WO2003101323A1 - Rf micro-needle for glaucoma surgery - Google Patents

Rf micro-needle for glaucoma surgery Download PDF

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Publication number
WO2003101323A1
WO2003101323A1 PCT/DK2003/000359 DK0300359W WO03101323A1 WO 2003101323 A1 WO2003101323 A1 WO 2003101323A1 DK 0300359 W DK0300359 W DK 0300359W WO 03101323 A1 WO03101323 A1 WO 03101323A1
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WO
WIPO (PCT)
Prior art keywords
micro
degrees
needle
conductor
needle according
Prior art date
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PCT/DK2003/000359
Other languages
French (fr)
Inventor
Svend Vedel Kessing
Ole I. Nissen
Original Assignee
Rigshospitalet
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Publication date
Application filed by Rigshospitalet filed Critical Rigshospitalet
Priority to AU2003233784A priority Critical patent/AU2003233784A1/en
Publication of WO2003101323A1 publication Critical patent/WO2003101323A1/en

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/14—Probes or electrodes therefor
    • A61B18/1402—Probes for open surgery

Definitions

  • the present invention relates to a micro-needle for glaucoma surgery and a method of using the same, and more specifically the invention relates to a bipolar diathermal micro- needle. Furthermore, the invention relates to a method of creating a micro-canal in the cornea with the necessary thermal coagulation of the wall in said micro-canal.
  • Glaucoma is a decease where intraocular pressure is elevated to a point where the optic nerve is damaged, progressively and irreversible.
  • the present invention is the third generation of micropenetrating surgery, i.e. filtering glaucoma operations where the inner outflow opening has a surgically created diameter of less than e.g. 200 micron, which means about physiological dimensions in contrast to the conventional filtering glaucoma operation (Trabeculectomy).
  • SLS Subconjunctival Holmium Laser Sclerostomy
  • the second generation was the clear-cornea, guarded Intrastromal Holmium Laser Keratostomy (ILK) developed in Copenhagen 1994.
  • ILK Intrastromal Holmium Laser Keratostomy
  • the aim of ILK was to change the localisation of the laser micro-canal and the construction of the outflow system.
  • the laser canal was therefore positioned intrastromally in the cornea, in front of Schwalbe's line, in the floor of a corneo-scleral tunnel incision formed with a knife.
  • the laser probe was introduced into the tunnel incision from the corneal side, that is, there were no opening in the conjunctiva.
  • the invention relates to a bipolar diathermal micro-needle for creating a micro-canal, said needle comprising a first and a second electrical conductor, wherein
  • the needle comprises a first and a second electrical conductor, but could also comprise further conductors such as a plurality of three conductors or four conductors or five conductors or six conductors. Some of the conductors may be adapted to generate an arc between the conductors while other conductors may be used to determine parameters in the operation area such as temperature or PH value.
  • the arc may be used to cut tissue and to coagulate the tissue e.g. such that a micro-hole created in the tissue is maintained. If the hole is not coagulated the sidewalls of the tissue may press against each other closing the hole again. Further the coagulation cause some shrinkage of the surrounding corneal tissue preventing self-sealing of the combined outflow system (diathermal micro-canal and surgical tunnel-incision).
  • the diathermal micro-needle is preferably used for creation of a micro-canal by glaucoma operations, but could also be used for neuro-surgery or surgery in the cranium or surgery in the hand or surgery in ears such as in the inner ear or surgery in the foot or surgery in the genitalia or any other kind of micro surgery or micropenetrating surgery.
  • the first and second conductor may be provided on each side of a tissue so as to burn a hole in the tissue when an electric field is generated between the conductors, and thus it may be prevented that the conductors are inserted into the tissue.
  • the conductors may be arranged so that only one of the conductors are inserted into the tissue and so that an arc is generated between the conductor inserted into the tissue and the conductor which is not inserted into the tissue.
  • the conductors may be arranged such that two conductors are inserted into the tissue and that an arc is generated between the conductors when both conductors are inserted into the tissue.
  • the first conductor may define a cylindrical cutting part with a peripheral surface and an end surface.
  • the cutting edge may be a transition between the peripheral surface and the end surface.
  • the end surface may be concave or convex or may have a cross sectional shape being substantially similar to at least a part of a parabola or an ellipse or a circle.
  • the surface may extend in two dimensions and thus be a plane but could also extend in three dimensions.
  • the cutting part may be oblong thus being substantially longer than wide.
  • the cutting part may be two times longer than wide or three times longer or four times longer or five times longer or six times longer or seven times longer or eight times longer or nine times longer or ten times longer.
  • the cutting part may be an end part of the first conductor, but could also be provided on a part of the first conductor located between the ends of the conductor, e.g. the conductor may bend with an angle sufficiently sharp to provide a cutting edge.
  • the oblong cutting part may extend in a direction transverse to at least one other part of the first conductor.
  • a major part of the first conductor may extend in a first direction while a small part extends in a second direction, said second direction being transverse to the first direction.
  • the first conductor may define three zones extending in different directions.
  • the three zones may extend in different directions while said directions extends in the same plane.
  • the first conductor may also be curved e.g. a first zone of the conductor may be substantially straight while another is curved.
  • the angle between the oblong cutting part and the rest of the first conductor may be 10- 170 degrees, such as 20 degrees, such as 30 degrees, such as 40 degrees, such as 50 degrees, such as 60 degrees, such as 70 degrees, such as 80 degrees, such as 90 degrees, such as 100 degrees, such as 110 degrees, such as 120 degrees, such as 130 degrees, such as 140 degrees, such as 150 degrees, such as 160 degrees.
  • the angle is 70° for providing the preferred penetration angle for the needle in relation to cornea.
  • At least a part of the first conductor may be surrounded by the second conductor, but the first and second conductor may also be placed side by side with an electrically insulating material between the conductors.
  • the first conductor may be longer than the second conductor and the additional part on the first conductor may be bend in a direction transverse to the first and second conductor.
  • the cutting part may be attached to a probe part comprising the first conductor and the second conductor.
  • the probe part may be provided with an outer surface defined by the second conductor, but both the first and second conductor may also provide the outer surface of the probe part. Further the outer surface of the probe part may be provided with an electrically insulation material.
  • the probe part and the cutting part may be made from one element comprising the first and second conductor and an isolating material arranged therein between.
  • the first and/or the second conductor may be made from one piece of a conductive material.
  • the conductive material may be made from a metallic material selected from the group consisting of: copper, aluminium, chromium, titanium, magnesium, nickel, cobalt, zinc, cadmium, tin, led, wolfram, molybdenum, tantalum, silver, gold and platinum.
  • the conductive material may be made from an alloy selected from the group consisting of: stainless steel, bronze and brass.
  • the conductive element may be made from surgical steel.
  • the conductive material may be made from a composite material comprising at least one conductive element.
  • the probe part may extend between a connector and the cutting part, the connector being adapted to connect the needle to a power source.
  • the connector may comprise a plurality of contacting points for each conductor.
  • the connector may comprise two contact points for each conductor.
  • the connector may further comprise one or more fuses for each conductor so that a maximum current for each conductor is not exceeded.
  • the connector may also comprise one or more diodes for ensuring a desired directing of a current or electrical field.
  • the diode may be a light emitting diode, which is adapted to emit light when an arc is generated between the fist and second conductor.
  • the cutting part may be provided in a length in the range of 0.4-0,6 mm, such as in the size of 0,41 mm or 0,42 mm or 0,43 mm or 0,44 mm or 0,45 mm or 0,46 mm or 0,47 mm or 0,48 mm or 0,49 mm or 0,50 mm or 0,51 mm or 0,52 mm or 0,53 mm or 0,54 mm or 0,55 mm or 0,56 mm or 0,57 mm or 0,58 mm or 0,59 mm.
  • the cutting part may be provided with a cross-sectional area in the range of 500-500000 ⁇ m 2 such as in the range of 2500-300000 ⁇ m 2 , such as in the range of 5000-100000 ⁇ m 2 , such as in the range of 10000-50000 ⁇ m 2 , such as in the range of 15000-30000 ⁇ m 2 , such as 22686 ⁇ m 2 .
  • the cross-sectional shape of the cutting part may be a polygon such as a triangle, such as a quadrangle, such as a polygon with five edges, such as with six edges, such as with seven edges, such as with eight edges, such as with nine edges, such as with ten edges.
  • the edges of the polygon may be smooth but could also be sharp so as to provide a mechanical cutting edge.
  • the cross-sectional shape of the cutting part may be annular or circular, such as an ellipse, such as substantially round.
  • a hole in an annular body of the needle may be used to provide suction so as to remove ablated tissue from the internal eye during surgery.
  • the diameter of the substantially round cutting part may be in the range of 10-500 ⁇ m, such as 30 ⁇ m, such as 50 ⁇ m, such as 70 ⁇ m, such as 90 ⁇ m, such as 110 ⁇ m, such as 130 ⁇ m, such as 150 ⁇ m, such as 170 ⁇ m, such as 190 ⁇ m, such as 210 ⁇ m, such as 230 ⁇ m, such as 250 ⁇ m, such as 270 ⁇ m, such as 290 ⁇ m, such as 310 ⁇ m, such as 330 ⁇ m, such as 350 ⁇ m, such as 370 ⁇ m, such as 390 ⁇ m, such as 410 ⁇ m, such as 430 ⁇ m, such as 450 ⁇ m, such as 470 ⁇ m, such as 490 ⁇ m.
  • the diameter is 170 ⁇ m.
  • the end surface defining a surface in space transverse to the peripheral surface of the cutting part may have an angle to at least a part of said peripheral surface of 10 degrees, such as 20 degrees, such as 30 degrees, such as 40 degrees, such as 45 degrees, such as 50 degrees, such as 60 degrees, such as 70 degrees, such as 80 degrees.
  • the angle is 45° for providing the preferred penetration angle for the needle in relation to cornea.
  • the probe part and/or the cutting part may be provided with a total length in the range of 20-25 mm such as in the size of 22,5 mm.
  • the second conductor may define an annular body with an annular end surface
  • the annular end surface may define an angle with the peripheral surface of the first conductor of 10 degrees or 20 degrees or 30 degrees or 40 degrees or 50 degrees or 60 degrees or 70 degrees or 80 degrees or 90 degrees or 100 degrees or 110 degrees or 120 degrees or 130 degrees or 140 degrees or 150 degrees or 160 degrees or 170 degrees.
  • the annular end surface may define an angle with a line defined by a part of the first conductor of 10 degrees or 20 degrees or 30 degrees or 40 degrees or 50 degrees or 60 degrees or 70 degrees or 80 degrees or 90 degrees or 100 degrees or 110 degrees or 120 degrees or 130 degrees or 140 degrees or 150 degrees or 160 degrees or 170 degrees.
  • an end zone of a part of the second conductor extends in substantially the same direction as the cutting part of the first conductor.
  • Said end zone may be bend so as to form a curved part.
  • the curved end zone may be provided by bending an element comprising the first and second conductor and remove a part of the second conductor so as to provide the cutting part.
  • the radius of curvature of the curved part may be 0,5 mm or 0,75 mm or 1 mm or 1,25 mm or 1,5 mm or 1,75 mm or 2 mm or 2,5 mm or 3 mm or 3,5 mm or 4 mm or 4,5 mm or 5 mm.
  • the needle may further comprise an orientation mark, e.g. placed on the probe part.
  • the orientation mark may be provided by a concave or convex surface and said surface may be covered with a coloured material such as ink.
  • the orientation mark may also be provided by a light emitting diode adapted to emit light when an arc is provided between the first and second conductor.
  • the main purpose of the orientation mark is to control the position of the cutting part, so as to ensure that the micro-canal is provided at the precise location in the cornea.
  • the orientation mark may be placed in a transition zone between the end zone of the second conductor and another part of the second conductor, thus the orientation mark may be placed on a part of the probe part which in not bend in the direction of the cutting part. Furthermore the orientation mark may be placed on an opposite side of the probe part, said opposite side being opposite the direction in which the first conductor extends e.g. the direction in which the cutting part is bent.
  • the orientation mark may be circular, e.g. with a diameter the range 0,1-1 mm, such as 0,2-0,8 mm, such as 0,3-0,6 mm, such as 0,35-0,45 mm. Furthermore the orientation mark may further comprise a line extending along a part of a line defined by the circumference of the second conductor.
  • the line may extend in an angle of 10 degrees to each side but could also extend with an angle of 20 degrees or 30 degrees or 45 degrees or 50 degrees or 60 degrees or 70 degrees or 80 degrees or 90 degrees or 120 degrees or 150 degrees or along the hole line i.e. 180 degrees to each side.
  • the needle may be adapted to use at an effect in the range of 0,5 and 5 watts, such as 1-4 watts, such as 2-3,5 watts, such as 3 watts. Further the needle may be adapted to be used for a time period of 0,5 second or 1 second or 1,5 second or 2 seconds or 2,5 seconds or 3 seconds or 3,5 seconds or 4 seconds or 5 seconds or in the range of 5- 10 seconds or 10-20 seconds.
  • the effect applied through the needle may be pulsed so as to follow a sine curve or a cosine curve or a combination hereof.
  • the second conductor may be an annular body comprising the first conductor inside.
  • Said first conductor may be electrically insulated from the second conductor an may be movable in the hole of the annular body so that the first conductor may be protected by the second conductor and moved so as to extend out of the second conductor only when the bi-polar property is to be used. This may prevent damage of the tissue in which the probe is inserted, and the cutting edge of the first conductor will not be free of the second conductor.
  • the needle may be adapted to be operated at a peak to peak voltage of 100 Volts or 125 volts or 150 volts or 175 volts or 200 volts or 225 volts or 250 volts or 275 volts or 300 volts or 325 volts or 350 volts or 375 volts or 400 volts.
  • the pulse/pause ratio may be in the range of 1-10, such as 2-8, such as 3-6, such as 3,8-5,1, such as 3,8-4,8.
  • the invention relates to a method of creating a micro-canal by diathermal surgery comprising:
  • a corneal incision parallel to the limbus in a chosen surgical sector providing from the bottom of said incision a corneo-scleral tunnel incision, providing an incision in Tenon's capsule, - sliding a diathermal micro-needle into said corneal end of the tunnel incision, and providing said micro-canal in a floor of the surgical tunnel incision by use of said micro needle.
  • the corneal incision is provided by the use of an adjustable diamond knife.
  • the depth of the incision may be at least one half of the thickness of the corneal, such as 0.45 mm.
  • the corneo-scleral incision may be provided by the use of a dual bevel disc knife, the incision being provided oblique through the hmbal area with the scleral opening to the subconjunctival space.
  • the incision in Tenon's capsule may be provided just posterior and to the sides of the scleral opening with the disc knife.
  • the diathermal micro-needle comprises the needle according to the first aspect of the invention.
  • the micro needle may be slided into the tunnel incision until an orientation mark on the needle, being visible through the corneal ceiling, is just central to the con unctival limbus.
  • the corneo-scleral incision may be provided approximately 2-3 mm behind the limbus.
  • the micro-canal may be provided in the floor of the surgical canal anterior to Schwalbe's line.
  • the step of providing said micro-canal may comprise keeping the tip of the needle for 1-2 seconds in said floor for creating a totally penetrated micro-canal in the cornea stroma, and subsequently keeping the tip of the needle for further 2-3 seconds in the provided micro-canal for providing a sufficient collateral thermal coagulation of the canal wall.
  • IDK is performed in parabulbar anaesthesia as an outpatient procedure.
  • Mitomy ⁇ n-C or another anti pro terative compound
  • the injection is performed in the slit lamp after local anesthesia with cocaine drops.
  • Indication for using Mitomycin was the presence of one or more preoperative risk of failure factors in the patient.
  • Pilocarpine 2% (or another compound which makes the Ins more visible) is instilled.
  • a corneal traction suture a 3 mm long corneal incision is made 1 mm from and parallel to the limbus in the chosen surgical sector, using an adjustable diamond knife (fig. 16-2).
  • Incision depth should be more than one half of the corneal thickness (0.45 mm).
  • a corneo-scleral tunnel incision is then made with a 2.00 mm wide dual bevel Disc knife (Alcon), cutting through the sclera approximately 2 mm behind limbus (fig. 16-3). Conjunctiva is not cut, that is, the tunnel incision opens into the subtenonial space.
  • the scleral opening is thereby made posterior-convex, so that the risk for self-sealing of the ostium is reduced.
  • the risk for self-sealing of the ostium is reduced.
  • it is especially important that Tenon is cut completely through.
  • balanced salt solution (BSS) or 0.1% adrenaline is injected through the tunnel incision with the tip of the blunt hypodermic needle placed subconjunctivally. If the injected fluid does not spread freely subconjunctivally, a new incision of Tenon is necessary.
  • topical antibiotics are instilled four times a day for 1-2 weeks and Scopolamine two times a day for pupil dilation.
  • Topical steroids are prescribed individually. Sutures are removed 3-4 weeks postoperatively.
  • Figs. 1 and 2 shows a needle according to the invention
  • Figs. 3, 4 and 5 shows details of a needle according to the invention
  • Figs. 6,7 and 8 shows examples of pulses applied to the needle
  • Fig. 9 shows a schematic drawing of outflow system of the conventional filtering operative glaucoma procedure (Trabeculectomy),
  • Fig. 10 shows a schematic drawing of physiological outflow system in the eye.
  • Fig. 11 shows a schematic drawing of the outflow system according to the present invention
  • Fig. 12 shows a picture of the operation where the disc knife is seen in the subconjunctival space introduced through the surgical tunnel incision
  • Fig. 13 shows a preoperative picture of the bipolar micro-needle inserted into the corneal part of the tunnel incision to create the diathermal micro-canal
  • Fig. 14 shows a picture of the bipolar diathermal micro-needle according to the invention
  • Fig. 15 shows a schematic drawing of the outflow system of an ILK and the new IDK (an ultrasound cross-sectional view of an eye)
  • Fig. 16 shows a schematic drawing with the steps of the operation according to the invention
  • Fig. 17 shows a postoperative ultrasound picture of the outflow system in IDK with the diathermal micro-canal
  • Figs. 18-19 show a histological experimental section of the micro-canal provided by the Holmium Laser surgery (prior art: ILK) and diathermy (according to the invention: IDK), respectively.
  • the micro-needle 1 comprises a connector 2, a probe part 3 and a cutting part 4.
  • the probe 3 is bend in one end so as to form a smooth surface 5.
  • the smooth surface 5 of needle 1 may be pressed against the wall of the canal, this will prevent the cutting part 4 from damaging the side-wall of the canal.
  • the length 6 of the probe part could be 22,5 mm and the probe part 3 comprises a orientation mark 7.
  • the cutting part 4 comprises a peripheral surface 8 and terminates in an end surface 9.
  • the second conductor 10 surrounds the first conductor 11, and an electrically insulating material 12 separates the two conductors.
  • the second conductor 10 terminated in an annular end surface 13, which may have a rounded part 14.
  • the orientation mark may have a visible angle 15.
  • Fig. 6, 7 and 8 shows examples of curves of voltages applied to the needle, the examples comprising a primary axis 20 representation the time in micro seconds and a secondary axis 21 representing the voltage.
  • the curves represent the voltage of a pulse generator connected to the needle.
  • the load impedance of fig. 6 is 100 ohms, and in fig. 7 and 8 the load impedance is 300 ohms and 500 ohm respectively.
  • the frequency of the pulse applied to the needle is 500 kHz.
  • the current is 215 mA, the effect is 4 watts and the pulse/pause relationship is between 3,8 and 4,8.
  • the current is 100 mA
  • the effect is 3 watts and the pulse/pause relationship is between 3,8 and 4,8.
  • the impedance is 72 mA
  • the effect is 2 watts and the pulse/pause relationship is 3,8-5,1.
  • the load impedance could be 100 ohms or 200 ohms or 300 ohms or 400 ohms.
  • the voltage is kept constant and the current and the pulse/pause relationship varies.
  • the effect drops as the load impedance raises.
  • the frequency is substantially 500 kHz.
  • the peak to peak voltage may be 200 volts
  • the current may be 214 mA
  • the effect may be 4 watts
  • the pulse/pause relationship may be 3,8-4,8 and the frequency may be 500 kHz.
  • the peak to peak voltage may be 248 volts
  • the current may be 133 mA
  • the effect may be 3 watts
  • the pulse/pause relationship may be 3,8-4,8 and the frequency may be 500 kHz.
  • the peak to peak voltage may be 291 volts
  • the current may be 97 mA
  • the effect may be 3 watts
  • the pulse/pause relationship may be 3,8-4,8 and the frequency may be 500 kHz.
  • the peak to peak voltage may be 324 volts
  • the current may be 79 mA
  • the effect may be 3 watts
  • the pulse/pause relationship may be 3,8-5,1
  • the frequency may be 500 kHz.
  • the peak to peak voltage may be 350 volts
  • the current may be 72 mA
  • the effect may be 2 watts
  • the pulse/pause relationship may be 3,8-4,8 and the frequency may be 500 kHz.
  • Fig 9 shows a schematic drawing of an outflow system of the conventional filtering operative glaucoma procedure (Trabeculectomy).
  • the figure shows the canal 22 provided in the cornea 23.
  • a larger bleb 23a has been formed, and the ins 25 has been cut.
  • Fig. 10 shows a schematic drawing of physiological outflow system in the eye.
  • the drawing shows the cornea 23, the ins 25, the sclera 24 and the Schlemm's canal 35.
  • Fig. 11 shows a schematic drawing of the outflow system according to the present invention.
  • the micro-surgical operation provides a micro-canal 26 draining fluids into the surgically provided canal 22, thus draining liquid into the compartment 27. It is important that the micro-canal 26 is provided at a minimum distance from the root 25a of the ins 25 in order to ensure that the ins 25 does not flip up and obstruct the micro-canal.
  • the orientation mark on the micro-needle ensures this precise positioning of the micro-canal in contrast to prior art surgery where the micro-canal often was placed to close to the root of the ins resulting in an obstruction of the canal which then results in a follow up surgery.
  • the sclera 24 is shown.
  • Fig. 12 shows a picture of the operation where a disc knife is seen in the subconjunctival space introduced through the surgical tunnel incision.
  • a knife 28 preferably a bevel disc knife with a knife tip 28a (e.g. from the company Alcon), is used for cutting the surgical canal (tunnel incision) 22, cf. fig 11.
  • the micro needle 29 is inserted into the corneal part of the tunnel incision to create the diathermal micro-canal 26, cf. fig. 11.
  • Fig. 14 shows a picture of the micro-needle 29 according to the invention. In the upper right corner is shown an enlarged picture of the tip 29a of the needle 29 compared to a 1
  • Fig. 15 shows a schematic drawing of the outflow system of an ILK and the new IDK operation (aN ultrasound cross-sectional view of an eye).
  • the surgical canal 22 (highlighted) is provided in the cornea 31, and the micro-canal 26 (highlighted).
  • the figure further shows the root 32a of the iris 32.
  • Fig. 16 shows a schematic drawing of the steps in the operation as disclosed in the preceding text, cf. page 8-9 above.
  • Fig. 17 shows a postoperative ultrasound picture of the outflow system in an IDK with the diathermal micro-canal 26 provided.
  • Figs. 18-19 shows a histological experimental section of the micro-canal 26 provided by the Holmium Laser surgery (prior art, ILK) and diathermy (according to the invention, IDK), respectively.
  • the micro-canal provided by the Holmium Laser is not penetrating the cornea sufficiently, cf. the remaining tissue 33.
  • the wall 34 of the micro-canal is not coagulated sufficiently to ensure no healing/closing of the micro- canal.
  • the micro-canal provided by the diathermy surgery according to the invention is a totally penetrating micro-canal with an optimal stromal thermal coagulation of wall, so that it will not grow together and close the micro-canal.
  • the capsule of the eye may be opened using diathermic radio frequency energy applied with a small bipolar needle. Energy is footswitch-activated and automatically controlled. The method was introduced in 1991 and is standard on all Oertli phaco and vitreoretmal equipment.
  • the Kloti Bipolar Unit provides the capsulotomy function as well as haemostasis and conjunctiva welding in a small standalone unit. Ideal for surgeons who have already a phaco machine or who do EC technique.
  • Capsulotomy power may be controlled automatically in two ranges; a regular and a high.
  • the high range may be used for capsulotomies underneath the iris.
  • the diathermy power may be selectable from 0.1 to 8 Watts (50 Ohms) in 20 steps.
  • An earth free power output is preferred so as to provide a safe patient current according to
  • the pulse generating device may comprise an optical and/or an acoustic signal so as to indicate delivery of power
  • the diathermal micro-needle may be adapted to the Oertli bipolar diathermy probe and may have to following specifications: Based on experimental IDK operations on pig eyes and human bank eyes prototype I and II of the new diathermal micro-needle has been invented. After clinical IDK operations with the prototype II needle a prototype III has been made, the needle may preferably be as follows:
  • the outer micro-tip of the needle should be cylindrical, 170 micron (0,17 mm) in diameter, 0.5 mm in length and with a 450 sharpened end (like a hypodermic needle) with the face pointing forward.
  • the angle between the outer micro-tip and the circular end surface of the needle should be 90°.
  • the orientation mark should be located with the centre on the upper circumference just before the curvature of the needle end, with a distance between the centre of the mark and the basis of the needle of 21,5 mm.
  • the mark should be circular with a diameter of 0,35- 0,45 mm corresponding to a viewing angle of 70- 90°.
  • the diathermal micro-needle is preferably a non-disposable instrument, but it may be constructed as a disposable needle, e.g. at least a part of it being made of plastic.
  • micropenetrating surgery was defined as operations with a surgically created outflow opening from the anterior chamber of less than 200 micron (with the present technique, 150-200 micron).
  • the study is a retrospective, non-randomized comparative case series of consecutively included patients with complicated primary and secondary open angle glaucoma.
  • SLS Subconjunctival Holmium Laser Sclerostomy
  • 24 eyes 22 patients operated 1992-93, using postoperative 5- Fluorouracil injections.
  • Mean observation time 27,6 month (19,7-34,3).
  • Group II The clear-cornea Intrastromal Holmium Laser Keratostomy (ILK), 17 eyes (17 patients) operated 1994-95, using preoperative subconjunctival MMC injections (0,02 ml of 0,2 mg/ml). Mean observation time: 22,5 months ( 16,6-26,7).
  • ILK Intrastromal Holmium Laser Keratostomy
  • Group III The clear-cornea Intrastromal Diathermal Keratostomy (IDK) using a new bipolar diathermy micro-needle, 10 eyes (9 patients) operated after may 2001, using preoperative subconjunctival MMC injections (0,02 ml of 0,15 mg/ml). Mean observation time: 6,4 month (3,0-12,0).
  • IDK Intrastromal Diathermal Keratostomy
  • An object of the invention is to provide a non-disposable dipolar needle with micro-tip (diameter 170 micron, length 0,5 mm) and to secure a controlled creation of a cylindrical micro-canal (diameter 150-200 microns) the diathermal cutting effect of the needle should be as minimal as possible. Therefore the output from the high frequency bipolar diathermi was reduced from 6 watt to 3 watt. This caused a too poor penetration effect (no penetration of the Descemet's membrane). This problem was solved making the micro-tip with a sharpened end - like the hypodermic needle. The reduced output also reduced the too violent thermal collateral coagulation of the border of the micro-canal. A thermal collateral coagulation sufficient to avoid self-sealing of the canal is now created in a controlled way. After 2-3 seconds heating (air bobbles in the anterior chamber) following penetration, which occur after 1-2 seconds.

Abstract

A bipolar diathermal micro-needle for creating a micro-canal, said needle comprising a first (11) and a second electrical conductor (10). The first (11) and a second conductor (10) are electrically separated and at least the first conductor (11) comprises a cutting part (4). The micro-needle comprises an orientation mark (7), and the cutting part (4) comprises a peripheral surface (8) and terminates in an end surface (9). The second conductor 10 surrounds the first conductor 11, and an electrically insulating material (12) separates the two conductors. The second conductor (10) terminates in an annular end surface 13, which may have a rounded part (14). The orientation mark may have a visible angle (15).

Description

A DIATHERMAL MICRO-NEEDLE FOR GLAUCOMA SURGERY AND A METHOD OF USING THE SAME
Field of the Invention
The present invention relates to a micro-needle for glaucoma surgery and a method of using the same, and more specifically the invention relates to a bipolar diathermal micro- needle. Furthermore, the invention relates to a method of creating a micro-canal in the cornea with the necessary thermal coagulation of the wall in said micro-canal.
Description of the Prior Art
Glaucoma, mostly seen by older people, is a decease where intraocular pressure is elevated to a point where the optic nerve is damaged, progressively and irreversible. Two principle methods for treating the decease exist. The first method is to reduce the pressure in the eye using medicine and the second method is to perform a surgical operation so as to permanently creating an outflow opening from the anterior chamber. The latter method provides a substitute for the destroyed physiological outflow system (canal of Schlemm). The present invention is the third generation of micropenetrating surgery, i.e. filtering glaucoma operations where the inner outflow opening has a surgically created diameter of less than e.g. 200 micron, which means about physiological dimensions in contrast to the conventional filtering glaucoma operation (Trabeculectomy).
The First generation of micropenetrating surgical approaches was the Subconjunctival Holmium Laser Sclerostomy (SLS) developed in San Francisco 1990. This is a full- thickness, uncovered procedure (like the old Elliot trepanation), with complications such as postoperative hypotony and shallow anterior chambers. The clinical results were unacceptable (success rate 6%) due to early and late iris incarceration in the Internal sclerostomy ostium and blockage of the sclerostomy canal because of progressive subconjunctival fibrosis.
The second generation was the clear-cornea, guarded Intrastromal Holmium Laser Keratostomy (ILK) developed in Copenhagen 1994. The aim of ILK was to change the localisation of the laser micro-canal and the construction of the outflow system. With the ILK the laser canal was therefore positioned intrastromally in the cornea, in front of Schwalbe's line, in the floor of a corneo-scleral tunnel incision formed with a knife. The laser probe was introduced into the tunnel incision from the corneal side, that is, there were no opening in the conjunctiva. The clinical results were good (success rate 63%), but experimental and clinical observations showed that it was impossible to provide a total penetrating micro-canal with the Holmium laser, as in the original SLS procedure. The internal micro-canal ostium was slitformed, presumably due to the pulsed Holmium laser energy. Thus the operation had to be followed by photo disruption by YAG-laser to open the internal ostium. Fig. 15 shows the result of an ILK operation.
It is known to use bipolar diathermy surgery on the human body from e.g. WO 01/60273, US 2001 014804 and US 6,183,469. However, these surgery equipment are adapted for macro surgery, such as breast operation and removal of pacemakers, where it is important not to coagulate the created path, and where the equipment is of a large size not applicable for micropenetrating eye surgery.
It is an object of the present invention to provide a third generation micropenetrating surgical approach which overcomes the above mentioned obstacles.
Thus, it is an object to provide an approach, which provides a permanent, totally penetrating micro-canal, preferably through a floor of a corneo-scleral tunnel incision.
It is an object of the present invention to provide a method where postoperative routinely YAG laser treatment is not necessary (such as routinely YAG laser treatment).
Further, it is an object to provide equipment, which is simpler and better functioning than the advanced Holmium laser technology and therefore makes the operation less expensive.
Finally it is an object to provide a method with high portability, such that the method may be used in field surgery.
Description of the Invention
According to a first aspect the invention relates to a bipolar diathermal micro-needle for creating a micro-canal, said needle comprising a first and a second electrical conductor, wherein
- the first and second conductor are electrically separated and,
- at least the first conductor defines a cutting edge.
In an embodiment the needle comprises a first and a second electrical conductor, but could also comprise further conductors such as a plurality of three conductors or four conductors or five conductors or six conductors. Some of the conductors may be adapted to generate an arc between the conductors while other conductors may be used to determine parameters in the operation area such as temperature or PH value. The arc may be used to cut tissue and to coagulate the tissue e.g. such that a micro-hole created in the tissue is maintained. If the hole is not coagulated the sidewalls of the tissue may press against each other closing the hole again. Further the coagulation cause some shrinkage of the surrounding corneal tissue preventing self-sealing of the combined outflow system (diathermal micro-canal and surgical tunnel-incision).
The diathermal micro-needle is preferably used for creation of a micro-canal by glaucoma operations, but could also be used for neuro-surgery or surgery in the cranium or surgery in the hand or surgery in ears such as in the inner ear or surgery in the foot or surgery in the genitalia or any other kind of micro surgery or micropenetrating surgery.
The first and second conductor may be provided on each side of a tissue so as to burn a hole in the tissue when an electric field is generated between the conductors, and thus it may be prevented that the conductors are inserted into the tissue. In another embodiment the conductors may be arranged so that only one of the conductors are inserted into the tissue and so that an arc is generated between the conductor inserted into the tissue and the conductor which is not inserted into the tissue. In yet another embodiment the conductors may be arranged such that two conductors are inserted into the tissue and that an arc is generated between the conductors when both conductors are inserted into the tissue.
The first conductor may define a cylindrical cutting part with a peripheral surface and an end surface. The cutting edge may be a transition between the peripheral surface and the end surface. The end surface may be concave or convex or may have a cross sectional shape being substantially similar to at least a part of a parabola or an ellipse or a circle. The surface may extend in two dimensions and thus be a plane but could also extend in three dimensions. The cutting part may be oblong thus being substantially longer than wide. The cutting part may be two times longer than wide or three times longer or four times longer or five times longer or six times longer or seven times longer or eight times longer or nine times longer or ten times longer.
The cutting part may be an end part of the first conductor, but could also be provided on a part of the first conductor located between the ends of the conductor, e.g. the conductor may bend with an angle sufficiently sharp to provide a cutting edge.
The oblong cutting part may extend in a direction transverse to at least one other part of the first conductor. In an embodiment a major part of the first conductor may extend in a first direction while a small part extends in a second direction, said second direction being transverse to the first direction. In a further embodiment the first conductor may define three zones extending in different directions. In yet another embodiment the three zones may extend in different directions while said directions extends in the same plane. The first conductor may also be curved e.g. a first zone of the conductor may be substantially straight while another is curved.
The angle between the oblong cutting part and the rest of the first conductor may be 10- 170 degrees, such as 20 degrees, such as 30 degrees, such as 40 degrees, such as 50 degrees, such as 60 degrees, such as 70 degrees, such as 80 degrees, such as 90 degrees, such as 100 degrees, such as 110 degrees, such as 120 degrees, such as 130 degrees, such as 140 degrees, such as 150 degrees, such as 160 degrees. Preferably, the angle is 70° for providing the preferred penetration angle for the needle in relation to cornea.
At least a part of the first conductor may be surrounded by the second conductor, but the first and second conductor may also be placed side by side with an electrically insulating material between the conductors. In this embodiment the first conductor may be longer than the second conductor and the additional part on the first conductor may be bend in a direction transverse to the first and second conductor.
The cutting part may be attached to a probe part comprising the first conductor and the second conductor. The probe part may be provided with an outer surface defined by the second conductor, but both the first and second conductor may also provide the outer surface of the probe part. Further the outer surface of the probe part may be provided with an electrically insulation material.
In an embodiment the probe part and the cutting part may be made from one element comprising the first and second conductor and an isolating material arranged therein between. The first and/or the second conductor may be made from one piece of a conductive material.
The conductive material may be made from a metallic material selected from the group consisting of: copper, aluminium, chromium, titanium, magnesium, nickel, cobalt, zinc, cadmium, tin, led, wolfram, molybdenum, tantalum, silver, gold and platinum. Alternatively the conductive material may be made from an alloy selected from the group consisting of: stainless steel, bronze and brass. The conductive element may be made from surgical steel. Alternatively the conductive material may be made from a composite material comprising at least one conductive element. In an embodiment the probe part may extend between a connector and the cutting part, the connector being adapted to connect the needle to a power source. The connector may comprise a plurality of contacting points for each conductor. As an example the connector may comprise two contact points for each conductor. The connector may further comprise one or more fuses for each conductor so that a maximum current for each conductor is not exceeded. The connector may also comprise one or more diodes for ensuring a desired directing of a current or electrical field. The diode may be a light emitting diode, which is adapted to emit light when an arc is generated between the fist and second conductor.
The cutting part may be provided in a length in the range of 0.4-0,6 mm, such as in the size of 0,41 mm or 0,42 mm or 0,43 mm or 0,44 mm or 0,45 mm or 0,46 mm or 0,47 mm or 0,48 mm or 0,49 mm or 0,50 mm or 0,51 mm or 0,52 mm or 0,53 mm or 0,54 mm or 0,55 mm or 0,56 mm or 0,57 mm or 0,58 mm or 0,59 mm. The cutting part may be provided with a cross-sectional area in the range of 500-500000 μm2 such as in the range of 2500-300000 μm2, such as in the range of 5000-100000 μm2, such as in the range of 10000-50000 μm2, such as in the range of 15000-30000 μm2, such as 22686 μm2.
The cross-sectional shape of the cutting part may be a polygon such as a triangle, such as a quadrangle, such as a polygon with five edges, such as with six edges, such as with seven edges, such as with eight edges, such as with nine edges, such as with ten edges. The edges of the polygon may be smooth but could also be sharp so as to provide a mechanical cutting edge. In an embodiment the cross-sectional shape of the cutting part may be annular or circular, such as an ellipse, such as substantially round. A hole in an annular body of the needle may be used to provide suction so as to remove ablated tissue from the internal eye during surgery.
The diameter of the substantially round cutting part may be in the range of 10-500 μm, such as 30 μm, such as 50 μm, such as 70 μm, such as 90 μm, such as 110 μm, such as 130 μm, such as 150 μm, such as 170 μm, such as 190 μm, such as 210 μm, such as 230 μm, such as 250 μm, such as 270 μm, such as 290 μm, such as 310 μm, such as 330 μm, such as 350 μm, such as 370 μm, such as 390 μm, such as 410 μm, such as 430 μm, such as 450 μm, such as 470 μm, such as 490 μm. Preferably, the diameter is 170 μm.
Furthermore, the end surface defining a surface in space transverse to the peripheral surface of the cutting part, may have an angle to at least a part of said peripheral surface of 10 degrees, such as 20 degrees, such as 30 degrees, such as 40 degrees, such as 45 degrees, such as 50 degrees, such as 60 degrees, such as 70 degrees, such as 80 degrees. Preferably, the angle is 45° for providing the preferred penetration angle for the needle in relation to cornea. The probe part and/or the cutting part may be provided with a total length in the range of 20-25 mm such as in the size of 22,5 mm.
The second conductor may define an annular body with an annular end surface, the annular end surface may define an angle with the peripheral surface of the first conductor of 10 degrees or 20 degrees or 30 degrees or 40 degrees or 50 degrees or 60 degrees or 70 degrees or 80 degrees or 90 degrees or 100 degrees or 110 degrees or 120 degrees or 130 degrees or 140 degrees or 150 degrees or 160 degrees or 170 degrees. Furthermore the annular end surface may define an angle with a line defined by a part of the first conductor of 10 degrees or 20 degrees or 30 degrees or 40 degrees or 50 degrees or 60 degrees or 70 degrees or 80 degrees or 90 degrees or 100 degrees or 110 degrees or 120 degrees or 130 degrees or 140 degrees or 150 degrees or 160 degrees or 170 degrees.
In an embodiment an end zone of a part of the second conductor extends in substantially the same direction as the cutting part of the first conductor. Said end zone may be bend so as to form a curved part. The curved end zone may be provided by bending an element comprising the first and second conductor and remove a part of the second conductor so as to provide the cutting part. The radius of curvature of the curved part may be 0,5 mm or 0,75 mm or 1 mm or 1,25 mm or 1,5 mm or 1,75 mm or 2 mm or 2,5 mm or 3 mm or 3,5 mm or 4 mm or 4,5 mm or 5 mm.
In an embodiment of the invention the needle may further comprise an orientation mark, e.g. placed on the probe part. The orientation mark may be provided by a concave or convex surface and said surface may be covered with a coloured material such as ink. The orientation mark may also be provided by a light emitting diode adapted to emit light when an arc is provided between the first and second conductor. The main purpose of the orientation mark is to control the position of the cutting part, so as to ensure that the micro-canal is provided at the precise location in the cornea.
The orientation mark may be placed in a transition zone between the end zone of the second conductor and another part of the second conductor, thus the orientation mark may be placed on a part of the probe part which in not bend in the direction of the cutting part. Furthermore the orientation mark may be placed on an opposite side of the probe part, said opposite side being opposite the direction in which the first conductor extends e.g. the direction in which the cutting part is bent. The orientation mark may be circular, e.g. with a diameter the range 0,1-1 mm, such as 0,2-0,8 mm, such as 0,3-0,6 mm, such as 0,35-0,45 mm. Furthermore the orientation mark may further comprise a line extending along a part of a line defined by the circumference of the second conductor. The line may extend in an angle of 10 degrees to each side but could also extend with an angle of 20 degrees or 30 degrees or 45 degrees or 50 degrees or 60 degrees or 70 degrees or 80 degrees or 90 degrees or 120 degrees or 150 degrees or along the hole line i.e. 180 degrees to each side.
In an embodiment the needle may be adapted to use at an effect in the range of 0,5 and 5 watts, such as 1-4 watts, such as 2-3,5 watts, such as 3 watts. Further the needle may be adapted to be used for a time period of 0,5 second or 1 second or 1,5 second or 2 seconds or 2,5 seconds or 3 seconds or 3,5 seconds or 4 seconds or 5 seconds or in the range of 5- 10 seconds or 10-20 seconds. The effect applied through the needle may be pulsed so as to follow a sine curve or a cosine curve or a combination hereof.
In an embodiment the second conductor may be an annular body comprising the first conductor inside. Said first conductor may be electrically insulated from the second conductor an may be movable in the hole of the annular body so that the first conductor may be protected by the second conductor and moved so as to extend out of the second conductor only when the bi-polar property is to be used. This may prevent damage of the tissue in which the probe is inserted, and the cutting edge of the first conductor will not be free of the second conductor.
The needle may be adapted to be operated at a peak to peak voltage of 100 Volts or 125 volts or 150 volts or 175 volts or 200 volts or 225 volts or 250 volts or 275 volts or 300 volts or 325 volts or 350 volts or 375 volts or 400 volts. Furthermore the pulse/pause ratio may be in the range of 1-10, such as 2-8, such as 3-6, such as 3,8-5,1, such as 3,8-4,8.
According to a second aspect the invention relates to a method of creating a micro-canal by diathermal surgery comprising:
providing a corneal incision parallel to the limbus in a chosen surgical sector, providing from the bottom of said incision a corneo-scleral tunnel incision, providing an incision in Tenon's capsule, - sliding a diathermal micro-needle into said corneal end of the tunnel incision, and providing said micro-canal in a floor of the surgical tunnel incision by use of said micro needle.
Preferably, the corneal incision is provided by the use of an adjustable diamond knife. The depth of the incision may be at least one half of the thickness of the corneal, such as 0.45 mm.
The corneo-scleral incision may be provided by the use of a dual bevel disc knife, the incision being provided oblique through the hmbal area with the scleral opening to the subconjunctival space.
The incision in Tenon's capsule may be provided just posterior and to the sides of the scleral opening with the disc knife.
Preferably, the diathermal micro-needle comprises the needle according to the first aspect of the invention.
The micro needle may be slided into the tunnel incision until an orientation mark on the needle, being visible through the corneal ceiling, is just central to the con unctival limbus.
The corneo-scleral incision may be provided approximately 2-3 mm behind the limbus.
The micro-canal may be provided in the floor of the surgical canal anterior to Schwalbe's line.
The step of providing said micro-canal may comprise keeping the tip of the needle for 1-2 seconds in said floor for creating a totally penetrated micro-canal in the cornea stroma, and subsequently keeping the tip of the needle for further 2-3 seconds in the provided micro-canal for providing a sufficient collateral thermal coagulation of the canal wall.
A preferred embodiment of the method (in the following called the IDK Technique) will now be described:
IDK is performed in parabulbar anaesthesia as an outpatient procedure. Approximately 1 week before surgery Mitomyαn-C (or another anti pro terative compound) is injected subconjunctivally in the chosen surgical area (fig. 16-1). The injection is performed in the slit lamp after local anesthesia with cocaine drops. Indication for using Mitomycin was the presence of one or more preoperative risk of failure factors in the patient. After injection with Mitomycin, Pilocarpine 2% (or another compound which makes the Ins more visible) is instilled. After placement of a corneal traction suture, a 3 mm long corneal incision is made 1 mm from and parallel to the limbus in the chosen surgical sector, using an adjustable diamond knife (fig. 16-2). Incision depth should be more than one half of the corneal thickness (0.45 mm). From the bottom of this incision a corneo-scleral tunnel incision is then made with a 2.00 mm wide dual bevel Disc knife (Alcon), cutting through the sclera approximately 2 mm behind limbus (fig. 16-3). Conjunctiva is not cut, that is, the tunnel incision opens into the subtenonial space. By extending the Disc knife incision further subconjunctivally, Tenon's capsule is intersected, leaving the conjunctival epithelium covered with spongy stroma untouched. As the Disc knife is pulled back, the scleral incision is widened to the sides. The scleral opening is thereby made posterior-convex, so that the risk for self-sealing of the ostium is reduced. In the presence of subconjunctival fibrosis it is especially important that Tenon is cut completely through. To test for adequate intersection of Tenon, balanced salt solution (BSS) or 0.1% adrenaline is injected through the tunnel incision with the tip of the blunt hypodermic needle placed subconjunctivally. If the injected fluid does not spread freely subconjunctivally, a new incision of Tenon is necessary.
To hinder episcleral hemorrhage, compress transconjunctivally with a spongostan sponge moistened with 0.1% adrenalin immediately after removal of the Disc knife. BBS is then injected through a limbal paracentesis until normal pressure (in the range of 15-20 mm Hg)
In a lying position is the diathermal micro-needle then cautiously slided into the corneal end of the tunnel incision along the right border. When the orientation mark, visible through the corneal ceiling, seems to be just central to the conjunctival limbus, the needle is turned to a vertical position and the probe grasped as a pencil. Thereby the needle will get caught in the narrow tunnel incision because the eye is relative hard. This is very essential because it now is impossible to make a too big, slit formed micro-canal in spite of shaken hands! Guided by the orientation mark, a diathermy micro-canal (150-200 micron) is then created in the floor of the surgical canal, in front of Schwalbe's line (fig. 16-4) and perpendicularly through the corneal stroma. During the diathermy application the tunnel incision must be wet. After 1-2 seconds Diathermy application the micro-tip has penetrated totally causing micro-air bubbles in the aqueous. After 2-3 seconds with air bubbles is the collateral thermal coagulation of canal border sufficient.
When cautiously removing the diathermal micro-needle in the same way as the insertion, leakage of aqueous through the corneal incision will be observed. The operation is completed with two 10-0 knotted nylon sutures (fig. 16-5) and BBS injections through the paracentesis. It should be emphasised that there is no conjunctival opening or iridectomy.
Postoperatively, topical antibiotics are instilled four times a day for 1-2 weeks and Scopolamine two times a day for pupil dilation.
Topical steroids are prescribed individually. Sutures are removed 3-4 weeks postoperatively.
Detailed description of the invention
A preferred embodiment of the invention will now be described in details with reference to the figures in which:
Figs. 1 and 2 shows a needle according to the invention,
Figs. 3, 4 and 5 shows details of a needle according to the invention,
Figs. 6,7 and 8 shows examples of pulses applied to the needle,
Fig. 9 shows a schematic drawing of outflow system of the conventional filtering operative glaucoma procedure (Trabeculectomy), Fig. 10 shows a schematic drawing of physiological outflow system in the eye.
Fig. 11 shows a schematic drawing of the outflow system according to the present invention,
Fig. 12 shows a picture of the operation where the disc knife is seen in the subconjunctival space introduced through the surgical tunnel incision, Fig. 13 shows a preoperative picture of the bipolar micro-needle inserted into the corneal part of the tunnel incision to create the diathermal micro-canal,
Fig. 14 shows a picture of the bipolar diathermal micro-needle according to the invention,
Fig. 15 shows a schematic drawing of the outflow system of an ILK and the new IDK (an ultrasound cross-sectional view of an eye), Fig. 16 shows a schematic drawing with the steps of the operation according to the invention,
Fig. 17 shows a postoperative ultrasound picture of the outflow system in IDK with the diathermal micro-canal, and
Figs. 18-19 show a histological experimental section of the micro-canal provided by the Holmium Laser surgery (prior art: ILK) and diathermy (according to the invention: IDK), respectively.
Referring to Fig. 1, the micro-needle 1 comprises a connector 2, a probe part 3 and a cutting part 4. The probe 3 is bend in one end so as to form a smooth surface 5. Thus when the needle is inserted into a canal, provided e.g. by a surgical knife, the smooth surface 5 of needle 1 may be pressed against the wall of the canal, this will prevent the cutting part 4 from damaging the side-wall of the canal.
The length 6 of the probe part could be 22,5 mm and the probe part 3 comprises a orientation mark 7. As shown in figs. 3 and 4 the cutting part 4 comprises a peripheral surface 8 and terminates in an end surface 9. The second conductor 10 surrounds the first conductor 11, and an electrically insulating material 12 separates the two conductors. The second conductor 10 terminated in an annular end surface 13, which may have a rounded part 14. The orientation mark may have a visible angle 15.
Fig. 6, 7 and 8 shows examples of curves of voltages applied to the needle, the examples comprising a primary axis 20 representation the time in micro seconds and a secondary axis 21 representing the voltage. The curves represent the voltage of a pulse generator connected to the needle. The load impedance of fig. 6 is 100 ohms, and in fig. 7 and 8 the load impedance is 300 ohms and 500 ohm respectively. The frequency of the pulse applied to the needle is 500 kHz. In fig. 6 the current is 215 mA, the effect is 4 watts and the pulse/pause relationship is between 3,8 and 4,8. In fig. 7 the current is 100 mA, the effect is 3 watts and the pulse/pause relationship is between 3,8 and 4,8. In fig 8 the impedance is 72 mA, the effect is 2 watts and the pulse/pause relationship is 3,8-5,1. The load impedance could be 100 ohms or 200 ohms or 300 ohms or 400 ohms. Generally the voltage is kept constant and the current and the pulse/pause relationship varies. The effect drops as the load impedance raises. The frequency is substantially 500 kHz.
With a load impedance of 100 Ohms the peak to peak voltage may be 200 volts, the current may be 214 mA, the effect may be 4 watts, the pulse/pause relationship may be 3,8-4,8 and the frequency may be 500 kHz.
With a load impedance of 200 Ohms the peak to peak voltage may be 248 volts, the current may be 133 mA, the effect may be 3 watts, the pulse/pause relationship may be 3,8-4,8 and the frequency may be 500 kHz.
With a load impedance of 300 Ohms the peak to peak voltage may be 291 volts, the current may be 97 mA, the effect may be 3 watts, the pulse/pause relationship may be 3,8-4,8 and the frequency may be 500 kHz.
With a load impedance of 400 Ohms the peak to peak voltage may be 324 volts, the current may be 79 mA, the effect may be 3 watts, the pulse/pause relationship may be 3,8-5,1 and the frequency may be 500 kHz. With a load impedance of 500 Ohms the peak to peak voltage may be 350 volts, the current may be 72 mA, the effect may be 2 watts, the pulse/pause relationship may be 3,8-4,8 and the frequency may be 500 kHz.
Fig 9 shows a schematic drawing of an outflow system of the conventional filtering operative glaucoma procedure (Trabeculectomy). The figure shows the canal 22 provided in the cornea 23. As clearly indicated a larger bleb 23a has been formed, and the ins 25 has been cut.
Fig. 10 shows a schematic drawing of physiological outflow system in the eye. The drawing shows the cornea 23, the ins 25, the sclera 24 and the Schlemm's canal 35.
Fig. 11 shows a schematic drawing of the outflow system according to the present invention. The micro-surgical operation provides a micro-canal 26 draining fluids into the surgically provided canal 22, thus draining liquid into the compartment 27. It is important that the micro-canal 26 is provided at a minimum distance from the root 25a of the ins 25 in order to ensure that the ins 25 does not flip up and obstruct the micro-canal. The orientation mark on the micro-needle ensures this precise positioning of the micro-canal in contrast to prior art surgery where the micro-canal often was placed to close to the root of the ins resulting in an obstruction of the canal which then results in a follow up surgery. The sclera 24 is shown.
Fig. 12 shows a picture of the operation where a disc knife is seen in the subconjunctival space introduced through the surgical tunnel incision. A knife 28, preferably a bevel disc knife with a knife tip 28a (e.g. from the company Alcon), is used for cutting the surgical canal (tunnel incision) 22, cf. fig 11.
In fig. 13 the micro needle 29 is inserted into the corneal part of the tunnel incision to create the diathermal micro-canal 26, cf. fig. 11.
Fig. 14 shows a picture of the micro-needle 29 according to the invention. In the upper right corner is shown an enlarged picture of the tip 29a of the needle 29 compared to a 1
Fig. 15 shows a schematic drawing of the outflow system of an ILK and the new IDK operation (aN ultrasound cross-sectional view of an eye). The surgical canal 22 (highlighted) is provided in the cornea 31, and the micro-canal 26 (highlighted). The figure further shows the root 32a of the iris 32. Fig. 16 shows a schematic drawing of the steps in the operation as disclosed in the preceding text, cf. page 8-9 above.
Fig. 17 shows a postoperative ultrasound picture of the outflow system in an IDK with the diathermal micro-canal 26 provided.
Figs. 18-19 shows a histological experimental section of the micro-canal 26 provided by the Holmium Laser surgery (prior art, ILK) and diathermy (according to the invention, IDK), respectively. As can be seen, the micro-canal provided by the Holmium Laser is not penetrating the cornea sufficiently, cf. the remaining tissue 33. Furthermore, the wall 34 of the micro-canal is not coagulated sufficiently to ensure no healing/closing of the micro- canal.
The micro-canal provided by the diathermy surgery according to the invention is a totally penetrating micro-canal with an optimal stromal thermal coagulation of wall, so that it will not grow together and close the micro-canal.
In a preferred embodiment the capsule of the eye may be opened using diathermic radio frequency energy applied with a small bipolar needle. Energy is footswitch-activated and automatically controlled. The method was introduced in 1991 and is standard on all Oertli phaco and vitreoretmal equipment.
The Kloti Bipolar Unit provides the capsulotomy function as well as haemostasis and conjunctiva welding in a small standalone unit. Ideal for surgeons who have already a phaco machine or who do EC technique.
Capsulotomy power may be controlled automatically in two ranges; a regular and a high. The high range may be used for capsulotomies underneath the iris.
The diathermy power may be selectable from 0.1 to 8 Watts (50 Ohms) in 20 steps.
An earth free power output is preferred so as to provide a safe patient current according to
IEC601 BF.
The pulse generating device may comprise an optical and/or an acoustic signal so as to indicate delivery of power
The diathermal micro-needle may be adapted to the Oertli bipolar diathermy probe and may have to following specifications: Based on experimental IDK operations on pig eyes and human bank eyes prototype I and II of the new diathermal micro-needle has been invented. After clinical IDK operations with the prototype II needle a prototype III has been made, the needle may preferably be as follows:
Specifications:
1. Total length and curve of the needle appropriate for sufficient handling of the probe: 22,5 mm with a 700 bending of the end.
2. The outer micro-tip of the needle should be cylindrical, 170 micron (0,17 mm) in diameter, 0.5 mm in length and with a 450 sharpened end (like a hypodermic needle) with the face pointing forward. The angle between the outer micro-tip and the circular end surface of the needle should be 90°. 3. The orientation mark should be located with the centre on the upper circumference just before the curvature of the needle end, with a distance between the centre of the mark and the basis of the needle of 21,5 mm. The mark should be circular with a diameter of 0,35- 0,45 mm corresponding to a viewing angle of 70- 90°.
The diathermal micro-needle is preferably a non-disposable instrument, but it may be constructed as a disposable needle, e.g. at least a part of it being made of plastic.
The change of output for the "Kløti bipolar Capsulotomy" unit of Oertli will now be described:
To secure the creation of a circular micro-canal with a diameter about 150 to 200 micron (0,15 -0,2 mm) and not a slit formed canal causing hyperfistulation, the output of 6 Watt (the fixed normal output of the Kløti capsulotomy unit, when e.g. operating for cataract) is too much based on our experimental studies. Earlier experiences from the Intrastromal Holmium Laser Keratostomy, developed in 1994, had however shown, that some collateral thermal tissue coagulation of the micro-canal wall is necessary to avoid self-sealing of the outflow system. Experimentally, based on histological sections, one therefore had to titrade the output by changing the software of the unit (EPROMS) to find an appropriate output.
Specification:
After experiments using output 2,0-2,5 or 3,0 Watt it went out, that 3 Watt was appropriate both concerning easy and secure creation of a circular micro-canal and on the same time, a sufficient collateral thermal effect. This was evaluated on histological sections and clinical postoperative examinations. Clinical it is possible to titrate the necessary collateral thermal coagulation using different diathermy application time (seconds of air bubbles in the anterior eye chamber). Application time of 2-3 sec. seems appropriate. In fig. 19 is shown the resulting micro-canal, cf. above.
The following comparative study has been carried out:
Diathermy instead of Holmium-laser in Filtering Clear-cornea Micropenetrating Surgery
Purpose: The new developed, third generation of micropenetrating techniques was introduced: The Intrastromal Diathermal Keratostomy (IDK). To demonstrate the progress in these techniques during the last 10 years the rate of success and complication was compared. Micropenetrating surgery was defined as operations with a surgically created outflow opening from the anterior chamber of less than 200 micron (with the present technique, 150-200 micron).
Methods: The study is a retrospective, non-randomized comparative case series of consecutively included patients with complicated primary and secondary open angle glaucoma.
Group P The Subconjunctival Holmium Laser Sclerostomy (SLS), 24 eyes (22 patients) operated 1992-93, using postoperative 5- Fluorouracil injections. Mean observation time: 27,6 month (19,7-34,3).
Group II: The clear-cornea Intrastromal Holmium Laser Keratostomy (ILK), 17 eyes (17 patients) operated 1994-95, using preoperative subconjunctival MMC injections (0,02 ml of 0,2 mg/ml). Mean observation time: 22,5 months ( 16,6-26,7).
Group III: The clear-cornea Intrastromal Diathermal Keratostomy (IDK) using a new bipolar diathermy micro-needle, 10 eyes (9 patients) operated after may 2001, using preoperative subconjunctival MMC injections (0,02 ml of 0,15 mg/ml). Mean observation time: 6,4 month (3,0-12,0).
Results- Complete surgical success: 6%/63%/100% for SLS/ILK/IDK, respectively. Average IOP for these ILK/IDK eyes: 11 mm Hg (6-17 mmHg). Incidence of complications (SLS/ILK/IDK): Ins incarcerations: 69%/13%/0%. Occluding Descement Membrane flap of the internal ostium: 100%/100 %/0 %. Early hypotony (IOP<5mmHg): 100 %/75 %/30%. Anterior thin cystic blebs: 100%/13 %/0%.
Conclusions: The preliminary results of the third generation of micropenetrating procedures with the new, non-disposable, inexpensive instrumentation seem promising. The easy, standardised, technique without iridectomy and conjunctival flap, with few postoperative complications, qualifies this operation for a controlled, clinical, multicenter study.
An object of the invention is to provide a non-disposable dipolar needle with micro-tip (diameter 170 micron, length 0,5 mm) and to secure a controlled creation of a cylindrical micro-canal (diameter 150-200 microns) the diathermal cutting effect of the needle should be as minimal as possible. Therefore the output from the high frequency bipolar diathermi was reduced from 6 watt to 3 watt. This caused a too poor penetration effect (no penetration of the Descemet's membrane). This problem was solved making the micro-tip with a sharpened end - like the hypodermic needle. The reduced output also reduced the too violent thermal collateral coagulation of the border of the micro-canal. A thermal collateral coagulation sufficient to avoid self-sealing of the canal is now created in a controlled way. After 2-3 seconds heating (air bobbles in the anterior chamber) following penetration, which occur after 1-2 seconds.
The above description should not be considered as a limitation of the invention, but only as an exemplification, and other variations and modifications thereof are possible within the scope of the following claims.

Claims

1. A bipolar diathermal micro-needle for creating a micro-canal, said needle comprising a first and a second electrical conductor, wherein
5 the first and second conductor are electrically separated and, at least the first conductor defines a cutting edge.
2. A micro-needle according to claim 1, wherein the first conductor defines a cylindrical 10 cutting part with a peripheral surface and an end surface, and wherein the cutting edge is defined by a transition between the peripheral surface and the end surface.
3. A micro-needle according to claim 2, wherein the cutting part is oblong.
15 4. A micro-needle according to claim 3, wherein the end surface defines a surface in space transverse to the peripheral surface of the cutting part.
5. A micro-needle according to claim 4, wherein the surface in space is two-dimensional.
20 6. A micro-needle according to claim 4, wherein the surface in space is three-dimensional.
7. A micro-needle according to any of claims 2-6, wherein the cutting part is an end part of the first conductor.
25 8. A micro-needle according to any of claims 2-7, wherein the oblong cutting part extends in a direction transverse to at least one other part of the first conductor.
9. A micro-needle according to claim 8, wherein an angle between the oblong cutting part and the other part of the first conductor is 10-170 degrees, such as 20 degrees, such as 30 30 degrees, such as 40 degrees, such as 50 degrees, such as 60 degrees, such as 70 degrees, such as 80 degrees, such as 90 degrees, such as 100 degrees, such as 110 degrees, such as 120 degrees, such as 130 degrees, such as 140 degrees, such as 150 degrees, such as 160 degrees.
35 10. A micro-needle according to any of the preceding claims, wherein a first zone of the first conductor is transverse to a second zone of the first conductor.
11. A micro-needle according to any of the preceding claims, wherein the first conductor is curved.
12. A micro-needle according to any of the preceding claims, wherein at least a part of the first conductor is surrounded by the second conductor.
13. A micro-needle according to any of the preceding claims, wherein the cutting part is 5 attached to a probe part comprising the first conductor and the second conductor.
14. A micro-needle according to claim 13, wherein the probe part is provided with an outer surface defined by the second conductor.
10 15. A micro-needle according to claims 13 or 14, wherein the probe part and the cutting part is made from one element comprising the first and second conductor and an isolating material arranged therein between.
16. A micro-needle according to claim 15, wherein the first and/or the second conductor is 15 made from one piece of a conductive material.
17. A micro-needle according to claim 16, wherein the conductive material is made from a metallic material selected from the group consisting of: copper, aluminium, chromium, titanium, magnesium, nickel, cobalt, zinc, cadmium, tin, led, wolfram, molybdenum,
20 tantalum, silver, gold and platinum.
18. A micro-needle according to claim 16, wherein the conductive material is made from an alloy selected from the group consisting of: stainless steel, bronze and brass.
25 19. A micro-needle according to claim 16, wherein the conductive material is made from a composite material comprising at least one conductive element.
20. A micro-needle according to any of the preceding claims, wherein the probe part extends between a connector and the cutting part, the connector being adapted to connect
30 the needle to a power source.
21. A micro-needle according to any of claims 2-20, wherein the cutting part is provided in a length in the range of 0.4-0,6 mm. such as in the size of 0.5 mm.
35 22. A micro-needle according to any of claims 2-21, wherein the cutting part is provided with a cross-sectional area in the range of 500-500000 μm2 such as in the range of 2500- 300000 μm2, such as in the range of 5000-100000 μm2, such as in the range of 10000- 50000 μm2, such as in the range of 15000-30000 μm2, such as 22686 μm2.
23 A micro-needle according to any of claims 2-22, wherein the cross-sectional shape of the cutting part is a polygon such as a triangle, such as a quadrangle, such as a polygon with five edges, such as with six edges, such as with seven edges, such as with eight edges, such as with nine edges, such as with ten edges.
24. A micro-needle according to any of claims 2-23, wherein the cross-sectional shape of the cutting part is annular or circular, such as an ellipse, such as substantially round.
25. A micro-needle according to claim 24, wherein the diameter of the substantially round cutting part is in the range of 10-500 μm, such as 30 μm, such as 50 μm, such as 70 μm, such as 90 μm, such as 110 μm, such as 130 μm, such as 150 μm, such as 170 μm, such as 190 μm, such as 210 μm, such as 230 μm, such as 250 μm, such as 270 μm, such as 290 μm, such as 310 μm, such as 330 μm, such as 350 μm, such as 370 μm, such as 390 μm, such as 410 μm, such as 430 μm, such as 450 μm, such as 470 μm, such as 490 μm.
26. A micro-needle according to any claims 4-25, wherein the end surface defining a surface in space transverse to the peripheral surface of the cutting part, has an angle to at least a part of said peripheral surface of 10 degrees, such as 20 degrees, such as 30 degrees, such as 40 degrees, such as 45 degrees, such as 50 degrees, such as 60 degrees, such as 70 degrees, such as 80 degrees.
27. A micro-needle according to any of claims 13-26, wherein the probe part and the cutting part is provided with a total length in the range of 20-25 mm such as in the size of 22,5 mm.
28. A micro-needle according to any of claims 2-27, wherein the second conductor defines an annular body with an annular end surface, the annular end surface defining an angle with the peripheral surface of the first conductor of 10 degrees or 20 degrees or 30 degrees or 40 degrees or 50 degrees or 60 degrees or 70 degrees or 80 degrees or 90 degrees or 100 degrees or 110 degrees or 120 degrees or 130 degrees or 140 degrees or 150 degrees or 160 degrees or 170 degrees.
29. A micro-needle according to any of the preceding claims, wherein an end zone of a part of the second conductor extends in substantially the same direction as the cutting part of the first conductor.
30. A micro-needle according to claim 29, wherein the end zone of the second conductor is curved.
31. A micro-needle according to claim 30, wherein the curved end zone of the second conductor is rounded.
32. A micro-needle according to any of the preceding claims, further comprising an 5 orientation mark.
33. A micro-needle according to claim 32, wherein the orientation mark is placed on the probe part.
10 34. A micro-needle according to claims 32 or 33, wherein the orientation mark is placed in a transition zone between the end zone of the second conductor and another part of the second conductor.
35. A micro-needle according to any of claims 32-34, wherein the orientation mark is 15 placed on an opposite side of the probe part, said opposite side being opposite to the direction in which the first conductor extends.
36. A micro-needle according to any of claim 32-35, wherein the orientation mark is circular.
20
37. A micro-needle according to claim 36, wherein the diameter of the orientation mark in the range 0, 1-1 mm, such as 0,2-0,8 mm, such as 0,3-0,6 mm, such as 0,35-0,45 mm.
38. A micro-needle according to any of the preceding claims, wherein the needle is
25 adapted to use at an effect in the range of 0,5 and 5 watts, such as 1-4 watts, such as 2- 3,5 watts, such as 3 watts.
39. A micro-needle according to any of the preceding claims, wherein the needle is adapted to be used for a time period of 0,5 second or 1 second or 1,5 second or 2 seconds
30 or 2,5 seconds or 3 seconds or 3,5 seconds or 4 seconds or 5 seconds or in the range of 5- 10 seconds or 10-20 seconds.
40. A micro-needle according to any of the preceding claims, wherein the needle is adapted to create a micro-canal in the cornea.
35
41. A micro-needle according to any of the preceding claims, wherein the needle is adapted to be operated at a peak to peak voltage of 100 Volts or 125 volts or 150 volts or 175 volts or 200 volts or 225 volts or 250 volts or 275 volts or 300 volts or 325 volts or 350 volts or 375 volts or 400 volts.
42. A method of creating a micro-canal by diathermal surgery comprising:
providing a corneal incision parallel to the limbus in a chosen surgical sector, providing from the bottom of said incision a corneo-scleral tunnel incision, 5 - providing an incision in Tenon's capsule, sliding a diathermal micro needle into said corneal end of the tunnel incision, and providing said diathermal micro-canal in a floor of the surgical tunnel incision by use of said micro-needle.
10 43. A method according to claim 42, wherein the corneal incision is provided by the use of an adjustable diamond knife.
44. A method according to claim 42 or 43, wherein the depth of the corneal incision is at least one half of the thickness of the corneal, such as 0.45 mm.
15
45. A method according to any of claims 42-44, wherein the corneo-scleral incision is provided by the use of a dual bevel disc knife.
46. A method according to any of claims 42-45, wherein the diathermal micro-needle 20 comprises the micro-needle according to claims 1-41.
47. A method according to claim 46, wherein the micro-needle is slided into the tunnel incision until an orientation mark on the needle, being visible through the corneal ceiling, is just central to the conjunctival limbus.
25
48. A method according to any of claims 42-47, wherein the corneo-scleral incision is provided by cutting through the sclera approximately 2-3 mm behind the limbus.
49. A method according to any of claims 42-48, wherein the micro-canal is provided in the 30 floor of the surgical tunnel incision anterior to Schwalbe' line.
50. A method according to any of claims 42-49, wherein the tunnel incision opens into the subtenonial space.
35 51. A method according to any of claims 45-50, wherein the disc knife is extended such subconjunctivally that Tenon's capsule is intersected leaving the conjunctival epithelium covered with spongy stroma untouched.
52. A method according to any of claims 45-51, wherein the incision in Tenon's capsule is provided just posterior and to the sides for the scleral opening with the disc knife.
53. A method according to any of claims 42-52, wherein the step of providing said micro- 5 canal comprises:
keeping the tip of the needle for 1-2 seconds in said floor for creating a totally penetrated micro-canal in the cornea stroma.
10 54. A method according to claim 53, further comprising:
keeping the tip of the needle for further 2-3 seconds in the provided micro-canal for providing a sufficient collateral thermal coagulation of the canal wall.
PCT/DK2003/000359 2002-05-31 2003-05-30 Rf micro-needle for glaucoma surgery WO2003101323A1 (en)

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Cited By (1)

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