Microsurgical probe

Microsurgical Probe

Field of the Invention

The present invention relates generally to microsurgical probes and, more particularly, to ophthalmic microsurgical probes, such as vitrectomy probes.

Description of the related technique

Ophthalmic surgical procedures of the posterior segment generally require the cutting and / or removal of the vitreous humor, a transparent gelatin-like material that fills the posterior segment of the eye. Vitreous humor,

or vitreous, it is composed of numerous microscopic fibers that are often coupled to the retina. Therefore, the cutting and removal of the vitreous should be carried out very carefully in order to avoid traction on the retina, the detachment of the choroid retina, a tear of the retina or, in the worst case, the cutting and removal of the retina itself.

The use of microsurgical cutting probes in ophthalmic surgery of the posterior segment is well known. Such vitrectomy probes are typically inserted through an incision in the sclera, near the pars plana. The surgeon can also insert other microsurgical instruments, such as a fiber optic illuminator, an infusion cannula, or an aspiration probe during posterior segment surgery. The surgeon performs the procedure, while viewing the eye through a microscope.

Conventional vitrectomy probes typically include a hollow outer cutting element, a hollow inner cutting element arranged coaxially with and arranged so that it can move in the hollow outer cutting element, and a port that extends radially through said outer cutting element near its distal end. The vitreous humor is sucked into the open port and the inner element is activated, closing the port. After the closing of said port, the cutting surfaces in both inner and outer cutting elements cooperate to cut the vitreous and then the cut glass is sucked out by the inner cutting element. US Patents 4,577,629 (Martinez); No. 5,019,035 (Missirlian et al.); No. 4,909,249 (Akkas et al.); No. 5,176,628 (Charles et al.); No. 5,047,008 (de Juan et al.); No. 4,696,298 (Higgins et al.); No. 5,733,297 (Wang) discloses various types of vitrectomy probes and US 2005/0135776 describes a cutting tool comprising a sleeve incorporating a suction chamber.

During ophthalmic surgery of the posterior segment, it is generally desirable to remove as much overlapping vitreous as possible, before any procedure to repair the underlying retina. However, the surgeon is limited to the proximity with which a conventional vitrectomy probe can be arranged with respect to the retina, due to the geometry of the tip of said probe and the cutting port. Therefore, there remains a need to provide an improved vitrectomy probe that does not suffer from the limitations mentioned above.

Summary of the invention

In accordance with the foregoing, a method according to claim 1 is provided.

Brief description of the drawings

For a better understanding of the present invention, and for the purposes and additional advantages thereof, reference is made to the following description considered in conjunction with the accompanying drawings, in which:

Figure 1 is a fragmented sectional side view of the distal part of a vitrectomy probe according to a preferred embodiment of the present invention;

Figure 2 is a fragmented sectional side view of the distal part of a vitrectomy probe;

Figure 3 is a fragmented sectional side view of a second conventional vitrectomy probe;

Figures 4A to 4C schematically illustrate a process for manufacturing the vitrectomy probe of Figure 1, in accordance with a preferred embodiment of the present invention;

Figure 5 is an enlarged, fragmented, sectional and schematic view of a preferred tool for the process of Figures 4A to 4C; and

Figures 6A to 6C schematically illustrate a second process for manufacturing the vitrectomy probe of Figure 1, in accordance with a preferred embodiment of the invention.

Detailed description of the preferred embodiments

Preferred embodiments of the present invention, as well as their advantages, will be better understood by referring to Figures 1 to 6 of the drawings, the same reference numbers being used for the same and corresponding parts of the different drawings.

Figure 1 shows the distal part of a vitrectomy probe 10 according to a preferred embodiment of the present invention. Said probe 10 generally includes a tubular body 12 provided with an inner hole 14, a closed distal tip 16, and a port 18 that provides access to the inner hole 14. The tubular body 12 is preferably made of stainless steel. An inner cutting element (not shown) is longitudinally reciprocating with the inner hole 14, so that the tissue aspirated into the inner hole 14 is cut through port 18 by a surgical console (not shown). The distal tip 16 provides a flat outer surface 16a and a flat inner surface 16b. Said probe 10 preferably has a diameter between 0.5 mm (25 ga) and 0.9 mm (20 ga).

Figures 2 and 3 show the distal parts of conventional vitrectomy probes 22 and 24, respectively. Said probes 22 and 24 generally include a tubular body 26 provided with an inner hole 28, distal tips 30 and 30a closed, and a port 32 providing access to the inner hole 28. Preferably, the tubular body 26 is made of stainless steel . An inner cutting element (not shown) is longitudinally reciprocating with the inner hole 28, so that the tissue aspirated into the inner hole 28 is cut through port 32 by a surgical console (not shown).

The distal tip 30 has a convex and spherical outer surface 34 and a concave and spherical inner surface

36. The distal tip 30 is manufactured using a conventional embossing process. In conventional embossing, a fixed tubular needle is rotated and a tool provided with a generally concave distal end is brought into contact with the end of the needle. The force of the tool on the rotating needle closes the end of the tube and creates a distal tip 30 that has a spherical geometry.

The distal tip 30a provides a flat outer surface 42 and a convex spherical inner surface 44. Said distal tip 30a is manufactured using a conventional bead welding (or TIG) process. In a conventional bead welding, an electrode is disposed on the end of the fixed tubular needle and an electric current is passed between the needle and the electrode. A cord of material is formed at the end of the needle, creating a closed distal tip 30a that has a spherical geometry. Secondary machining operations are carried out on the outer surface 42, to flatten it. However, said inner surface 44 maintains a convex spherical shape because the inner welding arc is difficult to control.

As explained in greater detail below, the flat outer surface 16a and the flat inner surface 16b are preferably formed using an improved embossing process, or a resistance welding process. The flat outer surface 16a and the flat inner surface 16b give rise to a distal end 18a of the port 18 with a smaller distance 20 with respect to the outer surface 16a compared to the distance 40 between the distal end 38 of the port 32 and the surface outer 34 of the conventional probe 22, or the distance 48 between the distal end 46 of the port 32 and the outer surface 42 of the conventional probe 24. The flat inner surface 16b also allows the distal end 18a of the port 18 to be arranged in an almost coplanar arrangement with respect to the inner surface 16b. On the contrary, the distal end 38 of the port 32 of the conventional probe 22 is offset with respect to its inner surface 36 due to the concave spherical geometry of the inner surface 36. Similarly, the distal end 46 of the port 32 of the conventional probe 24 is displaced from its inner surface 44 due to the uncertainty tolerances of the inner welding arc in the bead welding process. Preferably, the distance 20 will be between approximately 0.1524 mm (0.006 inches) and 0.406 mm approximately (0.016 inches) and more preferably between 0.1524 mm approximately (0.006 inches) and approximately 0.2794 mm (0.11 inches) . Preferably, the distal end 18a of port 18 is disposed between approximately 0.0762 mm (0.003 inches) and 0.127 mm (0.005 inches) with respect to the inner surface 16b. By reducing the distance 20, the surgeon can arrange the probe 10 closer to the retina without making contact with it. Thus, with the probe 10 the surgeon can remove more of the overlapping vitreous prior to performing the procedure to repair the underlying retina than with conventional probes 22 or 24.

Figures 4A to 4C and Figure 5 schematically illustrate an improved and preferred embossing process for the formation of a vitrectomy probe 10. The tubular needle fixed 100 is arranged in a clamp jaw 102 of the lathe (not shown ), in the conventional way. Said clamping jaw 102 and, thus, the needle 100, are rotated at a high speed, as indicated by arrow 104. A tool 106 having a generally flat distal surface 108 with a generally spherical projection 110 is brought into contact with an edge 112 of a distal end 114 of the needle 100, as shown in Figure 4B. Said tool 106 moves along the entire face of the distal end 114 from the edge 112 in the direction of the arrow 118. Alternatively, the tool 106 moves along the face of the distal end 114 from the edge 112 to pass slightly beyond a center line 116 of the needle 100 in the direction of the arrow 118, as shown in Figure 4C . The force of the projection 110 that contacts the distal end 114 of the needle 100 causes the displacement of the material that forms the needle 100. When the shoulder 110 reaches the center line 116, the distal end 114 of the needle 100 is closed, so that it forms the distal end 16 of the probe

10. Preferably, the diameter of the spherical projection 110 is +/- ten percent of an outer diameter of the needle 100. Preferably, the flat outer surface 16a is machined so that it has a radius or chamfer at its periphery to facilitate the incision in the flat pars.

Figures 6A to 6C schematically illustrate a preferred resistance welding process, to form the vitrectomy probe 10. The distal end 114 of the fixed tubular needle 100 is brought into contact with a sheet of stainless steel sheet 150, and is exerted a compressive force indicated with the arrows 152 on the needle 100 and the sheet 150. Preferably, said sheet 150 has a thickness of approximately 0.1016 mm (0.004 inches). An electrode 154 is disposed on one side of the needle 100, and an electrode 156 is disposed on the sheet 150. An electrical pulse is sent between electrodes 154 and 156. As the electrical pulse moves from the needle 100 to the sheet 150, there is a localized zone of high resistance that generates heat and welds the distal end 114 to the sheet 150 in a fusion zone 158. The needle 100 is disposed in a punch die 160 and then the needle 100 is pierced through the sheet 150 (as shown in Figure 6C), so that the tip of the welded sheet 162 forms a distal end 16 of the probe 10. A preferred resistance welding machine is the model 125 resistance welding machine available from the Miyachi Unitek Corporation of Monrovia, California. Preferably, a micro welding head available from Miyachi Unitek Corporation, containing electrode 156, is used with said resistance welding machine model 125. A preferred welding cycle is a dual pulse cycle with a power range between ten times one hundred (10%) and sixty percent (60%). Preferably, the outer flat surface 16a is machined so that it has a radius or chamfer at its periphery, to facilitate the incision of the flat pars.

From the foregoing, it can be seen that the present invention provides an improved apparatus and method for performing vitrectomy surgery. The present invention is illustrated herein by way of example, and one skilled in the art may make various modifications. For example, although the present invention is described herein in relation to a vitrectomy probe, it can be applied to other ophthalmic microsurgical probes and other non-ophthalmic microsurgical probes. As another example, although the present invention is described herein in relation to a cutting probe, it can also be applied to an aspiration probe.

The operation and construction of the present invention are considered to be apparent from the above description. Although the apparatus and procedures that have been shown or described above have been characterized as preferred, various changes and modifications can be made therein without thereby departing from the scope of the invention as defined in The following claims.