Method for aligning an eye to a treatment position on a treatment device

Abstract

The invention relates to a method for aligning an eye (16) to a treatment position (26) on a treatment device (10) comprising an ophthalmic laser (12). The method comprises, as steps: determining correction parameters for correcting the eye (16) with the ophthalmic laser (12); determining a tolerance range (28, 28') of the treatment position (26) depending on the determined correction parameters; checking whether the eye (16) is aligned within the tolerance range (28, 28'); releasing the treatment if the eye (16) is aligned within the tolerance range (28, 28'); and generating a termination signal if the eye (16) is not aligned within the tolerance range (28, 28').

Description

The invention relates to a method for aligning an eye to a treatment position on a treatment device comprising an ophthalmic laser. The invention further relates to a control unit configured to perform the method, a treatment device with such a control unit, a computer program comprising commands that cause the treatment device to execute the method, and a computer-readable medium on which the computer program is stored. Treatment devices and methods for controlling ophthalmic lasers to correct refractive errors and / or pathologically or abnormally altered areas of the cornea are known in the prior art. For example, pulsed lasers and a beam focusing device can be configured such that laser pulses cause photodisruption and / or ablation in a focus located within the organic tissue in order to remove tissue, in particular a tissue lenticel, from the cornea. Before treatment with the ophthalmic laser, the eye is positioned at a patient interface of the treatment device and aligned for the procedure. During alignment, the eye should be brought into a treatment position in which, for example, a treatment area of ​​the eye is centered for the ophthalmic laser, specifically centered on a neutral position of the laser beam. However, such centering or alignment of the eye to the treatment position can be time-consuming, especially if the eye is not ideally aligned immediately and corrections are necessary. From US patent 2023 / 0372149 A1, a method for centering a contact lens relative to the patient's eye is known. The method comprises providing a fixation light through the contact lens to enable the patient's eye to fixate on the fixation light; capturing an image of a light pattern projected onto the ocular surface; and displaying the image over the eye with the contact lens, wherein a first mark identifies the central axis of the contact lens and a second mark identifies a reference mark derived from the image of the light pattern and located on the central axis of the contact lens; laterally positioning the contact lens so that the distance between the marks is minimized; and determining the position of the eye where the second mark is located when the marks have reached the minimized distance, and recording the position of the vertex. The object of the invention is to simplify the alignment of an eye to a treatment position on a treatment device. This problem is solved by the independent patent claims. Advantageous embodiments of the invention are disclosed in the dependent patent claims, the following description, and the figures. The invention is based on the idea that, depending on the planned treatment, a tolerance range is defined that an eye being docked may exhibit when aligning itself with the treatment position. In particular, depending on the planned correction, the size and / or shape of the tolerance range can be adjusted, which can simplify the alignment of the eye with the treatment position. One aspect of the invention relates to a method for aligning an eye to a treatment position on a treatment device comprising an ophthalmic laser. The method comprises, as steps, determining correction parameters for correcting the eye with the ophthalmic laser, determining a tolerance range of the treatment position depending on the determined correction parameters, checking whether the eye is aligned within the tolerance range of the treatment position, releasing the treatment if the eye is aligned within the tolerance range, and generating a termination signal if the eye is not aligned within the tolerance range. The aforementioned steps can be controlled, for example, by a control device to align the eye with the treatment position. In other words, correction parameters can first be determined to be used for correcting the eye. For example, the correction parameters can include diopter values ​​for sphere and / or cylinder correction, as well as axis values. Alternatively or additionally, the correction parameters can also include corrections for higher-order aberrations. Based on the planned correction parameters, a tolerance range can then be determined within which the eye should be aligned for treatment with the device. This means that a treatment position can be defined on the device where the eye should be positioned for the procedure. For example, the eye might be positioned centrally at a patient interface or centrally to the exit direction of a laser beam from the device. However, deviations from an ideal treatment position may be permitted, and these deviations are specified by the tolerance range. The tolerance range can vary depending on the specified correction parameters. For example, a circular tolerance range can be selected for spherical correction. If the correction parameters also include cylindrical correction, the tolerance range can extend along a cylinder axis, resulting in a cylindrical or elliptical tolerance range. Furthermore, the size of the tolerance range can be modified depending on the planned correction parameters. For instance, a smaller tolerance range may be used for correcting higher-order aberrations than for correcting lower-order aberrations. Once the tolerance range has been determined, it can be verified whether the eye is within the tolerance range of the treatment position. This can be done, for example, using a camera device that records images of the eye as it approaches the treatment position. If the eye is within the tolerance range, treatment with the ophthalmic laser can be performed. For example, a release signal can be generated to enable or start the laser pulse delivery of the ophthalmic laser. However, if the eye is outside the tolerance range, a termination signal can be generated. This termination signal can, for example, prevent the ophthalmic laser from delivering a laser pulse. Alternatively or additionally, the termination signal can include a warning signal to alert the user to a possible misalignment of the eye. The invention offers the advantage that the alignment of the eye can be improved and adapted to a planned treatment, which facilitates the overall alignment of the eye. In a first alternative according to the invention, the size of the tolerance range is defined depending on the specific correction parameters. This means, for example, that dimensions in the x / y direction or radial direction can be defined based on the planned correction parameters. Thus, for certain corrections, a small tolerance range can be defined, for example, a tolerance range with a radius of 50 micrometers, while for other corrections, where centering the eye on the treatment position is less critical, the radius of the tolerance range can be set, for example, at 200 micrometers. Alternatively or additionally, a second embodiment of the invention provides that the shape of the tolerance range is defined depending on the specific correction parameters. This means that the tolerance range need not be circular, but can exhibit an azimuthal dependency. The invention also includes embodiments that offer additional advantages. One embodiment provides that the tolerance range is defined as either elliptical or cylindrical. A cylindrical shape may be used, in particular, if only cylinder correction is to be performed on the eye. An elliptical tolerance range may be provided if a combination of spherical and cylindrical correction is planned. In an exemplary embodiment, the correction parameter includes at least one cylinder correction of the eye, with the tolerance range being extended along a cylinder axis of the cylinder correction. In particular, it can be provided that the tolerance range is extended along the cylinder axis where no correction is to take place. Another embodiment provides that the positioning of a contact element on the treatment device is additionally determined, with the tolerance range being adjusted depending on the positioning of the contact element. In other words, the tolerance range can also be determined based on the established positioning of a contact element. If the contact element is slightly displaced or tilted, this displacement and / or tilt can be taken into account when defining the tolerance range. The contact element can, for example, be a contact lens to which the eye can be placed for treatment. The contact element can also, for example, include a suction device that can hold the eye in position using negative pressure. Another embodiment provides for the alignment of the eye with the treatment device to be monitored by a camera system. The camera system can have one or more cameras that determine the alignment or position of the eye. Based on the eye's position, it can then be determined whether it is within the tolerance range, thus automatically triggering the approval for treatment or the abort signal. The respective procedure may include at least one additional step that is executed precisely when a use case or application situation occurs that is not explicitly described here. This step may, for example, include the output of an error message and / or a prompt for user feedback. Additionally or alternatively, it may be provided that a default setting and / or a predetermined initial state is set. Another aspect of the invention relates to a control device configured to perform the steps of at least one embodiment of a previously described method. For this purpose, the control device may include a computing unit for electronic data processing, such as a processor. The computing unit may comprise at least one microcontroller and / or at least one microprocessor. The computing unit may be implemented as an integrated circuit and / or a microchip. Furthermore, the control device may include an (electronic) data storage device or a storage unit. Program code, which encodes the steps of the respective embodiment of the respective method, may be stored on the data storage device. The program code may include the control data for the respective laser.The program code can be executed by the processing unit, which then causes the control unit to execute the respective configuration. The control unit can be designed as a control chip or control device. The control unit can, for example, be part of a computer or computer network. A further aspect of the invention relates to a treatment device comprising at least one ophthalmic or surgical laser and a control unit configured to perform the steps of at least one embodiment of one or both of the previously described methods. The respective laser can be configured to at least partially separate a predefined corneal volume with predefined interfaces of a human or animal eye by means of optical breakthrough, in particular to at least partially separate it by means of photodisruption, and / or to ablate corneal layers by means of (photo)ablation, and / or to cause a laser-induced change in the refractive index of the cornea and / or the lens of the eye, and / or to increase corneal crosslinking. 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 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 take place in a wavelength range below 300 nm. This range is subsumed under the term "deep ultraviolet" in laser technology. This advantageously avoids unintentional damage to the cornea caused by these very short-wavelength and high-energy beams.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, necessary for optical breakthrough, to be spatially tightly limited, thus enabling high cutting accuracy in the generation of interfaces. The wavelength range between 700 nm and 780 nm can also be selected. In a further advantageous embodiment of the treatment device according to the invention, the control device can have at least one storage device for at least temporary storage of 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. Another aspect of the invention relates to a computer program. The computer program comprises instructions that, for example, constitute program code. The program code can, for example, include a control data set with the respective control data for the respective laser. Alternatively or additionally, when the program code is executed by a computer or a computer network, the computer can be caused to execute or control the previously described method or at least one embodiment thereof. Another 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, for example, designed as a data storage device, in particular at least partially as a volatile or non-volatile data storage device. A non-volatile data storage device can be flash memory and / or an SSD (solid-state drive) and / or a hard drive. A volatile data storage device can be RAM (random access memory). The instructions can be, for example, in the form of source code of a programming language and / or as assembly language and / or as binary code. Further features and advantages of one of the described aspects of the invention may arise from further developments of another aspect of the invention. The features of the embodiments of the invention can therefore exist in any combination with one another, unless they have been explicitly described as mutually exclusive. Additional features and advantages of the invention are described below with reference to the figure(s) in the form of advantageous embodiments. The features or combinations of features of the embodiments described below can be combined with each other and / or with the features of the embodiments. That is, the features of the embodiments can complement and / or replace the features of the embodiments, and vice versa. Therefore, embodiments that are not explicitly shown or explained in the figures, but which can be derived and generated from separate combinations of features in the embodiments and / or embodiments, are also to be considered as encompassed and disclosed by the invention.Thus, embodiments that do not exhibit all the features of an originally formulated claim, or that go beyond or deviate from the combinations of features set out in the cross-references of the claims, are also to be considered disclosed. Regarding exemplary embodiments: Fig. 1 shows a schematic representation of a treatment device according to an exemplary embodiment; Fig. 2 shows a schematic process diagram for a method for aligning an eye; Fig. 3 shows a schematic representation of a tolerance range for aligning an eye. In the figures, identical or functionally equivalent elements are provided with the same reference symbols. Figure 1 shows a schematic representation of a treatment device 10 with an ophthalmic laser 12 for removing tissue 14 from the cornea of ​​a human or animal eye 16 by means of photodisruption and / or ablation. The tissue 14 can, for example, be a lenticule or a volumetric body that can be removed from the cornea with the ophthalmic laser 12 to correct a refractive error. A correction profile or the geometry of the tissue 14 to be removed can be defined based on correction parameters that are to be applied to the eye 16. For example, the correction parameters can provide diopter values, in particular for sphere, cylinder, and axis correction. To remove the tissue 14, control data can be provided by a control unit 18, 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 unit 18 can be an external control unit 18 with respect to the treatment device 10. Furthermore, Fig. 1 shows that the laser beam 20 generated by the laser 12 can be deflected towards the cornea by means of a beam deflection device 22, 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. The laser 12 shown is preferably 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 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 includes a storage 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. Before treatment of eye 16 with the treatment device 10 begins, the eye 16 is positioned on the treatment device 10. For example, it is intended that the eye 16 be aligned centrally to a neutral position of the laser beam 20 before the treatment starts. However, aligning the eye 16 is often time-consuming. To simplify the alignment of the eye 16 to the treatment position of the treatment device 10, the procedure shown in Fig. 2 can therefore be carried out. Figure 2 shows a schematic process diagram for aligning the eye 16 to a treatment position on the treatment device 10. The process can be controlled, for example, by the control unit 18, which monitors the alignment of the eye 16 by means of a camera device 24. The camera device 24 can comprise one or more cameras designed to capture image data of the eye 16, from which the alignment of the eye 16 to the treatment device 10 can be determined. In step S10, correction parameters for correcting eye 16 can first be determined. This means that the correction parameters define which corrections are to be made and what geometry the tissue 14 to be removed has. In step S12, a tolerance range can be determined depending on the specified correction parameters. This tolerance range can define the maximum permissible deviation of the eye 16 from an ideal treatment position on the treatment device 10. In particular, the size and / or shape of the tolerance range can be defined depending on the specific correction parameters. This means that the size and / or shape of the tolerance range can be adjusted depending on the planned correction. Figure 3 shows a schematic representation of tolerance ranges 28, 28' and a highly simplified representation of an eye 16. The eye 16 is shown from the perspective of the treatment device 10, which has a treatment position 26 towards which the eye 16 is to be aligned. In particular, it may be intended that the center of the eye 16 should coincide with the treatment position 26. Since pinpoint alignment is not practical, a tolerance range 28 can be provided, by which the eye 16 may deviate from the treatment position 26. For example, a circle with a radius of 70 µm can be specified as the tolerance range 28. In this example, however, it may be necessary to perform a cylinder correction of eye 16. Therefore, the shape and / or size of tolerance area 28 can be adjusted to tolerance area 28'. For example, tolerance area 28' can be increased in the y-direction, since no correction is planned on this cylinder axis and therefore precise positioning in this direction is less critical. Once the tolerance range has been determined, it can be checked in step S14 whether the eye 16 is within the tolerance range 28'. This can be monitored, for example, by the camera device 24. If the eye is within the tolerance range 28', the treatment can be performed in step S16. For this purpose, for example, a release signal can be generated that enables the triggering of laser pulses by the ophthalmic laser 12. However, if eye 16 is not within tolerance range 28-, a termination signal can be generated in step S18, which, for example, prevents the ophthalmic laser 12 from triggering laser pulses. In particular, eye 16 can then be realigned until it is within tolerance range 28'. Overall, the examples show how a procedure for aligning an eye 16 to a treatment position 26 can be provided.

Claims

Method for aligning an eye (16) to a treatment position (26) on a treatment device (10) comprising an ophthalmic laser (12), the method comprising the following steps: - Determining correction parameters for correcting the eye (16) with the ophthalmic laser (12); - Determining a tolerance range (28.28') of the treatment position (26) depending on the specified correction parameters; - Check whether the eye (16) is aligned within the tolerance range (28, 28'); - if the eye (16) is aligned within the tolerance range (28, 28'), release the treatment; - if the eye (16) is not aligned within the tolerance range (28, 28'), generate a termination signal; ◯ where a size of the tolerance range (28, 28') is specified depending on the specified correction parameters; and / or ◯ where a shape of the tolerance range (28, 28') is specified depending on the specified correction parameters. Method according to claim 1, wherein the tolerance range (28, 28') is defined as elliptical or cylindrical. Method according to one of the preceding claims, wherein the correction parameter comprises at least a cylinder correction of the eye (16), wherein the tolerance range (28, 28') is extended along a cylinder axis of the cylinder correction. Method according to one of the preceding claims, wherein a positioning of a contact element on the treatment device (10) is additionally determined, wherein the tolerance range (28, 28') is adjusted depending on the positioning of the contact element. Method according to one of the preceding claims, wherein the alignment of the eye (16) at the treatment position (26) is monitored by a camera device (24). Control device (18) configured to perform a procedure according to any of the preceding claims. Treatment device (10) comprising at least one ophthalmic laser (12) for separating a corneal volume of a human or animal eye by means of optical breakthrough, in particular by means of photodisruption and / or photoablation, and at least one control device (18) according to claim 6. Computer program comprising commands that cause the treatment device (10) according to claim 7 to execute a method according to any one of claims 1 to 5. Computer-readable medium on which a computer program according to claim 8 is stored.

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