METHOD FOR CONTROLLING AN EYE SURGICAL LASER, TREATMENT APPARATUS, COMPUTER PROGRAM AS WELL AS COMPUTER-READABLE MEDIUM

Abstract

The invention relates to a method for controlling an eye surgical laser (18) for removing a volume body (12) from a cornea (44) with an anterior interface (16) of the cornea (44) and a posterior interface (14) of the cornea (44), comprising the steps of: presetting the posterior actual interface (14); determining a first imaging point (48) of the cornea (44); determining an anterior target interface (46) depending on the posterior actual interface (14) and the first imaging point (48) based on a mathematical model (M); determining a shape of the volume body (12) to be generated by presetting the determined anterior target interface (46); and generating control data for generating the volume body (12) such that the anterior actual interface (16) corresponds to the determined anterior target interface (46) after removing the volume body (12) from the cornea (44).

Further, the invention relates to a treatment apparatus (10), to a computer program product as well as to a computer-readable medium.

Claims

1. A method for controlling an eye surgical laser for removing a volume body from a human or animal cornea of an eye with an anterior actual interface of the cornea and a posterior actual interface of the cornea by means of a treatment apparatus, comprising the steps of: presetting the posterior actual interface depending on at least one preset parameter of the cornea by means of a control device of the treatment apparatus; determining a first imaging point of the cornea by means of the control device; determining an anterior target interface depending on the posterior actual interface and the first imaging point based on a mathematical model by means of the control device; determining a shape of the volume body to be generated by presetting the determined anterior target interface; and generating control data for generating the volume body such that the anterior actual interface corresponds to the determined anterior target interface after removing the volume body from the cornea.

2. The method according to claim 1, wherein in the mathematical model, a second imaging point is preset on a side of the cornea opposing a retina of the eye at a preset distance by means of the control device.

3. The method according to claim 1, wherein in the mathematical model, a second imaging point is preset on a side of the cornea opposing a retina of the eye at infinity.

4. The method according to claim 1, wherein a correction for an astigmatism is determined by means of the mathematical model.

5. The method according to claim 1, wherein a correction for a spherical aberration is determined by means of the mathematical model.

6. The method according to claim 1, wherein the first imaging point in the eye and a second imaging point at a preset distance in front of the eye and a thickness of the cornea and a refractive index (n) of the cornea are taken into account in the mathematical model.

7. The method according to claim 1, wherein the shape of the volume body is defined by a center of the volume body and/or by a geometric shape of the volume body and/or a diameter of the volume body.

8. The method according to claim 1, wherein the shape of the volume body is determined as the volume to be removed by subtraction of the preset, determined anterior target interface of the cornea from the anterior actual interface of the cornea.

9. The method according to claim 1, wherein for determining the anterior target interface, the position of the volume body is selected such that it is removed from the cornea.

10. The method according to claim 1, wherein when viewed in the direction of an optical axis of the eye, a position of the anterior target interface is determined to be located deeper than a position of the anterior actual interface.

11. The method according to claim 1, wherein a lenticular volume body is removed from the corneal volume by means of photodisruption or that the volume body is removed by means of an ablative method.

12. 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 100 nm and 1400 nm, in particular between 700 nm and 1200 nm, at a respective pulse duration between 1 fs and 20 ns, in particular between 10 fs and 10 ps, and a repetition frequency of greater than 1 kHz, in particular between 100 kHz and 10 MHz.

13. The method according to claim 1, wherein for determining the posterior actual interface and/or for determining the anterior actual interface and/or for determining the shape of the volume body, topographic and/or pachymetric and/or morphologic data of the cornea of the eye and/or of a lens of the eye is taken into account.

14. A treatment apparatus with at least one eye surgical laser and with at least one control device for the laser or lasers, which is formed to perform the steps of the method according to 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(s) control data for positioning and/or for focusing a laser beam into the eye; at least one control device with a mathematical model and for generating control data; 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.

16. A computer program including commands, which cause a treatment apparatus with at least one eye surgical laser and with at least one control device for the at least one eye surgical laser to execute the method steps according to claim 1.

17. A non-transitory 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 of an eye with an anterior actual interface of the cornea and a posterior actual interface of the cornea by means of a treatment apparatus, comprising the steps of: presetting the posterior actual interface depending on at least one preset parameter of the cornea by means of a control device of the treatment apparatus; determining a first imaging point of the cornea by means of the control device; determining an anterior target interface depending on the posterior actual interface and the first imaging point based on a mathematical model by means of the control device; determining a shape of the volume body to be generated by presetting the determined anterior target interface; and generating control data for generating the volume body such that the anterior actual interface corresponds to the determined anterior target interface after removing the volume body from the cornea.

19. The method for performing a surgical procedure according to claim 18, wherein in the mathematical model, a second imaging point is preset on a side of the cornea opposing a retina of the eye at a preset distance by means of the control device.

20. The method for performing a surgical procedure according to claim 18, wherein in the mathematical model, a second imaging point is preset on a side of the cornea opposing a retina of the eye at infinity.

21. The method for performing a surgical procedure according to claim 18, wherein a correction for an astigmatism is determined by means of the mathematical model.

22. The method for performing a surgical procedure according to claim 18, wherein a correction for a spherical aberration is determined by means of the mathematical model.

23. The method for performing a surgical procedure according to claim 18, wherein the first imaging point in the eye and a second imaging point at a preset distance in front of the eye and a thickness of the cornea and a refractive index (n) of the cornea are taken into account in the mathematical model.

24. The method for performing a surgical procedure according to claim 18, wherein the shape of the volume body is defined by a center of the volume body and/or by a geometric shape of the volume body and/or a diameter of the volume body.

25. The method for performing a surgical procedure according to claim 18, wherein the shape of the volume body is determined as the volume to be removed by subtraction of the preset, determined anterior target interface of the cornea from the anterior actual interface of the cornea.

26. The method for performing a surgical procedure according to claim 18, wherein for determining the anterior target interface, the position of the volume body is selected such that it is removed from the cornea.

27. The method for performing a surgical procedure according to claim 18, wherein when viewed in the direction of an optical axis of the eye, a position of the anterior target interface is determined located deeper than a position of the anterior actual interface.

28. The method for performing a surgical procedure according to claim 18, wherein a lenticular volume body is removed from the corneal volume by means of photodisruption or that the volume body is removed by means of an ablative method.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0036] 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.

[0037] FIG. 1 depicts a schematic side view of an embodiment of a treatment apparatus.

[0038] FIG. 2 depicts a further schematic side view of an embodiment of a treatment apparatus.

[0039] FIG. 3 depicts a schematic sectional view of an eye.

[0040] In the figures, identical or functionally identical elements are provided with the same reference characters.

DETAILED DESCRIPTION

[0041] 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. A cornea 44 (FIG. 3) comprises predefined interfaces 14, 16 (FIG. 2), wherein the cornea 44 is in particular that of a human or animal eye 42. The volume body 12 can be generated by means of photodisruption. Alternatively, the volume body 12 can also be removed by means of an ablative method. In particular, a posterior actual interface 14 and an anterior actual interface 16 of the cornea 44 are shown. 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 interfaces 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. The interfaces of the volume body 12 form a lenticular volume body 12 in the illustrated embodiment, 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), for example a visual disorder, 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.

[0042] 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.

[0043] The illustrated laser 18 is a photodisruptive laser or a 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. Alternatively, the laser 18 can also be formed for removing the volume body 12 by an ablative method.

[0044] In addition, the control device 20 comprises a storage device (not illustrated) for at least temporary storage of at least one control dataset, wherein the control dataset or datasets include(s) 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. Further, data, such as for example the shape and the position, of the posterior actual interface 14 of the cornea 44 and of the anterior actual interface 16 of the cornea 44 is also determined. Below, this data is also referred to as preset parameter.

[0045] 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 of the volume body 12 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 of the volume body 12 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 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.

[0046] In the illustrated embodiment, the interface located deeper, that is the interface of the volume body 12 located deeper in the eye 42 and the stroma 36, respectively, can first be generated by means of the laser beam 24. 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 of the volume body 12 located higher is generated in comparable manner such that the interfaces form the lenticular volume body 12. Subsequently, the incision 34 is also generated by the laser 18. However, the order of the generation of the interfaces of the volume body 12 and of the incision 34 can also be changed.

[0047] FIG. 3 shows a schematic sectional view according to an embodiment of the method. In particular, a sectional view of the eye 42 is shown. FIG. 3 shows the eye 42 with the posterior actual interface 14 as well as the anterior actual interface 16. Further, it is shown that an anterior target interface 46 is to be achieved and determined, respectively.

[0048] Thus, FIG. 3 shows that the posterior actual interface 14 is preset depending on at least one preset parameter of the cornea 44 by means of the control device 20. Determining a first imaging point 48, which is in particular located on a retina 50 of the eye 42, is effected by means of the control device 20. Then, determining the anterior target interface 46 depending on the posterior actual interface 14 and the first imaging point 48 is performed based on a mathematical model M by means of the control device 20. Subsequently, determining a shape of the volume body 12 to be generated is effected by presetting the determined anterior target interface 46. Subsequently thereto, the control data for generating the volume body 12 is determined such that the anterior actual interface 16 corresponds to the determined anterior target interface 46 after removing the volume body 12 from the cornea 44.

[0049] In particular, it is provided that the posterior actual interface 14 and the anterior actual interface 16 are determined based on topographic and/or pachymetric and/or morphologic data of the cornea 44 of the eye 42 and/or of a lens of the eye 42.

[0050] Further, it is in particular shown that the shape of the volume body 12 is determined as the volume to be removed by subtraction of the preset determined anterior target interface 46 from the anterior actual interface 16 of the cornea 44.

[0051] FIG. 3 further shows that in the mathematical model M, a second imaging point 52, 54 is preset on the side of the cornea 44 opposing the retina 50 of the eye 42 at a preset distance by means of the control device 20, wherein this presently in particular corresponds to the second imaging point 52. Further, the second imaging point 52, 54 can also be preset at infinity in front of the eye 42, wherein this is in particular represented by the reference character 54.

[0052] In particular, a correction for an astigmatism and/or a correction for a spherical aberration can be determined by means of the mathematical model M. In particular, the first imaging point 48 in the eye 42, the second imaging point 52, 54 at a preset distance in front of the eye 42, a thickness T of the cornea 44 and a refractive index n of the cornea 44 are taken into account by the mathematical model M.

[0053] Therein, the anterior interface, in particular the anterior target interface 46, can in particular be ascertained based on the parameters z.sub.a(x.sub.a, y.sub.a), wherein the index a in turn corresponds to the coordinates of the input surface. The output surface, thus the posterior actual interface 14, is in turn described based on the function z.sub.b(x.sub.b, y.sub.b), wherein the index b in turn stands for the outgoing surface, thus the posterior interface. Therein, z in particular corresponds to the direction of the incoming optical waves, wherein this direction can also be referred to as optical axis 30 of the eye 42. It is normally substantially rectangular to the input surface, thus the anterior interface. Thus, it is the object to describe the input function, thus the description of the anterior target interface 46, based on the preset posterior actual interface 14. Therein, the first imaging point 48 is in particular described by a focal length (f) on the imaging point such that z=f.sub.b can be written. Further, z is also dependent on a depth (T) or extension length of the cornea 44, as well as a focal length in front of the eye 42, which can be described by f.sub.a.

[0054] By application of the Snell's law, the formulas result:

[00004] $S \equiv \sqrt{z_{bx}^{2} + z_{by}^{2} + 1}$ $D \equiv \sqrt{x_{b}^{2} + y_{b}^{2} + {(z_{b} - f_{b})}^{2}}$ $L \equiv \sqrt{{(x_{a} - x_{b})}^{2} + {(y_{a} - y_{b})}^{2} + {(z_{a} - z_{b})}^{2}},$

wherein z.sub.b x corresponds to the partial derivatives at the locations x.sub.b and y.sub.b and z.sub.b y.sub.b corresponds to the partial derivative at the location x.sub.b. Therein, S and D are only dependent on the output surface, wherein L is dependent both on the input surface and on the output surface. D describes the 3-dimensional distance between an “object point” and a point of impingement on the lens, at which the light beam impinges on the surface of the lens, presently, D is the 3-dimensional distance between retina 50 and the posterior corneal surface, thus the posterior actual interface 14. L corresponds to the length of the path of the light beam within the cornea 44. S corresponds to an auxiliary parameter and indicates the overall slope.

[0055] By corresponding separation according to the Cartesian coordinate system, the following formulas arise:

[00005] $X \equiv \frac{x_{a} - x_{b}}{L} = \frac{x_{b} (z_{b_{y}}^{2} + 1) - z_{b_{x}} (y_{b} z_{b_{y}} + f_{b} - z_{b})}{{nDS}^{2}} - z_{b_{x}} \frac{Φ}{S}$ $Y \equiv \frac{y_{a} - y_{b}}{L} = \frac{y_{b} (z_{b_{x}}^{2} + 1) - z_{b_{y}} (x_{b} z_{b_{x}} + f_{b} - z_{b})}{{nDS}^{2}} - z_{b_{y}} \frac{Φ}{S}$ $Z \equiv \frac{z_{a} - z_{b}}{L} = \frac{(z_{b} - f_{b}) (z_{b_{x}}^{2} + z_{b_{y}}^{2}) + x_{b} z_{b_{x}} + y_{b} z_{b_{y}}}{{nDS}^{2}} + \frac{Φ}{S}$

Based thereon, the mathematical model M can then be created with the formulas:

[00006] $x_{a} = x_{b} + \frac{X (z_{a} - z_{b})}{Z}$ $y_{a} = y_{b} + \frac{Y (z_{a} - z_{b})}{Z}$ $z_{a} = \frac{g - \sqrt{g^{2} - h (n^{2} - 1)}}{n^{2} - 1}$ $with$ $g \equiv (z_{b} - f_{a} - T) Z^{2} + qZ + z_{b} (n^{2} - 1)$ $h \equiv {(x_{b}^{2} + y_{b}^{2} - z_{b}^{2} + T - f_{a})}^{2} - {(p - nT)}^{2}] Z^{2} - 2 z_{n} qZ - z_{b}^{2} (n^{2} - 1)$ $h \equiv - sgn (f_{b}) D + f_{b} - f_{a}$ $q \equiv x_{b} x + y_{b} Y - np + n^{2} T$

[0056] Now, this mathematical model M analytically describes the shape of the anterior target interface 46 depending on the posterior actual interface 14. Based on this anterior target interface 46 and based on the anterior actual interface 16, which can in particular also be already preset by the patient information, the shape of the volume body 12 to be removed can now be determined. Then, for example based on the difference from the anterior actual interface 16 to the anterior target interface 46, the shape of the volume body 12 can in turn be determined, which has to be removed to get from the anterior actual interface 16 to the anterior target interface 46.

[0057] Further, FIG. 3 in particular shows that the shape of the volume body 12 is defined by a center of the volume body 12 and/or by a geometric shape of the volume body 12 and/or by a diameter of the volume body 12.

[0058] Furthermore, it is in particular provided that for determining the anterior target interface 46, the position of the volume body 12 is selected such that it is removed from the cornea 44. Further, a position of the anterior target interface 46 is in particular determined located deeper than a position of the anterior actual interface 16 viewed in the direction of an optical axis 30 of the eye 42.

[0059] Further, a lenticular volume body 12 can in particular be removed from the corneal volume by means of photodisruption or the volume body 12 can be removed based on an ablative method.

METHOD FOR CONTROLLING AN EYE SURGICAL LASER, TREATMENT APPARATUS, COMPUTER PROGRAM AS WELL AS COMPUTER-READABLE MEDIUM

Inventors

Cpc classification

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A61F2009/00872

HUMAN NECESSITIES

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A61F9/00804

HUMAN NECESSITIES

Classification Explorer

A61F2009/00882

HUMAN NECESSITIES

Classification Explorer

A61D1/00

HUMAN NECESSITIES

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A61F9/00827

HUMAN NECESSITIES

International classification

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A61F9/008

HUMAN NECESSITIES

Abstract

Claims

Description