Crushed chip

Abstract

To provide a crushed chip capable of efficiently crushing and sucking ocular tissue while suppressing complication due to displacement of an axial direction intermediate part and damage of the tissue to be protected.SOLUTION: A shaft part 10 is cylindrical and forms a suction route 11 inside. A central shaft of the shaft part 10 matches a rotary shaft R. A crushing part 20 is cylindrical, and is connected to an end part of the shaft part 10 with the central axis matching the rotary shaft R. When the crushing part 20 is seen from an end side of the rotary shaft R, a shape of an annular opening 30 in the crushing part 20 is provided with bent corners 31 in four corners and formed into a rectangular shape including linear parts in each of the pair of long sides 34A, 34B and a pair of short sides 33A, 33B. An end surface of the opening 30 of the crushing part 20 tilts to a surface vertical to the rotary shaft R, so that one short side 33A of the pair of short sides 33A, 33B is located on an end side of the other short side 33B.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a disruption tip that disrupts ocular tissue by applying ultrasonic vibrations thereto. [Background technology]

[0002] For example, a homogenizing tip is used when crushing and aspirating ocular tissue such as a cloudy cataract-caused lens. The homogenizing tip crushes the ocular tissue using ultrasonic vibrations. The crushed and emulsified ocular tissue is then aspirated through a suction path within the homogenizing tip.

[0003] When performing surgery using a crushing tip, it is desirable to have a large crushing force for crushing ocular tissue. For example, the crushing tip described in Patent Document 1 comprises a shaft and a crushing part. The shaft is formed in a cylindrical shape with the rotation axis as the central axis. The crushing part is bent relative to the shaft in the direction of an inclined axis that intersects with the rotation axis and is connected to the tip of the shaft. By bending the crushing part at the tip relative to the rotation axis, torsional vibrations are generated in the crushing part around the rotation axis in addition to forward and backward vibrations along the rotation axis. This aims to increase the crushing force compared to a crushing tip (straight tip) that is formed in a straight line to the tip. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-84168 Summary of the Invention [Problem to be solved by the invention]

[0005] As described in Patent Document 1, when the distal end of the fragmentation section is bent relative to the rotation axis, the displacement volume of the fragmentation section farther from the rotation axis increases, thereby increasing the fragmentation force. On the other hand, when the distal end of the fragmentation section is bent relative to the rotation axis, the center of gravity of the fragmentation section moves away from the rotation axis, resulting in a greater torsional movement of the entire fragmentation tip. As a result, bending occurs in the axially intermediate portion of the fragmentation tip, causing lateral displacement, increasing the likelihood of complications (e.g., iris depigmentation, thermal injury, etc.). Furthermore, if the distal end of the fragmentation section has a sharp edge, it is more likely to injure tissues that need to be protected (e.g., the lens capsule). Conventional techniques have been difficult to efficiently fragment and aspirate ocular tissue while minimizing complications due to displacement in the axially intermediate portion and damage to tissues that need to be protected.

[0006] A typical object of the present disclosure is to provide a fragmentation tip that can efficiently fragment and aspirate ocular tissue while suppressing complications due to displacement of the axial intermediate portion and damage to tissue that needs to be protected. [Means for solving the problem]

[0007] A typical embodiment of the present disclosure provides a disruption tip that disrupts eye tissue by applying ultrasonic vibrations to it, and includes: a cylindrical shaft portion that forms a suction path inside and whose central axis coincides with the rotation axis of the disruption tip; and a cylindrical disruption part that is connected to the tip of the shaft portion with its central axis coincident with the rotation axis and that forms a suction path inside together with the shaft portion. When the disruption part is viewed from the tip side of the rotation axis, the shape of the annular opening of the disruption part is formed into a rectangle with curved corners at all four corners and including straight portions on each of a pair of long sides and a pair of short sides, and the tip surface of the opening of the disruption part is inclined with respect to a plane perpendicular to the rotation axis, so that one of the pair of short sides on the tip surface is located closer to the tip than the other short side.

[0008] According to the fragmentation tip of the present disclosure, ocular tissue is efficiently fragmented and aspirated while preventing complications due to displacement of the axial intermediate portion and damage to tissue that needs to be protected. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a right side view (partial cross-sectional view) of the US handpiece 2 to which the fracturing tip 1 is attached. [Figure 2] 1 is a perspective view of the vicinity of the tip of the sleeve 6 into which the crushing tip 1 is inserted, viewed from diagonally above right. [Figure 3] FIG. 2 is a perspective view of the crushing tip 1 as seen from diagonally above to the right. [Figure 4] FIG. 2 is a perspective view of the vicinity of the tip of the crushing tip 1, seen from diagonally above right. [Figure 5] 1 is a view of the vicinity of the tip of the crushing tip 1 as seen from the tip side of the rotation axis R. FIG. [Figure 6] This is a graph showing the results of simulating the displacement volume (movement volume) of the crushing section by changing the radius of curvature of the corners of the opening and the ratio of the width of the long side to the width of the short side of the opening. [Figure 7] 10 is a graph showing the results of simulating the suction port area at the tip of the opening by changing the radius of curvature of the corner of the opening and the ratio of the width in the long side direction to the width in the short side direction of the opening. [Figure 8] 10 is a graph showing the results of simulating the amplification factor in the crushing section of the vibrations applied to the crushing tip from the US handpiece by changing the weight of the crushing tip. [Figure 9] 10 is a graph showing the results of simulating the amplification factor in the crushing section of the vibration applied to the crushing tip from the US handpiece by changing the length of the crushing tip. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Summary> The crushing tip exemplified in the present disclosure comprises a shaft portion and a crushing portion. The shaft portion is cylindrical and forms a suction path therein. The central axis of the shaft portion coincides with the rotation axis of the crushing tip. The crushing portion is cylindrical and is connected to the tip portion of the shaft portion with its central axis coincident with the rotation axis. The crushing portion, together with the shaft portion, forms a suction path therein. When the crushing portion is viewed from the tip side of the rotation axis, the shape of the annular opening in the crushing portion is formed into a rectangle with curved corners at the four corners and with straight portions on each of a pair of long sides and a pair of short sides. The tip surface of the opening of the crushing portion is inclined with respect to a plane perpendicular to the rotation axis, so that one of the pair of short sides on the tip surface is located closer to the tip than the other short side.

[0011] In the crushing tip exemplified in the present disclosure, the central axis of the crushing part coincides with the rotation axis of the crushing tip. In other words, the crushing part at the tip is not bent relative to the rotation axis, and the central axis of the crushing part is not deviated from the rotation axis (when viewed from the tip side of the rotation axis, the crushing part is formed rotationally symmetrically around the rotation axis). Therefore, compared to when the crushing part is bent relative to the rotation axis, torsional movement of the entire crushing tip is suppressed. As a result, problems such as complications due to displacement of the axial middle part are suppressed.

[0012] On the other hand, when the crushing unit is viewed from the tip of the rotating shaft, the annular opening in the crushing unit is formed in a rectangular shape. Therefore, compared to when the opening is formed in a circular or square shape when viewed from the tip, the area away from the rotating shaft is more likely to increase, and the displacement volume when the crushing unit rotates around the rotating shaft is more likely to increase. In particular, the displacement volume at the four corners of the opening is larger. As a result, the crushing force is more likely to be improved.

[0013] Furthermore, in the fracturing tip of the present disclosure, the distal end surface of the opening of the fracturing section is inclined with respect to a plane perpendicular to the rotation axis, so that one of the pair of short sides of the distal end surface is located closer to the distal end than the other short side. In this case, the short side located closest to the distal end (hereinafter referred to as the "tip-side short side") is the part that is most likely to come into contact with the tissue to be protected. However, since the tip-side short side also includes a straight portion, the shape of the tip-side short side is prevented from becoming sharp compared to when the tip-side short side is curved and protrudes in a direction away from the rotation axis. Therefore, the fracturing tip of the present disclosure can efficiently fracturize ocular tissue while suppressing complications due to displacement of the axial intermediate portion and damage to the tissue to be protected.

[0014] The straight line portions included in each of the pair of long sides and the pair of short sides do not have to be strictly straight lines. For example, as long as the straight line portions of each of the four sides form an approximately rectangular opening, at least one of the straight line portions may be slightly curved.

[0015] When the crushing section is viewed from the tip of the rotating shaft, the length of the straight line portion included in the short side of the opening may be 22% or more of the width of the opening in the short side direction, which appropriately reduces the possibility of damaging the tissue to be protected.

[0016] The homogenizing tip may be used in a state where it is inserted inside a sleeve. The sleeve is a tubular member that forms a flow path for the perfusion fluid inside. The sleeve has an insertion hole at the most distal end through which the homogenizing tip is inserted, and a perfusion fluid passage hole formed on the side surface rearward of the insertion hole. The outer periphery of the cross section perpendicular to the rotation axis (hereinafter referred to as the "vertical cross section") of the opening of the homogenizing part that passes through the insertion hole of the sleeve may be 3.2 mm or less.

[0017] Increasing the perimeter of the vertical cross section of the opening of the homogenizer increases the area of ​​the entrance to the suction path at the tip of the opening, thereby increasing the holding power of the tissue to be homogenized. On the other hand, the size of the sleeve through which the homogenizer tip is inserted is limited to minimize the incision required for inserting the homogenizer tip and sleeve into the eye. Therefore, if the perimeter of the vertical cross section of the opening of the homogenizer is too large, the shape of the irrigation fluid passage holes formed on the side of the sleeve will be distorted, increasing the possibility of obstructing the flow of irrigation fluid. Therefore, by setting the perimeter of the vertical cross section of the opening of the homogenizer to 3.2 mm or less, ocular tissue can be efficiently homogenized and aspirated without obstructing the flow of irrigation fluid.

[0018] When the crushing part is viewed from the tip side of the rotary shaft, the ratio of the width in the long side direction to the width in the short side direction of the rectangular opening of the crushing part may be 1.25 to 1.75.

[0019] We investigated the case where the ratio of the long side width to the short side width was varied while keeping the perimeter of the vertical cross section of the opening constant. The larger the ratio of the long side width to the short side width, the greater the displacement volume when the crushing unit rotates around the rotation axis, thereby improving the crushing force. On the other hand, the smaller the ratio of the long side width to the short side width, the greater the area of ​​the entrance to the suction path at the tip of the opening, thereby increasing the holding force of the tissue to be crushed. The inventors of the present invention conducted simulations to determine the appropriate ratio of the long side width to the short side width in order to achieve both crushing force and holding force (details will be described later). As a result, it was newly discovered that both crushing force and holding force can be achieved by setting the ratio of the long side width to the short side width of the opening to 1.25 to 1.75.

[0020] When the crushing part is viewed from the tip side of the rotary shaft, the radius of curvature of each of the four corners of the rectangular opening in the crushing part may be 0.25 mm or less.

[0021] The smaller the radius of curvature of each of the four corners of the rectangular opening in the crushing section, the greater the displacement volume when the crushing section rotates around the rotation axis, thereby improving the crushing force. Therefore, by setting the radius of curvature of each of the four corners of the opening to 0.25 mm or less, sufficient crushing force can be easily ensured.

[0022] When the crushing part is viewed from the tip side of the rotary shaft, the radius of curvature of each of the four corners of the rectangular opening in the crushing part may be 0.15 mm to 0.25 mm.

[0023] We consider the case where the perimeter of the vertical cross section of the opening is kept constant, and the curvature radius of each of the four corners of the rectangular opening in the crushing section is changed. As mentioned above, the smaller the curvature radius of each of the four corners of the rectangular opening in the crushing section, the greater the displacement volume when the crushing section rotates around the rotation axis, thereby improving the crushing force. On the other hand, when the perimeter of the vertical cross section of the opening is kept constant, the larger the curvature radius of the four corners of the opening, the greater the area of ​​the entrance to the suction path at the tip of the opening, thereby increasing the holding force of the tissue to be crushed. The inventors of the present invention conducted simulations to determine the conditions for the curvature radius of the four corners of the opening to achieve both crushing force and holding force (details will be described later). As a result, it was newly discovered that both crushing force and holding force can be achieved by setting the curvature radius of the four corners of the opening to 0.15 mm to 0.25 mm.

[0024] The crushing tip is used while attached to the distal end of a US handpiece. The US handpiece applies ultrasonic vibrations to the crushing tip. The amplitude of the vibrations applied to the crushing tip from the US handpiece is amplified in the crushing section at the distal end of the crushing tip. Here, if the amplitude of the vibrations in the crushing section is too small, the crushing force will be insufficient. On the other hand, if the amplitude of the vibrations in the crushing section is too large, the crushing tip will be easily damaged. In order to ensure an appropriate crushing force while preventing damage to the crushing tip, it is desirable to set the amplification factor of the vibrations applied to the crushing tip from the US handpiece in the crushing section to 3 to 4 times.

[0025] The inventors of the present invention conducted simulations (described in detail below) to determine the desirable weight of a crushing tip having the configuration of the present disclosure in order to satisfy the above-mentioned condition (condition for an amplification factor of 3 to 4 times). As a result, it was newly discovered that by setting the total weight of the crushing tip to 0.146 g to 0.165 g, the amplification factor becomes 3 to 4 times, and both the suppression of breakage of the crushing tip and the securing of crushing force can be achieved.

[0026] The inventors of the present invention conducted simulations (details will be described later) to determine the desirable length (the length from the tip of the detachable part to the tip of the crushing part) of the crushing tip having the configuration of the present disclosure in order to satisfy the above-mentioned condition (condition of 3 to 4 times the amplification factor). As a result, it was newly discovered that by setting the length of the crushing tip to 24.4 mm to 25.6 mm, the amplification factor becomes 3 to 4 times, and both the suppression of breakage of the crushing tip and the securing of crushing force are achieved.

[0027] <Embodiment> (US handpiece) A typical embodiment of the present disclosure will be described below with reference to the drawings. First, a US handpiece 2 to which a fragmentation tip 1 of this embodiment is attached will be described with reference to Figures 1 and 2. The US handpiece 2 applies ultrasonic vibrations to the fragmentation tip 1 attached to the distal end side, thereby fragmenting and emulsifying ocular tissue (in this embodiment, the nucleus of the patient's lens, which has become cloudy due to cataracts), and then aspirating and removing the fragmented ocular tissue.

[0028] As shown in FIG. 1, the US handpiece 2 includes a handpiece body 3 and a sleeve 6. The handpiece body 3 includes a horn 4 and a suction path 5. A lithotriptor tip 1 is detachably attached to the tip of the horn 4. The horn 4 amplifies ultrasonic vibrations generated by a vibrator (not shown) and transmits them to the lithotriptor tip 1 attached to the tip. The suction path 5 extends from the tip of the horn 4 through the interior and toward the rear end. When the lithotriptor tip 1 is attached to the tip of the horn 4, the suction path 5 of the handpiece body 3 is connected to the suction path 11 of the lithotriptor tip 1 (see FIG. 3). The ocular tissue lithotriptor tip 1 and the irrigation fluid (e.g., saline solution) supplied into the eye are sucked from the inside of the eye toward the proximal end through the suction path 5 by suction force generated by a suction device (not shown).

[0029] As shown in FIG. 2, the sleeve 6 is tubular (e.g., cylindrical) and detachably attached to the distal end of the handpiece body 3 (see FIG. 1). The sleeve 6 is made of a material such as silicone resin with appropriate flexibility. The interior of the tubular sleeve 6 serves as a flow path for the irrigation fluid. The homogenization tip 1 is inserted into the tubular sleeve 6 during use. The sleeve 6 has an insertion hole 7 and an irrigation fluid passing hole 8. The insertion hole 7 is formed at the distal end of the tubular sleeve 6. During surgery, the sleeve 6 covers the proximal end of the homogenization tip 1 with the distal end of the homogenization tip 1 exposed distally from the insertion hole 7. The irrigation fluid passing hole 8 is formed on the side of the tubular sleeve 6, closer to the rear end than the insertion hole 7. Although not shown, the sleeve 6 of this embodiment has an irrigation fluid passing hole 8 on the front right side of FIG. 2 as well as a similar irrigation fluid passing hole on the rear left side. The irrigation fluid that flows through the flow path in the sleeve 6 from the rear end side (base end side) to the tip side is supplied to the outside of the sleeve 6 through the irrigation fluid passing hole 8.

[0030] (Crushed chips) The configuration of the disruption tip 1 of this embodiment will be described. As shown in FIG. 3, the disruption tip 1 comprises a shaft portion 10 and a disruption portion 20. The shaft portion 10 has a tubular (typically cylindrical) shape. That is, the shaft portion 10 is a hollow thin tube extending linearly. The central axis of the tubular shaft portion 10 coincides with the rotation axis R of the disruption tip 1. When ultrasonic vibration is applied to the disruption tip 1, the shaft portion 10 rotates back and forth within a predetermined angle range around the rotation axis R. The cross-sectional shape of the shaft portion 10 of this embodiment, which is perpendicular to the rotation axis R, is symmetrical with respect to the rotation axis R. Therefore, even if torsional vibration occurs in the disruption tip 1, water pressure from the perfusion fluid is unlikely to be applied to the shaft portion 10.

[0031] Inside the cylindrical shaft 10, a suction path 11 (see Figures 3 and 4) is formed through which the ocular tissue crushed by the crushing unit 20 and the irrigation fluid supplied into the eye pass. As shown in Figure 3, a detachable part 12 is formed at the base end of the shaft 10, which detachably attaches the crushing tip 1 to the tip of the horn 4 (see Figure 1) of the US handpiece 2. The suction path 11 communicates from the detachable part 12 on the base end side to the tip end.

[0032] As shown in Figures 2 to 5, the crushing part 20 has a cylindrical shape. The crushing part 20 is connected (fixed) to the tip of the shaft part 10. The cylindrical crushing part 20, together with the shaft part 10, forms a suction path 11 inside. The central axis of the crushing part 20 in this embodiment coincides with the rotation axis R of the crushing tip 1. In other words, the crushing part 20 is not bent with respect to the rotation axis R, and the central axis of the crushing part 20 is not deviated from the rotation axis R (when viewed from the direction of the rotation axis R, the crushing part 20 is formed rotationally symmetrically around the rotation axis R). Therefore, compared to when the crushing part 20 is bent with respect to the rotation axis R, the overall torsional movement of the crushing tip 1 is suppressed. As a result, problems such as complications caused by displacement of the axial middle part of the crushing tip 1 are suppressed.

[0033] As shown in FIG. 4, the homogenization unit 20 of this embodiment includes an opening 30 and a connecting unit 40. The opening 30 is cylindrical. The tip of the opening 30 forms the open end of the homogenization tip 1. The homogenized ocular tissue and irrigation fluid enter the suction path 11 inside the homogenization tip 1 from the open end of the tip of the opening 30. The connecting unit 40 is a cylindrical member that connects the rear end of the opening 30 to the tip of the stem 10. In this embodiment, the suction path inside the opening 30 is formed thicker than the suction path inside the stem 10. In other words, when viewed in a cross section perpendicular to the rotation axis R, the cross-sectional area of ​​the suction path of the opening 30 is larger than the cross-sectional area of ​​the suction path of the stem 10.

[0034] As shown in Figures 4 and 5, the opening 30 in the crushing part 20 has a rectangular cylindrical shape (square cylindrical shape). That is, the crushing part 20 is formed so that the annular opening 30 in the crushing part 20 has a rectangular shape when viewed from the tip side of the rotation axis R. Therefore, compared to when the opening 30 is formed in a circular or square shape when viewed from the tip side, the area spaced apart from the rotation axis R is more likely to increase, and the amount of displacement of the volume when the crushing part 20 rotates around the rotation axis R is more likely to increase. In particular, the amount of displacement of the corners 31 of the opening 30 becomes larger. As a result, the crushing force of the crushing tip 1 is more likely to be improved.

[0035] As shown in FIGS. 4 and 5, when the crushing unit 20 is viewed from the distal end of the rotation axis R, each of the four corners of the opening 30 of the crushing unit 20 has a curved corner 31 that curves away from the rotation axis R. When the crushing unit 20 is viewed from the distal end of the rotation axis R, the rectangular annular opening 30 of the crushing unit 20 has a pair of short sides 33A, 33B and a pair of long sides 34A, 34B that each have a straight line in their central portion. Furthermore, the distal end surface of the opening 30 is inclined with respect to a plane perpendicular to the rotation axis R, so that one short side 33A of the pair of short sides 33A, 33B on the distal end surface of the opening 30 is positioned closer to the distal end than the other short side 33B. In this case, the short side 33A positioned closer to the distal end (hereinafter referred to as the "tip-side short side") is the part that is most likely to come into contact with the tissue to be protected (e.g., the lens capsule). However, since distal short side 33A also includes a straight portion, the shape of distal short side 33A is prevented from becoming sharp, compared to when the entire distal short side 33A is curved and protrudes in a direction away from the rotation axis, thereby preventing damage to the tissue to be protected.

[0036] In the fracturing tip 1 of this embodiment, the sharp shape of the tip short side 33A is removed by blasting the tip short side 33A of the opening 30. As a result, damage to the tissue to be protected is further suppressed.

[0037] Furthermore, when the crushing unit 20 is viewed from the tip side of the rotation axis R, it is more desirable that the length of the straight line portion 33X included in the short sides 33A, 33B of the opening 30 is 22% or more of the width SW in the short side direction of the opening 30. In this case, the possibility of damaging the tissue to be protected is appropriately reduced.

[0038] (perimeter of opening) The outer circumferential length of the opening 30 will be described with reference to FIG. 2. When viewed in a cross section perpendicular to the rotation axis (hereinafter referred to as the "vertical cross section"), the greater the outer circumferential length of the opening 30, the easier it is to increase the area of ​​the entrance of the suction path at the tip of the opening 30. The greater the area of ​​the entrance of the suction path at the tip of the opening 30, the easier it is to increase the holding force of the tissue to be crushed, thereby improving the efficiency of crushing and suctioning the tissue. However, as shown in FIG. 2, the homogenization tip 1 of this embodiment is used while inserted into a tubular sleeve 6. The size (thickness) of the sleeve 6 through which the homogenization tip 1 is inserted is limited to minimize the incision opening for inserting the homogenization tip 1 and the sleeve 6 into the eye. Therefore, if the outer circumferential length of the vertical cross section of the opening 30 of the homogenization unit 20 is made too large, the shape of the irrigation fluid passage hole 8 (see FIG. 2) formed on the side of the sleeve 6 will be distorted, increasing the possibility of impeding the flow of irrigation fluid. In contrast, in the homogenization tip 1 of this embodiment, the perimeter of the vertical cross section at the opening 30 of the homogenization part 20 is set to 3.2 mm or less. As a result, the ocular tissue can be homogenized and aspirated efficiently while preventing the flow of the perfusion fluid from being obstructed.

[0039] (Aspect ratio of opening / Corner curvature radius) 5 to 7, the ratio of the width LW in the long side direction to the width SW in the short side direction of the opening 30 (sometimes referred to as the "aspect ratio") and the radius of curvature of the corners 31 of the opening 30 will be described. As shown in FIG. 5, in the crushing tip 1 of this embodiment, when the crushing unit 20 is viewed from the tip side of the rotation axis R, the shape of the annular opening 30 in the crushing unit 20 is rectangular. In FIG. 5, when viewed from the tip side of the rotation axis R, the width in the short side direction of the opening 30 is "SW" and the width in the long side direction is "LW". Furthermore, as described above, when the crushing unit 20 is viewed from the tip side of the rotation axis R, corners 31 curved in a direction away from the rotation axis R are formed at each of the four corners of the opening 30.

[0040] The inventors of the present invention simulated the displacement volume (movement volume) of the crushing section 20 for the crushing tip 1 illustrated in Figures 1 to 5 by changing the curvature radius of the four corners 31 of the opening 30 and the ratio of the long side width LW to the short side width SW of the opening 30. The results of the simulation of the displacement volume are shown in Figure 6. The horizontal axis of Figure 6 represents the ratio (aspect ratio) of the long side width LW to the short side width SW of the opening 30. The vertical axis of Figure 6 represents the simulated displacement volume (movement volume) of the crushing section 20. Note that multiple simulations were performed while keeping the perimeter of the vertical cross section of the opening 30 and the twist angle caused by ultrasonic vibration constant. As an example, in this simulation, the perimeter of the vertical cross section of the opening 30 was fixed within a narrow range of 2.96 mm to 2.98 mm, and the twist angle was set to 14 degrees.

[0041] Furthermore, the inventors of the present invention simulated the suction port area at the tip of opening 30 (i.e., the area of ​​the entrance to the suction path) by changing the radius of curvature of each of the four corners 31 of opening 30 and the ratio of the long side width LW to the short side width SW of opening 30, while maintaining the perimeter length of the vertical cross section of opening 30 within a narrow range of 2.96 mm to 2.98 mm. The results of the simulation of the suction port area are shown in Figure 7.

[0042] As shown in Fig. 6, the larger the ratio of the long side width to the short side width (aspect ratio), the larger the displacement volume (movement volume) when the crushing unit 20 rotates around the rotation axis R, and therefore the crushing force improves. On the other hand, as shown in Fig. 7, the smaller the ratio of the long side width to the short side width (aspect ratio), the larger the suction port area, and therefore the holding force of the tissue to be crushed increases. Comparing the simulation results shown in Fig. 6 and Fig. 7, it can be seen that in order to achieve both crushing force and holding force, it is desirable for the ratio of the long side width LW to the short side width SW of the opening 30 to be 1.25 to 1.75.

[0043] As shown in Figure 6, it can be seen that the smaller the radius of curvature of each of the corners 31 at the four corners of the opening 30, the greater the displacement volume when the crushing unit 20 rotates around the rotation axis R, and the improved crushing force. Specifically, when the radius of curvature of the corners 31 of the opening 30 is 0.30 mm, it can be seen that the displacement volume decreases particularly when the ratio of the width LW in the long side direction to the width SW in the short side direction of the opening 30 is reduced. From the above results, it can be seen that in order to ensure sufficient crushing force, it is desirable that the radius of curvature of each of the corners 31 at the four corners of the opening 30 be 0.25 mm or less.

[0044] 7, when the perimeter of the vertical cross section of opening 30 is fixed, the larger the radius of curvature of each of the four corners 31 of opening 30, the larger the suction port area, and therefore the greater the holding power of the tissue to be crushed. Therefore, in order to achieve both crushing power and holding power, it is desirable that the radius of curvature of corners 31 of opening 30 be 0.15 mm to 0.25 mm.

[0045] (Vibration amplification factor) As described above, the homogenizing tip 1 is used while attached to the distal end of the US handpiece 2. The US handpiece 2 applies ultrasonic vibrations to the homogenizing tip 1. The amplitude of the vibrations applied from the US handpiece 2 to the homogenizing tip 1 is amplified in the homogenizing section 20 at the distal end of the homogenizing tip 1. If the amplitude of the vibrations in the homogenizing section 20 is too small, the homogenizing force will be insufficient. On the other hand, if the amplitude of the vibrations in the homogenizing section 20 is too large, the homogenizing tip 1 will be easily damaged. After careful consideration, the inventors of the present invention have found that in order to prevent damage to the homogenizing tip 1 while ensuring appropriate homogenizing force, it is desirable to set the amplification factor of the vibrations applied from the US handpiece 2 to the homogenizing tip 1 in the homogenizing section 20 to 3 to 4 times.

[0046] (weight of crushed chips) The inventors of the present invention conducted a simulation to determine the desirable weight of the fragmentation tip 1 having the configuration of the present disclosure in order to achieve the condition of a 3 to 4 times amplification factor of the vibration in the fragmentation part 20. The results of the weight simulation are shown in FIG. 8. The horizontal axis of FIG. 8 represents the total weight of the fragmentation tip 1. The vertical axis of FIG. 8 represents the amplification factor in the fragmentation part 20 of the vibration applied to the fragmentation tip 1 from the US handpiece 2. In this simulation, the length L (see FIG. 2) of the fragmentation tip 1 from the tip of the detachable part 12 to the tip of the fragmentation part 20 was fixed at 24.8 mm, and the thickness of the thick part on the rear end (base end) of the shaft part 10 was changed to simulate the amplification factor.

[0047] As shown in FIG. 8, by setting the total weight of the crushing tip 1 to 0.146 g to 0.165 g, the amplification factor of vibration in the crushing part 20 becomes 3 to 4 times, which means that damage to the crushing tip 1 can be suppressed while ensuring crushing force.

[0048] (Length of crushing tip) The inventors of the present invention conducted a simulation to determine the desirable length L of the fragmentation tip 1 having the configuration of the present disclosure, which satisfies the condition that the amplification factor of the vibration in the fragmentation part 20 is 3 to 4 times. The results of the simulation of the length L are shown in FIG. 9. The horizontal axis of FIG. 9 represents the length L of the fragmentation tip from the tip of the detachable part 12 to the tip of the fragmentation part 20 (see FIG. 2). The vertical axis of FIG. 9 represents the amplification factor in the fragmentation part 20 of the vibration applied to the fragmentation tip 1 from the US handpiece 2. In this simulation, the total weight of the fragmentation tip 1 was maintained within a narrow range of 0.155 g to 0.159 g, and the amplification factor was simulated by changing the length of the section of the tip side of the shaft part 10 where the outer shape was constant.

[0049] As shown in Figure 9, by setting the length L of the crushing tip 1 to 24.4 mm to 25.6 mm, the amplification factor of the vibration in the crushing section 20 becomes 3 to 4 times, which means that damage to the crushing tip 1 can be suppressed while ensuring crushing force.

[0050] The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the scope of the claims and their equivalents. It is also possible to employ only a portion of the technologies (including desirable ranges of dimensions, weight, etc.) exemplified in the above embodiments. [Explanation of symbols]

[0051] 1 crushing tip 2 US handpieces 6 sleeves 7 Insertion hole 8 Irrigation fluid passage hole 10 Shaft 11 Suction path 12 Detachable part 20 Crushing section 30 Opening 31 Corner 33A, 33B short side 33X Straight section 34A, 34B long side 40 Connection R rotation axis

Claims

1. A crushing tip that crushes eye tissue by applying ultrasonic vibration, A cylindrical shaft portion that forms a suction path therein and has a central axis that coincides with the rotation axis of the crushing tip; a crushing unit that is cylindrical, is connected to the tip of the shaft unit with its central axis aligned with the rotation shaft, and forms a suction path therein together with the shaft unit; Equipped with When the crushing section is viewed from the tip side of the rotating shaft, the shape of the annular opening in the crushing section is formed into a rectangle having curved corners at four corners and including straight line portions on each of a pair of long sides and a pair of short sides, The tip surface of the opening of the crushing section is inclined with respect to a plane perpendicular to the rotation axis, so that one of the pair of short sides on the tip surface is located closer to the tip than the other short side.

2. The crushing tip according to claim 1, It is used in a state where it is inserted into the inside of a tubular sleeve that forms a flow path for the perfusion fluid inside. the sleeve has an insertion hole at the most distal end through which the homogenizing tip is inserted, and an irrigation fluid passage hole formed on a side surface on the rear end side of the insertion hole, A crushing tip, wherein the outer periphery of a cross section perpendicular to the rotation axis of a portion of the opening of the crushing portion that passes through the insertion hole of the sleeve is 3.2 mm or less.

3. The crushing tip according to claim 1 or 2, When the crushing section is viewed from the tip side of the rotating shaft, the ratio of the width in the long side direction to the width in the short side direction of the rectangular opening in the crushing section is 1.25 to 1.75 times. A crushing tip characterized by.

4. The crushing tip according to any one of claims 1 to 3, A crushing tip characterized in that, when the crushing section is viewed from the tip side of the rotating shaft, the radius of curvature of each of the four corners of the rectangular opening in the crushing section is 0.25 mm or less.

5. The crushing tip according to claim 4, When the crushing section is viewed from the tip side of the rotating shaft, the radius of curvature of each of the four corners of the rectangular opening in the crushing section is 0.15 mm to 0.25 mm.

6. The crushing tip according to any one of claims 1 to 5, The crushed chips have a total weight of 0.146 g to 0.165 g.

7. The crushing tip according to any one of claims 1 to 6, a detachable portion provided at a base end of the shaft portion and detachably attached to a tip of an US handpiece that generates ultrasonic vibrations; The length of the crushing tip from the tip of the detachable part to the tip of the crushing part is 24.4 mm to 25.6 mm.

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