BR112022002394B1 - INTRAOCULAR LENS WITH EXTENDED DEPTH OF FOCUS - Google Patents

Abstract

INTRAOCULAR LENS WITH EXTENDED DEPTH OF FOCUS. This is an intraocular lens (1) with extended depth of focus that comprises anterior and posterior aspherical optical surfaces (2, 3).

Description

Technical Field

[001] This invention relates to an intraocular lens (IOL). More specifically, it relates to an intraocular lens with extended depth of focus (EDOF).

Previous Technique

[002] Age-related protein changes in an eye's natural lens can lead to cataract formation. In cataract surgery, the natural lens is usually replaced with an IOL.

[003] An implant of a monofocal IOL generally provides good quality vision when selecting an appropriate IOL power, generally adjusted for long distances.

[004] However, an eye with an implanted IOL loses its residual accommodative capacity. It follows that a patient with an implanted monofocal IOL often needs to wear glasses for near and intermediate distances during activities that require sharper vision capabilities. This refers to a wide range of activities, such as reading and computer work, with possible strong consequences for the patient's daily life.

[005] Nowadays, patients increasingly want to avoid wearing glasses for near vision after cataract surgery. Multifocal IOLs are becoming more widely used to try to compensate for the weakness of monofocal IOLs mentioned above.

[006] However, multifocal IOLs typically have a limited number of two or three focal points, while providing poor vision quality for out-of-focus distances. This can lead to difficulties with intermediate vision in the case of, for example, bifocal IOLs that are designed with two focal points for near and far distances, respectively, and may then lead to the need for the patient to wear glasses. Another disadvantage in the specific case of diffractive multifocal IOLs is related to the existence of a proportion of incident light loss (about 18%) at high diffraction orders, which generate focal points outside the range of useful distance for vision. In addition, multifocal IOLs present other disadvantageous side effects, such as stray light, halos and glare.

Disclosure of the invention

[007] An objective of the present invention is to provide an intraocular lens presenting better quality vision at long and intermediate distances, minimizing the above-mentioned side effects.

[008] To this end, the present invention provides an intraocular lens comprising: • a (single) anterior optical surface; and • a (single) posterior optical surface, both extending around and substantially radially outwardly relative to an optical axis; wherein: • the first surface between the anterior and posterior optical surfaces is defined by the equation: where: • zst (r) is a component, measured along the optical axis, of a displacement vector from a vertex of the first surface, to any point on the latter at a radius r (considered as a radial variable) from the optical axis • is a radius of curvature of the first surface evaluated at (its) vertex; • is a conic constant of the first surface evaluated at (its) vertex and defined as a function of the said radius of curvature Rst of the first surface by the relation: where erf denotes a (a) Gaussian error function, and where a, b, c, A, B, C, D are constant real numbers, such as: a ϵ [0.050; 0.075], b ϵ [-1; 0], c ϵ [-20; 0], A ϵ [-41; -39], B ϵ [0.07; 0.13], C ϵ [-2.6; -2.0] and D ϵ [0.75; 1.25]; (for each 𝑖 ≥ 2) is an asphericity coefficient of order 2i of the first surface; the second surface between the anterior and posterior optical surfaces is defined by the equation: where: • znd (r) is a component, measured along the optical axis, of a displacement vector from a vertex of the second surface to any point on the latter at a radius r (considered as a radial variable) from the optical axis; • Rnd < 0 is a radius of curvature of the second surface evaluated at (its) vertex; • Knd (Rnd) is a conic constant of the second surface evaluated at (its) vertex and defined as a function of said radius of curvature Rnd of the second surface by the relation: where f, g, h are constant real numbers, such as: f ϵ [0.08; 0.12], g ϵ [1.0; 1.6] and h ϵ [0; 9]; • (for each 𝑖 ≥ 2) is a coefficient of asphericity of order 2i of the second surface. The anterior and posterior optical surfaces (or equivalently, the so-called first and second surfaces) are such that the intraocular lens provides an extended depth of focus.

[009] The intraocular lens (IOL) according to the invention presents a better quality vision at long and intermediate distances (than a bifocal intraocular lens with two focal points for long and near distances, for example), while both minimizing side effects such as stray light, halos and glare, and providing better quality of vision at long distances (than a standard monofocal IOL, for example).

[010] In fact, the IOL comprises an optic (or central optical part) comprising an anterior surface (called anterior optic surface) and a posterior surface (called posterior optic surface) described by an equation of the same form. It is well known to one skilled in the art that such an equation defines an aspherical surface (as reviewed in the detailed description, in view of figure 4 introduced below). Therefore, both the anterior and the posterior optical surfaces are aspherical, thus providing an optic with a fully aspherical design that generates more negative spherical aberrations and allows, with the contribution of the parameters of the equations of the surfaces, an extension of the depth of focus (i.e. providing a single elongated focal point to improve the “range of vision”), compared to a standard monofocal IOL. This is further commented and illustrated in the detailed description, in view of figures 6A-C, 7, 8, 9A-C, presented below, which present results of experimental measurements.

[011] The IOL according to the invention can be considered a monofocal IOL, since it causes a single focal point (like a monofocal IOL) to be elongated in order to increase the depth of focus (or range of vision). It is not designed as a multifocal IOL with a regularized optical power map between focus points, nor as a multizonal optical power IOL. This is noticeable because most monofocal IOLs only correct vision to help cataract patients see at (long) distances and thus do not improve the intermediate vision necessary for many important daily tasks. In contrast, the present monofocal IOL (with elongated focal point) offers improved intermediate vision as well as good vision at (long) distances, which is a great advance in allowing patients greater ease in their daily activities.

[012] The IOL according to the invention advantageously provides an extended depth of focus (EDOF) while minimally affecting peak resolution (i.e., better focus), providing clear vision at intermediate distance and minimizing side effects such as stray light, halos and glare that are common for multifocal IOLs. Indeed, refractive multifocal IOLs typically comprise a multizonal optic (and then anterior and posterior optical surfaces) divided into several sections (with surface geometries that are potentially described by different equations) that can cause diffraction problems such as halos due to abrupt changes in geometry and/or optical power between these sections. In contrast, the IOL of the invention comprises a single continuous and regular (or, in other words, at least differentiable or smooth) anterior optical surface and a single continuous and regular posterior surface, each surface being aspherical and described by a single smooth equation, which prevents such halos. It will be clearly understood by one skilled in the art that an IOL optical surface can be verified as satisfying such an equation (in general) by simple profile comparison or superposition or, if more in-depth analysis is required, by obtaining measurements of points on (a cross-sectional curve of) the IOL surface and comparing such measurements with the equation to determine the IOL optical surface equation. Comparison of IOL optical performances, such as EDOF or otherwise, as described in the detailed description, can also be applied.

[013] The IOL according to the invention is preferably refractive, more preferably purely refractive. More specifically, the characteristics optically provided by the anterior and posterior surfaces are preferably refractive. However, an IOL comprising any diffractive characteristic (such as a component, an optical surface portion, ...) is not excluded from the scope of the invention.

[014] Another important aspect of the present invention is that the claimed EDOF depends to a limited extent (or, in other words, is relatively independent): - on the optical power of the IOL; - on an aperture (i.e., an opening through which light moves; for example, a diameter of the pupil of the eye when the IOL is in normal use in an aphakic eye) and spherical aberrations of the cornea (for example, spherical aberrations of a model cornea or spherical aberrations of a cornea of the eye when the IOL is in normal use in an aphakic eye). This is further commented on in the detailed description, in view of figures 6A-B and 7, presented below. However, the good control of the EDOF, the aperture and the dependence of the spherical aberrations of the cornea on the optical power of the IOL can also be understood from the aspheric equations defining the anterior and posterior optical surfaces. Indeed, it is known to the person skilled in the art that the optical power of an optical surface depends, in general, on the refractive index associated with a raw material constituting this surface, as well as on the geometry of this surface. The latter is determined (at least to small orders of r) by the radius of curvature and (optionally) by the conic constant of this optical surface evaluated at its vertex. In the present context, it is rational to assume that both this refractive index and the contribution of each of the anterior and posterior optical surfaces to the overall optical power of the IOL are known. Furthermore, each of the conic constants of the anterior and posterior optical surfaces is defined as a function of the radius of curvature of this surface by completely new, specific and very advantageous smooth relations. As a consequence, at least to small orders, for each optical power of the IOL, each of the anterior and posterior optical surfaces is characterized by its radius of curvature. Since all the relationships between these parameters and the optical power of the IOL are regular, the variations of the geometry of the anterior and posterior optical surfaces in relation to the optical power of the IOL are then predetermined and regular, which allows (at least locally) a controlled and regular variation of the EDOF in relation to the optical power of the IOL, the aperture and the spherical aberrations of the cornea.

[015] These direct or indirect controlled regular variations of the parameters in the equations of the anterior and posterior optical surfaces with respect to the IOL optical power are very important to achieve this technical effect. In particular, it should be underlined that the present invention proposes a global optimization of the parameters of the equations taking into account this objective for limited EDOF dependence. It does not use any separate optimization of each of the parameters independently for each IOL optical power, which would be a more naive approach but would also generate a high EDOF dependence on the IOL optical power.

[016] Furthermore, and advantageously, the invention also takes into account the modulation transfer function (MTF) (i.e., an optical bench measurement used to evaluate the performance of a lens, generally speaking, an image resolution function; more specifically, this function is known to one skilled in the art and specifies how much contrast is captured as a function of spatial frequency) that is associated with the IOL. In general, the MTF at best focus (i.e., for long distances) is inversely related to the EDOF, which makes it very difficult to obtain MTF and EDOF, limited dependence on the optical power of the IOL, the spherical aberrations of a cornea model that equips an optical bench, and the aperture. But, in the case of the present invention, the parameters of the equations that define the anterior and posterior optical surfaces vary in order to obtain such limited dependence. This is illustrated in the detailed description, in view of figures 6C and 8, presented below. The ranges for the constant real numbers are chosen around specific preferred values detailed below. These values optimize both the EDOF and the MTF for optical surfaces made from an average raw biomaterial of average refractive index (e.g. around 1.52), in the sense that they consist of a good regular compromise between providing an optimized EDOF or an optimized MTF, for the optical powers considered (on which the radii of curvature of the optical surfaces depend). To take into account such variations in values that may arise from the choice of raw biomaterial and/or the IOL manufacturing techniques, it is highly relevant to consider the above-mentioned ranges, including such practical uncertainties.

[017] Another advantage of the present invention is that these relationships between the EDOF, the optical power of the IOL and the parameters of the equations make the IOL of different optical powers easier to design with a view to manufacturing by means of current technologies, since it can be configured by using said equations as well as the relationships Kst (Rst) and Knd (Rnd). In general, it can be highlighted that these new relationships expressing the conic constant of the anterior and posterior optical surfaces of the IOL according to the invention as a function of the radius of curvature of this surface advantageously open up technical perspectives in the design and/or manufacturing of IOLs, in particular monofocal IOLs comprising an optical surface whose conic constant is expressed as a function of its radius of curvature by means of one of these relationships.

[018] Within the scope of this document, an “optical axis” of an eye preferably consists of a vector crossing the eye from one side to the other, directed by its anterior segment, which successively comprises the cornea, the iris and the lens (claimed natural or intraocular crystalline lens), up to its posterior segment, which in particular comprises the retina. For an IOL according to the invention in an implantation position in an eye, the optical axis of the eye is directed from the anterior surface to the posterior surface and preferably corresponds to the optical axis intrinsically defined with respect to the IOL. In particular, the term optical axis is here and preferably used in this document as the reference axis with respect to the eye and/or the IOL.

[019] In the context of this document, an “anterior” (or respectively, “posterior”) side and/or surface of a part of an eye or of an IOL preferably consists of a side and/or a surface located upstream (or respectively, downstream) of the part of the eye or of the IOL with respect to the vector defined by the optical axis. As an example, in an eye, the iris is located anteriorly with respect to the lens (claimed natural or intraocular crystalline); a posterior surface of the iris is therefore a part of the iris that is closest to this lens. Likewise, when a first part of an eye or of an IOL is anteriorly (or respectively, posteriorly) above a second part of an eye or of an IOL, it is known that this first part is located anteriorly (or respectively, posteriorly) with respect to this second part. Similarly, an optical surface is said to be “anteriorly concave (resp. convex)” when it is seen as concave (resp. convex) when looking at the optical surface in the same direction and in the same sense as the vector defined by the optical axis (i.e., following the propagation of light rays), and an optical surface is said to be “posteriorly concave (resp. convex)” when it is seen as concave (resp. convex) when looking at the optical surface in the same direction and in the opposite sense of the vector defined by the optical axis. The aforementioned notions of anteriority, posteriority or even of an optical axis in relation to parts of an eye and/or an IOL are known to the person skilled in the art.

[020] Within the scope of the present invention, the first and second surfaces are always different. Preferably, in the structure of the entire document, the first surface is the anterior optical surface and the second surface is the posterior optical surface. However, it is possible to invert the IOL surfaces within the scope of the invention while maintaining the main advantageous optical properties detailed here above. For ease of reading, within the scope of this document, the indices st and nd for the parameters of the equations are replaced by the indices ant and post when referring specifically to the parameters of the anterior or posterior optical surface. For example, Rant and Rpost correspond to the radii of curvature of the anterior and posterior optical surfaces respectively (being evaluated at their respective vertices). The indices st and nd are also replaced respectively by the indices ant and post in the structure of this document, when the first and second surfaces are considered to be the anterior and posterior optical surfaces, respectively.

[021] Within the scope of the present invention, as generally known to a skilled person, the “vertex” of an optical surface (e.g., the front optical surface or the back optical surface) is preferably defined as a point of intersection of this optical surface with the optical axis.

[022] Within the scope of this invention, the “radius of curvature” of an aspherical surface (e.g., the anterior optical surfaces or the posterior optical surfaces) evaluated at the vertex of this surface is the distance between said vertex and a center of curvature of the surface at this vertex. The conventional sign for this radius of curvature is preferably defined as being the sign of the component, measured along the optical axis, of the displacement (vector) from said vertex to said center of curvature. Then, the anterior optical surface is anteriorly concave (resp. anteriorly convex) at its vertex if and only its radius of curvature evaluated at its vertex is negative (resp. positive), and the posterior optical surface is posteriorly concave (resp. posteriorly convex) at its vertex if and only its radius of curvature evaluated at its vertex is positive (resp. negative). In particular, for the IOL according to the present invention, since Rnd < 0, the second surface of the IOL is posteriorly convex and anteriorly concave at and around its apex.

[023] According to the terminology of a skilled person, the IOL according to the invention is said to be “biconvex” if Rant > 0 and Rpost < 0, i.e. if and only if the anterior optic surface is anteriorly convex and the posterior optic surface is posteriorly convex. According to the terminology of a skilled person, the IOL according to the invention is said to be “concavo-convex” if Rant < 0 and Rpost < 0, i.e. if the anterior optic surface is anteriorly concave and the posterior optic surface is posteriorly convex. These terminologies of a skilled person relate to the external appearance of the IOL, the anterior optic surface being seen anteriorly and the posterior optic surface being seen posteriorly.

[024] Within the scope of the present invention, a portion of an IOL is said to extend “radially outward” when it extends, preferably, according to vectors perpendicular to the optic axis, directed from a point in common with the optic axis to points on a circle centered on this common point. Similarly, a portion of an IOL is said to extend “circumferentially” when it extends, preferably, along at least one arc of a circle in a plane perpendicular to the optic axis and centered on a point of intersection of the plane and the optic axis.

[025] It is known to the person skilled in the art that the adjective “distal” refers to a part of a portion of a body that is further away from some reference organ or body trunk, and that the adjective “proximal” refers to the other portion of a part of a body that is closer to some reference organ or body trunk. Within the scope of this document, these two definitions will preferably apply to parts of an eye and/or parts of an IOL according to the invention with respect to a distance from the reference optical axis.

[026] Within the scope of this invention, the term "intermediate distances" preferably refers to distances (around and/or approximately at and/or) at arm's length, such as working on a computer or looking at a car speedometer. More preferably, this term refers to distances between 0.2 and 1.6 meters, most preferably between 0.4 and 1.0 meters.

[027] Within the scope of this invention, some usual mathematical expressions are recalled as meaning: • “< 0” means “negative”, i.e. strictly less than 0; • “> 0” means “positive”, i.e. strictly greater than 0; • “≤ 0” means “non-positive”, i.e. less than or equal to 0; • “≥ 0” means “non-negative”, i.e. greater than or equal to 0; • “ϵ” means “belongs to”; refers to the set of real numbers; refers to the set of non-zero real numbers; • for such that refers to the closed interval of numbers between y and δ, including those. In addition, it is also well known from Einstein's summation convention that: the index " 𝑖 " being here an integer greater than or equal to 2

[028] In the context of this document, the "Gaussian error function" denoted by erf refers to the well-known special invertible integer function of sigmoidal form defined (in particular) on the real numbers by

[029] Within the scope of this invention, the terms "regular" for a function or surface preferably refer to a function or surface that is at least differentiable (or smooth). Within the scope of this invention, the terms "as a function of", "depends on", and similar terms, should not be construed restrictively as a limited dependence on the specified parameters, unless such a restriction is explicitly written.

[030] Within the scope of this document, the use of the indefinite article “a”, “an” or the definite article “the” to introduce an element does not exclude the presence of a plurality of these elements. In this document, the terms “first”, “second”, “third” and similar are used exclusively to differentiate elements and do not imply any order in these elements.

[031] Within the scope of this document, the use of the verbs “compreender”, “incluir”, “envolvir” or any other variant, as well as their conjugal forms, cannot in any way exclude the presence of elements other than those mentioned.

[032] According to a preferred embodiment of the invention, the IOL has an optical power comprised between 10D and 35D. Optionally, it differs from 13.5 and/or 14D.

[033] For the purposes of this document, an “optical power” of an IOL is preferably an average optical power measured without correction within a (reading) window centered on the optical axis with a diameter of 3 mm.

[034] According to a preferred embodiment of the invention, the constant real numbers involved in defining the relations Kst (Rst) and Knd (Rnd) are in the following restricted value ranges: aϵ [0.060; 0.075] and/or bϵ [-0.5; -0.2] and/or cϵ [-12; -10] and/or Aϵ [-40.1; -39.9] and/or Bϵ [0.080; 0.095] and/or Cϵ [-2.35; -2.05] and/or Dϵ [0.9; 1.1] and/or fϵ [0.085; 0.105] and/or gϵ [1.05; 1.40] and/or cϵ [3; 6].

[035] These ranges may be considered independently or in combination. For example, a first part of these constant real numbers may be considered in the wider ranges of paragraph [0008], and a second part of these constant real numbers may be considered in these restricted ranges. Optionally, these restricted ranges are considered in combination, all “and/or” terms preferably being “and”. Alternatively, these constant real numbers are in other ranges of values smaller than the ranges of paragraph [0008], such that: a ϵ [0.055; 0.070] and/or b ϵ [-0.7; -0.2] and/or c ϵ [-15; -5] and/or A ϵ [-40.5; -39.5] and/or B ϵ [0.08; 0.10] and/or C ϵ [-2.4; -2.2] and/or D ϵ [0.85; 1.15] and/or f ϵ [0.09; 0.11] and/or g ϵ [1.20; 1.45] and/or h ϵ [3; 7]

[036] These intervals may be considered independently or in combination. For example, a first part of these constant real numbers may be considered in the wider intervals of paragraph [0008], a second part of these constant real numbers may be considered in the restricted intervals mentioned above, and a third part of these constant real numbers may be considered in these other smaller intervals. Optionally, these other smaller intervals are considered in combination, all the terms “and/or” being preferably “and”. These constant real numbers are in intervals of even smaller values such that: a ϵ [0.060; 0.065] and/or b ϵ [-0.5; -0.3] and/or c ϵ [-12; -10] and/or A ϵ [-40.1; -39.9] and/or B ϵ [0.090; 0.095] and/or C ϵ [-2.35; -2.25] and/or D ϵ [0.9; 1.1] and/or f ϵ [0.095; 0.105] and/or g ϵ [1.25; 1.40] and/or h ϵ [4; 6]

[037] These ranges may be considered independently or in combination. For example, a first part of these constant real numbers may be considered in the wider ranges of paragraph [0008], a second part of these constant real numbers may be considered in the restricted ranges mentioned above, a third part of these constant real numbers may be considered in the other smaller ranges mentioned above, and a fourth part of these constant real numbers may be considered in these even smaller ranges. Quite optionally, these ranges are considered in combination, all “and/or” terms preferably being “and”. As detailed above, the choice of the ranges corresponds to uncertainties, for example in the choice of the raw biomaterial and/or manufacturing techniques of the intraocular lens, which may induce small variations in the choice of the radii of curvature or conic constants to optimize both EDOF and MTF of the IOL at a given IOL optical power.

[038] The exact values for each of these constant real numbers may optionally be given as: a = 0.0621 and/or b = -0.396 and/or c = -11.035 and/or A = -40 and/or B = 0.092 and/or or C = -2.29 and/or D = 1 and/or / = 0.0989 and/or g = 1.277 and/or h = 4.663.

[039] Each of these values can be considered alone or in combination with one or more other values, all the terms “and/or” being preferably “and”. The above-mentioned ranges for the value of the constant real numbers are around these specific values. It should be emphasized that these values can be obtained by interpolation and/or approximation curves of certain real values chosen for the radius of curvature and the conic constant of the aspheric equations defining the anterior and posterior optical surfaces. In particular, although such a choice of exact values provides an IOL according to the invention, variations around these exact values remain entirely within the scope of the invention. This is further commented on in the detailed description in view of figures 5A-C, introduced below. This is why it makes sense to consider “envelopes” as a margin of uncertainty around the graphs of the two relations Kst (Rst) and Knd (Rnd) defined by this choice of exact values. According to the invention, these envelopes are envisaged in the form of the intervals mentioned above, but other types of envelopes may be defined. In particular, according to an independent preferred embodiment of the invention: (relations annotated (*)) where, for each je (1, 2, 3), pj are numbers, pj > 10 and, optionally, pj = 10, more optionally, pj = 20, more optionally pj = 50. It will be understood by one skilled in the art that these relations express that the real conic constants of the first and second surfaces, respectively, are “close enough” to the conic constants defined by the relations Kst (Rst) and Knd (Rnd) taking into account all the exact values mentioned above. By “close enough” it should be understood that the associated relative deviations are limited by 1/pj in absolute value. The deviations 1/pj can also perform an evaluation of said interpolation and/or approximation by the two relations Kst (Rst) and Knd (Rnd) defined by the choice of exact values, and can then vary according to the latter. As a non-limiting illustrative example, for the exact values mentioned above, p1 = 10, p2 = 15, p3 = 20 may be considered. These deviations additionally define another type of such envelopes combined with the intervals mentioned above. Alternatively, these envelopes may be considered in isolation, in place of the intervals of paragraph [0008] in which the constant real numbers are included, so as to define an alternative invention within the same framework as the present invention. In this case, the relations (*) may be generalized by: where a, b, c, AB, C, D, f, g, h may be any values explicitly disclosed in this document, in particular in paragraphs [0034]-[0036] and [0070]-[0073], and where, for each j and {1, 2, 3}, pj are numbers greater than or equal to 10 and, optionally, pj = 10, plus optionally, pj = 20, plus optionally pj = 50.

[040] Other exact values may be considered more faithful with respect to the specific choice of radius of curvature and conic constant for the anterior and posterior optical surfaces. As an example, for an IOL whose optical power is less than or equal to 27.5 D, the real constant numbers f, g, and h are most preferably given exactly by: f = 0.1032 and/or g = 1.372 and/or h = 5.1353. These values are most preferably considered in combination, the terms “and/or” being preferably “and”. This is specifically discussed below with reference to Figure 5C. As another example, the above-mentioned values B = 0.092 and/or C = -2.29 may alternatively be replaced by B = 0.081 and/or C = -2.095 (or, optionally, also by the values B = 0.085 and/or C = -2.168), providing other approximation curves of particular values chosen for the radius of curvature and the conic constant of the aspheric equations defining the anterior and posterior optical surfaces, to obtain, smoothly with respect to at least a main selection of optical powers of the IOL, a desired optimized EDOF and MTF. In particular, according to a corresponding independent embodiment of the invention, the relations and/or and/or if the optical power of the IOL is strictly greater than 27.5; and/or if the optical power of the IOL is strictly greater than 27.5; and/or if the optical power of the IOL is less than or equal to 27.5 D; where, for each j ϵ {1.2, 3.4), , preferably, , are preferably satisfied. All or part of these latter relations may be considered in combination and/or replacement of all or part of the associated relations (*).

[041] According to a first preferred embodiment of the invention, the IOL has an optical power strictly less than 14D, and Rst < 0. In particular, the first surface is then anteriorly concave and posteriorly convex at its apex. According to a second preferred embodiment of the invention, the IOL has an optical power greater than or equal to 14D and Rst > 0. In particular, the first surface is then anteriorly convex and posteriorly concave at its apex. In other words, combining these two preferred embodiments, preferably, the optical power of the IOL is strictly less than 14D if and only if Rst < 0.

[042] Preferably, according to any of these preferred embodiments, the radius of curvature Rst of the first surface depends continuously and regularly on the optical power (in the aforementioned definition range of the optical power considered). Preferably and independently of these preferred embodiments, the radius of curvature Rnd of the second surface depends continuously and regularly on the optical power of the intraocular lens. The continuity and regularity of the variation of the radius of curvature of each of the optical surfaces is a preferred natural option for implementing the desired technical effect of the invention. It also implies a regularity of the variation of the conic constant of each of the optical surfaces, since it is expressed regularly as a function of the associated radius of curvature.

[043] Within the scope of the invention, at least one of the asphericity coefficients of at least one of the anterior and posterior optical surface equations (preferably of both optical surface equations) is non-zero. The IOL optic is provided with an aspherical design allowing an extension of the depth of focus thanks to the contribution of these non-zero asphericity coefficients. According to a preferred embodiment of the invention, the asphericity coefficients of order less than or equal to 10 of the anterior and/or posterior optical surfaces are non-zero. The contribution of all these non-zero asphericity coefficients allows to obtain a very high EDOF performance. In particular, it induced a complete aspheric geometry for the anterior and/or posterior optical surfaces comprising a turning point ring of curvatures (i.e. inflection points) at the mean optical diameter. Preferably, the asphericity coefficients are decreasing in absolute value with respect to their order and/or limited in absolute value by 0.1. Most preferably, they follow the relationships: and/or, preferably, and,

[044] These asphericity coefficients correspond to the lateral perturbation of the general shape of the aspheric surfaces around their vertex. Preferably, the asphericity coefficients of order strictly higher than 10 of the anterior and/or posterior optical surfaces are negligible and/or approximated by and/or equal to zero. In other words, they are substantially equal to zero and preferably equal to zero.

[045] Preferably, the asphericity coefficients of the anterior and/or posterior optical surfaces depend continuously and regularly on an optical power of the intraocular lens. In particular, preferably, all the parameters (the radius of curvature, the conic constant and the asphericity coefficients) defining the anterior and/or posterior optical surfaces depend regularly on the optical power of the IOL.

[046] As specific embodiments of the invention, there are now provided exact equations for the anterior and posterior (aspheric) optical surfaces of an IOL of a selection of predetermined optical powers: • according to a first specific embodiment of the invention, an IOL optical power is 15 D and • according to a second specific embodiment of the invention, an IOL optical power is 20 D and • according to a third specific embodiment of the invention, an IOL optical power is 25 D and

[047] For each of the optical powers mentioned above, these explicit data are preferably considered in combination. Within the scope of this document, any explicit data mentioned as geometric parameters for the anterior and posterior optical surfaces are provided for the IOL in the dry state. These values may be observed with respect to an uncertainty of at most 10% in absolute value, more preferably 5%, given that factor such as the raw biomaterial constituting the IOL and/or manufacturing techniques and conditions may impact them. As an example, the radii of curvature of these first, second and third specific embodiments may be replaced respectively by other preferred values such as: Rant = 86.11 mm, and/or Rpost = - 14.00 mm; and/or Rant = 22.01 mm, and/or Rpost = - 15.42 mm; and/or • Rant = 11.61 mm, and/or Rpost = - 19.88 mm; without changing the other equation parameter values.

[048] The apparent geometry of the anterior and posterior optical surfaces is now described. Preferably, according to embodiments of the invention for which the optical power of the IOL is greater than or equal to 14D: an elevation map evaluated at a radial coordinate on the anterior optical surface, considering a plane perpendicular to the optical axis as the zero elevation reference plane and considering the optical axis as the reference axis for an elevation evaluation: presents a local minimum at the vertex of the anterior optical surface, is increased from the vertex of the anterior optical surface to an edge of that surface; • an elevation map evaluated at a radial coordinate on the posterior optical surface, considering the plane perpendicular to the optical axis as the zero elevation reference plane and considering the optical axis as the reference axis for an elevation evaluation, presents: • a local maximum at the vertex of the posterior optical surface, • a peripheral local minimum at a positive distance from an edge of the posterior optical surface, • an inflection point situated between said local maximum and said peripheral local minimum and: • is decreasing from the vertex of the posterior optical surface to the peripheral local minimum, • is increasing from the peripheral local minimum to an edge of this posterior optical surface.  •

[049] Preferably, according to embodiments of the invention for which the optical power of the IOL is strictly greater than 12D and strictly less than 14D: • an elevation map evaluated in a radial coordinate on the anterior optic surface, considering a plane perpendicular to the optic axis as zero elevation reference plane and considering the optic plane as reference axis for an elevation evaluation, presents: • a local maximum at the vertex of the anterior optic surface, • a peripheral local minimum at a positive distance from an edge of the anterior optic surface, • an inflection point situated between said local maximum and said peripheral local minimum and: • is decreasing from the vertex of the anterior optic surface to said peripheral local minimum, • is increasing from said peripheral local minimum to an edge of the anterior optic surface. • an elevation map evaluated at a radial coordinate on the posterior optical surface, considering the plane perpendicular to the optical axis as the zero elevation reference plane and considering the optical plane as the reference axis for an elevation evaluation, presents: • a local maximum at the vertex of the posterior optical surface, • a peripheral local minimum at a positive distance from an edge of the posterior optical surface, • an inflection point situated between said local maximum and said peripheral local minimum and: • is decreasing from the vertex of the posterior optical surface to the peripheral local minimum, • is increasing from the peripheral local minimum to an edge of this posterior optical surface.

[050] In particular, in this case, both the elevation maps of the anterior and posterior optical surfaces have similar profiles.

[051] Preferably, according to embodiments of the invention for which the optical power of the IOL is less than or equal to 12D: • an elevation map evaluated in a radial coordinate on the anterior optic surface, considering a plane perpendicular to the optic axis as zero elevation reference plane and considering the optic plane as reference axis for an elevation evaluation: • presents a local maximum at the vertex of the anterior optic surface, • is decreasing from the vertex of the anterior optic surface to an edge of this surface; • an elevation map evaluated in a radial coordinate on the posterior optic surface, considering the plane perpendicular to the optic axis as zero elevation reference plane and considering the optic plane as reference axis for an elevation evaluation: • presents a local maximum at the vertex of the posterior optic surface, • is decreasing from the vertex of the posterior optic surface to an edge of this surface.

[052] In particular, in this case, both the elevation maps of the anterior and posterior optical surfaces have similar profiles.

[053] These geometric properties of the anterior and posterior optical surfaces described in the previous three paragraphs are due to the asphericity of these surfaces governed by the equation (aspheric) for these surfaces, in particular for the preferred embodiments of the invention for which the asphericity coefficients of order less than or equal to 10 of the anterior and posterior optical surfaces are non-zero. These geometric properties give the IOL a high optical quality (described by a high MTF) and result in the EDOF depending only marginally on the optical power, the aperture and the spherical aberrations of the cornea.

[054] According to a preferred embodiment of the invention, the anterior and posterior optical surfaces are cut from a hydrophobic raw biomaterial of refractive index between 1.40 and 1.65. Preferably, this raw biomaterial is free of glistening. “Glistenings”, also called fluid-filled microvacuoles, form within certain IOL materials and can develop after IOL implantation in various shapes, sizes and densities. Some IOLs on the market develop microvacuoles after implantation that can impact the quality of vision. Preferably, the raw biomaterial contains a UV blocker (in the range strictly below 400 nm) and/or a yellow chromophore to reduce the transmittance of potentially phototoxic light in the violet-blue range (between 400 and 500 nm). Preferably, the refractive index is equal to 1.52.

[055] According to a preferred embodiment of the invention, the anterior and posterior optical surfaces are separated by an internal body of predetermined central thickness, measured along the optical axis, and comprising between 0.30 and 0.70 mm. Advantageously, this central thickness makes it possible to fix flexible haptic devices on a periphery of an optic consisting of the internal body and the anterior and posterior optical surfaces.

[056] According to a preferred embodiment of the invention, both the anterior and posterior optical surfaces have a diameter, measured perpendicularly to the optical axis, comprised between 4.70 and 5.00 mm, preferably between 4.80 and 4.95 mm, more preferably between 4.85 and 4.91 mm. This diameter preferably refers to the so-called clear optic. It is targeted around the value of 5 mm during the manufacture of the IOL optic (or central optic part). However, as described below, the junction between the IOL haptics and its optic must be optimized, which generates a potential reduction of the clear optic which is more generally around 4.85 mm after the manufacture of the IOL. In particular, the geometry of the anterior and posterior optical surfaces ends at the edges of the IOL optic defined by its junction with the haptics, referring to the “edge of these optical surfaces”.

[057] According to one embodiment of the invention, a combined optical refraction of the anterior and posterior optical surfaces with a corneal model (anteriorly external to the IOL) provides a continuous and regular map of optical power comprising a central global maximum (diopter power) (which may be associated with vision at closer distances, e.g., intermediate distance) along the optical axis surrounded by a scattered central region of lower optical power (for vision at longer distances, e.g., long distances). The term “lower” should be interpreted relative to the central global maximum (peak power). The “corneal model” is, for example, an “average corneal model”, that is, a corneal model providing a spherical aberration of the cornea of 0.28 μm (± 0.2 μm) at a 5.15 mm aperture, in the IOL plane and for an average human eye. This average corneal model is completely standard and well known to a skilled artisan. It is indicated by IS02. Preferably, the central region is “smeared” in the sense that it is spread over about half the diameter of the anterior and posterior optical surfaces. Preferably, this central region is surrounded by a first ring of map points that are inflection points or local minima of optical power. Optionally, the map further comprises a second ring of points that are local maxima of optical power, said second ring surrounding said first ring. This regular map is shown in Figures 10A-B, below. This naturally results in an EDOF provided by the IOL. It is advantageous to note that the optical power map is regular. In particular, the IOL provides the patient with high optical quality for several distances simultaneously, without abrupt changes in optical power across the optic likely to cause side effects such as stray light, halos or glare.

[058] According to a highly preferred embodiment of the invention, the intraocular lens according to the invention comprises: • a central optical portion (or optic) whose: • an anterior surface is the anterior optical surface, and • a posterior surface is the posterior optical surface; - a plurality of flexible haptics connected to the central optical portion and configured to stabilize the intraocular lens in a capsular bag of an aphakic eye.

[059] The term “central” refers to the extent of the optic around and/or centered on the optic axis. The term “central” preferably does not refer to a portion of the IOL optic and preferably consists of the entire optical portion of the IOL optic. Preferably, the first surface is the anterior optic surface.

[060] Preferably, the IOL comprises four closed flexible haptics, each forming a loop based on the central optic portion. Preferably, a haptic thickness measured along the optical axis is between 0.20 and 0.50 mm, more preferably equal to 0.34 mm. Preferably, the haptics are made of the same hydrophobic bulk biomaterial as the central optic portion. Preferably, the haptics are cut by a milling machine. Preferably, the plurality of flexible haptics consists of four closed flexible haptics, each forming a loop based on the central optic portion. These four closed flexible haptics are preferably arranged symmetrically around the central optic portion, along the diagonals of a rectangle, providing four points of contact, allowing a maximized contact angle between the haptics and the surrounding ocular tissues when the IOL is in normal use in an aphakic eye. As a consequence, controlled compensation of variations in the capsular bag size is advantageously possible through radial deformation of the haptics.

[061] Preferably, a distance, measured along the optical axis, between a flexible (anterior) haptic apex and a principal (or median) optical plane of the central optic portion depends continuously and regularly on an optical power of the intraocular lens. It is advantageous and important to take this distance into account and to calculate it as a function of the optical power of the IOL. Indeed, as discussed above, the aspherical geometry of the anterior and posterior optical surfaces varies regularly depending on the optical power of the IOL. This implies that the principal optical plane is not constant and changes position as a function of the optical power of the IOL. It is therefore also of great importance to adapt the connection between the haptic and the central optic portion in a position parallel to the optical axis (thus creating an offset) and at an angle between the principal optical plane and a proximal part of the haptics at their connection with the central optic portion. This is as important as correctly adapting the legs of the spectacles to a body. Advantageously, the present invention proposes to take this into account through the aforementioned distance. Furthermore, the haptic geometry and distance are preferably also chosen to ensure the stability of the IOL parallel to the optical axis when implanted in a capsular bag of an aphakic eye. It is preferably limited by 0.45 mm and is continuously increasing to increase the optical powers. This distance as a function of the optical power of the IOL is further commented in the detailed description in view of figures 12A-B, presented below.

[062] In other words, according to a preferred embodiment of said very preferred embodiment of the invention, a distance, measured along the optical axis, between a flexible (anterior) haptic vertex and a principal (or median) optical plane of the center optical part corresponds to an image of an optical power of the intraocular lens by a continuous regular function, continuously increasing for increasing optical powers, and delimited by 0.45 mm, such that said principal optical plane is (longitudinally) stably parallel to the optical axis when the intraocular lens is implanted in a capsular bag of an aphakic eye. This distance and the related advantages form part of the invention. In particular, the present invention also provides an intraocular lens (IOL) comprising: • a central optical part (or optic) comprising: • an aspherical anterior optical surface, and • an aspherical posterior optical surface; • a plurality of flexible haptics connected to the central optical part; wherein a distance, measured along the optical axis, between a flexible haptic vertex and a principal optical plane of the central optic portion depends continuously and regularly on an optical power of the IOL. Any of the embodiments and/or advantages of the IOL of paragraph [0008] described above may be extended to this other IOL according to the invention.

[063] According to a preferred embodiment of the present invention, the IOL is shape invariant under a 180° rotation around the optical axis. It is then easier to insert and manipulate the IOL in an eye, since its shape, and in particular the shape of the haptics, naturally follows the potential rotational position adjustment at the time of surgery.

[064] The present invention also provides a method of manufacturing an intraocular lens according to the invention comprising the steps: (a) modeling an optic with a profile pattern of aspherical optical surfaces; (b) calculating a refractive efficiency distribution for light propagation through the modeled optic; (c) selecting profile parameters of aspherical optical surfaces according to the calculated refractive efficiency distribution so as to achieve the desired refractive efficiencies; and (d) forming the modeled optic with the selected parameters from a raw biomaterial.

[065] The manufacturing method according to the invention easily provides IOLs with optimized parameters for improved quality vision at long and intermediate distances. Preferably, the aspherical optical surface profile parameters selected in step (c) depend continuously and regularly on an optical power of the intraocular lens. For each surface, these parameters preferably comprise (more preferably consist of) the radius of curvature and the conic constant evaluated at the apex of the surface, and the asphericity coefficient. The embodiments and advantages of the IOL according to the invention are transposed with the appropriate necessary modifications to the method according to the invention. In particular, preferably, step (c) is carried out with a view to a parameter table comprising optimized aspherical surface profile parameters for each desired IOL optical power associated with the desired refractive efficiencies, these parameters being very easily determined in view of the predetermined relations Kst (Rst) and Knd (Rnd). Preferably and specifically, a conic constant Kst of a (a) first surface among these aspherical optical surfaces, evaluated at its vertex, is selected in step (c) as a function of a radius of curvature Rst of the first surface evaluated at this vertex by the relation where erf denotes a Gaussian error function, and where a, b, c, A, B, C, D are constant real numbers; and a conic constant Knd of a (a) second surface between these aspherical optical surfaces, evaluated at its vertex, is selected in step (c) as a function of a radius of curvature Rnd of the second surface evaluated at this vertex by the relation wherein f, g, h are constant real numbers. All embodiments and advantages of the IOL according to the invention with respect to these relations and/or the constant real numbers a, b, c, A, B, C, D, f, g, h apply with the necessary changes to this preferred embodiment of the manufacturing method according to the invention. As another independent preferred embodiment of this manufacturing method for an IOL as described in paragraph [0053], this method comprises the step of selecting a distance, measured along the optical axis, between a flexible haptic apex and a principal optical plane of the optical part, as a function of an optical power of the intraocular lens as an image of the latter by a continuous and regular function, continuously increasing for increasing optical powers, and delimited by 0.45 mm, so as to achieve the desired longitudinal stability of the principal optical plane parallel to the optical axis when the intraocular lens is implanted in a capsular bag of an aphakic eye.

Brief description of the figures

[066] Other features and advantages of the present invention will become apparent upon reading the detailed description below, for the understanding of which reference is made to the attached figures, in which: - figure 1 illustrates a simplified planar representation of an anterior surface of an IOL, according to a preferred embodiment of the invention; - figure 2 illustrates a simplified comparison of the focusing of light by a single-vision lens with the focusing of light by the IOL, according to the invention; - figures 3A-D illustrate cross-sectional views of the anterior and posterior optical surfaces of an IOL, according to preferred embodiments of the invention; - figure 4 illustrates a schematic view of an aspherical surface; - figure 5A illustrates a graphical representation of the conic constant of the first surface, according to preferred embodiments of the invention, defined as a function of its radius of curvature when this is positive; - figure 5B illustrates a graphical representation of the conic constant of the first surface, according to preferred embodiments of the invention, defined as a function of its radius of curvature when this is negative; - figure 5C illustrates a graphical representation of the conic constant of the second surface, according to preferred embodiments of the invention, defined as a function of its radius of curvature; - figures 6A-C illustrate experimental (on an optical bench) and interpolated graphical representations of the EDOF, a) spherical aberration and the MTF of IOLs, according to preferred embodiments of the invention, as a function of their nominal optical power; - figure 7 illustrates graphical representations of the EDOF of a medium dioptric power IOL according to a preferred embodiment of the invention, together with an aperture, for three different models of spherical aberrations of the cornea; - figure 8 illustrates graphical representations of the MTF of a mean dioptric power IOL according to a preferred embodiment of the invention as a function of an aperture, for three different models of corneal spherical aberrations; - figures 9A-C each illustrate graphical representations of spherical aberrations (fourth order) as a function of an aperture, for a corneal model, for an IOL according to a preferred embodiment of the invention and for their combination; - figures 10A-B illustrate optical power maps obtained by combined optical refraction of the anterior and posterior optical surfaces according to embodiments of the invention with a corneal model; - figures 11-A-C illustrate simplified sectional representations of IOLs according to preferred embodiments of the invention; - figure 12A illustrates a connection between a haptic and a central optic of an IOL according to an embodiment of the invention; - figure 12B illustrates a graphical representation of the distance measured along the optical axis between a flexible haptic vertex and a principal optical plane of a central optical portion of the IOL according to preferred embodiments of the invention, as a function of the optical power of the IOL; - figure 13 illustrates graphical representations of measurements on an optical bench of a direct-focus MTF of an IOL according to a preferred embodiment of the invention and a standard monofocal IOL.

[067] The drawings in the figures are not to scale. In general, similar elements are assigned by similar references in the figures. Within the scope of this document, identical or analogous elements may have the same references. Furthermore, the presence of reference numerals in the drawings cannot be considered limiting, which includes when such numerals are indicated in the claims.

[068] However, figures 5A-C, 6A-C, 7, 8 and 9A-C which illustrate the graphical representations are considered as faithfully reproducing the measurement data and/or interpolation (or approximation) curves, in such a way that these figures reveal each value or ranges of values derivable from these graphical representations.

Detailed Description of Specific Embodiments of the Invention

[069] This part presents a detailed description of specific preferred embodiments of the invention. These are described with references to figures, but the invention is not limited by these references. In particular, the drawings or figures described below are only schematic and are not limiting in any way. The present detailed description refers only to the preferred embodiment of the invention for which the first and second surfaces are respectively the anterior and posterior optical surfaces. Then, for ease of reading, the index st and nd are replaced respectively by the index ant and post. Furthermore, the reference numeral 2 (resp. 3) is used in the detailed description and in the figures to designate the anterior (resp. posterior) optical surface (which then corresponds to the first (resp. second) surface).

[070] As illustrated in the following figures, the present invention provides a refractive intraocular lens (IOL) 1 with extended depth of focus (EDOF) comprising a single aspherical anterior optical surface 2 and a single aspherical posterior optical surface 3 extending radially outwardly relative to an optical axis Z and rotationally symmetrically about this optical axis Z. This optical axis Z is directed from the anterior optical surface 2 to the posterior optical surface 3, or in other words, from a global anterior surface of the IOL 1 to a global posterior surface of the IOL 1. Reference numerals 21 and 31 indicate the apex of the optical surfaces 2 and 3, respectively.

[071] Each of the optical surfaces 2 and 3 are defined by a single equation of the form as described in the disclosure of the invention. For an arbitrary aspherical surface (for example, the anterior optical surface 2 or posterior optical surface 3) indicated more generally by S, which comprises a vertex indicated more generally by V, figure 4 illustrates how such an aspherical surface is defined from an equation of that form. This figure illustrates an osculating circle of a section of the surface S (thus defining a curve) comprising the optical axis Z, at the vertex V. In particular, this circle approximates the section of the surface S around the vertex V. The center of curvature C of this circle lies on the optical axis Z. This circle has a radius corresponding to the so-called radius of curvature R of the section of the surface S evaluated at the vertex V. In the embodiment illustrated in figure 4, the conventional sign for this radius of curvature R is positive since the component, measured along the optical axis Z, of the displacement (vector) from the vertex V to the center of curvature C is positive. Indeed, this displacement (vector) is directed both in the same direction and in the direction of the optical axis Z. It is known to a skilled person that a conic constant K of the cross-section of the surface S, evaluated at the vertex V, defines a global deviation (for example a hyperbolic, parabolic or elliptical profile) of the cross-section of the surface S from the osculating circle. These notions of radius of curvature R and conic constant k extend directly to the surface S when evaluated at the vertex V since an aspherical surface is rotationally symmetric about the optical axis Z, at least locally in a neighborhood of the vertex V. In particular, the radius of curvature R then corresponds to a radius of an osculating sphere evaluated at the vertex V. For each i > 2, α2i is a real coefficient (called coefficient of asphericity) of order 2i of the surface S. These coefficients correspond substantially to (lateral) variations of the surface as defined from the radius of curvature R and the conic constant K. Depending on all these parameters R, K, α4 ae, ae, ... the equation defines the surface S by expressing a given z(r) as a function of a radial variable r, both illustrated in figure 4. The given z(r) corresponds to the component, measured along the optical axis Z, of a displacement (vector) from the vertex V to any point on the surface a a radius r from the optical axis Z. Equivalently, the data z(r) correspond to the Z component of a vector where P is any point on the surface S at a radius r from the optical axis Z. Considering local polar coordinates (r, z) on the surface S, also equivalently, the data z(r) corresponds to the coordinate along the optical axis Z of a point on the surface S whose radial coordinate is r (counted from the vertex V). The vertex V corresponds, in general, to the point (r = 0; z(r) = 0). In the embodiment shown in figure 4, the data z(r) is positive because this displacement (vector) is directed in the same direction and sense as the optical axis Z. In this case, the surface S is anteriorly convex (and posteriorly concave). Figure 4 has been described as a very general illustration of the above equation for aspherical surfaces. It is not limitative to the exact shape of the claimed anterior 2 and posterior 3 optical surfaces, their concavity or convexity, the sign of their radius of curvature Rant and Rpost, or the sign of their data z(r).

[072] As illustrated in figure 1, the IOL 1 according to the invention comprises a central optical portion 4 (or optic) whose anterior surface consists of the anterior optical surface 2, and whose posterior surface consists of the posterior optical surface 3. The IOL 1 also comprises four closed flexible haptics 5 (in the shape of a mouse ear), each forming a handle based on and connected to the central optical portion 4. As explained in the disclosure of the invention, these haptics 5 are specifically arranged to stabilize the IOL 1 in a capsular bag of an aphakic eye when the IOL 1 is in an implanted state. A circular extension 52 of the haptics 5 extends around the central optical portion 4 to fix the latter. A diameter d of the central optical portion 4, measured perpendicularly to the optical axis Z, is comprised between 4.70 and 5.00 mm, preferably it is 4.85 mm. A diameter d' of the central optical portion 4 surrounded by the extension 52, measured perpendicularly to the optical axis Z, is comprised between 5.65 and 6.10 mm. Preferably, the diameter d' is comprised between 5.90 and 6.10 mm, more preferably it is 6.00 mm, if the optical power of the IOL 1 is strictly less than 25 D. Preferably, the diameter d' is comprised between 5.65 and 5.85 mm, more preferably it is 5.75 mm, if the optical power of the IOL 1 is greater than or equal to 25 D. A diameter d” of the IOL 1 (which then comprises the central optical portion 4, the extension 52 and the haptics 5), measured perpendicularly to the optical axis Z, is comprised between 10.55 and 11.20 mm. Preferably, the diameter d” is between 10.80 and 11.20 mm, more preferably it is 11.00 mm, if the optical power of the IOL 1 is strictly less than 25 D. Preferably, the diameter d” is between 10.55 and 10.95 mm, more preferably it is 10.75 mm, if the optical power of the IOL 1 is greater than or equal to 25 D. Advantageously, the design of the haptics 5 is adapted according to the optical power of the IOL. The flexibility of the haptics 5 deduced from their low thickness (between 0.30 and 0.40 mm, measured along the optical axis Z) and their position around the central optical portion 4, as illustrated in figure 1, allows them to deform radially to compensate for variations in the size of the capsular bag when the IOL 1 is implanted.

[073] The advantageous aspherical geometry of the anterior 2 and posterior 3 optical surfaces of the IOL 1 according to the invention provides an EDOF. As illustrated in Figure 2, the IOL 1 focuses light into an “extended” focal point, whereas a standard monofocal T IOL focuses light into a single focal point FP. The monofocal T IOL provides quality vision for selected long distances around the focal point FP, but not for near or intermediate distances of this focal point FP. The IOL 1 according to the invention advantageously allows an (asymmetric) extension of this focal point FP to closer distances in order to create an EDOF that provides overall better quality vision for a wide range of long and intermediate distances.

[074] To obtain this EDOF, the IOL 1 according to the invention comprises an anterior optical surface 2 and a posterior optical surface 3, both aspherical. Figures 3A-D illustrate sectional profiles (comprising the optical axis Z) of the anterior optical surfaces 2 and posterior optical surfaces 3 for four different optical powers: 10D (in Figure 3A), 15D (in Figure 3B), 20D (in Figure 3C) and 35D (in Figure 3D). For each of these figures, axes 81 and 82 define a Cartesian coordinate system for defining the position of points of the anterior optical surfaces 2 and posterior optical surfaces 3 in a plane in which the sectional profiles are illustrated. Each of the axes 81 and 82 is graduated in mm. The axis 81 allows to measure positions along the optical axis Z. The axis 82 allows to measure positions perpendicular to the optical axis Z. The axes 81 and 82 intersect at the vertex 21 of the anterior surface 2. Since the diameter d of the center of the optical part 4, measured perpendicular to the optical axis Z, is between 4.70 and 5.00 mm, it can be seen that the sectional profiles illustrated in figures 3A-D are more worn than the anterior optical surfaces 2 and posterior optical surfaces 3 finally actually drawn and cut for the IOL 1.

[075] The optical surfaces 2, 3 deduced from Figure 3A define a concave and convex IOL profile. The anterior optical surface 2 is concave anteriorly, while the posterior optical surface 3 is convex posteriorly. In particular, both the Kant and Rpost radii of curvature of the anterior optical surfaces 2 and posterior optical surfaces 3 evaluated by the respective vertex 21 and 31 are negative, and both the Kant and Kpost constants of the anterior optical surfaces 2 and posterior optical surfaces 3 evaluated by the respective vertex 21 and 31 are positive. An elevation map evaluated in a radial coordinate on any of the anterior optical surfaces 2 and posterior optical surfaces 3, considering a plane perpendicular to the optical axis Z as a zero elevation plane of the reference and considering the optical axis Z as a reference axis for an elevation evaluation: • presents a local maximum at its vertex 21 or 31, • is decreasing from its vertex 21 or 31 to an edge (at the limit of the finally cut optical surface 2 or 3, whose dimensions are associated with the diameter d) of the optical surface 2 or 3.

[076] The optical surfaces 2, 3 inferred from Figures 3B-D define a biconvex IOL profile. The anterior optical surface 2 is anteriorly convex, while the posterior optical surface 3 is posteriorly convex. The radius of curvature Rant of the anterior optical surface 2 evaluated at its vertex 21 is positive, the radius of curvature Rpost of the posterior optical surface 3 evaluated at its vertex 31 is negative, the conic constant Kant of the anterior optical surface 2 evaluated at its vertex 21 is negative, and the conic constant Kpost of the posterior optical surface 3 evaluated at its vertex 31 is positive. An elevation map evaluated at a radial coordinate on the previous optical surface 2, considering a plane perpendicular to the optical axis Z as a zero elevation reference plane and considering the optical plane Z as a reference axis for an elevation evaluation: • presents a local minimum at its vertex 21, • is increasing from its vertex 21 to an edge (at the limit of the finally cut previous optical surface 2, whose dimensions are associated with the diameter d) of the previous optical surface 2.

[077] An elevation map evaluated at a radial coordinate on the posterior optical surface 3, considering the plane perpendicular to the optical axis Z as the zero elevation reference plane and considering the optical plane Z as the reference axis for an elevation evaluation, presents: • a local maximum at its vertex 31, • a peripheral local minimum 32 at a positive distance from an edge (at the limit of the finally cut posterior optical surface 3, whose dimensions are associated with the diameter d) of the posterior optical surface 3, • an inflection point 33 situated between the local maximum and the peripheral local minimum 32, and: • is decreasing from its vertex 31 to the peripheral local minimum 32, • is increasing from the peripheral local minimum 32 to an edge of the posterior optical surface 3.

[078] Since the elevation map is evaluated in a radial coordinate on the posterior optical surface 3, its reading at points across the posterior optical surface 3 (and not in a radial coordinate) defines a ring of such peripheral local minimum 32 and a ring of inflection points 33 approximately at the mean optical diameter. Such inflection points 33 correspond to turning points of curvature where the posterior optical surface 3 (as illustrated in Figures 3B-D) changes from concave to convex or from convex to concave. More specifically, the posterior optical surface 3 is posteriorly convex around the vertex 31 and posteriorly concave around the ring of peripheral local minimum 32.

[079] Although the anterior optical surfaces 2 and posterior optical surfaces 3 clearly show variation in curvature, it should be noted that both the anterior optical surfaces 2 and posterior optical surfaces 3 are smooth, continuous and regular. They do not show any breaking points or abrupt zonal limitations.

[080] The IOL 1, according to the invention, has an optical power depending on the refractive index associated with a material constituting the anterior 2 and posterior 3 optical surfaces, and on the geometry of these surfaces 2 and 3. The latter is determined (at least around its vertices 21 and 31) by the radii of curvature Rant and Rpost and by the conic constants Kant and Kpost. According to preferred embodiments of the invention, Rant > 0 if and only if the optical power is greater than or equal to 14D, and Rpost < 0 for the entire optical power of the IOL. The radius of curvature Rant depends continuously and regularly on the optical power in each of the intervals ]0D, 13.5D] and [14D, 40D[. The radius of curvature Rpost depends continuously and regularly on the optical power. The invention very advantageously provides new smooth, continuous and regular relations for expressing the conic constants Kant and Kpost as a function of the radii of curvature Rant and Rpost. These are illustrated by graphical representations in figures 5A-C. For each of these figures, the axes 83 and 84 define a Cartesian coordinate system corresponding respectively to a radius of curvature measured in mm and to a conic constant. Figure 5A represents graphical representations of a Kant function (Rant) defining the conic constant Kant as a function of the radius of curvature Rant for the anterior optical surface 2 of an IOL 1 whose optical power is greater than or equal to 14D. Figure 5B represents graphical representations of a Kant function (Rant) defining the conic constant Kant as a function of the radius of curvature Rant for the anterior optical surface 2 of an IOL 1 whose optical power is strictly less than 14D. Figure 5C depicts graphical representations of a Kpost function (Rpost) that defines the conic constant Kpost as a function of the radius of curvature Rpost for the posterior optic surface 3 of an IOL 1. Each of these figures 5A–C represents either a collection (or graph) of points corresponding to measured values of conic constants as a function of radii of curvature, or the graph of an interpolation function and/or very good approximation of this collection of points.

[081] The graph in Figure 5A represents the function which corresponds almost perfectly to the plotted points as can be seen in the graphical representations. This function is completely new and very specific in the technical field of the invention. It defines a continuous and regular sigmoid that can be used to define any appropriate Kant conic constant as a function of the radius of curvature Rant for an anterior optical surface 2 of an IOL 1 whose optical power is greater than or equal to 14D.

[082] The graph in Figure 5B represents the function which corresponds to a perfect interpolation (with correlation coefficient equal to 1) of the plotted points as can be seen in the graphical representations. This function is completely new and very specific in the technical field of the invention. It defines a continuous and regular polynomial that can be used to define any appropriate Kant conic constant as a function of the radius of curvature Rant for an anterior optical surface 2 of an IOL 1 whose optical power is strictly less than 14D.

[083] The graph in Figure 5C represents the function which corresponds to an almost perfect interpolation (with correlation coefficient equal to 0.99) of the plotted points represented (for example) for an optical power between 10D and 27.5D, as can be seen from the graphical representations. This function is completely new and very specific in the technical field of the invention. It defines a continuous and regular polynomial that can be used to define any appropriate conic constant Kpost as a function of the radius of curvature Rpost for a posterior optical surface 3 of an IOL 1.

[084] The invention is not limited to the specific values of the parameters of the above-mentioned Kant (Rant) and Kpost (Rpost) functions. Any sigmoid or similar polynomial functions may be used, the spirit of the invention being in the use of relations of these types to express the conic constant as a function of the radius of curvature of each of the anterior 2 and posterior 3 optical surfaces. Examples of sigmoid or similar polynomial functions are provided in the disclosure of the invention explicitly or in the form of suitable intervals in which the numerical coefficients (A, B, C, D, a, b, c, f, g and h, as indicated herein) of these functions vary. These intervals do not limit the present disclosure. In addition, other polynomial functions of degrees other than two may be used. For example, the Kant (Rant) function represented in figure 5B could be replaced by providing another very good interpolation of the points plotted in Figure 5B. However, the use of polynomials of order two is preferable for computational reasons. The Kant (Rant) function represented in Figure 5B for an anterior optical surface 2 of an IOL 1 whose optical power is strictly less than 14D, can also be considered in the form of a very simple polynomial of order one: by reducing the conic constant for the anterior optical surface of IOL 1 with optical power of 13.5D compared with the previous equations, which can facilitate the manufacturing process of IOL 1. Such an equation well interpolates the pair of values of radii of curvature and conic constants for the anterior optical surfaces of IOL1 with small optical powers (i.e., less than or equal to 13.5D), and is very easy to use for computing reasons.

[085] Figure 6A illustrates a graphical representation of a collection of points with error bars corresponding to the experimental optical bench measurements of the EDOF of IOL 1, read on the 86 axis and measured in diopters (D), as a function of the optical power of the IOL, read on the 85 axis and measured in diopters (D). The EDOF is defined as the power added in diopters from a maximum MTF peak to an MTF value of 0.17 at 50 Lp/mm. The measurements are made for a 3 mm aperture with a corneal model providing a spherical aberration of 0 μm (IS01). This graphical representation is interpolated by a polynomial curve with equation where x is the optical power of the IOL. As can be seen in Figure 6A, the invention provides an IOL 1 whose EDOF depends to a very limited extent on the optical power of the IOL.

[086] Figure 6B illustrates a graphical representation of a collection of points with error bars corresponding to experimental optical bench measurements of a fourth-order longitudinal spherical aberration (LSA) of IOL 1, read on axis 87 and measured in microns (μm), as a function of the optical power of the IOL, read on axis 85 and measured in diopters (D). The SA is measured at 50 Lp/mm and 4mm aperture. This graphical representation is interpolated by a polynomial curve with equation S/l = -0.00002 x3 + 0.0008 x2 - 0.0025 x + 0.1982 where x is the optical power of the IOL. As can be seen in Figure 6B, the invention provides an IOL 1 whose SA depends to a very limited extent on the optical power of the IOL. A slight decrease in SA is found with decreasing optical power. In fact, lower power IOLs are actually flatter and more difficult to make aspheric. EDOF values and SA values follow the same trend and are strongly correlated.

[087] Figure 6C illustrates a graphical representation of a collection of points with error bars corresponding to experimental optical bench measurements of the MTF of IOL 1, read on the 88 axis and measured at 50 cy/mm, as a function of the optical power of the IOL, read on the 85 axis and measured in diopters (D). The MTF is measured at 50 Lp/mm and 3 mm aperture, in the presence of a corneal model providing a spherical aberration of 0.28 μm (IS02). This graphical representation can be (very weakly) interpolated by a polynomial curve with equation where x is the optical power of the IOL. As can be seen in Figure 6C, the invention provides an IOL 1 whose MTF depends to a very limited extent on the optical power of the IOL.

[088] Figure 7 illustrates three graphical representations of average optical bench experimental measurements of the EDOF of IOLs 1 according to the invention, read on axis 86 and measured in diopters (D), as a function of an aperture (here being the pupil diameter), read on axis 89 and measured in millimeters (mm). The EDOF is defined as the power added in diopters from a maximum MTF peak to an MTF value of 0.17 at 50 Lp/mm. The average is calculated for measurements on an IOL 1 of each of the optical powers 10D, 15D, 20D, 25D, 30D and 35D. The three graphical representations correspond to the use of three different corneal models giving three different corneal spherical aberrations: - a corneal model giving a corneal spherical aberration of 0.00 μm (corresponding to reference number 71 or IS01); - a corneal model giving a corneal spherical aberration of 0.13 μm (± 0.2 μm) (with 5.15 mm aperture and IOL plan) (corresponding to reference number 72), - a corneal model giving a corneal spherical aberration of 0.28 μm (± 0.2 μm) (with 5.15 mm aperture and IOL plan) (corresponding to reference number 73 or IS02).

[089] These graphical representations clearly show that the EDOF of IOL 1 depends to a limited extent on the aperture and on the spherical aberrations of the cornea. Furthermore, for the classical monofocal IOL known in the prior art, after pupil dilation, the increase in a pinhole effect decreases rapidly, as does the resulting EDOF. This trend is fundamentally different for IOL 1 according to the invention, since the EDOF remains relatively high despite the increase in pupil diameter, and this for any of the three corneal models mentioned above.

[090] Figure 8 illustrates three graphical representations of average optical bench experimental measurements of the MTF of IOLs 1 according to the invention, read on axis 88, as a function of an aperture (here being the pupil diameter), read on axis 89 and measured in millimeters (mm). The MTF is measured at 50 Lp/mm. The average is calculated for measurements on an IOL 1 of each of the optical powers 10D, 15D, 20D, 25D, 30D and 35D. The three graphical representations correspond to the use of the three cornea models mentioned above (corresponding to reference numerals 71, 72 and 73). These graphical representations show that the MTF of IOL 1 depends to a limited extent on the aperture and on the spherical aberrations of the cornea.

[091] Figure 13 illustrates graphical representations of through focal MTF curves of two IOLs (corresponding, respectively, to curves 7A and 7B), read on the 88 axis, as a function of the LOLS optical powers, read on the 85 axis and measured in diopters (D), in a mid (far) optical power range (approximately 20D). The MTF is measured on an optical bench equipped with a corneal model that provides a 12:00 spherical aberration (IS01), at 50 lp/mm and 3 mm aperture. These curves 7A and 7B correspond to the MTF measurements for a standard monofocal IOL and for IOL 1 respectively. The elongated focus of the IOL 1 according to the invention is visible in Figure 13. An asymmetrical MTF peak is clearly shown in the case of the IOL 1 according to the invention, with an elongated focus towards higher powers (closer distances), while the MTF peak of the standard single-vision lens is basically symmetrical with respect to the power at best focus, this focus being attributed to long distances. These differences, as evidenced for the optical bench, would be responsible for the superior EDOF and better clinical visual acuity at intermediate distance of the IOL 1 according to the invention.

[092] Each of Figures 9A-C illustrates graphical representations of experimental optical bench measurements of fourth-order spherical aberration (indicated hereinafter by SA), read on the 90 axis and measured in microns (miti), as a function of an aperture (being the pupil diameter), read on the 89 axis and measured in millimetres (mm). For each of these figures, the SA is measured at 50 Lp/mm and for: - one of the three cornea models mentioned above considered in isolation (corresponding to reference numeral 74) - an IOL 1 according to the invention considered in isolation (corresponding to reference numeral 75) - said specific cornea model combined with said IOL 1 (corresponding to reference numeral 76)

[093] The cornea models considered in Figure 9A, 9B and 9C are respectively: - the cornea model that provides a corneal spherical aberration of 0.28 μm (± 0.2 μm) (with 5.15 mm aperture and IOL plane), - the cornea model that provides a corneal spherical aberration of 0.13 μm (± 0.2 μm) (with 5.15 mm aperture and IOL plane), and - the cornea model that provides a corneal spherical aberration of 0.00 μm.

[094] Compared to the known classical monofocal IOLs, IOL 1 differs in the amount of SA it provides on its own. The SA of IOL 1 is negative and decreases rapidly with opening. The SA is much more negative for IOL 1 compared to the SA of known classical monofocal IOLs. As a consequence, the SA resulting from the combination of any corneal model and IOL 1 is basically determined by the SA of IOL 1, since the SA of IOL 1 overcompensates for the (small) positive SA of either corneal model. The residual SA is then advantageously only very slightly affected by the choice of corneal model.

[095] After the existence of EDOF for the IOL 1 according to the invention, a combined optical refraction of the anterior 2 and posterior 3 optical surfaces with an average corneal model (preferably as defined in paragraph [0049]) (arranged on the optical axis Z anterior with respect to the IOL 1) provides a continuous and regular map 9 of optical power comprising a central global maximum 91 along the optical axis Z surrounded by a scattered central region 92 of lower optical power (corresponding to the EDOF). This map 9 is illustrated in figures 10A and 10B, for an optical power of the IOL of 35D and 20D, respectively, within a (reading) window centered on the optical axis Z with a diameter of 4 mm. It is known that said optical power of the IOL is defined as an average optical power (the optical power represented by the map 9) measured without correction within a (reading) window centered on the optical axis Z with a diameter of 3 mm. The central region 92 is spread over about half a diameter d of the anterior 2 and posterior 3 optical surfaces and surrounded by a first ring 93, 93' of points of the map 9 which are inflection points (in the case of FIG. 10A) or local minima of optical power (in the case of FIG. 10B). This first ring 93, 93' corresponds in both cases to the radial change in the trend of the optical power. FIG. 10B has illustrated more faithfully such a general map 9 of optical power for optical power around 20D. In this case, the map 9 also comprises: - said first ring 93 of local minima of optical power surrounding the spread central region 92, and - a second ring 94 of local maxima of optical power surrounding the first ring 93.

[096] More generally, the IOLs 1 according to some embodiments of the invention comprise a collection of rings, such as rings 93 and 94, of variable, progressively alternating maximum and minimum optical power. It should be noted that the map 9 for any given IOL optical power is very smooth, both continuous and regular. It does not divide into zone partitions with fixed optical power.

[097] Sectional representations of the IOL 1 according to preferred embodiments of the invention are further illustrated in Figure 11A (for an optical power equal to 10D), in Figure 11B (for an optical power equal to 24D) and in Figure 11C (for an optical power equal to 35D). The section of these IOLs 1 is made along a plane comprising the optical axis Z. The geometry and concavity or convexity of the anterior 2 and posterior 3 optical surfaces commented on above are visible in these Figures 11AC. These anterior 2 and posterior 3 optical surfaces are separated by an internal body 41 from the central optical part 4 which is made of a raw biomaterial. The inner body 41 has a predetermined central thickness E, which is measured along the optical axis Z, and comprised between 0.3 and 0.7 mm, regularly depending on the optical power of the IOL, such that a peripheral thickness of the IOL comprised between 0.2 and 0.3 mm (preferably of about 0.25 mm) is provided for connecting the flexible haptics 5 to the central optical part 4.

[098] As illustrated in figure 12A, the central optical part 4 of the IOL 1 preferably has a principal optical plane (M) separated from the vertex (51) of the flexible haptics (5) by a predetermined distance (HC) measured along the optical axis (Z), comprised between 0.00 and 0.45 mm. This distance (HC) depends continuously and regularly on the optical power of the IOL 1 through a function, the graph of which is represented in figure 12B. The distance (HC) is read on the axis 62, measured in millimeters (mm), as a function of the optical power which is read on the axis 61, measured in diopters (D). This function is continuously increasing for increasing optical powers and its graph presents a sigmoid profile. This distance (HC) is advantageously calculated in view of the geometry of the anterior 2 and posterior 3 optical surfaces to ensure the longitudinally stable (IOL power invariant) position of the principal optical plane of IOL 1 relative to the optical axis Z when implanted in an eye.

[099] In other words, the present invention relates to an intraocular lens 1 with extended depth of focus comprising anterior 2 and posterior 3 aspherical optical surfaces. A specific aspherical geometry of these optical surfaces 2 and 3 is described within the scope of this invention.

[0100] The present invention has been described in relation to specific embodiments that have a merely illustrative value and should not be considered limiting. The person skilled in the art will appreciate that the present invention is not limited to the examples that are illustrated and/or described herein above. The invention comprises each of the new technical features described in this document, as well as their combinations.

Claims (15)

1. An intraocular lens (1) comprising: • an anterior optical surface, and • a posterior optical surface, both extending radially outwardly relative to an optical axis (Z); the intraocular lens (1) CHARACTERIZED by the fact that: • a first surface (2) between the anterior and posterior optical surfaces is defined by the equation: where: • zst(r) is a component, measured along the optical axis (Z), of a displacement vector from a vertex (21) of the first surface (2), to any point on the latter at a radius r from the optical axis (Z); • Rst is a radius of curvature of the first surface (2) evaluated at said vertex (21); • is a conic constant of the first surface (2) evaluated at said vertex (21) and defined as a function of said radius of curvature Rst of the first surface (2) by the relation: where erf indicates a Gaussian error function, and where a, b, c, A, B, C, D are constant real numbers, such that: ae [0.050; 0.075], be [-1; 0], ce [-20; 0], A e [-41; -39], B e [0.07; 0.13], C e [-2.6; -2.0] and D e [0.75; 1.25]; is an asphericity coefficient of order 2i of the first surface (2); • is a second surface (3) between the anterior and posterior optical surfaces and different from said first surface (2 is defined by the equation: where: • znd(r) is a component, measured along the optical axis (Z), of a displacement vector from a vertex (31) of the second surface (3) to any point on the latter at a radius r from the optical axis (Z); • Rnd < 0 is a radius of curvature of the second surface (3) evaluated at said vertex (31); • Knd (Rnd) is a conic constant of the second surface (3) evaluated at said vertex (31) and defined as a function of said radius of curvature Rnd of the second surface (3) by the relation: where f, g, h are constant real numbers, such as: f ϵ [0.08; 0.12], g ϵ [1.0; 1.6] and h ϵ [0; 9]; is an asphericity coefficient of order 2i of the second surface (3); in which the asphericity coefficients of order less than or equal to 10 of the first (2) and second (3) surfaces are both non-zero and bounded in absolute value by 0.1; in which the asphericity coefficients of order strictly greater than 10 of the first (2) and second (3) surfaces are equal to zero; the anterior and posterior optical surfaces are such that the intraocular lens (1) provides an extended depth of focus. 2. Intraocular lens (1) according to claim 1, CHARACTERIZED by the fact that: a ϵ [0.060; 0.075] and/or b ϵ [-0.5; -0.2] and/or c ϵ [-12; -10], and/or A ϵ [-40.1; -39.9] and/or B ϵ [0.080; 0.095] and/or C ϵ [-2.35; -2.05], and/or D ϵ [0.9; 1.1], and/or f ϵ [0.085; 0.105] and/or g ϵ [1.05; 1.40] and/or h ϵ [3; 6]. 3. Intraocular lens (1) according to claim 1 or 2, CHARACTERIZED by the fact that: where, for each j ϵ {1, 2, 3}, pj ≥ 10. 4. Intraocular lens (1) according to any one of claims 1 to 3, CHARACTERIZED by the fact that: - it has an optical power strictly less than 14D, and Rst < 0; or - it has an optical power greater than or equal to 14D and Rst > 0. 5. Intraocular lens (1) according to any one of claims 1 to 4, CHARACTERIZED by the fact that: and/or 6. Intraocular lens (1) according to any one of claims 1 to 5, CHARACTERIZED by the fact that the first surface (2) is the anterior optical surface and the second surface (3) is the posterior optical surface, the optical axis (Z) being directed from the anterior surface to the posterior surface. 7. Intraocular lens (1) according to claim 6, CHARACTERIZED by the fact that it has an optical power greater than or equal to 14D, and by the fact that: - an elevation map evaluated in a radial coordinate on the first surface (2), considering a plane perpendicular to the optical axis (Z) as a zero elevation reference plane and considering the optical axis (Z) as a reference axis for an elevation evaluation: • presents a local minimum at the vertex (21) of the first surface (2), • is enlarged from the vertex (21) of the first surface (2) to an edge of that surface (2); - an elevation map evaluated in a radial coordinate on the second surface (3), considering the plane perpendicular to the optical axis (Z) as a zero elevation reference plane and considering the optical axis (Z) as a reference axis for an elevation evaluation, presents: • a local maximum at the vertex (31) of the second surface (3); • a peripheral local minimum (32) at a positive distance from an edge of the second surface (3); • an inflection point (33) situated between said local maximum and said peripheral local minimum (32), and: • is decreasing from the vertex (31) of the second surface (3) to the peripheral local minimum (32), • is increasing from the peripheral local minimum (32) to an edge of said second surface (3); or by the fact that it has an optical power strictly greater than 12D and strictly less than 14D, and by the fact that: - an elevation map evaluated at a radial coordinate on the first surface (2), considering a plane perpendicular to the optical axis (Z) as a zero elevation reference plane and considering the optical axis (Z) as a reference axis for an elevation evaluation, presents: • a local maximum at the vertex (21) of the first surface (2); • a peripheral local minimum at a positive distance from an edge of the first surface (2); • an inflection point situated between said local maximum and said peripheral local minimum; and: • is decreasing from the vertex (21) of the first surface (2) to said peripheral local minimum, • is increasing from said peripheral local minimum to an edge of the first surface (2); - an elevation map evaluated at a radial coordinate on the second surface (3), considering the plane perpendicular to the optical axis (Z) as a zero elevation reference plane and considering the optical axis (Z) as a reference axis for an elevation evaluation, presents: • a local maximum at the vertex (31) of the second surface (3); • a peripheral local minimum (32) at a positive distance from an edge of the second surface (3); • an inflection point (33) situated between said local maximum and said peripheral local minimum (32), and: • is decreasing from the vertex (31) of the second surface (3) to the peripheral local minimum (32), • is increasing from the peripheral local minimum (32) to an edge of said second surface (3); or by the fact that it has an optical power less than or equal to 12D, and by the fact that: - an elevation map evaluated at a radial coordinate on the first surface (2), considering a plane perpendicular to the optical axis (Z) as a zero elevation reference plane and considering the optical axis (Z) as a reference axis for an elevation evaluation: • presents a local maximum at the vertex (21) of the first surface (2); • is decreasing from the vertex (21) of the first surface (2) to an edge of that surface (2); - an elevation map evaluated at a radial coordinate on the second surface (3), considering the plane perpendicular to the optical axis (Z) as a zero elevation reference plane and considering the optical axis (Z) as a reference axis for an elevation evaluation: • presents a local maximum at the vertex (31) of the second surface (3); • is decreasing from the vertex (31) of the second surface (3) to an edge of that surface (3). 8. Intraocular lens (1) according to any one of claims 1 to 7, CHARACTERIZED by the fact that a combined optical refraction of the anterior and posterior optical surfaces with a cornea model anteriorly external to the intraocular lens (1) provides a continuous and regular map (9) of optical power comprising a central global maximum (91) along the optical axis (Z) surrounded by a scattered central region (92) of lower optical power. 9. The intraocular lens (1) of claim 8, wherein the central region (92) is spread over about half a diameter (d) of the anterior and posterior optical surfaces, and surrounded by a first ring (93, 93') of map points (9) that are inflection points or local optical power minima; and wherein the map (9) further comprises a second ring (94) of points that are local optical power maxima, said second ring (94) surrounding said first ring (93). 10. Intraocular lens (1) according to any one of claims 1 to 9, CHARACTERIZED by the fact that it comprises: • a central optical portion (4) whose: • an anterior surface is the anterior optical surface; and • a posterior surface is the posterior optical surface; • a plurality of flexible haptics (5) connected to the central optical portion (4), configured to stabilize the intraocular lens (1) in a capsular bag of an aphakic eye; and by the fact that a distance (HC), measured along the optical axis (Z), between a flexible haptic apex (51) (5) and a principal optical plane (M) of the central optical part (4) corresponds to an image of an optical power of the intraocular lens (1) by a continuous regular function, continuously increasing for increasing optical powers, and limited by 0.45 mm, such that said principal optical plane (M) is stably parallel to the optical axis (Z) when the intraocular lens (1) is implanted in a capsular bag of an aphakic eye. 11. Intraocular lens (1), according to claim 10, CHARACTERIZED by the fact that it comprises four closed flexible haptics (5) each forming a handle based on the central optical part (4) and by the fact that it is invariant in shape under a rotation of 180° around the optical axis (Z). 12. A method for manufacturing an intraocular lens (1) as defined in any one of claims 1 to 11, comprising the steps: (a) modeling an optic with a profile pattern of aspherical optical surfaces; (b) calculating a refractive efficiency distribution for light propagation through the modeled optic; (c) selecting profile parameters of aspherical optical surfaces according to the calculated refractive efficiency distribution so as to achieve the desired refractive efficiencies; and (d) forming the modeled optic with the selected parameters from a raw biomaterial. 13. Manufacturing method according to claim 12, CHARACTERIZED by the fact that the aspherical optical surface profile parameters selected in step (c) depend continuously and regularly on an optical power of the intraocular lens (1). 14. Manufacturing method according to claim 12 or 13, CHARACTERIZED by the fact that a conical constant Kst of a first surface (2) between these aspherical optical surfaces, evaluated at its vertex (21), is selected in step (c) as a function of a radius of curvature Rst of the first surface (2) evaluated at this vertex (21) by the relation where erf indicates a Gaussian error function, and where a, b, c, A, B, C, D are constant real numbers; and a conic constant Knd of a second surface (3) between these aspherical optical surfaces, evaluated at its vertex (31), is selected in step (c) as a function of a radius of curvature Rnd of the second surface (3) evaluated at this vertex (31) by the relation where f, g, h are constant real numbers. 15. Manufacturing method according to any one of claims 12 to 14, CHARACTERIZED by the fact that the intraocular lens (1) is according to claim 10, and by the fact that the manufacturing method comprises the step of selecting a distance (HC), measured along the optical axis (Z), between a flexible haptic apex (51) (5) and a principal optical plane (M) of the central optical part (4), as a function of an optical power of the intraocular lens (1) as an image of the latter by a continuous and regular function, continuously increasing for increasing optical powers, and limited by 0.45 mm, so as to achieve a desired longitudinal stability of the principal optical plane (M) parallel to the optical axis (Z) when the intraocular lens (1) is implanted in a capsular bag of an aphakic eye.