蛍光眼底造影検査にてIRVAN症候群の診断に至った2例

Two cases of IRVAN syndrome diagnosed by fluorescent angiography

要約　目的：IRVAN症候群は特発性の網膜血管炎，網膜血管瘤，視神経網膜炎をきたす疾患である。2例経験したので報告する。

症例：症例1は76歳，男性。X年8月に視力低下，飛蚊症を主訴に前医を受診し，閉塞性血管炎を指摘され，9月に東京大学医学部附属病院眼科（当科）へ紹介され受診した。初診時の矯正視力は右0.8，左0.6，眼圧は正常，両眼前房内細胞，両眼視神経乳頭からの白線化した網膜動脈，網膜出血，硝子体混濁を認めた。その後，両眼虹彩新生血管，左眼硝子体出血を発症した。眼内液PCR検査，全身精査をするも明らかな原因疾患を認めず，蛍光眼底造影検査で広範な無灌流域，血管分岐部に多数の血管瘤を認め，IRVAN症候群と診断した。ステロイド内服，両眼汎網膜光凝固術，左眼抗VEGF薬硝子体注射を施行した。左眼硝子体出血に対しては硝子体手術を施行した。症例2は60歳，女性。Y年1月に右眼視力低下をきたし，同月に当科を紹介され受診した。初診時の矯正視力は右0.3，左1.0，眼圧は正常，両眼底に黄斑前膜，視神経乳頭付近に白線化した動脈血管，網膜出血，右眼に黄斑浮腫，硝子体混濁を認めた。蛍光眼底造影検査で両眼視神経乳頭過蛍光，右眼優位に網膜動脈分岐部の複数の血管瘤，周辺部無灌流域を認め，IRVAN症候群と診断した。右眼に対しトリアムシノロンテノン囊下注射，網膜光凝固術を施行した。以後，病変の活動性を認めなかった。

結論：IRVAN症候群には早期診断と適切なレーザー治療が重要である。

Abstract　Purpose：To report two cases of idiopathic retinal vasculitis, aneurysms, and neuroretinitis（IRVAN）syndrome who were diagnosed by means of fluorescein angiography（FA）.

Case report：Case 1　A 76-year-old male was referred to the University of Tokyo Hospital for bilateral vasculitis. At the first visit, corrected visual acuity was 0.8 in the right eye, 0.6 in the left eye, and intraocular pressure was normal. Anterior chamber cells, perivascular sheathing in arteries, retinal hemorrhage, and vitreous opacity were found bilaterally. Later, bilateral iris neovascularization and vitreous hemorrhage developed in the left eye. Infectious retinitis was excluded by PCR tests using aqueous humor and by systemic work-up. FA revealed an extensive non-perfusion area and multiple aneurysms. Finally, the patient was diagnosed with IRVAN syndrome. Oral steroids, bilateral panretinal photocoagulation, and intravitreous injections of anti-vascular endothelial growth factor agent were administered. Vitrectomy was performed for vitreous hemorrhage. Case 2　A 60-year-old female was referred to our hospital for decreased visual acuity of the right eye. At the first visit, corrected visual acuity was 0.3 in the right eye and 1.0 in the left eye, and intraocular pressure was normal. Epiretinal membrane, perivascular sheathing in arteries, and retinal hemorrhage were found bilaterally, whereas macular edema and vitreous opacity were found in the right eye. FA revealed staining of the optic disc, multiple aneurysms, and non-perfusion areas in the periphery, bilaterally. She was diagnosed with IRVAN syndrome. Sub-Tenon triamcinolone acetonide injection and retinal photocoagulation were performed in the right eye. No progression was observed thereafter.

Conclusion：Early diagnosis and appropriate retinal photocoagulation are essential for IRVAN syndrome.