硝子体手術後の遅発性視野欠損の1例

A case of late-onset visual field defect after vitreous surgery

　68歳女性が緑内障で受診した。右眼に＋2.75D，左眼に＋2.5Dの遠視があり，矯正視力は1.0であった。両眼に乳頭陥凹と緑内障性視野欠損があった。両眼が狭隅角であり，レーザー虹彩切開術を行った。その14か月後に左眼の視野が0.2に低下し，黄斑円孔が生じていた。手術は後部硝子体剝離を作製したのち，20％SF₆で硝子体内容を置換した。灌流空気は加湿しなかった。術後5日間，顔面を下向きに保ち，円孔は閉鎖した。その16か月後に白内障手術を行い1.0の矯正視力を得た。硝子体手術から26か月後に左眼の耳側下方に視野欠損を自覚し，視野検査でそれが確認された。黄斑円孔への手術後に行った2度の視野検査では視野異常はなかった。硝子体手術の際の空気灌流に続発した晩発性視野障害の可能性がある。

　A 68-year-old female was referred to us for glaucoma. The visual acuity was 1.0 in either eye when corrected by＋2.75D right and＋2.5D left. Both eyes showed disc excavation and glaucomatous visual field defect. Both eyes received laser iridotomy for narrow angle. Macular hole developed in her left eye 14months later. We performed vitreous surgery. After artificial posterior vitreous detachment,the vitreous was replaced by 20％sulfur hexafluoride. The irrigating air was not humidified. The macular hole closed after keeping face-down position for 5 days. Cataract surgery was performed 16months later. Twenty-six months after macular hole surgery,the patient noted visual field defect in the lower temporal sector in her left eye. Perimetry corroborated the finding. No such visual field defect had been detected by two sessions of perimetry after macular hole surgery. There is a possibility that air irrigation may have induced the late-onset visual field defect.