METHOD FOR PROVIDING CONTROL DATA FOR AN EYE SURGICAL LASER OF A TREATMENT APPARATUS

Abstract

The invention relates to a method for providing control data of an eye surgical laser (18). A control device (20) ascertains (S1) a lenticule geometry of a lenticule (12) to be separated from predetermined visual disorder data of a human or animal eye (36), wherein the lenticule geometry is defined by means of a refractive power value to be corrected and a lenticule diameter, ascertains (S2) a correction value for compensating for a deformation of the lenticule (12), which is generated by at least one contact element (28) of the treatment apparatus (10), wherein the correction value is determined by means of at least one preceding measurement of the treatment apparatus (10), ascertains (S3) a deformation geometry of the lenticule (12), wherein a deformation refractive power value is calculated depending on the refractive power value to be corrected and the correction value and a deformation diameter is calculated depending on the lenticule diameter and the correction value, and provides (S4) control data for controlling the eye surgical laser (18), which uses the deformation geometry for the separation of the lenticule (12).

Claims

1. A method for providing control data of an eye surgical laser of a treatment apparatus for the separation of a lenticule, wherein the method comprises the following steps performed by a control device: ascertaining a lenticule geometry of the lenticule to be separated from predetermined visual disorder data of a human or animal eye, wherein the lenticule geometry is defined by means of a refractive power value to be corrected and a lenticule diameter; ascertaining a correction value for compensating for a deformation of the lenticule, which is generated by at least one contact element of the treatment apparatus, wherein the correction value is determined by means of at least one preceding measurement of the treatment apparatus; ascertaining a deformation geometry of the lenticule, wherein the deformation geometry is defined by means of a deformation refractive power value and a deformation diameter, wherein the deformation refractive power value is calculated depending on the refractive power value to be corrected and the correction value and the deformation diameter is calculated depending on the lenticule diameter and the correction value; and providing control data for controlling the eye surgical laser, which uses the deformation geometry for separating the lenticule.

2. The method according to claim 1, wherein the correction value is ascertained from a deviation of the refractive power value to be corrected and an achieved refractive power value, and wherein the achieved refractive power value is determined after an application of the treatment apparatus without use of the deformation geometry.

3. The method according to claim 2, wherein the correction value is statistically determined from multiple preceding measurements of the refractive power value to be corrected and the achieved refractive power value.

4. The method according to claim 2, wherein the achieved refractive power value is determined at least at two different points of time, wherein the correction value is ascertained from an average value of the deviations at the at least two different points of time.

5. The method according to claim 1, wherein the correction value is in a range from 0.6 to 1.4.

6. The method according to claim 1, wherein a lenticule height or a lenticule volume is kept constant in the calculation of the deformation geometry, and wherein the deformation refractive power value is calculated by means of a multiplication of the refractive power value to be corrected by a reciprocal value of the correction value.

7. The method according to claim 1, wherein the deformation diameter is calculated by means of a multiplication of the lenticule diameter by a parameter depending on the correction value, wherein the parameter is determined by means of a theoretical lenticule geometry model.

8. The method according to claim 6, wherein the deformation diameter is calculated by means of a multiplication of the lenticule diameter by the square root of the correction value with a lenticule height kept constant and the deformation diameter is calculated by means of a multiplication of the lenticule diameter by the fourth root of the correction value with a lenticule volume kept constant.

9. A control device, which is configured to perform a method according to claim 1.

10. A treatment apparatus with at least one eye surgical laser for the separation of a lenticule of a human or animal eye by means of photodisruption and at least one control device according to claim 9.

11. The treatment apparatus according to claim 10, wherein the laser is formed to emit laser pulses in a wavelength range between 300 nm and 1400 nm, at a respective pulse duration between 1 fs and 1 ns, and a repetition frequency of greater than 10 kHz.

12. The treatment apparatus according to claim 10, wherein the control device comprises at least one storage device for at least temporary storage of at least one control dataset, wherein the control dataset or datasets include control data for positioning and/or focusing individual laser pulses in the cornea; and includes 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.

13. A computer program including instructions, which cause a treatment apparatus with at least one eye surgical laser for the separation of a lenticule of a human or animal eye by means of photodisruption, and at least one control device to execute a method according to claim 1.

14. A computer-readable medium, on which the computer program according to claim 13 is stored.

15. The method according to claim 3, wherein the correction value is statistically determined by means of a linear regression.

16. The method according to claim 5, wherein the correction value is in a range from 0.7 to 1.0.

17. The method according to claim 7, wherein the parameter is determined by means of the Munnerlyn formula.

18. The method according to claim 7, wherein the deformation diameter is calculated by means of a multiplication of the lenticule diameter by the square root of the correction value with a lenticule height kept constant and the deformation diameter is calculated by means of a multiplication of the lenticule diameter by the fourth root of the correction value with a lenticule volume kept constant.

19. The treatment apparatus according to claim 11, wherein the laser is formed to emit laser pulses in a wavelength range between 700 nm and 1200 nm, at a respective pulse duration between 10 fs and 10 ps, and a repetition frequency of between 100 kHz and 100 MHz.

Description

[0024] Further features of the invention are apparent from the claims, the figures and the description of figures. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of figures and/or shown in the figures alone are usable not only in the respectively specified combination, but also in other combinations without departing from the scope of the invention. Thus, implementations are also to be considered as encompassed and disclosed by the invention, which are not explicitly shown in the figures and explained, but arise from and can be generated by separated feature combinations from the explained implementations. Implementations and feature combinations are also to be considered as disclosed, which thus do not comprise all of the features of an originally formulated independent claim. Moreover, implementations and feature combinations are to be considered as disclosed, in particular by the implementations set out above, which extend beyond or deviate from the feature combinations set out in the relations of the claims.

[0025] FIG. 1 shows a schematic representation of a treatment apparatus according to the invention according to an exemplary embodiment.

[0026] FIG. 2 shows an exemplary scatter plot of planned and achieved refractive power values

[0027] FIG. 3 shows a schematic method diagram according to an exemplary embodiment.

[0028] In the figures, identical or functionally identical elements are provided with the same reference characters.

[0029] FIG. 1 shows a schematic representation of a treatment apparatus 10 with an eye surgical laser 18 for the separation of a corneal volume/cornea volume predefined by a lenticule geometry of a cornea of a human or animal eye 36, thus a lenticule 12, which can also be referred to as volume body, with predefined interfaces 14, 16 by means of photodisruption. One recognizes that a control device 20 for the laser 18 can be formed besides the laser 18 such that it emits pulsed laser pulses for example in a predefined pattern into the cornea of the eye 36, wherein the ascertained interfaces 14, 16 of the lenticule 12 to be formed can for example be generated by a predefined pattern by means of photodisruption. Alternatively, the control device 20 can be a control device 20 external with respect to the treatment apparatus 10.

[0030] The ascertained interfaces 14, 16 form a lenticule 12 in the illustrated embodiment, wherein the position of the lenticule 12 is selected in this embodiment such that it can for example be located within a stroma 32 of the cornea. Furthermore, it is apparent from FIG. 1 that the so-called Bowman's membrane 34 can be formed between the stroma 32 and an epithelium.

[0031] Furthermore, FIG. 1 shows that the laser beam 24 generated by the laser 18 is deflected towards a surface 26 of the cornea by means of a beam device 22, namely a beam deflection device, such as for example a rotation scanner. The beam deflection device is also controlled by the control device 20 to generate the ascertained interfaces 14, 16, preferably also incisions or cuts 30, along preset incision progressions.

[0032] Preferably, the illustrated laser 18 can be a photodisruptive laser, which is formed to emit laser pulses in a wavelength range between 300 nm and 1400 nm, preferably between 700 nm and 1200 nm, at a respective pulse duration between 1 fs and 1 ns, preferably between 10 fs and 10 ps, and a repetition frequency of greater than 10 kHz, preferably between 100 kHz and 100 MHz. Additionally, the control device 20 optionally comprises a storage device (not illustrated) for at least temporary storage of at least one control dataset, wherein the control dataset or datasets include control data for positioning and/or for focusing individual laser pulses in the cornea. The position data and/or focusing data of the individual laser pulses, that is the lenticule geometry of the lenticule 12 to be separated, are generated based on predetermined visual disorder data, in particular from a previously measured topography and/or pachymetry and/or the morphology of the cornea or the optical visual disorder correction to be generated exemplarily within the stroma 32 of the eye 36. For determining the visual disorder data, which can for example indicate a value in diopters, or other suitable data for describing the visual disorder, the control device 20 can for example receive the corresponding data from a data server or the visual disorder data can be determined as a data input. The lenticule geometry of the lenticule 12 to be separated for correcting the visual disorder is in particular defined by means of a refractive power value to be corrected, which can also be referred to as planned refractive power value, and a lenticule diameter, which is also referred to as optical zone.

[0033] Further, a contact element 28 can be provided, which can be associated with the treatment apparatus 10. Alternatively, the contact element 28 can also be provided separately from the treatment apparatus 10. The contact element 28, which can be referred to as patient interface or fixing system, serves to fix the eye 36 for the treatment. Hereto, the contact element 28 can comprise a plano-concave lens, which is adapted to the eye 36 for fixing. By fixing by means of the contact element 28, however, it can occur that the cornea deforms and thus the ascertained lenticule geometry for separating the lenticule 12 does no longer optimally apply to the predetermined visual disorder data. Therefore, it can occur that a planned refractive power value or refractive power value to be corrected deviates from an achieved refractive power value after the treatment with the treatment apparatus 10.

[0034] This is illustrated in an exemplary scatter plot of FIG. 2, wherein the achieved refractive power value after the treatment is represented on the Y-axis and the refractive power value to be corrected, which has been planned by means of the predetermined visual disorder data, is represented on the X-axis. This means that for each represented point, the value on the X-axis has been planned and the value on the Y-axis has been achieved. Furthermore, these deviations in FIG. 2 are plotted for one day after the treatment (circles), for example data point d1, and for one week after the treatment (squares), for example data point w1.

[0035] In order to compensate for this deformation caused by the contact element 28, it can be provided that the control device 20 performs the method steps S1 to S4 described below, which are for example presented as a method diagram in FIG. 3. In step S1, as described above, the lenticule geometry of the lenticule 12 to be separated is determined from the predetermined visual disorder data, wherein the lenticule geometry is defined by means of the refractive power value to be corrected and the lenticule diameter. Subsequently, a correction value for compensating for the deformation by the contact element 28 can be determined from at least one preceding measurement with the treatment apparatus 10 in step S2. Hereto, the scatter plot from FIG. 2 can for example be used, wherein a linear regression LR_d1 of the refractive power values to be corrected and the achieved refractive power values on the first day after the treatment is in particular statistically determined and a linear regression LR_w1 at the further point of time one week after the treatment is preferably also formed. For example, a slope of the regression line LR_d1 can have a value of 0.77, which would correspond to a 23 percent deviation one day after the treatment, and the regression line LR_w1 can for example have a slope of 0.83, which would correspond to a 17 percent deviation one week after the treatment. This means that the correction value is preferably between 0.77 and 0.83 in this example, wherein the correction value can preferably be formed from an average value of this range of values. Thus, at 0.8 in this embodiment. However, the previously shown numbers are only to represent examples of the correction value and the correction value can for example be different according to treatment apparatus and associated contact element. A type of the treatment, that is depending on the visual disorder data, can also change the correction value. In particular, the correction value can be in a range from 0.6 to 1.4, preferably in a range from 0.7 to 1.0.

[0036] After ascertaining the correction value, a deformation geometry of the lenticule can be ascertained by the control device in step S3, wherein the deformation geometry is defined by means of a deformation refractive power value and a deformation diameter. The deformation refractive power value can be calculated depending on the refractive power value to be corrected, that is the previously planned refractive power value, from the initially planned lenticule geometry and the correction value in that the refractive power value to be corrected is divided by the correction value. In other words, the planned refractive power value is divided by the correction value, thus by 0.8 according to the above example, to obtain the deformation refractive power value. Furthermore, it can be selected in step S3 if a lenticule height or a lenticule volume is kept constant, that is if the lenticule height ascertained in the lenticule geometry or the lenticule volume is adopted for the deformation geometry.

[0037] If the lenticule height is to be adopted, a deformation diameter of the deformation geometry can be calculated depending on the lenticule diameter and the correction value in that the lenticule diameter is calculated with a parameter depending on the correction value, wherein the parameter is determined by means of a theoretical lenticule geometry model. For example, the lenticule geometry model can be that model, by means of which the lenticule geometry was previously determined. Preferably, the lenticule geometry model can be the Munnerlyn formula, wherein the parameter depending on the correction value is therein the square root of the correction value. This means that the deformation diameter is calculated with the lenticule height kept constant in that the lenticule diameter is multiplied by the square root of the correction value, thus by the root of 0.8 in the above example. If the lenticule volume is to be kept constant, another parameter depending on the correction value is calculated by means of the theoretical lenticule model, which corresponds to the fourth root of the correction value in case of the Munnerlyn formula. This means that the deformation diameter is calculated by means of a multiplication of the lenticule diameter by the fourth root of the correction value, thus by 0.8 to the power of 0.25 in the above example, with the lenticule volume kept constant.

[0038] The deformation geometry thus determined can then be provided in the form of control data for controlling the eye surgical laser 18 by the control device 20 in a step S4. By means of the thus provided control data, which uses the deformation geometry for separating the lenticule, a compensation for the deformation by the contact element 28 can be achieved in simple manner, whereby a treatment with the treatment apparatus 10 can be improved. The treatment can also be continuously improved by means of the method since the correction value can be iteratively adapted. For example, the correction value can first be determined as 0.8. After further measurements with application of this correction value, a deviation of 1.05 can then for example still be ascertained, whereupon the original correction value of 0.8 is multiplied by 1.05 and thus results in an iteratively adapted correction value of 0.84. Accordingly, the correction value can also be iteratively refined for the treatment apparatus.