Cannula

Abstract

A cannula includes a hollow cylindrical body which is open at one end and closed at the other end. A slot extends from the open end toward the closed end, terminating with an opening that is larger in width than the slot, the width being measured in a direction perpendicular to the longitudinal direction in which the slot extends. The opening allows the passage of a guide wire for relative sliding. The configuration of the cannula is such that the end of the wire coming out of the cannula through the opening cannot, once inserted into the openings, penetrate into the part of the cannula beyond the opening between the latter and the closed end of the cannula.

What is claimed is: 
     
         1 . Cannula designed to be inserted into tear ducts for receiving a wire connected to a probe that is to be inserted into the tear duct, the wire being guided into the cannula so as to traverse the tear duct in this way up to the exit of the latter on the side of the nasal cavity, the surgeon then removes the cannula through the other exit of the duct (from the side of the eyes) then pulling the wire to guide the probe into position in the tear duct, the cannula comprising an oblong, hollow cylindrical body open at one end and closed at its other outer end, a lateral slot extending from the open end towards the closed outer end ending with a lateral opening with a larger width dimension than the slot, the width being measured in a direction perpendicular to the longitudinal direction along which the slot extends, the opening allowing the passage within it of the guide wire introduced through the opening of the open end into the cylindrical hollow body for relative sliding by pulling the cannula and the guide wire, characterised in that the form and the dimension of the cannula are such that the guide wire, in particular its free end designed to come out of the cannula through the opening, cannot, once inserted into the cannula through the opening of the open end, penetrate into the part of the cannula beyond the opening between the latter and the closed outer end of the cannula. 
     
     
         2 . Cannula according to  claim 1 , characterised in that the spacing between the end of the opening in the longitudinal direction towards the closed outer end and the closed outer end is solid such that the inner base of the cannula is located substantially at the end of the opening. 
     
     
         3 . Cannula according to  claim 1 , characterised in that the cannula comprises an inner wall forming the base of the cannula which closes the space between the end of the opening in the direction of the closed outer end and said closed outer end. 
     
     
         4 . Cannula according to  claim 3 , characterised in that the inner wall of the base of the cannula, which is located substantially at the end of the opening in longitudinal direction towards the outer closed end, forms an angle of less than 90°, in particular between 15 and 30°, with the longitudinal axis, to thus form a guide ramp to the top, that is towards the opening, for the end of the wire which is slid into the cannula by pushing it through the opening of the cannula. 
     
     
         5 . Ritleng type system comprising a cannula according to  claim 1 , and an intubation probe comprising at least one part in the form of a tube ( 9 ) made of a biocompatible flexible material, in particular made of silicone, designed to be connected to a guide wire ( 7 ), in particular made of prolene, one end ( 16 ) of which for joining together the probe and the wire, is introduced into the tube through an opening ( 22 ) of the latter, characterised in that the tube comprises a section ( 24 ), from the side of the opening ( 22 ) of the tube through which the end of the wire is introduced into the tube, having a bevelled form, the exterior diameter of the tube, along the section ( 24 ), increasing from the opening ( 22 ). 
     
     
         6 . System according to  claim 5 , characterised in that the tube of the probe comprises a section, from the side of the opening of the tube through which the end of the wire is introduced into the tube, having a bevelled form, the exterior diameter of the tube, along the section, increasing from the opening. 
     
     
         7 . System according to  claim 5 , characterised in that the thickness of the tube increases from the opening of the tube along the bevelled section and then is constant thereafter.