外斜視術後周期性内斜視の1例

A case of cyclic esotropia after surgery for intermittent exotropia

要約　目的：外斜視に対する手術後に生じた周期性内斜視の1症例の報告。症例：4歳11か月の女児に2年前から眼位異常があった。間欠性外斜視として紹介受診した。視力は左右眼とも1.5で，プリズムカバーテストで近見－35Δ，遠見－30Δの間欠性外斜視があった。左眼の内直筋5mmの短縮と外直筋5mmの後転を行った。術後1か月に遠見＋4Δの内斜視と左眼外転不全が生じ，術後6か月で遠見＋14Δの内斜視となり，左眼の外転不全があった。正位と内斜視の眼位が交互に出現することから，周期性内斜視と診断した。内斜視が次第に優位となり，初回の手術から8か月後に左眼の外直筋を本来の付着部に戻した。以後は良好な眼位になり，周期性は消失した。結論：間欠性外斜視に対して手術を行い，過矯正になり，外転不全が残存した症例に周期性内斜視としての再手術を行い，好結果を得た。

Abstract.　Purpose：To report a case of cyclic esotropia after surgery for intermittent exotropia. Case：A 5-year-old girl showed abnormal eye position since 2 years and was referred to us as intrermittent exotropia. Visual acuity was 1.5 in either eye without correction. Prism cover test showed intermittent exotropia with －35Δ for near and －30Δ for distance. She received 5mm recession of medial rectus and 5 mm resection of lateral rectus in the left eye. One month after surgery, the left eye showed restricted abduction with ＋4Δ esotropia. Six months after surgery, the left eye showed restricted abduction with ＋14Δ esotropia. She was diagnosed with cyclic esotropia. She received a second surgery by suturing the lateral rectus muscle of the left eye to the original site of insertion. The eye position became normal with disappearance of cyclic pattern. Conclusion：Surgery for intermittent exotropia resulted in overcorrection with restricted abduction. Another surgery for intermittent esotropia resulted in normal ocular motility.