Method for providing control data for ophthalmic laser of treatment device

Abstract

The invention relates to a method for providing control data for an ophthalmic laser (12) of a treatment device (10) for treating a cornea (16) that has been treated with a cross-linking method. By means of the control device (18), it is achieved that conventional laser parameters for removing a predetermined correction volume (14) from the cornea (16) are set, the laser parameters comprising at least the laser pulse energy and the number of laser pulses of the laser (12); providing a power-increased laser parameter in the region of the correction volume (14), in which the cornea (16) is expected to be changed by a cross-linking method, the power-increased laser parameter having a higher laser pulse energy and / or a higher number of laser pulses than conventional laser parameters; and providing control data comprising an increased power laser parameter in the region of the correction volume (14) for corneal alteration and a conventional laser parameter in the remaining region of the correction volume (14).

Description

Technical Field

[0001] The invention relates to a method for providing control data for an ophthalmic laser of a treatment device for treating a cornea that has been treated with a cross-linking method. Furthermore, the invention relates to a control device configured to carry out the method, a treatment device having such a control device, a computer program comprising commands for causing the treatment device to carry out the method, and a computer-readable medium having the computer program stored thereon. Background Art

[0002] Therapeutic devices and methods for controlling ophthalmic lasers to correct optical visual disorders or pathological and / or unnaturally altered areas of the cornea are known in the prior art, wherein the pulsed laser and the beam focusing device can, for example, be formed such that the laser pulses achieve photodisruption and / or ablation in a focus located within the organic tissue to remove tissue, in particular tissue lenticules, from the cornea.

[0003] Furthermore, it is known to subject the cornea to so-called cross-linking methods (cross-linking; CXL). In this case, the cornea is irradiated with UV light, in particular with the aid of riboflavin (vitamin B2), which leads to cross-linking of the connective tissue fibers, thereby strengthening the corneal structure, for example stabilizing keratoconus. However, treatment with such cross-linking methods can also affect the interaction of the laser pulses with the treated tissue of the cornea, thereby affecting subsequent treatment with ophthalmic lasers and possibly affecting tissue separation. SUMMARY OF THE INVENTION

[0005] It is therefore an object of the present invention to improve the provision of control data for a cornea on which a cross-linking method has been performed.

[0006] This object is solved by the independent claims. Advantageous embodiments of the invention are disclosed in the dependent claims, the following description and the drawings.

[0007] One aspect of the invention relates to a method for providing control data for an ophthalmic laser of a treatment device for treating a cornea that has been treated with a cross-linking method, wherein the method comprises the following steps performed by a control device, wherein the control device is an apparatus or an apparatus component, in particular a computer or a processor, that can automatically or semi-automatically perform the following steps.

[0008] In the method, setting conventional laser parameters for removing a predetermined corrective volume from the cornea is achieved, wherein the laser parameters include at least a laser pulse energy and a number of laser pulses of the laser, providing laser parameters with increased power in the region of the corrective volume, wherein a cornea is expected to be changed by a cross-linking method, wherein the laser parameters with increased power have a higher laser pulse energy and / or a higher number of laser pulses compared to the conventional laser parameters, and providing control data, which control data include the laser parameters with increased power in the region of the corrective volume, wherein the cornea is changed, and the conventional laser parameters in the remaining region of the corrective volume.

[0009] In other words, it can be assumed that the cornea has been treated with a cross-linking method and therefore has altered areas of the cornea. In order to plan a treatment with the treatment device, a predetermined correction volume can be set, which correction volume is to be treated with conventional laser parameters, wherein it can be checked whether there are areas of the cornea that have been altered by the cross-linking method in the predetermined correction volume. If this is the case, more powerful laser parameters can be planned for these areas compared to areas of the correction volume where no altered cornea is present.

[0010] The power increase of the laser parameters can be achieved by increasing the laser pulse energy and / or increasing the number of laser pulses in these regions. Increasing the number of laser pulses can be achieved by increasing the repetition rate on the one hand and / or reducing the pulse distance of the laser pulses in these regions on the other hand. In particular, it is specified that the power-increased laser parameters provide a power increase of at least 10% compared to conventional laser parameters.

[0011] Specifically, the cornea may have a higher stability in the areas modified by the cross-linking method, and therefore a higher energy is required to separate the corneal layers. Here, the laser parameters for the power increase do not have to be increased to a constant value, but can be adjusted according to the assumed size or intensity of the cornea modified by the cross-linking method. For all other areas of the cornea, conventional laser parameters can be used, wherein the conventional laser parameters can be optimized for (photo)ablation and / or photodestruction of the unchanged corneal tissue.

[0012] For example, the area of ​​the cornea that is expected to be altered by the cross-linking method can be estimated, in particular based on a diffusion model of riboflavin in the cornea and / or an absorption gradient of UV light in the cornea. Alternatively or additionally, the location of the altered cornea can also be determined by measurements of the cornea before treatment.

[0013] Finally, control data can be provided in which areas to be irradiated with laser parameters with increased power and areas to be irradiated with conventional laser parameters are set.

[0014] The control data may include a corresponding data set for positioning and / or focusing the individual laser pulses in the cornea. Additionally or alternatively, the control data may include a corresponding data set for adjusting at least one beam arrangement for beam guiding and / or beam shaping and / or beam deflecting and / or beam focusing the laser beam of the individual lasers.

[0015] By means of the present invention, it is advantageously possible to improve the treatment of corneas that have been treated with cross-linking methods.

[0016] The invention also includes embodiments that produce additional advantages.

[0017] In one embodiment, the cornea that is intended to be altered by the cross-linking method is from the surface of the corneal stroma down to a preset depth in the cornea. This means that the cross-linking area is assumed to be from the front interface of the stroma in the depth direction or z-direction down to a preset depth in the cornea, which preset depth may also be located in the stroma. For example, the preset depth may be preset to a depth value of 100 μm in the corneal stroma, in particular 50 μm. These values ​​represent preferred depths, where the cornea is still altered by the cross-linking method, where 50 μm is assumed in a conventional cross-linking method, where no additional riboflavin is applied, and 100 μm is assumed in an accelerated cross-linking method, where riboflavin is applied. The epithelial layer located above the stroma cannot be treated with laser parameters of increased power, but only with conventional laser parameters.

[0018] In another embodiment, it is assumed that the altered cornea has a gradient up to a preset depth in the cornea, wherein laser parameters with increasing power are provided according to the gradient. This means that the cornea is heavily cross-linked and therefore changes occur in the upper layers of the cornea, wherein the cross-linking decreases with increasing depth. Therefore, at the location of the upper layers of the cornea, laser parameters with increasing power can be provided with a high laser pulse power, wherein the laser pulse power can be reduced with increasing depth in the cornea corresponding to the gradient, until finally reaching conventional laser parameters in the preset depth. This means that the laser power can be reduced along the gradient of cross-linking with increasing depth. Thereby, the advantage is that suitable laser parameters can be provided for each degree of cross-linking.

[0019] In another embodiment, it is assumed that the cornea modified by the cross-linking method has a gradient in the radial direction, wherein it is assumed that the degree of cross-linking in the center of the cornea is higher than that in the periphery of the cornea, wherein laser parameters with increased power are provided according to the gradient in the radial direction. Thus, for example, a diffusion of riboflavin from the inside to the outside may occur during the cross-linking method, so that the degree of cross-linking in the center of the cornea is higher than that in the periphery. Accordingly, the laser parameters can be adjusted so that laser parameters with increased power are provided with a maximum power in the center, which decreases outwardly in the radial direction until the laser pulse power of conventional laser parameters is finally reached. In particular, the aforementioned gradient can be combined with a radial gradient in the depth direction of the cornea, so that optimized laser parameters depending on the z-direction and the radial direction are provided to irradiate the cornea modified by the cross-linking method.

[0020] In another embodiment, the areas of the cornea that are expected to be changed by the cross-linking method are determined based on predetermined measurement data, in particular by Brillouin spectroscopy. In other words, the areas where the laser parameters with increased power are to be provided can be predetermined by measurement. In these areas determined by measurement, constant laser parameters with increased power can be provided, for example an increase of 10% compared to conventional laser parameters, or laser parameters with increased power can be provided depending on the degree of cross-linking. A preferred possibility for determining the degree of cross-linking is Brillouin spectroscopy, by examining the inelastic scattering of light by phonons, the Young's modulus of the material can be determined. With this embodiment, the advantage is that the areas of corneal changes or cross-linking can be located most accurately.

[0021] In another embodiment, a warning signal is generated if it is determined that the removal of the cornea modified by the cross-linking method exceeds a threshold value preset by generating a correction volume. In other words, a warning signal can be provided if it is determined that too much cross-linked tissue is removed from the cornea by removing the correction volume. For example, a warning signal can be output to the user via a user interface (e.g., via a display device or an acoustic device). Here, the control device can compare how large the correction volume is and what percentage of the cornea modified by the cross-linking method is in the correction volume. With this embodiment, precautions can be taken not to remove too much cross-linked cornea, as this may compromise the stability of the entire cornea.

[0022] In another embodiment, the area of ​​the cornea that is changed by the cross-linking method is determined based on the duration of a previously known cross-linking method and / or the therapeutic properties of a previously known cross-linking method. In other words, if the parameters of the cross-linking method used are known, it is possible to estimate in which areas the cornea is cross-linked and / or the severity of the cross-linking of the cornea in which areas. In particular, the duration of the cross-linking method can determine the extent to which riboflavin penetrates into the cornea, thereby determining the expected depth of the cornea after cross-linking. Therefore, depending on the cross-linking method used, the duration can, for example, include 5 to 45 minutes. It is also possible to use a distinction between conventional cross-linking methods, accelerated cross-linking methods (in which additional drugs are applied to accelerate diffusion or penetration), or cross-linking methods in which the epithelial layer is still present. By this embodiment, the advantage is that improved positioning of the cornea after cross-linking can be performed.

[0023] Another aspect relates to a method for controlling a therapeutic device. The method comprises the method steps of at least one embodiment of the method as described above. In addition, the method for controlling a therapeutic device comprises the steps of transmitting the provided control data to at least one ophthalmic laser of the therapeutic device and controlling the therapeutic device and / or the laser using the control data.

[0024] The corresponding method may include at least one additional step, which is performed if and only if an application case or application situation occurs, which application case or application situation is not explicitly described here. For example, this step may include outputting an error message and / or outputting a request for input user feedback. Additionally or alternatively, it may be provided that a default setting and / or a predetermined initial state are adjusted.

[0025] Another aspect of the present invention relates to a control device, which is formed to perform the steps of at least one embodiment of one or both of the aforementioned methods. In addition, the control device may include a computing unit, such as a processor, for electronic data processing. The computing unit may include at least one microcontroller and / or at least one microprocessor. The computing unit may be configured as an integrated circuit and / or a microchip. In addition, the control device may include an (electronic) data memory or a storage unit. A program code may be stored on a data memory, by which the steps of the corresponding embodiments of the corresponding method are encoded. The program code may include control data for the corresponding laser. The program code may be executed by a computing unit, thereby causing the control device to perform the corresponding embodiment. The control device may be formed as a control chip or a control unit. The control device may, for example, be included in a computer or a computer cluster.

[0026] Another aspect of the invention relates to a treatment device having at least one eye surgery or ophthalmic laser and a control device, which is formed to carry out the steps of at least one embodiment of one or both of the above-mentioned methods. The corresponding laser can be formed to at least partially separate a predetermined corneal volume of a human or animal eye with a predetermined interface by optical decomposition, in particular by photodisruption and / or by ablating corneal layers by means of (photo)ablation and / or to achieve a laser-induced refractive index change in the cornea and / or the eye lens.

[0027] In another embodiment of the treatment device according to the invention, the laser can be suitable for emitting laser pulses with a wavelength range between 300nm and 1400nm, for example between 900nm and 1200nm, and a repetition frequency greater than 10 kilohertz (kHz), for example between 100kHz and 100 megahertz (MHz), with a corresponding pulse duration between 1fs and 1ns, for example between 10fs and 10ps. The use of such a laser in the method according to the invention also has the advantage that the irradiation of the cornea does not have to be carried out in a wavelength range below 300nm. This range is included in the term "deep ultraviolet" in laser technology. As a result, accidental damage to the cornea caused by these extremely short wavelength and high-energy beams is advantageously avoided. Photodisruptive and / or ablative lasers of the type used here usually input pulsed laser radiation with a pulse duration between 1fs and 1ns into the corneal tissue. As a result, the power density of the corresponding laser pulses required for optical breakdown can be narrowly limited spatially, so that high cutting accuracy can be achieved in the generation of the interface. In particular, the range between 700 nm and 780 nm may also be selected as the wavelength range.

[0028] In another embodiment of the therapeutic device according to the invention, the control device may include at least one storage device for at least temporarily storing at least one control data set, wherein one or more control data sets include control data for positioning and / or for focusing individual laser pulses in the cornea; and may include at least one beam device for beam guiding and / or beam shaping and / or beam deflection and / or beam focusing of the laser beam of the laser.

[0029] Another aspect of the invention relates to a computer program. The computer program includes, for example, commands forming a program code. The program code may include at least one control data set having corresponding control data for a corresponding laser. When the program code is executed by a computer or a computer cluster, the previously described method or at least one embodiment thereof is performed.

[0030] Another aspect of the present invention relates to a computer-readable medium (storage medium) on which the above-mentioned computer program and its commands are stored respectively. In order to execute the computer program, a computer or a computer cluster can access the computer-readable medium and read out its content. For example, the storage medium is formed as a data memory, in particular at least partially formed as a volatile or non-volatile data memory. The non-volatile data memory can be a flash memory and / or an SSD (solid state drive) and / or a hard disk. The volatile data memory can be a RAM (random access memory). For example, the command can exist as a source code of a programming language and / or as an assembler and / or as a binary code.

[0031] Further features and advantages of one of the aspects described herein may result from the embodiments of another aspect of the invention. Therefore, if the features of the embodiments of the invention are not explicitly described as mutually exclusive, they may exist in any combination with each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Below, additional features and advantages of the present invention are described in the form of advantageous implementation examples based on the accompanying drawings. The features or feature combinations of the implementation examples described below may exist in any combination in combination with each other and / or with the feature combinations of the implementation examples. This means that the features of the implementation examples may supplement and / or replace the features of the implementation examples, and vice versa. Therefore, configurations are also considered to be covered and disclosed by the present invention, which are not explicitly shown or explained in the drawings, but are produced and can be generated by separate feature combinations from the implementation examples and / or implementation examples. Therefore, configurations are also considered to be disclosed, which do not include all the features of the originally proposed claims or extend beyond or deviate from the feature combinations set forth in the relationship of the claims. For the implementation examples, it is shown:

[0033] Figure 1 is a schematic diagram of a therapeutic device according to an exemplary embodiment;

[0034] Figure 2 is a diagram of a schematic method of providing control data according to an exemplary embodiment.

[0035] In the figures, identical or functionally identical elements are provided with the same reference symbols. DETAILED DESCRIPTION OF THE INVENTION

[0037] Figure 1A schematic diagram of a treatment device 10 is shown with an ophthalmic laser 12 for removing a corrective volume 14 from a human or animal cornea 16 by photodestruction and / or ablation. The corrective volume 14 may, for example, represent a lenticule or a volumetric body, which may be separated from the cornea 16 by the ophthalmic surgical laser 12 in order to correct a visual disorder. The corrective volume 14 to be removed or the geometry of the corrective volume 14 may be preset in a control device 18, in particular in the form of control data, so that the laser 12 emits pulsed laser pulses into the cornea 16 of the eye in a pattern predefined by the control data in order to remove the corrective volume 14. Alternatively, the control device 18 may be a control device 18 external to the treatment device 10.

[0038] also, Figure 1 It is shown that a laser beam 20 generated by a laser 12 can be deflected toward the cornea 16 by a beam deflection device 22 (eg, a rotary scanner) to remove the corrective volume 14. The beam deflection device 22 can also be controlled by the control device 18 to remove the corrective volume 14.

[0039] In particular, the illustrated laser 12 may be a photodisruptive and / or photoablative laser formed to emit laser pulses having a wavelength in the range of 300 nm to 1400 nm, for example, 700 nm to 1200 nm, with a corresponding pulse duration between 1 femtosecond and 1 nanosecond, for example, between 10 femtoseconds and 10 picoseconds, and a repetition frequency of the laser pulses greater than 10 kHz, for example, between 100 kHz and 100 MHz. In addition, the control device 18 optionally includes a storage device (not shown) for at least temporarily storing at least one control data set, wherein one or more control data sets include control data for positioning and / or for focusing individual laser pulses in the cornea.

[0040] If the cornea 16 has been treated with a cross-linking method in a pre-treatment, areas of the cornea 16 may be changed by the cross-linking so that they have a more compact structure than untreated areas. Here, the properties of the cornea 16 are also changed with respect to the separation of the correction volume 14, so that the generation of the correction volume 14 using conventional laser parameters is impaired. Therefore, in order to take into account the influence of the previous cross-linking method, the control device 18 can perform Figure 2 The method shown in .

[0041] exist Figure 2 A schematic diagram of a method for providing control data for an ophthalmic laser 12 of a treatment device 10 for treating a cornea 16 which has previously been treated with a cross-linking method is shown in FIG.

[0042] In step S10, conventional laser parameters for removing a predetermined correction volume 14 from the cornea 16 may be provided. For example, the correction volume may be set based on predetermined examination data to correct visual impairment and / or unnatural or pathologically altered tissue of the cornea 16. At this point, conventional laser parameters may be planned, particularly including laser pulse energy and the number of laser pulses per tissue volume, which are optimized for common corneal tissues. This means that corneal tissue ablation and / or corneal tissue incision may be performed using conventional laser parameters without adverse effects, such as an opaque bubble layer or black spots.

[0043] In step S12, increased-power laser parameters can be planned in the region of the correction volume 14, in which the cornea is expected to change due to the cross-linking method. Here, the increased-power laser parameters can have a higher laser pulse power than conventional laser parameters, wherein the laser pulse energy can in particular be increased to this and / or a greater number of laser pulses per volume can be planned. In order to increase the number of laser pulses, for example, the repetition rate of the laser and / or the laser pulse distance in the corresponding region can be changed. The increased-power laser parameters can be increased continuously compared to the conventional laser parameters, for example by 10%, or the increased-power laser parameters can be adjusted depending on the degree of corneal changes. This means that the higher the degree of corneal cross-linking, the higher the laser pulse power can be adjusted, wherein the degree of cross-linking and therefore the adjusted laser pulse power may differ depending on the location in the cornea 16.

[0044] In step S12, it can be determined in advance where the areas of the cornea that have been altered by the crosslinking method are located. In addition, the extent of the alteration can be determined here. In order to determine the areas with increased crosslinking, measurements can be performed, in particular using Brillouin spectroscopy, or these areas can be estimated by a model.

[0045] When estimating by means of a model, on the one hand, previously known treatment properties of the crosslinking method, in particular treatment properties with a known duration, can be used to determine the area of ​​corneal changes. In this case, it can be assumed that the degree of crosslinking of the cornea 16 at the surface, that is, in the direction of the treatment device 10, is higher than at depth, wherein in particular there is a gradient that decreases from the surface to the depth. Thus, for example, the laser parameters for increasing power can be selected to be higher at the surface than in the depth direction, wherein the laser parameters for increasing power can be reduced according to the gradient in depth, for example to a preset depth of 100 μm, in particular 50 μm, in the stroma, at which depth the influence of crosslinking is no longer expected.

[0046] In a corresponding manner, a gradient of crosslinking in the radial direction can be planned so that a higher degree of crosslinking is assumed in the central region than in the peripheral region. In other words, the laser power in the power-increasing laser parameters can decrease from the surface to the depth and from the center to the periphery.

[0047] In step S14, control data can then be generated which have laser parameters with increased power in the region of the correction volume 14 which has been changed by the cross-linking method, and conventional laser parameters can be used for the remaining region of the correction volume 14. In particular, laser pulse parameters with increased power can be planned only in the stroma of the cornea 16, wherein thus conventional laser parameters can be provided for setting in an incision or ablation in the epithelium of the cornea 16.

[0048] Overall, these examples demonstrate how to provide an improved treatment plan for a cornea 16 that has been pre-treated with a cross-linking method.

Claims

1. A method for providing control data for an ophthalmic laser (12) of a treatment device (10) for treating a cornea (16) which has been treated with a cross-linking method, wherein the method comprises the following steps performed by a control device (18): - setting conventional laser parameters for removing a predetermined corrective volume (14) from the cornea (16), wherein the laser parameters include at least the laser pulse energy and the number of laser pulses of the laser (12); - providing laser parameters with increased power in the region of the correction volume (14), wherein: In the region of the correction volume (14), the cornea (16) is intended to be modified by the cross-linking method, wherein the laser parameters with increased power have a higher laser pulse energy and / or a higher number of laser pulses compared to the conventional laser parameters; - providing said control data, said control data comprising laser parameters with increased power in the area of ​​said correction volume (14) where the cornea is modified by said cross-linking method and conventional laser parameters in the remaining areas of said correction volume (14).

2. The method according to claim 1, wherein: The cornea (16) altered by the cross-linking method is intended to extend from the stromal surface of the cornea (16) down to a predetermined depth in the cornea (16).

3. The method according to claim 2, wherein: A modified corneal gradient is assumed down to a preset depth in the cornea (16), wherein the power-increased laser parameters are provided in accordance with the gradient.

4. The method according to any one of claims 2 or 3, wherein: The preset depth is preset to a depth value of 100 μm, in particular 50 μm, in the stroma of the cornea (16).

5. A method according to any one of the preceding claims, wherein: It is assumed that the cornea changed by the cross-linking method has a gradient in the radial direction, wherein the degree of cross-linking in the center of the cornea (16) is assumed to be higher than the degree of cross-linking in the periphery of the cornea (16), wherein the laser parameters with increased power are provided according to the gradient in the radial direction.

6. A method according to any one of the preceding claims, wherein: The area of ​​the cornea modified by the cross-linking method is expected to be determined based on predetermined measurement data, in particular by Brillouin spectroscopy.

7. A method according to any one of the preceding claims, wherein: If the amount of cornea removed as altered by the cross-linking method as determined by generating the correction volume exceeds a preset threshold, a warning signal is generated.

8. A method according to any one of the preceding claims, wherein: The area of ​​the cornea altered by the cross-linking method is determined based on the duration of a previously known cross-linking method and / or the previously known therapeutic properties of the cross-linking method.

9. Control device (18) configured to carry out a respective method according to any of the preceding claims.

10. Treatment device (10) comprising: at least one eye surgery laser (12) for separating a corneal volume (14) of a human or animal eye by optical breakdown, in particular by photodestruction and / or photoablation, and at least one control device (18) according to claim 9.

11. Computer program comprising instructions causing a therapeutic device (10) according to claim 10 to perform a method according to any one of claims 1 to 8.

12. Computer readable medium having stored thereon a computer program according to claim 11.

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