SYSTEM AND ASSOCIATED METHOD FOR DETERMINING THE SUBJECTIVE VALUE OF OPTICAL CHARACTERISTICS OF AT LEAST A CORRECTION LENS FITTED TO A SUBJECT'S EYES - Patent application

Abstract

The present invention relates to a system for determining magnitude values ​​associated with subjective values ​​of optical characteristics of at least corrective lenses fitted to a subject's eyes by performing a subjective test in which the subject is asked to describe his or her visual performance in a plurality of real optical conditions by selecting one explanatory answer from a set of possible explanatory answers, the system comprising a computer having one or more memories and one or more processors, - an initial model providing a probability of each explanatory answer of a set of explanatory answers for each theoretical optical condition of a plurality of theoretical optical conditions is stored in one of the one or more memories of the computer; - the one or more processors of the computer a) collecting (500) results of the subjective test, which is performed by asking a subject to describe their visual performance in each actual optical condition of the plurality of actual optical conditions by selecting, for each actual optical condition, one explanatory answer from the set of possible explanatory answers, wherein the results include each selected explanatory answer and the corresponding actual optical condition; b) determining the magnitude value by considering the initial model and each collected explanatory response (800, 900); It is programmed like this.

Description

[Technical field]

[0001] The present invention relates to a system and method for determining the subjective value of at least the optical characteristics of a corrective lens fitted to a subject's eye. [Background technology]

[0002] In order to provide visual equipment adapted to the subject's visual impairment, this visual impairment must be estimated.

[0003] A first possibility is to measure the objective values ​​of the optical characteristics of the subject's eye.

[0004] It is also known to determine the subjective values ​​of the optical characteristics of the corrective lenses required by a subject by subjective tests.

[0005] In practice, the subject's vision is tested during a test protocol using a phoropter, which makes it possible to place lenses with different values ​​of optical characteristics in succession in front of the subject's eyes.

[0006] This testing protocol can be accomplished using a classic phoropter or a phoropter with two complex lenses of variable power.

[0007] 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 with different spheres are placed in succession in front of one eye of a subject during successive trials. The sphere is increased by a predetermined step value from one trial to the next. This step value is usually 0.25 diopters (D) or 0.125D.

[0008] The subjective testing protocol may also use modified phoropters that include lenses of variable power. Such phoropters / variable lenses are described, for example, in U.S. Pat. No. 5,393,633, U.S. Pat. No. 5,493,367, or U.S. Pat. No. 5,523,366.

[0009] In each trial of the subjective test, corresponding to the current lens placed in front of the eye, the subject is asked to indicate a visual assessment that corresponds to an indication of a preferred visual state out of two presented visual states, or whether they cannot decide between the two visual states. The two visual states may, for example, correspond to the subject's vision of two different images through the current lens, or may correspond to the subject's vision through a previous lens and through the current lens.

[0010] In practice, each trial of the subjective test protocol may correspond to, for example, a rating given by a subject during a duochrome test, during which the subject is presented with an image that includes a target displayed on a red background on the one hand and a target displayed on a green background on the other hand. If the subject has better vision through the current lens at a target on a red background, the sphere should be reduced in the next lens presented, and if the subject has better vision through the current lens at a target shown on a green background, the sphere should be increased in the next lens presented.

[0011] Alternatively, in each trial, with the 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 visual quality.

[0012] Thus, state-of-the-art subjective testing relies on a predefined standardized protocol. This protocol may use the subject's characteristics as an entry for the first trial of the protocol, for example, to determine the optical characteristics of a test lens that is first placed in front of the subject. Otherwise, no other customization is provided.

[0013] As a result, the protocols may take a long time to execute or may be inaccurate for certain subjects, such as children. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] US Patent Application Publication No. 2016 / 0331226 [Patent Document 2] US Patent Application Publication No. 2017 / 027435 [Patent Document 3] International Publication No. 2017 / 021663 Brochure [Patent Document 4] International Application No. PCT / EP2018 / 061207 [Patent Document 5] US Patent Application Publication No. 2016 / 0331226 [Patent Document 6] US Patent Application Publication No. 2017 / 027435 [Patent Document 7] International Publication No. 2017 / 021663 Brochure Summary of the Invention [Means for solving the problem]

[0015] It is therefore one object of the present invention to provide a system for determining a subjective value of a magnitude related to the subjective value of the optical characteristics of at least a corrective lens fitted to a subject's eye, which enables a more efficient testing protocol, reduces the time required to perform the subjective test, and increases the reliability of the subjective test.

[0016] By reliable it is meant that the subjective values ​​of the optical characteristics are accurate and reproducible.

[0017] The above object is achieved according to the invention by providing a system for determining a magnitude value associated with a subjective value of an optical characteristic of at least a corrective lens fitted to an eye of a subject, by carrying out a subjective test in which the subject is asked to describe his / her visual performance in a number of real optical conditions by selecting one explanatory answer out of a set of possible explanatory answers, the system comprising a computer having one or more memories and one or more processors, - storing in one of the one or more memories of the computer an initial model providing a probability of each explanatory answer of the set of explanatory answers for each theoretical optical condition of the plurality of theoretical optical conditions; - One or more processors of a computer a) collecting results of a subjective test performed by asking subjects to describe their visual performance in each actual optical condition of a plurality of actual optical conditions by selecting, for each actual optical condition, one explanatory answer from a set of possible explanatory answers, the results including each selected explanatory answer and the corresponding actual optical condition; b) determining a magnitude value by considering the initial model and each explanatory response collected; It is programmed like this.

[0018] The magnitude related to the subjective value of the optical characteristics of at least the corrective lens fitted to the eye of the subject may be any kind of magnitude, in particular - the value of the optical characteristic itself, - a statistically determined magnitude based on multiple values ​​of the optical characteristic, such as a mean, a weighted average, or a standard deviation; - an indication of the confidence level associated with the measurement of the optical characteristic; may be also possible.

[0019] In step b), the value is determined taking into account the initial model, which is true as long as at least one trial of the subjective test is performed using the initial model. The initial model can be used to determine values ​​of parameters of the subjective test, such as step values ​​for increasing / decreasing the optical characteristics of an optical component placed in front of the subject's eye, for example, to determine a modified model to be used in further trials, and / or to directly determine a magnitude value.

[0020] With the system according to the invention, the magnitude determination takes into account an initial model that gives the probability of each explanatory answer of a set of explanatory answers for each theoretical optical condition of a plurality of theoretical optical conditions. Thus, by comparing the actual optical conditions with the theoretical conditions, it is possible to determine the most likely answer of the subject in the actual optical conditions. Furthermore, based on this most likely answer, the subjective test protocol can be modified more efficiently by reducing the time required to perform the subjective test and increasing the reliability of the subjective test.

[0021] By determining the initial model based on the subject's personal characteristics, it is further possible to tailor the subjective test to the subject.

[0022] Other advantageous, non-limiting features of the system according to the invention are listed below. - in step b), the computer is programmed to compare the initial model with at least one collected explanatory answer and to determine a magnitude value based on this comparison, in particular the computer is programmed to compare the initial model with each collected explanatory answer and to determine a magnitude value based on this comparison, The initial model includes an initial model curve, an initial model equation, and an initial model data set; At least one of the initial model comprises an initial model curve, and the computer in step b) - plotting at least one collected explanatory answer selected by the subject against a corresponding actual optical condition and overlaying an initial model curve on the resulting plot such that the initial model curve is fitted to the plot; - determining a magnitude value taking into account the relative position of the initial model curve and the plot; the method being programmed to execute the substeps consisting of: the initial model comprises an initial data set, and the computer in step b) - statistically processing the initial data set and the collected narrative responses; - determining a magnitude value taking into account this statistical process; and the method being programmed to execute the substeps consisting of: - in step b), the computer - modifying the initial model to obtain a modified model taking into account at least one explanatory answer of the subject and the corresponding actual optical conditions; - comparing the modified model with the collected explanatory responses and determining a magnitude value based on this comparison, in particular modifying the initial model to obtain a modified model taking into account each explanatory response of the subject and the corresponding actual optical conditions, comparing the modified model with each collected explanatory response and determining a magnitude value based on this comparison; the method being programmed to execute the substeps consisting of: the modified model includes a modified model curve, a modified equation, and a modified model data set; At least one of the correction model comprises a correction model curve, and the computer in step b) - plotting at least one, and possibly each, of the collected explanatory answers selected by the subject against a corresponding actual optical condition and superimposing the modified model curve on the resulting plot such that the modified model curve is fitted to the plot; - determining a magnitude value taking into account the relative position of the modified model curve and the plot; the method being programmed to execute the substeps consisting of: the modified model includes an initial data set, and the computer, in step b), - statistically processing the revised data set and the collected narrative responses; - determining a magnitude value taking into account this statistical process; and the method being programmed to execute the substeps consisting of: - The initial model takes into account one or more personal characteristics of the subject, - Personal characteristics are at least: - Social parameters such as age, sex, place of origin, history of eye care, etc. - Morphological parameters such as pupil size, interpupillary distance, etc. optical parameters such as type and / or value of refractive error, astigmatism, distance between eye and lens, Setting parameters such as the starting point of the subjective test, the type of stimulus, the distance for testing far or near vision, the distance between the phoropter and the eye, etc. - visual parameters such as visual acuity, previous answers to subjective tests, dominant eye, binocular vision, eye movements, etc. behavioral parameters such as rapidity of previous answers to subjective tests, sensitivity to variations in at least the optical characteristics of ophthalmic lenses, Contains the value of - the computer is further programmed to determine at least initial parameter values ​​of the subjective test based on personal characteristics of the subject; - the computer is programmed to take into account the initial model to determine at least initial parameter values ​​of the subjective test; - the optical characteristics of the corrective lenses fitted to the subject are - the sphere in the zone for distance and / or near vision, - cylinder power and / or axis or a combination thereof in the zones for distance vision and / or for near vision, - prism power and / or axis or a combination thereof in the zones for distance vision and / or for near vision, - the filter transmittance in the zones for distance and / or near vision, At least one of - A set of explanatory answers - Better visual performance in first real optical conditions, - Better visual performance in second real optical conditions, - no difference is perceived between the first actual optical condition and the second actual optical condition, The answer includes: The initial model is statistically determined based on a reference dataset previously collected while performing subjective testing on a number of reference subjects, the reference dataset being - the personal characteristics of each referent; - the actual optical conditions and corresponding answers of each reference subject, Including, - the initial model is determined based on the average or weighted average of this reference data set, - the initial model is determined based on an average or weighted average of a portion of the reference data set selected based on one or more personal characteristics of the reference subject, and / or the initial model is determined using machine learning algorithms and / or neural network algorithms, - a plot of reference responses is obtained by plotting the responses of each reference subject against the corresponding actual optical condition, and an initial model is determined based on characteristics of the distribution of the plot of reference responses; - the reference subjects are selected from a group of reference subjects as having one or more personal characteristics that are identical or similar to a corresponding personal characteristic of the subject; - the computer is programmed to perform subjective tests and to determine the actual optical conditions that are subsequently used to perform the subjective tests taking into account the initial model; - the computer is programmed to perform the subjective test and to determine the actual optical conditions subsequently used to perform the subjective test taking into account the correction model; - the computer is programmed to determine a magnitude value based on a position of the initial model curve or the modified model curve relative to the plot when this position is determined after a predetermined number of trials or when this position does not modify by more than a predetermined amount between two successive trials of the subjective test; - the computer is programmed to compare each of the collected explanatory responses corresponding to the actual optical conditions with the initial model or the modified model, and if the comparison indicates that a difference between a particular collected explanatory response corresponding to a particular actual optical condition and the respective modified initial model exceeds a predetermined threshold, the particular collected explanatory response is identified as being inconsistent; If the number of conflicting answers exceeds a predefined threshold, the initial model or the modified model is modified to reduce the number of conflicting answers.

[0023] The invention also relates to a method for determining a magnitude value related to a subjective value of an optical characteristic of at least a corrective lens fitted to an eye of a subject, through a subjective test in which the subject is asked to describe his / her visual performance in a number of real optical conditions by selecting one explanatory answer out of a set of possible explanatory answers, the method comprising: i) providing an initial model that provides a probability of each explanatory answer of a set of explanatory answers for each theoretical optical condition of a plurality of theoretical optical conditions; j) performing a subjective test by asking the subject to describe his / her visual performance in each of the plurality of actual optical conditions by selecting one explanatory answer from a set of possible explanatory answers for each actual optical condition; k) collecting each of the subject's descriptive responses and the corresponding actual optical conditions; l) determining a magnitude value by considering the initial model and each of the explanatory responses collected; The method includes the steps of:

[0024] The method is generally carried out by a system according to the present invention.

[0025] Detailed Description of the Preferred Embodiments The following description, referring to the accompanying drawings, will make clear what constitutes the present invention and how it can be achieved. The present invention is not limited to the embodiments shown in the drawings. Therefore, when features mentioned in the claims are followed by reference signs, it should be understood that such signs are included only to enhance the level of understanding of the claims, and do not limit the scope of the claims. [Brief description of the drawings]

[0026] [Figure 1] 1 is a schematic block diagram of an embodiment of a method according to the invention using a device according to the invention; [Diagram 2] Schematic plot (squares) of the answers of several subjects obtained during the corresponding subjective tests plotted against the theoretical optical conditions linked to the sphere of the lens placed in front of each subject's eye in each corresponding trial of the subjective test corrected on the basis of each subject's actual refraction, with a comparison with graphs (solid and dashed lines) of three different initial models determined on the basis of these data (as will be explained later, the answer represented by the value "0" corresponds to an answer in which the subject distinguishes there is no difference between the two actual optical conditions tested). [Diagram 3] Schematic plot (squares) of the subject's responses obtained in successive trials of a subjective test corresponding to the actual optical conditions (here the sphere in diopters of the test lens) fitted by an initial model curve (solid line). [Figure 4] Schematic plot (squares) of the subject's responses obtained in successive trials of a subjective test corresponding to the actual optical conditions (here the sphere in diopters of the test lens) fitted by an initial model curve (solid line). [Diagram 5]Schematic plot (squares) of the subject's responses obtained in successive trials of a subjective test corresponding to the actual optical conditions (here the sphere in diopters of the test lens) fitted by an initial model curve (solid line). [Figure 6] Schematic plot (squares) of the subject's responses obtained in successive trials of a subjective test corresponding to the actual optical conditions (here the sphere in diopters of the test lens) fitted by an initial model curve (solid line). [Figure 7] Schematic plot (squares) of the subject's responses obtained in successive trials of a subjective test corresponding to the actual optical conditions (here the sphere in diopters of the test lens) fitted by an initial model curve (solid line). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The present invention is in the field of conception and manufacture of visual instruments adapted to the optical characteristics of at least one eye of a subject in order to improve vision by compensating for a visual defect in that eye.

[0028] FIG. 1 shows a schematic diagram of the steps of one embodiment of a method for determining a magnitude value related to a subjective value of an optical characteristic of at least a corrective lens fitted to a subject's eye according to the invention.

[0029] The magnitude value is determined by subjective testing.

[0030] The magnitudes related to the subjective values ​​of the optical characteristics of at least the corrective lens fitted to the subject's eye are in particular - the subjective value of the optical characteristics itself, - a statistically determined magnitude based on multiple subjective values ​​of the optical characteristics, such as an average, a weighted average, or a standard deviation; - an indication of the level of confidence associated with the subjective value of the optical characteristic, It could be.

[0031] The optical characteristics of the corrective lens can be any optical characteristics useful for compensating for any type of visual impairment in a subject.

[0032] In particular, the optical characteristics of the corrective lenses fitted to the subject are the sphere of the lens in the zone for distance and / or near vision, - addition degree, - the cylinder and / or axis or a combination thereof in the zones of the lens for distance and / or near vision, - the prism power and / or axis or a combination thereof in the zones of the lens for distance and / or near vision, - the filter transmittance in the zones of the lens for distance and / or near vision, Includes at least one of the following:

[0033] The sphere corresponds to the refractive power of the lens, given in diopters, due to the spherical components of the shape of the front and back surfaces of the lens.

[0034] Cylinder corresponds to the refractive power of the lens given in diopters by the cylindrical components of the shape of the front and back surfaces of the lens.

[0035] The axis corresponds to the orientation of the cylindrical component of the lens shape.

[0036] The cylinder power and axis represent the cylinder component of the ophthalmic lens determined to compensate for the astigmatism of the subject's eye. Instead of being determined in standard polar form with magnitude and orientation decomposition, as described in the applicant's US Pat. No. 6,399,633, a vector decomposition of the cylinder component may be used.

[0037] The vector decomposition of the cylindrical components can be performed according to two orthogonal directions J0, J45.

[0038] 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 ​​(M, J0, J45) defined as an astigmatic decomposition of the polar form of astigmatism (C, axis) as an equivalent spherical lens of power M=S+C / 2 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).

[0039] To more closely resemble the standard Jackson cross cylinder procedure, the two orthogonal directions may correspond to the initial astigmatism direction and its perpendicular direction.

[0040] 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.

[0041] A prism is a wedge-shaped optical component. When a ray of light passes through a prism, the ray of light diverges towards the base of the prism, i.e. towards the larger side of the prism.

[0042] A corrective lens usually has a non-uniform thickness so that it behaves like a prism: a subject looking at an object through the lens will see this object as slightly deviating, since the image seen will appear to originate from a deviating light ray direction.

[0043] Prism power corresponds to the prism displacement of the image in prism diopters, with one prism diopter equal to a displacement of one centimeter over a distance of one meter.

[0044] The filter transmittance corresponds to the ratio of the intensity of the light emerging from the correction lens and the intensity of the incident light.

[0045] Furthermore, subjective values ​​for binocular balance, astigmatism, addition, or binocular surface may additionally be determined during the subjective test.

[0046] 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 eyes. In order to achieve a comfortable correction of the subject's eyes, it is certainly useful to ensure that the quality of the image seen through the fitted lens with the determined fitted sphere is similar on both eyes.

[0047] 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.

[0048] Thus, the corresponding optical characteristic may be equal to the difference between the spheres of both lenses.

[0049] It 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.

[0050] 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 simultaneously changed by the same increment and the binocular vision quality is evaluated by the subject. The subject is then asked to compare the quality of the image seen when both spheres are changed.

[0051] More precisely, according to the method of the invention, the method comprises: i) providing an initial model that provides a probability of each explanatory answer of a set of explanatory answers for each theoretical optical condition of a plurality of theoretical optical conditions; j) performing a subjective test by asking the subject to describe his / her visual performance in each of the plurality of actual optical conditions by selecting one explanatory answer from a set of possible explanatory answers for each actual optical condition; k) collecting each of the subject's descriptive responses and the corresponding actual optical conditions; l) determining a magnitude value by considering the initial model and each of the explanatory responses collected; The method includes the steps of:

[0052] The method is carried out by a system for determining a magnitude value related to a subjective value of an optical characteristic of at least a corrective lens fitted to an eye of a subject according to the present invention.

[0053] The system includes a computer having one or more memories and one or more processors.

[0054] In accordance with the invention, an initial model providing a probability of each explanatory answer of a set of explanatory answers for each theoretical optical condition of a plurality of theoretical optical conditions is stored in one of one or more memories of a computer.

[0055] The one or more memories of a computer may include permanent memory or temporary memory.

[0056] This memory may be local or remote. The memory may be housed with the processor or may be accessed remotely via a network cable (wired) or wireless connection. Thus, the initial model may be stored in the computer's local memory or retrieved from a server / cloud.

[0057] In a preliminary step of the method according to the invention, an initial model is determined (block 300 in FIG. 1).

[0058] The initial model provides a probability of each explanatory answer of the set of explanatory answers for each theoretical optical condition of the plurality of theoretical optical conditions.

[0059] The initial model includes an initial model curve, an initial model equation between the answer and the theoretical optical condition, and an initial model data set; may include at least one of:

[0060] In particular, the initial model may be continuous, in the case of a curve or equation, or discontinuous, in the case of a data set.

[0061] The initial model curve may correspond to a graphical representation of a corresponding initial model equation linking the answer with the theoretical optical conditions or initial model data set, or may be determined based on such initial model data set.

[0062] The initial model curve or formula or data set is, for example, statistically determined based on a reference data set previously collected while performing subjective tests on a number of reference subjects, the reference data set including the actual optical conditions and the corresponding answers of each subjective test performed on each reference subject.

[0063] In a preliminary step of the method according to the invention, a data set is acquired (block 100 in FIG. 1).

[0064] Preferably, for all tests performed, such as classical refraction, duochrome, Jackson cross cylinder, binocular balance, etc., the respective answers for all corrections tested are collected and can be considered to determine the initial model.

[0065] The reference data set also preferably includes at least one personal characteristic of each reference subject, stored with respect to other data for this reference subject.

[0066] At a minimum, personal characteristics include - Social parameters such as age, sex, place of origin, etc. - Eye care history (past prescriptions, eye diseases / problems, etc.), - morphological parameters such as pupil size and interpupillary distance, - optical parameters such as the type and / or value of the refractive error, in particular the sphere, cylinder, cylinder axis, astigmatism, distance between the eye and the lens, - setting parameters such as the starting point of the subjective test, the type of stimulus, the distance for testing far or near vision, the distance between the phoropter and the eye, etc. - visual parameters such as visual acuity, previous answers to subjective tests, dominant eye, binocular vision or eye movements, - behavioral parameters such as the rapidity of previous answers to subjective tests, the sensitivity to variations in at least the optical characteristics of at least the ophthalmic lenses, Contains the value of

[0067] Other information regarding the reference subjects is preferably collected in the reference data set, such as the final refraction or final optical characteristics determined via each test performed.

[0068] The reference data set is collected, for example, by saving the above-mentioned data of each reference subject after each subjective test performed.

[0069] Data can be collected automatically from devices used to administer the subjective tests anywhere in the world and programmed to transmit these data to a computer.

[0070] In one embodiment, the initial model is determined based on statistical characteristics of a reference data set.

[0071] In particular, the initial model is determined based on the average or weighted average of the reference data set.

[0072] This means that an initial model curve or equation or data set is determined by fitting a modified data set that includes the average or weighted average value of the reference data set.

[0073] For example, three different possible answers of a performed subjective test may be associated with numerical values ​​and these values ​​may be averaged for fixed actual optical conditions.

[0074] Possible answers are, for example: - better visual performance in a first actual optical condition, for example coded as "1", i.e. represented in FIG. 2 with ordinate value 1; - better visual performance in a second real optical condition, e.g. coded as "-1", i.e. represented in Fig. 2 with an ordinate value of -1; - no difference is perceived between the first and second actual optical conditions, for example coded as "0", i.e. represented in FIG. 2 with an ordinate value of 0, It consists of:

[0075] In the case where the initial model curve or formula or data set is determined by fitting a modified data set with the mean or weighted mean of the reference data set, if for a given sphere value 10 answers corresponding to the value -1, 8 answers corresponding to the value 0 and 2 answers corresponding to the value +1 are obtained, the mean value of the answers that will be associated with the given sphere value is -0.4 (-40% for a percentage scale). The averaged answers may be given by the same subject or by different subjects. Finally, the mean value of the data set is not a priori equal to -1, 0 or 1, but represents the probability of obtaining an answer of 1, 0 or -1.

[0076] It is also possible to determine the initial model based on the distribution envelope of the reference data set, for example, a reference response plot is obtained by plotting the responses of each reference subject against the corresponding actual optical conditions, and the initial model is determined based on the distribution characteristics of the reference response plot.

[0077] A distribution envelope can be defined, for example, as including data within a given percentile or data located at a given distance from the mean data. For example, for a reference data set, all data collected at a particular actual optical condition are distributed around a mean or median. The median corresponds to a 50% distribution. 50% of the values ​​collected at this actual optical condition are above the median and 50% are below the median.

[0078] Other statistically interesting values ​​can be defined, for example, by the 10% and 90% values ​​of the distribution: 90% of the values ​​collected at this actual optical condition are above and 10% are below the 10% value of the distribution, and 10% of the values ​​collected at this actual optical condition are above and 90% are below the 90% value of the distribution.

[0079] Examples of different initial models obtained using different parts of the distribution of the reference dataset are shown in FIG.

[0080] The solid curve represents the initial model obtained by considering the data for 50% of the distribution.

[0081] The two dashed curves represent the initial model obtained by considering the 10% (curve M10) and 90% (curve M90) values ​​of the distribution of the data. In the case of Figure 2, the data represented are corrected according to the following description.

[0082] Any other distribution of the reference data set, whether corrected or not, may also be used, for example the values ​​at the 25% percentage (1st quartile) or the values ​​at the 75% percentage (3rd quartile).

[0083] In one embodiment, the initial model considers the explanatory answers given by all referent subjects, without selecting them based on their personal characteristics.

[0084] In this case, the reference data set may need to be corrected to take into account differences between the personal characteristics of the reference subjects. An initial model is then determined based on the corrected reference data set.

[0085] For example, the theoretical optical conditions of the initial model are linked to the optical components placed in front of the subject when the answers plotted on the ordinate are given by the reference subject. These theoretical optical conditions may be the values ​​of the optical characteristics of the lenses placed in front of the subject, or may be estimated from the values ​​of this optical characteristic, for example by applying an offset or multiplication factor.

[0086] An example is given below as to how reference data of reference subjects with different actual spherical refractions can be taken into account for determining the initial model.

[0087] To do so, the theoretical optical condition of the initial model is defined for each reference subject's actual refraction. For example, the theoretical optical condition can correspond to the actual optical condition of the reference data set with an offset. The offset is calculated to center the data on a predetermined refraction value. Then, the initial model is determined based on the corrected actual optical condition that corresponds to the actual optical condition with an offset.

[0088] For example, in practice, a subjective test is first carried out on a reference subject, as is usually the case, according to methods known to those skilled in the art. The actual value of the refraction of the reference subject is determined by this test.

[0089] The actual value of refraction is then subtracted from the value of the optical characteristics of the lenses used in each trial of the subjective test in order to obtain the answer of the reference subject in theoretical optical conditions relative to the actual value of refraction. It is then possible to compare the reference data obtained for each reference subject and in particular to average them.

[0090] The embodiments described herein can of course be combined, and an initial model can be determined based on data from a selected group of subjects to which it is adapted for comparison.

[0091] An example of an initial model obtained with such a protocol is shown in FIG.

[0092] Figure 2 shows the values ​​of the responses of the different referent subjects superimposed on the actual value of the refraction, centered at −0.5D.

[0093] More precisely, the ordinate indicates three different possible answers of the subjective test carried out.

[0094] These possible answers are, for example, as mentioned above: - the first choice or answer, i.e., better visual performance in the first actual optical condition, coded as "1", - a second choice or answer, i.e. better visual performance in the second actual optical condition, coded as "-1"; - a third choice or response, i.e., no difference is perceived between the first actual optical condition and the second actual optical condition, coded as "0"; It consists of:

[0095] The abscissa indicates the theoretical optical conditions.

[0096] In the example of FIG. 2, the theoretical optical condition is determined based on the value of the sphere of a lens placed in front of a reference subject, as will be explained below.

[0097] A group of reference subjects with a refraction of -0.5D plus or minus 0.2D is considered.

[0098] In this example, the answers of all the reference subjects of this group are centered around -0.5 D. This means that for the reference subjects of this group whose refraction was finally determined to be -0.53 D, the value of the obtained answer is plotted or stored corresponding to the value of the theoretical optical condition corresponding to the actual optical condition used during the subjective test, +0.03 D, thereby centering the results at -0.5 D.

[0099] A corrected reference data set is thereby generated, which contains the answers and the corresponding theoretical optical conditions.

[0100] The corrected reference data set is represented by a plotted square on Figure 2. Here, an initial model giving the probability of each explanatory answer of the set of explanatory answers for each theoretical optical condition of the plurality of theoretical optical conditions is obtained based on the corrected reference data set by determining a curve or equation that fits the corrected reference data set.

[0101] In the examples described and illustrated here, the general formula used for fitting is a general sigmoidal one, (1-2 / (1+e (-s*(x-x0)) ).

[0102] In the general formula for the sigmoid above, S is the maximum slope of the sigmoid, x0 is the relative position of the sigmoid, and x is the abscissa of the fitted data (the actual optical condition value). RMS is defined as the root mean square of the difference between the ordinate given by the answer from the data and the ordinate given by the formula being fitted.

[0103] Other general formulas can be used to determine the initial model by fitting or interpolating the reference data, for example, step functions, linear, polynomials, or other types of functions.

[0104] In the example initial model shown, the initial model is scaled to vary between 1, which corresponds to a 100% probability of the first choice or answer, and -1, which corresponds to a 100% probability of the second choice or answer.

[0105] In general, the slope of the portion of the initial model curve whose ordinate is comprised between 1 and -1 and which intersects with the abscissa is greater for subjects who are more sensitive to variations in the actual optical conditions, e.g., variations in the refractive power of a lens placed in front of the eye, and a decrease in refractive power for less sensitive subjects.

[0106] Alternatively, the initial model may also include a model data set that includes an average / weighted mean of the responses associated with corresponding theoretical optical conditions.

[0107] Preferably, the initial model is determined taking into account at least personal characteristics of the subject.

[0108] In the embodiment of the method according to the invention shown in FIG. 1, during a preliminary step at least personal characteristics of the subject are obtained (block 200 in FIG. 1).

[0109] The subject's personal characteristics may be any of the personal characteristics listed above.

[0110] Preferably, this personal characteristic relates to the type of visual impairment of the subject.

[0111] It may also be related to the age of the subject.

[0112] The personal characteristics may include, for example, age, and / or the type / value of refractive error, and / or the distance between the eye and the lens of the eyewear. The type of subjective test performed may also be taken into account.

[0113] For example, different initial models may be determined for subjects with myopia, hyperopia, subjects within a certain age range, and so on.

[0114] Preferably, the initial model is determined taking into account a number of personal characteristics of the subject, for example the initial model is determined via successive steps, each step taking into account one personal characteristic.

[0115] The initial model then uses all the data collected on the reference subject, i.e., - for each entry, the values ​​of the personal and optical characteristics in the corresponding trials of the subjective test (sphericity, cylinder, axis, etc.); - for the output, the response (or probability of response) associated with each trial, The output may be obtained using supervised learning (e.g., decision trees or neural networks) with, for example, sure choice 1 (100% probability), likely choice 1 (60% probability), no choice (0% probability), likely choice 2 (-60% probability), sure choice 2 (-100% probability). The output may be a discrete or continuous variable.

[0116] In particular, taking into account the personal characteristics of the subject, in particular taking into account the subject's sensitivity to variations in the actual optical conditions used, taking into account the subject's age and / or expected refractive error (nature and / or value), it is possible to determine an initial model, or a set of different initial models, associated with each personal characteristic, with a probability associated with each initial model.

[0117] For example, in the case of an initial model obtained by fitting the reference data with a sigmoid general equation, the slope of the part of the initial model curve that intersects the abscissa can be adjusted depending on the subject's sensitivity to variations in the actual optical conditions, e.g., to variations in at least the optical characteristics of at least the ophthalmic lens.

[0118] Here, the optical characteristics correspond to the actual optical conditions of a subjective test.

[0119] Subjects with higher sensitivity to variations in optical features will indeed benefit from a higher gradient in the initial model, as they will be able to perform the subjective test more quickly.

[0120] The slope of the initial model can also be adjusted depending on the age of the subject, the level of comprehension of the test (e.g. depending on whether the subject speaks the language of the test fluently) or the degree of fatigue at the moment of the test. Older or younger subjects, or subjects who are generally tired with poor comprehension, will benefit from using an initial model with a lower slope, introducing a more gradual test giving more trials that allow to confirm the answer obtained.

[0121] Finally, the slope of the initial model may also be adjusted according to the subject's refractive error: for example, for a subject with myopia and / or astigmatism, the higher the correction the subject requires, the lower the slope of the initial model.

[0122] Furthermore, the evolution of the subject's responses during the subjective test can also be taken into account.

[0123] Some subjects do indeed give different answers when the evolution of the actual optical condition is in one direction or the other. More precisely, when changing the refractive power of a lens, the subject's answers during a decrease in the refractive power may be different from those during an increase in the refractive power.

[0124] Due to the training effect, answers at the end of a subjective test may be closer to the answers expected according to the initial model than answers at the start of the subjective test.

[0125] Conversely, for some subjects, subject fatigue may result in answers at the end of the subjective test being further from the answers expected according to the initial model than the answers at the start of the subjective test.

[0126] The subject's behavior towards training effect / fatigue during the subjective test is also a personal characteristic and can be taken into account when determining the initial model (or a further modified model) by giving different weights to the answers collected in the reference data based on the duration of the subjective test when the answers were collected. Of course, more reliable answers (without fatigue after training) will be assigned a higher weight.

[0127] This process for determining the initial model is particularly useful when there are a large number of personal characteristics that are considered.

[0128] Additionally, the selection among all personal features and the weighting of each personal feature may be determined using machine learning algorithms and / or neural network methods.

[0129] This process can be used on a selected group of reference subjects.

[0130] In one embodiment, the initial model is determined based on a portion, average, or weighted average of the reference data set.

[0131] The part of the reference data set that is taken into account is preferably selected based on one or more reference personal characteristics of the reference subject.

[0132] More precisely, the part of the reference data set considered is selected to hold data obtained for reference subjects, one or more reference personal characteristics of which match the corresponding personal characteristics of the subject currently having their eyes tested.

[0133] The reference personal characteristics of the reference subject may be the same as the personal characteristics of the subject or may be within a predefined range with respect to the personal characteristics of the subject.

[0134] In other words, the multiple reference subjects are selected from a group of reference subjects having one or more personal characteristics that are the same or similar to a corresponding personal characteristic of the subject.

[0135] For example, for a myopic subject, the initial model is determined by considering a reference data set collected from a selected myopic reference subject. For a myopic subject with a known refraction of -1D, the initial model is determined by considering a reference data set collected from a selected myopic reference subject with a final refraction determined to be -1D, or a final refraction determined to be between -0.9D and -1.1D, or between -0.5D and -1.5D, or between 0D and -2D. The data of the selected reference subject can be corrected as described above to center on the actual refraction or visual impairment of each reference subject.

[0136] The initial model can then be used directly with data collected during subjective testing administered to subjects to determine magnitude.

[0137] However, in a preferred embodiment, the subjective tests are adjusted based on the initial model (block 400 of FIG. 1).

[0138] In practice, the computer is programmed to determine at least initial parameter values ​​of the subjective test based on the subject's personal characteristics.

[0139] Personal characteristics such as age, the subject's sensitivity to variations in the optical characteristics of the lenses, level of understanding and / or fatigue level, the nature and value of refractive error may be taken into particular consideration.

[0140] If it is determined that the subject is unlikely to adapt, e.g. for an elderly subject (adult), the initial value of the subject's eye refraction, measured objectively, e.g. using an autorefractometer, is used as the starting value for the subjective test without any modification.

[0141] If the subject is determined to have a tendency to accommodate, for example for a young subject (child), a hyperopic subject, or a fatigued subject, the initial value of the subject's refraction is increased by an additional value. The higher the subject's tendency to accommodate is determined, the higher the additional value for the initial value of refraction is determined.

[0142] For example, an initial value of an optical characteristic of an optical component placed in front of a subject's eye, or an initial step value for increasing or decreasing this optical characteristic, may be determined taking into account the initial model.

[0143] For example, in the situation where an initial model based on the average data of FIG. 2 is taken into account, if in a first trial an optical lens with a refractive power equal to −0.375 D is used, then answer 2 is expected based on the initial model. A second trial is performed with an optical lens of −0.75 D, and answer 1 is expected. If the answer given by the subject coincides with the expected answer, the initial model is confirmed, otherwise it will be adjusted, e.g. modified taking into account the subject's answer.

[0144] Generally, based on the initial model and the initial parameter value (e.g., the value of the past prescription), the computer is programmed to perform two first trials with the value of the actual optical condition, so that during the two successive first trials, one answer 1 and one answer 2 are obtained. This allows to reduce the total number of trials required.

[0145] The computer is programmed to consider the initial model to determine at least initial parameter values ​​for the subjective test.

[0146] A subjective test is then administered to the subjects.

[0147] According to the invention, one or more processors of a computer include: a) collecting results of a subjective test performed by asking subjects to describe their visual performance in each of a plurality of actual optical conditions by selecting, for each actual optical condition, one explanatory answer from a set of possible explanatory answers, the results including each selected explanatory answer and the corresponding actual optical condition (block 500 of FIG. 1 ); b) determining a magnitude value by considering the initial model and each explanatory response collected (blocks 800, 900 in FIG. 1); It is programmed like this.

[0148] Step a) During the subjective test, subjects are asked to describe their visual performance in multiple real-world optical conditions by selecting one explanatory answer from a set of possible explanatory answers.

[0149] This subjective test can be carried out within the method according to the invention or independently of it.

[0150] Each of the plurality of actual optical conditions typically corresponds to a given value of an optical characteristic, such as sphere, cylinder, axis, or transmission coefficient, of an optical component, such as a test filter or test lens, placed in front of a subject's eye.

[0151] Subjective tests are usually carried out using a specific device known as a "phoropter", which comprises either at least one test optical component with a variable optical characteristic, such as a test lens with a variable optical power, or a plurality of test optical components with different fixed predetermined optical characteristics, such as a plurality of lenses with different fixed predetermined optical powers, and at least one support adapted to support the test optical component or one of the plurality of test optical components. The support is adapted to be placed in front of the subject's head in order to position the test optical component supported by the support in front of the subject's eye to be tested.

[0152] Variable lenses are described, for example, in the following documents: US Pat. No. 5,399,633, US Pat. No. 5,499,623, US Pat. No. 5,499,633, or US Pat. No. 5,499,623.

[0153] The device may also comprise other test optical components with different optical characteristics, such as spherical lenses, cylindrical lenses, prisms, linear or circular polarizing filters, color filters, transmission filters, narrow holes, Badal systems, mirrors, active lenses, deformable mirrors, SLMs (Spatial Light Modulators), Alvarez lenses, etc.

[0154] In practice, a subject's vision is tested during a subjective testing protocol using a phoropter, which successively places test optical components, such as lenses having different values ​​of an optical characteristic, in front of at least one eye of the subject.

[0155] For the test lenses, the refractive power is increased or decreased by a predetermined step value from one step of the subjective test to the next, typically 0.25 diopters (D) or 0.125 D. Successive steps of the subjective test are referred to herein as "trials."

[0156] For each test lens placed in front of the eye, the subject is asked to indicate a visual assessment that corresponds to an indication of a preferred visual state out of the two presented visual states, or whether they cannot decide between the two visual states. The two visual states can, for example, correspond to the subject's vision through a previous lens and the subject's vision through a current lens, or correspond to the subject's vision of two different images through a current lens.

[0157] In practice, this part of the test protocol can correspond, for example, to the assessment given by the subject during a duochrome test, during which the subject is presented with an image that includes a target displayed on a red background on the one hand and a target displayed on a green background on the other hand. If the subject has better vision through the current lens with a target on a red background, the sphere should be reduced in the next lens presented, and if the subject has better vision through the current lens with a target shown on a green background, the sphere should be increased in the next lens presented.

[0158] Alternatively, for each current lens placed in front of the subject's eye, the subject is asked to rate the quality of his or her vision through the current lens compared to the previous lens, asking whether the current lens makes the subject see better or worse than the previous lens, or whether he or she cannot decide between the two. In this last case, the two lenses provide the subject with similar vision quality.

[0159] The phoropter may be part of the device according to the invention described herein or may be separate therefrom, in this last case it may be provided with means of communication with the device according to the invention.

[0160] As mentioned above, in general, a set of explanatory answers will be e.g. - Better visual performance in first real optical conditions, - Better visual performance in second real optical conditions, - no difference is perceived between the first actual optical condition and the second actual optical condition, Includes answers consisting of:

[0161] The first and second actual optical conditions may correspond to viewing the same image with different test optical components having different values ​​of an optical feature, or to viewing different images with the same test optical component, such as an image including one visual target displayed on a red background and another visual target displayed on a green background.

[0162] Step b) In step b), the computer is, for example, programmed to compare the initial model with each of the collected explanatory responses and determine a magnitude value based on this comparison.

[0163] If the initial model includes an initial model curve, the computer in step b) b1) plotting each collected explanatory answer selected by the subject against a corresponding actual optical condition and overlaying an initial model curve on the resulting plot such that the initial model curve is fitted to the plot; b2) determining a magnitude value taking into account the relative position of the initial model curve and the plot; The method is programmed to perform the substeps of:

[0164] The step of plotting the collected explanatory responses does not imply that the plot is displayed in any way: the plot and / or other curves may or may not be displayed for viewing by the user and / or subject.

[0165] In one embodiment, the subjective values ​​of the optical characteristics of at least the corrective lens fitted to the subject's eye are determined directly by comparing responses collected for the subject with an initial model.

[0166] In step b1), the initial model is not modified to fit the plot, but the relative positions of the model curve and the plot are modified in order to globally minimize the distance between the model curve and the plot, which distance is minimized, for example, using quadratic optimization.

[0167] Using the initial model determined in the example of FIG. 2, positioning of the initial model with respect to the data collected for the subject may give the actual refraction of the subject at the intersection point between the initial model and the abscissa.

[0168] Alternatively, the computer is programmed to perform the subjective test.In the embodiment of Figure 1, block 500 corresponds to performing the subjective test and collecting corresponding data.

[0169] In this case, the computer is programmed to adjust the parameters of the subjective test taking into account the initial model (block 400 of FIG. 1), e.g., to determine the actual optical conditions that will subsequently be used to perform the subjective test taking into account the initial model.

[0170] Advantageously, step b1) is performed at each trial of the subjective test, in other words for each answer given by the subject. For each new answer given by the subject, this answer is added to the plot and the relative positions of the model curve and the plot are modified so that the distance between the model curve and the plot is globally minimized. Then, at each trial, an intermediate value of the magnitude can be determined and the parameters of the subjective test can be modified before performing the next trial. In particular, the step value between two successive values ​​of the optical characteristic of the test lens used during the test can be adjusted. Alternatively, the next value of the optical characteristic of the test lens can be determined directly.

[0171] The subjective test is then adjusted taking into account the data already collected on the subject (arrow 501 in FIG. 1).

[0172] An example of this process is shown in Figures 3 to 7. In these figures, the squares indicate the location of the subjects' plotted data, i.e. the answers given in the corresponding real optical conditions, here the sphere in diopters of the test lens. The initial model is represented by a curve.

[0173] Figure 3 shows the results of the first trial, where the subject gives only one answer. The initial model is positioned to pass through this single point. Thus, the location of the initial model curve is uncertain.

[0174] After the second trial, the second response is plotted and the initial model curve is moved to fit the plot (Figure 4).

[0175] After the third trial, the third answer is plotted and the initial model curve is shifted accordingly.

[0176] 6 and 7 show the corresponding next two trials.

[0177] The intersection point PV of the initial model curve with the abscissa gives the predicted spherical refraction of the eye (Figure 7).

[0178] It is therefore possible to adjust the diopter variation step value of the next test lens so that the next test lens has a sphere that is closer to the predicted spherical refraction of the eye.

[0179] The computer can be programmed to determine a magnitude value based on the position of the initial model curve relative to the plot when this position is determined after a predetermined number of trials, or if this position does not change between two consecutive trials of the subjective test by more than a predetermined amount, for example, when this position is determined after at least 4, 10, or 20 trials, or when this position does not change by more than 0.25D, 0.12D, or 0.06D between two consecutive trials of the subjective test.

[0180] The use of an initial model makes it possible to quickly obtain the exact location of the curve.

[0181] If the initial model includes an initial data set, the computer in step b) - statistically processing the initial data set and the collected narrative responses; - determining a magnitude value taking into account this statistical process; and In practice, a law explaining the variability of the reference data set is determined by a statistical process and then this law is applied to the responses of the subjects during the subjective test.

[0182] According to an advantageous feature of the device and method according to the invention, the initial model may be modified at any trial of the subjective test, i.e. with every new test optical component proposed to the subject (block 600 in FIG. 1).

[0183] In particular, the initial model may be modified in any trial of the subjective test based on at least one of the previous answers collected for the subject (arrow 502 in FIG. 1).

[0184] In one embodiment, the initial model may be determined by considering a first personal characteristic of the subject. In any trial of the subjective test, the initial model may be modified to consider a second personal characteristic of the subject, different from the first personal characteristic. The second personal characteristic may be considered in addition to or instead of the first personal characteristic.

[0185] For example, the subject's behavior during the response, i.e., facial features, facial expressions, voice, hesitation, the time elapsed between the presentation of each new actual optical condition and the subject's response, The initial model can be modified in real time to take into account

[0186] The time elapsed between the presentation of each new actual optical condition and the subject's response can be compared to a threshold, and if the time elapsed exceeds the threshold, the response is not considered.

[0187] In one embodiment, the initial model may be modified to take into account responses collected for a subject, who is then included in the reference subjects and whose responses are used to determine the model.

[0188] The resulting corrected model is then used to determine the magnitude.

[0189] In this case, the computer in step b) - modifying the initial model to obtain a modified model taking into account each explanatory answer of the subject and the corresponding actual optical conditions; - comparing the modified model with each of the collected explanatory responses (block 700 of FIG. 1 ) and determining a magnitude value based on this comparison; The method is programmed to perform the substeps of:

[0190] The modified model is determined and used in the same manner as the initial model described above. The modified model includes a modified model curve, a modified model equation between the solution and the theoretical optical conditions, and a modified model data set. may include at least one of:

[0191] If the correction model includes a correction model curve, the computer in step b) - plotting each collected explanatory answer selected by the subject against a corresponding actual optical condition and overlaying the modified model curve on the resulting plot such that the modified model curve is fitted to the plot; - determining a magnitude value taking into account the relative position of the modified model curve and the plot; The method is programmed to perform the substeps of:

[0192] Alternatively, if the revised model includes a revised data set, the computer in step b) - statistically processing the revised data set and the collected narrative responses; - determining a magnitude value taking into account this statistical process; and The method is programmed to perform the substeps of:

[0193] In practice, the computer is programmed to determine at least one of the actual optical conditions used to perform the subjective test by taking into account the correction model. In particular, the computer may be programmed to determine each of the actual optical conditions used to perform the post-hoc trials of the subjective test by taking into account the correction model.

[0194] The computer is programmed to determine a magnitude value based on the position of the modified model curve relative to the plot when this position is determined for a predetermined number of trials or when this position does not modify by more than a predetermined amount between two successive trials of the subjective test (block 800 of FIG. 1).

[0195] Further, the computer is programmed to compare each of the collected explanatory answers corresponding to the actual optical conditions with the initial model or the revised model, and if this comparison indicates that the difference between a particular collected explanatory answer corresponding to a particular actual optical condition and the respective revised initial model exceeds a predetermined threshold, then this particular collected explanatory answer is identified as inconsistent (block 900 of FIG. 1 ).

[0196] In particular, a criterion that calculates the distance from the curve of the initial or revised model can be used to detect false or uncertain answers: If the distance between the plot of the answer and the curve of the initial or revised model is greater than a predefined threshold, or greater than it would be if it were a "don't know" answer, then the answer is identified as inconsistent.

[0197] Thus, an indicator of the confidence level associated with each measured subjective value of the optical characteristic may be determined based on this distance between the plot of the answer and the curve of the initial or modified model, for example giving an indicator of a higher confidence level for the answer corresponding to a plot closer to the model.

[0198] If such conflicting answers are detected, an alert may be issued to the subjective test operator's destination.Conflicting answers are preferably not considered for purposes of determining magnitude.

[0199] Preferably, the subjective test trial in which conflicting answers were collected is repeated and alternative answers are collected to replace the conflicting answers that were not considered (arrow 901 in FIG. 1).

[0200] Preferably, if the number of conflicting answers detected during the subjective testing exceeds a predetermined threshold, the initial model or the revised model is modified to reduce the number of conflicting answers (arrow 902 in FIG. 1).

[0201] The initial or modified model is then modified: for example, a model based on an average reference set of data can be modified to a model based on the distribution of the reference data set, or a model based on the personal characteristics of the subject can be modified to a more general model based on all the reference data.

[0202] Aberrant behavior may be detected: for example, younger subjects tend to answer faster than older subjects. If a younger subject is slower, this may be due to a specific problem or a misunderstanding on the part of this subject.

[0203] Typically, during subjective testing, an initial value of the actual optical condition is determined taking into account the subject's personal characteristics, such as past prescriptions, if any, and an initial model selected or determined for this subject. A next value of the actual optical condition is determined by the computer based on the initial model.

[0204] For example, as already mentioned, the computer is programmed to perform the first two trials with actual optical condition values, resulting in one answer 1 and one answer 2 during the successive performance of the first two trials.

[0205] The correspondence between the actual responses and the expected responses according to the initial model is monitored: the subject's actual responses for a given actual optical condition are compared with the expected responses based on the initial model for a corresponding theoretical optical condition.

[0206] If the actual answers match the expected answers, the initial model can be retained or modified for further improvement. If the number of actual answers that differ from the expected answers falls below a first discrepancy threshold, the actual answers can be considered to match the expected answers.

[0207] If the actual answers differ from the expected answers, then either the initial model is discontinued and the subjective steps are restarted in the conventional manner, or the initial model is modified. If the number of actual answers that differ from the expected answers exceeds a second discrepancy threshold, then the actual answers can be considered to differ from the expected answers.

[0208] According to a first possibility, another predefined model can be tried.

[0209] According to a second possibility, currently collected data for the subject can be added to the reference data, and the revised model is determined based on this updated reference data which includes the data collected for the subject.

[0210] According to a third possibility, a new model can be determined based on data collected on the subject, current and past data. This last solution is particularly useful when past data is available.

[0211] In fact, the present invention also allows data from past eye examinations to be taken into account, allowing a better understanding of the evolution of the behavior. This can be used to prevent and / or detect the progression of cataracts, or to prevent and / or detect other evolutionary refractive errors (myopia) or pathologies (such as age-related macular degeneration). For example, determining that a past initial model used on a successful subject does not fit this subject at all later may be an indication of a new problem, such as cataracts.

Claims

1. 1. A system for determining a magnitude value associated with a subjective value of an optical characteristic of at least a corrective lens fitted to an eye of a subject by performing a subjective test in which the subject is asked to describe his / her visual performance in a plurality of real optical conditions by selecting one explanatory answer from a set of possible explanatory answers, the system comprising: a computer having one or more memories and one or more processors, an initial model giving a probability of each explanatory answer of the set of explanatory answers for each theoretical optical condition of a plurality of theoretical optical conditions is stored in one of the one or more memories of the computer; said one or more processors of said computer a) collecting (500) results of the subjective test, which is performed by asking the subject to describe his / her visual performance in each actual optical condition of the plurality of actual optical conditions by selecting, for each actual optical condition, one explanatory answer from the set of possible explanatory answers, said results including each selected explanatory answer and the corresponding actual optical condition; b) determining (800, 900) the value of the magnitude by considering the initial model and each collected explanatory answer; The system is programmed as such.

2. 2. The system of claim 1, wherein in step b), the computer is programmed to compare the initial model with at least one collected explanatory answer by determining a distance between each explanatory answer and a curve or a data set representing the initial model, and to determine the value of the magnitude based on this comparison.

3. The initial model includes an initial model curve, and the computer in step b) - plotting at least one collected explanatory answer selected by said subject against said corresponding actual optical condition and superimposing said initial model curve on said obtained plot such that said initial model curve is fitted to said plot; - determining said value of said magnitude taking into account the relative position of said initial model curve and said plot; 3. The system of claim 1 or 2, programmed to perform the substeps consisting of:

4. The initial model comprises an initial data set, and the computer in step b) - statistically processing said initial data set and said collected explanatory responses; determining said value of said magnitude taking into account this statistical process; The system according to any one of claims 1 to 3, programmed to perform the substeps consisting of:

5. The computer in step b) - modifying said initial model to take into account each explanatory response of said subject and said corresponding actual optical conditions to obtain a modified model; - comparing said revised model with each collected explanatory response and determining said value of said magnitude based on said comparison; 2. The system of claim 1, programmed to perform the substeps consisting of:

6. The correction model comprises a correction model curve, and the computer in step b) - plotting each collected explanatory answer selected by the subject against the corresponding actual optical condition and overlaying the modified model curve on the resulting plot such that the modified model curve is fitted to the plot; - determining said value of said magnitude taking into account the relative position of said modified model curve and said plot; 6. The system of claim 5, programmed to perform the substeps consisting of:

7. The modified model includes a modified data set, and the computer in step b) - statistically processing said modified data set and said collected explanatory responses; determining said value of said magnitude taking into account this statistical process; 7. The system according to claim 5 or 6, programmed to perform the substeps consisting of:

8. The system of any one of claims 1 to 7, wherein the initial model and / or the revised model take into account one or more personal characteristics of the subject.

9. The set of explanatory answers: - better visual performance in first real optical conditions, - better visual performance in second real optical conditions, - no difference is perceived between the first and the second actual optical conditions; The system according to any one of claims 1 to 8, comprising a response consisting of:

10. The initial model is statistically determined based on a reference dataset previously collected during execution of the subjective test on a plurality of reference subjects, the reference dataset comprising: - the personal characteristics of each referent; - the actual optical conditions and corresponding answers of each reference subject, The system according to any one of claims 1 to 9, comprising:

11. The system of claim 10, wherein the initial model is determined based on an average or weighted average of a portion of the reference dataset selected based on one or more personal characteristics of the reference subject, and / or the initial model is determined using a machine learning algorithm and / or a neural network algorithm.

12. The system of claim 10 or 11, wherein the plurality of reference subjects are selected from a group of reference subjects as having one or more personal characteristics that are the same or similar to the corresponding personal characteristics of the subject.

13. The initial model comprising an initial model curve, wherein the computer in step b) - plotting at least one collected explanatory answer selected by said subject against said corresponding actual optical condition and superimposing said initial model curve on said obtained plot such that said initial model curve is fitted to said plot; - determining said value of said magnitude taking into account the relative position of said initial model curve and said plot; the method being programmed to execute the substeps consisting of:

13. The system of claim 1, wherein the computer is programmed to determine the value of the magnitude based on a position of the initial or modified model curve relative to the plot when the position is determined after a predetermined number of trials or when the position does not modify by more than a predetermined amount between two successive trials of the subjective test.

14. A system according to any one of claims 1 to 13, wherein the computer is programmed to compare each of the collected explanatory answers corresponding to actual optical conditions with the initial model or the modified model, and if the comparison indicates that a difference between a particular collected explanatory answer corresponding to a particular actual optical condition and the respective modified initial model exceeds a predetermined threshold, the particular collected explanatory answer is identified as being inconsistent.

15. 1. A method for determining a magnitude value associated with a subjective value of an optical characteristic of at least a corrective lens fitted to an eye of a subject through a subjective test in which the subject is asked to describe his / her visual performance in a number of real optical conditions by selecting one explanatory answer from a set of possible explanatory answers, comprising: i) providing an initial model (300) that gives a probability of each explanatory answer of the set of explanatory answers for each theoretical optical condition of a plurality of theoretical optical conditions; j) carrying out the subjective test by asking the subject to describe his / her visual performance in each real optical condition of the plurality of real optical conditions by selecting for each real optical condition one explanatory answer from the set of possible explanatory answers; k) collecting (500) each narrative response of the subject and corresponding actual optical conditions; l) determining (800, 900) the value of the magnitude by considering the initial model and each collected explanatory answer; A method comprising the steps of:

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