WO2009153550A1

WO2009153550A1 - Surgical cutting implement

Info

Publication number: WO2009153550A1
Application number: PCT/GB2009/001491
Authority: WO
Inventors: Robert Andrew Gibbs; John Daniel Stokes
Original assignee: Nottingham University Hospitals Nhs Trust
Priority date: 2008-06-17
Filing date: 2009-06-16
Publication date: 2009-12-23
Also published as: GB0811087D0

Abstract

A surgical cutting implement and tool (2), in some embodiments for use in capsulorhexis, is provided which allows a blade (12) having a cutting portion with two ends to be introduced through a small incision and to form into a substantially circular configuration to provide a circular cutting ability after insertion through the incision. In some embodiments, a cutting portion (58) with a saw tooth like profile is provided for use in a cutting action in a direction perpendicular to the profile, rather than in a sawing motion.

Description

SURGICAL CUTTING IMPLEMENT

The present invention relates to a surgical cutting implement and a corresponding surgical tool including such an implement, in particular although not exclusively for use in cutting a central circular opening in the anterior lens, known as capsulorhexis (or capsulorrhexis, capsular rhexis, capsularrhexis and capsularhexis).

Whilst cataract surgery is one of the most commonly performed operations in the world, one of the most frequent complications in the procedure is the incomplete opening of the anterior lens capsule or capsulorhexis. This delicate procedure is often classed by surgeons as the most important and most challenging part of the operation and is currently performed using either a needle or forceps to tear away the lens capsule to form a complete circular opening. The most common complication in this known method of removal are irregular and inaccurate openings and, due to the dome shape of the capsule, errant tears running down hill, out of control and away from the forceps. Paediatric cataract surgery is often significantly even more difficult due to the size of the eye, the depths of the anterior chamber and the elasticity of the anterior lens capsule.

FR-A-2855746 discloses a cutting device for cataract surgery in which a flexible cutting ring, sharp on one side for cutting the capsule, is slideably disposed in relation to an introducer sleeve. In a first configuration, the ring extends outside the introducer sleeve ready for the cutting operation and in another configuration it is retracted into the sleeve such that it is deformed into an elongate shape fitting within the sleeve. However, as the cutting ring must be stowed in a round tube of dimensions typical for dimensions of existing introducers for deformable lenses in cataract surgery (typically 2-3 mm. for example approximately 2.8 mm), significant strain is placed on the cutting ring to deform it into an elongate shape which fits into the introducer tube, for example an ellipse having a smallest radius of curvature which is less than lmm.

Aspects of the invention provide a substantially circular blade, which has two ends and is retractable such that the two ends are separated, and a surgical tool using such a blade.

An aspect of the present invention is set out in independent claim 1. Further, optional features of embodiments of the invention are set out in the dependent claims.

By using a blade geometry of, in effect, a curled strip, the degree of deformation, as compared to the prior art, can be reduced by allowing a cutting portion of the blade to be disposed in a first configuration, for example substantially relaxed, in which an arcuate cutting surface is presented, for example a substantially circular cutting surface, and a second configuration in which the cutting portion is "uncurled" into a linear configuration (straight or less arcuate than the first configuration), allowing the blade to be retracted in the linear direction into a channel of a corresponding surgical tool.

For example, the cutting portion may have a saw tooth shape profile. Advantageously, this allows the cutting portion to positively engage the surface to be cut, for example the capsule in capsulorhexis, and to cut the surface by pressure normal to the surface at the location of each saw tooth (rather than by a saw-like operation). The cutting implement may comprise a flat strip of resilient material. For example, the material may be a super elastic material (or metal) such as nickel titanium. The strip may be shape-set in the arcuate configuration.

The cutting implement may comprise an attachment portion for attaching it to a surgical tool and an opposed, free, end which comprises a leading blunt portion level with a sharp side of the cutting implement to provide protection against involuntary cuts being made as the cutting implement is allowed to take its arcuate configuration.

The sharp side of the cutting implement may be shaped to define a cutting plane which is tilted with respect to the attachment portion, which may be beneficial where an oblique approach to the surface to be cut is desired.

The cutting implement may be disposed in a channel defined by a surgical tool, for example resembling an introducer for flexible lenses in cataract surgery. The cutting implement may be slideable between an exposed configuration in which the cutting portion extends in its arcuate configuration from an introducer portion of the tool (corresponding to the end at which the flexible lens is dispensed in a lens introducer for cataract surgery). Similarly, the cutting implement may be retractable into the channel, which guides it into a more linear configuration (straight or less curved than the exposed configuration). In this way, the surgical tool can be used, for example, to be inserted through an incision into the eye while the cutting implement is held inside the tool in the channel and, once inside the eye, the cutting implement is exposed and resiliently recovers the arcuate configuration. In this configuration, the cutting portion can be used to form a well-defined capsulorhexis simply by applying it with some pressure and possibly some minor agitation onto the capsule. The introducer portion may have a tapered end to facilitate insertion, for example into the eye, through an incision. The introducer portion may further define a support surface to support the cutting portion where its curled up free end overlaps (or touches) an interior portion of the cutting portion. The support surface may be located opposite the sharp side of the cutting implement to stabilise the arcuate configuration as a cutting pressure is applied to it.

In some embodiments, the surgical tool may comprise means for supplying or aspirating a fluid or viscoelastic medium through the introducer portion. Particularly, the surgical tool may comprise a coupling for coupling to a syringe and a conduit extending from the coupling into the introducer portion for supplying or aspirating the fluid through it. The surgical tool, and in particular the handle of the surgical tool, may define a hollow, open, space into which the syringe can be inserted to couple with the coupling.

Embodiments of the invention are now described by way of example only and with reference to the accompanying drawings in which:

Figures IA and B illustrate a surgical tool in accordance with embodiments of the invention in, respectively, a first configuration in which a blade is extended from an introducer tube of the tool, and a second configuration in which the blade is retracted;

Figure 2 illustrates a frontal view of the tool;

Figures 3A, B and C illustrates enlarged views of an introducer portion with the blade extended; Figures 4A and B illustrates the introducer portion with, respectively, the blade retracted and at the beginning of extension;

Figures 5 A to 5 C illustrates components of the surgical tool;

Figures 6A to 6C schematically depict views of the blade in a configuration when retracted; Figures 7 A to 7C schematically depict views of the blade in a configuration when extended;

Figures 8A and 8B illustrates a blade suitable for an angled approach of the tool; Figures 9A to 9C illustrate a blade having a sawtooth profile suitable for an angled approach of the tool;

Figure 1OA and 1OB illustrates a surgical tool which is additionally arranged to accept a syringe for supplying a fluid through the introducer portion; Figures HA and HB illustrate interior components of the surgical tool of Figures 1OA and 10B₅ arranged to allow the supply of fluid through the introducer portion; and

Figure 12 depicts a surgical tool with an alternative introducer portion.

With reference to Figures IA and IB, a surgical tool 2 for use in capsulorhexis (or similar surgical procedures requiring circular cuts, or other predetermined shaped cuts, in confined spaces) comprises a handle portion 4, an introducer portion 6 mounted at one end of the handle portion 4 and a slider portion 8 slideably mounted in the handle portion 4. The slider portion 8 comprises a shaped plate 10 for supporting a user's thumb or finger when the slider portion 8 is actuated. A cutting implement or blade 12 is held in a channel inside the tool and is slideable between an extended configuration in Figure IA and a retracted configuration shown in Figure IB by actuation of the slider portion 8. In the extended configuration, the blade is exposed at a tip 14 of a tube 15 of the introducer portion 6, ready for cutting action such as in capsulorhexis. In the retracted configuration, shown in Figure IB, the blade 12 is held within the tool 2, allowing safe introduction and removal of the tools to and from the operating side such as the capsule inside an eye. As the blade 12 moves from the retracted configuration to the extended configuration, it curls into an arched configuration to provide a substantially circular cutting portion due to the resilience of the blade material, as described in more detail below. Similarly, as the blade 12 is retracted, it uncurls on retraction into the tool.

With reference to Figure 2, the blade 12 extends from the tip 14 at an opening of a channel 16 in which it is held with a sharp side 18 of the blade 12 clear of an opposed (lower in Figure 2) surface of the channel to avoid blunting of the sharp side 18 and/or creation of debris as the cutting implement is moved to its extended position. In some embodiments, the handle portion 4 is shaped to provide an anti-roll functionality for example by providing it with a cross- sectional profile having a number of joined, substantially flat portions 20, although completely round or otherwise ergonomically shaped cross sections are equally envisaged.

With reference to Figures 3A, B, and C, the tip 14 of the introducer is shaped to provide a lip 22 which supports the blade 12 as it emerges from the channel 16 and also a free end 24 of the blade 12, in the direction of cutting. Thus, the lip is located adjacent an opposed side 26 of the blade, opposed to the sharp side 18, such that it can support the blade 12 and in particular the free end 24 as pressure is exerted on the sharp side 18 during cutting. The lip 22 further has a lateral extent such that the blade 12 is supported not only in the region of its free end 24 but further extending over a sector of the substantially circular blade so that the blade 12 is stabilised further. To further provide support for the blade 12, an end 28 of the channel 16 from which the blade emerges is located as close as possible to the blade 12 in its extended configuration whilst still providing sufficient clearance for the blade. The channel wall 30 located on the side of the blade which lies on the outside when the blade is curled is extended beyond the end 28 towards the end 32 of the tip 14 to provide lateral support for the blade. The opposite side of the introducer portion 4 in the vicinity of the lip 22 terminates in an arcuate wall 34 following the outer contour of the curled blade 12 with sufficient clearance.

With reference to Figures 4A and 4B, the end 32 of the introducer tip 14 is formed as a blade-like edge between an upper tapered surface 38 and a lower tapered surface 36 of the tip 14 of the introducer portion 6. The blade-like end and tapered introducer tip facilitate the insertion of the introducer through an incision, in particular in the case of a stepped incision as is typically the case in minimally invasive ophthalmic operations. The introducer tip is generally cylindrical or tube shaped with a diameter of about 2.2 mm, as for a typical lens introducer. In some embodiments, the diameter is reduced to about 1.5 to

2 mm, but the diameter could be up to about 2.8mm or larger.

As the blade 12 emerges from the channel 16, it tends to migrate to the most open part of the tip 14, i.e. downwards in the region of a tapered surface 19 adjacent the channel 16. This could risk bringing the teeth of the blade into contact with the tip 14. As a measure to reduce the likelihood of jamming, the channel may therefore include a guide or resilient biasing means such as a spring to bias the blade such that its teeth are kept away from the inside of the tip 14.

With reference to Figures 5A, B and C, the surgical tool 2 comprises 3 component parts (excluding the blade 12). The first part provides the introducer 6 and is an interference fit with a second part defining the handle 4. In particular, an arcuate portion 40 of the introducer 6 engages an opening 42 of the handle 4 and a tongue 44 of the introducer 6 engages a slot 46 of the handle 4 to cooperatively define a slot in which a third part providing the slider 8 rides. The slider 8 comprises a plate 48 having secured to it on one side the support surface 10 and on the other side a blade carrying portion 50 which S

securely holds the blade 12 in relation to the slider 8. An outer surface of the plate 48 engages an inner surface of both the tongue 44 and the handle portion 4 in the vicinity of the slot 46 to provide an enclosed space for carrying the blade 12 in both the retracted and exposed positions inside the handle 4.

In the retracted configuration of the surgical tool, a rear abutment 52 between the support surface 10 and the plate 48 engages a rear end 54 of the slot 46 and, in the extended configuration, a corresponding front abutment 56 engages a rear end 57 of the tongue 44 to positively define the respective configurations. In some embodiments, features to indicate full extension and retraction of the blade are provided. For example, an outer surface of the plate 48 may be colour coded such that an indicator colour, for example red, is visible at the front of the plate 48 unless the tool is in the fully extended configuration and a similar colour coding may be arranged in a rear end portion of the plate 48 such that it is visible unless the tool is disposed in a completely retracted configuration.

Further, appropriately positioned, click-fit features are provided in some embodiments the plate 48 and the tongue 44 and/or the handle 4 to provide an audible click when the tool is disposed in the respective configuration. In some embodiments, the click-fit feature comprises a groove on the plate 48 and a detent on the tongue 44 of holder 4, or vice-versa. In addition to these features, embodiments may comprise a ground feature on the blade 12 which engages with an abutment feature provided in the channel 16 when the blade is fully extended to provide a positively defined extended configuration. In some embodiments, a locking feature is provided between the plate 48 and the handle 4 which engages when the blade is fully retracted to prevent further extension of the blade, thus making the surgical tool single-use. In these embodiments, the blade is stowed fully hidden but is not retracted as far as is possible. On completion of the operation, on full retraction, the blade moves past a ratchet mechanism in the back of the handle such that it cannot be extended again.

The parts described above with referenced to Figures 5A, B, and C can be manufactured in a variety of ways. In some embodiments, all parts are moulded, for example injection moulded, from a suitable plastic material such as PA, PET, ABS or nylon. As the tip 14 of the introducer 6 will have to withstand the pressure of the blade 12 attempting to curl against the channel 16 in its retracted configuration, a plastic of suitable strength must be chosen and in some embodiments a medically approved reinforcement for a plastic material at least in the region of the tip 14 is used. In some embodiments, the tube 15 of the introducer is manufactured from a metal.

A detailed description of the blade 12 will now follow with reference to Figures 6A, 6B, 6C, 7A, 7B and 1C. In the retracted configuration depicted in Figures 6A, 6B and 6C, the blade 12 is disposed in a substantially straight configuration inside the channel 16. Detailed measures of specific features of a particular embodiment of the blade are depicted in the referenced figures in units of millimetres or degrees, as appropriate. The blade comprises a cutting portion 58 defining the sharp side 18 with a saw tooth like profile ground into the cutting portion on one side thereof with the opposed side 26 being left untreated or only polished, for example electro polished. The saw tooth profile comprises a series of teeth 64 with sharp tips and edges between the tips and the root of the teeth. The dimension from the tip to the root of the teeth is 0.25mm compared to a typical thickness of a human lens capsule of 0.022mm. In addition to the cutting portion 58, which, in the extended configuration, curls up on itself as described in detail below, the blade 12 further comprises an attachment portion 60 adjacent the cutting portion 58 and having an attachment feature 62 at an opposed end thereof so that the blade can be securely held by the blade carrying portion 50.

Figures 7 A, 7B, and 7C depict the cutting portion 58 of the blade 12 in the extended configuration in which the cutting portion 58 extends from the surgical tool 2 and curls up on itself due to resilient biasing of the cutting portion into this configuration. When curled up, the free end 24 comes to rest and touches against the cutting portion 58 in the region of a last tooth 70 at the opposed end of the cutting portion. This results in a substantial circular cutting surface on the sharp side 18 with a small off set between the radial position of a first tooth 72 adjacent the free end 24 and the last tooth 70, due to the finite thickness of the blade. In some embodiments, the cutting portion is thinned in the region of the last tooth 70 to reduce this reduction in radius. The cutting portion in the extended configuration is hence not an exact circle but rather substantially circular with a radius of curvature which reduces from the last to the first tooth due to the finite thickness of blade In some embodiments particularly adapted for capsulorhexis in children, the diameter of the substantially circular cutting portion is about 4.5 mm.

The height of the blade in the region of the cutting portion from a blunt edge of the blade 26 to the tip of the teeth 64 is between 1 and 2 mm, for example in the region of 1.4 mm, to impart sufficient stiffness to the cutting portion 58 while at the same time ensuring sufficient clearance between the teeth 64 of the blade 12 and the introducer tube material inside the channel 16. A typical blade thickness is about 0.16mm. Other blade heights fulfilling these requirements are of course equally possible.

The blade of the above-described embodiments is manufactured from a nickel titanium (NiTi or Nitinol) strip (or sheet) material which is ground to the appropriate shape and then polished, for example using electro-polishing or electro-chemical sharpening to provide sharp cutting edges. Alternative shaping techniques used in some embodiments include micro-wire electro discharge machining, chemical etching, laser cutting, water-guided laser jet cutting. In alternative embodiments, the shape of the teeth can be imparted merely by application of an appropriately grained grinding wheel without further polishing. In these embodiments, a specifically shaped grinding wheel can be used to directly impart the desired shape to the teeth. During grinding, the strip is submerged in coolant to ensure that it is kept at an appropriate temperature in particular given its very small thickness.

In some embodiments, following shaping of the strip, it is put in a rig imparting the final, substantially circular shape of the cutting portion to it. In some embodiments, the strip is thermally annealed in an intervening step. This is followed by shape setting the nickel titanium strip using a heat treatment program (for example 2 to 5 minutes in a molten salt bath at 500⁰C, the exact parameters depending on the equipment used). In some embodiments, the process is reversed in that the Nitinol strip is first shape set and then ground as described above. Yet a further possibility would be to shape the strip to a certain extent for example only leaving the cutting portion unshaped, followed by shape setting the cutting portion and then grinding the teeth into the cutting portion in some embodiments.

A number of further embodiments resulting from modifications of the embodiments described above are now described. As will become apparent from inspection of Figure 4B above, there is a risk of unintentional injury to structures inside the eye by the first tooth 72 as the blade is paid out from the introducer tip 14. To reduce this risk, in one embodiment, the blade may be provided with a blunt leading edge to minimise the risk of the first tooth 72 coming into contact with structures inside the eye as the cutting portion is paid out so that the risk of unintentional injury can be reduced.

With reference to Figures 8A and B, it may sometimes be advantageous for the surgeon to be able to approach the lens capsule from an incision not exactly at 90° to the capsule but at a more oblique or acute angle. In such a situation, the cutting portion 58, or more precisely its sharp side 18 can advantageously be angled with respect to the remainder of the blade such that an angled approach is enabled. In some embodiments, this angling of a plane defined by the sharp side of the cutting portion can be achieved by an appropriate arcuate, multimodal shaping of the sharp side 18, as depicted in Figure 8B, such that the resulting surface is planar and at an angle to the remainder of the blade when the cutting portion is curled up into its substantially circular configuration, as depicted in Figure 8A.

The multimodal arcuate shape can be defined as follows. Imagine a strip of material for example a metal bent around a cone to rest on the conical surface. If the strip is applied to the cone parallel to the base of the cone, it will spiral upwards towards the tip of the cone. If, however, the strip is applied to the cone at an appropriate angle, it will wrap onto itself after one turn around the cone, forming a loop which substantially defines a cross-section or frustrum of the cone in the fashion of a wide funnel, or frustrated cone. The free end corresponding to the attachment portion (60) will be at an acute angle to a plane of the frustrum and the multimodal arcuate pattern results from shaping (notionally cutting along that plane) the strip to have an edge (corresponding to the sharp side 18) parallel to the plane when the strip is wrapped on the cone (corresponding to the curled configuration). This arrangement is termed a conical bend. It will be noted that, while the blade shown in Figures 8A and B are shown with a straight cutting surface and no saw tooth profile, in some embodiments, described below, the same angled approached is used with a saw tooth profile, the envelop of the saw tooth profile being shaped such that the tips of the teeth define a plane at an angle to the remainder of the blade in the curled configuration. Likewise, any of the embodiments described with a saw tooth profile may equally use a blade having a straight cutting edge.

A blade enabling an angled approach and having a sawtooth profile is now described with reference to figures 9A to 9C. The loci of the tips 74 and the teeth 64 follow the multimodal curve described above with reference to the conical frustrum between the first and last tooth 72. The blade 12 has an inner face 76 and an outer face 78 (defined by the curl of the cutting portion 58). The teeth are ground such that the outer face 78 is substantially flat from the tips 74 of the teeth 64 to the opposed side 26. In other words, the edges 80 and the tips 74 of the teeth 64 are flush with the outer face 76 to leave a clean cut in the lens capsule. The resulting jagged edges of the cutaway material, due to the profile of the inner face 76 are not of clinical importance, as this material is discarded. This feature is equally applicable to any of the blades described above and in particular is also shown for the blade in Figures 6A to C and Figures 7A to C.

In some embodiments, the teeth are arranged to be straight in the uncurled retracted configuration illustrated in Figure 9A. In other embodiments, the teeth are arranged to be straight (perpendicular to a plane defined by the loci) when the blade 12 is in the curled, extended configuration depicted in Figure 9B and Figure 9C. The height of the teeth may vary about the respective loci so that they cut at different moments as the blade 12 advances downwards on the surface to be cut. This variation in tooth height reduces the number of incisions made by the teeth at the same time, thereby reducing peak cutting forces. It will be understood that this is equally applicable to the non-angled blade described above with reference to Figures 6A to C and Figures 7A to C, the importance being that the height of the teeth varies such that, in the curled, extended configuration, the tips 74 of the teeth do not lie all in the same plane perpendicular to the cutting direction. The height variation results, in various embodiments, in the tips 74 of the teeth 64 defining a plane at an angle to the direction of cutting or being distributed about a plane (angled or perpendicular to the direction of cutting), for example lying in alternation on either side of the plane or defining a random distribution of heights relative to the plane. In some embodiments, the tips 74 of the teeth 64 do not lie in a common plane but may be randomly distributed around an average plane or subset of teeth may define a plurality of corresponding blades. As a result, the teeth cut at different times during the downward stroke of the blade, which may reduce peak cutting forces.

Adjacent to the first tooth 72, the cutting portion 58 comprises a rounded end portion 82 for reducing or preventing particulate generation inside the channel 16 of the introducer tube 15. Adjacent to the last tooth 70, the blade 12 has an attachment portion 60 which is shorter relative to the cutting portion 58 than for the blade described above with references to Figures 6 A to 6C and Figures 7A to 7C. The attachment portion 60 comprises an attachment feature 62 for attachment to a blade carrying portion 50, which is shaped as an elongate arm, described below but also applicable to the embodiments described above. This allows the blade itself to be shortened reducing the use of, for example, super elastic metal and hence reducing overall cost. With reference to Figures 9B and 9C₅ the cutting portion 58, in some embodiments, approximates the conical bend or frustrated cone described above using mutually angled (for example planar) bends 84 to approximate the conical bend and substantially provide the frustrated cone described above. In other words, this approximation provides a substantially conical frustrum. In the corresponding arcuate configuration, the points of the teeth create a substantially circular cut out. In some embodiments, the bends are created by shape setting, as described above, with the arcuate profile between the bends resulting from the resilience of the material. The resulting circle defined by the tips 74 of the teeth 64 is at an angle to a portion 86 of the attachment portion 60 adjacent to the attachment feature 62 to allow an angular approach of the instrument, as described above. A further portion 88 of the attachment portion 60 adjacent to the cutting portion 58 comprises a lower edge 90 which is angled with respect to the portion 86 to provide clearance for the teeth 64 cutting through the capsule without hindrance by the edge 90.

With reference to figures 1OA and 1OB and HA and HB, an embodiment providing means for supplying (or aspirating) liquid through the introducer portion 6 is now described. In capsulorhexis pressure is maintained in the eye to increase the height in the interior chamber during the operation by injection of a viscous liquid through a separate incision in the eye. By providing for the supply of liquid through the introducer portion 6, an additional mechanism for topping up the injected liquid is provided, for example as a failsafe if the main supply of liquid fails or if some of the fluid leaks away through the original incision or incisions. Alternatively all liquid can be supplied through the introducer portion 6.

With reference to Figures 1OA and B and Figures 1 IA and B a surgical tool 2 comprising means for supplying a fluid comprises a handle portion 4 which defines a hollow space for accepting a syringe 92, for example a conventional syringe having a Luer lock connection. In some embodiments, the connection may be provided external to the tool, so that the tool does not need the hollow space. The surgical tool 2 is similar to the one described 5 above in that it comprises a slider portion for actuating the blade 12 to be paid out through the introducer portion 6. The slider has an actuating portion 110 for engaging with a user's fmger or thumb (or finger and thumb of the other hand) for actuating the blade. 0 The introducer portion 6 is similar to the one described above, also having a tip with a lower tapered surface 36 (but no upper tapered surface - this is applicable to all described embodiments which may have one or two layered surfaces) and defining a channel 16 for containing the blade 12 as well as a flat portion 20 and arcuate wall 34 described above for supporting the 5 blade in its extended curled configuration.

Additionally, the channel comprises a guide rail 94 on the side of the channel facing the inner (as defined by the curl) face of the blade 12 to support the blade, and in particular the sawtooth profile, away from the remainder of the0 channel to minimise or eliminate particulate generation or jamming of the blade. An open dispensing end 96 of a capillary 98 is located in the introducer tube 15 to one side of the blade 12 in a recessed portion of the introducer tube 15. The capillary (or other tube or fluid conduit) 98 extends from the dispensing end 96 to a coupling part 106, for exampled provided with a luer5 lock coupling for coupling to the syringe 92.

With reference to Figure 1 IA an inner part 100 located inside the handle portion 4 comprises a rear portion 102 and a front portion 104. The rear portion 102 provides a stop to define a slot limiting the movement of the slider

1269263V1 portion 8 when actuated by a user applying pressure to the actuating portion 110 of the slider portion 8. The rear portion 102 further defines, cooperatively with the handle portion 4, the hollow space for accepting the syringe 92. The front portion 104 engages with a front end of the handle portion 4 and the introducer portion 6 is secured to the front portion 104 and disposed through a corresponding hole in the handle portion 4. The inner portion 100 further comprises a middle portion 105 linking the front and rear portions 104, 102 and supporting the coupling 106.

With reference to Figure HB, the slider portion comprises a protruding finger 108 defining the blade carrying portion 50 at one end thereof. The coupling 106 defines locating features 112 and 114 for engaging with the inner portion 100. The sliding portion 8 rests slidably on the inner portion 100. The capillary 98 extends from the coupling 106 through a recessed space in the blade carrying portion 50 to the dispensing opening 96.

In the above embodiments, the introducer portion 6 is straight, but other embodiments have differently shaped introducer portions. As discussed above, the required degree of resilience of the blade such that it can be elastically deformed between the expanded configuration and the retracted configuration without causing non-elastic deformations requires a thin strip of material to provide the required elasticity. However, it would be advantageous if a thicker strip of material could be used to provide a more sturdy blade. In some embodiments of the surgical tool, now described with reference to Figure 13, the introducer tip 14 and, accordingly, the channel 16 are curved with a radius of curvature which is larger than the radius of the substantially circular cutting portion in the extended configuration but significant as compared in the infinite radius of curvature of the straight channel embodiment described above. In these embodiments, since the blade only needs to move elastically between the extended configuration and a retracted configuration which is still bent (albeit at a larger radius of curvature) the requirements on the elasticity of the blade are reduced and, accordingly, a thicker strip of blade material can be used with these embodiments to provide a more stable cutting portion for the same material used.

It will be appreciated that features of the embodiments described above and shown in the drawings are independent and can be employed in various combinations, all of which are disclosed herewith. For example, a tool using the fluid supply means described above may have a saw tooth or a straight blade, one which is angled by suitable shaping or straight and may have a bent or straight introducer tube, as convenient for specific applications.

In operation, illustrated here in the context of capsulorhexis, the introducer tip 14 is introduced through an incision in the eye and into the space in front of the lens capsule. The surgeon then moves the slider 8 forward, paying out the cutting portion 12 from the introducer tip 14. As a consequence of the shape setting and the inherent resilience of the blade, the blade progressively curls into the substantially circular configuration of the cutting portion described above as it is paid out from the introducer tip 14. Once the slider 8 has been fully advanced and the blade has been disposed in its exposed configuration, it is ready for cutting. The surgeon places the substantially circular blade onto the capsule where the teeth of the saw tooth profile engage and pierce the capsule surface. The cutting action is thus not a sawing motion but rather the cutting portion is advanced through the capsule surface to pierce and cut the surface in a plurality of locations to result in a substantially circular cut as the teeth of the cutting portion have been fully pushed into the capsule. Once the cut is completed, the surgeon retracts the blade by pulling the slider back and the instrument can then be removed from the eye, followed by removal of the cut portion of the capsule, for example using forceps or during phaco-emulsification, or a similar, subsequent procedure that removes the patient's lens.

For the avoidance of doubt it will be understood that the above description of specific embodiments is made by way of example only to illustrate aspects of the invention. Indeed, many modifications, juxtapositions and alterations of the features described above will be apparent to the skilled person and are intended to be covered by the scope of the appendent claims.

Claims

1. A surgical cutting implement comprising a resilient cutting portion having a first end portion adjacent a first end of the cutting portion, a

5 second end portion adjacent a second end of the cutting portion and a sharp side between the first and second ends, the cutting portion having an arcuate configuration in which the first end portion is adjacent the second end portion and being resiliently deformable to space the first end portion away from the second end portion. 0

2. A surgical cutting implement as claimed in claim 1 which is arranged and dimensioned for capsulorhexis, in particular but not exclusively in children. 5

3. A surgical cutting implement as claimed in claim 1 or claim 2 which comprises an attachment portion, adjacent the second end, for attachment to a surgical tool

4. A surgical cutting implement as claimed in claim 3, in which the sharp 0 side is shaped to define, in the arcuate configuration, a plane which is tilted with respect to the attachment portion.

5. A surgical cutting implement as claimed in claim 4 in which the cutting portion has two or more mutually angled bends. 5

6. A surgical cutting implement as claimed in claim 4 or claim 5 in which the cutting portion defines a substantially conical frustrum in the arcuate configuration.

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7. A surgical cutting implement as claimed in any preceding claim, in which the cutting portion is arranged to define a substantially circular cut in the arcuate configuration.

5 8. A surgical cutting implement as claimed in any preceding claim, in which the sharp side has a saw tooth like profile including a plurality of teeth.

9. A surgical cutting implement as claimed in claim 8, in which the sharp 0 side defines a plurality of teeth with tips, which, in the arcuate configuration, do not lie in a common plane.

10. A surgical cutting implement as claimed in any preceding claim, in which the first end portion touches the second end portion in the 5 arcuate configuration.

11. A surgical cutting implement as claimed in any preceding claim which comprises a flat strip of resilient material having a cutting edge in the0 region of the cutting portion.

12. A surgical cutting implement as claimed in claim 11, in which the material includes a super elastic material, preferably nickel titanium. 5 13. A surgical cutting implement as claimed in claim 11 or claim 12, in which the strip is shape set in the arcuate configuration.

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14. A surgical cutting implement as claimed in any preceding claim, in which the first end portion comprises a blunt side between the first end and the sharp side.

5 15. A surgical cutting element as claimed in any preceding claim in which the first end portion has a rounded leading edge.

16. A surgical tool comprising a cutting implement as claimed in any preceding claim, the cutting implement being disposed in a channel 0 and being slideable between an exposed configuration in which the cutting portion extends in its arcuate configuration from an introducer portion of the tool and a retracted configuration in which the cutting portion is disposed in the channel with the first end spaced from the second end. 5

17. A surgical tool as claimed in claim 16 which comprises an introducer portion defining an opening of the channel for paying out the cutting portion. 0

18. A surgical tool as claimed in claim 17, in which the introducer portion is arranged and dimensioned for capsulorhexis, in particular but not exclusively in children.

19. A surgical tool as claimed in claims 17 or claim 18 which comprises5 means for supplying or aspirating fluid through the opening.

20. A surgical tool as claimed in claims 17, claim 18 or claim 19, which comprises a coupling for coupling to a syringe and a conduit extending between the coupling and the opening.

1269263V1

21. A surgical tool as claimed in claim 20 which comprises a hollow body for accepting the syringe.

5 22. A surgical tool as claimed in any of claims 17 to 21, which the introducer portion has a tapered end.

23. A surgical tool as claimed in any of claims 17 to 22, in which the introducer portion defines a support surface adjacent the first and 0 second end portions opposite the sharp side of the cutting implement in the exposed configuration.

24. A surgical tool as claimed in any of claims 17 to 23, in which the introducer portion defines an abutment for engaging a feature of the 5 attachment portion in the exposed configuration of the cutting implement.

25. A surgical tool as claimed in any of claims 17 to 24, in which the channel comprises a substantially straight portion such that the cutting0 portion is substantially straight in the retracted configuration of the implement.

26. A surgical tool as claimed in any of claims 17 to 24, in which the channel comprises a curved portion such that the cutting portion is5 curved in the retracted configuration of the implement.

27. A surgical tool comprising a cutting element disposed in a channel and being slideable within the channel between an exposed and a retracted

1269263v1 configuration, the channel having an opening and the surgical tool comprising means for supplying or aspirating a fluid through the opening.