眼窩内への異物刺入による視神経損傷の1例

A case of optic nerve damage by a penetrating orbital foreign body

　13歳男児が転倒し，竹の棒が左眼窩下縁で貫通した。その直後に受診した。左眼視力は零で，瞳孔が散大し，対光反応が欠如していた。磁気共鳴画像検査（MRI）で左眼の視神経腫大，球後出血，6mmの眼球突出があった。異物は検出されなかった。副腎皮質ステロイド剤の全身投与を開始し，その直後に光覚弁となり，受傷6日後に0.1,10日後に0.3，最終的に0.6の視力が得られた。穿孔性異物で視神経が直接損傷し，光覚が消失していても，ステロイド剤投与で視機能が回復した例である。

A 13 year-boy suffered penetrating injury by a bamboo stick through the lower margin of the left orbit. When seen immediately after the injury, the left visual acuity was nil and the pupil was dilated with negative light reaction. Magnetic resonance imaging (MRI) showed swelling of the left optic nerve, retrobulbar hemorrhage and proptosis by 6 mm. No foreign body was detected in the orbit. He was given massive dosis of systemic corticosteroid. The visual acuity improved to light perception immediately, to 0.1 6 days later, 0.3 10 days later and finally to 0.6. This case illustrates that recovery of visual functions is possible following systemic corticosteroid even after initial total visual loss due to injury to the optic nerve by a penetrating orbital foreign body.