Method, apparatus and computer program product for determining the sensitivity of at least one eye of a subject

Abstract

Method for determining the sensitivity of at least one eye of a subject based on at least two provided visual acuity-refraction value pairs, wherein at least one of the visual acuity-refraction value pairs is provided by the following steps: - Projecting a target with adjustable target refraction into at least one eye of the subject, the target being designed to verify a predetermined visual acuity; and - Determining a visual acuity limit refraction of at least one eye of the subject corresponding to the given visual acuity by varying the target refraction of the target projected into at least one eye of the subject and recording a subject action which establishes that the identifiability of the target for the subject has changed at the time of the subject action; wherein the sensitivity is determined based on at least one calculated refraction error, and wherein the at least one calculated refraction error is calculated based on a determined optimal refraction of at least one eye of the subject.

Description

[0001] The invention relates to a method, a device, and a corresponding computer program product for determining the sensitivity of at least one eye of a test subject or spectacle wearer. Furthermore, the invention relates to a method and a device for calculating, optimizing, or evaluating a spectacle lens for the at least one eye of the test subject, taking into account the sensitivity of the at least one eye of the test subject determined according to the invention. Furthermore, the invention relates to a method and a device for producing a spectacle lens, as well as a spectacle lens produced using such a method or such a device.

[0002] The published patent application WO 2013 / 104548 A1 describes an optimization of a spectacle lens based on the wavefronts determined by directly calculating light through the eye. The wavefronts are evaluated at a plane in the eye instead of at the vertex sphere (SPC) as is usual, and thus depend on the properties of the eye. With this method, the influence of the cornea and all other individual properties of the eye, such as deviations of the anterior chamber depth or other geometric parameters from the population average, can be directly incorporated into the optimization of the spectacle lens via the wavefronts. The basis for this optimization method is an objective function which, in addition to the calculated wavefront properties (including their higher-order aberrations (HOA)), also depends on target specifications and weightings that may be required for certain properties of the wavefronts in the eye.

[0003] In the state-of-the-art methods for optimizing a spectacle lens, a spectacle lens is optimized by minimizing or maximizing an objective function that incorporates actual values ​​and corresponding target values ​​of at least one imaging property or aberration of the spectacle lens. The at least one imaging property or aberration can represent a direct quantification of a wavefront deviation from a reference wavefront. An example objective function is the function: F=∑i[GR,i(RIact(i)−Rset(i))2+GA,i(AIst(i)−ASPK,set(i))2+…], where: i (i=1 to N) denotes an evaluation point of the spectacle lens; R Ist (i) denotes the actual spherical power or refractive error at the i-th assessment point; R Ist (i) denotes the target spherical power or the target refractive error at the i-th assessment point; Branch Ist(i) denotes the astigmatism or astigmatic error at the i-th assessment point; Branch Soll (i) denotes the target astigmatism or the target astigmatic error at the i-th evaluation point.

[0004] The sizes G R,i , G A,i , ... are weights of the respective imaging property or aberration that are used in the optimization.

[0005] The imaging properties or aberrations of the spectacle lens can be evaluated at the vertex sphere or at an evaluation plane or evaluation surface in the eye, as described, for example, in WO 2015 / 104548 A1.

[0006] It was later recognized that direct quantification of a wavefront deviation in diopters without taking the effective pupil size into account is not the best possible criterion for describing and assessing a spectacle wearer's perception through a spectacle lens because of the depth of field that depends on it. On the basis of this finding, DE 10 2017 007 663 A1 proposes directly taking visual acuity into account in the target or quality function. The visual acuity included in the target or quality function depends on an assignment of at least one imaging property or aberration of a spectacle lens system, whereby the at least one imaging property or aberration can be evaluated on a suitable evaluation surface (e.g. on the vertex sphere or in the eye). The spectacle lens system can consist of at least one spectacle lens (e.g. a lens of refractive glasses).Preferably, however, the spectacle lens system comprises additional components such as a model eye or eye model, which can be based on average values ​​from spectacle wearers or on at least one individual parameter of the wearer's eye. In other words, the spectacle lens system, which underlies the assignment of at least one imaging property or aberration to the wearer's visual acuity, can be a spectacle lens-eye system.

[0007] As described in DE 10 2017 007 663 A1, an exemplary target or quality function, which is derived from the visual acuity V via the assignment of at least one imaging property or aberration ΔU s,j to the visual acuity of the wearer or an average wearer, e.g. have the following structure: Fs=∑i[GS,j,iV(VIact(ΔUs,j(i))−Vset(ΔUs,j(i)))2+…].

[0008] In the above formula, V(ΔU s,j(i)) a function that describes the dependence of visual acuity on at least one imaging property or aberration of a spectacle lens system at the i-th evaluation point (i = 1, 2, 3, ..., N) on an evaluation surface. In other words, V(ΔU s,j (i)) an exemplary assignment of at least one imaging property or aberration of a spectacle lens system to the visual acuity of the subject or spectacle wearer or of an average spectacle wearer when viewing an object through the spectacle lens system. The argument ΔU s,jis generic and can refer to any imaging property or aberration of a spectacle lens system, which describes the effect of the spectacle lens system on a light beam emanating from an object or the difference between the effects of the spectacle lens system on a light beam emanating from an object and on a reference light beam converging on the retina of the eye. One or more imaging properties or aberrations can be included in the objective or quality function and evaluated, where the subscript j,j ≥ 1 denotes the jth imaging property or aberration.

[0009] V Ist (ΔU s,j (i) denotes the visual acuity, which is determined based on the assignment and the actual value of at least one imaging property of the spectacle lens to be calculated (e.g., to be optimized) or evaluated at the i-th evaluation point, and V Soll (ΔU s,j(i)) denotes the corresponding target value of visual acuity.

[0010] The at least one imaging property or aberration can be calculated or evaluated on a suitable evaluation surface. The subscript "s" accordingly stands for any evaluation surface of the at least one imaging property or aberration ΔU s,j The evaluation surface can be, for example, a plane (evaluation plane) or a curved (e.g., spherical) surface. The evaluation surface can be, for example, the vertex sphere or a surface in the eye, e.g., one of the following planes or surfaces: a plane or a (e.g. spherical) surface behind the cornea, the anterior surface of the lens or a plane tangential to the anterior surface of the lens, the back surface of the lens or a plane tangential to the back surface of the lens, the plane of the exit pupil (AP); or the plane of the back surface of the lens (L2).

[0011] The size Gs,iso,iV denotes the weighting of the image property ΔU s,j given visual acuity at the i-th assessment point.

[0012] In this case, for example, one of the visual acuity models described in DE 10 2017 007 663 A1 or any other suitable visual acuity model (which in particular describes the visual acuity as a function of refraction or malrefraction) can be used, preferably in combination with a rule as to how the visual acuity model is to be incorporated into the objective function of an optimization in conjunction with a transformation of the target specifications and weights. It should be noted at this point that, within the scope of this description, a sensitivity metric (as described further below) can preferably be used based on such a visual acuity model (as a functional dependence of a visual acuity value on the refraction / malrefraction). In particular, a preferred sensitivity metric could be used as a derivation of a visual acuity model (i.e. the function of the visual acuity value on the refraction / malrefraction) after the refraction / malrefraction.

[0013] The objective function can also be used to evaluate a spectacle lens, whereby the actual value of at least one imaging property of the spectacle lens to be evaluated is calculated at at least one evaluation point of the spectacle lens to be evaluated and compared with the corresponding target value.

[0014] As is also clear from DE 10 2017 007 663 A1, for the calculation, optimization and / or production of highly individual and high-quality spectacle lenses, knowledge of the so-called sensitivity, i.e. the change in visual acuity with refraction, is particularly helpful. Thus, the assignment of at least one imaging property or aberration of a spectacle lens system to the visual acuity of the wearer, or the function V(ΔU s,j (i)) depend parametrically on the measured initial visual acuity and / or the determined sensitivity of the wearer.

[0015] In the context of the present invention, sensitivity is a (particularly phenomenological) quantity or parameter used in ophthalmic optics and ophthalmology, with which the dependence of visual acuity on a refractive error can be described or specified. The sensitivity of an eye is understood in particular to be the change in the visual acuity of the eye when changing from a refractive error. In particular, sensitivity can be defined as the derivative of visual acuity after the refractive error or as the local derivative of visual acuity after the refractive error for a specific refractive error. The refractive error is a deviation of an effect or refraction applied to at least one eye of the subject during the visual acuity determination from an ideal refraction determined or known for at least one eye. The ideal refraction (hereinafter also referred to as optimal refraction or target refraction) can, for example,It can be determined from a conventional objective and / or subjective refraction measurement. In particular, sensitivity describes how much visual acuity changes when an optical effect or correction applied in front of the eye changes. Sensitivity can be quantitatively described, in particular, using a sensitivity metric and / or a visual acuity model.

[0016] The sensitivity of at least one eye of a test subject can thus be taken into account when calculating and / or creating individual spectacle lenses, in particular when creating multifocal spectacle lenses such as ophthalmic spectacle lenses. Spectacle lenses can have transitions between areas with different optical corrections, for example transitions between a visual point for distance and a visual point for near. These transitions between spectacle lens areas with different optical corrections can be designed in different ways. For example, one speaks of hard transitions or soft transitions, depending on how strong or gentle the change in refraction along the transition is. In the case of highly individual and high-quality spectacle lenses, such a transition (but other areas of the spectacle lens) can in particular influence the sensitivity of at least one eye of the test subject.glasses wearer.

[0017] To determine the sensitivity of at least one eye of a test subject with regard to blur, the presence of at least two applied powers and the visual acuity achieved with each are required. Relevant models and corresponding formulas for calculating the sensitivity are described below. According to the state of the art, to determine the sensitivity, quantized powers are presented to the test subject or to at least one of the subject's eyes (e.g., in steps of 0.25 dpt using conventional trial lens sets). Using a visual acuity chart with optotypes in quantized sizes or quantized visual acuity steps, the corresponding visual acuity is determined for each of the applied powers. Furthermore, the optimal correction (or the optimal refraction or target refraction) must be determined for the test subject in order to convert the applied powers into an incorrect refraction.

[0018] Within the scope of the present invention, it was recognized that the double quantization associated with the conventional method leads to high measurement uncertainty. Furthermore, it was recognized that the conventional method is not only complex but can also be psychologically disadvantageous, since at least one of the subject's eyes is provided with a poorer correction after determining the optimal refraction, and the subject must then perform visual tasks with this poorer correction to determine sensitivity. This sequence is necessary with the conventional procedure, since a defined fog for visual acuity measurement can only be set once the optimal refraction is known.

[0019] The published patent application DE 20 2005 021 287 U1 discloses an aberrometer for the automatic measurement of aberrations of the human eye, for determining subjective visual acuity with simultaneous selection of the best possible spherical-cylindrical correction in different conditions, for eye accommodation, in a second version for investigating the influence of higher-order aberrations on subjective visual acuity and for predicting the results of visual acuity correction using spectacles, custom contact lenses, anterior chamber lenses or laser ablation.

[0020] The published patent application DE 10 2021 202 442 A1 describes a method for determining a sensitivity of at least one eye of a test subject. For this purpose, a subjective refraction result is determined for the at least one eye of the test subject. While determining the subjective refraction result, a first visual acuity of the at least one eye is determined for a first applied refraction. While determining the subjective refraction result, a second visual acuity of the at least one eye is determined for a second applied refraction, wherein the second applied refraction is different from the first applied refraction. The sensitivity of the at least one eye is determined taking into account the first and second visual acuities at the first and second applied refraction.

[0021] The published patent application DE 10 2009 004 866 A1 describes a method for determining the individually required addition of a visual aid for one eye.

[0022] It is an object of the present invention to determine the sensitivity of at least one eye of the subject in an improved manner, particularly simply and quickly, which is required for calculating, optimizing, evaluating, and / or producing highly individualized and high-quality spectacle lenses. Furthermore, it is an object of the present invention to provide a method and a device for calculating, optimizing, evaluating, and producing spectacle lenses that are highly individualized and of high quality due to the consideration of the sensitivity of at least one eye of the subject. It is also an object of the present invention to provide such improved spectacle lenses. These objects are achieved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0023] A first independent aspect of solving the problem concerns a method for determining the sensitivity of at least one eye of a subject based on at least two provided visual acuity-refraction value pairs. At least one of the visual acuity-refraction value pairs is provided by the following steps: - Projecting a target with an adjustable target refraction into at least one eye of the subject, wherein the target is designed to verify a predetermined visual acuity; and - Determining a visual acuity limit refraction of at least one eye of the subject associated with the predetermined visual acuity by varying the target refraction of the target projected into the at least one eye of the subject and detecting a subject action with which it is determined that the identifiability of the target for the subject has changed at the time of the subject action.

[0024] As already mentioned at the beginning, the “sensitivity” (with regard to blur) of at least one eye of the subject is understood to mean the dependence of the visual acuity of at least one eye of the subject on a misrefraction, whereby the “misrefraction” is a deviation of an effect or refraction presented to at least one eye of the subject when determining the visual acuity from an ideal or optimal refraction (target refraction) determined or known for at least one eye.

[0025] Visual acuity is a measure of the (central) visual acuity of at least one eye of a test subject. Visual acuity is usually determined in bright conditions. In particular, visual acuity can be defined as the inverse of the smallest detectable gap in the standard test symbol, the Landolt ring. In humans, visual acuity can be determined using an eye test. For this purpose, the test subject is presented with optotypes, and the test subject's answers indicate whether the test subject has recognized them correctly. Visual acuity depends on which optotypes the test subject can recognize with the set or applied refraction. The optotypes usually have a defined size, brightness, shape, and contrast.

[0026] The optotypes can be displayed on a chart or projected. Using a projector instead of a chart has the advantage of being independent of the testing distance. DIN standards exist for reproducible visual acuity testing. These standards define the standard optotype, the Landolt ring: a ring of defined width with a gap of the same width that can be positioned in eight different directions. By identifying the direction of the gap, the test subject demonstrates that their resolving power is at least as wide as the gap. In practice, however, standardized representations of numbers are usually used as optotypes to facilitate communication. There are also other standardized optotypes, such as the Snellen E, the Pflüger E-Hook, where the middle line is shorter, and others that are suitable for testing visual acuity in illiterate people and preschool children, as well as for non-verbal communication.

[0027] When determining visual acuity, a distinction is made between that with correction, such as glasses or contact lenses, and that without correction. Visual acuity without correction is also referred to as raw visual acuity. The abbreviations "sc" ("sine correctione," Latin for "without correction") and "cc" ("cum correctione," Latin for "with correction") are also commonly used.

[0028] The sensitivity of at least one eye can be determined, in particular, based on a sensitivity metric. By using a sensitivity metric, a sensitivity can be calculated even if the applied refraction values ​​do not have a predetermined distance from each other.

[0029] The sensitivity metric represents the dependence of visual acuity on a (mis)refraction. The distance between two refraction values ​​can be part of a sensitivity metric. The sensitivity metric can be defined in the metric space of refraction values. Each refraction value of the sensitivity metric can be assigned a visual acuity value, or vice versa. Refraction can, for example, be defined in at least a three-dimensional space. For example, a refraction value can usually be described with the coordinates s, c, and α. S can depend on the strength of an optical correction for the sphere, c on the strength of an optical correction for a cylinder, and α on the axial position of this cylinder. In this metric space of refraction values, at least the refraction values ​​for a given first and a given second visual acuity can be determined and are therefore known when calculating the sensitivity.The sensitivity metric can be used to determine sensitivity as a function of two fundamentally different refraction values. By using such a sensitivity metric, the determination of sensitivity is independent of visual acuity measurements at predetermined refraction values, as is common with conventional methods. This makes the determination of sensitivity independent, on the one hand, of visual acuity measurements at at least one predetermined and / or fixed refraction distance from the refraction result (or from the optimal refraction or target refraction), and, on the other hand, of visual acuity measurements at at least one predetermined and / or fixed relative refraction distance between the two applied refractions. This can make it easier for both the refractionist and the subject to obtain the measurement data necessary to determine sensitivity. Examples of a sensitivity metric

[0030] Sensitivity can be calculated using a metric space in which different refraction values ​​represent individual points. A refraction value can be represented three-dimensionally, e.g., using the coordinates s, c, and α. Here, s can depend on the strength of a spherical correction and can be specified, for example, in diopters (which can also be abbreviated to dpt). c can depend on the strength of a cylindrical correction and can be specified, for example, in dpt. α can depend on the axial position of the cylindrical correction and can be specified, for example, in degrees, e.g., from 0 to 180°. Alternatively, other coordinates can be used.

[0031] In the following, it is assumed that the best refraction (also referred to as optimal or ideal refraction in this description), i.e., in particular, a specific objective, subjective refraction result, is denoted by s0, c0, and α0 in this sensitivity metric, and the corresponding visual acuity by v0. When performing the procedure, at least two visual acuity-refraction value pairs are provided. In general, n refractions s i , c i , α i with corresponding visual acuity v i with i ∈ [1, ..., n] and n ≥ 2. At least one visual acuity-refraction value pair of at least one eye of the subject may already be known and provided as a known value pair. Providing includes, in particular, determining and / or measuring.

[0032] In a possible sensitivity metric, the distance of a refraction i from the best refraction in the middle sphere d i and in cylinder a i with equation (1) to: di=(si+12⋅ci)−(s0+12⋅c0)ai=ci2+c02−2⋅ci⋅c0⋅cos(αi−α0) Simple bilinear model of a sensitivity metric with knowledge of a target refraction

[0033] In one embodiment of a bilinear model of a sensitivity metric, the following relationship shown in equation (2) applies to the dependence of visual acuity for each individual measurement for a refraction i. In a simplified case, it can be assumed that the subject cannot compensate for fogging by accommodation. lg vi=md⋅|di|+ma⋅ai+lg v0

[0034] Here m d for the sensitivity at a spherical distance and m afor the sensitivity at a cylindrical distance. Such a separation between a spherical and a cylindrical refraction error can be used to account for the fact that subjects can react very differently to these two components of a refraction error. For example, from data from D. Methling: Bestimmung von Sehhilfen, 2nd ed. Ferdinand Enke Verlag, Stuttgart 1996, it can be determined that, empirically determined for the population average, equations (3) approximately apply: md=21 dpt⋅lg 0.5=−0.601dpt−1ma=21 dpt⋅lg 0.5=−0.301dpt−1

[0035] In general, the above equation (2) has the independent parameters m a , m d , v0. Therefore, the system of equations (2) with three measurements i=1,2,3 of refractions (s1, c1, α1; s2, c2, α2; s3, c3, α3) at three (in particular given) different visual acuity values ​​v1, v2, v3 can be uniquely solved to the system of equations (2a): ma=−1denominator(log(v1|d2|−|d3|)+log(v2|d3|−|d1|)+log(v3|d1|−|d2|)) md=−1denominator(log(v1a3−a2)+log(v2a1−a3)+log(v3a2−a1)) log v0=−1denominator(log(v1a2|d3|−a3|d2|)+log(v2a1−a3)+log(v3a2−a1)) denominator−(a2−a3)|d1|+(a3−a1)|d2|+(a1−a2)|d3|

[0036] For example, a visual acuity measurement can be performed under optimal correction conditions, i.e., at the target refraction (in particular, determined from an objective and / or subjective refraction measurement). Then, for example, for i=3: (s3, c3, α3) = (s0, c0, α0). Under these optimal correction conditions, a3 = a0 = 0 and d3 = d0 = 0.

[0037] Thus, the third of equations (2a) is automatically satisfied. The other equations then take the following form of the system of equations (4): ma=−1denominator(|d2|log(v1 / v0)−|d1|log(v2 / v0)) md=−1denominator(−a2 log(v1 / v0)+a1 log(v2 / v0)) with denominator=a2|d1|−a|d2|

[0038] The system of equations (4) thus provides an example of a simplified bilinear model of a sensitivity metric. The system of equations (4) can be solved with knowledge of the target refraction and two additional refraction values ​​for two additional visual acuity values ​​(for i=1,2). Thus, the sensitivity can be determined from the system of equations (4). The sensitivity describes the dependence of visual acuity on the (mis)refraction. This can be expressed, for example, by the values ​​m a and m d be described.

[0039] If, in addition to the visual acuity v0, more than two additional refractions are measured at given visual acuity values ​​during the target refraction, the sensitivity can be determined more precisely by m d and m acan be determined from all data using a fitting procedure, e.g., the least squares method. Furthermore, outliers can be excluded from the measured data to increase the quality of the sensitivity determination. Simplified linear model of a sensitivity metric with knowledge of a target refraction

[0040] In a further simplified, less individual model of the sensitivity metric, e.g., if only one measurement is available at a misrefraction i=1, a relationship between the spherical and the cylindrical refraction distance can be assumed according to equation (5): md=m ma=f⋅md=f⋅m

[0041] Here, the parameter f can be derived from empirical values ​​and, for example, be a scalar. With the assumption according to equation (5), the system of equations (2) simplifies to the following equation (6): lg vi=m⋅(di+f⋅ai)+lg v0 lg vi=m⋅(ai+f⋅di)+lg v0

[0042] This allows the sensitivity m to be determined from a measurement with a misrefraction i from equation (7): m=ai+f⋅|di|lg vi−lg v0

[0043] A value for f can be derived from relevant literature, e.g., f = 1 / 2 can be set, derived from Applegate, RA, Sarver, EJ, Khemsara: "Are all aberrations equal?", J Refract Surg. 2002, 18: pages 556-562. Or f = 1 can be set, derived from Atchison et al.: "Blur limits for defocus, astigmatism and trefoil", VisionResearch, 2009.

[0044] A linear relationship does not necessarily have to be assumed for equation (5). Alternatively, more complex relationships can be established, and the sensitivity can be derived from them, e.g., depending on the number of independent parameters and / or refraction measurements, by substituting them into appropriately resolved relationships, see equations (4) and (7). The sensitivity can also be derived from a fitting method, such as least squares. Further models of a sensitivity metric with knowledge of subjective refraction

[0045] Sensitivity can also be calculated based on another model. For example, R. Blendowske, "Unaided Visual Acuity and Blur: "A Simple Model," Optometry and Vision Science, Vol. 92, No. 6, 2015, describes models that are characterized by their exceptional simplicity and are based on only a few parameters. Such simple models are particularly suitable for calculating sensitivity and for adaptation when data is scarce, for example, because they can effectively avoid overfitting.

[0046] If a larger number of parameters are individually available, a model with many different parameters is more suitable, as described in the document DE 10 2017 007 663 A1.

[0047] In principle, a variety of different models can be used. The model used in a specific case may depend on the number of visual acuity-refraction value pairs provided or determined. With a sufficient number of visual acuity-refraction value pairs, relatively complex, not necessarily linear models can be developed, whose parameters can be adapted to the measurements.

[0048] The models listed above as examples can be generalized, e.g., by having a function describing visual acuity in the power vector space exhibit contours of constant visual acuity, which correspond to ellipsoids or ovoids containing the point of maximum visual acuity. This can be done analogously to a method presented in A. Rubin and WF Harris: "Closed Surfaces of Constant Visual Acuity in Symmetric Dioptric Power Space", Optometry and Vision Science, Vol. 78, No. 10, 2001. Axial ratios can vary individually within a range of 0.25 to 4. Instead of individually measured values, means, medians, or other estimates of the corresponding model parameters of the population can also be used to calculate visual acuity.

[0049] In one embodiment, a generalization of the above equation (6) leads to different factors f, e.g., equation (8): lg vi={(di,aiort,aiobl)R[m12000m22000m32]RT(di,aiort,aiobi)T}1 / 2+lg v0

[0050] Here, a i ort and a i ort the astigmatism of the refraction error with orthogonal (J0) or oblique (J45) axis positions and are defined as: aiort=−ci2cos(2αi)+c02cos(2α0) and aiobl=−ci2sin(2αi)+c02sin(2α0).

[0051] R represents a rotation matrix, which represents an orientation of an ellipsoid of constant visual acuity in the power vector space of the vectors (di,aiort,aiobl) The eigenvalues ​​m1, m2, m3 denote the sensitivities to fogging in the direction of the first, second, and third column vectors of the rotation matrix R in the power vector space, respectively. Embodiments of models of a sensitivity metric without knowledge of the target refraction

[0052] In some embodiments, the sensitivity can be determined without knowing or determining the target refraction. This can be done by determining an associated refraction or visual acuity limit refraction for several different predefined visual acuity values. In this case, the best refraction or target refraction can be determined from the resulting measurement data. Furthermore, an actually determined best refraction can be verified from the measurement data using a sensitivity metric model.

[0053] It can be assumed that a misalignment, i.e. an intentional refraction, can be compensated for by the subject through accommodation of at least one eye. In this case, a point can be selected in the linear model according to the above equations (2) and (6) at which the visual acuity curve bends. In non-linear models, which result in saturation, the best refraction can be calculated directly as a parameter of the system of equations. For this purpose, the misrefraction, i.e. the distances d i and a i , be replaced by the difference between the best refraction and the set or applied correction.

[0054] The embodiments of models of a sensitivity metric explained above represent examples to illustrate how the sensitivity can be determined within the scope of the present invention.

[0055] The target can be, in particular, a real target (or real object) or a virtual target (or virtual object). In particular, the target can be a real object or a virtually projected object (or a projected virtual object). A target can be realized, for example, by a display (e.g., with one or more lenses and / or with one or more mirrors), by a light-field display, and / or by a badaloptometer (which enables constant magnification despite changes in the effect) and projected into at least one eye of the subject.

[0056] A "virtual object" or "virtual target" is understood, in particular, to be an optical imaging system that generates wavefronts emanating from virtual object points so that they impinge on at least one eye of the subject. The wavefronts generated by the virtual target (each corresponding to a virtual object point) and impinging on at least one eye of the subject can have an adjustable spherical curvature and / or an adjustable cylindrical curvature component, wherein the cylindrical curvature component is preferably adjustable both with respect to the magnitude of the curvature and with respect to the axial position.

[0057] Preferably, the virtual position of the virtual object (target) can be changed so that different accommodation states of at least one eye can be stimulated. In particular, the position of the virtual object can preferably be changed between a position for stimulating distance accommodation and a position for stimulating near accommodation. In addition, the position of the virtual object can preferably be adjusted such that the at least one eye of the subject is no longer able to accommodate the virtual object. In this case, the virtual object (target) can only be perceived by the subject as blurred in all directions. This causes the ciliary muscles to relax. Such a state is referred to as a "foggy" state.

[0058] A target is projected into at least one eye of the subject with an adjustable or variable target refraction (or target effect). This projection can be carried out with the aid of an optical system with which the effect or refraction of the target, i.e., the target refraction, can also be adjusted and / or varied. In the context of this invention, "target refraction" is understood to mean the refraction (applied or brought about by the optical system) (in particular spherical and / or astigmatic refraction) with which the target is projected into at least one eye of the subject or with which the target is presented to at least one eye of the subject.

[0059] A target is particularly considered to be an optical projection into or onto the subject's eye such that this projection creates an image on the retina of the eye that corresponds to the image of a real object at a specific distance from the eye. This specific distance is also referred to here as the virtual position for the virtual target. In other words, a target within the meaning of this description is particularly an image of an object in at least one of the subject's eyes. A backlit slide, for example, can be used as an object. Since in the case of a virtual target the target is not (directly) a real object at the virtual position, a virtual position beyond infinity can also be simulated by appropriately designing the optical system for projection. This then corresponds to wavefronts that converge towards the eye (i.e. in the direction of propagation).

[0060] The projection of a target (in particular a virtual target) into at least one eye of the subject using an optical system is generally known, so it will not be discussed in detail within the scope of the present invention. For example, the projection of a target into at least one eye of the subject is described in K. Nicke and S. Trumm: "Brillengläser der Zukunft - Schritt 3 Der DNEye Scanner," Der Augenoptiker, June 2012, or also in the publication DE 10 2013 000 295 A1.

[0061] The target projected into at least one eye of the test subject is designed to verify a predefined, in particular predetermined and / or known, visual acuity (or a predefined visual acuity level). “Verifying a predefined visual acuity” is understood here in particular to mean that with the aid of the target it can be determined or ascertained (in particular based on a test subject action) whether the at least one eye of the test subject achieves the predefined visual acuity or the predefined visual acuity level. In other words, the target specifies a specific visual acuity or a specific visual acuity level, the attainability of which for the at least one eye of the test subject can be determined (in particular based on a test subject action). In particular, the target is designed (in particular dimensioned) in such a way that a predefined visual acuity or a predefined visual acuity level can be or is assigned to the virtual target.In other words, the target is a target with a predetermined visual acuity or a predetermined visual acuity level. This means that the subject, particularly with ideal refraction or with correction of any ametropia in at least one of the subject's eyes, can recognize or identify the target, provided that at least one of the subject's eyes reaches or has at least the visual acuity or the visual acuity level specified by the target.

[0062] In particular, the target can comprise or be an optotype suitable for determining visual acuity. The dimension or size of the optotype depends on the specified visual acuity or the specified visual acuity level. In particular, the dimension or size of the optotype is selected such that only a subject with a visual acuity that at least corresponds to the specified visual acuity or the specified visual acuity level can recognize and / or identify the optotype.

[0063] The target can also be an image or photo containing two or more details, the recognition of which can each be assigned to a given visual acuity or a given visual acuity level. The image can in particular depict objects (such as a road leading to infinity, a sky, a distant balloon, etc.) which can evoke a feeling of vastness or distance in the viewer. The above-mentioned details contained in the image (such as symbols or strips of fabric on a hot air balloon or the basket of a hot air balloon, clouds or symbols on clouds, lines on a road, symbols on signs at the side of the road, etc.) are expressly included in the term optotype in this description. A particularly suitable symbol as an optotype comprises, for example, one or more concentric rings which merge into a circle when the degree of blur is given.

[0064] The determination of the visual acuity or the visual acuity levels of a target, targets or optotype can be done, for example, by calculating the visual angle of details or by recognizing subjects with known visual acuity characteristics.

[0065] After projecting the target into at least one eye of the subject, a visual acuity limit refraction of at least one eye of the subject is determined, corresponding to the specified visual acuity or the specified visual acuity level.

[0066] In the context of this invention, the "visual acuity limit refraction" or "visual acuity level limit refraction" is understood to mean the refraction or limit refraction at or above which the identifiability of the target for the subject changes. In particular, the "visual acuity limit refraction" or "visual acuity level limit refraction" is understood to mean the refraction or limit refraction at which the subject can identify the target held up to him or the virtual target projected into at least one eye, which is characterized by a predetermined visual acuity or a predetermined visual acuity level. a) starting from a fogged state, can first detect and / or identify the target by varying the refraction (applied or caused by the optical system), or b) starting from an unfogged state, by varying the target refraction (applied or caused by the optical system) it can no longer be detected and / or identified.

[0067] The visual limit refraction is determined by varying the target refraction of the target projected into at least one eye of the test subject and by detecting a test subject action (e.g. a message or input from the test subject, in particular pressing a button or joystick). The target refraction can be varied step by step or, preferably, continuously. The target refraction is preferably varied monotonously and / or continuously. The test subject action signals or establishes that the identifiability of the target for the test subject has changed at the time of the test subject action. In other words, the test subject signals by means of the test subject action that they can recognize or identify the target for the first time, or for the first time or are currently no longer able to recognize or identify it.In particular, the visual acuity limit refraction corresponds to the target refraction or target effect present at the time of the subject's action or applied by the optical system.

[0068] Thus, the sensitivity of at least one eye of the subject is determined taking into account the given visual acuity or the given visual acuity level and the determined associated visual acuity limit refraction.

[0069] The method according to the invention can be carried out particularly in the context of autorefractometric or aberrometric measurements. For this purpose, at least one pair of visual acuity level and the corresponding applied power is recorded. This is achieved by a signal from the subject during the change of the applied power for a target with a defined visual acuity level (i.e., a defined size of an optotype).

[0070] As already mentioned, at least two pairs of visual acuity levels and the corresponding applied power are required to determine sensitivity. Conventional methods, for defined applied powers, determine which visual acuity level the subject achieves with each of these powers (i.e., the size at which the subject can still recognize optotypes). In the method according to the invention, however, the size of the optotype (and thus the visual acuity level) remains constant for at least one of these pairs, and the applied power is changed. The subject signals when they can just about recognize or can no longer recognize an optotype of a defined size.

[0071] In the present invention, in contrast to the prior art, the sensitivity determination does not require the visual acuity level for a specific applied power - with a priori known or a priori unknown misrefraction - but rather the applied power required to achieve a given visual acuity.

[0072] The procedure according to the invention allows the sensitivity to be determined in a simple and rapid manner. In particular, the procedure according to the invention allows the sensitivity (as a subjective measurement) to be determined easily and without great additional effort during a normal objective refraction measurement. In particular, complex measurements during a subjective refraction can be avoided and the psychologically unfavorable step in which the test subject, after determining the best refraction, is provided with a worse correction and is thus expected to solve visual tasks can be omitted. In addition, the procedure according to the invention can advantageously be very well combined with further measurements for determining individual parameters for advanced spectacle lenses (e.g., near measurement, pupillometry, keratography) and for optometric or ophthalmological screening or with measurements for creating reports (such as, for example,Keratography, opacity, pachymetry, tomography, tonometry, or retinal images).

[0073] In a preferred embodiment, before the step of projecting a target designed to verify (or determine) a predetermined visual acuity into at least one eye of the subject, an objective and / or subjective refraction result (in particular a combined refraction result based on an objective and subjective measurement, which also includes further data such as lower and / or higher order aberrations from aberrometry or further biometric data such as corneal shape, lens-retina distance, anterior chamber depth, etc.) of at least one eye of the subject is determined. In the context of the invention, a "refraction result" is understood to mean in particular a determined refraction value. In this way, in contrast to the previous procedure, the determination of the sensitivity can be combined with one or more aberrometric or autorefractometric measurements.In particular, the determination of visual acuity can be combined with the measurement of autorefractometric or aberrometric data in the unaccommodated and accommodated state.

[0074] Preferably, the objective refraction value or the objective refraction result is determined in a fogged state. For this purpose, a target (e.g. an image or photo) can be presented to the test subject or a corresponding virtual target can be projected into at least one eye of the test subject (with the aid of the optical system). This target has an effect that causes the test subject to only see the target blurred (or not completely sharply), thereby relaxing the ciliary muscles of at least one eye of the test subject. Such fogging can, for example, be carried out with an additional effect of approximately 1.25 dpt to 1.5 dpt compared to the optimal refraction of at least one eye of the test subject.

[0075] In a special embodiment, the accommodation state of the eye can also be monitored in order to obtain even more reliable values ​​for the sensitivity.

[0076] Preferably, before the step of varying the target refraction, the target is projected into at least one eye of the test subject with a starting target refraction such that the test subject can only see the target blurred (or not completely sharply) and / or cannot identify it. In other words, a starting target refraction is preferably chosen such that the test subject cannot focus the target or optotype through accommodation. This is achieved in particular by the starting target refraction being shifted towards plus compared to the optimal refraction of at least one eye of the test subject. Only by changing the target refraction towards minus can a state be achieved in which the test subject can see and / or identify the target or optotype. This has the additional advantage that the test subject canoptotype initially and thus the test subject is more likely to perform the action at the right time, namely only when they can actually identify the target or optotype. If, on the other hand, the test subject already knows the target or optotype beforehand or at the start of the measurement (due to a corresponding starting target refraction with which they can see the target or optotype clearly), it was recognized within the scope of the present invention that while such an approach is a possible alternative, it may be inferior to the preferred embodiment mentioned above in terms of accuracy and reliability. This is because a test subject who already knows the target or optotype beforehand often tends to signal the point in time at or from which they can no longer recognize and / or no longer identify the target or optotype after varying the target refraction towards plus, somewhat too late.

[0077] In a further preferred embodiment, the method comprises determining an optimal refraction (target refraction) of the at least one eye of the subject, either before or after the steps of projecting a target, which is designed to verify a predetermined visual acuity, into the at least one eye of the subject and determining a visual acuity limit refraction associated with the predetermined visual acuity of the target. In particular, the method can comprise determining an objective and / or subjective refraction or an objective and / or subjective refraction result. Determining an optimal refraction can also comprise determining a combined refraction or a combined refraction result on the basis of an objective and / or subjective refraction measurement, in which in particular further data such as, for example, low and / or higher order aberrations from the aberrometry orother biometric data such as the shape of the cornea, lens-retina distance, anterior chamber depth, etc.) of at least one eye of the test subject must be taken into account. In this sense, the terms “refraction” and “target refraction” (or “refraction result”) in connection with “optimal refraction” should not be restricted to corrections of low-order aberrations (e.g. sphere and astigmatism), but they can also include higher-order aberrations. Therefore, the term “refraction” could also be understood generally as “correction”. Preferably, the optimal refraction of at least one eye of the test subject is determined in a fogged state, which can be achieved by holding a corresponding target or projecting a corresponding target into the at least one eye of the test subject (see above).Furthermore, according to this preferred embodiment, the visual acuity achieved by the at least one eye of the subject when compensating for any visual impairment of the at least one eye of the subject (e.g., based on a determined optimal refraction) is determined. In other words, the visual acuity is determined after the visual impairment determined by the refraction measurement has been substantially corrected using an optical system or lenses whose effect corresponds to the determined refraction result, i.e., the visual acuity cum correctione (VCC). The visual acuity can be determined using known methods. In particular, the determined optimal refraction and the measured associated visual acuity represent one of the at least two provided visual acuity-refraction value pairs that are used or taken into account when determining the sensitivity.This makes it possible to combine the determination of sensitivity with measurements of objective and / or subjective refraction, or to integrate it into such measurements. Sensitivity can thus be determined quickly and easily, especially in conjunction with other measurements.

[0078] In a further preferred embodiment, the method, preferably after projecting a target designed to verify a predetermined visual acuity into the at least one eye of the subject and after determining a visual acuity limit refraction associated with the predetermined visual acuity of the target, further comprises the steps: - Determining a subjective refraction result or a subjective refraction for at least one eye of the subject; - Determining the visual acuity achieved by at least one eye of the subject when compensating for any visual impairment of at least one eye of the subject on the basis of the determined subjective refraction result.

[0079] The determined subjective refraction and the visual acuity of at least one eye of the subject determined in this subjective refraction preferably represent one (or another, in particular a second, third, fourth, etc.) of the visual acuity-refraction value pairs provided by the method for determining the sensitivity.

[0080] Furthermore, the method preferably comprises determining an optimal refraction of at least one eye of the subject based on the subjective refraction result and an objective refraction result. The optimal refraction is in particular a combined refraction from the subjective and objective refraction results. The determination of a combined refraction result from an objective and subjective refraction measurement is generally known and will therefore not be explained in more detail within the scope of the present description. For example, a combined refraction can be determined by first performing an objective refraction measurement and adjusting the objective refraction result with the aid of a subsequently performed subjective refraction. In particular, it is also possible to determine a combined refraction by calculating an average of the objective and subjective refraction.

[0081] The sensitivity is determined based on at least one calculated refraction error, whereby the at least one calculated refraction error is calculated based on a determined optimal refraction. The optimal refraction can be a determined objective and / or subjective refraction. In particular, the optimal refraction can be a combined refraction of an objective and a subjective refraction.

[0082] Preferably, the refraction error is determined "ex post," i.e., only after projecting a target designed to verify a given visual acuity into at least one eye of the subject, and after determining a visual acuity limit refraction associated with the given visual acuity of the target. Preferably, the refraction error is determined only after determining at least one visual acuity-refraction value pair. Preferably, the refraction error is determined after performing an objective and / or subjective refraction measurement, and in particular after determining an ideal refraction or an ideal refraction result from an objective and subjective refraction measurement. For example, in a preferred embodiment, the following steps can be performed, in particular in the specified order: 1) Carrying out an objective refraction measurement (within the scope of the inventive procedure); 2) Determining at least one pair of visual acuity and refraction values ​​(within the scope of the inventive procedure); 3) Performing a subjective refraction measurement; 4) Determining an ideal refraction or an ideal refraction result from the objective and subjective refraction measurement; and 5) Calculate the refraction errors and the sensitivity based on the result from step 4, i.e. on the basis of the determined ideal refraction or the determined ideal refraction result.

[0083] In a further preferred embodiment, varying the target refraction comprises a monotonous decrease of the target refraction and / or a monotonous increase of the target refraction.

[0084] In a further preferred embodiment, a visual acuity limit refraction of at least one eye of the subject associated with the predetermined visual acuity is determined by decreasing the target refraction and detecting a subject action while decreasing the target refraction, and / or by increasing the target refraction and detecting a subject action while increasing the target refraction, wherein with each subject action it is determined that the identifiability of the target for the subject has changed at the time of the respective subject action. In this way, the "blur point" is approached from different directions. In other words, one blur point can be determined when increasing the target refraction and another blur point when decreasing it. These blur points can be different from one another and can subsequently be averaged.In particular, the sensitivity can be determined by minimizing the squared errors using known metrics from both uncertainty points.

[0085] In a further preferred embodiment, at least two of the provided visual acuity-refraction value pairs are provided by the following steps: - Projecting a first target with a first adjustable and / or variable target refraction into the at least one eye of the subject, wherein the first target is designed to verify a given (predetermined and / or known) first visual acuity (or a given first visual acuity level); - Determining a first visual acuity limit refraction of the at least one eye of the subject, which refraction corresponds to the predetermined first visual acuity (or the predetermined first visual acuity level), by varying (in particular continuously, monotonously and / or constantly varying) the first target refraction of the first target projected into the at least one eye of the subject and detecting a first subject action, which signals or determines that the identifiability of the first target for the subject has changed at the time of the first subject action; - Projecting a second target with a second adjustable and / or variable target refraction into the at least one eye of the subject, wherein the second target is designed to verify a predetermined (predetermined and / or known) second visual acuity (or a predetermined second visual acuity level) that differs from the predetermined first visual acuity (or the predetermined first visual acuity level); - Determining a second visual acuity limit refraction of the at least one eye of the subject associated with the predetermined second visual acuity (or the predetermined second visual acuity level) by varying (in particular continuously, monotonously and / or constantly varying) the second target refraction of the second target projected into the at least one eye of the subject and detecting a second subject action with which it is signaled or determined that the identifiability of the second target for the subject has changed at the time of the second subject action.

[0086] In particular, the sensitivity of at least one eye of the test subject is determined using or taking into account the predefined first visual acuity and the determined associated first visual acuity limit refraction, as well as using or taking into account the predefined second visual acuity and the determined associated second visual acuity limit refraction. Preferably, the first predefined visual acuity or the first predefined visual acuity level of the first target is smaller than the second predefined visual acuity or the second predefined visual acuity level of the second target. For example, the first predefined visual acuity or the first predefined visual acuity level can have the value 0.8 logMar, while the second predefined visual acuity or the second predefined visual acuity level has the value 1.0 logMar. Or, for example, the first predefined visual acuity or the first predefined visual acuity level can have the value 0.4 logMar, while the second predefined visual acuity orThe second predetermined visual acuity level has a value of 0.8 logMar or 1.0 logMar. It is understood that other values ​​can also be selected. The change in the predetermined visual acuity or the predetermined visual acuity level from one virtual target to the next is preferably in the range of 0.2 logMar to 0.7 logMar, preferably in the range of 0.2 logMar to 0.5 logMar, and particularly preferably in the range of 0.2 logMar to 0.3 logMar.

[0087] In a further preferred embodiment, determining a visual acuity limit refraction comprises measuring and / or monitoring an accommodation state of at least one eye of the subject, wherein the accommodation state is measured in particular at least at the time of or immediately after the subject's action. The results of such a measurement or monitoring can be used to control the process (e.g., aborting or repeating individual steps in the event of unwanted accommodation (e.g., exceeding a certain threshold). The measurement can be performed continuously or only during or immediately after the subject's action. Furthermore, an accommodation state (sphere, cylinder, low- or high-order aberrations), ideally measured at the time of the subject's action, can be included in the calculation of the sensitivity or the refraction error.For example, the amount of accommodation can be subtracted from the distance refraction value by the amount of the applied power. Expressed in formulas, the simplest case is the following: Sensitivity represents the visual acuity V as a function f of the refractive error F, i.e. V = f(F). Here, the refractive error is F. - without accommodation the difference between the actually applied effect T and the ideal effect I, i.e. F = T - I; and - with accommodation the difference between the actually applied effect T and the currently measured effect G a , so F = T - G a .

[0088] If there is a deviation D between the ideal effect I and the measured effect with a relaxed eye (effect G0), then: I = G0 + D. Accordingly, in this situation F = T - (G0+D) or F = T - (G a+D). For spherical values, this formula can be used as described. For cylindrical values, the cross-cylinder formula should be used accordingly. Zernike coefficients (also for higher-order aberrations) or power vectors can be used analogously.

[0089] Alternatively or additionally, determining a visual acuity limit refraction comprises measuring and / or monitoring a pupil size (e.g. pupil radius) of at least one eye of the test subject, wherein the pupil size is measured in particular at least at the time of or immediately after the test subject's action. The pupil size can be measured, for example, using a camera which is part of an autorefractometer or aberrometer, or using a separate camera. The pupil size measured at the time of the test subject's action (i.e. at the point of blur) or shortly before or after (e.g. up to 2 seconds before the point of blur is reached) can be used to determine the sensitivity of the at least one eye of the test subject to blur.In particular, the measured pupil size can be used to quantify the blur of the image on the retina, preferably with the help of a suitably parameterized eye model and a known additional fogging. Instead of a complete eye model, a simpler description can also be used. For example, the angle at which the disc of confusion of a blurred point can be observed for a given pupil and a given additional fogging can be calculated (see, for example, WO 2019 034525 A1). Within the framework of such a visual acuity model, the sensitivity can be determined as the deterioration in visual acuity per angle of the disc of confusion.

[0090] In a further preferred embodiment, in order to determine a visual acuity limit refraction, the test subject is given a visual task with at least two, preferably at least three, particularly preferably at least four, in particular four or eight, possible different answers, wherein the test subject can answer the visual task based on the test subject’s action. A “visual task” is understood here in particular to be a task which has a predetermined and thus verifiable solution. In particular, the visual task is therefore a verifiable task (i.e. a visual task whose solution is known and thus verifiable). In other words, the test subject’s action goes beyond simply communicating the recognizability or identifiability of the target. The visual task is preferably based on a forced choice, i.e. the test subject is “forced” to make a selection from several or more possible answers.to make at least two or a plurality of possible answers, whereby the correct answer is preferably predetermined or known. In the context of the invention, such a visual task is referred to as a "forced choice" visual task. The visual task can be solved or a selection can be made, for example, with the help of a joystick which the test subject can use to move in different directions. For example, the visual task can consist of the test subject having to identify the position or direction of the gap in an optotype with the help of a joystick. If the optotype is a Landolt ring, for example, there are eight possible positions and therefore eight possible answers for the test subject. It goes without saying that, in principle, other optotypes can also be used, so that the test subject has, for example, two, three, four, five, six, seven, etc. possible answers.In this way, the procedure becomes more accurate and reliable than if the test subject only has to give unchecked feedback (e.g. “yes” or “no” or “recognizable” or “not recognizable”).

[0091] In a further preferred embodiment, before the step of determining a visual acuity limit refraction, first aberrometric data of the at least one eye of the subject are acquired, preferably for a distance accommodation state and / or a foggy state of the at least one eye of the subject and in particular at a first brightness. Furthermore, the method preferably comprises acquiring second aberrometric data of the at least one eye of the subject for a near accommodation state of the at least one eye of the subject, in particular at a second brightness whose value is lower than that of the first brightness. The acquisition of second aberrometric data preferably takes place before the step of determining a visual acuity limit refraction. In the context of this description, “aberrometric data” (or“aberrometric measurements”) are understood to mean data describing the imaging errors of an eye (measurements to obtain this data), the information content of which corresponds at least to the term of the order “defocus” when represented with Zernike coefficients, but ideally includes higher orders (e.g. coma and spherical aberrations). In particular, the “aberrometric data” can also comprise or be (purely) autorefractometric data. In particular, the acquisition of aberrometric data also comprises the acquisition of (purely) autorefractometric data (i.e. sphere and / or cylinder and / or axis). The first and second brightnesses are preferably each a brightness in the regime of mesopic vision (preferred luminance in the range of approximately 0.003 cd / m²). 2 up to about 30 cd / m 2 , particularly preferably in the range of about 0.003 cd / m 2 up to about 3 cd / m 2 , more preferably in the range of about 0.003 cd / m 2up to about 0.3 cd / m 2 , most preferably in the range of about 0.003 cd / m 2 up to about 0.03 cd / m 2 ). Brightness is always understood to mean the brightness at the location of the eye or the brightness that can be perceived by the eye.

[0092] Together with the acquisition of first aberrometric data and / or the acquisition of second aberrometric data (i.e., in particular for the first or second brightness and for the first or second accommodation state), first or second pupillometric data for at least one eye of the subject can also be acquired. The term "pupillometric data" (or pupillometric measurements) refers to information on the size of the pupil (or measurements used to obtain this data), which includes at least one size specification (e.g., in the form of a radius), but can also reflect the shape of the pupil in a more complex form. In addition, the pupillometric data can contain information on the position of the pupil (e.g., relative to the corneal vertex or the optical axis of the eye).

[0093] A further aspect for solving the problem relates to a method for calculating, optimizing or evaluating a spectacle lens for at least one eye of a test subject or spectacle wearer, taking into account the sensitivity of the at least one eye of the test subject, wherein the sensitivity of the at least one eye of the test subject is determined by the method according to the invention described herein.

[0094] In particular, the method for calculating, optimising or evaluating a spectacle lens for at least one eye of a subject may comprise the following steps: a) providing an assignment of at least one imaging property or aberration of a spectacle lens system to the visual acuity of the spectacle wearer or of an average spectacle wearer when viewing an object through the spectacle lens system; b) determining or specifying an objective function for the spectacle lens to be calculated or evaluated, in which the assignment from step (a) is to be evaluated; c) Calculating or evaluating the spectacle lens to be calculated or evaluated by evaluating the objective function, whereby the objective function is evaluated at least once.

[0095] The assignment of at least one imaging property or aberration of a spectacle lens system to the visual acuity of the wearer can depend parametrically on the measured initial visual acuity and / or the measured sensitivity of the wearer. Calculating and / or optimizing the spectacle lens can, in particular, comprise minimizing or maximizing the objective function. The method for calculating, optimizing, or evaluating a spectacle lens can further comprise calculating at least one light beam emanating from the object for at least one viewing direction using wavefront calculation, ray calculation, or wavefield calculation through the spectacle lens system and / or through the spectacle lens to be calculated or evaluated up to an evaluation surface in the spectacle lens system.Furthermore, the method for calculating, optimizing, or evaluating a spectacle lens can comprise calculating the difference between the light beam emanating from the object at the evaluation surface and a reference light beam converging on the retina of a model eye, and determining the at least one imaging property or aberration based on the calculated difference. The calculation of at least one light beam emanating from the object is preferably carried out by means of wavefront calculation, wherein the calculation of the difference present at the evaluation surface comprises calculating the wavefront difference between the wavefront of the light beam emanating from the object and the wavefront of the reference light beam converging on the retina, wherein the wavefront difference is calculated at the evaluation surface.Furthermore, the method for calculating, optimizing or evaluating a spectacle lens can comprise assigning a geometric-optical angle and / or a quadratic shape in the space of geometric-optical angles to the calculated wavefront difference, wherein the at least one imaging property or aberration depends on at least one component of the geometric-optical angle and / or the quadratic shape.

[0096] Alternatively or additionally, the method for calculating, optimizing or evaluating a spectacle lens may comprise the following steps: - Specifying a first surface and a second surface for the spectacle lens to be calculated or optimized; - Determining the path of a principal ray through at least one viewing point of at least one surface of the spectacle lens to be calculated or optimized into a model eye; - evaluating an aberration of a wavefront resulting along the principal ray from a spherical wavefront incident on the first surface of the spectacle lens at an evaluation surface in comparison with a wavefront converging at a point on the retina of the eye model; - iteratively varying at least one surface of the spectacle lens to be calculated or optimized until the evaluated aberration corresponds to a specified target aberration.

[0097] A further aspect of solving the problem relates to a method for producing a spectacle lens, comprising: - Calculating or optimising a spectacle lens according to the method according to the invention for calculating or optimising a spectacle lens; and - Manufacturing the calculated or optimized spectacle lens.

[0098] The invention also provides a computer program product, in particular in the form of a storage medium or a data stream, which contains program code that, when loaded and executed on a computer, is designed to carry out a method according to the invention, in particular for determining the sensitivity of at least one eye of a test subject and / or for calculating, optimizing or evaluating a spectacle lens and / or for producing a spectacle lens. In other words, the invention provides a computer program product that comprises machine-readable program code that, when loaded onto a computer, is suitable for carrying out the method according to the invention described above. In particular, a computer program product is to be understood as a program stored on a data carrier. In particular, the program code is stored on a data carrier.In other words, the computer program product comprises computer-readable instructions which, when loaded into a memory of a computer and executed by the computer, cause the computer to perform a method according to the invention.

[0099] In particular, the invention provides a computer program product which contains a program code which is designed and configured, when loaded and executed on a computer, to carry out a method according to the invention for determining the sensitivity of at least one eye of a subject and / or a method according to the invention for calculating, optimizing or evaluating a spectacle lens and / or a method according to the invention for producing a spectacle lens.

[0100] A further independent aspect for solving the problem relates to a device for determining the sensitivity of at least one eye of a subject, comprising: - a target providing device for providing a target designed to verify a predetermined visual acuity; - an optical system for projecting the target with a target refraction into at least one eye of the subject, wherein the optical system is designed to adjust and vary the target refraction; - a feedback unit for detecting a subject's action in order to determine that the identifiability of the target for the subject has changed at the time of the subject's action, in particular as a result of varying the target refraction of the target projected into at least one eye of the subject with the aid of the optical system; and - a visual acuity limit refraction determination unit for determining a visual acuity limit refraction of the at least one eye of the subject associated with the predetermined visual acuity, wherein the visual acuity limit refraction determination unit is designed to detect (in particular to determine and store) the target refraction effected by the optical system at the time of the subject's action; and - an evaluation unit which is designed to determine the sensitivity on the basis of at least one misrefraction calculated on the basis of a determined optimal refraction.

[0101] The target provision device can comprise, for example, an electronic display or a digital screen. In particular, the display can be designed so that individual pixels of the display, different areas, or different components of the display can be controlled individually, in particular to display composite optotypes. For example, partial segments of a ring can be displayed, with which Landolt-C optotypes with differently directed openings can be generated or displayed. Alternatively or additionally, complete optotypes such as letters or numbers can also be designed as complete and, in particular, switchable LCD elements.

[0102] The target delivery device can, for example, comprise a folding, sliding, or rotating mechanism, for example, magnetic or motorized, with which different targets or images can be displayed and / or swapped. The targets or images can also be partially transparent and contain only areas that are to be displayed in addition to another image.

[0103] Transparent, backlit images can also be designed so that certain parts of the image are only visible when one or more specific light sources (e.g. in otherwise shadowed areas or with specific wavelengths) are switched on or off.

[0104] The optical system is arranged in particular between the at least one eye of the test subject and the target provision device or the provided target. The optical system is designed to apply or bring about different target effects and thus influence the detectability of the target for the at least one eye of the test subject. In the simplest case, the optical system is designed to provide different spherical effects. This can be achieved, for example, by arranging one or more spherical lenses, for example in the form of a Badal system. Alternatively or additionally, one or more adaptive lenses, optionally in combination with conventional lenses, can be used or arranged. In more complex cases, the optical system can be designed to apply or bring about different cylindrical effects or higher-order effects in addition to or instead of spherical effects.

[0105] The optical system can have at least one lens with a spherical power and / or at least one lens with a cylindrical power. For example, the optical system can comprise a magazine with a plurality of spherical lenses and / or cylindrical lenses, each having different spherical or cylindrical powers, and wherein the magazine is designed and arranged such that individual spherical lenses or individual cylindrical lenses and / or a combination of several spherical lenses or cylindrical lenses of the magazine can be selected and used to project the target. The optical system can, for example, also have an Alvarez lens system. In other words, the subject is presented with a target (or a projected or virtual target) through which the subject sees the target or virtual target. The optical system can, for example,also comprise two lenses rotatable relative to one another, each with at least one cylindrical component in its power. In particular, the optical system can comprise two cylindrical lenses with interlocking, facing, rotationally symmetrical surfaces, preferably planar surfaces. The optical system can also comprise a positive and a negative cylindrical lens with opposite, identical powers, which are mounted so as to be rotatable relative to one another and preferably displaceable relative to one another.

[0106] Furthermore, the visual angle of the target may change when different effects are applied through the optical system. This can either be prevented by a corresponding design of the optical system or determined mathematically and compensated for in the display. To do this, the visual angle must be determined as a function of the applied effect and a visual acuity value must be assigned on the basis of this actual visual angle. This can be achieved, for example, by determining the magnification of the optical system and a correspondingly reduced display of the target. Alternatively, the optical system can be calibrated with the aid of a camera by directly measuring the size of the target using a camera positioned instead of at least one of the test subject's eyes (and looking into the optical system).

[0107] The test subject's feedback or the test subject's action can in principle be given verbally. In this case, a user can remember the state of the optical system during the feedback or test subject's action and / or pass the feedback directly on to the feedback system. However, this variant is prone to errors and causes delays. Therefore, direct feedback from the test subject to the feedback system is preferred. In the simplest case, the feedback system can comprise a button for this purpose. In a further preferred embodiment, the feedback system can also comprise two buttons ("+" and "-"), three buttons ("+", "-" and "OK"), four buttons (e.g. "+", "-", "OK" and "Cancel"), etc., and / or a joystick. Alternatively or additionally, the feedback system can comprise a microphone for recording verbal utterances from the test subject.

[0108] In a preferred embodiment, the evaluation unit is designed to determine the sensitivity of at least one eye of the subject based on at least two provided visual acuity-refraction value pairs. The visual acuity limit refraction determination unit can be a component of the evaluation unit.

[0109] In other words, the evaluation unit can include the visual acuity limit refraction determination unit.

[0110] In a further preferred embodiment, the device comprises an autorefractometric or aberrometric measuring unit for determining one or more objective refractions of the at least one eye of the subject, wherein the autorefractometric or aberrometric measuring unit is preferably designed to measure and / or monitor an accommodation state of the at least one eye of the subject. Furthermore, the autorefractometric or aberrometric measuring unit can comprise a camera for determining a pupil size (in particular a pupil radius) of the at least one eye of the subject. Alternatively or additionally, the autorefractometric or aberrometric measuring unit can comprise a calibration camera for calibrating the optical system.The camera for determining pupil size and the calibration camera can also be implemented in a single camera that combines both functions (determining pupil size and calibrating the optical system).

[0111] In a further preferred embodiment, the device comprises a pupil size measuring unit (in particular a camera) for determining a pupil size (in particular a pupil radius) of at least one eye of the subject. Alternatively or additionally, the device may comprise an illumination device for generating at least two brightness levels. Alternatively or additionally, the device may comprise a pupillometer device configured to acquire first pupillometric data of the at least one eye at a first brightness level and to acquire secondary pupillometric data of the at least one eye at a second brightness level.

[0112] A further aspect for solving the problem relates to a device for calculating, optimizing or evaluating a spectacle lens for at least one eye of a test subject, taking into account the sensitivity of the at least one eye of the test subject, comprising a device according to the invention for determining the sensitivity of the at least one eye of the spectacle wearer.

[0113] The device for calculating, optimising or evaluating a spectacle lens can in particular comprise the following components: - a surface model database for specifying a first surface and a second surface for the spectacle lens to be calculated or optimized; - a main ray determination module for determining the path of a main ray through at least one viewing point of at least one surface of the spectacle lens to be calculated or optimized into a model eye; - an evaluation module for evaluating an aberration of a wavefront resulting along the principal ray from a spherical wavefront impinging on the first surface of the spectacle lens at an evaluation surface in comparison with a wavefront converging at a point on the retina of the eye model; and - an optimization module for iteratively varying the at least one surface of the spectacle lens to be calculated or optimized until the evaluated aberration corresponds to a predetermined target aberration.

[0114] A further aspect of solving the problem relates to a device for producing a spectacle lens, comprising: - calculation or optimization means designed to calculate or optimize the spectacle lens according to a method according to the invention for calculating or optimizing a spectacle lens; and - Processing means designed to process the spectacle lens according to the result of the calculation or optimization.

[0115] A further aspect for solving the problem relates to a spectacle lens which was produced by a method according to the invention for producing a spectacle lens and / or by means of a device according to the invention for producing a spectacle lens.

[0116] Furthermore, the invention provides a use of a spectacle lens produced by the manufacturing method according to the present invention, in particular in a preferred embodiment, in a predetermined average or individual usage position of the spectacle lens in front of the eyes of a specific spectacle wearer for correcting a visual impairment of the spectacle wearer.

[0117] In particular, a computer-implemented method according to the invention can be provided in the form of ordering and / or industry software. In particular, in such a method, the data required for the calculation and / or optimization and / or production of a spectacle lens can be recorded and / or transmitted.

[0118] A device and / or a system according to the invention, e.g., for ordering a spectacle lens, can in particular comprise a computer and / or data server designed to communicate via a network (e.g., the Internet). The computer is in particular designed to execute a computer-implemented method, e.g., ordering software for ordering at least one spectacle lens, and / or transmission software for transmitting relevant data, and / or determination software for determining relevant data, and / or calculation or optimization software for calculating and / or optimizing a spectacle lens to be manufactured, according to the present invention.

[0119] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in isolation or in other combinations without departing from the scope of the present invention.

[0120] The statements made above or below regarding the embodiments of the first aspect also apply to the above-mentioned further independent aspects and in particular to preferred embodiments in this regard.

[0121] In particular, the above and below statements regarding the embodiments of the other independent aspects also apply to an independent aspect of the present invention and to preferred embodiments thereof.

[0122] In the following, individual embodiments for achieving the object are described by way of example with reference to the figures. In some cases, the individual embodiments described have features that are not absolutely necessary to carry out the claimed subject matter, but which provide desired properties in certain applications. Thus, embodiments that do not have all the features of the embodiments described below are to be regarded as falling within the scope of the described technical teaching. Furthermore, to avoid unnecessary repetition, certain features are only mentioned in relation to individual embodiments described below. It is pointed out that the individual embodiments should therefore not only be considered in isolation, but also in conjunction with one another.Based on this overview, those skilled in the art will recognize that individual embodiments may also be modified by incorporating one or more features of other embodiments. It is noted that a systematic combination of the individual embodiments with one or more features described with reference to other embodiments may be desirable and useful and should therefore be considered and considered to be encompassed by the description. Short description of the drawings Fig. 1 shows an example image or photo that gives the viewer a sense of distance; Fig. 2 shows the picture or photo of Fig. 1 with exemplary optotypes integrated into or superimposed on the image; Fig. 3 shows a diagram of the range of accommodation depending on age (Duane curve) Detailed description of the drawings

[0123] The Fig. Figure 1 shows an exemplary image or photograph containing a hot air balloon and a road, giving the viewer a sense of distance. Such an image can, for example, be projected as a target (in particular as a virtual target) into at least one eye of a subject within the scope of the present invention, in order to perform an objective refraction measurement, for example, in a foggy state in which the subject only perceives the image or details of the image in a blurred manner.

[0124] The Fig. 2 shows the picture or photo of Fig. 1 with exemplary optotypes integrated into or superimposed on the image, namely numbers of different sizes arranged in roadside signs. Each of these optotypes has a predetermined visual acuity or a predetermined visual acuity level. Within the scope of the method according to the invention, the image with the optotypes is provided with an adjustable target refraction using an optical system. This target refraction is varied by means of the optical system, and the test subject signals by means of a test subject action that the identifiability of the target or optotypes has changed for them at the time of the test subject action. In this way, visual acuity-refraction value pairs can be provided in order to determine the sensitivity of at least one eye of the test subject.

[0125] One or more targets can be presented to the subject or projected as virtual targets into at least one of the subject's eyes. Depending on the design, two or more targets can be used, which may also be identical in content.

[0126] For example, a first target can be an image that conveys a sense of distance (see e.g. Fig. 1), a second target contains one or more optotypes of a specific size, and a third target contains one or more optotypes of a different size. Optotypes are understood to be all symbols, images, and the like that can be identified by a subject.

[0127] Alternatively, the first target may be an image that conveys a sense of distance, while the second and third targets may be identical in content and may contain one or more optotypes, each in one of two sizes.

[0128] Alternatively, all three targets may be identical and represent an image that conveys a sense of distance, but contain one or more details whose recognition can be assigned to a visual acuity level. These details are explicitly included in this description by the term optotype. Examples of such details are in an image containing, for example, a hot air balloon and a road: - Symbols or fabric panels on the hot air balloon as well as the basket of a hot air balloon, - clouds or symbols on clouds, - lines on a road, and / or - Symbols on roadside signs.

[0129] A particularly suitable symbol, for example, has one or more concentric rings that merge into a circle at a given blur.

[0130] In contrast to the prior art, the present invention does not determine the visual acuity level for a specific applied power, but rather the applied power required to achieve a given visual acuity. Furthermore, the determination of visual acuity can be combined with the measurement of autorefractometric or aberrometric data in the unaccommodated and accommodated states. In a special embodiment, the eye's accommodation state can also be monitored to obtain even more reliable sensitivity values. A. Procedure according to an exemplary embodiment without subjective refraction

[0131] An examination of the test subject can take place as follows: 1) The subject's objective refraction value is determined using an autorefractometric or aberrometric measurement. For this purpose, a first target is presented to the subject. A suitable optical system is used to apply an initial effect that prevents the subject from seeing the target in full focus, thereby inducing relaxation of the ciliary muscles. 2) A second target is now placed in front of the subject and, using the optical system, a second power is applied which makes it impossible for a subject with high visual acuity to recognize the optotype(s). This is achieved by selecting a spherical power corresponding to the mean sphere or one of the two principal sections of the objective refractive value plus an additional positive spherical power. The latter power - often called "foggy power" - is chosen because the subject cannot compensate for such a power through accommodation. To determine the speed at which the applied power is changed, standard values ​​based on averages for a large number of subjects can be used. For example, it is known that visual acuity is approximately halved with a fogging of 0.5 dpt spherical or 1 dpt cylindrical.Preferably, the target refraction is varied at a rate between 1 / 16 dpt per second and 1 / 2 dpt per second. The additional spherical power may also depend on the pupil measured with the aberrometry unit. For example, it may be inversely proportional to the pupil radius, so that subjects with smaller pupils are preferably fogged with a stronger power than subjects with larger pupils, to ensure that the blur perceived by all subjects is similar. 3) Alternatively, a sphero-cylindrical power can be applied. For example, a cylindrical power can be adopted for the optical system from the objective refraction, and an average objective refraction value can be subjected to an additional positive spherical power. Alternatively or additionally, the objective refraction value can be subjected to an astigmatic offset (so-called astigmatic fogging). The optical power is then slowly adjusted (e.g., between 1 / 16 dpt per second and 1 / 2 dpt per second) toward optimal or objective refraction (by varying the spherical and / or astigmatic power). 4) As soon as the subject can recognize the optotype of the second target by changing the power, they indicate this (e.g., by pressing the "OK" button). If necessary, they can adjust the limiting power themselves (e.g., using the "+" and "-" buttons) and confirm it (e.g., also by pressing the "OK" button). The adjusted power is stored as the "visual acuity limiting power" or "visual acuity limiting refraction" upon detection of the second target. 5) The subject is presented with the third target 6) The optical power is now slowly changed (e.g. between 1 / 16 dpt per second and 1 / 2 dpt per second) towards the optimal or objective refraction value (by varying the spherical and / or astigmatic power) 7) As soon as the subject can recognize the optotype of the third target by changing the power, they indicate this (e.g., by pressing the "OK" button). If necessary, they can adjust the limiting power (e.g., using the "+" and "-" buttons) and confirm it (e.g., also by pressing the "OK" button). The adjusted power is stored as the "limiting visual acuity power" or "limiting visual acuity refraction" upon detection of the third target.

[0132] The sensitivity can be determined from the visual acuity levels of the two targets, the objective refraction value, the effect upon detection of the second target, and the effect upon detection of the third target. For this purpose, a sensitivity metric, as described in exemplary embodiments above, can be used. The misrefractions result from the spherical and / or astigmatic distance of the effect upon detection of the respective target from the objective refraction value. B. Procedure according to an exemplary embodiment with subjective refraction

[0133] With this variant, the above-mentioned steps 5) to 7) from the procedure in Section A can be omitted. Therefore, only the visual acuity for a target and the effect upon detection of a target need to be determined. A subjective refraction determination is then performed, and the subjective refraction value and the visual acuity (visus cum correctione, VCC) achieved by the subject are determined. The objective refraction value can be used as the starting value for the subjective refraction determination.

[0134] Alternatively, the subjective refraction determination with visual acuity determination can be performed before the steps in section A. In this case, the autorefraction or aberrometry and the determination of the objective refraction value (step 1) can be omitted and the subjective refraction value can be used instead.

[0135] The misrefraction can be calculated as the spherical or astigmatic distance of the effect when detecting the target from the subjective refraction value.

[0136] Instead of the subjective refraction value, a combined refraction value can also be used to calculate sensitivity or refractive error. This can be calculated based on the subjective refraction value and the objective refraction value or other data (e.g., low- or high-order aberrations from aberrometry or other biometric data such as corneal shape, lens-retina distance, anterior chamber depth). C. Adjusting the visual acuity level of a target

[0137] Furthermore, at least one visual acuity level of the symbol(s) of a target can be adjusted to the subject. This is useful, for example, if the subject's astigmatism cannot be corrected. The visual acuity level of the (virtual) target can then be selected so that the target can still be recognized despite the remaining refraction error due to the astigmatism.

[0138] Information about visual acuity (e.g. visual acuity cum correctionem or visual acuity sine correctionem, for example from subjective refraction determination) can also be used to determine the target size.

[0139] If the subject does not recognize the symbol despite a slight deviation of the applied power from the objective, subjective or combined refraction value, the patient can switch to a lower visual acuity level and repeat the corresponding step with a lower visual acuity level.

[0140] In addition or instead, the findings from step 4 can be used to determine the visual acuity level in step 6.

[0141] To prevent the subject from already knowing the optotype when performing multiple measurements or switching between eyes, at least one optotype, symbol, or detail in the image can be changed between different measurements or when switching eyes (e.g., rotating a Landolt ring or changing a letter or number). Electronic displays are naturally particularly well-suited as target delivery devices for this purpose. D. Finding the blur point and adjusting the effect by the subjectFinding the blur point

[0142] As an alternative to the procedure described in the previous sections, the effect presented at the beginning (i.e., in step 2) after section A or B) can also be an effect that allows the detection of the target. This can be an objective, subjective, or combined refraction value.

[0143] In steps 5 and 6, the applied power is then moved away from this power in the plus direction. This direction is chosen to prevent accommodation. In steps 4 and 7, the subject then signals the point in time at which they can no longer recognize the optotype.

[0144] If the applied powers are determined for two visual acuity levels analogous to the procedure in Section A, the applied powers can be determined first (steps 2-4) for the higher visual acuity level and then (steps 5-7) for the lower visual acuity level. This can increase the refraction error over the course of the procedure, rendering the optotype with the more difficult recognition (higher visual acuity level) and then the one with the easier recognition (lower visual acuity level) unrecognizable. Correcting the (blur)point of focus

[0145] Optionally, the subject can correct the pre-determined effect in steps 4) and 7) of the above embodiments if they are unsure whether they have signaled the correct time or the correct pre-determined effect. This can be done, for example, using the "+" and "-" buttons on the feedback unit. Adjustment of the (un)focus point by the subject

[0146] The subject can also be asked directly to adjust the power at which recognition of the optotype is just possible or no longer possible. This can be done, for example, using the "+" and "-" buttons on the feedback unit. Approaching the (un)focus point from different directions

[0147] Furthermore, one blur point can be determined for increasing the sensitivity and another for decreasing the sensitivity. These points can be different from each other and then averaged. Alternatively, the sensitivity can be determined from both blur points using known metrics by minimizing the squared errors. Repeat the measurement

[0148] Of course, the uncertainty can also be determined several times to increase the measurement accuracy of the method. Monitoring the state of accommodation

[0149] During steps 3), 4), 6), or 7) in the method according to Section A, or during steps 3) or 4) in the method according to Section B, the accommodation state of at least one eye of the subject can be monitored using the autorefractometry or aberrometry unit. The results obtained can be used to control the process (e.g., aborting or repeating individual steps in the event of unwanted accommodation (e.g., exceeding a certain threshold). The measurement can be performed continuously or only when detectability is signaled.

[0150] Furthermore, an accommodation state (sphere, cylinder, low or higher order aberrations) measured - ideally when signaling detectability - can be included in the calculation of the sensitivity or the refraction error. E. Blurring towards minus and incorporating a close-up measurementBlurring towards minus

[0151] In the above examples, the applied power corresponds to a positive refraction, since this cannot be compensated for by the subject through accommodation. However, the opposite approach can also be used, i.e., with an applied power that corresponds to a negative refraction. The accommodation that may occur in this case can be dealt with as follows: - Ignoring accommodation; - Measurement of subjects who are unable to accommodate, e.g. due to physiological reasons (e.g. age-related) or pharmacological reasons (e.g. drip-induced)), or who are only weakly able to accommodate; - Measuring or monitoring the state of accommodation; - Using assumptions on accommodation ability (e.g. depending on age according to the Duane curve, see Fig. 3).

[0152] The Fig.The Duane curve shown in Figure 3 is taken from B. Lachenmayr, D. Friedburg, E. Hartmann, A. Buser: “Eye - Glasses - Refraction: Schober Course: Understand - Learn - Apply”, 2005, Fig. 1.29, and was originally published in Alexander Duane: “Studies in monocular and binocolar accommodation with their clinical applications”, Transactions of the American Ophthalmological Society, Volume 20, 1922, pp. 132-157, PMID 16692582, PMC 1318318. Duane's curve shows that the ability of the human eye to accommodate (width of accommodation) decreases continuously from an average of 14 to one diopter from the age of eight until shortly after the age of fifty.

[0153] The influence of accommodation on the sphere can be taken into account in the following ways, for example: - The amount of accommodation is subtracted from the amount of distance of the applied power from the refraction value for distance; - The refraction error is calculated directly from the applied power and the measured or assumed refraction value.

[0154] In an analogous manner, the astigmatic aberration can also be calculated using known formalisms (e.g., the cross-cylinder formula, power vector notation) over the measured cylinder to account for changes in astigmatism due to accommodation. Furthermore, measured higher-order aberrations can be accounted for using known metrics. Integrating a close-up measurement

[0155] The procedure described above can be combined with a determination of the objective near refraction values, the maximum accommodation, and / or the imaging errors (lower or higher orders).

[0156] This can be done as follows: The eye's accommodation state is monitored using (ideally concurrent and as frequent as possible) autorefractometric or aberrometric measurements. The procedure begins with a pre-applied power that allows the target to be identified. This can be an objective, subjective, or combined refraction value. In step 5) and, if necessary, step 6), the pre-applied power is then moved away from this power in the plus direction. In step 4) and, if necessary, step 7), the subject then signals the point in time at which they can no longer recognize the optotype. If the applied powers are determined for two visual acuity levels, in this case the applied powers for the higher visual acuity level can be determined first (steps 2-4) and then (steps 5-7) for the lower visual acuity level.This allows the refraction error to be increased over the course of the procedure, whereby the optotype with the more difficult detection (higher visual acuity) becomes unrecognizable first, followed by the one with the easier detection (lower visual acuity). The autorefractometric or aberrometric value measured at the (respective) signaling of loss of detection is used to calculate sensitivity or visual acuity, respectively.

[0157] The value of the autorefractometric or aberrometric measurement corresponding to the greatest accommodation is then used as the value (sphere, cylinder, lower or higher order aberration) for the near refraction or for the maximum accommodation capacity. F. Monitoring pupil size

[0158] Furthermore, pupil size (e.g., pupil radius) can be monitored, e.g., using a camera mounted in the autorefractometer or aberrometer, or using a separate camera. The pupil size measured at the point of blur or shortly before (e.g., up to 2 seconds before reaching the point of blur) can be used to determine sensitivity to blur.

[0159] The measured pupil size can then be used to quantify the blur of the image on the retina using a suitably parameterized eye model and the known additional fogging. For example, the angle at which the disc of confusion of a blurred point can be observed for a given pupil size and given additional fogging can be calculated (cf. WO 2019 034525 A1). Within such a visual acuity model, the sensitivity can be determined as the deterioration in visual acuity per angle of the disc of confusion. G. More complex models for sensitivity

[0160] In more complex models, a distinction can be made between the influence of spherical fogging or misrefractions and astigmatic fogging or misrefractions. For this purpose, spherical fogging and astigmatic fogging can be determined for the same visual acuity level. H. Combination with other measurements

[0161] The present invention can be very well combined with or embedded in other measurements. In a preferred embodiment, the procedure according to section A or B is carried out after an autorefractometric or aberrometric measurement for distance. This autorefractometric or aberrometric distance measurement already represents the first step according to section A and does not need to be carried out again. The procedure according to one of the above sections can be carried out either before or after any measurement for near vision. The former has the advantage that the (virtual) target is initially unknown to the test subject and the test subject has already familiarized themselves with the target for the near measurement.

Claims

[1] Method for determining the sensitivity of at least one eye of a subject on the basis of at least two provided visual acuity-refraction value pairs, wherein at least one of the visual acuity-refraction value pairs is provided by the following steps: - Projecting a target with an adjustable target refraction into at least one eye of the subject, wherein the target is designed to verify a predetermined visual acuity; and - Determining a visual acuity limit refraction of the at least one eye of the subject associated with the predetermined visual acuity by varying the target refraction of the target projected into the at least one eye of the subject and detecting a subject action with which it is determined that the identifiability of the target for the subject has changed at the time of the subject action; wherein the sensitivity is determined based on at least one calculated misrefraction, and wherein the at least one calculated misrefraction is calculated on the basis of a determined optimal refraction of the at least one eye of the subject. [2] Method according to claim 1, wherein, before the step of projecting a target designed to verify a predetermined visual acuity into the at least one eye of the subject, an objective and / or subjective refraction result of the at least one eye of the subject is determined, and wherein preferably before the step of varying the target refraction, the target is projected into the at least one eye of the subject with such a starting target refraction that the subject can only see the target in a blurred manner and / or cannot identify it. [3] The method of claim 1 or 2, further comprising the step - Determining the optimal refraction of at least one eye of the subject and determining the visual acuity achieved by at least one eye of the subject when compensating for any visual impairment of at least one eye of the subject on the basis of the determined optimal refraction. [4] Method according to one of the preceding claims, further comprising the steps: - Determining a subjective refraction result for at least one eye of the subject; - Determining the visual acuity achieved by the at least one eye of the subject upon compensation of any visual impairment of the at least one eye of the subject on the basis of the determined subjective refraction result; wherein the optimal refraction of the at least one eye of the subject is preferably determined on the basis of the subjective refraction result and an objective refraction result. [5] Method according to one of the preceding claims, wherein varying the target refraction comprises monotonously decreasing the target refraction and / or monotonously increasing the target refraction. [6] Method according to one of the preceding claims, wherein the determination of a visual acuity limit refraction of the at least one eye of the subject associated with the predetermined visual acuity is carried out by lowering the target refraction and detecting a subject action during the lowering of the target refraction, and / or by increasing the target refraction and detecting a subject action during the increasing of the target refraction, wherein with each subject action it is determined that the identifiability of the target for the subject has changed at the time of the respective subject action. [7] Method according to one of the preceding claims, wherein at least two of the provided visual acuity-refraction value pairs are provided by the following steps: - Projecting a first target with a first adjustable target refraction into the at least one eye of the subject, wherein the first target is designed to verify a predetermined first visual acuity; - determining a first visual acuity limit refraction of the at least one eye of the subject associated with the predetermined first visual acuity by varying the first target refraction of the first target projected into the at least one eye of the subject and detecting a first subject action with which it is determined that the identifiability of the first target for the subject has changed at the time of the first subject action; - Projecting a second target with a second adjustable target refraction into the at least one eye of the subject, wherein the second target is designed to verify a predetermined second visual acuity that differs from the predetermined first visual acuity; - Determining a second visual acuity limit refraction of the at least one eye of the subject associated with the predetermined second visual acuity by varying the second target refraction of the second target projected into the at least one eye of the subject and detecting a second subject action with which it is determined that the identifiability of the second target for the subject has changed at the time of the second subject action. [8] Method according to one of the preceding claims, wherein the determination of a visual acuity limit refraction comprises measuring an accommodation state and / or a pupil size of the at least one eye of the subject, wherein the measurement of the accommodation state and / or the pupil size takes place in particular at the time of or immediately after the subject's action. [9] Method according to one of the preceding claims, wherein, in order to determine a visual acuity limit refraction, the subject is given a visual task with at least two possible different answers, and wherein the subject can answer the visual task based on the subject's action. [10] Method according to one of the preceding claims, wherein, before the step of determining a visual acuity limit refraction, first aberrometric data of the at least one eye of the subject, in particular for a distance accommodation state of the at least one eye of the subject, are recorded, and wherein the method preferably further comprises acquiring second aberrometric data of the at least one eye of the subject for a near accommodation state of the at least one eye of the subject, wherein the acquiring of second aberrometric data preferably takes place before the step of determining a visual acuity limit refraction. [11] Method for calculating, optimizing or evaluating a spectacle lens for at least one eye of a subject taking into account the sensitivity of the at least one eye of the subject, wherein the sensitivity of the at least one eye of the subject is determined by a method according to one of the preceding claims. [12] A method for producing a spectacle lens, comprising: - Calculating or optimizing a spectacle lens according to the method for calculating or optimizing a spectacle lens according to claim 11; and - Manufacturing the calculated or optimized spectacle lens. [13] A computer program product comprising program code designed and arranged, when loaded and executed on a computer, to perform a method according to any one of the preceding claims. [14] Device for determining the sensitivity of at least one eye of a subject, comprising: - a target providing device for providing a target designed to verify a predetermined visual acuity; - an optical system for projecting the target with a target refraction into at least one eye of the subject, wherein the optical system is designed to adjust and vary the target refraction; - a feedback unit for detecting a subject's action in order to determine that the identifiability of the target for the subject has changed at the time of the subject's action, in particular as a result of varying the target refraction of the target projected into at least one eye of the subject with the aid of the optical system; - a visual acuity limit refraction determination unit for determining a visual acuity limit refraction of the at least one eye of the subject associated with the predetermined visual acuity, wherein the visual acuity limit refraction determination unit is designed to detect the target refraction effected by the optical system at the time of the subject's action; and - an evaluation unit which is designed to determine the sensitivity on the basis of at least one misrefraction calculated on the basis of a determined optimal refraction. [15] Device according to claim 14, wherein the evaluation unit is designed to determine the sensitivity of the at least one eye of the subject on the basis of at least two provided visual acuity-refraction value pairs, and wherein the visual acuity limit refraction determination unit represents a component of the evaluation unit. [16] Apparatus according to claim 14 or 15, further comprising - an autorefractometric or aberrometric measuring unit for determining one or more objective refractions of the at least one eye of the subject, wherein the autorefractometric or aberrometric measuring unit is preferably designed to measure and / or monitor an accommodation state of the at least one eye of the subject. [17] Device according to one of claims 14 to 16, further comprising: - a pupil size measuring unit for determining a pupil size of at least one eye of the subject; and / or - a lighting device for generating at least two brightness levels, and / or - a pupillometer device configured to acquire first pupillometric data of the at least one eye at a first brightness and to acquire secondary pupillometric data of the at least one eye at a second brightness. [18] System for calculating, optimising or evaluating a spectacle lens for at least one eye of a subject taking into account the sensitivity of the at least one eye of the subject, comprising a device for determining the sensitivity of the at least one eye of the spectacle wearer according to one of claims 14 to 17. [19] Apparatus for producing a spectacle lens, comprising: - Calculation or optimization means designed to calculate or optimize the spectacle lens according to a method for calculating or optimizing a spectacle lens according to claim 11; and - Processing means designed to process the spectacle lens according to the result of the calculation or optimization. [20] Spectacle lens produced by a method according to claim 12 and / or by means of a device according to claim 19.

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