METHOD FOR CONTROLLING AN EYE SURGICAL LASER AND TREATMENT APPARATUS

Abstract

A method for controlling a surgical laser for the separation of a volume body, with predefined posterior and anterior interfaces, from a human or animal cornea is disclosed. The method including controlling the laser by means of a control device such that it emits pulsed laser pulses in a shot sequence into the cornea. The interfaces are generated by the generation of a plurality of cavitation bubbles generated by photodisruption by means of an interaction of the individual laser pulses with the cornea. A minimum diameter of the volume body orthogonal to an optical axis of the volume body is determined depending on at least one diopter value for the volume body and on a preset thickness of the volume body viewed in a direction of the optical axis. A treatment apparatus, a computer program product and a computer-readable storage medium are also disclosed.

Claims

1. A method for controlling an eye surgical laser for the separation of a volume body with a predefined posterior interface and a predefined anterior interface from a human or animal cornea, comprising: controlling the laser by means of a control device such that it emits pulsed laser pulses in a shot sequence into the cornea, wherein the interfaces are generated by the generation of a plurality of cavitation bubbles generated by photodisruption by means of an interaction of the individual laser pulses with the cornea, wherein a minimum diameter of the volume body orthogonal to an optical axis of the volume body is determined depending on at least one diopter value for the volume body and on a preset thickness of the volume body viewed in a direction of the optical axis.

2. The method according to claim 1, wherein a first diopter value for an optical zone of the volume body is preset as the at least one diopter value and/or a second diopter value for a transition zone of the volume body is preset as the at least one diopter value.

3. The method according to claim 2, wherein a first diameter of the optical zone is determined depending on the first diopter value and a second diameter of the transition zone is determined depending on the second diopter value and the minimum diameter of the volume body corresponds to the greater one of the two diameters.

4. The method according to claim 2, wherein the second diopter value of the transition zone is determined with a preset first diameter of the optical zone and with a preset second diameter of the transition zone.

5. The method according to claim 2, characterized in that wherein the second diopter value is determined with a preset first diopter value for determining the minimum diameter.

6. The method according to claim 1, wherein a plurality of potential control data for controlling the eye surgical laser is proposed for selection to a user of the eye surgical laser on a display device of the eye surgical laser.

7. The method according to claim 1, wherein a value of greater than 20 μm, in particular at least 24 μm, is preset as a minimum value for the preset thickness of the volume body.

8. The method according to claim 1, wherein control data is generated for an eye surgical laser formed as a femto laser in situ keratomileusis or for an eye surgical laser formed as a short incision lenticule extraction laser.

9. The method according to claim 1, wherein the control of the laser is performed considering the formula: $\begin{array}{cc}MLT=\max \left(\mathrm{abs}\left(S\right),\mathrm{abs}\left(C\right),\mathrm{abs}\left(S+C\right)\right)*\frac{{\mathrm{OZ}}^2}{8*\left(n-1\right)}+\mathrm{ThicknessTZ}& \end{array}$ wherein S corresponds to a spherical diopter value, C corresponds to a cylindrical diopter value, OZ corresponds to a diameter of the optical zone of the volume body, n corresponds to a refractive index of the cornea, Thickness Tz corresponds to a thickness of a transition zone and MLT corresponds to the preset thickness of the volume body.

10. The method according to claim 1, wherein the control of the laser is effected such that a transition zone is generated on the posterior interface such that the transition zone contacts the anterior interface or the transition zone is generated on the anterior interface such that the transition zone contacts the posterior interface.

11. The method according to claim 10, wherein the control of the laser is effected such that the transition zone contacts the anterior interface or the posterior interface at an acute angle.

12. The method according to claim 1, wherein the control of the laser is effected such that topographic and/or pachymetric and/or morphologic data of the cornea are taken into account.

13. The method according to claim 1, wherein the control of the laser is effected such that the laser emits laser pulses in a wavelength range between 300 nm and 1400 nm, in particular between 700 nm and 1200 nm, at a respective pulse duration between 1 fs and 1 ns, in particular between 10 fs and 10 ps, and a repetition frequency of greater than 10 kHz, in particular between 100 kHz and 10 MHz.

14. A treatment apparatus with at least one surgical laser for the separation of a volume body with predefined interfaces of a human or animal eye by means of photodisruption and with at least one control device, which is formed for controlling the according to a method of claim 1.

15. The treatment apparatus according to claim 14, 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 for focusing individual laser pulses in the cornea; and at least one beam device for at least one of beam guidance, beam shaping, beam deflection, and beam focusing of a laser beam of the laser.

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

17. A computer-readable medium, on which the computer program according to claim 16 is stored.

18. A method for performing a surgical procedure on a human or animal cornea for the separation of a volume body from the cornea, wherein interfaces are generated by the generation of a plurality of cavitation bubbles generated by photodisruption by means of an interaction of individual laser pulses with the cornea, wherein a minimum diameter of the volume body orthogonal to an optical axis of the volume body is determined depending on at least one diopter value for the volume body and on a preset thickness of the volume body viewed in a direction of the optical axis.

19. The method for performing a surgical procedure according to claim 18, wherein a first diopter value for an optical zone of the volume body is preset as the at least one diopter value and/or a second diopter value for a transition zone of the volume body is preset as the at least one diopter value.

20. The method for performing a surgical procedure according to claim 19, wherein a first diameter of the optical zone is determined depending on the first diopter value and a second diameter of the transition zone is determined depending on the second diopter value and the minimum diameter of the volume body corresponds to the greater one of the two diameters.

21. The method for performing a surgical procedure according to claim 19, wherein the second diopter value of the transition zone is determined with a preset first diameter of the optical zone and with a preset second diameter of the transition zone.

22. The method for performing a surgical procedure according to claim 19, wherein the second diopter value is determined with a preset first diopter value for determining the minimum diameter.

23. The method for performing a surgical procedure according to claim 18, wherein a plurality of potential control data for controlling the eye surgical laser is proposed for selection to a user of the eye surgical laser on a display device of the eye surgical laser.

24. The method for performing a surgical procedure according to claim 18, wherein a value of greater than 20 μm, in particular at least 24 μm, is preset as a minimum value for the preset thickness of the volume body.

25. The method for performing a surgical procedure according to claim 18, wherein control data is generated for an eye surgical laser formed as a femto laser in situ keratomileusis or for an eye surgical laser formed as a short incision lenticule extraction laser.

26. The method for performing a surgical procedure according to claim 18, wherein the method is performed considering the formula: $\begin{array}{cc}MLT=\max \left(\mathrm{abs}\left(S\right),\mathrm{abs}\left(C\right),\mathrm{abs}\left(S+C\right)\right)*\frac{{\mathrm{OZ}}^2}{8*\left(n-1\right)}+\mathrm{ThicknessTZ}& \end{array}$ wherein S corresponds to a spherical diopter value, C corresponds to a cylindrical diopter value, OZ corresponds to a diameter of the optical zone of the volume body, n corresponds to a refractive index of the cornea, Thickness Tz corresponds to a thickness of a transition zone and MLT corresponds to the preset thickness of the volume body.

27. The method for performing a surgical procedure according to claim 18, wherein a transition zone is generated on the posterior interface such that the transition zone contacts the anterior interface or the transition zone is generated on the anterior interface such that the transition zone contacts the posterior interface.

28. The method for performing a surgical procedure according to claim 27, wherein the transition zone contacts the anterior interface or the posterior interface at an acute angle.

Description

[0029] Further features 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.

The Figures show the following.

[0030] FIG. 1 is a schematic side view of an embodiment of a treatment apparatus.

[0031] FIG. 2 is a further schematic side view of an embodiment of a treatment apparatus.

[0032] FIG. 3 is a schematic side view of an eye.

[0033] FIG. 4 is a schematic top view to a volume body.

[0034] In the figures, identical or functionally identical elements are provided with the same reference characters.

[0035] FIG. 1 shows a schematic representation of a treatment apparatus 10 with an eye surgical laser 18 for the separation of a predefined corneal volume or volume body 12 with predefined interfaces 14, 16 in a cornea 44 (FIG. 3) of a human or animal eye 42 by means of photodisruption. One recognizes that a control device 20 for the laser 18 is formed besides the laser 18 such that it emits pulsed laser pulses for example in a predefined pattern into the cornea 44, wherein the interfaces 14, 16 of the volume body 12 to be separated are generated by the predefined pattern by means of photodisruption. The treatment apparatus 10 can also comprise further control devices. In the illustrated embodiment, the interfaces 14, 16 form a lenticular volume body 12, wherein the position of the volume body 12 is selected in this embodiment such that a pathological and/or unnaturally altered area 32 (see FIG. 2) within a stroma 36 of the cornea 44 is enclosed. Furthermore, it is apparent from FIG. 1 that the so-called Bowman's membrane 38 is formed between the stroma 36 and an epithelium 28.

[0036] Furthermore, one recognizes 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 mentioned predefined pattern in the cornea.

[0037] The illustrated laser 18 is 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.

[0038] The control device 20 additionally 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 44. The position data and/or focusing data of the individual laser pulses are generated based on a previously measured topography and/or pachymetry and/or the morphology of the cornea and the pathological and/or unnaturally altered area 32 for example to be removed or the optical visual disorder correction to be generated within the stroma 36 of the eye 42.

[0039] FIG. 2 shows a schematic diagram of the generation of the volume body 12 to be separated according to an embodiment of the present method. One recognizes that the interfaces 14, 16 are generated by means of the pulsed laser beam 24, which is directed towards the cornea 44 or towards the surface 26 of the cornea 44 via the beam deflection device 22. Therein, the interfaces 14, 16 form a lenticular volume body 12, which for example encloses the pathological and/or unnaturally altered area 32 within the stroma 36. Furthermore, the laser 18 generates a further incision 34 in the illustrated embodiment, which intersects the volume body 12 at a predefined angle and with a predefined geometry and is formed up to the surface 26 of the cornea 44. The volume body 12 defined by the interfaces 14, 16 can then be removed from the cornea 44 via the incision 34. In the illustrated embodiment, the pathological and/or unnaturally altered area 32 is formed within the stroma 36 and outside of an optical axis 30 of the eye 42.

[0040] In the illustrated embodiment, the interface 14, that is the interface located deeper in the eye 42 or the stroma 36, is first formed by means of the laser beam 24, wherein it then corresponds to the posterior interface 14. This can be effected by at least partially circularly and/or spirally guiding the laser beam 24 according to the predefined pattern. Subsequently, the interface 16 is generated in comparable manner, which then corresponds to the anterior interface 16, such that the interfaces 14, 16 form the lenticular volume body 12 (see also FIG. 1). Subsequently, the incision 34 is also generated by the laser 18. However, the order of the generation of the interfaces 14, 16 and of the incision 34 can also be changed.

[0041] FIG. 3 shows a schematic side view of the eye 42, in particular, the cornea 44 is shown, wherein the cornea 44 in particular describes a corneal volume. In the present embodiment, the volume body 12 is in particular shown as a myopic profile. This in particular means that a preset thickness 46 of the volume body 12 is located in the center of the volume body 12. The preset thickness 46 of the volume body 12 is in particular formed viewed in the direction of an optical axis 48 of the volume body 12. Further, FIG. 3 shows that the volume body 12 can have a diameter 50 of the lenticule as well as a cap diameter 52 corresponding to a diameter of the upper incision, thus the anterior interface 16. Preferably, the cap diameter 52 is greater than the lenticule diameter. In particular, the volume body 12 is removed from the eye 42 via an incision 54, which corresponds to the incision 34 from FIG. 2.

[0042] In particular, it is provided that the laser 18 is controlled by means of the control device 20 such that it emits pulsed laser pulses in a shot sequence into the cornea 44, wherein the interfaces 14, 16 are generated by the generation of a plurality of cavitation bubbles 40 generated by photodisruption by means of an interaction of the individual laser pulses with the cornea 44, wherein a minimum diameter 50 of the volume body 12, which presently corresponds to the lenticule diameter, orthogonal to the optical axis 48 of the volume body 12 is determined depending on at least one diopter value for the volume body 12 and the preset thickness 46 of the volume body 12 viewed in a direction of the optical axis 48.

[0043] In the present embodiment, the anterior interface 16 in particular corresponds to a so-called upper incision and the posterior interface 14 corresponds to a lower incision. On the respective sides of the lower incision, presently thus of the posterior interface 14, there is a so-called transitions zone 56. An optical zone 58 is presently in particular formed on the posterior interface 14. In the present embodiment, thus, the optical zone 58 and the transition zone 56 form the posterior interface 14. Presently, the transition zone 56 contacts the anterior interface 14 presently at the respective outer edge thereof, preferably at an acute angle. Thus, an additional incision is not required to connect the anterior interface 16 to the posterior interface 14 and to form the extractable volume body 12.

[0044] In particular, it can be provided that a first diopter value is preset as the at least one diopter value for the optical zone 58 of the volume body 12 and/or a second diopter value is preset as the at least one diopter value for the transition zone 56 of the volume body 12. Further, a first diameter of the optical zone 58 can be determined depending on the first diopter value, and a second diameter of the transition zone 56 can be determined depending on the second diopter value, and the minimum diameter 50 then corresponds to the greater one of the two diameters.

[0045] Further, it can be provided that the second diopter value of the transition zone 56 is determined with a preset first diameter of the optical zone 58 and with a preset second diameter of the transition zone 56. Further, the second diopter value can be determined with a preset first diopter value for determining the minimum diameter 50.

[0046] Further, it can in particular be provided that a value of greater than 20 μm, in particular at least 24 μm, is preset as a minimum value for the preset thickness 46 of the volume body 12.

[0047] Furthermore, it can be provided that a plurality of potential control data for controlling the eye surgical laser 18 is proposed for selection to a user of the eye surgical laser 18 on a display device 60 (FIG. 1) of the eye surgical laser 18 or the treatment apparatus 10. For example, a following table can be displayed on the display device 60 for the user. Therein, the first table displays the first diameter of the optical zone 58, which should be selected greater than the value indicated in the table. In the first row, the preset minimum thickness 46 is registered. For example, the optical zone should have at least a first diameter of 5.2 mm with a diopter value of −3.0 and with a preset thickness 46 of 27 μm.

TABLE-US-00001 Diopter value Thickness 18 μm Thickness 27 μm Thickness 36 μm −6.0 3.0 3.7 4.2 −5.5 3.1 3.8 4.4 −5.0 3.3 4.0 4.7 −4.5 3.5 4.2 4.9 −4.0 3.7 4.5 5.2 −3.5 3.9 4.8 5.6 −3.0 4.2 5.2 6.0 −2.5 4.7 5.7 6.6 −2.0 5.2 6.4 7.4 −1.5 6.0 7.4 8.5 −1.0 7.4 9.7 10.4 −0.5 10.4 12.7 14.7

[0048] The second table shows the first diameter for the effective minimum optical zone 58 at the thicknesses 46 demonstrated in table 1, wherein it is limited by the limit values of 5.5 mm and 7.5 mm due to treatment restrictions.

TABLE-US-00002 Diopter value Eff. min OZ Eff. min OZ Eff. min OZ −6.0 5.5 5.5 5.5 −5.5 5.5 5.5 5.5 −5.0 5.5 5.5 5.5 −4.5 5.5 5.5 5.5 −4.0 5.5 5.5 5.5 −3.5 5.5 5.5 5.6 −3.0 5.5 5.5 6.0 −2.5 5.5 5.7 6.6 −2.0 5.5 6.4 7.4 −1.5 6.0 7.4 7.5 −1.0 7.4 7.5 7.5 −0.5 7.5 7.5 7.5

[0049] The third table in particular displays the determined minimum thickness 46 in mm, which would have to be used with the corresponding diopter values to achieve the desired correction and to consider the effective minimum optical zone 58.

TABLE-US-00003 Diopter value Thickness 18 μm Thickness 27 μm Thickness 36 μm −6.0 60 60 60 −5.5 55 55 55 −5.0 50 50 50 −4.5 45 45 45 −4.0 40 40 40 −3.5 35 35 36 −3.0 30 30 36 −2.5 25 27 36 −2.0 20 27 36 −1.5 18 27 28 −1.0 18 19 19 −0.5 9 9 9

[0050] The fourth table now shows the evaluation considering table three if a correction with the preset thickness 46 is possible.

TABLE-US-00004 Diopter value possible possible possible −6.0 yes yes yes −5.5 yes yes yes −5.0 yes yes yes −4.5 yes yes yes −4.0 yes yes yes −3.5 yes yes yes −3.0 yes yes yes −2.5 yes yes yes −2.0 yes yes yes −1.5 yes yes no −1.0 yes no no −0.5 no no no

[0051] In particular, it is shown that not every correction is possible considering a preset thickness 46.

[0052] The tables 1 to 4 listed above are in particular generated based on the following formula. The control of the laser 18 is in particular effected considering the formula

[00003]$\begin{array}{cc}MLT=\max \left(\mathrm{abs}\left(S\right),\mathrm{abs}\left(C\right),\mathrm{abs}\left(S+C\right)\right)*\frac{{\mathrm{OZ}}^2}{8*\left(n-1\right)}+\mathrm{ThicknessTZ}& \end{array}$

[0053] wherein S corresponds to a spherical diopter value, C corresponds to a cylindrical diopter value, OZ corresponds to a diameter of the optical zone 58 of the volume body 12, n corresponds to a refractive index of the cornea 44, Thickness Tz corresponds to a thickness of the transition zone 56 and MLT corresponds to the thickness 46 of the volume body 12.

[0054] FIG. 4 shows an embodiment of the volume body 12 to be removed in a schematic top view. In particular, the anterior interface 16 is shown. Presently, it is in particular shown that the volume body 12 has a cylindrical shape. Further, circular cavitation bubble paths are indicated. Here, it is in particular seen that the preset thickness 46 is substantially demonstrated along a line. Alternatively, other shapes of the volume body 12 can also be removed from the eye 42, in particular from the cornea 44. Therein, the preset thickness 46 always corresponds to the location with the maximum thickness of the volume body 12. In particular, it is thus provided that the minimum thickness 46 for this location is preset at the maximum thickness of the volume body 12. Herein, it is in particular to be ensured that in particular at least 20 μm, preferably at least 24 μm, are preset as the minimum thickness 46.

[0055] Further, it can in particular be provided that the first diopter value of the optical zone 58 is between −0.5 diopters and −12 diopters, typically −4 diopters. The second diopter value of the transition zone 56 is in particular between 0 diopters and −4 diopters, typically at approximately −2 diopters. The optical zone 58 typically has a first diameter between 5.5 mm and 7.5 mm, in particular for example 6.75 mm. The diameter of the transition zone 56, thus the second diameter, is in particular between 0 and 2.5 mm greater than the first diameter of the optical zone 58, typically greater by about 1.5 mm. The cap diameter 52 is for example at 6.5 to 9 mm, typically at 8 mm. A preset thickness of the cap, which is located between the surface 26 and the anterior interface 16, can for example be between 100 and 160 μm, typically about 120 μm. The incision 54 in particular has an angle between 45° and 135°, typically about 90°. The position of the incision 54 can be between 0° and 360°, typically at about 90°, wherein this is dependent on the eye, in particular depending on the fact if it is a left or right eye 42. The length of the incision 54 can for example be between 1.5 and 4 mm, typically about 3 mm.