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Strabismus (from Greek ''strabismós''〔(Online Etymology Dictionary )〕) is a condition that interferes with binocular vision because it prevents a person from directing both eyes simultaneously towards the same fixation point; the eyes do not properly align with each other. Heterotropia is a medical synonym for the condition. Colloquial terms for strabismus include cross-eye, wall-eye, and a cast of the eye. Strabismus typically involves a lack of coordination between the extraocular muscles, which prevents directing the gaze of both eyes at once to the same point in space; it thus hampers proper binocular vision, and may affect depth perception adversely. Strabismus is primarily managed by ophthalmologists, optometrists, and orthoptists. Strabismus is present in about 4% of children. Treatment should be started as early as possible to ensure the development of the best possible visual acuity and stereopsis. ==Signs and symptoms== When observing a patient with strabismus, the misalignment of the eyes may be quite apparent. A patient with a constant eye turn of significant magnitude is very easy to notice. However, a small magnitude or intermittent strabismus can easily be missed upon casual observation. In any case, an eye care professional can conduct various tests, such as cover testing, to determine the full extent of the strabismus. Strabismus can be seen in Down syndrome, Loeys-Dietz syndrome, cerebral palsy, and Edwards syndrome. Symptoms of strabismus include double vision and/or eye strain. To avoid double vision, the brain may adapt by ignoring one eye. In this case, often no noticeable symptoms are seen other than a minor loss of depth perception. This deficit may not be noticeable in someone who has had strabismus since birth or early childhood, as they have likely learned to judge depth and distances using monocular cues. However, a constant unilateral strabismus causing constant suppression is a risk for amblyopia in children. Small-angle and intermittent strabismus are more likely to cause disruptive visual symptoms. In addition to headaches and eye strain, symptoms may include an inability to read comfortably, fatigue when reading, and unstable or "jittery" vision. 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「Strabismus」の詳細全文を読む スポンサード リンク
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