尿崩症患者に生じた低眼圧黄斑症

Hypotony maculopathy in a case of diabetes insipidus

　8か月前に右眼白内障手術を受けた尿崩症を有する79歳の女性が，霧視を訴えて来診した。矯正視力は術後0.6から0.2へ低下し，右眼圧は0mmHgであった。眼底に脈絡膜皺襞と黄斑浮腫がみられ低眼圧黄斑症と診断した。バゾプレシン投与を開始して尿量が正常化し，血液および尿浸透圧が改善するにつれ，眼圧は回復し視力も上昇した。尿崩症という多量の尿排泄がいわば高浸透圧利尿薬のように作用し，白内障手術眼に低眼圧黄斑症をきたしたと考えられた。内眼手術後の晩期合併症として生じる低眼圧の原因として稀ではあるが尿崩症も鑑別し，患者の尿量にも注意を要する。

A 79-year-old female presented with blurring in her rignt eye of two week's duration. She had received cataract surgery with intraocular lens implantation in the same eye 8 months before. She had also been diagnosed as insulinoma followed by splenectomy and partial panreatectomy 6 years before. Diabetes insipidus had been present since one year before. The visual acuity in her right eye was 0.2. The intraocular pressure (IOP) was 0 mmHg. Funduscopy showed choroidal folds and macular edema, leading to the diagnosis of hypotony maculopathy. The left eye was normal except for ocular hypony with IOP of 8 mmHg. After start of systemic vasopressin, the urine volume decreased to normal level. The IOP was 12 mmHg and the visual acuity in her right eye was 0.5 at day 18 of treatment. It appeared that the ocular hypotension was initiated by low serum osmolarity due to diabetes insipidus and was triggered by cataract surgery.