Apparatus and method for providing control data for ophthalmic laser of therapeutic device for reducing geometric irregularities of eye

Abstract

The present invention relates to an apparatus and a method for providing control data for an ophthalmic laser (12) of a therapeutic device (10) for reducing geometric irregularities (14) of the eye. The method comprises, as steps: determining a geometric irregularity (14) of the eye from predetermined examination data producing high-order aberrations; determining a treatment profile having a predetermined optical region from the geometric irregularities (14), an optimization function comprising terms for reducing higher order aberrations and opposite tissue removal terms being optimized until an optimization range for determining the treatment profile; and providing control data including at least the treatment profile.

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for providing control data for an ophthalmic laser of a treatment device for reducing a geometric irregularity of an eye. Furthermore, the present invention relates to a control device configured to perform the method, a treatment device having such a control device and a computer program comprising a command to cause the treatment device to perform the method, and a computer readable medium storing the computer program. BACKGROUND

[0002] Treatment devices and methods for controlling an ophthalmic laser for correcting optical visual impairments and / or pathological or unnatural altered regions of the cornea are known in the prior art. Therein, a pulsed laser and a beam focusing device can for example be formed such that the laser pulses generate a photodisruption and / or ablation at a focal point located within organic tissue to remove tissue, in particular tissue lenses, from the cornea.

[0003] If the eye, in particular the cornea, has a geometric irregularity, it is difficult to improve the vision by changing the curvature of the cornea. The geometric irregularity can for example be a bulge and / or thinning of the eye, in particular the cornea, which can for example be caused by keratoconus, pachymene, limbal dystrophy, inflammation of the eye and / or scarring of the eye, for example due to an improper treatment. Thus, the cornea can no longer be smooth, but have one or more bulges or depressions, which create aberrations and thus interfere with the vision. This means that the geometric irregularity is not a regular visual impairment like myopia or hyperopia. Therefore, the geometric irregularity cannot be improved by spectacles correction, in particular by laser treatment, wherein the values of sphere, cylinder and axis are adapted. SUMMARY

[0004] It is an object of the present invention to treat a geometric irregularity of an eye in an improved way.

[0005] This object is solved by the independent claims. Advantageous developments of the present invention are disclosed in the dependent claims, the following description and the figures.

[0006] The present invention is based on the idea to plan a treatment by which the geometric irregularity is cut or ablated, thereby minimizing the impairment effect on the vision and additionally preserving as much corneal tissue as possible.

[0007] One aspect of the present invention relates to a method for providing control data for an ophthalmic laser of a treatment device for reducing a geometric irregularity of an eye, wherein the method comprises the following steps performed by a control device. Therein, the instrument or instrument component shall be understood by the control device, which for example comprises a processor or microprocessor, wherein the following steps can be performed automatically or semi-automatically by the control device.

[0008] The following is achieved: determining a geometric irregularity of the eye from predetermined examination data which generates higher-order aberrations, determining a treatment profile with a preset optical zone from the geometric irregularity, wherein an optimization function comprises terms for reducing the higher-order aberrations and counteracting tissue removal terms, the optimization function is optimized to an optimization range for determining the treatment profile, and control data is provided which at least comprises the treatment profile.

[0009] In other words, a geometric irregularity can be present in the eye or the cornea. For example, the geometric irregularity can be a protrusion and / or a depression, thereby generating higher-order aberrations. The geometric irregularity or the higher-order aberrations can be determined, for example, by an examination which is predetermined and provided as examination data to the control device. Here, in particular, the corneal profile can be determined by topography or the wavefront profile of the eye can be determined. Thus, the geometric irregularity can be described as an optical error.

[0010] In order to compensate or reduce the geometric irregularity, a treatment profile can be planned, wherein, for example, a preset optical zone is specified as a specification of the treatment area, wherein the higher-order and lower-order aberrations can be changed for the treatment planning. In particular, an optimization function can be provided which is optimized using an optimization calculation method, wherein the optimization function comprises terms for reducing the higher-order aberrations and counteracting tissue removal terms. Here, the higher-order aberrations to be corrected can in particular be varied between a value determined initially and zero, wherein an individual reduction can be determined for each higher-order aberration or globally for all higher-order aberrations. For lower-order aberrations which occur therein, for example spherical, cylindrical and axial values, here no specification can be provided so that the lower-order aberrations can be introduced to advantage the regularization, which can be compensated by a separate correction after the treatment, for example by glasses or refractive correction.

[0011] In order to compensate the geometric irregularity, the treatment profile can comprise, for example, a plane-parallel volume to ablate the irregularity. In particular, the treatment can also extend beyond the optical zone, for example to the transition zone or even to the epithelial profile beyond the total stromal ablation zone. In particular, a maximum permissible optical zone can be used which can be preset by wavefront treatment.

[0012] The optimization function can be a cost function, wherein the ablation depth or ablation volume planned in the treatment and removal of the geometric irregularity is used as a term for tissue removal. In particular, it can be optimized by an iterative method until the optimization function is in an optimization range, for example in a range of 10% around the optimum.

[0013] If the optimization function has found a treatment profile, the corresponding treatment profile can be provided to the treatment device, in particular an ophthalmic laser, in the form of control data, wherein the control data can be used subsequently to control the laser. In particular, the laser can be an ablation laser, by which corneal tissue can be ablated, but also a photodisruptive laser, by which incisions can be produced on the cornea, so that geometric irregularities can be removed.

[0014] An advantage that arises through the present application is that the influence of geometric irregularities on vision, in particular higher-order aberrations, can be reduced, so that as much tissue as possible can be saved.

[0015] The present application also comprises further embodiments, by which additional advantages can be produced.

[0016] One embodiment provides that the geometric irregularities are determined by a wavefront measurement of the eye, wherein a corneal ideal profile without geometric irregularities and higher-order aberrations is defined by a wavefront ideal profile, wherein the optimization function is optimized in accordance with the corneal ideal profile. This means that the predetermined examination data comprises at least one wavefront measurement of the eye, wherein the treatment profile is determined with the aid of the wavefront ideal profile. The wavefront ideal profile can be a specification of the post-treatment corneal appearance, wherein the wavefront ideal profile thus produces the corneal ideal profile. In particular, it is free of geometric irregularities and / or higher-order aberrations. The optimization can thus be performed by superimposing the current corneal profile on the corneal ideal profile, wherein the corneal ideal profile is changed, for example, along a common axis, until the optimization function is in the range of optimization.

[0017] A further embodiment provides that the geometric irregularities are provided by a corneal profile from a tomography and / or topography of the cornea of the eye, wherein a corneal ideal profile without geometric irregularities and higher-order aberrations is defined, wherein the optimization function is optimized in accordance with the corneal ideal profile. This means that in this embodiment the examination data is determined by the tomography and / or topography and the geometric irregularities are present as a corneal profile. Here, the corneal ideal profile can be defined, which can be superimposed, for example, with a common axis of the corneal profile and changed or moved along this axis until the optimization function is in the range of optimization.

[0018] It can be provided in the following embodiments that the corneal profile used and the corneal ideal profile are provided by a wavefront measurement or from a tomography and / or topography.

[0019] In an embodiment it is provided that for optimizing the optimization function the corneal ideal profile is superimposed with the corneal profile and moved along the perpendicular axis of the corneal profile until the optimization function reaches the optimization range, wherein only the areas of the corneal profile that are located above the treatment profile in the direction of the perpendicular axis are set to be removed. In other words, by moving the corneal ideal profile on the perpendicular axis a position can be found, at which geometric irregularities that can be located above the cut corneal ideal profile are not removed without too much tissue.

[0020] Another embodiment provides that the corneal ideal profile is superimposed with the corneal profile and tilted relative to the perpendicular axis of the corneal profile until the optimization function reaches the optimization range, wherein only the areas of the corneal profile that are located above the treatment profile in the direction of the perpendicular axis are set to be removed. Here it is accepted that the tilted corneal ideal profile results in a cone or prism that is used as the treatment profile, wherein the prism can result in low order aberrations. However, these low order aberrations can be compensated by eyeglass correction.

[0021] A further embodiment provides that the corneal ideal profile is superimposed with the corneal profile and the curvature of the corneal ideal profile is changed until the optimization function reaches the optimization range, wherein only the areas of the corneal profile that are located above the treatment profile are set to be removed. This means that the refractive profile for creating the curvature change of the cornea can be determined by the curvature change of the corneal ideal profile, wherein a plurality of irregularities can be at least partially compensated by the curvature change, thereby minimizing them. In this embodiment, refraction, in particular low order aberrations, can be introduced by the curvature change, but can be compensated again, for example, by eyeglass correction. Here, the aim can be to reduce the high order aberrations of the geometric irregularities by introducing low order aberrations. For example, it can be provided that only low refraction or low order aberrations are introduced, thereby particularly minimizing tissue removal. The refractive values of sphere, cylinder and axis can in particular be freely selectable and independent of the patient. This embodiment serves to obtain symmetry, wherein an overall curvature change of the corneal ideal profile or a curvature change in a plurality of planes, for example two different curvatures perpendicular to each other, can be created to produce a target asphericity.

[0022] Another configuration provides that the irregularities include keratoconus, keratoglobus, corneal limbal dystrophy, herpes simplex keratitis and / or corneal treatment malpractice. This means that usual optical errors, for example low order aberrations, in particular myopia or hyperopia, do not mean geometric irregularities, but unnatural protrusions and / or depressions and / or scar tissue in the eye.

[0023] Another embodiment provides that the examination data comprises a wavefront measurement and / or a tomography measurement and / or a topography measurement of the cornea by which geometric irregularities of the cornea are determined. For example, the wavefront measurement can comprise the cornea or the eye wavefront and the measurement results can be aligned with respect to a point, for example, centered on the pupil, decentered on a pathological point and / or on the corneal vertex, the location of the thinnest cornea and / or on a symmetrical point.

[0024] Another configuration provides that the maximum depth of the tissue removal is limited to below 50 pm. In particular, this can be provided in the case of a maximized optical zone. In particular, 50 pm can be provided below the epithelial tissue, i.e. in the corneal stroma. If the optimization function cannot be optimized to the optimization range by maximizing the optical zone and the change of the higher-order and lower-order aberrations, the optical zone can be adjusted, wherein the higher-order and lower-order aberrations can be adjusted, for example, again to adapt to a smaller optical zone to optimize the optimization function.

[0025] The corresponding method can comprise at least one additional step, which is executed only if and as long as an application case or application situation occurs, which is not explicitly described here. For example, the step can comprise outputting an error message and / or outputting a request for inputting user feedback. Additionally or alternatively, it can be provided that a default setting and / or a predetermined initial state is adjusted.

[0026] Another aspect of the application relates to a control device which is formed to execute the steps of at least one embodiment of the aforementioned method. Furthermore, the control device can comprise a computing unit for electronic data processing, for example, a processor. The computing unit can comprise at least one microcontroller and / or at least one microprocessor. The computing unit can be configured as an integrated circuit and / or a microchip. Furthermore, the control device can comprise an (electronic) data memory or storage unit. A program code can be stored on the data memory, by which the steps of the respective embodiment of the corresponding method are coded. The program code can comprise control data of the respective laser. The program code can be executed by the computing unit, whereby the control device executes the respective embodiment. The control device can be formed as a control chip or control unit. The control device can be included, for example, in a computer or computer cluster.

[0027] Another aspect of the application relates to a treatment device with at least one ophthalmic surgical or ophthalmic laser and a control device which is formed to execute the steps of at least one embodiment of one or both of the aforementioned methods. The respective laser can be formed to at least partially separate a predetermined corneal volume from a predetermined interface of a human or animal eye by optical breakdown, in particular to at least partially separate it by photodisruption and / or to ablate a corneal layer by (photo)ablation.

[0028] In a further advantageous embodiment of the treatment device according to the application, the laser can be adapted to emit laser pulses with a respective pulse duration between 1 fs and 1 ns, for example between 10 fs and 10 ps, a wavelength range between 300 nm and 1400 nm, for example between 900 nm and 1200 nm, and a repetition frequency of more than 10 kilohertz (kHz), for example between 100 kHz and 100 megahertz (MHz). The use of such a laser in the method according to the application also has the advantage that the irradiation of the cornea does not have to be carried out in the wavelength range below 300 nm. This range is contained in the term "deep ultraviolet" in laser technology. Thereby, an unintended damage of the cornea by these very short wavelengths and high-energy light beams is advantageously avoided. The type of photodisruptive and / or ablation laser used here typically inputs pulsed laser radiation with a pulse duration between 1 fs and 1 ns into the corneal tissue. Thereby, the power density of the respective laser pulse required for the optical breakdown can be spatially narrowly limited, so that a high cutting precision can be achieved in the generation of the interface. In particular, a range between 700 nm and 780 nm can also be selected as the wavelength range.

[0029] In a further advantageous embodiment of the treatment device according to the application, the control device can comprise at least one storage device for at least temporarily storing at least one control data set, wherein the one or more control data sets comprise control data for positioning and / or for focusing the individual laser pulses in the cornea; and can comprise at least one beam device for beam guidance and / or beam shaping and / or beam deflection and / or beam focusing of the laser beam of the laser.

[0030] A further aspect of the application relates to a computer program. The computer program comprises commands, for example forming a program code. The program code can comprise at least one control data set with respective control data for the respective laser. When the program code is executed by a computer or a computer cluster, it causes the execution of the method described previously or at least one embodiment thereof.

[0031] A further aspect of the application relates to a computer-readable medium (storage medium) on which the above-mentioned computer program and its commands are respectively stored. 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 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 commands can exist as source code in a programming language and / or as an assembler and / or as binary code.

[0032] Further features and advantages of one of the aspects described by the present application can result from developments of another aspect of the present application. Thus, features of embodiments of the present application can exist in any combination with each other, if they are not explicitly described as mutually exclusive. BRIEF DESCRIPTION OF DRAWINGS

[0033] In the following, additional features and advantages of the present application are described in the form of advantageous execution embodiments based on the drawings. Features or combinations of features of the execution embodiments described in the following can exist in any combination with each other and / or with combinations of features of the embodiments. This means that features of the execution embodiments can supplement and / or replace features of the embodiments and vice versa. Thus, configurations are also considered to be covered and disclosed by the present application, which are not explicitly shown or explained in the drawings, but result from and can be generated by combinations of separate features from the execution embodiments and / or the embodiments. Thus, configurations are also considered to be disclosed, which do not include all features of the initially presented claims or extend beyond the feature combinations set forth in the context of the claims. For the execution embodiments, it is shown:

[0034] Figure 1 is a schematic diagram of a treatment device according to an exemplary embodiment;

[0035] Figure 2 is a schematic method diagram of a method according to an exemplary embodiment;

[0036] Figure 3 is a schematic diagram of determining an optimized treatment profile according to an exemplary configuration;

[0037] Figure 4 is a schematic diagram of determining an optimized treatment profile according to another exemplary configuration;

[0038] Figure 5 is a schematic diagram of determining an optimized treatment profile according to another exemplary configuration.

[0039] In the drawings, identical or functionally identical elements have the same reference signs. DETAILED DESCRIPTION

[0040] Figure 1A schematic diagram of a treatment device 10 is shown, which has an ophthalmic laser 12 for reducing geometrical irregularities 14 of a human or animal cornea 16 by means of photodisruption and / or ablation. For example, the geometrical irregularities 14 of the cornea 16 can be caused by inflammation, improper treatment or degeneration of the cornea 16. Therein, the geometrical irregularities 14 can locally change the curvature of the cornea 16, thereby generating higher-order visual disturbances, in particular higher-order aberrations. A control device 18 can provide a treatment profile for correcting the geometrical irregularities 14, in particular in the form of control data, such that the laser 12 emits pulsed laser pulses in a pattern predefined by the control data towards the cornea 16 of the eye. Alternatively, the control device 18 can be a control device 18 located externally with respect to the treatment device 10.

[0041] Furthermore, Figure 1 It is shown that the laser beam 20 generated by the laser 12 can be deflected by a beam deflection device 22, for example a rotating scanner, towards the cornea 16 for removing the geometrical irregularities 14. The beam deflection device 22 can also be controlled by the control device 18.

[0042] The illustrated laser 12 can be a photodisruptive and / or photoablation laser which is formed to emit laser pulses with a respective pulse duration between 1 femtosecond and 1 nanosecond, for example between 10 femtoseconds and 10 picoseconds, and a wavelength range between 300 nanometers and 1400 nanometers, for example between 700 nanometers and 1200 nanometers, and a repetition frequency of the laser pulses of more than 10 kilohertz, for example between 100 kilohertz and 100 megahertz. In addition, the control device 18 optionally comprises a storage device (not shown) for at least temporarily storing at least one control data set, wherein the one or more control data sets comprise control data for positioning and / or for focusing the individual laser pulses in the cornea.

[0043] For determining the control data comprising a treatment profile for reducing or removing the geometrical irregularities 14, the control device 18 can for example perform the method shown in Figure 2 .

[0044] In Figure 2 , a schematic method diagram for providing control data for the ophthalmic laser 12 of the treatment device 10 is shown, wherein the reduction of the geometrical irregularities 14 can be achieved using the method. The method steps described below can in particular be performed by the control device 18 of the treatment device 10 or an external control device for planning the treatment.

[0045] In step S10, geometrical irregularities 14 of the eye can be determined from predetermined examination data, wherein the geometrical irregularities 14 generate higher-order aberrations. For determining the examination data, for example a wavefront measurement and / or a tomographic measurement and / or a topographic measurement of the cornea can be performed.

[0046] In step S12, a treatment profile with a preset optical zone can be determined, wherein an optimization function can be optimized until an optimization range, in particular an optimization value, for the optimization function. In particular, the optimization function can comprise a term for reducing the higher order aberrations and an opposite term for tissue removal, wherein the optimization function can for example be a cost function, which can be iterated to maximize the reduction of the higher order aberrations and to minimize the tissue removal. Thereby, a cornea ideal profile 26 can be defined, for example, which is varied with respect to the measured cornea profile 24 until the higher order aberrations and the tissue removal are minimized. Here, the cornea ideal profile 26 can be directly preset or can be derived from a wavefront ideal profile.

[0047] For example, Figure 3 A configuration for determining a treatment profile by the cornea ideal profile 26 to optimize an optimization function is shown. Here, the cornea profile 24 of the cornea 16 can be determined from a wavefront measurement or a tomography and / or a topography, and the cornea ideal profile 26 can be preset. Therein, the optical zone (not shown) can radially limit the treatment zone or the cornea ideal profile 26, wherein a maximum optical zone, for example a dark pupil, can be preset. Subsequently, the cornea ideal profile 26 and the cornea profile 24 can be superimposed, for example at a preset point or a preset axis, and moved with respect to each other along a perpendicular axis 28 until the optimization function reaches an optimization range. If both the higher order aberrations and the tissue removal are minimized, the position of the cornea ideal profile 26 can be set as the treatment profile, wherein only those areas 30 between the treatment profile or the cornea ideal profile 26 and the cornea profile 24 in the direction of the perpendicular axis 28 are set for removal. This means that the areas 30 can be removed to reduce the geometric irregularities 14.

[0048] In Figure 4 In a further configuration for determining a treatment profile by the cornea ideal profile 26 is schematically shown. In this configuration, the cornea profile 24 of the cornea 16 can again be determined from the examination data in advance, and the cornea ideal profile 26 can be preset. For optimizing the optimization function, in this configuration the cornea ideal profile 26 can be tilted around the perpendicular axis 28, in particular until the optimization function reaches an optimization range. Then, the areas 30 for removal can be set, which are located between the treatment profile or the tilted cornea ideal profile 26 and the cornea profile 24. In this configuration, a situation can occur that the tilted cornea ideal profile 26 generates additional lower order aberrations, but this aberration can be accepted in this configuration, since the lower order aberrations can be compensated by an eyeglass correction.

[0049] Figure 5Another configuration for determining a treatment profile from the corneal ideal profile 26 is shown. After the corneal profile 24 has been determined and the corneal ideal profile 26 has been preset, in this configuration the curvature of the corneal ideal profile 26 can be changed after superimposing the corneal ideal profile 26 with the corneal profile 24 until the optimization function reaches the optimization range. In this embodiment, the corneal ideal profile 26 can be changed to an optimized corneal ideal profile 26' with a lower radius of curvature to reach the optimization range. In particular, different planes, i.e. different radii of curvature of the corneal ideal profile 26, can be adjusted independently from each other to reach the optimization range for the optimization function. Subsequently, the area 30 between the optimized corneal ideal profile 26' and the corneal profile 24 can be set again for removal.

[0050] Figure 3 Figure 4 and Figure 5 The configurations described in ,

[0050] , Figure 3 , Figure 4 and Figure 5 can be combined with each other such that a treatment profile can be determined by optimizing the optimization function which can provide the highest reduction of higher order aberrations and the lowest tissue removal. Furthermore, it can be provided that the tissue removal is limited to a preset value, e.g. a depth of less than 50 pm.

[0051] Finally, control data can be provided in step S14 which comprises at least the determined treatment profile.​

Claims

1. A method for providing control data for an ophthalmic laser (12) of a treatment device (10) to reduce geometric irregularities (14) of the eye, wherein the method comprises the following steps performed by a control device (18): - Determine the geometric irregularity of the eye based on predetermined examination data that produce higher-order aberrations (14); -A treatment profile with a preset optical region is determined based on the geometric irregularity (14), wherein an optimization function is optimized to determine the optimization range of the treatment profile, the optimization function including terms for reducing the higher-order aberrations and the opposite tissue removal terms; - Provide control data, which includes at least the treatment profile.

2. The method according to claim 1, wherein the geometric irregularity (14) is determined by wavefront measurement of the eye, wherein the ideal corneal profile (26) without geometric irregularity and higher-order aberrations is defined by the ideal wavefront profile, wherein the optimization function is optimized based on the ideal corneal profile (26).

3. The method according to claim 1, wherein the geometric irregularity (14) is provided by a corneal profile (24) from a tomographic scan and / or topographic measurement of the cornea of ​​the eye, wherein an ideal corneal profile (26) without geometric irregularity and higher-order aberrations is defined, wherein the optimization function is optimized based on the ideal corneal profile (26).

4. The method according to claim 3, wherein the ideal corneal contour (26) is superimposed on the corneal contour (24) and moved along the vertical axis (28) of the corneal contour (24) to optimize the optimization function until the optimization function reaches the optimization range, wherein only those regions (30) of the corneal contour (24) located above the treatment contour in the direction of the vertical axis (28) are set to be removed.

5. The method according to any one of claims 3 or 4, wherein the ideal corneal contour (26) is superimposed on the corneal contour (24) and tilted relative to the vertical axis (28) of the corneal contour (24) until the optimization function reaches the optimization range, wherein only those regions (30) of the corneal contour (24) located above the treatment contour in the direction of the vertical axis (28) are set to be removed.

6. The method according to any one of claims 3 to 5, wherein the ideal corneal contour (26) is superimposed on the corneal contour (24) and the curvature of the ideal corneal contour (26) is changed until the optimization function reaches the optimization range, wherein only those regions of the corneal contour (24) above the treatment contour are set to be removed.

7. The method according to any one of the preceding claims, wherein the irregularity includes keratoconus, globular keratosis, clear marginal degeneration of the cornea, herpes simplex keratitis and / or improper treatment of the cornea (16).

8. The method according to any one of the preceding claims, wherein the examination data includes wavefront measurements and / or tomographic measurements and / or topographic measurements of the cornea (16), by means of these measurements to determine the geometric irregularity (14) of the cornea (16).

9. The method according to any one of the preceding claims, wherein the maximum depth of tissue removal is limited to less than 50 μm.

10. A control device (18) configured to perform the corresponding method according to any one of the preceding claims.

11. A treatment device (10) comprising: at least one ophthalmic laser (12) for removing corneal volume (30) of a human or animal eye by optical decomposition, particularly by photodestruction and / or photoablation, and at least one control device according to claim 10.

12. A computer program, including commands that cause the therapeutic device (10) according to claim 11 to perform the method according to any one of claims 1 to 9.

13. A computer-readable medium having a computer program thereon according to claim 12.

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