Custom ablation for correcting refractive errors in vision

Abstract

The present invention relates to an apparatus, a computer program and a method for correcting refractive errors of vision. In a first example, a position (480) of a desired focus point (440) relative to the retina of an eye can be determined based on topographic information obtained about the anterior corneal surface (401) and the posterior corneal surface (402) and refractive aberration information of an individual eye. In a second example, correction information (416, 496) related to the anterior corneal surface (401) can be determined based on the topographic information obtained about the anterior corneal surface (401) and the posterior corneal surface (402) and based on topographic information obtained about the anterior lens surface (431) and the posterior lens surface (432) of the individual eye to optimize focusing on the retina of the eye.

Description

Technical Field

[0001] The present invention relates to customized ablation for correcting visual refractive errors, and in particular to the determination of a customized volume of corneal tissue to be ablated, corresponding apparatus, and computer program. Background Art

[0002] Corneal refractive surgery has evolved significantly over the past two decades, resulting in customized ablations where the ablation profile is adapted to the specific needs of each patient to correct their visual ametropia.

[0003] When treating the cornea to correct ametropia, the refractive error (e.g., refractive aberration information) is typically determined first. In conventional techniques, the corneal refractive index is then used to calculate the volume of tissue equivalent to the lens required to correct the refractive aberration information and correct the patient's vision. The cornea is then treated by laser ablation of the lens to correct the calculated ametropia.

[0004] In more recent prior art, several different methods have been introduced to determine the target profile of the anterior corneal surface, rather than calculating the volume of tissue equivalent to the lens required to correct the refractive aberration information. In one example, the target profile of the anterior corneal surface can be determined subjectively by the treating physician, that is, the treating physician can determine the target profile based on his or her clinical experience so that it meets clinical requirements. WO 98 / 42291 relates to such a method. Based on the available resolution, a set of points on the cornea and the position of each point are determined. Then, a computer determines the distance between the actual surface of the cornea and a predetermined reference surface for each point in the determined set of points. The predetermined reference surface can be determined based on clinical experience and / or alternative methods. The determined distance then defines the profile for corneal tissue ablation.

[0005] In another example, refractive correction values ​​can be determined for various points on the patient's cornea. These refractive correction values ​​can be determined by searching for diopter values ​​that optimize the focusing of light rays impinging on the cornea, generated by a light source arranged at an infinite distance, at the level of the fovea (EP 1 352 623). This set of refractive correction values ​​then defines a profile for corneal tissue ablation.

[0006] For other prior art, reference may be made to US 2015 / 131054 A1 and WO 2019 / 202104 A1.

[0007] However, known methods only take into account the structure of the individual eye to a limited extent. Accordingly, current methods for determining the corneal target contour are not always optimal in terms of improving visual quality. More importantly, current methods may result in the removal of corneal tissue that may be (significantly) higher than necessary.

[0008] Therefore, there is a need for improved determination of corneal target contours so that corneal tissue ablation can be minimized and / or visual quality can be further improved. Summary of the Invention

[0009] A first embodiment of the present invention relates to an apparatus for correcting refractive errors. The apparatus includes means for obtaining topographic information of the anterior corneal surface and the posterior corneal surface of an individual's eye. The apparatus further includes means for obtaining distance information of the retina of the eye relative to the anterior corneal surface of the individual's eye. The apparatus further includes means for determining the position of a desired focus point relative to the retina based on the topographic information of the anterior and posterior corneal surfaces and information about refractive aberrations of the eye.

[0010] The basic idea behind the present invention is that a major limitation of prior art methods is that these methods only consider the individual structures of the eye to a limited extent. Therefore, correcting refractive errors based on data that only considers individual eye information in a limited way is suboptimal. However, obtaining more individual eye data requires that this data be obtained reliably, which is not always the case in the prior art.

[0011] According to this embodiment, based on the refractive aberration information of the individual eye (e.g., measured information, such as in a vision test performed by an ophthalmologist, or in a wavefront analyzer, or in a scanning laser refraction measurement) and taking into account the topographic information (e.g., measured information) about the anterior corneal surface and the posterior corneal surface of the individual eye, a desired focus point is determined, i.e., the point on which the eye should focus to optimize vision. In a subsequent step, this desired focus point can then be used to determine the modifications that need to be made to the anterior corneal surface to optimize vision in the individual eye.

[0012] Especially when dealing with complex cases such as irregular astigmatism or ectasia, the eye's posterior corneal surface may have associated irregularities. Corrections calculated solely based on the anterior corneal surface may not be satisfactory because, despite the applied correction, the (ignored) irregular posterior corneal shape may result in uncompensated refractive aberrations. Therefore, correcting visual ametropia based solely on topographic information of the anterior corneal surface may not be optimal. Because in real eyes, refraction occurs not only at the anterior corneal surface but also at the posterior corneal surface (due to the transition from the eye's denser corneal stroma to the eye's less dense aqueous humor), considering the patient-specific posterior corneal surface (e.g., including information about the distance of the posterior corneal surface relative to the anterior corneal surface) can allow for better determination of correction information. This is particularly true because the posterior corneal surface can vary significantly from patient to patient and may have an irregular shape (which can often be described not only by linear or quadratic functions, but also by higher-order functions, such as third-order and higher-order functions, such as polynomials, which may not have a shape that can be approximated by a sphere or ellipse, etc.).

[0013] However, the inventors of the present invention have recognized that the refractive error information and the topographic information of the corneal surface may not always be completely accurate, and / or that each patient may have, for example, an irregularly shaped lens, so that the above-described steps for determining the desired focus point do not always accurately determine the desired focus point. It is indeed crucial to reliably obtain the contribution of, for example, the posterior corneal surface for each patient, just as the refractive aberration information.

[0014] Therefore, according to this embodiment, the means for obtaining information about the distance of the retina of an eye relative to the anterior corneal surface of an individual's eye and determining the position of the desired focus point relative to the retina allows for providing a reliability measure. Consequently, more accurate data about an individual's eye may be needed for refractive error correction. Determining a reliability measure (e.g., the distance of the desired focus point relative to the retina) based on topographic information of the anterior and posterior corneal surfaces and refractive aberration information allows for verification of the reliability of the obtained data.

[0015] The topographic information of the corneal surface (e.g., the anterior and / or posterior surfaces) can include a profile (e.g., a plurality of coordinates defining one or more actual points on the corneal surface, a plurality of points approximating the corneal surface, or a function fitted to the corneal surface, etc.). The topographic information can be provided, for example, in the form of a plurality of points in an xyz coordinate system. Of course, other coordinate systems can be used. Corrective information can then be determined based on the topographic information of the anterior and posterior corneal surfaces and the desired focal point.

[0016] It should be noted that the above-described apparatus may not necessarily include means for determining or calculating topographic information and / or a desired focal point. The obtaining means may be implemented by means for receiving corresponding information from another device or an apparatus operator. In such instances, the apparatus may directly use the received information to determine the correction information and / or the desired focal point, and / or the apparatus may further process the received information. For example, topographic information and / or the desired focal point associated with the patient may be retrieved from a memory, a database, a server in the cloud, and / or from a corresponding diagnostic apparatus, or such topographic information and / or the desired focal point may be simply input by an apparatus operator, such as a surgeon.

[0017] The refractive aberration information may comprise the subjective refraction of the eye (e.g. one or more spherical diopter values ​​and / or one or more cylindrical diopter values ​​and one or more cylindrical axes), such as may be obtained by a typical vision test. Thus, in some instances, the refractive aberration information comprises or consists of the subjective refraction. Additionally or alternatively, the apparatus may comprise means for obtaining the refractive aberration information of the eye from a scanning laser refraction meter (e.g. as disclosed in EP 1 459 676) and / or a wavefront analyser or similar device. For example, the refractive aberration information may comprise one or more parameters, such as polynomial coefficients, which may be obtained from a wavefront analyser. The scanning laser refraction meter and / or the wavefront analyser may, for example, be adapted to provide the refractive aberration information in the form of a refractive error map, such as for a selected area on the anterior surface of the cornea, as explained. For example, the refractive error may be expressed as a refractive value, as coefficients of one or more polynomials, such as Zernike polynomials, or the like. The device may include a scanning laser refraction meter and / or a wavefront analyzer, or may simply import refractive aberration information from the laser refraction meter and / or wavefront analyzer via any medium. The refractive aberration information may also be obtained, for example, by an operator of the device, who may input this information, for example, via an interface. Additionally or alternatively, the refractive aberration information may be obtained from a storage medium.

[0018] In some examples, the means for determining the position of the desired focal point can be further adapted to determine the position based on a lens model estimating the lens of the eye (e.g., a statistical lens model that can describe average lens parameters, for example, based on data measured for a large number of eyes). Thus, when determining the desired focal point, the (estimated) contribution of the lens to refraction within the eye can also be taken into account. As described, by determining the desired focal point relative to the retina, the reliability of the lens model and / or the refractive aberration information can be analyzed. Based on the distance information measured for the individual eye, it can be verified whether the desired focal point is indeed located on or near the retina. For example, if the distance of the desired focal point relative to the (measured) retina (i.e., the reliability measure) is above a threshold, e.g., above 500 μm, more preferably above 300 μm, and most preferably above 100 μm, then the available data for the individual eye (e.g., the refractive aberration information and / or the lens model estimating the lens of the eye) can be determined to be erroneous.

[0019] If the deviation is too large, eg, greater than the aforementioned threshold, it may be determined, for example, that the patient's lens does not conform to the lens model (and / or the refractive aberration information and / or topographic information regarding the anterior and / or posterior corneal surfaces is inaccurate).

[0020] The lens model of the eye may, for example, include a lens contour (e.g., an anterior lens contour and / or a posterior lens contour). The lens contour may include a plurality of coordinates defining one or more actual points on the anterior lens surface and / or the posterior lens surface, a plurality of points approximating the anterior lens surface and / or the posterior lens surface, or a function fitted to the anterior lens surface and / or the posterior lens surface, similar to that described above with respect to the topographic information of the corneal surface. The lens contour may additionally or alternatively include distance information, such as the distance of the anterior and / or posterior surfaces of the lens model relative to the anterior corneal surface (e.g., statistical distance information that may describe the average distance of the anterior and / or posterior surfaces of the lens model from the anterior corneal surface, for example, based on data measured for a large number of eyes).

[0021] In some examples, the parameters of the lens model can be adapted to the individual eye. For example, the parameters can be adjusted based on information about the distance of the retina relative to the anterior corneal surface. However, the parameters of the lens model may not include any measured parameters. Additionally or alternatively, they may or may not be obtained using wavefront measurements and / or using fitting to wavefront measurements.

[0022] In some instances, the device may further include means for obtaining distance information. The distance information may include the distance of the front surface of the lens of the eye relative to the front surface of the cornea of ​​the individual eye, and / or the distance of the back surface of the lens relative to the front surface of the cornea of ​​the individual eye (e.g., information measured for the individual eye). The distance information obtained may be used to place a lens model that models the lens of the eye based on the distance information (e.g., via the front surface and / or the back surface of the lens). Thereby, the reliability measure, i.e., the distance of the desired focus point relative to the retina, may be further improved, thereby allowing a more accurate determination of whether the available individual eye data is accurate. This in turn allows for a more personalized correction of refractive errors when the available individual eye data is used for correction of refractive errors.

[0023] In some examples, the means for determining the position of the desired focal point relative to the retina can be further adapted to base the determination on a lens contour of a lens model that models the lens of the eye. Thus, to determine the distance of the desired focal point relative to the retina, not only topographic information of the anterior and posterior corneal surfaces but also the model of the lens contour of the lens of the eye is taken into account. This results in a more improved reliability measure, thereby producing more reliable results, such as regarding whether the acquired data for an individual eye is accurate.

[0024] In some examples, the device may be adapted to issue a warning if the position of the desired focus point relative to the retina exceeds a predetermined threshold, thereby alerting the device operator that the available data may be erroneous and allowing the operator to reconsider the data before using it to correct a visual ametropia.

[0025] In some examples, the means for obtaining a desired focal point can be further adapted to determine the desired focal point by ray tracing at least one light ray refracted by the optical means according to topographic information of the anterior and posterior corneal surfaces (possibly including distance information of the posterior surface relative to the anterior surface) and according to correction of the refractive aberration information of the eye. As known to those skilled in the art, the refraction at the interface between two materials (e.g., air and corneal tissue, corneal tissue and aqueous humor, aqueous humor and lens, lens and vitreous humor, etc.) can be calculated, for example, based on Snell's law and the refractive indices of the materials. Thus, based on topographic information (e.g., contour) of the corneal surface (possibly including distance information) and the refractive indices of the relevant materials (known to those skilled in the art), the refraction of light rays passing through the anterior and posterior corneal surfaces, and possibly also through the anterior and posterior lens surfaces, can be calculated.

[0026] Using the ray tracing mentioned in the previous paragraph, the available eye data can be verified by tracing one or more light rays. The light rays can be incident on an optical component (e.g., a lens) that corresponds to the correction of the refractive aberration information of the eye in a manner parallel to the optical axis of the eye. Before the light rays intersect the optical axis in the eye, they are refracted by the optical component, the anterior and posterior corneal surfaces, and possibly also a lens model (which may be positioned according to distance information and may also be described by the contours of the anterior and / or posterior surfaces). The point of intersection of the light rays with the optical axis in the eye (e.g., its center of gravity) can define a desired focal point, from which the distance relative to the retina can be determined.

[0027] In some examples, an area within a specific radius around the corneal vertex (or the center of the anterior corneal surface) can be considered for ray tracing. For example, an area on the anterior surface within a diameter corresponding to the pupil diameter of the eye, detected based on a predefined light environment, preferably but not necessarily obtained by a pupillometer, can be considered. Ray tracing can then be performed for a regular or randomized grid of points within such an area, so that for each point, the position of the desired focal point relative to the retina can be obtained, as described in the previous paragraph. By using an appropriate number of points, an estimate of the desired focal point relative to the retina can be obtained, for example, by calculating the centroid or taking a weighted average of the determined positions.

[0028] In some examples, ray tracing involves impinging at least one first ray on an optical component in a manner parallel to the optical axis of the eye (forward ray tracing). For example, forward ray tracing can be performed for multiple first rays, each of which impinges on a corresponding point of a grid of points within a selected area of ​​the anterior corneal surface, as outlined in the previous paragraphs.

[0029] In the case of forward ray tracing, the position of the desired focal point relative to the retina can be defined as the intersection of at least one first ray with the optical axis of the eye after being refracted by the optical components, the anterior and posterior corneal surfaces, and possibly a lens model (possibly positioned based on distance information and possibly also described by the contours of the anterior and / or posterior surfaces). By making this determination for multiple rays, each of which strikes a point on a grid of points on the anterior surface, the desired focal point can be obtained by taking, for example, a weighted average of the relative distances between the rays' intersections with the optical axis and the retina. Thus, a reliable estimate of the desired focal point can be determined.

[0030] In some examples, in addition to or in lieu of forward ray tracing, ray tracing may also involve emitting at least one second ray from the desired focal point (reverse ray tracing). For example, reverse ray tracing may be performed for a plurality of second rays, each of which exits the optical component after being refracted by an optical component corresponding to the correction of the eye's refractive aberration information (e.g., a lens corresponding to the correction of the refractive aberration information), the posterior corneal surface, the anterior corneal surface, and possibly a lens model (placed according to the distance information and possibly also described by the contours of the anterior and posterior surfaces).

[0031] In the case of reverse ray tracing, a desired focal point can be determined, at least in part (e.g., iteratively) to minimize the angle between the optical axis of the eye and the at least one second ray after the at least one second ray has been refracted by the lens model (placed according to distance information and possibly also described by the contours of the anterior and posterior surfaces), the posterior and anterior corneal surfaces (determined by corresponding topographic information), and the optical component (e.g., simulating a lens corresponding to the correction of the refractive aberration information). For example, the desired focal point can be determined such that the angle between the ray-traced ray exiting the optical component and the optical axis is substantially zero. This can be performed for a set of points on the anterior corneal surface in a manner similar to that described above.

[0032] In some examples, the device may further include means for determining corrective information related to the anterior corneal surface based on topographic information of the anterior corneal surface and the posterior corneal surface to optimize focus at a desired focal point. In some examples, focus may also be optimized based on distance information between the anterior corneal surface and the posterior corneal surface and / or a lens model and / or distance information of the lens model.

[0033] The corrective information can include corrections that need to be applied to the anterior corneal surface, such as to optimally focus light rays that are refracted by the posterior corneal surface after the correction of the anterior corneal surface onto a desired focal point. For example, the corrective information can define corrections in the form of an ablation volume, an ablation profile, and / or a target profile and / or a target slope of the anterior corneal surface. The corrective information can include values ​​associated with various points on the anterior corneal surface, such as a grid of points on the anterior corneal surface. The corrective information can then be used to ablate the corresponding corneal volume.

[0034] In some examples, the corrective information may include a target slope and / or a target profile of the anterior corneal surface. For example, the corrective information may relate to one or more points on the anterior corneal surface (e.g., forming a grid), wherein for each point, a target slope or target thickness may be indicated, e.g., in the form of a map or profile of the target anterior corneal surface. However, the corrective information may also relate to a value to be ablated, such as a target ablation volume and / or a target ablation thickness (for each point). The target ablation value may be obtained by intersecting the topographic information of the anterior corneal surface with, for example, a target profile of the anterior corneal surface that optimizes vision.

[0035] Using the ray tracing mentioned in the previous paragraphs, correction information can be determined, at least in part, to optimize focus at a desired focal point. In other words, the correction that needs to be applied to a particular point on the anterior corneal surface is determined so that light rays passing through that point are optimally focused onto the desired focal point, as calculated based on the (corrected) anterior surface topography and based on topographic information of the posterior corneal surface and possibly based on distance information between the anterior and posterior corneal surfaces and / or a lens model and / or distance information of the lens model.

[0036] In some examples, in a manner similar to that described above, an area within a specific radius around the corneal vertex (or the center of the anterior corneal surface) can be considered for ray tracing. For example, in a manner similar to that described above, an area on the anterior surface within a diameter corresponding to the pupil diameter of the eye, which is detected based on a predefined light environment, preferably but not necessarily obtained by a pupillometer, can be considered. Ray tracing can then be performed for a regular or randomized grid of points within such an area, so that for each point, corresponding correction information can be obtained, such as the target slope of the anterior surface at that point. By using an appropriate number of points, the correction information can be determined in the form of a map of the anterior corneal surface.

[0037] In some examples, ray tracing involves forward ray tracing, wherein at least one first ray is directed onto the anterior corneal surface parallel to the optical axis of the eye. Forward ray tracing can be performed for a plurality of first rays, each first ray being directed onto a corresponding point of a grid of points within a selected region of the anterior corneal surface, as outlined above.

[0038] In the case of forward ray tracing, correction information related to the anterior corneal surface can be determined, at least in part, to optimize focus on a desired focal point, i.e., to bring the point at which the light rays are focused as close as possible to the desired focal point. The point at which the light rays are focused can be defined as the intersection of the light rays with the optical axis of the eye after being refracted by the anterior and posterior corneal surfaces (possibly taking into account distance information between the anterior and posterior corneal surfaces) and, possibly, by a lens model (possibly positioned based on this distance information and possibly also described by the contours of the anterior and posterior surfaces). For example, a target slope of the anterior corneal surface can be determined such that the distance between the desired focal point and the aforementioned intersection point is substantially zero. By performing this determination for multiple light rays, each of which strikes a point on a grid of points on the anterior surface, the necessary correction information to be applied at these points can be determined so that each light ray striking the corresponding point is optimally focused on the desired focal point. Thus, correction information, such as a target slope, can be obtained for the entire grid of points. A target contour of the anterior corneal surface can then be determined, for example, by integrating the determined target slopes.

[0039] In some examples, in addition to or in lieu of forward ray tracing, ray tracing may also involve emitting at least one second ray from a desired focal point (reverse ray tracing), as described above. In a manner similar to that described above, reverse ray tracing may be performed for a plurality of second rays, each of which exits the cornea at a corresponding point of a grid of points within a selected region of the anterior corneal surface after being refracted by the posterior and anterior corneal surfaces (possibly taking into account distance information between the anterior and posterior corneal surfaces) and possibly also by a lens model (possibly positioned based on the distance information and possibly also described by contours of the anterior and posterior surfaces).

[0040] In the case of reverse ray tracing, correction information related to the anterior corneal surface can be determined, at least in part, to minimize the angle between the optical axis of the eye and the at least one second ray as it exits the cornea after being refracted by the lens model (possibly positioned based on distance information and possibly also described by the contours of the anterior and posterior surfaces) and the posterior and anterior corneal surfaces (determined by corresponding topographic information), and possibly taking into account distance information between the anterior and posterior corneal surfaces. For example, correction information can be determined such that the angle between the ray-traced ray exiting the cornea and the optical axis is substantially zero. Similarly, for a grid of points on the anterior corneal surface, the necessary correction information can be determined such that, for each point of the grid, the angle between the ray-traced ray exiting the cornea and the optical axis is substantially zero.

[0041] Another (second) embodiment of the present invention relates to an apparatus for correcting refractive errors of vision. The apparatus includes: means for obtaining topographic information of the anterior corneal surface and the posterior corneal surface of an individual's eye; means for obtaining topographic information of the anterior and / or posterior lens surfaces of the individual's eye; and means for obtaining distance information of the retina of the eye relative to the anterior corneal surface of the individual's eye. The apparatus also includes means for determining, based on the topographic information of the anterior and posterior corneal surfaces and the topographic information of the anterior and posterior lens surfaces, corrective information related to the anterior corneal surface to optimize focus on the retina of the eye.

[0042] It should be noted that the first and second embodiments, and all aspects related to these embodiments described herein, can be combined. For example, a single device implementing both embodiments can be provided. Unless explicitly stated otherwise, aspects described with reference to the first embodiment also apply to the second embodiment, and vice versa.

[0043] Considering the topographic information of the anterior and posterior surfaces of the lens of an individual eye when determining correction information - rather than just the anterior and posterior corneal surfaces of an individual eye - allows for an ablation volume that is better suited to the needs of each patient and improves vision correction because the refractive contribution of the lens can be taken into account.

[0044] As outlined above, the underlying concept of the present invention is that a major limitation of prior art methods is that they only consider the individual structures of the eye to a limited extent. Prior art methods ignore the refractive contribution of the eye's lens, or consider it only to a very limited extent. For example, in the case of an abnormal lens shape, a correction calculated solely based on corneal surface information and / or the regular shape of a general lens model may not be satisfactory because, despite the correction being applied, the (ignored) abnormal shape of the individual lens may lead to refractive aberrations. Therefore, such correction is suboptimal. Taking into account the shape of the cornea and lens of a specific patient allows for better determination of correction information. Consequently, vision correction for each individual patient can be improved. This is particularly true because the corneal and lens surfaces can vary greatly from patient to patient and may have irregular shapes (which can often be described not only by linear or quadratic functions, but also by higher-order functions, such as third-order and higher-order functions, such as polynomials, which may not have a shape that can be approximated by a sphere or ellipse, etc.). Taking into account the specific configuration (morphology or shape) of the cornea and lens of the eye when determining the corrective information that optimizes focus on the retina of the eye allows this problem to be eliminated. Taking into account not only the refractive contribution of the corneal surface but also the refractive contribution of the lens of each patient allows for optimization of the correction and often minimizes the ablation volume necessary for the correction.

[0045] In a manner similar to that already described above, the device may not necessarily include means for determining or calculating topographic information and / or distance information of the retina of the eye. The obtaining means may be implemented by means for receiving corresponding information from other devices or the device operator. In such instances, the device may directly use the received information to determine the correction information and / or the retina, and / or the device may further process the received information. For example, topographic information and / or distance information of the retina of the eye relative to the anterior corneal surface associated with the patient may be retrieved from a memory, a database, a server in the cloud, and / or a corresponding diagnostic device, or such information may simply be input by the device operator, such as a surgeon.

[0046] In one example, topographic information of the anterior and posterior surfaces of the eye's lens can be obtained for near and / or distance vision. As described above, the topographic information of the lens can include a profile. In some examples, this profile can be obtained for distance and / or near vision. This profile may also be obtained for a radius corresponding to the eye's pupil diameter and detected based on a predefined light environment (e.g., for distance vision), or a smaller radius may be considered (e.g., for near vision). In some examples, a radius around the corneal vertex (or the center of the anterior corneal surface) may be considered, preferably obtained by a pupillometer. It is noteworthy that in the case of pupil data detected by a pupillometer, the pupillometer need not be part of the device, but it is sufficient if the device is adapted to receive corresponding pupil data, for example, from a storage device or from a device operator via a corresponding interface. For example, correction information can be determined separately for each zone defined by the region within the eye's pupil radius for near and distance vision. Thus, the corrective information may include corrective information specific to one or more zones for near vision and distance vision.

[0047] In some examples, the means for determining corrective information can be adapted to perform ray tracing on at least one ray that passes through the cornea and is refracted by the anterior and posterior corneal surfaces, and passes through the lens and is refracted by the anterior and posterior lens surfaces, based on topographic information of the anterior and posterior corneal surfaces and topographic information of the anterior and posterior lens surfaces, to optimize focus on the retina. The same considerations as described above with respect to ray tracing apply here as well.

[0048] In some examples, the device may further include means for obtaining distance information of the posterior surface of the cornea relative to the anterior surface of the cornea of ​​the individual's eye and / or the distance of the anterior surface of the lens of the eye relative to the anterior surface of the cornea of ​​the individual's eye and / or the distance of the posterior surface of the lens of the eye relative to the anterior surface of the cornea of ​​the individual's eye. The means for determining corrective information related to the anterior surface of the cornea to optimize the focus on the retina of the eye may be further adapted to base the determination on at least one distance information obtained. Using the obtained distance information in addition to topographic information (e.g., contours) of the corneal surface, the lens surface, and the refractive index of related materials (known to the skilled person) may allow further improvements to, for example, the above-mentioned ray tracing. The distance information may also be used in the ray tracing process outlined in the previous paragraph.

[0049] In one example, the apparatus according to the first and / or second embodiments may be adapted to obtain topographic information of the anterior and posterior corneal surfaces of the cornea from a corneal tomography scanner. The tomography scanner may be based on light scattering technology and / or ultrasound technology, among others. Additionally or alternatively, optical coherence tomography may be used.

[0050] In another example, the device may be further adapted to obtain topographic information of the anterior and posterior lens surfaces, for example from optical coherence tomography or ultrasound.

[0051] In another example, the device may be adapted to obtain information about the distance of the posterior surface of the cornea relative to the anterior surface of the cornea of ​​the individual's eye and / or the distance of the anterior surface of the lens of the eye relative to the anterior surface of the cornea of ​​the individual's eye and / or the distance of the posterior surface of the lens of the eye relative to the anterior surface of the cornea of ​​the individual's eye from a biometer. The biometer may be based on ultrasound technology or optical coherence tomography technology.

[0052] In another example, topographic information of the anterior and posterior corneal surfaces obtained from a corneal tomography scanner and topographic information of the anterior and posterior lens surfaces obtained from an optical coherence tomography scanner can be used for ray tracing as described herein. For example, the correction that needs to be applied to a specific point on the anterior corneal surface (obtained from the corneal tomography scanner) is determined so that the light passing through the point is optimally focused on the retina, as calculated based on the (corrected) anterior surface configuration and based on the topographic information of the posterior surface (obtained from the corneal tomography scanner) and the topographic information of the anterior and posterior lens surfaces (obtained from the optical coherence tomography scanner). In some examples, this can be done without any fitting parameters. In some examples, it may only be possible to use the topographic information of the anterior and posterior corneal surfaces (obtained from the corneal tomography scanner) and the topographic information of the anterior and posterior lens surfaces (obtained from the optical coherence tomography scanner). In some examples, distance information obtained from a biometer (e.g., an optical biometer) can also be used for ray tracing.

[0053] The device may include a tomography scanner. For example, in contrast to a corneal tomography scanner based on a Placido ring, the use of a corneal tomography scanner allows not only the anterior corneal surface properties to be determined, but also properties regarding the thickness of the cornea, in particular properties regarding the posterior corneal surface. For example, a corneal tomography scanner can provide topographic information such as the contours of the anterior corneal surface and the posterior corneal surface. It can also provide information regarding the thickness of the cornea. It can also provide more detailed information regarding the various layers of the cornea, such as the corneal epithelium and / or the corneal stroma. In some instances, as mentioned, topographic information regarding the various layers of the cornea can also be taken into account when determining the correction information, which can allow for more precise determination of the target anterior corneal surface to optimize vision.

[0054] In another example, the device may be adapted to obtain topographic information at least in part from a pupillometer to determine the (photopic) diameter of the pupil of the eye. The device may comprise such a pupillometer. The pupillometer may also be used to define the smallest area of ​​the anterior corneal surface where ametropia can be corrected, the diameter of the area being determined based on a predefined light environment. In some examples, the area may also be determined subjectively and received by the device. Alternatively, the operator may preselect the area of ​​the eye to be treated and then in a next step may refine the preselected area by using the information provided by the pupillometer, for example by using the pupil diameter. Overall, this allows for precisely limiting the area of ​​the cornea to be treated by laser surgery. As a result, the invasiveness of the surgical treatment may be reduced.

[0055] In another example, the device may further include means for correcting eye aberrations based on the determined corrective information, preferably a laser for removing corneal tissue. For example, an excimer laser or a solid-state laser may be used for this purpose. In other examples, the device may be adapted to determine the corrective information so that it can be provided to a laser for removing corneal tissue, but the laser need not necessarily be part of the device.

[0056] In some examples, the device can be adapted to control means for correcting using closed-loop feedback. For example, the device can include means for controlling a laser (or more generally, a corrective means) based on updated topographic information of the anterior corneal surface. During laser ablation, the topographic information of the anterior corneal surface can be updated, for example, in real time, and ablation can be controlled accordingly, for example, in a closed-loop manner. For example, ablation can be stopped if sufficient agreement is achieved between the updated topographic information and corrective information, such as a target contour of the anterior corneal surface, while ablation can be controlled to continue as long as agreement is not reached.

[0057] The device may also be adapted to store the determined correction information, for example on a memory, in a database or on a server.The correction information may then be retrieved by means for correcting eye aberrations, such as a laser, which may be part of the device or may be provided separately.

[0058] In one example, a corneal tomography scanner, an optical coherence tomography scanner, a biometer, a scanning laser refraction instrument and / or a wavefront analyzer, a laser and optionally a pupillometer can be included in the device so that they become part of the device. In such an example, the device can include a processing and / or control unit (e.g., a computer) that interacts with the other mentioned parts of the device. For example, topographic information and / or refractive aberration information can be transmitted to the processing and / or control unit, for example, via one or more wires and / or wirelessly. For example, correction information can be transmitted from the processing and / or control unit to the laser in a similar manner. In another example, the various parts mentioned may not necessarily be part of the device, thereby providing a modular device. In this example, the device (which can still include a processing unit) can be suitable for exchanging topographic information, refractive aberration information and / or correction information, for example, via one or more wires and / or wirelessly. For example, the corresponding information can be transmitted to and from the device wirelessly.

[0059] It should be noted that aspects related to determining a desired focal point relative to the retina can be combined with other aspects of the present invention, but can also be implemented independently of these other aspects. For example, methods and / or apparatus can be provided that involve obtaining topographic information of the anterior corneal surface and topographic information of the posterior corneal surface of an eye. Furthermore, refractive aberration information of the eye can be obtained. The desired focal point can be determined based on the topographic information of the anterior corneal surface and the posterior corneal surface and based on the refractive aberration information, for example, by ray tracing.

[0060] Another embodiment of the present invention relates to a computer program comprising instructions for performing the steps described herein and / or implementing the components described herein. For example, the computer program may be stored on a memory medium and may cause a processor to perform the steps. The memory medium and / or the processor may be included in an apparatus according to the present invention. The apparatus according to the present invention may generally include the computer program according to the present invention.

[0061] Another embodiment of the present invention relates to a method for correcting refractive errors of vision. The method may include the steps of obtaining topographic information of the anterior corneal surface and topographic information of the posterior corneal surface of the eye. The method may further include the step of obtaining a desired focal point within the eye. The method may further include determining corrective information related to the anterior corneal surface based on the topographic information of the anterior corneal surface and the posterior corneal surface to optimize focus on the desired focal point. The method may also optionally include other steps, which are described herein with reference to the apparatus and / or computer program. The method may not include steps for actually correcting eye aberrations based on the determined corrective information. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Possible embodiments of the present invention will be described in more detail in the subsequent detailed description with reference to the following figure:

[0063] Figure 1 : Example flow chart for customized corneal ablation according to an example of the present invention;

[0064] Figure 2a : A schematic illustration of an exemplary corneal cross section including the anterior surface of the cornea of ​​an eye and the anterior surface of the cornea of ​​a target;

[0065] Figure 2b : Top view of example areas of the anterior corneal surface that can be treated surgically, including the monofocal refractive zone and the custom connection zone.

[0066] Figure 2c : A top view of an example area of ​​the cornea to be surgically treated, including a multifocal refractive zone subdivided into near vision, intermediate vision, and distance vision zones, and a customized connection zone surrounding the multifocal zone.

[0067] Figure 3 : Schematic illustration of an exemplary corneal cross-section with a lens cross-section, wherein the corneal cross-section includes the anterior corneal surface, the posterior corneal surface, and the slopes of each point on the anterior corneal surface and the posterior corneal surface, and the lens cross-section includes the anterior lens surface and the posterior lens surface, and the slopes of each point on the anterior lens surface and the posterior lens surface.

[0068] Figure 4a : Example for determining an area of ​​the anterior corneal surface relevant for vision based on topographic information of the anterior corneal surface and the posterior corneal surface and based on a predefined, preferably photopic pupil diameter.

[0069] Figure 4b : An example of determining a desired focus point based on topographic information of the anterior and posterior surfaces of the cornea, topographic information of the anterior and posterior surfaces of a lens model of the lens of an eye, distance information of the posterior surface of the cornea relative to the anterior surface of the cornea, distance information of the anterior surface of the lens model relative to the anterior surface of the cornea, distance information of the posterior surface of the lens model relative to the anterior surface of the cornea, and distance information of the retinal surface relative to the anterior surface of the cornea and based on refractive aberration information.

[0070] Figure 4c : An example for determining an area of ​​the anterior corneal surface, wherein correction information is calculated based on topographic information of the anterior and posterior corneal surfaces, topographic information of the anterior and posterior surfaces of a lens model of an estimated eye's lens, distance information of the posterior corneal surface relative to the anterior corneal surface, distance information of the anterior surface of the lens model relative to the anterior corneal surface, distance information of the posterior surface of the lens model relative to the anterior corneal surface, distance information of the retinal surface relative to the anterior corneal surface, a desired focus point, and a detected eye pupil diameter according to a predefined light environment.

[0071] Figure 5a : A first example for determining correction information based on a desired focus point by reverse ray tracing based on topographic information of the anterior and posterior surfaces of the cornea, topographic information of the anterior and posterior surfaces of a lens model of the lens of the eye, distance information of the posterior surface of the cornea relative to the anterior surface of the cornea, distance information of the anterior surface of the lens model relative to the anterior surface of the cornea, distance information of the posterior surface of the lens model relative to the anterior surface of the cornea, and distance information of the retinal surface relative to the anterior surface of the cornea.

[0072] Figure 5b: A second example for determining correction information by forward ray tracing based on a desired focus point based on topographic information of the anterior and posterior surfaces of the cornea, topographic information of the anterior and posterior surfaces of a lens model of the lens of the eye, distance information of the posterior surface of the cornea relative to the anterior surface of the cornea, distance information of the anterior surface of the lens model relative to the anterior surface of the cornea, distance information of the posterior surface of the lens model relative to the anterior surface of the cornea, and distance information of the retinal surface relative to the anterior surface of the cornea.

[0073] Figure 5c :With the basis Figure 5a and 5b An exemplary cross section of the cornea showing an example of a target profile obtained on the anterior corneal surface.

[0074] Figure 6a : A first example for determining correction information based on the retina by reverse ray tracing based on topographic information of the anterior and posterior surfaces of the cornea, topographic information of the anterior and posterior surfaces of the lens of the eye, distance information of the posterior surface of the cornea relative to the anterior surface of the cornea, distance information of the anterior surface of the lens relative to the anterior surface of the cornea, distance information of the posterior surface of the lens relative to the anterior surface of the cornea, and distance information of the retinal surface relative to the anterior surface of the cornea.

[0075] Figure 6b : A second example for determining correction information based on the retina through forward ray tracing based on topographic information of the anterior and posterior surfaces of the cornea, topographic information of the anterior and posterior surfaces of the lens of the eye, distance information of the posterior surface of the cornea relative to the anterior surface of the cornea, distance information of the anterior surface of the lens relative to the anterior surface of the cornea, distance information of the posterior surface of the lens relative to the anterior surface of the cornea, and distance information of the retinal surface relative to the anterior surface of the cornea.

[0076] Figure 6c :With the basis Figure 6a An exemplary cross section of the cornea showing an example of a target profile obtained on the anterior corneal surface. DETAILED DESCRIPTION

[0077] The following describes possible embodiments of the present invention. For the sake of brevity, only a few embodiments may be described. Those skilled in the art will recognize that the specific features described with reference to these embodiments may be modified and combined in various ways, and that individual features may be omitted if they are not essential. The general explanations in the above sections also apply to the more detailed explanations below.

[0078] Figure 1 An example flow chart 100 is shown for customized corneal ablation performed with the apparatus according to the present invention.

[0079] In this example, an apparatus includes a corneal tomograph 101, a control unit 105 (e.g., a computer, such as a central control unit), a biometer 108, and an excimer or solid-state laser 106. Reference numeral 102 denotes an operator, such as a treating physician. In this example, the apparatus may optionally include a pupillometer 103, a scanning laser refraction meter, a wavefront analyzer 104, a database 109, an optical coherence tomography (OCT), and / or an ultrasound scanning system 107.

[0080] The corneal tomography scanner 101 can be adapted to provide topographic information of the anterior and posterior corneal surfaces. For example, the tomography scanner can be based on light scattering technology, ultrasound technology, and / or optical coherence tomography. The topographic information provided can include the contours of the anterior and posterior corneal surfaces, and possibly also the slope and / or curvature profiles. It can also provide information about the thickness of the cornea and / or more detailed information about the various layers of the cornea, such as the corneal epithelium and / or the corneal stroma.

[0081] At 102, the apparatus may obtain refractive aberration information of the eye from an operator (e.g., a treating physician). This information may be, for example, refractive aberration information that may be subjectively determined by the operator based on their clinical experience. For example, the correction information may include spherical refractive correction, cylindrical refractive correction, and related axes, etc., which may be determined through conventional vision testing or schiascopic examination or an autorefractor.

[0082] In addition to or in lieu of the refractive aberration information obtained from the operator, such information may also be obtained from a scanning laser refraction meter and / or a wavefront analyzer 104. The scanning laser refraction meter and / or the wavefront analyzer may provide refractive aberration information, such as a refractive error map of a cross section of the cornea and / or a two-dimensional region of the corneal surface. For example, the refractive error may be expressed as an angular error or an angular slope or any other suitable form. The refractive error may be associated with an error that varies with the planar x and y (or any other) coordinates of the anterior corneal surface.

[0083] The optical corneal tomography (OCT) and / or ultrasound scanning system 107 can be adapted to provide topographic information of the anterior and posterior surfaces of the eye's lens. As described above with respect to the anterior and posterior corneal surfaces, the topographic information provided can include the contours of the anterior and posterior surfaces of the eye's lens and possibly also the slope and / or curvature profiles. It can also provide information about the thickness of the lens.

[0084] The biometer 108 can be adapted to provide distance information about the posterior surface of the cornea relative to the anterior surface of the cornea and / or the anterior surface of the lens relative to the anterior surface of the cornea and / or the posterior surface of the lens relative to the anterior surface of the cornea and / or distance information about the retina relative to the anterior surface of the cornea. The biometer can be based on ultrasound biometry or optical biometry (e.g., using partial coherence interferometry). The distance information can be represented, for example, as a function of planar x and y (or any other) coordinates of the anterior corneal surface.

[0085] The pupillometer 103 can be used to determine, for example, the photopic pupil diameter, e.g., the pupil diameter that is ultimately associated with the statistical probability of occurrence of a set of predefined light environments, as detected based on the light environment. The photopic pupil diameter can preferably, but not necessarily, be used to define the desired focal point, and the pupil diameter that is ultimately associated with the statistical probability of occurrence of a set of predefined light environments, as detected based on the light environment, can preferably, but not necessarily, be used to limit the corneal region to be treated surgically. The corneal region corresponding to the photopic pupil diameter and to the pupil diameter that is ultimately associated with the statistical probability of occurrence of the light environment, as detected based on the predefined light environment, is determined by a ray tracing process. For example, this can allow the operator to better refine a preselected region of the cornea for treatment. Furthermore, it can be determined which region of the cornea should be used to determine the desired focal point (e.g., by ray tracing). For this determination, it may be useful if the determination of the iris plane allows for a more accurate calculation of the projection of the pupil diameter onto the anterior surface (i.e., calculated individually for the patient's eye geometry). For this purpose, the device and / or corneal tomograph may comprise means for determining the iris plane and / or means for obtaining such information. Alternatively, such corneal region may be arbitrarily selected by the operator.

[0086] Database 109 can be used, for example, to model the lens of an individual eye. Database 109 can include multiple profiles of the anterior and posterior surfaces of different lenses, and possibly also slope and / or curvature profiles. The lens information can be associated with data measured from different individuals and / or can be associated with a universal model. Furthermore, thickness information and / or distance information about the anterior corneal surface of different lenses can be obtained in the database. Alternatively, the lens model can be arbitrarily selected by the operator.

[0087] The control unit 105 can be adapted to obtain information about the optical axis of the eye. The optical axis can be determined by the control unit 105, for example, based on information provided by the tomograph or predefined by the operator. It can also be determined by the tomograph 101 and obtained by the control unit 105 from the tomograph 101. However, it can also be determined by other means and input to the control unit 105, for example, by the operator. For example, the optical axis can be selected as the (approximate) symmetry axis of the cornea.

[0088] Similarly, the control unit 105 can be adapted to obtain information regarding the corneal center of vision, where the optical axis can be centered. This can correspond to the corneal vertex. The center of vision can be determined by the control unit 105, for example, based on information provided by the tomograph or predefined by the operator. It can also be determined by the tomograph 101, for example, based on the corneal vertex, or based on the gaze reflection of light on the anterior surface of the cornea, or based on the corneal axis of symmetry, and obtained by the control unit 105 from the tomograph 101. However, it can also be determined by other means and input to the control unit 105, for example, by the operator.

[0089] Topographic information obtained, for example, from a corneal tomograph 101, an optical coherence tomography (OCT) scanner, and / or an ultrasound scanning system 107, and / or from a database 109, and / or distance information obtained from a biometer 108, and / or pupil information, which may be collected from a pupillometer 103, and / or refractive aberration information obtained, for example, from an operator 102 and possibly from a scanning laser refractor and / or from a wavefront analyzer 104, can be obtained by a control unit 105 of the device. The control unit 105 can then determine corrective information based on the obtained information. The control unit can be adapted to determine the corrective information as generally described above in the "Summary of the Invention" section and further described below with respect to Figures 2-6. In some examples, other characteristics of the individual patient's eye, such as topographic information regarding the retina and / or the fovea relative to the cornea, can also be taken into account when determining the corrective information. The corrective information can be expressed, for example, in terms of a customized ablation volume of corneal tissue. For example, the correction information may be related to the ablation depth, which is expressed in microns and varies with the planar x and y (or any other) coordinates of the anterior corneal surface. Topographic information of the anterior and posterior corneal surfaces may be related to similar coordinates. Figures 4a-4c 、 Figures 5a-5c and Figure 6a-6b Further exemplary details regarding the determination of the correction information are provided.The control unit 105 may further be adapted to control and coordinate other elements of the device with each other.

[0090] The determined corrective information can then be provided to, for example, an excimer or solid-state laser 106, which can ablate corneal tissue using, for example, a series of deliberately arranged "laser shots." The laser 106 can include a coupling interface for reading the corrective information from the control unit 105. After performing one or more "laser shots," the resulting anterior corneal shape can be examined, for example, by topography (or morphology) and / or refraction, based at least in part on the corrective information. In one example, the corneal tomograph 101 can provide updated topographic information of the ablated anterior corneal surface. In another example, the scanning laser refraction meter and / or wavefront analyzer 104 can additionally or alternatively provide updated refractive aberration information after ablation. This updated topographic and / or refractive aberration information can then be used to determine whether the target anterior corneal surface has been achieved. If the desired anterior surface or refractive error reduction has not been achieved after performing the entire ablation, the control unit 105 can determine another volume of corneal tissue for ablation, which can then be removed by the excimer or solid-state laser 106. Instead of applying such feedback after the entire ablation is complete, it can also be applied in real time, or after a specific portion of the planned ablation has been ablated, for example so that possible calibration errors of the laser can be taken into account. If the target profile of the anterior corneal surface is achieved, the customized ablation procedure can be stopped.

[0091] In one example, the control unit 105 may represent an embodiment of the apparatus of the present invention. In other examples, the corneal tomograph 101 and / or the optical coherence tomography (OCT) scanner and / or the ultrasound scanning system 107 and / or the biometer 108 and / or the laser 106 may or may not be part of the apparatus. The control unit 105 may be adapted to interface with the corneal tomograph 101 and / or the optical coherence tomography (OCT) scanner and / or the ultrasound scanning system 107 and / or the biometer 108 and / or the laser 106. This may allow for receiving data from the corneal tomograph 101 and / or the optical coherence tomography (OCT) scanner and / or the ultrasound scanning system 107 and / or the biometer 108 and / or the laser 106, and / or controlling the laser 106.

[0092] In some examples, the control unit 105 can optionally be permanently coupled (e.g., by wire or wirelessly) to any of the corneal tomograph 101 and / or the optical coherence tomography (OCT) scanner and / or the ultrasound scanning system 107 and / or the biometer 108 and / or the laser 106. However, this need not be the case. In other examples, the control unit 105, the corneal tomograph 101 and / or the optical coherence tomography (OCT) scanner and / or the ultrasound scanning system 107 and / or the biometer 108 and / or the laser 106 can exchange data (unidirectionally in each direction and / or bidirectionally) via a temporary coupling or via a data carrier (e.g., a USB device that can be moved from one device to another, a server that they can access together, and / or any other available data carrier).

[0093] Figure 2a A schematic diagram of a corneal cross-section 200a is shown. This schematic illustration depicts topographic information of the anterior corneal surface, i.e., profile 201a, as measured, for example, using a corneal tomograph. Furthermore, a target profile 202a of the anterior corneal surface is depicted. The volume bounded by the actual profile 201a and the target profile 202a of the anterior corneal surface defines the volume of corneal tissue that can be ablated, for example, by an excimer or solid-state laser, i.e., the target ablation volume.

[0094] Figure 2b Schematic diagram showing a top view of a corneal region 200b that can be analyzed and / or treated. The region includes a monofocal zone 201b. The monofocal zone 201b can define a corneal region that can be treated to optimize distance vision. In one example, the monofocal zone can be determined by a treating physician and / or a reference physician. Figure 1 The pupillometer 103 as explained determines, for example, that the monofocal zone is selected to correspond to the projection of the pupil diameter ultimately associated with the statistical probability of the occurrence of a set of predefined light environments detected according to the light environment. The monofocal zone 201b can be further surrounded by a custom connection zone 202b. The custom connection zone 202b connects the treated area of ​​the anterior corneal surface—i.e., the monofocal zone 201b in this example—with the untreated area. The perimeter of the custom connection zone 202b can be arbitrarily selected so that the perimeter includes an irregular shape. The custom connection zone 202b can be used and its perimeter can be selected to minimize the risk of regression, corneal epithelial haze, and starburst effects, which can further promote corneal healing after treatment.

[0095] Figure 2c Another schematic illustration of a top view of a corneal region 200c is shown. The corneal region includes a multifocal region 201c and a custom connection region 205c surrounding the multifocal region 201c. Figure 2bAs explained, the customized connection zone 205c can connect the periphery of the treated area of ​​the anterior corneal surface, that is, the multifocal zone 201c in this example, with the untreated area. The multifocal zone 201c can be further subdivided into a near vision zone 202c, an intermediate vision zone 203c, and a distance vision zone 204c. Figure 2b As explained in the example of FIG, the multi-focal zone 201c and sub-zones of the multi-focal zone 201c can be selected by the treating physician and / or Figure 1 The pupillometer 103 is used to determine the corrected image quality. Furthermore, the operator can determine different refractive corrections and / or different refractive error maps for sub-zones of the multifocal zone 201c, such that different refractive aberration information and / or a different desired focal point can be used in each zone. The refractive aberration information can include refractive aberration information specific to one or more of the near vision zone 202c, the intermediate vision zone 203c, and the distance vision zone 204c. Similarly, the focal points of these zones can be different. Based on this information, corresponding correction information can then be determined for each zone, as generally described herein, for example, by considering only the areas of the anterior corneal surface and the corresponding posterior corneal surface, as well as the anterior lens surface and the corresponding posterior lens surface, that fall within the corresponding zone. Thus, the near vision zone 202c for near visual field vision, the intermediate vision zone 203c for intermediate visual field vision, and the distance vision zone 204c for far visual field vision can be individually optimized. In other words, the corrective information may include corrective information specific to one or more of the near vision zone 202c, the intermediate vision zone 203c, and the distance vision zone 204c.

[0096] Figure 3 Another schematic illustration of a corneal cross section 300 is shown. The cross section 300 shows topographic information of the front surface of the cornea, i.e., profile 301, and topographic information of the back surface of the cornea, i.e., profile 302. It further shows topographic information of the front surface of the lens of the eye, i.e., profile, and topographic information of the back surface of the lens of the eye, i.e., profile. The profiles of the front and back surfaces of the cornea can be obtained, for example, by reference to Figure 1 The contours of the anterior lens surface and the posterior lens surface of the eye can be obtained, for example, by an optical coherence tomography (OCT) scanner and / or an ultrasound scanning system 107, or they can be obtained from a reference Figure 1 The explained database 109 is obtained. In addition, Figure 3Slopes 303 and 304 are depicted for each point on the anterior corneal surface 301 and the posterior corneal surface 302. Slopes 307 and 308 are also depicted for each point on the anterior lens surface 305 and the posterior lens surface 306. Slopes 303, 304, 307, and 308 are related to the refractive properties of the cornea and the lens (e.g., to calculate the refractive angle, as determined by Snell's law), and may also be determined by the corneal tomograph 101 and the optical coherence tomography and / or ultrasound scanning system 107, respectively, or may be obtained from the database 109 or derived from information provided by the corneal tomograph 101 and the optical coherence tomography (OCT) and / or ultrasound scanning system 107, respectively, for example, by calculating corresponding tangent lines. As discussed in more detail below, the slope 303 of the anterior corneal surface can be modified by laser ablation so that a target profile of the anterior corneal surface 301 can be obtained that optimizes vision based on the refraction provided by the slope 304 of the posterior corneal surface 302 and the slopes 307 and 308 of the anterior lens surface 305 and posterior lens surface 306.

[0097] Figure 4a Another schematic illustration of a corneal cross-section 400a is shown. Cross-section 400a includes topographic information of the anterior corneal surface, i.e., profile 401, and topographic information of the posterior corneal surface, i.e., profile 402. Furthermore, the schematic includes an iris plane 404, wherein the iris defines a pupil 403. Pupil 403 can correspond to a photopic pupil. Optical axis 420 can be defined, for example, based on the visual axis of the eye, such as an axis of symmetry of the cornea, e.g., as selected by an operator. Furthermore, center 405 of the anterior corneal surface can be defined, for example, as the corneal vertex or a light gaze reflection on the anterior corneal surface, or can be defined based on an axis of symmetry of the cornea, or can be selected by an operator.

[0098] Optionally, an area 401a of the anterior corneal surface can be determined that corresponds to the projection of the photopic pupil (i.e., assuming that light rays strike the cornea parallel to the optical axis). Thus, the area 401a of the anterior corneal surface relevant for determining the desired focal point can be determined (light rays striking other areas of the cornea will be blocked by the iris). Based on topographic information of the anterior and posterior corneal surfaces and the generally known refractive index of the cornea and the aqueous humor within the cornea, light rays can be tracked by calculating the corresponding refractive angles, for example, based on Snell's law.

[0099] Figure 4b The topographic information based on the anterior corneal surface 401, the topographic information based on the posterior corneal surface 402, the topographic information based on the lens (e.g., from the topographic information about the retina) 403, and the topographic information based on the anterior corneal surface 401 are shown. Figure 1 The lens model of the estimated eye lens obtained from the interpreted database 109) is based on the topographic information of the front surface 431, the topographic information of the back surface 432 of the lens (for example, from the lens model of the estimated eye lens obtained from the interpreted database 109), the topographic information of the front surface 431 of the lens, the topographic information of the back surface 432 of the lens (for example, from the lens model of the estimated eye lens obtained from the interpreted database 109), the Figure 1 This example illustrates an example of using a lens model (estimating the lens of an eye obtained from the database 109) and determining a desired focal point based on refractive aberration information. In this example, light ray 410 propagates toward the cornea parallel to optical axis 420. The light ray is refracted by an optical component 450, such as a simulated lens, that corrects the refractive aberration information. For example, if the refractive aberration information corresponds to subjective refraction with spherical aberration and cylindrical aberration on opposite axes, optical component 450 can be a lens suitable for correcting these spherical and cylindrical aberrations. In the case of more complex refractive aberration information, such as that involving higher-order aberrations, optical component 450 can be defined accordingly, for example to simulate a more complex lens.

[0100] The light ray 410 refracted by the optical member 450 then strikes the anterior corneal surface 401, propagates through the cornea, and strikes the posterior corneal surface 402, where the posterior corneal surface is separated from the anterior corneal surface by a distance 461 at the optical axis 420, which may correspond to the corneal vertex (wherein the distance information may be obtained from information about the corneal vertex). Figure 1 The light then propagates through the anterior chamber and strikes the lens (e.g., from about Figure 1 The light then propagates further through the lens and strikes the lens (e.g., from a lens model obtained from the database 109). Figure 1 The lens model obtained from the interpreted database 109) is located on the back surface 432 of the lens, which can be located at a distance 462 and a distance 463 measured at the optical axis 420 from the anterior corneal surface 401 (e.g., by the distance 462 and the distance 463 measured at the optical axis 420). Figure 1 Based on the anterior corneal surface 401 and the posterior corneal surface 402 and the lens (e.g., from the Figure 1 Based on the topographic information of the front surface 431 and the back surface 432 of the lens model obtained from the database 109 interpreted by the computer, the refraction at these different surfaces can be calculated and the rays can be traced so that their intersection with the optical axis 420 in the eye can be determined. Here, the calculation can be limited to the rays that fall on the area of ​​the front surface 401 of the cornea, such as for example Figure 4a Alternatively, the calculation can be limited to the reference area 401a. Figure 2c Any of the outlined areas 202c, 203c or 204c, for example where near vision, intermediate vision or distance vision is to be analyzed separately.

[0101] Based on the intersection points, a desired focus point 440 can be determined. For example, a weighted average of all intersection points can be used. In the simplest case, a centroid calculation can be used, or calculations with different weighting factors can be used, such as giving more weight to central rays. Determined intersection points can be given decreasing weights depending on the radial distance between the center of vision and the corresponding impinging ray on the anterior corneal surface.

[0102] It should be noted that in other examples, the focal point can be defined in different ways, for example based on the refractive aberration that the operator wants to correct, based on the position of the fovea or retina of the patient's eye, or arbitrarily defined by the operator. The corresponding determination can be performed by the operator or a separate device, in which case the device according to the present invention has a corresponding interface for obtaining the desired focal point 440. However, the corresponding determination can also be performed by the device itself.

[0103] Based on the determined desired focus point 440, a distance 480 from the retina can be determined, which can be at a distance 464 relative to the anterior corneal surface (at the optical axis 420) (e.g., by the distance 480 relative to the retina). Figure 1 4). This distance 480 defines the position of the desired focal point 440 relative to the retina and can be used as a reliability measure for the refractive aberration information, for example, obtained from the database 109 and / or provided by the operator 102 and / or obtained by the scanning refraction meter and / or wavefront analyzer 104. For example, if the distance 480 is above a threshold, for example, above 500 μm, more preferably above 300 μm, and most preferably above 100 μm, a warning, for example an audio signal, can be issued, indicating to the operator, for example, the treating physician, that the available data may be erroneous. The operator can then reassess the obtained information.

[0104] Additionally or alternatively, the desired focus point 440 can also be determined based on backward ray tracing. Determinations based on forward ray tracing and backward ray tracing can be applied as an alternative or in addition to each other, for example, alternately in one or more iterations or separately from each other, wherein a weighted average (or simple average) of the respectively determined desired focus points can then be determined.

[0105] Figure 4cAnother step that can be implemented is shown, in which a region 401b of the anterior corneal surface is determined to which subsequent calculation of corrective information and / or treatment can be limited. Region 401b can be determined based on a desired focal point 440 and a selected pupil diameter 403a, such as a pupil diameter that is ultimately associated with the statistical probability of occurrence of a predefined set of light environments, or a pupil diameter to which the patient's actual pupil diameter in daily life is expected to be somewhat limited. For example, the diameter can be selected such that 80%-100%, and preferably approximately 95%, of all instances in the patient's daily life include a pupil diameter that does not exceed the selected diameter.

[0106] Figure 1 The device shown, in particular the control unit 105, may be adapted to perform reference Figures 4a-4c Any of the steps outlined.

[0107] Figure 5a A first example for determining correction information by reverse ray tracing is shown. In this example, the determination is based on rays 410 emerging from a desired focal point 440, which is at a distance 480 relative to the retina. For each point or portion on the selected area 401b of the anterior corneal surface 401 (e.g., a point or portion in a grid, as outlined earlier), as well as on the posterior corneal surface 402, the lens (e.g., from about Figure 1 The lens model obtained from the database 109 interpreted by Figure 1 For each corresponding point on the back surface 432 of the lens model obtained from the database 109 interpreted by the user, a ray can be traced. Figure 4b In the manner described, the posterior surface of the lens, the anterior surface of the lens, and the posterior surface of the cornea can be located at distances 461, 462, and 463, respectively, relative to the anterior surface of the cornea and are exemplarily indicated with respect to the optical axis 420 (where these distances can be represented by the distances with respect to Figure 1 For each point, correction information can be determined in the form of an angle 416 between a ray 410 exiting the cornea and a direction 415 of the optical axis 420. The angular deviation between the ray 410 exiting the cornea and the direction of the optical axis 420 indicates a refractive error. The determination can include determining the angle 416 between the ray 410 exiting the cornea and the direction of the optical axis 420. Figure 1 The lens model obtained from the database 109 interpreted by the invention is used to determine the refraction of the light ray 410 when it strikes the posterior surface 432 of the lens (after propagating through the lens, which is obtained from the lens of the invention). Figure 1The method comprises determining the refraction of a ray 410 when it strikes the posterior corneal surface 402 (which may be contained in or determined based on topographic information of the posterior corneal surface 402, such as the contour of the posterior corneal surface). Similarly, it comprises determining the refraction of a ray 410 when it strikes the anterior corneal surface 401 having a local slope 490 (after propagation through the cornea).

[0108] Next, a local target slope 495 of the anterior surface 401 can be determined such that a light ray 410 impinging on the anterior surface having such a slope 495 will be refracted such that it exits the cornea in the direction 415 of the optical axis 420. Additionally or alternatively, an angle 496 between the local slope 490 of the anterior surface 401 and the local target slope 495 can be calculated. In this way, a local target slope 495 can be determined for each portion or each point within the region 401b. For example, by integrating the local target slope 495, a desired target profile 470 (see below) representing the region 401b of the anterior surface 401 can be determined. Figure 5c ) in the form of correction information.

[0109] Optionally, the desired target contour 470 of the anterior corneal surface 401 within the region 401 b is then translated along the optical axis 420 so that, if desired, a smooth transition between the target contour within the region 401 b and the anterior surface 401 outside the region 401 b can be achieved. In this step, it is also ensured that all points of the target contour lie within the actual contour of the anterior corneal surface 401.

[0110] refer to Figure 5a The steps outlined above can then be re-iterated one or more times, wherein the topographic information of the front surface is replaced with the target profile of the front surface obtained from the corresponding previous iteration. Such iterations can produce increasingly improved target profiles, which optimize the focus on the desired focus point 440. It is possible to apply a modification to the angle 496 in each iteration to optimize the focus on the desired focus point 440. By iterating this process, an optimization of the focus on the desired focus point 440 can be achieved.

[0111] In addition to keeping the anterior corneal surface 401 within the desired target profile 470 (see below) between iterations Figure 5c ) in addition to or instead of the translation along the optical axis 420, such a translation may also be performed as a final step, i.e. after completion of the iteration.

[0112] The ablation volume can be determined based on the intersection between the topographic information of the anterior surface 401 and the target contour 202a of the anterior corneal surface, which is defined as the determined target contour 470, possibly including the connection zone 202b. Therefore, correction information can also be provided in the form of the ablation volume.

[0113] Especially in regard to Figure 5a In the calculations outlined, it is beneficial to consider topographic information about the posterior corneal surface and the lens model. Local irregularities in the posterior shape of the cornea can significantly affect the refraction at each point and the correction required at each point. Taking these factors into account improves the vision correction optimized for each patient and can minimize the ablation volume.

[0114] Figure 5b Another example for determining correction information is shown, which is similar to Figure 5a However, instead of Figure 5a As outlined above, light rays 410 are used that are directed from the desired focal point 440 onto the selected area 401b of the cornea in a manner parallel to the optical axis 420, i.e., forward ray tracing is used. Similarly, as described with reference to Figure 5a As outlined, based on the local slopes 490 of the anterior corneal surface 401, the posterior corneal surface 402, the anterior surface 431 of the lens model, and the posterior surface 432 of the lens model, each ray 410 can be tracked until it intersects the optical axis 420 within the eye. For each ray, the positional deviation 417 of the intersection point relative to the desired focus point 440 can be determined.

[0115] A local target slope 495 of the front surface 401 can be determined such that the light ray 410 is focused onto the desired focal point 440 (or minimizes deviation from the desired focal point). Additionally or alternatively, an angle 496 between the local slope 490 of the front surface and the local target slope 495 can be determined. In this manner, a local target slope 495 can be determined for each portion or each point within the selected area 401b. For example, by integrating the local target slope 495, a desired target profile of the front surface 401 can be determined, as described above with reference to FIG. Figure 5a In addition, for reference Figure 5b The examples outlined, iterations and / or translations along the optical axis 420 may also be performed in a similar manner.

[0116] Similarly, as referenced Figure 5a As explained, considering the topographic information about the corneal posterior surface 402, the front surface 431 and the posterior surface 432 of the lens model and the respective distance information 461, distance information 462, distance information 463, distance information 464 for Figure 5b The determination of is also particularly helpful.

[0117] refer to Figure 5a and 5b The determinations outlined can be applied as an alternative or in addition to one another, for example alternately in one or more iterations or separately from one another, wherein a weighted average (or simple average) of the respectively determined correction information can then be determined. Region 401b can be selected as any of the regions outlined herein.

[0118] Figure 1 The device shown, in particular the control unit 105, may be adapted to perform reference Figure 5a-5b Any of the steps outlined.

[0119] Figure 5c Another exemplary cross section is shown, wherein the image reference Figure 5a-5b Exemplary corrective information in the form of a target profile 470 of the anterior corneal surface determined as outlined.

[0120] Figure 6a Another example for determining correction information by reverse ray tracing is shown. In this example, the determination is based on rays 410 emerging from the retinal surface 445. For each point or portion on the selected area 401b of the anterior corneal surface 401 (e.g., a point or portion in a grid, as outlined earlier), the posterior corneal surface 402, the lens (e.g., a region 401b of the retina, as outlined earlier), and the posterior corneal surface 402, the retina (e.g., a region 401b of the retina, as outlined earlier), the retinal surface 445, ... Figure 1 The anterior surface 431 and the lens (e.g., obtained by the OCT and / or ultrasound scanning system 107 as explained) are Figure 1 For each corresponding point on the back surface 432 obtained by the OCT and / or ultrasound scanning system 107 as explained above, a ray can be traced. Figure 4b In the manner described, the posterior surface of the lens, the anterior surface of the lens, and the posterior surface of the cornea can be located at distances 461, 462, and 463, respectively, relative to the anterior surface of the cornea and are exemplarily indicated with respect to the optical axis 420 (where these distances can be represented by the distances with respect to Figure 1 For each point, correction information can be determined in the form of an angle 416 between a ray 410 exiting the cornea and a direction 415 of the optical axis 420. The angular deviation between the ray 410 exiting the cornea and the direction of the optical axis 420 indicates a refractive error. The determination can include determining the angle 416 between the ray 410 exiting the cornea and the direction of the optical axis 420. Figure 1 The refraction of the light 410 when it strikes the posterior surface 432 of the lens (obtained by the OCT and / or ultrasound scanning system 107 as explained above) determines the refraction of the light 410 when it strikes the anterior surface 431 of the lens (after propagating through the lens, which is formed by, for example, the lens of FIG. Figure 1The method further comprises determining the refraction of a light ray 410 when it strikes the posterior corneal surface 402 (which may be contained in or determined based on topographic information of the posterior corneal surface 402, such as the contour of the posterior corneal surface). Similarly, it comprises determining the refraction of a light ray 410 when it strikes the anterior corneal surface 401 having a local slope 490 (after propagation through the cornea).

[0121] Next, a local target slope 495 of the anterior surface 401 can be determined such that a light ray 410 impinging on the anterior surface having such a slope 495 will be refracted such that it exits the cornea in the direction 415 of the optical axis 420. Additionally or alternatively, an angle 496 between the local slope 490 of the anterior surface 401 and the local target slope 495 can be calculated. In this way, a local target slope 495 can be determined for each portion or each point within the region 401b. For example, by integrating the local target slope 495, a desired target profile 470 (see below) representing the region 401b of the anterior surface 401 can be determined. Figure 6c ) in the form of correction information.

[0122] Optionally, the desired target contour 470 of the anterior corneal surface 401 within the region 401 b is then translated along the optical axis 420 so that, if desired, a smooth transition between the target contour within the region 401 b and the anterior surface 401 outside the region 401 b can be achieved. In this step, it is also ensured that all points of the target contour lie within the actual contour of the anterior corneal surface 401.

[0123] refer to Figure 6a The steps outlined above can then be re-iterated one or more times, wherein the topographic information of the anterior surface is replaced with the target profile of the anterior surface obtained from the corresponding previous iteration. Such iterations can produce increasingly improved target profiles, which optimize the focus on the retinal surface 445. It is possible that modifications to the angle 496 are applied in each iteration to optimize the focus on the retinal surface 445. By iterating this process, optimization of the focus on the retinal surface 445 can be achieved.

[0124] In addition to keeping the anterior corneal surface 401 within the desired target profile 470 (see below) between iterations Figure 6c ) in addition to or instead of the translation along the optical axis 420, such a translation may also be performed as a final step, i.e. after completion of the iteration.

[0125] The ablation volume can be determined based on the intersection between the topographic information of the anterior surface 401 and the target contour 202a of the anterior corneal surface, which is defined as the determined target contour 470, possibly including the connection zone 202b. Therefore, correction information can also be provided in the form of the ablation volume.

[0126] Especially in regard to Figure 6a In the calculations outlined, it is beneficial to consider topographic information about the posterior corneal surface and the anterior and posterior lens surfaces. Local irregularities in the posterior shape of the cornea can significantly affect the refraction at each point and the correction required at each point. Taking these factors into account improves the vision correction optimized for each patient and can minimize the ablation volume.

[0127] Figure 6b Another example for determining correction information is shown, which is similar to Figure 6a However, instead of Figure 6a As outlined above, light rays 410 are used that are incident on a selected area 401b of the cornea in a manner parallel to the optical axis 420, i.e., forward ray tracing is used. Similarly, as described with reference to Figure 6a As outlined, each ray 410 can be tracked until it intersects the optical axis 420 within the eye based on the local slopes 490 of the anterior corneal surface 401, the posterior corneal surface 402, the anterior lens surface 431, and the posterior lens surface 432. For each ray, the positional deviation 417 of the intersection point relative to the retinal surface 445 can be determined.

[0128] A local target slope 495 of the anterior surface 401 can be determined such that the light ray 410 is focused onto (or minimizes deviation from) the retinal surface 445. Additionally or alternatively, an angle 496 between the local slope 490 of the anterior surface and the local target slope 495 can be determined. In this manner, a local target slope 495 can be determined for each portion or each point within the selected area 401b. For example, by integrating the local target slope 495, a desired target profile of the anterior surface 401 can be determined, as described above with reference to FIG. Figure 6a In addition, similar to reference Figure 6a The described approach performs iterations and / or translations along the optical axis 420 .

[0129] Similarly, as referenced Figure 6a As explained, considering the topographic information about the corneal posterior surface 402, the lens anterior surface 431 and the lens posterior surface 432 and the respective distance information 461, distance information 462, distance information 463, distance information 464 for Figure 6b The determination of is also particularly helpful.

[0130] refer to Figure 6a and 6b The determinations outlined can be applied as an alternative or in addition to one another, for example alternately in one or more iterations or separately from one another, wherein a weighted average (or simple average) of the respectively determined correction information can then be determined. Region 401b can be selected as any of the regions outlined herein.

[0131] Figure 1 The device shown, in particular the control unit 105, may be adapted to perform reference Figure 6a-6b Any of the steps outlined.

[0132] Figure 6c Another exemplary cross section is shown, wherein the image reference Figure 6a-6b Exemplary corrective information in the form of a target profile 470 of the anterior corneal surface determined as outlined.

[0133] Additionally or alternatively, as with respect to Figure 6a The topographic information obtained about the anterior corneal surface 401 and the posterior corneal surface 402, the topographic information about the anterior lens surface 433 and the posterior lens surface 434, and possibly also the respective distance information 461, 462, 463, 464 can be used in a manner similar to that about Figures 4a to 4c In the manner described above, a desired focus point is determined 440. In a manner similar to that described above, a distance 480 of the determined desired focus point relative to the retina can be determined. If this distance is above a second threshold, for example above 500 μm, more preferably above 300 μm, and most preferably above 100 μm, a warning can be issued in a manner similar to that described above.

Claims

1. A device (100) for correcting refractive errors of vision, comprising: a. a means for obtaining measured topographic information of the anterior corneal surface (401) and measured topographic information of the posterior corneal surface (402) of an individual eye; b. means for obtaining measured distance information (464) of the retina of the eye relative to the anterior corneal surface (401) of the individual's eye; c. means for determining a position (480) of a desired focus point (440) relative to the retina based on the measured topographic information of the anterior corneal surface (401) and the posterior corneal surface (402) and the measured refractive aberration information of the eye; Wherein, based on the measured distance information, it is verified whether the desired focus point is actually located on or close to the retina, and the device is configured to verify the reliability of the measured topographic information and / or the measured distance information and / or the measured refractive aberration information relative to the actual respective values ​​based on the position of the desired focus point relative to the retina.

2. The device (100) according to claim 1, further comprising a component for obtaining at least one of distance information (462) of the front surface of the lens of the eye relative to the front surface of the cornea of ​​the individual eye and distance information (463) of the back surface of the lens relative to the front surface of the cornea of ​​the individual eye and positioning a lens model for estimating the lens of the eye.

3. The device (100) according to claim 2, wherein the means for determining the position (480) of the desired focus point (440) relative to the retina is further adapted to perform the determination based on estimating a lens model of the lens of the eye.

4. The device (100) according to any one of claims 1 to 3, wherein the device (100) is adapted to issue a warning if the position (480) of the desired focus point relative to the retina exceeds a predetermined threshold.

5. The device (100) according to any one of claims 1 to 3, wherein the component for obtaining the desired focus point (440) is further adapted to determine the desired focus point (440) by ray tracing of at least one light ray (410) refracted by an optical component (450) according to topographic information of the anterior corneal surface (401) and the posterior corneal surface (402) and according to a correction of the refractive aberration information of the eye.

6. The device (100) according to any one of claims 1 to 3, further comprising a component for determining correction information related to the anterior corneal surface (401) based on topographic information of the anterior corneal surface (401) and the posterior corneal surface (402) to optimize focusing on the desired focusing point (440).

7. A memory medium having stored thereon a computer program for correction of refractive errors of vision, the computer program comprising instructions which, when executed, cause the apparatus (100) according to any one of claims 1 to 6 to perform the following operations: a. obtaining measured topographic information of the anterior corneal surface (401) and topographic information of the posterior corneal surface (402) of an individual eye; b. obtaining measured distance information (464) of the retina of the eye relative to the anterior corneal surface (401) of the individual's eye; c. determining a position (480) of a desired focus point (440) relative to the retina based on measured topographic information of the anterior corneal surface (401) and the posterior corneal surface (402) and measured refractive aberration information of the eye; d. verifying whether the desired focus point is indeed located on or close to the retina based on the measured distance information, and verifying the reliability of the measured topographic information and / or the measured distance information and / or the measured refractive aberration information based on the position of the desired focus point relative to the retina.

8. A method for determining refractive error correction information, comprising the steps of: a. obtaining measured topographic information of the anterior corneal surface (401) and topographic information of the posterior corneal surface (402) of an individual eye; b. obtaining measured distance information (464) of the retina of the eye relative to the anterior corneal surface (401) of the individual's eye; c. determining a position (480) of a desired focus point (440) relative to the retina based on measured topographic information of the anterior corneal surface (401) and the posterior corneal surface (402) and measured refractive aberration information of the eye; d. verifying whether the desired focus point is indeed located on or close to the retina based on the measured distance information, and verifying the reliability of the measured topographic information and / or the measured distance information and / or the measured refractive aberration information based on the position of the desired focus point relative to the retina.

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