Ophthalmic minimally invasive drainage device with expansion and fixation function and its delivery system

Abstract

The present invention provides an ophthalmic minimally invasive drainage device with an expansion and fixation function and a delivery system thereof, wherein the ophthalmic minimally invasive drainage device comprises a drainage body with a hollow cavity and an expansion fixator, wherein the drainage body comprises a proximal portion and a distal portion away from the proximal portion; the expansion fixator is in a two-dimensional plane or a three-dimensional solid shape and has a first end and a second end, the first end being connected to the proximal portion of the drainage body, and the second end being connected to the distal portion of the drainage body; the proximal portion is an end close to the suprachoroidal space, and its length is 0.2-2.5 mm, and the distal portion is an end close to the anterior chamber of the eye, and its length is 0.5-3.0 mm. The ophthalmic minimally invasive drainage device with an expansion and fixation function of the present invention adopts a drainage body with a hollow cavity, which can meet the requirements of loading and implantation; after being released, it returns to a preset shape. While playing a drainage role, the expansion fixator can enhance the fixation effect in the eye, form ciliary body dissociation, and thereby promote aqueous humor absorption and inhibit aqueous humor secretion.

Description

Technical Field

[0001] The present invention relates to the field of medical devices, and in particular to an ophthalmic minimally invasive drainage device with expansion and fixation functions and a delivery system thereof. Background Art

[0002] MIGS (minimally invasive glaucoma surgery) is an emerging surgical procedure for the treatment of mild to moderate glaucoma. Implantation of a shunt, either alone or in combination with cataract extraction, can effectively, minimally, and conveniently reduce IOP (intraocular pressure). Currently, MIGS can be categorized into three types based on the anatomical pathway through which the shunt drains the aqueous humor: subconjunctival drainage, Schlemm's canal drainage, and suprachoroidal drainage. Suprachoroidal drainage is an ideal approach because the suprachoroidal space is the physiological drainage pathway for the aqueous humor, offers ample space, and does not form a filtration bleb during operation. Currently, MIGS shunts for suprachoroidal drainage are categorized by implantation method as either internal or external. Representative internal shunt devices include the Cypass, iStentSupra, and MiniJect, while representative external shunt devices include the Slox Gold shunt, Aquashunt, and STARflo. All of the above approaches can effectively lower IOP in glaucoma patients. However, the internal approach requires concurrent cataract surgery and carries the risk of drainage device displacement and dislodgement, leading to intraocular tissue damage. The external approach is also highly invasive, with the potential for severe perioperative complications such as explosive suprachoroidal hemorrhage, and significant fibrosis in the internal drainage area. These factors limit the clinical application of suprachoroidal drainage of MIGS.

[0003] Suprachoroidal space drains are mostly non-metallic tubes with an inner lumen, such as Cypass, which is made of polyimide. Due to the extrusion processing characteristics of the tube, the tube has fixed inner and outer diameter parameters and a fixed axial direction, which makes it easy for the tube to slip in the suprachoroidal space after implantation, affecting the drainage effect. Therefore, in the tube drain solution, a structure that increases the fixing effect of the tube (such as the ring with an increased outer diameter set in Cypass) will be provided. However, due to the limitation of the small overall size of the tube (such as the outer diameter of Cypass is about 0.40mm and the inner diameter is about 0.30mm), the processing of the fixed structure is difficult. Summary of the Invention

[0004] The inventors of this case discovered that nickel-titanium shape memory alloy (nickel mass fraction of 54.5%-57.0%) is a shape memory alloy. Nickel-titanium shape memory alloy materials have good biocompatibility and excellent shape memory properties and are currently widely used in intravascular implants, such as intravascular stents and filters. However, their use as MIGS drainage devices is less common. The Hydrus Microstent, made of nickel-titanium shape memory alloy, is a Schlemm's tube drainage product. The successful application of the Hydrus Microstent demonstrates that nickel-titanium shape memory alloy materials can be successfully used in ophthalmic drainage devices.

[0005] The present invention aims to solve, at least to a certain extent, one of the technical problems in the related art. To this end, the present invention provides an ophthalmic minimally invasive drainage device with an expansion and fixation function, the ophthalmic minimally invasive drainage device comprising a drainage body having a hollow cavity and an expansion and fixation device connected to the drainage body, wherein:

[0006] The drainage body is used to connect the anterior chamber of the eye and the suprachoroidal space, and includes a proximal portion and a distal portion away from the proximal portion; the expander fixture is in a two-dimensional planar shape or a three-dimensional solid shape, and has a first end and a second end, the first end is connected to the proximal portion of the drainage body, and the second end is connected to the distal portion of the drainage body;

[0007] The proximal portion of the drainage body is the end close to the suprachoroidal space, and its length is 0.2-2.5 mm. The distal portion of the drainage body is the end close to the anterior chamber of the eye, and its length is 0.5-3.0 mm.

[0008] The present invention utilizes a minimally invasive ophthalmic drainage device with an expandable and fixed function, utilizing a drainage body with a hollow cavity that meets loading and implantation requirements. Upon release, the device returns to its pre-set shape. While providing drainage, the expandable and fixed device prevents slippage and enhances intraocular fixation, thus achieving the device's expandable and fixed function. Furthermore, the expandable and fixed device deployed in the supraciliary cavity can achieve a certain degree of ciliary dissociation, allowing aqueous humor drained from the anterior chamber to enter the supraciliary choroidal space and then be absorbed by the sclera or ciliary choroidal blood vessels. Furthermore, the ciliary dissociation caused by the expandable and fixed device inhibits aqueous humor secretion by the non-pigmented ciliary epithelial cells, further reducing intraocular pressure.

[0009] Optionally, the ophthalmic minimally invasive drainage device with expansion and fixation function is made of nickel-titanium shape memory alloy material;

[0010] The drainage body and the expansion fixator are formed in one piece or in a split combination;

[0011] The outer diameter of the drainage body is 0.15-0.6 mm; the inner diameter of the drainage body is 0.05-0.4 mm.

[0012] Optionally, the expandable fixture is shaped like a two-dimensional plane; wherein the expandable fixture includes two expansion ribs arranged symmetrically about the axis of the drainage body, for example, the expandable fixture comprises two expansion ribs arranged at a 180° angle and parallel to the axis of the drainage body; and the two-dimensional expansion plane formed by the two expansion ribs has a first expansion diameter, which is 0.6-2.0 mm; preferably, the first expansion diameter is 0.8-1.5 mm. The expandable fixture can be integral with the drainage body or can be assembled with the drainage body, and the assembly method includes welding or bonding with biocompatible glue.

[0013] Optionally, the drainage body can be a drainage tube with an inner cavity; the first end and the second end of the expansion fixer are respectively sleeved on the outer wall of the drainage tube, and any one of the first end and the second end is fixedly connected to the outer wall of the drainage tube, and the other end is a free sliding end.

[0014] Optionally, the shape of the expansion fixator is three-dimensional; the expansion fixator comprises n expansion ribs, wherein n is an integer greater than 2, preferably, n is 3 or 4;

[0015] The n expansion ribs are arranged to be evenly spaced along the circumference of the drainage body. For example, the expansion ribs are n expansion ribs evenly distributed at an angle of 360° / n, and the expansion ribs are arranged along the axial direction parallel to the drainage body; or, the expansion ribs are arranged in a spiral form along the axial direction of the drainage body.

[0016] Optionally, the expansion fixator includes three expansion ribs evenly arranged along the circumference of the drainage body, and the three-dimensional expansion structure composed of the three expansion ribs has a second expansion diameter, and the second expansion diameter is 0.4-1.2 mm; preferably, the second expansion diameter is 0.6-0.8 mm; the expansion fixator can be an integral part with the drainage body, and can also be composed of a combination with the drainage body, and the combination method includes welding or bonding with biocompatible glue.

[0017] Optionally, the length of the two-dimensional planar expander is 0.9-2.2 mm, preferably 1.0-1.8 mm; or the length of the three-dimensional expander is 0.8-1.8 mm, preferably 1.0-1.5 mm; preferably, the two-dimensional planar expander or the three-dimensional expander is configured to dissociate the ciliary body, so that the aqueous humor drained from the anterior chamber enters the ciliary body suprachoroidal space and is then absorbed through the sclera or ciliary body choroidal blood vessels.

[0018] The present invention provides a delivery system for delivering the ophthalmic minimally invasive drainage device with expansion and fixation functions of the present invention, the delivery system comprising a puncture needle, a needle seat, a housing, a thimble, a tail seat, a button and a spring;

[0019] The puncture needle is fixedly connected to the needle holder, and the needle holder is disposed in the housing and can move forward and backward relative to the housing; the puncture needle includes a first cylindrical inner cavity for loading the ophthalmic minimally invasive drainage device with an expansion and fixing function; the ophthalmic minimally invasive drainage device can be elastically compressed and loaded into the first cylindrical inner cavity; the puncture needle is disposed at the front end of the housing, and at least a portion of the puncture needle is inserted into the interior of the housing;

[0020] The button is connected to the needle seat and cooperates with the housing; the spring is arranged between the button and the needle seat; the button can push the needle seat to move forward and backward relative to the housing;

[0021] The ejector pin is fixedly connected to the tailstock, the outer diameter of the ejector pin is slidably matched with the inner diameter of the puncture needle, the ejector pin is used to support the ophthalmic minimally invasive drainage device with expansion and fixing functions, and the tailstock is fixedly connected to the shell.

[0022] Optionally, the button and the housing have a first state and a second state; in the first state, the button and the housing form a limit to prevent the needle seat from moving; in the second state, the button releases the limit relationship with the housing.

[0023] Optionally, the tailstock includes a blind hole cooperated with and fixed to the ejector pin, and a first locking structure cooperated with and fixed to the housing, the first locking structure is a threaded structure or a snap-fit structure, and the tailstock and the housing are fixedly connected via the first locking structure;

[0024] The puncture needle is made of stainless steel or nickel-titanium shape memory alloy, the needle seat, shell, tail seat and button are made of resin, and the ejector pin and spring are made of stainless steel.

[0025] Optionally, the shell includes a second cylindrical inner cavity that slides with the puncture needle, a shell inner cavity that slides with the outer surface of the needle seat, a first shell inner cavity surface and a second shell inner cavity surface that slide with the outer surface of the button, and a second locking structure that cooperates with the first locking structure.

[0026] Optionally, the needle seat has a third cylindrical inner cavity with the same axis as the puncture needle and slidingly engaged with the ejector pin, the needle seat has a rectangular outer surface that slides with the inner cavity of the shell, the needle seat has a first needle seat inner cavity surface and a second needle seat inner cavity surface that slides with the outer surface of the button, the first needle seat inner cavity surface and the second needle seat inner cavity surface are arranged to form a button mounting cavity, the needle seat has a cylinder fixedly engaged with the inner surface of the spring, and the cylinder is arranged in the button mounting cavity.

[0027] Optionally, the button includes a second button outer surface slidably matched with the inner cavity surface of the first needle seat, a first button outer surface slidably matched with the inner cavity surface of the second needle seat, a third button outer surface slidably matched with the inner cavity surface of the first shell, a fourth button outer surface slidably matched with the inner cavity surface of the second shell, and a button inner cavity surface fixedly matched with the spring;

[0028] The width of the first shell inner cavity surface is greater than the width of the second shell inner cavity surface, and the diameter of the second button outer surface is greater than the width of the second shell inner cavity surface, so that in the first state, the second shell inner cavity faces the second button outer surface to form a locking limit;

[0029] The diameter of the outer surface of the fourth button is smaller than that of the outer surface of the second button and smaller than or equal to the width of the inner cavity of the second shell, so that the outer surface of the fourth button can slide relatively along the inner cavity of the second shell in the second state.

[0030] Optionally, the outer diameter of the puncture needle is 0.4-0.8 mm, the inner diameter of the puncture needle is 0.18-0.61 mm, and the puncture needle is a round blunt needle;

[0031] The spring comprises an outer spring surface fixedly matched with the inner cavity surface of the button and an inner spring surface fixedly matched with the outer surface of the cylinder of the needle seat.

[0032] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings herein are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present invention, and together with the description are used to explain the principles of the present invention. In the accompanying drawings, the same components use the same figure marks, and the drawings are not in actual proportion.

[0034] Figure 1A 1 is a schematic structural diagram of a flow diverter with a two-dimensional planar expansion fixator according to an embodiment of the present invention;

[0035] Figure 1B 2 is a schematic structural diagram of a drainage device with a two-dimensional planar expansion fixator in another embodiment of the present invention;

[0036] Figure 2 This is a schematic structural diagram of a drainage device with a three-dimensional expansion fixator in another embodiment of the present invention;

[0037] Figure 3 This is a schematic structural diagram of a drainage device with a three-dimensional expansion fixator in another embodiment of the present invention;

[0038] Figure 4 2 is a schematic structural diagram of a puncture needle and a needle holder of a delivery system according to an embodiment of the present invention;

[0039] Figure 5 is a schematic structural diagram of a housing of a delivery system according to one embodiment of the present invention;

[0040] Figure 6 2 is a schematic structural diagram of an ejector pin and a tailstock of a delivery system according to an embodiment of the present invention;

[0041] Figure 7 is a schematic structural diagram of a button of a delivery system according to an embodiment of the present invention;

[0042] Figure 8 is a schematic structural diagram of a spring of a delivery system according to an embodiment of the present invention;

[0043] Figure 9 is a schematic diagram of the assembly relationship of the delivery system in one embodiment of the present invention;

[0044] Figure 10 is a schematic diagram of the assembly of a drainage device and a delivery system according to one embodiment of the present invention;

[0045] Figure 11A Schematic diagram of the coordination relationship between the drainage device and the delivery system components in the initial state in one embodiment of the present invention;

[0046] Figure 11B Schematic diagram of the coordination relationship between the drainage device and the delivery system components in the activated state (button pressed) in one embodiment of the present invention;

[0047] Figure 11C Schematic diagram of the coordination relationship of components during the release process of the drainage device according to one embodiment of the present invention;

[0048] Figure 11D Schematic diagram of the coordination relationship of the components of the flow diverter in the release completion state according to one embodiment of the present invention;

[0049] Figure 12A is a schematic diagram of injecting a viscoelastic agent into the suprachoroidal space according to one embodiment of the present invention;

[0050] Figure 12B Schematic diagram of the position of the drainage device during implantation according to one embodiment of the present invention;

[0051] Figure 12C Schematic diagram of the drainage device after release in one embodiment of the present invention;

[0052] Figure 12D Schematic diagram of a completed drainage device implantation according to an embodiment of the present invention;

[0053] Figure 13 This is an AS-OCT image of a rabbit eye one month after implantation of the drainage device according to one embodiment of the present invention.

[0054] Reference numerals:

[0055] 100-Drainage device with a two-dimensional planar expansion fixator;

[0056] 200-Drainage device with three-dimensional expansion fixator;

[0057] 110, 210 - distal end of the drainage body; 130, 230 - proximal end of the drainage body; 140, 240 - hollow inner cavity of the drainage body; 121, 122 - first expansion rib in a two-dimensional plane;

[0058] 150 - a second expansion fixator in a two-dimensional plane; 151, 152 - a second expansion rib in a two-dimensional plane;

[0059] 221, 222, 223-the third expansion rib of the three-dimensional shape;

[0060] 224, 225, 226-fourth expansion rib of three-dimensional shape;

[0061] 300-delivery system;

[0062] 310 - puncture needle; 311 - first cylindrical inner cavity;

[0063] 320 - needle seat; 321 - third cylindrical inner cavity; 322 - rectangular outer surface; 323 - first needle seat inner cavity surface, 324 - second needle seat inner cavity surface; 325 - cylinder;

[0064] 330 - housing; 331 - second cylindrical inner cavity, 332 - housing inner cavity, 333 - first housing inner cavity surface, 334 - second housing inner cavity surface; 335 - second locking structure;

[0065] 340-thimble;

[0066] 350-tailstock; 351-blind hole; 352-first locking structure;

[0067] 360 - button; 361 - outer surface of the first button; 362 - outer surface of the second button; 363 - outer surface of the third button; 364 - outer surface of the fourth button; 365 - inner surface of the button;

[0068] 370-spring; 371-outer surface of spring; 372-inner surface of spring. DETAILED DESCRIPTION

[0069] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0070] Based on the problems of poor fixation effect and difficult processing of current drain devices, as well as the risks of current external surgical methods, the present invention provides a new ophthalmic minimally invasive drain with expansion and fixation function, which is protected by a suprachoroidal viscoelastic sheath and implanted externally in the suprachoroidal space, and its delivery system.

[0071] This embodiment first provides an ophthalmic minimally invasive drainage device with expansion and fixation functions, see FIG1- Figure 3 The ophthalmic minimally invasive drainage device is a drainage body with a hollow cavity (140, 240), the hollow cavity (140, 240) is a passage for aqueous humor to flow from the anterior chamber into the suprachoroidal space, the drainage body includes a proximal portion (130, 230) and a distal portion (110, 210) away from the proximal portion, wherein the end of the drainage body entering the anterior chamber of the eye is the distal portion (110, 210), and the end in the suprachoroidal space is the proximal portion (130, 230); the ophthalmic minimally invasive drainage device with an expansion and fixation function is also provided with an expansion fixator capable of enhancing the fixation effect in the eye and having a ciliary body dissociation function, the expansion fixator can be an integral part with the drainage body, or can be a combined part (150) with the drainage body, and the combination method includes welding or bonding with biocompatible glue.

[0072] The shape of the expansion fixator is a two-dimensional plane or a three-dimensional solid. The two-dimensional plane expansion fixator has a first end and a second end. The first end is connected to the proximal end (130, 230) of the drainage body, and the second end is connected to the distal end (110, 210) of the drainage body. Exemplarily, the expansion fixator includes two expansion ribs (121, 122, 151, 152) that are symmetrically distributed and parallel to the axial direction of the drainage body and are integral with the drainage body, such as the first expansion rib (121, 122) or the second expansion rib (151, 152); the expansion fixator may also include n expansion ribs (221, 222, 223, 224, 225, 226) uniformly spaced along the circumference of the drainage body. Specifically, the expansion fixator may have n expansion ribs uniformly distributed at an angle of 360° / n along the circumference of the drainage body, where n is an integer, preferably, n is 3 or 4. The expansion fixator may include third expansion ribs (221, 222, 223) uniformly arranged along the axis parallel to the drainage body, and may also include fourth expansion ribs (224, 225, 226) distributed in a spiral shape along the axis of the drainage body. The above-mentioned drain device is squeezed into the suprachoroidal space and eye tissue, which can enhance the fixation effect of the implant in the eye. The drain device with a preset two-dimensional planar or three-dimensional expansion fixator can be compressed and loaded into the puncture needle of the delivery system. After being released and implanted into the eye, it can restore the preset shape and then be fixed in the release position.

[0073] In some embodiments, the ophthalmic minimally invasive drainage device is made of nickel-titanium shape memory alloy, and the drainage body and the expansion fixator are formed in an integral manner or in a split manner.

[0074] The drainage device, made of nickel-titanium shape memory alloy, connects the anterior chamber and the suprachoroidal space, acting as a drainage device. It also meets the requirements for linear compression, thus satisfying loading and implantation requirements. Upon release, it returns to its preset shape, preventing slippage and enhancing intraocular fixation while providing drainage. Furthermore, the expansion device deployed in the supraciliary space can achieve a certain degree of ciliary dissociation, allowing aqueous humor drained from the anterior chamber to enter the suprachoroidal space and then be absorbed through the sclera or ciliary choroidal blood vessels. Furthermore, the ciliary dissociation caused by the expansion device can inhibit aqueous humor secretion by the non-pigmented ciliary epithelial cells, further reducing intraocular pressure.

[0075] Preferably, the outer diameter of the drainage body of the ophthalmic minimally invasive drainage device is 0.15-0.6 mm; the inner diameter of the drainage body is 0.05-0.4 mm; the total length of the ophthalmic minimally invasive drainage device is 2.5-7.0 mm; the length of the distal end of the drainage body of the ophthalmic minimally invasive drainage device entering the anterior chamber of the eye is 0.5-3.0 mm; the length of the proximal end of the drainage body of the ophthalmic minimally invasive drainage device at the suprachoroidal space is 0.2-2.5 mm.

[0076] Reference Figure 1A 、 Figure 1B A drainage device (100) with a two-dimensional planar expansion fixator, wherein the expansion fixator is composed of two expansion ribs (121, 122, 151, 152) arranged symmetrically about the axis of the drainage body, and the expansion fixator can be integrated with the drainage body ( Figure 1A ), or it can be combined with the drainage body ( Figure 1B The two expansion ribs can form a preset two-dimensional expansion plane, which has a first expansion diameter, and the first expansion diameter is 0.6-2.0 mm; preferably, the first expansion diameter is 0.8-1.5 mm. It should be noted that the first expansion diameter and the second expansion diameter described below refer to the diameter of the circumscribed circle formed by the expansion rib after expansion, in a direction perpendicular to the axial direction of the drainage body.

[0077] When it is a split assembly (refer to Figure 1B ), the drainage body and the expansion fixture are independent components that can be assembled to form an assembly (150). For example, the drainage body can be a drainage tube with an inner cavity, and the first end and the second end of the expansion fixture are respectively sleeved on the outer wall of the drainage tube, and any one of the first end and the second end is fixedly connected to the outer wall of the drainage tube, for example, by using a laser welding machine to spot weld any one end of the expansion fixture to the drainage tube, and the other end is a free sliding end that can slide freely on the drainage tube.

[0078] See Figure 2 、 Figure 3 A drainage device (200) with a three-dimensional expansion fixator, wherein the expansion fixator is composed of three expansion ribs uniformly arranged along the circumference of the drainage body, such as three third expansion ribs (221, 222, 223) or fourth expansion ribs (224, 225, 226) spaced 120 degrees apart and uniformly distributed, and the third expansion ribs (221, 222, 223) can be distributed parallel to the axial direction of the drainage body ( Figure 2 ), the fourth expansion ribs (224, 225, 226) can also be spirally distributed relative to the axial direction of the drainage body ( Figure 3The expansion fixator can be integral with the drainage body or assembled with the drainage body. The three-dimensional expansion structure formed by the three expansion ribs in this embodiment has a second expansion diameter, which can be 0.4-1.2 mm; preferably, the second expansion diameter is 0.6-0.8 mm.

[0079] According to one embodiment, the length of the two-dimensional planar expansion fixator is 0.9-2.2 mm, preferably 1.0-1.8 mm; or the length of the three-dimensional expansion fixator is 0.8-1.8 mm, preferably 1.0-1.5 mm.

[0080] This embodiment further provides a delivery system for delivering the ophthalmic minimally invasive drainage device in any of the above embodiments, see Figures 4-10 The delivery system mainly includes a puncture needle 310, a needle seat 320, a shell 330, a thimble 340, a tail seat 350, a button 360 and a spring 370; wherein the puncture needle 310 is fixedly connected to the needle seat 320, and the puncture needle 310 includes a first cylindrical inner cavity 311 for loading an ophthalmic minimally invasive drainage device; the ophthalmic minimally invasive drainage device can be elastically compressed and loaded into the first cylindrical inner cavity 311 of the puncture needle; the puncture needle 310 is arranged at the front end of the shell 330, and a part of the puncture needle 310 is inserted into the interior of the shell 330; the needle The seat 320 is arranged in the shell 330 and can move forward and backward relative to the shell 330; the button 360 is connected to the needle seat 320 and cooperates with the shell 330; the spring 370 is arranged between the button 360 and the needle seat 320; the button 360 can push the needle seat 320 to move forward and backward relative to the shell 330; the ejector pin 340 is fixedly connected to the tail seat 350, and the outer diameter of the ejector pin 340 is slidably matched with the inner diameter of the puncture needle 310. The ejector pin 340 is used to support the minimally invasive ophthalmic drainage device, and the tail seat 350 is fixedly connected to the shell 330.

[0081] In order to meet the implantation requirements, the drain made of nickel-titanium shape memory alloy can be linearly compressed. One solution is to completely compress its expansion fixator into the rigid puncture needle 310, with the length of the distal end of the drainage body exposed from the puncture needle 310 being 0.5-3.0 mm. Before the drain is implanted, it is stretched open by injecting a viscoelastic agent into the suprachoroidal space to facilitate the puncture and positioning of the puncture needle 310. As part of the delivery system, the puncture needle 310 enters the suprachoroidal space until the distal end of the drain body passes through the anterior chamber angle by 0.3-1.0 mm. After the puncture needle is withdrawn, the drain is released in situ, and then the delivery system is withdrawn as a whole to complete the implantation process of the drain.

[0082] In some embodiments, the button 360 and the housing 330 have a first state and a second state; in the first state, the button 360 and the housing 330 form a limit to prevent the needle seat 320 from moving; in the second state, the button 360 releases the limit relationship with the housing 330.

[0083] See Figure 6 The tailstock 350 includes a blind hole 351 that cooperates with the ejector pin 340 and is fixed to the shell 330. The first locking structure 352 is a threaded structure or a snap structure. The tailstock 350 and the shell 330 are fixedly connected through the first locking structure 352. The puncture needle 310 is made of stainless steel or nickel-titanium shape memory alloy. The needle seat 350, the shell 330, the tailstock 350 and the button 360 are made of resin. The ejector pin 340 and the spring 370 are made of stainless steel.

[0084] See Figure 5 The housing 330 includes a second cylindrical inner cavity 331 that slidably engages with the puncture needle 310, a housing inner cavity 332 that slidably engages with the outer surface of the needle holder 320, a first housing inner cavity surface 333 and a second housing inner cavity surface 334 that slidably engage with the outer surface of the button 360, and a second locking structure 335 that engages with the first locking structure 352. The second locking structure 335 can be a threaded structure or a snap-fit structure, as long as it can be fixedly connected to the first locking structure 352. The housing inner cavity 332 can be a rectangular inner cavity.

[0085] The width of the first shell inner cavity surface 333 is greater than the width of the second shell inner cavity surface 334, and the diameter of the second button outer surface 361 is greater than the width of the second shell inner cavity surface 334, so that the second shell inner cavity surface 334 forms a restriction on the second button outer surface 361 in the first state.

[0086] Furthermore, the diameter of the fourth button outer surface 364 is smaller than the diameter of the second button outer surface 362 and smaller than or equal to the width of the second shell inner cavity surface 334, so that the fourth button outer surface 364 can slide along the second shell inner cavity surface 334 in the second state.

[0087] See Figure 4 The needle seat 320 has a third cylindrical inner cavity 321 with the same axis as the puncture needle 310 and slidingly cooperates with the ejector pin 340. The needle seat 320 has a rectangular outer surface 322 that slides with the inner cavity of the shell. The needle seat 320 has a first needle seat inner cavity surface 323 and a second needle seat inner cavity surface 324 that slide with the outer surface of the button 360. The first needle seat inner cavity surface 323 and the second needle seat inner cavity surface 324 are arranged to form a button installation cavity. The needle seat 320 has a cylinder 325 that is fixedly cooperated with the inner surface of the spring 370, and the cylinder 325 is located in the button installation cavity.

[0088] See Figure 7 The button 360 includes a second button outer surface 361 that slides with the first needle hub inner surface 323, a first button outer surface 362 that slides with the second needle hub inner surface 324, a third button outer surface 363 that slides with the first housing inner surface 333, a fourth button outer surface 364 that slides with the second housing inner surface 334, and a button inner surface 365 that is fixedly engaged with the outer surface of the spring 370. The fourth button outer surface 364 has a smaller diameter than the second button outer surface 361 and is capable of sliding along the second housing inner surface 334.

[0089] In some embodiments, the outer diameter of the puncture needle 310 is 0.4-0.8 mm, the inner diameter of the puncture needle 310 is 0.18-0.61 mm, and the needle tip of the puncture needle 310 is a rounded blunt needle.

[0090] See Figure 8 The spring 370 has a spring outer surface 371 fixedly matched with the button inner cavity surface 365 and a spring inner surface 372 fixedly matched with the outer surface of the cylinder 325 of the needle seat 320.

[0091] During the assembly process, after the needle seat 320 is installed in the inner cavity 332 of the shell, the inner surface 372 of the spring is fixedly matched with the cylinder 325 of the needle seat, and the outer surface 371 of the spring is fixedly matched with the inner cavity surface 365 of the button. The second outer surface 362 of the button 360 passes through the first inner cavity surface 333 of the shell 330 through an interference fit, thereby realizing the matching of the first inner cavity surface 323 of the needle seat and the second outer surface 362 of the button. At the same time, under the support of the elastic force of the spring 370, the matching of the first inner cavity surface 333 and the third outer surface 363 of the button is maintained. Since the width of the second inner cavity surface 334 of the shell is smaller than the first inner cavity surface 333 and cannot adapt to the third outer surface 363 of the button, a limiting connection is formed between the button 360 and the shell 330, and between the button 360 and the needle seat 320 ( Figure 9 、 Figure 11A ).

[0092] See Figure 10 After the drain is installed into the first cylindrical inner cavity 311 of the puncture needle 310, the assembly of the drain and the delivery system is completed.

[0093] See Figure 11A , the limiting connection between the button 360 and the housing 330, and between the button 360 and the needle seat 320 is in the initial state (ie, the first state). Figure 11B By pressing the button 360, the first housing inner surface 333 and the third button outer surface 363 are released from the engagement, and the assembly enters the start-up state (i.e., the second state). Figure 11CThe retraction button 360 realizes the sliding fit between the inner cavity surface 334 of the second shell and the outer surface 364 of the fourth button. The retraction movement of the button 360 drives the needle seat 320 to retract, and also realizes the retraction of the puncture needle 310. At the same time, the position of the ejector 340 remains unchanged, so the ejector 340 pushes the drain device out of the puncture needle 310, thereby realizing the in-situ release of the drain device. Figure 11D After the force on the button 360 is removed, the delivery system can be stabilized in a state where the drain release is completed.

[0094] Drain implantation is a new external route implantation method based on the protection of suprachoroidal viscoelastic sheath. The implantation steps are as follows:

[0095] (1) Cut the bulbar conjunctiva about 4 mm in diameter approximately 4 mm behind the corneoscleral limbus;

[0096] (2) See Figure 12A , use a syringe or dedicated device (such as a suprachoroidal syringe) to inject viscoelastic (about 70 μl / eye) 4 mm behind the corneoscleral limbus;

[0097] (3) See Figure 12B The puncture needle of the delivery system is inserted into the suprachoroidal space at an oblique angle (approximately 10-15° tangential angle to the sclera) until the distal end of the drain penetrates the anterior chamber angle by approximately 0.5 mm.

[0098] (4) See Figure 12C , press the button and withdraw to release the drain in situ;

[0099] (5) See Figure 12D , pull out the puncture needle and complete the implantation of the drainage device;

[0100] (6) Press the puncture site to stop bleeding and allow the puncture site to close on its own (if the puncture site does not close on its own, close the incision with 10-0 sutures).

[0101] The present embodiment continues to provide the following examples based on specific experiments.

[0102] Example 1

[0103] Two hollow structures were laser-engraved into a nickel-titanium shape memory alloy tube with an outer diameter of 0.2 mm and an inner diameter of 0.1 mm, forming two ribs. The circumferential width of the ribs and the spacing between them were both 1 / 4 of the tube's circumference. The ribs were 2.0 mm long and cut at 0.5 mm and 2.5 mm at each end, respectively, to produce a 5.0 mm long drain material. A 1.1mm outer diameter stainless steel wire was inserted into the hollow structure to support the expansion of two ribs. The structure was heat treated at 500°C for 15 minutes and then water-quenched. After removing the stainless steel wire, a two-dimensional planar expansion fixture tubing with two expansion ribs was obtained. The tubing was pickled in a solution primarily composed of hydrofluoric acid and nitric acid to remove the oxide scale formed during the heat treatment. The tubing was then electrochemically polished using an electrochemical workstation in a polishing solution primarily composed of glacial acetic acid, ethanol, ethylene glycol, and perchloric acid. After cleaning, a drain device with a two-dimensional planar expansion fixture was obtained. The two-dimensional planar expansion fixture was integrated with the drainage body. The drain body had an outer diameter of 0.2mm, an inner diameter of 0.1mm, a total length of 4.6mm, a distal length of 2.5mm, a proximal length of 0.5mm, and an expansion diameter of 1.2mm. The drain device exhibited good elasticity and a phase transition temperature of 28°C.

[0104] The drainage device in this embodiment can be released in situ into the eye using the delivery system in this embodiment. The delivery system uses a 25G normal-wall needle (0.50mm outer diameter, 0.24mm inner diameter) with a blunt tip. The initial length of the needle protruding from the housing is 6mm, and the final length (with the needle retracted and the drainage device implanted) is 1mm, meaning the maximum length of the button retracted is 5mm. The delivery system has a 0.20mm outer diameter ejector pin, which extends 2mm beyond the housing. The total length of the delivery system is 100mm, with a maximum outer diameter of 22mm.

[0105] Use a 25G normal wall needle (0.50mm outer diameter, 0.24mm inner diameter) to push the drain into the conical fixture, compress and expand the fixture, and move it in the desired direction ( Figure 11A 、 Figure 11D ) is inserted into the puncture needle. The distal end of the assembled drain protrudes 1.0 mm from the puncture needle. When no external force is applied, the drain can maintain its relative position to the puncture needle.

[0106] After cleaning and sterilization, the drain and delivery system were implanted into the rabbit eye according to the operation steps. The delivery system functioned normally, the operation was convenient, and the positioning was accurate. The drain was successfully implanted in the expected position. The results of the one-month follow-up showed that the drainage function of the drain was normal and the tissue biocompatibility was good; the AS-OCT images at one month of follow-up ( Figure 13) showed that the drain did not move and the ciliary body dissociation effect of the dilator was obvious.

[0107] Example 2

[0108] Two hollow structures were laser engraved on a nickel-titanium shape memory alloy tube with an outer diameter of 0.3mm and an inner diameter of 0.2mm, forming two ribs. The circumferential width of the ribs and the spacing between them were both 1 / 4 of the circumference of the tube. The ribs were 2.0mm long and cut at 0.30mm on both ends to obtain a fixed structure raw material with a length of 2.6mm. A stainless steel wire with an outer diameter of 1.1mm was inserted into the hollow structure to support the expansion of the two expansion ribs. After heat treatment at 500℃ for 15 minutes and water quenching, the stainless steel wire was removed to obtain a two-dimensional planar expansion fixture with two expansion ribs. The total length of the expansion fixture was 2.2mm and the expansion diameter was 1.2mm.

[0109] A nickel-titanium shape memory alloy tubing with an outer diameter of 0.2 mm and an inner diameter of 0.1 mm was cut into short sections of 4.5 mm in length to form the drainage body of the drainage device. This was inserted into the lumen of the two-dimensional planar expandable fixture, and the distal end was adjusted to 2.0 mm in length (i.e., the distance between the drainage body and the fixture end was 1.7 mm). A laser welder was used to spot weld one end of the expandable fixture (the other end was free to slide the fixture on the drainage body), resulting in a combined drainage body and fixture. The assembly is pickled in a pickling solution with hydrofluoric acid and nitric acid as the main components to remove the oxide scale formed during the heat treatment and welding process, and then electrochemically polished using an electrochemical workstation in a polishing solution with glacial acetic acid, ethanol, ethylene glycol and perchloric acid as the main components. After cleaning, a drain with a two-dimensional planar expansion fixture is obtained, wherein the two-dimensional planar expansion fixture and the drainage body are an assembly, the outer diameter of the drainage body of the drainer is 0.2mm, the inner diameter of the drainage body is 0.1mm, the total length is 4.5mm, the distal end length is 2.0mm, the proximal end length is 0.9mm, the expansion diameter of the expansion fixture is 1.2mm, and the drain has good elasticity.

[0110] The drainage device in this embodiment can be released in situ into the eye using the delivery system in this embodiment. The delivery system uses a 23G thin-walled needle (0.60mm outer diameter, 0.37mm inner diameter) with a blunt tip. The initial puncture needle extends 5mm beyond the housing, while the final state (with the needle retracted and the drainage device implanted) extends 1mm beyond the housing, meaning the maximum length of the button retracted is 4mm. The delivery system has a 0.30mm outer diameter ejector pin, which extends 2mm beyond the housing. The total length of the delivery system is 100mm, with a maximum outer diameter of 22mm.

[0111] Use a 25G normal wall needle (0.50mm outer diameter, 0.24mm inner diameter) to push the drain into the conical fixture, compress the fixture, and move it in the desired direction ( Figure 11A 、 Figure 11D ) is inserted into the puncture needle. After assembly, the distal end of the drain protrudes 1.5 mm from the puncture needle. When no external force is applied, the drain can maintain its relative position to the puncture needle.

[0112] After cleaning and sterilization, the drain device and delivery system were implanted into the rabbit eye according to the procedure. The delivery system functioned normally, was easy to operate, and accurately positioned, successfully placing the drain device in the intended location. A one-month follow-up showed that the drain device maintained normal drainage function, had not shifted, and had good tissue biocompatibility.

[0113] Example 3

[0114] Three hollow structures were laser-engraved into a nickel-titanium shape memory alloy tube with an outer diameter of 0.2 mm and an inner diameter of 0.1 mm, forming three ribs. The circumferential width of the ribs and the spacing between them were both 1 / 6 of the tube's circumference. The ribs were 1.7 mm long and cut at 1.0 mm and 2.0 mm, respectively, to produce a 4.7 mm long drain material. The raw material was inserted into a mold, axially compressed by 0.2 mm, expanded by three ribs, and then fixed. The material was heat-treated at 500°C for 15 minutes and then water-quenched. After removing the mold, a three-dimensional expansion fixture tubing with three expansion ribs was obtained. The tubing was pickled in a solution primarily composed of hydrofluoric acid and nitric acid to remove the oxide scale formed during the heat treatment. The tubing was then electrochemically polished using an electrochemical workstation in a polishing solution primarily composed of glacial acetic acid, ethanol, ethylene glycol, and perchloric acid. After cleaning, a drain device with a three-dimensional expansion fixture was obtained. The three-dimensional expansion fixture was integrated with the drain body. The drain body had an outer diameter of 0.2 mm, an inner diameter of 0.1 mm, a total length of 4.5 mm, a distal length of 2.0 mm, a proximal length of 1.0 mm, and an expanded diameter of 0.8 mm. The drain device exhibited good elasticity and a phase transition temperature of 28°C.

[0115] The drainage device in this embodiment can be released in situ into the eye using the delivery system in this embodiment. The delivery system uses a 25G normal-wall needle (0.50mm outer diameter, 0.24mm inner diameter) with a blunt tip. The initial length of the needle protruding from the housing is 6mm, and the final length (with the needle retracted and the drainage device implanted) is 1mm, meaning the maximum length of the button retracted is 5mm. The delivery system has a 0.20mm outer diameter ejector pin, which extends 2mm beyond the housing. The total length of the delivery system is 100mm, with a maximum outer diameter of 22mm.

[0116] Use a 25G normal-wall needle (0.50mm outer diameter, 0.24mm inner diameter) to push the drain into the tapered fixture. Compress the retainer and insert it into the needle in the desired orientation (distal end outside the needle). The distal end of the drain should protrude 1.0mm from the needle after assembly. The drain should maintain its relative position to the needle when not subjected to external forces.

[0117] After cleaning and sterilization, the drain device and delivery system were implanted into the rabbit eye according to the procedure. The delivery system functioned normally, was easy to operate, and accurately positioned, successfully placing the drain device in the intended location. A one-month follow-up showed that the drain device maintained normal drainage function, had not shifted, and had good tissue biocompatibility.

[0118] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0119] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0120] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0121] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0122] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0123] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An ophthalmic minimally invasive drainage device with expansion and fixation function, characterized in that: The ophthalmic minimally invasive drainage device comprises a drainage body having a hollow cavity and an expansion fixer connected to the drainage body, wherein: The minimally invasive ophthalmic drainage device is made of nickel-titanium shape memory alloy, and the drainage body and the expansion fixator are formed in one piece or in a split combination; the drainage body includes a proximal portion and a distal portion away from the proximal portion; the expansion fixator has a first end and a second end, the first end is connected to the proximal portion of the drainage body, and the second end is connected to the distal portion of the drainage body; The proximal portion of the drainage body is the end close to the suprachoroidal space, and its length is 0.2-2.5 mm. The distal portion of the drainage body is the end close to the anterior chamber of the eye, and its length is 0.5-3.0 mm. The outer diameter of the drainage body is 0.15-0.6 mm, and the inner diameter of the drainage body is 0.05-0.4 mm. The total length of the ophthalmic minimally invasive drainage device is 2.5-7 mm. The expandable fixture is in a two-dimensional plane shape and includes two expansion ribs symmetrically arranged about the drainage body. The two-dimensional expansion plane formed by the two expansion ribs has a first expansion diameter of 0.6-2.0 mm. The length of the expandable fixture is 0.9-2.2 mm. Alternatively, the shape of the expansion fixator is three-dimensional, and the expansion fixator includes three expansion ribs evenly arranged along the circumference of the drainage body. The three-dimensional expansion structure composed of the three expansion ribs has a second expansion diameter, the second expansion diameter is 0.4-1.2 mm, and the length of the expansion fixator is 0.8-1.8 mm.

2. The ophthalmic minimally invasive drainage device with expansion and fixation function according to claim 1, characterized in that: When the shape of the expansion fixator is a two-dimensional plane, the first expansion diameter is 0.8-1.5 mm.

3. The ophthalmic minimally invasive drainage device with expansion and fixation function according to claim 1, characterized in that: When the drainage body and the expansion fixer are composed of a split combination, the drainage body is a drainage tube with an inner cavity; the first end and the second end of the expansion fixer are respectively sleeved on the outer wall of the drainage tube, and any one of the first end and the second end is fixedly connected to the outer wall of the drainage tube, and the other end is a free sliding end.

4. The ophthalmic minimally invasive drainage device with expansion and fixation function according to claim 1, characterized in that: When the shape of the expansion fixator is three-dimensional, the second expansion diameter is 0.6-0.8 mm.

5. The ophthalmic minimally invasive drainage device with expansion and fixation function according to claim 1, characterized in that: in, The length of the two-dimensional planar expander is 1.0-1.8 mm; or the length of the three-dimensional expander is 1.0-1.5 mm; or the two-dimensional planar expander or the three-dimensional expander is configured to dissociate the ciliary body so that the aqueous humor drained from the anterior chamber enters the suprachoroidal space and is then absorbed through the sclera or ciliary choroidal blood vessels.

6. A delivery system for delivering the ophthalmic minimally invasive drainage device with expansion and fixation function according to any one of claims 1 to 5, characterized in that: The delivery system includes a puncture needle, a needle seat, a housing, an ejector pin, a tailstock, a button, and a spring; The puncture needle is fixedly connected to the needle seat, and the needle seat is arranged in the shell and can move forward and backward relative to the shell; the puncture needle includes a first cylindrical inner cavity for loading the ophthalmic minimally invasive drainage device; The ophthalmic minimally invasive drainage device can be elastically compressed and loaded into the first cylindrical inner cavity; the puncture needle is arranged at the front end of the shell, and at least a portion of the puncture needle is inserted into the interior of the shell; The button is connected to the needle seat and cooperates with the housing; the spring is arranged between the button and the needle seat; the button can push the needle seat to move forward and backward relative to the housing; the button and the housing have a first state and a second state; in the first state, the button and the housing form a limit to prevent the needle seat from moving; in the second state, the button releases the limit relationship with the housing; The ejector pin is fixedly connected to the tail stock, and the outer diameter of the ejector pin is slidably matched with the inner diameter of the puncture needle. The ejector pin is used to support the ophthalmic minimally invasive drainage device with expansion and fixation functions, and the tail stock is fixedly connected to the shell; the outer diameter of the puncture needle is 0.4-0.8mm, and the inner cavity diameter of the puncture needle is 0.18-0.61mm. When in use, the expansion fixator is completely compressed and installed into the rigid puncture needle, and the length of the distal end of the drainage body exposed from the puncture needle is 0.5-3.0mm.

7. The delivery system according to claim 6, wherein The tailstock includes a blind hole that cooperates with the ejector pin and a first locking structure that cooperates with the housing. The first locking structure is a threaded structure or a snap-fit structure. The tailstock is fixedly connected to the housing through the first locking structure. The puncture needle is made of stainless steel or nickel-titanium shape memory alloy, the needle seat, shell, tail seat and button are made of resin, and the ejector pin and spring are made of stainless steel.

8. The delivery system according to claim 7, wherein The shell includes a second cylindrical inner cavity that slides with the puncture needle, a shell inner cavity that slides with the outer surface of the needle seat, a first shell inner cavity surface and a second shell inner cavity surface that slides with the outer surface of the button, and a second locking structure that cooperates with the first locking structure.

9. The delivery system according to claim 8, wherein The needle seat has a third cylindrical inner cavity with the same axis as the puncture needle and slidingly cooperates with the ejector pin. The needle seat has a rectangular outer surface that slides with the inner cavity of the shell, and a first needle seat inner cavity surface and a second needle seat inner cavity surface that slides with the outer surface of the button. The first needle seat inner cavity surface and the second needle seat inner cavity surface are arranged to form a button installation cavity. The needle seat has a cylinder that is fixedly cooperated with the inner surface of the spring, and the cylinder is arranged in the button installation cavity.

10. The delivery system according to claim 9, wherein The button includes a second button outer surface that slides with the inner cavity surface of the first needle seat, a first button outer surface that slides with the inner cavity surface of the second needle seat, a third button outer surface that slides with the inner cavity surface of the first shell, a fourth button outer surface that slides with the inner cavity surface of the second shell, and a button inner cavity surface that is fixedly matched with the spring; The width of the first shell inner cavity surface is greater than the width of the second shell inner cavity surface, and the diameter of the second button outer surface is greater than the width of the second shell inner cavity surface, so that in the first state, the second shell inner cavity faces the second button outer surface to form a locking limit; The diameter of the outer surface of the fourth button is smaller than that of the outer surface of the second button and smaller than or equal to the width of the inner cavity of the second shell, so that the outer surface of the fourth button can slide relatively along the inner cavity of the second shell in the second state.

11. The delivery system according to claim 10, wherein The needle tip of the puncture needle is a rounded blunt needle; The spring comprises an outer spring surface fixedly matched with the inner cavity surface of the button and an inner spring surface fixedly matched with the outer surface of the cylinder of the needle seat.

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