Method for providing control data for an ophthalmic surgical laser of a treatment device

Abstract

Method for providing control data for an ophthalmic surgical laser (12) of a treatment device (10) for the removal of tissue (14), wherein the method comprises the following steps performed by a control device (18): - Determining (S10) a corneal geometry of a cornea of ​​a human or animal eye (16) from predetermined examination data; - Determining (S12) a tissue geometry of the tissue to be removed (14) from the predetermined examination data; - Determining (S14) a target corneal geometry expected by removing the tissue (14) from the cornea; - Determining (S16) a transition region geometry of a transition region (28) depending on the target corneal geometry, wherein the transition region (28) provides a transition between the tissue (14) to be removed and the cornea; - Providing (S18) control data for controlling the ophthalmic surgical laser (12) using the tissue geometry and transition area geometry for tissue removal (14).

Description

[0001] The present invention relates to a method for providing control data for an ophthalmic surgical laser of a treatment device for removing tissue. The invention also relates to a treatment device comprising at least one ophthalmic surgical laser and at least one control device for carrying out the method, a computer program, and a computer-readable medium.

[0002] Treatment devices and methods for controlling ophthalmic lasers to correct optical refractive errors and / or pathologically or abnormally altered areas of the cornea are known in the prior art. For example, a pulsed laser and a beam focusing device can be configured such that laser pulses in a focus located within the organic tissue cause photodisruption and / or photoablation in order to remove tissue, in particular a tissue lenticle, from the cornea. To ensure that the transition from the removed tissue to the cornea is not too abrupt, for example, too steep, a transition zone is usually provided in the edge regions of the tissue to be removed, which provides a smooth transition for the tissue to be removed into the cornea.

[0003] US 2019 / 0209379 A1 discloses a treatment device for surgically correcting a refractive error of an eye. The device comprises a laser device controlled by a control unit. The control unit determines a desired correction of the refractive error using measurement data of the eye to generate control data for the laser and to control the laser to emit radiation according to the control data, thereby isolating a lenticule-shaped volume in the cornea. The control unit calculates a lenticule-shaped target volume whose distance from the cornea results in the actual correction of the refractive error in an optical zone of the eye, which differs more from the intended correction at the edges of the optical zone than in the center of the optical zone.

[0004] WO 2017 / 091200 A1 discloses a method and system for eye measurements and cataract surgery planning using vector functions derived from previous operations.

[0005] The invention is based on the object of providing control data for controlling an ophthalmic surgical laser with an improved adapted transition region, in particular an improved adapted transition region geometry.

[0006] This object is achieved by the method according to the invention, the devices according to the invention, the computer program according to the invention, and the computer-readable medium according to the invention. Advantageous embodiments with expedient refinements of the invention are specified in the respective subclaims, wherein advantageous embodiments of the method are to be regarded as advantageous embodiments of the treatment device, the control device, the computer program, and the computer-readable medium, and vice versa.

[0007] A first aspect of the invention relates to a method for providing control data for an ophthalmic laser of a treatment device for removing tissue, wherein the method comprises the following steps performed by a control device. A control device is understood to be a device, a device component, or a device group configured to receive and evaluate signals and to provide, for example, generate, control data. The control device can be configured, for example, as a control chip, computer program, computer program product, or control unit.The control device determines a corneal geometry of a human or animal eye from predetermined examination data, determines a tissue geometry of the tissue to be removed from the predetermined examination data, and determines a target corneal geometry expected from the removal of the tissue from the cornea. Furthermore, the control device determines a transition region geometry of a transition region depending on the target corneal geometry, wherein the transition region provides a transition between the tissue to be removed and the cornea, and provides control data for controlling the ophthalmic laser, which data uses the tissue geometry and the transition region geometry to remove the tissue.

[0008] In other words, a corneal geometry and a tissue geometry of the tissue to be removed are first determined from previously determined examination data. In particular, the respective geometry contains information about dimensions and shapes, in particular a volume, a thickness, a diameter and / or a position. The examination data can, for example, describe an ametropia, i.e. a deviation of the refractive power of an eye or a cornea from the ideal value, for example, nearsightedness, farsightedness, or astigmatism. The examination data can, for example, describe a refractive power value, i.e., a value in diopters, or, for example, a deviation of a corneal curvature from a normal value.The examination data can be obtained, for example, by retrieving the examination data from a data storage or data server, or the examination data can be received, for example, from a measuring device that measures the cornea and / or determines ametropia. The tissue geometry of the tissue to be removed can describe a dimension and position of the tissue within the cornea that is to be removed from the cornea to provide correction for a refractive error and / or a pathologically altered area of ​​the cornea.

[0009] The cornea expected as a result of tissue removal, i.e., the target corneal geometry, can be determined in a subsequent method step. In particular, the target corneal geometry can be determined by subtracting the tissue geometry from the determined corneal geometry. In a further method step, a transition region geometry for a transition region from the tissue to be removed to the cornea is then determined depending on the target corneal geometry. This means that the transition region geometry is individually adapted to the patient's respective cornea, in particular to the target corneal geometry, i.e., the geometry expected for the cornea after the tissue has been removed. Preferably, the gradient of the cornea, i.e., the steepness of the cornea expected after treatment, can be taken into account for this purpose.In particular, the transition area is not adapted exclusively to the tissue to be removed, as has been the case up to now. Instead, the adaptation options permitted by the target corneal geometry are taken into account for the transition area. The transition area geometry thus determined can then be provided by the control unit, together with the tissue geometry, as control data for controlling the ophthalmic laser of the treatment device.

[0010] The invention offers the advantage that the transition area geometry can be adjusted depending on the target corneal geometry, thus tailoring the transition area to the individual eye or cornea. This can improve treatment success and patient safety, as it is easier to determine whether too much of the cornea is removed. Instead of adapting a transition area uniformly around the tissue to be removed, the transition area can be adjusted to be flatter, depending on the target corneal geometry, and thus more gentle on the patient.

[0011] The invention also includes embodiments which provide additional advantages.

[0012] According to an advantageous embodiment, it is provided that a difference between the corneal geometry and the tissue geometry, in particular an optical zone of a tissue lenticle, is modeled to determine the target corneal geometry. This means that the target corneal geometry results from a subtraction of the tissue geometry from the corneal geometry. In particular, an optical zone of a tissue lenticle with a predetermined diameter and a predetermined thickness can be subtracted from the corneal geometry to obtain the target corneal geometry. The optical zone is understood to be the area of ​​the cornea that is to be treated to correct the refractive error. This then provides the target corneal geometry expected from the treatment, in which, for example, the refractive error is corrected and with which the transition region can be better modeled.

[0013] Preferably, the transition region geometry is adapted to a geometry and / or morphology and / or thickness of the target corneal geometry. In other words, the transition region geometry takes into account the appearance of the target corneal geometry, and the transition region geometry can be adapted accordingly. In particular, the transition region geometry can be adapted to the target corneal geometry in such a way that the thickness of the cornea does not fall below a predetermined value and the transition region is as flat as possible. Alternatively or additionally, a structure of the cornea can also be taken into account, so that the transition region, for example, does not run through predetermined tissue layers.Adapting the transition area geometry to the geometry and / or morphology and / or thickness of the target corneal geometry has the advantage that the transition area can be individually adapted, thereby improving safety and treatment outcome.

[0014] According to a further advantageous embodiment, a gradient of the transition region is adapted depending on the target corneal geometry. This means that the steepness of the transition region is modeled according to the remaining target corneal geometry, so that gradients that are preferably as flat as possible can be achieved and thus tissue removal for the cornea can be reduced. The gradient can be a parameter of the transition region geometry. Advantageously, the gradient is adapted to the target corneal geometry in such a way that a thickness and / or gradient of the cornea does not fall below or above a predetermined safety value.

[0015] It is advantageous if the gradient is specified with a linear and / or non-linear course, with a maximum gradient value of the gradient being 10 diopters per millimeter. In other words, the gradient is adjusted such that the gradient value is below 10 diopters per millimeter. In particular, this can be used to adjust the thickness of the transition region. For example, the gradient can be linear and fall from -5 diopters to 0 diopters. A gradient of 5 diopters per millimeter can be used here, resulting in a transition region diameter of 1 millimeter. Alternatively or additionally, the gradient of the transition region can also be linear in some areas and then have a non-linear course.For example, the gradient of the transition region can initially be linear and then change to a non-linear gradient in a second section to utilize a width specified by the target corneal geometry. The gradient can therefore, for example, change a gradient value within the gradient. This offers the advantage that the gradient of the transition region can be individually adjusted according to the target corneal geometry, thus keeping the gradient as small as possible.

[0016] According to a further advantageous embodiment, the transition region is delimited in a radial direction of the eye by an inner boundary and an outer boundary, wherein the inner boundary is predetermined by an end of an optical zone of the tissue to be removed and the outer boundary is determined depending on the target corneal geometry. In other words, the transition region begins at the outer edge of an optical zone of the tissue to be removed and extends outwards in the radial direction of the eye depending on the target corneal geometry. In particular, the outer boundary of the transition region can be variably adapted depending on the existing target corneal geometry. This results in the advantage that the transition region, in particular a gradient of the transition region, can be optimally adapted to the available corneal tissue.

[0017] It is advantageous that each point of the outer boundary is determined by a radial length dependent on the target corneal geometry, wherein the radial length is a distance from a central point of the cornea to the respective point of the outer boundary. The central point of the cornea can preferably be a center of an optical axis and / or a geometric axis of the cornea. This means that the outer boundary can vary point by point and is adjusted by a distance from the central point outwards to the respective point of the outer boundary, depending on how much space is provided outwards by the target corneal geometry. Thus, the outer boundary can be optimally adapted to the existing target corneal geometry.

[0018] It is also advantageous if the transition region is defined by a substantially oval ring, in particular by an elliptical ring or a circular ring. A ring here refers to an area that, in the case of a circular ring, lies within two different radial lengths. The transition region can therefore comprise a closed body that can be arranged concentrically or non-concentrically to the tissue to be removed and is selected depending on the target corneal geometry. This has the advantage that the transition region can be adapted to the target corneal geometry while simultaneously ensuring continuity and deflectability, thus simplifying laser beam guidance.

[0019] A second aspect of the present invention relates to a control device that is configured to carry out one of the methods described above. This results in the advantages listed above. The control device can be designed, for example, as a control chip, control unit, or user program (“app”). The control device can preferably have a processor device and / or a data memory. A processor device is understood to be a device or device component for electronic data processing. The processor device can, for example, have at least one microcontroller and / or at least one microprocessor. A program code for carrying out the method according to the invention can preferably be stored on the optional data memory.The program code can then be designed, when executed by the processor device, to cause the control device to carry out one of the above-described embodiments of one or both of the methods according to the invention.

[0020] A third aspect of the present invention relates to a treatment device comprising at least one ophthalmic surgical laser for separating a tissue predefined by the control data, in particular a corneal volume with predefined interfaces of a human or animal eye by means of photodisruption and / or photoablation, and at least one control device for the laser(s) configured to carry out the steps of the method according to the first aspect of the invention. The treatment device according to the invention makes it possible to reliably reduce or even avoid the disadvantages that occur when using conventional ablative treatment devices.

[0021] In a further advantageous embodiment of the treatment device according to the invention, the laser can be suitable for emitting laser pulses in a wavelength range between 300 nm and 1400 nm, preferably between 700 nm and 1200 nm, with a respective pulse duration between 1 fs and 1 ns, preferably between 10 fs and 10 ps, ​​and a repetition frequency greater than 10 kilohertz (kHz), preferably between 100 kHz and 100 megahertz (MHz). Such a femtosecond laser is particularly well suited for removing tissue within the cornea. The use of photodisruptive and / or photoablative lasers in the method according to the invention also has the advantage that the cornea does not have to be irradiated in a wavelength range below 300 nm. In laser technology, this range is referred to as "deep ultraviolet."This advantageously prevents unintentional damage to the cornea caused by these very short-wave and high-energy beams. Photodisruptive lasers of the type used here typically deliver pulsed laser radiation with a pulse duration between 1 fs and 1 ns into the corneal tissue. This allows the power density of the respective laser pulse required for optical breakthrough to be spatially limited, enabling high cutting precision when creating the interfaces. The wavelength range between 700 nm and 780 nm can also be selected.

[0022] In further advantageous embodiments of the treatment device according to the invention, the control device can have at least one storage device for at least temporarily storing at least one control data set, wherein the control data set(s) comprise control data for positioning and / or focusing individual laser pulses in the cornea; and can have at least one beam device for beam guidance and / or beam shaping and / or beam deflection and / or beam focusing of a laser beam of the laser. Said control data set comprises the control data for tissue removal determined in the method.

[0023] Further features and their advantages can be found in the descriptions of the first aspect of the invention, wherein advantageous embodiments of each aspect of the invention are to be regarded as advantageous embodiments of the respective other aspect of the invention.

[0024] A fourth aspect of the invention relates to a computer program comprising instructions which cause the treatment device according to the fourth aspect of the invention to carry out the method steps according to the first aspect of the invention and / or the method steps according to the second aspect of the invention.

[0025] A fifth aspect of the invention relates to a computer-readable medium on which the computer program according to the fourth aspect of the invention is stored. Further features and their advantages can be found in the descriptions of the first to fourth aspects of the invention, with advantageous embodiments of each aspect of the invention being regarded as advantageous embodiments of the other aspect of the invention.

[0026] Further features of the invention emerge from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respective combination specified, but also in other combinations without departing from the scope of the invention. Thus, embodiments are to be regarded as encompassed and disclosed by the invention that are not explicitly shown and explained in the figures, but which emerge and can be produced by separate combinations of features from the explained embodiments. Embodiments and combinations of features are also to be regarded as disclosed that therefore do not have all the features of an originally formulated independent claim.Furthermore, embodiments and combinations of features are to be considered disclosed, in particular by the embodiments presented above, which go beyond or deviate from the combinations of features presented in the claims. This shows: . Fig. 1 a schematic representation of a treatment device according to the invention according to an exemplary embodiment. Fig. 2 is a schematic process diagram according to an exemplary embodiment; Fig. 3 a top view of a schematically represented eye.

[0027] In the figures, identical or functionally identical elements are provided with the same reference numerals.

[0028] The Fig. 1 shows a schematic representation of a treatment device 10 with an ophthalmic laser 12 for removing tissue 14 from a human or animal eye 16 by means of photodisruption and / or photoablation. The tissue 14 can, for example, represent a lenticule or solid body that can be severed from a cornea of ​​the eye 16 with the ophthalmic laser 12 to correct a visual impairment. A geometry of the tissue 14 to be removed can be provided by a control device 18, in particular in the form of control data, so that the laser 12 emits pulsed laser pulses into the cornea of ​​the eye 16 in a pattern predefined by the control data in order to remove the tissue 14. Alternatively, the control device 18 can be a control device 18 external to the treatment device 10.

[0029] Furthermore, the Fig. 1, the laser beam 20 generated by the laser 12 can be deflected toward the eye 16 by a beam device 22, namely a beam deflection device such as a rotary scanner, in order to remove the tissue 14. The beam deflection device 22 can also be controlled by the control device 18 to remove the tissue 14.

[0030] The laser 12 shown can preferably be a photodisruptive and / or photoablative laser configured to emit laser pulses in a wavelength range between 300 nanometers and 1400 nanometers, preferably between 700 nanometers and 1200 nanometers, with a respective pulse duration between 1 femtosecond and 1 nanosecond, preferably between 10 femtoseconds and 10 picoseconds, and a repetition frequency greater than 10 kilohertz, preferably between 100 kilohertz and 100 megahertz. The control device 18 optionally also has a memory device (not shown) for at least temporarily storing at least one control data set, wherein the control data set(s) comprise control data for positioning and / or focusing individual laser pulses in the cornea.The position data and / or focusing data of the individual laser pulses, i.e. the geometry of the tissue 14, is determined using the method described below.

[0031] In Fig. 2 shows a schematic process diagram for providing control data for the ophthalmic laser 12 of the treatment device 10 for the removal of tissue 14. In a step S10, a corneal geometry of a cornea of ​​a human or animal eye 16 is determined from predetermined examination data. The corneal geometry can be determined, for example, by means of a topography measurement. Subsequently, in a step S12, a tissue geometry of the tissue to be removed can be determined from the predetermined examination data. The tissue geometry can, in particular, serve to correct a visual impairment and, for this purpose, can have a diameter and a predetermined thickness predetermined by the examination data. Subsequently, in a step S14, a target corneal geometry can be determined, which is expected to result from the removal of the tissue from the cornea.In particular, the tissue geometry can be subtracted from the corneal geometry to obtain the target corneal geometry. The target corneal geometry represents the corneal geometry expected after treatment.

[0032] Based on the target corneal geometry, a transition region geometry of a transition region 28 can be determined in a step S16, wherein the transition region 28 is intended to provide a transition between the tissue 14 to be removed and the cornea. This means that, in particular, excessively steep transitions, such as steps, in the cornea are to be avoided in order to prevent optical artifacts after the treatment. The modeling of the transition region geometry is intended to be adapted to a geometry and / or morphology and / or thickness of the target corneal geometry. In particular, the target corneal geometry can be different for each patient, in particular for each eye 16, and the respective transition region geometry can be adapted to the respective target corneal geometry.For example, a target corneal geometry, i.e., the resulting cornea, can be asymmetrical, which also allows the transition region 28 to be asymmetrical. In particular, the transition region 28 can have more space in one direction to compensate for a difference in the cornea, allowing a gradient of the transition region geometry to be selected to be flatter than in other regions of the cornea.

[0033] For explanation, Fig. 3 shows a plan view of a schematically illustrated eye 16. The representation of the eye 16 comprises the tissue 14 to be removed, which can be designed, for example, as a lenticule with an optical zone for correcting a visual impairment, and the transition region 28. The transition region 28 can be arranged at the edges of the tissue 14 to be removed and have the transition region geometry dependent on the target corneal geometry, wherein an inner boundary profile 30 of the transition region 28 can be predetermined by an end of the tissue 14 to be removed, in particular by an end of the optical zone of the tissue 14 to be removed, and an outer boundary profile 32 of the transition region 28 is determined depending on the target corneal geometry.

[0034] In this exemplary embodiment, the transition region 28 is depicted as a circular ring. However, the target corneal geometry can also, for example, specify that the cornea has more space in a radial direction of the eye 16, whereby the transition region 28 can be extended in this direction and thus form a substantially oval or elliptical ring. In particular, a gradient of the transition region 28 between the inner boundary line 30 and the outer boundary line 32 can be adapted to the target corneal geometry such that the available space in the radial direction is optimally utilized and the gradient is as flat as possible. Preferably, the gradient of the transition region 28 can be selected such that a thickness from the inner boundary line 30 to the outer boundary line 32 is reduced to zero diopters in order to provide a transition from the tissue 14 to be removed to the cornea.In particular, it can be specified that a gradient of the transition region 28 is less than 10 diopters per millimeter. The gradient can preferably be linear and / or non-linear depending on the target corneal geometry, i.e., depending on the available space specified by the target corneal geometry, and can be configured, for example, linear and / or non-linear. In particular, the gradient can be variably and gradually adjusted within the transition region 28 to provide a transition into the cornea.

[0035] Particularly preferably, a respective point of the outer boundary line 32 can be individually determined depending on the target corneal geometry. This means that a radial length from a central point of the cornea, for example, a center of an optical axis and / or a geometric axis of the cornea, to the respective point of the outer boundary line 32 can be individually selected. Thus, a different width and / or a different gradient can be selected point by point for each point of the outer boundary line 32, whereby the transition region 28 can be particularly well adapted to the target corneal geometry.

[0036] Referring again to Fig. 2, finally, in a step S18, control data for controlling the ophthalmic surgical laser 12, which uses the tissue geometry and the transition region geometry for removing the tissue 14, can be provided.

[0037] Overall, the examples show how the invention can provide a minimal gradient for a transition region 28 depending on a target corneal geometry.

Claims

[1] Method for providing control data for an ophthalmic surgical laser (12) of a treatment device (10) for the removal of a tissue (14), the method comprising the following steps carried out by a control device (18): - determining (S10) a corneal geometry of a cornea of a human or animal eye (16) from predetermined examination data; - determining (S12) a tissue geometry of the tissue (14) to be removed from the predetermined examination data; - determining (S14) a target corneal geometry expected by removing the tissue (14) from the cornea; - determining (S16) a transition region geometry of a transition region (28) as a function of the target cornea geometry, wherein the transition region (28) provides a transition between the tissue (14) to be removed and the cornea; - Providing (S18) control data for controlling the ophthalmic surgical laser (12) using the tissue geometry and the transition region geometry for removing the tissue (14). [2] Method according to claim 1, characterized by that in order to determine the target corneal geometry, a difference between the corneal geometry and the tissue geometry, in particular an optical zone of a tissue lenticle, is modeled. [3] Method according to one of the preceding claims, characterized by that the transition region geometry is adapted to a geometry and / or morphology and / or thickness of the target corneal geometry. [4] Method according to one of the preceding claims, characterized by that a gradient of the transition region (28) is adapted depending on the target corneal geometry. [5] Method according to claim 4, characterized bythat the gradient is specified with a linear and / or non-linear course, with a maximum gradient value of 10 diopters per millimeter. [6] Method according to one of the preceding claims, characterized by that the transition region (28) is delimited in a radial direction of the eye (16) by an inner boundary course (30) and an outer boundary course (32), wherein the inner boundary course (30) is predetermined by an end of an optical zone of the tissue (14) to be removed and the outer boundary course (32) is determined as a function of the target corneal geometry. [7] Method according to claim 6, characterized by that a respective point of the outer boundary course (32) is determined by a radial length dependent on the target cornea geometry, wherein the radial length is a distance from a center point of the cornea to the respective point of the outer boundary course. [8] Method according to claim 7, characterized by that the center point of the cornea is a center of an optical axis and / or a geometric axis of the cornea. [9] Method according to claims 6 to 8, characterized by that the transition region (28) is defined by a substantially oval ring, in particular by an elliptical ring or a circular ring. [10] Control device (18) designed to carry out a method according to one of the preceding claims. [11] Treatment device (10) with at least one ophthalmic surgical laser (12) for the removal of a tissue (14) of a human or animal eye (16), in particular a tissue lenticle, by means of photodisruption and / or photoablation and at least one control device (18) according to claim 10. [12] Treatment device (10) according to claim 11, characterized bythat the laser is designed to emit laser pulses in a wavelength range between 300 nm and 1400 nm, preferably between 700 nm and 1200 nm, with a respective pulse duration between 1 fs and 1 ns, preferably between 10 fs and 10 ps, and a repetition frequency greater than 10 kHz, preferably between 100 kHz and 100 MHz. [13] Treatment device (10) according to one of claims 11 or 12, characterized by that the control device (18) - at least one storage device for at least temporarily storing at least one control data set, wherein the control data set(s) comprise control data for positioning and / or focusing individual laser pulses in the cornea; and - at least one beam device (22) for beam guidance and / or beam shaping and / or beam deflection and / or beam focusing of a laser beam (20) of the laser (12). [14] Computer program comprising instructions causing the treatment device (10) according to one of claims 11 to 13 to carry out a method according to one of claims 1 to 9. [15] A computer-readable medium on which the computer program according to claim 14 is stored.

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