Lacrimal sac incision knife

A lacrimal sac incision knife which is insertable into nasal cavity of patient, the lacrimal sac incision knife configured to incise the lacrimal sac located in the back of the nasal cavity, comprising:

• a grip portion arranged to extend in a predetermined longitudinal direction to be held by an user of the lacrimal sac incision knife,
• a shank portion connected to the grip portion, the shank portion entirely linearly extending in the longitudinal direction,
• wherein the shank portion comprises a base portion extending in the longitudinal direction and a blade portion connected to the base portion at a front end region in the longitudinal direction,
• the blade portion comprises a stabbing blade provided at the front end region in the longitudinal direction and a pair of side blades having a first side blade and a second side blade, the first side blade being formed at a first side of the blade portion in the width direction and the second side blade being formed at a second side of the blade portion in the width direction,
• the stabbing blade defines a lacrimal sac stabbing portion which can be stabbed to the lacrimal sac in a state that the grip portion is held by the user,
• one of the first side blade and the second side blade defines a first lacrimal sac incision portion which incises the lacrimal sac in a first longitudinal direction of the lacrimal sac as the lacrimal sac incision knife is operated to move in a first width direction,
• the other of the first side blade and the second side blade defines a second lacrimal sac incision portion which incises the lacrimal sac in a second longitudinal direction of the lacrimal sac, as the state is kept such that the grip portion is held by the user and as the lacrimal sac incision knife is operated to move in a second width direction,
• the blade portion has a length size of approximately from 3.0 mm to 10.0 mm in the longitudinal direction, a maximum width size of approximately from 1.0 mm to 2.0 mm in the width direction,
• the stabbing blade has a blade length size of approximately 1.0 mm to 4.0 mm in the longitudinal direction, a maximum width size of approximately from 1.0 mm to 2.0 mm in the width direction,
• the first side blade and the second side blade respectively have a blade length size of approximately 2.0 mm to 6.0 mm in the longitudinal direction,
• wherein the base portion is arranged to comprise a taper portion such that the closer to the blade portion, the gradually thinner a thickness of the taper portion becomes in the longitudinal direction and wherein a region where the first side blade and the second side blade are formed is arranged such that a thickness of this region is constant,
• wherein the taper portion is arranged to have a length in the longitudinal direction as from approximately 3.0 mm to approximately 7.0 mm,
• and wherein the taper portion is connected with the blade portion such that the thickness of the taper portion is gradually decreased from approximately 0.3 mm to approximately 0.15 mm as gel closer to the blade portion,
• and wherein the region of the blade portion where the first side blade and the second side blade are formed is arranged to have a thickness of approximately 0.15 mm in the longitudinal direction.