本態性血小板血症に網脈絡膜循環障害をきたした1例

Disturbed circulation in the retina and choroid in a case of essential thrombocythemia

要約　目的：網膜と脈絡膜の循環障害が生じた本態性血小板血症の症例の報告。症例：64歳女性が前日からの右眼の眼痛と視朦で受診した。血小板が増加する本態性血小板血症が7年前からあった。所見：矯正視力は右手動弁，左1.2で，右眼の網膜静脈に口径不同，拡張と蛇行があり，後極部が白濁し，乳頭の発赤腫脹があった。左眼には異常所見はなかった。蛍光眼底造影では，造影開始が遅延し，網膜中心動脈閉塞症と診断した。光干渉断層計と網膜電図の所見もこれと一致した。赤外蛍光造影検査では後極部脈絡膜の循環障害があった。初診時の血小板数は，84.6万/μlであった。3か月後に左眼に視朦が生じた。視力は良好であったが，左眼の網膜静脈の拡張と蛇行があり，乳頭が発赤していた。右眼に乳頭新生血管があり，2か月後に硝子体出血，さらに虹彩ルベオーシスが生じ，眼圧が上昇した。初診から1年後の現在，視力は右手動弁，左1.5で，血小板数は24万/μl前後で安定している。結論：本態性血小板血症は網膜だけでなく，脈絡膜にも循環障害が生じる可能性のあることを，本症例では示している。

Abstract.　Purpose：To report a case of essential thrombocythemia with disordered circulation in the retina and choroid. Case：A 64-year-old female presented with pain and progressive blurring in the right eye since previous day. She had been treated for essential thrombocythemia since 7 years before. Findings：Corrected visual acuity was hand motion right and 1.2 left. The right fundus showed irregular dilatation of retinal veins and swelling of the disc. Fluorescein angiography showed delayed onset of dye inflow, leading to the diagnosis of central retinal artery occlusion. Findings by optical coherence tomograph and electroretinogram were compatible with the diagnosis. ICG angiography showed impaired circulation in the submacular choroid. The left eye was apparently normal. The platelet count was 846×10³/μl. Blurring in the left eye developed 3 months later. The fundus showed dilatation and tortuosity of retinal veins with disc swelling. Visual acuity was 1.0. The right eye showed disc neovascularization followed by vitreous hemorrhage and rubeosis iridis 2 months later. One year after her initial visit, visual acuity is maintained at hand motion right and 1.5 left with platelet count of 240×10³/μl. Conclusion：This case illustrates that disturbed circulation may manifest in the retina and also in the choroid as related to essential thrombocythemia.