Method for determining the value of a global sensitivity parameter of an object, method for using this value and system for determining said value - Patents.com

Abstract

The present invention provides a method for determining values ​​of global sensitivity parameters (Sgsph, Sgcyl, Sgaxis, Sgasr, SgJ0, SgJ45, Soverall) of a subject, said global sensitivity parameters relating to the sensitivity of said subject to changes in at least one refractive optical characteristic of at least an ophthalmic lens placed in front of at least one eye of said subject, said method comprising the following steps: a) determining a single value of at least a first sensitivity parameter of said subject relative to the sensitivity of said subject to changes in a first refractive optical characteristic of at least a first ophthalmic lens ( The present invention relates to a method for determining a global sensitivity parameter (120) using a calculation means, the method comprising the steps of: a) determining (110) a single value of at least a second sensitivity parameter for a subject relative to the subject's sensitivity to changes in a second refractive optical characteristic of at least a second ophthalmic lens, the single value of at least a second sensitivity parameter being associated with a minimum change in the first and second refractive optical characteristic, respectively, that can be perceived by the subject; and b) determining (120) using a calculation means, the value of a global sensitivity parameter taking into account a combination of the single values ​​of the first and second sensitivity parameters. The present invention also relates to a method for using this value and a system for carrying out this method.

Description

[Technical field]

[0001] The present invention relates to a method for determining the value of a global sensitivity parameter of an object.

[0002] The present invention also relates to a method for determining the optical characteristics of an ophthalmic lens adapted to improve the visual acuity of a subject, a method for informing an eye care practitioner of the value of the subject's global sensitivity parameter, a method for selecting a suitable optical design of an ophthalmic lens adapted to improve the visual acuity of a subject and a method for modifying a given optical design of an ophthalmic lens, taking into account this value of the global sensitivity parameter of said subject, in order to adapt it to the visual acuity of the subject.

[0003] The invention also relates to a system for carrying out this method. [Background technology]

[0004] US Patent No. 5,399,633 describes a method for determining a single value of a specific sensitivity parameter of one eye of a subject, the single specific sensitivity parameter being related to the sensitivity of the subject's eye to changes in a specific optical characteristic of a lens placed in front of this eye.

[0005] This single particular sensitivity parameter relates to the smallest change in a particular optical characteristic that can be perceived by a subject.

[0006] In practice, it may be defined as the range of values ​​of a particular optical characteristic that may be acceptable or beyond which the subject cannot determine whether a deviation is better.

[0007] The single value of a particular sensitivity parameter determined for different particular optical features, such as sphere, cylinder or axis, addition, etc., and for each eye of a subject, may be different. Furthermore, the determined single value may face measurement uncertainties.

[0008] Therefore, based on the single values ​​of these specific sensitivity parameters, it is not possible to infer general information about the subject's sensitivity to errors in determining the corresponding optical characteristics of a lens adapted to improve this subject's vision, or to optical aberrations of a lens having optical characteristics adapted to improve this subject's vision. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2018 / 015381 Brochure [Patent Document 2] US Patent Publication No. 20160331226 [Patent Document 3] US Patent Publication No. 2017027435 [Patent Document 4] International Publication No. 2017 / 021663 Brochure [Patent Document 5] PCT / EP Patent Application Publication No. 2018 / 061207 [Non-patent literature]

[0010] [Non-Patent Document 1] "Influence of Combined Power Error and Astigmatism on Visual Acuity" by FAUQUIER C., BONNIN T., MIEGE C., and ROLAND E.. Ophthalmic and Visual Optics Technical Digest, (Optical Society of America, Washington, DC), Vol. 1, p. 151-154, 1995. [Non-Patent Document 2] "Unaided Visual Acuity and Blur: A Simple Model" by Ralf Blendowske or "Phenomenological model of visual acuity" by Jose A. Gomez-Pedrero Summary of the Invention [Problem to be solved by the invention]

[0011] It is therefore one object of the present invention to provide a method for determining a reliable value of a global sensitivity parameter that provides a global assessment of a subject's sensitivity to changes in at least the optical characteristics of at least one ophthalmic lens. [Means for solving the problem]

[0012] By reliable we mean that the values ​​of the global sensitivity parameters are a better representation of the sensitivity of the subject: they are more reproducible.

[0013] The above object is achieved according to the present invention by providing a method for determining a value of a global sensitivity parameter of a subject, said global sensitivity parameter relating to the sensitivity of said subject to changes in at least a refractive optical characteristic of at least an ophthalmic lens placed in front of at least one eye of said subject, said method comprising the following steps: a) determining a single value of at least a first sensitivity parameter of a subject relative to a sensitivity of said subject to a change in a first refractive optical characteristic of at least a first ophthalmic lens; b) determining a single value of at least a second sensitivity parameter of the subject relative to the sensitivity of the subject to changes in a second refractive optical characteristic of at least a second ophthalmic lens, each of the first and second sensitivity parameters being associated with a minimal change in the first and second refractive optical characteristics, respectively, that can be perceived by the subject; c) using calculation means to determine said value of a global sensitivity parameter taking into account a combination of said single values ​​of the first and second sensitivity parameters; Includes.

[0014] The value of the global parameter so determined is more reliable for assessing the sensitivity of the subject than the single values ​​of the first and second sensitivity parameters. - the global sensitivity of one eye to changes in one or more optical characteristics of one lens placed in front of this eye, under the same or different environmental conditions; - the global sensitivity of both eyes to independent changes in one or more optical characteristics of each lens placed in front of one eye, under the same or different environmental conditions; - global sensitivity of both eyes to changes in one or more optical characteristics of two lenses placed in front of both eyes under the same or different environmental conditions It may reflect either

[0015] In the last case, the change may be absolute or relative, a change in the corresponding optical characteristics of both lenses respectively or a change in the difference between the optical characteristics of both lenses.

[0016] The value of the global sensitivity parameter can be taken into account throughout the processing chain: determining the refraction, determining the best next visual test to suggest to the subject during the refraction test protocol, prescribing the required correction, manufacturing and / or edging / finishing at the optician up to delivery, as a tolerance during adjustment of the frame on the subject's head and finally can be used to advise update / visual check frequency.

[0017] When selecting the frames, the values ​​of the global sensitivity parameters may also be taken into consideration by selecting appropriate pantoscopic angles, wrap angles, etc.

[0018] For patients with difficult challenges (amblyopia, high dominance, anisometropia, etc.), this provides a decision aid to eye care practitioners to give patients the prescription that best suits their particular challenges.

[0019] Other advantageous, but non-limiting, features of the method according to the invention are as follows: - the at least first and second sensitivity parameters determined in steps a) and b) - spherical sensitivity to a change in the sphere of said at least first or second ophthalmic lens for at least one eye of said subject; - cylinder and / or axis sensitivity to changes in cylinder and / or axis of said at least first or second ophthalmic lens for at least one eye of a subject; - the subject's spherical binocular sensitivity to binocular changes in the sphere of the first and second ophthalmic lenses; - the subject's binocular balance sensitivity to changes in the binocular balance of the first and second ophthalmic lenses; - an add power sensitivity to a change in add power of said at least first or second ophthalmic lens for at least one eye of a subject; Each of the following includes at least one of - the single values ​​of at least a first and a second sensitivity parameter determined in steps a) and b) are determined using different measurement methods or under similar or different measurement conditions, - in step c), the combination comprises an average of the single values ​​of the first and second sensitivity parameters determined during steps a) and b), the single values ​​of the first and second sensitivity parameters determined during steps a) and b) - a single value of the cylinder sensitivity (ScylOG, ScylOD) for each of the left and right eyes, or - a single value of the axial sensitivity for each of the left and right eyes (SaxisOG, SaxisOD), or - a single value of the astigmatism sensitivity (Sasr, SJ0, SxJ0, SJ45, SxJ45) for each of the left and right eyes, - Single values ​​of spherical, cylindrical, axial and binocular balance sensitivity for the left eye (SsphOG, ScylOG, SaxisOG, Seqbino) and one for the right eye (SsphOD, ScylOD, SaxisOD, Seqbino) and In step c), the determined global sensitivity parameter values ​​are: - a value of the global cylinder sensitivity parameter (Sgcyl) equal to the average of the single values ​​of the cylinder sensitivities of the left and right eyes, or - a value of the global axis sensitivity parameter (Sgaxis) equal to the average of the single values ​​of the axis sensitivities of the left and right eye, or - the value of the global sensitivity parameters (SgOG, SgOD) of the left or right eye, which is equal to the average of the single values ​​of the sphere, cylinder, axis and binocular balance sensitivity of the left or right eye; and - during steps a) and b), a single value of the spherical sensitivity (SsphOG, SsphOD) of each of the left and right eyes of the subject and a single value of the spherical binocular sensitivity (Sphbino) of said subject are determined, and in step c) the value of the determined global sensitivity parameter is a value of the global spherical sensitivity parameter (Sgsph) which is equal to the average value of the single values ​​of the spherical sensitivity and of the spherical binocular sensitivity of the left and right eyes, - during steps a) and b) the following: - a single value of the spherical sensitivity (SsphOD, SsphOG) for each of the left and right eyes, and - a single value of the cylinder sensitivity (ScylOD, ScylOG) for each of the left and right eyes, and - a single value of each axial sensitivity (SaxisOD, SaxisOG) for the left and right eye, and - the value of the spherical binocular sensitivity (Ssphbino) of the subject, and - the subject's binocular balance sensitivity (Seqbino) value is determined, and In step c), the value of the final global sensitivity parameter Sgfinal is calculated according to the following formula: Soverall=[(SsphOD+SsphOG+Ssphbino) / 3+(ScylOD+ScylOG) / 2+(SaxOD+SaxOG) / 2+Seqbino] / 4 It is determined by - in step c), the combination comprises a weighted average of the single values ​​of the first and second sensitivity parameters determined during steps a) and b), the weights associated with the values ​​of the first and second sensitivity parameters being - The subject's normal visual behavior, and / or - the type of lenses worn by the subject, and / or - the activity the subject wishes to have with the lens; and / or - Ocular dominance data, and / or - Comfort assessment of current / previous lenses worn by the subject, and / or - Data presented in previous prescriptions for optical correction devices Depends on - displaying this value of the global sensitivity parameter for notification to an eye care practitioner, - during steps a) and b) a value of the binocular balance sensitivity of the subject is determined, and in step c) a final global sensitivity parameter value is determined as the average value of the global spherical sensitivity parameter value, the global cylindrical sensitivity parameter value and the global axial sensitivity parameter value and the binocular balance sensitivity value, - in step c), the combination of values ​​of the first and second sensitivity parameters comprises a weighted average of the values ​​of the first and second sensitivity parameters determined during steps a) and b); and - the weight is higher for values ​​of the parameter for the subject's dominant eye than a weight associated with values ​​of the parameter for the subject's non-dominant eye, or if the subject is a progressive lens subject, said weighting of the cylindrical and axial sensitivity values ​​of each eye is higher than the weighting associated with the spherical sensitivity values ​​of each eye.

[0020] The present invention also relates to a method for determining adapted optical characteristics of an ophthalmic lens adapted to improve a subject's vision at near, intermediate and / or far distances, the method comprising the following steps: - a test protocol, - repeating the steps of placing a test lens in front of the subject's eye; - an iterative step of evaluating the quality of a subject's vision viewing through said test lens, the value of a refractive optical characteristic of the test lens being increased by an incremental value between each iteration of said step; - an iterative step of comparing the quality of the subject's vision looking through at least two successive test lenses placed in front of the subject's eye during two successive iterations of said steps of the test protocol and determining said adapted refractive optical characteristics based on this comparison; - an iterative step of determining values ​​of a global sensitivity parameter of interest according to the method described above; - an iterative step of determining said increment value taking into account this value of the global sensitivity parameter; performing a test protocol comprising: Includes.

[0021] Optionally, said increment value is determined so as to minimise the difference between said increment value and the value of the global sensitivity parameter.

[0022] The present invention also relates to a method for selecting a suitable optical design for an ophthalmic lens adapted to improve the visual acuity of a subject from among a list of predefined optical designs, said optical designs comprising current values ​​of at least one refractive optical characteristic of a corresponding lens having said predefined optical design, associated with a plurality of gaze directions of the subject when the lens is worn by said subject, the method comprising the following steps: - determining values ​​of the global sensitivity parameters of the object according to the method described above, - determining a fitting value of said refractive optical characteristics adapted to improve the visual acuity of a subject; - determining, for different gaze directions, the difference between the current value of the refractive optical characteristic of the corresponding lens and the adapted value of said refractive optical characteristic, - comparing this difference with the value of the global sensitivity parameter of interest; - selecting an appropriate optical design from said list of predefined optical designs taking into account this comparison. Includes.

[0023] This method is - determining an area of ​​the given optical design where the difference is less than a value of a global sensitivity parameter of interest; - selecting an appropriate optical design by selecting an optical design that has an area of ​​larger size in at least one predetermined direction and / or has a shape that is closer to the predetermined shape. It may further include.

[0024] The present invention also relates to a method of modifying a predefined optical design for an ophthalmic lens in order to adapt it to the visual acuity of a subject, said optical design comprising current values ​​of at least one refractive optical characteristic of a corresponding lens having said predefined optical design, associated with a plurality of gaze directions of a subject when said lens is worn by said subject, the method comprising the steps of: - determining values ​​of the global sensitivity parameters of the object according to the method described above, - determining a fitting value of said refractive optical characteristics adapted to improve the visual acuity of a subject; - determining, for several gaze directions, the difference between the current value of the refractive optical characteristic of the corresponding lens and the adapted value of said refractive optical characteristic, - comparing this difference with the value of the global sensitivity parameter of interest; - determining a modified optical design for a modified corresponding lens by modifying said predetermined optical design of the lens in view of the comparison. Includes.

[0025] This method is - determining an area of ​​the given optical design where the difference is less than a value of a global sensitivity parameter of interest; - determining a modified optical design such that modified regions of the modified optical design, in which the difference is smaller than a value of the global sensitivity parameter of interest, are larger compared to a size of said regions in the predetermined optical design and / or have a shape closer to a predetermined shape. It may further include.

[0026] The present invention also relates to a system for determining a value of a global sensitivity parameter of a subject, said global sensitivity parameter relating to the sensitivity of said subject to changes in at least a refractive optical characteristic of at least an ophthalmic lens placed in front of at least one eye of said subject, said system comprising: - means for determining a single value of at least a first sensitivity parameter of a subject relative to a sensitivity of said subject to a change in a first refractive optical characteristic of at least a first ophthalmic lens; - means for determining a single value of at least a second sensitivity parameter of the subject relative to a sensitivity of said subject to a change in a second refractive optical characteristic of at least a second ophthalmic lens; - computing means programmed to determine said value of a global sensitivity parameter taking into account a combination of said single values ​​of the first and second sensitivity parameters. Includes.

[0027] The present invention relates to - means for storing said values ​​of the global sensitivity parameters determined by the calculation means, and / or - means for displaying said value of the global sensitivity parameter determined by the calculation means; It may further include.

[0028] The following description, enriched with accompanying drawings to be taken as non-limiting examples, will serve to understand the invention and how it can be put into practice. [Brief description of the drawings]

[0029] [Figure 1] FIG. 2 is a block diagram illustrating generally the steps for determining a global sensitivity parameter according to an example of the method of the present invention; [Diagram 2] 1 is a graph of a certainty probability function of a subject versus the value of an optical feature used to determine a single value of a particular sensitivity parameter. [Diagram 3] 11A-11C illustrate different ways of displaying the values ​​of different global sensitivity parameters. [Figure 4] 11A-11C illustrate different ways of displaying the values ​​of different global sensitivity parameters. [Diagram 5] 11A-11C illustrate different ways of displaying the values ​​of different global sensitivity parameters. [Figure 6] 11A-11C illustrate different ways of displaying the values ​​of different global sensitivity parameters. [Figure 7] 1 is a schematic diagram of three different standard predetermined optical designs for a lens. [Figure 8] 1 is a graph showing the mean power, sagittal power, and tangential power of a monofocal ophthalmic lens as a function of the visual acuity angle for a subject having a standard predetermined optical design. [Figure 9] 1 is a graph showing the mean, sagittal and tangential powers of a monofocal ophthalmic lens as a function of subject vision angle, with an optical design modified for a subject with high global sensitivity to spherical changes and low global sensitivity to cylindrical changes. [Figure 10] 1 is a graph showing the mean, sagittal and tangential powers of a monofocal ophthalmic lens as a function of subject vision angle, with an optical design modified for a subject with high global sensitivity to cylindrical changes and low global sensitivity to spherical changes. [Figure 11] 1 is a graph showing the mean power, sagittal power, and tangential power as a function of subject vision angle for a monofocal ophthalmic lens with an optical design modified for a subject with high global sensitivity to cylindrical and spherical changes. [Figure 12]Graph showing the mean power, sagittal power and tangential power as a function of vertical visual acuity angle alpha (also called vertical deviation gaze angle) for subjects of multifocal ophthalmic lenses with optical designs modified for subjects with low (dashed and thin solid lines) or high (dotted and thick solid lines) global acuity. [Figure 13] 13 is a graph showing the same mean power lines for lenses having the optical design of FIG. 12, where the optical design has been modified for subjects having low (dashed line) or high (solid line) global acuity. [Figure 14] 13 is a graph showing the same unwanted astigmatism lines for a lens having the optical design of FIG. 12, the optical design being modified for subjects having low (dashed line) or high (solid line) global sensitivity. [Figure 15] 1 shows the decomposition of lens cylinder and axis values ​​on a J0, J45 vector basis. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Fig. 1 shows a schematic block diagram of the steps performed according to one embodiment of a method for determining a value of a global sensitivity parameter of at least one eye of a subject, said global sensitivity parameter relating to the sensitivity of said subject to changes in at least an optical characteristic of an ophthalmic lens.

[0031] The optical characteristics considered include, in particular, the refractive characteristics of the lens or lenses measured in diopters. The optical characteristics include, in particular, optical powers such as sphere, cylinder, astigmatism, addition, binocular balance, binocular surface, etc.

[0032] The global sensitivity parameter may relate to the sensitivity of the subject to a change in one particular optical characteristic of a lens, such as sphere or cylinder or axis or add power, for one eye of the subject, a change in only one particular optical characteristic of a lens, such as sphere or cylinder or axis or add power, for both eyes of the subject, or a binocular change in one particular optical characteristic of two lenses, such as the binocular value of sphere or the binocular balance of the sphere of two lenses, for both eyes of the subject.

[0033] Global sensitivity parameters may relate to the sensitivity of a subject to changes in different specific optical characteristics of a single lens, such as sphere, and / or cylinder, and / or axis, and / or add power, for the same eye of the subject, changes in different specific optical characteristics of a single lens, such as sphere, and / or cylinder, and / or axis, or add power, for each eye of the subject, or binocular changes in different specific optical characteristics of two lenses, such as the binocular value of sphere, or the binocular balance of the sphere of two lenses, for both eyes of the subject.

[0034] The first and second sensitivity parameters may be determined by different measurement methods or may be determined under similar or different measurement conditions.

[0035] In one embodiment, the global sensitivity parameter may relate to the sensitivity of the subject to changes in at least two different optical characteristics with respect to only one eye of the subject, or may relate to the sensitivity of the subject to changes in at least one optical characteristic taking into account each eye of the subject.

[0036] The method for determining the value of this global sensitivity parameter of an object according to the invention comprises the following steps: a) determining a single value of at least a first sensitivity parameter of a subject relative to a sensitivity of said subject to a change in a first refractive optical characteristic of at least a first ophthalmic lens (block 100 of FIG. 1 ); a) determining a single value of at least a second sensitivity parameter of a subject relative to a sensitivity of the subject to changes in a second refractive optical characteristic of at least a second ophthalmic lens (block 110 of FIG. 1 ), each of the first and second sensitivity parameters being associated with a minimum change in the first and second refractive optical characteristic, respectively, that can be perceived by the subject; c) using computational means to determine said value of a global sensitivity parameter taking into account a combination of said single values ​​of the first and second sensitivity parameters (block 120 of FIG. 1 ); Includes.

[0037] Steps a) and b) can be performed by the same or different means. Each of these steps can be performed on the same day or at different times. The determination of the single value of the sensitivity parameter can be based on a measurement or on a look-up of a previously determined value, as will be explained later. The method can include a step of transmitting the values ​​determined in steps a) and b) to a computational means which performs step c).

[0038] In the following, the optical characteristics of the lenses are refractive optical characteristics, as will be explained hereinafter.

[0039] The method is: - storing said value of the global sensitivity parameter determined by the calculation means, and / or - displaying said values ​​of the global sensitivity parameters determined by the calculation means. It may further include.

[0040] Steps a) and b) Each of the first and second sensitivity parameters relates to a minimum change in said first and second refractive optical characteristics, respectively, that can be perceived by a subject.

[0041] Each of the first and second sensitivity parameters is - related to a particular sensitivity of said subject to a change in one of the optical characteristics of the lens, said change being perceived in one eye of the subject, or - related to a particular sensitivity of said subject to a change in one of the optical characteristics of the two lenses, said change being perceived by both eyes of the subject.

[0042] More precisely, the at least first and second sensitivity parameters determined in steps a) and b) are - spherical sensitivity to a change in the sphere of said at least first or second ophthalmic lens for at least one eye of said subject; - cylinder and / or axis sensitivity to changes in cylinder and / or axis of said at least first or second ophthalmic lens for at least one eye of a subject; - the subject's spherical binocular sensitivity to binocular changes in the sphere of the first and second ophthalmic lenses; - the subject's binocular balance sensitivity to changes in binocular balance between the first and second ophthalmic lenses; - an add power sensitivity to a change in add power of said at least first or second ophthalmic lens for at least one eye of a subject; Each of the above includes at least one of the following:

[0043] Further, optionally, the at least first and second sensitivity parameters determined in steps a) and b) are determined with different measurement methods, respectively, or under similar or different measurement conditions, respectively.

[0044] Methods for determining a single value of a particular sensitivity parameter for one eye of a subject are known and are described in US Pat. No. 5,399,633.

[0045] During the complete process of refraction, each single value of a particular sensitivity parameter is measured for each eye, as described in this document.

[0046] More precisely, each particular sensitivity parameter for one eye of the subject represents the minimum change in a corresponding particular optical characteristic of a lens placed in front of this eye of the subject, as perceived by the subject, based on the subject's subjective evaluation.

[0047] In practice, the subject's visual acuity is tested during a test protocol using a phoropter, which allows lenses differing in value of said particular optical characteristic to be placed in succession in front of the subject's eye.

[0048] This testing protocol can be accomplished using a classic phoropter or a phoropter with two complex lenses of variable power.

[0049] In a classical phoropter, different lenses with fixed, predetermined powers can be placed in succession in front of each eye of a subject. For example, lenses of different spheres are placed in succession in front of one eye of a subject. The sphere increases in a predetermined step from one lens to the next. This step is usually 0.25 diopters (D) or 0.125D.

[0050] The test protocol may also use modified phoropters that include lenses of variable power. Such phoropters / variable lenses are described, for example, in US Pat. Nos. 5,993,333, 5,993,421, 5,993,512, and 5,993,623.

[0051] For each current lens placed in front of the subject's eye, the subject is asked to rate the quality of their vision through the current lens compared to the previous lens and, from the two presented visual conditions, is asked to either correspond to an indication of a preferred visual condition or express a visual evaluation in which they are unable to decide between the two visual conditions.

[0052] In practice, this step corresponds, for example, to the assessment given by the subject during the duochrome test, during which the subject is presented with an image containing, on the one hand, an index displayed on a red background and, on the other hand, an index displayed on a green background. If the subject sees the index on the red background better, the sphere should be decreased, and if the index shown on the green background is better, the sphere should be increased.

[0053] As a variant, for each current lens placed in front of the subject's eye, the subject is asked to rate the quality of their vision through the current lens compared to the previous lens, asking whether the current lens makes them see better or worse than the previous lens, or whether they cannot decide between the two. In this last case, the two lenses provide the subject with similar vision quality.

[0054] Subject responses can be collected by different means, e.g., tactile means, verbal means, by mouse, ball mouse, track pad, continuous potentiometer, etc. These means can be performed by the subject themselves or by an eye care professional.

[0055] The value of a particular sensitivity parameter corresponding to this optical characteristic of the lens represents the minimum difference in said particular optical characteristic at which a subject may perceive a difference in the quality of the image seen by said eye while viewing through lenses with different values ​​of said particular optical characteristic.

[0056] As shown in Fig. 2, a single value of a particular sensitivity parameter SRx can be determined, for example, as half the width of a zone of change in optical characteristics in which a subject is insensitive to changes in the values ​​of the optical characteristics of a lens placed in front of his or her eye. This zone corresponds to a range of values ​​of the optical characteristics that the subject can tolerate or in which the subject cannot determine which lens provides better vision.

[0057] The value of each particular sensitivity parameter is, for example, evaluated as a probability function of the certainty of the subject's answer.

[0058] An example of a subject's certainty probability function or certainty function is shown in Figure 2 (see Figure 2) as a graph of the certainty of a choice made by the subject as a function of the optical feature value of the lens placed in front of the eye.

[0059] The certainty probability function reflects a subject's certainty when making a choice between two visual states (e.g., visual acuity against a red or green background) or between two different lenses placed in succession in front of the eyes.

[0060] A value of 0% certainty is obtained when the subject cannot choose between the two visual conditions or the two lenses, i.e. when the subject cannot perceive any difference in the quality of the image seen in each visual condition (e.g. red or green background) or through each of the two lenses. A value of -100% certainty is obtained when the subject is certain that the first of the two visual conditions (e.g. a visual target on a red background) improves the quality of the image seen or that the first lens improves the quality of the image seen, and a value of 100% certainty is obtained when the subject is certain that the second visual condition (e.g. a visual target on a green background) or the second lens improves the quality of the image seen.

[0061] The example of FIG. 2 shows a certainty probability function determined as a function of the diopter, e.g., spherical optical characteristic, of a lens placed in front of one eye of a subject.

[0062] A method for determining the certainty probability function is known from document WO 2018 / 015381.

[0063] In fact, the better the quality of the image, - When evaluating lenses with different spheres, cylinders or axes, for example the Jackson cross cylinder procedure, does the target appear sharper? - In the duochrome test, can you see the colors clearly between red and green? - In the case of the Jackson Cross test using a fixed Jackson Cross cylinder, the vertical or horizontal direction of the image is clearer, - Top or bottom position for binocular balance The subject's response may be evaluated based on the following:

[0064] In this last case, the vision of each eye is separated by a polarizer or prism or any other known means, so that one eye sees the upper part of the image (for example the letters in the top line) and the other eye sees the lower part of the image. The wearer can then compare both parts of the image (upper and lower) to find the best balance between the two eyes, which is the difference in the value of the sphere between the two eyes.

[0065] A subject's particular choice is considered, along with answers of values ​​-1 and +1, and zero answers of "don't know" and "same." Any uncertain answers can be represented by a value between 0 and 1 depending on the estimated or measured certainty. A certainty function is calculated by averaging all the estimated answers for a particular optical feature value. The certainty function is then interpolated to any non-estimated values.

[0066] The insensitive zone is defined corresponding to values ​​of the optical characteristic of the lens for which the probability of certainty is included in a predefined range of uncertainty. The extremes of this predefined range of uncertainty may consist of 20% to 80% on one side and -20 to -80% on the other side.

[0067] Examples of uncertainty ranges are the ranges [-20%, 20%], [-30%, 30%], [-40%, 40%], [-50%, 50%], [-60%, 60%], [-70%, 70%] or [-80%, 80%].

[0068] The value of the particular sensitivity parameter of the subject is then defined to be equal to half the size of the zone of non-response. The theoretical value Rx of the optical characteristic fitted to the subject can be any value of the optical characteristic included in the range of uncertainty, in particular the value corresponding to a value of 0% certainty.

[0069] Optical features for which a particular sensitivity can be assessed in the above-mentioned manner include, for example: - Spherical, also called spherical power, - Cylinder, also known as cylinder power and / or axis or a combination thereof, - astigmatism, defined as a combination of cylindrical and axial - addition powers used, for example, in progressive lenses, bifocal lenses or single vision lenses for near vision, - Binocular, - Binocular balance It is.

[0070] All of these optical characteristics can be given in diopters. Conventional methods for determining these optical characteristics are well known to those skilled in the art. These conventional methods as well as the improved methods according to the present invention described below can be used.

[0071] The sphere corresponds to the refractive power of the lens given in diopters by the spherical components of the shape of the front and back surfaces of the lens.

[0072] Cylinder corresponds to the refractive power of the lens given in diopters by the cylindrical components of the front and back surface shapes of the lens.

[0073] The axis corresponds to the orientation of the cylindrical component of the lens shape.

[0074] The cylinder power and axis represent the cylinder component of the ophthalmic lens determined to compensate for the astigmatism of the subject's eye. The present invention uses a vector decomposition of the cylinder component instead of being determined in a standard polar form with a magnitude and orientation decomposition as described in the applicant's US Pat. No. 5,399,633.

[0075] Vector decomposition of the cylindrical components is performed, for example, according to two orthogonal directions J0, J45, as shown in FIG.

[0076] For example, the decomposition along the two J0, J45 directions corresponds to replacing the classical sphero-cylindrical notation (sphere S, cylinder C, axis) by a triplet of orthogonal values ​​(S, J0, J45) defined as an astigmatic decomposition of polar astigmatism (C, axis) as a spherical lens of power S and two Jackson cross cylinder lenses, one with axis 0° and power J0=(-C / 2)*cos(2*axis) and the other with axis 45° and power J45=(-C / 2)*sin(2*axis).

[0077] In FIG. 15, the first cylinder component is represented by a vector V1 in polar coordinates with standard Cylinit and an angle equal to twice the axis 2xAxeInit.

[0078] Vector V2 is an example of the final correction that was tested.

[0079] To come closer to the standard Jackson cross cylinder procedure, the two orthogonal directions may correspond to the initial astigmatism direction and its perpendicular direction, as shown in FIG. 15. Each component of the decomposition is expressed in diopters, making it possible to define and measure two corresponding sensitivities. The component Jx0 determined along the initial astigmatism direction is associated with the cylindrical power component, and the perpendicular component Jx45 is associated with the axial component. In the following, cylindrical and axial will refer to this definition.

[0080] Addition can be defined as the difference in sphere between distance and near vision, for example between the distance and near vision zones of a progressive lens.

[0081] It is known that after determining the spherical and cylindrical components of the correction required by the subject, it may be necessary to adjust the binocular balance of the eye. In order to achieve a comfortable correction of the subject's eye, it is certainly useful to ensure that the quality of the image seen through the fitted lens with the determined fitted sphere is similar.

[0082] The determination of the value of the sphere of the lens fitted to each eye of the subject may not in practice be performed exactly for both eyes. It is then useful to compare the quality of the image seen by each eye with the corresponding fitted lens with the fitted sphere by known methods that allow separation of the image seen by each eye, such as using two polarizers oriented at 90°, one of these polarizers being placed in front of each eye. If one of the determined fitted lenses provides a better image than the other, the sphere of this lens can be modified to make the quality of the image seen by the subject similar.

[0083] The corresponding optical characteristic may then be equal to the difference between the spheres of both lenses.

[0084] The corresponding optical characteristic may also be equal to the difference between the spacing between the spheres of both lenses initially determined before the binocular balance test and the spacing between the spheres of both lenses after the binocular balance test.

[0085] The certainty function may be determined as a function of either one of these optical features. No-response zones may be identified and the values ​​of the subject's particular sensitivity parameters to binocular balance adjustments may be determined in a manner similar to that described above.

[0086] After adjusting the binocular balance, the binocular spheres can be adjusted. Based on the previously determined sphere values, for example after the binocular balance test, the spheres of both lenses are changed simultaneously by the same increment and the quality of binocular vision is evaluated by the subject. The subject is then asked to compare the quality of the images seen when both spheres are changed.

[0087] The corresponding optical characteristic of each lens or of the two lenses may then be equal to the difference between the sphere originally determined before the binocular testing and the sphere determined after the binocular testing, and the corresponding sensitivity parameter relates to the subject's sensitivity to this adjustment.

[0088] A certainty function can be determined as a function of this optical characteristic. Non-responsive zones can be identified and values ​​of the subject's particular sensitivity parameters to binocular accommodation can be determined in a manner similar to that described above.

[0089] The different single values ​​of the at least first and second sensitivity parameters may be determined in steps a) and b) using different measurement methods.

[0090] Different single values ​​of the at least first and second sensitivity parameters may be determined in steps a) and b) under similar or different measurement conditions.

[0091] For example, a single value of the first and / or second sensitivity parameters may be determined at different viewing distances or for the same viewing distance.

[0092] Thus, a single value of a particular sensitivity parameter may relate to the subject's sensitivity to said first and / or second optical features of one lens or two lenses in distance, intermediate or near vision conditions, and may relate to a particular measurement condition such as phoropter ergonomics: pantoscopic angle, phoropter wrap angle, etc.

[0093] A single value of the first and / or second sensitivity parameter may be determined in different light conditions.

[0094] Thus, a single value of a particular sensitivity parameter may relate to a subject's sensitivity to said first and / or second optical features of one lens or two lenses in daylight vision, low light vision or night vision conditions.

[0095] Other environmental conditions that affect the subject's visual capabilities may also be taken into account.

[0096] Step c) In step c), said combination of said single values ​​of the first and second sensitivity parameters typically comprises a linear or non-linear combination, for example a quadratic combination, of some or all of the single values ​​of the first and second sensitivity parameters.

[0097] The global sensitivity parameter is, for example, an average value of several single values ​​of the specific sensitivity parameters. The global sensitivity parameter can be a weighted average value of several single values ​​of the specific sensitivity parameters.

[0098] In one embodiment, in step c), said combination of said single values ​​of the first and second sensitivity parameters comprises an average value of the single values ​​of the first and second sensitivity parameters determined during steps a) and b).

[0099] For example, several single values ​​of the same particular sensitivity parameter are determined, i.e. for the same optical characteristics of the same eye or two eyes and lens or two lenses, under the same environmental conditions, and the average of these single values ​​is determined.

[0100] In one embodiment, such a global sensitivity parameter may be, for example, the mean spherical sensitivity SmphOD, SmsphOG of the right or left eye obtained by averaging several single values ​​SphOD, SphOG of the spherical sensitivity parameter of the right or left eye, - the mean binocular spherical sensitivity Smsphbino, the mean cylindrical sensitivity SmcylOD, SmcylOG of the right or left eye, obtained by averaging several single values ​​of the spherical sensitivity parameter ScylOD, ScylOG of the right or left eye, the mean axial sensitivity SmaxisOD, SmaxisOG of the right or left eye obtained by averaging several single values ​​SaxisOD, SaxisOG of the spherical sensitivity parameter of the right or left eye, or - Average sensitivity of the eyes to binocular balance Smeqbino It is.

[0101] These averages are averaged to provide greater reliability than a single value.

[0102] In another embodiment, the single values ​​of the first and second sensitivity parameters determined during steps a) and b) are - a single value of the cylinder sensitivities ScylOD, ScylOG for the left and right eye, respectively, or - a single value of the axis sensitivities SaxisOD, SaxisOG for the left and right eye respectively, or - Single values ​​of spherical, cylindrical, axial and binocular balance sensitivities SsphOD, ScylOD, SaxisOD, SsphOG, ScylOg, SaxisOG, Seqbino for the left and right eye and In step c), the determined global sensitivity parameter values ​​are: - a value of the global cylindrical sensitivity parameter (Sgcyl) equal to the average of the single values ​​of the cylindrical sensitivities of the left and right eye: Sgcyl = (ScylOD + ScylOG) / 2, or - a value of the global axis sensitivity parameter (Sgaxis) equal to the average of the single values ​​of the axis sensitivities of the left and right eye: Sgaxis=(SaxisOD+SaxisOG) / 2, or - value of the global sensitivity parameters (SgOG, SgOD) for the left or right eye, equal to the average of the single values ​​of the sphere, cylinder, axis and binocular balance sensitivity for the left eye only or the right eye only: SgOG=SsphOG+ScylOG+SaxisOG+Seqbino) / 4 SgOD=SsphOD+ScylOD+SaxisOD+Seqbino) / 4 It is.

[0103] These global sensitivity parameters are particularly relevant to one eye of a subject. They are particularly useful, for example, when the sensitivity of each eye is very different, for example, when the correction needs or visual capabilities (visual acuity) of each eye are very different, or when unilateral dominance is critical.

[0104] Alternatively, during steps a) and b), single values ​​of the spherical sensitivities SsphOG, SsphOD of the left and right eyes of the subject, respectively, and a single value of the spherical binocular sensitivity (Sphbino) of said subject are determined, and - in step c), the value of the global sensitivity parameter determined is the value of the global spherical sensitivity parameter Sgsph which is equal to the average value of the single values ​​of the spherical sensitivities SsphOG, SsphOD of the left and right eye and the binocular spherical sensitivity Ssphbino: Sgsph=(SsphOG+SsphOG+Ssphbino) / 3.

[0105] Sphericity is usually the parameter to which a subject is most sensitive, but may also vary greatly due to accommodation variations. Therefore, determining the value of such a global spherical sensitivity parameter may be advantageous to assess a subject's sensitivity to spheres.

[0106] The overall sensitivity taking into account all the above sensitivities and the average sensitivity of the eye for binocular balance Sgeqbino can be defined as equal to the average of the global spherical sensitivity Sgsph, the global cylindrical sensitivity Sgcyl, the global axial sensitivity Sgaxis and the average sensitivity of the eye for binocular balance Sgeqbino, Soverall=(Sgsph+Sgcyl+Sgaxis+Sgeqbio) / 4.

[0107] The values ​​obtained for the right and left eye and the main optical characteristics of the lens are averaged.

[0108] Other similar global sensitivity parameters that take into account the sensitivity of each eye are - another global spherical sensitivity, equal to the average value of the mean spherical sensitivities SmsphOD, SmsphOG of the right or left eye and the mean binocular spherical sensitivity Smsphbino, - another global cylinder sensitivity SmcylOD, SmcylOG, equal to the average of the mean cylinder sensitivities of the right or left eye, - Another global axis sensitivity SmaxisOD equal to the average of the mean axis sensitivities of the right or left eye It can be determined as:

[0109] Of course, the overall sensitivity can be calculated directly based on a single value of a particular parameter or based on an average of the single values, without calculating intermediate average values; Soverall=[(SsphOD+SsphOG+Ssphbino) / 3+(ScylOD+ScylOG) / 2+(SaxisOD+SaxisOG) / 2+Seqbino] / 4, or Smoverall=[(SmsphOD+SmsphOG+Smsphbino) / 3+(SmcylOD+SmcylOG) / 2+(SmaxisOD+SmaxisOG) / 2+Smeqbino] / 4 It is.

[0110] Another global sensitivity parameter to the astigmatism taking into account cylinder and axis, Sgasr, can be defined as Sgasr=(Sgcyl+Sgaxe) / 2.

[0111] With the definition of cylinder and axis in diopters, these optical characteristics can be denoted as J0 or Jx0 and J45 or Jx45 and Sgasr can be expressed as the average of the single values ​​of sensitivity for the components of cylinder J0 or Jx0 and J45 or Jx45 or the average of the average sensitivity for J0 or Jx0 and J45 or Jx45: Sgasr=(SJ0+SJ45) / 2 or Sgasr=(SJx0+SJx45) / 2 or Sgasr=(SmJ0+SmJ45) / 2.

[0112] The values ​​of the global cylindrical components J0 and J45 or Jx0 and Jx45, sensitivity parameters SgJ0, SgJ45 or SgJx0, SgJx45, which are equal to the average of the single values ​​of the cylindrical components J0 and J45 or Jx0 and Jx45 sensitivities of the left and right eye, can also be defined as SgJ0=(SJ0OD+SJ0OG) / 2 and SgJ45=(SJ45OD+SJ45OG) / 2 or SgJx0=(SJx0OD+SJx0OG) / 2 and SgJx45=(SJx45OD+SJx45OG) / 2.

[0113] Of course, the corresponding global sensitivities can be determined using any of the base vectors J0, J45, Jx0, Jx45 mentioned above.

[0114] Global sensitivity can also be defined for only SgOD in the right eye or SgOG in the left eye, SgOD=(SgsphOD+SgcylOD+SgaxisOD+SgeqbioOD) / 4, SgOG=(SgsphOG+SgcylOG+SgaxisOG+SgeqbioOG) / 4 It is.

[0115] Tests based on the overall sensitivity parameter values ​​showed that subjects with higher sensitivity were more likely to select the correct lens and see benefits and differences better than the overall population.

[0116] The tests also showed that the more sensitive the subjects were, the less “having no choice” they were and the more likely they were to choose the more accurate lens, i.e. the more the subjects perceived the benefit of precision, thus validating the reliability of the overall sensitivity parameters.

[0117] The global sensitivity parameters, especially the overall sensitivity parameters, may also represent the sensitivity to aniseikonia, i.e. differences in retinal image size.

[0118] The values ​​of the global sensitivity parameters are determined as follows: - Estimation of sensitivity to aniseikonia, - subjective and / or objective determination of the sensitivity to sphere and / or cylinder and / or axis and / or addition and / or binocular surface and / or binocular balance, for example taking into account accommodation; - Comparison based on realistic scenes may also be included.

[0119] In another embodiment, in step c), the combination of the single values ​​of the first and second sensitivity parameters comprises a weighted average value of the single values ​​of the first and second sensitivity parameters determined during steps a) and b).

[0120] The weights associated with the single values ​​of the first and second sensitivity parameters can be, for example, - The subject's normal visual behavior, and / or - the type of lenses worn by the subject, and / or - the activity the subject wishes to have with the lens; and / or - Ocular dominance data, and / or - Comfort assessment of current / previous lenses worn by the subject, and / or - Data presented in previous prescriptions for optical correction devices may depend on.

[0121] This is represented diagrammatically in FIG.

[0122] The weight taken into account may, for example, be higher for a single value of a particular sensitivity parameter associated with a subject's dominant eye than for a single value of a particular sensitivity parameter associated with a subject's non-dominant eye.

[0123] Other normal behaviors of the subject to be considered may include, for example, eye-head coordination, eye-hand or eye-foot coordination, hand or foot dominance (preference), walking behavior, eye-moving / head-moving behavior.

[0124] In a variant or in addition, if the subject is a progressive lens subject, the weights are higher for a single value of cylindrical sensitivity for each eye than the weights associated with a single value of spherical sensitivity for each eye.

[0125] The weights may also be associated with activities typically performed by the subject, such as reading, watching television, driving, static activities, dynamic activities or practicing sports involving movement using a smartphone or tablet or computer.

[0126] Reading using a smartphone or tablet means using a higher weight for the sensitivity parameters determined for near vision, and using a computer or watching television means using a higher weight for the sensitivity parameters determined for intermediate vision.

[0127] The weight taken into account to determine the global sensitivity parameter may also be higher for optical features of lenses for which the subject reported having fitting problems with previous ophthalmic devices, e.g., complaints about distortion or that the field of view is not wide enough may be taken into account.

[0128] For example, if the subject complains about near vision, a higher weight may be used for the add power or near vision sensitivity, if the subject complains about distortion, a higher weight may be used for cylinder sensitivity, if the subject complains about the fit of the previous device, a higher weight may be used for the refractive parameter that changed the most with the new device, etc.

[0129] Alternatively, the combination weights can be determined based on a visual acuity model.

[0130] For example, according to Le Grand's visual acuity model, as published in "Sur le calcul des verres de lunetterie" by Le Grand Y., Revue d'Optique, Paris, (1966), the ratio between the refractive error associated with the astigmatism of the eye and the refractive error associated with the sphere is equal to √2 / 2.

[0131] Therefore, the global sensitivity parameters can be defined as Swoverall_1=(Sgsph+√2 / 2Sgcyl) / 2 or Swoverall_2=(Sgsph+√2 / 2Sgasr) / 2, using the notation defined previously.

[0132] By way of another example, data on the measurement of visual acuity obtained by Sloan and published by Sloan L.L., Arch. Ophtalmol. 45, (6), 704-725, (1951), show that the ratio between the refractive error associated with the astigmatism of the eye and the refractive error associated with the sphere is equal to 0.8 for visual acuity greater than 20 / 28.

[0133] Therefore, the global sensitivity parameters can be defined as Swoverall_3=(Sgsph+0,8Sgcyl) / 2 or Swoverall_4=(Sgsph+0,8Sgasr) / 2, using the notations Sgsph and Sgasr defined previously.

[0134] According to yet another example, the decrease in relative visual acuity VA%, i.e. the decrease in visual acuity of a subject with spherical error DPPO and astigmatic residual error ASR, compared to the visual acuity of a subject with a perfectly corrected eye, is: VA%=100-63.DPPO-44.3.ASR+7.2.DPPO in a non-presbyopic subject. 2 +19,5.DPPO.ASR+ASR 2 It can be determined as:

[0135] This formula can be used when DPPO is positive or equal to zero.

[0136] In this formula, the quantities DPPO and ASR quantify the optical effect of the difference between the subject's eye and the perfect eye. Thus, the quantities DPPO and ASR correspond to the values ​​of sphere, cylinder, and axis of a corrective lens fitted to the subject.

[0137] This formula can be extended to presbyopic patients by determining the residual subjective accommodation as a function of age and ergonomics, as described in Non-Patent Document 1.

[0138] The corresponding global sensitivity parameter is Swoverall_5=63*Sgsph+44.3*Sgasr-7.2*Sgsph 2 -19.5*Sgsph*Sgasr-Sgasr 2 It can be calculated as:

[0139] In a common method, if a criterion P for evaluating monocular visual ability is calculated as P=m.DPPOa+n.ASRb (where m, n>=0, and a and b are included in 0 to 2), the global sensitivity parameter Swoverall_i is calculated as Swoverall_i=m.Sgsph using the aforementioned Sgsph and Sgasr global sensitivity parameters. a +n.Sgasr b It can be evaluated as:

[0140] Visual acuity models are known from various documents, for example from "Visual Acuity Models for Vision Imaging" by Robert J. Schneider, "Visual Acuity Models for Vision Imaging," Journal of Visual Acuity and Vision, Vol.

[0141] More specifically, it is proposed here to consider a particular visual acuity model developed by the applicant, according to which visual acuity follows Swaine's law for very small values ​​of DPPO and / or ASR errors, for example DPPO or ASR below 0.5 D, Gomez's law for small errors of DPPO and / or ASR, for example comprised between 0.5 and 1.75 D, and Blendoswke's law for higher levels of errors.

[0142] The invention also relates to a system for determining said values ​​of the global sensitivity parameters Sgsph, Sgcyl, Sgaxis, Sgasr, SgJ0, SgJ45, Soverall of an object, the system comprising: - means for determining a single value of at least a first sensitivity parameter of a subject, for said subject's sensitivity to a change in a first optical characteristic of at least a first ophthalmic lens; - means for determining a single value of at least a second sensitivity parameter of the subject relative to the sensitivity of said subject to a change in a second optical characteristic of at least a second ophthalmic lens; - computing means programmed to determine said value of a global sensitivity parameter taking into account a combination of said single values ​​of the first and second sensitivity parameters. Includes.

[0143] The means for determining said single values ​​of the first and second sensitivity parameters may be the same or different means. These means may, for example, comprise the aforementioned phoropter coupled to an analysis means programmed to analyze the subject's responses to the aforementioned test protocol. This analysis means may be integrated in the phoropter or may be an independent analysis means. In this last case, the analysis means comprises a communication module adapted to receive data from the phoropter.

[0144] The means for determining a single value of at least a first sensitivity parameter of the subject may also include input means for inputting a single value retrieved from a previous test. It may also include communication means adapted to receive said value.

[0145] This system is - means for storing said values ​​of the global sensitivity parameters determined by the calculation means, and / or - means for displaying said value of the global sensitivity parameter determined by the calculation means; Further includes.

[0146] The means for storing the value may include a memory or a local or remote server. The means for displaying may include a screen or any type of display, whether integrated in the phoropter or not.

[0147] The value of the subject's global sensitivity parameter thus determined may be taken into account in many different steps of the process of providing a corrective device adapted to improve the subject's vision, using any of the possible formulas and methods described above.

[0148] The determined value of the global sensitivity parameter provides practically reliable information about the subject's perception of the difference between two different devices, thus assisting the subject and the eye care practitioner in determining the characteristics of the corrective device that best suits the subject at a better cost.

[0149] Determining the refraction or providing lenses with a higher accuracy than the subject's global sensitivity is practically useless, since the subject will not be able to distinguish any difference between lenses that have a refractive difference smaller than the value of the global sensitivity parameter.

[0150] The present invention therefore also relates to a method for informing an eye care practitioner of a value of a global sensitivity parameter of a subject, said global sensitivity parameter relating to the sensitivity of said subject to changes in at least an optical characteristic of at least an ophthalmic lens placed in front of at least one eye of said subject, said method comprising the following steps: - determining values ​​of at least a global sensitivity parameter of the object according to any of the methods described above, - displaying this value of the global sensitivity parameter for notification to the eye care practitioner. Includes.

[0151] Such methods may also assist eye care practitioners in optimizing testing protocols for determining the refraction of the fellow eye.

[0152] It may also help eye care practitioners recommend frames based on values ​​such as pantoscopic and wrap angles.

[0153] An eye care practitioner can then take into account the values ​​of the global sensitivity parameters to determine refraction and / or to prescribe an appropriate lens, as described below.

[0154] For the global sensitivity parameters, different types of displays may be taken into consideration.

[0155] Global sensitivity is displayed as a field size on a target and can be used to assess the match between the subject's exact refraction and the final correction of the lens provided to the subject.

[0156] An example of such targets 10, 20 is shown in Fig. 3. The larger target 10 represents the global sensitivity value of a first subject, and the smaller target 20 represents the global sensitivity value of a second subject, which is more sensitive than the first. In this example representation, the abscissa is a sphere and the ordinate is a cylinder, the center of the target is placed at the refraction values ​​(S1, C1), (S2, C2) determined for one eye of the subject, and the inner rings 11, 21 of the targets 10, 20 are positioned so as to be spaced from the center of the target 12, 22 by the value of the global sensitivity parameter of the subject.

[0157] As a variant, the abscissa and ordinate can give the value of any optical characteristic for which the sensitivity of the object can be determined.

[0158] The shape of the inner ring of the target may also be different. In the example shown, the values ​​of the global sensitivity parameters are the same on the abscissa and ordinate since both spheres and cylinders are considered.

[0159] The target may also consider two different global sensitivity parameter values, e.g., a spherical global sensitivity and a cylindrical global sensitivity, in which case an elliptical ring can be used instead of a circular ring if the subject has different sensitivities to spheres and cylinders.

[0160] Thus, the target zone located inside the inner ring gives the range of possible values ​​of the optical characteristics of the lens, plotted on the abscissa and ordinate, for which the subject perceives perfect visual correction.

[0161] Using this representation, it is possible to overlay targets representing the subject's global sensitivity with symbols 30, 40, 50, 60 representing the values ​​and accuracy of the corresponding optical characteristics of the lens that will actually be provided to the subject based on the refraction determined by conventional refraction techniques.

[0162] The symbols 30, 40, 50, 60 are arranged on the display with the same regularity for the abscissa and ordinate. A central area 31, 41, 51, 61 of the symbols 30, 40, 50, 60 is centred at the coordinates corresponding to the optical characteristic of the lens, the size of this central area 31, 41, 51, 61 corresponding to the precision of the value of the optical characteristic of the lens.

[0163] This makes it possible to calculate a matching score related to the probability that the lens offered to the subject will have optical features located in the inner zone of the inner ring 11, 21 of the target 10, 20, and therefore provide an instrument in which the subject will perceive perfect visual correction.

[0164] This is done, for example, by calculating the area of ​​the inner ring of the target that is covered by the central region of the code.

[0165] In the example of figures 4 and 5, the symbols 30, 40, 50, 60 are central disks 31, 41, 51, 61 with radial branches 32, 42, 52, 62. The matching score is calculated as a function of the area of ​​the inner zone of the inner ring 11, 21 of the target 10, 20 covered by the central disk 31, 41, 51, 61 of the symbol 30, 40, 50, 60.

[0166] The example of Fig. 4 shows a case where the refraction of the subject is determined with low accuracy, and therefore the lenses offered based on this determination are also low accuracy, for example this is the case for a refraction determined with an accuracy of 0.25 diopters.

[0167] In this case, 95% of the central disks 31 of reference 30 are located inside the inner ring 11 of the target 10, which means that for a first subject with a low global sensitivity corresponding to the larger target 10, there is a 95% probability of obtaining a lens that can provide a value of refraction and therefore a complete visual correction of this first subject. On the contrary, only 15% of the central disks 41 of reference 40 are located inside the inner ring 21 of the smaller target 20, which means that for a second subject with a high global sensitivity corresponding to the smaller target 20, there is a 15% probability of obtaining a lens that can provide a value of refraction and therefore a complete visual correction of this first subject.

[0168] The example of Fig. 5 shows the case where the refraction of the subject is determined with high accuracy, and therefore the lenses offered based on this determination are also highly accurate, for example this is the case for a refraction determined with an accuracy of 0.01 diopters.

[0169] In this case, 100% of the central disks 51, 61 of the reference numbers 50, 60 are located inside the inner rings 11, 21 of the targets 10, 20, which means that for both the first and second subjects there is a 100% probability of obtaining a refractive value and therefore a lens capable of providing complete visual correction for these first and second subjects.

[0170] Of course, many other shapes can be used to generally represent the target and / or the symbol.

[0171] Currently, visual acuity is primarily considered to assess whether a lens will have a beneficial effect on improving a subject's visual acuity and to predict whether a subject will be satisfied with the prescription. When an eye care practitioner is faced with the decision to favor or penalize an eye when prescribing, the decision is primarily based on visual acuity.

[0172] Now, by calculating the value of the subject's global sensitivity parameter, the eye care practitioner may be informed of this value, thereby assisting the eye care practitioner in deciding which eye to prioritize when deciding and prescribing lenses. Particular consideration may be given to the value of the global sensitivity parameter of the dominant or most sensitive eye.

[0173] Up until now, visual acuity measurements alone have been used to help eye care practitioners decide which eye should be prioritized. Sometimes visual acuity is similar in both eyes, e.g., there is little change in prescription, and fitting a subject to new equipment can be difficult and time-consuming.

[0174] Here, the eye care practitioner may take care to prescribe modifications limited to the prescription of the most sensitive eye, especially if it corresponds to the dominant eye or otherwise clearly warns the patient of the possible longer term indication.

[0175] Taking into account the values ​​of the global sensitivity parameters of a subject, it is possible to determine the appropriate precision of the refraction to be measured and / or the lens to be prescribed for this subject.

[0176] A method of prescribing a lens to improve the vision of a subject may in fact comprise the steps of determining a value for the global sensitivity parameter as described above and prescribing a lens adapted to the subject taking this value into account.

[0177] In a second step, lenses can be prescribed with values ​​that are as accurate as the values ​​of the global sensitivity parameters.

[0178] Prescribing values ​​with a higher precision than the values ​​of the global sensitivity parameters is of no practical use, and prescribing values ​​with a lower precision than the values ​​of the global sensitivity parameters may not produce satisfactory results.

[0179] No changes to the previous recipe should be made if they are less than the value of the global sensitivity parameter, rather, any changes that are greater than the value of the global sensitivity parameter should be made.

[0180] However, when sensitivity is high due to potential difficulties in adaptation, eye care practitioners should avoid very high (usually greater than 3-5 times the sensitivity) changes.

[0181] Thus, information relating to the values ​​of the global sensitivity parameters may assist eye care practitioners in prescribing.

[0182] As will be explained later, the value of the global sensitivity parameter can also be used during refraction to adjust the refraction process accordingly in real time.

[0183] Regarding the display of the values ​​of the different global sensitivity parameters, they can be displayed in a sensitivity map.

[0184] The sensitivity map of the subject is adapted to be taken into consideration to provide assistance for prescribing a lens and / or to suggest or modify the lens optical design.

[0185] The sensitivity map of the subject can be easily compared to the reference sensitivity map.

[0186] For example, in Figure 6, a subject's sensitivity map 2 is compared to a reference sensitivity map 1. Reference sensitivity map 1 is a sensitivity map obtained, for example, by averaging the values ​​of the global sensitivity parameters determined for each individual in a given population.

[0187] As already mentioned, the value of the global sensitivity parameter of the subject can be taken into account while determining the refraction of the subject's eye.

[0188] As mentioned above, the value of the global sensitivity parameter is determined during the steps normally performed to determine the refraction of the subject's eye, and can then be taken into account during this determination, either in real time or after refraction.

[0189] The present invention therefore also relates to a method for determining adapted optical characteristics of an ophthalmic lens adapted to improve the visual acuity of a subject, the method comprising the following steps: - a test protocol, - repeating the steps of placing a test lens in front of the subject's eye; - an iterative step of evaluating the quality of a subject's vision when viewing through said test lens, the value of an optical characteristic of the lens being increased by an incremental value between each iteration of said step; - an iterative step of comparing the quality of the subject's vision looking through at least two successive lenses placed in front of the subject's eye during two successive iterations of said steps of the test protocol and determining said adapted optical characteristics based on this comparison; - an iterative step of determining values ​​of at least a global sensitivity parameter of the object according to the method described above, - an iterative step of determining said increment value taking into account this value of the global sensitivity parameter; performing a test protocol comprising: Includes.

[0190] The test protocols are standard procedures well known to those skilled in the art and may be carried out, for example, by using a phoropter.

[0191] Different types of phoropters may be used: phoropters using lenses with variable optical characteristics, such as lenses with variable spherical power, as described in particular in US Pat. No. 5,399,623 and US Pat. No. 5,499,633; and classical phoropters using multiple lenses of different powers may also be used.

[0192] A test protocol typically begins with a predetermined value of an optical characteristic, such as the optical characteristic of a previous vision correction device or an objective value determined with an autorefractometer.

[0193] The step of determining the value of the global sensitivity parameter may be performed during the same test protocol or during a previously executed test protocol.

[0194] In the first case, the test protocol may be initially run using the standard increment value while the value of the global sensitivity parameter is being determined, and the steps of the test protocol may be repeated once again using the increment value determined to determine the refraction of the subject's eye, after which the increment value is adjusted in real time.

[0195] In the second case, the value of the global sensitivity parameter is associated with the subject's data, stored in memory, and then used to determine the increment value prior to running the test protocol.

[0196] More precisely, said increment value is determined so as to minimize the difference between this increment value and the value of the global sensitivity parameter.

[0197] This allows the determination of an exact value of the refraction, which is accurate enough to ensure that a lens is determined that provides the best possible correction for the subject, close to perfect vision, and avoids determining the refraction with an unnecessarily high accuracy, since a higher accuracy than the value of the global sensitivity parameter does not lead to any further improvement in vision, but which may have practical drawbacks, such as a longer determination time for the subject.

[0198] Accuracy is defined here as the difference between the value of refraction determined by the method and the actual current refraction of the subject's eye.

[0199] During a typical testing protocol to determine the refractive characteristics of a lens fitted to correct a visual defect of a subject's eye, one of the refractive characteristics of the test lens is gradually decreased or increased, the starting point often being the refractive characteristics of the subject's previous device (if any) or an objective measurement from an autorefractometer.

[0200] As described above in connection with the determination of the value of the global sensitivity parameter, when a lens having the current optical characteristics is placed in front of the subject's eye, the subject is asked to rate the quality of vision through the current lens compared to the previous lens and, from two presented visual states, is asked to indicate either a preferred visual state indicator or a visual assessment in case he or she is unable to decide between the two visual states.

[0201] In practice, this step corresponds to the rating given by a subject during a duochrome test or when comparing two different lenses.

[0202] The subject then indicates their answer, for example "I see it better on the red background", "I see it better on the green background" or "I see it better with either the first lens or the second lens".

[0203] In case of an answer of "I don't know", i.e. in case the subject is unable to choose between the two visual conditions or the two lenses, the usual protocol skips this step and continues the test protocol by presenting another duochrome test with another optical feature of the lens or another optotype reading with another lens.

[0204] Typically, the sphere, cylinder or axis is changed when moving to the next step in the same way as before, i.e., by increasing the sphere, cylinder or axis of the lens when it was previously increased, or decreasing the sphere, cylinder or axis of the lens when it was previously decreased.

[0205] However, to control the adjustment of a subject, it may be useful to test new values ​​from both sides and / or to start from a given side of the one currently being tested.

[0206] When testing distance visual acuity, it is indeed important to try to minimize the subject's accommodation during the test.

[0207] When testing the sphere required by the subject's eye, it is then useful to test a new value of positive sphere rather than a value that would result in an answer of "I don't know", as this answer may indicate that the current value of sphere is close to the appropriate value or that the subject is accommodating.

[0208] If the subject believes that their vision would be worse at this more positive value of sphere, then the appropriate value of sphere is halfway between them (so the next value of sphere is decreased). If the subject further answers "I don't know" or believes their vision is improving, continue the testing protocol by increasing the sphere.

[0209] When testing other optical features, such as cylinder and axis, new values ​​of the optical features that constitute the values ​​that result in the answer "I don't know" are tested, especially if the answer "I don't know" is the first answer given at the beginning of the test.

[0210] When testing the subject's near vision, accommodation is maximized. This process is mirrored from that of distance vision. When testing sphere, more negative values ​​are tested after the answer "don't know". The sphere to be tested is then decreased until there are no more "don't know" answers. The value of sphere is then finally increased.

[0211] A similar process applies to a cylinder or axis, especially if the initial answer is "I don't know."

[0212] A test protocol for determining the optical characteristics of a lens fitted to a subject may also be customized according to the subject and / or according to the habits or desires of the eye care professional performing it.

[0213] For example, the test protocol is customized as a function of the historical data available to the subject, for example as a function of the value of the subject's global sensitivity parameter, as a function of the subject's visual impairment (such as myopia), as a function of the optical characteristics of the subject's current device, or as a function of the subject's age. In the case of children, for example, tests in near vision conditions are not performed.

[0214] The present invention also relates to a method for selecting a suitable optical design of an ophthalmic lens adapted to improve the visual acuity of a subject from a list of predefined optical designs, said optical designs including a current value of at least one optical characteristic of the corresponding lens associated with a plurality of gaze directions of the subject when the lens is worn by said subject, by taking into account the value of at least one global sensitivity parameter.

[0215] Said list of predefined optical designs includes different optical designs, e.g. different power layouts or astigmatism layouts or vision layouts as a function of the subject's gaze direction in the wearing state, all of which are adapted to the visual correction required by the subject, e.g. adapted to the subject's refraction.

[0216] A predetermined optical design is selected from the list of predetermined optical designs to minimize a gap between at least one optical characteristic of a lens having this selected predetermined optical design and a target optical characteristic determined taking into account the subject's sensitivity to this optical characteristic or a different optical characteristic.

[0217] Here, the method comprises the following steps: - determining values ​​of at least a global sensitivity parameter of the object according to the method described above, - determining adaptation values ​​of at least said optical features adapted to improve the visual acuity of a subject, - determining, for several gaze directions of the lens having the predetermined optical design, the difference between a current value of an optical characteristic of the lens in each of the gaze directions and a fitted value of the optical characteristic; - comparing this difference with the value of the global sensitivity parameter of interest; - selecting an appropriate optical design from said list of predefined optical designs taking into account this comparison. Includes.

[0218] The optical design of a lens specifies a set of parameters that make it possible to define the optical function of the lens. It therefore includes a set of data that associates the gaze direction of an object through the lens with the values ​​of the optical characteristics of the lens at the intersection between this gaze direction and the lens. The optical design in particular includes a set of data that associates each gaze direction with the values ​​of the refractive characteristics of the lens. It then provides the effect of the lens on the rays passing through the lens for each gaze direction.

[0219] The gaze direction of the subject is measured relative to a reference gaze direction corresponding to the gaze direction of the subject passing through a particular reference point of the lens, such as the optical center of the lens (for single vision lenses) or the fitting cross of the lens (for progressive lenses), which is determined by at least one, and preferably two, angles of the gaze direction compared to the reference gaze direction.

[0220] A given optical design corresponds to a map of the optical characteristics of the lens as a function of the subject's gaze direction.

[0221] In practice, a region of the optical design is determined in which said difference is smaller than the value of the global sensitivity parameter of interest, said region corresponding to a subset of the gaze directions.

[0222] This region of the optical design corresponds to the zone of perfect vision of the corresponding lens, since errors in the optical characteristics occurring in this region are not perceptible to the subject.

[0223] In practice, the method for selecting an appropriate predetermined optical design is - determining the regions of the given optical design where the difference is less than a value of a global sensitivity parameter of interest; - selecting an appropriate optical design by selecting an optical design that has an area of ​​greater size in at least one predetermined direction of the lens and / or has a shape that is closer to the predetermined shape. Includes.

[0224] For example, this can be done by calculating the area of ​​the region.

[0225] Preferably, the global sensitivity parameters considered are related to the optical characteristics observed.

[0226] This selection does not include any modification of the pre-determined optical designs listed. The method of selecting an optical design only allows for identifying the pre-determined optical design that would be most appropriate for a subject.

[0227] For example, among all the optical designs in the list of optical designs, the optical design having the largest area where said difference is smaller than the value of the global sensitivity parameter of interest is selected, or alternatively, the optical design having said area exhibiting a size larger than a predefined size threshold is selected.

[0228] Figure 7 shows an example of a list of predefined optical designs of lenses. These optical designs are represented by lines along which a given optical characteristic exhibits the same value. These lines correspond to the intersections of the line of sight direction with the mean surface of the lens, projected onto a plane for a 2D representation.

[0229] This given optical characteristic can be, for example, the sphere, cylinder or axis of the lens, or a combination of sphere, cylinder and axis, e.g., representing the visual acuity of the subject. For example, the line where the spheres of the lenses are the same is represented in three different designs in FIG.

[0230] The regions where said difference is smaller than the value of the global sensitivity parameter of the subject, which correspond to the zone of perfect vision of each corresponding lens, are shown in this figure by hatched zones. It is possible to show this graphical representation of the subject, which represents the lenses and the areas of the lenses that provide perfect vision to the corresponding lenses.

[0231] For a given optical design 3A, 3B, the hatched zone 31A, 31B corresponds to a zone of perfect vision, which is a periphery centered on the distance vision gaze direction FVA, FVB of the optical design 3A, 3B.

[0232] For optical design 3B, the hatched zone 31B is larger than the hatched zone of optical design 3A. This can be due to the difference in many factors such as pantoscope parameters, wrap angle, aspherization of the lens, etc. Therefore, this optical design 3B is selected over the other optical design 3A.

[0233] For optical design 3C, the area of ​​perfect vision does not cover the distance vision zone. This is a significant drawback of this optical design. In some cases, perfect vision may not exist because all gaze directions show differences in refractive index higher than the value of the subject's global sensitivity parameter.

[0234] The predetermined shape may be, for example, a target shape having a target dimension, for example a shape having a predetermined angular dimension in one direction, or a shape that is elongated, for example, in one predetermined direction.

[0235] Alternatively or additionally, it is possible to provide a score for the size of the complete vision zone, for example equal to the angular area of ​​the corresponding lens that provides complete vision in square degrees.

[0236] It is also possible to provide different graphical representations of the zones of interest and to determine said zones of perfect vision where the previously defined difference is less than the value of the global sensitivity parameter, zones having "ultimate" vision of the subject and / or where the previously defined difference is less than half the value of the global sensitivity parameter of the subject, and / or zones having acceptable vision where the previously defined difference is less than 1.5 times the value of the global sensitivity parameter of the subject.

[0237] Weighting may also be used, for example the angular zones in square degrees are calculated using weighting factors determined from the ratio between the difference in lens power and subject's refraction and the value of the subject's global sensitivity parameter.

[0238] For example, if the difference is 0 then the weight applied is 1, if the difference is above the value of the global sensitivity parameter of the subject then the weight is 0, and somewhere in between otherwise.

[0239] The present invention also allows for providing a performance map of an optical design.

[0240] The performance score can be determined, for example, by determining the global error W of the lens at each point on the surface of the lens. This performance score can be calculated as follows, where a+b+c=1, and a, b, and c are positive, and W=a.(Sphlens-Sphsubject) 2 / Ssph 2 +b.(Cyllens-Cylsubject) 2 / Scyl 2 +c.(Axislens-Axisubject) 2 / Saxis 2 , where Sphlens-Sphsubject, Cyllens-Cylsubject and Axislens-Axisubject are the sphere, cylinder and axis errors between the actual lens and the correction required by the subject.

[0241] A global score can be obtained by integrating this score W over a region of the lens or over the entire lens.

[0242] Such a performance map indicates the tolerance of each optical design to perturbations.

[0243] The probability of having a difference between the optical characteristics of a given optical design and the adapted optical characteristics determined for the subject can be estimated as a function of the magnitude of the perturbation. To adjust the determination of this probability, the value of the global sensitivity parameter of the subject can be taken into account, and then the probability of having a difference perceived by the subject between the optical characteristics of the optical design and the adapted optical characteristics determined for the subject is determined and used.

[0244] The error tolerance value can then be adjusted as a function of the subject's sensitivity to error.

[0245] To adjust the error tolerance values ​​for different optical features, different global parameters can be considered: for example, the global sensitivity of the error tolerance to errors on a spherical surface to the spherical surface or the overall global sensitivity to sphere and cylinder if these two optical features are considered.

[0246] For progressive lenses, designs with faster change in sphere and astigmatism, larger central clear zone but higher peripheral unwanted residual error can be suggested for subjects with a global sensitivity parameter value below a threshold (high sensitivity), and designs with slower change in sphere and astigmatism, smaller central clear zone but lower peripheral unwanted residual error can be suggested for subjects with a global sensitivity parameter value above a threshold (low sensitivity).

[0247] Furthermore, depending on the value of the global sensitivity parameter, such as a parameter related to the visual behavior of the subject, different other parameters of the subject may be taken into account in order to select the optical design of the lens.

[0248] Such parameters may, for example, relate to the subject's tendency to move their eyes or head while performing a visual task.

[0249] This parameter related to the visual behavior of the subject may be considered only for subjects having a global sensitivity parameter below a threshold, or may be considered with a weight determined as a function of the value of the global sensitivity parameter.

[0250] The invention also relates to a method for determining a customized optical design for a subject by taking into account the value of at least one global sensitivity parameter.

[0251] The customized optical design is obtained by modifying a given optical design according to a criterion based on the values ​​of the global sensitivity parameters.

[0252] The optical design is, for example, optimized to reach target values ​​of the optical characteristics of the corresponding lenses, these target values ​​being set taking into account the values ​​of the target global sensitivity parameters.

[0253] According to the present invention, there is provided a method for modifying a given optical design of an ophthalmic lens in order to adapt it to the visual acuity of a subject, said optical design including current values ​​of at least one optical characteristic of the lens associated with a plurality of gaze directions of the subject when the lens is worn by said subject. Thus, the method comprises the following steps: - determining values ​​of the global sensitivity parameters of the object according to the method described above, - determining a fitting value of said optical feature adapted to improve the visual acuity of a subject; - determining, for several gaze directions, the difference between the current value of an optical characteristic of the lens and an adapted value of said optical characteristic, - comparing this difference with the value of the global sensitivity parameter of interest; - determining a modified optical design for a modified lens by modifying said predetermined optical design for a lens in view of the comparison. Includes.

[0254] In practice, this means, for example, - determining an area of ​​the given optical design where the difference is less than a value of a global sensitivity parameter of interest; - determining a modified optical design such that modified regions of the modified optical design in which the difference is less than a value of the global sensitivity parameter of interest are larger than corresponding regions of the predetermined optical design and / or have a shape closer to a predetermined shape. The modified optical design can be obtained, for example, by considering additional processing of a lens manufactured with a given design, in which case the modified optical design is the optical design of a lens manufactured with a given design to which additional processing, for example aspherization or attrition, is applied.

[0255] In order to obtain a zone of full vision of maximum size, the application of the aspherization or attenuation process may be adapted according to the value of at least one global sensitivity parameter.

[0256] For example, a given optical design may show an insufficient match of one of the lens' spheres with the adapted sphere determined for the subject. In that case, the zone of perfect vision of a lens manufactured with this optical design may be small. Aspherizing the lens will expand the zone of perfect vision.

[0257] Thus, the choice of whether to aspherize a lens may depend on the value of at least one of the global sensitivity parameters of interest, for example, if the value of the spherical or overall sensitivity parameter Sgsph or Soverall is below a predefined threshold, then aspherization is recommended and / or performed.

[0258] The level of aspherization can also be adapted depending on the sensitivity: no aspherization for low sensitivity subjects, aspherization with standard wearing parameters for medium sensitivity subjects, and aspherization including fitting parameters such as tilt, wrap angle, eye-lens distance, etc. for high sensitivity subjects.

[0259] The choice of whether to attribulate a lens may also depend on the value of at least one of the global sensitivity parameters of the subject. For example, attrition is recommended and / or performed if the value of the global cylinder or overall sensitivity parameters Sgcyl, SgJ0, SgJx0, Sgasr, or Soverall falls below a predefined threshold.

[0260] Examples of possible modifications of a given optical design depending on the values ​​of the spherical and cylindrical global sensitivity parameters are shown in FIGS.

[0261] 8 is a graph showing the mean power (solid curve 200), sagittal power and tangential power (dashed curves 210, 220 on either side of the solid line) of each side of a monofocal ophthalmic lens having a given optical design for different angles (ordinate) of visual acuity of a subject. This given optical design is the standard.

[0262] In the example of FIG. 8, the subject has a prescription for a lens with a spherical power of -4D. The lens is a standard monofocal lens with a refractive index of 1.665, a central thickness of 1.4 mm, a spherical front surface of 2.75D of base curve (at 1.53), and a spherical back surface calculated to be -4D at the optical center. The lens wearing conditions are a corneal lens distance of 12 mm, a pantoscopic tilt of 0°, and a wrap angle of 0°. The prism between the two surfaces of the lens at the center of the lens is 0. Here, the center of the lens corresponds to a gaze direction with an angle of 0° for the monofocal lens.

[0263] The optical center of the lens is located at the visual acuity angle or at a gaze angle equal to zero, where the gaze is measured along the vertical median plane of the lens. The gaze angle plotted on the ordinate corresponds to the vertical movement of the subject's eye. The abscissa gives the error compared to the optical characteristic fitted to the subject, here the refractive power. Thus, zero on the abscissa corresponds to an optical characteristic equal to the fitted optical characteristic of the subject.

[0264] The sagittal and tangential powers of a lens are given by the maximum and minimum powers of the lens for each gaze direction, taking into account the aberrations of the lens. The horizontal difference between these two curves gives the astigmatism of the lens in a given gaze direction.

[0265] As can be seen from the graph of FIG. 8, for a given optical design, a lens with the given optical design will provide perfect vision to the subject in a small area centered on the optical center. If the subject's global sensitivity Soverall is 0.1, this area is the angular range [-17, +17 degrees]. Beyond this range, the curve moves away from the ordinate axis, indicating that the power of the lens differs from the power fitted to the subject. At an eccentricity of 30° away from the optical center, the power error is -0.17 diopters (D) and the unwanted astigmatism is 0.39D.

[0266] According to the present invention, the given optical design of this lens can be modified, ie, optimized, to have a larger zone around the optical center in which the subject has complete vision with the lens.

[0267] For subjects with high sensitivity to sphere and low sensitivity to cylinder, i.e. where the value of the global spherical sensitivity Sgsph is below the first spherical sensitivity threshold and the value of the global cylindrical sensitivity Sgcyl, or SgJ0, or SJx0 is above the first cylindrical sensitivity threshold, the modification of the given optical design aims to reduce the power error in a zone inside a circle of a given radius around the optical center, for example a radius of 35°.

[0268] The threshold for high sensitivity is, for example, 0.06D to 0.15D, preferentially 0.125D. The threshold for low sensitivity is, for example, 0.125D to 0.375D, preferentially 0.15D.

[0269] Using these conditions, a first modified design is obtained for optimization.

[0270] The lens of the first modified optical design has the same refractive index, central thickness, front surface, wear condition and prism between its two surfaces as the standard lens, but the compound back surface is modified to reach the same optical properties (power and astigmatism error as a function of gaze direction) as a monofocal lens with a front base curve of 4D instead of 2.75D. At an eccentricity of 30°, the power error of the lens with the first modified design is reduced to -0.02D and the unwanted astigmatism is reduced to 0.23D.

[0271] The graph in FIG. 9 shows the mean power 300, sagittal and tangential powers 310, 320 for this lens with the optical design modified with the same rules as in FIG.

[0272] As can be seen from Fig. 9, the difference between the mean power curve 300, the sagittal and tangential curves 310, 320 and the ordinate axis remains below the value of the global sensitivity parameter Soverall (0.1D) in the range up to [-30, +30 degrees]. The zone with perfect vision of the subject is indeed larger.

[0273] For objects with high sensitivity to cylinder and low sensitivity to sphere, i.e. values ​​of the cylindrical global sensitivity Sgcyl, or SgJ0, or SgJx0 below the second cylindrical sensitivity threshold and values ​​of the spherical global sensitivity Sgsph above the second spherical sensitivity threshold, the correction aims to reduce to a minimum the unwanted astigmatism in a zone inside a circle of a given radius around the optical center, for example a radius of 35°.

[0274] A second modified design is obtained using these criteria for optimization.

[0275] The lens of the second modified optical design has the same refractive index, central thickness, front surface, wear condition and prism between its two surfaces as the lens of the given design, but the compound back surface is optimized to reach the same optical properties (power and astigmatism error as a function of gaze direction) as a single vision lens with a front base curve of 6D instead of 2.75D. At an eccentricity of 30°, the power error is now reduced to 0.17D and the unwanted astigmatism is also reduced to 0.03D.

[0276] As can be seen from figure 10, the difference between the mean power curve 400, the sagittal and tangential curves 410, 420 and the ordinates remains below the value of the global sensitivity parameter Soverall (0.1D) in the range up to [-22, +22 degrees]. The zone with full vision of the subject is certainly larger than with a lens with a given optical design.

[0277] For objects with other sensitivities to cylinder and sphere, a given design modification aims to reduce a combination of both power error and unwanted astigmatism values ​​in a zone inside a circle of a given radius around the optical center, e.g., a radius of 35°.

[0278] Using these criteria, a third modified design is obtained for optimization.

[0279] A third modified optical design lens has the same refractive index, central thickness, front surface, wear condition and prism between its two surfaces as the standard lens, but the compound back surface is optimized to reach the same optical properties (power and astigmatism error as a function of gaze direction) as a monofocal lens with a front base curve of 5D instead of 2.75D. At an eccentricity of 30°, the power error is now reduced to 0.09D and the unwanted astigmatism is also reduced to 0.12D.

[0280] As can be seen from figure 11, the difference between the mean power curve 500, the sagittal and tangential curves 510, 520 and the ordinates remains below the value of the global sensitivity parameter Soverall (0.1D) in the range up to [-30, +30 degrees]. The zone with perfect vision of the subject is indeed larger than with a lens with a given optical design.

[0281] As shown in the above example, in order to optimize the optical design of the lens, several values ​​of different global sensitivity parameters can be considered.

[0282] Usually, a single vision lens is calculated according to the subject's prescription and can be optimized taking into account the prescription. This optimization represents a compromise between reducing the power error and reducing the unwanted astigmatism of the entire lens. By measuring the subject's sensitivity to sphere (Sgsph) and cylinder (Sgcyl), it is possible to adjust the optimization according to the subject's sensitivity.

[0283] The optical design of the progressive lens may be altered to optimize according to the value of at least one global sensitivity parameter.

[0284] In progressive lenses, design modifications will be aimed at expanding the zones of perfect vision centered around the distance and near vision of the lens.

[0285] The more sensitive the subject, i.e. the lower the value of the global sensitivity parameter, the larger the zone of vision through the lens with a lower level of aberration.

[0286] The size of the vision zone with low levels of power error and unwanted astigmatism can be modified depending on the global sensitivity score. In the example of Figures 12-14, the subject has a distance vision prescription of -4D and an add prescription of +2D. The progressive lens has a refractive index of 1.665, a central thickness of 1.4mm, and a spherical anterior surface of 2.75D with a base curve (at 1.53).

[0287] The lens wearing conditions are corneal lens distance 12 mm, pantoscopic inclination -8°, wrap angle 0°. The prism between the two surfaces of the lens at the prism reference point corresponds to 2 / 3 of the add. The prism reference point is located between two minute circles marked on the progressive lens. This corresponds to a point located 4 mm below the fitting cross, placed in front of the pupil of the subject's eye and at a gaze angle of 0°.

[0288] For example, a given optical design of this lens can be modified to optimize the distance vision zone of the lens, i.e. to increase the size of the complete vision zone centered on the distance gaze point, taking into account the value of the global sensitivity parameter of the subject, where the global sensitivity parameter Soverall is taken into account.

[0289] In Fig. 12, the dashed and thin solid lines 600, 610, 620 represent the optical characteristics (sagittal and tangential powers, mean power) of a lens optimized for a less sensitive subject, i.e. values ​​of the global sensitivity parameter above a fourth threshold, and the dotted and thick solid lines 700, 710, 720 represent the optical characteristics (sagittal and tangential powers, mean power) of a lens with the same prescription but optimized for a very sensitive subject, i.e. values ​​of the global sensitivity parameter below a fifth threshold. A high value of the global sensitivity parameter indicates a low sensitivity and a low value of the global sensitivity parameter indicates a high sensitivity.

[0290] In the distance vision zone located at intersection point FV in Figures 12 to 14, the mean power stabilizes in a slightly wider zone, and the low unwanted astigmatism zone is enlarged due to the optical design optimized for high sensitivity subjects.

[0291] The optical center is referenced OC in Figures 13 and 14. In these Figures 13 and 14, alpha and beta are the vertical and horizontal gaze angles.

[0292] Sensitivity may also be considered as a tolerance during manufacturing and / or trimming / mounting processes.

[0293] In particular, as described above, the values ​​of the global parameters determined according to the method of the present invention can be used to adapt the test protocol performed to determine the refractive characteristics of the subject's eye and the refractive characteristics of the corrective lens required by this subject.

[0294] The eye care professional is informed of this value by a message displayed on the screen of the device used to determine the refraction. A visual or sound warning signal can be issued to draw the eye care professional's attention to this information. Depending on the determined value, an alert signal can also be issued. For example, an alert signal is issued for subjects whose sensitivity exceeds a predefined threshold, for example for values ​​of the global sensitivity parameter less than 0.05D.

[0295] Based on this value of the global sensitivity parameter, recommendations can be made to the eye care professional regarding a test protocol for determining the refractive characteristics of the subject, for example, the use of a particular instrument, e.g., for highly sensitive subjects, an instrument that provides precise measurements, such as a refractor arranged on a column, can be recommended.

[0296] The global sensitivity value determined for a subject may also be used by an eye care practitioner to make recommendations to the subject. These recommendations may be made, for example, when delivering a prescription to the subject. The recommendations may be adapted taking into account a comparison of the value of the global sensitivity parameter to a threshold value.

[0297] The values ​​of the global sensitivity parameters may also be prescribed and may be underlined if they fall within a predefined range of values.

[0298] Among the possible recommendations related to the value of the global sensitivity parameter, it is possible to consider the recommendation of a type of lens, e.g. it is necessary to recommend a precise lens for a subject with high global sensitivity in order to provide the subject with precise refractive characteristics.

[0299] Furthermore, it is possible to estimate the visual capabilities of a subject using a given type of lens as a function of the wearer and the refractive characteristics adapted to the wearer's global sensitivity. Such estimated visual capabilities may take into account the predicted power errors and resulting astigmatism associated with the optical aberrations of the lens. Visual capabilities can be simulated and presented to the subject.

[0300] A type of frame can also be recommended based on the value of the global sensitivity parameter, and subjects with high global sensitivity may benefit from a frame that can fit precisely to their face and stay in place once fitted, such as would be the case for a frame with a nose pad.

[0301] As already mentioned above, the optical design of the lens may also be modified based on the values ​​of the global sensitivity parameters as well as the manufacturing, cutting, fitting and checking steps of the process of providing a vision correction device. When the lab responsible for manufacturing the lens receives the order including the values ​​of the global sensitivity parameters of the subject, the lab may either check the feasibility of the ordered lens and confirm the order, or alternatively send a request for additional parameter measurements for the subject or an indication of additional delays required to fulfill the order based on the values ​​of the global sensitivity parameters and the level of precision required to manufacture the lens.

[0302] Final adjustments of the device upon delivery at the optician can also be accommodated and, depending on the value of the global sensitivity parameters, special care can be taken to fit the glasses to the subject's face, with highly sensitive subjects requiring precise fitting.

[0303] Final recommendations may include encouraging the highly sensitive subject to visit the store periodically to check and adjust the fitting of their glasses, and also to check the current refraction of the subject's eyes using a test protocol adapted to the value of the sensitivity parameter.

[0304] High sensitivity subjects may require precise control of frame adjustment or re-measurement of fitting parameters, whereas low sensitivity subjects would not benefit from this.

[0305] Commercial offers made to subjects may also be adapted as a function of the value of the global sensitivity parameter, for example, subjects with high sensitivity who need to obtain new equipment more frequently than subjects with low sensitivity may be able to obtain specific commercial offers.

[0306] In order to take the value of the global sensitivity parameter into account throughout the process of providing an accurate vision correction device, this value needs to be transmitted to all parties involved in this process.

[0307] For this purpose, the value of the global sensitivity parameter is associated with an identification tag of the object. The association of the two data is stored, for example, in a secure manner on a server accessible online. It may be stored in Eyecloud™, a service offered by the Applicant.

[0308] To provide security for the data, known encryption methods may be used.

[0309] The methods described herein that take into account the values ​​of the global sensitivity parameters can improve image quality, comfort and / or fit to a subject's lens.

[0310] Alternatively, any method described herein using global sensitivity parameters can be implemented in a simplified mode with a single value of a specific sensitivity parameter, which, however, will provide less improvement compared to the improvement achieved using the global sensitivity parameter values, due to its lower accuracy and reliability.

Claims

1. 1. A method for determining a value of a global sensitivity parameter of an individual, said global sensitivity parameter relating to the sensitivity of said individual to changes in at least a refractive optical characteristic of at least an ophthalmic lens placed in front of at least one eye of said individual, said method comprising the steps of: a) determining (100) a single value of at least a first sensitivity parameter of said individual relative to said sensitivity of said individual to changes in a first refractive optical characteristic of at least a first ophthalmic lens; b) determining (110) a single value of at least a second sensitivity parameter of the individual relative to said sensitivity of said individual to changes in a second refractive optical characteristic of at least a second ophthalmic lens, each of said first and second sensitivity parameters being associated with a minimal change in said first and second refractive optical characteristic, respectively, that can be perceived by said individual; c) determining (120) using a calculation means a value of the global sensitivity parameter based on a combination of a single value of the first sensitivity parameter and a single value of the second sensitivity parameter; Including, During steps a) and b), a single value of the spherical sensitivity of each of the left and right eyes of the individual and a single value of the spherical binocular sensitivity of the individual are determined, and - in step c), the value of the determined global sensitivity parameter is the value of a global spherical sensitivity parameter equal to the average value of the single value of the spherical sensitivity of the left and right eye and the single value of the spherical binocular sensitivity.

2. At least the first and second sensitivity parameters determined in steps a) and b) are - the spherical sensitivity to said change in the sphere of at least said first or second ophthalmic lens for at least one of said individual's eyes, - cylinder and / or axis sensitivity to said change in cylinder power and / or axis of at least said first or second ophthalmic lens for at least one of said individual's eyes, the spherical binocular sensitivity of said individual to binocular changes in the sphere of said first and second ophthalmic lenses, the binocular balance sensitivity of said individual to changes in the binocular balance of said first and second ophthalmic lenses, the add sensitivity to said change in add power of at least said first or second ophthalmic lens for at least one of said individual's eyes, The method of claim 1 , further comprising at least one of:

3. 3. The method according to claim 2, wherein the single values ​​of at least a first and a second sensitivity parameter determined in steps a) and b) are determined with different measurement methods, respectively, or under similar or different measurement conditions, respectively.

4. The method according to any one of claims 1 to 3, wherein in step c) the combination comprises an average of the single values ​​of the first and second sensitivity parameters determined during steps a) and b).

5. The single values ​​of the first and second sensitivity parameters determined during steps a) and b) are a single value of the cylindrical sensitivity for each of the left and right eyes, or a single value of the axial sensitivity for each of the left and right eyes, or a single value of astigmatism sensitivity for each of said left and right eyes, - a single value of the sphere, cylinder, axis and binocular balance sensitivity of one of said left and right eyes, and In step c), the values ​​of the determined global sensitivity parameters are respectively - the value of a global cylindrical sensitivity parameter equal to the average of the single values ​​of the cylindrical sensitivities of the left and right eye, or the value of a global axis sensitivity parameter equal to the average of the single values ​​of the axis sensitivities of the left and right eye, or a value of the global sensitivity parameter of the left or right eye equal to the average value of the single values ​​of the spherical, cylindrical, axial and binocular balance sensitivities of the left or right eye, The method according to any one of claims 1 to 4, wherein

6. In steps a) and b), a single value of the spherical sensitivity of each of the left and right eyes, and a single value of the cylindrical sensitivity of each of said left and right eyes, and a single value of the axial sensitivity of each of said left and right eyes, and - the value of the spherical binocular sensitivity of said individual, and - the value of the binocular balance sensitivity of said individual, is determined, and In step c), the value of the final global sensitivity parameter Soverall is calculated according to the following formula: Soverall=[(SsphOD+SsphOG+Ssphbino) / 3+(ScylOD+ScylOG) / 2+(SaxisOD+SaxisOG) / 2+Seqbino] / 4 It is determined by where Soverall is the final global sensitivity parameter, SsphOD and SsphOG are the single values ​​of the spherical sensitivities of the left and right eyes, respectively; Ssphbino is the value of the individual's spherical binocular sensitivity, ScylOD and ScylOG are the single values ​​of cylinder sensitivity for the left and right eyes, respectively; SaxisOD and SaxisOG are the single values ​​of axial sensitivity for the left and right eyes, respectively; The method according to any one of claims 1 to 5, wherein Seqbino is a value of binocular balance sensitivity of the individual.

7. - displaying said value of said global sensitivity parameter for notification to an eye care practitioner. The method of any one of claims 1 to 6, further comprising:

8. 1. A method for determining adapted refractive optical characteristics of an ophthalmic lens adapted to improve an individual's visual acuity, comprising the steps of: - a test protocol, - repeating the steps of placing a test lens in front of the individual's eye; an iterative step of assessing the quality of the individual's vision looking through said test lenses, the value of said refractive optical characteristics of said test lenses being increased by an incremental value between each iteration of said steps; an iterative step of comparing the quality of the visual acuity of the individual looking through at least two successive test lenses placed in front of the eye of the individual during two successive iterations of the steps of the test protocol and determining the adapted refractive optical characteristics based on the comparison; - an iterative step of determining the value of the personal global sensitivity parameter according to the method of any one of claims 1 to 6, an iterative step of determining said increment value taking into account said value of said global sensitivity parameter; performing a test protocol comprising: The method includes:

9. A method for selecting a suitable optical design for an ophthalmic lens adapted to improve the visual acuity of an individual from among a list of predefined optical designs, the optical designs including current values ​​of at least one refractive optical characteristic of a corresponding lens having the predefined optical design associated with a plurality of gaze directions of the individual when the ophthalmic lens is worn by the individual, the method comprising the steps of: - determining the value of the personal global sensitivity parameter according to the method of any one of claims 1 to 6, - determining a fitting value of said refractive optical characteristics adapted to improve said visual acuity of said individual, - determining, for different gaze directions, the difference between the current value of the refractive optical characteristic of the corresponding lens and the adapted value of the refractive optical characteristic; - comparing said difference with said value of said global sensitivity parameter of said individual, - selecting, from among said list of predefined optical designs, said suitable optical design taking into account said comparison; A method comprising:

10. 1. A method of modifying a predefined optical design of an ophthalmic lens to adapt it to the visual acuity of an individual, the optical design including current values ​​of at least one refractive optical characteristic of a corresponding lens having the predefined optical design associated with a plurality of gaze directions of the individual when the ophthalmic lens is worn by the individual, the method comprising the steps of: - determining the value of the personal global sensitivity parameter according to the method of any one of claims 1 to 6, - determining a fitting value of said refractive optical characteristics adapted to improve said visual acuity of said individual, - determining, for several gaze directions, the difference between the current value of the refractive optical characteristic of the corresponding lens and the adapted value of the refractive optical characteristic; - comparing said difference with said value of said global sensitivity parameter of said individual, - determining a modified optical design for a modified corresponding lens by modifying the predetermined optical design of the lens taking into account said comparison; A method comprising:

11. 1. A system for determining a value of a global sensitivity parameter of an individual, the global sensitivity parameter relating to a sensitivity of the individual to changes in at least a refractive optical characteristic of at least an ophthalmic lens placed in front of at least one eye of the individual, the system comprising: means for determining a single value of at least a first sensitivity parameter of said individual relative to said sensitivity of said individual to a change in a first refractive optical characteristic of at least a first ophthalmic lens; means for determining a single value of at least a second sensitivity parameter of said individual relative to said sensitivity of said individual to a change in a second refractive optical characteristic of at least a second ophthalmic lens; - computing means programmed to determine a value of said global sensitivity parameter based on a combination of a single value of said first sensitivity parameter and a single value of said second sensitivity parameter; Including, the single value of at least a first sensitivity parameter of the individual and the single value of at least a second sensitivity parameter of the individual correspond to a single value of a spherical sensitivity of each of the individual's left eye and right eye and a single value of a spherical binocular sensitivity of the individual; The system, wherein the determined value of the global sensitivity parameter is a value of a global spherical sensitivity parameter equal to the average value of a single value of the spherical sensitivity of each of the left and right eyes and a single value of the spherical binocular sensitivity.

12. - means for storing the values ​​of the global sensitivity parameters determined by the calculation means, and / or - means for displaying said value of said global sensitivity parameter determined by said calculation means; The system of claim 11 further comprising:

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