Abstract:
A vitreous body cutter for incising a vitreous body in an eye, includes: an inner cylindrical blade which includes a first suction hole: and an outer cylindrical blade which includes a second suction hole, into which the inner cylindrical blade is slidably fitted, and which has a shape of an inner wall formed by transferring a shape of an external wall of the inner cylindrical blade by electroforming.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a vitreous body cutter for cutting a vitreous body in an eye, vitreous body surgical equipment (apparatus) equipped with the vitreous body cutter, and a method for manufacturing the vitreous body cutter.  
         [0002]     In a vitreous body cutter used in vitreous body surgery, a vitreous body of an eye is drawn by suction through a suction hole formed in a side surface in the vicinity of an extremity (a distal end) of a fixed, outer cylindrical (tubular) blade, to thus cause the vitreous body to fit into the suction hole. An inner cylindrical (tubular) blade is caused to axially reciprocate (move back and forth) with respect to the outer cylindrical blade (a guillotine type) or to rotate about its central axis (a rotary type), to thus excise the fitted vitreous body (see U.S. Pat. No. 6,514,268 (JP-A-2003-529402)).  
         [0003]     Such a vitreous body cutter requires high-precision meshing engagement between the outer cylindrical blade and the inner cylindrical blade. However, the related-art vitreous body cutter is manufactured by machining the outer and inner cylindrical blades, which poses difficulty in ensuring high-precision meshing engagement.  
       SUMMARY OF THE INVENTION  
       [0004]     A technical problem to be solved by the present invention is to provide a vitreous body cutter having an outer cylindrical cutter and an inner cylindrical cutter, between which high-precision meshing engagement is ensured; vitreous body surgical equipment having the vitreous body cutter; and a method for manufacturing the vitreous body cutter.  
         [0005]     To solve the problem, the present invention has a configuration such as that provided below.  
         [0006]     (1) A vitreous body cutter for incising a vitreous body in an eye, comprising:  
         [0007]     an inner cylindrical blade which has a first suction hole; and  
         [0008]     an outer cylindrical blade which has a second suction hole and a shape of an inner wall formed by transferring a shape of an external wall of the inner cylindrical blade by electroforming, into which the inner cylindrical blade is slidably fitted.  
         [0009]     (2) The vitreous body cutter according to (1), wherein the first suction hole is formed in a distal end of the inner cylindrical blade, and the second suction hole is formed in a distal end of the outer cylindrical blade.  
         [0010]     (3) The vitreous body cutter according to (2), wherein the distal ends of the respective cylindrical blades are formed into a shape of a curved surface.  
         [0011]     (4) The vitreous body cutter according to (2), further comprising:  
         [0012]     a drive section which rotates the inner cylindrical blade about its central axis with respect to the outer cylindrical blade.  
         [0013]     (5) Vitreous body surgical equipment comprising:  
         [0014]     the vitreous body cutter according to claim  1 ; and  
         [0015]     a suction pump which generates a suction pressure within the inner cylindrical blade.  
         [0016]     (6) The vitreous body cutter according to (5), further comprising:  
         [0017]     a sensor which is provided at a distal end of the outer cylindrical blade for detecting a distance between the distal end and a retina; and  
         [0018]     an alarm which reports a sensing result of the sensor. (7) The vitreous body cutter according to (5), further comprising:  
         [0019]     a sensor which is provided at a distal end of the outer cylindrical blade for detecting a distance between the distal end and a retina; and  
         [0020]     a control section which controls the suction pump in accordance with a sensing result of the sensor.  
         [0021]     (8) A method for manufacturing a vitreous body cutter for incising a vitreous body in an eye, comprising:  
         [0022]     producing an inner cylindrical blade;  
         [0023]     producing an outer cylindrical blade having a shape of an inner wall formed by transferring a shape of an external wall of the produced inner cylindrical blade by electroforming; and  
         [0024]     forming suction holes in the formed inner and outer cylindrical blades, respectively.  
         [0025]     (9) The manufacturing method according to (8), wherein the suction holes are formed in distal ends of the produced inner and outer cylindrical blades, respectively.  
         [0026]     (10) The manufacturing method according to (9), wherein the distal ends of the inner and outer cylindrical blades are formed into a shape of a curved surface.  
         [0027]     (11) Vitreous body surgical equipment including a vitreous body cutter for incising a vitreous body in an eye, comprising:  
         [0028]     a sensor which is provided at a distal end of the cutter and detects a distance between the distal end and a retina; and  
         [0029]     an alarm which reports a sensing result of the sensor.  
         [0030]     (12) The vitreous body surgical equipment according to (11), further comprising:  
         [0031]     a suction pump which generates a suction pressure within the cutter; and  
         [0032]     a control section which controls the suction pump in accordance with a detection result of the sensor.  
         [0033]     (13) The vitreous body surgical equipment according to (11), further comprising:  
         [0034]     a drive section which moves an inner blade of the cutter with respect to an outer blade of the cutter; and  
         [0035]     a control section which controls the drive section in accordance with a detection result of the sensor. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0036]      FIG. 1A  is a schematic side cross-sectional view showing the shape of an extremity (a distal end) of an outer cylindrical (tubular) blade according to an embodiment and the shape of the vicinity thereof;  
         [0037]      FIG. 1B  is a schematic side cross-sectional view showing the shape of an extremity (a distal end) of an inner cylindrical (tubular) blade according to an embodiment and the shape of the vicinity thereof;  
         [0038]      FIG. 2  is a schematic external view showing the inner cylindrical blade fitted into the outer cylindrical blade;  
         [0039]      FIGS. 3A and 3B  are schematic side cross-sectional views showing the inner cylindrical blade fitted in the outer cylindrical blade;  
         [0040]      FIGS. 4A and 4B  are schematic side cross-sectional views showing the inner cylindrical blade fitted in the outer cylindrical blade;  
         [0041]      FIGS. 5A, 5B , and  5 C are schematic views showing a method for manufacturing the outer and inner cylindrical blades;  
         [0042]      FIG. 6  is a schematic block diagram of vitreous body surgical equipment of the present embodiment; and  
         [0043]      FIG. 7  is a schematic side cross-sectional view showing an embodiment in which a sensor is attached to a vitreous body cutter. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0044]     An embodiment according to the present invention will be described with reference the drawings.  FIG. 1A  is a schematic side cross-sectional view of an outer cylindrical (tubular) blade  1 . The outer cylindrical blade  1  is formed into a hollow cylindrical shape having an outer diameter of about 0.7 mm to about 1.5 mm and a thickness of about 0.05 mm to about 0.2 mm (therefore an inner diameter of about 0.3 mm to about 1.4 mm) A curved (rounded) surface  2  is formed at a distal end of the outer cylindrical blade  1 . The reason for this is that consideration is taken for infliction of damage on a retina, which would otherwise be caused when the distal end of the outer cylindrical blade  1  comes into contact with the retina. As a matter of course, it may be the case that the curved surface  2  is not formed.  
         [0045]     An opening  3  is formed in the distal end of the outer cylindrical blade  1  by cutting a portion of the curved surface  2 . This opening  3  is a suction hole for drawing a vitreous body into the outer cylindrical blade  1  by suction, and an edge  3   a  on an interior-wall-side of the opening  3  acts as an outer blade. The shape of the interior wall of the outer cylindrical blade  1  essentially coincides with the shape of an external wall of an inner cylindrical (tubular) blade  10  to be described later.  
         [0046]      FIG. 1B  is a schematic side cross-sectional view of the inner cylindrical blade  10  housed in the outer cylindrical blade  1 . The inner cylindrical blade  10  is fitted into the outer cylindrical blade  1  and retained (held) so as to be rotatable. The inner cylindrical blade  10  is formed into a hollow cylindrical shape whose outer diameter essentially coincides with the inner diameter of the outer cylindrical blade  1  (a clearance of micrometers to tens of micrometers exists between the inner wall of the outer cylindrical blade  1  and the external wall of the inner cylindrical blade  10 ).  
         [0047]     A curved (round) surface  11  substantially coinciding with the inner wall of the curved surface  2  of the distal end of the outer cylindrical blade  1  is formed at the distal end of the inner cylindrical blade  10 . An opening  12  is formed in the distal end of the inner cylindrical blade  10  by cutting a portion of the curved surface  11 . This opening  12  is a suction hole for drawing a vitreous body into the inner cylindrical blade  10  by suction, and an edge  12   a  on the external wall-side of the opening  12  acts as an inner blade.  
         [0048]     A suction device and a rotary drive device are provided on a base-end-side of the inner cylindrical blade  10 , and the inner cylindrical blade  10  is rotated about its central axis within the outer cylindrical blade  1 . The vitreous body is drawn into a suction path  13  in the inner cylindrical blade  10   b  by suction through the opening  3  and the opening  12  (which will be described in detail later).  
         [0049]      FIG. 2  is a schematic external view showing the inner cylindrical blade  10  fitted into the outer cylindrical blade  1 . The vitreous body cutter of the present embodiment incises a vitreous body by rotating (rotationally moving) the inner cylindrical blade  10  with respect to the outer cylindrical blade  1  between a state where the opening  3  and the opening  12  overlap each other (an open state where the opening  12  can be seen through the opening  3 ) and a state where they do not overlap each other (a closed state where the opening  12  is not visible through the opening  3 ). When the opening  3  and the opening  12  overlap each other as shown in  FIG. 2 , the vitreous body is drawn into the suction path  13  in the inner cylindrical path  10  by suction.  
         [0050]      FIG. 3A  is a schematic side cross-sectional view showing that the inner cylindrical blade  10  is fitted in the outer cylindrical blade  1  and that the opening  3  and the opening  12  overlap each other.  FIG. 4A  is a schematic side cross-sectional view along direction A shown in  FIG. 3A .  FIG. 3B  is a schematic side cross-sectional view showing that that the opening  3  and the opening  12  do not overlap each other.  FIG. 4A  is a schematic side cross-sectional view along direction B shown in  FIG. 3B . As mentioned previously, when the opening  12  overlaps the opening  13 , the vitreous body is drawn into the suction path  13  by suction through the openings  3  and  12 . When the opening  12  does not overlap the opening  3  as a result of rotation of the inner cylindrical blade  10  within the outer cylindrical blade  1 , the vitreous body is incised by meshing engagement between the edge  3   a  and the edge  12   a.    
         [0051]     The shape of the inner wall of the outer cylindrical blade  1  essentially coincides with the shape of the outer wall of the inner cylindrical blade  10 . When the inner cylindrical blade  10  is fitted into the outer cylindrical blade  1 , the blades can be fitted together without involvement of any substantial clearance between the blades (only a clearance sufficient for rotation exists). Consequently, the accuracy of meshing engagement between the edge  3   a  and the edge  12   a  is greatly enhanced, so that the vitreous body can be incised without excess labor.  
         [0052]     A method for manufacturing such an outer cylindrical blade  1  and such an inner cylindrical blade  10  will now be described with reference to  FIGS. 5A  to  5 C. First, the distal end of a pipe material which is of a size (has inner and outer diameters) suitable for use as the inner cylindrical blade  10  and is formed from metal (for example, stainless) is closed in advance by electrode position, welding or the like. Next, the distal end is formed into the curved surface  11  by cutting with a cutting tool or grinding with a grindstone. As a result, as shown in  FIG. 5A , a metal matrix  100  which is to be formed into the inner cylindrical blade  10  is obtained.  
         [0053]     As shown in  FIG. 5B , the metal matrix  100  is placed as a cathode in an electrolyte for electroforming, which is made of nickel sulfamic acid solution, or the like, and a sulfur-containing nickel plate  101  is used as an anode. A predetermined voltage is applied across electrodes from a power source, to thus deposit nickel on the surface of the metal matrix  100 . At this time, deposition of nickel is controlled by means of the voltage to be applied and an application time, so that nickel is deposited on the surface of the metal matrix  100  to a thickness required for the outer cylindrical blade  1  (a thickness of essentially 0.05 mm to 0.2 mm in the embodiment). The metal matrix  100  is rotated within the electrolyte such that nickel is deposited to as uniform a thickness as possible over the overall metal matrix  100 . Any rotational speed is allowable, so long as nickel is uniformly deposited over the entire metal matrix  100 . For instance, the rotational speed is set so as to fall within a range of about 10 rpm to about 200 rpm.  
         [0054]     When a nickel cylinder  102  formed from the metal matrix  100  with nickel deposited thereon is obtained by means of such an electroforming method, the metal matrix  100  having the nickel cylinder  102  is taken out of the electrolyte. Subsequently, as shown in  FIG. 5C , the metal matrix  100  is released from the nickel cylinder  102 . In this case, for instance, it is better to leave the nickel cylinder  102  in contact with a stopper  103 , and to withdraw the metal matrix  100  away from the nickel cylinder  102 . As a result, the shape of the outer wall of the metal matrix  100  which is to become the inner cylindrical blade  10  is transferred as the shape of the inner wall of the nickel cylinder  102  which is to become the outer cylindrical blade  1 .  
         [0055]     Next, the opening  3  is formed by cutting a portion of the distal end of the nickel cylinder  102  with an end mill or the like. At this time, the distal end of the end mill is not brought into contact with the curved surface  2  of the nickel cylinder  102 , but is brought into contact at right angles to the nickel cylinder  102 . In this state, the side wall (body) of the end mill cuts the curved surface  2  of the nickel cylinder  102  (cutting is performed such that the axis of the nickel cylinder  102  forms right angles with the axis of the end mill). As a result, the edge  3   a  on the inner-wall-side of the opening  3  is formed acutely and acts as the outer blade. A machining method other than that described above may also be employed, so long as the method enables formation of the opening  3  having the acute edge  3   a . For instance, a plurality of nickel cylinders  102  are arranged in a line, and a rotary grindstone is pressed against the nickel cylinders  102  such that the rotating direction of the grindstone becomes perpendicular to the axial direction of each of the nickel cylinders  102 , to thus grind portions of the distal ends of the nickel cylinders  102 . As a result, the openings  3 , each having the acute edge  3   a , are formed. The grindstone used for forming the openings  3  preferably has a curved grinding surface to be used for forming the edge  3   a.    
         [0056]     The outer cylindrical blade  1  is obtained by polishing the inner and outer walls of the nickel cylinder  102 .  
         [0057]     The opening  12  can also be formed by cutting a portion of the distal end of the metal matrix  100  with the end mill or the like. At this time, the distal end of the end mill is brought into contact with the curved surface  11  of the metal matrix  100 , to thus cut the surface. As a result, the edge  12   a  on the external wall-side of the opening  12  is formed acutely, and acts as an inner blade. Any other method may be employed, so long as the method enables formation of the opening  12  having the acute edge  12   a . For instance, it may be a case that the opening  12  is formed before performance of machining involving usage of the end mill, by electric discharge machining, and only finishing of the thus-machined opening is performed through use of the end mill.  
         [0058]     The inner cylindrical blade  10  is obtained by polishing the inner and external walls of the metal matrix  100 .  
         [0059]     In general, when the hollow, cylindrical external wall is machined, precision machining can be performed by cutting or grinding. However, in the case of machining of an inner wall, a highly-versatile machining method or measurement means is not available, and ensuring desired dimensional accuracy is highly difficult. However, in the present embodiment, the shape of the inner wall of the outer cylindrical blade  1  can be formed with high accuracy in conformance with the shape of the external wall of the inner cylindrical blade  10 . Consequently, accuracy of meshing engagement between the outer cylindrical blade  1  (outer blade) and the inner cylindrical blade  10  (inner blade) becomes extremely high. Hence, sharp cutting can be performed even at the distal end of the cutter.  
         [0060]     The schematic configuration of the vitreous body cutter using the outer cylindrical blade  1  and the inner cylindrical blade  10  and that of the vitreous body surgical equipment are shown in  FIG. 6  and will now be described. The outer cylindrical blade  1  is secured to a housing  21  of the vitreous body cutter  20 , which is a handpiece. The inner cylindrical blade  10  is fitted in the outer cylindrical blade  1  so as to be rotatable about the central axis of the inner cylindrical blade. The base end of the inner cylindrical blade  10  has been closed in advance by welding, electrode position, or the like. A motor  23  fixed in the housing  21  is connected to the base end via a joint member  22 . The motor  23  is electrically connected to a control section  30  of the equipment main body through a cable  26  and rotationally driven in accordance with a control signal from the control section  30 . A delivery hole  10   a  which connects the suction path  13  to a suction chamber  24  provided in the housing  21  is formed in a sidewall of the inner cylindrical blade  10 . The suction chamber  24  is connected to a suction pump  31  of the equipment main body through a tube  25 , and suction pressure for drawing the vitreous body V by suction develops in the suction path  13  by driving of the suction pump  31 .  
         [0061]     The equipment main body is roughly divided into the control section  30  for driving and controlling the entire piece of equipment, the suction pump  31  for generating the suction pressure for drawing the vitreous body V by suction, a waste (waste fluid) bag  32 , a foot switch  33  for issuing a signal for activating the cutter  20  and the suction pump  31 , and a setting panel  34  for setting various surgical conditions. The control section  30  drives and controls the motor  23  and the suction pump  31  on the basis of the signal output from the foot switch  33  or the settings of the setting panel  34 .  
         [0062]     Operation of the vitreous body surgical equipment having such a configuration will now be described. First, with switches of the setting panel  34 , surgical conditions (e.g., a suction pressure, a cutting speed of the cutter  20 , and the like) are set. Next, a perfusion liquid from an unillustrated perfusion liquid bottle is introduced into an eye of a patient. Moreover, the outer cylindrical blade  1  of the cutter  20  is inserted into the eye such that the opening  3  is situated at a diseased area, such as an opaque area. Subsequently, the foot switch  33  is stepped on, to thus activate the cutter  20  (the motor  23 ) and the suction pump  31  at a preset cutting speed and a preset suction pressure.  
         [0063]     The motor  23  rotates the inner cylindrical blade  10  forward and in reverse while maintaining the preset cutting speed. Forward and rearward rotation of the inner cylindrical blade  10  is for preventing involvement of the vitreous body V. When the inner cylindrical body  10  rotates about its central axis and the opening  3  and the opening  12  overlap each other, the vitreous body V is drawn into the suction path  13  by suction through the opening  3  and the opening  12 . The inner cylindrical blade  10  rotates further, whereby the opening  3  and the opening  12  do not overlap each other. As a result, the vitreous body V is incised by meshing engagement between the edge  3   a  and the edge  12   a . The thus-incised vitreous body V is drawn by suction and delivered to the suction chamber  24  by the suction pressured generated by the suction pump  31 , through the suction path  13  and the delivery hole  10   a . The vitreous body is further discharged to the waste bag  32  through the tube  25 .  
         [0064]     In the foregoing embodiment, the inner cylindrical blade  10  is arranged to rotate forward and in reverse about its central axis. However, the essential requirement is to be able to bring the opening  3  of the outer cylindrical blade  1  into the open state and the closed state by rotational movement of the inner cylindrical blade  10 . For instance, the inner cylindrical blade  10  may be rotated in a single direction about its central axis.  
         [0065]     Although in the present embodiment, the inner cylindrical blade  10  is rotated by the motor  23 , the inner cylindrical blade  10  may be rotated by providing a mechanism for converting linear motion into rotational motion or through use of air pressure originating from a compressor pump, a solenoid valve, or a diaphragm. A part of the drive mechanism for rotating the inner cylindrical blade  10  may be provided on the equipment main body.  
         [0066]     In the embodiment, in order to efficiently incise the vitreous body located close to a retina, the opening  3  is provided in the distal end of the outer cylindrical blade  1 , and the opening  12  is provided in the distal end of the inner cylindrical blade  10 . However, needless to say, the present invention can be applied to a vitreous body cutter having an opening in a side surface in the vicinity of the distal end of an outer cylindrical blade, with a view toward enhancing the meshing accuracy between the outer cylindrical blade and the inner cylindrical blade. In this case, the inner cylindrical blade may be axially reciprocated (moved back and forth) with respect to the outer cylindrical blade.  
         [0067]     By providing the cutter  20  with a function for detecting and reporting a distance between the distal end of the cutter and the retina, suction of the retina or infliction of damage on the retina, which would otherwise be caused when the cutter  20  approaches too close to the retina, can be prevented.  FIG. 7  is a schematic side cross-sectional view showing an embodiment in which a sensor  200  is provided on the vitreous body cutter  20  for detecting a distance between the distal end of the cutter  20  and a retina. The sensor  200  detects a distance by transmitting an ultrasonic signal or an optical signal and receiving a reflected signal. As illustrated, the sensor  200  is disposed on the distal end of the cutter  20  (the outer cylindrical blade  1 ).  
         [0068]     In the cutter  20  having such a configuration, a signal to be received by the sensor  200  is always monitored by the control section  30 . When the level of the received signal has reached a predetermined value or more, the control section  30  displays reaching of the predetermined value on a display of the setting panel  34  or issues an alarm sound, thereby informing the user of approach of the cutter  20  to a predetermined distance. Further, the control section  30  may suppress drawing of the retina, by weakening the suction force generated by the suction pump  31  or stop rotation of the inner cylindrical blade  10 .  
         [0069]     An unillustrated cable for electrically connecting the sensor  200  to the control section  30  can also be embedded in the wall of the outer cylindrical blade  1  (caused to adhere to the wall of the outer cylindrical blade  1 ) through use of the foregoing electroforming technique. When the cable is embedded in the wall of the outer cylindrical blade  1 , electroforming is temporarily suspended when the wall has been formed to a certain thickness during the course of formation of the nickel cylinder  102  shown in  FIG. 5B , and the cable sheathed with insulating material is laid on the nickel cylinder  102 . Nickel is then deposited to a predetermined thickness by again using electroforming. At this time, the tip end of the cable to be connected to the sensor  200  is preferably covered in advance with a protective member or the like, so that the deposited nickel can be readily removed.  
         [0070]     When deposition of nickel on the sheathed cable and embedding the cable in the wall of the outer cylindrical blade  1  are difficult, an insulation portion of the cable to be sheathed may be plated beforehand with nickel or the like. Although the cable is connected to the sensor  200  after the cable and the outer cylindrical blade  1  have been integrated beforehand, it may be a case that the sensor  200  and the cable, being connected together, are previously provided on the outer cylindrical blade  1 , and that only the cable is embedded in the wall of the outer cylindrical blade  1  through use of the foregoing electroforming process.