術中虹彩緊張低下症候群の白内障手術後に残存した水晶体小片により角膜内皮の減少をきたした1例

A case of IFIS accompanied by corneal endothelial cell loss by a lens remnant after cataract surgery

要約　目的：術中虹彩緊張低下症候群（IFIS）を伴う白内障手術中に水晶体核片が残存し再手術にて除去したが，短期間で角膜内皮の著明な減少をきたした1例を報告する。

症例：85歳，男性。東邦大学医療センター佐倉病院（当院）にて左眼白内障手術を受けたが，術中にIFISを発症した難症例であった。術後早期は視力良好であったが，術後29日目に左眼視力低下を訴え近医を受診し，眼内炎の疑いで当院に紹介となった。

所見：左眼視力は（0.04）と低下し，前房内の残存水晶体とそれに隣接した限局性の角膜全層浮腫が認められた。左眼角膜内皮細胞数は術前2,641個/mm²から1,434個/mm²まで減少していた。術後40日目に再手術にて残存水晶体を摘出した。核片除去手術後86日目には左眼視力は（0.9），角膜浮腫は改善したが，角膜内皮細胞数は510個/mm²と著明に減少した。

結論：残存した水晶体が機械的接触をすることや，炎症を惹起し角膜へ波及することによって角膜内皮が減少するため，IFISを伴う白内障手術は，水晶体の一部が残存しないように注意しながら行う必要がある。また，たとえ小片であっても早急に除去するべきであると考えられた。

Abstract　Purpose：To report a case of intraoperative floppy iris syndrome（IFIS）in whom a nuclear fragment remained after cataract surgery. Despite its removal, remarkable corneal endothelial cell loss was observed within a short period.

Case：An 85-year-old man underwent cataract surgery of the left eye at our hospital. The surgery was difficult to perform due to IFIS；however, his postoperative visual acuity was good immediately after surgery. He complained of decreasing visual acuity in his left eye and was referred to our hospital by his family doctor due to suspected endophthalmitis 29 days after the initial surgery.

Findings：The best corrected visual acuity in his left eye was reduced to 0.04；a lens remnant in the anterior chamber and adjacent localized corneal edema were observed at the subsequent examination 35 days after the initial surgery. The left corneal endothelium had decreased from 2,641 cells/mm²（preoperatively）to 1,434 cells/mm²（postoperatively）. The remnant was removed by reoperation；3 months after reoperation, the best corrected visual acuity of the left eye had improved to 1.0 and the corneal edema had improved；however, the corneal endothelium had markedly decreased to 510 cells/mm².

Conclusion：Even the smallest lens remnant should be removed promptly, as it can cause intraocular inflammation and spread to the cornea, and mechanical contact can markedly reduce the corneal endothelium. Moreover, cataract surgery should be performed with care in IFIS cases to prevent retained lens fragments.