SOLUTION: Blade tips 15 are provided on both sides of a tip portion 3 of a blade body in a width direction Y, blade edges 17 extend from both blade tips 15 in an extending direction X, and openings 16, 18 are provided between both blade tips 15 and both blade edges 17 so as to open towards a tip XF of the extending direction X and a vertical direction Z. A groove 19 is provided inside a bottom face 9 that connects bith blade tips 15 and both blade edges 17 so as to open towards the openings 16, 18, the groove 19 opening towards the tip XF in the extending direction X at a tip face 12 of the bottom face 9 via an opening 20.EFFECT: Double-blade tips 15 are inserted into a trabecula in a thickness direction, and then the trabecula enters into an opening 16, 18 between the double-blade tips 15 and double-blade edges 17 to be incised by the double-blade tips 15 and the double-blade edges 17 while being guided in a circumferential direction of the trabecula, thereby smoothly enabling an incision operation of the trabecula including an implantation operation of a tip portion 3 into the trabecula. Also, a bottom face 9 allows increasing rigidity for maintaining a distance between the double-blade tips 15 and the double-blade edges 17.SELECTED DRAWING: Figure 4【解決手段】刃体の頭部３において、幅方向Ｙの両側に刃尖端１５を設けるとともに両刃尖端１５から延設方向Ｘへ刃縁１７を延設し、両刃尖端１５間及び両刃縁１７間には延設方向Ｘの先端向きＸＦ及び上下方向Ｚへ開放された開口１６，１８を設けた。両刃尖端１５間及び両刃縁１７間をつなぐ底壁９の内側には開口１６，１８に開放された溝１９を設けるとともに、底壁９の先端面１２で開口２０により溝１９を延設方向Ｘの先端向きＸＦへ開放した。【効果】線維柱帯の厚み方向への両刃尖端１５の刺入後に、線維柱帯が両刃尖端１５間及び両刃縁１７間の開口１６，１８に入り込んで線維柱帯の周方向へ案内されながら両刃尖端１５及び両刃縁１７により切開されるので、線維柱帯に対する頭部３の刺入操作を含む線維柱帯の切開作業を円滑に行うことができる。また、底壁９により両刃尖端１５間及び両刃縁１７間の間隔を維持するための剛性を高めることができる。【選択図】図４
