Procedure for adjusting treatment coordinates for treatment with an ophthalmic laser

Abstract

Method for adjusting treatment coordinates for treating an eye (12) with an ophthalmic laser (18) of a treatment device (10), wherein the treatment device (10) comprises a contact element (14) for fixing the eye (12), the method comprising the following steps: - capturing (S10) at least one first image of the eye (12) before the eye (12) is fixed by the contact element (14), and determining treatment coordinates of the eye (12) using the first image; - determining (S12) reference points of the eye (12) and their position in the first image; - capturing (S14) a second image of the eye (12) after the eye (12) has been fixed by the contact element (14), determining the position of the respective reference points in the second image;- Determining (S16) a transformation matrix based on the respective positions of related reference points in the first and second images; - Adjusting (S18) the treatment coordinates using the determined transformation matrix; - whereby the transformation matrix performs a recentering and / or a cyclotorsion correction and / or a deformation correction of the treatment coordinates.;

Description

[0001] The present invention relates to a method for adjusting treatment coordinates for a treatment of an eye with an ophthalmic laser of a treatment device. The invention also relates to a control device for carrying out the method, a treatment device with at least one ophthalmic laser and at least one control device, a computer program, and a computer-readable medium.

[0002] Treatment devices and methods for controlling lasers to correct corneal optical refractive errors are known in the art. For example, a pulsed laser and a beam focusing device can be configured such that laser beam pulses cause photodisruption or optical breakthrough at a focus located within the corneal tissue in order to separate a lenticule from the cornea to correct the cornea. During treatment with a treatment device, for example to separate a lenticule, the eye is usually fixed by one or more contact elements of the treatment device. The contact element can be a rigid element, for example a plano-concave lens, which is placed on the eye, in particular on the cornea, so that the eye is not moved during treatment.Suction rings can also be used as a contact element, which fixes the eye in a fixed position using negative pressure.

[0003] A disadvantage of such contact elements, however, is that the shape and thus the geometry of the cornea changes due to the contact element and thus treatment coordinates that were determined when the cornea was not deformed can be incorrect, which worsens the treatment result.

[0004] The invention is based on the object of improving the treatment of an eye with a treatment device.

[0005] 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.

[0006] A first aspect of the invention relates to a method for adjusting treatment coordinates for a treatment of an eye with an ophthalmic laser of a treatment device, wherein the treatment device comprises a contact element for fixating the eye. The method comprises the steps of acquiring at least one first image of the eye before the eye is fixated by the contact element, determining treatment coordinates of the eye using the first image, and determining landmarks of the eye and their position in the first image.Furthermore, the method comprises capturing a second image of the eye after the eye has been fixed by the contact element, wherein the position of the respective landmarks in the second image is determined, determining a transformation matrix based on the respectively determined positions of associated landmarks in the first and second images, and adjusting the treatment coordinates by the determined transformation matrix.

[0007] Preferably, the treatment coordinates thus adjusted can be provided in a subsequent step as control data of the laser or the treatment device in order to control the laser by means of the control data for correcting a visual defect.

[0008] In other words, the method can involve taking at least a first and a second image of the eye, in which the iris of the eye is preferably visible. The first image can be taken before fixation by the contact element and thus in the non-deformed state. Based on this first image, the treatment coordinates can also preferably be determined, which can be used to correct a refractive error. The treatment coordinates can include, for example, the positions of laser pulses in the cornea.

[0009] The second image of the eye is preferably taken when the eye has been fixed by the contact element, i.e. when it is in a deformed state. In the two images, characteristic orientation points in the eye can then be searched for, such as a structure of the iris of the eye. In this way, an orientation point or landmark can be determined in the first image, and the same orientation point can be searched for in the second image. The deformation caused by the contact element can cause the orientation point to change between the two images, which can be described using a vector. Preferably, for several orientation points or landmarks that appear in pairs in the two images, the respective changes or shifts can be determined, from which a transformation matrix can be calculated.The transformation matrix, which can preferably be an affine matrix, can describe how the orientation points change due to the deformation.

[0010] Finally, the treatment coordinates can be adjusted using the transformation matrix to compensate for any deformation caused by the contact element. When adjusting the treatment coordinates, either planned, undeformed treatment positions can be deformed into new, adjusted treatment positions using the transformation matrix, or the treatment positions in the fixed eye state can be transformed back to an undeformed eye state from which the diagnosis was made, so that the treatment device knows which correction should be applied for these laser points.

[0011] The contact element can fix the eye in place by compressing or flattening the eye and / or can have a suction device that can suck the eye in. The second exposure can be performed in contact with the contact element, either with or without suction.

[0012] The invention provides the advantage that deformation effects can be compensated for in a simple manner, which improves treatment with the treatment device.

[0013] The invention also includes embodiments which provide additional advantages.

[0014] One embodiment provides for an affine transformation to be performed through the transformation matrix. This means that the transformation matrix is ​​an affine matrix that describes a mapping between two affine spaces, preserving colinearity, parallelism, and partial relationships. Thus, rotation, reflection, scaling, shearing, and translation of the treatment coordinates can be described by the transformation matrix, with the mappings being bijective.

[0015] A further embodiment provides that the first image is taken by an external diagnostic device or a recording device of the treatment device, and wherein the second image is taken by the recording device of the treatment device. Thus, the first image can preferably be taken by an external diagnostic device for determining a visual impairment of the eye, where external means that the diagnostic device is not part of the treatment device. Alternatively, the first image can also be taken by a recording device of the treatment device, for example when the patient is lying under the laser, wherein the first image is then taken shortly before docking with the contact element. This image can preferably be taken while observing a coaxial fixation target. Furthermore, the eye can preferably be located close (less than 50 mm) to the contact element.In this first image, the eye is therefore undeformed. In this embodiment, the second image is always taken by the treatment device's imaging device when the eye is docked to the contact element and thus deformed.

[0016] Preferably, the first image is taken by the external diagnostic device, and between the first and second images, a third image of the eye is acquired by the imaging device of the treatment device before the eye is fixated by the contact element. In the third image, the positions of the landmarks are determined, a calibration transformation matrix is ​​determined from the respective positions of related landmarks in the first and third images, and the transformation matrix is ​​adjusted using the calibration transformation matrix. In other words, preferably three images can be taken: the first image by the external diagnostic device, followed by the third image lying under the laser, but before the eye is fixated by the contact element.The third image can be acquired by the imaging device of the treatment device. A calibration transformation matrix can then be determined from the first and third images using related landmarks in the eye, which can be used to determine, in particular, differences between the imaging device of the diagnostic device and the imaging device of the treatment device. Finally, after the third image, the second image can be acquired by the imaging device of the treatment device, and the transformation matrix can be determined using the related landmarks of the first and second images. This transformation matrix can then be adjusted using the calibration transformation matrix, for example, using a matrix product, to describe the transformation of the treatment coordinates between the first image and the second image.Alternatively, the calibration transformation matrix can be determined using the landmarks of the first and third images, followed by another transformation matrix between the landmarks of the second and third images. Overall, the transformation matrix is ​​thus the matrix product of the matrix from images 1 and 3 and the matrix from images 2 and 3. In other words, the third image serves as a bridge image used to calibrate the different imaging devices.

[0017] A further embodiment provides that the respective images are taken in the same spectral range, in particular in the infrared spectral range or the visible spectral range. In other words, the respective images are preferably taken with the same illumination in order to better identify related landmarks. This way, all images can be taken in the infrared spectral range or the visible spectral range. The infrared spectral range can start at wavelengths greater than 690 nm, and the visible spectral range can be approximately in a range between 380 nm and 680 nm. Alternatively, the images can also be taken with different illumination and / or wavelengths if related landmarks can be found in these images. This embodiment offers the advantage that related landmarks can be determined more easily.

[0018] A further embodiment provides for the treatment coordinates to be determined from the first image using a pupil center and / or a limbal ring of the eye. In other words, treatment centering in the image can be determined based on the pupil center and / or the limbal ring, which appears in images as a dark ring around the iris of the eye where the sclera meets the cornea. These positions can preferably also simultaneously serve as landmarks for determining the transformation matrix. This offers the advantage that suitable and retrievable positions can be used to determine the treatment coordinates.

[0019] Another embodiment provides for the landmarks to be determined based on characteristics of the iris of the eye from the respective image. The iris, or iris in the eye, has a unique and characteristic structure for each patient, which is advantageously suited to determining landmarks. These landmarks can then be determined in the respective images, with any change in the landmarks between these images then serving to calculate the transformation matrix. This offers the advantage of improved landmark determination.

[0020] In a further embodiment, the transformation matrix performs a recentering and / or a cyclotorsion correction and / or a deformation correction of the treatment coordinates. In other words, the treatment coordinates are recentered, shifted, rotated, and / or distorted, in particular by shearing or pincushion distortion. Thus, treatment positions in the eye can be adjusted using the transformation matrix to compensate for the deformation.

[0021] A further aspect of the present invention relates to a control device that is configured to carry out the method described above. This means that the control device can be designed to control the recording devices and calculate the transformation matrix. 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 embodiments of the method according to the invention described above.

[0022] A further aspect of the present invention relates to a treatment device comprising at least one ophthalmic surgical laser for the treatment of a human or animal eye, in particular by means of optical breakthroughs and / or ablation and / or laser-induced refractive index change (LIRIC), and at least one control device which is designed to carry out the steps of the method according to the first aspect of the invention.

[0023] 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 900 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). The use of such lasers in the method according to the invention also has the advantage that the irradiation of the cornea does not have to occur in a wavelength range below 300 nm. In laser technology, this range is subsumed under the term "deep ultraviolet". This advantageously prevents unintentional damage to the cornea from these very short-wave and high-energy rays.Photodisruptive and / or ablative 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.

[0024] In further advantageous embodiments of the treatment device, 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.

[0025] 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 other aspect of the invention.

[0026] A further aspect of the invention relates to a computer program comprising instructions which cause the control device to carry out the method steps according to the first aspect of the invention.

[0027] A further aspect of the invention relates to a computer-readable medium (storage medium) on which the aforementioned computer program or its instructions are stored. To execute the computer program, a computer or a computer network can access the computer-readable medium and read its contents. The storage medium is designed, for example, as a data memory, in particular at least partially as a volatile or non-volatile data memory. A non-volatile data memory can be a flash memory and / or an SSD (solid state drive) and / or a hard disk. A volatile data memory can be a RAM (random access memory). The instructions can be present, for example, as source code of a programming language and / or as assembler and / or as binary code.

[0028] Control data for the laser can include a respective data set for positioning and / or focusing individual laser pulses in the cornea. The control data can additionally or alternatively include a respective data set for adjusting 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 respective laser.

[0029] The method may include at least one additional step that is executed precisely when a use case or application situation occurs that has not been explicitly described here. This step may, for example, include outputting an error message and / or a request for user feedback. Additionally or alternatively, it may be provided that a default setting and / or a predetermined initial state is set.

[0030] Additional features and advantages of the invention are described below with reference to the figure(s) in the form of advantageous exemplary embodiments. The features or combinations of features of the exemplary embodiments described below can be present in any combination with one another and / or with the features of the embodiments. This means that the features of the exemplary embodiments can supplement and / or replace the features of the embodiments, and vice versa. Thus, the invention also encompasses and discloses configurations that are not explicitly shown or explained in the figures, but which emerge and can be produced from the exemplary embodiments and / or embodiments through separate combinations of features.Thus, embodiments are also considered to be disclosed that do not have all the features of an originally formulated claim or that go beyond or deviate from the combinations of features set forth in the claims' references. The embodiments are shown in: Fig. 1 shows a schematically illustrated treatment device according to an exemplary embodiment; Fig. 2 a schematic process diagram according to an exemplary embodiment.

[0031] In the figures, identical or functionally identical elements are provided with the same reference numerals.

[0032] The Fig. 1 shows a schematic representation of a treatment device 10 with an ophthalmic laser 18 for treating an eye 12, in particular a cornea of ​​the eye 12 by means of photodisruption and / or ablation and / or laser-induced refractive index change (LIRIC).

[0033] In addition to the laser 18, the treatment device 10 can have a control device 20, which can be configured to control the laser 18 using control data, so that it can emit pulsed laser pulses, for example, in a predefined pattern or at predetermined treatment coordinates for treating the eye 12. Alternatively, the control device 20 can be a control device 20 external to the treatment device 10.

[0034] Furthermore, the Fig. 1, the laser beam 24 generated by the laser 18 can be deflected toward the eye 12 by means of a beam device 22, namely a beam deflection device, such as a rotary scanner. The beam deflection device 22 can also be controlled by the control device 20 to direct the laser beam 24 to a predetermined position in the eye, in particular in the cornea of ​​the eye 12.

[0035] The laser 18 can preferably be a photodisruptive and / or ablative laser 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. The control device 20 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 a cornea of ​​the eye 12. The position data and / or focusing data of individual laser pulses can be generated based on predetermined control data, in particular from a previously measured topography and / or pachymetry and / or morphology.

[0036] Furthermore, the treatment device 10 can have a fixing device or a contact element 14, which is designed to fix the eye 12 to be treated in a position for irradiation with the laser 18. The contact element 14 can, for example, have a suction device 16, wherein the suction device 16 can be a vacuum pump that generates a vacuum on a suction ring or absorbent ring segments on a side of the contact element 14 that is oriented toward the eye 12. In other words, the suction ring can be placed on the eye 12, and the suction device 16, in particular the vacuum pump, can hold the eye 12 in position by generating a negative pressure.

[0037] In addition, the treatment device 10 can comprise a recording device 26 which can in particular capture images of the eye 12, for example in order to center the eye for the laser 18 and to recognize previously determined treatment coordinates.

[0038] Furthermore, a diagnostic device 28 is shown, which comprises at least one recording device 32. The recording device 32 can preferably have the same illumination as the recording device 26 of the treatment device 10. This means that the respective recording devices 26 and 32 take images in the same spectral range, in particular in the infrared spectral range and / or the visible spectral range.

[0039] Thus, by means of the recording device 32 of the diagnostic device 28, a first image of the eye 12 can be acquired, based on which treatment coordinates for the treatment with the ophthalmic laser 18 of the treatment device 10 can be determined. For this purpose, a pupil center and / or a limbal ring can preferably be used to determine the treatment coordinates. Furthermore, orientation points or landmarks in the eye 12 can be determined from the first image, wherein these are preferably determined based on characteristics of the iris or iris of the eye 12. Thus, there are preferably a plurality of unique points in the eye 12 that can be found again in each image.

[0040] Thereafter, when the patient is lying on the patient support device 30 in a treatment position beneath the treatment device 10 and the eye 12 is fixed by the contact element 14, in particular by suction by the suction device 16, a second image of the eye 12 can be captured by the recording device 26 of the treatment device 10. The defined orientation points, which may be at least partially displaced by the fixation by the contact element 14, can then be searched for in this second image.

[0041] From the positions of the associated landmarks, which may be partially shifted between the first and second recording, a transformation matrix, in particular an affine transformation matrix, can then be determined, which describes a shift of the landmarks and thus the deformation of the eye 12.

[0042] To compensate for this deformation, the treatment coordinates determined by the diagnostic device 28 can be adjusted using the previously determined transformation matrix. This means that, for example, planned undeformed treatment positions can be calculated into new adjusted treatment positions using the transformation matrix, or the treatment positions in the fixed state of the eye 12 are transformed back to an undeformed state of the eye 12 using the transformation matrix, so that the treatment device 10 knows which correction should apply for these treatment positions.

[0043] Particularly preferably, a third image can also be taken between the first image and the second image, wherein the third image is taken by the recording device 26 of the treatment device 10, preferably shortly before the patient is treated by the treatment device 10, but the eye 12 has not yet been fixed by the contact element 14. In this case, the eye 12 can preferably be located close to the contact element 14, for example in an area less than 50 mm away. The respective associated landmarks can then be searched for from the first image, which was taken by the recording device 32 of the diagnostic device 28, and the third image in the unfixed state, and any deviations can be described by means of a calibration transformation matrix.Thus, the recording device 32 of the diagnostic device 28 and the recording device 26 of the treatment device 10 can preferably be calibrated to each other. This calibration transformation matrix can then be used to adapt and thus improve the transformation matrix.

[0044] In Fig. Figure 2 shows a schematic process diagram for adjusting treatment coordinates for a treatment of an eye 12 with an ophthalmic laser 18 of a treatment device 10. In a step S10, at least a first image of the eye 12 is taken before the eye is fixed by a contact element 14 of the treatment device 10. Furthermore, treatment coordinates of the eye 12 are determined using the first image.

[0045] In a step S12, landmarks of the eye 12 and their positions are determined in the first image. The landmarks can be characteristics of an iris of the eye 12.

[0046] In a step S14, a second image of the eye 12 is taken after the eye 12 has been fixed by the contact element 14. The fixation can be achieved with or without suction by a suction device 16. From this second image, the positions of the respective orientation points are then determined again.

[0047] In a step S16, a transformation matrix is ​​determined by comparing the respective positions of associated landmarks in the first and second images, wherein a deviation of the positions of the associated landmarks describes the transformation by the transformation matrix.

[0048] Finally, in a step S18, the treatment coordinates can be adjusted using the determined transformation matrix in order to adjust the irradiation positions by the laser 18 and compensate for the deformation caused by the contact element 14. The adjusted treatment coordinates, which can be present as control data, can then be used to control the laser 18.

[0049] In a further exemplary embodiment, it is provided that images of the eye 12 are recorded, for example, by a diagnostic device 28. Alternatively, when the patient is located at the treatment device 10, at least one image of the eye 12 can be recorded, in particular with infrared or visual illumination, while the eye 12 has not yet been fixated by the contact element 14, but is close to it, and while a coaxial fixation target is viewed. The pupil center can be detected from the images, in particular from the diagnostic image or the image under the laser, or both, and the desired treatment centering can be determined in the images, for example, depending on the pupil center or the limbal ring. Furthermore, peripheral landmarks, for example on the iris, can be detected from the images before fixation of the eye 12.

[0050] Another image, preferably with the same wavelength region in the infrared or visual spectral range, is acquired after the eye has docked onto the contact element 14 and a suction device 16 fixates and holds the eye. From this image, the landmarks can then be searched for and registered. From this image, an (affine) transformation matrix can be generated, which is generated from the detected positions of the landmarks in the images before and after fixation by the contact element 14. The treatment coordinates determined in the image before fixation can thus be transformed into the image after fixation using the (affine) transformation matrix.An offset of the (affine) transformation matrix corresponds to a treatment centering, a rotation angle calculated from the (affine) transformation matrix can be used to correct a cyclotorsion axis and the transformation matrix can, for example, compensate for shear and pincushion distortion for the treatment positions.

[0051] In this way, deformation compensation can be achieved without theoretical / simulated models or statistical empirical corrections.

[0052] Overall, the examples show how affine corneal registration can be carried out using the invention.

Claims

[1] Method for adjusting treatment coordinates for a treatment of an eye (12) with an ophthalmic laser (18) of a treatment device (10), wherein the treatment device (10) comprises a contact element (14) for fixing the eye (12), the method comprising the following steps: - capturing (S10) at least a first image of the eye (12) before the eye (12) is fixed by the contact element (14), and determining treatment coordinates of the eye (12) by means of the first image; - determining (S12) landmarks of the eye (12) and their position in the first image; - capturing (S14) a second image of the eye (12) after the eye (12) has been fixed by the contact element (14), wherein the position of the respective orientation points in the second image is determined; - determining (S16) a transformation matrix based on the respectively determined positions of related landmarks in the first and second images; - Adjusting (S18) the treatment coordinates using the determined transformation matrix. [2] Method according to claim 1, wherein an affine transformation is performed by the transformation matrix. [3] Method according to one of the preceding claims, wherein the first recording is carried out by an external diagnostic device (28) or a recording device (26) of the treatment device (10) and wherein the second recording is carried out by the recording device (26) of the treatment device (10). [4] Method according to claim 3, wherein the first recording is carried out by the external diagnostic device (28) and between the first and second recordings a third recording of the eye (12) is acquired by the recording device (26) of the treatment device (10) before the eye (12) is fixed by the contact element (14), wherein the positions of the orientation points are determined in the third recording, wherein a calibration transformation matrix is ​​determined from the respective positions of associated orientation points in the first and third recordings, wherein the transformation matrix is ​​adapted by means of the calibration transformation matrix. [5] Method according to one of the preceding claims, wherein the respective recordings are carried out in the same spectral range, in particular in the infrared spectral range or in the visible spectral range. [6] Method according to one of the preceding claims, wherein the treatment coordinates are determined from the first image by means of a pupil center and / or a limbal ring of the eye. [7] Method according to one of the preceding claims, wherein the orientation points are determined from the respective image based on characteristics of the iris of the eye (12). [8] Method according to one of the preceding claims, wherein a re-centering and / or a cyclotorsion correction and / or a deformation correction of the treatment coordinates is carried out by the transformation matrix. [9] Control device (20) which is arranged to carry out a method according to one of the preceding claims. [10] Treatment device (10) with at least one ophthalmological laser (18) for the treatment of a human or animal eye (12) and at least one control device (20) according to claim 9. [11] A computer program comprising instructions causing the control device (20) according to claim 9 to execute a method according to any one of claims 1 to 8. [12] A computer-readable medium on which a computer program according to claim 11 is stored.

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