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

Abstract

The invention relates to devices and methods for providing control data for an ophthalmic laser (12) of a treatment device (10).The procedure comprises determining (S10) correction data for a planned refractive correction of a corneal refractive error (16) from predetermined examination data, wherein the correction data include a correction for a sphere value, a cylinder value, and an axis value; determining (S12) adapted correction data based on a nomogram and the determined correction data, wherein the nomogram adapts the correction of the sphere value and / or the cylinder value and / or the axis value to the treatment device (10) used, such that a refractive correction with the adapted correction data corresponds to the planned refractive correction, wherein the nomogram is determined from previous treatment results with the same treatment devices; and providing (S14) the control data based on the adapted correction data.

Description

The invention relates to a method for providing control data for an ophthalmological laser of a treatment device. Furthermore, the invention relates to a control device which is configured to carry out the method, to a treatment apparatus having such a control device, and to a computer program comprising instructions which cause the treatment apparatus to carry out the method. Also provided is a computer readable medium on which the computer program is stored.Treatment devices and methods for controlling ophthalmological lasers for correcting an optical defect vision and / or pathologically or unnaturally modified regions of the cornea (cornea) are known in the prior art. In this case, for example, pulsed lasers and a beam focusing device can be designed such that laser pulses cause photodisruption and / or ablation in a focus located within the organic tissue in order to remove a tissue, in particular a tissue lenticle, from the cornea.During the treatment of a cornea, it may occur that an achieved correction deviates from a planned correction. This can be based in particular on properties of the environment in which the treatment device is located, on a demographics, on treatment or diagnostic differences by the physician and / or on a systematic distortion of devices used.It is therefore an object of the invention to provide control data for controlling the ophthalmological laser and / or the treatment device, which control data generate an improved correction.This object is achieved by the independent patent claims. Advantageous refinements of the invention are disclosed in the dependent patent claims, the following description and the figures.The invention is based on the idea that a nomogram is created which comprises planned and achieved corrections, in particular of sphere, cylinder and axis values. The planned correction data required for the treatment can then be deduced from the nomogram during the treatment planning on the basis of the correction data achieved.One aspect of the invention relates to a method for providing control data for an ophthalmological laser of a treatment apparatus, wherein the method has the following steps carried out by means of a control device. A control device is understood to mean a device or a device component, in particular a computer or processor, which can perform the following steps automatically or semi-automatically.In the method, correction data for a planned refraction correction of a refractive error of a cornea is ascertained from predetermined examination data, wherein the correction data comprise a correction for a sphere value, a cylinder value and an axis value. Furthermore, adjusted correction data are determined on the basis of a nomogram and the determined correction data, wherein the correction of the sphere value and / or the cylinder value and / or the axis value is adjusted to the treatment device used by the nomogram, such that a refraction correction with the adjusted correction data corresponds to the planned refraction correction, wherein the nomogram is determined by previous treatment results using the same treatment devices. Finally, the control data are provided, which are based on the adapted correction data.In other words, due to characteristics of the treatment device, an achieved refraction correction may deviate from a planned refraction correction. This deviation can be compensated for by the nomogram by adapting the initially determined correction data in such a way that the planned refraction correction is obtained as the refraction correction achieved.For this purpose, the initial correction data for correcting a refraction of the cornea can first be determined from predetermined examination data. The predetermined examination data can originate, for example, from a manifest or subjective refraction measurement, in particular by means of a phoropter. Alternatively or additionally, the examination data can comprise wavefront measurements and / or topography measurements of the cornea. The refraction correction for compensating for a refractive error may comprise at least a sphere value, a cylinder value and an axis value.From the nomogram, which is preferably based on previous treatments with similar treatment devices, preferably the same treatment device, treatment results of these treatment devices can be present together with an initially planned correction. The control device can then match the initially planned correction data with achieved treatment results in order to determine via the nomogram which initial correction data can be used to achieve these treatment results. This means that an initially planned sphere value is preferably matched to a sphere value reached and an adapted sphere value is determined via the nomogram, furthermore a cylinder value reached is determined via the nomogram to form an adapted cylinder value, and an axis value is determined via the nomogram to form an adapted axis value.Finally, the adjusted correction data, which in particular comprise the adjusted sphere, cylinder and axis values, can be provided in the form of control data, wherein the treatment apparatus and / or the ophthalmological laser can be controlled by means of the control data.The control data can comprise a respective data record for positioning and / or focusing individual laser pulses in the cornea. Additionally or alternatively, a respective data set for setting 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 can be included in the control data.The nomogram can comprise in particular changes in the manifest refraction, changes in the cycloplegic refraction, changes in the autorefraction, changes in the aberometric refraction at a fixed analysis diameter (and reference center), changes in the aberometric refraction for a maximum pupil size, changes in the keratometric refraction power or similar topographical metrics, with the aim of obtaining an optimized nomogram from which the adapted values can be determined for achieving the refraction correction.The invention has the advantage that an improved refraction correction can be carried out, since properties of the similar or identical treatment device can be compensated.The invention also comprises developments, by means of which additional advantages result.A further development provides that the nomogram is determined by previous treatment results using the same treatment device. That is, the nomogram is specifically tailored to the treatment device used. Preferably, a separate nomogram can be created for each laser of the treatment device. For this purpose, after a predefined number of treatments, for example after ten treatments, the nomogram can be released for use, as a result of which the initially planned correction data can be adapted. This results in the advantage that the nomogram takes into account characteristic properties of the treatment device used.A further development provides that the nomogram is automatically updated. In other words, treatment results or postoperative data can be fed back to the treatment device and / or the control device, in particular using artificial intelligence, in order to complete the nomogram and / or to improve accuracy.It is preferably provided that the preceding treatment results are weighted with respect to time in the nomogram. In particular, provision can be made for more recent treatment results to be weighted higher than older treatment results. It can thus be ensured, inter alia, that a temporal change of the laser and / or of the treatment device is detected, as a result of which improved adapted correction data can be produced.A further advantageous development provides that the nomogram is newly generated after predefined periods of time and / or after a predefined number of new treatment results. In particular, it can be avoided that outliers find too strong a weighting in the nomogram. In addition, it is possible to react in an improved manner to changes in the laser and / or the treatment device. The predefined periods of time after which the nomogram is newly generated may be dependent, for example, on seasons, so that ambient conditions can be taken into account in an improved manner. The predetermined number, after which the nomogram can be newly generated, can take place, for example, after 100 or 200 treatments with the treatment device.A further development provides that the nomogram is based on a linear relationship between a planned refraction correction and a refraction correction achieved. This means that preferably a regression can be carried out between the planned and the achieved refraction correction, wherein the value for the adjusted correction parameters can be determined by means of this linear compensation function. This can preferably be carried out in each case for the sphere value, cylinder value and axis value. In particular, the nomogram can be present in different coordinate systems:The nomogram can be provided, for example, as a sphere and negative cylinder, wherein the adjusted correction values thus result from where S conv is the adjusted sphere value, S orig is the initially planned sphere value, C orig is the initially planned cylinder value, C conv is the adjusted cylinder value, A conv is the adjusted axis value and A orig is the initially planned axis value. Alternatively or additionally, the nomogram can also be represented as a sphere and positive cylinder.In an alternative embodiment, the nomogram can be provided using the spherical equivalent and the astigmatism (axis value). In this case, the change in the spherical equivalent achieved can be correlated with the planned change, and the absolute size of the cylindrical change achieved (vectorial analysis) can be correlated with the planned change. Furthermore, effects of a cyclotorsion of a residual astigmatism can also be taken into account, for example.In a further alternative embodiment, the nomogram can be provided on the basis of the principal meridians. In this case, the sphere, cylinder and axis values (spherocylindrical values; SCA) can be converted to the principal meridians, in particular by means ofIn a further alternative embodiment, the nomogram can be provided on the basis of a cardinal and oblique astigmatism according to the Jackson Kreuz cylinder, in which the sphere, cylinder and axis values are represented in M, C+, Cx. In particular, further power vector notations can also be used.For some strategies, the sphere, cylinder and axis values may be represented in M, C+, Cx, with this notation built on mathematically independent components (vector character). It is preferably also possible for the nomogram to be constructed from a plurality of variants and for the most likely variant to be selected statistically. Other types of nomograms can be calculated, if the data location is large enough, via a distance metric, for example, between the scheduled correction and the correction in the database. In this case, one can use the most similar with the smallest distance or all with a distance below a tolerance in order to generate the nomogram from this subset only.A further development provides that the nomogram is additionally provided as a function of patient parameters and / or environment parameters and / or laser parameters. That is, these parameters can be determined in the present treatment and a nomogram is retrieved, with treatment results of treatments in which these parameters were also present. For example, the parameters may comprise: laterality, i.e. information about a right or left eye, and / or a achieved treatment result of the other eye and / or a target refraction and / or a preoperative CDVA (best corrected vision, for example as with spectacles), and / or an ambiiyopia (value for a "bad" eye with a strong difference between the eyes), and / or a time after the treatment results have been determined, and / or a wavefront aberration and / or a UDVA (uncorrected vision) and / or an aspharicity and / or a planned transition zone and / or a planned optical zone and / or a repetition rate of the laser and / or a treatment duration and / or a water content of the cornea and / or an adaptation of the lens in order to focus an image, and / or a patient age and / or a corneal curvature and / or cross effects if, for example, a sphere is treated and, in addition, a cylindrical component arises, and / or a neuronal adaptation of the patient and / or an air humidity and / or an air pressure.A further development provides that the nomogram is determined on the basis of refraction values reached during preceding treatments and / or on the basis of topographical changes of the cornea reached during preceding treatments. In other words, the sphere, cylinder and axis value can be determined either by means of measurements of refraction, for example a subjective manifest refraction by means of a phoropter, or from measurements of morphology, for example topography measurements.Preferably, it is provided that at least two nomograms are provided, one on the basis of the refraction values and the other on the basis of the topographical change, wherein an adapted correction data range is determined, with limit values provided by the respective nomogram. That is, at least two nomograms are present, and values that can be provided from these nomograms can provide limit values for a range in which the adjustment can take place. In this case, a nomogram can be provided on the basis of refraction values which are present subjectively for the patient, and the other can be provided by means of objective measurements, in particular topography measurements which indicate a curvature of the cornea. Thus, it is possible to weight, for example, whether a treatment result is to provide an improved subjective refraction or an improved objective refraction. In particular, it can be provided that, if the initially planned correction data lie in the provided area, no adaptation can take place.A further development provides that a warning message is generated if the adapted correction data deviate from the initial correction data by a predefined limit value and / or if statistics of the nomogram for the correction data are below a threshold value. The warning message can preferably be output to a user via a user interface, in particular optically and / or acoustically, if the adapted correction data deviate from the initial correction data by a predefined limit value. For example, a relative limit value can be specified, in particular at 25 percent. Alternatively or additionally, a warning message may be generated and output if a statistic of the nomogram is below a threshold value. That is to say that either the entire nomogram has too little data to derive statistically significant values therefrom and / or a region of the nomogram in which the refraction correction takes place may have no or too little values, whereby a warning message is output. For example, at least ten treatments, preferably 20, may be provided before the nomogram can be used without warning.A further aspect relates to a method for controlling a treatment device. The method comprises the method steps of at least one embodiment of a method as described above. Furthermore, the method for controlling the treatment device also comprises the step of transmitting the provided control data to at least one ophthalmological laser of the treatment device and controlling the treatment device and / or the laser with the control data.The respective method can comprise at least one additional step which is executed exactly when a use case or an application situation occurs which has not been explicitly described here. The step may comprise, for example, outputting an error message and / or outputting a request to input a user feedback. Additionally or alternatively, it can be provided that a default setting and / or a predetermined initial state is set.A further aspect of the invention relates to a control device which is designed to carry out the steps of at least one embodiment of one or both of the methods described above. For this purpose, the control device can have a computing unit for electronic data processing, such as a processor. The computing unit can comprise at least one microcontroller and / or at least one microprocessor. The computing unit can be designed as an integrated circuit and / or microchip. Furthermore, the control device can comprise an (electronic) data memory or a storage unit. The data memory can store program code by which the steps of the respective embodiment of the respective method are encoded. The program code can comprise the control data for the respective laser. The program code can be executed by means of the arithmetic unit, as a result of which the control device is caused to execute the respective embodiment. The control device can be designed as a control chip or control device. The control device can be comprised, for example, by a computer or computer group.A further aspect of the invention relates to a treatment apparatus having at least one ophthalmic surgical or ophthalmic laser and a control device which is designed to carry out the steps of at least one embodiment of one or both of the methods described above. The respective laser can be designed to at least partially separate a predefined corneal volume with predefined boundary surfaces 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 bring about a laser-induced refractive index change in the cornea and / or the eye lens and / or to increase a cross-linking (cross-linking) of the cornea.In a further advantageous development 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, at a respective pulse duration between 1 fs and 1 ns, preferably between 10 fs and 10 ps, and at 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 region is subsumed in laser technology under the term "deep ultraviolet". This advantageously prevents unintentional damage to the cornea from occurring due to these very short-wave and high-energy beams. Photodisruptive and / or ablative lasers of the type used here usually introduce pulsed laser radiation with a pulse duration between 1 fs and 1 ns into the corneal tissue. As a result, the power density of the respective laser pulse required for the optical breakdown can be spatially narrowly limited, so that a high cutting accuracy is made possible during the generation of the boundary surfaces. The wavelength range selected can also be, in particular, the range between 700 nm and 780 nm.In a further advantageous development of the treatment apparatus 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 or sets comprise control data for positioning and / or for focusing individual laser pulses in the cornea / 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.A further aspect of the invention relates to a computer program. The computer program comprises instructions which form, for example, a program code. The program code can comprise at least one control data set with the respective control data for the respective laser. When the program code is executed by means of a computer or a computer group, it is caused to execute the method described above or at least one embodiment thereof.A further aspect of the invention relates to a computer-readable medium (storage medium) on which the aforementioned computer program or the instructions thereof are stored. For executing the computer program, a computer or a computer cluster can access the computer-readable medium and read its content. The storage medium is embodied, for example, as a data memory, in particular at least partially as a volatile or nonvolatile 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 may be present, for example, as source code of a programming language and / or as assembler and / or as binary code.Further features and advantages of one of the described aspects of the invention can be derived from the developments of another of the aspects of the invention. The features of the embodiments of the invention can thus be present in any combination with one another, provided they have not 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 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 the features of the embodiments. That is, the features of the embodiments may supplement and / or replace the features of the embodiments, and vice versa. Embodiments are therefore also to be considered as included and disclosed by the invention, which are not explicitly shown or explained in the figures, but which emerge from the exemplary embodiments and / or embodiments and can be generated by separate combinations of features. Embodiments are therefore also to be regarded as disclosed which do not have all features of an originally formulated claim or go beyond or deviate from the combinations of features set forth in the references back of the claims. The following shows the exemplary embodiments: FIG. 1 shows a schematic illustration of a treatment apparatus according to an exemplary embodiment; FIG. 2 shows a schematic method diagram for providing control data according to an exemplary embodiment; FIG. 3 shows an exemplary diagram with a refraction correction achieved and a planned refraction correction for providing a nomogram.In the figures, identical or functionally identical elements are provided with the same reference numerals.FIG. 1 shows a schematic representation of a treatment device 10 with an ophthalmological laser 12 for the removal of a tissue 14 from a human or animal cornea (cornea) 16 by means of photodisruption and / or ablation. The tissue 14 can be, for example, a lentivirus or else a volume body, which can be separated from the cornea 16 by the eye-surgical laser 12 in order to correct for a lack of vision. A geometry of the tissue 14 to be removed can be predefined by correction data which are provided to a control device 18, in particular in the form of control data, so that the laser 12 emits pulsed laser pulses in a pattern predefined by the control data into the cornea 16 of the eye in order to remove the tissue 14. Alternatively, the control device 18 can be a control device 18 external with respect to the treatment apparatus 10.Furthermore, FIG. 1 shows that the laser beam 20 generated by the laser 12 can be deflected in the direction of the cornea 16 by means of a beam deflection device 22, such as a rotation scanner, for example, in order to remove the tissue 14. The beam deflector 22 may also be controlled by the controller 18 to remove the tissue 14.The laser 12 illustrated can preferably be a photodisruptive and / or photoablative laser which is designed 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 with a repetition frequency greater than 10 kilohertz, preferably between 100 kilohertz and 100 megahertz. The control device 18 optionally also has a storage device (not shown) for at least temporarily storing at least one control data set, wherein the control data set or sets comprise control data for positioning and / or focusing individual laser pulses in the cornea.In the refraction correction by removing the tissue 14 from the cornea 16, it may occur that a planned refraction correction deviates from a refraction correction achieved. This may be dependent, for example, on characteristics of the treatment device, in particular a location and / or environmental conditions of the treatment device 10. In order to take these effects into account and to provide improved control data for refraction correction, the method shown in FIG. 2 can be carried out by the control device 18.In a step S 10, initial correction data for a planned refraction correction can be determined from predetermined examination data, wherein the correction data comprise a correction for at least one sphere value, a cylinder value and an axis value. The predetermined examination data can preferably be determined from a subjective measurement, for example by means of a phoropter, with which the corresponding sphere, cylinder and axis values for the treatment can be determined.In a step S 12, it can then be determined on the basis of a predetermined nomogram how the initially determined sphere, cylinder and axis values are to be adapted in order to achieve the originally planned refraction correction. In this case, the nomogram can preferably be adapted to the treatment device used, wherein previous treatment results in the nomogram, which have an achieved refraction correction with the treatment device 10, can be provided with the originally planned refraction correction.For example, FIG. 3 shows an exemplary representation of a refraction correction (ordinate) achieved with the corresponding planned refraction correction (abscissa), wherein the values at the top right in the positive range can represent the sphere values and the values at the bottom left in the negative range can represent the cylinder values. A corresponding diagram can preferably also be present for the axis values. Particularly preferably, other notations of the sphere, cylinder and axis values may also be provided.The nomogram provided can preferably be automatically updated, for example by an artificial intelligence playing back the treatment results or postoperative data to the treatment apparatus 10 and / or the control device 18 and supplementing or adapting the nomogram. In this case, it can be provided, for example, that the newly installed treatment results are weighted higher in time than old treatment results on account of the updatableness. In particular, it can be provided that after predetermined time periods and / or after a predetermined number of new treatment results, the nomogram is re-created. Alternatively, treatment results that have exceeded a predefined period of time can also be removed from the nomogram to date, so that the nomogram can always be kept at a current state.In particular, it can also be provided that the nomogram is provided on the basis of refraction values achieved, which are determined by means of subjective measurement methods, and additionally a second nomogram is provided, which is determined using objective measurement methods, in particular morphological measurements. From this, correction ranges can then be determined which have limit values which are provided by the respective nomograms.The initially determined correction data can then be adapted as a function of the nomogram, wherein the adapted correction data can be provided in a step S 14 in the form of control data to the control device 18 for controlling the laser 12 and / or the beam deflection device 22. That is, the treatment apparatus 10 can be controlled with the control data for refraction correction of the defective vision.Preferably, it can be provided that a warning message is generated if the adapted correction data deviate from the initial correction data by a predefined value and / or if statistics of the nomogram, i.e. detected treatment values, are below a threshold value.Overall, the examples show how automatic provision of nomograms can be achieved.

Claims

Method for providing control data for an ophthalmological laser (12) of a treatment apparatus (10), wherein the method has the following steps, carried out by means of a control device (18): - determination (S10) of correction data for a planned refraction correction of a refractive error of a cornea (16) from predetermined examination data, wherein the correction data comprise a correction for a sphere value, a cylinder value and an axis value; determining (S 12) adjusted correction data on the basis of a nomogram and the determined correction data, wherein the correction of the sphere value and / or the cylinder value and / or the axis value is adjusted to the treatment device (10) used by the nomogram, such that a refraction correction with the adjusted correction data corresponds to the planned refraction correction, wherein the nomogram is determined by previous treatment results with the same treatment devices; providing (S 14) the control data which are based on the adjusted correction data.Method according to claim 1, wherein the nomogram is determined by previous treatment results with the same treatment device (10).The method of any preceding claim, wherein the nomogram is automatically updated.The method of claim 3, wherein the previous treatment results are time weighted in the nomogram.Method according to one of claims 3 or 4, wherein the nomogram is newly generated after predefined periods of time and / or after a predefined number of new treatment results.Method according to one of the preceding claims, wherein the nomogram is based on a linear relationship between a planned refraction correction and a refraction correction achieved.Method according to one of the preceding claims, wherein the nomogram is additionally provided as a function of patient parameters and / or environment parameters and / or laser parameters.Method according to any one of the preceding claims, wherein the nomogram is determined on the basis of obtained refraction values in preceding treatments and / or on the basis of obtained topographical changes of the cornea in preceding treatments.Method according to claim 8, wherein at least two nomograms are provided, one on the basis of the refraction values and the other on the basis of the topographical change, wherein an adapted correction data range is determined, with limit values provided by the respective nomogram.Method according to one of the preceding claims, wherein a warning message is generated if the adapted correction data deviate from the initial correction data by a predefined limit value and / or if statistics of the nomogram for the correction data are below a threshold value.Control device (18) which is configured to carry out a method according to one of the preceding claims.Treatment device (10) having at least one eye-surgery laser (12) for separating a corneal volume (14) having predefined boundary surfaces 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 11.A computer program comprising instructions for causing the treatment device (10) of claim 12 to perform a method according to any one of claims 1 to 10.A computer readable medium having stored thereon a computer program according to claim 13.

Images