Patent Publication Number: US-2023149214-A1

Title: Device and method for creating a channel in soft tissue

Description:
RELATED APPLICATIONS 
     This application is a continuation of and claims priority to U.S. application No. 17/828,749, filed May 31, 2022, which is a continuation of and claims priority to U.S. application No. 16/493,686, filed Sep. 12, 2019, which is a U.S. National Stage application from and claims priority to PCT Application No. WO2018IL50412, filed Apr. 9, 2018, which claims priority from IL application No. 251684 filed on Apr. 9, 2017 and U.S. provisional application No. 62/595,172 filed on Dec. 06, 2017, all of which disclosures are herein incorporated by reference. 
    
    
     TECHNOLOGICAL FIELD 
     The present invention is in the medical field and relates specifically to surgical devices, and more specifically to miniature surgical cuttings tools. 
     BACKGROUND 
     Removing tissue from the body is solicited in various scenarios including for diagnosis or treatment purposes. For example, in biopsy procedure, a sufficiently small tissue specimen is acquired in order to undergo examination outside the body. Usually, the shape of the specimen or the cavity left at the site of the removed tissue have low or no importance, the body heals from the injury leaving apparently no traces. In another example, tissue is removed in order to create paths for drainage of excessive liquids such as in Glaucoma condition (excessive intra ocular pressure). 
     Several surgical procedures are practiced to treat Glaucoma and/or elevated intra-ocular pressure (IOP). Filtering surgeries are used to gain access to the inner layers of the eye in order to create a drainage channel from the anterior chamber to the external surface of the eye under the conjunctiva, allowing aqueous humor to seep into a bleb from which it is slowly absorbed. Filtering surgeries are divided into either penetrating or non-penetrating types depending upon whether an intraoperative entry into the anterior chamber occurs. Scar formation at the site of operation may block aqueous humor circulation. Surgical adjuvants may be used to facilitate healthy tissue regeneration and keep created drainage channels functional. 
     Trephination to create αb interno sclerostomies was reported by Brown et al (Brown RH, Lynch MG, Denham DB, et al. Internal sclerectomy with an automated trephine for advanced glaucoma. Ophthalmology 1988; 95:728-734), and by SHIHADEH et al (Wisam A. Shihadeh, MD, Robert Ritch, MD, Jeffrey M. Liebmann, MD. Rescue of failed filtering blebs with ab interno trephination. Cataract Refract Surg 2006; 32:918-922), as a way of performing filtering procedures, after failure of other procedures due to blocking, while maintaining the integrity of the overlying conjunctiva at the treated site. 
     GENERAL DESCRIPTION 
     The present invention provides a novel technique for removal of tissue from the body. The technique of the present invention is particularly effective and useful in the controlled removal of soft tissue, e.g. by creating a well-defined, timely-controlled channel inside tissue. The technique of the present invention also provides for verifying the channel’s creation and its dimensions, without a need for using external verification techniques such as imaging, by retrieving and preserving the shape of the tissue removed. It should be noted that a “channel” as used herein means a pathway created in the tissue after removal of a corresponding tissue piece from the body. No parts, such as implant(s), are left in the body to create or maintain the integrity of the channel. Other expressions that are used interchangeably herein are “hole”, “void” and “pathway”. Specifically, the unique technique allows for controllably creating a channel in one or more adjacent target tissue layers being part of a multilayered tissue structure while preserving the one or more tissue layers covering/preceding and/or following the target tissue layer(s). Further, the unique technique provides the user with on-line feedback referring the success of the channel creating procedure by verifying the removed tissue volume and shape. The length and/or the diameter, of the removed tissue (e.g. having a cylindrical shape) matches/indicates about the length and/or diameter of the created channel. Minimizing the applied deformation on the removed tissue keeps it as close as possible to its original length and/or diameter, thereby providing improved and better real time feedback. 
     It is noted that the words “tissue layer” as used herein can mean a single tissue layer or a group of layers such as adjacent stacked layers (a multilayer) or a group of distinct layers. However, generally, the single tissue layer is the default meaning. Also, the “tissue layer” refers often to a tissue wall having a specific thickness and two sides (outer and inner, or proximal and distal) such that the channel/hole created therein extends between the two sides of the tissue wall. 
     For example, the channel may be a channel in the sclero-corneal junction of a subject’s eye, which may be used to treat glaucoma by reducing intraocular pressure through providing fluid communication between the anterior chamber of the eye and the interface between the episclera and the conjunctiva tissues. 
     In the above-described literature (Brown et al and Shihadeh et al), the Ab interno trephination technique involve invasively introducing the surgical device into the anterior chamber of the eye through an incision made in the cornea opposite to the site of channel creation. This procedure is demanding, it depends heavily on the expertise of the surgeon and on the ability to accurately visualize the route of the surgical device inside the anterior chamber parallel to the iris into the filtration angle. It is also risky to vital organs such as the iris and lens as well as the angle structures that cannot be directly visualized unless an additional gonioscopic lens is used. This intraoperative gonioscopic lens is only rarely used even by glaucoma surgeons. 
     In contrast, the present invention provides a safe, minimally-invasive (Ab externo) and blazingly fast (in the order of seconds), highly-effective technique. As such, the present invention provides an opportunity for combined surgery by combining several surgical operations, for example combining treatment of high intraocular pressure according to the invention, together with cataract surgery, thus saving time and effort from both the surgeon and the patient. 
     Although, as described above, the present invention is advantageous in its Ab externo application, the device of the present invention can also be safely and effectively applied in Ab interno procedure, because as will be further detailed below, the device includes an outer part that functions as a protector that is configured to protect organs of the eye, including internal organs, such as the iris, when utilized in Ab interno configuration. 
     At different sites in the body, the target tissue in which the channel has to be made underlies or precedes other tissue(s). In such a situation, the challenge is even greater because harm to the surrounding tissue(s) or adjacent should be avoided. One example is creating a channel in the sclera while keeping the conjunctiva intact. The medical device of the present invention is configured, in the Ab externo application, to optimize the remote penetration through the outer, first, tissue (e.g., conjunctiva) followed by cutting inner, second, tissue (e.g., sclera) to form a channel, while the minimal force possible is applied, such that the hole created in the upper tissue (conjunctiva) heals almost immediately leaving no traces. On the other hand, in the Ab interno application, the device, while being actually inserted into the anterior chamber of the eye, its construction and way of action ensure that no harm is caused to other organs, including the outer conjunctiva, while it creates a channel in the scelra tissue from inside. 
     Further, the medical device of the present invention is configured for easy automatic or semi-automatic operation, relieving burden from surgeon and providing him continuous feedback over the whole surgical procedure. The technique of the present invention aids the surgeon in safe positioning of the device inside the tissue to be cut while still allowing him/her control over the channel’s three-dimensional orientation. 
     Moreover, the device of the present invention may incorporate authentication or validation features by retaining form/specimen of tissue removed from the body during the channel creation. The shape of the cutting tool of the device also provides enhanced trapping of the removed tissue within the cutting tool and prevents or minimizes the chances of leaving the removed tissue within the tissue wall such as the eye wall. 
     The channel created by the technique of the present invention is advantageous, for example in comparison to other techniques that leave implant(s) inside the tissue so to insure the drainage of fluid, because nothing is left in the tissue, except for the created void/hole/channel extending between the two side walls of the specific target tissue layer or multilayer, as the case may be. In other words, the created channel is a hole through the tissue with no artificial tube/shunt left inside the target tissue at all. Therefore, the created channel can be dynamic acting as a pressure regulator, i.e. it can regulate its drainage capacity by changing its size based on the pressure acting on its both ends. When the pressure gradient increases the channel opens/increases its size accordingly, and when the pressure gradient decreases the channel closes/decreases its size accordingly. 
     The range of sizes of the channel can be controlled by the geometry and size of the device that creates the channel. In the specific example of creating a channel in the eye wall, to treat elevated IOP for example, the present invention is advantageous in achieving the channel creation and verification in the micro scale, as the desired dimensions of the drainage channel are typically about 0.1-0.2 mm in diameter and 1-1.5 mm in length, supposing a substantially cylindrical shape for the channel and the matching removed tissue. The present invention accomplishes the targets above in the micro level while overcoming the limitations of the currently available techniques. Inter alia, available techniques may be used to produce tools having tissue receiving cavities of up to about 0.5 mm length with the required above-mentioned diameter. However, this is not suitable for creating a substantially cylindrical channel within the eye wall that has a 1.5 mm length. The technique of the present invention enables creating cutting tools with micro-scale desired dimensions in diameter and length, thereby enabling to preserve the shape of the removed tissue to be used for verification of the channel creation. 
     Generally, the medical device of the present invention is configured to operate in three distinct phases, a positioning phase characterized by an essentially linear advancement of the device along its linear longitudinal axis through one or more tissue layers until reaching the target tissue and stabilizing there inside the target tissue by an anchoring/sticking portion of an outer part of the device, a channeling phase during which an inner rotatable cutting tool of the device is rotated around its linear longitudinal rotation axis and then advanced to project from the outer part of the device and progress inside the target tissue to cut tissue of the target tissue and create the channel with the desired dimensions (diameter, cross-section area, length...), and a withdrawal phase in which the inner rotatable cutting tool is withdrawn from the target tissue into the outer part of the device and the whole device is retracted from the body. The withdrawal phase may be with or without rotation of the inner rotatable cutting tool depending, inter alia, on the tissue characteristics (kind, stiffness, region in the body), the time of operation and the desired channel shape. Typically, the outer part does not rotate during any of the phases and it only moves straight forwards and backwards on the linear longitudinal axis of the device. Generally, the outer part functions as a protective shaft, that protects the surrounding tissue during advancement of the device until reaching the target tissue, and as a stabilizing part such that its front (distal) portion is inserted /anchored/stuck in the target tissue to enable stable activation and performance of the inner rotatable cutting tool during the channeling phase. 
     Thus according to an aspect of the invention, there is provided a medical device for removing a predetermined shape of soft tissue from a target tissue layer thereby leaving a matching channel with predetermined geometry and orientation between two side walls of the target tissue layer, the device comprises coaxial outer and inner elongated members extending along axis X;
     said outer member comprises an open distal side and a first distal part configured for sticking to said target tissue layer (or multilayer), during forward axial movement;   said inner member comprises a second distal part configured to rotate and project distally through said open distal side to said predetermined shape of the soft tissue from the target tissue layer and create said channel formed as a hole through the target tissue layer or multilayer.   

     In some embodiments, the first distal part is configured for penetrating at least one other tissue layer preceding the target tissue layer during the forward axial movement. 
     In some embodiments, the first distal part comprises a tissue piercing tip at its distal end configured and operable to penetrate said at least one other tissue layer and said target tissue layers and a proximal portion at its proximal side configured and operable to penetrate said at least one other tissue layer and to stop at said target tissue layer, thereby sticking said outer member in the target tissue layer. 
     In some embodiments, said first distal part has a mid-portion between said tip and said proximal portion having a shape and an orientation that complement a shape and an orientation of said second tissue layer. 
     In some embodiments, the first distal part has a predefined length such that said tip does not exit distally from said target tissue layer. 
     In some embodiments, the proximal portion is a rim of said outer member, formed by cutting a section of wall of the outer member along said axis X. 
     In some embodiments, the inner member is fixedly attached to and housed within said outer member during said forward axial movement of the outer member. 
     In some embodiments, the outer member is manually moved during said forward axial movement until its said sticking in the second tissue layer. 
     In some embodiments, the inner member, while rotating, is manually moved along said axis X to create the channel. 
     In some embodiments, the device comprises a constant-force moving mechanism configured and operable to move said inner member, while rotating, along said axis X under a constant force. In some other embodiments, the device comprises a constant rate moving mechanism configured and operable to move said inner member, while rotating, along said axis X with a constant rate. 
     In some embodiments, the device comprises an electric motor configured and operable for axially moving and / or rotating said inner member. 
     In some embodiments, the device comprises a cavity for collecting tissue cut from said target tissue layer during creation of said channel. In some embodiments, the cavity is located within said inner member. In some embodiments, the cavity is located in a space between said inner and outer members. 
     In some embodiments, the second distal part of said inner member is open at its distal end and comprises a round cutting edge configured to attach to and cut soft tissue while rotating. The inner member may comprise a chamber for retaining a full shape of tissue cut from said second tissue layer during creation of said channel. 
     In some embodiments, the inner member comprises:
     an elongated round body extending along a longitudinal axis and having a uniform outer diameter at a proximal side thereof,   a cutting portion at a distal side of the elongated body, comprising at a distal end thereof a round cutting edge of a first diameter being smaller than said outer diameter and a distally and continuously decreasing outer diameter, and   a cavity extending along the longitudinal axis inside the cutting tool from said cutting portion, the cavity having dimensions matching said soft tissue shape,   wherein said tissue shape is cylindrical and has a length of about 1.5 mm and a diameter of between about 0.1 mm and about 0.2 mm.   

     In some embodiments, the inner member comprises:
     an elongated round body extending along a longitudinal axis and having a uniform outer diameter at a proximal side thereof,   a cutting portion at a distal side of the elongated body, comprising at a distal end thereof a round cutting edge of a first diameter being smaller than said outer diameter and a distally and continuously decreasing outer diameter, and   a cavity extending along the longitudinal axis inside the cutting tool from said cutting portion, the cavity having a length of at least the length of the removed tissue,   wherein said cavity has a cavity diameter smaller than said first diameter at a distal end of the cavity and which increases continuously towards a proximal end of the cavity.   

     In some embodiments, the inner member comprises:
     an elongated round body extending along a longitudinal axis and having a uniform outer diameter at a proximal side thereof,   a cutting portion at a distal side of the elongated body, comprising at a distal end thereof a round cutting edge of a first diameter being smaller than said outer diameter and a distally and continuously decreasing diameter, and   a cavity extending along the longitudinal axis inside the cutting tool from said cutting portion, the cavity having a length of at least the length of the removed tissue,   wherein said cavity has a constant cavity diameter being equal to said first diameter, and wherein said first diameter is between about 0.1 mm to about 0.2 mm.   

     In some embodiments, the inner member comprises a tissue trapper comprising a slit formed in a wall of the body of the inner member along at least part of said cavity. In some embodiments, the slit is formed by tangential cutting of the wall of the body of the inner member, said device thereby further comprising an outer cavity located between the inner and outer members. In some embodiments, the slit is formed by radial cutting of the wall of the inner member. 
     In some embodiments, the second distal part of said inner member is configured as a drill bit configured for removing soft tissue. 
     In some embodiments, the rotating of said second distal part comprises clockwise and anti-clockwise reciprocal movement. 
     In some embodiments, the tissue piercing tip is configured as a lancet. 
     In some embodiments, the first distal part of the outer member is formed by cutting the outer member in the direction of the axis X along a curved line chosen to provide smooth penetration, at a distal segment of the first distal part, with increasing resistance-to-progression force, at a proximal segment of the first distal part. 
     In some embodiments, the at least one other tissue layer comprises the conjunctiva and / or the tenon and said target tissue layer is the episclera and/or the sclera and/or the cornea of an eye. 
     In some embodiments, the predetermined geometry of the channel is selected to enable pressure regulation of a treated eye over a predetermined time period. 
     According to yet another aspect of the invention, there is provided a cutting tool for removing a portion of soft tissue from a target tissue layer in an eye while being rotated and progressed, thereby creating a channel between two side walls of the target tissue layer enabling fluid to pass through the channel, the cutting tool comprising:
     an elongated round body extending along a longitudinal axis and having a uniform outer cross-section at a proximal side thereof,   a cutting portion at a distal side of the elongated body, comprising at a distal end thereof a cutting edge of a first cross-section being smaller than said outer cross-section, and a distally and continuously decreasing outer cross-section, and   a chamber extending along the longitudinal axis inside the cutting tool from said cutting portion, the chamber having dimensions enabling storing of the removed soft tissue portion inside the chamber thereby providing a validation to the channel creation.   

     In some embodiments, said chamber has a chamber cross-section smaller than said first cross-section at a distal end of the chamber and which increases continuously towards a proximal end of the chamber. 
     In some embodiments, said chamber has a constant chamber cross-section being equal to the first cross-section. 
     In some embodiments, said first cross-section is circular having a diameter between about 0.1 mm to about 0.2 mm. 
     In some embodiments, said removed soft tissue portion is substantially cylindrical with a cross-section having a diameter of between about 0.1 mm to about 0.2 mm. 
     In some embodiments, said removed soft tissue portion has a length of up to 1.5 mm. 
     In some embodiments, said chamber has a length of up to 1.5 mm. 
     In some embodiments, an inner surface of the chamber is coated with a friction-lowering composition. 
     According to yet another aspect of the invention, there is provided a method for producing a cutting tool used in cutting soft tissue, the cutting tool comprising a distal cutting portion having at a distal end thereof a round cutting edge of a first diameter and a cavity extending for a predetermined length along a longitudinal axis of the cutting tool from said cutting portion and comprising a cavity diameter being either constant or increasing proximally along the predetermined length, the method comprising:
     providing a tool comprising at a distal side thereof a hollow cylinder having uniform outer and inner diameters and extending along at least said predetermined length, wherein said inner diameter is larger than said first diameter,   shaping a distal portion of the hollow cylinder with a predetermined pattern such that both said inner and outer diameters decrease towards a distal end of the hollow cylinder and such that said first diameter is larger than said inner diameter and is smaller than said outer diameter at the distal end, and   removing a slice of the hollow cylinder along said distal portion, such that the inner diameter at the distal end is substantially equal to said first diameter and the inner diameter at a proximal end of the distal portion is substantially equal to said cavity diameter.   

     In some embodiments, said shaping of the distal portion is carried out by swaging and/or spinning technique(s). 
     In some embodiments, said shaping of the distal portion is carried out by tapering technique. 
     In some embodiments, said predetermined pattern is linear. 
     In some embodiments, said predetermined pattern is non-linear. 
     In some embodiments, said cavity diameter is equal to said first diameter. 
     In some embodiments, the method further comprising: sharpening said round cutting edge from an internal side of the cutting portion, thereby providing that the cavity diameter at a proximal end of the cutting portion being smaller than the first diameter. In some embodiments, said cavity diameter increases proximally. 
     In some embodiments, the method further comprising coating an inner surface of said cavity with a friction-lowering composition. 
     In some embodiments, said predetermined length is at least 1.5 mm. In some embodiments, said cavity diameter at a proximal side of the cavity is between 0.1 mm and 0.2 mm. 
     In some embodiments, said uniform outer and inner diameters of the hollow cylinder are about 0.3 mm and 0.16 mm respectively. 
     In some embodiments, after shaping, said outer and inner diameters of the hollow cylinder at the distal end are about 0.27 mm and 0.13 mm respectively. 
     In some embodiments, said distal portion of the hollow cylinder has a length along the longitudinal axis of between about 1 mm to about 2 mm. According to yet another aspect of the present invention, there is provided a cutting tool for removing a predetermined shape of soft tissue while revolving and progressing, thereby leaving a matching channel between two walls of the soft tissue, the cutting tool being produced according to the method described above. 
     According to yet another aspect of the invention there is provided a method for removing a portion of soft tissue from a target tissue layer of the eye to enable drainage of excessive fluid from inside the eye, the method comprising:
     providing a device comprising a soft-tissue cutting tool extending along an axis X, the cutting tool comprising an elongated proximal part attached to a proximal handle for gripping the device, a distal part having an open distal end and a distal cutting edge configured to attach to and cut the soft tissue portion, and a chamber extending inside the cutting tool from said open distal end to receive the cut soft tissue portion;   positioning the device at a first point with respect to the eye;   advancing the device along the axis X until contacting said target tissue layer;   rotating and distally progressing at least the distal part of the cutting tool into the target tissue layer to thereby cut and remove the soft tissue portion, extending between two side walls of the target tissue layer, by said distal part of the cutting tool, and storing the removed soft tissue portion in the cavity, thereby creating a channel of a predetermined geometry across the target tissue layer;   retracting at least the distal part proximally out of the target tissue layer; and   withdrawing the device out of the body substantially along the axis X, thereby leaving the created channel allowing the drainage of the excessive fluid therethrough.   

     In some embodiments, the method comprising repeating said positioning, rotating and progressing, and retracting steps for a plurality of times to create a respective plurality of channels at respective plurality of locations at said target tissue layer. 
     In some embodiments, said rotating and progressing are done manually. 
     In some embodiments, said rotating includes reciprocal clockwise and anticlockwise rotations. 
     In some embodiments, the method is done ab interno such that said advancing of the device is done inside the anterior chamber of the eye. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: 
         FIGS.  1 A- 1 B  illustrate a non-limiting exemplary embodiment of a device according to the invention; 
         FIGS.  2 A- 2 B  illustrate another non-limiting exemplary embodiment of a device according to the invention; 
         FIGS.  3 A- 3 E  exemplify a non-limiting technique for creating a channel in soft tissue according to the invention; 
         FIGS.  3 F- 3 I  exemplify another non-limiting technique for creating a channel in soft tissue according to the invention; 
         FIGS.  4 A- 4 D  illustrate non-limiting examples of a part of a device according to exemplary embodiments of the invention; 
         FIG.  5 A -5D3 illustrate non-limiting examples of a part of a device according to the invention; 
         FIG.  5 E 1 - 5 E 7    - illustrate one non-limiting scenario of creating a channel in soft tissue and specifically in the eye wall; 
         FIG.  5 F -5G4 illustrate non-limiting examples of a device and methods for producing the device according to exemplary embodiments of the invention; 
         FIGS.  6 A- 6 D  illustrate a non-limiting example of a manual movement mechanism according to the invention; 
         FIGS.  7 A- 7 D  illustrate another non-limiting example of manual movement mechanism according to the invention; 
         FIGS.  8 A- 8 D  illustrate yet another non-limiting example of manual movement mechanism according to the invention; 
         FIGS.  9 A- 9 E  illustrate a non-limiting example of automatic movement mechanism according to the invention; and 
         FIGS.  10 A- 10 D  illustrate another non-limiting example of automatic movement mechanism according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The present invention provides a technique for creating a well-defined channel in a soft tissue. In one aspect, a medical device for removing a predetermined shape of soft tissue from a target tissue layer (or a first group of target tissue layers) thereby leaving a matching/corresponding channel with predetermined geometry and/or orientation through/between two side walls of the target tissue layer is provided. In some embodiments, such a device can be particularly useful in creating a drainage channel along the whole thickness of the episclera and/or sclera and/or cornea tissue (which will be generally referred to herein, for simplicity, as the sclera), of the eye to thereby treat excessive intraocular pressure. The sclera is covered by the conjunctiva and tenon tissues, such that approaching the sclera from outside requires penetrating the conjunctiva and the tenon. Therefore, the device may be also configured to penetrate through the conjunctiva/tenon before reaching the sclera. 
     Reference is made to  FIGS.  1 A and  1 B  showing a specific, non-limiting, example of a medical device  100  according to some embodiments of the present invention. 
     The medical device  100  is configured for and capable of penetrating through first, upper, tissue layer(s) and creating a channel with predetermined geometry through a consecutive second, lower, target tissue layer. The device  100  includes coaxial outer and inner members,  110  and  120  respectively, extending along axis X, for creating the channel in the target tissue, and possibly penetrating the tissue layer(s) preceding the target tissue layer. The axis X is typically a longitudinal straight axis. The coaxial outer and inner members  110  and  120  are usually made from a hard, tough, material and are therefore rigid and do not bend when pushed/inserted/progressed through at least soft tissue. The coaxial outer and inner members  110  and  120  are mounted, at a proximal side  114 P thereof, on a handle/gripping unit  150  by which the user holds/grips the device  100  and operates it. 
     The outer member  110  includes an open distal side  112 D, a first distal part  112 , and a first proximal elongated part  114 . It is noted that the relative expressions “proximal” and “distal” as used herein, define relative orientation with respect to the user, such that” proximal” denotes the close side to the user and “distal” denotes the far side from the user. The outer member  110  is configured to move axially along the axis X to thereby penetrate soft tissue by its first distal part  112 . The axial movement of the outer member  110  is achieved by user manual operation. As it is manually operated by the user, the outer member  110  can be fixedly/firmly attached, at the proximal side  114 P, to the handle  150 . Alternatively, it can be configured for manual sliding by the user along axis X while not being firmly attached to the handle  150 . Details about the moving mechanism are described herein further below. 
     The first distal part  112  is configured for penetrating and passing through the tissue layer(s) preceding the target tissue layer, if any, during forward axial movement, and therefore it includes a tissue piercing tip  116 , at the distal end of the first distal part  112 , that enables the penetration. It is noted that, as the forward axial movement is manually controlled, the penetration of the preceding tissue layer(s), such as the relatively thin conjunctiva, is enabled by the manual pushing force applied by the user and which can be further facilitated by the manual lifting/pulling of the conjunctiva outwardly towards the user. The first distal part  112  is also configured to pierce the target, typically thicker, tissue layer, and stick into the target tissue layer so as to position the device inside the target tissue in which the channel is to be created, and provide the user with a pivotal point to define the three dimensional orientation of the channel. In addition to its plain name, the first distal part  112  is interchangeably called herein as “sticking part”, “stabilizing part” or “anchoring part”. It should be understood that while the first distal part  112  enters into the target tissue and sticks/anchors therein, it can be withdrawn backwardly by the application of a minimal force and without causing damage to the surrounding tissue. Sticking and/or anchoring as used herein do not mean a permanent state but rather a temporal, transitional state of the position of the first distal part, that gives the user a stable pivotal point of action. 
     The tissue piercing tip  116 , formed at the most distal part of the first distal part  112 , can be configured according to the known in the art, e.g. as done with conventional medical needles. Accordingly, the tissue piercing tip  116  can include, for example, a beveled lancet structure. Yet, it can have other configurations, as will be further described below with reference to  FIGS.  4 A to  4 D . 
     The first proximal elongated part  114  is hollow, e.g. a hollow tube, enclosing and housing the inner member  120  there inside. Typically, the first proximal elongated part  114  has a cylindrical shape with a circular (round) or substantially circular transverse outer cross section. The first proximal elongated part  114  is configured to penetrate soft tissue smoothly and easily with minimum force, therefore it can have circular outer cross section and can be provided with a smooth (polished) outer surface to minimize friction during penetration into tissue. The inner cross section of the first proximal elongated part  114  is circular or has other shape that matches the outer surface of the inner member  120  enclosed therein. 
     The inner member  120  includes a second distal part  122  and a second proximal elongated part  124 . The second distal part  122  is configured to project distally through the open distal side  112 D, approaching the target tissue while rotating, to thereby cut a predetermined shape of the target tissue and create the channel with the predetermined geometry and orientation in the target tissue, while the first distal part  112  is substantially positioned inside the target tissue as described above and as will be further exemplified below with reference to  FIGS.  3 A to  3 I . In general, the second distal part  122 , at its distal end, is configured to provide effective attachment to the target tissue and to cut the target tissue while rotating. To this end, the distal end of the second distal part  122  can be provided with a cutting edge, a punching mechanism and the like, as will be further described below. 
     Generally, the device  100  includes a cavity/chamber  126  configured to collect the removed tissue therein, such that no tissue is left in the body. In some embodiments, the cavity/chamber is located inside the second proximal elongated part  124 , as exemplified in  FIG.  1 B . In some other embodiments, the cavity/chamber  126  can be located in a space between the outer and inner members  110  and  120 . 
     The device  100 , including the handle  150  may be configured for single use, being disposable, therefore enhancing and maintaining safety and sterility of the device. The handle  150  can be configured as described in PCT/IL2016/051063 assigned to the assignee of the present invention. 
     The moving mechanism  140  is configured to enable axial movement of the outer member  110 , forwards (distally) and backwards (proximally), and both axial and rotational movement of the inner member  120 . The moving mechanism  140  can have manual (by the user) and/or automatic (by the use of mechanical and/or electrical means, such as a spring and/or a motor) operational modes for each of the movements it is capable of. The rotational movement of the inner member  120  can be in full or partial circles or rounds, clockwise and/or anticlockwise, and/or in reciprocal movement. 
     The construction and dimensions of the device can be costumed to match the application, the tissue properties, and anatomy and morphology of the site of body in which the channel is created. 
     For example, if used to create a drainage channel in the human eye, the dimensions of the device can be as follows: 
     The external diameter of the outer member is chosen to enable smooth and safe penetration into and withdrawal from tissue, while maintaining a minimal strength such that it does not break in the tissue during operation. It can be about 0.4 - 1.2 mm. 
     The overall length of the outer member is chosen to enable easy and safe access to the surgery site. It can be about 8 - 30 mm. 
     The length of the first distal part of the outer member can be chosen to enable insertion/sticking/anchoring of the first distal part into the second tissue, i.e. the sclera in this instance, while assuring that the first distal part does not protrude distally from the sclera, thus minimizing or cancelling invasive entrance into the anterior chamber of the eye. It can be about 0.5 - 3 mm. 
     The external diameter of the inner member is chosen to create the predetermined geometry of the channel, while maintaining a minimal strength such that it does not break in the tissue during operation. It can be about 0.2 - 0.5 mm. 
     The overall length of the inner member is chosen to enable its connection to a moving mechanism at the proximal side while providing sufficient forward distance to create the desired channel length. It can be about 15- 40 mm. 
     The length of the second distal part of the inner member depends on the second distal part’s specific construction that insures the channel creation. 
     During the channel creation, the inner member protrudes/projects from the outer member by about 1 - 4 mm. 
     The inner member’s rotation can be in the range of about 1 - 10,000 rpm. And, the penetration force is about 0.2 - 10 Newton. 
     The resulting channel’s diameter would be about 0.1 - 0.5 mm. 
     Reference is made to  FIGS.  2 A and  2 B . Throughout the text, functional parts which have the same functionality, have the same numbers with difference of one hundred duplicates. For example, the number  210  denotes an outer member and the number  220  denotes an inner member, both configured as at least having the features described above with respect to outer member  110  and inner member  120 , with possibly additional features. In the following various non-limiting embodiments of the device, including its outer and inner members and its moving mechanism will be exemplified. It should be understood, that any combination of one outer member, one inner member and one moving mechanism is equally possible. The shown or described specific examples should not limit the broad aspects of the invention. 
       FIGS.  2 A and  2 B  exemplify a non-limiting example of the device  200  of the invention. In the figures, an outer member  210  and inner member  220  of the device  200  are shown. The outer member  210  and the inner member  220  are configured and operable at least as the outer member  110  and inner member  120  described above.  FIG.  2 A  (as well as  FIG.  1 A ) illustrates the device during the positioning phase, i.e. during inserting the device through the first and second (target) consecutive tissues, in which the outer member  210  leads the device into its position inside the second tissue to be channeled, and the inner member  220  (as well as  110  in  FIG.  1 A ) is housed entirely in the outer member  210 .  FIG.  2 B  (as well as  FIG.  1 B ) illustrates the device during the channeling phase, i.e. during creation of the channel by the rotational and forward movement(s), projection, of the inner member  220 . As shown, the first distal part  212  of the outer member  210  includes a piercing portion / tip  216  at its most distal side, being configured as described above and operable to pierce and penetrate through tissue layer(s) preceding the target tissue, and to pierce, without fully penetrating, the target tissue layer. In addition, the first distal part  212  includes a portion  212 P at its proximal side configured and operable to pierce and penetrate the tissue layer(s) preceding the target tissue layer and to stop at the second (target) tissue layer, i.e. the portion  212 P prevents the outer member  210  from excessively penetrating the second (target) tissue in which the channel is created thereby sticking the outer member  210 , by its distal piercing portion  216 , in the target tissue layer. The portion  212 P is interchangeably called herein as “stopping portion” or “stopper”. 
     In the described example, the stopper  212 P is an integral portion of the outer member  210  formed by a rim of the transverse, round, cross section of the outer member  210  by cutting a section of wall of the outer member  210  substantially along the axis X. Specifically, the section cut is a wall of the cylinder of the outer member  210 , e.g. half of the cylinder of the outer member between its most distal end and up to a proximal point along the outer member. The length of the wall section cut along axis X defines the length of the first distal portion  212  and the latter defines the extent of sticking the outer member  210  into the target tissue such that the distal end of the piercing tip  216  does not protrude/exit distally from the target tissue layer. 
     Reference is made to  FIGS.  3 A to  3 I  exemplifying non-limiting techniques for creating a channel in soft tissue by using the medical device of the invention. The described example relates to creating a channel in the sclera tissue of the eye. However, as has already been said, the invention is not limited to this application and can be practiced at other regions in the body where creation of a controlled channel in a tissue layer preceding/beneath other tissue layer(s) is needed. Specifically, the invention enables channel creation at a region in the body which needs a clear and defined stopping/localization/stabilization feature of the device therein because the region cannot provide this feature; such a region is the soft tissue. The example described in  FIGS.  3 A to  3 E  relates to Ab externo procedure where the device approaches the sclera tissue from outside. A human eye  360  is shown, where a channel should be created at the region of the sclera-corneal junction  362 . The created channel will controllably connect between the anterior chamber  364  of the eye and the sub conjunctival space/zone and hence allow the extra fluid accumulated in the anterior chamber to exit and by this reduce the intraocular pressure. As has been described earlier, the channel size can be controlled by providing a device with specific geometrical dimensions. Also, when used for treating excessive pressure, the size of the created channel is determined based on the magnitude of excessive pressure that should be treated. Higher pressure requires bigger channel and vice versa. The created channel insures effective regulation of pressure such that it expands or contracts between controlled sizes based on the pressure gradient across the channel, i.e. the pressure difference between inside and outside the eye. 
     As shown in  FIG.  3 A , the device  300  approaches the eye from outside where it encounters the outer tissue layer that includes the conjunctiva and/or tenon tissues (366 in  FIG.  3 B ) by the outer member  310 , and precisely by the first distal part  312  of the outer member  310 . The outer member  310  pierces and penetrates the conjunctiva and/or tenon when it is advanced forwardly, typically manually, by the surgeon. 
     As shown in  FIG.  3 B , after or while the device passes the conjunctiva and tenon  366 , the surgeon can pull the conjunctiva  366 , and possibly also the tenon, outwardly by the help of a suitable tool held in his other hand. The conjunctiva tissue, and possibly also the tenon, now wraps the outer member  310  at the first proximal elongated part  314 . This saves the conjunctiva and/or tenon by preventing them from coming into contact with the inner member which will be rotated and advanced to cut and remove sclera tissue. The tissue piercing tip  316  of the outer member  310  now contacts the sclera tissue  368 . 
     As shown in  FIG.  3 C , the outer member  310  is further advanced forwardly, manually, as described above, such that the piercing tip  316  penetrates the sclera tissue  368 . The device, by the first distal part  312  of its outer member  310 , is stuck in (anchored) and stabilized temporarily in the sclera tissue  368 . During advancement inside the sclera tissue  368 , the resistance-to-progression increases and is given as a feedback to the surgeon when he/she manually advances the device. In the case the device is configured with the stopper  312 P, as shown in this specific example, the device  300  comes to a hard stop because the stopper  312 P provides significant increase in resistance-to-progression force on the outer member  310  and prevents the additional penetration/progression inside the sclera tissue  368 . 
     It is appreciated that  FIGS.  3 A to  3 C  illustrate the positioning phase of the device  300  as a preparation for the channeling phase. It is also appreciated, that during the positioning phase, no relative motion between the outer and inner member occurs. Generally, the inner member is hidden inside and fixedly attached to the outer member during the axial movement of the outer member, no matter how the axial movement of the outer member is executed, whether the axial movement includes manual displacement of the outer member by the surgeon relative to the handle, or whether the outer member is fixedly attached to the handle such that the axial movement of the outer member is generated by manual axial movement of the handle by the surgeon. 
     At this point, as shown in  FIG.  3 D  and while the outer member  310  protects the conjunctiva tissue, the inner member  320  is rotated, either mechanically or electrically by a dedicated motor as described above and will be further exemplified below, and is advanced by the applied moving mechanism forwardly such that it contacts and attaches to the sclera tissue  368  and starts with drilling and creating the channel. The advancement distance of the rotating inner member can be configured by the moving mechanism such that the distal end of the inner member  320  does not protrude significantly into the anterior chamber of the eye to avoid causing harm to the internal side of the eye. The inner member  320  is then retracted backwardly (not shown), either rotating or not depending on its configuration, as will be described further below, until it is back in its secured position inside the outer member  310 , and the latter is pulled out from the sclera and conjunctiva tissues by the surgeon. The conjunctival tissue recovers almost immediately and the hole therein, formed by the outer member only, closes. Moreover, as during the positioning phase the surgeon pulls the conjunctiva outwardly, then after releasing the conjunctiva the hole in the conjunctiva will be displaced with respect to the channel in the sclera. As the conjunctiva attaches back to the sclera, the risk of eye collapse due to excessive fluid exiting the eye is prevented. 
       FIG.  3 E  illustrates the created channel  370  after the device is pulled outside the eye. The aqueous humor (the fluid in the anterior chamber) starts to exit the anterior chamber towards the sub-conjunctival space, such that a bleb  372  is formed under the conjunctiva and above the sclera, and the fluid is reabsorbed in the blood vessels at the vicinity thereof. 
     Reference is now made to  FIGS.  3 F to  3 I  exemplifying another non-limiting technique for creating a channel in soft tissue by using the medical device of the invention. The described example relates to creating a channel in the sclera tissue of the eye in Ab interno procedure by approaching the sclera tissue from inside of the eye. As has been mentioned above, the device of the invention is advantageous in that it can be used in either Ab externo or Ab interno procedures. For simplicity of presentation, every feature which is not referenced in the figures is assumed to be the same as in  FIGS.  3 A to  3 E . The human eye is shown, where a channel should be created at the region of the sclera-corneal junction  362 , as depicted in  FIG.  3 F . As described above, the created channel will controllably connect between the anterior chamber of the eye and the sub conjunctival space/zone and hence allow the extra fluid accumulated in the anterior chamber to exit and by this reduce the intraocular pressure. The properties of the channel, including its size and geometry, can be as has been described earlier with reference to  FIGS.  3 A to  3 E . As shown in  FIG.  3 F , the device  300  approaches the eye from outside and is to be inserted into the anterior chamber  364  of the eye through an opening  374  created beforehand in clear cornea at the opposite side to where the channel is to be created. The opening  374  can be achieved by conventional means known in the art such as a stylet blade. The device is inserted with respect to the eye in an orientation which is opposite to the orientation described in  FIGS.  3 A to  3 E  relating to the Ab externo procedure. In other words, the tissue sharp tip of the outer member is now closer to the internal side of the eye, whereas it was farther away in the Ab externo procedure (as shown in  FIG.  3 A ). By this, the first distal portion beveled shape and orientation will complement the shape and orientation of the sclera at the contact region  362 . 
     The device is inserted into the anterior chamber and is pushed manually by the surgeon, while passing above the iris  376 , until it contacts the sclera tissue at the sclera-corneal junction  362  from inside. 
     As appreciated from  FIG.  3 G , after the surgeon feels the contact, another pushing force is applied manually in the forward direction, such that the outer member  310  pierces and penetrates the sclera (from the inside). The device, by the first distal part  312  of its outer member  310 , is stuck in (anchored) and stabilized temporarily in the sclera tissue. As described above, during advancement inside the sclera tissue, the resistance-to-progression increases and is given as a feedback to the surgeon when he/she manually advances the device. In the case the device is configured with the stopper  312 P, as shown in this specific example, the device comes to a hard stop because the stopper provides significant increase in resistance-to-progression force on the outer member and prevents the additional penetration/progression inside the sclera tissue. As also described above, the preconfigured length of the first distal portion of the outer member insures that the piercing tip does not exit the sclera from the other (here external) side, such that the conjunctiva or other covering tissue is not torn or pierced by the outer member. 
     It is appreciated that  FIGS.  3 F and  3 G  illustrate the positioning phase of the device  300  as a preparation for the channeling phase. It is also appreciated, that during the positioning phase, no relative motion between the outer and inner member occurs. Generally, the inner member is hidden inside and fixedly attached to the outer member during the axial movement of the outer member, no matter how the axial movement of the outer member is executed, whether the axial movement includes manual displacement of the outer member by the surgeon relative to the handle, or whether the outer member is fixedly attached to the handle such that the axial movement of the outer member is generated by manual axial movement of the handle by the surgeon. 
     As shown in  FIG.  3 H , while or after the outer member is anchored into the sclera tissue, the surgeon can pull and lift the conjunctiva  366 , and possibly also the tenon, outwardly in a direction  378  by the help of a suitable tool held in his other hand. This saves the conjunctiva and/or tenon by preventing them from coming into contact with the inner member which will be rotated and advanced to cut and remove sclera tissue. The inner member is rotated, either mechanically or electrically by a dedicated motor as described above and is advanced by the applied moving mechanism forwardly such that it contacts and attaches to the sclera tissue and starts with drilling and creating the channel. The advancement distance of the rotating inner member can be configured by the moving mechanism such that the distal end of the inner member does not protrude significantly outside the sclera tissue to avoid causing harm to the conjunctiva and/or tenon tissues. While the inner member rotates to cut and remove tissue from the sclera, the outer member, which is stabilized by its anchor to the sclera tissue, is stationary, it does not or hardly moves, thus preserving the internal organs, such as the iris, from any damage that may have been caused by the rotating inner member. Further, its anchoring to the sclera minimizes any accidental pulling of the rotating inner member from the sclera, something which may otherwise have adverse consequences on the internal organs of the eye. After creating the channel, the inner member is retracted backwardly (not shown), either rotating or not depending on its configuration, as will be described further below, until it is back in its secured position inside the outer member, and the device is pulled backwardly out from the anterior chamber and out of the eye through the opening  374  which can be treated by suitable medicines in order to heal and close almost immediately. 
       FIG.  3 I  illustrates the created channel after the device is pulled outside the eye. The aqueous humor (the fluid in the anterior chamber) starts to exit the anterior chamber towards the sub-conjunctival space, such that a bleb  372 B is formed under the conjunctiva and above the sclera, and the fluid is reabsorbed in the blood vessels at the vicinity thereof. 
     Reference is made to  FIGS.  4 A to  4 D  showing various non-limiting examples of the outer member of the device according to some non-limiting embodiments of the invention. The figures are illustrative only and are not presented in a full scale. Specifically, the figures show different non-limiting configurations of the first distal portion of the outer member. Generally, the shape and/or orientation of the first distal part can be chosen to complement the shape and/or orientation of the target tissue, such that better coupling/attachment/adherence/anchoring between the outer member and the target tissue is achieved. 
       FIG.  4 A  shows a known shape of cannula end used in medical needles. This is a common point cannula end known as flat bevel point. This configuration can be used as the first distal part  412 A of the outer member  410 A. 
       FIG.  4 B  also shows a known shape of cannula end used in medical needles. This is a common point cannula end known as lancet bevel point. This configuration can be used as the first distal part  412 B of the outer member  410 B. 
       FIG.  4 C  shows a special non-limiting example of a first distal part  412 C of an outer member  410 C according to the invention. Similar configuration to  FIG.  4 C  is also shown in  FIGS.  2 A and  2 B . The first distal part  412 C includes a tissue piercing tip  416 C configured as a lancet bevel point and a stopping portion  412 PC formed by the rim of the outer member  410 C which is obtained by cutting a section of the wall of the outer member  410 C along its longitudinal axis. In some exemplary, non-limiting, embodiments, half of the wall (e.g. half of cylinder) is cut. 
       FIG.  4 D  shows another special non-limiting example of a first distal part  412 D of an outer member  410 D according to the invention. The first distal part  412 D includes a tissue piercing tip  416 D and a stopping portion  412 PD both obtained by cutting the outer member  410 D in the direction of the longitudinal axis along a curved line. The curved line can be chosen to provide smooth transition along the first distal part enabling smooth penetration with increasing resistance-to progression force. The curved line is usually configured as a smooth, continuous line with constant or variable slope (its derivative trend is always positive or always negative, though not necessarily constant), although other non-continuous behavior can be used. For example, the curved line can be a combination of two or more line segments, among which some are curved and/or straight. Specifically, the piercing portion can be configured as a curved line while the stopping portion can be configured as a straight line, e.g. in the direction of the transverse cross section of the inner member. In some embodiments, such a smooth curved line can follow a circular, elliptical, semi- circular or semi-elliptical path, e.g. can be part of a circle’s or an ellipse’s circumference. In the example shown, an elliptical curve is presented, such that the elliptical major axis lies in the direction of the longitudinal axis of the outer member and the elliptical minor axis is in the orthogonal direction (across the outer member). In this instance, the major axis defines the length of the first distal part, and the minor axis (or, more specifically the relation between major and minor axes) defines the level of resistance-to-progression of the stopping portion  412 PD. It should be understood, that the above-described example relates to formation of the curved line, forming the piercing tip / stopper, along the longitudinal axis direction, from a single direction (2D forming), while any other shaping combination in 3D is also possible. 
     As has been clarified above, any configuration of the outer member can be used with any configuration of the inner member. Also, it should be noted that all the examples presented here are by no means limiting and the invention can be practiced with other specific suitable configurations. 
     The inner member is configured, as described above, for attaching effectively to the second tissue (in which the channel is formed) and for cutting a well-defined geometrical shape of the tissue, both while rotating and advancing distally. In some embodiments, the inner member is configured for storing the cut tissue in its intact form, thus providing a validation and authentication to the created channel. In addition, storing the cut tissue inside the inner member (in the second proximal elongated part) serves in protecting the eye from sudden collapse by blocking the outflow of aqueous humor from the anterior chamber during the channel creation and/or when the device is pulled outwardly from the eye. 
     Reference is made to  FIGS.  5 A- 5 D  showing non-limiting examples of the inner member of the device according to some non-limiting exemplary embodiments of the invention. The different examples can be distinguished by the specific channel creating application, including the specific dimensions of the channel which is affected by its purpose and its location in the body. Specifically, some of the described examples may be more suitable than others for the application of creating a channel in the eye wall for treating elevated IOP. 
       FIG.  5 A  illustrates an inner member  520 A having a second distal part  522 A configured to attach to tissue and cut tissue, while rotating and progressing distally, and to guide the inner member through the tissue, e.g. towards the anterior chamber of the eye. The inner member also includes a second proximal elongated part  524 A that includes an elongated chamber/cavity (not shown) configured to receive therein the tissue being removed. The outer diameter of the inner member should preferably match the inner diameter of the outer member such that no space is left there between. The shape of the chamber/cavity preferably matches the shape of the cut tissue. In action, the inner member approaches the tissue while rotating (at least the second distal part), so that the rotation creates desired attachment of the inner member to the tissue and enables start of the piercing and cutting. Generally, the second distal part  522 A has at the distal end a round cutting edge  522 EA, typically of a circular shape, having one of the following configurations:
     the round cutting edge  522 EA has a diameter equal to the diameter of the elongated cavity, such that the cutting edge is created by sharpening (grinding) in the direction from the outer diameter of the inner member towards the diameter of the elongated cavity;   the round cutting edge  522 EA has a diameter equal to the outer diameter of the inner member, such that the cutting edge is created by sharpening in the direction from the diameter of the elongated cavity towards the outer diameter of the inner member; and   the round cutting edge  522 EA has a diameter bigger than the diameter of the elongated cavity and smaller than the outer diameter of the inner member, such that the cutting edge is created by sharpening in both directions, from the outer diameter of the inner member towards the diameter of the elongated cavity and from the diameter of the elongated cavity towards the outer diameter of the inner member.   

     It was found by the inventors that the degree of sharpening, i.e. the inclination angle, plays an important role in providing effectively desired piercing of and/or attachment to the tissue. 
       FIG.  5 B  illustrates another non-limiting example of the inner member  520 B. In this example, the inner member is configured as a full-bodied, not hollow, elongated member with a second distal part  522 B configured as a drill bit being provided with a flute enabling creating the desired channel in soft tissue while rotating. The length, spiral, point angle and lip angle of the drill bit can all be adjusted for optimal soft tissue removal. In this instance, the inner member  522 B rotates with full rounds clockwise or anticlockwise, depending on the spiral direction, such that the removed tissue is conveyed backwardly far from the target tissue and towards a collecting cavity located between the inner member and the outer member of the device. 
       FIG.  5 C 1 - 5 C 3    illustrate another non-limiting example of the inner member  520 C.  FIG.  5 C 1    is an isometric view of the inner member  520 C.  FIG.  5 C 2    is an isometric view of the coaxial outer and members,  510 C and  520 C, with half of the wall of the outer member at the distal side removed for easy illustration.  FIG.  5 C 3    illustrates a transverse cross section of the outer and inner members made along the line C-C in  FIG.  5 C 2   . In this example, the inner member is configured partially similar to the example of  FIG.  5 A  in that, as shown, the inner member  520 C has a second distal part  522 C configured to attach to tissue and cut tissue by its cutting edge  522 EC, while rotating and progressing distally, and to guide the inner member through the tissue. The inner member  520 C also includes a second proximal elongated part  524 C that includes an elongated chamber/cavity  526 C (inside the second proximal elongated part  524 C, shown in  FIG.  5 C 3   ) configured to receive therein the tissue being removed. As also shown, the second proximal elongated part  524 C of the inner member  520 C includes a tissue trapper  524 TC at a distal segment  524 DC of the second proximal elongated part  524 C, located substantially in parallel to the elongated cavity  526 C. The tissue trapper / tissue-trapping enhancer  524 TC enhances and contributes to the trapping of the removed tissue during its removal, such that it allows/ensures pulling the removed tissue out of the body. In addition, the tissue trapper  524 TC can facilitate the flow of the removed tissue into the cavity  526 C by minimizing issues of clogging. In some embodiments, additionally or alternatively, the cavity in the inner member of the device can be designed to trap or contribute to trapping of the tissue there inside. In this example, the tissue trapper  524 TC includes a slit  524 SC, located in the longitudinal direction, i.e. along at least part of the cavity  526 C. The slit  524 SC is obtained by tangential cutting of the round wall of the inner member along the distal segment  524 DC, i.e. by cutting in the tangential direction to the inner member’s wall/circumference. It should be noted that generally the tissue trapper  524 TC can include more than one slit along the inner member circumference, each slit being formed by tangential cutting along the longitudinal axis.  FIG.  5 C 2    illustrates the device either during the positioning phase or after the device has been pulled out of the body, while in both cases the inner member (and the removed tissue in the after operation case) is located safely inside the outer member. As shown in  FIGS.  5 C 2  and  5 C 3    the tangential cutting of the inner member’s wall forms, in addition to the slit  524 SC, a depression  524 D along the distal segment  524 DC of the inner member. The depression  524 D causes the formation of a second outer cavity  528 C between the inner and outer members, that may enhance the pulling of the removed tissue towards the cavity  526 C and/or the inside of the outer member  510 C. In other words, the depression  524 D, resulting from the tangential cutting, forms part of the tissue trapper  524 TC. 
       FIG.  5 D 1 - 5 D 3    illustrate another non-limiting example of the inner member  520 D including a tissue trapper / tissue-trapping enhancer  524 TD.  FIG.  5 D 1    is an isometric view of the inner member  520 D.  FIG.  5 D 2    is an isometric view of the coaxial outer and members,  510 D and  520 D, with half of the wall of the outer member in the distal side removed for easy illustration.  FIG.  5 D 3    illustrates a transverse cross section of the outer and inner members made along the line D-D in  FIG.  5 D 2   . As can be appreciated, various features and elements in  FIG.  5 D 1 - 5 D 3    are similar to those in  FIG.  5 C 1 - 5 C 3   . Specifically, as shown in  FIG.  5 D 1   , the inner member  520 D has a second distal part  522 D configured to attach to tissue and cut tissue by its cutting edge  522 ED, while rotating and progressing distally, and to guide the inner member through the tissue. The inner member  520 D also includes a second proximal elongated part  524 D that includes an elongated chamber/cavity  526 D (inside the second proximal elongated part  524 D, as shown in  FIG.  5 D 3   ) configured to receive therein the tissue being removed. The second proximal elongated part  524 D of the inner member  520 D includes a tissue trapper  524 TD at a distal segment  524 DD of the second proximal elongated part  524 D, located substantially in parallel to the elongated cavity  526 D. As has been explained, the tissue trapper  524 TD enhances and contributes to the trapping of the removed tissue during its removal, such that it allows/ensures pulling the removed tissue out of the body. In addition, the tissue trapper  524 TD can facilitate the flow of the removed tissue into the cavity  526 D by minimizing issues of clogging. In some embodiments, additionally or alternatively, the cavity in the inner member of the device can be designed to trap or contribute to trapping of the tissue there inside. In this example, the tissue trapper  524 TD includes a slit  524 SD, located in the longitudinal direction, i.e. along at least part of the cavity  526 D. The slit  524 SD is obtained by radial cutting of the round wall of the inner member along the distal segment  524 DD, i.e. by cutting in the radial direction of the inner member. It should be noted that generally the tissue trapper  524 TD can include more than one slit along the inner member’s circumference, each slit being formed by radial cutting in the radial direction and along the longitudinal axis.  FIG.  5 D 2    illustrates the device either during the positioning phase or after the device has been pulled out of the body, while in both cases the inner member (and the removed tissue in the after operation case) is located safely inside the outer member. 
     Turning now to  FIG.  5 E 1  to  5 E 7    illustrating one non-limiting scenario of removing soft tissue from a tissue layer in the body. Specifically, the figures illustrate undesired effect of tearing of the soft tissue, instead of or in addition to cutting, while rotating the cutting tool inside the tissue. 
     Ideally, the channel created in the tissue can be expected to look as shown in  FIG.  5 E 1   , i.e. it should have a cylindrical shape, such as when the inner member is as described in  FIG.  5 A . The channel  5003  connects between outer scleral surface  5002  and inner scleral surface  5001 . The cutting tool  520 E, e.g. the inner member, rotates in a direction  503 E around its longitudinal axis, either clockwise or anticlockwise or reciprocating in both directions, and approaches the sclera under feeding rate  502 E. In preferable scenario, the channel should have the required dimensions while its diameter is similar to the diameter of the cutting edge  522 EE. The removed tissue  5004  is expected to be trapped within the cutting tool  520 E as shown in  FIG.  5 E 2   . 
     It is appreciated that cutting of the tissue is defined by the tissue behavior and characteristics. As the cutting tool  520 E cuts, it rotates/revolves within the tissue. The treated organ (e.g. - the eye) is static while the cutting tool  520 E rotates/turns. The cutting tool  520 E presses the tissue both by its external surface  504 E (outer diameter) and inner diameter  505 E. The diameter of the cylindrical tissue  5004  is defined by the cutting edge  522 EE yet the inner diameter  505 E might be slightly smaller and causes squeezing of the tissue (within the cavity of the cutting tool). Another reason for squeezing of the tissue inside the cavity of the cutting tool can be a relatively high friction force between the tissue and the inner surface of the cavity. Additional reason for squeezing of the tissue inside the cavity might be the limited length of the cavity as shown in  FIG.  5 E 3    which is a magnified image of a cutting tool, captured by a microscope. The current technology enables creating a cavity with a small diameter, as required in the treatment of the eye, with length up to about 0.5 mm, as illustrated by the step  508 E in the figure. However, the required length for the channel may be longer than that, for example it should be about three times more (1.5 mm) when the channel is to be created in the sclera in the eye wall. 
     Since the cutting tool 1(e.g. the inner member) rotates and the tissue (e.g., the eye) is static, the tissue  5004  is expected to remain static until the cutting process is completed. In reality, during the cutting process, as shown in  FIGS.  5 E 4  and  5 E 5   , the tissue  5004  is defined by two sections, tissue section  5041  pressed into the cavity of the cutting tool and tissue section  5042  still un-pressed. The attachment of tissue section  5041  to the inner surface of the cavity, due to high friction or due to insufficient cavity length, may cause tissue section  5041  to start rotating with the cutting tool and to tear apart from tissue section  5042 . In this case, the separation of tissue  5004  is not caused by cutting, but rather by torsional tearing. Accordingly, the channel created within the eye wall might look as shown in  FIGS.  5 E 6  or  5 E 7   . This may result in insufficient and ineffective drainage, or even no drainage at all. 
     Minimizing the radial attachment of the removed tissue to the inner surface of the cavity in the cutting tool enables continuation of cutting rather than tearing. Reducing the radial attachment force between the removed tissue (e.g., tissue  5041 ) and inner surface of the cavity (e.g., surface  505 E) can be achieved by lowering the friction coefficient between the tissue and the inner surface of the cavity (for example by applying low friction coating on the inner surface). Alternatively or additionally, Reducing the radial attachment between the removed tissue and inner surface of the cavity can be achieved by creating specific geometry of the cutting tool, e.g. by making the diameter of the inner surface of the cavity bigger than the diameter of the cutting edge of the cutting tool. 
     Turning now to  FIGS.  5 F- 5 G  showing non-limiting exemplary embodiments of tissue cutting tools and methods of fabrication and/or optimization. The cutting tools are optimized for cutting soft tissue and for creating a channel with predetermined dimensions and geometry in a specific given tissue while minimizing the effect of tearing. In some embodiments, the inner member of the device of the invention can be configured as the cutting tools described in  FIGS.  5 F and  5 G . Therefore, the reference numbers used in the following figures follow the same numbering used so far, for example  520 E denotes a tissue cutting tool that can be used as the inner member of the device of the invention. However, this should not be interpreted as limiting the invention. 
       FIG.  5 F  shows a first non-limiting example of a cutting tool configured according to some embodiments of the present invention. The figure describes a cutting tool  520 E which can minimize the radial attachment between the removed tissue and the cavity’s inner surface to thereby minimize the effect of tearing of the tissue. This can be achieved by shaping of the cutting tool. As shown in the figure, a distal portion  504 F of the cutting tool is shaped and pressed towards rotation axis of the tool (passing at the center of the tool if the tool is symmetrical and isotropic). Pressing and shaping can be made by means of known techniques, such as swaging and spinning. In this case, the diameter of the cutting edge  522 EF at the distal end of the cutting tool is smaller than the inner diameter  505 F of the cavity inside the cutting tool. As the diameter of the cutting edge determines the diameter of the removed tissue, the cutting tool  520 F is expected to provide minimal or no attachment force on the removed tissue inside the tool and by this improve the trapping of the removed tissue, while minimizing tearing risk and preserving full shape of the removed tissue that matched a full open channel inside the tissue wall. 
       FIG.  5 G 1  to  5 G 4    illustrate non-limiting exemplary cutting tools  520 G 1  (in  FIG.  5 G 3   ) and  520 G 2  (in  FIG.  5 G 4   ) and an exemplary process for producing the cutting tools ( FIGS.  5 G 1  and  5 G 2   ), according to some embodiments of the invention. 
     In  FIG.  5 G 1   , a side view (cross section) of tool  520 G includes at a distal side  501 G a hollow cylinder  506 G having a cavity  507 G between uniform outer and inner diameters,  504 G and  505 G respectively, that extend along a longitudinal (rotation) axis X1. In  FIG.  5 G 2   , a close-up view on the cylinder  206 G is shown. A distal portion  504 G is shaped with a predetermined pattern, e.g. by pressing, such that both the inner and outer diameters decrease towards the distal end  509 G of the hollow cylinder. As shown on the proximal end  511 G of the hollow cylinder, the original inner and outer diameters are about 0.17 mm and 0.3 mm respectively, and the modified inner and outer diameters at the distal end  509 G are about 0.13 mm and 0.27 mm respectively. The shaping of the distal portion can be done by, for example but not limited to, swaging and/or spinning techniques. The pattern of shaping can be linear, for example by tapering the distal portion to provide a substantially cylindrical frustum shape, or non-linear, e.g. by following a curved line such as parabolic or other similar pattern. 
     In a next step, a slice of the hollow cylinder’s side wall is removed (to the right, in the figure) along the longitudinal axis, in the proximal direction, starting from the distal end  509 G. Depending on the slice depth (i.e. thickness), two exemplary cutting tools  520 G 1  and  520 G 2  are shown in  FIGS.  5 G 3  and  5 G 4   . A cutting edge  522 EG is formed at the distal end and the inner and outer diameters become almost equal, such as 0.18 mm in  FIG.  5 G 3    and 0.16 mm in  FIG.  5 G 4   . Additional sharpening of the cutting edge, both from inside and outside directions results in that the cavity, at a distal side thereof, has a slightly smaller diameter than the cutting edge’s diameter. Then, the inner diameter of the cavity increases continuously in the proximal direction (to the right in the figures) until the inner diameter of the cavity reaches the higher value  505 G of the proximal side of the hollow cylinder. Alternatively, the slicing of the inner surface of the cavity may provide a substantially constant inner cavity diameter. By this slicing step, no step (such as step  508 E in  FIG.  5 E 3   ) is present, and the cavity will have at least a length, in the longitudinal axis direction, equal to the original hollow cylinder’s cavity length, thus providing receiving cavities longer than the limit of 0.5 mm and wide enough to thereby minimize attachment of the tissue entering the cavity to the inner surface of the cavity. All at a micro level required for applications such as creating safe enough channels in the eye wall. 
     Other non-limiting examples of the inner member include devices as described in WO2013186779 and WO2015145444 both assigned to the assignee of the present invention. 
     As described above, the various movements of the outer and inner member of the device are performed either manually and/or by using a moving/movement mechanism. The outer member is configured for axial movement only, while the inner member is configured for both rotational and axial movements. Typically, the inner member’s rotation is governed by an electrical motor connected to the proximal side of the inner member. This is not particularly described here, examples can be found in the above mentioned patent application PCT/IL2016/051063 assigned to the assignee of the present invention. In the following, a variety of moving/movement mechanisms are described. 
     Reference is made to  FIGS.  6 A to  6 D  illustrating a non-limiting example of a movement mechanism configured for manual movement of the device during operation. As shown, the device  600  includes outer member  610  and inner member  620  mounted on a handle  650  via a movement mechanism  640 .  FIGS.  6 A and  6 C  show the device during the positioning phase, i.e. when the outer member is moved forwardly (by manual pushing of the handle by the operating surgeon) to pierce first (preceding) and second (target) tissue layers, or to approach and stick into the target layer directly (such as in the Ab interno procedure).  FIGS.  6 B and  6 D  show the device during the channeling phase, i.e. when the inner member is rotated, by an electric motor (not shown), and advanced distally to cut and remove tissue, thereby leaving the channel in the target tissue layer. 
     The movement mechanism  640  includes a latch  642 , a spring  644 , and a housing  646 . As shown in  FIG.  6 C , the latch is movable to the sides as illustrated by the arrow A. The outer member  610  is axially locked by being firmly attached to the housing at B and supported by the latch  642  at C. The spring  644  is slightly pre-compressed/relaxed during the positioning phase. 
     After pushing the device with the handle  650  inside the tissue until the first distal part of the outer member is stuck/anchored temporarily inside the target tissue layer, e.g. in the sclera, as described above, the operating surgeon turns the latch  642  to the left (or to the right) releasing the outer member  610  at C, thus enabling its retraction proximally. The surgeon switches the electrical motor to rotate the inner member and pushes distally with the handle  650  to expose the inner member  620  as in  FIG.  6 D . The outer member  610  retracts and the spring  644  is compressed. The channel creation occurs once the surgeon pushes the device distally. While the compressed spring  644  tends to push the outer member  610  distally, the spring’s constant is chosen to be too low to enable further penetration of the outer member to the sclera. Ergonomically, the surgeon can control over all features using a single finger while holding the handle. 
     Reference is made to  FIGS.  7 A to  7 D  illustrating another non-limiting example of a movement mechanism configured for manual movement of the device, specifically the inner member, during operation. As shown, the device  700  includes outer member  710  and inner member  720  mounted on a handle  750  via a movement mechanism  740 . 
       FIGS.  7 A and  7 C  show the device during the positioning phase, i.e. when the outer member is moved forwardly (by manual pushing of the handle by the operating surgeon) to pierce one or more tissue layers and/or until being inserted and anchored in the target tissue layer.  FIGS.  7 B and  7 D  show the device during the channeling phase, i.e. when the inner member is rotated, by an electric motor, and advanced distally to create the channel in the second tissue layer. 
     The movement mechanism  740  is configured for controllably advancing the inner member (distally) by manual pushing movement. As shown in  FIG.  7 C , the movement mechanism  740  includes a knob  742 , a spring  744 , and a housing  746 . The outer member  710  is axially locked by being fixedly attached to the housing at D, and as a result also to the handle  750 , such that when the operating surgeon pushes the handle  750  towards the tissue, the outer member moves in the axial direction and penetrates the tissue until it sticks in the sclera. The spring  744  is relaxed during the positioning phase. 
     The knob  742  is attached to the proximal side of the inner member  720  at E, such that they move together in the distal and proximal directions. During the channeling phase, the knob  742  is controllably pushed in the distal direction by the operating surgeon, as shown by arrow R, against the spring  744  causing it to compress. The inner member moves distally at the same rate by which the operating surgeon pushes the knob  742 . Upon releasing the knob  742 , a retraction movement occurs, the spring  744  relaxes and pulls the knob  742  as well as the inner member  720  proximally to the closed state as in  FIG.  7 C . Additionally, though not specifically illustrated, the movement mechanism may include a latch configured to lock the knob  742  in the forward position, and only when the latch is released by the operating surgeon, the retraction movement occurs. As mentioned, the rotational movement of the inner member is controlled by an electrical motor which is not specifically described herein. 
     Reference is made to  FIGS.  8 A to  8 D  illustrating another non-limiting example of a movement mechanism configured for manual movement of the device, specifically the inner member, during operation. As shown, the device  800  includes outer member  810  and inner member  820  mounted on a handle  850  via a movement mechanism  840 .  FIGS.  8 A and  8 C  show the device during the positioning phase, i.e. when the outer member is moved forwardly (by manual pushing of the handle by the operating surgeon) to pierce one or more tissue layers and/or until being inserted and anchored in the target tissue layer.  FIGS.  8 B and  8 D  show the device during the channeling phase, i.e. when the inner member is rotated, by an electric motor (not shown), and advanced distally to create the channel in the target tissue layer. 
     The movement mechanism  840  is configured for controllably advancing the inner member (distally) by manual pulling movement. As shown in  FIG.  8 C , the movement mechanism  840  includes a knob  842 , a spring  844 , and a housing  846 . The outer member  810  is axially locked by being fixedly attached to the housing at F, and as a result also to the handle  850 , such that when the operating surgeon pushes the handle  850  towards the tissue, the outer member moves in the axial direction and penetrates the tissue until it sticks in the sclera. The spring  844  is relaxed during the positioning phase. 
     The knob  842  is attached to the proximal side of the inner member  820  at G, such that they move together in the distal and proximal directions. During the channeling phase, the knob  842  is controllably pulled in the proximal direction by the operating surgeon, as shown by arrow W, such that G moves distally against the spring  844  causing it to compress. The inner member moves distally at the same rate by which the operating surgeon pulls the knob  842 . Upon releasing the knob  842 , it moves in the distal direction, the spring  844  relaxes and pushes G as well as the inner member  820  proximally to the closed state as in  FIG.  8 C . Additionally, though not specifically illustrated, the movement mechanism may include a latch configured to lock the knob  842  in the backward position, and only when the latch is released by the operating surgeon, the retraction movement of the inner member occurs. As mentioned, the rotational movement of the inner member is controlled by an electrical motor which is not specifically described herein. 
     Reference is made to  FIGS.  9 A to  9 E  illustrating another non-limiting example of a movement mechanism configured for advancement of the inner member under constant or substantially constant force, e.g. 5 - 6 N (with tolerance of about 1 N).  FIGS.  9 A and  9 B  show the whole device  900 . As shown, the device  900  includes outer member  910  and inner member  920  mounted on a handle  950  via a movement mechanism  940 .  FIGS.  9 A,  9 C and  9 D  show the device during the positioning phase, i.e. when the outer member is moved forwardly to pierce one or more tissue layers and/or until being inserted and anchored in the target tissue layer ( all by manual pushing of the handle by the operating surgeon).  FIGS.  9 B and  9 E  show the device during the channeling phase, i.e. when the inner member  920  is rotated, by an electric motor, and advanced distally to create the channel in the target tissue layer. 
     The movement mechanism  940  includes a knob  942 , a spring  944 , a floating disk  948  and a housing  946  including three pins  946 P firmly received therein in a spaced-apart relationship matching the floating disk’s teeth. The outer member is permanently attached to the housing  946  such that it does not move relative to the handle  950 , and the outer member’s axial movement is generated only by the operating surgeon by pushing the handle forwards and pulling it backwards. 
     During the positioning phase, as shown in  FIG.  9 C , the spring  944  is compressed applying a distal pushing force on the floating disk  948 . However, the floating disk is kept stationary while the knob  942  is engaged with the floating disk  948  preventing from moving. 
     As shown in  FIG.  9 D , after the outer member is inserted and anchored in the sclera, the operating surgeon turns on the electrical motor to cause rotation of the inner member, then turns the knob to the right or left and releases the floating disk  948 . Once the floating disk is released it turns and is pushed distally by the spring  944  which starts to relax, the floating disk engages with the pins  946 P, as shown in  FIG.  9 E . The floating disk  948  is also axially attached to a base of the inner member, such that the floating disk’s distal movement under the constant relaxing force of the spring  944  causes the rotating inner member to move distally under a constant force until the floating disk reaches the distal side of the housing  946  and the axial movement stops. Additionally, though not specifically illustrated, the movement mechanism may include a latch configured to lock the knob  942 , and only when the latch is released by the operating surgeon, the retraction movement of the inner member occurs. 
     Reference is made to  FIGS.  10 A to  10 D  illustrating another non-limiting example of a movement mechanism configured for advancement of the inner member under constant rate.  FIGS.  10 A and  10 B  show the whole device  1000 . As shown, the device  1000  includes outer member  1010  and inner member  1020  mounted on a handle  1050  via a movement mechanism  1040 .  FIGS.  10 A and  10 C  show the device during the positioning phase, i.e. when the outer member is moved forwardly to pierce one or more tissue layers and/or until being inserted and anchored in the target tissue layer (by manual pushing of the handle by the operating surgeon).  FIGS.  10 B and  10 D  show the device during the channeling phase, i.e. when the inner member  1020  is rotated, by an electric motor, and advanced distally to create the channel in the target tissue layer. 
     The movement mechanism  1040  is configured for automatic rotation and advancement of the inner member. The rotation and advancement movements can be executed by the same or different motors. Additionally, the rate of the rotation and advancement movements can be the same or different, regardless of whether one or two separate motors are employed. 
     As shown in  FIGS.  10 C and  10 D , the movement mechanism  1040  includes two gears G1 and G2. Gear G1 receives, at a first rate (e.g. 100 - 500 rounds per minute (RPM)), the rotational power delivered by the motor (which is not shown). Gear G1 rotates with the inlet shaft  1062  which is constantly connected to Gear G1 and is responsible for the rotational movement of the inner member  1020 . The inner member is connected to the inlet shaft  1062  via an outlet shaft  1064  which rotates together with the inlet shaft  1062  yet it can move axially with respect to the inlet shaft  1062 . Gear G2 is engaged with gear G1 such that it rotates according to a predetermined ratio between G1 and G2. Gear G2 is responsible for the axial movement of the inner member as shown in  FIG.  10 D . Gear G2 is connected constantly to a parallel shaft  1066  that has a built-in driving thread, as shown, such that the rotational movement of the Gear G2 and the parallel shaft  1066  is translated to an axial movement, of a driving nut  1072 , via the built-in driving thread. The axial movement of the inner member is controlled by the housing’s  1046  length along the axial direction. The driving nut  1072  is driven by the rotation of the parallel shaft  1066 , via the built-in thread, such that it moves to the distal direction and forces the outlet shaft  1064  distally with it. A bearing  1074  between the driving nut  1072  and outlet shaft  1064  enables the outlet shaft to rotate as it moves axially while a fork-like shaft  1076  enables the outlet shaft to continue turning along the axial distal travel.