Control method and control device for generating control data for an ophthalmological laser therapy device

Abstract

The present invention relates to a control method for generating control data for an ophthalmological laser therapy device (100). The problem addressed by the present invention is to specify a method and a device for generating control data on the basis of which the laser therapy device (100) is enabled to reduce the risk of a deviation of a correction, generated according to a plan created before the surgery, from the planned correction target. The problem is solved by a control method for generating control data, which comprises receiving (S1) measurement data which characterise a state of a cornea (190) of an eye (E) immediately before the start of the planned laser therapy, determining (S2) a control variable on the basis of the measurement data and comparison data, and providing (S3) control data on the basis of the determined control variable. The problem is further solved by a corresponding control unit (K), an ophthalmological laser therapy device (100) and by a computer program product.

Description

[0001] Control procedure and control device for generating control data for an ophthalmic laser therapy device

[0002] The present invention relates to a control method for an ophthalmic laser therapy device for generating control data. The present invention further relates to a corresponding control unit, an ophthalmic laser therapy device, a computer program product with program code, and a computer-readable medium.

[0003] Refractive errors of the human eye have long been corrected with lenses in the form of eyeglasses. However, for some years now, various approaches have been developed to correct refractive errors by modifying the cornea. This modification alters the curvature of the cornea and thus the refractive power of the eye. This is typically achieved by removing (or ablating) tissue from the cornea. By removing corneal tissue from the eye, the refractive power of the cornea is altered in such a way that—taking into account the overall optical properties of the eye—the refractive error is reduced or even completely corrected (see, for example, US 6110166 A).

[0004] Carl Zeiss Meditec AG has developed a particularly gentle corneal modification procedure called SMILE (Small Incision Lenticule Extraction). In this procedure, a femtosecond laser is used to create shallow incisions in the cornea, enclosing a lenticule-shaped piece of corneal tissue. This lenticule is then removed from the cornea through a small access incision. This alters the curvature of the anterior surface (also called the front surface) of the cornea (the interface between the cornea and air). This change in curvature alters the cornea's refractive power, thereby correcting refractive errors.

[0005] To create the large incisions in the cornea, laser radiation is used to treat the eye within the tissue - i.e., below the surface. 2024P00147WG 2

[0006] The laser beam is focused in such a way that optical breakthroughs occur within the tissue. Various processes, initiated by the laser radiation, take place sequentially within the tissue. If the power density of the radiation exceeds a threshold, an optical breakthrough occurs, generating a plasma bubble within the material. This plasma bubble grows after the optical breakthrough due to expanding gases. If the optical breakthrough is not maintained, the gas generated in the plasma bubble is absorbed by the surrounding material, and the bubble disappears. However, this process takes much longer than the formation of the bubble itself. When a plasma bubble separates previously fused material layers, this is usually referred to as photodisruption. For the sake of simplicity, the processes mentioned here are summarized under the term optical breakthrough.This term encompasses not only the actual optical breakthrough but also the resulting effects within the material. If a large number of optical breakthroughs are created side by side in the fabric, a planar cut (cut surface) can be generated in this way.

[0007] A section of the cornea that delineates a lenticule typically includes a cap cut, a lenticule cut, a lateral cut, and an access cut. The cap cut (also called a flap cut) delineates the lenticule—the volume of tissue to be isolated from the cornea for removal—anteriorly, towards the front of the cornea. The lenticule cut delineates the lenticule posteriorly, towards the retina. The lateral cut (also called a side cut or lenticule side cut) delineates the lenticule laterally, opposite a principal optical axis of the eye, and extends to both the cap cut and the lenticule cut. The access cut extends to both the cap cut and the anterior surface of the cornea.Through the access incision, the isolated volume of tissue (lenticule) within the cornea can be removed. Another corneal modification procedure is laser-assisted in situ keratomileusis, also known as LASIK. In this procedure, a corneal flap is detached from the corneal surface on one side and folded back. This flap can be detached using a mechanical microkeratome or a femtosecond laser. After the flap has been detached and folded back, the LASIK procedure involves the use of an excimer laser, which ablates the corneal tissue exposed beneath the flap. This process vaporizes the corneal tissue that was originally located beneath the corneal surface. After the ablation, the corneal flap is repositioned.

[0008] Corneal modification to correct refractive errors can also be performed using PRK (photorefractive keratectomy) or LASEK (laser-assisted epithelial keratomileusis). In these procedures, the outer layer of cells (epithelium) on the corneal surface is first removed (for example, with an alcohol solution) or loosened with an alcohol solution and then moved aside. This is followed by the removal of corneal tissue with an excimer laser. Afterward, in LASEK, the epithelium is repositioned.

[0009] The aforementioned procedures for correcting refractive errors by means of corneal modification have in common that, between the start of preparation for a laser surgery and the actual application of the laser to the cornea, so much time can elapse that the patient's cornea may have changed: the corneal thickness can decrease, for example, due to dehydration, but it can also swell due to excessive moisture. Specifically, eyelid speculums (also called lid retractors or speculum oculi) and / or anesthetic eye drops are usually used immediately before the laser surgery. These prevent blinking and can thus promote corneal dehydration. It was shown that at an average rate of approximately 11 pm / min, the corneal thickness of 12 eyes decreased by approximately 55 pm in just 5 minutes due to dehydration (see H. Aurich, C. Wirbelbauer, J. Jaroszewski, C. Hartmann and DT).Pham, “Continuous measurement of corneal dehydration with online optical coherence pachymetry,” Cornea, Vol. 25, No. 2, pp. 182–184, 2006). Various medical conditions or genetic predisposition can further intensify this effect. Some time after the laser surgery, once the eyelid speculum is removed and blinking has resumed at its typical frequency, the cornea typically regains its normal hydration.

[0010] However, due to variations in corneal thickness during laser surgery, particularly if corneal hydration deviates from normal, the corneal incisions may not be created at the intended depth. For example, if the cornea is dehydrated during the procedure, the incisions for isolating a lenticule may be made at excessive depth. Furthermore, the curvature of the incisions may deviate from the planned shape. Both of these factors can result in the achieved correction differing from the intended target.

[0011] In the case of LASIK or PRK / LASEK, a deviation in corneal hydration from normal can lead to, for example, an increase in flap thickness and / or incorrect ablation, since the volume of cornea removed per laser pulse also depends on its hydration. These effects can also cause the achieved correction to deviate from the planned correction goal.

[0012] Currently, it is the responsibility of the clinic staff to minimize the time between the insertion of the lid speculum and the start of the laser treatment, or to keep the eye moist with drops in order to counteract dehydration.

[0013] The object of the present invention is therefore to provide a method for an ophthalmic laser therapy device that reduces the risk of deviation of a correction produced according to a plan created before the procedure from the planned correction target. Furthermore, it is an object of the invention to provide a corresponding control unit. 2024P00147WG 5

[0014] According to the invention, the problem is solved by the features of the independent claims. Preferred embodiments and configurations are the subject of the dependent claims.

[0015] A first aspect of the invention relates to a control method for an ophthalmic laser therapy device for generating control data to monitor the planning of laser therapy performed by the ophthalmic laser therapy device. Before a laser surgical procedure to correct a refractive error, the eye to be corrected is typically characterized using measurement techniques. Based on these preoperative measurements, a correction plan is created; such a plan is also called a treatment plan. Based on this plan, control data is generated for controlling the ophthalmic laser therapy device, which—when executed by the laser therapy device—creates incisions in the cornea or ablates corneal tissue to achieve the planned correction of the refractive error.The control data generated in the control procedure thus serve to ensure, even before the actual laser surgery (i.e., the cornea being exposed to laser radiation), that potential deviations from the correction to be carried out according to plan are detected in order to be able to intervene if necessary.

[0016] The control procedure, which can be implemented in a control unit, includes the step of receiving measurement data that characterizes the condition of an eye's cornea. This reception can occur via a first interface of the control unit, through which the measurement data is provided. This first interface can be a connector or socket for a cable (e.g., USB, FireWire, RS232, CAN bus, Ethernet, etc.); it can also be a wireless interface such as a WLAN, UMTS, or Bluetooth receiver.

[0017] The measurement data can be a single value (a scalar) or a multitude of values ​​(for example, in the form of a vector or a matrix). Furthermore, the measurement data can have been taken at a single location on the cornea or at multiple locations. The received measurement data preferably characterizes a condition of the cornea, describing a property of the corneal volume. Examples include corneal thickness (e.g., at the corneal apex or at multiple locations) or corneal moisture (as opposed to corneal surface curvature, which describes a property of the corneal surface).

[0018] The received measurement data characterize the condition of the cornea of ​​the eye immediately before the start of the planned laser surgery procedure. The start of the laser surgery procedure is defined as the point in time at which the first laser beam is directed into or onto the cornea of ​​the eye to cause photodisruption or ablation. "Immediately before" is defined as a maximum of 2 minutes before the start, preferably a maximum of 1 minute, 30 seconds, or 15 seconds. Preferably, at the time of measurement, the eye to be treated is fully prepared for the start of the laser surgery procedure, i.e., for example, that the lid speculum is in place and / or anesthetic eye drops have been administered. The received measurement data preferably describe the condition of the cornea immediately before the operator (e.g.,the surgeon, doctor, operator, user) of the ophthalmic laser therapy device causes the first laser beam to be delivered into or onto the cornea.

[0019] Furthermore, the control procedure includes the step of determining a control parameter based on the measurement data and comparison data. The comparison data may consist of further measurement data (such as some or all of the aforementioned preoperative measurements on which the correction plan was based); it may also consist of typical "mean" data or measurement data taken from or derived from a (normative) database. Preferably, the comparison data and the received measurement data have the same data type or characterize the same corneal condition. For example, both the received measurement data and the comparison data may be a 2024P00147WQ 7

[0020] This could involve corneal thickness or corneal moisture. Determining the control parameter can be based on a comparison of the received measurement data with the reference data (e.g., the received measurement data is greater than, equal to, or less than the reference data). The control parameter can also be determined by calculating the difference or quotient between the received measurement data and the reference data.

[0021] The comparison data may already be present in the process (for example, as a database to which the process has access); the comparison data may also be received in a further process step.

[0022] The control variable determined in this process step characterizes a difference between the received measurement data and the comparison data.

[0023] The determination can be performed in a computing unit of the control unit, which is configured to receive the measurement data, for example, via the aforementioned first interface. The computing unit can be a computer comprising a processor and memory. The computing unit can include a processor or processing element, such as a CPU (central processing unit) (optionally in the form of a microprocessor), a GPU (graphics processing unit), a TPU (tensor processing unit), and / or an FPGA (field programmable gate array). The computing unit can include computer memory, optionally a semiconductor memory chip. The processor can be configured to execute a computer program. The computer program can be stored in the computer memory.

[0024] The control procedure further includes the step of providing control data based on the specified control variable. This involves calculating the control data using the specified control variable. The calculation can, for example, be performed in the control unit's calculation unit described above. However, it is also possible to use a separate calculation unit, which is linked to the calculation unit described above (2024P00147WG 8).

[0025] is connected via an interface through which the control variable can be provided to the further calculation device.

[0026] Control data refers to data that has a format suitable for receipt and processing by the ophthalmic laser therapy device. This control data is designed to enable the ophthalmic laser therapy device to reduce the risk of deviation between the generated correction (using the control data according to the plan) and the planned correction target. For example, the control data may include:

[0027] - A recommendation to release or abort,

[0028] - a probability of an expected deviation (above a defined threshold) of the achieved correction (using the control data according to plan) from the planned correction target,

[0029] - Suggestions for adjusting the tax data, and / or

[0030] - Information about a time.

[0031] The time information describes, for example, how much time remains until the laser surgery procedure should be completed. This time information can be formatted, for example, as a timer and / or as a target time.

[0032] The provision of the control data can be done via the first interface described above; however, it can also be done via a second interface different from the first interface.

[0033] The control method according to the invention advantageously allows it to be checked (immediately) before the actual laser surgical procedure whether it can be expected that – using the control data according to the plan – the targeted correction goal can be achieved or not. This enables the operator of the ophthalmic laser therapy device and / or the ophthalmic laser therapy device itself to intervene to make corrections. The control method thus has a safety feature. 2024P00147WG 9

[0034] It should be noted that the control procedure for generating the control data is carried out before the actual laser surgical procedure, i.e., before a laser device of the ophthalmic laser therapy device emits a laser beam into or onto the cornea of ​​the eye to be treated.

[0035] According to an advantageous embodiment of the control procedure, the control data represent authorization for laser therapy to be performed by the ophthalmic laser therapy device if a limit value for the control parameter is met. Conversely, the control data do not represent authorization for laser therapy to be performed by the ophthalmic laser therapy device if the limit value for the control parameter is exceeded. The latter case corresponds to a recommendation to terminate the procedure or a warning.

[0036] If the device is cleared, the planned correction can continue without interruption. If it is not cleared, or if the operator receives a termination recommendation (or warning), the ophthalmic laser therapy device is enabled to stop the laser radiation being applied to the eye being corrected. The ophthalmic laser therapy device can be configured to provide the operator with relevant information. Additionally, it can provide recommendations for action, such as checking and / or moisturizing the eye and / or adjusting the control settings. After taking these actions, the control procedure can be repeated to obtain clearance to perform ophthalmic laser therapy (or to receive another termination recommendation or warning).

[0037] This design enables monitoring of the subsequent implementation of the therapy, which reduces the risk of deviation from the targeted correction goal within a short time.

[0038] According to a further embodiment, the control procedure includes the step of receiving time data that characterizes the point in time of manipulation of the cornea of ​​the eye immediately before the start of the planned laser therapy and / or that characterizes the point in time of acquisition of the measurement data. Reception can occur via the aforementioned first interface. However, the control unit can also have a further interface designed to receive the time data.

[0039] Corneal manipulation is a step that directly or indirectly alters the condition of the cornea—particularly a condition that describes a property of corneal volume. It specifically refers to a step that affects corneal thickness and / or corneal moisture. Direct corneal manipulation occurs, for example, through corneal moistening. Indirect corneal manipulation occurs, for example, through the insertion of an eyelid speculum, as this prevents normal blinking and thus alters corneal moisture. The application of anesthetic eye drops can also be a manipulation, as they likewise affect blinking and therefore corneal moisture. However, the application of laser radiation is not considered corneal manipulation within the scope of this application.Rather, the manipulation of the cornea according to the claim is a manipulation that takes place immediately before the start of laser therapy.

[0040] The received time data thus describe a point in time from which a change in corneal thickness and / or corneal moisture is to be expected – such as the time at which the lid speculum was inserted or the eye was moistened. Additionally or alternatively, the time data describes the point in time at which the received measurement data were acquired.

[0041] The aforementioned timing data can be obtained, for example, using a camera set up to record an image or video of the eye being treated, and a downstream camera evaluation unit. The camera evaluation unit is configured to analyze the images or videos in such a way as to detect the time of insertion of the eyelid speculum, anesthesia of the eye, and / or lubrication. The analysis in the camera evaluation unit can be performed using conventional (not based on artificial) methods.

[0042] The devices should primarily utilize AI (AI) and / or AI-based algorithms. Such algorithms are known in the prior art. The camera and / or camera evaluation unit can be part of the control unit; they can also be part of the ophthalmic laser therapy device. They can also be part of or constitute another device. The aforementioned time data can also be provided manually by the user. For this purpose, the control unit can include an input device. The input device can be, for example, a keyboard (for entering a time) or a button with which the operator marks the time when the corneal manipulation took place. The input device can also be part of the ophthalmic laser therapy device.

[0043] Furthermore, the control procedure is characterized by the fact that the control variable is additionally determined based on the received time data. The determination is thus based on both the received time data and the received measurement data. The control variable then preferably characterizes an available time for the planned laser therapy (time window). For this purpose, the received time data is compared, for example, with the current time. Advantageously, the control unit has a timer (such as a clock) that allows the current time to be determined and compared with the received time data. When determining the control variable, a model is preferably used that determines the time window based on the received measurement data as well as the received time data. A model can, for example, be based on findings regarding the average rate of change in corneal thickness over time (cf. H. Aurich, C.Whirlbauer, J. Jaroszewski, C. Hartmann and DT Pham, “Continuous measurement of corneal dehydration with online optical coherence pachymetry,” Cornea, Vol. 25, No. 2, pp. 182-184, 2006).

[0044] This design enables monitoring of the subsequent therapy, reducing the risk of deviation from the targeted correction goal on a patient-specific basis. 2024P00147WG 12

[0045] In a further development of the control procedure, the control data includes a value representing the control variable. By providing the control variable itself, the ophthalmic laser therapy device is enabled to perform more complex and differentiated reactions that go beyond simply issuing a release or a termination recommendation.

[0046] If, for example, the control parameter is a deviation (e.g., in percent) between the currently measured corneal thickness (immediately before the laser surgery) and the corneal thickness obtained preoperatively for determining correction planning and the derived control data, then the control data (especially the data from a scan unit) can be adjusted to achieve the desired correction despite the thickness deviation during therapy, once normal corneal hydration has been restored. For instance, the control data for the scan unit, which can change the focus of the laser beam axially (along an optical axis of the ophthalmic laser therapy device), could be adjusted according to the (percentage) deviation.

[0047] According to a further embodiment, the control procedure is characterized in that the control data includes control data which, when executed by the ophthalmic laser therapy device, performs an adapted therapy taking into account the specific control parameter.

[0048] Preferably, this involves control data for the laser device (which can provide pulsed laser radiation) and / or a scanning device (which can deflect the laser beam in two or three spatial directions).

[0049] An adapted therapy means that the parameters (or control data) used to perform the adapted therapy differ from the parameters of the original plan. In particular, the locations in the cornea and / or the laser parameters (e.g., laser power) for creating incisions or performing ablation differ. 2024P00147WG 13

[0050] In this configuration, the control procedure directly provides adjusted control data. The adjustment of the control data occurs directly within the control procedure (and not subsequently). Depending on the technical design of the computing device used for the control procedure, this configuration can lead to a result more quickly than, for example, adjusting the control data in the control unit. This can reduce the overall time required for the therapy (i.e., for preparation, the actual laser surgery procedure, and aftercare) and thus reduce the burden on the patient.

[0051] In a further embodiment, the control procedure is characterized in that the comparison data includes previous measurement data that characterize the condition of the cornea at an earlier time point. This earlier time point is prior to the time at which the received measurement data were acquired, which characterize the condition of the cornea immediately before the start of the planned laser therapy. Preferably, the comparison data and the received measurement data are of the same data type, i.e., they characterize the same condition of the cornea. This simplifies the determination of the control parameter and the control data, allowing the control data to be provided as quickly as possible (with less computational effort than with different data types), thus minimizing the burden on the patient.

[0052] To determine the adapted control data, a corneal dehydration / rehydration model can be used, which takes into account a moisture gradient within the cornea for the calculations of the control data. With the adapted control data, the laser surgery can then be performed in a partially dehydrated cornea in order to achieve the desired refractive correction after rehydration.

[0053] According to a further development of the above-mentioned design, the control procedure is characterized by the fact that the earlier time is at least one hour before the creation of the received measurement data, which2024P00147WG 14

[0054] The condition of the cornea of ​​the eye should be characterized immediately before the start of the planned laser therapy, preferably at least two, five, or ten hours. These earlier measurements may be the preoperative data on which the treatment plan was based. This data is usually collected several days or weeks before the planned procedure. Additionally or alternatively, these measurements characterize a state in which the cornea exhibits normal hydration and is not compressed. Normal hydration is defined as corneal hydration present at a typical blink rate and without medication or eyelid speculum. Such data are particularly well-suited as a baseline, as they accurately reflect the expected corneal hydration after therapy.

[0055] According to an alternative further development of the above-mentioned design, the control procedure is characterized in that the earlier time point is a time point immediately before contact of the cornea of ​​the eye with a contact element of the ophthalmic laser therapy device.

[0056] During refractive correction, precise positioning of the laser beam within the cornea is of paramount importance. Movement of the eye being treated must therefore be avoided as much as possible. A contact element (also called a contact lens or contact interface) can be used for this purpose. One side of the contact element is brought into contact with the eye (or rather, its cornea) to perform the therapy. The contact element optically couples the eye to the ophthalmic laser therapy device; simultaneously, the eye is fixed in place. This fixation can lead to corneal compression. If the corneal thickness is measured immediately before contact with the contact element, the comparative data provides information about the condition (thickness) of the uncompressed cornea."Immediately before" here also means a time of a maximum of 2 minutes, preferably a maximum of 1 minute, a maximum of 30 seconds or 15 seconds. 2024P00147WG 15.

[0057] In a further embodiment, the control procedure is characterized by the fact that the measurement data represents the thickness of the cornea. Such a corneal thickness measurement is also known as pachymetry. It is possible that the measurement data may include further data characterizing the condition of the cornea immediately before the planned laser therapy begins. Typically, however, one type of measurement (here, the thickness measurement) is sufficient.

[0058] Direct pachymetry measurement can be performed, for example, using optical coherence tomography (OCT), confocal (multiphoton) microscopy, or ultrasound or terahertz measurement, as shown, for instance, in US 2021259540 A1. Preoperative measurements typically also include pachymetry values, which form the basis for a treatment plan. As a control parameter, the deviation of the received pachymetry value from a preoperative value can be determined. If the deviation is too large (greater than a predefined limit), control data can be provided, representing a warning to the operator and / or a recommendation to terminate the procedure and / or an order to prevent the laser surgery from being performed according to the plan by the ophthalmic laser therapy device.Additionally or alternatively, control data can be calculated taking into account the new, currently available pachymetry value and taking into account the preoperative pachymetry value (which shows no altered hydration).

[0059] The use of a pachymetry value as received measurement data is particularly advantageous, as changes in corneal hydration can be derived particularly well from this value.

[0060] In a further development of the above-described embodiment, the control procedure is characterized in that the comparison data represent previous measurement data of the corneal thickness of the eye at an earlier time. Thus, the previous measurement data and the received measurement-2024P00147WG 16

[0061] Data characterizing the condition of the cornea immediately before the planned laser therapy are recorded using the same data type. This simplifies (and speeds up) the determination of the control parameter (and control data), thereby reducing the burden on the patient. Since corneal thickness is generally constant over time under normal hydration, it is not critical whether the measurement of the control data was taken minutes or weeks before the laser surgery, as long as it characterizes the cornea under normal hydration.

[0062] According to a further development of the aforementioned method, the control procedure is characterized by the fact that the received measurement data are recorded after the eye comes into contact with a contact element of the ophthalmic laser therapy device. The received measurement data thus provide information about the condition (thickness) of the cornea compressed by fixation on the contact element. Additionally, the earlier measurement data (the comparison data) represent the condition of the cornea before contact with the contact element. This can be a point in time immediately before contact; however, it can also be a point in time at least one hour (or two hours, five hours, or ten hours) before the start of the planned laser therapy.

[0063] Furthermore, the development of the control procedure is characterized by the fact that determining the control parameter includes calculating the elasticity of the cornea. Information about the thickness of the cornea before and after contact with the contact element allows for the determination of corneal elasticity or compression.

[0064] In this configuration, for example, atypical corneal elasticity can be advantageously detected. If, for instance, the control parameter detects that a limit value has been exceeded, information can be provided via the control data that prevents potentially incorrect therapy (e.g., through a discontinuation recommendation or new control data). 2024P00147WG 17

[0065] The elasticity or compression of the cornea can be calculated particularly reliably if the received measurement data are recorded immediately after the eye comes into contact with the contact element (preferably less than 3 minutes, 2 minutes, or 1 minute), and if, in addition, the comparison data were obtained immediately before the eye came into contact with the contact element.

[0066] In a further embodiment, the control procedure is characterized by the fact that the measurement data represent the moisture level of the cornea. Corneal moisture can be measured directly or indirectly. Indirect measurement is possible, for example, by determining the refractive index or by measuring the tear film breakup time. Additionally or alternatively, the moisture level can be determined by evaluating camera images of the process of the eye docking (making contact) with any existing contact elements; for this purpose, a fluid meniscus is analyzed with regard to its shape and movement during docking.

[0067] Typical values ​​for corneal moisture can be used as comparative data (for example, from a database). However, if the patient is known to have dry eyes, appropriately adjusted values ​​from a database can be used. Alternatively, measurements of the moisture of the eye to be treated (or its cornea) taken before the start of therapy preparation can be used as comparative data. These measurements should be taken before the insertion of a lid speculum or the administration of anesthetic eye drops. The comparative data would then include previous measurements characterizing the condition of the cornea at an earlier time, with the earlier measurements representing the corneal moisture level at that time.

[0068] In this configuration, a patient-specific risk for an expected deviation from the targeted correction goal can be identified particularly well. 2024P00147WG 18

[0069] According to a further embodiment, the control procedure is characterized in that the laser therapy performed by the ophthalmic laser therapy device involves creating a cut surface within the cornea of ​​the eye. This can involve one or more cut surfaces for delineating a lenticule (such as a lenticule incision, cap incision, or lateral incision) within the cornea and / or for creating a pocket within the cornea and / or for creating an access point to the cornea (access incision). The control procedure can therefore be used to monitor the planning of a lenticule extraction. Additionally or alternatively, the control procedure can be used to monitor the planning of incisions suitable for the implantation of an implant (inlays, e.g., artificial or biological corneal tissue).This can involve implantation into the remaining volume after lenticule extraction or implantation into a pocket (without prior removal of part of the cornea).

[0070] For the aforementioned feasible laser therapies, careful planning is particularly important to ensure that the incisions to be made in the cornea are created at the planned depth and with the planned radii of curvature. Unlike, for example, in ablative procedures (such as LASIK, where the ablation rate can be monitored and adjusted intraoperatively), it is very difficult to adjust the control parameters during treatment when creating an incision within the cornea of ​​the eye, as the creation of the incision occurs within a few seconds and should ideally not be interrupted.

[0071] A second aspect of the invention relates to a control unit for generating control data for an ophthalmic laser therapy device. The control unit comprises a computing unit configured to execute a control procedure according to one of the embodiments described above. The computing unit can include a processor or a processing element, e.g., a CPU (optionally in the form of a microprocessor), 2024P00147WG 19

[0072] A GPU, a TPU, and / or an FPGA. The computing device may include computer memory, optionally a semiconductor memory chip. The processor may be configured to execute a computer program. The computer program may be stored in the computer memory.

[0073] The computing device is further equipped to receive the measurement data that characterize the condition of the cornea of ​​the eye and to provide the control data.

[0074] To receive measurement data characterizing the condition of the cornea of ​​the eye and to forward this data to the processing unit, the control unit also includes a first interface connected to the processing unit. This allows the processing unit (via the first interface) to receive the measurement data for determining the control parameter.

[0075] Furthermore, the control unit has a second interface connected to the processing unit, through which the generated control data can be provided – for example, to an ophthalmic laser therapy device, where the generated control data can be further processed. The second interface can be identical to the first.

[0076] The interfaces of the control unit can be designed as described above.

[0077] A third aspect of the invention relates to an ophthalmic laser therapy device. According to the invention, this device comprises a control unit as described above. Furthermore, the laser therapy device has a control unit that is connected to the control unit via the second interface for receiving the control data. The control data generated in the control unit can thus be received by the control unit via the second interface, which can be configured as described above, so that it can be further processed by the laser therapy device. Based on the provided control data, for example, the planned laser surgical procedure can be authorized (the treatment plan, which has been "translated" into control data, can be executed).

[0078] Alternatively, the execution of the control data can be stopped if the control data does not indicate approval for execution and / or if the control data indicates a recommendation to abort.

[0079] Additionally or alternatively, new control data can be calculated based on the control data from the ophthalmic laser therapy device (for example, in the control unit) if the control data has provided corresponding information (for example, the control parameter).

[0080] Additionally or alternatively, the control data provided in the control data can replace the control data already present in the control unit, so that the new control data can be executed by the ophthalmic laser therapy device.

[0081] Additionally or alternatively, based on time information provided in the control data, the user of the ophthalmic laser therapy device can be shown how much time remains until the laser surgical procedure should be completed. This display can be visual or audible. For this purpose, the ophthalmic laser therapy device can have a display device or a speaker. The display device can, for example, show the remaining time as a timer (in the form of numbers as a countdown or graphically).

[0082] The control unit's control data can form a control data set. The control unit is connected to the ophthalmic laser therapy device devices described below in order to control them. This is typically done using signal data transmitted from the control unit to the various devices via signal data lines or wirelessly. The signal data is adapted based on the control data and / or, if necessary, forwarded to the devices. 2024P00147WG 21

[0083] The control unit can typically access all controllable devices of the ophthalmic laser therapy device. The control unit can be a single unit or a multi-part system, and it can communicate with the controllable devices of the ophthalmic laser therapy device via wired or wireless communication channels.

[0084] The ophthalmic laser therapy device further comprises a laser device for providing a laser beam, preferably a pulsed laser beam.

[0085] This can involve femtosecond or picosecond pulses whose focused laser beam is capable of severing the tissue of a patient's eye via optical breakthrough due to non-linear absorption. The laser device can, for example, include a femtosecond laser or a picosecond laser.

[0086] A femtosecond laser, for example, has a wavelength in the range of 750 nm to 1100 nm. However, the use of femtosecond lasers at other wavelengths is also conceivable in principle. The pulse duration of a femtosecond or picosecond laser that can be used here can be selected from a pulse duration range of 50 fs to 5 ps. The pulse energy of a femtosecond or picosecond laser that can be used here is advantageously in the pulse energy range of 20 nJ to 2 pJ. A pulse energy of approximately 130 nJ is particularly preferred. Typically, a laser device can provide laser pulses with a laser pulse frequency of up to 50 MHz. However, the laser device can be configured to reduce the laser pulse frequency.

[0087] The laser device may also include an excimer laser whose focused laser beam is capable of ablating tissue in a patient's eye. The wavelength used for therapy is typically in the ultraviolet spectral range. 2024P00147WG 22

[0088] The ophthalmic laser therapy device further comprises a focusing device for concentrating the laser beam into a focus for cutting or ablating the cornea. The focusing device is designed to focus the laser beam in a working area (typically in the tissue or on the surface of the tissue of the patient's eye) so that an optical breakthrough or ablation is achieved at the focus point. The focusing device is preferably designed to take into account the optical properties of the patient's eye (such as the radii of curvature of the optically effective interfaces – for example, at the cornea – or the refractive indices of the tissue through which the beam passes). Furthermore, the focusing device can be configured to create a focus of the laser beam in the tissue of the patient's eye, with a contact lens positioned in the beam path upstream of the patient's eye.

[0089] In addition, the ophthalmic laser therapy device includes a scanning device for moving the focus of the laser beam in the working area.

[0090] The scanning device of the ophthalmic laser therapy unit allows the focus of the laser beam to be shifted or scanned within the tissue of the eye. Scanning the laser beam should be possible without restriction in all three spatial directions: x, y, z. Accordingly, the scanning device should be designed to perform lateral scans in the x and y directions as well as z-scans along the optical axis of the pulsed laser beam. The volume accessible by the scanning device is also referred to as the working area.

[0091] The ophthalmic laser therapy device according to the invention makes it possible to use the control data generated by the control unit in such a way that the risk of a deviation of a generated correction (when using the originally planned control data) from the planned correction target is reduced.

[0092] According to one embodiment, the ophthalmic laser therapy device further includes a measuring device for recording the measurement data that characterize the condition of the cornea of ​​the eye. The measuring device can be integrated into a 2024P00147WG 23

[0093] The measuring device is integrated into a housing that encloses the other components of the ophthalmic laser therapy device. It can also be spatially separated from the rest of the device and connected via a wired or wireless data link. The measuring device has an interface that is connected to the first interface of the control unit and through which the measurement data can be made available.

[0094] The measuring device can be an OCT device (optical coherence tomography device), a confocal (multiphoton) microscope, an ultrasound and / or terahertz measuring device. Additionally or alternatively, the measuring device can be designed to measure the moisture content of the eye directly or indirectly.

[0095] If the measuring device is part of the ophthalmic laser therapy device, the measuring device can advantageously also be used to monitor or check a docking process between the contact element that may be present and the eye.

[0096] A fourth aspect of the invention relates to a computer program product with program code. When this program code is loaded into a computing unit of a control unit as described above, it executes a control procedure as described above.

[0097] The described computer program product with program code can also be configured to execute a control procedure as described above when it is loaded into an ophthalmic laser therapy device (or its computing unit) as described above.

[0098] A fifth aspect of the invention relates to a computer-readable medium. According to the invention, a computer program product as described above is stored on the computer-readable medium.

[0099] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0100] The invention is explained in more detail below with reference to exemplary embodiments and illustrations, which also reveal essential features of the invention. The illustrations show:

[0101] - Fig. 1 shows a schematic of an embodiment of an ophthalmological laser therapy device with a control unit according to the invention;

[0102] - Fig. 2 shows an example of a control method according to the invention.

[0103] Figure 1 schematically depicts an embodiment of an ophthalmic laser therapy device 100 (enclosed by a dashed box). During operation of the ophthalmic laser therapy device 100, a laser device 110 emits a pulsed laser beam 115. The laser beam 115 is deflected axially (in the z-direction) by a scanning device 130 and laterally (in the x- and y-directions) by another scanning device 135. A focusing device 120 concentrates the pulsed laser beam 115 into a focus 125 (when the laser therapy device 100 is used to correct the refraction of a human eye E) in the cornea 190 of the eye E to be corrected. The present embodiment features a fixation of the eye E relative to the ophthalmic laser therapy device 100 by means of a contact element 150.If the contact element 150 exhibits a refractive effect after docking with the eye E, this is taken into account in the design of the focusing device 120. Using the scanning devices 130 and 135, the focus 125 of the pulsed laser beam 115 can be shifted in three spatial dimensions. The resulting accessible volume is the working area 160, which is shown as a dotted line.

[0104] The presence of a contact element 150 is not absolutely necessary.

[0105] During operation, the laser device 110 and the scanning devices 130 and 135 are controlled fully automatically via signal data transmitted from a control unit 140 to the respective devices 110, 130, and 135. This is indicated by arrows pointing from the control unit 140 to the devices 110, 130, and 135, respectively. The control unit 140 ensures appropriately synchronized operation of the laser device 110 and the three-dimensional scanning devices 130 and 135. The focusing device 120 can also be controlled by the control unit 140. The signal data can be transmitted via signal data lines or wirelessly. The signal lines are represented as solid arrows pointing from the control unit 140 to the devices 110, 130, and 135. The signal data required for operation are determined in the control unit 140 based on control data.

[0106] During a check (immediately) before the actual laser surgery procedure using the ophthalmic laser therapy device 100, the control unit K receives measurement data via a first interface P1. This data was acquired from the cornea 190 of eye E using the measuring device M and characterizes the condition of the cornea 190 immediately before the planned laser therapy begins. The transmission path between the measuring device M and the control unit K is shown as a solid line in Fig. 1. The measurement data can also be transmitted using memory chips (e.g., via USB or memory stick), magnetic storage media (e.g., floppy disks), wirelessly via radio (e.g., WLAN, UMTS, Bluetooth), or via wired connections (e.g., USB, FireWire, RS232, CAN bus, Ethernet, etc.). As an alternative to direct communication, the control unit K can also be positioned spatially separate from the measuring device M, and a corresponding data transmission channel can be provided.

[0107] The control unit K has a computing unit C, which is a computer with a processor and memory. Furthermore, the control unit K has a second interface P2, through which control data can be provided to the control unit 140.

[0108] In the illustrated embodiment, the measurement data is provided by a measuring device M. In this example, this is an OCT system. The ability of the measuring device M to acquire the measurement data is represented in Fig. 1 by a dashed double arrow. The processing unit C of the control unit K is configured to receive measurement data, determine a control variable, and generate and provide control data. The control data enables the ophthalmic laser therapy device to detect early on the risk that therapy using the original treatment plan would lead to a deviation from the targeted correction. Furthermore, the ophthalmic laser therapy device is enabled to counteract this by preventing the start of the laser therapy procedure and / or by adjusting the treatment plan (by adjusting the control data).

[0109] The control unit K does not have to be part of the ophthalmic laser therapy device. Alternatively, it can be a separate unit that can be connected to the laser therapy device via the aforementioned interfaces. The control unit K can have a measuring device; it can also be additionally or alternatively connected via interface P1 to a measuring device that is neither part of the control unit K nor of the laser therapy device.

[0110] Figure 2 schematically illustrates an example of a control procedure for an ophthalmic laser therapy device. The individual procedure steps are shown schematically in the blocks labeled S1 to S3.

[0111] Procedure step S1 involves receiving measurement data that characterizes the condition of the cornea of ​​an eye immediately before the planned laser therapy begins. In particular, the measurement data characterizes a condition that describes a property of the corneal volume.

[0112] Process step S2 is performed after process step S1. Here, a control variable is determined based on the measurement data and comparison data. The comparison data can be parts of a database. It may also have been received previously in another (not shown) process step. Process step S3 is again performed after process step S2. In step S3, control data is provided based on the determined control variable. This requires first determining the control data.

[0113] The procedure shown in Fig. 2 can be carried out in the control unit K shown in Fig. 1. In this case, the result of the control is made available to the control unit 140 via interface P2. The control unit 140, in turn, is configured to perform various actions based on the control data, such as enabling or disabling the laser therapy procedure and / or adjusting control data.

[0114] It should be noted once again that the control unit K performs the procedure for generating the control data before the actual laser surgical procedure, i.e., before the laser device emits a laser beam into the cornea of ​​the eye to be treated.

[0115] The features of the invention mentioned above and described in various embodiments can be used not only in the exemplary combinations given, but also in other combinations or alone, without leaving the scope of the present invention.

[0116] A description of a device relating to process characteristics applies analogously to the corresponding process with respect to these characteristics, while process characteristics represent corresponding functional characteristics of the described device.

Claims

2024P00147WG 28 Patent claims 1. Control procedure for an ophthalmic laser therapy device (100) for generating control data for controlling a planning of a laser therapy executable by the ophthalmic laser therapy device (100), wherein the control procedure comprises the following steps: - Receiving (S1) measurement data that characterizes the condition of the cornea (190) of an eye (E) immediately before the start of the planned laser therapy, in particular a condition that describes a property of the corneal volume, - Determining (S2) a control parameter based on the measurement data and comparison data, - Providing (S3) control data based on the specified control variable.

2. Control method according to claim 1, characterized in that the control data represent a release to perform the laser therapy by the ophthalmic laser therapy device (100) if a limit value for the control parameter is adhered to, and that the control data do not represent a release to perform the laser therapy by the ophthalmic laser therapy device (100) if the limit value for the control parameter is exceeded.

3. Control method according to one of the aforementioned claims, characterized in that, - that the control procedure continues to include the step of receiving time data that characterize a time of manipulation of the cornea (190) of the eye (E) immediately before the start of the planned laser therapy and / or that characterize the time of obtaining the measurement data, and - that the determination of the control variable is additionally based on the received time data.

4. Control method according to one of the preceding claims, characterized in that the control data includes a value that represents the control variable.

5. Control method according to one of the preceding claims, characterized in that the control data includes control data which, when executed by the ophthalmic laser therapy device (100), performs an adapted therapy taking into account the determined control parameter.

6. Control method according to one of claims 1 to 5, characterized in that the comparison data include previous measurement data that characterize the condition of the cornea (190) of the eye (E) at an earlier time.

7. Control method according to claim 6 characterized in that the earlier time point is at least one hour before the creation of the received measurement data, which characterize the state of the cornea (190) of the eye (E) immediately before the start of the planned laser therapy, preferably at least two hours, five hours or ten hours and / or that the earlier time point corresponds to a time point at which the cornea (190) has normal hydration.

8. Control method according to claim 6 characterized in that the earlier time point is a time point immediately before contact of the cornea (190) of the eye (E) with a contact element (150) of the ophthalmic laser therapy device (100).

9. Control method according to any of the preceding claims, characterized in that the measurement data represent a thickness of the cornea (190) of the eye (E).

10. Control method according to claim 9, characterized in that the earlier measurement data represent a thickness of the cornea (190) of the eye (E) at an earlier time.

11. Control method according to claim 10, characterized in that, - that the received measurement data are recorded after contact of the eye (E) with a contact element (150) of the ophthalmic laser therapy device (100), and - that determining (S2) the control parameter includes calculating the elasticity of the cornea.

12. Control method according to one of the preceding claims, characterized in that the measurement data represent a moisture level of the cornea (190) of the eye (E).

13. Control method according to one of claims 6 to 12, characterized in that the previous measurement data represent a moisture level of the cornea (190) of the eye (E) at an earlier time.

14. Control method according to one of claims 1 to 13, characterized in that the laser therapy that can be carried out by the ophthalmological laser therapy device (100) is a creation of a cut surface within the cornea (190) of the eye (E).

15. Control unit (K) for generating control data for an ophthalmic laser therapy device (100), comprising - a computing device (C) that is designed to, to carry out a control method according to one of claims 1 to 14, to receive the measurement data that characterize the condition of the cornea (190) of the eye (E), and to provide the control data, a first interface (P1) for receiving the measurement data and forwarding it to the calculation unit (C), and a second interface (P2) for providing the control data.

16. Ophthalmic laser therapy device (100), comprising - a control unit (K) according to claim 15, - a control unit (140) for controlling the ophthalmic laser therapy device (100), wherein the control unit (140) is connected to the control unit (K) via the second interface (P2) for receiving the control data, - a laser device (110) for providing a laser beam (115), - a focusing device (120) for focusing the laser beam (115) at a focus (125) in a working area (160), - a scanning device (130, 135) for moving the focus (125) of the laser beam (115) in the working area (160).

17. Ophthalmological laser therapy device (100) according to claim 16, further comprising a measuring device (M) for recording the measurement data that characterize the condition of the cornea (190) of the eye (E).

18. Computer program product comprising program code which, when executed on a control unit (K) according to claim 15, is configured to execute a method according to any one of claims 1 to 14.

19. Computer-readable medium on which the computer program product according to claim 18 is stored.

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