薬物治療に抵抗し硝子体手術が必要となったトキソプラズマ網脈絡膜炎の1例

A case of toxoplasmic chorioretinitis resistant to medical treatment and requiring vitrectomy

要約　目的：アセチルスピラマイシン内服治療に反応不良を示し，硝子体手術に至ったトキソプラズマ網脈絡膜炎の症例を報告する。

症例：63歳，男性。右眼の飛蚊症を主訴に前医を受診した。右眼汎ぶどう膜炎の診断で点眼加療を開始し，トリアムシノロン・テノン囊下注射を施行するも硝子体混濁は改善しなかった。右眼網膜周辺部に白色滲出病変を認めたため，当科へ紹介となった。初診時右眼肉芽腫性虹彩炎，硝子体混濁，網膜周辺部に瘢痕化した網膜萎縮巣および近傍に網膜滲出斑を認めた。前房水PCR検査でトキソプラズマDNAが陽性となり，トキソプラズマ網脈絡膜炎と診断し，アセチルスピラマイシン内服を開始した。しかし，内服開始7日後には右眼矯正視力が0.06に低下した。右眼の硝子体混濁が増悪し，眼底は透見不能となった。同日緊急入院し，右眼に白内障手術併用硝子体手術を施行した。術後は治療薬をスルファメトキサゾール・トリメトプリム製剤内服に変更したが，腎障害のため，アトバコン内服に変更した。網膜滲出病変は術後1か月でほぼ瘢痕化し，最終矯正視力は0.7まで回復した。

結論：トキソプラズマ網脈絡膜炎にステロイド単独治療を行うと，網脈絡膜炎の病勢が増悪する可能性があり，注意が必要である。本症例では病変部が網膜周辺部であったことに加え，眼底視認性の確保のための硝子体手術および効果不良な薬物療法の変更が，視力予後改善に寄与した可能性がある。

Abstract　Objective：We report a case of toxoplasmic chorioretinitis that was resistant to oral acetylspiramycin treatment and required emergency vitrectomy.

Case：A 63-year-old man presented to his previous physician with floaters in his right eye. He was diagnosed with right-eye panuveitis, and topical treatment was initiated. Despite sub-tenon injection of triamcinolone, vitreous opacification developed. He was referred to our department after a white exudative lesion was found in the peripheral retina of his right eye. At initial consultation, granulomatous iritis, vitreous opacification, and a scarred retinal atrophy lesion in the peripheral retina, along with nearby retinal exudates, were observed in the right eye. A polymerase chain reaction test of the aqueous humor revealed positivity for Toxoplasma DNA. A diagnosis of toxoplasmic chorioretinitis was made, and oral acetylspiramycin was initiated. However, after 7 days of treatment, the best-corrected-visual acuity（BCVA） decreased to 0.06 in the right eye. Vitreous opacity in the right eye worsened, and fundus visualization became impossible. The patient was admitted to the hospital on the same day and underwent emergency cataract surgery and vitrectomy on the right eye. After surgery, the medication was changed to oral trimethoprim-sulfamethoxazole, but due to renal impairment, it was changed to oral atovaquone. The retinal exudate lesions were almost completely scarred 1 month after surgery, and the final BCVA recovered to 0.7.

Conclusion：Caution is required when treating toxoplasmic chorioretinitis with steroids alone, which can worsen the condition. In this case, the lesion was located in the peripheral retina, and vitrectomy（to ensure fundus visibility） and change in ineffective drug therapy may have contributed to the improved visual prognosis.