Ophthalmic surgical system and procedure for operating the ophthalmic surgical system

Abstract

Ophthalmic surgical system (1), comprising: - a first fluid pump (2) comprising a first pump chamber (3) having a first volume and a first drive chamber (5) having a second volume separated from it by a first elastic separating element (4), - a second fluid pump (52) which has a second pump chamber (53) having a third volume and a second drive chamber (55) with a fourth volume separated from it by a second elastic separating element (54), - an irrigation fluid line (22) for conveying irrigation fluid (21) to an inlet (24) of the first pump chamber (3), through the pump chamber (3) to an outlet (25) of the first pump chamber (3) and from there to a first connection (27) which is designed to be coupled with a surgical instrument (29), - an aspiration fluid line (41) for conveying aspiration fluid from a second port (40), which is designed to be coupled to the surgical instrument (29), to an inlet (44) of the second pump chamber (53), through the second pump chamber (53) to an outlet (45) of the second pump chamber (53), - a first drive fluid line (7) for guiding a first drive fluid (8) to the first drive chamber (5), whereby the second volume can be increased and the first volume reduced simultaneously by means of a deformation of the first elastic separating element (4), - a second drive fluid line (57) for conveying a second drive fluid (58) to the second drive chamber (59), whereby the fourth volume can be reduced and the third volume increased simultaneously by means of a deformation of the second elastic separating element (54), - a first displacement sensor (6) for detecting a first deflection position (x1) of the first elastic separating element (4), - a second displacement sensor (56) for detecting a second deflection position (x2) of the second elastic separating element (54), - a first pressure sensor (11) for detecting a first pressure (p1) in the first drive fluid line (7), - a second pressure sensor (28) for detecting a second pressure (p2) at the outlet of the first pump chamber (3), and / or a third pressure sensor (43) for detecting a third pressure (p3) at the inlet of the second pump chamber (53), - a fourth pressure sensor (61) for detecting a fourth pressure (p4) in the second drive fluid line (57), - a connecting line (48) which is designed to directly connect the irrigation fluid line (22) to the aspiration fluid line (41), - a processing unit (70) which is set up to process the first pressure (p1), the second pressure (p2) and / or the third pressure (p3), the fourth pressure (p4) each depending on the first deflection position (x1) and the second deflection position (x2).

Description

[0001] The invention relates to an ophthalmic surgical system and a method for operating the ophthalmic surgical system.

[0002] There are several surgical techniques for treating clouding of the lens of the eye, known medically as cataracts. The most common technique is phacoemulsification, in which a thin hollow needle is inserted into the lens and stimulated to produce ultrasonic vibrations. The vibrating hollow needle emulsifies the lens in its immediate vicinity so that the resulting lens particles can be suctioned away through a line using a pump. A rinsing fluid is then introduced, and the lens particles and fluid are suctioned away through an aspiration fluid line. Once the lens has been completely emulsified and removed, a new artificial lens can be inserted into the empty capsular bag, allowing the patient treated in this way to regain good vision.

[0003] In order to enable the comminution of the eye lens with the irrigation fluid in the desired amount and at the desired pressure, as well as the suction of aspiration fluid in the desired amount and at the desired pressure, fluid pumps can be used, as in an ophthalmic surgical system according to DE 10 2016 201 297 B3. Several fluid pumps are used in this case. Since there are several fluid pumps that interact with one another and one fluid pump can never be manufactured completely identically to another, it is possible that the fluid pumps do not pump the fluid to be pumped with the desired accuracy. Even small deviations in the accuracy of the components used in the fluid pumps can lead to undesirable deviations in the fluid to be pumped, which can make surgical treatment difficult.

[0004] DE 10 2021 111 178 A1 relates to a method for operating a fluid pump and an ophthalmic surgical system with a fluid pump.

[0005] It is an object of the invention to provide an ophthalmic surgical system with which the supplied irrigation fluid and the discharged aspiration fluid can be controlled with minimal effort and high precision. Furthermore, it is an object to provide a method for controlling such an ophthalmic surgical system that can be implemented with minimal effort.

[0006] This problem is solved by the subject matter of the independent patent claim. Advantageous developments of the invention are the subject matter of the dependent claims. The ophthalmic surgical system features: - a first fluid pump having a first pumping chamber having a first volume and a first drive chamber having a second volume separated therefrom by a first elastic separating element, - a second fluid pump having a second pumping chamber having a third volume and a second drive chamber having a fourth volume separated therefrom by a second elastic separating element, - an irrigation fluid line for conducting irrigation fluid to an inlet of the first pumping chamber, through the pumping chamber to an outlet of the first pumping chamber and from there to a first connection which is adapted to be coupled to a surgical instrument, - an aspiration fluid line for conducting aspiration fluid from a second port, which is adapted to be coupled to the surgical instrument, to an inlet of the second pumping chamber, through the second pumping chamber to an outlet of the second pumping chamber, - a first drive fluid line for conducting a first drive fluid to the first drive chamber, whereby the second volume can be increased and the first volume can be reduced at the same time by means of a deformation of the first elastic separating element, - a second drive fluid line for conducting a second drive fluid to the second drive chamber, whereby the fourth volume can be reduced and the third volume can be increased simultaneously by deforming the second elastic separating element, - a first displacement sensor for detecting a first deflection position of the first elastic separating element, - a second displacement sensor for detecting a second deflection position of the second elastic separating element, - a first pressure sensor for detecting a first pressure in the first drive fluid line, - a second pressure sensor for detecting a second pressure at the outlet of the first pumping chamber, and / or a third pressure sensor for detecting a third pressure at the inlet of the second pumping chamber, - a fourth pressure sensor for detecting a fourth pressure in the second drive fluid line, - a connecting line which is designed to directly connect the irrigation fluid line to the aspiration fluid line, - a processing unit which is configured to process the first pressure, the second pressure and / or the third pressure, the fourth pressure in each case as a function of the first deflection position and the second deflection position.

[0007] The recording and processing of three or four pressure values ​​and the use of a connecting line that directly connects the irrigation fluid line and the aspiration fluid line enables a precise assessment of the actual pressure values ​​with little effort for a first fluid pump located in the irrigation fluid line and a second fluid pump located in the aspiration fluid line. This eliminates the need for the first fluid pump and the second fluid pump to have nearly identical properties, meaning that the manufacturing requirements for the fluid pumps and their associated components can be lower than before. The connecting line makes it possible to obtain precise information about the fluidic situation in the ophthalmic surgical system without the influence of a surgical instrument or the patient's eye.

[0008] Preferably, the system comprises a control unit that detects signals from the processing unit and is coupled to a first actuator in the first drive fluid line for controlling the first drive fluid and to a second actuator in the second drive fluid line for controlling the second drive fluid. The first actuator enables a precise supply of the first drive fluid into the first drive chamber. This allows the supply of irrigation fluid from the first pump chamber to be precisely controlled. This also applies analogously to the second actuator, the second drive fluid line, the second drive chamber, and the second pump chamber.

[0009] According to one embodiment, the processing unit is configured to process a difference between the first pressure and the second pressure as a function of the first deflection position. Knowing such a pressure difference depending on the deflection position makes it possible to precisely adjust the desired pressure in the irrigation fluid line.

[0010] Preferably, the processing unit is configured to process a difference between the fourth pressure and the third pressure as a function of the second deflection position. Knowing such a pressure difference depending on the deflection position makes it possible to precisely adjust the desired pressure in the aspiration fluid line.

[0011] Furthermore, it is preferred that the processing unit is configured to process a difference between the second pressure and the third pressure as a function of a hydraulic resistance of at least part of the irrigation fluid line, the connecting line, and at least part of the aspiration fluid line. Dividing this pressure difference by the hydraulic resistance in said lines yields a flow rate through the irrigation fluid line, connecting line, and aspiration fluid line. Knowing the flow rate in the irrigation fluid line and, at the same time, in the aspiration fluid line is advantageous, for example, to determine the required amount of fluid and to allow it to flow during surgical treatment in the event of a leak in the eye.

[0012] According to a further embodiment, the processing unit is configured to process the flow rate and a time derivative of the first deflection position. The time derivative of the first deflection position corresponds to a speed in the movement of the first elastic separating element. Processing the flow rate and the associated speed of the first elastic separating element enables precise control of the amount of irrigation fluid to be delivered by the first fluid pump and the pressure to be applied during a surgical procedure in which a sudden, rapid change in the flow rate or pressure in the irrigation fluid line occurs.

[0013] The processing unit can also be configured to process the flow rate and a time derivative of the second deflection position. Processing the flow rate and the associated speed of the second elastic separating element allows for precise control of the amount of aspiration fluid to be discharged by the second fluid pump and the pressure to be applied during a surgical procedure in which a sudden, rapid change in flow or pressure in the aspiration fluid line occurs.

[0014] According to the invention, a method for controlling the ophthalmic surgical system described above comprises the following steps: - Closing an outlet valve of the first pumping chamber and an inlet valve of the second pumping chamber, - Filling the first pump chamber with irrigation fluid - Emptying the first drive chamber of the first drive fluid - Emptying the second pump chamber of aspiration fluid - Filling the second drive chamber with the second drive fluid - Closing an inlet valve of the first pumping chamber and an outlet valve of the second pumping chamber, - Supplying the first drive fluid into the first drive chamber, - Connect the irrigation fluid line to the aspiration fluid line using the connecting line - Opening the outlet valve of the first pumping chamber and the inlet valve of the second pumping chamber - discharging the second drive fluid from the second drive chamber, - Emptying the first pump chamber of irrigation fluid and filling the second pump chamber with this irrigation fluid, - Recording measured values ​​of the first deflection position of the first displacement sensor, the second deflection position of the second displacement sensor, the first pressure, the second pressure and / or the third pressure, the fourth pressure, - Feeding the measured values ​​to the processing unit.

[0015] Preferably, the values ​​determined by the processing unit are passed to a control unit which is coupled to a first actuator in the first drive fluid line for controlling the first drive fluid and to a second actuator in the second drive fluid line for controlling the second drive fluid.

[0016] Further advantages and features of the invention are explained with reference to the following drawings, in which: Fig. 1 a schematic representation of an embodiment of the ophthalmic surgical system with connectable components; Fig. 2 a first schematic diagram showing a signal curve of a first differential pressure as a function of measured values ​​of a first displacement sensor; Fig. 3 a second schematic diagram showing a signal curve of a second differential pressure as a function of measured values ​​of a second displacement sensor; Fig. 4 a third schematic diagram showing a signal curve of a third differential pressure as a function of measured values ​​of the first displacement sensor; and Fig. 5 a fourth schematic diagram showing a signal curve of the third differential pressure as a function of measured values ​​of the second displacement sensor.

[0017] Fig. Figure 1 shows a schematic representation of an embodiment of an ophthalmic surgical system 1. The system 1 comprises a first fluid pump 2, which has a first pump chamber 3 with a first volume and a first drive chamber 5 with a second volume. The first pump chamber 3 and the first drive chamber 5 are separated from each other by a first elastic separating element 4 such that no exchange of fluid from the first pump chamber 3 to the first drive chamber 5 or vice versa is possible.

[0018] The first elastic separating element 4 is fixedly mounted at its edge region in the first fluid pump 2. When the volume of the first pump chamber 3 is equal to the volume of the first drive chamber 5, the first elastic separating element 4 is in a horizontal position. When the first volume is greater than the second volume, the first elastic separating element 4 is in an expanded position, in which it can, for example, be substantially convexly shaped, see. Fig. 1. The first elastic separating element 4 can have any geometry and can also assume other positions if there is a volume difference between the first pump chamber 3 and the first drive chamber 5. The illustration in Fig. 1 is only schematic and not drawn to scale.

[0019] The first elastic separating element 4 can have a first element in the center region, which is suitable for contactless detection by a first displacement sensor 6. The first displacement sensor 6 can be an inductive or capacitive displacement sensor. The first displacement sensor 6 can be arranged on the edge of the fluid pump 2.

[0020] The first drive chamber 5 is connected to a first drive fluid line 7. A first drive fluid 8 can be supplied from a first drive fluid container 9 into the first drive chamber 5 depending on a first actuator 10. This process is reversible, so that drive fluid can be returned from the first drive chamber 5 along the drive fluid line 7 into the first drive fluid container 9. The fluid pressure present in the drive fluid line 7 can be detected as the first pressure p1 by means of a first pressure sensor 11, which is preferably coupled to a connection on the drive fluid line 7.

[0021] The first pump chamber 3 can be supplied with irrigation fluid 21 at its inlet 24. The irrigation fluid 21 is contained in an irrigation fluid container 20, which can be coupled to the system 1 by means of an irrigation fluid line 22 via a third connection 19. The irrigation fluid line 22 is then connected to the inlet 24 of the first fluid pump 2.

[0022] A supply or blockage of the irrigation fluid 21 to the first fluid pump 2 can be achieved by means of a first inlet valve 23, wherein the first inlet valve 23 belongs to the first pumping chamber 3, but does not have to be directly connected to the first pumping chamber 3. Filling the first pumping chamber 3 with irrigation fluid 21 requires that a first outlet valve 26 arranged downstream of a first outlet 25 is closed, wherein the first outlet valve 26 belongs to the first pumping chamber 3, but does not have to be connected to the first pumping chamber 3.

[0023] When the first inlet valve 23 is closed and the first outlet valve 26 is open, the first drive fluid 8 flowing into the first drive chamber 5 can force the irrigation fluid 21 out of the first pump chamber 3 and flow out to the first outlet 25 in the irrigation fluid line 22 to a first connection 27. Immediately downstream of the first outlet 25 of the first fluid pump 2, the ophthalmic surgical system 1 has a connection on the irrigation fluid line 22 for a second pressure sensor 28, wherein the second pressure sensor 28 can detect a second pressure p2 present in the irrigation fluid line 22. The first connection 27 is configured to be coupled to a line of a surgical instrument 29, so that in the coupled state, the irrigation fluid can flow to the surgical instrument 29 and be used for a surgical treatment.

[0024] The surgical instrument 29 may include a needle 30 from which irrigation fluid can flow. The irrigation fluid 21 may be used during phacoemulsification of a lens 32 of an eye 31.

[0025] If lens particles are to be removed from the eye during phacoemulsification, they can be aspirated through the needle 30 along an aspiration fluid line 41. For this purpose, the aspiration fluid line 41 is coupled to the ophthalmic surgical system 1 via a second connection 40, so that the aspiration fluid, after passing through an open second inlet valve 42 arranged in the aspiration fluid line 41, can reach a second inlet 44 of a second pump chamber 53 of a second fluid pump 52. The second inlet valve 42 is an inlet valve that belongs to the second pump chamber 53 but does not need to be directly connected to the second pump chamber 53. A third pressure p3 in the aspiration fluid line 41 immediately upstream of the second inlet 44 of the second pumping chamber 53 can be detected by means of a third pressure sensor 43, which is coupled to a connection on the aspiration fluid line 41 immediately upstream of the second inlet 44.

[0026] The second fluid pump 52 is constructed analogously to the first fluid pump 2. The second fluid pump 52 has a second pump chamber 53 and a second drive chamber 55 arranged adjacent thereto, which are separated from one another by a second elastic separating element 54. The second elastic separating element 54 is firmly connected to the second fluid chamber 52 at its edge region. The position of the second elastic separating element 54 can be detected by means of a second displacement sensor 56, which is arranged, for example, at the edge of the second pump chamber 52 or is brought into contact with it. The second pump chamber 53 has a third volume, and the second drive chamber 55 has a fourth volume.

[0027] The second drive chamber 55 can be filled or emptied with a second drive fluid 58 from a second drive fluid reservoir 59 along a second drive fluid line 57. The drive fluid flow is controlled by a second actuator 60. A fourth pressure p4 can be detected by a fourth pressure sensor 61, which is coupled to the drive fluid line 57 by means of a connection.

[0028] When drive fluid is conveyed from the second drive chamber 55 toward the drive fluid reservoir 59, aspiration fluid can flow into the second pump chamber 53 due to pressure equalization. If a second outlet valve 46 arranged downstream of a second outlet 45 of the second fluid pump 52 and in the aspiration fluid line 41 is closed, the third volume of the second pump chamber 53 increases as aspiration fluid flows in, while the fourth volume of the second drive chamber decreases simultaneously. The second outlet valve belongs to the second pump chamber 53, but does not have to be directly connected to the second pump chamber 53. The second elastic separating element 54 deforms in the process.When the second inlet valve 42 is closed and the second outlet valve 46 is open, by filling the second drive chamber 55 with drive fluid 58, the aspiration fluid located in the second pump chamber 53 can flow into the aspiration fluid line 41 and then into a drive fluid collection container 47.

[0029] The ophthalmic surgical system 1 further comprises a connecting line 48, which is configured to directly connect the irrigation fluid line 22 to the aspiration fluid line 41. A first end 481 of the connecting line 48 can be connected to the first connection 27, and a second end 482 of the connecting line 48 can be connected to the second connection 40, in which case the system 1 is configured such that no fluid can flow to a surgical instrument 29. Alternatively, the first end 481 of the connecting line 48 can be arranged between the connection on the irrigation fluid line 22 for the first pressure sensor 28 and the first connection 27, and the second end 482 of the connecting line 48 can be arranged between the second connection 40 and the connection on the aspiration fluid line 41 for the third pressure sensor 43, in which case the system is also configured such that no fluid can flow to the surgical instrument 29.This embodiment is in . Fig. 1. It is also possible for the first end 481 of the connecting line 48 to be coupled to the irrigation fluid line 22 upstream of the first inlet 24, as seen in the flow direction 90, and for the other end 482 of the connecting line 48 to be arranged downstream of the second outlet 45, as seen in the flow direction 91. In this case, it must be ensured that no fluid flows downstream of the first outlet 25 in the flow direction 90 and no fluid flows toward the second inlet 44 in the flow direction 91. This can be achieved by closing the first outlet valve 26 and the second inlet valve 42.

[0030] The connecting line 48 is thus configured to connect the irrigation fluid line 22 to the aspiration fluid line 41, wherein the system 1 is configured to simultaneously prevent a fluidic connection to the surgical instrument 29.

[0031] The connecting line 48 acts as a direct connecting line or "short-circuit line." The system 1 is thus configured such that there is no other direct connecting line between the irrigation fluid line 22 and the aspiration fluid line 41 in which fluid could flow along a "detour" or a line running parallel thereto.

[0032] During an ophthalmic surgical procedure, irrigation fluid can flow into a connected surgical instrument 29 and out of the instrument 29 again as aspiration fluid. In this case, the system 1 is configured so that no fluid can flow through the connecting line 48. The system 1 is configured so that a flow of fluid through the connecting line 48 is only possible before or after a surgical procedure, but not during a surgical procedure.

[0033] An irrigation fluid line 22 is understood to be a fluid line through which fluid can flow from the irrigation fluid container 20 to the third connection 19, from there to the first inlet 24 of the first fluid pump 2, then through the first pump chamber 3, from the first outlet 25 through the first outlet valve 26 to the first connection 27. If a surgical instrument 29 is connected, the irrigation fluid line 22 also includes the line up to the surgical instrument 29 up to an outlet of the surgical instrument 29.

[0034] An aspiration fluid line is understood to mean a fluid line through which fluid can flow from a surgical instrument 29 possibly connected to the second connection 40 to the second connection 40, from there to the second inlet valve 42 and to the second inlet of the second pumping chamber 53, through the second pumping chamber 53 to the second outlet 45 to the second outlet valve 46 and from there to the aspiration fluid collection container 47.

[0035] The surgical system 1 additionally has a processing unit 70. The processing unit 70 is configured to receive and process signals from the first pressure sensor 11 via a first signal line 71 and from the second pressure sensor 28 via a second signal line 72. In addition, the processing unit 70 is configured to receive and process signals from the third pressure sensor 43 via a third signal line 73 and signals from the fourth pressure sensor 61 via a fourth signal line 74. Furthermore, the processing unit 70 is configured to receive and process signals from the first displacement sensor 6 via a fifth signal line 75 and signals from the second displacement sensor 56 via a sixth signal line 76.The processing unit 70 is connected to a control unit 80 of the ophthalmic surgical system 1, so that a result of the processing of the signals of the pressure sensors and displacement sensors can be used to control the first actuator 10 via a seventh signal line 81 and the second actuator 61 via an eighth signal line 82.

[0036] Fig. 1 shows the ophthalmic surgical system 1, in which the irrigation fluid container 20 containing irrigation fluid 21 and a portion of the irrigation fluid line 22 are not coupled to the third port 19. Furthermore, the aspiration fluid collection container 47 containing a portion of the aspiration fluid line 41 is not coupled to the fourth port 49. The surgical handpiece 29 is not coupled to the first port 27 and the second port 40. However, the connecting line 48 is coupled at its first end 481 to the irrigation fluid line 22, and the second end 482 of the connecting line 48 is coupled to the aspiration fluid line 49.

[0037] If a surgical treatment such as phacoemulsification is to be performed, the irrigation fluid container 20 containing irrigation fluid 21 and the portion of the irrigation fluid line 22 are coupled to the third port 19. Likewise, the aspiration fluid collection container 47 is coupled to the portion of the aspiration fluid line 41 containing the fourth port 49. Furthermore, the surgical handpiece 29 is coupled to the first port 27 and the second port 40. However, the connecting line 48 is then not coupled at its first end 481 to the irrigation fluid line 22 and / or at its second end 482 to the aspiration fluid line 41.

[0038] The processing of the signals from the pressure sensors and displacement sensors is subsequently carried out using the Fig. 2 to 5. The graphs shown in these figures were determined in the state in which the connecting line 48 connects the irrigation fluid line 22 and the aspiration fluid line 41, and no fluid can flow to a surgical instrument 29. The graphs represent calibration curves, which can preferably be recorded before a surgical treatment.

[0039] When the connecting line 48 directly connects the irrigation fluid line 22 to the aspiration fluid line 41 and no surgical handpiece is used, no particles of an emulsified crystalline lens 32 and other fluid originating from a patient's eye 31 flow in the aspiration fluid line. Instead, the irrigation fluid 21 from the irrigation fluid line 22 flows in the aspiration fluid line 41.

[0040] Fig. 2 shows a first diagram 100 with a first graph 101 under the following conditions: - The first inlet valve 23 is closed; - the first pump chamber 3 is filled with irrigation fluid 21; - the first drive chamber 5 is not filled with any drive fluid 8; - the first output valve 26 is open; - the connecting line 48 connects the irrigation fluid line 22 with the aspiration fluid line 41; - no fluid can flow to a surgical instrument; - the second inlet valve 42 is open; - the second pumping chamber 53 contains no fluid; - the second drive chamber 55 is completely filled with drive fluid 58; - the second output valve 46 is closed; - the first drive fluid 8 can flow from the first drive fluid container 9 into the first drive fluid line 7; - drive fluid 58 can flow from the second drive chamber 55 to the second drive fluid container 59.

[0041] The first elastic separating element 4 and the second elastic separating element 54 are in a corresponding position, for example, both separating elements 4 and 54 are initially convex, as shown in Fig. 1. In the Fig. In Figures 2 to 5, the respective separating elements are symbolically drawn in a convex shape in the left part of the diagrams. In the middle part, they are drawn in a relaxed horizontal position, and in the right part, they are drawn in a concave position.

[0042] In diagram 100, the ordinate represents a difference Δp1 between the first pressure p1 and the second pressure p2. The abscissa represents the displacement x1 detected by the first displacement sensor 6. The left-hand region 102 of the graph 101 shows difference values ​​that are less than zero. This can be explained as follows: The first elastic separating element 4 and the second elastic separating element 54 are in a very strongly deformed convex position and have a high restoring force toward a relaxed position. Only a relatively small amount of the first drive fluid 8 is required to force the irrigation fluid out of the first pump chamber 3 toward the first outlet valve 26. The first pressure p1 is therefore somewhat lower than the second pressure p2, so that the difference Δp1 = p1 - p2 is negative.

[0043] In a central region 103 of the graph 101, the elastic separating elements 4 and 54 are in an approximately horizontal position and are only slightly or not at all deformed, thus relatively relaxed. In this case, the first pressure p1 for the first drive fluid 8 is almost equal to or identical to the second pressure p2 of the irrigation fluid. The difference Δp1 is therefore almost equal to or equal to zero in the central region 103 of the graph 101.

[0044] In a right-hand region 104 of the first graph 101, the values ​​are above the zero line. A relatively high pressure must be exerted by the first drive fluid 8 on the first elastic separating element 4 to bring this separating element 4 into a relatively strongly concavely deformed position. In this situation, irrigation fluid 21 flows out of the first outlet 25 at a lower pressure. The difference Δp1 = p1 - p2 is therefore positive.

[0045] Multiplying the pressure difference Δp1 by the projected cross-sectional area of ​​the first pump chamber 3 results in a compressive force. Using the first graph 101, a force-displacement characteristic curve for the first elastic separating element 4 can be determined. It is useful to record the force-displacement characteristic curve for the entire travel of the elastic separating element 4. This corresponds to the situation where the pump chamber 3 is initially completely filled with irrigation fluid 21 and is completely emptied at the end of the movement of the separating element 4.

[0046] Fig. 3 shows a second diagram 200 with a second graph 201 under the same conditions as described above in Fig. 2. The ordinate represents a difference Δp2 between the fourth pressure p4 and the third pressure p3. The abscissa represents the displacement x2 detected by the second displacement sensor 56. The left-hand region 202 of the second graph 201 shows difference values ​​that are less than zero. The second elastic separating element 54 is strongly convexly deformed and has a high restoring force toward a relaxed position. Therefore, a relatively low pressure must be applied in the second drive fluid line 57.

[0047] The fourth pressure p4 is therefore lower in magnitude than the third pressure p3 of the fluid flowing into the second pump chamber 53 at the second inlet 44. Thus, Δp2 = p4 - p3 is negative, see left-hand area 202 of graph 201.

[0048] In the central region 203 of the second graph 201, the second elastic separating element 54 is in a position with little or no deformation. Thus, the fourth pressure p4 is almost equal to or equal to the third pressure p3, so that the difference Δp2 is almost equal to or equal to zero.

[0049] In the right-hand area 204 of the second graph 201, the values ​​are above the zero line. To give the second elastic separating element 54 a concave shape, a relatively strong negative pressure must be applied in the second drive fluid line 57. Since the third pressure p3 is also a negative pressure, Δp2 = p4 - p3 is therefore positive.

[0050] Multiplying the second pressure difference by the projected cross-sectional area of ​​the second pump chamber 53 results in a pressure force. This makes it possible to determine a force-displacement characteristic curve for the second elastic pressure element 54.

[0051] The first elastic separating element 4 and the second elastic separating element 54 are two different components. They may be manufactured with great precision, but they are not identical. This also applies analogously to the first drive fluid line 7 and the second drive fluid line 57. Likewise, the first pressure sensor 11 and the fourth pressure sensor 43 are two different components that do not provide identical measured values. It is therefore to be expected that, when viewed more accurately, the first graph 101 does not exactly correspond to the second graph 201.

[0052] Fig. 4 shows a third diagram 300 with a third graph 301. In diagram 300, the ordinate represents a difference Δp3 between the second pressure p2 and the third pressure p3, i.e., Δp3 = p2 - p3. The abscissa represents the displacement x1 detected by the first displacement sensor 6.

[0053] The second pressure p2 is the pressure in the irrigation fluid line 22 immediately after the first outlet 25 of the first pumping chamber 3, and the third pressure p3 is the pressure in the aspiration fluid line 41 immediately before the second inlet 44 of the second pumping chamber 53. The length of the line between the connection of the second pressure sensor 28 to the first end 481 of the connecting line 48, the connecting line 48 to the second end 482 of the connecting line 48, and from there to the connection of the third pressure sensor 43 has a hydraulic resistance that is greater than zero. This causes the third pressure p3 to be slightly lower than the second pressure p2. This applies to the entire travel of the first elastic separating element 4, so that the third graph 302 shows a differential pressure Δp3 along the entire travel distance x1, which is positive.If this differential pressure Δp3 is divided by the hydraulic resistance R, this corresponds to the fluid flow through the specified distance.

[0054] Fig. Figure 5 shows a fourth diagram 400 with a fourth graph 401. In this diagram 400, the ordinate represents the difference Δp3 between the second pressure p2 and the third pressure p3, i.e., Δp3 = p2 - p3. The abscissa represents the displacement x2 detected by the second displacement sensor 56. The only difference to Fig. 4 is thus that the pressure difference is not shown as a function of the first displacement sensor 6, but of the second displacement sensor 56. If this pressure difference is divided by the hydraulic resistance of the path from the connection of the second pressure sensor 28 to the third displacement sensor 43, this corresponds to the fluid flow through this path.

[0055] It is possible for the hydraulic resistance R of a section running from the connection of the second pressure sensor 28 to the first end 481 of the connecting line 48, the connecting line 48 to the second end 482 of the connecting line 48, and from there to the connection of the third pressure sensor 43 to be known, and for the fluid flow Q along this section to be known as well. Then, either the second pressure sensor 28 or the third pressure sensor 43 can be dispensed with. If the second pressure sensor 28 is present and a second pressure p2 is present, but no third pressure sensor 43 or third pressure p3 is known, the third pressure is calculated as p3 = p2 - Q * R. The third pressure p3 is then not available as a measured value, but as a calculated value, which can be determined by the processing unit 70.However, if the third pressure sensor 43 and the associated third pressure p3 are known, but no second pressure sensor 28 is present or no second pressure p2 is present, the second pressure is calculated as p2 = p3 + Q * R, whereby this second pressure can be determined by the processing unit 70.

[0056] With system 1, it is thus possible to determine the spring characteristic of the first elastic separating element 4 and the associated flow through the irrigation fluid line 22 for calibration with the single movement of the first elastic separating element 4 from a filled first pump chamber 3 to an emptied first pump chamber 3. This also applies analogously to the second elastic separating element 54. Since this calibration can take place simultaneously for the first elastic separating element 4 and the second elastic separating element 54, four characteristic curves can be determined after only a single movement sequence from the filled first pump chamber 3 to the emptied first pump chamber 3 or from the emptied second pump chamber 53 to the filled second pump chamber 53. This represents a significant time saving compared to conventional calibration methods, in which each pump chamber must be calibrated individually and sequentially. Reference symbol 1 Ophthalmic surgical system 2 first fluid pump 3 first pumping chamber 4 first elastic separating element 5 first drive chamber 6 first displacement sensor 7 first drive fluid line 8 first drive fluid 9 first drive fluid tank 10 first actuator 11 first pressure sensor 19 third connection 20 irrigation fluid containers 21 Irrigation fluid 22 Irrigation fluid line 23 first inlet valve of the first pump chamber 24 first entrance of the first pumping chamber 25 first outlet of the first pumping chamber 26 first outlet valve of the first pump chamber 27 first connection 28 second pressure sensor 29 surgical instrument 30 hollow needles 31 Eye 32 lens 40 second connection 41 Aspiration fluid line 42 second inlet valve of the second pump chamber 43 third pressure sensor 44 second inlet of the second pumping chamber 45 second outlet of the second pumping chamber 46 second outlet valve of the second pump chamber 47 Aspiration fluid collection container 48 connecting line 481 first end of the connecting line 482 second end of the connecting line 49 fourth connection 52 second fluid pump 53 second pumping chamber 54 second elastic separating element 55 second drive chamber 56 second displacement sensor 57 second drive fluid line 58 second drive fluid 59 second drive fluid reservoir 60 second actuator 61 fourth pressure sensor 70 processing unit 71 first signal line 72 second signal line 73 third signal line 74 fourth signal line 75 fifth signal line 76 sixth signal line 80 Control unit 81 seventh signal line 82 eighth signal line 90 Flow direction 91 Flow direction 100 first diagram 101 first graph 102 left area of ​​the first graph 103 middle area of ​​the first graph 104 right area of ​​the first graph 200 second diagram 201 second graph 202 left area of ​​the second graph 203 middle area of ​​the second graph 204 right area of ​​the second graph 300 third diagram 301 third graph 400 fourth diagram 401 fourth graph p1 first print p2 second print p3 third print p4 fourth print Δp1 first differential pressure Δp2 second differential pressure Δp3 third differential pressure Q Fluid flow R hydraulic resistance

Claims

[1] Ophthalmic surgical system (1), comprising: - a first fluid pump (2) having a first pump chamber (3) with a first volume and a first drive chamber (5) with a second volume separated therefrom by a first elastic separating element (4), - a second fluid pump (52) having a second pump chamber (53) with a third volume and a second drive chamber (55) with a fourth volume separated therefrom by a second elastic separating element (54), - an irrigation fluid line (22) for conducting irrigation fluid (21) to an inlet (24) of the first pumping chamber (3), through the pumping chamber (3) to an outlet (25) of the first pumping chamber (3) and from there to a first connection (27) which is designed to be coupled to a surgical instrument (29), - an aspiration fluid line (41) for conducting aspiration fluid from a second connection (40) which is adapted to be coupled to the surgical instrument (29), to an inlet (44) of the second pumping chamber (53), through the second pumping chamber (53) to an outlet (45) of the second pumping chamber (53), - a first drive fluid line (7) for conducting a first drive fluid (8) to the first drive chamber (5), whereby the second volume can be increased and the first volume can be reduced at the same time by means of a deformation of the first elastic separating element (4), - a second drive fluid line (57) for conducting a second drive fluid (58) to the second drive chamber (59), whereby the fourth volume can be reduced and the third volume can be increased at the same time by means of a deformation of the second elastic separating element (54), - a first displacement sensor (6) for detecting a first deflection position (x1) of the first elastic separating element (4), - a second displacement sensor (56) for detecting a second deflection position (x2) of the second elastic separating element (54), - a first pressure sensor (11) for detecting a first pressure (p1) in the first drive fluid line (7), - a second pressure sensor (28) for detecting a second pressure (p2) at the outlet of the first pumping chamber (3), and / or a third pressure sensor (43) for detecting a third pressure (p3) at the inlet of the second pumping chamber (53), - a fourth pressure sensor (61) for detecting a fourth pressure (p4) in the second drive fluid line (57), - a connecting line (48) which is arranged to directly connect the irrigation fluid line (22) to the aspiration fluid line (41), - a processing unit (70) which is configured to process the first pressure (p1), the second pressure (p2) and / or the third pressure (p3), the fourth pressure (p4) in each case as a function of the first deflection position (x1) and the second deflection position (x2). [2] Ophthalmic surgical system (1) according to claim 1, which has a control unit (80) which detects signals of the processing unit (70) and is coupled to a first actuator (10) in the first drive fluid line (7) for controlling the first drive fluid (8) and to a second actuator (60) in the second drive fluid line (57) for controlling the second drive fluid (58). [3] Ophthalmic surgical system (1) according to claim 1 or 2, wherein the processing unit (70) is configured to process a difference between the first pressure (p1) and the second pressure (p2) as a function of the first deflection position. [4] Ophthalmic surgical system (1) according to one of the preceding claims, wherein the processing unit (70) is arranged to process a difference of the fourth pressure (p4) from the third pressure (p3) as a function of the second deflection position. [5] Ophthalmic surgical system (1) according to one of the preceding claims, wherein the processing unit (70) is configured to process a difference between the second pressure (p2) and the third pressure (p3) as a function of a hydraulic resistance of at least a part of the irrigation fluid line (22), the connecting line (48) and at least a part of the aspiration fluid line (41). [6] Ophthalmic surgical system (1) according to claim 5, wherein the processing unit (70) is configured to process the flow and a time derivative of the first deflection position (x1) together. [7] Ophthalmic surgical system (1) according to claim 5 or 6, wherein the processing unit (70) is configured to process the flow and a time derivative of the second deflection position (x2). [8] Method for controlling the ophthalmic surgical system (1) according to one of the preceding claims, comprising the steps: - closing an outlet valve (26) of the first pumping chamber (3) and an inlet valve (42) of the second pumping chamber (53), - Filling the first pump chamber (3) with irrigation fluid (21), - Emptying the first drive chamber (5) of the first drive fluid (8), - Emptying the second pumping chamber (53) of aspiration fluid, - filling the second drive chamber (55) with the second drive fluid (58), - closing an inlet valve (23) of the first pumping chamber (3) and an outlet valve (46) of the second pumping chamber (53), - feeding the first drive fluid (8) into the first drive chamber (5), - connecting the irrigation fluid line (22) to the aspiration fluid line (41) by means of the connecting line (48), - Opening the outlet valve (26) of the first pumping chamber (3) and the inlet valve (42) of the second pumping chamber (53), - discharging the second drive fluid (58) from the second drive chamber (55), - Emptying the first pumping chamber (3) of irrigation fluid (22) and filling the second pumping chamber (53) with this irrigation fluid (22), - detecting measured values ​​of the first deflection position (x1) of the first displacement sensor (6), the second deflection position (x2) of the second displacement sensor (56), the first pressure (p1), the second pressure (p2) and / or the third pressure (p3), the fourth pressure (p4), - feeding the measured values ​​to the processing unit (70).

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