Trephine for corneal graft cutting

Abstract

The invention relates to a trephine for corneal graft cutting, the trephine comprising a blade holder and a blade mounted on the blade holder. The blade is provided, opposite the blade holder, with a sharp free edge extending around a closed contour. According to the invention, the blade is a strip that has a longitudinal first edge forming the sharp free edge of the blade, wherein the strip is shaped as a loop that is deformable between at least two states defining two diameters for the closed contour, and wherein the blade holder is arranged to hold the blade selectively in each of these states.

Description

[0001] DESCRIPTION

[0002] TITLE OF THE INVENTION: Trephine for cutting corneal graft

[0003] The present invention relates to the field of corneal transplantation, in particular the field of graft preparation for corneal surgeries.

[0004] BACKGROUND OF THE INVENTION

[0005] Graft cutting is performed by an operator (surgeon or eye bank technician) from a donor cornea. The operator will cut the graft directly from the cornea using a manual cutting instrument or a laser to obtain the graft adapted to the patient to be treated and the planned surgery. For several years, there have been cutting devices commonly called "punch" devices. A punch comprises, on the one hand, a circular base in the center of which the donor corneal tissue is held by an automatic or manual suction system connected to the base and, on the other hand, a trephine which includes a blade and which fits around the base thus allowing the operator to cleanly cut the piece of cornea according to the morphology and indications of the patient to be grafted.

[0006] These devices are generally single-use and allow a circular cut of a single diameter predefined by the trephine used. Thus, commercial punches are defined according to the most common graft diameters. We thus typically find punches for diameters of 6 mm to 11 mm, sometimes a little more. Each punch thus allows the cutting of a single graft diameter. For example, there are punches for diameters of: 6.0 mm, 7.5 mm, 7.75 mm, 8 mm, 8.5 mm, 9.5 mm, 10 mm, etc. requiring having punches in stock covering the entire range in sufficient quantity to perform graft operations for all types of patients. This inventory management is complex and costly with a risk of not having the appropriate punch at the time of surgery if this management is not carried out correctly or of throwing away unused punches.Furthermore, if the operator wishes to reduce the diameter of a graft already cut using a first punch, he must use another drill bit with a diameter adapted to the base to make a new cut or move the graft to a second punch equipped with a drill bit with a smaller blade diameter, further complicating stock management and operating costs.

[0007] SUBJECT OF THE INVENTION

[0008] The invention aims in particular to at least partially overcome the aforementioned drawbacks.

[0009] SUMMARY OF THE INVENTION

[0010] For this purpose, a corneal graft cutting trephine is provided, comprising a blade holder and a blade mounted on the blade holder. The blade is provided, opposite the blade holder, with a free cutting edge extending along a closed contour. According to the invention, the blade is a strip which has a first longitudinal edge forming the free cutting edge of the blade, said strip being shaped into a loop deformable between at least two states defining two diameters of the closed contour, the blade holder being arranged to hold the blade selectively in each of these states. Thus, the trephine according to the invention makes it possible to cut the graft according to a diameter determined prior to the cutting step without having to choose a trephine with a predefined diameter. The trephine according to the invention also allows the operator to make a second cut of a diameter smaller than the first cut with the same trephine simply by adjusting the diameter of the loop formed by the blade.Thus, with a single trephine according to the invention, it is possible to cut a graft according to the desired diameter or to make successive cuts with decreasing diameters of the graft while avoiding its handling or the use of several trephines. The trephine according to the invention is at the same time more practical, simpler and more economical to use, manage and store.

[0011] According to the invention, the strip forming the blade is preferably received with longitudinal sliding in a groove arranged in a spiral in a bottom of the blade holder around a central axis of the blade holder in such a way that the cutting edge extends projecting from the groove and the groove holds the strip in the form of a loop around the central axis. The blade has a first end, closer to the central axis of the blade holder, formed by a tongue which is provided with the cutting edge and which extends completely outside the groove to come into contact with a portion of the lateral surface of the blade oriented towards the central axis so as to close the loop formed by the blade in the two states of deformation of the strip.

[0012] Preferably, the groove is provided in a through manner in the bottom of the blade holder in such a way that the strip has a second longitudinal edge which projects from the groove opposite the first longitudinal edge.

[0013] The drill bit according to the invention may further comprise a button mounted on the bottom of the blade holder, on a side opposite the cutting edge of the blade, to pivot around the central axis of the blade holder. The button comprises at least one connecting element with a portion of the second longitudinal edge of the strip to be able to push the latter along the groove. More particularly, the connecting element comprises a relief engaged in a notch provided in the second longitudinal edge of the strip.

[0014] Optionally, the button can be mounted on the blade holder in a removable manner.

[0015] One of the blade holder or the button of the drill bit may further comprise at least one mark and the other of the blade holder or the button graduations centered on the central axis so as to be able to indicate the diameter of the loop formed by the strip as a function of the angular position of the button.

[0016] Thus, the operator can, using the knob mounted on the bottom of the blade holder, easily adjust the diameter of the loop formed by the blade between a minimum diameter and a maximum diameter, the marks and graduations on either the blade holder or the knob allowing the operator to precisely adjust the diameter of the loop to obtain the graft at the desired diameter by engaging the drill bit on the base without having to change the blade holder.

[0017] The invention also relates to a punch comprising such a drill bit.

[0018] Other characteristics and advantages of the invention will emerge from reading the following description of a particular and non-limiting embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Reference will be made to the attached drawings, including:

[0020] [Fig. 1] Figure 1 is a sectional view of a punch according to the invention; [Fig. 2] Figure 2 is a slightly perspective view from below of a drill bit according to the invention, the blade being set to an intermediate cutting diameter, between a minimum diameter and a maximum cutting diameter;

[0021] [Fig. 3] Figure 3 is a detail view of the central interior portion of the blade holder of this drill bit;

[0022] [Fig. 4] Figure 4 is a side view of the blade alone; [Fig.5] Figure 5 is a slightly perspective view from below of the drill bit, during mounting of the blade on the blade holder;

[0023] [Fig. 6] Figure 6 is a slightly perspective top view of this drill bit with the button removed from the core holder;

[0024] [Fig. 7] Figure 7 is a slightly perspective top view of this drill bit, the button being engaged on the blade holder;

[0025] [Fig. 8] Figure 8 is an axial sectional view of the drill bit according to the invention;

[0026] [Fig. 9a] Figure 9a is a view similar to Figure 2 with the blade defining the minimum cutting diameter; [Fig. 9b] Figure 9b is a view similar to Figure 2 with the blade defining the maximum cutting diameter DETAILED DESCRIPTION OF THE INVENTION

[0027] With reference to figures 1 to 9b, according to a particular embodiment, the invention relates to a punch comprising a base B and a drill bit 1. Conventionally, the drill bit 1 is shaped so that it can be engaged on the base B.

[0028] The base B is cylindrical and comprises an upper face B1 provided with a support surface B2 for the cornea to be cut. The trephine 1 comprises a blade holder 2 and a blade 3 mounted on the blade holder 2. Here, the blade holder 2 comprises a cover

[0029] 4 comprising a cylindrical wall 8, with central axis X, having an annular free edge 7 and, opposite, an end closed by a bottom 5. The bottom 5 is partially open by notches 6 extending astride the bottom 5 and the cylindrical wall 8 and delimiting between them arms 9. The cover 4 of the blade holder 2 here comprises three notches 6 but could comprise one, two or more than three.

[0030] The bottom 5 of the cover 4 has an internal surface provided with a bulge 10 which extends projectingly and in the center of the bottom

[0031] 5 towards the inside of the cover 4. The bulge 10 is shaped so as to receive a blade 3. Here, the bulge 10 comprises a groove 11 arranged in a spiral around the central axis X to receive the blade 3, here mounted to slide longitudinally in the groove 11. Those skilled in the art will know how to define the width of the groove as a function of the thickness of the blade so that the blade 3 is held while allowing sliding.

[0032] According to the invention and as particularly illustrated in Figure 4, the blade 3 has a single-piece strip shape which has a first longitudinal edge 12 sharpened to form the free cutting edge of the blade 3 and a second opposite longitudinal edge 13, said first and second edges extending between first and second ends 16, 18 of the blade 3, delimiting a first inner lateral surface 14 and a second opposite outer lateral surface 15 of height h when the blade 3 is wound on itself. The first end 16 is extended by a tongue 17 extending projecting along the cutting edge 12, of length and height hl, hl being less than h. Preferably, the blade is made of stainless steel. Those skilled in the art will be able to determine the thickness of the blade such that it is sufficiently flexible to be shaped into a spiral while being sufficiently held by the groove 11 and having relative transverse rigidity.By way of illustration, the thickness of the blade may be between 0.03 and 0.2 mm, preferably 0.1 mm. A person skilled in the art will also be able to provide restrictions, cutouts, extra thicknesses, reinforcements, etc. to improve the flexibility of the blade 3 along its length while maintaining relative rigidity over its height h.

[0033] Furthermore, as more particularly visible in Figure 4, the blade here comprises three tabs 19, 20, 21. The tab 19 is delimited in the second longitudinal edge 13 by a notch formed in the second end 18 parallel to the second longitudinal edge 13 and at a height h2 of said second longitudinal edge 13. The tab 20 is delimited in the second longitudinal edge 13 by a second notch, substantially L-shaped, formed in the second longitudinal edge 13 substantially halfway along the length of the blade 3, the large bar of the L being parallel to the second longitudinal edge 13 and the small bar of the L being formed perpendicular to the second longitudinal edge 13. The small bar of the L has a height equal to h2. The tab 21 extends in the extension of the second longitudinal edge 13, parallel to the tab 17 and opposite it.

[0034] The blade 3 also comprises a third notch 22 which has a depth and a width substantially equal to h2 and which is located close to the first end 16. As illustrated particularly by FIG. 5, the blade 3 is received with longitudinal sliding in the groove 11 formed spirally in the bulge 10 around the central axis X of the blade holder 2 in such a way that the cutting edge 12 projects from the groove 11, at least by the height hl, towards the inside of the cover 4 and the second longitudinal edge 13 projects from the groove 11, at least by the height h2, towards the outside of the cover 4. The blade 3 is engaged in the groove 11 in such a way that the first end 16 is closest to the central axis X.The tongues 19, 20 and 21 extend completely out of the groove 11 so that they remain rectilinear and will project laterally above the edges of the groove 11: the tongues 19, 20 and 21 thus oppose a movement of the blade 3 towards the inside of the cover 4 (see figure 6). The tongue 17 also extends completely out of the groove 11 so that the tongue 17 tends to remain rectilinear and the external lateral surface 15 of the tongue 17 comes to bear on a portion of the internal lateral surface 14 of the blade 3 oriented towards the central axis X: the tongue 17 thus comes to close the loop formed by the strip.It is understood that the degree of axial penetration of the blade 3 into the groove 11 makes it possible to define a loop of greater or lesser diameter: the loop formed by the blade 3 is therefore deformable between a first state defining the maximum diameter of the loop (for example, the diameter may be 10 mm) in which the tongue 17 bears against a portion of the lateral surface 14 in the immediate vicinity of the second end 18 as illustrated in FIG. 9b and a second state defining a minimum diameter of the loop in which the tongue 17 bears against a portion of the lateral surface 14 furthest from the second end 18 of the blade 3 as illustrated in FIG. 9a. For example, the minimum diameter of the loop may be 7.5 mm.It is easily understood that the diameter of the loop formed by the support of the external surface 15 of the tongue 17 on the internal surface 14 can take any value between the two states of deformation of the strip between the minimum diameter and the maximum diameter. It is specified that here the shape of the closed loop is assimilated to a circle although it is not perfect. Thus, the term "diameter" designates the diameter of the circle inscribed in the closed loop. The person skilled in the art is able to adapt the shape and the length of the groove 11 and the length l of the tongue 17 and the length C of the blade 3 so as to define the diameter interval between the two extreme positions desired to form the closed loop. As a non-limiting example, here the groove 11 is helical in shape with a pitch of 0.9 mm, the length of the groove 11 is 62 mm.

[0035] The blade 3 slides along the groove 11 so that it can be adjusted from the smallest diameter, here 7.5 mm, to the largest, here 10 mm. The lengths C of the blade and Cl of the tab 17 defined accordingly are here respectively 26.9 mm for C and 6 mm for Cl.

[0036] The width of groove 11 is here 0.2 mm to allow free sliding of the blade 3, here with a thickness of 0.1 mm in the groove 11.

[0037] Preferably, the groove 11 is arranged in a through manner in the tubular support 10 so that the second longitudinal edge 13 of the blade 3 projects from the groove 11 opposite the first cutting edge 12. Thus, the operator can adjust the diameter of the loop in complete safety by using the second longitudinal edge 13 rather than the cutting edge 12. It is specified that the second longitudinal edge 13 here projects from the groove by a height equal to h2. In other words, the height of the groove has a height equal to h- (hl+h2). As stated, the means for locking the blade 3 in the groove 11 are constituted by the tongues 19 to 21 which will come to bear on the bottom of the cover 4 so as to prevent the blade 3 from falling from the groove 11 when it is engaged therein.

[0038] Advantageously, according to the invention, the drill bit may comprise a knob 23 for adjusting the loop formed by the blade 3, as is particularly illustrated by FIGS. 6 to 8. The knob 23 is mounted on the bottom 5 of the blade holder 2 on a side opposite the cutting edge of the blade so as to be able to pivot around the central axis X of the blade holder 2. The knob 23 is here cylindrical and comprises a lower face 24 facing the second longitudinal edge of the blade and an opposite upper face 25 visible to the operator using the drill bit. The upper face 25 here comprises a gripping element 26 projecting from the upper face so that the operator can easily manipulate the knob 23 by rotation. A person skilled in the art is able to define any means to facilitate the manipulation of the button 23. By way of non-limiting examples, the gripping element can thus have the shape of a rectangular bar, a half-sphere, a ring, etc.The lower face 24 of the button 23 comprises at least one connecting element 27 with a portion of the second longitudinal edge 13 of the strip to be able to push the blade 3 along the groove 11. The diameter of the button 23 is here defined such that it can be inserted by rotation into a central orifice of the bulge 10 so that on the one hand the connecting element 27 and the portion of the second longitudinal edge 13 are connected and on the other hand the gripping element 26 is easily manipulated by the operator. Preferably, the connecting element 27 of the button 23 comprises a relief engaged in the notch 22 formed in the second longitudinal edge 13 of the blade 3. Advantageously the connecting element 27 has a shape complementary to that of the notch 22. Here, the connecting element 27 therefore has a parallelepiped shape.The knob 23 can be made of any plastic or metal material, it is preferably a single piece but can also be made of several assembled parts. The knob 23 can be permanently fixed to the blade holder 2 or can be removable, thus facilitating maintenance of the drill bit (cleaning, blade change, for example). Advantageously, one of the blade holder 2 or the knob 23 comprises at least one mark and the other of the blade holder 2 or the knob 23 graduations centered on the central axis X so as to be able to indicate the diameter of the loop formed by the blade 3 in the two deformation states. A person skilled in the art will know how to produce the mark and the graduations so that the operator can identify the diameters of the loop most often used as well as the interval of the graduations, so as to know by how much the diameter of the loop is increased or decreased when he turns the knob 23 clockwise or counterclockwise.By way of illustration, the button 23 may comprise a mark and the blade holder 2 may comprise graduations which may mention values ​​identifying the diameter of the loop formed by the blade 3. For example, the values ​​10 - 8.75 and 7.5 may be mentioned on the blade holder in a clockwise direction to identify loop diameters of 10 mm, 8.75 mm and 7.5 mm respectively, other intermediate graduations may represent the step by which the diameter is modified, for example intermediate graduations may signify a step of 0.25 mm. Those skilled in the art will be able to use any marking means for the mark and the graduations so that they are perfectly legible by the operator. For example, the mark and / or the graduations may be printed with ink or laser-marked, engraved in hollow or shown in relief.

[0039] Thus and as illustrated by figures 2, 9a, 9b, the operator will determine a first desired cutting diameter, for example 10 mm as illustrated by figure 9b by turning the knob 23 via the gripping element 26 to align the mark on the knob with the graduation “10” on the blade holder. The knob 23 via the connecting element 27 engaged in the notch 22 of the blade 3 will drive the blade such that the tab 17 comes to bear on a portion of the lateral surface 14 closest to the second end 18 of the blade 3 and thus form a closed loop 10 mm in diameter. The operator will then fully engage the trephine on the base to cut a corneal graft with the cutting edge 12 of the blade 3. The graft thus obtained has substantially the shape of a disc 10 mm in diameter.If the operator wishes to cut either a graft of smaller diameter or a corneal ring, he will completely or partially disengage the trephine 1 from the base B. He will then modify the setting of the knob 23 to align the mark with the desired graduation, for example 8.75 as illustrated in Figure 2. The clockwise rotation of the gripping element 26 of the knob 23 will push the blade 3 along the groove 11 so that the tongue 17 comes to bear on a portion of the lateral surface 14 to form a closed loop with a diameter of 8.75 mm. The operator will then completely engage the trephine again on the base B so that the blade 3 cuts a second corneal graft, also substantially disc-shaped, with a diameter of 8.75 mm.

[0040] Figure 9a illustrates an adjustment which corresponds to the second state defining a minimum diameter of the loop, here for example 7.5 mm, in which the tab 17 comes to bear on a portion of the lateral surface 14 furthest from the second end 18 of the blade 3. The operator will then repeat the steps of engaging the trephine 1 on the base B to cut the corneal graft. The operator can thus make as many cuts of the same graft as necessary with different diameters without having to change either the trephine or the punch, he simply has to modify the diameter of the blade 3 as needed.

[0041] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0042] In particular, the number and shape of the tabs 19, 20, 21 and of the notch 22 may be different. The notch may be held in the groove 11, for example, by welding studs onto the second longitudinal edge 13. The notch 22 may, for example, be replaced by a projection cooperating with a recess in the button 23.

[0043] The diameter of the loop formed by blade 3 is here adjusted by the knob 23 mounted on the bottom 5 of the blade holder 2 but the adjustment of the diameter of the loop can also be done by means of a slider engaged on the second lateral edge 13 of the blade 3 projecting from the bottom 5 on a side opposite the cutting edge of the blade. The slider can alternatively be located on another part of the blade holder 2, said slider then being fixed on the external lateral surface 15 of the blade 3.

[0044] The person skilled in the art will be able to make any modification necessary for the intended application. He will be able to adapt the shape, the material, the dimensions (thickness, length, height) of the blade 3, as well as the conformation of the groove 11 of the blade holder 2.

[0045] In order to reinforce the retention of the blade 3 in the groove 11, the person skilled in the art can also provide means for locking the blade 3 in the groove 11.

[0046] For safety reasons, in particular to avoid incorrect handling which would result in damaging the graft, the person skilled in the art can provide safety means aimed at preventing any back-and-forth movement of the blade 3 in the groove 11 from a second state defining a minimum diameter to a first state aiming for a maximum diameter. Thus, the safety means constrain the movement of the blade 3 in the groove 11 in the direction of reducing the diameter of the loop, and thus prevent any back-and-forth movement. In other words, if the user has defined a first setting corresponding to a first diameter, for example a diameter less than 8.8 mm, he will not be able to define a second setting aimed at obtaining a second diameter greater than the first, that is to say for example greater than 8.8 mm.The person skilled in the art is able to define any safety means capable of preventing the movement of the blade 3 from a second state defining a minimum diameter to a first state defining a maximum diameter. By way of illustration, the safety means can thus prevent the counterclockwise rotation of the button 23. The safety means can alternatively or additionally comprise a device for breaking the blade when the user attempts to move from a second state defining a minimum diameter of the loop to a first state defining a maximum diameter of the loop. The safety means can alternatively or additionally comprise notches in the groove 11 to prevent the blade 3 from moving from a second state defining a minimum diameter of the loop to a first state defining a diameter greater than that of the second state.

Claims

CLAIMS 1. Trephine (1) for cutting corneal graft, comprising a blade holder (2) and a blade (3) mounted on the blade holder (2) and provided, opposite the blade holder, with a free cutting edge (12) extending along a closed contour, characterized in that the blade (3) is a strip which has a first longitudinal edge forming the free cutting edge of the blade and which is shaped into a loop deformable between at least two states defining two diameters of the closed contour, and in that the blade holder (2) is arranged to hold the blade selectively in each of these states.

2. A drill bit according to claim 1, wherein the blade (3) is received with longitudinal sliding in a groove (11) arranged in a spiral in a bottom of the blade holder around a central axis (X) of the blade holder in such a way that the cutting edge (12) extends projecting from the groove (11) and the groove (11) holds the strip in the form of a loop around the central axis; the blade having a first end (16), closer to the central axis (X) of the blade holder, formed of a tongue (17) which is provided with the cutting edge and which extends completely out of the groove to come into contact with a portion of the lateral surface of the blade oriented towards the central axis so as to close the loop formed by the strip in the two states of deformation of the strip.

3. A drill bit according to claim 2, wherein the groove (11) is provided transversely in the bottom of the blade holder in such a way that the strip has a second longitudinal edge (13) extending projecting from the groove (11) opposite the first longitudinal edge.

4. Drill bit according to claim 3, comprising a button (23) mounted on the bottom (5) of the blade holder (2), on a side opposite the cutting edge of the blade, to pivot around the central axis of the blade holder, the button comprising at least one connecting element (27) with a portion of the second longitudinal edge (13) of the strip to be able to push the latter along the groove (11).

5. Drill bit according to claim 4 in which the connecting element (27) comprises a relief engaged in a notch (22) provided in the second longitudinal edge (13) of the strip.

6. A drill bit according to claim 4 or 5, wherein the button (23) is removably mounted on the blade holder.

7. A drill bit according to claims 4 to 6, wherein one of the blade holder (2) or the button (23) comprises at least one mark and the other of the blade holder or the button comprises graduations centered on the central axis (X) so as to be able to indicate the diameter of the loop formed by the strip as a function of the angular position of the button.

8. Punch comprising a base (B) defining a support surface (B2) for the graft and a drill bit (1) according to any one of the preceding claims, the blade holder (2) being removably mounted on the base (B) in such a way that the blade (3) extends opposite the support surface of the graft.

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