Method, apparatus, computer program, and system for converting ophthalmic lens measurements

Abstract

A method for converting measurements of a lens (1), comprising the following steps: receiving experimental lens measurements (EXP) of the lens (1) from optical measurements of the lens (1); determining (S1) a digital lens model representing the lens (1) from the experimental lens measurements (EXP); determining (S2) a transformed digital lens measurement (SIM2) representing the transformed lens measurements of the lens (1) based on the digital lens model; and determining (S3) a measurement result (CON) of the lens (1) based on the experimental lens measurements (EXP1) and the transformed digital lens measurement (SIM2).

Description

[Technical Field]

[0001] The present invention relates to a method, apparatus, computer program and system for converting measurements of a lens, preferably an ophthalmic lens. [Background technology]

[0002] Many lens manufacturing processes involve rigorous quality control. Examples of ophthalmic lenses are contact lenses or intraocular lenses (IOLs). One important parameter of an ophthalmic lens that is controlled is, for example, the lens's focus (also known as the lens's refractive power), but other control parameters can be part of the quality control as well. To measure the desired control parameter of an ophthalmic lens, as shown in the example of Figure 1, the analyzed lens 1 is illuminated with incident light 2, and the emitted light 3 transmitted through the analyzed lens 1 is analyzed. The incident light 2 is often a collimated light beam. In modern lens mappers, the wavefront 4 of the emitted light 3 is measured, but it is also possible to measure only the focus F2 of the emitted length or other parameters of the emitted light 3. Based on the measured emitted light, e.g., the wavefront, the parameters of the ophthalmic lens are determined. In some situations, the control parameter is desired under different measurement conditions, e.g., in a solution (wet condition). In this case, the analyzed lens 1 can be measured in this different measurement condition, e.g., in a liquid 5, to obtain the control parameter under the wet condition, as shown in Figure 2. As can be seen from Figures 1 and 2, the focal point F1 of the emitted light 3 of the analyzed lens 1 in wet conditions is different from the focal point F2 of the emitted light 3 of the analyzed lens 1 in air.

[0003] However, in many situations, lens measurements require a transformation of the measurement results. One transformation scenario is when lens 1 is measured in a first measurement condition, while parameters are needed for a second measurement condition, as explained in the following example.

[0004] The first example is a measurement for a contact lens. The standard for the characterization of contact lenses, ISO 18369-3:2016(E), requires reporting of performance in air (shown in Figure 1), while measurements are taken in saline solution 5 (see Figure 2). Changing the refractive index of the surrounding medium 5 from 1.336 to 1 changes the refraction of light rays by the ophthalmic lens 1. This is called wet-to-dry conversion. To a first approximation, the change in direction of light 3' at the lens exit is proportional to the ratio of the two refractive indices. In a real experiment, light 3' undergoes another refraction as it passes through the cuvette from the liquid to the air. This effect is easy to explain because the two faces of the cuvette are parallel. For simplicity, the refraction from the liquid to the air is ignored in this discussion. Campbell C. converts the measured wet cell soft lens power to the apex power in air. Int Contact Lens Clin. 1984;11:168-71 proposes a model that takes into account the parameters of the lens 1 (including at least the refractive index, thickness, and radius of curvature) to calculate the power in air from the power measured in saline solution 5. This model assumes that the two surfaces are spherical and is valid in the paraxial approximation. In practice, the conversion becomes much less accurate when the surface shape deviates from a sphere and due to high optical power.

[0005] A second example is the measurement of IOLs. For IOLs, it is the opposite. Standard ISO 11979-2:2014(E) requires that measurements be reported in a cuvette filled with saline (as shown in Figure 2), but some lens manufacturers prefer to perform the measurements in air (as shown in Figure 1). The conversion is from dry to wet, but the principle remains the same.

[0006] The third example also refers to an IOL. Standard ISO 11979-2:2014(E) requires measuring the optical performance of a lens 1 with a model cornea 6 (shown in Figure 3) to mimic the performance of an IOL 1 when applied to an eye. On the one hand, this configuration takes into account all aberrations introduced by the model cornea 6 itself, the IOL alone, and the combination of the two. On the other hand, the measured wavefront curvature is much higher because, to a first approximation, the powers of the model cornea 6 and the IOL 1 under test are summed. In addition, the alignment of the IOL 1 with respect to the model cornea 6 becomes important. In practice, most lens mappers for lens testing do not integrate a physical model cornea 6. Therefore, the incident light 2 is collimated. Rather, they measure the lens 1 without the corneal model 6 as in Figures 1 or 2 and numerically add the effect of the corneal model. This configuration provides better accuracy because the incoming beam 1 is then collimated, resulting in a flatter wavefront 4, and there are no alignment constraints with the physical corneal model that can generate measurement errors. In the paraxial approximation, the effects of beam convergence produced by the model cornea 6 are ignored, and the wavefront of the exiting light 3 from the IOL 1 is approximated as the sum of (i) the wavefront produced by the digital model cornea and (ii) the wavefront produced by the measured IOL 1. This approximation of the effect of the corneal model, while easy to implement, can result in an erroneous estimation of the optical performance of the IOL 1.

[0007] Ray tracing simulation is a highly accurate method for simulating the optical performance of a lens or lens assembly. Obviously, it requires knowledge of the lens being simulated. In contrast, a lens mapper is expected to be able to inspect a lens and report its optical performance without knowing the detailed lens design.

[0008] Therefore, DE102016209720 proposes experimentally measuring the wavefront 4 of the light 3 exiting the IOL 1 without using a corneal model 6, as shown in Figures 1 and 2. A digital lens model of the IOL 1 is estimated based on the experimentally measured wavefront 4 of the exiting light 3. A transformed digital lens model is calculated, including the digital corneal model and the digital lens model of the IOL 1. The transformed wavefront of the light exiting the IOL using the corneal model is calculated based on ray tracing in the transformed digital lens model. The parameters of the IOL 1 with the corneal model can be determined from the numerically calculated wavefront. If the estimated digital lens model perfectly describes the actual lens through a complete ray tracing simulation of the digital corneal model and the estimated digital lens model, approximation errors due to numerical conversion can be reduced. Any characteristics of the lens that are not well represented will result in errors when calculating the optical performance using the corneal model. The results are varied. Numerically obtained corrected wavefronts may not reflect small surface irregularities, such as scratches on the lens, which can affect the optical performance of complex lenses, such as aspheric toric lenses or multifocal lenses with different focal zones. This requires a lens model with multiple parameters. Accurate estimation of all parameters can be numerically challenging, especially when parameters are coupled. The lens being tested may deviate from the design, leading to inaccuracies in the model. A good description of deviations between the design and the tested lens may require complex models. Therefore, there is a significant risk that the lens model will be an overly optimistic representation of the test lens. The performance simulated with a digital lens model will misestimate the actual performance of the tested lens. Finally, there are lens designs that are practically impossible to represent with a lens model. For example, a multifocal diffractive lens integrates an engraved grating on one of its two surfaces, generating multiple fixed focal points. An accurate description of the complex structure is crucial for simulating the lens's accurate optics. Therefore, the solution proposed in the aforementioned German patent application cannot be applied to complex lens designs such as diffractive lenses.

[0009] Figure 4 shows a further state-of-the-art transformation scenario for deflectometry. Typically, the deviation map of the output beam 3 is measured by measuring the parameter tuple of the output position ro and the output angle of the output beam 3. While the output angle is the same for all measurement positions along the optical axis, the output position ro is sensitive to the measurement position, i.e., the distance between the vertex of the lens and the measurement plane. Therefore, some measurement devices instead measure the parameter tuple of the input position of the incident beam and the output angle of the output beam 3. In particular, if the incident beam is collimated, the input position ri is independent (to a very good approximation) of the measurement position and can therefore be measured very reliably. In the thin lens approximation, the input position is equal to the output position. Therefore, substituting the output position for the input position provides a measurement configuration that can be ignored when calculating the wavefront but is much less critical in terms of alignment. However, this measurement principle may not work when the thin lens approximation no longer holds and the input position ri no longer corresponds to the output position ro. Summary of the Invention

[0010] The object of the present invention is to provide a system, method, computer program, or device for solving the above-mentioned problems of the state of the art, in particular to provide an improved method for converting measured values ​​into numerical values ​​with high quality. In particular, it is desirable to convert experimental measured values ​​realized under a first measurement condition into a second measurement condition into numerical values. A further object is to numerically convert a first set of experimental measurement parameters into a second set of measurement parameters.

[0011] According to the invention, this problem is solved by a method, a computer program, an apparatus or a system for converting measurements of a lens into another measurement condition according to the independent claims.

[0012] By combining experimental lens measurements with transformed digital lens measurements, the final measurement result is significantly improved compared to state-of-the-art transformations. The use of digital lens measurements obtained by a digital lens model allows for a significant improvement in transformation compared to transformations based on the assumption of paraxial approximation or thin lens approximation. Because experimental lens measurements are combined with digital lens measurements to obtain a transformed measurement result, lens details, such as the surface characteristics of diffractive lenses, are not lost. This combination brings transformation technology for lenses to a new level. The present invention allows for the solution of all lens transformation problems with high accuracy and can therefore be applied to complex lenses such as diffractive lenses. This solution solves all transformation problems for the measurement of ophthalmic lenses and is therefore particularly advantageous for applications using ophthalmic lenses.

[0013] According to the present invention, this problem is solved by a method for converting lens measurement values, the method comprising the following steps: receiving experimental lens measurement values ​​of a lens from light measurement values ​​of the lens in a first measurement condition; determining a digital lens model representing the lens from the experimental lens measurements; determining a transformed digital lens model representing the lens in a second measurement condition based on the digital lens model; determining transformed digital lens measurements representing the lens measurement values ​​of the lens in the second measurement condition based on the transformed digital lens model; determining digital lens measurements representing the lens measurement values ​​of the lens in the first measurement condition based on the digital lens model; determining a conversion correction based on the digital lens measurements and the transformed digital lens measurements for conversion from the first measurement condition to the second measurement condition; and determining a measurement result of the lens in the second measurement condition based on the experimental lens measurement values ​​and the conversion correction.

[0014] According to the present invention, this problem is solved by a method for converting measurement values ​​of a lens, the method comprising: a receiver for receiving experimental lens measurements of the lens from light measurements of the lens at a first measurement condition; a first lens model estimator for determining a first digital lens model representing the lens from the experimental lens measurements; a second lens model estimator for determining a second digital lens model representing the lens at a second measurement condition based on the first digital lens model; a first measurement simulator for determining first digital lens measurements representing the lens measurements of the lens at the first measurement condition based on the first digital lens model; a second measurement simulator for determining second digital lens measurements representing the lens measurements of the lens at the second measurement condition based on the second digital lens model; a combiner for determining a conversion correction for converting from the first measurement condition to the second measurement condition based on the first digital lens measurements and the second digital lens measurements; and a result calculator for determining a measurement result of the lens at the second measurement condition based on the experimental lens measurements and the conversion correction.

[0015] The calculation of the transformation correction based on the first and second digital lens models is much more accurate than state-of-the-art transformation corrections. By applying this transformation correction to the experimental lens measurements, the true measurements are transformed to the second measurement conditions using a high-quality transformation, so that measurement details are not lost in the measurement results, as would be the case if modeled measurements at the second measurement conditions were simply used. In addition, this approach is less susceptible to errors in determining the lens model compared to using the second digital lens measurements as the measurement results. Because the same errors appear in the first and second digital lens models, these errors are somewhat offset when calculating the transformation correction, which is not the case with state-of-the-art methods that use only the second digital lens measurements without combining them with the experimental lens measurements. Thus, a high-quality transformation correction can be calculated based on the digital lens models, but the true first experimental lens measurements are used to apply the transformation correction so that information from the experimental measurements is not lost. This solution solves the general problem of transforming ophthalmic lenses from the first measurement condition to the second measurement and is therefore particularly advantageous for applications with ophthalmic lenses.

[0016] According to the present invention, this object is solved by a method for converting lens measurements, comprising the following steps: receiving experimental lens measurements of a lens from optical measurements of the lens, the experimental lens measurements comprising an experimental parameter tuple comprising a first experimental parameter and a second experimental parameter; determining a digital lens model representing the lens from the experimental lens measurements; determining converted digital lens measurements comprising digital parameters based on the digital lens model, the first experimental parameter being different from the digital parameter, and the measurement results being based on a measurement parameter tuple comprising the digital parameter and the second experimental parameter.

[0017] The invention therefore allows the transfer of experimental measurements to another parameter space without assuming any approximations, thereby improving the accuracy of the measurements in the other parameter space.

[0018] Further advantageous embodiments are listed below.

[0019] In one embodiment, the conversion correction is a conversion correction factor obtained by the ratio of the (first) digital lens measurement to the conversion / second digital lens measurement. In a preferred embodiment, the conversion correction factor is applied by multiplication or division with the experimental lens measurement. The conversion correction factor is preferably used for wet to dry or dry to wet conversions.

[0020] In one embodiment, the transformation correction is a transformation correction term obtained by the difference between the (first) digital second lens measurement and the transformed / second digital lens measurement. In a preferred embodiment, the transformation correction term is applied by addition or subtraction to the experimental lens measurement. The transformation correction term is preferably used to insert the corneal model into the second measurement conditions.

[0021] In one embodiment, determining a (first) digital lens model representing the lens from experimental lens measurements includes, or the (first) lens model estimator is configured to perform, the following steps: receiving at least one parameter of the lens; and estimating the (first) digital lens model based on the received at least one parameter and the at least one experimental lens measurement. By constraining some parameters of the digital lens model to known values, it is possible to estimate the remaining parameters with a smaller error.

[0022] In one embodiment, the first digital lens model is determined / estimated based on an iterative parameter optimization procedure having multiple iteration steps.

[0023] In one embodiment, one or more, or each, iterative step includes the following steps: a new set of parameter values ​​for the lens for this iterative step is determined; a digital lens model for that iterative step based on the new set of parameter values ​​is determined; digital lens measurements for this iterative step are determined by ray tracing simulation of the digital lens model for that iterative step; and the digital lens measurements for this iterative step are compared with experimental first lens measurements. Preferably, the iterative parameter optimization procedure is terminated when a specific stopping criterion is met. The stopping criterion may be a value that evaluates the difference between the digital lens measurements for the last iterative step and the experimental first lens measurements. The new set of parameters for the last iterative step (and that meets the stopping criterion) is used as the estimated first digital lens model.

[0024] In one embodiment, at least one parameter of the received lens is a constraint in the iterative parameter optimization procedure, i.e. the at least one parameter received is not / will not be changed in the new set of parameters between two subsequent iteration steps. This has the advantage that the risk of the iterative optimization procedure falling into mistakes or local maxima and thus resulting in an incorrect estimator of the set of parameters determining the digital lens model is significantly reduced.

[0025] In one embodiment, the digital lens measurements are determined by ray tracing simulation of the digital lens model. In one embodiment, the (first) digital lens measurements are determined by ray tracing simulation of the (first) digital lens model at a first measurement condition. In one embodiment, the second / transformed digital lens measurements are determined by ray tracing simulation of the second / transformed digital lens model at a second measurement condition.

[0026] In one embodiment, in a first measurement condition, the lens is placed in a liquid, and in a second measurement condition, the lens is placed in a gas, preferably air. That is, experimental lens measurements are obtained by measuring light emitted from the lens placed in a liquid. The liquid is preferably a salt solution, i.e., salt water. Therefore, the measurement results in the second measurement condition represent the measurement results of the lens in a gas. The gas is preferably air.

[0027] In one embodiment, in a first measurement condition, the lens is placed in a gas, and in a second measurement condition, the lens is placed in a liquid. That is, experimental lens measurements are obtained by measuring light emitted from the lens placed in a gas. The gas is preferably air. Therefore, the measurement results in the second measurement condition represent measurement results of the lens in a liquid. The liquid is preferably a salt solution, i.e., salt water.

[0028] In one embodiment, the effect of the cornea model is not considered in a first measurement condition, and the effect of the cornea model is considered in a second measurement condition. That is, experimental lens measurements are obtained by illuminating the lens with incident light without passing through the cornea model and measuring the light exiting the lens. Therefore, the measurement results in the second measurement condition represent measurements of a lens illuminated with incident light that passed through the cornea model before entering the lens. This allows the effect of the cornea model to be numerically considered with high accuracy, even for thick lenses or other lenses for which the paraxial approximation does not hold. It also avoids the difficulty of aligning a physical cornea model with the lens for measurement.

[0029] In one embodiment, the experimental lens measurements, the digital first lens measurements, and / or the digital second lens measurements are measurement maps. The measurement map is preferably a two-dimensional (or more) measurement matrix of the exit light of the lens. In one embodiment, the points of the measurement map represent points on the wavefront of the exit light. In another embodiment, the measurement map comprises (at least) two deviation maps of the exit light of the lens. The two deviation maps are measured along two directions, preferably along two perpendicular directions.

[0030] In one embodiment, the measurement result is a measurement map or wavefront measurement of light exiting the lens. In one embodiment, the measurement result is a measurement map or wavefront measurement of light exiting the lens at a second measurement condition. In one embodiment, the measurement result is a measurement map or wavefront measurement of light exiting the lens including multiple points, each point represented by a measurement tuple including one experimentally measured parameter and one converted digital parameter.

[0031] In one embodiment, the parameters of the lens at the second measurement condition are determined based on the measurement results or measurement map.

[0032] In one embodiment, the measurement is a parameter of the lens.

[0033] In one embodiment, receiving experimental lens measurements for the lens includes illuminating the lens with incident light that interacts with the lens to generate exit light resulting from the interaction of the incident light with the lens; and measuring the exit light to obtain the experimental first lens measurement. Preferably, the incident light is collimated or substantially collimated. In one embodiment, the lens is illuminated with the incident light at a first measurement condition.

[0034] In one embodiment, the (first) digital lens model represents a digital model of the lens at a first measurement condition.

[0035] In one embodiment, the (first) digital lens model represents a digital model of the lens itself, i.e., does not take into account the first measurement condition. In this case, the (first) digital lens model at the first measurement condition is derived from the (first) digital lens model and the digital model at the first measurement condition. For some first measurement conditions, such as in air, the first digital lens model at the first measurement condition and the first digital lens model itself are the same.

[0036] In one embodiment, the system comprises a lens measurer configured to measure exit light of the lens, e.g., at a first measurement condition. Preferably, the lens mapper comprises a light source for illuminating the lens with incident light. The incident light interacts with, and preferably traverses, the lens to generate exit light. Preferably, the lens measurer comprises a light sensor for sensing said exit light to measure experimental lens measurements. Preferably, the experimental lens measurements from the lens measurer are sent to / received by an apparatus for conversion of lens measurements. The lens measurer is preferably a lens mapper.

[0037] In one embodiment, the lens measurement device and the device for conversion are located in the same device.

[0038] In one embodiment, the lens measurement device and the device for conversion (conversion device) are located in different devices. The conversion device can be, for example, a separate device connected to the lens measurement device via a cable. The conversion device can be, for example, a computer with software running on it. The conversion device can also be implemented as a server connected to the lens measurement device via the Internet.

[0039] In one embodiment, the system comprises a lens parameter calculator configured to calculate lens parameters of the lens at the second measurement condition based on the measurement results at the second measurement condition, hi a preferred embodiment, the lens parameter calculator is located in the conversion device.

[0040] In one embodiment, the experimental lens measurements include an experimental parameter tuple including a first experimental parameter and a second experimental parameter. Here, the converted digital lens measurements include digital parameters. At least the first experimental parameter is different from the digital parameter, and the measurement results are based on the measurement parameter tuple including the digital parameter and the second experimental parameter. The parameter tuple preferably has two parameters. However, the parameter tuple can include more than two parameters. Preferably, the experimental lens measurements include a measurement map, each point of the measurement map including one experimental parameter tuple. Preferably, the converted digital lens measurements include a measurement map, each point of the measurement map including at least a digital parameter, preferably a digital parameter tuple including the digital parameter and an additional digital parameter. The additional second parameter can, for example, be equal to a second first parameter. Preferably, the measurement results include a measurement map, each point of the measurement map including one measurement parameter tuple.

[0041] In one embodiment, the first experimental parameter is the position of the incident light on the side of the lens, the second experimental parameter is the angle of the exit light on the surface of the ophthalmic lens, and the digital parameter is the position of the exit light on the side of the lens at a predetermined distance from the lens.

[0042] In one embodiment, the lens is an ophthalmic lens.

[0043] In one embodiment, the lens is a lens other than an ophthalmic lens. [Brief explanation of the drawings]

[0044] [Figure 1] FIG. 1 is a state-of-the-art measurement of an ophthalmic lens in dry conditions. [Figure 2] FIG. 2 is a state-of-the-art measurement of an ophthalmic lens in wet conditions. [Figure 3]FIG. 3 is a state-of-the-art measurement technique for ophthalmic lenses in wet conditions using a corneal model. [Figure 4] Figure 4 shows the state-of-the-art measurement technique for ophthalmic lenses using the polarimetric method. [Figure 5] FIG. 5 is a flow chart illustrating steps of a first embodiment of a method for converting measurements of an ophthalmic lens. [Figure 6] FIG. 6 is a flow chart illustrating the steps of applying the method of FIG. 5 or FIG. [Figure 7] FIG. 7 shows a schematic representation of a first embodiment of an apparatus for converting measurements of an ophthalmic lens. [Figure 8] FIG. 8 shows a schematic representation of a first embodiment of a system for measuring an ophthalmic lens. [Figure 9] FIG. 9 shows a schematic representation of a second embodiment of a system for measuring an ophthalmic lens. [Figure 10] FIG. 10 is a flow chart illustrating steps of an embodiment of a method for converting ophthalmic lens measurements. [Figure 11] FIG. 11 shows a schematic representation of a second embodiment of an apparatus for converting measurements of an ophthalmic lens.

[0045] In the various figures, the same or similar elements are designated by the same reference numerals. DETAILED DESCRIPTION OF THE INVENTION

[0046] Other characteristics and advantages of the invention can be derived from the following non-limiting description, with reference to the drawings and examples.

[0047] FIG. 5 illustrates a first embodiment of a method for measurement conversion for converting experimental lens measurements EXP from a first measurement condition to a second measurement condition. The first and second measurement conditions may represent different measurement media surrounding the ophthalmic lens 1. In a first measurement scenario, the first measurement condition may be the ophthalmic lens 1 placed in a first measurement medium having a first refractive index. The second measurement condition may be the ophthalmic lens 1 placed in a second measurement medium having a second refractive index (different from the first refractive index). The first medium may be a liquid, preferably water, or preferably a salt solution (refractive index of approximately 1.3). The second medium may be a gas, preferably air (refractive index of approximately 1.0) (wet-to-dry conversion) or vice versa (dry-to-wet conversion). Due to the different refractive indices, the optical measurement values ​​in the first measurement condition will be different in the second measurement condition. FIG. 1 illustrates an example of an ophthalmic lens 1 measured in air, while FIG. 2 illustrates an example of an ophthalmic lens 1 measured in liquid. An ophthalmic lens 1 measured in a liquid or wet condition typically means that the ophthalmic lens 1 is placed in a liquid in a cuvette or container. Incident light 2 enters the cuvette, liquid 5, and ophthalmic lens. Exiting light 3' passes through the ophthalmic lens 1, then into the liquid, then into the cuvette, then into the air, where the final exiting light 3 is measured. Thus, only the lens 1 is placed in the liquid, and the light source and / or light sensor are placed outside the liquid. However, in a less preferred embodiment, the light source or light sensor can also be placed in the liquid. In a second measurement scenario, the first measurement condition represents a measurement of the ophthalmic lens 1 without a corneal model 6 (see, for example, FIG. 2 ), while the second measurement condition represents a measurement of the ophthalmic lens 1 with a corneal model 6 (see, for example, FIG. 3 ) (corneal transformation). In the second measurement condition, the incident light 2 traverses the corneal model 6 before reaching the ophthalmic lens 1. Therefore, instead of the original incident light 2, the lens 1 is illuminated with light 2' that is further focused by the corneal model 6. Thus, in a second measurement scenario, the method converts from a first measurement condition with a first type of incident light 2 to a measurement condition with a second type of incident light 2'.The second measurement scenario can be combined with the first measurement scenario, for example the lens 1 is measured in air without a corneal model 6 (see Figure 1) and converted to a second measurement in liquid using the corneal model (see Figure 3).

[0048] 10 shows a second embodiment of a method for measurement conversion of experimental lens measurements EXP to converted lens measurements CON. In this embodiment, the experimental lens measurements EXP are not converted to another measurement condition, but rather to another set of measurement parameters.

[0049] The methods for measurement conversion are described below for both embodiments together. Unless explicitly specified that a particular step applies to only one of the two embodiments, the following description applies to both embodiments.

[0050] In step , experimental lens measurements EXP are received. The experimental lens measurements EXP can be received via a receiver (also referred to as an interface for short). This interface can be a user input, a cable interface, or a wireless interface. The interface can also be an Internet connection. The interface is preferably a digital interface for receiving the experimental lens measurements EXP in digital form. However, the interface can be an analog interface. The interface is preferably connected to the lens measurement instrument 20, so that the interface receives the experimental lens measurements EXP automatically and directly (without human intervention) from the lens measurement instrument 20. However, the interface can also require human intervention when uploading the experimental lens measurements EXP via the interface, for example, from a memory plugged into the interface or from a client device in the case of a server-client configuration.

[0051] The experimental lens measurements EXP represent light measurement values ​​of the ophthalmic lens 1. The light measurement values ​​are preferably measurements of the exiting light 3 that has interacted with the ophthalmic lens 1 after irradiation with the incident light. The light measurement values ​​of the exiting light 3 may also be combined light measurement values ​​of the exiting light 3 and the incident light 2, as in the second embodiment, for example as shown in FIG. 4. The light measurement values ​​are explained in more detail in the context of FIG. 6. The light measurement values ​​are preferably provided by a measurement map of the exiting light 3. The measurement map is preferably configured to determine a wavefront measurement value of the exiting light. The measurement map preferably comprises a plurality of (measurement) points extending in two dimensions. Each point in the plurality of points may comprise one or more measurement parameters. In one embodiment, each point in the plurality of points may comprise a measurement tuple comprising at least two parameters (per point). It is also possible for the measurement map to comprise a plurality of points extending in three (spatial) dimensions. In a less preferred embodiment, it is also possible for the experimental lens measurements EXP to comprise a plurality of points extending in only one (spatial) dimension or in only one measurement point. The experimental lens measurement EXP or measurement map may be determined by combining multiple light measurements. The multiple light measurements may include light measurements resulting from different incident light conditions. The experimental lens measurement EXP may also include multiple light measurements (without combining them into a combined light measurement).

[0052] In a first embodiment, the experimental lens measurement value EXP represents an optical measurement value of an ophthalmic lens at a first measurement condition.

[0053] In a second embodiment, the experimental lens measurement EXP represents a light measurement of the ophthalmic lens comprising an experimental parameter tuple. The experimental parameter tuple preferably comprises a first experimental parameter and a second experimental parameter. The experimental parameter tuple may comprise more than the two mentioned above. Preferably, the experimental lens measurement EXP is a measurement map comprising a plurality of points, each point comprising such an experimental parameter tuple. In a preferred embodiment, the first experimental parameter is the input position ri of the incident light 2. In a preferred embodiment, the second experimental parameter is the output angle θ of the exiting light 3. Thus, in the second embodiment, the light measurement is a mixture of the incident light 2 and the exiting light 3.

[0054] In step S1, a digital lens model is determined / estimated / obtained based on the experimental lens measurements EXP. The digital lens model is a numerical / digital representation of the ophthalmic lens 1. The digital lens model is preferably a three-dimensional representation of the ophthalmic lens's shape. The digital lens model is preferably described by a set of parameters. This set of parameters may, for example, include the curvature or curvatures of its surface, the refractive index of its material, the lens thickness, etc. For more complex lens designs, the set of parameters may be a description of the three-dimensional shape of the ophthalmic lens 1 and its refractive index. The digital lens model is then described by a set of parameter values ​​for the set of parameters. In one embodiment, this is achieved by a parameter estimation / optimization algorithm that receives the experimental lens measurements EXP as input and outputs a best estimator for the set of parameters describing the ophthalmic lens 1. The optimization algorithm is preferably an iterative procedure that optimizes the set of parameters describing the digital lens model in each iteration step. For example, each iteration step includes the steps of: determining a new set of parameter values ​​for the ophthalmic lens for that iteration step; determining a digital lens model for that iteration step based on the new set of parameters; determining digital lens measurements for that iteration step based on the digital lens model for that iteration step; and comparing the digital lens measurements for that iteration step with experimental first lens measurements (yielding a comparison result). The new set of parameters for an iteration step is preferably based on a new set of parameters from a previous iteration step and / or based on the comparison result. The selection of the new set of parameters highly depends on the optimization algorithm used. The selection of the new set of parameters for an iteration step can also be performed randomly. The digital lens measurements for that iteration step are preferably determined by ray tracing simulation of the digital lens model for that iteration step. The comparison result of the iteration step provides an indication of the quality of the new set of parameters for that iteration step. The iteration procedure is preferably repeated until a specific stopping criterion is met.This can be, for example, a maximum number of iteration steps, a threshold for the comparison result, a threshold for the improvement of the comparison result compared to the comparison result of the previous step, or a threshold for another previous iteration step that has been classified as the best performer. In the first iteration step, a new set of parameter values ​​can be initialized randomly or with predetermined values ​​for the set of parameters. Finally, after a stopping criterion is met, the best-performing set of parameter values ​​is used as the digital lens model describing the ophthalmic lens 1. However, it is also possible to determine / calculate / estimate the digital lens model by a different process, i.e., not an iterative process. This can be achieved, for example, by analytical techniques for the estimator.

[0055] In a preferred embodiment, the user can input one or more (known) parameters of the ophthalmic lens 1. Corresponding parameters of the set of parameters describing the digital lens model are then constrained to the inserted values ​​of these known parameters. This significantly improves the estimation quality of the digital lens model.

[0056] The digital lens model preferably describes only the digital lens model without taking into account the measurement conditions of the ophthalmic lens. However, it is also possible for the digital lens model to describe the digital lens model in the (first) measurement conditions in which the ophthalmic lens 1 is measured. In the latter case, the (first) digital lens model needs to provide additional parameters that describe the (first) measurement conditions.

[0057] In step S2, transformed digital lens measurements SIM or SIM2 are determined based on the digital lens model, which represent transformed lens measurements of the ophthalmic lens. The transformed digital lens measurements represent optical measurements of the ophthalmic lens 1 obtained digitally or numerically from the (transformed) digital lens model. The optical measurements are preferably measurement maps as explained in more detail above for the experimental lens measurements (just obtained digitally).

[0058] In the first embodiment shown in FIG. 5, the step S2 of determining transformed digital lens measurements SIM2 based on a digital lens model comprises the following steps:

[0059] In step S21a, a transformed or second digital lens model representing the ophthalmic lens 1 in a second measurement condition is determined / calculated / computed based on the (first) digital lens model. In other words, the digital lens model is transformed into a transformed digital lens model. The transformed digital lens model thus includes a parameter set describing the ophthalmic lens 1 and the second measurement condition. This may be a medium around the ophthalmic lens 1 (wet-to-dry transformation or dry-to-wet transformation) or an additional corneal model (corneal transformation) added to the digital lens model in the transformed digital lens model. The transformed digital lens model for wet-to-dry transformation or dry-to-wet transformation may also take into account the influence of a cuvette around the liquid in the first measurement (for wet-to-dry transformation) or the second measurement condition (for wet-to-dry transformation). However, the cuvette may also be ignored in a non-preferred implementation. The corneal model here describes a digital representation of the patient's cornea. The corneal model is preferably a digital model having one of the configurations defined in the IOL standards mentioned above. The configurations defined in the standards define several lens configurations with different levels of aberration. In a preferred embodiment, the user can select one of several different standardized corneal models. Because the cornea describes the eye's effect on the light incident on the IOL 1, the corneal model is often also referred to as an eye model. The corneal model describes only the effect of the cornea without the effect of the IOL 1. In one embodiment, the corneal model is a standardized model of the effect of the cornea. In one embodiment, the corneal model used can be selected from different standard corneal models, for example, with different levels of spherical aberration. In one embodiment, the corneal model can be a patient-specific corneal model, for example, resulting from separate measurements of the patient's cornea.

[0060] In step S23, a transformed or second digital lens measurement value SIM2 is determined based on the transformed or second digital lens model (determined in step S21). Preferably, the transformed or second digital lens measurement value SIM2 is determined based on a ray tracing simulation of the transformed or second digital lens model. The transformed digital lens measurement value SIM2 preferably has the same settings as the experimental lens measurement value EXP, e.g., a measurement map with the same number of points, the same measurement parameters, etc. However, it is also possible for the transformed digital lens measurement value SIM2 and the experimental lens measurement value EXP to have different settings. Therefore, the description of the settings of the experimental lens measurement value EXP also applies for the transformed / second digital lens measurement value and will not be repeated for the sake of brevity.

[0061] In step S22, a (first) digital lens measurement SIM1 is determined based on the (first) digital lens model in the first measurement condition. If the digital lens model determined in step S1 already represents the ophthalmic lens 1 in the first condition, the digital lens model determined in step S1 can be directly used to determine the (first) digital lens measurement SIM1. Otherwise, the (first) digital lens model is transformed / converted into the (first) digital lens model in the first measurement condition. Preferably, the (first) digital lens measurement SIM1 is determined based on a ray tracing simulation of the (first) digital lens model in the first measurement condition. The (first) digital lens measurement SIM1 preferably has the same settings as the experimental lens measurement EXP and / or the transformation / measurement map of the second digital lens measurement SIM2, e.g., the same number of points, the same measurement parameters, etc. Therefore, the description of the settings of the experimental lens measurement EXP also applies for the (first) digital lens measurement and will not be repeated for the sake of brevity. However, it is also possible that the digital lens measurements SIM1 and the experimental lens measurements EXP and / or the transformed digital lens measurements SIM2 have different settings.

[0062] As shown in FIG. 10 , in the second embodiment, the transformed digital lens measurement values ​​SIM in step S2 are obtained by ray tracing simulation of the digital lens model. The transformed digital lens measurement values ​​SIM preferably include (at least one) digital parameter different from the parameters measured in the experimental lens measurement values ​​EXP, in particular different from the first and / or second experimental parameters. In other words, the transformed digital lens measurement values ​​SIM (digitally) transform the (experimental) measurement results EXP from the parameter space of the experimental measurement results EXP to a different parameter space of the transformed measurement results SIM. The parameter spaces of EXP and SIM distinguish at least one parameter. Different parameters do not mean that the same parameter has different values ​​or realizations, but rather that different parameter values ​​(even if they have the same numerical value) actually describe different physical characteristics of the lens. Preferably, the digital parameter is the output position ro of the output light 3, as shown in FIG. 4 . Preferably, the transformed digital lens measurement values ​​SIM include a digital parameter tuple, preferably including the digital parameter and a further digital parameter. A further digital parameter is preferably the output angle θ of the exiting light 3 as shown in Figure 4. Therefore, a ray tracing simulation of the digital lens model is used to determine the digital parameters of the ophthalmic lens.

[0063] In step S3, a measurement result CON is determined based on the experimental lens measurements EXP and the transformed digital lens measurements SIM or SIM2. The measurement result CON is determined by combining the experimental lens measurements EXP with the transformed digital lens measurements SIM or SIM2 (obtained in step S2). This combination of experimental measurements and simulated digital measurements is the reason for the high quality of the conversion obtained by the present invention.

[0064] In the first embodiment of FIG. 5, step S3 includes the following steps:

[0065] In step S31, a transformation correction COR is determined / calculated / computed based on the (first) digital lens measurement SIM1 and the transformed / second digital lens measurement SIM2. Depending on the transformation performed, the transformation correction may be calculated differently.

[0066] In a first embodiment of the transformation correction, the transformation correction is a transformation correction coefficient COR1 obtained by the ratio (or a function of the ratio) of the transformed digital lens measurement SIM2 and the digital lens measurement SIM.

[0067] COR1=SIM2 / SIM1 (1) Preferably, the transformed / second digital lens measurement SIM2 is divided through the (first) digital lens measurement SIM1. This transformation correction factor COR1 is preferably used for media transformations such as wet to dry transformations or dry to wet transformations. If the transformed digital lens measurement SIM2 and the digital lens measurement SIM1 are measurement maps, the division operation is performed point by point. For a regular measurement map arranged in rows and columns, the point in the i-th row and j-th column of the transformation correction factor COR1(i,j) is obtained by the ratio of the corresponding point in the transformed digital lens measurement SIM2(i,j) and the digital lens measurement SIM1(i,j). COR1(i,j)=SIM2(i,j) / SIM1(i,j).

[0068] In a second embodiment of the transformation correction, the transformation correction is a transformation correction term COR2 obtained by the difference (or a function of the difference) between the transformed digital lens measurement SIM2 and the digital lens measurement SIM.

[0069] COR2=SIM2-SIM1 (2) Preferably, the (first) digital lens measurement SIM is subtracted from the transformed / second digital lens measurement SIM2. This transformation correction term COR2 is preferably used for the corneal transformation.

[0070] Other embodiments of the transformation correction COR are also possible. An advantage of the transformation correction COR obtained based on the (first) digital lens measurement SIM and the transformed / second digital lens measurement SIM2 is that the estimation error of the digital lens model in step S1 is at least partially canceled out, since it appears equally in the (first) digital lens measurement SIM and the transformed / second digital lens measurement SIM2. Therefore, even if there is an estimation error in the digital lens model, the obtained transformation correction is always better than a theoretical transformation correction based on a paraxial approximation.

[0071] In step S32, a measurement result CON of the ophthalmic lens 1 in the second measurement condition is determined / obtained based on the experimental lens measurement EXP and the transformation correction COR (obtained from the transformed digital lens measurement SIM2 in step S31). Thus, by applying the transformation correction COR to the experimental lens measurement EXP, the experimental lens measurement EXP is transformed from the first measurement condition to the second measurement condition.

[0072] In a first embodiment of the conversion correction, a conversion correction factor COR1 is applied to the experimental lens measurement EXP by multiplication or division (or a function of multiplication or division) (depending on how the ratio is calculated). If the conversion correction factor is calculated as in equation (1), then the conversion correction factor COR1 is applied by multiplication and the measurement result is CON=EXP*COR1 (3) is obtained by

[0073] If the experimental lens measurements EXP and the transformation correction factors are a measurement map, a multiplication (or division) operation is performed point-wise.

[0074] In a second embodiment of the transformation correction, a transformation correction term COR2 is applied to the experimental lens measurement EXP by addition or subtraction (depending on how the difference is calculated). If the transformation correction term is calculated as in equation (2), then the transformation correction factor COR1 is applied by addition, and the measurement result is: CON=EXP+COR2 (4) is obtained by

[0075] The obtained measurement result preferably has the same settings as the experimental lens measurement value EXP, and / or the converted / second digital lens measurement value SIM2, and / or the measurement map with the same settings as the (first) digital lens measurement SIM1, e.g., the same number of points and / or the same measurement parameters. Therefore, the description of the settings of the experimental lens measurement value EXP preferably also applies to the measurement result and will not be repeated for the sake of brevity. However, the measurement result may not be the measurement map obtained by Equation (3) or Equation (4), but a parameter determined based thereon, e.g., the lens power. However, the measurement result CON is preferably a measurement map representing the wavefront or deviation map of the ophthalmic lens 1 under the second measurement conditions. This measurement result CON allows all desired parameters of the ophthalmic lens 1 to be determined.

[0076] Step S22 is defined as part of step S2. However, it is equally possible to define S22 as a step of S3. Step S31 is defined as part of step S3. However, it is equally possible to define step S31 as part of step S2.

[0077] In the second embodiment of FIG. 10 , the measurement result CON is obtained by combining at least one parameter of the experimental lens measurements EXP with at least one parameter of the transformed digital lens measurements SIM. The at least one parameter of the experimental lens measurements EXP used in the measurement result CON is preferably a second experimental parameter, preferably the output angle θ. The at least one parameter of the transformed digital lens measurements SIM used in the measurement result CON is preferably a digital parameter, preferably the output position ro. Thus, the measurement result CON combines an accurate measurement of the output angle θ with a transformed measurement of the output position ro. The transformation of the input position ri to the output position ro based on an estimated digital lens model improves the transformation compared to the thin lens approximation, where ri is equal to ro. Therefore, a highly robust measurement of ri and θ can be maintained even for ophthalmic lenses for which the thin lens approximation does not hold.

[0078] The two described transformations of measurement conditions can also be combined. For example, the dry-to-wet transformation can be combined with the corneal transformation as described above. This can be achieved by measuring the ophthalmic lens 1 in air (as shown in Figure 1) and first performing a dry-to-wet transformation to yield a measurement CON1 at wet conditions as shown in Figure 2. This can be achieved by applying the corneal transformation to CON1 (instead of EXP) to obtain a final measurement result CON2 at wet conditions using a corneal model (as shown in Figure 3).

[0079] The steps described may be applied in a different order than the steps described.

[0080] FIG. 6 shows a further optional step in addition to the conversion step S10 described above in FIGS.

[0081] Preferably, the method includes a step S20 of measuring light of the ophthalmic lens 1. Step S20 preferably includes illuminating the ophthalmic lens 1 with incident light 2 and measuring exit light 3 from the ophthalmic lens 1. The exit light 3 results after the incident light 2 interacts with, and preferably passes through, the ophthalmic lens 1. The exit light 3 is preferably measured using a light sensor 20, for example as shown in FIG. 9 . The light measurement of the ophthalmic lens 1 in step S20 results in an experimental lens measurement EXP as described above. The light measurement of the ophthalmic lens 1 may include multiple light measurements, which are combined to obtain the experimental lens measurement EXP.

[0082] The obtained experimental lens measurements EXP are transformed in step S10 described above to obtain the (transformed) measurement results CON.

[0083] The method preferably comprises a step S30 for determining / calculating / calculating at least one lens parameter of the ophthalmic lens 1 based on the transformed measurement result CON.

[0084] Preferably, step S10 and finally step S30 are performed by a processing means. The processing means may be a conventional computer, a dedicated chip, a server connected on the Internet, etc. The processing means may comprise multiple sub-processors, such as are common in multi-kernel machines or server parks. The sub-processors may be separate processing units that perform separate steps of the conversion method S10 and evtl. S20.

[0085] A computer program according to the present invention comprises a plurality of instructions configured to perform the steps of the conversion method S10 described above when the instructions are executed on a processing means. The computer program may be transitory or non-transitory.

[0086] A computer program product according to the present invention stores a plurality of instructions configured to perform the steps of the conversion method S10 described above when the instructions are executed on a processing means.

[0087] Figure 7 shows a first embodiment of an apparatus 10 for measurement conversion. In particular, Figure 7 shows a first embodiment of an apparatus for converting experimental lens measurements of an ophthalmic lens 1 in a first measurement condition to a second measurement condition.

[0088] Figure 11 shows a second embodiment of an apparatus 10 for measurement conversion. In particular, Figure 11 shows a second embodiment of an apparatus for converting experimental lens measurements EXP of an ophthalmic lens 1 in a conversion parameter measurement CON.

[0089] Both embodiments will be described together where applicable and separately where they can be distinguished. The apparatus 10 comprises: a receiving means configured to receive experimental lens measurements EXP of the ophthalmic lens 1 from optical measurements of the ophthalmic lens 1. The receiving means may be a communication interface that communicates directly with the optical sensor 21 of the lens measurement device 20 shown in FIG. 8 or the lens measurement device 20' shown in FIG. 9. The receiving means may be a cable or a wireless communication interface. However, the receiving means may also be a general-purpose communication interface such as a USB connector, an Ethernet connector, or any interface that allows an internet connection for receiving the experimental lens measurements EXP. The receiving means is configured to perform the steps of receiving the experimental lens measurements EXP as described in more detail above.

[0090] A lens model estimator 11 for determining a digital lens model representative of the ophthalmic lens from the experimental first lens measurements EXP. The lens model estimator 11 is configured to perform step S1 described in more detail above.

[0091] A measurement simulator 12 for determining, based on the digital lens model, transformed digital lens measurements SIM or SIM2 representing transformed lens measurements of the ophthalmic lens 1. The lens model estimator 11 is configured to perform step S2, which has been described in more detail above.

[0092] In a first embodiment of the apparatus 10 shown in Figure 7, the measurement simulator 12 comprises: a further lens model estimator 121 for determining, based on the first digital lens model, a second / transformed digital lens model representative of the ophthalmic lens in a second measurement condition. The further lens model estimator 121 is configured to perform step S21, which has been described in more detail above.

[0093] a first measurement value simulator 122 for determining first digital lens measurements representative of lens measurements of the ophthalmic lens in a first measurement condition based on the first digital lens model. The first measurement value simulator 11 is configured to perform step S22 described in more detail above.

[0094] and a second measurement value simulator 123 for determining, based on the second digital lens model, the second digital lens measurement value SIM2 representing the lens measurement value of the ophthalmic lens under the second measurement condition. The second measurement value simulator 123 is configured to perform step S23, which is described in more detail above.

[0095] The apparatus 10 further comprises a combiner 13 for determining a measurement result CON of the ophthalmic lens 1 based on the experimental lens measurements EXP and the transformed digital lens measurements SIM or SIM2. The combiner 13 is configured to perform step S3 described in more detail above.

[0096] In a first embodiment of the device 10 shown in FIG. 7, the combiner 13: a converter 131 for determining a conversion correction COR for conversion from the first measurement condition to the second measurement condition based on the first digital lens measurement SIM1 and the second digital lens measurement SIM2, the converter 131 being configured to perform step S31 described in more detail above.

[0097] a result calculator 132 for determining a measurement result of the ophthalmic lens at the second measurement condition based on the experimental lens measurements and the transformation correction. The result calculator 132 is configured to perform step S32 described in more detail above.

[0098] 8 and 9 show embodiments of a system comprising the conversion device 10 of FIG. 7 or FIG. 11 and a lens measurer 20 and / or lens parameter calculator 30. In FIG.

[0099] Lens measurement instrument 20 is configured to perform step S20, described in more detail above. Lens measurement instrument 20 may be the same device as conversion instrument 10, as shown in Figure 9, or a separate device, as shown in Figure 8. In the latter case, conversion calculator 10 may be a standard computer connected to lens measurement instrument 20 for receiving experimental lens measurements EXP and executing software configured to perform the described conversion. In the embodiment of Figure 8, lens measurement instrument 20' may be equipped with a control chip / software for performing the measurement conversion.

[0100] The lens parameter calculator 30 is configured to perform step S30, which is described in more detail above.

[0101] However, the conversion calculator 10 can also operate without the lens measurement instrument 20, for example as a server-provided service that receives experimental lens measurements EXP over the internet and returns converted measurement results CON and / or calculated lens parameters.

[0102] Step S31 (determining the transformation-corrected COR based on the digital lens measurement SIM1 and the transformed digital lens measurement SIM2) and step S32 (determining the measurement result CON of the lens under the second measurement condition based on the experimental lens measurement EXP and the transformation-corrected COR) can equally include all methods of determining the transformation-corrected COR' based on two of the digital lens measurement SIM1, the transformed digital lens measurement SIM2, and the experimental lens measurement EXP in a first step S31', and determining the measurement result of the lens under the second measurement condition CON' based on one of SIM1, SIM2, and EXP in a second step S32'. For example, in step S31', COR' is determined based on EXP and SIM1 (e.g., COR1' = EXP / SIM1 or COR2' = EXP - SIM). Then, in step S32', CON' is determined based on SIM2 and COR'. This method yields the same mathematical result, as shown in the following equation: CON=EXP+COR2=EXP+SIM2-SIM1=SIM2+EXP-SIM1=SIM2+COR2'=CON', or CON=EXP*COR1=EXP*SIM2 / SIM1=SIM2*EXP / SIM1=SIM2*COR1'=CON'.

[0103] In one embodiment, different measurement conditions can represent different spectral characteristics of incident light 2. In a first measurement condition, incident light 2 having a first wavelength is used, while in a second measurement condition, incident light having a second wavelength or a range of wavelengths different from the first wavelength is desired as the result CON. In this case, COR2 can be used in steps S31 and S32.

[0104] The described embodiments have referred to the example of ophthalmic lenses, it being understood that the invention is equally applicable to other lenses.

[0105] It is to be understood that the invention is not limited to the described embodiments and modifications can be applied without departing from the scope of the claims.

Claims

1. A method for converting measurements of a lens (1), comprising the following steps: receiving, at a receiver, experimental lens measurements (EXP) of the lens (1) from optical measurements of the lens (1); determining (S1) a digital lens model representing said lens (1) from said experimental lens measurements (EXP); determining (S2) transformed digital lens measurements (SIM, SIM2) representing transformed lens measurements of the lens (1) based on the digital lens model; determining (S3) a measurement result (CON) of said lens (1) by combining said experimental lens measurements (EXP) with said converted digital lens measurements (SIM, SIM2), each of said experimental lens measurements (EXP) represents an optical measurement of said lens (1) at a first measurement condition, and each of said converted digital lens measurements (SIM2) represents a lens measurement of said lens (1) at a second measurement condition; or or wherein the experimental lens measurements (EXP) comprise an experimental parameter tuple comprising a first experimental parameter (ri) and a second experimental parameter (θ), and the transformed digital lens measurements (SIM) comprise a digital parameter (ro) different from the first experimental parameter (ri).

2. The experimental lens measurements (EXP) of the lens (1) represent light measurements of the lens (1) in a first measurement condition, and the step (S2) of determining the transformed digital lens measurements (SIM2) based on the digital lens model and the step (S3) of determining a measurement result (CON) by combining the experimental lens measurements (EXP) with the transformed digital lens measurements (SIM2) comprise the following steps: determining (S21) a transformed digital lens model representing the lens (1) in a second measurement condition based on the digital lens model; determining (S22) a digital lens measurement value (SIM1) representing a lens measurement value of the lens (1) in the first measurement condition based on the digital lens model; determining (S23) the transformed digital lens measurements (SIM2) representing lens measurements of the lens (1) in the second measurement condition based on the transformed digital lens model; determining (S31) a conversion correction (COR) based on the digital lens measurement value (SIM1) and the converted digital lens measurement value (SIM2) for conversion from the first measurement condition to the second measurement condition; determining (S32) the measurement result (CON) of the lens (1) under the second measurement condition based on the experimental lens measurement value (EXP) and the conversion correction (COR); The method of claim 1 , wherein the method is implemented by:

3. 3. The method of claim 2, wherein the conversion correction (COR) is a conversion correction factor obtained by a ratio or a function of a ratio between the converted digital lens measurement (SIM2) and the digital lens measurement (SIM1).

4. 3. The method of claim 2, wherein the conversion correction (COR) is a conversion correction term obtained by the difference or a function of the difference between the converted digital lens measurement (SIM2) and the digital lens measurement (SIM1).

5. In the first measurement condition, the lens (1) is placed in a liquid, and in the second measurement condition, the lens (1) is placed in a gas; or Under the first measurement condition, the lens (1) is placed in a gas, and under the second measurement condition, the lens (1) is placed in a liquid. The method according to any one of claims 2 to 4.

6. The method according to any one of claims 2 to 5, wherein the first measurement condition does not take into account the influence of a cornea model, and the second measurement condition takes into account the influence of the cornea model.

7. the experimental lens measurements (EXP) include an experimental parameter tuple including a first experimental parameter (r i ) and a second experimental parameter (θ); the converted digital lens measurements (SIM) include digital parameters (r o ); at least the first experimental parameter (ri) is different from the digital parameter (ro); The method according to any one of claims 1 to 6, wherein the measurement result is based on a measurement parameter tuple comprising the digital parameter (ro) and the second experimental parameter (θ).

8. the first experimental parameter (ri) is the position of the incident light on the side of the lens (1) of the incident light, The second experimental parameter (θ) is the angle of the exiting light (3) on the surface of the lens (1); the digital parameter (ro) is the position of the exiting light (3) on the side of the lens (1) of the exiting light (3), The method according to any one of claims 1 to 7.

9. The step (S1) of determining the digital lens model representing the lens (1) from the experimental lens measurements (EXP) comprises the following steps: receiving at least one parameter of the lens (1); and estimating the digital lens model based on the received at least one parameter and the experimental lens measurements (EXP); The method according to any one of claims 1 to 8, comprising:

10. The digital lens model is determined / estimated based on an iterative parameter optimization procedure having multiple iterative steps, in each step: A new set of parameter values ​​for the lens (1) for that iteration step is determined; determining a digital lens model for that iteration step based on the new set of parameter values; The digital lens measurements for the iterative steps are determined by ray tracing simulation of the digital lens model for the iterative steps; and The method of any one of claims 1 to 9, wherein the digital lens measurements of the iterative steps are compared with the experimental lens measurements.

11. The method of any one of claims 1 to 10, wherein the transformed digital lens measurements (SIM) are determined by ray tracing simulation of the digital lens model.

12. Further steps below: Irradiating the lens (1) with incident light (2) that interacts with the lens (1), and generating emitted light (3) caused by the interaction of the incident light (2) with the lens (1); and The method according to any one of the preceding claims, comprising measuring the exiting light (3) to obtain the experimental lens measurement (EXP).

13. A computer program for the conversion of measurements of a lens (1) storing a number of instructions adapted to carry out the steps of the method according to any one of claims 1 to 11 when executed on a processing means.

14. 1. A device for converting measurements of a lens (1), comprising: receiving means for receiving experimental lens measurements (EXP) of said lens (1) from optical measurements of said lens (1); a lens model estimator (11) for determining a digital lens model representing said lens (1) from said experimental lens measurements (EXP); a measurement simulator (12) for determining transformed digital lens measurements (SIM; SIM1, SIM2) representing transformed lens measurements of the lens (1) based on the digital lens model; a combiner (13) for determining a measurement result (CON) of said lens (1) by combining said experimental lens measurements (EXP) with said converted digital lens measurements (SIM, SIM2); each of said experimental lens measurements (EXP) represents an optical measurement of said lens (1) at a first measurement condition and said converted digital lens measurements (SIM2) represents a lens measurement of said lens (1) at a second measurement condition; or the experimental lens measurements (EXP) include an experimental parameter tuple including a first experimental parameter (ri) and a second experimental parameter (θ), and the transformed digital lens measurements (SIM) include a digital parameter (ro) that is different from the first experimental parameter (ri).

15. a lens mapper, a lens measurement instrument (20) configured to measure the exit light (3) of a lens (1), comprising an optical sensor (21) for sensing said exit light (3) and measuring experimental lens measurements (EXP); and and an apparatus (10) according to claim 14, for receiving experimental lens measurements (EXP) of said optical sensor (21) and outputting measurement results (CON).

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