DEVICE FOR REFRACTIVE SURGERY, IN PARTICULAR FOR KERATOPLASTY

Description

[0001] The present invention relates to devices for refractive surgery, in particular for keratoplasty, for example a sutureless lamellar intrastromal keratoplasty (sIALK).

[0002] Devices and methods for refractive surgery, particularly for keratoplasty, as described, for example, in DE 10 2007 019 815 A1 and WO 2008 / 131888 A1, have so far assumed that a piece of tissue is always removed from the recipient eye during the course of treatment. To date, the sIALK procedure has been described in such a way that a resection is always required because only then does a depression in the stromal bed (vacancy) arise, which facilitates the correct implantation of an implant or transplant. A vacancy has inherent disadvantages, namely the surgical stress associated with its creation and the tissue loss. However, the advantages often outweigh these: the obtaining of biopsy material and the simplified positioning of the implant.

[0003] In a specific embodiment, in addition to improving the spectacle visual acuity (CDVA), the uncorrected visual acuity (UDVA) is also improved. Thus, spectacle correction is performed simultaneously. This concept has also been partially formulated in DE 10 2007 019 815 A1 and WO 2008 / 131888 A1.

[0004] Shaping can be performed in various ways during the manufacture of the implant, particularly a tissue implant. US 2009 / 0247999 A1 discloses a system for post-processing the implant in the patient's eye. Another system for producing implants is known from US 2014 / 264980 A1.

[0005] One possible approach involves imprinting the target geometry onto an implant blank using laser processing. This is particularly interesting for refractive surgery, because the refractive laser systems commonly used in this field can be adapted for such procedures with minimal effort. This would allow the medical practitioner to perform the patient-specific adjustment of the implant in the clinic, eliminating the need for a tissue bank or other facility. Such an approach would therefore have logistical advantages and also reduce some risks for patients.

[0006] However, simply transferring the procedure for PRK or LASIK treatment to the problem of implant manufacturing cannot reliably achieve the required processing precision. In contrast to the usual use in shaping stromal corneal tissue for the subtractive correction of a visual defect, in which tissue layers up to 13 µm thick are removed per diopter correction, thus rarely resulting in a maximum ablation of more than 100 µm, an ablation of more than 100 µm layer thickness is not uncommon in implant manufacturing. Achieving absolute precision in the micrometer range with such a large ablation is more difficult than meeting the high relative accuracy requirements of a PRK correction, especially since the properties of the implant material can be subject to greater fluctuations than is the case with stromal tissue during PRK or LASIK treatment.

[0007] In addition to shaping the implant within the tissue correction zone, which can be natural donor corneal tissue or artificial tissue with identical properties to natural corneal tissue, the geometry of its edge requires particularly high precision. In this periphery of the implant, referred to as the edge, a precise fit into an existing vacancy in the tissue is often necessary. (An accuracy of at least 10 µm, but preferably 5 µm or less, is desirable. Ideally, an adjustment can be achieved to within 1 µm.) One aspect of this problem is that the surgeon must not damage the edge of the implant during the entire process, for example, when separating the tissue to be transplanted from the surrounding tissue of the donor eye, or when separating the material from unnecessary parts. These process steps naturally require manual microsurgical work with surgical instruments.

[0008] The object of the invention is to describe devices for the production and implantation of a lamella of a tissue or material for the purpose of correcting a corneal geometry with the highest precision, thus improving the state of the art. The goal of the correction is, in particular, to restore a normal corneal geometry with improved optical function of the cornea compared to the state of the art.

[0009] The invention is divided into various measures or features, all of which serve the purpose of improving the above-mentioned devices for refractive surgery, in particular for keratoplasty, and are ultimately used to achieve a common goal: the production and implantation of a tissue or material for the purpose of correcting a corneal geometry with improved precision compared to the prior art.

[0010] The optimized target geometry sought here by the devices according to the invention described is intended to improve the optical function of the cornea and at the same time to create or restore an approximately normal corneal geometry.

[0011] The measures or features are intended to lead to an improved shape of the implant (to avoid cavities) and improved processing accuracy. Thus, the object of the invention is, in particular, to optimally prepare the periphery of the (natural or artificial) tissue or material for manual processing steps, or to facilitate or, where possible, replace critical processing steps through laser processing, as well as to describe measures for improving the accuracy of laser processing and reducing stress on or damage to the implant.

[0012] The invention is defined in the independent claim. The dependent claims relate to preferred developments.

[0013] Before describing these groups in detail, however, some terms should be clarified: "Implant" is tissue, here in particular (possibly modified) corneal tissue from a donor eye or an artificial tissue or material of non-human origin with identical properties. "Transplant" is tissue of human origin. (The distinction based on the presence of living cells may be relevant for regulatory purposes, but will be disregarded here.) "Implantation" refers to the insertion of both an implant and a transplant. "Blank" refers to a blank. This blank can be an implant or transplant, which generally has a three-dimensionally curved, round basic shape with a diameter of approximately 5-9 mm and a thickness between 10 µm and 400 µm, with a maximum thickness of 500 µm. The thickness profile of this spherical shell or spherical shell-like structure, with a radius of curvature between 5 mm and infinity, is not yet adapted to the recipient eye. A lamella is created from the blank through processing."Lamella" refers to an implant or transplant made from a blank and given a thickness profile specifically adapted to the recipient eye. The lamella is therefore the final product, ready for insertion into a prepared incision in the cornea of ​​a recipient eye or into a vacancy (structure) defined by this incision. "Vacancy" refers to the structure in the stromal bed created by resection (i.e., removal of a corneal volume). The vacancy can also be referred to as a resection cavity, although it practically never actually exists as a hollow space in the cornea. Instead, the overlying lamella always adheres closely to the stromal bed, and any resulting hollow space is quickly filled with tissue fluid.

[0014] The object is achieved by a planning device according to the invention for generating control data for a treatment system for refractive surgery, in particular for keratoplasty, which comprises a first laser device and at least one characterization device, wherein the first laser device, preferably a femtosecond laser device, can be controlled by means of the control data to create at least one cutting surface in a cornea of ​​an eye. Due to the tasks that this first laser device has to fulfill, it is necessary for a processing laser beam emitted by it to penetrate into ocular tissue, in particular into the cornea of ​​an eye, and to create a cutting surface within the tissue. Laser devices whose processing laser beam can create photodisruption of the tissue at a focus in the tissue are typically suitable for this purpose.

[0015] The planning facility also features: an interface for supplying first measurement data on parameters of the cornea to the characterization device, preferably an OCT (optical coherence tomography) device, an interface for supplying second measurement data or model data of a lamella that can be inserted into the cornea after the cutting surface has been created, an interface for supplying control data to the first laser device, and calculation means for defining the at least one cutting surface in the cornea using the first measurement data and the second measurement data or model data, wherein the calculation means generate a control data set for controlling the first laser device, wherein the at least one cutting surface can be generated by the first laser device using the control data set.

[0016] The at least one cut surface to be created in the cornea of ​​one eye, the recipient eye, can be simple in nature and really only have a curved surface into which the lamella can be "inserted." However, it can also be circumscribed—by several cut surfaces—a volume that can be removed in order to later insert the lamella into the resulting vacancy.

[0017] The planning device is further configured to generate control data for a second laser device of the treatment system, preferably an excimer laser device, for processing a blank into a patient-specifically shaped lamella and has an interface for transmitting control data to the second laser device. The first laser device, second laser device, and characterization device each have a device coordinate system, and they are or can be coupled to one another by registering the device coordinate systems, and the supplied second measurement data or model data of the lamella can be registered to these device coordinate systems. Due to the tasks that this second laser device must fulfill, it is necessary for a processing laser beam emitted by it to be able to ablate eye tissue, in particular the cornea of ​​an eye, from its surface into the tissue.Although it is of course also possible to work with a processing laser beam that creates photodisruption in the tissue, laser devices whose processing laser beam can process the tissue by ablation are particularly suitable for this purpose.

[0018] The blank is also processed, for example, with an excimer laser device, in such a way that the laser device's processing profile (fluence or laser shot distribution as a function of location) is precisely "placed" on the blank. This typically requires centering with an accuracy of approximately 100 µm. This transforms the blank into a patient-specific lamella, the implantation of which achieves the intended regularization of pachymetry and, if necessary, refraction adjustment.

[0019] Holistic surgical planning is crucial. The planning device executes a planning procedure encoded in planning software within the planning device. The measured corneal tomography data and, if necessary, other biometric parameters (e.g., radius of curvature, refraction) of the eye to be treated serve as input for the planning software. The planning device, in which the planning software is encoded, can be an integral part of the treatment system or can be located in parallel or alternatively on one or more computers spatially separate from the treatment system.

[0020] The user is shown the patient's spatially resolved pachymetry and at least one other location marker (e.g., center of the photopic pupil or corneal sight center, vertex position, limbus). The software also has information from the typical pachy map of a healthy eye. By correctly subtracting the existing pachy map from a typical pachy map, the software automatically calculates a difference map. The user decides whether the procedure should be performed with or without a vacancy, defines the treatment zone (usually round) by specifying, for example, the lamella center and lamella diameter, as well as other geometric parameters such as the diameter and edge thickness of the vacancy, the edge thickness of the lamella, and the depth of the pocket incision below the corneal surface. The software can also suggest or determine some or all of these parameters automatically.The software then generates control data for both the first laser device, preferably a femtosecond laser device, and for the second laser device, preferably the excimer laser device.

[0021] Depending on the condition of the blank from which the patient-specific lamella is to be machined, it may be of great advantage if the planning device according to the invention is further configured to generate control data for the first laser device or a further laser device, likewise preferably a femtosecond laser device, whose device coordinate system is likewise coupled to the aforementioned device coordinate systems by means of registration, for producing or pre-processing the blank, wherein the blank can be produced from a natural donor cornea or from an artificial tissue or can be pre-processed therein by producing one or more cutting surfaces in the donor cornea or the artificial tissue by means of the first laser device or the further laser device.

[0022] This tax data can and should include registration information, in particular: 1. The control data for, for example, a femtosecond laser device as a pre-processing additional laser device for creating a blank in a starting material, possibly in the cornea of ​​a donor eye or an artificial tissue. If the starting material is already available in a suitable configuration, this step can be replaced by inputting data about the geometry of the material. 2. The control data for, for example, an excimer laser device as a post-processing second laser device for processing the blank into a lamella. 3. The control data for creating at least one cutting surface, for example a pocket cut or a vacancy in the recipient eye for receiving the lamella, for, for example, a femtosecond laser device as the first laser device.

[0023] A preferred embodiment of the planning device according to the invention is configured to generate control data for a temperature regime for maintaining a temperature below a maximum temperature for processing the blank into a lamella using the second laser device. Processing the blank into a lamella by ablation using this second laser device generally leads to heating of the tissue being processed due to the high energy input. However, to ensure precise structuring, the processing temperature of the tissue should not fluctuate, but rather be kept constant at a low temperature.

[0024] In the invention, the blank is actively cooled before and / or during processing with the second laser device, usually an excimer laser device. In a special variant of the invention, the cooling takes place below 10 °C. In another variant of the invention, the cooling takes place below the freezing point of the blank. The processing waste products are actively removed by means of a controlled air flow. In one variant of the invention, the air flow is actively controlled with regard to temperature and / or humidity. In one variant of the invention, cooling takes place to the dew point of the air in the air flow. In another variant of the invention, a technical gas (e.g. nitrogen) is used instead of air. In a further variant of the invention, the processing is monitored continuously or cyclically. Monitored parameters include, for example, surface temperature, removal volume, material thickness, surface topography, axial and lateral position of the blank.In one embodiment of the invention, the monitoring parameters are used to control the removal process.

[0025] An important consideration in the planning (and subsequent execution) of the creation of a patient-specific lamella with the highest precision concerns the provision of different zones of the blank and the subsequent lamella.

[0026] The planning device is configured to determine a substantially annular transition zone at the edge of the lamella, within which the edge thickness gradually transitions into a patient-specific thickness profile, and furthermore, control data is generated such that no processing of the edge of the lamella is carried out by the second laser device, wherein the second laser device for processing the blank to form the patient-specifically shaped lamella has a holder on which the blank can be fixed during processing by the second laser device.

[0027] When using a holder for processing the blank by means of the second laser device, the planning device is configured to generate control data for active cooling of the holder.

[0028] If the blank does not already have the appropriate dimensions for processing by means of the second laser device, then in a first advantageous variant the planning device is configured to define cutting surfaces in the donor cornea or the artificial tissue, to generate control data and to transmit these to the first laser device or the further laser device, with which a blank can be generated which is defined by a correction zone located in the center of the blank, a transition zone arranged around this and an edge zone arranged around this, which is provided for later separation before insertion of the lamella into the cornea of ​​the eye, and this blank can be removed from the donor cornea or the artificial tissue and fixed on a holder for processing with the second laser device.

[0029] In a second advantageous variant, the planning device is configured to define cutting surfaces in the donor cornea or the artificial tissue, to generate control data and to transmit these to the first laser device or the further laser device, with which a blank can be generated which is defined by a correction zone located in the center of the blank and a transition zone arranged around this, and this blank can be further processed in the original donor cornea or the artificial tissue with the second laser device.

[0030] In this second variant, it is also of further advantage if the planning device is configured to define cutting surfaces in the donor cornea or the artificial tissue, to generate control data and to transmit these to the first laser device or the further laser device, with which a blank can be generated which also has an edge zone arranged around the transition zone, which is intended for later separation before insertion of the lamella into the cornea of ​​the eye.

[0031] Typical sizes of the corresponding zones are: For the diameter of the correction zone: 3 mm to 8 mm. For the width of the transition zone (radial): at least 10 µm, preferably between 50 µm and 2 mm. For the width of the edge zone: 0 to 1 mm. For the edge thickness: 1 µm to 50 µm. The edge thickness is the thickness to be achieved, particularly in the outer annular 10 µm edge area of ​​the lamella.

[0032] The correction zone, transition zone, and peripheral zone are usually circular or annular. However, depending on the patient's specific circumstances, an elliptical or irregular shape is also possible. This can also be used to ensure the correct angular positioning of the lamella in the cornea.

[0033] It should be noted that there is currently no technology for creating a defined edge geometry for a patient-specifically shaped lamella. The femtosecond laser cuts used in the experimental procedure to create the approximately cylindrical blank (which, strictly speaking, describes the cap of a spherical shell) and the subsequent excimer laser processing to create a patient-specifically shaped lamella cannot yet produce a precise edge geometry. It can be assumed that – without the special measures described here – the edge thickness alone could randomly deviate by up to 30 µm or up to 100% from the target value. An edge zone according to the invention for later separation is also advantageous for this reason, for example.

[0034] The Zernike polynomials up to the 6th order used for patient-specific adjustment using an excimer laser device as a second laser device represent a significant limitation for the procedure. Although a 10th-order Zernike decomposition is already available in a topography-guided treatment using an excimer laser device, such as the MEL, this treatment method has not yet been applied ex vivo and is not accessible using the current procedure. Therefore, there is currently no other proven technology for controlling an excimer laser device during ex vivo treatment of a lamella.

[0035] Although the goal of ex vivo corneal shaping with an excimer laser was already formulated in the late 1980s, and there was even a practical attempt at implementing it (P. Homolka et al., The Excimer Laser Corneal Shaping (ELCS) System. Electrical Engineering and Information Technology, 117th year (2000)), this approach did not establish itself in clinical practice. The reason for this failure lay, on the one hand, in the immature excimer laser technology, and, on the other hand, in the fact that modern diagnostic options such as high-resolution OCT devices did not yet exist. In addition, only mechanical microkeratomes were available for producing blanks, whose processing accuracy was an order of magnitude lower than today's femtosecond laser systems. Thus, in addition to the roughness of the transplants of approximately 10 µm caused by the excimer technology, there was also uncertainty about the exact initial shape of the processed donor cornea.The resulting lack of accuracy prevented the practical application of the resulting transplants.

[0036] Currently, sIALK uses a lamella with an edge thickness of at least 30 µm. This is sensible in terms of the mechanical strength and manipulability of the lamella, but despite the vacancy, it leads to the formation of an annular cavity at the interface between the stroma, lamella, and cap. While a cavity fills with tissue fluid, it is unphysiological and should be avoided whenever possible. Therefore, there is no current technology for creating a specific edge geometry for the lamella.

[0037] A precise geometry is difficult to produce with an excimer laser device if the spatial frequencies are high compared to the beam diameter. The production of a simple cylindrical blank with a femtosecond laser device already demonstrates that it is fundamentally possible to produce precise edges with a femtosecond laser device. Therefore, a combination of processing steps with a femtosecond laser device as the pre-processing second laser device and an excimer laser device as the post-processing second laser device is proposed. However, the processing principles described here, which must therefore be planned accordingly and implemented in control data, must be observed.

[0038] The planning device for generating control data for a treatment system for refractive surgery, in particular for keratoplasty, is, for example, particularly configured to generate the control data for the second laser device in such a way that a defined edge geometry is achieved for the patient-specifically shaped lamella, wherein in the case of a pocket incision, and thus without creating a vacancy, the edge thickness is a maximum of 30µm, preferably between 5µm and 15µm, or in the case of a removal of a corneal volume and thus the creation of a vacancy, the edge thickness of the lamella is adapted to the vacancy geometry.

[0039] It is advantageously further configured to determine a substantially annular transition zone at the edge of the lamella, within which the edge thickness gradually transitions into a patient-specific thickness profile, and the control data are generated in such a way that no processing of the edge of the lamella takes place by the second laser device.

[0040] The edge of the lamella should therefore essentially be created according to the specifications during the production of the blank, for example by means of a femtosecond laser device as the pre-processing first or further laser device, while the actual processing / individualization of the lamella takes place before implantation into a recipient eye, for example by means of an excimer laser device as the post-processing second laser device.

[0041] When viewed in the axial direction, the implant has a preferably round central correction zone. In this zone, it is shaped to achieve the desired correction, for example, of a corneal thickness profile, topography, or wavefront, as closely as possible. The correction zone is surrounded by an annular transition zone, which serves to achieve a smooth transition in shape from the edge of the correction zone to the marginal zone. This zone, also annular, extends to the outer edge of the implant with as constant a height (thickness) as possible. It is of course also possible to omit this marginal zone, although this would negate the associated advantage. The purpose of the marginal zone is to avoid or at least reduce the effect of a centering error during sequential laser processing on the outer edge thickness of the implant.Another purpose of an (extensive) marginal zone is to protect the nearer marginal zone of an (almost finished) lamella until its implantation, as explained below.

[0042] It should be noted that the measures for a defined edge of the lamella and a temperature regime are particularly effective when the device coordinate systems of the first laser device, the characterization device, and the second laser device are linked via the planning device by means of registration, and the supplied second measurement data of the lamella can be clearly registered to the device coordinate systems. However, even without such coupling and registration, the measures for a defined edge of the lamella and a temperature regime during processing contribute to improved precision compared to the state of the art and, in particular, to the restoration of a normal corneal geometry with improved optical function of the cornea compared to the state of the art.

[0043] As already described, an annular transition zone is provided at the edge, the radial width of which is at least 10 µm, preferably between 50 µm and 2 mm, particularly preferably between 50 µm and 500 µm. Within this transition zone, the edge thickness is gradually converted into the patient-specific thickness profile. In the simplest case, this is achieved by a linear connection from the edge thickness D(r=r_max, Phi) to D(r=r_max-edge width, Phi). Further configurations will be obvious to the person skilled in the art; smoothing in Phi is also possible.

[0044] The edge thickness and the profile within the transition zone are achieved, for example, by the interaction of a femtosecond laser device as a pre-processing first or further laser device and an excimer laser device as a post-processing second laser device. In particular, in the invention, the excimer processing is carried out in such a way that no excimer ablation occurs on the edge of the blank. This is because, on the one hand, the edge thickness precisely generated with the femtosecond laser device is to be prevented from being altered by the excimer laser device. On the other hand, if the blank is fixed to a holder for processing by the excimer laser device, ablation of the blank holder must not occur, as this could contaminate the lamella.In order to further improve this aspect, in one variant the transition zone is generated entirely or partially by the femtosecond laser device as a pre-processing first or further laser device, for example by generating a conical basic geometry of the edge zone of the blank.

[0045] The control of an excimer laser device during ex vivo processing of a lamella is currently performed using a shot pattern that decomposes the Zernike expansion of the difference profile into individual ablation volumes. Currently, this expansion is only performed up to the 6th order of the polynomial. However, expansion beyond the 6th order is useful in these ex vivo processing operations to create finer structures. However, such expansion is not mandatory. Instead, the difference profile can be directly decomposed into individual ablation volumes (shot decomposition). In any case, it is crucial to perform processing such that the temperature of the blank does not exceed 40°C. For this purpose, the shot distribution and laser frequency of the scanning spot laser are adjusted accordingly.

[0046] Furthermore, the following should be noted regarding the state of the art, its problems, and the resulting inventive measures: The improvement in spectacle visual acuity (CDVA) associated with regularizing corneal thickness is already a good result for the patient. In principle, refractive correction treatment is also possible to achieve good uncorrected visual acuity (UCVA), but photorefractive keratectomy (PRK) would always involve the loss of Bowman's membrane, which is a medically questionable option in a biomechanically unstable eye. Laser in situ keratomileusis (LASIK) is not feasible due to the even greater biomechanical implications, and femtosecond lenticule extraction (small incision lenticule extraction, SMILE) would be virtually impossible surgically.An anterior chamber lens would be conceivable, but it represents a high risk in such a patient, as does an intraocular lens (IOL), which in this case would replace a non-opaque lens (clear lens exchange).

[0047] As long as one only aims to regularize corneal thickness (pachymetry), one achieves a state in which the patient's eye has good visual acuity with the help of a visual aid (glasses, contact lenses). If one strives for an even better state, for example, where good visual acuity can be achieved without glasses correction, this requires additional measures. Some basic principles for solving this problem have already been formulated in DE 10 2007 019 815 A1 and WO 2008 / 131888 A1, but no concrete or even advantageous embodiments have been disclosed to date.

[0048] Therefore, an advantageous planning device is configured to generate the control data for the second laser device in such a way that a refractive power and / or an astigmatism is impressed on the blank.

[0049] For a more precise interaction between the second laser device and the first or further laser device which was used to prepare the blank, a particularly advantageous planning device according to the invention is set up to define the position of calibration marks in the transition zone and / or the edge zone and to generate control data for the first laser device or the further laser device with which these calibration marks can be introduced during processing with the first laser device or the further laser device, wherein the calibration marks are defined in such a way that they can be used as a single or multiple orientation during processing of the blank by means of the second laser device.

[0050] In particular, it is helpful if the planning device according to the invention defines the calibration marks in such a way that they are arranged several times above one another and / or offset from one another and / or at different heights in the blank to be processed by the second laser device.

[0051] As an optional step according to the invention when cutting the blank in the donor cornea or the artificial tissue, for example by means of a femtosecond laser device, the introduction of calibration cuts is possible; calibration cuts in an excavation volume, which will be described below, are particularly advantageous.

[0052] As a further optional cut when processing with, for example, an ablating excimer laser device as a second laser device, processing can be interrupted, followed by an option to continue after visual inspection by the user. In this case, the user checks in particular whether one or more of the calibration marks have already been hit by the excimer treatment and decides accordingly whether to continue ablation. This process can also be automated using appropriate image recording and processing equipment, with this automation being carried out by a controller with appropriate software.

[0053] In general, treatment with the ablating excimer laser can be carried out in different phases, for example a first phase for removing the epithelium and a second phase for treating the stromal tissue.

[0054] Specifically, the calibration marks are introduced into the excavation volume, for example, as shown in some embodiments. If this is done in one operation with the creation of the other cutting surface, for example using a femtosecond laser device as the first or subsequent laser device, these calibration marks can be positioned very precisely with respect to the other cutting surfaces. An accuracy of better than 1 µm both axially and laterally is achievable. If the excimer ablation then reaches such a calibration mark during processing of the blank with, for example, an excimer laser device as the second laser device, which remains in the tissue for some time as a cutting surface filled with gas bubbles, a very characteristic change in the optical appearance of the respective calibration mark becomes apparent.In this way, an optimized superposition of the two laser processing steps can be achieved through expert geometric design of calibration marks and ablation profile, particularly in the excavation volume, which, for example, allows a precise edge thickness to be produced with little effort.

[0055] As already indicated, it is further advantageous if a planning device is configured to define a processing profile for the second laser device and to determine the control data in such a way that the profile of the correction zone located in the center of the blank and the transition zone arranged around it can be generated by means of the second laser device and an excavation can be generated in the edge zone arranged around this transition zone. for removing a lamella cut from the donor cornea or the artificial tissue, or for further processing of the blank on a holder in such a way that the holder cannot be hit by a processing laser beam of the second laser device.

[0056] The creation of an excavation during the process for manufacturing the implant in the form of a patient-specific lamella is an important part of the invention. Excavation is the creation of a normally annular cavity around the outer periphery of the implant. This trench-shaped cavity serves to facilitate the surgeon's exposure of the implant during its separation or, in the case of an already exposed implant, to gently remove unnecessary material from the periphery of the implant. This prevents damage to the extremely fine marginal structure of the material before the lamella is inserted into a corresponding cut surface or structure in the cornea of ​​a recipient eye. In The illustrations of the working examples further illustrate some of the characteristic features of an excavation.

[0057] Typical values ​​for the width of an excavation (radial) are: 500 µm to 3 mm.

[0058] The diameter of any additional excavation cut should be at least 100 µm larger than the diameter of the actual implant, i.e. the final lamella.

[0059] In this context, it should also be mentioned, in order to give a real order of magnitude, that for the generation of the calibration marks described above, calibration sections are created in one to one hundred areas.

[0060] Furthermore, it is advantageous if the planning device according to the invention is configured to take into account, for the generation of the control data, a defined initial hydration state of the blank or the lamella ex vivo and the change in the hydration state of the lamella during or after the implantation, preferably by means of a constant expansion factor.

[0061] The problem of varying hydration is already known in corneal transplantation and can be mitigated by specific treatment of the grafts. However, it is occurring in this form for the first time in connection with sILAK, because until now, corneas have not been shaped ex vivo, for example, with an excimer laser device. In addition to swelling and shrinkage, the ablation efficiency of the excimer laser device is also affected by hydration.

[0062] When analyzing the previous approach, it became apparent that the variability of the material, particularly its hydration state, can be the source of significant errors. This was previously unclear and requires appropriate measures to ultimately be able to more precisely predict the geometry of the lamella in the recipient cornea, especially its thickness.

[0063] An additional possibility for improved control of the hydration state is the use of an artificial tissue material with well-defined parameters, from which the lamella to be implanted can then be carved out in a more controlled manner using the second laser device - as a replacement for a natural transplant material.

[0064] The blank or the lamella can also be colored with a dye for better handling, which gradually disappears after the lamella is implanted.

[0065] The object is further achieved by a treatment system according to the invention for refractive surgery, in particular for keratoplasty, which a first laser device for generating at least one cut surface in the cornea of ​​an eye, preferably a femtosecond laser device; a second laser device for processing a blank to create a patient-specifically shaped lamella, preferably an excimer laser device; at least one characterization device, preferably an OCT device; and a planning device according to the invention as described here. A treatment system according to the invention is advantageous, which has a further laser device for generating or pre-processing the blank, preferably a femtosecond laser device.

[0066] In the embodiment of the treatment system according to the invention, the second laser device contains a holder for fixing the blank during processing.

[0067] A particular embodiment of the treatment system according to the invention comprises a temperature control device, preferably such that a temperature of the blank can be lowered so that the blank can be processed in the frozen state.

[0068] The blank can then be cooled for processing. The reduced temperature leads to more precise processing during processing by reducing drying out and / or reducing temperature-induced material changes. The latter is particularly important when processing is carried out at a high laser frequency and a correspondingly rapid and large amount of energy is introduced into the blank. This energy input is not always limited to the immediate interaction zone of the laser radiation with the material, but can also include the area surrounding the interaction zone through heat transfer and heat conduction. Since biotechnologically produced (artificial) materials in particular sometimes react sensitively to increases in temperature, i.e., undergo adverse changes, cooling the blank can provide a remedy in one embodiment of the treatment system according to the invention and of a method according to the invention.

[0069] In a preferred embodiment, the temperature of the blank, especially a blank that is mounted on a holder for processing, is lowered to approximately the ambient dew point. This means, for example, that at a room temperature of 20°C and 50% humidity, a surface temperature of approximately 9°C is set.

[0070] In a particularly preferred embodiment, the temperature of the blank on the holder is lowered to such an extent that it freezes. Such a reduction in the temperature of the blank below its freezing point can be achieved by using a suitably cold holder, even in normal room air. Laser processing then takes place on the frozen blank. The temperature of the blank can, for example, be lowered to below 0°C, below -5°C or below -10°C. The advantage of a very low temperature is that the interaction of the laser radiation with non-ablated material is reduced. Condensation or frosting of the material is minimized by a fast process (e.g. complete laser processing in less than 1 minute) or compensated for by an appropriately designed ablation process.

[0071] In a specific treatment system according to the invention, its temperature control device has at least one of the following configurations: active electrical cooling using a Peltier element, active cooling using an introduced coolant, active cooling by an air flow, passive cooling by pre-cooling the holder with or without the blank fixed to it, a chamber separated from the environment for processing the blank.

[0072] The holder can therefore be equipped with a cooling mechanism for cooling purposes. This could be, for example, active electrical cooling using a Peltier element. Active cooling using an introduced coolant (e.g., nitrogen, glycerol, ethanol) or passive pre-cooling in a suitably cold environment (e.g., a refrigerator) is also conceivable. Cooling can be controlled, with the holder's temperature or the temperature of the blank being monitored in a suitable design.

[0073] Instead of normal room air (23°C, 50% relative humidity), the blank can also be exposed to an air stream, which, in addition to the usual effect of removing debris, also influences the temperature of the blank. This is achieved by adjusting the temperature and / or humidity. Alternatively, a protective gas can be used instead of room air. To further improve this method, the blank can be processed in a chamber separated from the ambient air.

[0074] The following values ​​can be used as guidelines for specific processing of the blank on a holder in the second laser device, in particular an excimer laser device: For frost-free operation, the temperature of the holder should be approximately 1°C to 20°C. For "frost operation," the temperature of the holder should be approximately -30°C to -1°C. A further advantage is a treatment system according to the invention that has a device for monitoring the temperature of the blank and / or the holder during blank processing.

[0075] Furthermore, as background information, a planning method is described which realizes the generation of control data for a treatment system for refractive surgery, in particular for keratoplasty, according to a coding of the described planning device.

[0076] Also as background information and not as part of the claimed invention, a method of refractive surgery, in particular keratoplasty, is described in which at least one incision surface is created in the cornea of ​​an eye, a lamella for insertion into the cornea of ​​a (recipient) eye is planned by means of the described planning method, produced with the aid of the generated control data and inserted into the at least one incision surface, optionally also into a vacancy created by the incision surface formation, in the cornea of ​​the eye.

[0077] One of the following process variants can be used to produce the lamella. Variant 1: 1. Cutting the blank in a donor cornea or artificial tissue using a first or further laser device, in particular a femtosecond laser device (also called a fs laser keratome). 2. Processing the blank in the donor cornea or artificial tissue using a second laser device, in particular an excimer laser device, thereby creating a correction zone, a transition zone, and a marginal zone, and, if necessary, introducing an excavation to expose the implant (i.e., the almost finished lamella). 3. Resection of the implant from the donor cornea or artificial tissue. Variant 2: 1. Cutting the blank in a donor cornea or artificial tissue using a first or further laser device, in particular a femtosecond laser device. 2. Resection of the blank from the donor cornea or artificial tissue and positioning it on a holder. 3.Processing the blank on the holder with a second laser device, in particular an excimer laser device, creating the correction zone, the transition zone, and the marginal zone, and if necessary, introducing an excavation. 4. Optional: Separating the implant (i.e., ultimately the patient-specific lamella) from the remnants of the blank. Variant 3: 1. Positioning the blank (made from donor corneal material or artificial tissue material) on a holder. 2. Optional: Starting cooling of the holder. 3. Processing the blank on the holder with a second laser device, in particular an excimer laser device, and optionally with a first or further laser device, in particular a femtosecond laser device (fs laser keratome), creating the correction zone, the transition zone, and the marginal zone. Introduction of an excavation. 4. Optional: Separating the implant from the holder after heating the holder. Variant 4: 1.Carry out one of the variants 1 to 3 2. Separation of the implant from the holder 3. Flipping (i.e. turning inside out) the implant (a spherical shell-shaped volume can be "flipped" / turned inside out) 4. Positioning of the implant on the holder, with the previous upper side now at the bottom 5. Repeat one of the variants 1 to 3 .

[0078] The present invention will now be explained using exemplary embodiments. It shows: the Fig. 1a the diagram of a preferred first treatment system according to the invention with a first planning device according to the invention, which does not reflect the exact physical conditions. Fig. 1b the scheme of a preferred second treatment system according to the invention with a second planning device according to the invention, the Fig. 1c the scheme of a preferred third treatment system according to the invention with a third planning device according to the invention. Fig. 2a bis 2f various processing stages as well as processing variants of a blank in a donor cornea or an artificial tissue for a process of producing an implant / a patient-specific lamella, such as can be achieved with the aid of the planning device according to the invention - for the basic variant of processing the blank up to the complete production of the patient-specific lamella within the donor cornea or the artificial tissue. Fig. 3a bis 3f various processing stages as well as processing variants of a blank in a donor cornea or an artificial tissue for a process of producing an implant / a patient-specific lamella, such as can be achieved with the aid of the planning device according to the invention - for the basic variant of further processing of the blank by means of the second laser device, here an excimer laser device, such that the blank is removed from the donor cornea or the artificial tissue and fixed on a holder. Fig. 4a bis 4c an implant after processing with the laser devices of the treatment system according to the invention and before its introduction into a cut surface of the cornea of ​​a recipient eye.

[0079] In all Fig. 1a bis 1c The treatment system 1 comprises a planning device 2, a characterization device 4, which is configured to generate measurement data on parameters of the cornea 20 of an eye using an examination radiation 8, a first laser device 3, which here is a femtosecond laser device and which is configured to generate a vacancy or, as shown here, a pocket incision 21 in the cornea 20 of a recipient eye by means of a focused femtosecond laser beam 9 (the direction of incidence of the beam is not shown here - however, the person skilled in the art will know the optical structure of corresponding devices).

[0080] All characterization and laser devices of the treatment system 1 contain interfaces 5 to the planning device 2.

[0081] The Fig 1a and 1bfurther comprise a pretreatment further laser device 6, which is also a femtosecond laser device, wherein the first femtosecond laser device 3 and the pretreatment further femtosecond laser device can be one and the same device or two different laser devices. The pretreatment further laser device cuts a blank 23 from the cornea of ​​a donor eye 22 with a focused femtosecond laser beam 10. The Figuren 1a bis 1c further comprise a second post-treatment laser device, here an excimer laser device 7, which uses an excimer laser radiation 11 to work out the lamella 24 to be implanted from the blank 23, which is then ultimately implanted in the pocket 21 of the cornea of ​​the recipient eye 20.

[0082] The planning device 2 is configured to couple the device coordinate systems of the involved laser devices 3, 6, 7 and characterization devices 4 by means of registration and to clearly register the supplied measurement data of the lamella 23 to be implanted to the device coordinate systems.

[0083] While in the Fig. 1a First, the pocket cut 21 is created in the cornea of ​​the recipient eye 20, and only then the blank 23 is created in the donor eye and removed from it, in order to subsequently form it into the lamella 24 as it should preferably be handled, takes place in the Fig. 1b First, the blank 23 is completely processed into the lamella 24. Only then is a pocket incision 21 made in the cornea of ​​the recipient eye 20 to prepare for implantation.

[0084] In the Fig. 1c Again, standardized blanks 23 (preferably made of a synthetic fabric material) are used, which are then simply reworked to form lamellas 24. Also shown here, however, is the fixation of the blank 23 on a holder 25 during its processing using the Exminer laser device 7 as a second laser device. The holder is cooled during the blank processing.

[0085] The Fig. 2a bis 2f show various processing stages as well as processing variants of a blank 23 in a donor cornea or an artificial tissue for a process of producing an implant / a patient-specific lamella 24, such as can be achieved with the aid of the planning device 2 according to the invention - for the basic variant of processing the blank 23 up to the production of the patient-specific lamella 24 within the donor cornea or the artificial tissue.

[0086] In the Fig. 2a A donor cornea is shown with its individual layers: the epithelial layer 101, the Bowman's membrane 102, and the corneal stroma 103. In addition, the cuts that fundamentally separate the blank 23 from the donor cornea are shown: the lamellar cut 104 and the side cut 105.

[0087] In the Fig. 2b Furthermore, the implant 106 to be created in the form of the patient-specific lamella 24 and the resulting ablation volume 107, which is to be ablated with the second laser device 7, are shown. Also shown is the excavation 108, which will later serve to simplify the separation of the implant 106 from the donor cornea (or an artificial tissue). Visible in the Fig. 2b are also the two outer boundaries of the correction zone 109, 110, as well as the upper outer boundary of the implant 111, which represents the intersection point of the edge cut 105 and the final implant top.

[0088] In the Fig. 2c is in addition to the Fig. 2a und 2b The outer boundary of the transition zone 112, 113 is shown in the areas, sections and markings mentioned.

[0089] The Fig. 2d shows in addition to the already in the Fig. 2a bis 2c Calibration marks 114 are placed in the areas, cuts and markings mentioned above. With their help, the shape of the excavation 108 can then be compared to the Fig. 2b und 2c shown form 115 of the excavation can be changed: By introducing calibration marks 114 by means of the first 3 or further laser device 6 (here the femtosecond laser device), the ablation profile in the edge regions is then controlled during the ablation process by means of the second laser device 7 (here the excimer laser device).

[0090] The Fig. 2e shows, in addition to the calibration marks 114 already mentioned, further calibration marks: calibration marks above the implant in its edge area 116 and calibration marks next to the implant, as well as stacked calibration marks 117, 118.

[0091] In the Fig. 2f In addition, an edge cut 119 is planned with the first 3 or further laser device 6, the femtosecond laser device, which thus determines the height of the implant 106 in its edge zone, in particular the patient-specific lamella 24 as the end product of the planning and processing of the blank 23, more reliably than if this height is generated solely by ablation using the second laser device 7, the excimer laser device.

[0092] In these variants of the Fig. 2a bis 2f The patient-specific lamella 24 is machined from a blank 23 in the donor cornea. Only after this processing is the implant 106 removed from this donor cornea or the artificial tissue.

[0093] The Fig. 3a bis 3f show various processing stages as well as processing variants of a blank 23 in an artificial tissue or a donor cornea for a process for producing an implant / a patient-specific lamella 24, such as can be achieved, for example, with the aid of the planning device 2 according to the invention - for the basic variant of further processing of the blank using the second laser device 7, here an excimer laser device, such that the blank 23 is removed from the artificial tissue and fixed on a holder 25. This method is particularly preferred when processing artificial tissue, since when fixed to a holder 25 during processing with the second laser device 7, i.e., an excimer laser device, a safe temperature regime should be ensured: Artificial tissue is even more sensitive in this regard than the natural tissue of a donor cornea.

[0094] In the Fig. 3a First, an artificial tissue is shown that essentially "recreates" a natural cornea, with epithelial layer 101, Bowman's membrane 102, and corneal stroma 103. In addition, the cuts that fundamentally separate the blank 23 from the artificial tissue are shown: the lamellar cut 104 and the edge cut 105, which in this case is not made from the lamellar cut 104 all the way into the epithelial layer 101, but only into the stromal layer. However, the blank 23 is only truly separated from the artificial tissue by the modified edge cut 120.

[0095] In the Fig. 3b is one of the already in the Fig. 3a In addition to the above-mentioned areas, cuts and markings, the implant 106 to be created in the form of the personalized lamella and the resulting ablation volume 107 as well as an excavation 108 are also shown: In particular, the representation of the excavation 108 makes it clear that the modified edge cut 120 is planned in such a way that the excavation 108 is completely enclosed in the blank 23 separated from the artificial tissue by the cuts. Visible in the Fig. 3b are also the two outer boundaries of the correction zone 109, 110, as well as the upper outer boundary of the implant 111, which represents the intersection point of the edge cut 105 and the final implant top side.

[0096] In the Fig. 3c The Blank 23 was first removed from the artificial tissue and fixed on a Haller 25. In addition to the Fig. 3a und 3b In addition to the areas, sections and markings mentioned above, the outer boundary of the transition zone 112, 113 is shown here.

[0097] The Fig. 3d shows in addition to the already in the Fig. 3a bis 3c mentioned areas, cuts and markings again have calibration marks 114. Here too, the shape 115 of the excavation 108 can be influenced with the help of the calibration marks 114.

[0098] The Fig. 3e In addition to the calibration marks 114 already mentioned, it shows further calibration marks: calibration marks above the implant in its edge area 116 and calibration marks next to the implant 106, as well as stacked calibration marks 117, 118 – all in more or less the same way as when processing the blank 23 into a patient-specific lamella 24 in the donor cornea. However, in this variant, from the moment the blank 23 is fixed to the holder 25, a temperature regime can be introduced and maintained very precisely during processing of the blank 23 with the second laser device 7, the excimer laser device.

[0099] In the Fig. 3f In addition, an edge cut 119 is planned with the first 3 or further 6 laser devices, the femtosecond laser device, which thus reliably determines the height of the implant 106 in its edge zone, in particular the patient-specific lamella 24 as the final product of the planning and processing of the blank 23.

[0100] The Fig. 4a bis 4c finally show an implant 106 after processing with the laser devices 3, 7, 6 of the treatment system 1 according to the invention and before its introduction into a cut surface 21 of the cornea of ​​a recipient eye.

[0101] In the Fig. 4a Such an implant 106, whose blank 23 was processed on a holder 25 with the second laser device 7, the exciner laser device, is shown in a plan view, which Fig. 4b und 4c show the same implant 106 in a side view. The excavation precisely carved out the actual edge of the lamella 24 to be implanted. However, it is protected until after its processing with the second laser device 7. The separation point for finally separating this extended "protective edge" was created with the edge cut ("side cut") of the blank 23 at the beginning of the entire manufacturing process of the patient-specific lamella 24. This patient-specific lamella 24 then remains after the actual separation of the "protective edge," as shown in the Fig. 4c shown, remains and can be inserted into the prepared cut surface 21 or structure in the cornea 20 of the recipient eye.

[0102] The features of the invention mentioned above and explained in various embodiments can be used not only in the combinations given as examples, but also in other combinations or alone, without departing from the scope of the present invention.

Claims

1. Planning device (2) for generating control data for a treatment system (1) for refractive surgery, in particular for keratoplasty, said treatment system comprising a first laser device (3) and at least one characterization device (4), - wherein the first laser device (3), preferably a femtosecond laser device, is rendered controllable by means of the control data so as to create at least one cut surface (21) in a cornea (20) of an eye, the planning device (2) comprising: - an interface (5) for supplying first measurement data regarding parameters of the cornea (20) to the characterization device (4), preferably an OCT (optical coherence tomography) device, - an interface (5) for supplying second measurement data or model data about a lamella (24) which is insertable into the cornea (20) following the creation of the cut surface (21), - an interface (5) for transmitting control data to the first laser device (3), and - calculation means for defining the at least one cut surface (21) in the cornea (20) using the first measurement data and the second measurement data or model data, the calculation means generating a control data set for controlling the first laser device (3), and the at least one cut surface (21) being created by the first laser device (3) using the control data set, - and the planning device is furthermore configured to generate control data for a second laser device (7) of the treatment system (1), preferably an excimer laser device, and comprising an interface (5) for transmitting control data to the second laser device (7), wherein the first laser device (3), the second laser device (7) and the characterization device (4) each have an equipment coordinate system and these devices are coupled or couplable with respect to one another by means of registration of the equipment coordinate systems, and the supplied second measurement data or model data of the lamella (24) are registrable with respect to these equipment coordinate systems, wherein - the second laser device is configured to treat a blank (23) to form a patient-specifically shaped lamella (24), and the second laser device (7) for processing the blank (23) to form a patient-specifically shaped lamella (24) comprises a holder on which the blank (23) is affixable during the processing by the second laser device (7), characterized in that - the planning device is configured to determine a substantially ring-shaped transition zone at the edge of the lamella (24), within which the edge thickness gradually transitions into a patient-specific thickness profile, and furthermore control data are generated in such a way that there is no processing of the edge of the lamella by the second laser device (7), and - the planning device is furthermore configured to generate control data for active cooling of the holder.

2. Planning device (2) according to Claim 1, furthermore configured to generate control data for the first laser device (3) or a further laser device (6), likewise preferably a femtosecond laser device, the equipment coordinate system of which is likewise coupled to the aforementioned equipment coordinate systems by means of registration, in order to generate or pre-process the blank (23), wherein the blank (23) is able to be generated from a natural donor cornea or from artificial tissue, or the blank is pre-processable therein, by creating one or more cut surfaces (104, 105, 119, 120) in the donor cornea or the artificial tissue by means of the first laser device (3) or the further laser device (6).

3. Planning device (2) according to Claim 1 or 2, configured to generate control data for a temperature regime for maintaining a temperature below a maximum temperature for processing the blank to form the lamella (24) using the second laser device (7).

4. Planning device (2) according to Claim 2 or 3, configured to define cut surfaces (104, 105, 119, 120) in the donor cornea or in the artificial tissue in such a way as to generate control data and transmit the latter to the first laser device (3) or the further laser device (6) with which the blank (23) is being generated, the blank being defined by a correction zone situated in the centre of the blank (23), a transition zone arranged around said correction zone and an edge zone arranged around said transition zone, the edge zone being provided for the subsequent separation prior to an insertion of the lamella (24) into the cornea of the eye, and this blank (23) can be removed and affixed on the holder (25) for the purposes of processing with the second laser device (3).

5. Planning device (2) according to Claim 4, configured to define the position of calibration marks (114, 117, 118) in the transition zone and / or the edge zone and to generate control data for the first laser device (3) or the further laser device (6), by means of which control data these calibration marks (114, 117, 118) are able to be introduced during processing with the first laser device (3) or the further laser device (6), wherein the calibration marks (114, 117, 118) are defined such that they are usable as a single or multiple orientation means during a processing of the blank (23) by means of the second laser device (7).

6. Planning device (2) according to Claim 5, which defines calibration marks (114, 117, 118) which are arranged multiple times above one another and / or offset from one another and / or at different levels in the blank to be processed by the second laser device (7).

7. Planning device (2) according to any of Claims 1 to 6, configured to define a processing profile for the second laser device (7) and determine the control data in such a way that the profile of the correction zone situated in the centre of the blank (23) and of the transition zone arranged around said correction zone is producible by means of the second laser device (7) and an excavation (108) is producible in the edge zone arranged around this transition zone, - for the removal of a lamella (24) carved out of the donor cornea or the artificial tissue, or - for further processing of the blank (23) on a holder (25), in such a way that the holder (25) cannot be hit by a processing laser beam of the second laser device (7).

8. Planning device (2) according to any of Claims 1 to 7, configured to take account of a defined initial hydration state of the blank (23) or of the lamella (24) ex vivo, and the change in the hydration state of the lamella (24) during or after the implantation, preferably by means of a constant expansion factor, to generate the control data.

9. Treatment system (1) for refractive surgery, in particular for keratoplasty, comprising - a first laser device (3) for creating at least one cut surface (21) in a cornea (20) of an eye, preferably a femtosecond laser device, - a second laser device (7) for processing a blank (23) to form a patient-specifically shaped lamella (24), preferably an excimer laser device, - at least one characterization device (4), preferably an OCT device, characterized in that the treatment system further - comprises a planning device (2) according to any of Claims 1 to 8, and - the second laser device (7) contains a holder (25) for affixing the blank (23) during the processing.

10. Treatment system (1) according to Claim 9, comprising a further laser device (6) for generating or pre-processing the blank (23), preferably a femtosecond laser device.

11. Treatment system (1) according to any of Claims 9 and 10, comprising a temperature control device, preferably such that the temperature of the blank (23) can be lowered in such a way that the blank (23) is able to be generated in the frozen state.

12. Treatment system (1) according to Claim 11, the temperature control device of which comprises at least one of the following configurations: - active electrical cooling by means of a Peltier element, - active cooling by means of an introduced coolant, - active cooling by an air flow, - passive cooling by pre-cooling the holder (25) with or without the blank (25) affixed thereon, - a chamber, separated from the surroundings, for processing the blank (23).

13. Treatment system (1) according to any of Claims 9 to 12, comprising a device for monitoring the temperature of the blank (23) and / or of the holder (25) during the processing.