亜急性後天性共同性内斜視における内直筋hang-back後転術の効果

The effect of medial rectus hang-back recession in subacute acquired concomitant esotropia

要約　目的：近年デジタルデバイスの過剰使用による亜急性後天性共同性内斜視（SAACE）が増加している。SAACEには短効性調節麻痺薬の就寝前点眼が有効であったが，長期経過した症例には手術治療が必要となる。さらに，内直筋の肥大や付着部の前方移動がみられ，筋付着部の変化が手術の結果へ影響すると報告されている。今回，SAACE手術症例の内直筋hang-back後転術の効果を検討した。

対象と方法：獨協医科大学埼玉医療センターで手術を受け，術後1年以上経過観察できたSAACE患者20例を対象とした。非優位眼に対して内直筋hang-back後転術および外直筋短縮術を行い，斜視角が大きい症例には僚眼手術も併施した。術前，術後1，3，6か月および1年の斜視角および立体視を検討した。

結果：術前に比べ，術後1週から斜視角は有意に減少し，再発はなかった。立体視も術後3か月で有意に改善し，術後1年まで良好であった。

結論：SAACEに対して外直筋短縮に加え内直筋のhang-back後転は有効であることが示唆された。

Abstract　Purpose：In recent years, cases of subacute acquired concomitant esotropia due to excessive use of digital devices（SAACE） have increased. In our previous study, short-acting cycloplegic eye drops were effective as treatment. However, surgical treatment became necessary in cases with a long-term course. Furthermore, hypertrophy of the medial rectus muscle and anterior displacement of its insertion were observed. The insertion changes have been reported to affect surgical outcomes. In this study, we examined the effects of medial rectus hang-back recession surgery in patients with SAACE.

Subjects and Methods：Among the patients with SAACE who visited our department, we included 20 cases who underwent surgery and could be followed up for more than 1 year postoperatively. We performed medial rectus hang-back recession and lateral rectus resection on the non-dominant eye. Fellow eye surgery was also performed in cases with a large strabismus angle. We examined the strabismus angles and stereopsis before surgery and at 1 week；1, 3, and 6 months；and 1 year postoperatively.

Results：Compared to preoperative measurements, the strabismus angle significantly decreased starting at 1 week postoperatively, and no recurrence was observed thereafter. Stereopsis also significantly improved at 3 months postoperatively and remained good for up to 1 year after surgery.

Conclusion：In addition to lateral rectus muscle shortening, medial rectus muscle hang-back recession appears to be effective for SAACE.