signs and symptoms== Many variations occur, but scintillating scotoma usually begins as a spot of flickering light near or in the center of the visual field, which prevents vision within the scotoma area. The affected area flickers but is not dark. It then gradually expands outward from the initial spot. Vision remains normal beyond the borders of the expanding scotoma(s), with objects melting into the scotoma area background similarly to the physiological blind spot, which means that objects may be seen better by not looking directly at them in the early stages when the spot is in or near the center. The scotoma area may expand to completely occupy one half of the visual area, or it may also be bilateral. It may occur as an isolated symptom without headache in acephalgic migraine. As the scotoma area expands, some people perceive only a bright flickering area that obstructs normal vision, while others describe seeing various patterns. Some describe seeing one or more shimmering arcs of white or colored flashing lights. An arc of light may gradually enlarge, become more obvious, and may take the form of a definite zigzag pattern, sometimes called a fortification spectrum (i.e. teichopsia, from Greek τεῖχος, town wall), because of its resemblance to the fortifications of a castle or fort seen from above.〔(【引用サイトリンク】title=imigraine.net )〕 It also can resemble the dazzle camouflage patterns used on ships in WWII. Others describe patterns within the arc as resembling Widmanstätten patterns. The visual anomaly results from abnormal functioning of portions of the occipital cortex at the back of the brain, not in the eyes nor any component thereof, such as the retinas.〔(【引用サイトリンク】title=imigraine.net )〕 This is a different disease from retinal migraine, which is monocular (only one eye).〔(【引用サイトリンク】title=Retinal migraine )〕 It may be difficult to read and dangerous to drive a vehicle while the scotoma is present. Normal central vision may return several minutes before the scotoma disappears from peripheral vision. Sufferers can keep a diary of dates on which the episodes occur to show to their physician, plus a small sketch of the anomaly, which may vary between episodes. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Scintillating scotoma」の詳細全文を読む スポンサード リンク
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