エクスプレス®挿入術後の強膜フラップ厚の経時的変化

Changes in scleral flap thickness after Ex-PRESS® implantation

要約　目的：エクスプレス^®（アルコン社）は緑内障濾過手術に用いるデバイスであり，従来の術式よりも合併症が少ないと報告されている。一方で，デバイス特有の合併症として結膜上への露出があり，強膜フラップの経時的な菲薄化の可能性が示唆される。そこで今回エクスプレス^®挿入術後の強膜フラップ厚の経時的変化を検討した。

対象と方法：エクスプレス^®挿入術を施行した27例29眼を対象とし，術後の眼圧や追加治療の有無によりコントロール良好群17例19眼と不良群10例10眼に分けた。術後1週，1，3，6か月の時点で前眼部光干渉断層計（CASIA，トーメー社）を用いて濾過胞を撮影し，断面像より強膜フラップ厚を測定した。角膜輪部から1.5mmまでの強膜フラップを前方，それ以降を後方とし，それぞれ比較検討した。

結果：良好群の強膜フラップ厚は，前方・後方ともに経時的変化はなかった。不良群の強膜フラップ厚は，有意差はないものの前方・後方とも徐々に薄くなる傾向があった。術後1週と6か月の強膜フラップ厚を比較すると，6か月において良好群で前方9μm，後方6μm，不良群で前方59μm，後方34μm菲薄化しており，前方の変化量に両群間で有意差があった（p＜0.05）。

結論：エクスプレス^®挿入術後に，眼圧コントロール不良例では強膜フラップが薄くなる可能性が示唆された。特にエクスプレス^®の鍔と接触する輪部付近の強膜フラップにおいて，その傾向は顕著であった。

Abstract　Purpose：The Ex-PRESS^®（Alcon）glaucoma filtration device is inserted under the partial thickness scleral flap for shunting aqueous humor from the anterior chamber into the filtering bleb. According to the past studies, postoperative complications were less common after Ex-PRESS^® implantation compared with trabeculectomy. On the other hand, there were some case reports about the device exposure through the scleral flap as one of the device-related complications. This study aims to assess longitudinal changes in scleral flap thickness after Ex-PRESS^® implantation.

Subjects and Methods：Twenty-nine blebs of 27 patients who had undergone glaucoma filtration surgery with Ex-PRESS^® implantation were consecutively examined for 6 months. All subjects were classified as good or poor IOP-control group by intraocular pressure（IOP）and additional treatment postoperatively. The scleral flap thickness of blebs was measured by anterior segment optical coherence tomography（AS-OCT）. We defined the anterior scleral flap as the area to 1.5 mm from corneal limbus and the posterior scleral flap as the rear area. Time-course changes in the anterior and posterior scleral flap thickness were evaluated respectively.

Results：There were 19 blebs in the good IOP-control group and 10 blebs in the poor IOP-control group. In the poor IOP-control group, the scleral flap thickness became gradually thinner after surgery. The difference in the anterior scleral flap thickness between 1 week and 6 months after surgery was 9 μm in the good IOP-control group, while that in the poor IOP-control group was 59 μm, showing a significant difference between them（p＜0.05）. The difference in the posterior scleral flap thickness between 1 week and 6 months after surgery was 6 μm in the good IOP-control group, while that in the poor IOP-control group was 34 μm, showing no significant differences between them.

Conclusions：In the poor IOP-control cases, the scleral flap thickness became gradually thinner after Ex-PRESS^® implantation. This tendency was more prominent in the anterior part of the scleral flap which was touching the filtration device.