眼窩底骨折整復術後に僚眼の下斜筋過動を呈した1例

Inferior oblique muscle overaction after surgical repair of blowout fracture in the fellow eye

要約　目的：眼窩底骨折整復後に最も顕著な眼球運動障害が僚眼の下斜筋過動症であった症例を報告する。

症例：41歳男性。左眼窩底骨折のため，計2回の左眼窩底骨折整復術を受けた。その後，徐々に正面視で上下・回旋複視が出現し，右眼の眼位異常も顕著となり，受傷から10か月後に当科を受診した。眼位は右上斜視で，眼球運動では左方視で右眼の下斜筋過動症を高度に認めた。左眼の斜視手術に加え，右眼の下斜筋減弱術を施行し，術後，正面視での複視は消失し，右眼の下斜筋過動症もほぼ消失した。

結論：右眼に認められた左方視での下斜筋過動症は左眼の下直筋拘縮に伴うものであり，両眼視改善には患眼への斜視手術だけでなく僚眼の下斜筋減弱術が有効であった。

Abstract　Purpose: To report a case who showed inferior oblique muscle overaction after surgical repair of blowout fracture in the fellow eye.

Case: A 41-year-old male suffered blowout fracture of the left orbit while involved in fist fighting. He received two sessions of surgery for orbital fracture. He then developed vertical and torsional diplopia with heterotropia of the right eye. He was seen by us 10 months after injury.

Findings: The right eye showed right hypertropia in the primary position. The right eye showed marked inferior oblique muscle overaction in the leftward gaze. He received strabismus surgery in the left eye and weakening surgery of inferior oblique muscle in the right eye. The surgery was followed by disappearance of diplopia and inferior oblique muscle overaction in the right eye.

Conclusion: Inferior oblique muscle overaction in the right eye was secondary to contracture of inferior rectus muscle in the left eye. Binocular vision improved after surgery in the injured eye as well as weakening surgery of inferior oblique muscle in the fellow eye.