Methods used to determine optical lenses

Abstract

A method implemented by a computer device for determining an optical lens suitable for a wearer and optimized for at least a given optical criterion having a target value around a specific gaze direction, the method comprising: obtaining an initial optical lens having a prescription of the wearer under given wearing conditions in the specific gaze direction; determining an intermediate optical lens by optimizing the initial optical lens using an optimization function, so that the difference between the value of at least the given optical criterion of the intermediate optical lens and the target value of the gaze direction around the specific gaze direction is less than or equal to a threshold value; determining the optical lens by optimizing the intermediate optical lens to obtain a maximum gaze direction area around the specific gaze direction, wherein the difference between the value of at least the given optical criterion and the target value around the specific gaze direction is less than or equal to the threshold value.

Description

Technical Field

[0001] The invention relates to a method implemented by computer means for determining an optical lens suitable for a wearer and optimized for at least a given optical criterion having a target value. Background Art

[0002] It is known to design an optical lens based on a target optical lens. The target optical lens is a virtual lens having an optimal optical function. The purpose is to design an optical lens having an optical function as similar as possible to that of the target optical lens.

[0003] The ophthalmologist provides the wearer with a prescription. The wearer provides the prescription to the lens supplier and must receive optical lenses that fit his or her prescription.

[0004] However, optical lenses may have a restricted area where the wearer can gaze comfortably.

[0005] What is needed is a method to identify optical lenses with the larger areas that a wearer may be seeking. Summary of the invention

[0006] To this end, the invention proposes a method, for example implemented by computer means, for determining an optical lens suitable for a wearer and optimized for at least a given optical criterion with a target value around a specific gaze direction, the method comprising:

[0007] - obtaining an initial optical lens having a prescription for the wearer under given wearing conditions in a specific gaze direction;

[0008] - determining an intermediate optical lens by optimizing the initial optical lens using an optimization function so that the difference between the value of at least a given optical criterion of the intermediate optical lens and a target value of a gaze direction around a specific gaze direction is less than or equal to a threshold value;

[0009] - determining the optical lens by optimizing the intermediate optical lens to obtain a maximum gaze direction area around a specific gaze direction, wherein the difference between at least a value of a given optical criterion and a target value around the specific gaze direction is less than or equal to a threshold value.

[0010] Advantageously, the use of the proposed method enables maximizing a gaze direction area around a specific gaze direction on an optical lens in which at least the optical criterion is close to a target value. The determined optical lens is an optical lens that provides a maximum gaze direction area around a specific gaze direction through which the wearer can comfortably find.

[0011] According to further embodiments which may be considered alone or in combination:

[0012] - the initial optical lens has a prescription of the wearer for a given object distance under given wearing conditions in a specific gaze direction, the initial lens being optimized for said object distance when the intermediate optical lens is determined, and the intermediate optical lens being optimized for said object distance when the optical lens is determined, and / or,

[0013] - at least one given optical criterion is optical power, and / or,

[0014] - at least one given optical criterion is astigmatism, and / or

[0015] - at least one given optical criterion is acuity, and / or

[0016] - at least a given optical criterion is distortion, and / or,

[0017] - the particular gaze direction is a primary gaze direction, and / or,

[0018] - the optimization function used when determining the intermediate optical lens comprises a weighted cost function depending on the gaze direction, wherein the weight decreases when the angle formed by the gaze direction and the specific gaze direction increases, and / or,

[0019] - adding a penalty function to the optimization function used when determining the intermediate optical lens to ensure that within a defined gaze direction area around a specific gaze direction, the difference between the value of at least a given optical criterion of the intermediate optical lens and a target value around a specific gaze direction is less than or equal to a threshold value, and / or,

[0020] - the intermediate optical lens is determined by optimizing at least one surface of the initial optical lens, and / or,

[0021] - the intermediate optical lens is determined by adding an optimized layer to at least one surface of the initial optical lens, and / or,

[0022] - the intermediate optical lens is determined by adding a Zernike layer to at least one surface of the initial optical lens, and / or,

[0023] - the order of the Zernike layer is greater than or equal to 4, and / or,

[0024] - the optical lens is determined by optimizing at least one surface of an intermediate optical lens, and / or,

[0025] - the optical lens is determined by adding a Zernike layer to at least one surface of the intermediate optical lens, and / or,

[0026] - the order of the Zernike layer is less than or equal to 10, and / or,

[0027] - optimization of the intermediate optical elements including derivative-free optimization, and / or,

[0028] - a gaze direction region around a specific gaze direction is centered on the specific gaze direction, and / or,

[0029] - a gaze direction zone around a specific gaze direction has a shape of the eyeglass frame selected by the wearer, and the size of the gaze direction zone is controlled using a homothetic transformation of the shape of the eyeglass frame, and / or

[0030] - where the threshold is standard or customised depending on the wearer, and / or

[0031] - the optical lenses are ophthalmic lenses, and / or

[0032] - the optical lenses are single vision lenses, and / or,

[0033] - the optical lens is a multifocal lens, such as a progressive multifocal lens, and / or,

[0034] - the threshold value is defined by at least one wearer-specific sensitivity parameter associated with the optical criterion, and / or

[0035] The specific sensitivity associated with the optical criterion corresponds to the wearer's tolerance for deviations from the optical criterion.

[0036] The present invention will be better understood as it will be described in detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The astigmatism axis γ of ophthalmic lenses in TABO convention is shown;

[0038] Figure 2 The cylindrical axis γAX in the convention used to characterize aspheric surfaces is shown;

[0039] Figure 3 The local sphericity along any axis at a point on the surface is shown;

[0040] Figure 4 and Figure 5a The reference system defined with respect to the micro-markings is shown for the surface with the micro-markings and the surface without the micro-markings respectively;

[0041] Figure 5b and Figure 5c The optical system of the eye and ophthalmic lenses is schematically shown;

[0042] Figure 5d Ray tracing from the center of eye rotation is shown;

[0043] Figure 6 shows a flowchart according to the description of the present invention; and

[0044] Figures 7 to 20The optical power and adverse astigmatism of the Tscherning optical lens and the optimized optical lens according to the description of the present invention are shown in the gaze direction diagram DETAILED DESCRIPTION

[0045] The present disclosure relates to a method, for example implemented by a computer device, for determining an optical lens suitable for a wearer and optimized for at least a given optical criterion having a target value.

[0046] An optical lens is any optical element having an optical function, such as an ophthalmic lens that provides correction for the wearer. An optical lens is adapted to the wearer's prescription and can be adapted to the wearer's wearing conditions. An optical lens here can be a single vision lens or a multifocal optical lens, such as a progressive multifocal lens.

[0047] Further, optical lenses are usually manufactured according to the wearer's specifications. For example, in the case of ophthalmic lenses for correcting or improving vision, the ophthalmic lenses are manufactured according to a wearer's prescription corresponding to the wearer's vision requirements. In addition, the shape and size of the eyeglass frame supporting the ophthalmic lens can be taken into account. At least one of the surfaces of the ophthalmic lens is processed to provide an optical function that conforms to the wearer's prescription in combination with the opposite surface. The contour of the ophthalmic lens can be edged according to the shape of the eyeglass frame into which the ophthalmic lens is to be mounted.

[0048] Optical lenses are usually manufactured from optical lens blanks such as semi-finished lens blanks. Semi-finished lens blanks usually have two opposite surfaces, at least one of which is unfinished.

[0049] Typically, a semi-finished lens blank is selected from a set of semi-finished lens blanks based on the wearer's prescription.

[0050] The optical lens may be a single vision lens. A single vision lens is designed to have a single sphero-cylindrical power corresponding to the prescription at the reference point. When the optical lens is a single vision lens, the reference point may be a control point, such as a fitting cross or a prism reference point.

[0051] The "optician cross" is a temporary mark written on the finished surface of semi-finished lens blanks and on the finished surface of optical lenses. If there is no temporary mark or it has been erased, the technician can always locate these control points on the lens by using the existing installation drawings, the manufacturer's technical documentation and / or permanent micro-markings.

[0052] The optical lens in the ophthalmic lens set can be a multifocal lens. A multifocal lens is designed to have more than one focal power. For example, multifocal lenses include bifocal, trifocal and progressive multifocal lenses.

[0053] When the ophthalmic lens is a progressive multifocal lens, the primary reference point may be the distance control point. When the ophthalmic lens is designed for near or intermediate vision, the primary reference point may be the near control point. Other reference points are the prism reference point, the fitting cross and possible secondary reference points. The fitting cross may be determined based on the position of the prism reference point, e.g. when the lens is a progressive multifocal lens, the fitting cross is located 4 mm above the prism reference point.

[0054] In addition, when the ophthalmic lens is a progressive multifocal lens, it includes:

[0055] - Main reference point for far vision,

[0056] - Near reference point,

[0057] - A main line, which starts at one end of the optical interest area, ends at the opposite end of the optical interest area and passes through the primary reference point and the secondary reference point.

[0058] The progressive multifocal lens comprises at least one, but preferably two, non-rotationally symmetric aspheric surfaces, such as but not limited to a progressive surface, a regressive surface, a toric surface or a non-toric surface.

[0059] Standard or general wearing conditions are to be understood as the position of the optical lens relative to the eye of a standard wearer, in particular defined by the intersection of the fitting cross with the main viewing direction, a distance of 25.5 mm between the center of rotation of the eye and the first main surface of the lens, a anteversion angle of 8° and a wrap angle of 0°.

[0060] The anteversion angle is the angle in the vertical plane between the optical axis of the optic and the visual axis of the eye in the primary position, which is usually considered to be horizontal.

[0061] The wrap angle is the angle in the horizontal plane between the optical axis of the optic and the visual axis of the eye in the primary position, which is usually considered to be horizontal.

[0062] Other fitting conditions may be used. The fitting conditions may be wearer dependent and may be calculated from a ray tracing program for a given lens.

[0063] The optical criterion may be defined as a parameter according to which the optimization of the lens is determined. The optical criterion may be at least one parameter of power, astigmatism, acuity and distortion.

[0064] It is known that the minimum curvature CURV at any point on an aspherical surface is min It is defined by the following formula:

[0065]

[0066] Among them, R max is the local maximum radius of curvature, expressed in meters, and CURVmin Expressed in diopters.

[0067] Similarly, the maximum curvature CURV at any point on an aspherical surface max It can be defined by the following formula:

[0068]

[0069] Where R min is the local minimum radius of curvature, expressed in meters, and CURV max Expressed in diopters.

[0070] When the surface is aspherical, the local minimum radius of curvature R min and the local maximum curvature radius R max are different.

[0071] According to the minimum curvature CURV min and the maximum curvature CURV max These expressions, denoted SPH min The minimum spherical power and is denoted as SPH max The maximum spherical power can be inferred depending on the type of surface considered.

[0072] When the surface under consideration is the object-side surface (also called the front surface), these expressions are as follows:

[0073] as well as

[0074] Where n is the refractive index of the lens's constituent material.

[0075] If the surface under consideration is the lateral surface of the eyeball (also called the posterior surface), these expressions are as follows:

[0076] as well as

[0077] Where n is the refractive index of the lens's constituent material.

[0078] Based on the thin lens approximation, taking into account that the thickness of the lens is very small compared to the radius of curvature, the maximum and minimum focal powers can be expressed as follows:

[0079] P max ≈SPH max，后 +SPH max，前

[0080] P min ≈SPH min，后 +SPH min，前

[0081] As is well known, the average spherical power SPH at any point on the aspherical surface is mean It can also be defined by the following formula:

[0082]

[0083] Therefore, the expression for the mean spherical power depends on the surface considered:

[0084] - If the surface is an object side surface, then

[0085] - If the surface is the lateral surface of the eyeball, then

[0086] - Also through the formula CYL = | SPH max -SPH min |Define the cylindrical power CYL.

[0087] Based on the thin lens approximation, taking into account that the thickness of the lens is very small compared to the radius of curvature, the average focal power can be expressed as follows:

[0088] P mean ≈SPH mean，后 +SPH mean，前

[0089] The properties of any surface of a lens can be expressed in terms of the local average spherical and cylindrical powers.

[0090] It can be noted that when the surface is partially or completely spherical, the local minimum radius of curvature R min and the local maximum curvature radius R max are the same, and accordingly, the minimum curvature CURV min and the maximum curvature CURV max is the same, so the minimum spherical power SPH min and maximum spherical power SPH max The same is true.

[0091] For aspherical surfaces, the local cylindrical axis γ can be further defined AX . Figure 1 shows the astigmatism axis γ as defined in the TABO convention, and Figure 2 Shows the cylindrical axis γ defined as the convention for characterizing aspherical surfaces AX .

[0092] Cylindrical axis γ AX is the maximum curvature CURV maxThe angle of the orientation relative to the reference axis and in the selected rotation direction. In the convention defined above, the reference axis is horizontal (the angle of this reference axis is 0°) and the rotation direction is counterclockwise for each eye when looking at the wearer (0°≤γ AX ≤180°). Therefore, the cylindrical axis is γ AX An axis value of +45° represents an obliquely oriented axis extending from the upper right quadrant to the lower left quadrant when looking at the wearer.

[0093] In addition, based on the knowledge of the local cylindrical axis γ AX The Gaussian formula can express the local spherical power SPH along any axis θ, θ is Figure 2 A given angle in the reference frame defined in . Figure 3 The axial position θ is shown in .

[0094] SPH(θ)=SPH max cos 2 (θ-γ AX )+SPH min sin 2 (θ-γ AX )

[0095] As expected, when using the Gaussian formula, SPH(γ AX )=SPH max And SPH(γ AX +90°)=SPH min .

[0096] The Gaussian formula can also be expressed in terms of curvature, such that the curvature CURV along each axis forms an angle θ with the horizontal axis, as follows:

[0097] CURV(θ)=CURV max cos 2 (D-γ AX )+CURV mim sin 2 (θ-γ AX )

[0098] Therefore, the surface can be locally defined by a triplet consisting of the maximum spherical power SPH max , minimum spherical power SPH min and cylindrical axis γ AX Alternatively, the triplet can be composed of the mean spherical power SPH mean , cylindrical lens power CYL and cylindrical lens axis γ AX constitute.

[0099] Whenever a lens is characterized by reference to one of its aspherical surfaces, as in Figure 4 As shown in FIG. 5 , reference systems with respect to the micro-markings are defined for the surface with the micro-markings and the surface without the micro-markings, respectively.

[0100] The micro-markings also make it possible to define a coordinate system for the two surfaces of the ophthalmic lens.

[0101] Figure 4 The coordinate system of the surface with micro-marks is shown. The center of the surface (x=0, y=0) is the point of the surface where the surface normal N intersects the center of the line segment connecting the two micro-marks. MG is a collinear single vector defined by the two micro-marks. The vector Z of the reference system is equal to the single normal (Z=N); the vector Y of the reference system is equal to the vector product of Z and MG; the vector X of the reference system is equal to the vector product of Y and Z. {X,Y,Z} thus forms a direct orthogonal trihedron. The center of the reference system is the center of the surface x=0 mm, y=0 mm. The X axis is the horizontal axis and the Y axis is the vertical axis, as Figure 2 shown.

[0102] Figure 5a The coordinate system of the surface opposite to the surface with the micro-markings is shown. The center (x=0, y=0) of this second surface is the point at which the normal N intersecting the centers of the segments connecting the two micro-markings on the first surface intersects the second surface. The reference system of the second surface is constructed in the same way as the reference system of the first surface, i.e., the vector Z is equal to the single normal of the second surface; the vector Y is equal to the vector product of Z and MG; the vector X is equal to the vector product of Y and Z. As for the first surface, the X axis is the horizontal axis and the Y axis is the vertical axis, as Figure 2 The center of the reference system of the surface is also x=0 mm, y=0 mm.

[0103] Figure 5b and Figure 5c is a diagram of the optical system of the eye and lens, thereby illustrating the definitions used in the specification. More precisely, Figure 5b A stereogram representing such a system, showing the parameters α and β used to define the gaze direction. Figure 5c is the view in a vertical plane parallel to the front-to-back axis of the wearer's head and passing through the center of rotation of the eye with parameter β equal to 0.

[0104] The center of eye rotation is labeled Q'. Figure 5cThe axis Q'F' shown in dashed lines in is a horizontal axis that passes through the center of rotation of the eye and extends in front of the wearer, i.e., the axis Q'F' that corresponds to the main gaze angle. This axis cuts the front surface of the lens at a point called the fitting cross, which exists on the lens to enable the ophthalmologist to position the lens in the frame. The point of intersection of the rear surface of the lens with the axis Q'F' is point O. If O is located on the rear surface, it can be the fitting cross. A top ball with center Q' and radius q' is tangent to the rear surface of the lens at the point of the horizontal axis. As an example, a value of radius q' of 25.5 mm corresponds to a commonly used value and provides satisfactory results when wearing the lens.

[0105] Depend on Figure 5b The given gaze direction represented by the solid line in corresponds to the position of the eye rotating around Q' and the point J of the top ball; the angle β is the angle formed between the axis Q'F' and the projection of the straight line Q'J on the horizontal plane including the axis Q'F'; this angle appears Figure 5b The angle α is the angle formed between the axis Q'J and the projection of the straight line Q'J on the horizontal plane including the axis Q'F'; this angle appears Figure 5b and Figure 5c . Thus, a given gaze angle corresponds to a point J of the top sphere or to a pair (α, β). If the value of the gaze reduction angle is larger in the positive direction, the gaze is reduced more; and if the value is larger in the negative direction, the gaze is raised more.

[0106] In a given gaze direction, the image of a point M at a given object distance in object space is formed between two points S and T corresponding to a minimum distance JS and a maximum distance JT, which will be the sagittal and tangential local focal lengths. An image of a point at infinity in object space is formed at point F'. The distance D corresponds to the posterior coronal plane of the lens.

[0107] The Ergorama function is a function that associates the usual distance of an object point to each gaze direction. Typically, in far vision following the main gaze direction, the object point is at infinity. In near vision following a gaze direction substantially corresponding to an angle α of about 35° in absolute value toward the nasal side and an angle β of about 5°, the object distance is about 30 cm to 50 cm. In order to understand more details about possible definitions of the Ergorama function, US patent US-A-6,318,859 can be considered. This document describes the Ergorama function, its definition and its modeling method. For the method of the present invention, a point can be at infinity or not at infinity. The Ergorama function can be a function of the wearer's refractive error.

[0108] These elements can be used to define the wearer's optical power and astigmatism in each gaze direction. Consider an object point M at an object distance for a gaze direction (α, β). The object proximity ProxO is defined in object space for a point M on the corresponding ray as the reciprocal of the distance MJ between point M and point J of the top sphere:

[0109] ProxO=1 / MJ

[0110] This enables object proximity to be calculated within a thin lens approximation for all points of the top sphere.For a real lens, object proximity can be considered as the inverse of the distance between the object point and the front surface of the lens on the corresponding ray.

[0111] For the same gaze direction (α, β), the image of a point M with a given object proximity is formed between two points S and T corresponding to the minimum and maximum focal lengths, respectively (which will be the sagittal and tangential focal lengths). The quantity ProxI is called the image proximity of the point M:

[0112]

[0113] By analogy with the case of thin lenses, the optical power Pui can therefore be defined as the sum of the image proximity and the object proximity for a given gaze direction and a given object proximity, ie for a point in object space on the corresponding ray.

[0114] Pui=ProxO+ProxI

[0115] With the help of the same notation, for each gaze direction and for a given object proximity, the astigmatism Ast is defined as:

[0116]

[0117] This definition corresponds to the astigmatism of the beam produced by the lens. It can be noted that this definition gives a typical value of the astigmatism in the main gaze direction. The angle of astigmatism, which is usually called the axis, is the angle γ. The angle γ is the value of the astigmatism in the reference frame {Q',x m ,y m ,z m}. It corresponds to the angle by which the image S or T is formed, depending on the angle relative to the plane {Q', z m ,y m}Direction z m The convention used.

[0118] Possible definitions of lens power and astigmatism under wearing conditions can therefore be calculated as explained in the paper by B. Bourdoncle et al., entitled "Ray tracing through progressive ophthalmic lenses" (1990 International Lens Design Conference, DT Moore, ed., Proceedings of the British Institute of Photonics).

[0119] Figure 5d represents a stereogram of a configuration where the parameters α and β are non-zero. Thus, the fixed reference frame {x, y, z} and the reference frame associated with the eye {x m ,y m ,z m} to demonstrate the effect of eye rotation. The origin of the reference frame {x,y,z} is at point Q'. The z-axis is the Q'O axis and is oriented from the lens toward the eye. The y-axis is vertical and oriented upward. The x-axis makes the reference frame {x,y,z} orthogonal and direct. The reference frame {x m ,y m ,z m} is associated with the eye and its center is point Q'. m The axis corresponds to the gaze direction JQ'. Therefore, for the main gaze direction, the two reference frames {x,y,z} and {x m ,y m ,z m} are the same.

[0120] It is known that the properties of an optical lens can be expressed in several different ways, and in particular in a surface and optical way. A surface representation is therefore equivalent to an optical representation.

[0121] In fact, both representations are able to describe the same object from two different perspectives. Whenever the properties of a lens are optical, it refers to the ergma function-eye-lens system. For simplicity, the term 'ophthalmic lens' is used in this specification, but it must be understood as 'ergma function-eye-lens system'. These points are explained with the help of Figure 2 , Figure 4 and Figure 5a The horizontal or vertical coordinates in the defined reference system are used to locate the object.

[0122] The same properties can be calculated for the gaze directions. The gaze directions are usually given by their lowering in the frame and by their azimuth, the origin of which is the eye's center of rotation and the reference direction of which is the main gaze direction, which corresponds to the wearer looking straight ahead. When the lens is mounted in front of the eye, the ray trajectory in the main gaze direction will pass through the eye's center of rotation Q' and therefore through the center of the eye's pupil, and will intersect the front surface of the lens at its fitting cross. In the chosen frame, the fitting cross therefore corresponds to a lowering angle α of 0° and an azimuth β of 0°.

[0123] References Figure 5b to Figure 5d The description is given for central vision. In peripheral vision, since the gaze direction is fixed, the center of the pupil is considered instead of the center of eye rotation and the peripheral light direction is considered instead of the gaze direction. When considering peripheral vision, the angles α and β correspond to the light direction, not the gaze direction.

[0124] In the rest of this specification, terms such as "upper", "bottom", "horizontal", "vertical", "above", "below", "front", "back", etc., or other words indicating relative positions may be used. These terms should be understood in the wearing conditions of the lens.

[0125] It is worth noting that the "upper" portion of the lens corresponds to a negative lowering angle α < 0° and the "lower" portion of the lens corresponds to a positive lowering angle α > 0°. Similarly, the "upper" portion of the surface of the lens or semi-finished lens blank corresponds to a positive value along the y-axis, and preferably corresponds to a value along the y-axis greater than the y-value at the fitting cross, and the "lower" portion of the surface of the lens or semi-finished lens blank corresponds to a positive value along the y-axis as described above with respect to Figure 2 , Figure 5a and Figure 5b Negative values ​​of the y-axis within the defined reference system and preferably correspond to values ​​along the y-axis that are less than the y-value at the fitting cross.

[0126] Regarding the optical parameter considered as acuity, the “relative acuity” (called AC%_P) is defined as the result of the function of the mean refractive power error PE_P and the resulting astigmatism ASR according to the acuity model at a given point in object space (α, β, ProxO).

[0127] The mean refractive power error (referred to as PE_P) is defined as the mean refractive power difference between the actual power and the near power of the lens at a given point (α, β, ProxO) in object space according to the following equation:

[0128] PE_P(α,β,ProxO)=Pui(α,β,ProxO)-(Pui(FV)-ProxFV p )-ProxO

[0129] Where Pui(FV) refers to the distance gaze direction, for the position corresponding to ProxFV p The average refractive power of the wearer's prescription for objects at a distance. The prescription for distance vision is the distance corresponding to a given ProxFV p In most cases, ProxFV p =0.

[0130] An example of an embodiment of calculating relative acuity is provided below.

[0131] The "loss of acuity" is called ACU_P and is defined as a function of the relative acuity at a given point (α, β, ProxO) in object space according to the following equation:

[0132]

[0133] Where "log" is the base 10 logarithm.

[0134] In the sense of the present invention, optical distortions are aberrations that affect the geometry of the visual scene. Optical distortions may be aberrations (but not modifications of sharpness) produced by an ophthalmic lens (monofocal or progressive) or a part thereof. For example, we can use a specific combination of some decomposition terms of optical distortions using classical polynomial decompositions such as Zernike, Mooney, Chebychev polynomials, etc. Optical distortions may be more complex deformations (linear, nonlinear, local or global). Optical distortions may be dynamic distortions involving aberrations that change in time.

[0135] The target value is a given value corresponding to the design value related to the optical criterion in order to obtain an optical lens corresponding to the wearer's needs.

[0136] For example, target values ​​for optical criteria corresponding to optical power and astigmatism are defined by the prescription.

[0137] Regarding distortion, it is preferred to have a target value that is as low as possible.

[0138] like Figure 6 As shown, the method of the present disclosure includes at least:

[0139] - initial optical lens providing step S1,

[0140] - intermediate optical lens determination step S2, and

[0141] -Optical lens determination step S3.

[0142] During an initial optical lens providing step S1 , a wearer's prescription is provided for a given wearing condition in a specific gaze direction and for a specific object distance.

[0143] The specific gaze direction may correspond to a primary gaze direction. The primary gaze direction corresponds to a situation where the wearer is looking straight ahead.

[0144] In the case of single vision lenses, the single vision lenses are designed for a specific object distance. The object distance is about 40 cm for near vision, about 1 m for intermediate vision, and about 4 m for far vision. For a given single vision lens, the predetermined gaze angle is predefined because the optical lens is designed for a specific use.

[0145] The gaze direction for near vision is lower compared to distance and intermediate vision.

[0146] The initial optical lens providing step S1 can provide an initial optical lens which is adapted to the wearer's prescription under given wearing conditions in a specific gaze direction and object distance.

[0147] The initial optical lenses may be provided based on a database or may be calculated.The prescription parameters and wearing conditions may be wearer-dependent parameters or parameters corresponding to a standard wearer.

[0148] The provided optical lens may be a spherical lens, a toric lens or an aspherical lens. The provided optical lens is hereinafter referred to as an initial lens. The initial lens satisfies the prescription parameters.

[0149] The determination method further comprises an intermediate optical lens determination step S2. During intermediate optical lens S2, the intermediate optical lens is determined by optimizing the initial optical lens so that the difference between the value of the optical criterion of the intermediate optical lens and the target value around a specific gaze direction is less than or equal to a threshold value.

[0150] The threshold value is either standard or customized depending on the wearer.The standard threshold value may be a predefined value based on the lens prescription, for example.

[0151] The threshold value may be based on a wearer's specific sensitivity parameter to the optical criterion. Advantageously, this enables the design of an optimized intermediate optical lens that takes into account the wearer's tolerance according to the gap between the target optical criterion value and the optical criterion value in a given direction. The specific sensitivity parameter may be based on age, the wearer's prescription or the wearer's measured sensitivity to the optical criterion.

[0152] The intermediate optical lens corresponds to an optimization of the initial optical lens, wherein around a specific gaze direction, the difference between the value of the optical criterion of the initial optical lens and a target value is less than or equal to a threshold value.

[0153] In order to optimize the initial optical lens, layers may be applied to the surface of the initial optical lens.

[0154] In an embodiment, the layer is applied on the back surface of the initial lens, which back surface corresponds to the surface facing the eye of the wearer after the lens has been determined, manufactured and worn by the wearer.

[0155] Optimization of the initial optics may be based on layers that may be defined by a weighted cost function or penalty function.

[0156] The layer to be applied may be a Zernike layer.

[0157] In this way, as an example, an intermediate optical lens may be determined by adding a Zernike layer to at least one surface of the initial optical lens, preferably the rear surface as defined above.

[0158] The front surface of the intermediate lens may be a spherical surface, whereas the rear surface, to which the Zernike layer is applied, is a three-dimensional surface.

[0159] In case of using Zernike layers, the order of the Zernike polynomials does not need to be very high for single vision lenses.

[0160] The order of the Zernike layer is greater than or equal to four, preferably greater than six, even more preferably greater than ten.

[0161] The optimization function used when determining the intermediate optic may be based on a weighted cost function of gaze directions, wherein the weight of a gaze direction decreases based on the distance to a particular gaze direction.

[0162] An example of a weighted cost function is given below. In this example, the optical criteria are optical power and adverse astigmatism, and the gaze direction is defined as the primary gaze direction.

[0163] A(X,δ p o w ,δ ast ) defines a set of all gaze directions such that the power error and the unwanted astigmatism are below a given threshold δ p o w , δ ast .

[0164] In this way, A is defined by the following formula:

[0165]

[0166] X is the vector of lens variables used for optimization. For example, the components of vector X can be parameters that define the surface, such as Zernike coefficients.

[0167] More generally, it can be any parameter that defines an optical lens:

[0168] - surface parameters (Zernike coefficients, spherical radius, aspheric coefficients, height of control points, etc.…),

[0169] - kinematic parameters (translation, rotation from one surface to another),

[0170] - Refractive index parameters, such as the coefficient of the refractive index gradient.

[0171] δ p o w defines the threshold value of optical power, and δ ast A threshold for adverse astigmatism was defined.

[0172] A set of all relevant gaze directions is defined by the letter K. In this way:

[0173] (α, β)∈K

[0174] The weighted cost function used to determine the layer to be applied to one of the surfaces of the initial optical lens is a least squares method defined as follows:

[0175]

[0176] The parameters u and v define the weights that allow favoring the power error or unfavorable astigmatism, depending on the wearer's sensitivity. The above examples concern power and unfavorable astigmatism, but other optical criteria may also be considered.

[0177] W is a weighting function for the gaze direction that allows a preferential distribution of the aberrations over the lens. The aberrations may be chosen to be equal to zero in the gaze direction (0,0) and to increase monotonically away from the center.

[0178] For example, W(α,β) is defined as follows:

[0179]

[0180] The choice of the weighting function parameter k will depend on how fast the lens designer allows the aberrations to increase as one moves away from the center (0,0) of the lens. Smaller values ​​of k tend to favor the center (0,0) of the lens and produce very small aberrations in the center, with the tradeoff being that aberrations increase fairly quickly as one moves away from that center. Intermediate values ​​of k give a smoother progression of errors and help maximize the optic disc radius where all gaze directions are below a given threshold in terms of both power error and adverse astigmatism. Larger values ​​of k are equivalent to using no weighting at all since W~=1 for all gaze directions.

[0181] Advantageously, such an optimization function including weights facilitates optimization of areas of the lens, in particular, areas around a specific gaze direction which are, in the case of single vision lenses, areas of the lens most frequently used by the wearer.

[0182] According to an embodiment of the present disclosure, a penalty function may be added to the optimization function used when determining an intermediate optical lens to ensure that within a defined area around a specific gaze direction, the difference between the value of the optical criterion of the intermediate optical lens and the target value is less than or equal to a threshold.

[0183] This example is similar to the above example, where the initial optical lens is a single vision lens and where the optical criteria are power and adverse astigmatism. In this example, the specific gaze direction is also the primary gaze direction.

[0184] The penalty function is a penalty function of the weighted cost function (1). The penalty ensures that within the defined area, the power error and adverse astigmatism are less than a threshold. The threshold can be any value in the range of 0.03D to 0.25D, for example 0.06D.

[0185] The penalty function is defined as follows:

[0186]

[0187] The parameters u, v, u′ and v′ correspond to the weights that allow for favorable power errors or unfavorable astigmatism, while p pow and p ast corresponds to the penalty function.

[0188] P pow The following definition:

[0189] p pow (X,α,β)={k·|PowerError(X,α,β)-δ pow |0if{|PowerError(X,α,β)|≥δ pow otherwise

[0190] P ast The following definition:

[0191] p Ast (X, α, β) = {k′·|UnwantedAstigmatism(X, α, β)-δ Ast |0if{|PowerError(X,α,β)|≥δ Ast otherwise

[0192] The penalty can be a quadratic penalty. In this way, the focal penalty function is as follows:

[0193] p pow(X,α,β)={k·(PowerError(X,α,β)-δ pow ) 2 Oif {|PowerError(X, α, β)|≥δ pow otherwise

[0194] The quadratic penalty function for adverse astigmatism is as follows:

[0195] p Ast (X,α,β)={k′·(UnwantedAstigmatism(X,α,β)-δ Ast ) 2 0 if {|PowerError(X, α, β)|≥δ Ast otherwise

[0196] k and k' are parameters that will be adjusted depending on the wearer's sensitivity.

[0197] Advantageously, in a similar manner to the weight optimization function, the penalty function enables optimization in an area around a specific gaze direction. Said optimization of the intermediate lens means that the optimization of the lens in a specific area (i.e. the area around a given specific gaze direction) is according to an optical criterion and ensures that the difference between the optical criterion value of the optimized lens and the target value is equal to or less than a threshold. In this way, said penalty function enables optimization according to a given optical criterion, taking into account the wearer's specific sensitivity parameters with respect to the optical criterion in a specific area of ​​the lens (which is the area of ​​the lens most used).

[0198] At the end of the intermediate optical lens determination step S2, the optical lens includes a sufficiently large area around the specific gaze direction centered on the specific gaze direction, where the difference between the optical criterion value of the optimized initial lens and the target value is equal to or less than a threshold.

[0199] The determination method comprises an optical lens determination step S3. During the optical lens determination step S3, the optical lens is determined by optimizing the intermediate optical lens. The optimization aims to obtain a maximum gaze direction area around a specific gaze direction, wherein the difference between the value of the optical criterion and the target value is less than or equal to a threshold value. The optimization can be obtained by optimizing at least one surface of the intermediate optical lens.

[0200] The method aims to provide a maximum gaze direction area corresponding to the wearer's prescription and the wearer's wearing conditions, wherein around a specific gaze direction, the difference between the value of the optical criterion and the target value is less than or equal to a threshold value.

[0201] The area to be enlarged corresponds to an area around a specific gaze direction, which can be a main gaze direction, in which the difference between the value of the optical criterion and the target value is less than or equal to a threshold. This area can also be defined as a set of gaze directions around the specific gaze direction, in which the difference between the value of the optical criterion and the target value is less than or equal to a threshold.

[0202] Advantageously, the optimization method is able to enlarge the gaze direction region that is suitable for the wearer's prescription and the wearer's wearing conditions for given optical parameters, taking into account the wearer's sensitivity with respect to the optical parameters.

[0203] The optic determination step S3 , which corresponds to the optimization of the intermediate optic, can be obtained by applying the second layer onto the surface of the intermediate optic.

[0204] The second layer may be applied to the first layer applied in the intermediate optic determination step S2.

[0205] The second layer may be a Zernike layer.

[0206] In an embodiment, both the first layer and the second layer may be Zernike layers. In the case where the first layer and the second layer are Zernike layers, there is no implicit order relationship between the first Zernike layer and the second Zernike layer. The first Zernike layer and the second Zernike layer may have the same order.

[0207] Preferably, when the second layer is a Zernike type layer, the second layer to be applied has a low order. In a preferred embodiment, the order may be less than or equal to 10, preferably less than or equal to 7, even more preferably less than or equal to 5.

[0208] Derivative-free optimization can be achieved by using low-order Zernike layers. Derivative-free optimization tends to be complex in high dimensions.

[0209] In an embodiment, the derivative-free optimization corresponds to the Nelder-Mead algorithm. This algorithm facilitates its implementation.

[0210] In another embodiment, methods such as CMA-ES may also be used. CMAE-ES is a derivative-free evolutionary algorithm for minimizing nonlinear, non-convex functions. It is very suitable for merit functions that are non-differentiable or difficult to obtain derivatives and / or computationally expensive.

[0211] In an embodiment, the frame and the optical lens fixed on the lens may have an elliptical shape. The ellipse E is composed of parameters (r, r * a) Definition. r defines the semi-major axis, and a * r defines the semi-minor axis. According to the (α, β) reference system, the ellipse is centered at (0,0). Da(r) corresponds to a set of all points included in the ellipse E. Da(r) is defined as follows:

[0212]

[0213] Da(r * ) is the maximum Da(r) included in a set of gaze directions that meet the standard threshold. In the embodiment described, the third optimization step S3 aims to expand the number of gaze directions defined by Da(r * ) defined by .

[0214]

[0215] r * According to the parameters X, δ pow and δ ast , is defined by the maximum radius Da(r) where, for a given point of the set, the difference between the value of the optical criterion and the target value is less than or equal to the threshold. This maximum radius r * is determined based on the variable r, and the parameters x, δ pow and δ ast are predefined parameters.

[0216] The second optimization can directly maximize r * .

[0217] The goal is to find at least one lens variable, preferably a set of variables that make r * Maximize the lens variables so that:

[0218]

[0219] The optical lens determination step S3 can be performed using derivative-free optimization to directly maximize r * .

[0220] In the above example, the lens has an elliptical shape, the lens may also have a circular shape, using the same maximum radius formula to determine the maximum radius of the circular boundary of the area to be optimized.

[0221] In another embodiment, the shape of the frame and the optical lens can be rectangular. In this case, the optimization of the area to be enlarged is based on a similar transformation. Advantageously, the area to be optimized on the lens depends on the final shape of the optical lens to be installed. The optimization should not be located in an area that will not be used later. Therefore, the optimization should be performed in such a way that the optimized area is present in the remaining optical lens to be fitted on the frame. In this way, the gaze direction area has a shape that depends on the glasses frame. Preferably, the optimized area of ​​the lens is controlled according to the shape of the frame (more particularly, the opening of the frame designed to accommodate the optimized lens) and the main gaze direction.

[0222] The method consists of two different optimization steps.

[0223] A first optical lens, namely an intermediate optical lens, is determined according to a first optimization. The first optimization comprises defining a portion of the intermediate lens, wherein the difference between the value of at least a given optical criterion of the intermediate optical lens and a target value of a gaze direction around a specific gaze direction is less than or equal to a threshold value.

[0224] The method comprises determining a second optical lens different from the intermediate optical lens based on a second optimization, i.e. an optimization of the intermediate lens, wherein the second optimization aims to enlarge a gaze direction zone around a specific gaze direction, wherein the difference between at least the value of a given optical criterion and a target value around the specific gaze direction is less than or equal to a threshold value determined for the intermediate optical lens.

[0225] The method according to the present invention may include a manufacturing step S4 to manufacture the optical lens optimized in step S3.

[0226] Figures 7 to 10 Power and adverse astigmatism diagram corresponding to the Tchernin spherical lens and the optimized optical lens.

[0227] The parameters of the spherical lens are:

[0228] -prescription

[0229] ο spherical power = -8D,

[0230] ο cylindrical power = 0D,

[0231] - and a front surface radius of 303mm

[0232] Figure 7 shows the power diagram and adverse astigmatism diagram of the Czernin spherical lens, and Figure 8 The power diagram and adverse astigmatism diagram of the optimized optical lens are shown, where δ pow =0.06D and δ ast = 0.25D. The Chernin spherical lens has a spherical front surface and a spherical back surface. The curvature of the front surface and thus the back surface is changed to obtain the maximum r for a given optical criterion threshold * , while retaining the prescription at the reference point. The obtained Tchernin lens is not suitable as a product due to its high base and thickness.

[0233] exist Figure 7 and Figure 8 In the embodiment shown, the r of the Chernin lens * The value is 27.6°. The optimized intermediate lens r * The value of is 23.4°, and the quadratic penalty optimization is adopted. And the optimized optical lens r * The value of is 29.8°. If the original spherical lens with a front surface radius of 303mm is used, then r* will be only 14.9°.

[0234] Fig. 9 shows the power diagram and adverse astigmatism diagram of a spherical lens, and Fig.10 The power diagram and adverse astigmatism diagram of the optimized optical lens are shown, where δ pow =0.25D and δ ast =0.06D.

[0235] exist Fig. 9 and Fig.10 In the embodiment shown, the r of the Chernin lens * The value of the lens r is 27.8° for the intermediate optimized lens * The value of is 26.5°, and the weighted cost function is used for optimization. And the optimized optical lens r * The value of is 34.2°. If the original spherical lens with a front surface radius of 303mm is used, then r * will be only 9.3°.

[0236] Figures 11 to 14 Power and adverse astigmatism diagram corresponding to single vision spherical lenses and optimized optical lenses.

[0237] The parameters of the spherical lens are:

[0238] -prescription

[0239] οSpherical power = +7D

[0240] οCylinder power = 0D

[0241] - and a front surface radius of 66 mm.

[0242] Fig.11 shows the power diagram and adverse astigmatism diagram of a spherical lens, and Fig.12 The power diagram and adverse astigmatism diagram of the optimized optical lens are shown, where δ pow =0.06D and δ ast =0.25D.

[0243] exist Fig.11 and Fig.12 In the embodiment shown, the r of the Chernin lens * The value is 24.6°. The optimized intermediate lens r * The value of is 22.0°, and the weighted cost function is used for optimization. And the optimized optical lens r * The value of is 28.3°. If the original spherical lens with a front surface radius of 66mm is used, then r * will be only 10.6°.

[0244] Fig.13shows the power diagram and adverse astigmatism diagram of a spherical lens, and Fig.14 The power diagram and adverse astigmatism diagram of the optimized optical lens are shown, where δ pow =0.25D and δ ast =0.06D.

[0245] exist Fig.13 and Fig.14 In the embodiment shown, the r of the Chernin lens * The value of is 23.9°. The intermediate optimized lens r * The value of is 20.4°, and the weighted cost function is used for optimization. And the optimized optical lens r * The value of is 32.8°. If the original spherical lens with a front surface radius of 66mm is used, then r * will only be 10.6°

[0246] Fig.15 and Fig.16 Power and adverse astigmatism diagrams corresponding to Tchernin-based single vision lenses and optimized optical lenses.

[0247] The prescription is Sph = -4D / Cyl = -2D / Axis = 0°. The lens tilt angle is -8°. The front surface radius is 193mm

[0248] Fig.15 shows the power and adverse astigmatism diagrams of a lens based on Tchernin, and Fig.16 The power diagram and adverse astigmatism diagram of the optimized optical lens are shown, where δ pow =0.06D and δ ast = 0.06D. The Tchernin-based lens has the same front surface as the optimized optical lens. The Tchernin-based lens has a complex back surface that is optimized to match the optical performance of a spherical Tchernin lens.

[0249] exist Fig.15 and Fig.16 In the embodiment shown, the r of the lens based on Chernin * The value of is 13.1°. The optimized intermediate lens r * The value of is 11.8°, and the weighted cost function is used for optimization. And the optimized optical lens r * The value of is 17.8°. If an initial spherical toric lens with a front surface radius of 193 mm is used, then r * will be only 3.1°

[0250] Fig.17 and Fig.18 Power and adverse astigmatism diagrams corresponding to Tchernin-based single vision lenses and optimized optical lenses.

[0251] The prescription is Sph = -6D; Cyl = -2D; and Axis = 0°. The radius of the front surface of the lens is 303 mm.

[0252] Fig.17 shows the power and adverse astigmatism diagrams of a lens based on Tchernin, and Fig.18 The power diagram and adverse astigmatism diagram of the optimized optical lens are shown, where δ pow =0.06D and δ ast =0.06D.

[0253] exist Fig.17 and Fig.18 In the embodiment shown, the r of the toric lens based on Chernin's * The value is 9°. The optimized intermediate lens r * The value of is 10.6°, and the weighted cost function is used for optimization. And the optimized optical lens r * The value of is 14.8°. If an initial spherical toric lens with a front surface radius of 303 mm is used, then r * will be only 2.5°.

[0254] Fig.19 and Figure 90 correspond to power and adverse astigmatism diagrams for a Tchernin-based single vision lens and an optimized optical lens.

[0255] The prescription is Sph = +2D; Cyl = -4D; and Axis = 0°. The front surface radius is 112 mm.

[0256] Fig.19 shows the power and adverse astigmatism diagrams of a lens based on Tchernin, and Fig. 20 The power diagram and adverse astigmatism diagram of the optimized optical lens are shown, where δ pow =0.06D and δ ast =0.06D.

[0257] exist Fig.19 and Fig. 20 In the embodiment shown, the r of the lens based on Chernin * The value is 15°. The optimized intermediate lens r * The value of is 14.3°, and the weighted cost function is used for optimization. And the optimized optical lens r * The value of is 20.3°. If an initial spherical toric lens with a front surface radius of 112 mm is used, then r * will be only 5.1°

[0258] The present disclosure has been described above by means of embodiments without limiting the general inventive concept.

[0259] Numerous further modifications and variations will be apparent to those skilled in the art upon reference to the foregoing illustrative embodiments, which are presented by way of example only and are not intended to limit the scope of the present disclosure, which is to be determined solely by the appended claims.

[0260] In the claims, the word "comprising" does not exclude other elements or steps and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage. Any reference signs in the claims shall not be construed as limiting the scope of the disclosure.

Claims

1. A method implemented by a computer device for determining an optical lens suitable for a wearer and optimized for at least a given optical criterion having a target value around a specific gaze direction, the method comprising: - obtaining an initial optical lens having a prescription for the wearer under given wearing conditions in a specific gaze direction; - determining an intermediate optical lens by optimizing the initial optical lens using an optimization function, so that the intermediate optical lens includes a gaze direction area around the specific gaze direction for which a difference between a value of at least a given optical criterion of the intermediate optical lens and a target value of a gaze direction around the specific gaze direction is less than or equal to a threshold value; - The optical lens is determined by optimizing the intermediate optical lens to expand a gaze direction area where the difference between the value of at least a given optical criterion of the intermediate optical lens and the target value of the gaze direction around the specific gaze direction is less than or equal to a threshold value, thereby obtaining a maximum gaze direction area around the specific gaze direction where the difference between the value of at least a given optical criterion of the optical lens and the target value around the specific gaze direction is less than or equal to the threshold value.

2. The method according to claim 1, wherein: The initial optical lens has a prescription of the wearer for a given object distance under given wearing conditions in the specific gaze direction, when the intermediate optical lens is determined, the initial optical lens is optimized for the object distance, and when the optical lens is determined, the intermediate optical lens is optimized for the object distance.

3. The method according to claim 1, wherein: The at least given optical criterion is optical power or astigmatism or acuity or distortion.

4. The method according to claim 1 or 2, wherein: The specific gaze direction is a primary gaze direction.

5. The method according to claim 1 or 2, wherein: The optimization function used when determining the intermediate optic comprises a weighted cost function depending on the gaze direction, wherein the weight decreases when the angle formed by the gaze direction and the specific gaze direction increases.

6. The method according to claim 1 or 2, wherein: The optimization function comprises a penalty function which is added to the optimization function used when determining the intermediate optical lens to ensure that within a defined gaze direction area around the specific gaze direction, the difference between the value of at least a given optical criterion of the intermediate optical lens and a target value around the specific gaze direction is less than or equal to the threshold.

7. The method according to claim 1 or 2, wherein: The intermediate optical lens is determined by optimizing at least one surface of the initial optical lens.

8. The method according to claim 1 or 2, wherein: The intermediate optic is determined by adding a Zernike layer to at least one surface of the initial optic.

9. The method according to claim 8, wherein: The order of the Zernike layer is greater than or equal to 4.

10. The method according to claim 1 or 2, wherein: The optical lens is determined by optimizing at least one surface of the intermediate optical lens.

11. The method according to claim 1 or 2, wherein: The optical lens is determined by adding a Zernike layer to at least one surface of the intermediate optical lens.

12. The method according to claim 1 or 2, wherein: The optimization of the intermediate optic comprises a derivative-free optimization.

13. The method according to claim 1, wherein: The gaze direction area around the specific gaze direction is centered on the specific gaze direction.

14. The method according to claim 1, wherein: The gaze direction region around the specific gaze direction has a shape of a spectacle frame selected by the wearer, and a size of the gaze direction region around the specific gaze direction is controlled using a homothetic transformation of the shape of the spectacle frame.

15. The method according to claim 1 or 2, wherein: The thresholds may be standard or customized depending on the wearer.

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