Ophthalmosurgical handpiece for treating the lens of an eye

Abstract

The invention relates to an ophthalmosurgical handpiece (2) for treating the lens (31) of an eye (29), to an ophthalmosurgical system (1), and to a method. The handpiece (2) comprises a connecting piece (70), on which a needle (20) having a needle tip (21) is mounted and which is coupled to a vibration-generating device (22), and the vibration-generating device (22), which can excite the needle (20), via the connecting piece (70), so as to vibrate. The handpiece (2) can be operated in a high-energy mode (42), in which the vibration components are excited at least by means of a first piezo element (24), and in a low-energy mode (44), in which the vibration components are excited at least by means of a second piezo element (23). Alternatively or additionally, the handpiece (2) can be operated in a pre-tensioning mode, in which a pre-tension is applied to the first piezo element (24) and / or the second piezo element (23) by actuating at least one piezo-based pre-tensioning device (35).

Description

[0001] Ophthalmic surgical handpiece for treating the lens of an eye

[0002] The invention relates to an ophthalmic surgical handpiece for treating the lens of an eye. Furthermore, the invention relates to an ophthalmic surgical system with such a handpiece and a method for operating an ophthalmic surgical handpiece for treating the lens of an eye.

[0003] An ophthalmic surgical system is used to treat a patient's eye, for example, during cataract surgery, when the patient's eye has a clouding of the lens, known as a cataract. Phacoemulsification is a particularly common technique in this context. In this procedure, a thin needle, especially a hollow needle, is inserted into the lens capsule of the eye being treated and set into mechanical vibrations within the capsule. The needle, which is inserted into the eye at the tip of the needle, is part of an ophthalmic surgical handpiece. The lens of the eye is broken up by the vibrating needle tip, releasing lens particles into the eye. These released lens particles are then aspirated through an aspiration tube of the ophthalmic surgical system.Simultaneously, an irrigating fluid is administered to the eye via an irrigation line of the ophthalmic surgical system. Once the lens has been completely removed from the eye, a new artificial lens can be inserted into the emptied capsular bag. This can result, for example, in the treated patient achieving improved vision compared to their vision before the operation.

[0004] During surgery, for example, high heat generation can occur due to the intensity of needle tip vibration and / or the duration of the procedure. This can cause tissue adjacent to the needle tip and / or the cornea punctured by the needle tip to become so hot that burns may occur, potentially resulting in permanent damage to the patient. Such high heat generation must therefore be prevented. US 2021 / 0196515 A1 discloses a surgical instrument for phacoemulsification. The instrument includes a dual-frequency voltage generation circuit comprising a low-frequency voltage path with a low-frequency LC network and a high-frequency voltage path with a high-frequency LC network.

[0005] US 8,545,528 B2 discloses a system for performing an ophthalmic surgical procedure. The system comprises a multi-frequency signal source, a configurable tuned output filter connected to the multi-frequency signal source, and a multi-frequency ultrasound handpiece.

[0006] The object of the invention is to provide a solution by means of which heat input into the eye can be kept low.

[0007] The problem is solved by the subject matter of the independent patent claims.

[0008] A first aspect of the invention relates to an ophthalmic surgical handpiece for treating the lens of an eye. The ophthalmic surgical handpiece can be comprised of an ophthalmic surgical system. The ophthalmic surgical handpiece can be inserted, at least partially, into the eye of a patient by a practitioner during surgery, particularly during phacoemulsification.

[0009] The ophthalmic surgical handpiece comprises several vibration components that can be excited to oscillation. Individual vibration components are described below. Further vibration components beyond those described are possible. One of the vibration components of the ophthalmic surgical handpiece is a connecting piece to which a needle with a needle tip is mounted. The needle and needle tip are also vibration components. The connecting piece is, for example, a horn. The connecting piece, particularly the horn, and the needle together form a sonotrode. In a preferred example, the needle is designed as a hollow needle. In this example, it has a hollow needle tip. The needle tip is located at the end of the needle facing away from the connecting piece.The connecting piece is coupled at one end, opposite the needle, to a vibration-generating device of the ophthalmic surgical handpiece. The vibration-generating device is a vibration component of the ophthalmic surgical handpiece. It is designed to excite the needle to vibrate via the connecting piece. This vibration can be longitudinal and / or torsional. In one example, the vibration-generating device can additionally or alternatively excite the connecting piece and needle to vibrate transversely. The vibration-generating device can include a transducer or form a transducer that can convert electrical energy supplied to the ophthalmic surgical handpiece into mechanical vibration.

[0010] The needle tip can alternatively be referred to as the point, tip, or cutting tip. The needle tip is the part of the ophthalmic surgical handpiece used, for example, to penetrate the cornea and puncture the lens of the eye. The connecting piece is designed to transmit the vibration generated by the vibration unit to the needle and its tip. This excites at least the needle tip to vibrate at a predetermined frequency, resulting in a predetermined amplitude of vibration. The vibrating parts of the ophthalmic surgical handpiece can be partially combined into a transducer. The transducer comprises the vibration unit and the connecting piece. The connecting piece with the mounted needle is, for example, housed within the casing of the ophthalmic surgical handpiece, and is specifically mounted there.

[0011] The invention is based on the understanding that, during eye surgery, for example, a mechanical power of 50 watts can be used to vibrate the components, particularly the needle and its tip. Such power is typically sufficient to shatter even lenses with relatively hard cataracts. However, this high power results in a significant energy input into the eye. As described above, this can lead to burns. Therefore, such intense heat generation must be prevented. Furthermore, the longitudinal vibrations of the needle tip can cause the lens particles to be pushed away from the needle tip and move in a direction opposite to the direction in which they are aspirated from the eye.This can, for example, increase the duration required for the operation, which may also lead to undesirably high heat generation in the eye during the procedure. Furthermore, it is known that, depending on the degree of cataract hardness, different energy inputs are sufficient to shatter the lens into lens particles. It can therefore be advantageous to reduce the energy input into the eye if the degree of cataract of the lens to be shattered allows for this. Therefore, different operating modes of the ophthalmic surgical handpiece should be adjustable, resulting in different energy inputs into the eye. According to the invention, a high-energy mode and a low-energy mode are therefore provided.

[0012] Furthermore, the invention is based at least on the understanding that an increased duration of the operation and, if applicable, an associated increase in heat generation can occur if a desired vibration of the needle tip can no longer be achieved, for example, due to aging effects of components of the vibration generation device. Therefore, these aging effects should also be counteracted. One measure that can be taken to counteract these aging effects includes applying a mechanical preload to the components of the vibration generation device affected by these effects. The components affected by these aging effects are typically piezoelectric elements. These are subject to continuous aging, during which depolarization effects occur, resulting in a decrease in the efficiency with which the piezoelectric element can convert electrical energy into mechanical energy.Over time, an efficiency loss occurs, which can initially be compensated for, for example, by increasing the applied electrical energy. In this case, a predetermined oscillation of the needle tip can be maintained by supplying more electrical energy to the vibration-generating device than before. However, beyond a certain efficiency loss, this can no longer be compensated for by supplying more electrical energy; that is, the supplied electrical energy cannot be increased as much as necessary to maintain the predetermined oscillation of the needle tip. It is then only possible to operate the needle and its tip with a reduced oscillation power, ultimately resulting in a lower frequency than desired.However, this can lead to an increase in the duration of the operation and ultimately to undesirable heat generation, as the desired oscillation of the needle tip can no longer be achieved. Therefore, aging should be counteracted, which is possible by applying a preload to the piezoelectric element. The applied preload can increase the efficiency and / or sound transmission power of the piezoelectric element, so that the desired oscillation can be achieved with a given amount of electrical energy. The increase in sound transmission power results, for example, from improved vibration coupling at the contact surfaces of individual components of the vibration generation device, such as between the piezoelectric element and the electrodes of the vibration generation device.Therefore, a pre-tensioning mode should be provided in which the piezoelectric element is electrically and / or mechanically subjected to the currently required pre-tension.

[0013] Furthermore, or alternatively, applying a mechanical stress to the piezoelectric element of the vibration generator can prevent it from being subjected to tensile stress during excitation, which can at least contribute to, and in particular lead to, the failure of the piezoelectric element. Moreover, applying a mechanical stress to the piezoelectric element of the vibration generator can at least help ensure that the desired vibration of the needle tip is achieved in the first place. Therefore, applying a mechanical stress to the piezoelectric element, and thus the preload, should be carried out regardless of aging effects.

[0014] The handpiece is designed to operate in a high-energy mode. In high-energy mode, at least the vibration components, particularly the needle tip, oscillate at a frequency within a predefined first frequency range, such that the energy input to the eye exceeds a predefined limit. This can be achieved, for example, by ensuring that the amplitude of the vibration, for instance in the area of ​​the needle, especially the needle tip, is greater than a predefined limit amplitude. Alternatively or additionally, the energy input exceeding the predefined limit can be achieved by applying an input voltage greater than a predefined input voltage limit to at least one component of the vibration-generating device. In one example, the applied input voltage is sinusoidal.

[0015] The vibration generation device is designed to excite the vibration components in high-energy mode, at least by means of a first piezoelectric element. The high-energy mode is suitable, for example, for treating cataracts with a moderate to high degree of cataracts, as this requires a relatively high energy input.

[0016] Furthermore, the handpiece is designed to operate in a low-energy mode in which at least the oscillating components, particularly the needle tip, vibrate at a frequency within a predefined second frequency range different from the first, so that the energy input into the eye is lower than the predefined limit. This can, for example, result in a lower amplitude of the oscillation than the predefined limit amplitude, thus achieving a lower energy input into the patient's eye than in high-energy mode. Alternatively, a second frequency range can be selected for the low-energy mode in which an amplitude of the oscillation is achieved that is greater than the predefined limit amplitude, but an input voltage is applied that is lower than the predefined input voltage limit.This comparatively low input voltage, compared, for example, to a typical input voltage in high-energy mode, can ensure that the energy input into the eye is kept low, especially lower than in high-energy mode. This approach is suitable, for example, for a second frequency range in which the needle tip is locally excited to a large-amplitude oscillation that exceeds the specified limit amplitude. In contrast, in a first frequency range suitable for high-energy mode, at least a region of the needle adjacent to the tip is also excited. Alternatively, by selecting a frequency independent of the oscillation amplitude, a lower energy input into the patient's eye can be achieved than in high-energy mode.

[0017] The vibration generation device is designed to excite the vibration components in low-energy mode, at least by means of a second piezoelectric element different from the first. Low-energy mode is suitable, for example, for treating cataracts of moderate to low severity, as it requires less energy input compared to high-energy mode. Furthermore, in low-energy mode, the lens particles are ejected less forcefully from the needle tip than in high-energy mode. This can reduce the duration of the procedure, as the lens particles can be aspirated more quickly, thus minimizing heat generation in the eye.

[0018] High-energy mode is therefore an operating mode of the ophthalmic surgical handpiece in which the energy input to the patient's eye is high, whereas low-energy mode is an operating mode in which the energy input to the patient's eye is lower than in high-energy mode. The different energy input levels can be adjusted by setting the frequency at which at least the oscillation components vibrate. It is assumed that by setting the frequency, for example, a desired amplitude can be achieved and / or the applied input voltage can be set in such a way that a suitable amplitude for high-energy mode is attenuated. The desired amplitude might, for example, be smaller in low-energy mode than in high-energy mode.Alternatively, the desired amplitude can be greater in low-energy mode than in high-energy mode, provided that the energy input into the eye is nevertheless lower than in high-energy mode. This can be achieved by applying the input voltage below the input voltage limit. To understand the energy input into the eye due to the inserted oscillating needle tip, an equation for calculating the energy E of an undamped harmonic oscillation of a point mass m with amplitude A and frequency f is given below.

[0019] This simplifies the understanding that mass, frequency, and amplitude all influence the energy input of a vibrating needle tip into the eye.

[0020] The vibration generation device comprises at least two piezoelectric elements, referred to here as the first and second piezoelectric elements. They can alternatively be called the first and second piezoelectric stack. In one example, the first piezoelectric element might be designated only for the high-energy mode, and the second piezoelectric element only for the low-energy mode. The amplitude of the vibration at the needle tip might, in another example, be a maximum of 200 micrometers in high-energy mode and a maximum of 40 micrometers, or even only a maximum of 2 micrometers, in low-energy mode. These amplitudes can be adjusted, for example, by setting a corresponding frequency, whereby different frequencies are used in the high-energy and low-energy modes, since the two different frequency ranges are predefined.In this example, the energy input into the eye in low-energy mode is only about 1 / 300 or 1 / 8000 compared to the energy input in high-energy mode.

[0021] The high-energy and low-energy modes can be used alternately, for example. Switching between these two energy modes is particularly possible during surgery. Alternatively or additionally, the handpiece can be operated in either high-energy or low-energy mode, especially for a predetermined period. This allows for the combination of conventional ultrasound technology, which uses, for example, vibration frequencies between 20 kilohertz and 1 gigahertz, and low-frequency technology, which uses comparatively lower vibration frequencies, in a single ophthalmic surgical handpiece. Ultimately, the ophthalmic surgical handpiece can be operated comfortably and with minimal effort using at least two different frequencies, one corresponding to the high-energy mode and the other to the low-energy mode.

[0022] Alternatively or additionally to the high-energy and low-energy modes, the ophthalmic surgical handpiece is designed to operate in a preload mode. In preload mode, the vibration generation unit is configured to apply a mechanical preload to the first and / or second piezoelectric element by controlling at least one piezoelectric preloading device of the vibration generation unit. This allows the needle tip to be excited to a predetermined vibration with less electrical energy supplied by the preloaded piezoelectric element compared to the same piezoelectric element without the preload. The supplied electrical energy here refers to the energy with which the handpiece is powered. Alternatively, an electrical voltage applied to the handpiece, particularly to the vibration generation unit, can be considered.For example, if the needle tip is to vibrate at a resonant frequency, this vibration is achieved in preload mode due to the set preload upon a first energy input into the handpiece. If, instead, the piezoelectric element is used without a set preload, a second energy input, greater than the first, is required to make the needle tip vibrate at the resonant frequency. The resonant frequency, as defined in the invention, refers to the vibration components, in particular the transducer, i.e., the connecting piece with piezoelectric elements mounted on it and clamped by bolts, such as several piezoelectric discs. In the case of resonance, i.e., when the resonant frequency is applied, the amplitude of the needle tip's vibration is at its maximum, at least locally.

[0023] In other words, the piezo-based preloading device achieves a change in the stiffness of at least one of the piezoelectric elements, in particular both or all of them. This preloading mode thus makes it possible to extend the service life of piezoelectric handpieces. For example, if a drop in performance is detected and cannot be compensated for by increasing the electrical energy input, the desired mechanical output can be restored by activating the piezoelectric preloading device. This helps ensure that, for example, the set vibrations in high-energy and low-energy modes can actually be maintained, even if aging effects of the piezoelectric elements occur.Furthermore, or alternatively, the piezo-based preload device can prevent the first and / or second piezoelectric element from being subjected to tensile stress during excited vibration, which could at least contribute to, and in particular lead to, the failure of the piezoelectric element. Moreover, applying the preload device to the first and / or second piezoelectric element helps to ensure that the desired vibration of the needle tip is achieved. The preload mode can be activated, for example, during the preparation phase of an operation with the ophthalmic surgical handpiece and / or during the initial phase of the operation, to ensure, for instance, that the resonant frequency is adjustable.Alternatively or additionally, the ophthalmic surgical handpiece can be designed to operate simultaneously in high-energy and pre-tension modes, or simultaneously in low-energy and pre-tension modes. In high-energy and pre-tension modes, the piezoelectric element subjected to pre-tension is, for example, the second piezoelectric element that is not currently needed in high-energy mode. Conversely, in low-energy and pre-tension modes, the piezoelectric element subjected to pre-tension is, for example, the first piezoelectric element that is not currently needed in low-energy mode. This allows the pre-tension mode to be activated at a predetermined time, in addition to either the high-energy or low-energy mode. This enables the pre-tension mode to be used at any time during handpiece operation, particularly during surgery.

[0024] The ophthalmic surgical handpiece may include a control device, which is in particular associated with or encompassed by the vibration generation device, wherein the control device is configured to switch between the individual described operating modes, i.e., the high-energy mode, the low-energy mode and / or the bias mode, and to operate the handpiece according to a currently set or activated operating mode.

[0025] Overall, the differentiation between the high-energy mode and the low-energy mode, as well as the enabling of the pre-tension mode, contribute at least indirectly to keeping the heat input into the eye low.

[0026] One embodiment relates to the ophthalmic surgical handpiece, which can be operated in high-energy and low-energy modes. In high-energy mode, the vibration generation device is designed to additionally excite the vibration components, particularly the needle and its tip, using the second piezoelectric element. Alternatively or additionally, in low-energy mode, the vibration generation device is designed to additionally excite the vibration components, particularly the needle and its tip, using the first piezoelectric element. It is therefore possible to use both piezoelectric elements in high-energy mode and / or low-energy mode. For this purpose, the two piezoelectric elements can be controlled simultaneously and / or sequentially, for example, with two different or two matching electrical signals, particularly by means of the control device.Each piezoelectric element can be powered, for example, by an AC or DC electrical supply. Therefore, the oscillation desired in the respective operating mode can be adjusted in a variety of ways using these two piezoelectric elements, always reliably.

[0027] Another embodiment also provides that the vibration generating device can be operated in high-energy and low-energy modes. In high-energy mode, the vibration generating device is designed to excite the vibration components, in particular the needle and its tip, such that the needle tip vibrates at a first frequency. This first frequency is, in particular, between 36 kilohertz and 45 kilohertz. Specifically, it is between 43 kilohertz and 44 kilohertz, for example, at 43.2 kilohertz. The first frequency can be a resonant frequency. Alternatively or additionally, in low-energy mode, the vibration generating device is designed to excite the vibration components, in particular the needle and its tip, such that the needle tip vibrates at a second frequency different from the first. The second frequency can be an operating frequency or another resonant frequency.The secondary resonant frequency differs, for example, from the resonant frequency that can be used for the high-energy mode. At the secondary resonant frequency, the amplitude of the needle tip's vibration is, for example, smaller or larger than at the primary resonant frequency. The second frequency, in particular the operating frequency, is specifically between 50 hertz and 1 kilohertz. Alternatively or additionally, the second frequency, in particular the secondary resonant frequency, is specifically between 2 kilohertz and 10 kilohertz, for example, between 9 kilohertz and 10 kilohertz or at 9.4 kilohertz. Alternatively or additionally, the second frequency, in particular the secondary resonant frequency, is specifically between 60 kilohertz and 80 kilohertz, for example, between 65 kilohertz and 66 kilohertz or at 65.9 kilohertz, or between 74 kilohertz and 75 kilohertz or at 74.9 kilohertz.Depending on the handpiece used, different first and / or second frequencies can be employed. The first and / or second frequency can be determined, for example, during handpiece commissioning and / or during surgical preparation, and the high-energy or low-energy mode can then be adjusted to the frequencies determined. The high-energy mode reliably utilizes the potential for high energy input into the eye, achieved, for example, through the needle tip oscillating with a large amplitude, whereas the low-energy mode, in comparison, results in a lower energy input into the eye, for example, through the smaller amplitude of the oscillating needle tip and / or by selecting a correspondingly low input voltage for the vibration generator.

[0028] The specific values ​​of the first and / or second frequencies within the specified intervals can depend, for example, on whether the needle tip is inserted into the eye, particularly into the lens, or not. When in contact with the eye, especially the lens, the frequency changes compared to the frequency when the needle tip is in contact with air outside the eye. To account for this, a control algorithm of the ophthalmic surgical system, particularly the ophthalmic surgical handpiece, can be used to detect the current vibration behavior of the needle tip and adjust the current operating frequency of the handpiece so that the needle tip vibrates at the first or second frequency. This adjustment of the vibration behavior can alternatively or additionally be achieved using the piezoelectric preload device.

[0029] Another embodiment provides that the vibration generation device can be operated in high-energy and low-energy modes. The ophthalmic surgical handpiece has a control device. This control device can correspond to the control device mentioned above. The control device is configured to switch between high-energy and low-energy modes when at least one of the following conditions is met: One condition is that a frequency shift exists, causing the needle tip's vibration to deviate from a predetermined vibration pattern. The frequency shift can alternatively be described as a detuning or damping of the needle tip, or as the detection of a load case, which always occurs when the needle tip is in contact with the lens, thereby influencing, for example, attenuating, the needle tip's vibration.Depending on the extent of this frequency shift, it is possible to infer, for example, the degree of cataracts or similar information.

[0030] Another condition for switching between the two energy modes is that the needle is hollow and an occlusion occurs at the needle tip. In the case of occlusion, the needle tip, and thus an opening of the hollow needle, is blocked, for example, by a lens particle. If occlusion occurs, it may be useful to switch to the high-energy mode to break up the lens particle blocking the needle tip. If, for example, no occlusion is detected, the system can switch to the low-energy mode or remain in it.

[0031] Another condition could be a temperature at the needle tip within a predefined range. This temperature can be used, for example, to determine whether parts of the eye have already become uncomfortably and / or potentially unhealthily warm for the patient. If, for instance, relatively strong warming is detected, such that the temperature falls within the predefined range, the system can switch to low-energy mode. However, if the temperature falls outside the predefined range, the system can switch to high-energy mode or remain in it. Different temperature ranges could be defined for high-energy and low-energy modes.The temperature at the needle tip can be measured and / or determined, for example, using a temperature sensor on the handpiece and / or a sensor on the ophthalmic surgical system and / or a diagnostic device not integrated into the ophthalmic surgical system. The diagnostic device can, for example, transmit the temperature to the ophthalmic surgical system and / or display the temperature, which can then be manually entered into the ophthalmic surgical system. Another requirement is that the treated eye has a cataract grade within a predefined range. A small to moderate degree of cataract is typically assigned to the low-energy mode, and a higher degree of cataract to the high-energy mode.The degree of cataract can be determined, for example, using a microscope connected to the ophthalmic surgical system, which at least partially captures and analyzes the lens. Alternatively or additionally to the microscope, another diagnostic device can be provided that can transmit and / or output data for determining the degree of cataract and / or data describing the degree of cataract to the ophthalmic surgical system, in particular displaying it.

[0032] The switch between high-energy and low-energy modes can occur automatically. Alternatively or additionally, a user, such as the surgeon, can initiate the switch manually. This can be done preoperatively, for example. A manual selection between high-energy and low-energy modes can be made by recording an action using a control element on the handpiece and / or the ophthalmic surgical system. The selection can be based, for example, on preoperatively acquired data describing the degree of cataracts. Alternatively or additionally, the manual switch can be performed intraoperatively, for example, by using a foot pedal and / or another control element during the operation.Due to the various conditions that can trigger a switch between high-energy mode and low-energy mode, situation-specific and precise activation of one of these two operating modes is possible, ensuring that the most suitable operating mode is always reliably selected.

[0033] Another embodiment provides that the vibration generation device can be operated in preload mode. The at least one piezo-based preload device includes at least one piezo-based washer. The piezo-based washer can alternatively be referred to as a piezo shim. The piezo-based washer is designed to apply the mechanical preload to the respective piezoelectric element by changing its thickness. The change in thickness can be controlled by applying a predetermined electrical voltage to the washer. For example, if the thickness of the washer increases, thereby pressing the washer at least locally against the piezoelectric element, a preload is established on the piezoelectric element, or the preload of the piezoelectric element is increased.The preload ensures that, for example, the piezoelectric ceramic interfaces of the piezoelectric element, which can degrade in quality over the element's lifetime (e.g., due to settling losses in the components involved), can establish better contact with at least a portion of the needle. This allows vibrations to be transmitted to the needle tip with less loss. A loss in the efficiency of the respective piezoelectric element can thus be compensated for, and the lifespan of the handpiece extended.

[0034] If, for example, a drop in the resonant frequency of the needle tip below a predefined threshold is observed, the ophthalmic surgical handpiece can be counteracted by activating the piezo-based preload device, i.e., the piezo-based washer. This allows the drop in the resonant frequency to be compensated for. The compensation can be dynamic, meaning it can be applied situationally. The ophthalmic surgical system is thus returned to a stable state in preload mode, in which, for example, the previously lowered resonant frequency is raised back to its original value. If a load (mass) on the needle tip temporarily reduces the system's resonant frequency, the washer can also counteract this by increasing the mechanical preload. Therefore, increasing the preload can result in a frequency increase.Therefore, the operation can also be supported in the short term, for example by activating the washer when the lens comes into contact with it.

[0035] The ophthalmic surgical handpiece can, in particular, have several washers, for example, at least one washer per piezoelectric element. The washers can be controlled, for example, via an electrical supply voltage. For instance, the washer can be supplied with a DC voltage to set the desired thickness and thus the desired preload. After the thickness has been set by a voltage of, for example, 50 volts to 200 volts, the supply of electrical energy to the piezoelectric preloading device, i.e., the washer, can be switched off using a control unit or regulator. This prevents the washer, whose thickness has already been changed, from changing further. The thickness is maintained after the supply voltage is switched off. This ensures that a constant preload can be maintained.For example, the washer can be deflected to a thickness of 20 micrometers, thereby applying a preload of up to 800 megapascals to the piezoelectric element. By re-applying the voltage, the thickness can be changed, thus altering the preload, particularly increasing it. The preload mechanism can be repeatedly controlled, for example, depending on any current age-related changes in the resonant frequency.

[0036] The control unit or control device of the preload device can be implemented in numerous configurations. For example, a control loop can be provided. During an adjustment process while the piezoelectric elements are operating or at short control intervals, the resonant frequency or a vibration amplitude equivalent is measured, and the thickness of the washer is adjusted using a DC voltage signal to change the preload of the piezoelectric element(s), which may be operated with AC, for example.

[0037] Another embodiment provides that the ophthalmic surgical handpiece has at least one mechanical preloading device that applies a predetermined preload to the respective piezoelectric element. The predetermined preload of the mechanical preloading device can be the same as or different from the preload that can be applied by means of the piezoelectric preloading device. The at least one mechanical preloading device is, in particular, designed as a screw nut. This can, for example, be screwed onto the respective piezoelectric element in such a way that it presses against the piezoelectric element. In addition to or as an alternative to the preloading mode, a fixed preload can be mechanically predetermined. Alternatively or additionally, several mechanical preloading devices can be provided, for example, at least one per piezoelectric element.The multiple mechanical preload devices can independently apply the preload or interact with each other. This is another way to counteract aging effects and achieve a particularly advantageous resonant vibration of the needle tip.

[0038] Another embodiment provides that the respective piezoelectric element comprises several piezoelectric rings arranged side by side in a section of the connector on an outer wall of the connector. The connector can thus be locally surrounded by the piezoelectric rings in this section. The connector is, for example, cylindrical. A piezoelectric ring is a ring-shaped, piezoelectric-based component. With an inner wall, the respective piezoelectric ring can, for example, rest against the outer wall of a core, particularly a cylindrical element, of the connector. The outer wall of the connector can, for example, be an outer wall of the horn. The respective piezoelectric element can, for example, be composed of two, four, or six individual piezoelectric rings. The individual piezoelectric rings can, for example, be made of the piezoceramics PZT4 or PZT8.Lead-free piezoelectric materials, such as PIC050 or PIC700 made of bismuth sodium titanate, can be used as an alternative or in addition. Both piezoelectric elements can have the same number of piezoelectric rings and / or piezoelectric rings made of the same material. Alternatively, the two piezoelectric elements can have a different number of piezoelectric rings and / or piezoelectric rings made of different materials. The thickness of a single piezoelectric ring, for example, ranges from 0.5 millimeters to 3 millimeters. The outer diameter of each piezoelectric ring can range from 5 millimeters to 10 millimeters. Using piezoelectric rings makes the piezoelectric elements simple and cost-effective to produce.

[0039] Another embodiment provides that the ophthalmic surgical handpiece has at least one spacer element. This can alternatively be referred to as a spacer sleeve. The spacer element is arranged between the first and second piezoelectric elements and spatially separates them, that is, it spatially separates the first piezoelectric element from the second. The spacer element is particularly designed as a sleeve that is arranged on an outer wall of the connecting piece, for example, between the piezoelectric rings of the first piezoelectric element and the piezoelectric rings of the second piezoelectric element. The spacer element has, for example, a length between 0 millimeters and 100 millimeters. The distance between the first and second piezoelectric elements and / or the determination of which piezoelectric element is closer to the needle tip can depend on the geometry of the connecting piece.To determine the spacing and / or to make the decision, the relationship between wave speed, wavelength, and frequency can be considered, and / or the goal can be achieved to maximize the efficiency and displacement of the needle tip when excited to vibrate by the first and / or second piezoelectric element, with the maximum displacement ideally coinciding with an antinode of the excited oscillation. The spacing element, and its precise size and position, thus enable advantageous adjustment of the needle tip's vibration behavior.

[0040] In another example, the distance between the two piezoelectric elements can be zero. In this example, no spacer is positioned between the piezoelectric elements. The two piezoelectric elements can then, for example, be controlled separately or simultaneously and be electrically separated from each other by a ground electrode.

[0041] Another aspect of the invention relates to an ophthalmic surgical system for treating an eye. The ophthalmic surgical system comprises an ophthalmic surgical handpiece for treating a lens of the eye, as described above. The ophthalmic surgical system also comprises a console. The console may, for example, have a cassette receiving area for receiving a cassette. Furthermore, the ophthalmic surgical system may include the cassette, which may, for example, have at least one fluid pump for delivering an irrigation fluid. The ophthalmic surgical handpiece can be connected to at least the console, or in particular to the cassette, for example, via a cable connection. The console may include a drive fluid supply system for supplying a drive fluid, such as compressed air, to a drive chamber of the fluid pump in the cassette.The fluid pump can have a pump chamber in addition to the drive chamber, wherein the two chambers can be separated from each other by means of a separating element that is at least partially deflectable. The irrigation fluid can be supplied to the pump chamber. Furthermore, for example, a sensor unit can be provided by means of which the deflection position of the separating element can be determined. The exemplary embodiments described in connection with the ophthalmic surgical handpiece according to the invention, both individually and in combination with one another, apply accordingly, insofar as applicable, to the ophthalmic surgical system according to the invention.

[0042] Another aspect of the invention relates to a method for operating the above-described ophthalmic surgical handpiece for treating the lens of an eye. The handpiece has at least the following vibration-generating components: a connecting piece to which a needle with a needle tip is mounted and which is coupled at one end opposite the needle to a vibration-generating device of the ophthalmic surgical handpiece, and the vibration-generating device itself. The vibration-generating device is configured to excite the needle to vibration via the connecting piece.

[0043] The handpiece can be operated in a high-energy mode in which at least the vibration components oscillate at a frequency within a predefined first frequency range, such that the energy input to the eye is greater than a predefined limit. In high-energy mode, the vibration generation device excites the vibration components at least by means of a first piezoelectric element. The handpiece can also be operated in a low-energy mode in which at least the vibration components oscillate at a frequency within a predefined second frequency range different from the first, such that the energy input to the eye is less than the predefined limit. In low-energy mode, the vibration generation device excites the vibration components at least by means of a second piezoelectric element, different from the first.

[0044] Alternatively or additionally, the handpiece can be operated in a pre-tensioning mode in which the vibration generation device applies a pre-tension to the first piezoelectric element and / or the second piezoelectric element by controlling at least one piezoelectric pre-tensioning device of the vibration generation device, so that the needle tip can be excited to a predetermined vibration with less electrical energy by means of the pre-tensioned piezoelectric element compared to the same piezoelectric element without the pre-tensioning.

[0045] The embodiments described in connection with the ophthalmic surgical handpiece according to the invention, both individually and in combination with each other, apply, where applicable, to the method.

[0046] The invention comprises combinations of the described embodiments.

[0047] The control device includes, for example, a processor. This processor can include at least a microprocessor, microcontroller, FPGA (Field Programmable Gate Array), and / or DSP (Digital Signal Processor). Furthermore, it can contain program code, which can alternatively be referred to as a computer program product. The program code can be stored in a data memory of the processor.

[0048] The figures show:

[0049] Fig. 1 shows a schematic representation of an ophthalmic surgical system with an ophthalmic surgical handpiece,

[0050] Fig. 2 shows a schematic cross-sectional view of an ophthalmic surgical handpiece;

[0051] Fig. 3 shows a schematic representation of frequencies;

[0052] Fig. 4 shows a schematic representation of a control mechanism for piezoelectric elements; and

[0053] Fig. 5 shows a schematic representation of a control system for an ophthalmic surgical handpiece in a preload mode.

[0054] In the figures, functionally identical elements are provided with the same reference numerals.

[0055] Fig. 1 shows an ophthalmic surgical system 1. The ophthalmic surgical system 1 includes an ophthalmic surgical handpiece 2, which is suitable for insertion into the eye 29 (not shown to scale, see reference numeral 29 in Fig. 2) of a patient during surgery, such as cataract surgery. The ophthalmic surgical system 1 includes a console 3. This console has, for example, a cassette receiving area 4 for a cassette 5 of the ophthalmic surgical system. The cassette 5 has, for example, at least one fluid pump 6 for delivering an irrigation fluid, which can be provided, for example, in a reservoir 8 and supplied to the cassette 5 via an irrigation fluid line 9. The cassette 5 can have, as sketched here, four fluid pumps 6 or another number of fluid pumps.

[0056] A connecting line 10 may be provided between the cassette 5 and the ophthalmic surgical handpiece 2, through which, for example, the irrigation fluid can be directed to the handpiece 2 and / or from the handpiece 2 to the cassette 5, an aspiration fluid can be conveyed, which is then aspirated from the eye 29 during the operation. The cassette 5 may therefore have an irrigation port 11 for pumping the irrigation fluid towards the handpiece 2 and an aspiration port 12 for aspirating the aspiration fluid from the eye 29. The ophthalmic surgical system 1 may also have a display device 7, which can, for example, display information for a person treating the patient.

[0057] Fig. 2 shows the ophthalmic surgical handpiece 2 in a cross-sectional view. The ophthalmic surgical handpiece 2 can have at least the following vibration-generating components: a connecting piece 70, a needle 20, and a vibration-generating device 22. The needle 20 with a needle tip 21 can be mounted on the connecting piece 70. The needle tip 21 can alternatively be referred to as a point or cutting tip. The connecting piece 70 is, for example, designed as a horn. The vibration-generating device 22 is arranged, for example, at an end of the connecting piece 70 facing away from the needle 20. It is coupled to the connecting piece 70 and can cause it to vibrate. Thus, the needle 20, and consequently the needle tip 21, is excited to a vibration, particularly longitudinal, transverse, and / or torsional, by means of the vibration-generating device 22 via the connecting piece 70.The vibration components can be arranged in a housing 25 of the handpiece 2. The ophthalmic surgical handpiece 2 can have an incision attachment 71 for the needle 20. Furthermore, a needle base 72 of the needle 20 is sketched in Fig. 2.

[0058] The case described here involves the insertion of a needle tip 21 into the patient's eye 29. For this purpose, the needle tip 21 was guided through the cornea 30 of the eye 29 and inserted into a lens 31 of the eye 29. The lens 31 is held in place in the eye 29, among other things, by a lens suspension 32 formed by zonular fibers. A vitreous body 33 located behind the lens 31 is also partially schematically depicted.

[0059] The handpiece 2 can be operated in several different operating modes. It is operated in these modes. The operating modes are a high-energy mode 42 (see reference numeral 42 in Fig. 3), a low-energy mode 44 (see reference numeral 44 in Fig. 3), and / or a bias mode. In the high-energy mode 42, the vibration components, in particular the needle tip 21, can be excited to vibrate at a frequency within a predetermined first frequency range. This results, for example, in an energy input into the eye 29 that is greater than a predetermined limit. This large energy input can be achieved, for example, by exciting the needle tip 21 to vibrate with an amplitude greater than a predetermined limit amplitude.The vibration generation device 22 is particularly designed to excite the vibration components, in particular the needle 20 with the needle tip 21, in high-energy mode 42 at least by means of a first piezoelectric element 24 of the vibration generation device 22.

[0060] In low-energy mode 44, at least the vibration components, in particular the needle tip 21, can be excited to vibrate at a frequency in a predetermined second frequency range different from the first frequency range. This results in the energy input into the eye 29 being smaller than the predetermined limit. In one example, this can result in the amplitude of the vibration being smaller than the predetermined limit amplitude. The vibration generation device 22 is specifically designed to excite the vibration components, in particular the needle 20 with the needle tip 21, in low-energy mode 44 by means of a second piezoelectric element 23 of the vibration generation device 22, which is different from the first piezoelectric element 24.

[0061] It can be provided that in high-energy mode 42, the vibration components, in particular the needle 20 with the needle tip 21, are additionally excited by means of the second piezoelectric element 23, and / or in low-energy mode 44, the vibration components, in particular the needle 20 with the needle tip 21, are additionally excited by means of the first piezoelectric element 24. The respective piezoelectric element 24, 23 can be supplied with, for example, electrical energy and / or a control signal via a connecting line 27. If the needle 20 is a hollow needle, a fluid channel can also be provided in it, which serves to aspirate the fluid from the eye 29.

[0062] A change between the high-energy mode 42 and the low-energy mode 44 can occur automatically or be manually initiated. For automatic switching, for example, a control device 26 of the handpiece 2, in particular the vibration generation unit 22, can be used. Automatic switching can occur, for example, upon detection of a frequency shift that causes the vibration of the needle tip 21 to deviate from a predetermined vibration pattern, upon occlusion of the needle tip 21 in the case of a hollow needle, upon a temperature at the needle tip 21, provided that this temperature is within a predetermined temperature range, and / or upon a cataract degree of the lens 31 of the treated eye 29, provided that this degree is within a predetermined cataract degree range.For example, the high-energy mode 42 is intended for severe damping of the needle tip 21 and / or medium to high cataract severity, but the low-energy mode 44 is intended for less severe damping and / or medium to low cataract severity.

[0063] In one example, the handpiece 2 can be operated in bias mode, in which the vibration generation device 22 is configured to apply a bias to the first piezoelectric element 24 and / or the second piezoelectric element 23 by actuating at least one piezoelectric biasing device 35. This bias allows the needle tip 21 to be excited to a predetermined vibration with less electrical energy by means of the biased piezoelectric element 24, 23 compared to the same piezoelectric element 24, 23 without the bias. The piezoelectric biasing device 35 can include at least one piezoelectric washer, which can alternatively be referred to as a piezoelectric shim. The washer can be configured to apply the bias to the respective piezoelectric element 24, 23 by changing its thickness 36.The thickness 36 can be changed, for example, by applying a predetermined electrical voltage to the washer. For example, a piezoelectric preload device 35, in particular a washer, can be provided for each of the two piezoelectric elements 24, 23.

[0064] The ophthalmic surgical handpiece 2 can further comprise at least one mechanical preloading device 37 which applies a predetermined preload to the respective piezoelectric element 24, 23. The at least one mechanical preloading device 37 can, in particular, be designed as a screw nut. At least one mechanical preloading device 37 can be provided for each of the piezoelectric elements 24, 23.

[0065] Each piezoelectric element 24, 23 can comprise several piezoelectric rings 34 arranged side by side. Here, each of the piezoelectric elements 24, 23 has, as an example, four piezoelectric rings 34. These are arranged, for example, side by side on an outer wall 39 of the connecting piece 70, where they can extend over a partial area 40 of the outer wall 39. Furthermore, more than the two piezoelectric elements 24, 23 described above can be provided. Each of the piezoelectric elements 24, 23 can have any number of piezoelectric rings.

[0066] The ophthalmic surgical handpiece 2 can have at least one spacer element 38, which is arranged, for example, between the first piezoelectric element 24 and the second piezoelectric element 23 and spatially separates them from each other. The spacer element 38 can, in particular, be designed as a sleeve that can be arranged on the outer wall 39 of the connecting piece 70.

[0067] Fig. 3 shows an example of the curve 41 of a displacement D of the needle tip 21 (y-axis) as a function of a frequency f (x-axis) at which the needle tip 21 is excited to oscillate. The displacement D is shown here in decibels referenced to 100 micrometers. The displacement given in micrometers can be converted to decibels referenced to 100 micrometers using the following formula: 20 x log (D / 100 micrometers). A displacement D of 0 dB therefore corresponds to an amplitude of 100 micrometers.

[0068] In high-energy mode 42, the needle tip 21 can be excited such that it oscillates at a first frequency 43. This first frequency 43 lies, in particular, between 36 kilohertz and 45 kilohertz. In the example outlined here, it is 43.2 kilohertz. The first frequency 43 can be a resonant frequency. In low-energy mode 44, the needle tip 21 can be excited such that it oscillates at a second frequency 45, 46, which differs from the first frequency 43 and is, in particular, an operating frequency or another resonant frequency. The second frequency 46 lies, in particular, between 50 hertz and 1 kilohertz. The second resonant frequency 45 lies, in particular, between 2 kilohertz and 10 kilohertz or, in particular, between 60 kilohertz and 80 kilohertz. In the outlined example, the second frequency 45 is, for example, 9.4 kilohertz, 65.9 kilohertz or 74.9 kilohertz.The additional frequencies 47 shown here are less suitable for operating the handpiece 2. Firstly, the frequency 47 shown here, at 30.3 Hertz, is relatively close to the preferred frequency range of the high-energy mode 42 and could potentially be confused with it during setup. Secondly, the particularly high frequency 47 of 97.7 Kilohertz is too high, as such high frequencies can result in relatively high energy transfer through mechanical components. Depending on the handpiece 2 and its geometry or dimensions, other frequency ranges may be provided for the high-energy mode 42 and / or the low-energy mode 44 compared to the frequency ranges shown in Fig. 3.

[0069] Fig. 4 shows an example of a preload adjustment process at the start of use of the handpiece 2. Phase A represents a warm-up phase, phase B an efficiency tuning phase, and phase C a power tuning phase. Four curves 60, 61, 64, 63 are sketched one above the other. The upper diagram shows the power curve 60 in the three phases A, B, C. The diagram below it shows the frequency curve 61 in the three phases A, B, C. A frequency sweep 62 with dashed lines is also shown, which, however, is intended to illustrate the prior art. Here, the curve 61 is shown according to the straight line. The diagram below it shows the longitudinal deflection 64 of the needle tip 21 in the three phases A, B, C. Here, the resonance deflection, which lies at the point 65 shown here and thus at the first frequency 43 in Fig. 3, is highlighted.The bottom diagram shows the curve 63 of a DC voltage sweep in the three phases A, B, C, which is performed here with the second piezoelectric element 23. During the DC voltage sweep, the frequency f is kept constant according to curve 61. The DC voltage sweep influences the bias voltage of the first piezoelectric element 24 and thus changes its resonance condition. Alternatively, the frequency sweep 62 and the DC voltage sweep can be performed in a two-dimensional parameter space to globally find the optimal resonance point.

[0070] Fig. 5 shows a possible control loop for the biasing mode of the handpiece 2. In a first step, a target frequency 50 can be specified. The target frequency 50 is passed to a comparator element 55, which compares a resonant frequency determined for the handpiece by a frequency determination device 54 with the target frequency 50. The comparator element 55 can be followed by a controller 51, which passes a control signal to a DC voltage source 52, which then controls either the piezoelectric element 24, 23 and / or the piezoelectric biasing device 35, which are shown here as the controlled element 53.

[0071] In general, the excitation of the piezoelectric elements 24, 23 is controlled by a common controller. This controller can be the control device 26. Depending on the change in vibration at the needle tip 21 upon contact with or penetration into the eye 29, or by a trigger mechanism activated by a user, the controller can switch between exciting the first piezoelectric element 24 and the second piezoelectric element 23, or exciting both piezoelectric elements 24, 23 simultaneously. This controlled excitation of the respective piezoelectric element 24, 23 allows for optimal vibration behavior, thereby optimizing, for example, the power flow into the eye 29 and minimizing heat dissipation to other parts of the eye 29.Furthermore, the service life of the oscillating components of the handpiece 2 can be optimized, and the power output to the needle tip 21 can be adapted, for example, to spatially heterogeneous cataract hardness by simultaneously switching on or switching between the piezoelectric elements 24, 23. For example, one of the two piezoelectric elements 24, 23 is excited with a DC voltage. This allows an optimized resonance point to be set or readjusted during operation.

[0072] The examples show a medical handpiece (handpiece 2) with a high-energy mode 42, a low-energy mode 44, and / or a bias mode. The invention relates in general to an ophthalmic surgical handpiece 2 for treating a lens 31 of an eye 29, an ophthalmic surgical system 1, and a method. The handpiece 2 comprises a connecting piece 70 to which a needle 20 with a needle tip 21 is mounted and which is coupled to a vibration-generating device 22; and the vibration-generating device 22, which can excite the needle 20 to a longitudinal vibration via the connecting piece 70. The handpiece 2 can be operated in a high-energy mode 42, in which at least by means of a first piezo element 24 the needle 20 with the needle tip 21 is excited, and in a low-energy mode 44, in which at least by means of a second piezo element 23 the needle 20 with the needle tip 21 is excited.Alternatively or additionally, the handpiece 2 can be operated in a pre-tensioning mode in which the first piezo element 24 and / or the second piezo element 23 is subjected to a pre-tension by controlling at least one piezo-based pre-tensioning device 35.

[0073] Reference symbol list

[0074] 1 system

[0075] handpiece

[0076] 3 console

[0077] 4 cassette recording area

[0078] 5 cassette

[0079] 6 Fluid pump display device

[0080] 8. Storage vessel, irrigation fluid line

[0081] 10 connecting line

[0082] 11 Irrigation side

[0083] 12 Aspiration side

[0084] 20 needles

[0085] 21 needle point

[0086] 22 Vibration generating device

[0087] 23 second piezoelectric element

[0088] 24 first piezoelectric element

[0089] 25 cases

[0090] Control device

[0091] 27 Connection

[0092] 28 Fluid channel

[0093] 29 Eye

[0094] 30 cornea

[0095] 31 lens

[0096] 32 lens suspension

[0097] 33 glass bodies

[0098] 34 Piezo ring

[0099] 35 piezo-based preload device

[0100] 36 Thickness

[0101] 37 mechanical preload device 38 spacer element

[0102] 39 Exterior wall

[0103] 40 sub-area

[0104] 41 Course 42 High-energy mode

[0105] 43 first frequency

[0106] 44 Low energy mode

[0107] 45 second frequency

[0108] 46 second frequency 47 other frequency

[0109] 50 Target frequency

[0110] 51 regulators

[0111] 52 DC voltage source

[0112] 53 controlled element 54 frequency determination device

[0113] 55 Comparison element

[0114] 60 Course

[0115] 61 Course

[0116] 62 Frequency sweep 63 Course

[0117] 64 Course

[0118] 65th position

[0119] 70 Connecting piece

[0120] 71 Incision attachment 72 Needle foot

Claims

Patent claims 1. Ophthalmic surgical handpiece (2) for treating a lens (31) of an eye (29) with at least the following vibration components that can be excited to vibration: - a connecting piece (70) to which a needle (20) with a needle tip (21) is mounted and which is coupled at one end opposite the needle (20) to a vibration generating device (22); and - the vibration generating device (22) which is designed to excite the needle (20) to vibration via the connecting piece (70); wherein the handpiece (2) is designed to: - to be operated in a high-energy mode (42) in which at least the vibration components oscillate at a frequency in a predetermined first frequency range, such that an energy input into the eye (29) is greater than a predetermined limit value, wherein the vibration generating device (22) is configured to excite the vibration components in the high-energy mode (42) at least by means of a first piezoelectric element (24) of the vibration generating device (22); and - to be operated in a low-energy mode (44) in which at least the vibration components oscillate at a frequency in a predetermined second frequency range different from the first frequency range, such that the energy input into the eye (29) is less than the predetermined limit value, wherein the vibration generation device (22) is configured to excite the vibration components in the low-energy mode (44) at least by means of a second piezoelectric element (23) of the vibration generation device (22) that is different from the first piezoelectric element (24); and / or - to be operated in a biasing mode in which the vibration generating device (22) is configured to bias the first piezoelectric element (24) and / or the second piezoelectric element (23) by controlling at least one piezoelectric biasing device (35) of the vibration generating device (22) apply such that the needle tip (21) can be excited to a predetermined oscillation with less electrical energy by means of the piezoelectric element (24, 23) applied with the pre-tension compared with the same piezoelectric element (24, 23) without the pre-tension.

2. Ophthalmic surgical handpiece (2) according to claim 1, wherein the vibration generation device (22) is operable in high energy mode (42) and low energy mode (44) and is configured to additionally excite the vibration components in high energy mode (42) by means of the second piezo element (23) and / or to additionally excite the vibration components in low energy mode (44) by means of the first piezo element (24).

3. Ophthalmic surgical handpiece (2) according to one of the preceding claims, wherein the vibration generation device (22) is operable in high-energy mode (42) and low-energy mode (44) and is configured to excite the vibration components in high-energy mode (42) such that the hollow needle tip (21) vibrates at a first frequency (43), wherein the first frequency (43) is in particular between 36 kilohertz and 45 kilohertz, and / or in low-energy mode (44) to excite the vibration components such that the needle tip (21) vibrates at a second frequency (45, 46) different from the first frequency (43), wherein the second frequency (45, 46) is in particular between 50 hertz and 1 kilohertz, between 2 kilohertz and 10 kilohertz or between 60 kilohertz and 80 kilohertz.

4. Ophthalmic surgical handpiece (2) according to one of the preceding claims, wherein the vibration generation device (22) is operable in high energy mode (42) and low energy mode (44) and the ophthalmic surgical handpiece (2) has a control device (26) configured to switch between the high energy mode (42) and the low energy mode (44) when at least one of the following conditions is met: - a frequency shift is present, due to which the vibration of the needle tip (21) deviates from a predetermined vibration behavior; - the needle tip (21) is designed as a hollow needle and an occlusion at the needle tip (21) is detected; - a temperature at the needle tip (21) lies within a specified temperature range; - the degree of cataract of the lens (31) of the eye to be treated (29) lies within a specified cataract degree range.

5. Ophthalmic surgical handpiece (2) according to one of the preceding claims, wherein the vibration generation device (22) is operable in preload mode and the at least one piezo-based preload device (35) has at least one piezo-based washer configured to apply the preload to the respective piezo element (24, 23) by changing the thickness (36) of the washer, wherein the change in thickness (36) can be predetermined by applying a predetermined electrical voltage to the washer.

6. Ophthalmic surgical handpiece (2) according to one of the preceding claims, wherein the ophthalmic surgical handpiece (2) has at least one mechanical preloading device (37) which applies a predetermined preload to the respective piezoelectric element (24, 23), wherein the at least one mechanical preloading device (37) is in particular designed as a screw nut.

7. Ophthalmic surgical handpiece (2) according to one of the preceding claims, wherein the respective piezo element (24, 23) comprises several piezo rings (34) arranged side by side in a partial area (40) of the connecting piece (70), in particular on an outer wall (39) of the connecting piece (70).

8. Ophthalmic surgical handpiece (2) according to one of the preceding claims, wherein the ophthalmic surgical handpiece (2) has at least one spacer element (38) that is positioned between the first piezoelectric element (24) and the second piezo element (23) and spatially separates them from each other, wherein the spacer element (38) is in particular designed as a sleeve which is arranged on an outer wall (39) of the connecting piece (70).

9. Ophthalmic surgical system (1) for the treatment of an eye (29), comprising at least: - an ophthalmic surgical handpiece (2) for treating a lens (31) of the eye (29) according to one of the preceding claims; and - a console (3); wherein the ophthalmic surgical handpiece (2) can at least be coupled to the console (3).

10. Method for operating an ophthalmic surgical handpiece (2) for treating a lens (31) of an eye (29), wherein the handpiece (2) comprises at least the following vibration components capable of being excited to vibration: a connecting piece (70) to which a needle (20) with a needle tip (21) is mounted and which is coupled at one end opposite the needle (20) to a vibration generating device (22), and the vibration generating device (22) which is configured to excite the vibration components to vibration via the connecting piece (70), wherein the handpiece (2): - is operable in a high-energy mode (42) in which the vibration components oscillate at a frequency within a predetermined first frequency range, such that an energy input into the eye (29) is greater than a predetermined limit value, wherein the vibration generating device (22) excites the vibration components in the high-energy mode (42) at least by means of a first piezoelectric element (24) of the vibration generating device (22); and - can be operated in a low-energy mode (44) in which the vibration components oscillate at a frequency in a predetermined second frequency range different from the first frequency range, so that the energy input into the eye (29) is less than the limit value, wherein the vibration generating device (22) excites the vibration components in low-energy mode (44) at least by means of a second piezoelectric element (23) of the vibration generating device (22) that is different from the first piezoelectric element (24); and / or - is operable in a bias mode in which the Vibration generating device (22) applies a pre-voltage to the first piezoelectric element (24) and / or the second piezoelectric element (23) by controlling at least one piezoelectric pre-voltage device (35) of the vibration generating device (22), so that the needle tip (21) can be excited to a predetermined vibration with less electrical energy by means of the piezoelectric element (24, 23) applied with the pre-voltage compared with the same piezoelectric element (24, 23) without the pre-voltage.

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