WO2014039093A1

WO2014039093A1 - System for performing micro-static tissue removal

Info

Publication number: WO2014039093A1
Application number: PCT/US2013/031615
Authority: WO
Inventors: Brian D. Mccary; David Haydn Mordaunt; Russ Finlay
Original assignee: Bausch & Lomb Incorporated
Priority date: 2012-09-07
Filing date: 2013-03-14
Publication date: 2014-03-13
Also published as: WO2014039093A9

Abstract

An elongated tube (12) for performing a micro-static removal of tissue from an eye of a patient defines an axis (14), and is formed with a lumen (20). At least one opening (44,50) is formed with an edge (46) at the distal end (18) of the tube (12) for interacting with tissue as tissue is drawn into the opening (44,50) while the tube (12) is vibrated at a selected repetition rate. The sheared tissue is then drawn into the central lumen (20) for the removal (aspiration) of tissue from the eye.

Description

SYSTEM FOR PERFORMING MICRO-STATIC TISSUE REMOVAL

This application claims the benefit of U.S. Provisional Patent Application Serial No. 61/698,352, filed September 7, 2012. The entire contents of Application Serial No. 61/698,352 are hereby incorporated by reference herein.

FIELD OF THE INVENTION

The present invention pertains generally to ophthalmic surgical devices. More particularly, the present invention pertains to systems and methods for removing tissue from an eye of a patient. The present invention is particularly, but not exclusively, useful as a system and method for using an elongated hollow tube (i.e. needle or cannula) which is axially vibrated at a high rate to shear and remove (aspirate) targeted tissue through at least one opening in the distal end of the tube.

BACKGROUND OF THE INVENTION

Anatomically, most of the eye includes several different types of tissues that are substantially transparent. Each of these contributes with different effect to the proper functioning of the eye. Exemplary of such tissues are the crystalline lens in the front segment of the eye, and the vitreous gel that fills the posterior segment (back of the eye). These tissues, in addition to being predominantly water (e.g. the vitreous gel is almost 99% water), contain protein in the form of collagen fibers that give them a structural substance with some form and nominal strength.

Like other types of tissue, when transparent tissues in the eye become diseased, it is sometimes necessary that they be removed from the eye. Removing tissue from an eye, however, can be quite problematic. For instance, tissue that is targeted for removal must be accessed. It must then be removed, without disturbing non-targeted tissue. Because the target tissue is not a liquid, it cannot be merely drained from the eye. Moreover, in most instances the target tissue cannot simply be removed in bulk either.

Staying with the examples presented above, the removal of a crystalline lens is typically accomplished in accordance with a procedure known as "phacoemulsification." On the other hand, the removal of vitreous gel is accomplished in accordance with a variety of operations that are collectively referred to as a vitrectomy. In all of these procedures, it is of utmost importance that only target tissue be affected.

Phacoemulsification is a commonly used procedure for removing tissue of the crystalline lens from the eye. In such a procedure the lens tissue is first broken (fractured) into particles and at least partially emulsified using ultrasonic energy. The tissue is then aspirated from the capsular bag. Major concerns with phacoemulsification are the generation of an effective energy zone, the establishment of the size and shape of this energy zone, and control over the position of the energy zone in a target tissue.

In contrast with phacoemulsification, an operation to prepare vitreous gel for removal from an eye involves a chopping or clipping of the vitreous gel into very small pieces or particles. Typically, this has been done using a mechanically intricate, guillotine-like device that interactively severs the tissue between a blade member and a base member.

In both phacoemulsification and vitrectomy procedures, as in all other types of ophthalmic surgical procedures, control of the respective device is essential to avoid collateral damage to non-target tissues. The purpose here is twofold. For one, the preparation of tissue for removal (i.e. by breaking, fracturing or crumbling) should not adversely affect adjacent tissue. For another, the actual removal of the tissue should also not impose adverse forces on non-target tissue. Stated differently, it is desirable to affect only target tissue. Specifically, the effect should be on only the target tissue that is to be removed from the eye. Moreover, this should happen only as the target tissue is actually being removed (i.e. in a "micro-static" operation). As used herein for purposes of disclosure, the term "micro-static" refers to a mechanical operation for removing tissue from an eye wherein there is no discernible movement within the target tissue as it is being removed. Moreover, no energy field is involved that will alter the tissue, and there is no interaction between two or more mechanical components to affect the removal of tissue. Specifically, the term "micro-static" is associated with an operation of a device wherein tissue is simultaneously removed as it is being sheared from the general body of the target tissue. There is no effective pulling and / or traction on the tissue and no ripping or tearing of the tissue is involved (i.e. the target tissue itself remains "static" during a "micro-static" procedure and, consequently, the effect on non-target tissue is "tractionless").

In light of the above, it is an object of the present invention to provide a system and method for removing target tissue from an eye of a patient that has minimal, if any, effect on non-target tissue. Another object of the present invention is to provide a system and method having a single unitary mechanism for shearing and aspirating portions of a target tissue from an eye of a patient, while the surrounding target tissue remains substantially stationary (i.e. static). Still another object of the present invention is to provide a system and method for using a substantially same mechanism for removing different types of tissue from an eye in separate operations. Yet another object of the present invention is to provide a micro-static tube for removing tissue from an eye of a patient that is simple to manufacture, is easy to use, and is comparatively cost effective.

SUMMARY OF THE INVENTION In accordance with the present invention, a system for shearing and removing tissue from an eye of a patient includes an elongated hollow tube (i.e. needle or cannula) that is vibrated while it is in contact with the tissue. As envisioned for the present invention, this vibration will be a reciprocating motion in either a rotational movement or a translational movement (i.e. longitudinally along the axis or transverse in a side to side or elliptical movement). In either case, tissue is drawn by a pressure differential, e.g. vacuum, through openings that are located in the tube's distal end and/or sidewall. The tissue is then sheared and essentially liquefied by the vibrational movements of the tube (needle). Sheared tissue then enters a lumen in the tube and is evacuated (aspirated) from the eye through the lumen.

Structurally, the system of the present invention includes an elongated hollow tube (needle) having a distal end and a proximal end. And, the tube is formed with at least one internal lumen that extends between the two ends. Further, the distal end of the tube is formed with at least one opening, and possibly a plurality of openings. Each opening individually establishes fluid communication into the internal lumen of the tube.

Openings into the lumen of the tube are typically circular in shape, and are bounded by a peripheral edge. The diameter of each opening will generally be less than about 300 μηι. More specifically, when a tube has only a single opening, its diameter "d_s" will be generally in a range between 75 μΐτι and 300 μηι. On the other hand, more openings will generally mean smaller diameters. For instance, when a plurality of openings is used, the diameter "dp" for each opening will typically be less than 75 μΐη and closer to 35 μΐτι. Independent of the diameter, "d_s" or "d_p", however, it is the sidewall thickness "t" of the tube at the location of a particular opening that effectively establishes the relative sharpness of its edge. In general, the edge of an opening will have a thickness "t" that is in a range of 4-5 thousandths of an inch.

When a plurality of openings is employed, their arrangement on the elongated tube is essentially a matter of choice. An important factor here is the shape of the distal end of the tube. Specifically, the distal end may be essentially flat, it may be rounded (e.g. hemispherical), or it may be a combination of these shapes such as when a rounded transition surface is formed to extend between a flat end surface and the sidewall of the tube. In each case, the type and location of the tissue that is to be removed from the eye will generally determine the arrangement of the openings. For example, in a procedure for removing vitreous tissue that is located next to the retina in an eye, an arrangement of openings that are clustered into one quadrant of the tube's distal end will most effectively allow the user to maintain visual contact with the openings during the procedure.

An added feature for the system of the present invention is an extension that is engaged with the elongated tube to prevent openings in the elongated tube from contacting tissue that should not be disturbed or removed. In particular, the extension is intended to give visual and / or tactile indications when it, the extension, makes contact with an interface surface between two different types of tissue (e.g. the interface surface between the vitreous and the retina, or the interface surface between the crystalline lens and the capsular bag). As envisioned for the present invention, such an extension can be a cylindrical shaped protrusion (i.e. a sleeve) that extends uniformly beyond the distal end of the elongated tube, or it can incorporate only a selected portion of such a protrusion. Preferably, the extension is made of silicon.

Operational aspects of the present invention primarily involve the cooperative function of both an aspiration source such as a vacuum pump and an actuator. In one aspect, the vacuum pump is operated to create a partial vacuum in the lumen of the elongated tube. This is done initially to draw tissue into the opening(s) of the tube. In the other aspect, the actuator vibrates the elongated tube so that edges of the openings interact with the tissue; for example, the edges may cut into the tissue. This action effectively shears and essentially liquefies the tissue that has been drawn into the opening. The tissue that has been sheared by the actuator is then evacuated from the lumen of the elongated tube by the partial vacuum that is created in the lumen of the tube by the vacuum pump.

In an operation of the system of the present invention, the vacuum pump will typically be operated to create a variably selected partial vacuum in the lumen of the elongated tube that is less than about 700 mmHg (preferably less than about 200 mmHg). Simultaneously, the actuator will be operated with a variably selected power to vibrate the elongated tube. As mentioned above, this vibration can be the result of either a rotational movement or a translational movement (i.e. longitudinally along the axis or transverse in a side to side or elliptical movement) of the elongated tube. In either case, the motion will be cyclical (e.g. sinusoidal) and will be characterized by a midpoint, or mid-stroke, velocity "v_mid" that is indicative of the operational power of the system. In general, a maximum practical power is indicated when "v_mid" is 1 1 .2 m/sec.

Typically, for a reciprocating translation motion, the cyclical stroke length "L_s" of the elongated tube will be less than about 125 μητι. Similarly, the arc length "L_a" for a reciprocating rotational motion will also be less than about 125 μΐτι. In most instances, the present invention envisions that procedures for removing tissue from an eye will be accomplished within an operational envelope identified by power settings indicated with "v_mid" in a range between 0.1 m/sec and 5 m/sec, and with partial vacuums in the lumen of the elongated tube generally below 200 mmHg. The particular combination of power and vacuum will depend on the requirements of the operation and the desires of the operator.

BRIEF DESCRIPTION OF THE DRAWI NGS

The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:

Fig. 1 is a perspective view of a system for removing tissue from an eye in accordance with the present invention;

Figs. 2A-C are each a perspective view of the distal end of respective embodiments for an elongated tube (needle) in accordance with the present invention;

Fig. 3A is a cross section view of the distal end of the elongated tube as seen along the line 3-3 in Fig. 2A; Fig. 3B is a cross section view of the distal end of the elongated tube as seen along the line 3-3 in Fig. 2B;

Fig. 4A is a perspective view of an elongated tube of the present invention with a silicon extension protruding from its distal end in a distal direction;

Fig. 4B is a perspective view of an elongated tube of the present invention engaged with a cylindrical shaped silicon sleeve protruding beyond the distal end of the tube;

Fig. 4C is a perspective view of an elongated tube as seen in Fig. 4A with only a portion of a silicon sleeve protruding beyond the distal end of the tube;

Fig. 5 is a cross section of an eye showing exemplary entries of the elongated tube of the present invention into the crystalline lens in the front part of the eye, and into the vitreous in the back of the eye;

Fig. 6 is a foot pedal controller for use with the present invention; and

Fig. 7 is a graph for showing the operational relationship between power (v_mid) and partial vacuum during a procedure using the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring initially to Fig. 1 , a system for shearing and removing ocular tissue in accordance with the present invention is shown and is generally designated 10. As shown, the system 10 includes an elongated cylindrical shaped tube (needle) 12 that defines a longitudinal axis 14. The elongated tube 12 has a proximal end 16 and a distal end 18 with an internal lumen 20 (see Fig. 2A) extending between the ends 16 and 18. As also shown in Fig. 1 , the proximal end 16 of the elongated tube 12 is engaged with a handle (housing) 22.

As indicated in Fig. 1 , the system 10 includes various components that are necessary for its operation. Although these components are shown externally connected to the handle 22, as will be appreciated by the skilled artisan, some may actually be incorporated into the handle 22. The components include a fluid source 24 that may be used to introduce a balanced salt solution (not shown) which will replace tissue as it is being removed by the system 10. Further, rather than being connected directly to the handle 22, the fluid source 24 may be a stand-alone device that is separately operated. A disposal unit 26 is shown in Fig. 1 to indicate that as tissue is removed by the system 10 it must necessarily be disposed of. Of particular importance for an operation of the system 10 are an actuator 28 and an aspiration source which is shown as vacuum pump 30. As indicated in Fig. 1 , these components (actuator 28 and vacuum pump 30) are operated in concert with each by a controller 32.

For purposes of the present invention, the actuator 28 is used to vibrate the elongated tube 12 either in translation as indicated by the arrow 34 (or in some cases laterally); in rotation as indicated by the arrow 36; or possibly in general motion (i.e. a combination of translation and rotation). More specifically, under the control of the controller 32, the power generated by the actuator 28 can be selectively varied, as required by the operator of system 10. As used herein, this operational power for the system 10 is indicated by the velocity "v_mid" of the elongated tube 12 at mid-stroke or mid- arc in a vibration cycle. As a practical matter the stroke length in translation "L_s" (see Fig. 2A) and the arc length in rotation "L_a" are each less than about 125 μηι.

The vacuum pump 30 shown in Fig. 1 is connected in fluid communication with the lumen 20 of elongated tube 12. With this connection, a partial vacuum of as much as 700 mmHg can be established in the lumen 20. In most instances, however, as disclosed below it is envisioned that the partial vacuum will normally be somewhere below 200 mmHg. In some cases, a smaller pressure differential between the intraocular pressure (IOP) and the pressure in the lumen 20 may be used. For these instances, the vacuum pump 30 can be replaced with an aspiration source which controls the pressure in the lumen 20 in a range between the IOP and ambient pressure. Referring now to Fig. 2A, an exemplary tip 37 for distal end 18 of the elongated tube 12 is shown. In this embodiment of the distal end 18, tip 37 includes a flat area 38 that is shown centered on the axis 14 and oriented substantially perpendicular to the axis 14. A rounded transitional surface 40 is also shown to extend from the flat area 38 to the sidewall 42 of the elongated tube 12. Fig. 2A also shows a cluster of openings 44a, 44b and 44c that have been formed through the transitional surface 40. With cross reference to Fig. 3A, it will be appreciated that each opening 44a, 44b and 44c has a respective edge 46 and a diameter "d_p". Further, it will be appreciated that each edge 46 has a thickness "t" that is effectively determined by the thickness of the sidewall 42 of the elongated tube 12. Fig. 3A also shows that the elongated tube 12 has an outside diameter "D", and that the flat area 38 has a diameter "D_f". In their relation to each other, "D_f" will generally be about half the size of "D" (D_f = 0.5D). In scale, "D" will generally be about twenty thousandths of an inch (D = 0.020 in.), "d_p" will typically be less than about 75 μητι, and "t" will be on the order of about 4-5 thousandths of an inch.

In Fig. 2B a tip 48 for an alternate embodiment of the elongated tube 12 is shown to have a single opening 50 that is centered on the axis 14. Fig. 3B shows that this opening 50, like the openings 44 disclosed above, has an edge 46 with a thickness "t". In this embodiment, however, the diameter "d_s" will be larger with a value of as much as 300 μηι. Fig. 2C shows yet another structural embodiment for the elongated tube 12. For this embodiment, several openings 52 are formed directly through the sidewall 42. As will be appreciated by the skilled artisan, the present invention envisions there may be a single opening 50, or a plurality of openings 44/52, and they may be positioned on the elongated tube 12 as required for a particular procedure. The following table shows a typical range of opening diameters for configurations with between 1 and 12 openings. # Holes Upper Lower

Limit Limit

μηι μΓΠ

1 300 75

2 212 53

3 173 43

4 150 38

5 134 34

6 122 31

7 1 13 28

8 106 27

9 100 25

10 95 24

1 1 90 23

12 87 22

Added features for different embodiments of the distal end 18 of the elongated tube 12 are respectively shown in Figs. 4A, 4B and 4C. In particular, each embodiment includes an extension 54 which protrudes, at least in part, in a distal direction beyond the tip 56 at the distal end 18 of the elongated tube 12. Fig. 4A shows the extension 54 as a buffer 58; Fig. 4B shows the extension 54 as a cap 60; and Fig. 4C shows the extension 54 as a sleeve 62. In each case, the purpose is to prevent contact between an opening(s) 44 at the tip 56 and non-target tissue.

In Fig. 4A, the extension 54 is shown as a buffer 58 which is attached directly to the tip 56. In Fig. 4B, the extension 54 is shown as a hollow cylindrical shaped cap 60 that is affixed to the sidewall 42 of the elongated tube 12 at its distal end 18. For the embodiment shown in Fig. 4B, the extension 54 protrudes uniformly beyond the tip 56 to effectively surround all of the openings 44. In Fig. 4C, the extension 54 is formed as a sleeve 62 that is positioned around the sidewall 42 of the elongated tube 12. For the embodiment shown in Fig. 4C, the sleeve 62 is formed with a protrusion 64 that extends from a portion of the sleeve 62 beyond the tip 56. Further, in Fig. 4C the sleeve 62 is shown to include an irrigation port 66 that is in fluid communication with a space between the sleeve 62 and the sidewall 42 of the elongated tube 12. In this embodiment, fluid (e.g. a salt bath solution from the fluid source 24) can be introduced through the irrigation port 66 to replace tissue that is removed during an operation of the system 10. As will be appreciated by the skilled artisan, various structural combinations suggested by the buffer 58, the cap 60, and the sleeve 62 are contemplated for the extension 54 of the present invention. In each case, the extension 54 should be made of a semi-soft, pliant and flexible material that does not effectively transmit forces. Preferably, the material is silicon.

An operation of the system 10 is primarily envisioned for a use involving transparent target tissue within an eye 68. As indicated in Fig. 5, the elongated tube 12 can be specifically designed in accordance with the above disclosure to be used either in tissue of a crystalline lens 70 or in the vitreous body 72 of an eye 68. In addition to being capable of removing target tissue (e.g. crystalline lens 70 or vitreous body 72), it is an important aspect of the system 10 that it also be capable of doing so without disturbing or altering non-target tissue (e.g. capsular bag 74 or retina 76). In accordance with the present invention, this caution is two-fold. On the one hand, the extension 54 is employed to provide visual and / or tactile identification for contact with a tissue interface between target tissue and non-target tissue, such as between the crystalline lens 70 and the capsular bag 74, or between the vitreous body 72 and the retina 76. On the other hand, it is essential that the elongated tube 12 be vibrated by the actuator 28 within operational parameters that effectively establish a "micro-static" condition for the target tissue.

Fig. 6 shows a controller 32 for use in the operation of system 10 that includes a base member 78 and a foot pedal 80. In detail, the arrow 82 in Fig. 6 shows that an operator can either depress or ease off on the foot pedal 80, and the arrow 84 shows that the operator can simultaneously rotate the foot pedal 80 either left or right. For the present invention, one of these movements can be used to control power of actuator 28 (e.g. arrow 82) while the other movement can be used to control the partial vacuum that is created by the vacuum pump 30 (e.g. arrow 84). In either combination, the control signals from controller 32 can be simultaneously passed to the actuator 28 and the vacuum pump 30 via an electronic connection 86. The consequence here will be an operation of the system 10 within the typical operational envelope 88 shown in Fig. 7.

As an operational example of a use for the present invention, the system 10 may be employed as part of a lensectomy procedure. For example, a laser unit or other suitable device such as a conventional phacoemulsification system (not shown) may first be employed to break-up or emulsify lens tissue such as cataractous tissue in the crystalline lens 70 (see Fig. 5). The emulsified / broken up tissue may then be aspirated / removed from the capsular bag 74 using conventional techniques. With the tissue removed, the system 10 may then be employed to perform a fast cortical cleanup / polish. The use of the system 10 for this cortical cleanup may be advantageous in situations where the capsular bag 74 is inadvertently broken during cleanup. In this case, the system 10 may then be used to perform a vitrectomy, which is often indicated in cases in which the capsular bag 74 has been compromised. Thus, the vitrectomy can be performed after cortical cleanup without changing tools.

In another operational example of a use for the present invention, the system 10 may be employed as part of another lensectomy procedure. For example, a laser unit may first be employed to initially establish fractures in lens tissue such as cataractous tissue in the crystalline lens 70 (see Fig. 5). It is estimated that a femtosecond laser operating at a pulse repetition rate of approximately 8kHz, can establish fracture points throughout the crystalline lens 70 within about 1 second. More specifically, this process can quickly establish fractures such that a fracture point is located within about 0.1 mm of every location in the crystalline lens 70. With these fractures established, it is anticipated that lens material will tear very easily. After the laser treatment, the system 10 can then be used in the crystalline lens 70, as described above, to remove lens tissue.

For these operations, the laser unit (not shown) can include a femtosecond laser system capable of generating a so-called "femtosecond" laser beam. Thus, the generated laser beam includes a sequence of laser pulses having a very ultra-short duration (e.g. less than approximately 500 fs). In addition, the laser unit can include a beam steering component for moving the focal spot of the laser beam along a selected path to treat target tissue. For example, the beam steering component can include a pair of mirrors (not shown) mounted on respective tip-tilt actuators to steer the beam in respective, orthogonal directions. For this purpose, the parameters of the laser beam are configured to perform Laser Induced Optical Breakdown (LIOB) on selected target tissue inside the eye. Typically, there will also be a capability of imaging the target tissue that is to be altered by LIOB. For example, a detector is provided using Optical Coherence Tomography (OCT) techniques. Alternatively, or in addition to the OCT device, the detector can include a Scheimpflug device, confocal imaging device, optical range-finding device, ultrasound device and / or two-photon imaging device.

In yet another operational example of a use for the present invention, the system 10 may be employed to perform aspects of a lensectomy procedure that are conventionally performed by both a phacoemulsification probe and an irrigation-aspiration cannula. In a conventional procedure, the irrigation-aspiration cannula instrument is typically employed to remove any cortical material that remains after phacoemulsification. The use of one tool (i.e. the system 10 described herein) to perform both functions reduces procedure time and eliminates complications associated with tool change-out.

While the particular System for Performing Micro-Static Tissue Removal as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.

Claims

What is claimed is:

1. A device for shearing tissue which comprises:

an elongated tube defining an axis and having a proximal end and a distal end, wherein the tube is formed with a lumen and the distal end of the tube is formed with at least one opening in fluid communication with the lumen;

a vacuum pump connected with the lumen of the elongated tube for creating a variably selected partial vacuum therein to draw tissue through the opening and into the lumen; and

an actuator connected with the elongated tube for moving the opening of the elongated tube back and forth with a variably selected mid-stroke velocity "v_mid", to shear tissue as the tube is being moved by the actuator, and to collect sheared tissue in the lumen of the tube for a subsequent evacuation of the sheared tissue from the lumen of the tube in response to the partial vacuum created by the vacuum pump.

2. A shearing device as recited in claim 1 further comprising a controller, wherein the controller is connected to the actuator, and to the vacuum pump, to coordinate controlled variations in the selected mid-stroke velocity "v_mid" of the tube with controlled variations in the selected partial vacuum created during an operation of the vacuum pump.

3. A shearing device as recited in claim 2 wherein the controller is operated to cooperatively establish "v_mid" less than 1 1 .2 m/sec and the partial vacuum less than seven hundred millimeters mercury (< 700 mmHg).

4. A shearing device as recited in claim 1 further comprising an extension positioned with the tube, with at least a portion of the extension protruding beyond the distal end of the tube, to limit and control contact between tissue and an opening of the tube, and wherein the extension is made of silicon.

5. A shearing device as recited in claim 1 wherein the tube is cylindrical shaped with a sidewall and the tube has an outside diameter "D" of approximately twenty thousandths of an inch (D = 0.020 in.), and further wherein the tube is formed with a tip at the distal end of the tube, with the tip having a flat area oriented substantially perpendicular to the axis of the tube with a rounded transition surface extending from the flat area to the sidewall of the tube, and wherein the flat area has a diameter "Df", with "D_f" being less than about one half "D" (D_f < 0.5D).

6. A shearing device as recited in claim 5 wherein the tube is formed with a single opening and the single opening has a diameter "d_s" less than about three hundred microns (d_s < 300 μΐη), and wherein the opening has a thickness "t" from the transition surface to the lumen, with "t" being between four and five thousandths of an inch (0.004 in. < t < 0.005 in.).

7. A shearing device as recited in claim 5 wherein a plurality of openings are formed through the transition surface, and wherein each opening has a diameter "d_p" less than seventy five microns (d_p < 75 μΐη), wherein each opening has a thickness "t" from the transition surface to the lumen, with "t" being between four and five thousandths of an inch (0.004 in. < t < 0.005 in.).

8. A shearing device as recited in claim 7 wherein the plurality of openings is located in a selected quadrant of the tip.

9. A shearing device as recited in claim 1 wherein the actuator reciprocates the elongated tube along a stroke length "L_s" less than one hundred and twenty five microns (L_s < 125 μιη) and a mid-stroke velocity "v_mj_d" in a range between 0.1 m/sec and 5 m/sec.

10. A system for shearing tissue from within an eye of a patient which comprises:

an elongated tube having a proximal end and a distal end, wherein the tube defines an axis and is formed with at least one opening in fluid communication with a lumen formed in the tube;

an actuator attached to the tube for imposing a cyclical back and forth motion on the tube, wherein each cycle has a variably selected mid-stroke velocity "v_mj_d";

a vacuum pump, wherein the vacuum pump is connected into fluid communication with the lumen at the proximal end of the tube, and the vacuum pump is operated at a variably selected partial vacuum for drawing tissue into the opening to shear tissue in contact with an edge of the opening as the tube is being moved by the actuator, and to evacuate sheared tissue from the lumen after the tissue has been sheared by contact with the edge of the opening; and

a controller, wherein the controller is connected to the actuator, and to the vacuum pump, to coordinate controlled variations in the selected mid-stroke velocity "v_mid" of the tube with controlled variations in the selected partial vacuum created during an operation of the vacuum pump.

1 1. A system as recited in claim 10 further comprising an extension positioned on the tube, with at least a portion of the extension protruding beyond the distal end of the tube, to limit and control contact between tissue and an opening of the tube, and wherein the extension is made of silicon.

12. A system as recited in claim 10 wherein a single opening at the distal end of the tube is substantially circular and has a diameter "d_s" less than three hundred microns (d_s < 300 μΐτι).

13. A system as recited in claim 10 wherein the actuator reciprocates the elongated tube along an axial path and through a stroke length "L_s" less than one hundred and twenty five microns (L_s < 125 μητι) and a mid-stroke velocity "v_mid" in a range between 0.1 m/sec and 5 m/sec.

14. A system as recited in claim 10 further comprising a fluid source for introducing a balanced salt solution into the eye as tissue is being removed from the eye.

15. A system as recited in claim 10 wherein the tube is formed with a plurality of openings, and wherein each opening has a diameter "d_p" less than seventy five microns (d_p < 75 μηι).

16. A system as recited in claim 10 wherein the controller is operated to establish "v_mid" less than 1 1.2 m/sec, and establish the partial vacuum at less than seven hundred millimeters mercury (< 700 mmHg).

17. A system as recited in claim 10 wherein the tube is cylindrical shaped with a sidewall and the tube has an outside diameter "D" of approximately twenty thousandths of an inch (D = 0.020 in.), and further wherein the tube is formed with a tip at the distal end of the tube, with the tip having a flat area oriented substantially perpendicular to the axis of the tube with a rounded transition surface extending from the flat area to the sidewall of the tube, and wherein the flat area has a diameter "Df", with "D_f" being less than about one half "D" (D_f < 0.5D).

18. A method for shearing tissue from an eye of a patient which comprises the steps of:

providing an elongated tube, wherein the tube defines a longitudinal axis and has a proximal end and a distal end, wherein the tube is formed with a lumen and the distal end of the tube is formed with at least one opening, with the opening having an edge with a thickness "t" less than 0.25 mm, and a diameter "d" less than 300 μητι, and with the opening being in fluid communication with the lumen; positioning the opening adjacent tissue to be removed from the eye;

moving the tube in a cyclical back and forth motion in an axial direction through a stroke length "L_s" less than 125 μηη, with a mid- stroke velocity in a range between 0.1 m/sec and 5 m/sec;

establishing a partial vacuum in the central lumen to draw tissue into the opening to shear tissue during the moving step, and to thereafter draw sheared tissue into the central lumen for a removal from the eye at a predetermined flow rate, wherein the partial vacuum established by the vacuum pump is dependent on the flow rate of tissue into the lumen, and wherein the partial vacuum is less than seven hundred millimeters mercury (< 700 mmHg); and

coordinating the simultaneous execution of the moving step and the establishing step.

19. A method as recited in claim 18 wherein the tube is cylindrical shaped with a sidewall and an outside diameter "D", and wherein the providing step further comprises the steps of:

forming the distal end of the tube with a tip having a flat area oriented substantially perpendicular to the axis of the tube with a rounded transition surface extending from the flat area to the sidewall of the tube, wherein the flat area has a diameter "d_f", with "d_f" being less than about one half "D" (df < 0.5D); and

creating a plurality of openings through the transition surface in a selected quadrant of the tip, wherein each opening has a diameter

"dp" less than seventy five microns (d_p < 75 μητι), and wherein the thickness "t" is measured from the transition surface to the lumen.

20. A method as recited in claim 19 further comprising the step of positioning an extension on the tube, wherein at least a portion of the extension protrudes beyond the distal end of the tube, to limit and control contact between tissue and an opening of the tube, and wherein the extension is made of silicon.