Devices and method for generating control data with an optimised cut geometry for edge zone cuts during correction of the refraction of an eye

Abstract

The present invention relates to a planning unit and a planning method, and to an ophthalmological laser therapy device for generating control data with an optimised cut geometry for edge zone cuts during correction of the refraction of an eye having an optical main axis and a cornea by means of cornea modification. The method comprises receiving data representing a need for refractive correction, calculating a tissue volume of the cornea to be removed and calculating cut surface data, wherein the cut surface data comprise cap cut data, lenticule cut data, optionally side cut data and access cut data. The invention further relates to a computer program product, a data signal, a computer-readable non-volatile storage medium and a therapeutic method for correcting the refraction of an eye.

Description

[0001] Devices and methods for generating control data with an optimized cutting geometry for marginal zone cuts during a correction of the refraction of an eye

[0002] The present invention relates to a planning unit, an ophthalmological laser therapy device and a planning method for generating control data with an optimized cutting geometry for marginal zone cuts when correcting the refraction of an eye with a main optical axis and a cornea by corneal modification within the tissue.

[0003] The planning unit comprises a data processing device which is designed to receive data representing a refractive correction requirement, to calculate a tissue volume of the cornea to be removed, wherein the calculation is carried out on the basis of the refractive correction requirement, and to calculate cutting surface data which represent at least one cutting surface completely delimiting the tissue volume.The sectional area data includes cap section data representing a cap section that delimits the tissue volume anteriorly, lenticule section data representing a lenticule section with a lenticule radius that delimits the tissue volume posteriorly, optionally lateral section data representing a lateral section that radially delimits the tissue volume circumferentially with respect to the main optical axis and that extends at least to the cap section and at least to the lenticule section, and access section data representing at least one access section. The present invention further relates to a computer program product, a data signal, a computer-readable non-volatile storage medium, and a therapeutic method for correcting the refraction of an eye.

[0004] For a long time, refractive errors in the human eye have been corrected by means of lenses in the form of glasses or contact lenses. However, for more than 20 years, there have been various approaches to correcting refractive errors by modifying the cornea. The modification changes the curvature of the cornea and thus corrects the refractive power of the eye. This is done either by removing a predetermined volume of a specific shape from the cornea or by removing tissue from the cornea. This changes the refractive power of the cornea in such a way that

[0005] - taking into account the overall imaging properties of the eye - the visual impairment is reduced or even completely compensated.

[0006] To create the flat incisions in the cornea, pulsed laser radiation is used to treat the eye within the tissue - i.e. below the surface of the tissue

[0007] - focused in such a way that optical breakthroughs occur in the tissue. This effect, called photodisruption, is observed particularly with picosecond and femtosecond lasers, but also with nanosecond lasers (shorter pulses result in lower fluences [in mW / cm 2 ] in focus is necessary to create optical breakthroughs). Optical breakthroughs are also achieved in media that are transparent to the laser radiation. Typical (central) wavelengths of picosecond and femtosecond lasers can be around 800 nm, around 1030-1060 nm, around 1300 nm, around 1500 nm or around 1900-2000 nm. Furthermore, the corresponding wavelength ranges at half, third, quarter, etc. wavelength are accessible through frequency multiplication using nonlinear effects. For example, with an Nd:YAG laser at 1064 nm, pulsed laser light with a central wavelength of 532 nm can be achieved by frequency doubling, 355 nm by frequency tripling, and 266 nm by frequency quadrupling.

[0008] In the tissue, various processes initiated by the laser radiation take place sequentially. Multiphoton absorption generates a plasma, which expands through the absorption of further photons in an avalanche effect. If the power density of the radiation exceeds a threshold, an optical breakthrough occurs, which creates a plasma bubble in the material. This plasma bubble grows after the optical breakthrough occurs due to expanding gases. If the optical breakthrough is not maintained, the gas generated in the plasma bubble is absorbed by the surrounding material, and the bubble disappears again. However, this process takes much longer than the formation of the bubble itself. For the sake of simplicity, the processes mentioned are summarized here under the term optical breakthrough, i.e.This term encompasses not only the actual optical breakthrough, but also the resulting effects in the material. If a large number of optical breakthroughs are created next to each other in the fabric, a flat cut (cut surface) can be created.

[0009] Laser-assisted refractive treatments have two major disadvantages: a) Damage to or severance of nerve fibers in the cornea and the associated, frequently occurring symptoms of dry eyes. b) The weakening of the stroma due to tissue removal or ablation and the treatment-specific incisions in the cornea, which can lead to ectasia or keratoconus.

[0010] Depending on the type of treatment, both points can be expressed to varying degrees.

[0011] When cutting a corneal flap with a specific thickness (typically 100 μm), the flap incision consists of a circular area with a lateral cut to the surface, which remains connected to the cornea only over a small arc (hinge, typically 3 mm). This severes nerve fibers along the entire circumferential lateral cut (a) and effectively weakens the tissue toward the surface in most of the flap (b).

[0012] An incision surface that defines a lenticule in the cornea of ​​an eye (typically at a depth of 120 pm) typically has a cap incision (typically 8 mm diameter), a lenticule incision (typically 6 mm diameter), optionally a lateral incision, and an access incision (typically 2 mm). The cap incision is usually larger in diameter than the lenticule incision to ensure orientation for access to both incision planes and easier separation, but here the access incision is only made over the small arc area of ​​the incision. This means fewer nerve fibers are severed (a) A remaining disadvantage of SMILE is the (slightly) weakened corneal tissue around the lenticule due to the larger cap incision. The cap incision is therefore comparable to a flap.The cap cut (also called cap or flap cut) limits the lenticule - the volume of tissue to be isolated from the cornea for removal - anteriorly, towards the front of the cornea. The lenticule cut limits the lenticule posteriorly - towards the retina of the eye. The lenticule cut can, for example, be created in a partial incision with a decreasing path radius (i.e. from the outside in) or with a increasing path radius (i.e. from the inside out). The optional side cut (also called side cut or lenticule side cut) limits the lenticule laterally opposite one of the main optical axis of the eye and extends to both the cap cut and the lenticule cut. The access incision extends to both the cap cut and the front of the cornea.The access incision allows the isolated tissue volume to be removed from the cornea.

[0013] It is also possible for the cap cut to extend into the lenticule cut, or for the lenticule cut to extend into the cap cut. It is therefore conceivable that the lenticule has no edge cut, or alternatively, a transition zone is formed at the edge of the lenticule instead of a side cut.

[0014] Furthermore, the access incision serves as an access point for separating the lenticule, which is usually still connected to the surrounding corneal tissue by bridges of material, from the areas of the cornea anterior to the lenticule and from the remaining area of ​​corneal tissue posterior to the lenticule. This can be achieved, for example, using a spatula-shaped tool curved similar to the curve of an eye, which is inserted through the access incision and used to remove the bridges of material. Corneal nerves are damaged during all ophthalmic procedures.

[0015] The object of the present invention is therefore to provide devices and methods which make it possible to damage as few corneal nerves as possible during operations on the human eye.

[0016] According to the invention, the object is achieved by the features of the independent claims. Preferred developments and refinements are the subject of the dependent claims.

[0017] The cap section data, which are part of the cutting surface data calculated by the data processing device of the planning unit according to the invention, comprise cover surface section data representing a cover surface section with a cover surface radius, edge zone section data representing at least one edge zone section that borders the cover surface section in a predetermined azimuth angle range and has an edge zone radius that is greater than the cover surface radius, and edge zone segment section data representing at least one edge zone segment section for each edge zone section. The at least one edge zone segment section is arranged in a further azimuth angle range bordering the azimuth angle range of the edge zone section and, at an azimuth angle present both in the azimuth angle range and in the further azimuth angle range, merges into the edge zone section or borders it.

[0018] Furthermore, the data processing device is designed to provide control data representing the cutting surface, wherein the planning unit further comprises at least one input and / or output interface for receiving the data representing the refraction correction requirement and for providing the control data generated by the data processing device.

[0019] The invention also relates to an aforementioned ophthalmic laser therapy device, comprising a previously or subsequently described embodiment of the planning unit, a laser device for providing therapeutic radiation, a focusing device for focusing the therapeutic radiation in a focus for severing the cornea, a scanning device for shifting the focus of the therapeutic radiation within the tissue of the cornea of ​​the eye to create the cutting surface, and a control unit connected to the planning unit via the at least one input and / or output interface for receiving the control data, wherein the control unit is further connected to control the laser device and / or to control the focusing device and / or to control the scanning device. The planning method according to the invention for generating control data is carried out in particular before and independently of an eye operation to be performed.During this planning phase, no patient treatment or therapy is yet taking place. The control data represents where and / or in what order and / or with what parameters a laser pulse should be applied to the patient's eye in order to correct the patient's refraction through corneal modification.

[0020] The planning method according to the invention for generating control data for correcting the refraction of a cornea of ​​an eye having a main optical axis by corneal modification within the tissue by means of an ophthalmological laser therapy device comprises the steps of receiving a

[0021] Correction data representing the need for refraction correction, calculating a tissue volume of the cornea to be removed, wherein the calculation is carried out on the basis of the need for refraction correction, calculating cutting surface data which represent at least one cutting surface completely surrounding the tissue volume, wherein the cutting surface data comprise cap cutting data, lenticule cutting data, optionally side cutting data, and access cutting data.

[0022] Here, the cap cut data represent a cap cut that limits the tissue volume anteriorly, the lenticule cut data represent a lenticule cut with a lenticule radius, wherein the lenticule cut limits the tissue volume posteriorly, the optional side cut data represent an optional side cut that limits the tissue volume radially all the way around the main optical axis and that extends at least to the cap cut and at least to the lenticule cut, and the access cut data represent at least one access cut to the cap cut and to the lenticule cut.

[0023] The cap cutting data also includes:

[0024] Cover surface section data, which represent a cover surface section with a cover surface radius,

[0025] Edge zone section data representing at least one edge zone section which adjoins the cover surface section in a predetermined azimuth angle range and has an edge zone radius which is greater than the cover surface radius, and

[0026] Edge zone segment section data which represent at least one edge zone segment section for each edge zone section, wherein the at least one edge zone segment section is arranged in a further azimuth angle range adjacent to the azimuth angle range of the edge zone section and merges into the edge zone section or adjoins it at an azimuth angle present both in the azimuth angle range and in the further azimuth angle range.

[0027] Ultimately, the planning process generates control data representing the cutting surface.

[0028] In the following description, the optional enhancements to the control data are based on the patient's eye or cornea. This is to be understood as the theoretical location of the planned but not yet performed incisions in the patient's eye.

[0029] The need for refractive correction can be determined through previous measurements of the patient's eye and represented by correction data. This correction data is used to calculate the volume of corneal tissue to be removed using the planning procedure. Various objective and subjective measurements are known to determine the need for refractive correction, and these can be combined. Measurements of the structure of the eye, for example, via an OCT measurement, as well as measurements of intraocular pressure and the topography of the eye, can also be incorporated into the refractive correction requirement.

[0030] The tissue volume is delimited or defined by cutting surfaces. These cutting surfaces are represented by the calculated cutting surface data.

[0031] As previously described, the tissue volume (i.e., the lenticule) is composed of different cutting surfaces. Each of these cutting surfaces is represented by corresponding cutting surface data, for example, the cap cutting data, which represents a cap cutting that delimits the tissue volume anteriorly; the lenticule cutting data, which represents a lenticule cutting that delimits the tissue volume posteriorly; the optional lateral cutting data, which represents an optional lateral cutting that delimits the tissue volume radially at least in sections with respect to the main optical axis and that extends in sections at least to the cap cutting and at least to the lenticule cutting; and the access cutting data, which represents at least one access cutting.

[0032] The cap incision is thus adapted and its area reduced compared to a conventional SMILE operation in order to minimize damage to the nerve fibers and weakening of the corneal tissue. For this purpose, the previously circular cap incision with a diameter that can, for example, correspond to twice the marginal zone radius) is divided into several partial incision areas significantly larger than the underlying lenticule incision. Furthermore, the area of ​​the cap incision that extends beyond the lenticule incision can be referred to as the clearance. The cap incision can extend beyond the lenticule incision by a clearance distance. According to the invention, areas of the clearance can be masked in the control data, whereby masking is understood to mean "no cutting" or is implemented when the control data is exported. In this way, incision areas can be omitted.

[0033] It is advantageous if the cover surface cut is arranged along the main optical axis essentially concentrically above the lenticule cut.

[0034] Such an adapted geometry of the cap incision minimizes the area of ​​the cap incision without sacrificing the advantage of easier orientation / separability provided by an existing transition zone of the marginal zone incision. The cap incision is aligned to the position of the access incision by the marginal zone incision.

[0035] Due to the reduced surface area, fewer nerves are severed and the biomechanical stability of the cornea after treatment is improved due to a comparatively smaller weakening of the tissue (the biomechanical stability is less reduced by the procedure).

[0036] It is also advantageous if the edge zone cut extends in the form of a circular segment in the direction of the access cut, wherein the edge zone cut can have an edge zone radius which is substantially 0.5 to 1.3 mm larger than the lenticule radius, preferably substantially 0.6 to 1.2 mm larger than the lenticule radius, further preferably substantially 0.7 to 1.1 mm larger than the lenticule radius and even more preferably substantially 0.9 mm larger than the lenticule radius.

[0037] For each access incision (there is at least one), there is a circular ring segment adjacent to the top surface incision in the direction of the access incision with a specific radial length D (also parameter D), which corresponds to the difference between the marginal zone radius and the lenticule radius. This radial length D can, in particular, correspond to a clearance length of a known SMILE operation. However, according to the invention, such a marginal zone incision or such a clearance region with radial length D is only provided within the azimuth angle range.

[0038] Furthermore, it is advantageous if the access incision and the marginal zone incision have different inclination angles relative to the main optical axis in the radial direction. The access incision represents a cut surface or a surface incision that extends from the marginal zone incision to the anterior surface of the cornea or that is applied to the anterior surface of the cornea. Furthermore, the marginal zone incision can be essentially continuous with the top surface incision or can merge continuously into it.

[0039] Preferably, the cover surface radius is greater than the lenticule radius by a clearance distance, wherein the clearance distance is <0.5 mm, preferably <0.4 mm, more preferably <0.3 mm, even more preferably <0.2 mm, and even more preferably less than or equal to 0.1 mm. The clearance distance can also be referred to as parameter A.

[0040] The cover surface radius can be larger than the lenticule radius by the clearance distance, particularly in an angular range outside the azimuth angle range of the edge zone cut. This angular range can thus essentially be (360° - azimuth angle range). In the azimuth angle range, the cover surface radius can be larger than the lenticule radius by the parameter D due to the edge zone cut.

[0041] The clearance can be understood in particular as a safety feature, since it ensures an overlap or abutment of the lenticule surfaces perforated by the laser even in the case of a slight offset between the lenticule cut and the cap cut, and thus separation is always possible along the surfaces processed by the laser, even in the case of such an offset.

[0042] The data processing device of the planning unit can further be configured to automatically calculate an aperture angle of the edge zone section represented by the edge zone section data. The aperture angle can be understood as the angle between a radial direction and a boundary of the edge zone section. Since the edge zone section transitions into the edge zone segment section at the azimuth angle, the aperture angle can be understood as the angle between the radial direction and the azimuth angle. Such an aperture angle can preferably be provided symmetrically to the radial direction, mirrored at the two azimuthal boundaries or the azimuthally delimiting linear regions of the edge zone section.

[0043] Such an opening angle, or the two opening angles, can ensure that with the selected geometry, every point of the lenticule can be reached with a tool and a separation of the perforated tissue of the lenticule (i.e. the cutting of the material bridges) can be carried out.

[0044] In a corresponding embodiment of the planning method, the calculation of the cutting surface data may include a calculation of the opening angle.

[0045] The calculation of the opening angle may depend, in particular, on the distance of the incision (i.e., the access cut) to the lenticule edge (i.e., the difference between the marginal zone radius and the cap surface radius), as well as on the width of the incision (the width of the incision is understood as the azimuthal length of the access cut). A shorter incision with a large distance to the lenticule may therefore require a larger opening angle.

[0046] The minimum possible opening angle can be calculated in such a way that any position of the lenticule can be reached from the incision using a tool for severing remaining material bridges. This can be represented geometrically, for example, by a tangent drawn to the circle of the lenticule (or lenticule radius + effective clearance) and passing through the opposite point or area of ​​the incision.

[0047] For example, if the access incision is located on the right side of the eye and runs essentially from top to bottom, this means that a line is calculated from the lower end of the access incision, tangentially upwards to the cap incision (made with the cap surface radius). The point of contact with the cap incision then represents one endpoint of the edge of the access tunnel, and the uppermost point of the access incision represents the second endpoint of this edge of the access tunnel. Accordingly, a downward tangent is drawn from the uppermost point of the access incision to the cap incision (for clarification, see Fig. 12).

[0048] The arc length of the access incision at the lenticule is obtained from the product of a radius (the radius along which the arc length runs) and an angle that spans the arc length, the arc angle of the access incision at the lenticule. Along this arc length, the access tunnel merges into the cap incision. A minimum arc length (which ensures that every point in the lenticule can be reached by the access incision) is thus determined by a minimum angle (i.e., a minimum arc angle of the access incision at the lenticule: a L (min)). This minimum angle can be calculated from the angle spanned by the incision (also: arc angle of the incision cut; aQ) and the radii (cover surface radius r D = lenticule radius + clearance distance; marginal zone radius r R ) using the formula: be calculated.

[0049] This minimum opening angle can be manually increased if necessary. Finally, two plausibility checks can be performed:

[0050] (1) For an opening angle < 0°, this can be set to 0° (= parallel tunnel sides of the access incision), since a decreasing tunnel is not practical. (2) If, in a case, the opening angle is chosen so large that the connecting lines defining the tunnel no longer intersect the lenticule circle (defined by the cover surface radius), it is limited to the maximum value (corresponding to the tangent to the lenticule circle on the same side of the incision edge:

[0051] In this case, a maximum arc angle of the access cut at the lenticule aL(min)) is calculated from the arc angle of the incision cut (ai) and the radii (r D , r R ) as follows:

[0052] The arc length of the access tunnel at the lenticule is then determined - as described above - by multiplying the obtained arc angle with the corresponding radius.

[0053] In an advantageous embodiment, the access incision and the at least one marginal zone incision can have substantially the same azimuth angle range, whereby the access incision can extend from the anterior surface of the cornea to the marginal zone incision, and the marginal zone incision can extend to the top surface incision. One access incision can be provided for each marginal zone incision.

[0054] The additional azimuth angle range of the at least one edge zone segment cut can be referred to as parameter C and increases the azimuth angle range of the edge zone cut. The resulting higher angle range can provide greater freedom of movement when separating the cutting planes using the typically performed wiping motion.

[0055] A marginal zone segment incision preferably borders on or merges into the marginal zone incision at an azimuth angle. The marginal zone segment incision thus enlarges the marginal zone incision, but not the access incision. In other words, an access opening is smaller (i.e., an incision is shorter) than a subsequent access tunnel, allowing for increased mobility within the access tunnel.

[0056] A further effect or advantage of the clearance may be that it makes it possible to shift wrinkles that may arise due to a mismatch of the arc lengths of the cap and lenticule surfaces to an area outside the optical zone.

[0057] Such wrinkles can induce unwanted aberrations, which, although gradually compensated for by epithelial growth, can still delay visual recovery. Smoothing the wrinkles out to an area outside the optical zone can contribute to improved visual acuity by reducing aberrations.

[0058] Therefore, the data processing device of the planning unit can optionally be configured to calculate the clearance distance (parameter A) based on user input or semi-automatically or automatically. In particular, the calculation or determination by the user can be performed depending on the refractive correction to be achieved.

[0059] For example, it is conceivable that for smaller corrections—i.e., refractive corrections that, for example, and not exclusively, are in the range of one diopter (approximately < 1 dpt) and below, and where only thin lenticules are cut and removed—smaller values ​​for the clearance distance may be selected or calculated. Conversely, for larger corrections and correspondingly thicker lenticules, a larger value for the clearance distance may be calculated or specified. Such mismatches in the arc lengths of the cap and lenticule surfaces can also occur with asymmetric lenticules. The clearance distance can thus be proportional to the change in refraction.

[0060] The mismatch of the arc lengths of the cap and lenticule surfaces can be decisive here.

[0061] Among other things, the clearance also has the important function of allowing the physician to differentiate between the incision and the lenticule incision during separation in the top view / projection. If the clearance were omitted, i.e., if a clearance distance of 0 were set, identifying whether a tool is located in the lenticule incision or the cap incision would be significantly more difficult, especially outside the access incision.

[0062] However, an effective clearance > 0 also has the advantage that the optional lateral cut can be completely separated with greater reliability. If the tool for cutting the material bridges is located posteriorly, i.e., on the side of the lenticule facing away from the ocular surface, i.e., "down" in the lenticule cut, this tool can be moved along the edge of the lenticule at the lateral cut, leaving some leeway to push the tool tip further upward and then into the effective clearance. This ensures that the (lenticule) lateral cut has been properly / completely separated.

[0063] In a myopic case (correction of myopia by removal of a lenticule with positive refractive power), the clearance distance can be calculated as follows:

[0064] ^-clearance ^min d” f * Pd.pt

[0065] The mina minimum effective clearance (e.g. a clearance distance of 100 pm for myopic lenticules, 50 pm for hyperopic lenticules), fine multiplication factor (can be different for each treatment type but can be pre-determined or determined) and P dp t the refractive power of the lenticule on the strongest axis. For myopic lenticules, this can correspond to the most myopic meridian, and for hyperopic lenticules, the most hyperopic meridian.

[0066] For such a myopic lenticule, a relatively small transition zone can be selected, for example, 0.1 mm, without limitation. In this case, it is advantageous to select a larger effective clearance or a larger clearance distance. This allows for more space to smooth out wrinkles. In hyperopic lenticules, on the other hand, the transition zone is rather large, for example, approximately 2.0 mm, without limitation. In such a case, there is already enough space outside the optical zone to smooth out wrinkles, and the effective clearance / clearance distance can be selected smaller than in the previously described case of the myopic lenticule.

[0067] The improvement in the incision geometry thus particularly affects the cap incision. The lenticule incision remains essentially unchanged, whereas the cap incision has a second clearance distance (also: parameter A) of the clearance area, which is significantly reduced. Only in the azimuth angle range (also: parameter B) of the access incision is the original clearance distance (also: parameter D) retained. Access via the access incision to the cap incision is thus unchanged, whereas in a recessed angular range of 360° minus the azimuth angle range, a significantly smaller area must be incised.

[0068] In this case, it may be advantageous if two edge zone segment cuts are provided symmetrically for increasing and decreasing azimuth angles, ie both in and against an azimuthal direction at the edge zone cut.

[0069] This means that a marginal zone segment cut is provided on both sides of at least one marginal zone cut. This increases the doctor's freedom of movement when separating the planes in both directions.

[0070] A marginal zone segment incision can be essentially triangular, essentially rectangular, or essentially triangular with a curved triangular side. This facilitates access with the tool to any point of the lenticule marginal incision. A curved triangular side, in particular, can contribute to increased stability of the incision, as it is less susceptible to stretching and the cornea is less likely to be overstretched at this location. Tensions in the tissue during stretching or compression are thus better distributed into the surrounding tissue.

[0071] In some embodiments of the at least one edge zone segment cut, the original clearance distance (parameter D) can be retained. This can be the case, in particular, with substantially rectangular edge zone segment cuts. Furthermore, the clearance distance prevailing in the at least one edge zone segment cut can vary depending on the azimuth angle between the original clearance distance (parameter D) and the second clearance distance (parameter A). In particular, the clearance distance prevailing in the at least one edge zone segment cut can change continuously depending on the azimuth angle. An edge cut delimiting the at least one edge zone segment cut can thus particularly preferably be continuously curved and / or transition continuously into the remaining clearance outside the azimuth angle range and outside the further azimuth angle range.Such a continuous transition can reduce the risk of unwanted and uncontrolled tearing of corneal tissue, since tensions in the tissue can be better distributed by a curved incision or a curved cutting edge that limits a marginal zone segment incision.

[0072] The data processing device of the planning unit can further be configured to calculate the marginal zone cutting data such that, viewed from the incision to the top surface, these cutting edges each converge on an opposite cutting edge and represent cutting edges spaced at a minimum (azimuthal) distance at a radius between the marginal zone radius and the top surface radius. This configuration thus results in an access tunnel that is not trapezoidal but has a waist. This waist can be located between the access incision, i.e., the access for an instrument for severing the material bridges from outside the eye, and the transition between the access tunnel and the lenticule, i.e., the transition from the access tunnel to the cap incision or the lenticule incision.

[0073] Such a design can reduce the total area of ​​cut tissue without compromising the ability to reach every point of the lenticule, particularly in the cap cut and the lenticule cut, with the tool for severing the material bridges. The pivot point of such a tool can be located at the waist of the access tunnel.

[0074] A minimum width of the waist can depend in particular on the dimensions of the selected tool. Furthermore, the shape of the waist, such as a selected curvature of the waist, can also depend on the selected tool. Furthermore, it is conceivable that the curvature(s) of the waist are not symmetrical in the radial direction and, for example, a smaller curvature of the sides of the access tunnel is selected as viewed from the access incision, whereas a stronger curvature is selected towards the lenticule. The smaller curvature of the sides of the access tunnel can reduce the risk of mechanical tearing by the tool. The waist can thus be arranged (in the radial direction) closer to the lenticule than to the access incision.

[0075] The device for data processing of the planning unit can thus be designed to calculate the access intersection data in such a way that the aforementioned at least one edge zone segment intersection, as well as further configurations of the edge zone segment intersection(s), are represented by the access intersection data.

[0076] It is further advantageous if the two edge zone segment cuts have boundary cutting lines arranged parallel to each other.

[0077] In a further embodiment, the azimuth angle range of the marginal zone incision can be between 20° and 40°, preferably between 25° and 35°, more preferably essentially approximately 30°. Depending on the surgeon's experience or the expected difficulty of lenticule extraction, the width of the access to the lenticule can thus be adjusted.

[0078] Furthermore, it is advantageous if a central azimuth angle of the azimuth angle range between 0° and 360° can be set.

[0079] The position of the access incision must also be adjusted accordingly. For example, the position of the access for plane separation and / or lenticule extraction can be adjusted based on operating room conditions, the surgeon's handedness (left-handed, right-handed), or the surgeon's preference. Optionally, the cap section data can include two marginal zone sections with correspondingly identical or different marginal zone element sections. If, for example, separation or extraction through the first marginal zone section leads to complications, this can be performed through the second marginal zone section.

[0080] The planning unit and the planning process can be further improved by increasing the azimuth angle range to between 1.5° and 15°, preferably between 0.75° and 7.5°. This wider angle range also allows for greater freedom of movement when separating the section planes using the typically performed swiping motion.

[0081] In a further embodiment of the planning method, this can further comprise method steps of a computer-implemented method for optimizing control data, wherein the computer-implemented method comprises: reading in or calculating start control data representing at least one cutting surface and its three-dimensional position and orientation in the cornea of ​​the eye; reading in nerve data representing a three-dimensional arrangement and a three-dimensional course and thickness of nerves in the cornea of ​​an eye; generating a weighting value from the start control data and from the nerve data by applying a penalty and / or merit function to the number and / or type and / or section length of the nerves represented by the nerve data that overlap with the at least one cutting surface, wherein the weighting value represents a degree of severity of the overlap; and providing the weighting value.

[0082] The weighting value can be understood as a factor for the severity of the overlap between the structure to be created in the cornea (cut surface) and the corneal nerves. It is conceivable that the weighting value will be further processed and / or prepared and / or, in particular, transmitted to a user, thus enabling an assessment of the severity of nerve damage to the corneal nerves during the planned procedure.

[0083] The weighting value can be provided optically, e.g., via a display device, or acoustically. One possible solution is a light source that changes the displayed color depending on a comparison of the determined weighting value with a predetermined ideal weighting value. A specific display of the weighting value, possibly coupled with color coding as described above, on a display device is also conceivable. Thus, the provided weighting value can be used to estimate how invasive—i.e., how damaging—the planned procedure will be for the corneal nerves right from the planning stage.

[0084] In a further embodiment, the planning unit therefore allows at least one start parameter stored in the start control data to be modified by means of at least one user input. Following a modification, a recalculated weighting value can be displayed. The user input can be made using a keyboard, mouse, touchscreen, voice input or otherwise. Furthermore, a modification of several parameters is conceivable. Furthermore, in such a modification, parameters can be linked to one another so that an increase in a first parameter causes a reduction in a second parameter. The provision of the weighting value allows a user to reduce the severity of the overlap, i.e. the invasiveness of the procedure, and to protect the corneal nerves of the eye to be treated by modifying at least one parameter during the planning stage.Thus, the likelihood of complications is reduced and patient satisfaction is increased. The data processing device of the aforementioned embodiments can also be configured to provide the start control data as control data without changing any parameters. Likewise, the data processing device can provide control data based on the start control data and the parameters set by the user.

[0085] In a further embodiment of the computer-implemented method, the weighting value is optimized in a further method step by repeatedly generating it from the neural data and from follow-up control data, which are generated in a first iteration starting from the start control data and in subsequent iterations starting from previously generated follow-up control data by modifying at least one start parameter stored in the start control data. Furthermore, the follow-up control data that results in the optimized weighting value are provided as optimized control data.

[0086] A previously described manual or semi-automatic or automatic optimization of the control data by modifying the at least one start parameter can be carried out following a modification of at least one parameter by means of user input.

[0087] Even with automatic optimization of the control data, the decision as to whether the procedure is performed using the optimized control data obtained remains with the physician. The method and the devices presented are designed to enable verification of the optimized control data, for example by visualizing the changed parameter sets and / or purely by way of example by comparing the position of the incisions to be performed with the start control data and the optimized control data. With this visualization, a property of the visualization can also be dependent on the determined weighting value or depending on a standardized weighting value. Purely by way of example and not by way of limitation, elements inside or outside the visualized position of the incisions can be color-coded or highlighted using a type of traffic light system.

[0088] In this optimized planning method, the start control data can comprise at least one predetermined parameter set of start parameters, a position of the access cut and / or a cover surface radius and / or an edge zone radius and / or an azimuth angle range and / or a further azimuth angle range and / or a clearance distance.

[0089] For example, a physician can vary the azimuthal position of the marginal zone incision and / or the position and / or shape and / or number of marginal zone segment incisions, for example, within a quadrant favorable for the procedure, and specify / set an azimuth angle in the planning phase that has a lower weighting value. It is also conceivable that a range of values ​​(e.g., the quadrant mentioned above) can be specified as the limits of the azimuth angle to be set, and (automatic) optimization should only occur within this quadrant.

[0090] Furthermore, it is conceivable that a lenticule depth and / or a lenticule height and / or a position of the access cut and / or a course of the cap cut and / or a course of the lenticule cut and / or a course of the edge cut and / or a course of a transition zone and / or a lenticule radius and / or a cover surface radius are also manually or semi-automatically or fully automatically variable as parameters.

[0091] It is possible that each start parameter can only be modified within a parameter interval specific to each parameter stored in the start control data.

[0092] Furthermore, it is advantageous if at least one start parameter can be set invariably as a fixed value.

[0093] A further improvement of the planning procedure is achieved when the nerve data represents a measurement from a high-resolution OCT and / or a measurement from a confocal microscope.

[0094] In particular, the measurement represented by the nerve data may have a resolution of 5 m or less.

[0095] The nerve data can represent the nerves of the eye for which the control data for the intervention is being generated. It is also conceivable that general nerve data, e.g., from measurements on patients and / or test subjects, could be used. This nerve data then does not exactly represent the nerves of the eye to be treated, for which the control data is to be generated, but can serve as an aid in determining how damaging the planned intervention will be to the nerves. Furthermore, it is also possible that the nerve data merely comprise model data, which may be simulated and not based on a real measurement on an eye.

[0096] Furthermore, it is advantageous if, when generating the weighting value, a branching index of individual nerves represented by the nerve data is taken into account, wherein the branching index represents at least a number of branches after the cutting of nerves; and / or thickness information of individual nerves represented by the nerve data is taken into account, wherein the thickness information represents at least a thickness of the nerves; and / or residual length information is taken into account, wherein the residual length information represents at least a total length of the cut nerves represented by the nerve data.

[0097] The planning unit according to the invention but also the ophthalmological laser therapy device according to the invention can be designed to carry out an embodiment of the planning method which comprises method steps of the computer-implemented method described above.

[0098] The invention further relates to a computer program product comprising instructions which, when loaded into a data processing device, enable the device to carry out an embodiment of the planning method described above.

[0099] The invention further relates to a data signal which transmits the aforementioned computer program product.

[0100] Furthermore, the invention relates to a computer-readable non-volatile storage medium comprising the computer program product described above.

[0101] Finally, the invention relates to a method for correcting the refraction of an eye by corneal modification within the tissue, comprising

[0102] Implementation of the planning procedure described above;

[0103] Cutting the cornea of ​​the eye according to the provided control data;

[0104] Release of the tissue volume along the cap incision through the access incision;

[0105] Release of the tissue volume along the lenticule incision through the access incision;

[0106] Detaching the tissue volume along the lateral incision; and removing the tissue volume from the cornea of ​​the eye through the access incision.

[0107] Below, some computational examples and advantages of the invention are presented. These are purely exemplary and not limiting.

[0108] The cap cut is adapted to the position of the incision, thus minimizing the effective area. Typically, the optical zone (OZ) has a diameter of approximately 6 mm, which, with a transition zone of 0.1 mm, results in a lenticule diameter of 6.2 mm. This corresponds to a projected area of ​​30.2 mm. 2A cap incision typically has a diameter of 8 mm with an access incision that has an azimuth angle range of 29° (or 2 mm). The clearance (clearance distance) is therefore 0.9 mm and the projected cap area is 50.3 mm. 2 . The cap cut is therefore approximately 20.1 mm 2 larger than the lenticule cut (approx. 66%).

[0109] In the adjusted cutting geometry, the cap cut is extended by only 0.1 mm radially beyond the lenticule diameter (parameter A or clearance distance). Additionally, a circular ring segment (the marginal zone cut) with a radial length D of 0.8 mm is created (to effectively place the access cut back to a diameter of 8 mm). The angular range of the marginal zone cut corresponds to the access cut (parameter B; 29° or 2 mm) extended (by one or two marginal zone segment cuts) by 1.5° (or 0.1 mm) angular extension each (parameter C). The area of ​​the ring segment is thus approximately 1.6 mm.2 and the total cap area 33.8 mm 2 This corresponds to a space saving of 16.5 mm 2 or 33% compared to the total area of ​​the cap in a regular SMILE. Considering only the area that extends beyond the lenticule area of ​​30.2 mm 2 the savings are even 82%.

[0110] With the same access incision length (2 mm) and an (effective) cap diameter of 7.5 mm, the savings decrease to approximately 25% (78% outside the lenticule area). With an (effective) cap diameter of 8.5 mm, the savings increase to approximately 40% (85% outside the lenticule area).

[0111] In one embodiment, the data processing device of the planning unit can be configured to automatically suggest or calculate the optical zone. This can, in particular, be dependent on a pupil diameter, whereby the refractive correction should extend over the entire area covered by the patient with dilated pupils. Based on a predetermined clearance or a predetermined clearance distance and / or a cover surface diameter, it is thus possible to determine which contact lens sizes are suitable for treatment.

[0112] Thus, it is conceivable to propose a contact lens size for a given cover surface diameter or cover surface radius and / or edge zone radius. It is also conceivable to determine or propose a clearance or clearance distance and / or a cover surface radius and / or an edge zone radius for a given contact lens and its size and a predetermined optical zone.

[0113] In a corresponding embodiment of the method according to the invention, this can comprise at least one of the above-mentioned calculations. In a further embodiment of the planning unit, its data processing device can be configured to calculate or take into account a displacement of the center of a lenticule to be machined relative to the center of the contact lens.

[0114] This may be desirable, for example, if an originally planned geometry of a lenticule, ie all areas of the cornea to be treated, cannot be treated with a selected contact lens because this (geometry) is larger than a maximum possible treatment zone of the contact lens.

[0115] This shift can now be applied particularly advantageously in combination with a masked clearance. Without such masking (but possibly also with masking, e.g., if the marginal zone incision is scheduled / planned to extend beyond the maximum possible treatment zone of the contact lens), it may happen that an area to be treated (this area is defined, among other things, by the clearance and / or the marginal zone) is larger in one dimension than the maximum possible treatment zone of a contact lens. Consequently, such a treatment could not be performed with the given parameters.

[0116] If the clearance is now masked, the area to be treated (i.e., the area to be cut) is again smaller than the maximum possible treatment zone due to the masking. In this case, it may be advantageous to shift the maximum possible treatment area of ​​the contact lens relative to the lenticule to be removed. Since the masking prevents areas of the cornea from being cut, particularly those areas opposite the incision (the access cut), the entire cutting pattern can be shifted in the direction of the uncut areas. This means that the area to be treated can fit entirely within the maximum treatment zone of the contact lens, thus enabling treatment.Even a cutting geometry with masked clearance, whose edge zone extends beyond the maximum treatment zone of the contact lens, can be decentered in such a way that the geometry fits completely into the treatment zone and treatment with this contact lens is possible.

[0117] A corresponding embodiment of the method according to the invention can comprise a calculation of such a displacement based on the size and / or shape of the area to be processed and / or the treatment zone of the contact glass and optionally provide correspondingly modified control data.

[0118] A corresponding device can be designed to perform the above calculations and the resulting shift of the center of the lenticule to be cut relative to the contact lens. The function of the proposed adaptable geometry can be switched off in the ophthalmic therapy device in order to return to the regular SMILE. In this case, for example, the parameters relevant for an adapted cap cut are grayed out in the planning software and the cap cut is displayed as regular, circular and concentric to the lenticule. It is easy to switch between the adapted cap cut (“masked clearance”) and the regular cap cut on a planning screen. A display can show the area difference or the saved area between the adapted and regular cap cut (relative, e.g., in %, or absolute, e.g., in mm 2 ) represent.

[0119] The new cut design can be displayed as a sketch to facilitate adjustment of the parameters (A, B, C, D). In addition to selecting the cut geometry, additional relevant adjustment parameters can be displayed or irrelevant parameters can be grayed out, as described above.

[0120] Through additional diagnostics (e.g., confocal microscopy or OCT) and the associated knowledge of the location and course of the nerve fibers, the position and width of the ring segment and the access incision can be adjusted to minimize nerve damage as much as possible. This is described above in the context of the computer-implemented procedure.

[0121] If diagnostic data on the course of the nerve fibers or the position of other tissue regions to be protected are available, the planning unit or the ophthalmic therapy device can optionally automatically make and / or visualize a suggestion for a specific incision geometry with correspondingly preselected parameters in order to support the physician in planning with the least possible nerve damage.

[0122] Because the area of ​​the cap incision is limited to the width of the access incision (parameter C ~ 0), the tissue on both sides of the access incision remains uncut within the clearance zone. This contributes to increased stability. The cap incision can be stretched less, and the cornea at this position can be overstretched less.

[0123] In addition, the stability of the access incision itself is increased. By eliminating the cap incision (since the clearance distance is preferably only 0.1 mm) on either side of the access incision (parameter C ~ 0), the risk of tearing of the access incision is reduced.

[0124] By eliminating the need for cut tissue, the effective length of the access tunnel (parameter D) can be increased compared to regular SMILE. This facilitates plane identification during manual lenticule extraction, as the edge of the cap cut and the edge of the lenticule cut are clearly distinguishable. Furthermore, within a long and laterally limited access tunnel, the separating tool can be guided along the natural curvature of the cornea. The probability of initially penetrating the anterior cap cut plane at the edge of the lenticule cut as desired is increased, and the risk of inadvertently separating the lenticule cut plane is reduced.

[0125] By maintaining only a slight difference in the diameter of the cap cut and the lenticule (low clearance, parameter A), the stability of a cap area above (i.e., anterior to) the lenticule is increased and offset of the two curves is reduced. This can reduce the risk of wrinkle formation ("microfolds" or "Bowman wrinkles"), which can have a positive effect on the patient's visual recovery.

[0126] The aspects of the present invention will be explained in more detail below with reference to the accompanying drawings. The drawings show possible exemplary embodiments of the present invention purely by way of example, whereby the described features can be combined with one another or omitted as desired. Identical features or features with the same function are also identified by the same reference numerals. Repetitive descriptions of features are omitted, so that explanations of features described in previous drawings can also be applied to other drawings, unless differences are explicitly pointed out.

[0127] They show:

[0128] Fig. 1 is a schematic representation of the ophthalmic laser therapy device;

[0129] Fig. 2 and 3 schematic representations of the effect of cuts on nerve fibers;

[0130] Fig. 4 is a schematic representation of a known cutting geometry in a SMILE operation;

[0131] Fig. 5 is a schematic representation of an improved cutting geometry;

[0132] Fig. 6-9 schematic representations of improved cutting geometry with different edge zone segment cuts;

[0133] Fig. 10 is a schematic representation of an ophthalmic laser therapy device;

[0134] Fig. 11 Schematic representations of further possible improved cutting geometries; Fig. 12 schematic representation for determining the opening angle; and

[0135] Fig. 13 schematic representation of a pattern shift.

[0136] Fig. 1 schematically shows an ophthalmic laser therapy device 1 and a focusing device 3 of the ophthalmic laser therapy device 1. The ophthalmic laser therapy device 1 generates therapy radiation 5, which is generated by a laser device (not shown) (see Fig. 11). The therapy radiation 5 is focused by the focusing device 3 into a focus 7, where photodisruption 9 occurs. An eye 13 is schematically shown in a treatment area 11. The eye 13 has a cornea 15, which is shown here in a highly simplified manner. The cornea is bounded anteriorly by a surface 17 and posteriorly by a back surface 19.

[0137] Furthermore, a tissue volume 21 to be removed from the cornea 15 is shown schematically, which can also be referred to as a lenticule 23. The indicated tissue volume 21 has not yet been removed from the cornea 15, but rather exists as a tissue volume 21 represented by planning data. The following explanations of the tissue volume 21 and the sections or cutting surfaces that form it are shown merely to illustrate a schematic position on or in the eye. The indicated sections or the area bounding the indicated tissue volume 21 are represented by the control data 90 before the actual treatment of the eye 13.

[0138] The tissue volume 21 is defined by several cut surfaces 25 (only one is shown here). Furthermore, the eye 13 has a main optical axis 27.

[0139] Figures 2 and 3 schematically show the cornea 15 of an eye 13 for the case of cutting a flap 29 (Figure 2) and for a SMILE operation (Figure 3). Also shown are nerves 50, whereby in Figure 2 both nerves 50 shown are cut and thus damaged by both the cap incision 29 and the edge incision 33. In the case of a SMILE operation shown in Figure 3, only one nerve fiber 50 is cut and damaged. Figure 3 also shows that a clearance area 51 of a conventional SMILE operation cuts the second nerve fiber 50.

[0140] Figure 4 schematically shows a top view of the incisions to be made in the eye 13. It shows a cutting pattern familiar from the conventional SMILE procedure.

[0141] The cap cut 29 has a cap radius 53 (also called edge zone radius 53) that is significantly larger than a lenticule radius 55 of the lenticule cut 31. The difference between the two radii 53, 55 is referred to as the clearance distance 57. An access cut 35 extends over an azimuth angle range 59, whereby access to the cap cut 29 is possible via the access cut 35 via the clearance area 51.

[0142] Figure 5 shows the improvement in the cutting geometry according to the invention. It can be seen that the lenticule cut 31 remains unchanged, but the cap cut 29 has a second clearance distance 57a (also: parameter A) of the clearance area 51, which is significantly reduced. Only in the azimuth angle range 59 (also: parameter B) of the access cut 35 is the original clearance distance 57 (also: parameter D) retained. Access via the access cut 35 to the cap cut 29 is thus possible without change, whereas in a recessed angle range 61, a significantly smaller area must be cut.

[0143] With reference to Figure 3, the nerve fibers 50 cut in the clearance area 51 can thus be retained intact if necessary.

[0144] The lenticule radius 55 and the clearance distance A together result in a cover surface radius 63 which is smaller than an edge zone radius 65, which corresponds to the cap radius 53.

[0145] Furthermore, two hatched edge zone segment sections 67 are shown. The two edge zone segment sections 67 are identical in the example shown and extend into a first further azimuth angle range 69 and a second further azimuth angle range 71, respectively. The further azimuth angle ranges 69, 71 directly adjoin the azimuth angle range 59, but the access section 35 does not extend into them.

[0146] The azimuth angle range 59 has a first azimuth angle 69A in common with the first further azimuth angle range 69 and a second azimuth angle 71A in common with the second further azimuth angle range 71.

[0147] Figures 6 to 9 each schematically show different designs of the edge zone segment cuts 67. For the sake of clarity, only the most necessary reference symbols are shown.

[0148] In Figure 6, the edge zone segment cuts 67 are rectangular 73, in Figures 7 and 8 they are triangular 75, and in Figure 9 they are essentially triangular 75 with a curved side surface 77. The different geometries of the edge zone segment cuts 67 allow unhindered access to both the cap cut 29 and the lenticule cut 31, whereby access should generally allow a wiping movement to sever the remaining material bridges of the corresponding cuts. Figure 10 schematically shows an embodiment of an ophthalmological laser therapy device 1. During operation of the ophthalmological laser therapy device 1, a laser device 110 emits therapy light 5 in the form of a pulsed laser beam 115. The laser beam 115 is deflected laterally (in the x and y directions) by a scanning device 130 and axially (z direction) by another scanning device 135.In other embodiments, the laser beam 115 can first be adjusted in the z-direction by the further scanning device 135 and subsequently deflected laterally in the x- and y-directions by the scanning device 130.

[0149] A focusing device 3 focuses the pulsed laser beam 115 into a focus 7 in the cornea 15. In Fig. 6, the focus 7 is shown as an example for two positions in the cornea 15 for different settings of the lateral scanning device 130 and the axial scanning device 135. A potentially advantageous fixation of the eye by means of a patient interface relative to the ophthalmic laser therapy device 1 is not shown.

[0150] During operation, the laser device 110, the scanning devices 130, 135, and the focusing device 3 are controlled fully automatically via signal data transmitted from a control unit 140 to the respective devices 110, 113, 130, 135. This is indicated by arrows pointing from the control unit 140 to the devices 110, 113, 130, and 135, respectively. The control unit 140 ensures suitably synchronous operation of the laser device 110, the three-dimensional scanning devices 130, 135, and, if applicable, the focusing device 3. The signal data can be transmitted via signal data lines 80 or wirelessly. The signal data required during operation is determined in the control unit 140 based on the control data 90. The control unit 140 receives the control data 90 beforehand from the planning unit P as a control data set 92 via unspecified communication paths such as control lines 94 (in Fig.6 as a solid line between the planning unit P and the control unit 140). The control data 90 can also be transmitted using memory chips 96 (e.g., via USB or memory stick), magnetic storage devices 98 (e.g., floppy disks), wirelessly via radio (e.g., WLAN, UMTS, Bluetooth), or wired (e.g., USB, Firewire, RS232, CAN bus, Ethernet, etc.). As an alternative to direct communication, it is also possible to arrange the planning device P spatially separate from the control unit 140 and to provide a corresponding data transmission channel. The transmission preferably takes place before the operation of the ophthalmic laser therapy device 1, i.e., before control signals are transmitted to the laser device 110, the scanning devices 130, 135, and, if applicable, to the focusing device 3. The control data set 92 is transmitted to the control unit 140 of the ophthalmic laser therapy device 100 via an input and / or output interface S2 of the planning device P.

[0151] The control data 90 represents, on the one hand, the various cuts, such as the cap cut 29, the lenticule cut 31, the optional edge cut 33, as well as the first access cut 35, the second access cut 41, and (the side surface segment 71) or (in another embodiment, the first side surface segment 71 and the second side surface segment 73), as well as the modifications of the processing parameters P to be applied in these side surface segments. Preferably, operation of the ophthalmic laser therapy device 1 is blocked until a valid control data set 92 is present at the control unit 140. A valid control data set 92 can be a control data set 92 that is, in principle, suitable for use with the control unit 140 of the ophthalmic laser therapy device 1. In addition, validity can also be linked to the passing of further tests.For this purpose, it can be checked, for example, whether additional information stored in the control data record 92 about the ophthalmic laser therapy device 100, e.g., a device serial number 90a, or about the patient, e.g., a patient identification number 90b, matches other information that was, for example, read out on the ophthalmic laser therapy device 1 or entered separately as soon as the patient is in the correct position for operation of the ophthalmic laser therapy device 1.

[0152] The planning device P generates the control data 90 or the control data set 92, which is provided to the control unit 140 of the ophthalmic laser therapy device 1 for carrying out the surgical procedure. In the embodiment shown here, the refraction correction requirement R is input via an input device (not shown) and provided to the planning unit P via a first interface S1. In other embodiments, the refraction correction requirement R can also be input via the input and / or output interface S2. Furthermore, the start control data 200 and the nerve data 210 can also be input via these interfaces.

[0153] The input device can be part of the ophthalmological laser therapy device 1 or can be designed independently.

[0154] The planning unit P comprises a calculation device C. This is connected to the first interface S1 and receives the refraction correction requirement R of the eye and, if applicable, the initial control data 200 and the nerve data 210. Control data 90 for correcting the refraction of the eye 13 by means of corneal modification are then calculated in the calculation device C. Alternatively, subsequent control data 201 are calculated by optimization in the calculation device C, and those subsequent control data 201 are output as optimized control data 203, which yield the optimized weighting value W.

[0155] The control data 90 are transmitted to the control unit 140 via the input and / or output interface S2. Using the transmitted control data 90, the control unit 140 can generate signal data S1, S2, S3 and transmit them to the

[0156] Devices 110, 3, 130, 135 are transmitted so that a cutting surface can be created in the cornea 15 of the eye 13.

[0157] Optionally, the optimized control data 203 are transmitted to the control unit 140 via the input and / or output interface S2. Using the transmitted optimized control data 203, the control unit 140 can generate signal data S1, S2, S3 and transmit them to the devices 110, 113, 130, 135, so that a cut surface can be created in the cornea 15 of the eye 13 according to the optimized control data 203. With this cut surface, it may be possible for fewer nerves to be damaged than when using the control data 90 without optimization.

[0158] It should be noted again that the planning unit P can generate the control data 90 or the optimized control data 203 regardless of whether the eye 13 is connected to the ophthalmic laser therapy device 1 or not.

[0159] Further embodiments of advantageous cutting geometries are shown schematically in Fig. 11.

[0160] In Fig. 11, a plan view of the incisions to be made in the eye 13 is shown schematically, wherein the access incision 35 is shown, not restrictively, at a different position than in Figs. 4, 5 and 6 to 9.

[0161] In all three cases shown, A, B and C, the cap cut 29 has the second clearance distance 57a, but for cases A and C the respective azimuth angle ranges 59 differ significantly from each other.

[0162] The clearance area 51 (see also the explanations for Fig. 4 and Fig. 5) is greatly reduced, analogous to the previously shown cutting geometries without masking.

[0163] In Case A and Case C, marginal zone segment cuts 67 can be defined, wherein the marginal zone segment cuts 67 have different opening angles 79. The opening angles 79 are each measured between a radial line 81 and a side surface 78 of the respective marginal zone segment cut 67. How the respective opening angle 79 is calculated is shown schematically in Fig. 12. Case B in Fig. 11 shows an access tunnel 83 (this corresponds to an incision located behind the access incision 35 and allowing access from outside the eye 13 to the lenticule incision 31 or the cap incision 29) that is not trapezoidal in shape, but has a waist 83 defined by a waist radius 85. The waist radius 85 is shorter than a length of the access incision 35. The waist radius 85 is to be understood merely as a distance. This is not rotationally symmetrical.A pivot point 87 of a tool 89 is located in the waist 83, allowing all areas of the cap cut 29 to be reached with the tool 89. The tool 89 is shown purely schematically in two positions.

[0164] In this embodiment, the side surfaces 78 have the waist radius 85 as the minimum distance from each other.

[0165] Fig. 12 shows schematically how the minimum and maximum opening angles can be determined.

[0166] A minimum possible opening angle 79m is calculated based on the idea that with a tool 89, every point of the lenticule, i.e., every point in the lenticule cut 31 and also every point in the cap cut 29, can be reached from every point of the access cut 35. Geometrically, this means a tangent 91 to the circle of the lenticule (or lenticule radius 55 + second clearance distance 57a) passing through an opposite point 93 of the access cut 35. The side surfaces 78 are calculated or constructed by connecting a tangent intersection point 95 with the nearest opposite point 93 of the access cut 35. This is shown schematically for a side surface 78.

[0167] By means of a side surface 78 constructed in this way, the minimum opening angle 79m can be determined.

[0168] It is also possible to calculate a maximum opening angle of 80. This is done by drawing a tangent 91 not from the opposite point 93 of the access cut 35 to the lenticule, but from a nearest point 94.

[0169] This is shown purely as an example for a second tangent 91a in the left-hand illustration of Fig. 12. Viewed from the nearest point 94 of the access incision 35, the second tangent 91a is applied to the cap incision 29. Transferring this to the right-hand illustration of Fig. 12 results in a maximum opening angle 80, which is greater than the minimum opening angle 79m. Fig. 13 schematically shows a shift in the incision pattern for an operation to be performed on an eye.

[0170] In Case A, a standard smile operation is schematically illustrated. The clearance distance 57 is arranged at a constant angle of 360° around the lenticule cut 29 and is not masked. A maximum possible treatment zone 97 of a contact lens (not shown) is schematically illustrated with a dotted line and is smaller than the cap cut 31; this treatment is therefore not feasible (with the selected contact lens, since this determines the treatment zone 97). Even if masking of the clearance is applied while maintaining this geometry, the marginal zone cut protrudes beyond the maximum possible treatment zone 97.

[0171] In case B, shown on the right in Fig. 13, the same lenticule size and the same optical zone are assumed. However, the clearance is masked according to the invention. The planned cutting pattern can be decentered relative to the treatment zone 97 (which is also unchanged). An original treatment zone 97a is shown schematically, with which treatment would not have been possible. By decentering or providing a decentered treatment zone 97b, the planned cutting pattern fits into the maximum possible treatment zone of the contact lens. Treatment is now also possible with this contact lens.

[0172] At this point, it should be noted that in the case of a slight decentration of the patient's eye relative to the contact lens, it is possible to merely decenter the cutting pattern without adjusting the position of the patient's eye relative to the contact lens to this changed center. If an adjustment of the position of the patient's eye is nevertheless desired or necessary, in such a case, it is preferable not to move the contact lens relative to the eye 13, but rather to move the eye 13 relative to the contact lens. The type of movement is irrelevant for the decentration.

[0173] In case A, a center of the lenticule 99a and a center of the treatment zone 99b coincide. In case B, these are spatially separated due to decentration.

Claims

Patent claims 1. Planning unit for generating control data for correcting the refraction of a cornea of ​​an eye having a main optical axis by corneal modification within the tissue by means of an ophthalmological laser therapy device, wherein the planning unit comprises - a data processing device which is designed o to receive correction data representing a refractive correction requirement, o to calculate a corneal tissue volume to be removed, wherein the calculation is carried out on the basis of the refractive correction requirement, o to calculate cutting surface data which represent at least one cutting surface completely surrounding the tissue volume, wherein the cutting surface data comprise cap cutting data, lenticule cutting data, optionally side cutting data, and access cutting data, wherein the cap cutting data comprise: ■ Cover surface section data, which represents a cover surface section with a cover surface radius, ■ Edge zone cut data representing at least one edge zone cut that borders the cover surface cut in a predetermined azimuth angle range and has an edge zone radius that is larger than the cover surface radius, and ■ Edge zone segment cut data, which represent at least one edge zone segment cut for each edge zone cut, wherein the at least one edge zone segment cut is arranged in a further azimuth angle range adjacent to the azimuth angle range of the edge zone cut and merges into the edge zone cut or borders on it at an azimuth angle present both in the azimuth angle range and in the further azimuth angle range, and o provide control data representing the cut surface, wherein the planning unit further comprises at least one input and / or output interface for receiving the data representing the refraction correction requirement and for providing the control data generated by the data processing device.

2. Planning unit according to claim 1, wherein the device for data processing is designed to calculate the access cut data in such a way that two edge zone segment cuts are provided symmetrically for increasing and for decreasing azimuth angles, ie both in and against an azimuthal direction adjacent to the edge zone cut.

3. Planning unit according to claim 1 or 2, wherein the data processing device is configured to calculate the access intersection data such that at least one edge zone segment intersection has a shape that is substantially triangular; substantially rectangular; or substantially triangular with a curved triangular side.

4. Planning unit according to claim 2, wherein the data processing device is designed to calculate the access intersection data such that the two edge zone segment intersections have boundary intersection lines arranged parallel to one another.

5. Planning unit according to one of claims 1 to 4, wherein the data processing device is designed to calculate the access interface data in such a way, - that the azimuth angle range of the edge zone cut is between 20° and 40°, preferably between 25° and 35°, more preferably substantially approximately 30°; and / or - that a central azimuth angle of the azimuth angle range between 0° and 360° can be set.

6. Planning unit according to one of claims 1 to 5, wherein the data processing device is designed to calculate the access cutting data such that the further azimuth angle range is between 1.5° and 15°, preferably between 0.75° and 7.5°.

7. An ophthalmic laser therapy device comprising a planning unit according to any one of claims 1 to 6, a laser device for providing therapeutic radiation, a focusing device for focusing the therapeutic radiation in a focus for severing the cornea within the tissue of the cornea, a scanning device for shifting the focus of the therapeutic radiation in the cornea of ​​the eye to produce the cutting surface, and a control unit which is connected to the planning unit via the at least one input and / or output interface for receiving the control data, wherein the control unit is further connected to control the laser device and / or to control the focusing device and / or to control the scanning device.

8. An ophthalmic laser therapy device according to claim 7, comprising a femtosecond laser or a picosecond laser for providing pulsed therapy radiation.

9. Planning method for generating control data for correcting the refraction of a cornea of ​​an eye having a main optical axis by corneal modification within the tissue of the cornea by means of an ophthalmological laser therapy device, comprising Receiving correction data representing a need for refraction correction, Calculating the volume of corneal tissue to be removed, based on the refractive correction required, Calculating cutting surface data representing at least one cutting surface completely delimiting the tissue volume, wherein the cutting surface data comprises: o Cap cut data representing a cap cut that delimits the tissue volume anteriorly, o Lenticle cut data representing a lenticule cut with a lenticule radius, wherein the lenticule cut delimits the tissue volume posteriorly, o Optional side cut data representing an optional side cut that radially delimits the tissue volume circumferentially with respect to the main optical axis and that extends at least to the cap cut and at least to the lenticule cut, and o Access cut data representing at least one access cut to the cap cut and to the lenticule cut, wherein the cap cut data comprises: Cover surface section data, which represent a cover surface section with a cover surface radius, Edge zone section data representing at least one edge zone section which adjoins the cover surface section in a predetermined azimuth angle range and has an edge zone radius which is greater than the cover surface radius, and Edge zone segment section data, which represent at least one edge zone segment section for each edge zone section, wherein the at least one edge zone segment section is arranged in a further azimuth angle range adjacent to the azimuth angle range of the edge zone section and merges into the edge zone section or borders on it at an azimuth angle present both in the azimuth angle range and in the further azimuth angle range, and Generating control data representing the cutting surface.

10. The planning method according to claim 9, further comprising method steps of a computer-implemented method for optimizing control data, comprising reading in or calculating start control data representing at least one cutting surface and its three-dimensional position and / or orientation in the cornea of ​​the eye; reading in nerve data representing a three-dimensional arrangement and / or a three-dimensional course and / or a thickness of nerves in the cornea of ​​an eye; generating a weighting value from the start control data and from the nerve data by applying a penalty and / or merit function to the number and / or type and / or section length of the nerves represented by the nerve data that overlap with the at least one cutting surface, wherein the weighting value represents a degree of severity of the overlap; and Providing the weighting value.

11. The planning method according to claim 10, further comprising: optimizing the weighting value by repeatedly generating the same from the nerve data and from follow-up control data, which are generated in a first iteration starting from the start control data and in subsequent iterations starting from previously generated follow-up control data by modifying at least one start parameter stored in the start control data; Providing those subsequent control data as optimized control data which result in the optimized weighting value.

12. Planning method according to claim 10 or 11, wherein the start control data comprise at least one predetermined parameter set of start parameters comprising a position of the access section and / or a cover surface radius and / or an edge zone radius and / or an azimuth angle range and / or a further azimuth angle range and / or a clearance distance and / or parameters of at least one edge zone segment section.

13. Planning method according to one of claims 10 to 12, wherein each start parameter can only be modified within a parameter interval specific to each parameter stored in the start control data and / or at least one start parameter can be set invariably as a fixed value.

14. Planning method according to one of claims 10 to 13, wherein the nerve data represent a measurement of a high-resolution OCT and / or a measurement of a confocal microscope, wherein the measurement preferably has a resolution of 5 pm or less.

15. Planning method according to one of claims 10 to 14, wherein, when generating the weighting value, a branching index of individual nerves represented by the nerve data is taken into account, wherein the branching index represents at least a number of branches after the cutting of nerves; and / or thickness information of individual nerves represented by the nerve data is taken into account, wherein the thickness information represents at least a thickness of the nerves; and / or residual length information is taken into account, wherein the residual length information represents at least a total length of the cut nerves represented by the nerve data.

16. Planning unit according to one of claims 1 to 6 or ophthalmological laser therapy device according to claim 7 or 8, which is designed to carry out a planning method according to one of claims 9 to 15.

17. A computer program product comprising instructions which, when loaded into a data processing device, cause the device to execute a planning method according to any one of claims 9 to 15.

18. A computer-readable non-volatile storage medium comprising the computer program product of claim 17.

Images