モデルエアーガンによる角膜障害

Corneal injury due to plastic bullet from a toy gun

　最近我々は所謂モデルエアーガンによって生じた特異な角膜外傷の1例に遭遇した．病変は中央にほぼ円形の健常部を残して，その周囲に輪状に角膜上皮の欠損を来し，隅角解離，前房出血などを生じていた．角膜病変は4日後には完全に治癒した．白色家兎眼および犬の摘出眼を用い，実験的にこの輪状角膜上皮欠損の形成機序について考察した．輪状病変の形成には射程距離，弾丸の衝突する方向，眼圧，眼球周囲構造などが関与し，角膜上皮のひずみと，ひずみを作り出す応力が重要と思われた．また輪状病変のうちでもその外側の境界部は，他の部に先行して最初に形成されると思われた．実験中は隅角解離，前房出血などの病変は生ぜず，動物眼が人眼に比して，衝撃に強いことが示された．

An 18-year-old male was hit by a plastic bullet, shot from an air-powered toy gun 20 m away, in his right cornea. The corneal lesion showed a ring-shaped epithelial defect of 4 mm in diameter with an intact central area of 2 mm in diameter. The involved eye also showed hyphema, goniodialysis, mydriasis and sluggish light reflex. The corneal lesion healed 4 days later.

We applied similar gun shots to in situ rabbit eyes and enucleated canine eyes. We could produce cor-neal lesions similar to the observed clinical case butfailed to induce other intraocular lesions. The dif-ference seemed to be due to fragility of hyman eyes as compared to animal ones.

Concerning the ring-shaped corneal lesion, the outer border of the ring seemed to form during the compression period, to be followed by formation of the inner border. The diameter of the inner border of the ring became smaller parallel with the dis-tance between the cornea and the gun, as the shorter distance would result in higher intraocular pressure at the moment of impact.

Rinsho Ganka (Jpn J Clin Ophthalmol) 41(6) : 689-692, 1987