DE102022121079A1 - REFRACTIVE SURGICAL LASER SYSTEM AND METHOD FOR DETERMINING A DISTANCE BETWEEN A CONTACT LENS AND A PATIENT'S EYE - Google Patents

Abstract

A method (300) is provided for determining a distance (1002) between a contact lens (16) and a patient's eye (12). The method (300) includes detecting (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), as well as 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 also includes 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 specific lateral extent of the optical reflection of the contact glass (16) in the Image information (700).

Description

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 using a laser system, a method for at least partially automated docking of a Contact glass to a patient's eye, 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 to determine the distance between the contact glass and the patient's eye, a control unit, and refractive surgical laser system with a contact glass. The embodiments are therefore particularly in the field of refractive surgery and laser systems for this purpose.

In a refractive surgical procedure using a femtosecond laser or an excimer laser or a solid-state laser, the user, such as the doctor, conventionally has to dock a contact lens of the laser system to the patient's eye at the beginning of the laser treatment. This serves to correctly center the laser system relative to the patient's eye, which is necessary for the success of the refractive surgical procedure. The user can use a joystick to control the distance of the contact lens to the patient's eye along the optical axis of the contact lens (referred to as z coordinate) and the lateral position in a plane perpendicular to the optical axis of the contact lens (referred to as xy coordinates). The xy position can be identified automatically via detection and marking of the center of the pupil or via a positioning target relative to the center of the pupil and can be displayed to the user using a computer and a display element in order to assist the user of the laser system in determining the xy position of the contact lens support. Such a method is described in the publication, for example WO 2021/239605 A1 described.

However, a suitable choice of the position and speed of the contact glass in the z-direction, i.e. along the optical axis, during docking conventionally requires a high degree of skill and experience on the part of the user.

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

The task is therefore to provide a method and a laser system which overcome the disadvantages inherent in the prior art.

The task is solved by a method, a use, a control unit and a refractive surgical laser system with the features of the respective independent claims. Optional refinements are specified in the subclaims and in the description.

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

Furthermore, a method for determining a speed of a contact lens relative to a patient's eye is provided. The method includes determining a distance between the contact lens and the patient's eye by means of a method according to one of the preceding claims at a first time and at a second time. In addition, the method includes determining a time period between the first time and the second time, as well as determining the speed of the contact glass relative to the patient's eye along the optical axis of the contact glass based on the determined distances of the contact glass from the patient's eye and the determined time period.

In addition, a method for preparing a refractive surgical treatment of a patient's eye using a laser system is provided. The method includes determining a distance between a contact lens of the laser system and the patient's eye according to a method according to the disclosure, as well as outputting information regarding the determined distance to a user of the laser system.

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 includes 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 includes repeatedly determining a speed of the contact glass relative to the patient's eye using a method according to the disclosure. In addition, the method includes approaching the contact lens to the patient's eye along the optical axis of the contact lens and regulating the distance between the contact lens and the patient's eye and / or regulating the speed of the contact lens relative to the patient's eye based on the repeatedly determined distance between the contact lens and the patient's eye and/or based on the repeatedly determined speed of the contact lens relative to the patient's eye.

In a further aspect, image information recorded by a contact glass of an optical reflection of the contact glass from a surface of a patient's eye is used to determine the distance between the contact glass and the patient's eye along the optical axis of the contact glass and / or to determine a speed of the contact glass relative to the Patient eye provided along the optical axis of the contact lens.

In a further aspect, a refractive surgical laser system with a contact lens is provided. The laser system includes an image capture unit which is set up to capture image information of an optical reflection of the contact glass from a surface of the patient's eye through the contact glass. In addition, the laser system includes a control unit which is set up to determine a lateral extent of the optical reflection of the contact glass perpendicular to an optical axis of the contact glass in the image information and to determine a distance between the contact glass and the patient's eye along the optical axis of the contact glass based on the determined to determine the lateral extent of the optical reflection of the contact glass in the image information.

In a further aspect, a therapeutic and/or diagnostic system is provided. The therapeutic and/or diagnostic system can be set up to be coupled to a patient's eye using a contact lens. The system includes an image capture unit which is set up to capture image information of an optical reflection of the contact glass from a surface of the patient's eye through the contact glass. In addition, the system includes a control unit which is set up to determine a lateral extent of the optical reflection of the contact glass perpendicular to an optical axis of the contact glass in the image information and to determine a distance between the contact glass and the patient's eye along the optical axis of the contact glass based on the determined to determine the lateral extent of the optical reflection of the contact glass in the image information.

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

Image information can include an image which, for example, includes 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 glass, i.e. from that side of the contact glass that faces the patient's eye, through the contact glass. Focusing, i.e. sharpening the image, does not necessarily have to take place. Rather, it may be sufficient if outlines of the contact glass or part of the contact glass are visible in the image information in order to determine its lateral extent in the image information. In other words, an optical reflection of the contact glass from a surface of the patient's eye can include an image of the underside of the contact glass via a convex surface of the patient's eye, with the image capture taking place through the contact glass. The image information can then be presented in the form of electronic image data, which can optionally be evaluated using computer-aided image evaluation in order to determine the lateral extent of the contact glass in the image information.

The lateral extent of the optical reflection of the contact glass in the image information is a measure of the one angular range and/or spatial area that the reflection of the contact glass occupies in the determined image information. This does not necessarily require that this be the case The actual, physical lateral extent of the contact glass must be clearly determinable. 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 the lateral extent of the optical reflection of the contact glass in the image information corresponds to a qualitative one and/or quantitative information about the distance can be obtained.

The distance between the contact glass and the patient's eye can represent a distance between an underside of the contact glass facing the patient's eye and the cornea of the patient's eye. The underside of the contact glass can be adapted and intended to come into mechanical contact with the patient's eye during docking and to fix it for the refractive surgical treatment.

The preparation of a refractive surgical treatment of a patient's eye using a laser system can include bringing about a condition that is necessary for carrying out the treatment. In particular, the preparation can include docking the contact lens to the patient's eye.

The fact that some process steps are carried out repeatedly can mean that these process steps are carried out several times. The implementation can take place at regular and/or irregular intervals. In particular, the implementation can take place continuously, for example several times per second, so that current information about the distance and/or the speed of the contact lens relative to the patient's eye can always be provided.

A refractive surgical laser system can be a laser system that can be used to carry out refractive surgical treatment on a patient's eye. Optionally, such a laser system can be designed as a femtosecond laser system. Optionally, the laser system can be suitable for carrying out a procedure for removing a lenticule from a patient's eye according to a SMILE procedure. SMILE stands for Small Incision Lenticle Extraction. Optionally, the laser system can be designed as or include 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 part of the cornea.

The fact that the docking process is at least partially automated means that the process can be carried out in a partially automated or completely automated manner. If carried out completely automatically, the method can optionally be carried out by the laser system without any further action on the part of the user, whereby the user can always optionally have the option of intervening in order to make changes and/or stop the docking if desired. If carried out in a partially automated manner, the docking can be carried out at least partially by the laser system and involve user intervention. For example, carrying out a movement of the contact glass can be controlled by a continuous input from the user, but the choice of speed and termination of the movement can be initiated by the laser system.

A surface of the patient's eye can be formed by a surface of the cornea and/or a moisture film on the cornea. These offer the advantage that a particularly bright reflection can be generated. Alternatively or additionally, however, reflections at other boundary layers in the patient's eye can also be used, such as higher-order Purkinje reflections.

The above-mentioned methods can 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.

The disclosure offers the advantage that docking of the contact lens of the laser system can be partially or completely automated and/or a user of the laser system can be offered support when approaching the contact lens and/or when 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 implementation of a refractive surgical procedure on the patient's eye, the reliability of the procedure can be increased and the risk of incorrect treatment due to incorrect docking can be reduced.

Furthermore, the disclosure offers the advantage that the requirements for the skill and/or experience and/or training of the user of the laser system can be reduced. This means that the effort required to train the user to correctly operate the laser system can be reduced.

Furthermore, the disclosure offers the advantage that the support 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 burden on the patient. In addition, the productivity of the laser system can be increased because a larger number of treatments can be carried out in the same amount of time.

The contact glass can optionally have a light source and can be set up to provide a light pattern using the light source. In this case, determining the lateral extent of the optical reflection of the contact glass perpendicular to the optical axis of the contact glass in the image information can include determining the lateral extent of the light pattern in the image information. The light pattern can increase the brightness of the contact glass and accordingly improve the visibility of the reflection of the contact glass from a surface of the patient's eye. This makes it possible to improve the reliability of the determination of the lateral extent of the reflection of the contact glass in the image information.

The light source can form a component of the contact glass and/or otherwise have a fixed positional relationship relative to the contact glass. In particular, the contact glass and/or the light source can be designed in such a way that when the contact glass is moved, the light source moves with the contact glass and the distance between the light source and the patient's eye changes 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 central axis of the contact glass 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.

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 central axis of the contact glass 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.

The light pattern can be a geometric arrangement of light, which can be seen in the image information of the reflection of the contact glass through the contact glass. 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 during the optical imaging on the surface of the eye. 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 glass.

Optionally, the light pattern can comprise a ring and/or a polygon and/or a grid or can be designed as such. For example, an annular light source can surround an outer contour of the underside of the contact glass, so that the outer contour of the underside of the contact glass can be recognized based on the light pattern. This offers the advantage that the optical reflection of the underside of the contact glass is particularly easy to see.

The light pattern can optionally be provided in the spectral range of visible light and/or in the range of infrared light. A light pattern made of visible light offers the advantage that its reflection can be seen by the human eye without any aids. For example, the captured image information can be output directly to the user via a display element so that the user can recognize the reflection of the light pattern and use it to prepare for the surgical procedure, for example for docking. A light pattern 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, can be used to capture the image information, which can still capture the infrared light pattern.

Outputting the information regarding the determined distance to the user may include displaying a graphic indicator using a display element. The graphic indicator can allow the user to read and/or estimate the distance. As a result, the determined information about the distance and/or the relative speed between the contact lens and the patient's eye is presented to the user in a simple and intuitive manner, so that the user can use this 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 using a pitch, as is common, for example, with a parking aid in the automotive sector. This offers the advantage that the user does not have to direct his gaze at a display element to perceive the information.

The graphic indicator can have a bar display with a variable level, the level of the bar display indicating the determined 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 easy-to-understand manner.

The laser system can be set up 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 set up to continuously determine the distance, optionally the speed. This may provide the ability to provide constantly updated distance and/or speed information and for use by the user for ongoing use during manual docking and/or ongoing monitoring of automated docking. For this purpose, the laser system can include a display element and can be set up to output information regarding the determined distance to a user of the laser system by means of the display element.

In addition, the continuously updated information about the distance and/or speed can be used to regulate the speed for automated docking.

The laser system can further have a positioning unit for positioning the contact glass along the optical axis of the contact glass. The laser system can also be set up to automatically approach the contact lens to the patient's eye using the positioning unit and to regulate 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 also be set up to automatically dock the contact lens to the patient's eye.

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

Specific optional features, embodiments and examples are explained below, without the disclosure being limited to these.

The method and the laser system can be designed in such a way that a graphic indicator in the form of a bar graph indicates a relative distance between the contact lens and the patient's eye. The bar display does not show absolute distances, but is only a relative measure for the user's orientation. The bars Display can have a fill level, which 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, such as the diameter, of the contact glass reflection in the image information is zero (D _CGR = 0), i.e. the reflex is only visible as a point in the image information. On the other hand, if the bar is filled to the maximum, this can correspond to a case when the diameter of the contact glass reflection (D _CGR ) corresponds to that of the contact glass (D _CG ) to which the light source is attached (D _CGR = D _CG ). The light source can be designed as a ring lighting that surrounds the contact glass. The height of the bar's fill level, H _Bar , can then result from the following ratio: $$H_{\text{bar}}=\frac{D_{\text{CGR}}}{D_{\text{CG}}}$$

The method and the laser system can be designed in such a way that a graphic indicator in the form of a bar display indicates an absolute distance between the contact lens and the patient's eye. The calculation of the absolute distance is particularly advantageous for automated docking and can optionally be derived analytically based on considerations for imaging on a concave mirror. For this purpose, the curvature of the cornea is taken into account, which can be described with the Rcv (Radius of Curvature).

mit $$g=-\frac{R_{CV}}{2}$$

wobei die Parameter folgendes angeben:

• z: Abstand zwischen Kontaktglas und Auge
• D_CGR: Durchmesser der Reflexion des Kontaktglases in den Bilddaten
• D_CG: Durchmesser des Kontaktglases
• Rcv: Krümmungsradius der Hornhaut

The Rcv (Radius of Curvature) of the cornea can be determined by averaging two corneal radii of curvature, which belong to the two corneal meridians that are determined as part of a refractive planning of the procedure. The functional connection z(D _CGR ) then results as follows: $$\mathrm{e.g}\left(D_{CGR}\right)=\frac{R_{Cv}}{2}\frac{D_{CG}}{D_{CGR}}+G=\frac{R_{Cv}}{2}\left(\frac{D_{CG}}{D_{CGR}}-1\right)$$

with $$G=-\frac{R_{Cv}}{2}$$

where the parameters specify the following:

• z: Distance between contact lens and eye
• D _CGR : Diameter of the reflection of the contact glass in the image data
• D _CG : diameter of the contact glass
• Rcv: radius of curvature of the cornea

Since the diameter of the illumination ring, which largely generates the contact glass reflection, depends on the radius of the contact glass, different z(D _CGR ) functions can result for different contact glass diameters (e.g. size S, M, L), which can be stored separately in the laser system and through manual or automatic selection can be used.

The relationship between the diameter of the reflection of the contact glass in the image information and the distance of the contact glass 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(D _CGR ) can be determined by calibration on a human model eye. For this purpose, several value pairs/support points z _i (D _(CGR,i) ) are measured using service software and preferably stored in a look-up table.

The relationship z(DCGR) can then be determined by interpolating the value pairs z _i (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 context z(D _CGR ), with the optimization parameters (a, b) $$\mathrm{e.g}\left(D_{CGR}\right)=a\frac{R_{Cv}}{2}\frac{D_{CG}}{D_{CGR}}+bG$$

Optionally, different test eyes with different Rcv, optionally with different moistening of the cornea (e.g. with water) and optionally with different room brightnesses for determining the value pairs are used for the calibration. This can be advantageous because the scattering of the back-reflected light from the cornea, and thus the precision of the determination of D _CGR , can depend on the moisture state of the eye and also on the Rcv.

The contrast sharpness with which D _CGR can be detected can also depend on the brightness in the treatment room. The measurement results can therefore depend on which lighting situation prevails on the laser system. This can depend, for example, on the (averaged) brightness in lumens at the location of the contact glass or at the location of the laser system and/or on the type of light sources. For this reason, there can be a large number of D _(CGR,i) values for each set distance z _i , which can be recorded at different humidity levels, corneal radii of curvature Rcv and/or brightness levels in the room.

All recorded data points can then optionally be used to determine the function z(D _CGR ). Alternatively, separate z(D _CGR ) corresponding functions can also be determined for one, some or all of the humidity level, Rcv and/or brightness level factors.

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

Furthermore, a method for automated docking can involve an acceptance criterion, which can be used to assess whether carrying out the automated method is advisable or not.

Based on an inhomogeneity of the reflection of the contact glass from the surface of the patient's eye during docking, it can optionally be decided whether the reflection can be used to determine the D _CGR or not. A radial intensity distribution I(r) can be used as a decision criterion, which can be approximated by a normal distribution at one or more angular positions Phi. Based on a width (FWHM or sigma) and/or a tail (area that is far from the central value of the normal distribution) of the normal distribution, it can be decided whether the contact glass reflex can be used to determine the D _CGR , ie whether a signal quality is considered sufficient is used for determining the distance and speed or not. If sufficient signal quality is not determined, the eye can optionally be re-moistened and/or the room brightness can be changed to improve the signal quality.

Further background information about an optional functional relationship between a diameter of the contact glass and the distance of the contact glass from the patient's eye and the speed to be selected is explained below.

A maximum speed can be specified for the speed at which the contact glass is approached to the patient's eye, particularly in the case of automated docking but optionally also in the case of manual docking. This may be done for safety reasons to avoid impact and 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.

The speed can be selected in two stages, meaning that two different speeds are specified, from which one speed is selected at any time. The speed of the contact lens relative to the patient's eye along the optical axis of the contact lens, which is referred to as v(z), can optionally be regulated differently in two time intervals. The first time interval can relate to a first approach phase in which the distance is greater than a predetermined threshold value z _T , i.e. z > z _T. The second time interval relates to a second approach phase in which the distance is smaller than the threshold value, i.e. z ≤ z _T (T for threshold). The threshold value z _T can optionally be 3 mm.

In a first approach phase, the speed can be reduced as the distance z(D _CGR ) decreases, whereby z(D _CGR ) was determined purely analytically and/or based on a calibration. Reducing the speed can be advantageous from a safety perspective in order to reduce the risk of a collision between the patient's eye and the contact lens. However, it can be disadvantageous if the speed is reduced too much, as in this case the docking process takes longer than necessary and the treatment time is extended accordingly. For this reason, the speed can optionally be reduced to a minimum value (plateau), which can be selected so that safe and rapid docking is ensured in the second docking phase.

The functional connection can then result from: $$v\left(\mathrm{e.g}\right)=\begin{array}{cc}a{\mathrm{e.g}}^b\frac{\text{mm}}{s},& \mathrm{e.g}>{\mathrm{e.g}}_T\\ \text{c}\frac{\text{mm}}{\text{s}},& \mathrm{e.g}\le {\mathrm{e.g}}_T\end{array}$$

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 decentration compensation.

For the precise determination of the D _CGR and thus the distance (z), the correct centering of the optical axis of the laser with respect to the eye can be advantageous. When decentering, an optional approximation of a round contact glass reflection as a circle can result in a loss of accuracy, as elliptical distortions can occur (see 10A and 10B in the publication WO 2021/239605 A1 ). To measure the decentering, an inherently round contact glass reflection can be approximated as an ellipse and the degree of decentering can be measured using an eccentricity ε. The scanners of the laser of the laser system can then be adjusted in xy in such a way that the eccentricity falls below a predetermined limit value, for example 0.1. During a decentering compensation process, the speed v(z) can optionally be reduced or set to less than or equal to zero (v(z)≤0) to avoid a collision with the patient's eye.

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

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.

A decentering compensation can optionally be carried out fully automatically and at least partially in parallel with the change in speed v(z) and can be achieved by adjusting the scanner of the laser system in xy. In a phase of decentering compensation, v(z) can optionally be automatically reduced or v(z) < 0 can be set. To determine the treatment center, the pupil can be used, especially for small distances z, since it can then be seen clearly and the contact glass reflex optionally disappears from the captured image or the image information.

The docking further includes a contact phase in which mechanical contact is established between the contact lens and the patient's eye. In case of contact, the speed v(z) = 0 is optionally set, whereby contact feedback can be output by force sensors on the contact glass. In addition, the water miniscus (tear film) of the patient's eye, which spreads upon contact between the edge of the contact lens 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 miniscus spreads symmetrically from the vertex; If this is not the case, the speed v(z) < 0 can be set to less than zero, ie the contact lens can be removed from the eye, or reduced to a value v(z) ≥ 0 and a new contact attempt can be made. The contact glass can be mounted in the applicator or in the laser system 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. During this yielding, the contact glass 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 glass on this distance. If this distance s exceeds a limit value s _T , a signal can optionally be triggered by an optionally installed light barrier or a sensor, and the speed v(z) <0 is set to less than zero, so that the contact lens moves away from the eye and to a z position 0 ≥ z > s _T.

For the method according to the disclosure it is not necessary to provide an annular light pattern. Rather, the reflection of the contact glass can also be used without a light pattern. 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 light patterns will be discussed below as an example.

A diameter is determined for one, some or more of the Placido rings irradiated as light patterns. This should be designated as an example of the i-th Placido ring with the index i. A diameter D _CGR,i is determined and a distance z _i (D _CGR,i ) 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 a determination of the speed v(z) if several different distances are determined. $$\mathrm{e.g}\left(D_{CGR}\right)=\text{min}\left({\mathrm{e.g}}_i(D_{CGR,i}\right)$$

To determine decentration, the eccentricity ε of several Placido rings can be used (with ellipse approximation). The Placido rings can also be used to precisely determine the corneal radius of curvature 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(D _CGR ).

der Mittelpunkte der reflektierten Punkte umfassen. Zudem kann ein Vergleich mit bekannten Positionen ${\overrightarrow{y}}_i$

der Mittelpunkte einer Punkt-Lichtquellen am Kontaktglas erfolgen. Außerdem kann das Verfahren ein Berechnen eines summierten Abstands aller n-Punktepaare umfassen: $$s={\displaystyle \sum _i^n\left(\left|{\overrightarrow{x}}_i-{\overrightarrow{y}}_i\right|\right)}$$

An optional example will be discussed below in which a dot pattern is used as a light pattern. The method for determining the distance can involve calculating some or all positions ${\overrightarrow{x}}_i\left(\mathrm{e.g}\right)$

the centers of the reflected points. In addition, a comparison with known positions can be made ${\overrightarrow{y}}_i$

the centers of a point light source on the contact glass. Additionally, the method may include calculating a summed distance of all n-point pairs: $$s={\displaystyle \sum _i^n\left(\left|{\overrightarrow{x}}_i-{\overrightarrow{y}}_i\right|\right)}$$

In addition, the method can include determining a maximum summed distance s _max at a large distance, for example for a distance of z = 5cm. The bar display of the graphical indicator then results in: $$H_{\text{bar}}=s_{\text{Max}}-s$$

The features and embodiments mentioned above and explained below are not only to be viewed as disclosed in the combinations explicitly mentioned in each case, but are also included in the disclosure content in other technically sensible combinations and embodiments.

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

• 1A und 1B eine schematische Darstellung eines refraktiven chirurgischen Lasersystems gemäß optionalen Ausführungsformen;
• 2 eine schematische Skizze der relativen Anordnung des Kontaktglases zum Patientenauge;
• 3 - 6 Diagramme von Verfahren gemäß optionalen Ausführungsformen;
• 7A und 7B Bildinformationen und ausgegebene Informationen für den Benutzer gemäß einer optionalen Ausführungsform.

Show it:

• 1A and 1B a schematic representation of a refractive surgical laser system according to optional embodiments;
• 2 a schematic sketch of the relative arrangement of the contact lens to the patient's eye;
• 3 - 6 Diagrams of methods according to optional embodiments;
• 7A and 7B Image information and output information to the user according to an optional embodiment.

In the following figures, the same or similar elements in the various embodiments are designated with the same reference numerals for the sake of simplicity.

1A shows a schematic representation of a refractive surgical laser system 10 for carrying out refractive surgical treatments of a patient's eye 12 of a patient 14 according to an optional embodiment.

The laser system 10 has a contact glass 16, by means of which the laser system 10 is coupled to the patient's eye 12. For this purpose, the patient 14 is arranged lying on a couch 15 so that his gaze is directed upwards and the laser system 10 can contact and fix the patient's eye 12 vertically from above by means of the contact glass 16.

In addition, the laser system 10 has a femtosecond laser 17, which is integrated into the laser system 10. The laser beam provided by the femtosecond laser 17 is used for the refractive surgical treatment of the patient's eye 12 of the patient 14 and can be applied to the eye 12 through the contact glass 16. According to other optional embodiments, the laser system 10 may 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.

Furthermore, the laser system 10 has a display element 18, by means of which the user of the laser system 10 or the doctor is 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 glass 16 via a reflection on the surface of the eye 12 can be displayed. The image of the patient's eye 12 to be displayed is carried out through the contact glass 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 doctor 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.

The laser system 10 is designed in such a way that a relative movement of the patient 14 to the contact glass and/or to the laser system 10 can be brought about. For this purpose, the laser system 10 can have a positioning unit 21, for example. The relative movement can include a lateral relative movement, ie perpendicular to the optical axis of the contact glass 16, in order to assume a suitable positioning of the contact glass 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 glass, by the distance between contact glass 16 and eye 12 to change and in particular to fix the contact glass 16 on the eye 12 and to detach it from the eye 12. Alternatively or additionally, the patient can be moved vertically using the couch 15.

In addition, the laser system 10 has an image capture unit 20, which is set up to capture image information of an optical reflection of the contact glass 16 from a surface of the patient's eye through the contact glass 16. In addition, the laser system 10 has a control unit 19, which is set up 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 specific 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 capture unit 20, so that the image information received from the image capture unit 20 can be transmitted to the control unit 19.

The laser system 10 is also set up to repeatedly determine the distance and, optionally, to repeatedly determine a speed of the contact lens 16 relative to the patient's eye 12.

In addition, the laser system 10 is set up to output information regarding the determined distance to a user of the laser system by means of the display element 18. For this purpose, the display element can be designed as a computer display or include one. Alternatively or additionally, the display element 18 can have one or more loudspeakers in order to output the information regarding the distance to the user as an acoustic signal.

The laser system 10 also has a positioning unit for positioning the contact glass 16 along the optical axis of the contact glass 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, the laser system 10 also being set up to automatically approach the contact glass 16 to the patient's eye 12 and to position the contact glass 16 by means of the repeatedly determined distance and/or the repeatedly determined speed Positioning unit to regulate. This makes the laser system 10 capable of automatically moving the contact glass 16 along the optical axis of the contact glass 16 and docking it onto the patient's eye 12.

The contact glass 16 also has 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 all around the lower edge of the contact glass, so that the light source provides an annular light pattern. The light source is firmly connected to the contact glass or forms part of it. Thus, when the contact glass 16 is moved, the light source 22 also moves at the same time. The lateral extent of the light source 16 has a fixed ratio to the lateral extent of the contact glass 16. According to various embodiments, the light pattern can optionally have 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.

1B shows a refractive surgical laser system 10 according to a further optional embodiment. This differs in particular from that in 1A shown embodiment, that it has a pivoting device 24, by means of which one of several pivot arms 26 can be positioned to examine and / or treat the patient's eye 12. The unit of the refractive surgical laser system 10 which is used for the refractive surgical treatment of the patient's eye 12 and which has the contact glass 16 for docking with the patient's eye 12 is arranged on one of the pivot arms 26. A surgical microscope 28 is arranged on the other swivel arm 26, which can be swiveled towards the patient's eye 12 in order to examine the patient's eye 12. This can be done when the other pivot arm is pivoted away from the patient's eye. In addition, according to this embodiment, the bed 15 is designed separately from the laser system 10 and can be designed to be positionable in order to carry out or support a 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 glass 16 relative to the patient's eye 12.

2 shows schematically a relative arrangement of a contact glass 16 of a laser system 10 and a patient's eye 12. The underside 16a of the contact glass 16, which faces the patient's eye, is curved in order to be able to make the largest possible contact with the cornea 12a of the eye 12. In the illustration shown, the contact glass is arranged at a distance from the patient's eye 12 along the optical axis 1000 of the contact glass. The distance is shown as 1002 and denotes the distance between the underside 16a of the contact glass 16 on the optical axis 1000 with the intersection of the cornea 12a with the optical axis 1000. Arrow 1004 indicates the possible direction of movement for increasing and reducing the distance 1002 along the optical axis 1000, which is referred to as up and down.

Regarding 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 includes, in step 302, acquiring image information of an optical reflection of the contact glass 16 from a surface of the patient's eye 12 through the contact glass 16.

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

Step 306 of the method 300 includes 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.

4 shows a schematic diagram of a method 400 for determining a speed of a contact lens 16 relative to a patient's eye 12. In a first step 402, the method 400 includes determining a distance 1002 between the contact lens 16 and the patient's eye 12 by means of a method 300, as with reference to 3 described, at a first point in time and at a second point in time.

In a step 404, the method 400 includes determining a time period between the first point in time and the second point in time.

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

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.

The method 500 includes, 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 referred to 3 described.

The method 500 further includes, in step 504, outputting information regarding the determined distance 1002 to a user of the laser system 10. Outputting the information regarding the determined distance 1002 to the user can include displaying a graphic indicator by means of the display element 18, where the graphic indicator allows the user to read and/or estimate the distance 1002. The graphic indicator 24 (see 8th ) can have a bar display with a variable fill level, the fill level of the bar display indicating the determined distance between the contact glass 16 and the patient's eye 12 along the optical axis 1000 of the contact glass 16.

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.

The method 600 includes, 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 3 described.

Alternatively or additionally, the method 600 includes, in a step 604, a repeated determination of a speed of the contact lens 16 relative to the patient's eye 12 by means of a method as referred to 4 described.

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.

In step 608, the method 600 includes controlling 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.

Accordingly, there is the possibility of using image information captured by a contact glass 16 of 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 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.

The control unit 16 can be set up to control a refractive surgical laser system 10 with a contact glass 16 to carry out one of the methods mentioned above.

The 7A and 7B show two exemplary reproductions of image information 700 and 702, which contain an optical reflection of the underside 16a of the contact glass 16 from the cornea 12a of the patient's eye 12, which was transmitted through the contact glass and captured by the image capture unit 20. The displayed reproductions of the image information 700 and 702 can, for example, be output to the user using 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.

The two image information items 700 and 702 differ in that they were recorded at different distances of the contact glass 16 from the patient's eye 12. The image information 700 in 7A was recorded at a greater distance between the contact glass 16 and the patient's eye 12 than the image information 702.

The image information 700 and 702 contain information about the light waves transmitted through the contact glass 16. Accordingly, the central pupil and surrounding parts of the iris of the patient's eye 12 can be seen in the background. It can be seen that a focused image of the cornea or iris is not necessarily required to carry out the procedure. Furthermore, the reflection of a light pattern 706 can be seen in the image information as a bright ring, which is annular and is provided on the contact glass 16 by the annular light source 22. If the contact glass 16 is at a greater distance from the patient's eye 12 (image information 700 and 7A) the reflection of the light pattern 706 and the contact glass 16 in the image information 700 is smaller than at a smaller distance (image information 702, 7B) .

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 match between the reflection of the contact glass 16 or 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, which identifies the determined lateral extent of the contact glass 16 in the image information.

In addition, they show 7A and 7B In addition to the reproduction of the image information, there is also a graphic indicator 710, which indicates the distance of the contact glass 16 from the patient's eye 12. The graphic indicator 710 is designed as a bar display, with the “filling 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 filling height of the bar, the greater the distance determined. Therefore, approximately in 7A Due to the larger distance 1002, the filling height of the bar is greater than in 7B at a small distance 1002. The graphical 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.

Reference symbol list

10

refractive surgical laser system

12

patient eye

12a

cornea

14

patient

15

Lounger

16

Contact glass

16a

Bottom of the contact glass

17

Femtosecond laser

18

Display element

19

Control unit

20

Image capture unit

21

Positioning unit

22

light source

24

Swivel device

26

Swing arm

28

Operating microscope

300, 400, 500, 600

Proceedings

302 - 608

Procedural steps

700, 702

Image information

706

Light pattern

708

lateral extent of the reflection of the contact glass

710

graphic indicator

1000

optical axis of the contact glass

1002

Distance between contact lens and patient's eye

1004

z direction

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2021/239605 A1 [0002, 0060, 0061]
• EP 3313265 A1 [0004]
• WO 2022/078998 A1 [0004]

Claims (16)

Method (300) for determining a distance (1002) between a contact lens (16) and a patient's eye (12), the method (300) comprising the steps: - Detecting (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 specific lateral extent of the optical reflection of the contact glass (16) in the image information (700) . Procedure (300) according to Claim 1 , wherein the contact glass (16) has a light source (22) and is designed 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) includes determining the lateral extent of the light pattern (706) in the image information (700). Procedure (300) according to Claim 2 , wherein a lateral extent of the light source (22) has a fixed ratio to the lateral extent of the contact glass (16) and wherein the light pattern (706) optionally has a ring and/or a polygon and/or a grid. Procedure (300) according to Claim 2 , wherein the light pattern (706) is provided in the spectral range of visible light and / or in the range of infrared light. 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 point in time and the second point in 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. Method (500) for preparing a refractive surgical treatment of a patient's eye (12) by means of 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 until 4 ; - Outputting (504) information regarding the determined distance (1002) to a user of the laser system (10). Procedure (500) according to Claim 6 , wherein outputting the information regarding the determined distance (1002) to the user includes displaying a graphic indicator (710) by means of a display element (18), wherein the graphic indicator (710) allows the user to read and/or estimate the distance ( 1002). Procedure (500) according to Claim 7 , wherein the graphic indicator (710) has a bar display with a variable fill level, the fill level of the bar display indicating the determined distance (1002) between the contact lens (16) and the patient's eye (12) along the optical axis of the contact lens (16). 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 glass (16) by means of a method (300) according to one of Claims 1 until 4 ; 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). Claim 5 ; - Approaching (606) the contact glass (16) to the patient's eye (12) along the optical axis (1000) of the contact glass (16); and - regulating (608) the distance (1002) between the contact lens (16) and the patient's eye (12) and/or regulating the speed of the contact lens (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). Use of image information (700) captured through 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). Control unit (19), which is set up 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. Refractive surgical laser system (10) with a contact lens (16), the laser system (10) comprising: - an image capture unit (20) which is set up to capture 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 set up 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 - 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 specific lateral extent of the optical reflection of the contact glass (16) in the image information (700). determine. Refractive surgical laser system (10) according to Claim 12 , wherein the laser system (10) is set up to repeatedly determine the distance (1002) and optionally to repeatedly determine a speed of the contact glass (16) relative to the patient's eye (12). Refractive surgical laser system (10) according to Claim 13 , further comprising a display element (18), wherein the laser system (10) is set up to output information regarding the determined distance (1002) to a user of the laser system (10) by means of the display element (18). Refractive surgical laser system (10) according to Claim 13 or 14 , further comprising a positioning unit (21) for positioning the contact glass (16) along the optical axis (1000) of the contact glass (16), the laser system (10) being further configured to position the contact glass (16) by means of the positioning unit (21). to automatically approach the patient's eye (12) and to regulate a positioning of the contact lens (12) by the positioning unit (21) based on the repeatedly determined distance (1002) and/or the repeatedly determined speed. Refractive surgical laser system (10) according to Claim 15 , wherein the laser system (10) is also set up to automatically dock the contact glass (16) to the patient's eye (12).

Images