JOHNNY-POPPERS - A CAUSE OF SERIOUS OCULAR INJURY

Aims/background-The causes of blunt ocular trauma are many and diverse . We present two cases of ocular injury caused by an unusual form of w eapon called a ''Johnny Popper''. There follows a theoretical and expe rimental evaluation of the velocity of the projectiles fired by this d evice. Methods-A Johnny Popper was constructed under expert guidance. The elastic properties of the device were measured and this allowed ca lculation of a theoretical exit velocity of the projectiles fired. The weapon was subsequently fired under test conditions which permitted t he exit velocity of the projectiles fired to be measured directly. Res ults-The theoretical velocity of the projectiles was calculated as 80 ms(-1) and the experimentally measured velocity was 57 ms(-1). Conclus ions-Johnny Poppers are a previously undescribed and unique form of ho me made weapon. They are intended for playful mischief, but have the p otential to cause serious ocular trauma.