Patent Publication Number: US-2012041358-A1

Title: One-Hand Device for Ophthalmic Surgery

Description:
The invention is related to a surgical instrument, which preferably can be used in ophthalmic surgery. 
     In surgical interventions in the eye, in which tissue is taken from the eye, normally the removed material is replaced by a solution for infusion. This is done to uphold the inner pressure in the eye-chamber. 
     Hitherto a gravity-controlled infusion has been used for this, in which the intraocular pressure corresponds to the infusion pressure that is determined by the height of the bottle unless material is suction-extracted from the eye simultaneously. 
     When material is suction-extracted from the eye simultaneously, the actual intraocular pressure (IOP) results from the interplay of infusion rate and aspiration rate. Ideally the intraocular pressure will be so high that the normal intraocular pressure is slightly exceeded and the anterior chamber and the posterior chamber are posed well without a prolapsing of intraocular tissue. 
     When the aspiration opening is closed by tissue particles or when the aspiration pump is stopped, the IOP rises to the infusion pressure that is determined by the height of the bottle. When on the other hand the infusion is obstructed or shut, there is the danger of a decrease of the intraocular pressure till the bulbus collapses. By a change of the height of the bottle, even when applying motor-driven infusion stands, the pressure variations that often occur within split seconds cannot be duly compensated. 
     In the prior art there are instruments, in which a cutting device for extracting material is arranged at a handpiece, wherein an extraction opening for extracting the cut material by suction is located immediately behind the cutting tool. It is possible to have a design, in which an irrigation liquid or infusion liquid is also supplied via this handpiece. However, thereby the diameter of the tip of the instrument that is introduced into the eye increases. This, however, means that a relatively large opening has to be created through which the instrument can be introduced into the eye. In view of an infection risk, the healing time and possible damages to healthy eye tissue such as corneal astigmatism—which can be induced when suturing the wound—this is disadvantageous. Therefore, normally the irrigation fluid in anterior segment surgery is supplied via a separate infusion needle, which is introduced into the eye bimanually through a separate opening. In posterior segment surgery the infusion needle is sewed into a separate (third) opening. 
     As already mentioned above, in order to attain a micro-incision surgery, a diameter of the instruments as small as possible has to be aimed at. Therefore, the diameter of the aspiration pipe in the handpiece is not particularly large. This can lead to a plugging of the pipe with cut and sucked off tissue. In such a case, the intraocular pressure (normal pressure around 15 mmHg, approximately 20 cm water column) rises to the bottle pressure and stays at this predetermined height until the aspiration pipe is again open. With a usual bottle height of 65 cm (approximately 48 mmHg) above the eye of the patient this leads to the problem that the intraocular pressure rises to more than three times the normal pressure. Thereby, diverse damages a.o. of the optic nerve can result. Choosing a lower bottle height during the aspiration is disadvantageous, because in this case there is the danger that the eye collapses. 
     The pressure variations generate physical work that acts on the intraocular structures like the corneal endothelium, the iris, the lens and its capsule by changing the depth of the chamber. 
     However, an occlusion of the aspiration pipe cannot only be caused by removed material. Also the mode of operation of conventional cutting tools induces this as a result of their operating frequency of opening and closing. 
     As an example,  FIG. 11  shows a cutting tool of the prior art as it is described in U.S. Pat. No. 4,099,529. The instrument consists of an outer hollow tube  911  and an inner hollow tube  913  which is concentrically inserted in it. The outer hollow tube  911  has an aperture  917  laterally to its tip. The aspiration pipe is located inside of the inner hollow tube, so that tissue to be cut at first is sucked by the aperture  917 , whereupon the inner hollow tube  913  that can be linearly moved inside of the outer hollow tube  911  moves in such a way that it closes the aperture  917  with its wall. Here a cutting edge is provided at the front end  920  of the inner hollow tube  913 , which cutting edge shall cut off the sucked material when closing the aperture ( 917 ). It can be seen that in a state, in which the aperture  917  is closed, suddenly the suction of the aspiration pipe is no longer present outside of the instrument and the material to be cut is no longer drawn to the cutting instrument and drops off from it. In this state the intraocular pressure is raised, which arises from an increased depth of the chamber. The pressure immediately decreases again when the inner pipe  913  unblocks the aperture  917 , whereby the depth of the chamber becomes smaller. However, during the removal of material by the back and forth movement of the inner hollow (cutting) tube  913  pressure fluctuations are generated. Moreover, for example in vitreous surgery (vitrectomy) the vitreous, which is temporarily sucked and held and temporarily is not sucked, because no vacuum is present, is set into oscillations. These oscillations of the vitreous body may exert a pull on the retina and thereby may provoke a retinal detachment or retinal tears. 
     In view of the above-described problems of the prior art an object of the present invention is to provide an ophthalmological instrument, in which fluctuations of the intraocular pressure are avoided. At the same time, an instrument shall be provided, which has a smaller diameter of the tip and is easy to handle. 
     The object is achieved by a one-hand device according to claim  1  and a device according to claim  4 . 
     Further developments of the invention are specified in the dependent claims. 
    
    
     
       Further features and advantages of the invention arise from the following description of embodiments based on the figures, of which: 
         FIG. 1  shows a schematic view of a complete system, in which the device according to the invention is used, 
         FIG. 2  shows a view of the handpiece according to the invention, 
         FIG. 3   a  shows a side view of a tip according to the invention having a cutting body/milling body integrated at its front end, 
         FIG. 3   b  shows a side view of a tip according to the invention having two irrigation openings, wherein the side view is rotated by 90° with respect to the view of  FIG. 3   a,    
         FIG. 3   c  shows a side view of a tip according to the invention, in which the cutting body/milling body and the aspiration opening are arranged in the transition area between the front end and the cylindrical wall of the hollow tube, 
         FIG. 3   d  shows a side view of a tip according to the invention having a cutting body/milling body arranged in the cylindrical wall of the hollow tube, 
         FIG. 3   e  shows a side view of a tip having more than one aspiration opening, 
         FIGS. 4   a  to  4   c  show examples of designs of a cutting body/milling body according to the invention, 
         FIG. 5  shows a view of an instrument according to the invention that is particularly suited for a use in cataract surgery, 
         FIG. 6   a  shows an enlarged view of a cutting body/milling body having a facing with disintegration tools, 
         FIG. 6   b  shows an enlarged view of a disintegration tool, 
         FIG. 7   a  shows the vitrectomy instrument of  FIG. 3   a  with attached optics in the form of a lens, 
         FIG. 7   b  shows the vitrectomy instrument of  FIG. 3   d  with attached optics in the form of a prism, 
         FIG. 8  shows an instrument according to the invention having a front end that is formed to be an injection needle for a one-step opening of the eye, 
         FIG. 9  shows a cut at right angle to the longitudinal axis of the tip of  FIG. 8 , 
         FIG. 10  shows examples of shapes of the tip and 
         FIG. 11  shows a cutting tool of the prior art. 
     
    
    
       FIG. 1  provides an overview of a complete system, in which the instrument according to the invention can be used. The instrument  10  consists of a handpiece  3 , to which a tip  5  is attached that can be introduced into the eye. The infusion solution, in the following referred to as irrigation solution or liquid is supplied from a container or infusion bag  20  to the handpiece  3  and the sucked off or aspirated material is discharged into a container or collection bag  30 . A main control unit, at which the individual functions are specified, the current supply is effected using mains operation or low-voltage operation and to which the foot switch is connected, is provided with the reference number  50 . 
     A multi-function foot switch, which can optionally be connected in order to control the instrument, is designated with the reference number  40 . 
       FIG. 2  shows a cross-section of the handpiece  3 , which schematically reflects the inner structure. For a better illustration the tip  5  is not shown. However, the ends of an irrigation conduit  115  and of a suction conduit  125 , also referred to as aspiration conduit  125  in the following, which extend into the tip  5 , can be seen at the handpiece  3  that is formed in the form of the tube  3   a . The irrigation conduit  115  and the suction conduit  125  are run to the tip outside of the handpiece. In this way an easy cleaning of the instrument possible. Such a running of the conduits, however, is not mandatory. Conduits  115  and  125  running to the tip inside of the tube  3   a  would also be conceivable provided that a good cleaning of the instrument is possible. 
     The irrigation conduit is connected to an irrigation fluid pump  11  that is arranged in the tube  3   a . Furthermore, an irrigation fluid sensor  14  is shown in the irrigation conduit  115  between the upper end of the tube  3   a  and the irrigation fluid pump  11 , which irrigation fluid sensor may be, for example, a flow rate meter or a pressure sensor. In the same way the aspiration conduit  125  is connected to a suction pump or aspiration pump  12  that is also arranged in the tube  3   a . Also, an aspiration fluid sensor  15  is provided between the aspiration pump  12  and the upper end of the tube  3   a.    
     By the described setup the irrigation fluid pump  11  is arranged between the irrigation conduit  115  and the container/infusion bag  20  for the irrigation fluid. Also, the mentioned aspiration pump  12  is arranged between the aspiration conduit  125  and the container/collection bag  30  for the aspirated material. 
     The flow rate through the irrigation conduit  115  is adjusted to the flow rate through the aspiration conduit  125  by means of a control  13  that may, for example, be also accommodated in the handpiece  3 , however, can also be arranged outside thereof in a main control unit  50 . The goal of the control is an active regulation of the intraocular pressure and of the flow rate during the whole duration of the surgery. To this effect the outputs of the two sensors  14 ,  15  are transferred to the control  13 , which then adjusts the flow rate through the irrigation conduit. Here, the regulation of the flow rate can be effected by regulating the pumping capacity of the irrigation fluid pump  11 . However, optionally a flow rate regulator  115   a  can also be arranged in the irrigation conduit, which flow rate regulator  115   a  then is suitably controlled by the control  13 . 
     The measurement results of the sensors  14  and  15  are the basis for the regulation. If these sensors  14  and  15  for example provide values for the flow rates through the irrigation conduit  115  and the aspiration conduit  125 , then the control  13  may intervene in a regulating way until both measurement values are equal. When the sensors  14 ,  15  are pressure sensors, then the control determines the actual flow rate in the irrigation conduit  115  and the aspiration conduit  125  taking into account the ratios of cross-sections in the region of the sensors  14 ,  15  and uses them as basis for the regulation. 
     The flow rate in the aspiration conduit can be set directly by the operator. 
     According to the present invention the flow rate of the irrigation fluid is actively regulated in dependence of the flow rate in the aspiration conduit  125  and/or the intraocular pressure. Thereby the system is resistant against an occlusion or clogging of the aspiration conduit  125 . If such an occlusion did occur, the control  13  would automatically throttle the flow rate in the irrigation conduit, which may also include a stoppage of the irrigation fluid pump  11  or an inversion of its pumping direction, so that no undesired overpressure may occur inside of the eye. 
     A further advantage with respect to the prior art results from the independence of the system according to the invention on the height of the container/infusion bag with the irrigation solution relative to the patient&#39;s eye. Thereby a change of height of the operating table and positional changes of the patient are possible without any problems. 
     The tip  5 , in which one, two or a plurality of openings  5   a  for the exit of the irrigation fluid and one or a plurality of aspiration openings  5   b  for holding the sucked material and for taking up material to be sucked off are located, can be fixedly connected to the tube  3 . However, it is also possible to choose an embodiment in which the tip  5  can be removed and in which the tip  5  is for example attached to the handpiece  3  by means of a plug connection, a screw coupling, a ball catch, taper catch or a ring detent or a bayonet mount. In this way it is easier to access the inside portions of the tube  3   a  and the tip  5  for a cleaning, disinfection and sterilization. Preferably the tip  5  is designed as disposable for a one-time use. 
     The arrangement of the pumps in the handpiece  3  leads to short pipes, so that the distance to the openings  5   a  and  5   b  is not large. Thereby a quick reaction to pressure fluctuations is possible compared to a hydrostatic system, in which the height of the infusion container/bottle can be changed or aseptic air may be supplied to the infusion bottle. Due to the length of the pipes in such a hydrostatic system only a slow reaction to pressure fluctuations is possible. The short length of the pipes in the system according to the invention in addition makes easier the sterilizability, for example by autoclaving. Preferably, for this the instrument  10  or the handpiece  3  is removed from the complete system and separately cleaned. 
     The pumps  11 ,  12  are extremely precise and are not vulnerable to counter-pressure. For instance, gear micro pumps are suitable as pumps  11 ,  12 . In these pumps a direction of rotation in both ways is possible, whereby pressure fluctuations can be effectively counteracted by changing the pumping direction. 
     It is possible to use the handpiece  3  with various tips  5 . Here in the first place one can think of tips having a cutting tool/milling tool for removing material. Cutting tools that are known in the prior art are suitable. However, it is also possible to integrate a novel cutting tool/milling tool according to the invention, which, by itself alone without a combination with the above handpiece  3  according to the invention, can lead to a reduction of the pressure variations and is described in the following. 
       FIGS. 3   a  to  3   d  in this connection show as an example a tip  5 , in which a cutting tool/milling tool  54  is inserted. As is shown in  FIGS. 3   a  to  3   d , the tip  5  consists of a cylindrical tube  53  having a longitudinal axis and a cross-section that is not necessarily circular. An aspiration opening  53   b  is arranged in the front part of the tube  53  and inside of the tube  53  an aspiration conduit or channel  125  that is connected to the aspiration opening  53   b  is present, which aspiration conduit is explicitly shown only in  FIG. 3   c . Immediately behind the aspiration opening  53   b  a cylindrical cutting body/milling body  54  is pivot-mounted inside of the tube  53 . 
     In the present case the cylindrical cutting body/milling body  54  has the shape of a prism with a triangular base. The cutting body/milling body  54  has a plurality of seperating edges or severing edges  55 , which are sharp, so that they are suited for cutting. An axis of rotation  56  passes through the base plane and the top plane of the cutting body/milling body  54  such that it is close to one of its principal axes of inertia or even coincides with it. In the figures the axis of rotation  56  is perpendicular to the longitudinal axis of the tube  53 . However, also a different orientation in space is possible. Preferably the position of the axis of rotation  56  is set such that it is in parallel or nearly in parallel to the tangent to the imaginary continuation of the peripheral surface of the cylindrical tube in the aspiration opening  53   b  (also simply described as ‘tangential to the aspiration opening’). 
     The tip having a lateral aspiration opening in the tube  53 , which is shown in  FIG. 3   d , is in particular suited for performing an anterior segment surgery or a posterior segment surgery. By arranging the cutting body/milling body  54  such that the axis of rotation  56  is tangential to the aspiration opening  53   b , it is possible to arrange the cutting body/milling body  54  closer to the front end of the tip  5 . Thereby it becomes possible to approach the retina very closely during interventions at the vitreous. Accordingly, in  FIGS. 3   a  and  3   b  embodiments are shown, in which the cutting body/milling body  54  is arranged directly at the front end. In order to avoid injuries of the retina and in order to visualize the aspiration opening a compromise could also be an arrangement of the cutting body/milling body  54  in the transition area between the cylindrical tube wall and the front end, as it is shown in  FIG. 3   c.    
     The at least one irrigation opening can also be arranged either laterally in the wall of the tube  53  or else may be arranged closer to the front end of the tip  5  and directly at the front end, respectively. 
     The sizes and the positions of the cutting body/milling body  54  and the aspiration opening  53   b  are matched to each other such that at the left side and at the right side of the cutting body/milling body  54  there remains a clearance to the edge of the suction opening  53   b , which is illustrated in  FIGS. 3   a  to  3   d  by two arrows. Thereby the material to be removed is sucked into the clearances that remain between the cutting body/milling body  54  and the suction opening  53   b  and held there. Thereby the material between the edge of the opening  53   b  and the cutting edges or separating edges is cut due to the rotary movement of the cutting body/milling body  54 . 
     Compared to the cutting tools of the prior art, in which the whole aspiration conduit is completely closed in a cutting procedure, in the present invention the material can be sucked at other positions (for example a clearance between the cutting body/milling body  54  and the edge of the aspiration opening that is far from the separating edge) even during the cutting procedure, in which a separating edge  55  is exactly opposite to the edge of the aspiration opening  53   b . Thereby the suction procedure is not interrupted and pressure fluctuations are avoided. Even if the aspiration conduit is completely closed, the pressure variations will be still smaller than in the prior art, because the cutting frequency is considerably higher due to the plurality of separating edges at the periphery of the cutting body/milling body. Moreover, a separating edge and the edge of the aspiration opening lie opposite to each other only for a very short time. Contrary to the prior art, the suction takes place outside of the cutting body. For this the aspiration conduit  125  is run to the aspiration opening  53   b  outside of the cutting body/milling body  54 , so that it is connected to the outside of the tube  53  via the space or clearance between the outer side of the cutting body/milling body  54  and the edge of the aspiration opening  53   b . This clearance, however, is closed only for a very short period, during which the separating edge and the edge of the aspiration opening exactly lie opposite to each other. As both edges are very narrow, the suction action is immediately available again as soon as both edges are no longer lying exactly opposite to one another. 
     Moreover, further aspiration openings  53   b  may be systematically added in the tube  53  nearby the cutting body/milling body  54 , wherein the tissue is sucked by means of these further aspiration openings. This is exemplified in  FIG. 3   e . By the very small cross-section of these openings and due to the absence of a cutting body/milling body in these openings they are at no time closed by material that is to be removed. They are merely further suction points for fixing the material. 
     For instance in a vitrectomy the vitreous material is separated or cut off by a co-action of a separating edge  55  and an edge  7  of the suction opening  53   b  that acts as counter-edge. In the process the cutting edge and the tissue are subject of a constant pressure. Thereby a sharp dissection is enabled. The cutting edge need not necessarily be located at the cutting body/milling body  54 . Rather, it is also possible to form the cutting edge at the counter-edge  7  at the rim of the suction opening  53   b , where the separating edges  55  merely press the material against the cutting edge at the counter-edge  7 . In addition, cutting edges may be formed both at the cutting body/milling body  54  and the counter-edge. 
     The seperating edges  55  or severing edges  55  at the cutting body/milling body  54  need not necessarily coincide with a geometrical edge of the cutting body/milling body  54 . As is illustrated in  FIG. 4   a , it is also possible to form vane-shaped appendices at the geometrical edges, wherein the severing edges or cutting edges  55  are formed at the ends of the vane-shaped appendices. Preferably the severing edges  55  or cutting edges  55  should be arranged at the periphery of the cutting body/milling body  54  with equal distances to one another. 
     The term “cylinder” is used in the present application according to its general geometrical definition according to which it includes bodies that have an arbitrarily shaped plane base and top surface, which can be made to overlap completely when being shifted along parallel straight lines. As is shown in  FIG. 4   b , the cutting body/milling body  54 , of course, can also be designed as cylinder having a circular surface, wherein severing edges/cutting edges  55  may be attached at the periphery of the cylinder, which severing edges/cutting edges  55  may alternatively also be located on vane-shaped appendices. In particular a cylinder having a star-shaped base like in  FIG. 4   c  is also conceivable. Further, a triangular prism base is not a basic requirement for a proper function. Rather, prisms in which the base is bordered by an arbitrary polygonal chain, may be used. 
     Furthermore, it is also possible to design the cutting body/milling body  54  in the shape of a cone, truncated cone, a pyramid, a truncated pyramid, an ellipsoid or as arbitrary solid of revolution. The shape of a spherical segment (portion of a sphere cut off by two parallel planes) in which the severing edges are placed on the lateral surface (zone) of the spherical segment and thereby have a small curvature is also conceivable. 
     Furthermore, in all previously described geometrical shapes of the cutting body/milling body  54  it may have any convex or concave shape of the base surface and the top surface, respectively. Here, the bordering rim at the edge of the base and the top surface, respectively, can be partially or completely rounded. 
     A cutting body/milling body  54  that consists of a stack of two or more cylinders is also applicable, wherein the severing edges  55  of two adjacent cylinders of the stack are angularly displaced against one another. Finally, the cutting body/milling body  54  may have at its periphery arbitrary impressions, in particular also gaps perpendicular to its axis of rotation  56  as well as through-holes. 
     Ultimately not even the whole cutting body/milling body  54  need have severing edges  55  at its peripheral surface. It is sufficient to have the severing edges  55  merely in that part of the peripheral surface of the cutting body/milling body  54  that is exposed in the region of the aspiration opening  53   b . All above specifications concerning the shape of the cutting body/milling body  54  and the design of the severing edges in this case need only apply for that part of the cutting body/milling body  54  that has the severing edges. However, care must be taken that as a result of asymmetries the unbalances during the rotation do not get too large. 
     Moreover, the cutting body/milling body may have such a configuration that at least one portion of it is hollow or merely consists of a holder for the rotating severing edges. Then the body structure looks like an agitator. A design, in which at least one portion of the cutting body/milling body has the shape of a curved surface, is also conceivable. For this the cutting body/milling body is for example designed such that a material layer such as a sheet is bent to have the shape of the letter “S”. The axis of rotation then coincides with the symmetry axis of the body thus generated, wherein the severing edges correspond to the edges of the sheet that are not curved. It can be seen that based on this design also a vane wheel having more than two severing edges is suited as cutting body/milling body. 
     In summary, the cutting body/milling body  54  may have a multitude of shapes in particular also hybrids of the above-mentioned geometrical bodies, as long as it is ensured that the respective lateral surface having the severing edges  55  is nearly tangential to the aspiration opening  53   b  when it is exposed in the region of the corresponding aspiration opening  53   b . In particular, when the cutting body/milling body has hollows, one can think of creating a connection between these hollows and the aspiration conduit. However, also in this case it is important that a part of the aspiration is effected via the clearance between the cutting body/milling body  54  and the edge of the aspiration opening  53   b.    
     The cutting body/milling body  54  can be made from a metal such as stainless steel or titanium or from ceramics. The cutting edges preferably are coated with diamond. However, also other hard materials such as zircon, corundum, an Si ceramics or oxide ceramics or metal are suited. Furthermore, it is possible to form toothed cutting edges  55 . 
     The drive of the cutting body/milling body  54  can for example be effected by means of a motor that is accommodated in the handpiece  3 . For example, a magnet can be integrated in the cutting body/milling body  54 , which magnet is driven via an electromagnetic loop in the tip  5  like a classical electric motor. For this preferably two small electromagnets are provided in the sidewall of the tip. Here, the feed cables for the magnets can be accommodated inside of the tube  53 . 
     Maximum freedom for an operation of the cutting body/milling body  54  is achieved, when the cutting body/milling body  54  can rotate in both directions and can also operate in an oscillating manner. Preferably, it should further be possible to drive the motor such that single cuts and cuts in series may be performed and any severing edge  55  does not protrude from the aspiration opening  53   b  in a non-operative condition, so that in the inactive state the possibility of injuries of the wound edges when entering the eye is eliminated. 
       FIG. 5  shows a tip  5 , in which the cutting body/milling body  54  is arranged at the front end of the tip together with the aspiration opening  53   b . Such a tip is particularly suited for cataract surgery, in which in this way the clouded human lens is removed. For this disintegration tools  57  are fixed to the rotating severing edges  55 , as is illustrated in  FIGS. 6   a  and  6   b . By severing edges designed in this way a disintegration of the lens material is possible. It is possible to change in addition the direction of rotation periodically and to work in an oscillating way or to perform a single cut. 
     An identical arrangement of the disintegration tools  57  can be chosen for all severing edges  55 . However, concerning an areal removal that is as uniform as possible it is advantageous when the respective arrangement of the disintegration tools  57  varies from severing edge to severing edge. 
     The material of the disintegration tools  57 , which tools can also be fixed to the lateral surface of the cutting body/milling body  54  as shown in  FIG. 6   a , is not limited to diamond that is (epitaxially) grown or applied as coating. It is also possible to use other materials such as zircon, corundum, Si ceramics or oxide ceramics or metal. For the cutting body/milling body having the disintegration tools  57  the same selection of materials is possible like for the cutting body/milling body  54  that lacks these disintegration tools  57 . 
     Compared to a conventional removal of the lens by means of ultrasound due to the mechanical approach the advantage arises that the integrated aspiration also takes over the cooling that is possibly necessary. In addition, the wound-edges at the penetration opening of the instrument are treated with care, which wound-edges can heat up very much in the case of using ultrasound due to the lateral oscillations of the tip (28 or 40 kHz). A pulsation as used when applying ultrasound is not necessary for the mechanical removal. 
     All tools for removing tissue that were described above have the advantage, which was mentioned above, that the fluctuations of the intraocular pressure are reduced, which fluctuations occur in the conventional irrigation with simultaneous aspiration. By the configuration of the tool according to the invention the cutting body/milling body  54  can freely rotate without that the aspiration opening  53   b  is closed at any moment. Thereby it is ensured that at each moment a sufficient suction effect is present, so that pressure fluctuations due to the cutting movements are prevented. The faster the cutting body/milling body  54  rotates, the shorter the time the surgeon works intraocularly. 
     Further, in the tool according to the invention the removal can be dosed more precisely. For example, in a use as vitrectomy instrument the interaction with the counter-cutting edge (counter-cutting edge, cutting edge and tissue are subjected to a constant pressure, which is the physical pre-condition for a sharp dissection) resembles more a cutting process than it is the case for the prior art, where more likely the material is yanked or torn or the material is chopped off. Also, the amount of material removal can be adjusted in a simple way by adjusting the rotation speed of the cutting body/milling body  54 . When using the instrument in a lens surgery no large suction is necessary due to the finer dosed removal. Thereby the danger of a rupture of the capsule is reduced. 
     In the present invention the position of the axis of rotation of the cutting body/milling body  54  can be arbitrarily chosen depending on the desired use of the cutting tool. It is advantageous when the axis of rotation  56  does not coincide with a longitudinal axis (center axis) of the tube  53 , but is tilted with respect to the longitudinal axis, is perpendicular to it or in parallel to it. Thereby, the aspiration conduit need not be run through the inside of the cutting body/milling body  54 , but can be located outside of the same. However, thereby room is made in the tube  53  for further devices in the tip  5  besides the cutting tool: 
     For instance, glass fibres may be inserted in the walls of the tube  53 , which fibres end at the front end of the tip  5  in order to illuminate the surgical zone. Furthermore, an LED may be fitted in the tube  53  or the handpiece  3 . 
       FIGS. 7   a  and  7   b  show a tip, in which an optics  8  is fitted close to the cutting tool. The optics  8 , e.g. an image fibre bundle, serves for visually supervising the surgical field. 
     At the distal end of the optics  8  for example an optical prism  8   b  may be positioned, as it is shown in  FIG. 7   b , a lens  8   a , as it is shown in  FIG. 7   a , or only the polished end of the fibre bundle. Here, the optical prism can have any angle for an optimal access to the field of view. Also, the optical prism itself may comprise the counter-cutting edge  7 . 
     Furthermore, it is possible to run an optical waveguide for a laser up to the front end of the tip. Such a tip then can be used for an endocoagulation during the vitrectomy. 
     A further field of application opens up when the end of the tip  5  has the shape of an injection needle, as it is shown in  FIG. 8 . For this the front end of the tip  5  is tapered like a needle. In particular, in  FIG. 8  the front end of the tip is bevelled. In this way the slender instrument (diameter 20 or 23 GA) can be used for a biopsy with the particular advantage that all functions are provided through one single opening in the eye: a cutting function by the cutting body/milling body  54 , a suction function, the irrigation through at least one irrigation opening  5   a , optionally an illumination and a monitoring by means of an optics  8  and moreover the use of a laser. The instrument can even be used for applying drugs in the eye in a controlled way. These drugs then are released via the irrigation opening(s)  5   a . In particular when the axis of rotation  56  is chosen to be perpendicular to the longitudinal axis of the tube  53  and when the cutting body/milling body is arranged in the bevelled portion, as it is shown in  FIG. 8 , this is particularly advantageous. 
     The sectional view of  FIG. 9  at right angle to the longitudinal axis of the tip illustrates the accommodation of the diverse functions in the tip  5 . There the reference sign W designates a channel for a power supply for the motor for rotating the cutting body/milling body  54 , X designates the laser fibre and Z designates the feed line for an illumination of the surgery field (e.g. one or more glass fibres). 
     Furthermore, the instrument can be operated with one hand using a three-point support, whereby the transmission of force to the tissue can be fine tuned, because the finger tips do not fulfil a holding task and the sense of touch is maintained (Weber-Fechner Law). In the prior art it is necessary to work bimanually with more than one opening in the eye. 
     Though in most of the illustrations the tip is shown as straight hollow cylinder, the effects of the present invention are also achieved with curved tips. Examples for possible shapes of the tip  5  are shown in  FIG. 10 .  FIG. 10   a  shows a rigid, straight tip,  FIG. 10   b  shows a tip that is angled by 45°,  FIG. 10   c  shows a tip that is angled by 30°,  FIG. 10   e  shows a bent tip and  FIGS. 10   f  and  10   g  show tips, in which a section is bent. Bent tips in particular make it possible in an intervention to further advance into the periphery of the eye, wherein the danger of touching the lens is reduced. Here in particular an arrangement of the cutting body/milling body  54  close to the front end of the tip as shown in  FIGS. 3   a  to  3   c  is advantageous. 
       FIG. 10   d  illustrates a flexible tip. A one-hand device having such a tip can for example be used in the lacrimal apparatus, in particular in a lacrimal duct, by introducing it “round the corner and the edge, respectively” into the lacrimal sack through the puncta lacrimalis in the lower eyelid. By means of the cutting mechanism of the vitrectomy tip stenoses in the tear drainage ways can be removed. In the endonasal use in particular the fibrous occlusion of the opening of the bone after a dacryocytorhinotomy can be removed. In particular in this application there is the advantage that due to the limited dimensions of the cutting body there is enough space in the tip for integrating an optics, so that the instrument can be applied as endoscope. 
     Though in the embodiments shown in the figures only one aspiration opening  53   b  and one cutting body/milling body  54  are shown, also several aspiration openings  53   b  can be provided at the tip  5 , to each of which a cutting body/milling body  54  is assigned. In some cases the tissue can be removed more uniformly due to a plurality of cutting bodies/milling bodies. When the cutting bodies/milling bodies  54  rotate in opposite directions of rotation, a neutralization of the angular momentum is possible, so that it is easier to control the instrument. 
     In a modification that goes even further a plurality of cutting bodies/milling bodies  54  is provided in one aspiration opening  53   b . For instance for two cutting bodies/milling bodies having adjoining axes of rotation it becomes thereby possible to suck the tissue to be cut between the two cutting bodies/milling bodies and not at the edge of the aspiration opening. In this way the cutting action takes place between two separating edges or severing edges  55  that are not located on the same cutting body/milling body. Accordingly, during the cutting process these two separating edges move towards each other due to their rotations. Possibly also an interpenetration of these two separating edges  55  during the cutting action is possible. The just mentioned arrangement can, of course, be also applied to more than two cutting bodies/milling bodies  54 . 
     An arrangement of the cutting body/milling body  54  having the same axis of rotation  56  in one and the same aspiration opening enables again a neutralization of the angular momentum. 
     Though up to now only applications in ophthalmic surgery have been described, the described instruments are in the same way applicable also in other fields of surgery. Of course, depending on the specific use possibly a change of the dimensions is necessary. 
     Finally, it should be noted that the described one-hand device, of course, is not limited in use to human medicine. Also a use in veterinary medicine is possible. For this the tip that is used must have larger geometrical dimensions in particular for the vitrectomy of large animals such as in the removal of leptospira of horses. Instead of a length of the tip ( 5 ) or approximately 35 mm such as in human medicine the tip length for horses must be approximately 65 mm. The diameter of the tip ( 5 ) is also larger. It can be up to 2.0 to 2.2 mm.