PROBLEM TO BE SOLVED: To prevent a blade part 6 from being carelessly inserted too much at the beginning of insertion to a cornea 35 when forming a side port 36 on the cornea 35 of an eyeball 33, to easily form a form of the side port 36 into a trapezoidal shape, and to be excellent in operability by easily setting an opening angle θ21 formed by both distal end side cutting edge parts 21 with each other to be large.SOLUTION: On both sides of a blade part 6, blade surfaces 9 are formed along cutting edges 10 crossing each other at a pointed end part 12 and extend from the pointed end part 12 to terminating end parts 19. Both cutting edges 10 are sectioned into a distal end side cutting edge part 21 and a proximal end side cutting edge part 22 by an intermediate part 20 between the pointed end part 12 and the terminating end parts 19. A line segment part 27 connecting both intermediate parts 20 with each other crosses a distal end side boundary edge 14 connecting a peak end part 13 at which opposed sides 11 to both proximal end side cutting edge parts 22 cross each other and the pointed end part 12 at which both distal end side cutting edge parts 21 cross each other, between the pointed end part 12 and the peak end part 13.COPYRIGHT: (C)2013,JPO&INPIT【解決手段】刃部6の両側には尖端部12で互いに交差するとともに尖端部12から終端部19まで延びる刃先縁10に沿う刃面9を形成している。両刃先縁10は尖端部12と終端部19との間で中間部20により先端側刃縁部21と基端側刃縁部22とに区画されている。両中間部20を互いに結ぶ線分部分27は、両基端側刃縁部22に対する対辺11が互いに交差する頂端部13と、両先端側刃縁部21が互いに交差する尖端部12とを結ぶ先端側境界縁14に対し、その尖端部12と頂端部13との間で交差している。【効果】両先端側刃縁部21が互いになす開き角度θ21を大きく設定し易いので、眼球33の角膜35にサイドポート36を形成する場合、刃部6を角膜35への挿入当初に不用意に挿入し過ぎず、そのサイドポート36の形態を台形状に形成し易くなり、操作性に優れている。【選択図】図6
