Nystagmus

Japanese: 眼球振盪 - がんきゅうしんとう（英語表記）nystagmus

Also called nystagmus. It is an involuntary, rhythmic, repeated back and forth movement of the eyes. There are pendulum-like nystagmus, in which the eyes move back and forth between two points like a pendulum, and rhythmic nystagmus, in which the eyes move slowly in one direction and rapidly in the other. It can also appear in healthy people under special conditions. Physiological nystagmus is useful for gazing at moving objects in the outside world, but pathological nystagmus is often accompanied by dizziness, balance disorders, and oscillating vision (objects flickering and making it difficult to look at them). These symptoms appear in various neurological disorders, brain disorders, eye disorders, and inner ear disorders, and nystagmus tests are often useful for diagnosing them.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

眼振ともいう。眼球の不随意的，律動的に反復する往復運動をいう。眼球が2点間を振り子のように往復する振り子様眼振と，一方向にはゆるやかで，他方向には急速に移動する律動眼振とがある。健康者でも特殊な条件下で現れる。生理的な眼振は，移動する外界の物体の注視に役立つが，病的なものは，めまい，平衡障害，動揺視 (物がちらちら揺れて，見つめにくい) などを伴うことが多い。種々の神経疾患，脳障害，眼疾患，内耳疾患などの際にこれらの症状が現れ，その診断のために眼振の検査が役立つことも多い。

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