Refractive surgical laser system and method for determining a distance between a contact glass and a patient's eye

Abstract

A method (300) is provided for determining a distance (1002) between a contact glass (16) and a patient's eye (12). The method (300) comprises capturing (302) image information (700) concerning an optical reflection of the contact glass (16) from a surface of the patient's eye (12) through the contact glass (16), and determining (304) a lateral extent of the optical reflection of the contact glass (16) perpendicular to an optical axis (1000) of the contact glass (16) in the image information (700). The method moreover comprises determining the distance (1002) between the contact glass (16) and the patient's eye (12) along the optical axis (1000) of the contact glass (16) on the basis of the determined lateral extent of the optical reflection of the contact glass (16) in the image information (700).

Description

[0001] Refractive surgical laser system and method for determining a distance between a contact lens and a patient's eye

[0002] Provided are a method for determining a distance between a contact lens and a patient's eye, a method for determining a speed of a contact lens relative to a patient's eye, a method for preparing a refractive surgical treatment of a patient's eye by means of a laser system, a method for at least partially automated docking of a contact lens to a patient's eye, a use of image information captured by a contact lens of an optical reflection of the contact lens from a surface of a

[0003] A contact lens for determining the distance between the patient's eye and the contact lens, a control unit, and a refractive surgical laser system with a contact lens. The embodiments thus lie particularly in the field of refractive surgery and laser systems for this purpose.

[0004] During a refractive surgical procedure using a femtosecond laser, an excimer laser, or a solid-state laser, the user, such as the physician, must traditionally dock a contact lens of the laser system onto the patient's eye at the beginning of the laser treatment. This ensures correct centering of the laser system relative to the patient's eye, which is necessary for the success of the refractive surgical procedure. Using a joystick, the user can control the distance of the contact lens from the patient's eye along the optical axis of the contact lens (referred to as the z-coordinate) and the lateral position in a plane perpendicular to the optical axis of the contact lens (referred to as the xy-coordinate).The xy position can be identified automatically by detecting and marking the pupil center or by a positioning target relative to the pupil center. This can be displayed to the user via a computer and a display element to assist the laser system user in determining the xy position of the contact lens. Such a method is described, for example, in WO 2021 / 239605 A1.

[0005] However, a suitable choice of the position and speed of the contact lens in the z-direction, ie along the optical axis, during docking traditionally requires a high degree of skill and experience of the user.

[0006] Although methods for determining the distance between a laser system and the patient's eye are known in the prior art, these cannot be easily combined with a contact lens. For example, such a method is described in EP 3313265 A1. Methods are also known in the prior art, for example, from WO 2022 / 078998 A1, by means of which the position of a laser focus in the patient's eye can be determined based on multiple Purkinje reflections.

[0007] The object is therefore to provide a method and a laser system which overcome the disadvantages inherent in the state of the art.

[0008] The object is achieved by a method, a use, a control unit, and a refractive surgical laser system having the features of the respective independent claims. Optional embodiments are specified in the subclaims and in the description.

[0009] A method is provided for determining a distance between a contact lens and a patient's eye. The method comprises capturing image information of an optical reflection of the contact lens from a surface of the patient's eye through the contact lens and determining a lateral extent of the optical reflection of the contact lens perpendicular to an optical axis of the contact lens in the image information. Furthermore, the method comprises determining the distance between the contact lens and the patient's eye along the optical axis of the contact lens based on the determined lateral extent of the optical reflection of the contact lens in the image information.

[0010] Furthermore, a method for determining a speed of a contact lens relative to a patient's eye is provided. The method comprises determining a distance between the contact lens and the patient's eye using a method according to one of the preceding claims at a first time and at a second time. Furthermore, the method comprises determining a time period between the first time and the second time, and determining the speed of the contact lens relative to the patient's eye along the optical axis of the contact lens based on the determined distances of the contact lens from the patient's eye and the determined time period.

[0011] Furthermore, a method for preparing a refractive surgical treatment of a patient's eye using a laser system is provided. The method comprises determining a distance between a contact lens of the laser system and the patient's eye according to a method according to the disclosure, and outputting information regarding the determined distance to a user of the laser system.

[0012] In a further aspect, a method for at least partially automated docking of a contact lens to a patient's eye is provided. The method comprises repeatedly determining a distance between the contact lens and the patient's eye along the optical axis of the contact lens using a method according to the disclosure. Alternatively or additionally, the method comprises repeatedly determining a speed of the contact lens relative to the patient's eye using a method according to the disclosure.In addition, the method comprises approaching the contact glass to the patient's eye along the optical axis of the contact glass and regulating the distance between the contact glass and the patient's eye and / or regulating the speed of the contact glass relative to the patient's eye based on the repeatedly determined distance between the contact glass and the patient's eye and / or based on the repeatedly determined speed of the contact glass relative to the patient's eye.

[0013] In a further aspect, a use of image information captured by a contact glass of an optical reflection of the contact glass from a surface of a patient's eye is provided for determining the distance between the contact glass and the patient's eye along the optical axis of the contact glass and / or for determining a speed of the contact glass relative to the patient's eye along the optical axis of the contact glass.

[0014] In a further aspect, a refractive surgical laser system with a contact lens is provided. The laser system comprises an image acquisition unit configured to acquire image information of an optical reflection of the contact lens from a surface of the patient's eye through the contact lens. Furthermore, the laser system comprises a control unit configured to determine a lateral extent of the optical reflection of the contact lens perpendicular to an optical axis of the contact lens in the image information and to determine a distance between the contact lens and the patient's eye along the optical axis of the contact lens based on the determined lateral extent of the optical reflection of the contact lens in the image information.

[0015] In a further aspect, a therapeutic and / or diagnostic system is provided. The therapeutic and / or diagnostic system can be configured to couple to a patient's eye by means of a contact lens. The system comprises an image acquisition unit configured to acquire image information of an optical reflection of the contact lens from a surface of the patient's eye through the contact lens. Furthermore, the system comprises a control unit configured to determine a lateral extent of the optical reflection of the contact lens perpendicular to an optical axis of the contact lens in the image information and to determine a distance between the contact lens and the patient's eye along the optical axis of the contact lens based on the determined lateral extent of the optical reflection of the contact lens in the image information.

[0016] A contact lens is a contact element used to fix the patient's eye to the laser system for performing refractive surgical treatment. The contact lens does not necessarily have to be made of glass, but can also be made of another suitable material. The contact lens can, in particular, be made of a material that is transparent to laser radiation. Furthermore, the contact lens can be designed such that the image information captured by the optical reflection of the contact lens from a surface of the patient's eye is at least partially transmitted through the contact lens.

[0017] Image information can comprise an image which, for example, comprises a reflection on a surface of the patient's eye. The convex surface of the patient's eye can be used as a convex mirror in order to capture image information from an underside of the contact lens, i.e. from the side of the contact lens which faces the patient's eye, through the contact lens. Focusing, i.e. sharpening of the image, does not necessarily have to take place. Rather, it can be sufficient if outlines of the contact lens or of a part of the contact lens are recognizable in the image information in order to determine its lateral extent in the image information. In other words, an optical reflection of the contact lens from a surface of the patient's eye can comprise an image of the underside of the contact lens via a convex surface of the patient's eye, wherein the image capture takes place through the contact lens.The image information can then be presented in the form of electronic image data, which can optionally be evaluated using computer-assisted image analysis to determine the lateral extent of the contact lens in the image information. The lateral extent of the optical reflection of the contact lens in the image information is a measure of the angular range and / or spatial area occupied by the reflection of the contact lens in the determined image information. This does not necessarily require that the actual, physical lateral extent of the contact lens be clearly determinable from it.Rather, it may be sufficient if the specific lateral extent of the optical reflection of the contact glass in the image information changes in a predetermined manner with the distance between the contact glass and the patient's eye, and if qualitative and / or quantitative information about the distance can be obtained accordingly from the lateral extent of the optical reflection of the contact glass in the image information. Optionally, the lateral extent of the optical reflection of the contact glass in the image information can be scaled indirectly proportionally with the distance between the contact glass and the patient's eye. The lateral extent of the optical reflection of the contact glass in the image information can be such that the extent of the optical reflection of the contact glass in the image information occurs independently of the sharpness or focusing of the image of the optical reflection of the contact glass.

[0018] The distance between the contact lens and the patient's eye can be the distance between the underside of the contact lens facing the patient's eye and the patient's cornea. The underside of the contact lens can be adapted and designed to come into mechanical contact with the patient's eye during docking, thus securing it for refractive surgery.

[0019] The preparation for refractive surgical treatment of a patient's eye using a laser system can include creating a condition necessary for performing the treatment. In particular, the preparation can include docking the contact lens onto the patient's eye. The fact that some procedural steps are performed repeatedly can mean that these procedural steps are performed multiple times. This can occur at regular and / or irregular intervals. In particular, the procedure can be performed continuously, for example, several times per second, so that current information about the distance and / or speed of the contact lens relative to the patient's eye can always be provided.

[0020] A refractive surgical laser system can be a laser system that can be used to perform refractive surgical treatment on a patient's eye. Optionally, such a laser system can be configured as a femtosecond laser system. Optionally, the laser system can be suitable for performing a method for removing a lenticule from a patient's eye according to a SMILE method. SMILE stands for Small Incision Lenticle Extraction. Optionally, the laser system can be configured as or comprise an excimer laser system or a solid-state laser system. The laser system can be designed to change the refractive effect of the patient's eye by ablating a portion of the cornea.

[0021] The fact that the docking process is at least partially automated means that the process can be carried out partially or fully automated. If the process is fully automated, the process can optionally be carried out by the laser system without any further user intervention, whereby the user can always optionally intervene to make changes and / or stop the docking if desired. If the process is partially automated, the docking can be carried out at least partially by the laser system and involve user intervention. For example, the movement of the contact lens can be controlled by continuous input from the user, but the selection of the speed and the termination of the movement can be initiated by the laser system.

[0022] A surface of the patient's eye can be formed by the surface of the cornea and / or a moisture film on the cornea. These offer the advantage of generating particularly strong light reflections. Alternatively or additionally, reflections at other boundary layers in the patient's eye, such as higher-order Purkinje reflexes, can also be used.

[0023] The above-mentioned methods may be computer-implemented methods, i.e. one, several or all steps of the method can be carried out by a data processing device or a computer.

[0024] The disclosure offers the advantage that docking of the contact lens of the laser system can be partially or fully automated and / or a user of the laser system can be provided with assistance in approaching the contact lens and / or docking the contact lens to the patient's eye. Since the correct docking of the contact lens to the patient's eye is of great importance for the correct performance of a refractive surgical procedure on the patient's eye, this can increase the reliability of the method and reduce the risk of maltreatment due to faulty docking.

[0025] Furthermore, the disclosure offers the advantage that the skill and / or experience and / or training requirements of the laser system user can be reduced. Thus, the effort required to train the user to operate the laser system correctly can be reduced. Furthermore, the disclosure offers the advantage that the assistance provided when docking the contact lens to the patient's eye, or even automated docking, can shorten the time required for docking and, accordingly, the time required for the entire treatment. This can reduce the strain on the patient. Furthermore, the productivity of the laser system can be increased because a larger number of treatments can be performed in the same amount of time.

[0026] The lateral extent of the optical reflection of the contact lens in the image information can be a measure of an angular range and / or a spatial region occupied by the reflection of the contact lens in the image information. The determined lateral extent of the optical reflection of the contact lens in the image information can be indirectly proportional to the distance between the contact lens and the patient's eye along the optical axis of the contact lens. This can offer the advantage of establishing a quantitative relationship between the lateral extent of the optical reflection of the contact lens in the image information and the distance between the contact lens and the patient's eye along the optical axis of the contact lens.

[0027] The contact lens can optionally have a light source and be configured to provide a light pattern by means of the light source. In this case, determining the lateral extent of the optical reflection of the contact lens perpendicular to the optical axis of the contact lens in the image information can comprise determining the lateral extent of the light pattern in the image information. The light pattern can increase the brightness of the contact lens and, accordingly, improve the visibility of the reflection of the contact lens from a surface of the patient's eye. This can improve the reliability of determining the lateral extent of the reflection of the contact lens in the image information. The light source for providing the light pattern and / or the contact lens can be designed such that the light pattern has an outline oran outer boundary and / or a border of the contact glass and optionally an underside of the contact glass. The light pattern provided by the light source can be arranged directly on and / or in the immediate vicinity of the outer boundary of the underside of the light pattern. This can offer the advantage that detection of the lateral extent of the optical reflection of the contact glass perpendicular to an optical axis of the contact glass in the image information is simplified, since the light pattern optionally enables a higher contrast of the optical reflection of the contact glass in the image information than a contact glass without a light pattern. Based on a lateral extent of the light pattern in the image information, the lateral extent of the reflection of the contact glass in the image information can optionally be determined.Optionally, a lateral extent of the light pattern in the image information can be proportional to the extent of the reflection of the contact glass in the image information and / or equal to the extent of the reflection of the contact glass in the image information. The lateral extent of the light pattern in the image information can correspond to a distance between two predetermined points and / or elements of the light pattern. Optionally, the lateral extent can be determined based on a side length and / or a line width and / or a diameter of the light pattern. For the predetermined points and / or elements used, the respective center of the predetermined point and / or element and / or the point of maximum brightness of the predetermined points and / or elements can optionally be used in order to be able to reliably determine the lateral extent even in the event of any blurring of the light pattern in the image information.Determining a distance between two separate elements of the light pattern can optionally offer the advantage that the lateral extension in the image information can be reliably determined even if the light pattern is blurred in the image information. A line and / or a corner and / or an intersection and / or a center point of the light pattern can optionally be selected as the predetermined element.

[0028] The light source can form a component of the contact glass and / or otherwise have a fixed spatial relationship relative to the contact glass. In particular, the contact glass and / or the light source can be designed such that when the contact glass is moved, the light source moves along with the contact glass and the distance between the light source and the patient's eye changes accordingly, in the same way as the distance between the contact glass and the patient's eye. In the context of the present disclosure, moving the contact glass is generally understood to mean bringing about a relative movement between the contact glass and the patient's eye along the optical axis of the contact glass. This relative movement can alternatively or additionally also be achieved by moving the patient or the patient's eye.The fact that the light source has a fixed spatial relationship to the contact glass means that the position of the contact glass and, optionally, the position of the contact glass's central axis can be clearly determined from the position of the light source. Optionally, the light source is arranged directly in and / or on the contact glass. According to an optional embodiment, the light source is at least partially annular and surrounds the contact glass at least partially in the circumferential direction. The light pattern of such a light source can be in the form of a light ring, with the center of the light ring optionally lying on the central axis of the contact glass.

[0029] The fact that the light source has a fixed spatial relationship to the contact glass means that the position of the contact glass and, optionally, the position of the contact glass's central axis can be clearly determined from the position of the light source. Optionally, the light source is arranged directly in and / or on the contact glass. According to an optional embodiment, the light source is at least partially annular and surrounds the contact glass at least partially in the circumferential direction. The light pattern of such a light source can be in the form of a light ring, with the center of the light ring optionally lying on the central axis of the contact glass.

[0030] The light pattern can be a geometric arrangement of light, which is recognizable in the image information of the reflection of the contact lens through the contact lens. The light pattern is designed in such a way that information about the distance of the contact lens from the patient's eye can be derived from a lateral extent of the light pattern in the image information. The fact that the light pattern is imaged via a reflection on the surface of the eye means that the beam path of the light is folded on the surface of the eye during optical imaging. The curved surface of the eye optionally acts as an imaging optical element in the manner of a convex mirror. The lateral extent of the light source can have a fixed ratio to the lateral extent of the contact lens.

[0031] The light source can optionally be configured such that the light pattern identifies an outline and / or an outer boundary and / or a border of the underside of the contact lens. This can facilitate the assignment of the lateral extent of the contact lens to the lateral extent of the light pattern.

[0032] Determining the lateral extent of the light pattern in the image information may include determining a distance between two predetermined points and / or elements of the light pattern. This may allow for a simple evaluation of the image information.

[0033] The predetermined points and / or elements can optionally be predetermined as a respective center of a predetermined point and / or element and / or as a point of maximum brightness of the predetermined point and / or element. This can allow for easy identification of the predetermined points and / or elements in the image information. Furthermore, this can optionally offer the advantage that the predetermined points and / or elements in the image information can be reliably determined even if the image of the light pattern is blurred or not fully focused.

[0034] Optionally, the light pattern can comprise or be designed as a ring, a polygon, and / or a grid. For example, a ring-shaped light source can surround an outer contour of the underside of the contact lens, so that the outer contour of the underside of the contact lens can be identified by the light pattern. This offers the advantage that the optical reflection of the underside of the contact lens is particularly clearly visible.

[0035] The light pattern can optionally be provided in the visible light spectral range and / or in the infrared light range. A visible light pattern offers the advantage that its reflection can be recognized by the human eye without any aids. For example, the captured image information can be output directly to the user via a display element, allowing the user to recognize the reflection of the light pattern and use it to prepare for the surgical procedure, e.g., for docking. A light pattern made of infrared light, which is not visible to the patient, can offer the advantage that the patient is not irritated by the incident light pattern. For the method according to the disclosure, a sensor, such as a camera, which can nevertheless capture the infrared light pattern, can be used to capture the image information.

[0036] Outputting the information regarding the determined distance to the user can comprise displaying a graphic indicator using a display element. The graphic indicator can enable the user to read and / or estimate the distance. The determined information regarding the distance and / or the relative speed between the contact lens and the patient's eye is thereby presented to the user in a simple and intuitive manner, so that the user can use this information when carrying out a manual docking process and / or when monitoring an automated docking process. Alternatively or additionally, information regarding the distance and / or the speed can be output in the form of an acoustic signal. The acoustic signal can optionally indicate the distance by means of a pitch, as is common with a parking aid in the automotive sector, for example.This offers the advantage that the user does not have to look at a display element to perceive the information.

[0037] The graphic indicator may include a bar graph with a variable fill level, with the fill level of the bar graph indicating the measured distance between the contact lens and the patient's eye along the optical axis of the contact lens. This provides the user with information about the distance and / or speed in an easily understandable manner.

[0038] The laser system can be configured to repeatedly determine the distance and, optionally, to repeatedly determine a speed of the contact lens relative to the patient's eye. In particular, the laser system can be configured to continuously determine the distance, optionally the speed. This can offer the possibility of providing continuously updated information about the distance and / or the speed and using this information for the user for continuous use during manual docking and / or for continuous monitoring of automated docking. For this purpose, the laser system can comprise a display element and be configured to output information regarding the determined distance to a user of the laser system by means of the display element.

[0039] In addition, the continuously updated information about the distance and / or the speed can be used to regulate the speed for automated docking. The laser system can further comprise a positioning unit for positioning the contact lens along the optical axis of the contact lens. The laser system can further be configured to automatically approach the contact lens to the patient's eye by means of the positioning unit and to regulate the positioning of the contact lens by the positioning unit based on the repeatedly determined distance and / or the repeatedly determined speed. The speed at which the positioning unit approaches the contact lens to the patient's eye can be regulated by a control unit. In particular, the refractive surgical laser system can further be configured to automatically dock the contact lens to the patient's eye.

[0040] The laser system can have one or more movable pivoting arms, which can be referred to as robot arms. The pivoting arms can form part of the positioning unit. The contact lens can be attached to one of the pivoting arms, whereby the patient's eye can be positioned at least partially by means of the pivoting arm. The laser system can be configured to move and position the contact lens in three spatial directions by means of the pivoting arm. Furthermore, the laser system can optionally have a surgical microscope, which is arranged on a further pivoting arm and can be moved in three spatial directions by means of this. To use the surgical microscope, the contact lens can be removed from the patient's eye using the associated pivoting arm, so that sufficient space is available for positioning the surgical microscope using the associated pivoting arm.This offers the possibility of positioning the contact lens and / or the surgical microscope flexibly relative to the patient's eye without the necessity of positioning the patient's bed.

[0041] Specific optional features, embodiments, and examples are explained below, without the disclosure being limited to them. The method and the laser system can be configured such that a graphic indicator in the form of a bar display indicates a relative distance between the contact lens and the patient's eye. Accordingly, the bar display does not show absolute distances, but is merely a relative measure for the user to orientate themselves. The bar display can, for example, have a fill level that indicates the relative distance. If the bar is empty, this can indicate a large distance between the patient's eye and the contact lens. This can be the case if the lateral extent, e.g. the diameter, of the contact lens reflection in the image information is zero (DCGR = 0), i.e. the reflection is only visible as a point in the image information.If, on the other hand, the beam is filled to its maximum, this can correspond to a case where the diameter of the contact lens reflection (DCGR) corresponds to that of the contact lens (DCG) to which the light source is attached (DCGR = DCG). The light source can be designed as a ring light surrounding the contact lens. The height of the beam fill level, Hßar, can then be determined from the following relationship:

[0042] ,, _ D CGR

[0043] “Bar — "

[0044] U : CG

[0045] The method and the laser system can be configured such that a graphic indicator in the form of a bar graph indicates the absolute distance between the contact lens and the patient's eye. Calculating the absolute distance is particularly advantageous for automated docking and can optionally be derived analytically based on considerations of imaging on a concave mirror. For this purpose, the curvature of the cornea is taken into account, which can be described by the Rcv (radius of curvature). The Rcv (radius of curvature) of the cornea can be determined by averaging two corneal curvature radii, which belong to the two corneal meridians determined during refractive planning of the procedure. The functional relationship Z(DCGR) is then calculated as follows: with

[0046] Rcv g = - — where the parameters specify the following: z: distance between contact lens and eye

[0047] DCGR: Diameter of the reflection of the contact glass in the image data

[0048] DCG: Diameter of the contact lens

[0049] Rcv: radius of curvature of the cornea

[0050] Since the diameter of the illumination ring, which primarily generates the contact lens reflection, depends on the radius of the contact lens, different Z(DCGR) functions can result for different contact lens diameters (e.g. size S, M, L), which can be stored separately in the laser system and used by manual or automatic selection.

[0051] The relationship between the diameter of the contact lens's reflection in the image information and the distance of the contact lens from the patient's eye can optionally be determined empirically using a model eye. Alternatively, or in addition to an analytical calculation, this relationship Z(DCGR) can be determined by calibration on a human model eye. For this purpose, several pairs of values / interpolation points Zj(D(CGR,i)) are measured using service software and preferably stored in a look-up table.

[0052] The relationship z(DCGR) can then be determined by interpolating the value pairs Zj(D(CGR,i)). Optionally, the value pairs are approximated with a fit function (e.g., with a least-square optimization method), where the function was determined from the analytical relationship Z(DCGR) with the optimization parameters (a, b)

[0053] Optionally, different test eyes with different RCVs, optionally with different corneal humidifications (e.g., with water), and optionally with different room brightness levels are used for calibration to determine the value pairs. This can be advantageous because the scattering of the reflected light from the cornea, and thus the precision of the DCGR determination, can depend on the moisture content of the eye and also on the RCV.

[0054] The contrast sharpness with which DCGR can be detected can also depend on the brightness in the treatment room. Thus, the measurement results can depend on the prevailing lighting situation at the laser system. This can depend, for example, on the (averaged) brightness in lumens at the location of the contact lens or at the location of the laser system and / or on the type of light source. For this reason, for each set distance Zi, there can be a multitude of D(CGR) values, which can be recorded at different humidity levels, corneal curvature radii Rcv, and / or brightness levels in the room.

[0055] All recorded data points can then optionally be used to determine the Z(DCGR) function. Alternatively, separate Z(DCGR) functions can be determined for one, some, or all of the factors humidity level, Rcv, and / or brightness level.

[0056] Before and / or during the docking phase of the contact element to the patient's eye, the brightness level can then be determined using an optional light-sensitive sensor on the laser system and / or on the contact lens and / or in the treatment room, and the corresponding Z(DCGR) can be selected based on this. The moisture content of the patient's eye can also optionally be estimated from the data from the light sensor. The corneal curvature radius Rcv can be determined from refractive planning parameters provided for the planned treatment, optionally as the average of the curvature radii of the two corneal meridians.

[0057] Furthermore, a method for automated docking may involve an acceptance criterion that can be used to assess whether or not it is advisable to carry out the automated method.

[0058] Based on an inhomogeneity of the reflection of the contact glass from the surface of the patient's eye during docking, a decision can optionally be made as to whether the reflection can be used to determine the DCGR or not. A radial intensity distribution l(r), which can be approximated by a normal distribution at one or more angular positions Phi, can be used as a decision criterion. Based on a width (FWHM or sigma) and / or a tail (area far from the central value of the normal distribution) of the normal distribution, a decision can be made as to whether the contact glass reflection can be used to determine the DCGR, i.e., whether or not a signal quality is considered sufficient for determining the distance and speed. If insufficient signal quality is determined, the eye can optionally be rehydrated and / or the room brightness can be changed to improve the signal quality.

[0059] In the following, further background information is explained about an optional functional relationship between a diameter of the contact lens and the distance of the contact lens from the patient's eye and the speed to be selected.

[0060] A maximum speed can be specified for the speed at which the contact lens is brought closer to the patient's eye, particularly during automated docking but optionally also during manual docking. This can be done for safety reasons to avoid impact and the associated injury to the patient's eye. The maximum speed in the z-direction can optionally be 10 mm / s and optionally 5 mm / s.

[0061] The speed can be selected in two stages, i.e., two different speeds are specified, from which one speed is selected at any given time. The speed of the contact lens relative to the patient's eye along the optical axis of the contact lens, referred to as v(z), can optionally be controlled differently in two time intervals. The first time interval can refer to a first approach phase, in which the distance is greater than a predetermined threshold value ZT, i.e., z > z T The second time interval concerns a second approach phase in which the distance is smaller than the threshold, i.e. z < z T (T stands for threshold). The threshold value ZT can optionally be 3 mm.

[0062] In a first approach phase, the speed can be reduced with decreasing distance Z(DCGR), where Z(DCGR) was determined purely analytically and / or based on calibration. Reducing the speed can be advantageous from a safety perspective to reduce the risk of collision between the patient's eye and the contact lens. However, reducing the speed too much can be disadvantageous, as in this case the docking process takes longer than necessary and the treatment time is correspondingly extended. Therefore, the speed can optionally be reduced to a minimum value (plateau), which can be selected to ensure safe and rapid docking in the second docking phase.

[0063] The functional relationship can then result in: The constants a, b are optionally real numbers between 1 and 10. The constant c is optionally a real number between 0.5 and 3. Optionally, the method can also include decentering compensation.

[0064] For the precise determination of the DCGR and thus the distance (z), the correct centering of the laser's optical axis with respect to the eye can be advantageous. In the event of decentration, an optional approximation of a round contact glass reflection as a circle can be associated with a loss of accuracy, as elliptical distortions can occur (see Figs. 10A and 10B in the document WO 2021 / 239605 A1). To measure decentration, an inherently round contact glass reflection can be approximated as an ellipse, and the degree of decentration can be measured using an eccentricity £. The scanners of the laser system's laser can then be adjusted in xy such that the eccentricity falls below a specified limit, e.g., 0.1 . During a decentration compensation process, the velocity v(z) can optionally be reduced or set less than or equal to zero (v(z)<0) to avoid collision with the patient's eye.

[0065] Decentering with elliptical distortion can also occur if the contact lens is centered not on the corneal vertex (C_V), but rather on the pupil center or another point (see WO 2021 / 239605 A1). In this case, the contact lens reflex can be approximated as an ellipse, and the double semi-major axis can be used instead of DCGR for the Z(DCGR) calculation.

[0066] Optionally, the contact lens can be auto-centered relative to the patient's eye, i.e. the contact lens can be positioned in the xy plane.

[0067] Decentering compensation can optionally be performed fully automatically and at least partially parallel to the change in velocity v(z) and can be achieved by adjusting the laser system's scanner in xy. During a decentering compensation phase, v(z) can optionally be automatically reduced or set to v(z) < 0. The pupil can be used to determine the treatment center, especially for short distances z, as it is then clearly visible and the contact lens reflex optionally disappears from the acquired image or image information.

[0068] The docking further comprises a contact phase in which mechanical contact is established between the contact lens and the patient's eye. Upon contact, the speed v(z) is optionally set to 0, whereby contact feedback can be provided by force sensors on the contact lens. In addition, the water meniscus (tear film) of the patient's eye, which spreads upon contact between the contact lens edge and the cornea, can be taken into account and used as a signal for the presence of contact. When centered on the corneal vertex, the water meniscus spreads symmetrically from the vertex; if this is not the case, the speed v(z) < 0 can be set to less than zero, i.e. the contact lens can be removed from the eye, or reduced to a value v(z) > 0 and another contact attempt can be made. The contact lens can be in the applicator orin the laser system must be mounted in such a way that it can give way when it comes into contact with the eye in order to avoid damage to the eye due to excessive pressure. When this give way, the contact lens can move in the z-direction relative to the applicator by a distance s. By definition, z < 0 applies to all z-positions of the contact lens on this distance. If this distance s exceeds a limit value ST, a signal can be triggered by an optionally installed light barrier or a sensor, and the speed v(z) < 0 is set less than zero, so that the contact lens moves away from the eye and to a z-position 0 > z > ST.

[0069] For the method according to the disclosure, it is not necessary to provide an annular light pattern. Rather, the reflection of the contact lens without a light pattern can also be used. Alternatively or additionally, a different type of light pattern can be used, such as a dot pattern and / or Placido rings. A method using Placido rings as a light pattern will be discussed below as an example.

[0070] A diameter is determined for one, some, or several of the Placido rings illuminated as a light pattern. For example, this diameter will be designated with the index i for the i-th Placido ring. A diameter DCGRJ is determined and a distance Zi(DcGRj) is determined using an analytical formula or calibration. For safety reasons, the minimum of the distances and the maximum of the speed are always used for a bar display of the distance and for determining the speed v(z), if several different distances are determined.

[0071] To determine decentration, the eccentricity £ of several Placido rings can be used (for ellipse approximation). The Placido rings can also be used to precisely determine the corneal curvature radius Rcv of the patient's eye. If necessary, the corneal surface can also be approximated by an asphere with several different corneal curvature radii R_CV, which are then used to calculate Z(DCGR).

[0072] In the following, an optional example will be discussed where a dot pattern is used as the light pattern. The method for determining the distance may involve calculating some or all positions x f (z) of the centers of the reflected points. In addition, a comparison with known positions the centers of a point light source on the contact lens. The method may also include calculating a summed distance between all n point pairs:

[0073] In addition, the method may include determining a maximum summed distance s m ax at a large distance, e.g., for a distance of z = 5cm. The bar display of the graphic indicator then becomes:

[0074] ^Bar — ma x — S

[0075] The features and embodiments mentioned above and explained below are not only to be regarded as disclosed in the respective explicitly mentioned combinations, but are also encompassed by the disclosure content in other technically meaningful combinations and embodiments.

[0076] Further details and advantages will now be explained in more detail using the following examples and optional embodiments with reference to the figures.

[0077] They show:

[0078] 1A and 1B are schematic diagrams of a refractive surgical laser system according to optional embodiments;

[0079] Fig. 2 is a schematic sketch of the relative arrangement of the contact lens to the patient’s eye;

[0080] Fig. 3 - Fig. 6 diagrams of methods according to optional embodiments;

[0081] 7A and 7B show image information and information output to the user according to an optional embodiment. In the following figures, identical or similar elements in the various embodiments are denoted by identical reference numerals for the sake of simplicity.

[0082] Figure 1A shows a schematic representation of a refractive surgical laser system 10 for performing refractive surgical treatments of a patient's eye 12 of a patient 14 according to an optional embodiment.

[0083] The laser system 10 has a contact lens 16, by means of which the laser system 10 couples to the patient's eye 12. For this purpose, the patient 14 is positioned lying on a couch 15 so that his gaze is directed upwards and the laser system 10 can contact and fixate the patient's eye 12 vertically from above using the contact lens 16.

[0084] Furthermore, the laser system 10 includes a femtosecond laser 17 integrated into the laser system 10. The laser beam provided by the femtosecond laser 17 is used for refractive surgical treatment of the patient's eye 12 of the patient 14 and can be applied to the eye 12 through the contact lens 16. According to other optional embodiments, the laser system 10 can alternatively include an excimer laser or a solid-state laser. As an alternative to a laser system 10, the device can represent a therapeutic and / or diagnostic system for examining and / or treating a patient's eye.

[0085] Furthermore, the laser system 10 has a display element 18, by means of which the user of the laser system 10 or the physician can be shown an image of the eye 12 of the patient 14 to be treated, as well as an image of a light source 23 arranged on the contact lens 16 via a reflection on the surface of the eye 12. The image of the patient's eye 12 to be displayed is created through the contact lens 16, for example, by means of a digital video camera (not shown) which is integrated into the laser system 10. The image of the eye captured by the digital video camera can then optionally be output by the display element 18 together with superimposed virtual markings, so that the physician or user of the laser system 10 can check the eye 12 to be treated and in particular its positioning relative to the contact lens 16.

[0086] The laser system 10 is designed such that a relative movement of the patient 14 to the contact lens and / or to the laser system 10 can be brought about. For this purpose, the laser system 10 can have, for example, a positioning unit 21. The relative movement can comprise a lateral relative movement, i.e. perpendicular to the optical axis of the contact lens 16, in order to assume a suitable positioning of the contact lens for the refractive surgical treatment of the patient's eye 12, and also in the longitudinal direction, i.e. along the optical axis of the contact lens, in order to change the distance between the contact lens 16 and the eye 12 and in particular to fix the contact lens 16 to the eye 12 and to detach it from the eye 12. Alternatively or additionally, the patient can be moved vertically by means of the couch 15.

[0087] In addition, the laser system 10 has an image acquisition unit 20, which is configured to acquire image information of an optical reflection of the contact glass 16 from a surface of the patient's eye through the contact glass 16. Furthermore, the laser system 10 has a control unit 19, which is configured to determine a lateral extent of the optical reflection of the contact glass 16 perpendicular to an optical axis of the contact glass 16 in the image information and to determine a distance between the contact glass 16 and the patient's eye 12 along the optical axis of the contact glass 16 based on the determined lateral extent of the optical reflection of the contact glass 16 in the image information. For this purpose, the control unit 19 can be connected to the image acquisition unit 20, so that the image information received by the image acquisition unit 20 can be transmitted to the control unit 19.

[0088] The laser system 10 is further configured to repeatedly determine the distance and optionally to repeatedly determine a speed of the contact lens 16 relative to the patient's eye 12.

[0089] Furthermore, the laser system 10 is configured to output information regarding the determined distance to a user of the laser system via the display element 18. For this purpose, the display element can be designed as a computer display or include such a display. Alternatively or additionally, the display element 18 can have one or more loudspeakers to output the information regarding the distance to the user as an acoustic signal.

[0090] The laser system 10 further comprises a positioning unit for positioning the contact lens 16 along the optical axis of the contact lens 16, which can be integrated into the laser system 10 and can form an integral part of the laser system 10. In particular, the control unit 19 can be connected to the positioning unit for this purpose, wherein the laser system 10 is further configured to automatically approach the contact lens 16 to the patient's eye 12 and to regulate the positioning of the contact lens 16 by the positioning unit based on the repeatedly determined distance and / or the repeatedly determined speed. As a result, the laser system 10 is capable of automatically moving the contact lens 16 along the optical axis of the contact lens 16 and docking it onto the patient's eye 12.

[0091] The contact lens 16 further comprises a light source 22, by means of which a light pattern can be emitted and provided in the direction of the patient's eye 12. This can improve the visibility of the contact lens 16 in the reflection on the cornea, which is collected by the contact lens 16 and then captured by the image capture unit 20, and thus increase the reliability and accuracy of the distance determination. The light source 22 can be arranged around the lower edge of the contact lens so that the light source provides an annular light pattern. The light source is fixedly connected to the contact lens or forms part of it. Thus, when the contact lens 16 is moved, the light source 22 also moves accordingly. The lateral extent of the light source 16 has a fixed relationship to the lateral extent of the contact lens 16.According to various embodiments, the light pattern can optionally comprise a ring and / or a polygon and / or a grid or the like. The light pattern can be provided in the spectral range of visible light and / or in the range of infrared light.

[0092] Figure 1B shows a refractive surgical laser system 10 according to a further optional embodiment. This differs from the embodiment shown in Figure 1A in particular in that it has a pivoting device 24, by means of which one of several pivoting arms 26 can be selectively positioned in order to examine and / or treat the patient's eye 12. The unit of the refractive surgical laser system 10 which serves for the refractive surgical treatment of the patient's eye 12 and which has the contact lens 16 for docking onto the patient's eye 12 is arranged on one of the pivoting arms 26. A surgical microscope 28 is arranged on the other pivoting arm 26 and can be pivoted toward the patient's eye 12 in order to examine the patient's eye 12. This can occur when the other pivoting arm is pivoted away from the patient's eye.Furthermore, according to this embodiment, the couch 15 is designed separately from the laser system 10 and can be designed to be positionable in order to perform or support the relative positioning of the patient's eye 12 and the contact lens 16. Furthermore, the laser system 10 has a positioning unit 21, by means of which the laser system 10 and in particular the pivot arms 26 can be positioned. The positioning system 21 can also be used for at least partial relative positioning of the contact lens 16 relative to the patient's eye 12.

[0093] Figure 2 schematically shows a relative arrangement of a contact lens 16 of a laser system 10 and a patient's eye 12. The underside 16a of the contact lens 16, which faces the patient's eye, is curved in order to be able to establish the largest possible contact with the cornea 12a of the eye 12. In the illustration shown, the contact lens is arranged along the optical axis 1000 of the contact lens at a distance from the patient's eye 12. The distance is shown as 1002 and designates the distance between the underside 16a of the contact lens 16 on the optical axis 1000 and the intersection point of the cornea 12a with the optical axis 1000. Arrow 1004 indicates the possible directions of movement for increasing and decreasing the distance 1002 along the optical axis 1000, which are referred to as upward and downward.

[0094] With reference to Figure 3, a method 300 for determining a distance 1002 between a contact lens 16 and a patient's eye 12 is explained using a schematic diagram. The method 300 comprises, in step 302, capturing image information of an optical reflection of the contact lens 16 from a surface of the patient's eye 12 by the contact lens 16.

[0095] Step 304 of method 300 includes determining a lateral extent of the optical reflection of contact glass 16 perpendicular to an optical axis 1000 of contact glass 116 in the image information. This may include determining the lateral extent of the light pattern provided by light source 22 in the image information.

[0096] Step 306 of method 300 comprises determining the distance 1002 between the contact glass 16 and the patient's eye 12 along the optical axis 1000 of the contact glass 16 based on the determined lateral extent of the optical reflection of the contact glass 16 in the image information. Figure 4 shows a schematic diagram of a method 400 for determining a speed of a contact glass 16 relative to a patient's eye 2. In a first step 402, the method 400 comprises determining a distance 1002 between the contact glass 16 and the patient's eye 12 by means of a method 300, as described with reference to Figure 3, at a first time and at a second time.

[0097] In a step 404, the method 400 includes determining a time period between the first time and the second time.

[0098] In a step 406, the method 400 comprises determining the speed of the contact glass 16 relative to the patient's eye 12 along the optical axis 1000 of the contact glass 16 based on the determined distances 1002 of the contact glass from the patient's eye 12 and the determined time period.

[0099] Figure 5 shows a schematic diagram of a method 500 for preparing a refractive surgical treatment of a patient's eye 12 using a laser system 10.

[0100] The method 500 comprises, in a step 502, determining a distance 1002 between a contact lens 16 of the laser system 10 and the patient's eye 12 according to a method as described with reference to Figure 3.

[0101] The method 500 further comprises, in step 504, outputting information relating to the determined distance 1002 to a user of the laser system 10. Outputting the information relating to the determined distance 1002 to the user can comprise displaying a graphic indicator by means of the display element 18, wherein the graphic indicator enables the user to read and / or estimate the distance 1002. The graphic indicator 24 (see Figure 8) can have a bar display with a variable fill level, wherein the fill level of the bar display indicates the determined distance between the contact lens 16 and the patient's eye 12 along the optical axis 1000 of the contact lens 16.

[0102] Figure 6 shows a schematic diagram of a method 600 for at least partially automated docking of a contact lens 16 to a patient's eye 12.

[0103] The method 600 comprises, in a step 602, repeatedly determining a distance 1002 between the contact lens 16 and the patient's eye 12 along the optical axis 1000 of the contact lens 16 by means of a method as described with reference to Figure 3.

[0104] Alternatively or additionally, the method 600 comprises, in a step 604, repeatedly determining a speed of the contact lens 16 relative to the patient's eye 12 by means of a method as described with reference to Figure 4.

[0105] In step 606, the method 600 includes approaching the contact lens 16 to the patient's eye 12 along the optical axis 1000 of the contact lens 16.

[0106] In step 608, the method 600 comprises regulating the distance 1002 between the contact glass 16 and the patient's eye 12 and / or regulating the speed of the contact glass 16 relative to the patient's eye 12 based on the repeatedly determined distance 1002 between the contact glass 16 and the patient's eye 12 and / or based on the repeatedly determined speed of the contact glass 16 relative to the patient's eye 12.

[0107] Accordingly, it is possible to use image information captured by a contact glass 16, an optical reflection of the contact glass 16 from a surface of a patient's eye 12, to determine the distance 1002 between the contact glass 16 and the patient's eye 12 along the optical axis 1000 of the contact glass 16 and / or to determine a speed of the contact glass 16 relative to the patient's eye 12 along the optical axis 1000 of the contact glass 16.

[0108] The control unit 16 can be configured to control a refractive surgical laser system 10 with a contact glass 16 for carrying out one of the above-mentioned methods.

[0109] Figures 7A and 7B show two exemplary reproductions of image information 700 and 702, which include an optical reflection of the underside 16a of the contact lens 16 from the cornea 12a of the patient's eye 12, which was transmitted through the contact lens and captured by the image capture unit 20. The illustrated reproductions of the image information 700 and 702 can, for example, be output to the user via the display element 18, so that the user can control and / or monitor the docking process of the contact lens 16 to the patient's eye 12.

[0110] The two pieces of image information 700 and 702 differ in that they were acquired at different distances between the contact lens 16 and the patient's eye 12. Image information 700 in Figure 7A was acquired at a greater distance between the contact lens 16 and the patient's eye 12 than image information 702.

[0111] The image information 700 and 702 contain information about the light waves transmitted through the contact lens 16. Accordingly, the pupil and surrounding parts of the iris of the patient's eye 12 can be seen centrally in the background. It can be seen that a focused image of the cornea or iris is not necessarily required to carry out the method. Furthermore, the reflection of a light pattern 706, which is ring-shaped and provided by the ring-shaped light source 22 on the contact lens 16, can be seen as a bright ring in the image information. At a greater distance between the contact lens 16 and the patient's eye 12 (image information 700 and Figure 7A), the reflection of the light pattern 706 and the contact lens 16 in the image information 700 is smaller than at a shorter distance (image information 702, Figure 7B).

[0112] Based on the determined lateral extent of the reflection of the contact glass 16 and in particular of the light pattern 706, the distance 1002 of the contact glass 16 from the patient's eye 12 can then be determined, as explained above. A larger lateral extent generally indicates a smaller distance 1002. Optionally, a coincidence of the reflection of the contact glass 16 or of the light pattern 706 with the outer edge of the image information can indicate the presence of contact between the contact glass 16 and the cornea 12a of the patient's eye 16. For example, the control unit 19 can output a marking 708 that identifies the determined lateral extent of the contact glass 16 in the image information.

[0113] In addition to displaying the image information, Figures 7A and 7B each show a graphic indicator 710 indicating the distance between the contact lens 16 and the patient's eye 12. The graphic indicator 710 is configured as a bar display, with the "fill height" of the bar representing a measure of the determined distance 1002 between the contact lens 16 and the patient's eye 12. The higher the fill height of the bar, the greater the determined distance. Therefore, for example, in Figure 7A, due to the larger distance 1002, the fill height of the bar is greater than in Figure 7B with a smaller distance 1002. The graphic indicator 710 can make it easier for the user of the laser system to control and / or monitor the distance 1002 and / or the docking process. List of Reference Symbols

[0114] 10 refractive surgical laser system

[0115] 12 patient's eye

[0116] 12a Cornea

[0117] 14 patients

[0118] 15 loungers

[0119] 16 contact lenses

[0120] 16a Bottom of the contact glass

[0121] 17 femtosecond lasers

[0122] 18 Display element

[0123] 19 Control unit

[0124] 20 image acquisition unit

[0125] 21 Positioning unit

[0126] 22 Light source

[0127] 24 Swivel device

[0128] 26 Swivel arm

[0129] 28 surgical microscope

[0130] 300, 400, 500, 600 procedures

[0131] 302 - 608 process steps

[0132] 700, 702 Image information

[0133] 706 light patterns

[0134] 708 lateral extent of the reflection of the contact glass

[0135] 710 graphic indicator

[0136] 1000 optical axis of the contact glass

[0137] 1002 Distance between contact lens and patient's eye

[0138] 1004 z-direction

Claims

Patent claims 1 . Method (300) for determining a distance (1002) between a contact lens (16) and a patient's eye (12), the method (300) comprising the steps: - capturing (302) image information (700) of an optical reflection of the contact glass (16) from a surface of the patient's eye (12) through the contact glass (16); - determining (304) a lateral extent of the optical reflection of the contact glass (16) perpendicular to an optical axis (1000) of the contact glass (16) in the image information (700); - Determining the distance (1002) between the contact glass (16) and the patient's eye (12) along the optical axis (1000) of the contact glass (16) based on the determined lateral extent of the optical reflection of the contact glass (16) in the image information (700).

2. Method (300) according to claim 1, wherein the lateral extent of the optical reflection of the contact glass (16) in the image information (700) is a measure of an angular range and / or a spatial range which the reflection of the contact glass (16) occupies in the image information (700).

3. Method (300) according to claim 1 or 2, wherein the determined lateral extent of the optical reflection of the contact glass (16) in the image information (700) is indirectly proportional to the distance (1002) between the contact glass (16) and the patient's eye (12) along the optical axis (1000) of the contact glass (16).

4. Method (300) according to one of the preceding claims, wherein the contact glass (16) has a light source (22) and is configured to provide a light pattern (706) by means of the light source (22), and wherein determining the lateral extent of the optical reflection of the contact glass (16) perpendicular to the optical axis (1000) of the contact glass (16) in the image information (700) comprises determining the lateral extent of the light pattern (706) in the image information (700).

5. The method (300) according to claim 4, wherein a lateral extent of the light source (22) has a fixed ratio to the lateral extent of the contact glass (16).

6. The method (300) according to claim 4 or 5, wherein the light source (22) is configured such that the light pattern (706) identifies an outline and / or an outer boundary and / or a border of the contact glass (16), optionally an underside (16a) of the contact glass (16).

7. The method (300) according to any one of claims 4 to 6, wherein determining the lateral extent of the light pattern in the image information comprises determining a distance between two predetermined points and / or elements of the light pattern.

8. The method (300) according to claim 7, wherein the predetermined points and / or elements are predetermined as a respective center of a predetermined point and / or element and / or as a point of maximum brightness of the predetermined point and / or element.

9. The method (300) according to any one of claims 4 to 8, wherein the light pattern (706) optionally comprises a ring and / or a polygon and / or a grid.

10. The method (300) according to any one of claims 4 to 9, wherein the light pattern (706) is provided in the spectral range of visible light and / or in the range of infrared light.

11. A method (400) for determining a speed of a contact lens (16) relative to a patient's eye (12), the method (400) comprising: - determining (402) a distance (1002) between the contact lens (16) and the patient's eye (12) by means of a method (300) according to one of the preceding claims at a first time and at a second time; - determining (404) a time period between the first time and the second time; - Determining (406) the speed of the contact glass (16) relative to the patient's eye (12) along the optical axis (1000) of the contact glass (16) based on the determined distances of the contact glass (16) from the patient's eye (12) and the determined time period.

12. A method (500) for preparing a refractive surgical treatment of a patient's eye (12) using a laser system (10), the method (500) comprising: - determining (502) a distance (1002) between a contact lens (16) of the laser system (10) and the patient's eye (12) according to a method (300) according to one of claims 1 to 10; - Outputting (504) information concerning the determined distance (1002) to a user of the laser system (10).

13. The method (500) according to claim 12, wherein outputting the information relating to the determined distance (1002) to the user comprises displaying a graphic indicator (710) by means of a display element (18), wherein the graphic indicator (710) enables the user to read and / or estimate the distance (1002).

14. The method (500) according to claim 13, wherein the graphic indicator (710) comprises a bar display with a variable fill level, wherein the fill level of the bar display represents the determined distance (1002) between the contact glass (16) and the patient's eye (12) along the optical axis of the contact lens (16).

15. A method (600) for at least partially automated docking of a contact lens (16) to a patient's eye (12), the method (600) comprising: - repeatedly determining (602) a distance (1002) between the contact lens (16) and the patient's eye (12) along the optical axis (1000) of the contact lens (16) by means of a method (300) according to one of claims 1 to 10; and / or - repeatedly determining (604) a speed of the contact glass (16) relative to the patient's eye (12) by means of a method (400) according to claim 11; - approaching (606) the contact lens (16) to the patient's eye (12) along the optical axis (1000) of the contact lens (16); and - controlling (608) the distance (1002) between the contact glass (16) and the patient's eye (12) and / or controlling the speed of the contact glass (16) relative to the patient's eye (12) based on the repeatedly determined distance (1002) between the contact glass (16) and the patient's eye (12) and / or based on the repeatedly determined speed of the contact glass (16) relative to the patient's eye (12).

16. Use of image information (700) captured by a contact glass (16) of an optical reflection of the contact glass (16) from a surface of a patient's eye (12) for determining the distance (1002) between the contact glass (16) and the patient's eye (12) along the optical axis (1000) of the contact glass (16) and / or for determining a speed of the contact glass (16) relative to the patient's eye (12) along the optical axis (1000) of the contact glass (16).

17. Control unit (19) which is configured to control a refractive surgical laser system (10) with a contact glass (16) for carrying out a method according to one of the preceding claims.

18. Refractive surgical laser system (10) with a contact lens (16), the laser system (10) comprising: - an image acquisition unit (20) which is configured to acquire image information (700) of an optical reflection of the contact glass (16) from a surface of the patient's eye (12) through the contact glass (16); - a control unit (19) which is designed to: - to determine a lateral extent of the optical reflection of the contact glass (16) perpendicular to an optical axis (1000) of the contact glass (16) in the image information (700); and - to determine a distance (1002) between the contact glass (16) and the patient's eye (12) along the optical axis (1000) of the contact glass (16) based on the determined lateral extent of the optical reflection of the contact glass (16) in the image information (700).

19. Refractive surgical laser system (10) according to claim 18, wherein the laser system (10) is configured to repeatedly determine the distance (1002) and optionally to repeatedly determine a speed of the contact lens (16) relative to the patient's eye (12).

20. Refractive surgical laser system (10) according to claim 19, further comprising a display element (18), wherein the laser system (10) is configured to output information relating to the determined distance (1002) to a user of the laser system (10) by means of the display element (18).

21. Refractive surgical laser system (10) according to claim 19 or 20, further comprising a positioning unit (21) for positioning the contact glass (16) along the optical axis (1000) of the contact glass (16), wherein the laser system (10) is further configured to to approach the patient's eye (12) automatically by means of the positioning unit (21) and to control a positioning of the contact glass (12) by the positioning unit (21) on the basis of the repeatedly determined distance (1002) and / or the repeatedly determined speed.

22. Refractive surgical laser system (10) according to claim 21, wherein the laser system (10) is further configured to automatically dock the contact lens (16) to the patient's eye (12).

Images