治療的角膜移植を回避できたgraft-host接合部にまたがる感染性角膜炎の1例

Case of infectious keratitis at the graft-host junction that allowed therapeutic corneal transplantation to be avoided

要約　目的：角膜移植眼のgraft-host接合部にまたがる感染性角膜炎は，いまだ有効な外科的治療法が確立されておらず難治性といえる。今回，角膜穿孔に至ったgraft-host接合部にまたがる感染性角膜炎に対し，治療的角膜移植を行わず薬物治療のみで感染の鎮静化が得られたので報告する。

症例：78歳，男性。格子状角膜ジストロフィ（TGFBI遺伝子L527Rホモ接合体）の症例。右眼は21年前と9年前に全層角膜移植術（PKP）を施行された。Graft-host接合部にまたがる膿瘍を認め，感染性角膜炎と診断した。視力は手動弁であった。塗抹検査で好中球を認め，移植眼であることからカンジダを疑い，抗真菌薬を中心に局所および全身投与を開始した。治療開始13日目に角膜穿孔をきたし，脈絡膜剝離を認めたが，膿瘍自体は縮小傾向であったため治療的角膜移植を行わずに薬物治療を継続した。25日目に潰瘍は消失し，感染徴候も消失した。57日目には脈絡膜剝離も消失し，前房も再形成された。92日目には視力が0.02まで改善した。

考察：筆者らは従来，角膜中央から周辺に及ぶ感染性角膜炎に対して，中央にPKP，周辺に部分的強角膜移植を行ってきた。この術式では感染の鎮静化はおおむね得られるものの，視力予後は不良であった。本症例では治療中に角膜穿孔に至ったものの，感染は治まりつつあると判断して薬物治療を継続し，感染の鎮静化と眼球形状の回復を得ることができた。

結論：PKP眼において感染巣がhost側に及び穿孔した場合でも，膿瘍などの感染徴候が消退しつつあれば治療的角膜移植を回避する選択肢もある。

Abstract　Purpose：Infectious keratitis at the graft-host junction in corneal transplantation is persistent because an effective surgical treatment is currently undeveloped. We report a case of infectious keratitis at the graft-host junction that resulted in corneal perforation that was successfully treated with drug therapy, without therapeutic keratoplasty.

Case：The patient was a 78-year-old male, with lattice corneal dystrophy type ⅢA（homozygous mutation［L527R］in TGFBI）. The right eye had undergone penetrating keratoplasty（PKP）21 and 9 years prior. The patient was diagnosed with infectious keratitis in the right eye due to an abscess in the graft and host. Visual acuity was defined based on hand motion. On microscopic examination of the smear, neutrophils were observed. Candida was suspected as the causative organism, and topical and systemic treatments with antifungal agents were initiated. On the 13^th d of treatment, corneal perforation occurred and choroidal detachment was observed, but the abscess was shrinking；therefore, drug treatment was continued without therapeutic keratoplasty. On the 25^th d of treatment, the corneal ulcer resolved and signs of infection disappeared. Fifty-seven days later, the choroidal detachment disappeared and anterior chamber was reformed. Visual acuity improved to 0.02 on day 92.

Discusion：We performed central PKP with peripheral partial scleral keratoplasty for infectious keratitis, extending from the center to the periphery of the cornea. Although this technique generally results in improvement of the infection, postoperative visual acuity is poor. In this case, although corneal perforation occurred during treatment, we judged that the infection subsided and continued drug treatment, consequently the infection improved and ocular structure was recovered.

Conclusion：After keratoplasty, even if the infection extends to the recipient side and corneal perforation occurs, therapeutic keratoplasty can be avoided if the signs of infection, such as abscess size diminish.