Progressive lens with variable refractive index and method for its design and manufacture

Description

[0001] The invention relates to a product comprising a progressive spectacle lens or a representation of the progressive spectacle lens on a data carrier according to the preamble of patent claims 1 and 8, a computer-implemented method for designing a progressive spectacle lens according to the preamble of patent claims 16, 17 and 18 and a method for producing a progressive spectacle lens according to claim 24 as well as a computer program according to patent claim 22 and a computer-readable medium according to patent claim 23.

[0002] Progressive lenses have been known and widely used in ophthalmic optics for decades. Like multifocal lenses (generally bifocal and trifocal lenses), they provide presbyopes with an additional optical power in the lower part of the lens for viewing close objects, e.g., when reading. This is necessary because the eye lens gradually loses its ability to focus on close objects with increasing age. Compared to these multifocal lenses, progressive lenses offer the advantage of providing a smooth increase in optical power from the distance to the near part, ensuring sharp vision not only at distance and near, but also at all intermediate distances.

[0003] According to Section 14.1.1 of DIN EN ISO 13666:2013-10, the distance portion is the part of a multifocal or progressive lens that has the dioptric power for distance vision. Similarly, according to Section 14.1.3 of this standard, the near portion is the part of a multifocal or progressive lens that has the dioptric power for near vision.

[0004] Progressive lenses have traditionally been made from a single material with a uniform, constant refractive index. This means that the dioptric power of the lens is determined exclusively by the appropriate shape of the two surfaces of the lens that are exposed to air (the front or object-facing surface, and the back or eye-facing surface, as defined in sections 5.8 and 5.9 of DIN EN ISO 13666:2013-10). According to the definition in section 9.3 of DIN EN ISO 13666:2013-10, dioptric power is the collective term for the focusing and prismatic power of a lens.

[0005] To achieve the continuous increase in focusing power in a progressive lens made of a material with a uniform, constant refractive index, a corresponding continuous change in surface curvature must be present on at least one of the two lens surfaces, as reflected in Section 8.3.5 of the standard DIN EN ISO 13666:2013-10, which defines the term "progressive lens" as "a lens with at least one progressive surface and an increasing (positive) power when the wearer looks downwards." According to Section 7.7, a progressive surface is a non-rotationally symmetric surface with a continuous change in curvature across all or part of the progressive surface, generally intended to provide an increasing near-vision or regressive power.

[0006] WO 89 / 04986 A1 initially concerns progressive spectacle lenses (the term "progressive spectacle lenses" is used in this document) of the type described above. On pages 1, 2, and 3 of the document, it is stated that "the manufacturing process, and in particular the polishing" of progressive spectacle lenses' surfaces is "difficult" due to their surface design, which "deviates greatly from the spherical shape," and that the manufactured surface deviates significantly from the calculated target shape. "Furthermore," "it is not possible—at least with a progressive surface—to minimize aberrations, and in particular astigmatism and distortion, across the entire lens."

[0007] WO 89 / 04986 A1 further states on page 2 that although spectacle lenses with a changing refractive index are known, the realisation of progressive spectacle lenses by replacing the complicated surface design of the progressive lens surface with a varying refractive index has probably failed in the past due to the expected similarly complicated refractive index function.

[0008] WO 89 / 04986 A1 claims to achieve "simplified production with comparable imaging properties" "if [...] a refractive index of the lens material that changes at least along the principal line of sight in the intermediate portion contributes at least partially to the increase in the refractive power." However, this is achieved with the objective of "reducing the differences in the radii of curvature between the distance portion and the near portion, so that, on the one hand, the machining of a blank with spherical boundary surfaces to produce a progressive surface is shortened" and "on the other hand, [...] the polishing process, which in progressive spectacle lenses according to the prior art essentially corresponds to that of a spherical lens, is simplified and the result of the polishing process is improved."At the time of filing WO 89 / 04986 A1, it was customary to use large-area polishing tools whose polishing surfaces were approximately the size of the progressive lens surface to be polished.

[0009] The document continues on page 5, line 15ff: If, in addition, the astigmatism along the principal meridian is reduced by varying the refractive index, this means that the restriction on the design of the spectacle lens that the surface astigmatism along the principal meridian or the principal line of sight should be small, is also eliminated, so that the [...] spectacle lens is not subject to Minkwitz's theorem, and the spectacle lens can be designed much more effectively from other points of view.

[0010] The stated goal of this document is to obtain easily polishable surfaces by making the refractive index variation correspondingly complex. The second-to-last paragraph on page 6 explicitly states: "In extreme cases, it is even possible for both surfaces of the progressive lens to be spherical. Of course, it is also possible to use rotationally symmetric aspherical surfaces." On the other hand, the document does not impose any restrictions on the complexity of the refractive index function, which, according to the last sentence on page 6, "can be described, for example, using spline functions."

[0011] The document discloses two embodiments. In the second embodiment, "both the front surface and the eye-side surface [...] are spherical surfaces" (see ibid., p. 11, last sentence). In the first embodiment, the front surface has a principal meridian in the shape of a circle (cf. ibid., p. 12, lines 6-13) and, perpendicular to it, the shape of conic sections (cf. ibid., p. 11, lines 6-14). The back surface is spherical in the first embodiment.

[0012] Regarding the first exemplary embodiment, the document "explicitly points out [...] that the correction of aberrations was not taken into account during optimization, and that lenses with very good imaging properties in the lateral areas were nevertheless obtained. A further improvement of the imaging properties in the areas lateral to the main meridian is achieved by further optimization of the index function."

[0013] WO 99 / 13361 A1 describes a so-called "MIV" lens object, which is supposed to have all the functional features of progressive lenses, namely a distance portion, a near portion, and a progression zone, but whose peripheral areas are supposed to be free of astigmatic aberrations. This document describes that such a lens object can have a spherical front surface and a spherical rear surface. The lens object is supposed to have a progression zone with a refractive index that continuously increases from the distance portion to the near portion. However, with such a design, not all desired additions can usually be realized.The document therefore states: "If desired, the range of additions can be bridged, if this is impossible with the single variable refractive index, also by manufacturing the lenses with a block of material with a variable refractive index, as described above, and forming curves with variable geometry like those of conventional progressive lenses, with the result that they have a much higher power than the latter, since the lens with varying refractive index in the different ranges provides the desired addition using much less differentiated curves between the distance power and the near power, with a reduction in the aberration area and an increase in the useful viewing area."

[0014] US 2010 / 238400 A1 describes progressive spectacle lenses consisting of multiple layers. At least one of the layers can have a varying refractive index, which is described with respect to two orthogonal meridians. Furthermore, at least one of the surfaces of one of the layers can have a progressive surface shape. It is described that the refractive index progression in the horizontal direction can be used for full correction of the vision determined by the geometry of the surfaces.

[0015] Yuki Shitanoki et al: "Application of Graded-Index for Astigmatism Reduction in Progressive Addition Lens", Applied Physics Express, Vol. 2, March 1, 2009, page 032401 describes how the astigmatism of a progressive lens with a refractive index gradient can be reduced compared to a progressive lens without a refractive index gradient by comparing two progressive lenses cast using the same mold.

[0016] With regard to the distinguishability of the subject matter of the present patent application from the multi-layer spectacle lenses described in US 2010 / 238400 A1, it is hereby stated that spectacle lenses are regularly subjected to one or more finishing processes. In particular, functional layers are applied to one or both sides. Such functional layers are layers that endow the spectacle lenses with predetermined properties that are advantageous for the wearer, properties that the spectacle lenses would not have based solely on the properties of the base or carrier material to which the functional layers are applied, and the shape. Such advantageous properties include, in addition to optical properties such as anti-reflective coating, mirroring, light polarization, coloring, self-tinting, etc., also mechanical properties such as hardening, reducing the adhesion of dirt or fogging, etc.and / or electrical properties such as shielding from electromagnetic radiation, conducting electrical current, etc., and / or other physical or chemical properties. Examples of functional coatings can be found, for example, in documents WO 10 / 109154 A1, WO 01 / 55752 A1, and DE 10 2008 041 869 A1. These functional layers have no or only a negligible influence on the dioptric properties of the spectacle lens discussed in the context of the present patent application. In contrast, the layers described in US 2010 / 238400 A1 have a non-negligible influence on the dioptric power of the progressive lens.

[0017] EP 2 177 943 A1 describes a method for optimizing an optical system, such as an ophthalmic lens, using a cost function. The ophthalmic lens is defined by the coefficients of the equations of all its surfaces, the refractive index of the spectacle lens, and the position of each surface relative to each other (offset, rotation, and tilt). In one embodiment, at least the coefficients of the equations of two optical surfaces of a working optical system are modified to obtain the optical system.

[0018] The document states that it is generally difficult to optimize a lens considering a multitude of different criteria when only the equation of one surface is considered variable. This embodiment allows optical designers to consider a larger number of criteria in the optimization process, paving the way for improving the geometric performance of the optical system and better responding to the physiological needs of spectacle wearers. The benefit to the wearer is enhanced when multiple surfaces of the optical system are optimized simultaneously.

[0019] In an embodiment in which the optical system to be optimized comprises at least two optical surfaces, the modification of the working optical system is carried out in such a way that at least the index of the working optical system is changed. It is possible to manufacture a lens from an inhomogeneous material with a gradient in the refractive index (known as a GRIN lens). For example, the optimized index distribution can be axial or radial and / or wavelength-dependent.

[0020] EP 0 347 917 A1 describes a spectacle lens with a front and an eye-side boundary surface and with a changing refractive index that contributes to the correction of aberrations. The spectacle lens is characterized by at least one set of level surfaces with a constant refractive index, which are equally spaced at all points in the direction of their surface normals, and which, or their extensions, intersect the axis connecting the lens vertices of the front surface and the eye-side surface.

[0021] The document explains that varying the refractive index is regularly used to reduce aberrations in single-vision lenses with a specially selected surface design and / or to reduce center thickness. However, it is also possible to use the gradient to create an astigmatic and / or progressive power, whereby the surface design contributes nothing or only partially to the astigmatic and / or progressive power.

[0022] WO 2011 / 093929 A1 describes a progressive lens with two progressive surfaces, in which the back surface is designed so that the minimum of the amount of the mean curvature is in the progression channel.

[0023] The object of the invention is now seen in providing a progressive spectacle lens which has further improved optical properties for the wearer compared to the progressive spectacle lenses known from the prior art and in providing a method with which a progressive spectacle lens with further improved optical imaging properties can be designed and manufactured.

[0024] This object is achieved by a product having the features of patent claims 1 and 8 and a method having the features of patent claims 16, 17 and 18.

[0025] Advantageous embodiments and further developments are the subject of the dependent claims. While WO 89 / 04986 A1 proposes reducing the complexity of the required surface geometry by introducing a complicated but, contrary to previous assumptions, technically feasible refractive index distribution in order to simplify its manufacture (see ibid., p. 2, 4th paragraph, last line; p. 4, first paragraph, last sentence; page 5, first paragraph; page 5, second paragraph; page 5, last paragraph, last sentence; page 6, second-to-last paragraph) and thus reducing the large deviations of the manufactured surface from the calculated surface, which impair the optical properties (see ibid. p. 1, 3rd paragraph), the inventors have recognized that this approach does not necessarily lead to progressive lenses with better optical properties for the wearer.The inventors have recognized that the interplay between the degree of complexity of the geometry of the progressive lens and the degree of complexity of the refractive index distribution is important. Deviating from the solution described in WO 89 / 04986 A1, the inventors therefore propose a product comprising a progressive lens or a representation of the progressive lens on a data carrier. The progressive lens has a front surface and a rear surface and a spatially varying refractive index. The front surface or the rear surface or front and rear surfaces are designed as a progressive lens. According to the invention, the progressive lens is characterized in that the front surface designed as a progressive lens surface is designed as a freeform surface or that the rear surface designed as a progressive lens surface is designed as a freeform surface.This also includes the case where only one of the two surfaces is present as a freeform surface.

[0026] The expression "representation of a progressive spectacle lens on a data carrier" is understood in the context of the present invention to mean, for example, a representation of the progressive spectacle lens stored in a computer memory.

[0027] The representation of the progressive lens includes, in particular, a description of the geometric shape and the medium of the progressive lens. Such a representation can, for example, include a mathematical description of the front surface, the back surface, the arrangement of these surfaces relative to one another (including the thickness) and the edge boundary of the progressive lens as well as the refractive index distribution of the medium from which the progressive lens is to be made. The representation can be in coded or even encrypted form. The term "medium" here refers to the material(s) or substance from which the progressive lens is made. The progressive lens can also consist of several layers, e.g. of an ultra-thin glass with a thickness of between 10 µm and 500 µm and plastic applied on top.

[0028] According to Section 5.8 of DIN EN ISO 13666:2013-10, the front surface or object-side surface of a spectacle lens is the surface of a spectacle lens that is intended to face away from the eye in the spectacles. Accordingly, according to Section 5.9 of this standard, the back surface is the eye-side surface, i.e., the surface of a spectacle lens that is intended to face the eye in the spectacles.

[0029] According to section 7.7 of DIN EN ISO 13666:2013-10, a progressive surface is a non-rotationally symmetric surface with a continuous change in curvature over the entire surface or part of it, which generally serves to provide an increasing near addition or a regression effect. A continuous change excludes sudden changes. In particular within the scope of the invention, "general" means that the near addition or the regression effect can be provided but does not have to be. In particular, within the scope of the present invention, the spatially varying refractive index can at least partially take over this task. According to this definition, every freeform surface is a progressive surface, but not vice versa.

[0030] In the broader sense, a freeform surface is understood to be a complex surface that can be represented in particular using exclusively (particularly piecewise) polynomial functions (in particular polynomial splines, such as bicubic splines, higher-order splines of fourth degree or higher, Zernike polynomials, Forbes surfaces, Chebyshev polynomials, Fourier series, polynomial non-uniform rational B-splines (NURBS)). A distinction must be made between these surfaces and simple surfaces, such as spherical surfaces, aspherical surfaces, cylindrical surfaces, toric surfaces, or the surfaces described in WO 89 / 04986 A1, which are described as a circle at least along the principal meridian (cf. ibid. p. 12, lines 6-13). In other words, freeform surfaces cannot be represented in the form of classical regular bodies such as spherical surfaces, aspherical surfaces, cylindrical surfaces, toric surfaces or the surfaces described in WO 89 / 04986 A1 (see e.g. https: / / www.computerwoche.de / a / die-natur-kennt-auch-nur-freiformflaechen, 1176029 downloaded on 18.1.2018; http: / / www.megacad.de / kennenlernen / megacadschulungen / schulungsinhalte / schulung-freiformflaechen.html downloaded on 18.1.2018) but for example using exclusively (especially piecewise) polynomial functions (especially polynomial splines, such as bicubic splines, higher degree splines of fourth degree or higher, Zernike polynomials, Forbes surfaces, Chebyshev polynomials, Fourier series, polynomial non-uniform rational B-splines (NURBS)). Freeform surfaces are therefore surfaces that do not correspond to any regular geometry (see e.g. https: / / www.infograph.de / de / nurbs downloaded on 18.1.2018; https: / / books.google.de / books?id=QpugBwAAQBAJ&pg=PA 101 &lpg=PA 101 &dq=regelgeome trie+definition&source=bl&ots=CJjmQwghvo&sig=MvsGvOsqbAVEygCaW-JOhfJ99jw&hl=de&sa=X&ved=0ahUKEwi_jcD5y-HYAhXDXCwKHUaQCBw4ChDoAQgsMAI#v=onepage&q=regelgeometrie%20definition&f= false downloaded on 18.1.2018) or which cannot be described using forms of analytical geometry (see e.g. https: / / books.google.de / books?id=LPzBgAAQBAJ&pg= PA26&1pg=PA26&dq=regelgeometrie+definition&source=bl&ots=e1upL5jinn&sig=hUNimu8d eH5x8OvCiYsa242ddn8&h1=de&sa=X&ved=0ahUKEwi_jcD5y-HYAhXDXCwKHUaQCBw4ChDoAQgvMAM#v=onepage&q=regelgeometrie%20definition& f=false downloaded on 18.1.2018).

[0031] The task described at the beginning is fully solved by the versions of a progressive lens, which are identified below as variants.

[0032] In a further embodiment of the invention, it is provided that the freeform surface is a freeform surface in the narrower sense according to section 2.1.2 of DIN SPEC 58194 of December 2015, namely a spectacle lens surface manufactured using freeform technology, which is mathematically described within the limits of differential geometry and is neither point-symmetric nor axially symmetric.

[0033] Furthermore, in particular, the freeform surface cannot exhibit point symmetry, axial symmetry, rotational symmetry, or symmetry with respect to a plane of symmetry. Although it is advantageous to remove any restriction regarding surface geometry, in view of the current requirements for the optical properties of progressive lenses, it is sufficient to permit only freeform surfaces with a high degree of complexity as progressive surfaces. If, in addition, the same degree of complexity is permitted for the refractive index distribution across the progressive lens, at least in two or preferably in three spatial dimensions, these progressive lenses will meet the wearers' requirements regarding their optical properties to the highest degree.

[0034] A variant of the invention, in a progressive spectacle lens according to the invention which has a progression channel, consists in that the front surface designed as a freeform surface is configured such that the mean curvature is maximum in the progression channel and decreases towards the periphery and / or downwards. Alternatively or additionally, the rear surface designed as a freeform surface can also be configured such that the mean curvature in the progression channel is minimal and increases towards the periphery and / or downwards. In other words, the front surface designed as a freeform surface is configured such that the maximum of the mean curvature of the front surface is in the progression channel and / or the rear surface designed as a freeform surface is configured such that the minimum of the mean curvature of the rear surface is in the progression channel.

[0035] According to DIN EN ISO 13666:2013-10 paragraph 14.1.25, the progression channel is the area of ​​a progressive lens that enables sharp vision for distances that lie between far and near.

[0036] Such surfaces can be manufactured with the highest precision using currently available production methods. The selection of this surface geometry for the front surface offers particular manufacturing advantages. Using currently available polishing tools, whose at least approximately spherical polishing surface corresponds to approximately one-third of the lens surface to be polished, the polishing removal can be kept sufficiently homogeneous across the lens surface to be polished, so that the deviation from the calculated lens geometry is comparatively small. The deviation of the actual optical properties from the calculated optical properties of the lens is thus extremely small.

[0037] A further variant of the invention is characterized in that the progressive spectacle lens according to the invention is designed in such a way that it has the more advantageous optical properties described below for the progressive spectacle wearer compared to a comparison progressive spectacle lens which has no spatial refractive index variation but an identical distribution of the spherical equivalent.

[0038] By way of explanation, it is stated that a spectacle lens is designed for a predetermined arrangement in front of the eye of a spectacle wearer and for one or more predetermined object distances at which the wearer should be able to see an object clearly. In a different arrangement in front of the wearer's eye and for other object distances, the spectacle lens is worthless or the optical quality is severely limited for the wearer. This applies even more so to progressive lens lenses. Accordingly, a progressive lens is only characterized by knowledge of the predetermined arrangement in front of the wearer's eye. In other words, knowledge of the arrangement of the spectacle lens in terms of location and orientation in space in relation to the eye is necessary but also sufficient to characterize its optical effect for the wearer in a one-to-one manner.Furthermore, an optician is only able to correctly insert the lens into a frame if they know the position and orientation of the lens relative to the wearer's eye. A representation of the predetermined position of the progressive lens in front of the eye of a progressive lens wearer for whom the progressive lens is intended is therefore an integral part of the product (article) or the commercial good "progressive lens."

[0039] The manufacturer applies permanent markings to the progressive lens to ensure that the optician correctly positions and orients the lens. Section 14.1.24 of DIN EN ISO 13666:2013-10 states that these are referred to as alignment markings or permanent markings and are applied by the manufacturer to enable the horizontal orientation of the lens [...] or the reconstruction of additional reference points. According to Section 6.1 of DIN EN ISO 14889:2009, the manufacturer of raw-edged finished lenses must enable identification through information on the individual packaging or in an accompanying document. In particular, they must provide correction values ​​for usage situations, the near-vision power, the type designation or trade name, and the information necessary to measure the near-vision power.The type designation or trade name indicates the object distance model used by the manufacturer for the progressive lens. According to Section 3.1 of this standard, a manufacturer is defined as a natural or legal person who markets the finished, unfinished ophthalmic lens.

[0040] In this variant of the invention, the product further comprises a representation, located on a data carrier, of a predetermined arrangement of the progressive spectacle lens in front of the eye of a progressive spectacle wearer for whom the progressive spectacle lens is intended. As already explained, the progressive spectacle lens designed according to the invention (not only) in this variant has a distribution of a spherical equivalent for the predetermined arrangement of the progressive spectacle lens in front of the eye of the progressive spectacle wearer for whom the progressive spectacle lens is intended. Furthermore, the progressive spectacle lens designed according to the invention has a progression channel with a width.The progressive spectacle lens designed according to this variant according to the invention has a refractive index which varies spatially in such a way that the width of the progression channel of the progressive spectacle lens is greater, at least in one section or over the entire length of the progression channel, than the width of the progression channel of a comparison progressive spectacle lens for an identical prescription with the same distribution of the spherical equivalent with the same arrangement of the comparison progressive spectacle lens in front of the eye of the progressive spectacle wearer but with a spatially non-varying refractive index.

[0041] The term "spherical equivalent" is defined here as the arithmetic mean of the focusing power, as can be seen, for example, in Albert J. Augustin: Ophthalmology. 3rd, completely revised and expanded edition. Springer, Berlin et al. 2007, ISBN 978-3-540-30454-8, p. 1272, or Heinz Diepes, Ralf Blendowske: Optics and Technology of Glasses. 1st edition, Optische Fachveröffentlichung GmbH, Heidelberg 2002, ISBN 3-922269-34-6, p. 482: Sph ä risches Ä quivalent = Sph ä re + 1 2 × Zylinder

[0042] According to Section 9.2 of DIN EN ISO 13666:2013-10, the focusing power is the collective term for the spherical and astigmatic power of a spectacle lens. The spherical power is abbreviated to "sphere" in the equation, while the astigmatic power is represented by "cylinder." The term "spherical equivalent" is also used to refer to the term "mean spherical power."

[0043] As already explained above, according to DIN EN ISO 13666:2013-10, paragraph 14.1.25, the progression channel is the area of ​​a progressive lens that enables sharp vision at distances between distance and near. The principal line of sight runs through the center of the progression channel. This represents the totality of all visual points through the progressive lens surface as the eye moves from distance to near to objects directly in front of the wearer. The principal line of sight is usually assumed to be on the front surface.In other words, the principal line of sight is the line on the front surface of a spectacle lens that connects the principal visual points through the progressive lens for distance and near vision, and on which the points of intersection of the visual rays for intermediate distances in the "straight ahead" direction lie (Note: the use of the back surface as the reference surface on which the principal line of sight lies is rather unusual). The principal line of sight is usually a line that is approximately vertical in the distance and near parts and sinuous in the progression channel, i.e., the part of a progressive lens that has the dioptric power for vision at distances between distance and near. The length of the progression channel can be determined, for example, by the position of the distance and near design reference points or the position of the distance and near design reference points. The distance design reference point is, according to 5.13 of DIN EN ISO 13666:2013-10 is the point on the front surface of a finished spectacle lens or the finished surface of a spectacle lens blank at which, according to the manufacturer's specifications, the design nominal values ​​for the distance portion are present. Accordingly, according to 5.14 of this standard, the near design reference point is the point on the front surface of a finished spectacle lens or the finished surface of a spectacle lens blank at which, according to the manufacturer's specifications, the design nominal values ​​for the near portion are present. According to 5.15, the distance reference point or principal reference point is the point on the front surface of a spectacle lens at which the dioptric power for the distance portion must be achieved, and according to 5.17, the near visual point is the assumed position of the visual point on a spectacle lens for near vision under certain conditions.

[0044] In principle, it is possible to use the above information to unambiguously define and determine the properties of the progressive lens in relation to a comparison progressive lens. A simple criterion arises if one assumes that at least one cut is a variant from the group horizontal cut, cut at half addition (in particular on the main line of sight), horizontal cut at half addition (in particular on the main line of sight), horizontal cut at half addition (in particular on the main line of sight) and horizontal cut at 25% of the addition (in particular on the main line of sight), horizontal cut at half addition (in particular on the main line of sight) and horizontal cut at 75% of the addition (in particular on the main line of sight), horizontal cut at half addition (in particular on the main line of sight) and horizontal cut at 25% of the addition (in particular on the main line of sight) and horizontal cut at 75% of the addition (in particular on the main line of sight).

[0045] DIN EN ISO 13666:2013-10 defines in Section 14.2.1 the near addition or addition as the difference between the vertex power of the near part and the vertex power of the far part measured by specified procedures. This standard states that corresponding measuring procedures shall be included in the standard applicable to spectacle lenses. In DIN EN ISO 13666:2013-10, reference is made to DIN EN ISO 8598-1:2012, "Optics and optical instruments - Vertex power measuring devices - Part 1: Instruments for general use" as the applicable standard. The vertex power is defined in DIN EN ISO 13666:2013-10, Section 9.7 as follows. A distinction is made between the image-side vertex power, which is defined as the reciprocal of the paraxial section width of the image-side focal point, measured in meters, and the object-side vertex power, which is defined as the reciprocal of the paraxial section width of the object-side focal point, measured in meters.It should be noted that, according to consensus in ophthalmology, the image-side vertex power is used as the "vertex power" of a spectacle lens, but for certain purposes the object-side vertex power is also required, e.g., for measuring the addition of some multifocal and progressive lenses.

[0046] A further variant of defining the properties of the progressive spectacle lens by comparing it with the properties of a comparative progressive spectacle lens with properties that can be predetermined in a one-to-one manner, namely the same distribution of the spherical equivalent over the lens under the same position of the spectacle lens in front of the eye of the same progressive spectacle wearer based on the same object distance model, is when the product further (i) a representation on a data carrier of a residual astigmatism distribution for the predetermined arrangement of the progressive spectacle lens in front of the eye of the progressive spectacle wearer for whom the progressive spectacle lens is intended, and / or (ii) a representation on a data carrier of an astigmatic power distribution required for full correction for the predetermined arrangement of the progressive spectacle lens in front of the eye of the progressive spectacle wearer for whom the progressive spectacle lens is intended, and / or (iii) a representation on a data carrier of a prescription and an object distance model for the predetermined arrangement of the progressive spectacle lens in front of the eye of a progressive spectacle wearer for whom the progressive spectacle lens is intended,and / or (iv) a representation on a data carrier of a distribution of the spherical equivalent for the predetermined arrangement of the progressive spectacle lens in front of the eye of the progressive spectacle wearer for whom the progressive spectacle lens is intended.

[0047] In this variant of a progressive spectacle lens according to the invention, which has a distance part and a near part, the width of the progression channel is defined by the dimension transverse to a longitudinal direction of the progression channel running between the distance part and the near part, within which the value of the amount of residual astigmatism lies below a predetermined limit value selected within a range from the group specified below: (a) the limit is in the range between 0.25 D and 1.5 D (b) the limit is in the range between 0.25 D and 1.0 D (c) the limit is in the range between 0.25 D and 0.75 D (d) the limit is in the range between 0.25 D and 0.6 D (e) the limit is in the range between 0.25 D and 0.5 D (f) the limit is 0.5 D.

[0048] Residual astigmatism is the astigmatism (in magnitude and axial direction) by which the astigmatism or astigmatic power of the progressive lens at a particular location on a progressive lens surface deviates from the astigmatic power required for full correction for a beam of rays penetrating the progressive lens at that location for the progressive lens wearer for whom the progressive lens is intended, when the progressive lens wears the lens as intended (so that it is positioned in a predetermined manner in front of the progressive lens wearer's eye). The term "distribution" clarifies that this residual astigmatism can and usually will vary locally across the lens.

[0049] In other words, residual astigmatism is the deviation of the astigmatic power (actual astigmatic power) of the progressive lens from the "prescribed" astigmatic power in terms of magnitude and axial position. In other words, residual astigmatism is the gaze-dependent difference between the actual astigmatic power and the desired astigmatic power for the wearer of the progressive lens in the wear position. The wear position takes into account the position and orientation of the lens relative to the eye during intended use. The gaze-dependent dependence of the astigmatic power can result, in particular, from the gaze-dependent dependence of the object distance and the gaze-dependent dependence of the astigmatic power of the eye.The term "prescribed effect" is therefore to be understood in the broadest sense as the desired effect that the spectacle lens should have based on its underlying position and orientation in relation to the eye for the respective direction of view and the distance at which the wearer should see the object sharply for this direction of view.

[0050] For the concrete calculation of the residual astigmatism distribution (or other error distributions, such as the spherical error distribution or other higher-order error distributions described, for example, in EP 2 115 527 B1 or actual power distributions, such as the astigmatic actual power, the spherical actual power or the prismatic actual power), the corneal vertex distance, the pupillary distance, the forward inclination of the spectacle lens, the frame angle of the spectacle lens and the spectacle lens size, including in particular the thickness and / or the edges (edge ​​contour), are regularly taken into account. In addition, an object distance model is regularly used which describes the position of object points in the wearer's field of vision relative to their eye rotation points.

[0051] The residual astigmatism distribution may already be available as a calculated mathematical description (as in case (i)) or it can be determined from the prescription (the term prescription is often used) and an object distance model (as in case (iii)) or an already calculated astigmatic power distribution for full correction (as in case (ii)).

[0052] In addition to the conventional refraction values, the prescription can also include other physiological parameters inherent in the wearer (i.e., generally parameters that are specific to the wearer) as well as the conditions of use (i.e., generally parameters that can be attributed to the wearer's environment) under which the prescribed progressive lens is to be worn. The inherent physiological parameters include, among other things, the wearer's visual impairment, the ability to accommodate and the (possibly monocular) pupil distance. The conditions of use include information on the fit of the lenses in front of the eye and also data that characterize the object distance model, such as whether the glasses are to be used for computer workstations, which are based on an object, namely the screen, at a distance other than infinity for the distance line of sight.In case the individually measured or determined prescription does not contain certain conditions of use, certain standard values ​​are assumed (e.g. standard forward inclination 9°).

[0053] The object distance model is an assumption about the distances in space at which the wearer of glasses should see objects clearly. In the object distance model, the object position is generally related to the eye's center of rotation, as already explained above.

[0054] The model calculation can take into account that the power and axial position of the eye change at different object distances and viewing directions. In particular, the model calculation can consider the so-called Listing's rule. The model calculation can also, for example, consider changes in the astigmatic power of the eye for near and far vision, for example, as described in DE 10 2015 205 721 A1.

[0055] In the context of the present invention, full correction refers to a correction brought about by the intended wearing of the progressive lenses, which allows the progressive lens wearer, taking into account the visual properties of his eye represented by the prescription, to see objects arranged at the distances on which the object distance model is based, clearly.

[0056] For the sake of completeness, it should be noted that the data carrier on which the predetermined representation is located may, for example, be a sheet of paper instead of a computer memory. This particularly applies to case (iii) above, where the regulation may also be written on a sheet of paper.

[0057] A further embodiment of the product according to the invention comprises the following components: a representation on a data carrier of a predetermined arrangement of the progressive spectacle lens in front of an eye of a progressive spectacle wearer for whom the progressive spectacle lens is intended, as well as one or more of the following representations on a data carrier: (i) a representation on a data carrier of a residual astigmatism distribution for the predetermined arrangement of the progressive spectacle lens in front of the eye of the progressive spectacle wearer for whom the progressive spectacle lens is intended, and / or (ii) a representation on a data carrier of an astigmatic power distribution required for full correction for the predetermined arrangement of the progressive spectacle lens in front of the eye of the progressive spectacle wearer for whom the progressive spectacle lens is intended,and / or (iii) a representation on a data carrier of a prescription and an object distance model for the predetermined arrangement of the progressive spectacle lens in front of the eye of a progressive spectacle wearer for whom the progressive spectacle lens is intended, and / or (iv) a representation on a data carrier of a distribution of the spherical equivalent for the predetermined arrangement of the progressive spectacle lens in front of the eye of the progressive spectacle wearer for whom the progressive spectacle lens is intended.

[0058] The progressive lens according to this embodiment has a distribution of a spherical equivalent for the predetermined arrangement of the progressive lens in front of the eye of the progressive lens wearer for whom the progressive lens is intended. In this embodiment, the refractive index of the progressive lens varies spatially such that the maximum value of the residual astigmatism of the progressive lens is smaller than the maximum value of the residual astigmatism of a comparison progressive lens for the same prescription, with the same distribution of the spherical equivalent for the same arrangement of the comparison progressive lens in front of the eye of the progressive lens wearer, but with a spatially non-varying refractive index.

[0059] The optical properties of the progressive spectacle lens according to this embodiment of the invention that are perceived by the wearer are improved compared to all progressive spectacle lenses of conventional type.

[0060] Another variant of the product according to the invention comprises the following components: a representation on a data carrier of a predetermined arrangement of the progressive spectacle lens in front of an eye of a progressive spectacle wearer for whom the progressive spectacle lens is intended, at least one of the following representations on a data carrier: (i) a representation on a data carrier of a residual astigmatism distribution for the predetermined arrangement of the progressive spectacle lens in front of the eye of the progressive spectacle wearer for whom the progressive spectacle lens is intended, and / or (ii) a representation on a data carrier of an astigmatic power distribution required for full correction for the predetermined arrangement of the progressive spectacle lens in front of the eye of the progressive spectacle wearer for whom the progressive spectacle lens is intended,and / or (iii) a representation on a data carrier of a prescription and an object distance model for the predetermined arrangement of the progressive spectacle lens in front of the eye of a progressive spectacle wearer for whom the progressive spectacle lens is intended, and / or (iv) a representation on a data carrier of a distribution of the spherical equivalent for the predetermined arrangement of the progressive spectacle lens in front of the eye of the progressive spectacle wearer for whom the progressive spectacle lens is intended.

[0061] The progressive lens according to this embodiment has a distribution of a spherical equivalent for the predetermined arrangement of the progressive lens in front of the eye of the progressive lens wearer for whom the progressive lens is intended. The progressive lens has a progression channel. The refractive index of the progressive lens varies spatially such that, for a given residual astigmatism value, A rest, limit from the group (a) the residual astigmatism value A rest, limit the residual astigmatism value is in the range between 0.25 dpt and 1.5 dpt (b) A rest, limit the residual astigmatism value is in the range between 0.25 dpt and 1.0 dpt (c) A rest, limit the residual astigmatism value is in the range between 0.25 dpt and 0.75 dpt (d) A rest, limit the residual astigmatism value is in the range between 0.25 dpt and 0.6 dpt (e) A rest, limit the residual astigmatism value is in the range between 0.25 dpt and 0.5 dpt (f) A rest, limitis 0.5 dpt on a horizontal section at the narrowest point of the progression channel (e.g. where the isoastigmatism lines for 1 dpt are closest to each other) or on a horizontal section through the point on the principal line of sight where half the addition is achieved, within a region with a horizontal distance of 10 mm on either side of the principal line of sight, the following relationship applies: B > c × A Rest , Grenz grad W where grad W is the efficiency gradient of the spherical equivalent of the progressive lens at the point on the principal line of sight at the narrowest point of the progression channel or at the point on the principal line of sight where half the addition is achieved, B is the width of the area in the progressive lens where the residual astigmatism A Rest ≤ A rest, limit where c is a constant chosen from the group: 1 , 0 < c 1 , 1 < c 1 , 2 < c 1 , 3 < c

[0062] The optical properties of the progressive spectacle lens according to this embodiment of the invention that are perceived by the wearer are improved compared to all progressive spectacle lenses of conventional type.

[0063] A further variant of a product according to the invention comprises a progressive spectacle lens or a representation of the progressive spectacle lens on a data carrier, wherein the progressive spectacle lens has a front surface and a rear surface and a spatially varying refractive index. Either the front surface or the rear surface, or both surfaces, are designed as a progressive surface. According to the invention, the front surface designed as a progressive surface is designed as a freeform surface, and / or the rear surface designed as a progressive surface is designed as a freeform surface.

[0064] The progressive lens consists of a substrate without individual layers and a front surface coating comprising one or more individual layers on the front surface of the substrate and / or a back surface coating comprising one or more individual layers on the back surface of the substrate. Only the substrate has the spatially varying refractive index.

[0065] According to the invention, a difference between the spherical equivalent measured at any point on the front surface of the progressive lens with the

[0066] front surface coating and / or the back surface coating and the spherical equivalent measured at each corresponding point on the front surface of a comparison progressive lens without front surface coating and without back surface coating but identical substrate (with identical geometry and identical refractive index) is less than a value from the group specified below: (a) the difference value is less than 0.001 dpt (b) the difference value is less than 0.002 dpt (c) the difference value is less than 0.003 dpt (d) the difference value is less than 0.004 dpt.

[0067] This variant can of course also have one or more of the features described above.

[0068] As stated above, the inventors recognized that the interplay between the degree of complexity of the geometry of the progressive surface and the degree of complexity of the refractive index distribution is crucial. Therefore, in contrast to the solution described in WO 89 / 04986 A1, they propose a computer-implemented method for designing a progressive spectacle lens with a front surface and a rear surface and a spatially varying refractive index, in which either the front surface or the rear surface, or both surfaces, are designed as a progressive surface, in the form of a ray-tracing method. Using the ray-tracing method, optical properties of the progressive spectacle lens are calculated at a plurality of evaluation points through which visual rays pass through the progressive spectacle lens.In this ray tracing method, at least one desired optical property for the progressive lens is determined at the respective evaluation point. First, a design for the progressive lens is determined, with this design including a representation of a local surface geometry of the progressive surface and a local refractive index of the progressive lens in the respective visual ray path through the evaluation points. The design of the progressive lens is modified with a view to approximating the at least one desired optical property of the progressive lens.According to the invention, the modification comprises not only a modification of the representation of the local surface geometry of the progressive lens, but also of the local refractive index of the progressive lens in the respective visual beam path through the evaluation points, wherein the at least one desired optical property comprises a desired residual astigmatism of the progressive lens.

[0069] The surface opposite the modified progressive surface is usually fixed. This generally has a simple surface geometry, such as spherical, rotationally symmetrical aspheric, or toric. In the case of a toric surface, the surface geometry and axial position are often selected to compensate for the astigmatic refractive deficit of the progressive lens wearer's eye (apart from any undesirable residual astigmatism). The surface opposite the modified progressive surface can also be a progressive lens surface, possibly even a freeform surface, with a fixed surface geometry. This can contribute to the increase in power necessary to provide the addition. The modified progressive lens surface can also contribute to the increase in power necessary to provide the addition.It is also possible for both surfaces—the front and back surfaces—to be modified along with the refractive index distribution to approximate the desired residual astigmatism distribution. Ray tracing methods for use in the design of progressive lenses are known. Particular reference is made to Werner Köppen: Conception and Development of Progressive Lenses, in Deutsche Optiker Zeitung DOZ 10 / 95, pp. 42-46, as well as EP 2 115 527 B1 and the publications cited therein. The calculation of optimized, location-dependent refractive index distributions using optical computer programs, such as the ZEMAX program from Zemax, LLC, is also known. Reference is made, for example, to their website at http: / / www.zemax.com / .

[0070] The definition of target properties for a spectacle lens refers to the so-called design of a spectacle lens. The design of a spectacle lens usually comprises the distribution of the target values ​​for one or more imaging errors, which are preferably included in the optimization of the spectacle lens as target values ​​or in the determination of the target values. In particular, a spectacle lens design is characterized by the distribution of the refractive error (i.e. the difference between the spherical equivalent of the progressive lens in the beam path in the wearing position and the spherical equivalent determined by refraction determination) and / or the distribution of the residual astigmatism (i.e. the difference between the astigmatism of the spectacle lens and the astigmatism determined by refraction determination).Instead of the term "residual astigmatism distribution," the terms "astigmatism error distribution" and "astigmatic deviation" are also used in the literature. Furthermore, a spectacle lens design can also include the distribution of the target values ​​for magnification, distortion, or other aberrations, particularly higher-order aberrations, as described in EP 2 115 527 B1. These can be area values ​​or, preferably, use values, i.e., values ​​in the wear position of the spectacle lens.

[0071] According to the invention, the design of the progressive lens is modified with the goal of achieving the specified target residual astigmatism as closely as possible. The target residual astigmatism can, for example, be set to zero at all evaluation points. It is also possible to specify a residual astigmatism distribution that preferably has much lower values ​​than those theoretically achievable with a conventional progressive lens with a spatially non-varying refractive index but a freely formed back (and / or front) surface, or those specified for the optimization of such a progressive lens. According to Werner Köppen: Conception and Development of Progressive Lenses, in Deutsche Optiker Zeitung DOZ 10 / 95, pp. 42-46, the number of evaluation points is typically between 1,000 and 1,500. EP 2 115 527 B1 proposes a number of over 8,000 evaluation points.

[0072] To achieve this goal as closely as possible, the invention not only locally alters the surface geometry of the (future) progressive lens at the evaluation point, but also the local refractive index in the medium of the progressive lens through which the optical path passes. The term "medium" refers to the material or materials from which the progressive lens is made.

[0073] In order to get as close as possible to the goal, this modification process must usually be carried out multiple times, i.e. iteratively. It should be made clear once again that during modification, especially during iteration, both the local surface geometry and the local refractive index can vary freely and neither the local surface geometry nor the local refractive index is fixed. In contrast, WO 89 / 04986 A1 teaches the specification of comparatively simple geometries for the front and back surfaces and the search for a suitable refractive index distribution in order to produce the increase in power necessary to provide the addition and, if necessary, to completely or partially correct the (residual) astigmatism along the principal line of sight and, if necessary, to further correct aberrations to the side of the principal meridian.

[0074] Although the refractive index is generally wavelength-dependent, dispersion is generally not taken into account, and the calculation is performed for a so-called design wavelength. However, it is not excluded that an optimization process considers different design wavelengths, as described, for example, in EP 2 383 603 B1.

[0075] Since the modification is carried out with the aim of coming as close as possible to the desired optical properties, experts also refer to this as optimization. The modification is carried out until a termination criterion is met. Ideally, the termination criterion is that the designed progressive lens has the specified desired optical properties. In the case in which the residual astigmatism is set to zero at all assessment points, this ideal case would be that the residual astigmatism of the calculated lens is actually zero at all assessment points. However, since this will regularly not be the case, particularly in the case described, the calculation is terminated, e.g. after one or more limit values ​​in the vicinity of the desired property(ies) have been reached or after a specified number of iterations have been reached.

[0076] Typically, the determination of the desired properties and the calculation of the actual properties are based on model calculations that take into account the conditions of use, such as the position of the lenses in front of the eye and an object distance model, as well as the wearer's physiological parameters, such as ametropia, accommodation ability, and pupillary distance. Details have already been described above.

[0077] The result of the approximation of the at least one optical target property(ies) of the progressive spectacle lens by modifying the local refractive index and the local surface geometry is generally that the front surface designed as a progressive surface is designed as a free-form surface and / or that the rear surface designed as a progressive surface is designed as a free-form surface.

[0078] The object posed at the outset is fully achieved by the method according to the invention described above.

[0079] One embodiment of this inventive method is characterized in that the design of the progressive lens is modified with a view to minimizing an objective function. In German-language literature, such an objective function is also referred to as a cost function, and in Anglo-Saxon literature as a merit function. The least squares method is very frequently used in the design of progressive lenses as a method for minimizing an objective function, as is practiced, for example, in EP 0 857 993 B2, EP 2 115 527 B1, or in Werner Köppen: Conception and Development of Progressive Lenses, in Deutsche Optiker Zeitung DOZ 10 / 95, pp. 42-46. The inventive embodiment applies this method with the objective function reproduced below. F = ∑ m P m ∑ n W n T n − A n 2 In this objective function F, P m the weighting at the assessment point m, W nthe weighting of the optical property n, T n the target value of the optical property n at the respective evaluation point m and A n the actual value of the optical property n at the assessment point m.

[0080] The application of this method has proven successful for the design of conventional progressive lenses. The invention proposes using this method for the design of gradient index (GRIN) progressive lenses according to the invention.

[0081] A particularly advantageous embodiment of the method according to the invention is characterized in that for at least one evaluation point, a target residual astigmatism is specified which is smaller than the theoretically achievable residual astigmatism at the at least one corresponding evaluation point for a comparison progressive spectacle lens for an identical prescription, with the same distribution of the spherical equivalent and the same arrangement of the comparison progressive spectacle lens in front of the eye of the progressive spectacle wearer but with a spatially non-varying refractive index, and that the modification of the representation of the local surface geometry of the progressive surface and the local refractive index of the progressive spectacle lens in the respective visual beam path by the evaluation points is only terminated whenif the residual astigmatism achieved for the designed progressive lens at the at least one evaluation point is smaller than the theoretically achievable residual astigmatism at the at least one corresponding evaluation point for the comparison progressive lens.

[0082] As already explained above, the target residual astigmatism can be set to zero at all evaluation points. In order to design a progressive lens that has better optical properties across its entire surface than a conventional comparison progressive lens, the target residual astigmatism at all evaluation points must be selected to be at least a significant percentage, e.g., 10-50% lower than is usually used for designing the comparison progressive lens. In general, a target residual astigmatism will be specified at at least the evaluation points that is smaller than the theoretically achievable residual astigmatism at at least the corresponding evaluation points in the comparison progressive lens that are to lie within the subsequent progression channel. A widening of the progression channel is always desirable.

[0083] In addition or as an alternative to the advantageous embodiment described above, a method variant consists in modifying the representation of the local surface geometry of the progressive lens and the local refractive index of the progressive lens in the respective visual ray path by the evaluation points, with the proviso that the maximum value of the residual astigmatism of the progressive lens is smaller than the maximum value of the residual astigmatism of a comparison progressive lens for an identical prescription with the same distribution of the spherical equivalent and the same arrangement of the comparison progressive lens in front of the eye of the progressive lens wearer, but with a spatially non-varying refractive index. In principle, the maximum value for the residual astigmatism in the progressive lens designed according to the invention does not have to be at the "same" location orbe located at the "same" evaluation point as the maximum value for the residual astigmatism of the comparison progressive lens. However, this is also considered as an additional condition when carrying out the method. These specifications further improve the optical properties of the progressive lens according to the invention compared to a comparison progressive lens of conventional manufacture.

[0084] In one embodiment, the method according to the invention can be carried out in such a way that the design of the progressive spectacle lens results in a progressive spectacle lens corresponding to a product of the types described above. The advantages of these products have already been described in detail above.

[0085] In a further variant of the method according to the invention, it is even provided that the design of the progressive spectacle lens is carried out with the specific objective of producing a progressive spectacle lens corresponding to a product of one of the types described above. In this further variant, the desired properties and the termination conditions are selected such that the corresponding progressive spectacle lens with the optical properties described above is inevitably created during the design process when positioned in front of the eye of the future spectacle wearer in the manner specified by the representation.

[0086] The invention further provides a computer program with program code for performing all method steps according to one of the methods described above when the computer program is loaded into and / or executed on a computer. The computer program can be stored on any computer-readable medium, in particular on a computer hard drive, on a USB stick, or even in a cloud. Accordingly, the invention also seeks protection for a computer-readable medium with a computer program of the type described above.

[0087] The invention also relates to a method for producing a progressive spectacle lens according to one of the products described above or a progressive spectacle lens designed using a method of the variants described above by an additive method.

[0088] Additive processes are methods in which the progressive lens is built sequentially. In this context, it is particularly well known that so-called digital fabricators offer manufacturing options for almost any structure that is impossible or difficult to realize using conventional abrasive processes. Within the machine class of digital fabricators, 3D printers represent the most important subclass of additive, i.e. accumulating, building fabricators. The most important 3D printing techniques are selective laser melting (SLM) and electron beam melting for metals and selective laser sintering (SLS) for polymers, ceramics, and metals; stereolithography (SLA) and digital light processing for liquid synthetic resins; and multijet or polyjet modeling (e.g., inkjet printing) and fused deposition modeling (FDM) for plastics and some synthetic resins.A structure using nanolayers is also known, as described, for example, at http: / / peaknano.com / wpcontent / uploads / PEAK-1510-GRINOptics-Overview.pdf, downloaded on January 12, 2017.

[0089] Raw materials for production using 3D printing as well as possibilities for the 3D manufacturing process itself can be found, for example, in European patent application No. 16195139.7.

[0090] A further development of the invention consists in a method for producing a progressive spectacle lens comprising a method for designing a progressive spectacle lens as described above and manufacturing the progressive spectacle lens according to the design.

[0091] According to the invention, the progressive lens can be manufactured according to the design using an additive process.

[0092] Another development of the invention consists in a computer with a processor which is configured to carry out a method for designing a progressive spectacle lens according to one of the types or variants described above.

[0093] The invention is described in more detail below with reference to the drawings. They show: Figure 1 optical properties of a comparison progressive lens of conventional design made of a material with a refractive index of n=1,600 to a GRIN progressive lens with a vertical plane of symmetry according to a first embodiment of the invention a: mean spherical power of the comparison progressive lens b: mean surface refractive power of the comparison progressive lens, object-side freeform surface c: mean surface astigmatism for n=1,600 of the object-side freeform surface of the comparison progressive lens of the Figure 1aFigure 2 optical properties of the GRIN progressive lens according to the first embodiment a: mean spherical power b: mean surface refractive power calculated for a constant refractive index n=1,600 for the object-side free-form surface c: mean surface astigmatism for n=1,600 of the object-side free-form surface of the GRIN progressive lens of the Figure 2aFigure 3 shows the distribution of the refractive index of the GRIN progressive spectacle lens according to the first embodiment. Figure 4 shows a comparison of the residual astigmatism distribution of the GRIN progressive spectacle lens according to the first embodiment with the residual astigmatism distribution of the comparison progressive spectacle lens. a: residual astigmatism distribution of the comparison progressive spectacle lens. b: residual astigmatism distribution of the inventive GRIN progressive spectacle lens according to the first embodiment. Figure 5 shows a comparison of the residual astigmatism curve of the GRIN progressive spectacle lens according to the first embodiment with the residual astigmatism curve of the comparison progressive spectacle lens along a section at y=0 according to the Figure 4a: Residual astigmatism curve of the comparison progressive lens b: Residual astigmatism curve of the GRIN progressive lens according to the invention according to the first embodiment Figure 6 Comparison of the contour of the front surface of the GRIN progressive lens according to the first embodiment with the contour of the front surface of the comparison progressive lens a: Sagittarius of the front surface of the comparison progressive lens b: Sagittarius of the front surface of the GRIN progressive lens according to the invention according to the first embodiment Figure 7 Optical properties of a comparison progressive lens of conventional design made of a material with a refractive index of n=1,600 to a GRIN progressive lens with a vertical plane of symmetry according to a second embodiment of the invention a: mean spherical power b: mean surface refractive power, object-side freeform surface c: surface astigmatism for n=1.600 of the object-side free-form surface of the comparison progressive lens of the . Figure 7aFigure 8 optical properties of the GRIN progressive lens according to the second embodiment a: mean spherical power b: mean surface refractive power calculated for a refractive index n=1.600 for the object-side surface c: Course of the surface astigmatism of the front surface of the GRIN progressive spectacle lens according to the invention according to the second exemplary embodiment Figure 9 the distribution of the refractive index of the GRIN progressive spectacle lens according to the second exemplary embodiment Figure 10 Comparison of the residual astigmatism distribution of the GRIN progressive spectacle lens according to the second exemplary embodiment with the residual astigmatism distribution of the comparison progressive spectacle lens a: Residual astigmatism distribution of the comparison progressive spectacle lens b: Residual astigmatism distribution of the GRIN progressive spectacle lens according to the invention according to the second exemplary embodiment Figure 11 Comparison of the residual astigmatism course of the GRIN progressive spectacle lens according to the second exemplary embodiment with the residual astigmatism course of the comparison progressive spectacle lens along a section at y = -5 mm after the . Figure 10a: Residual astigmatism curve of the comparison progressive spectacle lens b: Residual astigmatism curve of the inventive GRIN progressive spectacle lens according to the first embodiment Figure 12 Comparison of the contour of the front surface of the GRIN progressive spectacle lens according to the second embodiment with the contour of the front surface of the comparison progressive spectacle lens; the sagittal angles are indicated relative to a plane tilted by -7.02° about the horizontal axis a: Sagittal angles of the front surface of the inventive GRIN progressive spectacle lens according to the second embodiment b: Sagittal angles of the front surface of the comparison progressive spectacle lens Figure 13 Optical properties of a comparison progressive spectacle lens of conventional design made of a material with a refractive index of n=1.600 to a GRIN progressive spectacle lens without any symmetry according to a third embodiment of the invention a: mean spherical power of the comparison progressive spectacle lens b: mean surface refractive power of the comparison progressive spectacle lens, object-side free-form surface Figure 14 optical properties of the GRIN progressive spectacle lens according to the third embodiment a: mean spherical power b: mean surface refractive power calculated for a refractive index n=1.600 Figure 15 the distribution of the refractive index of the GRIN progressive spectacle lens according to the third embodiment Figure 16 comparison of the residual astigmatism distribution of the GRIN progressive spectacle lens according to the third embodiment with the residual astigmatism distribution of the comparison progressive spectacle lens a: residual astigmatism distribution of the comparison progressive spectacle lens b: residual astigmatism distribution of the GRIN progressive spectacle lens according to the invention according to the third embodiment Figure 17 comparison of the residual astigmatism distribution of the GRIN progressive spectacle lens according to the third embodiment with the residual astigmatism distribution of the comparison progressive spectacle lens along a section at y = -5 mm after the . Figure 16a: Residual astigmatism distribution of the comparison progressive lens b: Residual astigmatism distribution of the inventive GRIN progressive lens according to the third embodiment Figure 18 Comparison of the contour of the front surface of the GRIN progressive lens according to the third embodiment with the contour of the front surface of the comparison progressive lens a: Sagittarius of the front surface of the comparison progressive lens b: Sagittarius of the front surface of the inventive GRIN progressive lens according to the third embodiment

[0094] The first three embodiments relate to GRIN progressive spectacle lenses or their representation in a computer memory corresponding to a product of the type according to the invention. The fourth embodiment shows an example of a method according to the invention for designing a GRIN progressive spectacle lens. First embodiment

[0095] In the first example, a progressive lens with a particularly simple surface geometry is chosen. It is constructed with mirror symmetry to a plane perpendicular to the plane of the drawing and essentially consists of only a central zone running vertically from top to bottom with a steadily increasing power.

[0096] Figure 1a shows the distribution of the mean spherical power in the beam path for the wearer for a progressive lens made of a standard material (refractive index n=1600) with an object-side freeform surface described by so-called bicubic splines. This progressive lens serves as a comparison progressive lens for a progressive lens designed according to the invention, which is hereinafter referred to as a GRIN progressive lens due to its spatially varying refractive index.

[0097] The back of the reference progressive lens is a spherical surface with a radius of 120 mm, and the ocular center of rotation is located behind the geometric center of the lens, 25.5 mm from the back surface. The lens has a center thickness of 2.5 mm and a prismatic power of 0 at the geometric center. The back surface is untilted, meaning that both the front and back surfaces have a normal to the direction of gaze at the geometric center, horizontally straight ahead.

[0098] The x and y coordinate axes shown are used to determine points on this surface. On the vertical center axis of the lens, the power exceeds 0.00 diopters at a height of approximately y = 25 mm, and a power of 2.25 dpt (diopters) is reached at approximately y = -25 mm. Over this length of 50 mm, the lens power increases by 2.25 dpt. Therefore, for the wearer in the intended wearing position, the progressive lens has no spherical power (sphere = 0) and no astigmatic power (cylinder = 0) in the distance portion, and an addition of 2.25 dpt. According to section 11.1 of DIN EN ISO 13666:2013-10, a spherical lens is a spectacle lens that focuses a paraxial, parallel beam of light at a single focal point. According to section 12.According to DIN EN ISO 13666:2013-10, a spectacle lens with an astigmatic power is a spectacle lens that combines a paraxial, parallel light beam into two separate, perpendicular focal lines and therefore has a vertex power only in the two principal sections. Section 14.2.1 of this standard defines addition as the difference between the vertex power of the near portion and the vertex power of the distance portion.

[0099] Figure 1b shows the mean surface refractive power for n=1,600 of the object-side free-form surface of the comparison progressive lens of the Figure 1a The surface curvature increases continuously from top to bottom, the mean surface refractive power increases from about 5.3 dpt at y = 15 mm to about 7.0 dpt at y = -25 mm.

[0100] Figure 1c shows the mean surface astigmatism for n=1,600 of the object-side freeform surface of the comparison progressive lens of the Figure 1a .

[0101] The Figures 2a , 2b and 2c show the replica of the comparison progressive lens using a GRIN material. Figure 2a shows the distribution of the mean spherical power. The comparison of the Figure 1a and Figure 2a one can see that the power distribution of the two progressive lenses is the same. Figure 2b is the course of the mean surface refractive power, in Figure 2c the course of the surface astigmatism of the front surface of the GRIN progressive lens designed according to the invention is shown. In order to compare the mean curvatures with the Figure 1b and surface astigmatism with the Figure 1c In order to enable this, the GRIN material was not used in the calculation of the mean surface refractive power and the surface astigmatism, but rather the material with the refractive index n=1,600 as before.

[0102] According to Heinz Diepes, Ralf Blendowske: Optics and Technology of Glasses; 2nd edition, Heidelberg 2005, p. 256, the mean surface refractive power and the surface astigmatism are defined.

[0103] The comparison of the Figures 2b and 2c with the Figures 1b and 1c shows that the shape of the freeform surface has changed significantly: The mean surface refractive power (calculated with n=1,600) now decreases from top to bottom, i.e., the mean curvature of the surface decreases from top to bottom. The course of the surface astigmatism no longer shows a typical progression channel.

[0104] Figure 3 shows the distribution of the refractive index across the GRIN progressive lens according to the invention. The refractive index increases from top to bottom from approximately n = 1.48 to approximately n = 1.75 in the lower region.

[0105] The Figure 4a and Figure 4bshow the effects of the use of the GRIN material with its special refractive index distribution, as well as the design of the freeform surface for this GRIN progressive lens, on the width of the progression channel compared to the standard lens. The figures show the distribution of the residual astigmatic errors in the beam path for the wearer of a spectacle wearer with a purely spherical prescription.

[0106] In this example, the progression channel, defined here by the isoastigmatism line 1 dpt, widens from 17 mm to 22 mm, i.e. by about 30 percent.

[0107] The Figure 5a and Figure 5b show cross sections through the residual astigmatism distributions from Figure 4a and Figure 4bHere, the conventional relationship between the increase in power and the resulting lateral increase in astigmatic error (similar to the relationship between the mean surface power and surface astigmatism according to Minkwitz's theorem) becomes particularly clear. The increase in astigmatism near the center of the progression channel (y = 0) is significantly lower for the GRIN lens, despite the same increase in power as in the standard lens. It is precisely this increase that is explained in the theory of progressive lens optics using Minkwitz's statement.

[0108] The Figure 6 compares the contour of the front surface of the GRIN progressive lens according to the first embodiment with the contour of the front surface of the comparison progressive lens using an arrow height representation. Figure 6b shows the arrow heights of the front surface of the GRIN progressive spectacle lens according to the invention according to the first embodiment and in comparison shows Figure 6a the arrow heights of the front surface of the comparison progressive lens. Second embodiment

[0109] All of the following figures correspond thematically and in sequence to those of the first embodiment.

[0110] The Figure 7a shows the distribution of the mean spherical power in the beam path for the progressive lens wearer for a reference progressive lens made of a standard material (refractive index n=1600) with a freeform surface on the object side. The back surface is again a spherical surface with a radius of 120 mm, and the eye's center of rotation is 4 mm above the geometric center of the reference progressive lens, with a horizontal distance of 25.8 mm to the back surface. The reference progressive lens has a center thickness of 2.6 mm and a prismatic power of 1.0 cm / m base 270° 2 mm below the geometric center. The back surface is tilted by -8° around the horizontal axis.

[0111] The coordinate axes shown serve to determine points on this surface. On the vertical center axis of the comparison progressive lens, the power exceeds the 0.00 diopter line at a height of approximately y = 6 mm (i.e., the wearer receives a power of almost 0 dpt when looking horizontally straight ahead), and a power of 2.00 diopters is achieved at approximately y = -14 mm. Over this length of 20 mm, the lens power therefore increases by 2.00 dpt.

[0112] Figure 7b shows the mean surface refractive power for n=1,600 of the object-side free-form surface of the comparison progressive lens of the Figure 7a The surface curvature increases continuously from top to bottom, the mean surface refractive power increases from 5.00 dpt at y = 2 mm to 6.75 dpt at y = -18 mm.

[0113] Figure 7c shows the surface astigmatism for n=1,600 of the object-side freeform surface of the comparison progressive lens of the Figure 7a .

[0114] The Figures 8a , 8b and 8c show the reproduction of the comparison progressive lens using a GRIN material (inventive progressive lens). Figure 8a shows the distribution of the mean spherical power. The comparison of the Figures 7a and 8a one can see that the increase in power along the vertical center line of the two lenses is the same. Figure 8b is the course of the mean surface refractive power, in Figure 8c the course of the surface astigmatism of the front surface of the GRIN progressive lens according to the invention is shown. In order to compare the mean curvatures with the Figure 7b and surface astigmatism with the Figure 7c In order to enable this, the GRIN material was not used in the calculation, but as before the material with the refractive index n=1.600.

[0115] The comparison of the Figures 8b and 8c with the Figures 7b and7c shows that the shape of the freeform surface has changed significantly: the mean surface refractive power (calculated with n=1,600) now decreases unevenly from the center of the lens to the edge. The course of the surface astigmatism no longer shows a typical progression channel.

[0116] The Figure 9 shows the distribution of the refractive index across the lens. The refractive index increases from approximately 1.60 in the center of the lens to approximately n = 1.70 in the lower region.

[0117] The Figure 10a and the Figure 10b show the effects of the use of the GRIN material with its special refractive index distribution, as well as the design of the freeform surface for this GRIN progressive lens, on the width of the progression channel in comparison to the comparison progressive lens. The figures show the distribution of the residual astigmatic errors in the beam path for the wearer for a wearer with a purely spherical prescription.

[0118] In this example, the progression channel, defined here by the isoastigmatism line 1 dpt, widens from 8.5 mm to 12 mm, i.e. by approximately 41 percent.

[0119] The Figure 11a and the Figure 11b show cross sections through the residual astigmatism distributions from Figure 10a and Figure 10bHere, the conventional relationship between the increase in power and the resulting lateral increase in astigmatic error (similar to the relationship between the mean surface refractive power and surface astigmatism according to Minkwitz's theorem) becomes particularly clear. The increase in astigmatism in the vicinity of the center of the progression channel (y = -5 mm) is significantly lower for the GRIN progressive lens according to the invention, although the same increase in power is present as in the comparison progressive lens. Analogous to the first exemplary embodiment, there is a clear deviation of the astigmatism gradient of the GRIN progressive lens from the behavior predicted by Minkwitz: the progression channel becomes significantly wider.

[0120] The Figure 12compares the contour of the front surface of the GRIN progressive lens according to the second embodiment with the contour of the front surface of the comparison progressive lens using an arrow height representation. Figure 12b shows the sagittal angles of the front surface of the GRIN progressive spectacle lens according to the invention according to the second embodiment and in comparison shows Figure 12a the sagittal angles of the front surface of the comparison progressive lens with respect to a coordinate system tilted by -7.02 around a horizontal axis (i.e. the vertical Y-axis of this system is tilted by -7.02° relative to the spatial vertical). Third embodiment

[0121] All of the following figures correspond thematically and in sequence to those of the second embodiment.

[0122] The third example shows two progressive lenses that take into account the convergence movement of the eye when looking at objects at intermediate and near distances that lie directly in front of the wearer's eye. This convergence movement causes the points of vision through the front surface of the lens to lie not on a perfectly vertical line when looking at these points, but rather on a vertical line tilted toward the nose, which is referred to as the principal line of sight.

[0123] Therefore, in these examples, the center of the near field is shifted horizontally in the nasal direction. The examples are calculated so that this main line of sight in the progression range lies midway between the lines on the front surface for which the residual astigmatic error is 0.5 dpt (see the Figures 16a and 16b ).

[0124] The Figure 13ashows the distribution of the mean spherical power in the beam path for the progressive lens wearer for a comparison progressive lens made of a standard material (refractive index n = 1.600) with a freeform surface on the object side. The back surface is again a spherical surface with a radius of 120 mm and the eye pivot point is 4 mm above the geometric center of the comparison progressive lens with a horizontal distance of 25.5 mm to the back surface. The comparison progressive lens has a center thickness of 2.5 mm and, 2 mm below the geometric center, a prismatic power of 1.0 cm / m base 270°. The back surface is tilted so that when looking horizontally straight ahead, the eye-side ray is perpendicular to the back surface.

[0125] When looking horizontally straight ahead (i.e., for a viewing point through the lens 4 mm above the geometric center), the wearer receives an average power of 0 dpt, and when looking through the point 13 mm below the geometric center and -2.5 mm horizontally in the nasal direction, an average power of 2.00 dpt. This means that over a length of 17 mm, the lens power increases by approximately 2.00 dpt.

[0126] Figure 13b shows the distribution of the mean surface refractive power for a refractive index n=1,600 of the object-side free-form surface of the comparative progressive spectacle lens of the third embodiment, which causes a distribution of the mean power as shown in Figure 13a The surface curvature increases steadily from top to bottom, the mean surface refractive power increases from 5.00 dpt at y = approximately 2 mm to 6.50 dpt at y = -12 mm.

[0127] The Figures 14a and 14bshow the reproduction of the comparison progressive lens using a GRIN material (inventive progressive lens). Figure 14a shows the distribution of the mean spherical power. The comparison of the Figures 13a and 14a one can see that the increase in effect along the main line of sight in the progression area is the same. Figure 14b The curve of the mean surface refractive power of the front surface of the GRIN progressive lens according to the invention is shown. In order to compare the mean curvatures with the Figure 13b In order to enable this, the GRIN material was not used in the calculation, but as before the material with the refractive index n = 1.600.

[0128] The comparison of the Figure 13b with the Figure 14bshows that the shape of the freeform surface has changed significantly: the average surface refractive index (calculated with n = 1,600) now decreases unevenly from the center of the lens to the edge, only to increase again towards the periphery.

[0129] The Figure 15 shows the distribution of the refractive index across the lens. The refractive index increases from approximately 1.48 in the upper region of the lens to approximately 1.70 at a height of y = -13 in the lower region.

[0130] The Figures 16a and 16b show the effects of the use of the GRIN material with its special refractive index distribution as well as the design of the freeform surface for this GRIN progressive lens on the width of the progression channel in comparison to the reference progressive lens. The figures show the distribution of the residual astigmatic errors in the beam path for the wearer for a wearer with a purely spherical prescription.

[0131] In this third example, the progression channel, defined here by the isoastigmatism line 1 dpt, widens from 6 mm to 9 mm, i.e. by approximately 50 percent.

[0132] The Figure 17a and the Figure 17b show cross sections through the residual astigmatism distributions from Figure 16a and Figure 16b These figures again illustrate the conventional relationship between the increase in power and the resulting lateral increase in astigmatic error (similar to the relationship between the mean surface power and surface astigmatism according to Minkwitz's theorem). The increase in the residual astigmatic error near the center of the progression channel (y = -5 mm) is again significantly lower for the GRIN progressive lens according to the invention, although the same increase in power is present as in the comparison progressive lens.

[0133] The Figure 18compares the contour of the front surface of the GRIN progressive lens according to the first embodiment with the contour of the front surface of the comparison progressive lens using an arrow height representation. Figure 18b shows the arrow heights of the front surface of the GRIN progressive spectacle lens according to the invention according to the third embodiment and in comparison shows Figure 18a the sagittal angles of the front surface of the comparison progressive lens with respect to a plane that is perpendicular to the direction of view horizontally straight ahead. Fourth embodiment

[0134] The following outlines the essential steps of a method according to the invention for designing a GRIN progressive lens: In a first step, individual user data or application data of the wearer are recorded. This includes the recording of (physiological) data attributable to the wearer and the recording of usage conditions under which the wearer will wear the progressive lens to be designed.

[0135] The wearer's physiological data includes, for example, their visual impairment and accommodative capacity, which are determined by means of a refraction measurement and are regularly incorporated into the prescription in the form of prescription values ​​for sphere, cylinder, axial position, prism, base, and addition. Furthermore, the pupillary distance and pupil size are determined under different lighting conditions. The wearer's age, for example, is taken into account, which influences the expected accommodative capacity and pupil size. The convergence behavior of the eyes results from the pupillary distance for different viewing directions and object distances.

[0136] The conditions of use include the position of the lenses in front of the eye (usually relative to the ocular center of rotation) and the object distances for different viewing directions at which the wearer should see clearly. The position of the lenses in front of the eye can be determined, for example, by measuring the corneal vertex distance, forward and lateral tilt.

[0137] This data is incorporated into an object distance model for which a ray tracing procedure can be carried out.

[0138] InIn a subsequent step, a design draft for the spectacle lens is determined based on this collected data, including multiple assessment points. The design draft includes the target optical properties for the progressive lens at the respective assessment point. These target properties include, for example, the permissible deviation from the prescribed spherical and astigmatic power, taking into account the addition, distributed across the entire progressive lens, as determined by the position of the lens in front of the eye and the underlying distance model.

[0139] Furthermore, a design of surface geometries for the front and rear surfaces, as well as a design for a refractive index distribution across the entire lens, are defined. For example, the front surface can be selected as a spherical surface and the rear surface as a progressive surface. Both surfaces could also be initially selected as spherical surfaces. The choice of surface geometry for the initial design generally only determines the convergence (speed and success) of the applied optimization method. For example, it should be assumed that the front surface should retain its spherical shape and the rear surface should take the form of a progressive surface.

[0140] In a further step, the path of the principal rays is determined through the multiple evaluation points. If necessary, a local wavefront can be determined for each of the principal rays in a vicinity of the respective principal ray.

[0141] In a subsequent step, the above-mentioned optical properties of the spectacle lens at the evaluation points are determined by determining the influence of the spectacle lens on the beam path of the principal rays and, if applicable, the local wavefronts in the vicinity of the respective evaluation point.

[0142] In a further step, the lens design is evaluated depending on the determined optical properties and the individual user data. The back surface and the refractive index distribution of the lens design are then analyzed with a view to minimizing an objective function. F = ∑ m P m ∑ n W n T n − A n 2 modified, whereby P m the weighting at the assessment point m, W n the weighting of the optical property n, T n the target value of the optical property n at the respective evaluation point m and A n represents the actual value of the optical property n at the evaluation point m.

[0143] In other words, the local surface geometry of the back surface and the local refractive index of the progressive lens in the respective visual path are modified by the evaluation centers until a termination criterion is met.

[0144] The GRIN progressive lens designed in accordance with the invention can then be manufactured according to this design.

Claims

1. Product comprising a progressive power spectacle lens or a representation of the progressive power spectacle lens situated on a data medium in the form of computer-readable data with instructions for production by an additive method, the progressive power spectacle lens comprising (a) a front surface embodied as a progressive surface with a front surface geometry and a back surface with a back surface geometry or (b) a back surface embodied as a progressive surface with a back surface geometry and a front surface with a front surface geometry and - a spatially varying refractive index, characterized in that - the product further comprises a representation, situated on a data medium, of a predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that - the progressive power spectacle lens has a distribution of a spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that - the product further comprises (i) a representation, situated on a data medium, of a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (ii) a representation, situated on a data medium, of an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (iii) a representation, situated on a data medium, of a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (iv) a representation, situated on a data medium, of a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and in that the refractive index of the progressive power spectacle lens varies in space in such a way that the maximum value of the residual astigmatism of the progressive power spectacle lens is less than the maximum value of the residual astigmatism of a comparison progressive power spectacle lens with a spatially non-varying refractive index but with the same distribution of the spherical equivalent in the case of the same arrangement of the comparison progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, wherein the maximum value of the residual astigmatism of the comparison progressive power spectacle lens is situated at the same location as the maximum value of the residual astigmatism of the progressive power spectacle lens, wherein - in case (a), the front surface geometry of the front surface, embodied as a progressive surface, of the progressive power spectacle lens has a modified embodiment in relation to a front surface geometry of a front surface, embodied as a progressive surface, of the comparison progressive power spectacle lens and the back surface geometry of the back surface of the progressive power spectacle lens has an identical embodiment to a back surface geometry of a back surface of the comparison progressive power spectacle lens and - in case (b), the back surface geometry of the back surface, embodied as a progressive surface, of the progressive power spectacle lens has a modified embodiment in relation to a back surface geometry of a back surface, embodied as a progressive surface, of the comparison progressive power spectacle lens and the front surface geometry of the front surface of the progressive power spectacle lens has an identical embodiment to a front surface geometry of a front surface of the comparison progressive power spectacle lens.

2. Product according to Claim 1, characterized in that at least one of the freeform surfaces has no point symmetry and no axial symmetry or in that at least one of the freeform surfaces has no point symmetry and no axial symmetry and no rotational symmetry and no symmetry with respect to a plane of symmetry.

3. Product according to either of Claims 1 and 2, characterized in that the progressive power spectacle lens comprises an intermediate corridor and in that - the front surface embodied as a freeform surface is formed in such a way that the mean curvature has a maximum in the intermediate corridor and / or - the back surface embodied as a freeform surface is formed in such a way that the mean curvature has a minimum in the intermediate corridor.

4. Product according to any of Claims 1 to 3, characterized in that - the product further comprises a representation, situated on a data medium, of a predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that - the progressive power spectacle lens has a distribution of a spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that - the progressive power spectacle lens has an intermediate corridor with a width and in that the refractive index of the progressive power spectacle lens varies in space in such a way that the width of the intermediate corridor of the progressive power spectacle lens, at least in a section or over the entire length of the intermediate corridor, is greater than the width of the intermediate corridor of a comparison progressive power spectacle lens with the same distribution of the spherical equivalent in the case of the same arrangement of the comparison progressive power spectacle lens in front of the eye of the progressive power spectacle wearer but with a spatially non-varying refractive index.

5. Product according to Claim 4, characterized in that a variant of the group: - horizontal section, - section at half addition, - horizontal section at half addition, - horizontal section at half addition and horizontal section at 25% of the addition, - horizontal section at half addition and horizontal section at 75% of the addition, - horizontal section at half addition and horizontal section at 25% of the addition and horizontal section at 75% of the addition, is chosen for the at least one section.

6. Product according to Claim 4 or 5, characterized in that - the product further comprises (i) a representation, situated on a data medium, of a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (ii) a representation, situated on a data medium, of an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (iii) a representation, situated on a data medium, of a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (iv) a representation, situated on a data medium, of a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that - the progressive power spectacle lens has a distance portion and a near portion, and in that - the width of the intermediate corridor corresponds to the dimension transverse to a longitudinal direction of the intermediate corridor extending between the distance portion and near portion, within which the absolute value of the residual astigmatism lies below a predetermined limit value, which is selected within a range from the group specified below: (a) the limit value lies in the range between 0.25 dpt and 1.5 dpt, (b) the limit value lies in the range between 0.25 dpt and 1.0 dpt, (c) the limit value lies in the range between 0.25 dpt and 0.75 dpt, (d) the limit value lies in the range between 0.25 dpt and 0.6 dpt, (e) the limit value lies in the range between 0.25 dpt and 0.5 dpt, (f) the limit value is 0.5 dpt.

7. Product according to any of the preceding claims, characterized in that - the product further comprises a representation, situated on a data medium, of a predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that - the progressive power spectacle lens has a distribution of a spherical equivalent (W) for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that - the product further comprises (i) a representation, situated on a data medium, of a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (ii) a representation, situated on a data medium, of an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (iii) a representation, situated on a data medium, of a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (iv) a representation, situated on a data medium, of a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and in that - the progressive power spectacle lens comprises an intermediate corridor and a principal line of sight, and in that the refractive index of the progressive power spectacle lens varies in space in such a way that for a predetermined residual astigmatism value ARest,Grenz of the group (a) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 1.5 dpt, (b) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 1.0 dpt, (c) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 0.75 dpt, (d) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 0.6 dpt, (e) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 0.5 dpt, (f) the residual astigmatism value ARest,Grenz is 0.5 dpt on a horizontal section at the narrowest point of the intermediate corridor or for a horizontal section through the point on the principal line of sight at which the half addition is achieved, the following relationship applies within a region with a horizontal distance of 10 mm on both sides of the principal line of sight: B > c × A Rest , Grenz grad W where grad W describes the power gradient of the spherical equivalent of the progressive power spectacle lens at the narrowest point of the intermediate corridor on the principal line of sight or in a point on the principal line of sight at which the half addition is achieved, B describes the width of the region in the progressive power spectacle lens in which the residual astigmatism is ARest ≤ ARest,Grenz, where c is a constant selected from the group: (a) 1.0 < c , (b) 1.1 < c , (c) 1.2 < c , (d) 1.3 < c .

8. Product comprising a progressive power spectacle lens or a representation of the progressive power spectacle lens situated on a data medium in the form of computer-readable data with instructions for production by an additive method, the progressive power spectacle lens comprising - a front surface and a back surface, and - a spatially varying refractive index, wherein - the front surface is embodied as a progressive surface and / or the back surface is embodied as a progressive surface, wherein - the front surface embodied as a progressive surface is embodied as a freeform surface and / or the back surface embodied as a progressive surface is embodied as a freeform surface, characterized in that - the product further comprises a representation, situated on a data medium, of a predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that - the progressive power spectacle lens has a distribution of a spherical equivalent (W) for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that - the product further comprises (i) a representation, situated on a data medium, of a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (ii) a representation, situated on a data medium, of an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (iii) a representation, situated on a data medium, of a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (iv) a representation, situated on a data medium, of a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and in that - the progressive power spectacle lens comprises an intermediate corridor and a principal line of sight, and in that the refractive index of the progressive power spectacle lens varies in space in such a way that for a predetermined residual astigmatism value ARest,Grenz of the group (a) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 1.5 dpt, (b) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 1.0 dpt, (c) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 0.75 dpt, (d) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 0.6 dpt, (e) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 0.5 dpt, (f) the residual astigmatism value ARest,Grenz is 0.5 dpt on a horizontal section at the narrowest point of the intermediate corridor or for a horizontal section through the point on the principal line of sight at which the half addition is achieved, the following relationship applies within a region with a horizontal distance of 10 mm on both sides of the principal line of sight: B > c × A Rest , Grenz grad W where grad W describes the power gradient of the spherical equivalent of the progressive power spectacle lens at the narrowest point of the intermediate corridor on the principal line of sight or in a point on the principal line of sight at which the half addition is achieved, B describes the width of the region in the progressive power spectacle lens in which the residual astigmatism is ARest ≤ ARest,Grenz, where c is a constant selected from the group: (a) 1.0 < c , (b) 1.1 < c , (c) 1.2 < c , (d) 1.3 < c .

9. Product according to Claim 8, characterized in that at least one of the freeform surfaces has no point symmetry and no axial symmetry or in that at least one of the freeform surfaces has no point symmetry and no axial symmetry and no rotational symmetry and no symmetry with respect to a plane of symmetry.

10. Product according to either of Claims 8 and 9, characterized in that the progressive power spectacle lens comprises an intermediate corridor and in that - the front surface embodied as a freeform surface is formed in such a way that the mean curvature has a maximum in the intermediate corridor and / or - the back surface embodied as a freeform surface is formed in such a way that the mean curvature has a minimum in the intermediate corridor.

11. Product according to any of Claims 8 to 10, characterized in that - the product further comprises a representation, situated on a data medium, of a predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that - the progressive power spectacle lens has a distribution of a spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that - the progressive power spectacle lens has an intermediate corridor with a width and in that the refractive index of the progressive power spectacle lens varies in space in such a way that the width of the intermediate corridor of the progressive power spectacle lens, at least in a section or over the entire length of the intermediate corridor, is greater than the width of the intermediate corridor of a comparison progressive power spectacle lens with the same distribution of the spherical equivalent in the case of the same arrangement of the comparison progressive power spectacle lens in front of the eye of the progressive power spectacle wearer but with a spatially non-varying refractive index.

12. Product according to Claim 11, characterized in that a variant of the group: - horizontal section, - section at half addition, - horizontal section at half addition, - horizontal section at half addition and horizontal section at 25% of the addition, - horizontal section at half addition and horizontal section at 75% of the addition, - horizontal section at half addition and horizontal section at 25% of the addition and horizontal section at 75% of the addition, is chosen for the at least one section.

13. Product according to Claim 11 or 12, characterized in that - the product further comprises (i) a representation, situated on a data medium, of a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (ii) a representation, situated on a data medium, of an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (iii) a representation, situated on a data medium, of a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (iv) a representation, situated on a data medium, of a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that - the progressive power spectacle lens has a distance portion and a near portion, and in that - the width of the intermediate corridor corresponds to the dimension transverse to a longitudinal direction of the intermediate corridor extending between the distance portion and near portion, within which the absolute value of the residual astigmatism lies below a predetermined limit value, which is selected within a range from the group specified below: (a) the limit value lies in the range between 0.25 dpt and 1.5 dpt, (b) the limit value lies in the range between 0.25 dpt and 1.0 dpt, (c) the limit value lies in the range between 0.25 dpt and 0.75 dpt, (d) the limit value lies in the range between 0.25 dpt and 0.6 dpt, (e) the limit value lies in the range between 0.25 dpt and 0.5 dpt, (f) the limit value is 0.5 dpt.

14. Product according to any of Claims 8 to 13, characterized in that - the product further comprises a representation, situated on a data medium, of a predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that - the progressive power spectacle lens has a distribution of a spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that - the product further comprises (i) a representation, situated on a data medium, of a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (ii) a representation, situated on a data medium, of an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (iii) a representation, situated on a data medium, of a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and / or (iv) a representation, situated on a data medium, of a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and in that - the refractive index of the progressive power spectacle lens varies in space in such a way that the maximum value of the residual astigmatism of the progressive power spectacle lens is less than the maximum value of the residual astigmatism of a comparison progressive power spectacle lens with the same distribution of the spherical equivalent in the case of the same arrangement of the comparison progressive power spectacle lens in front of the eye of the progressive power spectacle wearer but with a spatially non-varying refractive index.

15. Product according to any of Claims 8 to 14, characterized in that - the progressive power spectacle lens consists of a substrate comprising no individual layers and having a front surface and a back surface and the spatially varying refractive index, and a front surface coating, comprising one or more individual layers, on the front surface of the substrate and / or a back surface coating, comprising one or more individual layers, on the back surface of the substrate, and in that - a difference between the spherical equivalent measured at each point on the front surface of the progressive power spectacle lens with the front surface coating and / or the back surface coating and the spherical equivalent measured at each corresponding point on the front surface of a comparison progressive power spectacle lens without front surface coating and without back surface coating but with an identical substrate is less than a value from the group specified below: (a) the difference value is less than 0.001 dpt, (b) the difference value is less than 0.002 dpt, (c) the difference value is less than 0.003 dpt, (d) the difference value is less than 0.004 dpt.

16. Computer-implemented method for designing a progressive power spectacle lens having addition power or degression power, for the purpose of using the design for the production of the progressive power spectacle lens, the progressive power spectacle lens having a front surface and a back surface and a spatially varying refractive index, wherein the front surface is embodied as a progressive surface and / or the back surface is embodied as a progressive surface, wherein the progressive power spectacle lens has a distribution of a spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, wherein the progressive power spectacle lens has an intermediate corridor with a width, wherein - optical properties of the progressive power spectacle lens are calculated by means of a ray tracing method at a plurality of evaluation points, at which visual rays pass through the progressive power spectacle lens, wherein - at least one intended optical property for the progressive power spectacle lens is set at the respective evaluation point, - a design for the progressive power spectacle lens is set, wherein the design comprises a representation of a local surface geometry of the progressive surface and a local refractive index of the progressive power spectacle lens in the respective visual beam path through the evaluation points, wherein - the design of the progressive power spectacle lens is modified in view of an approximation of the at least one intended optical property of the progressive power spectacle lens, wherein the modification comprises modifying the representation of the local surface geometry of the progressive surface and the local refractive index of the progressive power spectacle lens in the respective visual beam path through the evaluation points, wherein the at least one intended optical property comprises an intended residual astigmatism of the progressive power spectacle lens, wherein the design of the progressive power spectacle lens is implemented with the stipulation that - the addition power or the degression power is at least partly provided by the spatially varying refractive index, - the refractive index of the progressive power spectacle lens varies in space in such a way that the width of the intermediate corridor of the progressive power spectacle lens, at least in sections of the group (a) horizontal section at half addition and horizontal section at 25% of the addition, (b) horizontal section at half addition and horizontal section at 75% of the addition, (c) horizontal section at half addition and horizontal section at 25% of the addition and horizontal section at 75% of the addition, (d) horizontal section at the narrowest point of the intermediate corridor or over the entire length of the intermediate corridor, is greater than the width of the intermediate corridor of a comparison progressive power spectacle lens with a spatially non-varying refractive index but the same distribution of the spherical equivalent in the case of the same arrangement of the comparison progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, wherein the width of the intermediate corridor corresponds to the dimension transverse to a longitudinal direction of the intermediate corridor extending between the distance portion and near portion, within which the absolute value of the residual astigmatism lies below a predetermined limit value, which is selected within a range from the group specified below: (a) the limit value lies in the range between 0.25 dpt and 1.0 dpt, (b) the limit value lies in the range between 0.25 dpt and 0.75 dpt, (c) the limit value lies in the range between 0.25 dpt and 0.6 dpt, (d) the limit value lies in the range between 0.25 dpt and 0.5 dpt, (e) the limit value is 0.5 dpt.

17. Computer-implemented method for designing a progressive power spectacle lens having addition power or degression power, for the purpose of using the design for the production of the progressive power spectacle lens, the progressive power spectacle lens having a front surface and a back surface, wherein the progressive power spectacle lens comprises (a) a front surface embodied as a progressive surface with a front surface geometry and a back surface with a back surface geometry or (b) a back surface embodied as a progressive surface with a back surface geometry and a front surface with a front surface geometry and - a spatially varying refractive index, wherein the progressive power spectacle lens has a distribution of a spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, wherein - optical properties of the progressive power spectacle lens are calculated by means of a ray tracing method at a plurality of evaluation points, at which visual rays pass through the progressive power spectacle lens, wherein - at least one intended optical property for the progressive power spectacle lens is set at the respective evaluation point, - a design for the progressive power spectacle lens is set, wherein the design comprises a representation of a local surface geometry of the progressive surface and a local refractive index of the progressive power spectacle lens in the respective visual beam path through the evaluation points, wherein - the design of the progressive power spectacle lens is modified in view of an approximation of the at least one intended optical property of the progressive power spectacle lens, wherein the modification comprises modifying the representation of the local surface geometry of the progressive surface and the local refractive index of the progressive power spectacle lens in the respective visual beam path through the evaluation points, wherein the at least one intended optical property comprises an intended residual astigmatism of the progressive power spectacle lens, wherein the design of the progressive power spectacle lens is implemented with the stipulation that - the refractive index of the progressive power spectacle lens varies in space in such a way that the maximum value of the residual astigmatism of the progressive power spectacle lens is less than the maximum value of the residual astigmatism of a comparison progressive power spectacle lens with a spatially non-varying refractive index but the same distribution of the spherical equivalent in the case of the same arrangement of the comparison progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, wherein - in case (a), the front surface geometry of the front surface, embodied as a progressive surface, of the progressive power spectacle lens is modified in relation to a front surface geometry of a front surface, embodied as a progressive surface, of the comparison progressive power spectacle lens and the back surface geometry of the back surface of the progressive power spectacle lens is identical to a back surface geometry of a back surface of the comparison progressive power spectacle lens and - in case (b), the back surface geometry of the back surface, embodied as a progressive surface, of the progressive power spectacle lens is modified in relation to a back surface geometry of a back surface, embodied as a progressive surface, of the comparison progressive power spectacle lens and the front surface geometry of the front surface of the progressive power spectacle lens is identical to a front surface geometry of a front surface of the comparison progressive power spectacle lens.

18. Computer-implemented method for designing a progressive power spectacle lens, for the purpose of using the design for the production of the progressive power spectacle lens, the progressive power spectacle lens having a front surface, a back surface and a spatially varying refractive index, wherein the front surface is embodied as a progressive surface and / or the back surface is embodied as a progressive surface, wherein - optical properties of the progressive power spectacle lens are calculated by means of a ray tracing method at a plurality of evaluation points, at which visual rays pass through the progressive power spectacle lens, wherein - at least one intended optical property for the progressive power spectacle lens is set at the respective evaluation point, - a design for the progressive power spectacle lens is set, wherein the design comprises a representation of a local surface geometry of the progressive surface and a local refractive index of the progressive power spectacle lens in the respective visual beam path through the evaluation points, wherein - the design of the progressive power spectacle lens is modified in view of an approximation of the at least one intended optical property of the progressive power spectacle lens, wherein the modification comprises modifying the representation of the local surface geometry of the progressive surface and the local refractive index of the progressive power spectacle lens in the respective visual beam path through the evaluation points, wherein the at least one intended optical property comprises an intended residual astigmatism of the progressive power spectacle lens, wherein - the progressive power spectacle lens comprises an intermediate corridor and a principal line of sight, and the refractive index of the progressive power spectacle lens varies in space in such a way that for a predetermined residual astigmatism value ARest,Grenz of the group (a) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 1.5 dpt, (b) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 1.0 dpt, (c) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 0.75 dpt, (d) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 0.6 dpt, (e) the residual astigmatism value ARest,Grenz lies in the range between 0.25 dpt and 0.5 dpt, (f) the residual astigmatism value ARest,Grenz is 0.5 dpt on a horizontal section at the narrowest point of the intermediate corridor or for a horizontal section through the point on the principal line of sight at which the half addition is achieved, the following relationship applies within a region with a horizontal distance of 10 mm on both sides of the principal line of sight: B > c × A Rest , Grenz grad W where grad W describes the power gradient of the spherical equivalent of the progressive power spectacle lens at the narrowest point of the intermediate corridor on the principal line of sight or in a point on the principal line of sight at which the half addition is achieved, B describes the width of the region in the progressive power spectacle lens in which the residual astigmatism is ARest ≤ ARest,Grenz, where c is a constant selected from the group: (a) 1.0 < c , (b) 1.1 < c , (c) 1.2 < c , (d) 1.3 < c .

19. Method according to any of Claims 16 to 18, characterized in that the modification of the design of the progressive power spectacle lens is implemented in view of a minimization of a target function F = ∑ m P m ∑ n W n T n − A n 2 where Pm represents the weighting at the evaluation point m, Wn represents the weighting of the optical property n, Tn represents the intended value of the optical property n at the respective evaluation point m and An represents the actual value of the optical property n at the evaluation point m.

20. Method according to any of Claims 16 to 19, characterized in that an intended residual astigmatism is predetermined for at least one evaluation point, said intended residual astigmatism being less than the theoretically achievable residual astigmatism at the at least one corresponding evaluation point on a comparison progressive power spectacle lens with the same distribution of the spherical equivalent and the same arrangement of the comparison progressive power spectacle lens in front of the eye of the progressive power spectacle wearer but with a spatially non-varying refractive index, and in that modifying the representation of the local surface geometry of the progressive surface and of the local refractive index of the progressive power spectacle lens in the respective visual beam path through the evaluation points is only terminated if the residual astigmatism at the at least one evaluation point, achieved for the designed progressive power spectacle lens, is less than the theoretically achievable residual astigmatism at the at least one corresponding evaluation point on the comparison progressive power spectacle lens.

21. Method according to any of Claims 16 to 20, characterized in that designing the progressive power spectacle lens results in a progressive power spectacle lens corresponding to a product according to any of Claims 1 to 15 or in that the progressive power spectacle lens is designed with the stipulation that a progressive power spectacle lens corresponding to a product according to any of Claims 1 to 15 should be produced.

22. Computer program having program code for carrying out all method steps according to any of Claims 16 to 21 when the computer program is loaded on a computer and / or executed on a computer.

23. Computer-readable medium comprising a computer program according to Claim 22.

24. Method for producing a progressive power spectacle lens, comprising a method according to any of Claims 16 to 21 and manufacturing of the progressive power spectacle lens according to the design.

25. Method according to Claim 24, characterized in that the progressive power spectacle lens is manufactured using an additive method.

26. Computer comprising a processor and comprising a memory in which a computer program according to Claim 22 is stored, said computer being configured to execute a method according to any of Claims 16 to 21.