Method for predicting the future position of a target point of an eye to compensate for the latency of image evaluation; control device and treatment device

Abstract

Method for controlling an ophthalmic surgical laser (12) of a treatment device (10) during treatment of a cornea of ​​a human or animal eye (16) depending on a position and / or orientation of a target point of the eye (16), wherein the method comprises the following steps: - Capturing (S1) a respective image of the eye (16) at least at a first time point and a later second time point, - Determining (S2) motion information regarding a movement of the eye (16) and / or the target point based on the respective images, and - Determining (S3) forecast data which includes a forecast for a future position and / or orientation of the target point at a later time, based on the motion information, wherein the later time is temporally separated from the second time by a time interval, the duration of which is derived at least from a latency of an image evaluation, in particular the steps S1 and / or S2 and / or S3; - Determining (S4) a position specification for a laser pulse at least as a function of the prediction data, and - Adjusting (S5) the laser (12) according to the position specification; - wherein at a third time point a third image of the eye (16) is captured, the third time point being temporally after the second time point but before the later time point, wherein the prognosis, which is part of the prognostic data, is checked at least as a function of the third image; and - depending on the result of checking the prediction, the laser pulse is released for the position specification previously set on the basis of the prediction data (S8.1) or a resetting of the laser (12) to an updated position specification is ordered (S8.2).

Description

[0001] The invention relates to a method for controlling an ophthalmic surgical laser of a treatment device during a treatment of a cornea of ​​a human or animal eye depending on the position and / or orientation of a target point of the eye. A second aspect of the invention relates to a control device. A further aspect of the present invention relates to a treatment device. Furthermore, the invention also relates to 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 a patient's cornea are known in the prior art. For example, a pulsed laser and a beam device can be configured such that laser pulses cause photodisruption and / or photoablation at a focus located within the organic tissue to remove tissue, in particular a tissue lenticle, from the cornea.

[0003] To achieve optimal treatment results, it is necessary for the laser pulses to reach a target point on the eye, especially the cornea, with the greatest possible precision. To achieve the highest possible accuracy, it is advantageous if the eye is detected, especially continuously, by a detection device. This can also be referred to as tracking. In other words, the eye's movement can be tracked. The eye's movement can then be used to determine the respective target point for the laser pulses.

[0004] EP 1 923 026 B1 discloses a system for ablating the cornea of ​​an eye. Target targets are defined for each laser pulse prior to ablating the cornea. Based on the delayed signals received from an eye tracker, the distribution of the laser pulses to the actual target locations is calculated. To correct errors, additional laser pulses with associated target locations can then be defined.

[0005] From DE 10 2005 025 462 A1, a method for improving the performance of an eye position measuring system is known, the method comprising: calculating a future eye position based on a measurement of previous eye positions; using the calculated prediction of a future eye position to reduce the latency effect of the eye position measuring system.

[0006] Systems for applying and monitoring eye therapy are known from EP 2 547 298 B1.

[0007] From EP 2 497 414 A1 an image photography device is known, comprising a detection unit configured to detect an image of an eye to be examined, a measuring unit configured to measure a movement of the eye to be examined on the basis of the image, a prediction unit configured to predict the movement of the eye to be examined on the basis of a cycle of movement of the eye to be examined measured by the measuring unit, and a control unit configured to control a detection position at which the detection unit detects the image on the basis of the movement of the eye to be examined predicted by the prediction unit.

[0008] From US 2019 / 0175281 A1, a device for surgically correcting the ametropia of an eye and a method for generating control data therefor are known.

[0009] It is an object of the present invention to enable improved targeting accuracy for triggering a laser pulse at a respective target point.

[0010] This object is achieved according to the invention by the subject matter of the independent patent claims. Advantageous embodiments with useful further developments are the subject matter of the dependent claims.

[0011] The invention relates to a method for controlling an ophthalmic surgical laser of a treatment device during a treatment of a cornea of ​​a human or animal eye depending on a position and / or orientation of a target point of the eye.

[0012] The procedure comprises the following steps: - capturing a respective image of the eye at least at a first point in time and a later second point in time, - Determining movement information regarding a movement of the eye and / or the target point based on the respective images, - Determining forecast data containing a forecast for a future position and / or orientation of the target point at a later time based on the movement information, wherein the later time is spaced from the second time by a period of time whose duration is derived at least from a latency of an image evaluation, in particular steps S1 and / or S2 and / or S3, - Determining a position specification for a laser pulse at least as a function of the forecast data, and - Adjust the laser according to the specified position.

[0013] The forecast for the future position and / or orientation of the target point is thus used to determine the specified position for the laser pulse. For example, the specified position for the laser pulse can be defined in a coordinate system aligned with the eye or the cornea. In this example, the movement of the eye can lead to a relative movement between the coordinate system aligned with the eye and a world coordinate system or a coordinate system aligned with a treatment device for carrying out the treatment. Thus, the specified position for the laser pulse can be determined, for example, taking into account the forecast data, in particular the future positions of the eye and / or the target point, in the world coordinate system or the coordinate system aligned with the treatment device.The laser, in particular the ophthalmic surgical laser, can then be adjusted and / or aligned according to the specified position. Adjusting or aligning the ophthalmic surgical laser can, for example, include aligning or adjusting a beam device for beam guidance and / or beam shaping and / or beam deflection and / or beam focusing of a laser beam. For example, the future laser pulse can be aligned to the target point by appropriately controlling the beam device according to the specified position.

[0014] The respective images of the eye can each be images generated using any desired, preferably imaging, detection method. For example, the detection method can be thermography, ultrasound sensor technology, or any other imaging method. Preferably, the images of the eye are respective camera images. In other words, respective camera images of the eye can be captured at least at the first point in time and the later second point in time. This can be done, for example, using a camera. In particular, the images or camera images are each different individual images (“frames”) of a moving image or a video signal. In particular, the images are each a digital image, for example an image file or a video file.In particular, a camera can capture a continuous video signal, wherein the respective images can be part of the video signal, in particular individual images or frames of the video signal.

[0015] The image captured at the first point in time can represent or image the eye or its cornea at the first point in time or at the first point in time. The image captured at the first point in time is also referred to below as the first image. The image of the eye captured at the second point in time can represent or image the eye at or at the second point in time. The image captured at the second point in time is also referred to below as the second image. The second point in time lies after the first point in time. In other words, the second image represents the eye at a later point in time than the first image. In other words, the second image can image the eye at a later point in time than the first image.The present disclosure with two images at two different points in time is to be understood purely as an example. Of course, it is also possible to capture a respective image at more than two points in time, i.e., in particular, a respective image at two, three, four, five, six, seven, eight, etc. points in time. Similarly, it is possible to capture more than one image at each of the points in time or at individual points in time. For example, it may be provided that more than one image of the eye is captured at the first point in time.

[0016] From the respective images, in particular the first image and the second image, the movement information regarding the movement of the eye and / or the target point can be determined. If, as described above, more images of the eye than just the first and second images are captured, these can of course also be used to determine the movement information. For example, a relative movement of the eye and / or the target point between the first and second images can be determined as the movement information. In the case of multiple images, a respective relative movement between respective images can be determined as part of the movement information. For example, the respective relative movement between two images taken at adjacent times can be captured or determined.The motion information or the relative motion can be determined or specified, for example, in the form of a respective vector (in the case of a translational motion) and / or an angle (in the case of a rotational motion). The motion information can be determined jointly and / or independently for different degrees of freedom, such as for three independent translational degrees of freedom and / or three independent rotational degrees of freedom. The acceleration and / or the velocity, or the respective acceleration values ​​and / or the respective velocity values, can form the motion information or be part of the motion information.

[0017] Based on the movement information, the forecast for the future position and / or orientation of the target point at the later point in time can then be determined. This forecast can be determined as part of the forecast data. The later point in time is temporally spaced from the second point in time by a time period whose duration is derived at least from the latency of the image analysis. In other words, the forecast can be used to determine the position and / or orientation of the target point at such a later point in time at which the determination of the forecast data is completed and / or the forecast data is output.The invention is therefore based on the idea that, with a conventional determination of the position and / or orientation of the target point based on the respective images or based on the second image at the second time, a position and / or orientation would be determined which already lies in the past at a time at which the determination is completed, since the image analysis is subject to latency. One idea of ​​the present invention is therefore based on taking latency into account by predicting the position and / or orientation of the eye for the later time. In this way, the forecast data contain the predicted future position and / or orientation of the target point at the later time at which the image analysis, for example the acquisition of the respective images, the determination of the movement information and / or the determination of the forecast data, has already been completed.The temporal latency of the image analysis can thus be bridged by the forecast. Of course, in individual cases it may be useful to only consider the latency of selected or only some of the method steps. In this case, for example, the later point in time may be closer to the second point in time compared to an embodiment in which all steps are taken into account. Alternatively or additionally, it may of course be advantageous to consider other and / or additional method steps or other events when determining the time span by which the later point in time lies in the future from the second point in time. For example, latency-related method steps downstream of the determination of the position and / or orientation of the target point can be taken into account. This will be explained in more detail later.

[0018] According to a further development, during the determination of the forecast data, the later point in time is spaced at most as far apart in time as the first point in time. In other words, while the step of determining the forecast data is being performed, the later point in time can be at most the same time span in the future as the first point in time lies in the past. This ensures that the forecast is not directed too far into the future. This can be particularly problematic with the movement of a human or animal eye due to insufficient uniformity of its movement.

[0019] According to a further development, it is provided that an acceleration and / or a speed along a plurality of degrees of freedom are recorded independently of one another and / or evaluated independently of one another when determining the forecast data. In other words, it can be provided that the acceleration of the eye and / or the target point along the plurality of degrees of freedom are each recorded independently of one another. For example, a respective value for the acceleration along each of the plurality of degrees of freedom is determined independently. It can be provided that the speed along the plurality of degrees of freedom is recorded independently of one another. For example, a respective value for the speed along each of the plurality of degrees of freedom can be determined independently of the other degrees of freedom.Alternatively or additionally, it can be provided that the acceleration and / or the speed are evaluated independently of one another when determining the forecast data along the multiple degrees of freedom. For example, it can be provided that the respective values ​​for the acceleration and / or the speed along the individual degrees of freedom are each evaluated independently of one another for determining the forecast data or the forecast. In this case, respective partial forecasts for the movement along each of the multiple degrees of freedom can be determined or created. The forecast or forecast data can then be combined from the partial forecasts, for example by linear combination or vector addition.

[0020] According to a further development, the later time is spaced from the second time by a total time period, wherein a duration of the total time period is derived at least from the latency of the image analysis and from a latency for adjusting the laser. In other words, the method for controlling the ophthalmic surgical laser is provided such that, in addition to the latency of the image analysis, the latency for adjusting the laser is also taken into account in the total time period by which the later time is spaced from the second time period. The laser can thus be set to a specified position which takes into account the future position of the target point according to the forecast. In this way, a movement of the eye predicted for the total time period can already be taken into account when adjusting the laser. This can result in a more precise adjustment of the laser.

[0021] According to a further development, it is provided that a third image of the eye is captured at a third point in time, wherein the third point in time is after the second point in time but before the later point in time, wherein in particular the prognosis, which is part of the prognosis data, is checked at least as a function of the third image. In other words, it can be provided that the third image of the eye is captured at the third point in time. The third point in time is between the second point in time and the later point in time. Advantageously, the prognosis, which is part of the prognosis data, is checked at least as a function of the third image. It should be explicitly mentioned at this point that the term “third image” does not mean that the prognosis data is based exclusively on the first and second images.Of course, it is also possible within the scope of this further development for the movement information to be determined based on multiple images at more than two points in time and / or for the forecast or the forecast data to be based on respective images at more than two points in time. Based on the third image, the forecast, which is part of the forecast data, can thus be checked for its validity and quality. This further development is based on the idea that at the third point in time at which the third image is captured, due to the latency when adjusting the laser, the laser can no longer be aligned or adjusted based on a position and / or orientation of the target point derived from the third image.Thus, despite the presence of a more recent image, namely the third image, the laser is still adjusted to the position specification derived from it, as already described, in accordance with the forecast or the forecast data. The third time is located, in particular, between the second time and the later time such that an image evaluation of the third image is available or determined before the laser pulse is triggered. Thus, although the laser previously adjusted or aligned based on the forecast, which is derived, among other things, from the second image at the second time, can no longer be adjusted with regard to the position specification, the laser pulse can be enabled or disabled, depending on how accurate the forecast proves to be during the review based on the third image.

[0022] According to a further development, it is provided that depending on at least the third image, further movement information is determined and based on the further movement information, further forecast data containing a further forecast for the future position and / or orientation of the target point at the later point in time is determined. The forecast or the forecast data can be based on the second image as the most current image at the respective forecast time. The further forecast data or the further forecast can be based on the most current image at the third point in time, namely the third image. Thus, due to the shorter time span to be bridged by the forecast, the further forecast data can forecast the position and / or orientation of the target point at the later point in time more accurately than the forecast data which is based on the second image at the second point in time.The forecast or forecast data can be reviewed based on the additional forecast data or the additional forecast. For example, the review can determine the extent to which the forecast and the additional forecast agree or differ. It should be emphasized again at this point that the second image can be the most current image in each case. Due to the latency both when adjusting the laser and when performing image analysis, the laser can be adjusted for the laser pulse that is to occur at a later time. Based on the additional forecast data or the additional forecast, it is no longer possible to adjust the laser for the laser pulse that is to occur at a later time due to the overall latency.However, since only the latency of the image evaluation is significant for checking the prognosis based on the further prognosis, the check is still possible before the later time at which the laser is to be triggered.

[0023] According to a further development, depending on the result of checking the forecast, in particular based on the further forecast data, the laser pulse is released for the position specification previously set based on the forecast data, or a readjustment of the laser to an updated position specification is commanded. Specifically, the laser pulse can, for example, be released precisely when a deviation between the forecast and the further forecast or between the forecast data and the further forecast data is smaller than a predetermined threshold value. Analogously, the readjustment of the laser to the updated position specification can be commanded if the aforementioned deviation is greater than the predetermined threshold value. The position specification is, as already described above, derived from the forecast for the position and / or orientation of the target point at the later point in time.If the threshold is exceeded due to the deviation mentioned above, the updated position specification can be determined. In addition, the laser can be adjusted or aligned according to the updated position specification.

[0024] The updated position specification can, for example, be based on a forecast for the future position and / or orientation of the target point at a later point in time, which lies chronologically after the later point in time. This forecast of the position and / or orientation of the target point for the later point in time can be made analogously to the forecast for the future position and / or orientation of the target point at the later point in time. In this case, analogous movement information regarding the movement of the eye and / or the target point can be determined at least based on the second and third images. The forecast for the later point in time can then be determined based on the movement information determined from the second and third images.However, due to the analogy to determining the forecast for the future position and / or orientation of the target point at the later time, this will not be explained in a repetitive manner here.

[0025] According to a further training it is planned that - at least approximately at the later time a fourth image of the eye is captured, - the fourth image is used to determine the actual position and / or orientation of the target point at the later time, - compare the actual position of the eye at the later time with the forecast, which is part of the forecast data, and / or with the further forecast, which is part of the further forecast, and - depending on a result of the respective comparison, a first algorithm for determining the forecast data and / or a second algorithm for determining the further forecast data is changed.

[0026] If the respective images, for example the first, second, third and / or fourth image, are part of a video signal, the exact individual image of the video signal whose recording time is closest to the later point in time can be selected as the fourth image. The fourth image therefore relates to the eye at approximately the later point in time. In other words, the fourth image depicts the eye at approximately the later point in time. The fourth image can therefore be used to determine the actual position and / or orientation of the target point at the later point in time. By comparing the actual position of the eye at the later point in time with the forecast (which is part of the forecast data) for the position of the eye at the later point in time, it is possible to determine or ascertain how good this forecast was.For example, the quality of the forecast can be assessed or quantified by a value that indicates the deviation between the actual and predicted position. By comparing the actual position of the eye at the third time point with the long-range forecast (which is part of the further forecast data) for the position of the eye at the later time point, the quality of this further forecast can be determined or ascertained. For example, the quality of the further forecast can be assessed or quantified by a value that indicates the deviation between the actual and predicted position.

[0027] Depending on the deviation between the actual position of the eye and the forecast, the first algorithm used to determine the forecast or forecast data can be changed, i.e., trained, refined, or adapted. In this way, the quality of the first algorithm is refined or improved for future forecasts. Depending on the deviation between the actual position of the eye and the further forecast, the second algorithm used to determine the further forecast or further forecast data can be changed, i.e., trained, refined, or adapted. In this way, the quality of the second algorithm is refined or improved for future forecasts.

[0028] 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.

[0029] 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), which is 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 and / or photodisruptive treatment devices.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] A fourth aspect of the invention relates to a computer program comprising instructions which cause the treatment device according to the third aspect of the invention to carry out the method steps according to the first aspect of the invention.

[0034] 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.

[0035] 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. In this case, they show: Fig. 1 a schematic representation of a treatment device according to the invention according to an exemplary embodiment; Fig. 2 a flowchart of a method according to the invention according to an exemplary embodiment; and Fig. 3 a flowchart of further steps of the method according to the invention according to the exemplary embodiment.

[0036] 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, i.e., a tissue removal geometry 14, 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.

[0037] Furthermore, the Fig. 1, the laser beam 19 generated by the laser 12 can be deflected toward the eye 16 by means of a beam deflection device 22, namely a beam deflection apparatus 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.

[0038] 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 of the individual laser pulses are determined at least using the method described below.

[0039] Fig. 2 shows a flowchart of an exemplary embodiment of a method for controlling the ophthalmic surgical laser 12 of the treatment device 10 during a treatment of a cornea of ​​the human or animal eye 16 depending on a position and / or orientation of a target point of the eye 16. The laser beam of the laser 12 or laser pulses of the laser 12 should hit the target point of the eye 16 as precisely as possible. Since the eye 16 is frequently moving and complete "immobilization" is not entirely possible, the movements of the eye 16 must be detected and taken into account, i.e., compensated, when guiding the laser beam 19 of the laser 12 or the laser pulses of the laser 12. The method thus serves to adapt the predetermined laser pulses with regard to their respective positioning or orientation such that the movement of the eye 16 is compensated.

[0040] To determine the movement or tracking of the eye 16 and / or the target point, the treatment device 10 has at least one camera 20. The control device 18 is configured to evaluate images of the eye 16. The camera 20 can be configured to capture these images of the eye 16 and transmit them to the control device 18. The control device 18 can be configured to receive images of the eye 16 from the camera 20.

[0041] In particular, the images from camera 20 are a video signal composed of a large number of consecutive individual images. Depending on the image capture rate of camera 20, approximately 1200 Hz or 1200 fps (images per second), the latency of camera 20 can be slightly less than one millisecond.

[0042] The control device 18 can have an image processing unit 22. The images of the eye 16 can be processed and / or evaluated by the image processing unit 22. In particular, the position of the eye 16 and / or the target point can be determined by the image processing unit 22. The image processing unit 22 can comprise, for example, a microprocessor, a digital signal processor, an FPGA, or the like. This can result in a latency of approximately 1 ms, for example, 0.9 ms. The processed image can also be output to an output unit 32, such as a screen.

[0043] A main control unit 24 of the control device 18 can link the results of detecting the position and / or movement of the eye 16 with the predetermined laser pulses from a pulse list 26. Here, it can be determined according to which position specification the laser 12 or the beam device 17 must be adjusted in order to guide a laser pulse assigned by the pulse list 26 to the target position. Coordinates for the position specification of the laser 12 can be composed of coordinates of a respective laser pulse and an offset, whereby the coordinates can be assigned by the pulse list 26 and / or the offset results from the position and / or movement of the eye 16 or the target point. The offset serves to compensate for the movement of the eye. The latency in this case is, for example, approximately 90 µs.The laser 12 or the beam device 17 can then be adjusted or aligned according to the specified position. This can be done by a control unit 28. The latency when controlling the control unit 28 is, for example, approximately 100 ns. The control unit 28 can, for example, be provided by an amplifier for controlling the beam device 17. The control unit 28 can, for example, control or supply an adjustment unit 30 with a signal, a current, or a voltage. The adjustment unit 30 is designed in particular for the mechanical alignment of the beam device 17 according to the control by the control unit 28. A latency for adjusting or aligning the beam device 17 can, for example, be up to 1 ms; this depends, for example, on an adjustment path during alignment.The main control unit 24 may comprise, for example, a microprocessor, a digital signal processor, an FPGA or the like.

[0044] The following steps of the present embodiment of the method compensate for the mentioned latencies: In a step S1, a respective image of the eye is captured at least at a first point in time and a later second point in time. This can be done by the camera 20, as already described above. Alternatively or additionally, the images can be captured by the control unit 18 by receiving the images from the camera 20. For example, the camera 20 captures at least a first image at the first point in time and a second image at the later second point in time. Of course, several individual images of a video signal, each captured one after the other, can also be captured and used for the further process.

[0045] In a step S2, movement information relating to a movement of the eye and / or the target point is determined based on the respective images. This can be carried out in particular by the control unit 18. In particular, the movement information is determined by the image processing unit 22. In particular, the image processing unit 22 can evaluate the first and second images for this purpose. For example, a relative movement of the eye and / or the target point between the first and second images can be determined as the movement information. In the case of multiple images, a respective relative movement between respective images can be determined as part of the movement information. For example, the respective relative movement between two images taken at adjacent times can be detected or determined.The motion information or the relative motion can be determined or specified, for example, in the form of a respective vector (in the case of a translational motion) and / or an angle (in the case of a rotational motion). The motion information can be determined jointly and / or independently for different degrees of freedom, such as three independent translational degrees of freedom and / or three independent rotational degrees of freedom.

[0046] In a step S3, forecast data are determined, which contain a forecast for a future position and / or orientation of the target point at a later time. The forecast data are determined based on the movement information. The later time is preferably spaced from the second time by a period of time, the duration of which is derived at least from a total latency of the image analysis and the adjustment of the laser 12 or the beam device 17. Based on the movement information, the forecast for the future position and / or orientation of the target point at the later time can thus be determined. This forecast can be determined as part of the forecast data.The later point in time is spaced from the second point in time by the time period whose duration is derived at least from the total latency of the image evaluation and the adjustment of the laser 12 or the beam device 17. The total latency results, for example, from the added latencies of steps S1, S2, S3, S4, and S5. Thus, the total latency can be obtained by adding the respective latencies of the camera 20 (approximately 1 ms), the image processing unit 22 (approximately 0.9 ms), the main control unit 24 (approximately 90 µs), the control unit 28 (approximately 100 ns), and the alignment of the beam device 17 (approximately 1 ms). This total latency can be specified by a predetermined average value. Alternatively, the respective latencies can be specified by a respective average value. Step S3 can, for example, be performed by the image processing unit 22.

[0047] In a step S4, the position specification for the laser pulse is determined at least as a function of the forecast data. The forecast for the future position and / or orientation of the target point is thus used to determine the position specification for the laser pulse. For example, the position specification for the laser pulse can be defined by the pulse list 26 in a coordinate system aligned with the eye 16 or the cornea 14. In this example, the movement of the eye 16 can result in a relative movement between the coordinate system aligned with the eye 16 and a world coordinate system or a coordinate system aligned with a treatment device 10.Thus, the position specification for the laser pulse can be determined, for example, taking into account the prognosis data, in particular the future positions of the eye 16 and / or the target point, in the world coordinate system or the coordinate system aligned with the treatment device.

[0048] In a step S5, the laser 12 is adjusted according to the specified position. Thus, the laser 12 can be adjusted and / or aligned according to the specified position. In this case, the adjustment or alignment of the laser 12 is performed by aligning or adjusting the beam device 17 for beam guidance and / or beam shaping and / or beam deflection and / or beam focusing of the laser beam 19 of the laser 12. For example, the future laser pulse can be aligned to the target point by appropriately controlling the beam device 17 according to the specified position.

[0049] In a step S6, further movement information is determined depending on at least a third image. For this purpose, in particular a third image of the eye 16 is captured at a third point in time, wherein the third point in time is after the second point in time but before the later point in time. The third image can be a single image of the video signal from the camera 20 following the second image. In step S6, in particular the forecast, which is part of the forecast data, is checked at least depending on the third image. In other words, it can be provided that the third image of the eye is captured at the third point in time. The third point in time is between the second point in time and the later point in time. Based on the third image, the forecast, which is part of the forecast data, can thus be checked for its validity or quality.This is based on the idea that at the third time point, at which the third image is captured, due to the latency in adjusting the laser, the laser can no longer be aligned or adjusted based on a position and / or orientation of the target point derived from the third image. Thus, despite the presence of a more recent image, namely the third image, the laser is nevertheless adjusted to the position specification derived from it, as already described, according to the forecast or the forecast data. The third time point is located, in particular, between the second time point and the later time point in such a way that an image evaluation of the third image is available or determined before the laser pulse is triggered.Thus, the laser previously adjusted or aligned based on the forecast, which is derived, among other things, from the second image at the second time, can no longer be adjusted with regard to the position specification, but it is possible to enable or disable the laser pulse, depending on how well the forecast proves to be during the review based on the third image.

[0050] As part of step S6, it is provided here that the further movement information is determined depending on at least the third image. In a subsequent step S7, further forecast data containing a further forecast for the future position and / or orientation of the target point at the later point in time is determined at least based on the third image or the further movement information. The forecast or the forecast data can be based on the second image as the most current image at the respective forecast time. The further forecast data or the further forecast can be based on the most current image at the third point in time, namely the third image.Thus, the further forecast data can predict the position and / or orientation of the target point at the later time more accurately than the forecast data based on the second image at the second time due to the smaller time span to be bridged by the forecast.

[0051] Depending on the result of a check of the forecast based on the additional forecast data, the laser pulse can be released for the position specification previously set based on the forecast data (step 8.1), or a readjustment of the laser 12 to an updated position specification can be commanded (step 8.2). The check of the forecast or the forecast data can be carried out based on the additional forecast data or the additional forecast. For example, the check can determine the extent to which the forecast and the additional forecast agree or differ from one another. Specifically, the laser pulse can be released, for example, precisely when a deviation between the forecast and the additional forecast or between the forecast data and the additional forecast data is smaller than a predetermined threshold value.Analogously, the laser 12 or the beam device 17 can be commanded to be readjusted to the updated position specification if the aforementioned deviation is greater than the predetermined threshold. As already described above, the position specification is derived from the forecast for the position and / or orientation of the target point at the later time. If the threshold is exceeded due to the aforementioned deviation, the updated position specification can be determined. In addition, the laser can be adjusted or aligned according to the updated position specification. At this point, it should be clarified again that the second image can be the most recent image in order to adjust the laser for the laser pulse that is to occur at a later time due to the latency both when adjusting the laser 12 and when performing the image analysis.Based on the additional prognosis data or the additional prognosis, it is no longer possible to adjust the laser 12 for the laser pulse scheduled to occur at a later time due to the overall latency. However, since only the latency of the image analysis is significant for verifying the prognosis based on the additional prognosis, the verification is still possible before the later time at which the laser is scheduled to be triggered.

[0052] Fig. Figure 3 shows a further flowchart of further optional steps of the process. These can be added to the process according to Fig. 2 be carried out subsequently.

[0053] A step S9 provides that a fourth image of the eye 16 is captured at least approximately at the later point in time. A step S10 provides that an actual position and / or orientation of the target point at the later point in time is determined based on the fourth image. A step S11 provides that the actual position of the eye 16 at the later point in time is compared with the forecast, which is part of the forecast data, and / or with the further forecast, which is part of the further forecast. A step S12.1 provides that a first algorithm for determining the forecast data is changed depending on a result of the comparison. A step S12.2 provides that a second algorithm for determining the further forecast data is changed depending on a result of the comparison.

[0054] If the respective images, for example the first, second, third and / or fourth image, are part of a video signal, the exact individual image of the video signal whose recording time is closest to the later point in time can be selected as the fourth image. The fourth image therefore relates to the eye at approximately the later point in time. In other words, the fourth image depicts the eye at approximately the later point in time. The fourth image can therefore be used to determine the actual position and / or orientation of the target point at the later point in time. By comparing the actual position of the eye at the later point in time with the forecast (which is part of the forecast data) for the position of the eye at the later point in time, it is possible to determine or ascertain how good this forecast was.For example, the quality of the forecast can be assessed or quantified by a value that indicates the deviation between the actual and predicted position. By comparing the actual position of the eye at the third time point with the long-range forecast (which is part of the further forecast data) for the position of the eye at the later time point, the quality of this further forecast can be determined or ascertained. For example, the quality of the further forecast can be assessed or quantified by a value that indicates the deviation between the actual and predicted position.

[0055] Depending on the deviation between the actual position of the eye and the forecast, the first algorithm used to determine the forecast or forecast data can be changed, i.e., trained, refined, or adapted. In this way, the quality of the first algorithm is refined or improved for future forecasts. Depending on the deviation between the actual position of the eye and the further forecast, the second algorithm used to determine the further forecast or further forecast data can be changed, i.e., trained, refined, or adapted. In this way, the quality of the second algorithm is refined or improved for future forecasts. LIST OF REFERENCE SYMBOLS: 10 Treatment device 12 lasers 14 fabrics 16 Eye 17 Beam deflection device 18 Control device 19 Laser beam 20 Camera 22 Image processing unit 24 Main control unit 26 Pulse list 28 Control unit 30 setting unit 32 output unit S1 to 8.2 Process steps S9 to S12.2 Process steps

Claims

[1] Method for controlling an ophthalmic surgical laser (12) of a treatment device (10) during a treatment of a cornea of a human or animal eye (16) depending on a position and / or orientation of a target point of the eye (16), the method comprising the following steps: - capturing (S1) a respective image of the eye (16) at least at a first time and a later second time, - determining (S2) movement information relating to a movement of the eye (16) and / or the target point based on the respective images, and - Determining (S3) forecast data containing a forecast for a future position and / or orientation of the target point at a later time, based on the movement information, wherein the later time is spaced apart from the second time by a period of time whose duration is derived at least from a latency of an image evaluation, in particular steps S1 and / or S2 and / or S3; - determining (S4) a position specification for a laser pulse at least as a function of the forecast data, and - Adjusting (S5) the laser (12) according to the specified position; - wherein a third image of the eye (16) is captured at a third point in time, wherein the third point in time is after the second point in time but before the later point in time, wherein the prognosis, which is part of the prognosis data, is checked at least as a function of the third image; and - wherein, depending on a result of checking the forecast, the laser pulse is released for the position specification previously set on the basis of the forecast data (S8.1) or a readjustment of the laser (12) to an updated position specification is commanded (S8.2). [2] Method according to claim 1, characterized by that during the determination (S3) of the forecast data, the later point in time is at most as far apart in time as the first point in time. [3] Method according to claim 1 or 2, characterized by that an acceleration and / or a speed along several degrees of freedom are recorded independently of each other and / or are evaluated independently of each other when determining (S3) the forecast data. [4] Method according to one of the preceding claims, characterized bythat the later time is spaced apart from the second time by a total time period, wherein a duration of the total time period is derived at least from the latency of an image evaluation and from a latency for the adjustment (S5) of the laser (12). [5] Method according to one of the preceding claims, characterized by , that - further movement information is determined depending on at least the third image (S6), and - based on the further movement information, further forecast data are determined, which contain a further forecast for the future position and / or orientation of the target point at the later time (S7). [6] Method according to one of the preceding claims, characterized by , that - a fourth image of the eye (16) is captured at least approximately at the later time, - an actual position and / or orientation of the target point at the later time is determined on the basis of the fourth image, and - the actual position of the eye (16) at the later time is compared with the forecast which is part of the forecast data and / or with the further forecast which is part of the further forecast, - depending on a result of the respective comparison, a first algorithm for determining the forecast data and / or a second algorithm for determining the further forecast data is changed. [7] Control device (18) which is designed to cause a treatment device (10) to carry out a method according to one of the preceding claims. [8] Treatment device (10) with at least one ophthalmic surgical laser (12) for performing a corneal correction on a cornea by means of photodisruption and / or photoablation and with a control device (18) according to claim 7. [9] Treatment device (10) according to claim 8, characterized by that the laser (12) 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. [10] Treatment device (10) according to claim 8 or 9, 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 (17) for beam guidance and / or beam shaping and / or beam deflection and / or beam focusing of a laser beam (19) of the laser (12). [11] Computer program comprising instructions causing the treatment device (10) according to one of claims 8 to 10 to carry out a method according to one of claims 1 to 6. [12] A computer-readable medium on which the computer program according to claim 11 is stored.

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