Systems and methods for identifying rounded values ​​of optical characteristics of ophthalmic lenses adapted to provide refractive correction to improve a subject's visual acuity

Abstract

The present invention provides a system for identifying rounded values ​​of optical characteristics of an ophthalmic lens adapted to provide refractive correction to improve at least the visual acuity of a subject, the system comprising: a) a step (400) of identifying a first test value of the optical characteristic and a first change increment of the optical characteristic; b) a step (500) of performing a first trial of the subjective test, wherein two first different optical situations are identified based on at least the first test value; c) a step (600) of identifying a second test value of the optical characteristic based on the first test value, the first change increment, and a result of the first trial; d) a step (600) of performing a first trial of the subjective test, wherein two first different optical situations are identified based on at least the first test value; a) performing a second trial (700), wherein two second different optical situations are identified based on at least a second test value; b) identifying an intermediate value of an optical characteristic (800) based on the results of the first trial and the results of the second trial; c) identifying a rounded value of the optical characteristic (900) by rounding the intermediate value to a reference value, wherein the rounding modifies the refractive correction of the ophthalmic lens by less than a predetermined base refractive power value;

Description

[Technical Field]

[0001] The present invention relates to a system and method for identifying rounded values ​​of optical characteristics of an ophthalmic lens adapted to provide refractive correction to improve a subject's visual acuity. [Background technology]

[0002] The manufacture of ophthalmic lenses adapted to improve a subject's visual acuity requires the determination of values ​​of the optical characteristics of said ophthalmic lenses tailored to the subject. To determine these values ​​of said optical characteristics, eye care professionals usually perform subjective tests on the subject using appropriate optical equipment. Many publications describe instruments and methods for determining these values ​​of the optical characteristics of ophthalmic lenses. These optical characteristics may include, for example, spherical power, cylindrical power or cylindrical axis.

[0003] Typically, the subjective test includes several steps, hereinafter referred to as trials, in each of which the subject is required to compare two different optical situations taking into account the test values ​​of the optical features. Thus, the subjective test corresponds to a series of trials. The subject's feedback regarding this comparison is hereinafter referred to as the subject's answer, and in response, the eye care professional increases the test value and presents the subject with two new different optical situations based on the increased test value in the next trial of the subjective test. This process is repeated until a specific answer or combination of answers is provided by the subject. Thus, the prescription values ​​of the optical features are usually determined depending on the test values ​​used in the last trial of the subjective test.

[0004] To determine the exact value of an optical characteristic, new devices allow eye care professionals to use small increments between successive trials of subjective testing, for example, phoropters using variable lenses allow the use of increments of less than 0.2D.

[0005] In this regard, the specified values ​​of the optical characteristics are precise but do not take into account the typical values ​​of the optical characteristics of commercially available ophthalmic lenses.

[0006] Ophthalmic lenses are not actually commercially available with any value of their optical characteristics: only a predetermined set of values, hereafter called "standard values", for each optical characteristic is available.

[0007] Furthermore, devices and methods that use small increments between successive trials of subjective testing typically increase the testing time and run the risk of the subject not being able to tell any difference between two successive trials of subjective testing. Thus, eye care professionals may need to shorten the testing time because the subject may lose patience, become stressed, experience eye strain, or become less attentive during the test. Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, there is also a need for an apparatus and method in which the increments allow the subject to clearly understand the subjective test on the one hand, and on the other hand, reduce the test time while not exceeding the exact value of the optical characteristic. [Means for solving the problem]

[0009] It is therefore an object of the present invention to provide a system for identifying rounded values ​​of optical characteristics of an ophthalmic lens adapted to provide refractive correction to improve at least the visual acuity of a subject, said system comprising: an optical instrument for performing a subjective test comprising assessing the visual performance of a subject placed in two different optical situations; and a computer, a) identifying a first test value of the optical characteristic and a first increment of change of the optical characteristic; b) performing a first trial of the subjective test using the optical instrument, wherein two first different optical conditions are identified based on at least a first test value; c) determining a second test value of the optical characteristic based on the first test value, the first change increment and the results of the first trial performed in step b); d) performing a second trial of the subjective test using the optical instrument, wherein two second different optical conditions are identified based on at least a second test value; e) determining an intermediate value of the optical characteristic based on the results of the first trial performed in step b) and the results of the second trial performed in step d); f) determining the rounded value of the optical characteristic by rounding the intermediate value to a reference value, wherein the rounding modifies the refractive correction of the ophthalmic lens by less than a predetermined base power value. and a computer including one or more processors programmed to implement the method.

[0010] "Correcting the refractive correction of said ophthalmic lens by less than a predetermined base power value" means that the difference in the refractive correction provided by an ophthalmic lens that presents a value of an optical characteristic equal to the mean value and an ophthalmic lens that actually presents a rounded value of the optical characteristic is less than the base power value. The "refractive correction" of a lens corresponds to the overall optical power of the lens, which is obtained by the optical characteristics of the lens, such as spherical power, cylindrical power and cylindrical axis.

[0011] Reference values ​​refer to, for example, standard predetermined values. Reference values ​​include, for example, a predetermined set of standard values ​​of corresponding optical characteristics that can be ordered or manufactured.

[0012] Thus, with the system according to the invention, the rounded value of the optical characteristic may correspond to a standard value of the optical characteristic, thereby obtaining a value of the desired optical characteristic that matches the standard value currently suitable for manufacturing lenses.

[0013] These standard values ​​of a given set are preferably regularly spaced discrete values, and the cardinal frequency value therefore represents this regular interval, which is in fact equal to the difference between two consecutive standard values ​​of the set of standard values.

[0014] In the examples described herein, the standard value is equal to a multiple of the base power value. Multiple means that the standard value is a product of the base power value and an integer. For example, spherical powers are often prescribed and manufactured as multiples of 0.25D.

[0015] In this regard, the processor may be programmed in step e) to round the intermediate value of the optical feature to the nearest or second nearest multiple of the predetermined basic power value if the intermediate value is different from a multiple of the predetermined basic power value.

[0016] The system according to the invention may also take into account the personal characteristics of the subject, which makes the system adaptive, where personal characteristics are generally any characteristics relating to the subject's physical or optical condition.

[0017] Thus, the processor may be further programmed in step a) to identify the first change increment based on at least a first personal characteristic of the subject.

[0018] By adjusting the change increment, here not just the first change increment but any successive change increments, it is possible to reduce the number of subjective test trials required before identifying an intermediate value of the optical characteristic, for example.

[0019] If the difference between two different optical conditions is based on a change increment, the change increment can be tailored to the subject to prevent ambiguous responses when the subject does not know the difference between the two optical conditions.

[0020] For example, for a spherical power specific test, the change increment may increase with the age of the subject: it may be 0.30D for a 20-year-old subject with good vision, 0.55D for a 50-year-old subject with myopia, and 1.30D for an 85-year-old elderly patient with multiple medical conditions.

[0021] The processor may be further programmed in step f) to round the intermediate value according to a rounding method that depends on at least a second personal characteristic of the subject or the type of subjective test performed, where the second personal characteristic may be the same as the first personal characteristic or another personal characteristic different from the first personal characteristic.

[0022] This allows, for example, the selection of the nearest or second-nearest multiple of the predetermined basic power value depending on the age of the subject. For example, the intermediate value can be rounded to the nearest or second-nearest lower multiple for a young subject to prevent the person's eyes from becoming accustomed to the correction. The intermediate value can be rounded to the nearest or second-nearest higher multiple for an elderly subject to allow the correction to sufficiently improve the person's vision.

[0023] As another example, for myopic subjects, the intermediate value is preferably rounded to the nearest or next nearest multiple, whichever is lower, and for hyperopic subjects, the intermediate value is preferably rounded to the nearest or next nearest multiple, whichever is lower.

[0024] For subjects requiring correction primarily for distance vision, e.g., for professional drivers, the midpoint value is preferably rounded to the nearest or second nearest multiple, whichever is lower, and for subjects requiring correction primarily for near vision, the midpoint value is preferably rounded to the nearest or second nearest multiple, whichever is higher.

[0025] Intermediate values ​​may also be rounded to minimize the difference between the rounded value and the value obtained from the previous optical instrument of interest.

[0026] Other advantages and non-limiting features of the system according to the present invention are as follows: - the first personal characteristics include at least one of the following data about the subject: age, type of refractive error, visual acuity, dissatisfaction with one's visual performance or current vision correction devices, medical history data including the subject's current correction, medical condition, visual needs or activities, selected spectacle frames, selected ophthalmic lenses, optical characteristics of the subject's eyes; the second personal characteristics include at least one of the following data about the subject: age, type of refractive error, visual acuity, dissatisfaction with one's visual performance or current vision correction devices, medical history data including the subject's current correction, medical condition, visual needs or activities, selected spectacle frames, selected ophthalmic lenses, optical characteristics of the subject's eyes; - the processor is further programmed in step b) to identify two first different optical situations based on the first change increment; - the subject, during the subjective testing, - displaying targets placed in red and green environments; - Adding a cross cylinder in front of the subject's eye in two different positions, - placing two lenses of different spheres in front of the subject's eye; - Displaying two targets of different sizes, - Place different lenses in front of the subject's right and left eyes and placing the two different optical conditions in the two different optical states by realizing at least one of the following: - Optical characteristics: - the spherical refractive power of said ophthalmic lens, - the astigmatism power of said ophthalmic lens, - the astigmatism axis of said ophthalmic lens; - The difference in spherical power between two ophthalmic lenses placed in front of the right and left eyes and - The processor g) identifying a current test value and a current increment of change based on the results of a previous trial and the previous test value corresponding to said previous trial; h) performing a current trial of the subjective test, which comprises assessing the subject's visual performance in two current different optical situations identified based on at least the current test values; i) modifying the current test value based on that of the current trial and the current change increment, and modifying the current change increment based on the results of the current trial; and Optionally, repeating steps h) and i). and further programmed to perform the processor is programmed in step e) to determine the intermediate value based on a current test value; - the processor is further programmed to determine in step g) and / or modify in step i) a current change increment based on a degree of certainty of the results of the previous trial performed; - the current change increment is smaller than the predetermined basic value; - the processor is further programmed in step i) to modify the current change increment by decreasing its value; - The processor - if the current test value increases and decreases or decreases and increases consecutively on the last two consecutive trials, or - the second test value is greater than the first test value and the current test value determined in step g) is less than the second test value, or - if the second test value is less than the first test value and the current test value determined in step g) is greater than the second test value; further programmed to perform step e), - The processor - if during the final trial, the subject evaluates the two final different optical conditions as providing equivalent visual performance, and - if, during a preceding trial performed before the final trial, the subject rates one of two different preceding optical conditions as providing better visual acuity quality than the other preceding optical condition; It is further programmed to perform step e).

[0027] The present invention also relates to a method for identifying rounded values ​​of optical characteristics of an ophthalmic lens adapted to provide refractive correction to improve the visual acuity of a subject, which may be performed by the above-mentioned system and includes steps a) to f).

[0028] The following description, supplemented by the accompanying drawings, which should be taken as non-limiting examples, serves to make clearer the understanding of the invention and how it can be put into practice. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a schematic diagram of a system according to the present invention; [Figure 2] FIG. 2 is a block diagram that schematically illustrates the steps of a method for identifying rounded values ​​of optical characteristics of an ophthalmic lens adapted to provide refractive correction to improve a subject's visual acuity, according to the present invention, performed by the system of FIG. [Figure 3] 1 is a schematic diagram of a first decision tree of a first sequence of first subjective test trials for identifying the spherical power of an ophthalmic lens, programmed in a first embodiment of the system of FIG. 1, wherein each trial of the first subjective test includes displaying a target placed in a red and green environment. [Figure 4] 10 is a schematic diagram of a second decision tree of a second sequence of second subjective test trials aimed at identifying the astigmatic axis of an ophthalmic lens, programmed in a second embodiment of the system of FIG. 1, each trial of the second subjective test including adding two cross cylinders in different positions in front of the subject's eye. [Figure 5]FIG. 10 is a diagram of a user interface that an eye care professional can use to perform the determination of rounded values ​​of optical features. [Figure 6] 10 is a schematic diagram of a third decision tree of a third sequence of third subjective test trials aimed at identifying the spherical power of an ophthalmic lens, programmed in a third embodiment of the system of FIG. 1, wherein each trial of the third subjective test includes placing two lenses of different spheres in front of a patient's eye. [Figure 7] FIG. 10 is a schematic diagram of a fourth decision tree for a fourth sequence of trials of a fourth subjective test programmed in a fourth embodiment of the system of FIG. 1 for identifying the spherical power of an ophthalmic lens in a relaxed state of accommodation of a subject, wherein each trial of the fourth subjective test includes displaying two targets of different sizes. [Figure 8] 10 is a schematic diagram of a fifth decision tree for a fifth sequence of trials of a fifth subjective test programmed in a fifth embodiment of the system of FIG. 1 aimed at determining the binocular balance of two ophthalmic lenses fitted to a subject's eyes, each trial of the fifth subjective test including displaying and placing a different lens in front of the patient's right and left eyes. DETAILED DESCRIPTION OF THE INVENTION

[0030] FIG. 1 shows a system 1 according to the invention, comprising an optical instrument 2 and a computer 3 .

[0031] The optical instrument 2 is adapted to perform subjective testing trials by presenting the subject with two different optical conditions.

[0032] As will be explained in more detail below, different subjective tests may be performed to identify the optical characteristics of an ophthalmic lens. Each subjective test is associated with a specific optical situation that is presented to the subject. This optical situation, and therefore the optical equipment adapted to present it, may have different characteristics depending on the optical characteristics identified through the corresponding subjective test.

[0033] The optical characteristics may include dioptric optical characteristics, ie optical characteristics measured in diopters, or directional optical characteristics, ie optical characteristics representing angles measured, for example, in degrees.

[0034] Here, the optical characteristics include, for example, one or more of spherical refractive power, astigmatism power, astigmatism axis, and difference in sphere between the left and right eyes.

[0035] For this reason, self-examination - Red-green test to determine spherical power, - Cross cylinder test to identify the astigmatism power and / or axis, - A relaxed visual acuity test to determine spherical power, - relaxed visual acuity test to determine spherical power; - Binocular balance test may include one or more of:

[0036] Detailed examples are provided below.

[0037] Therefore, the corresponding optical instruments are: - placing a trial lens with optical characteristics equal to the test value in front of the subject's eye and simultaneously displaying a target containing a symbol placed on a red or green background; - To display a target with multiple elements and add cross cylinders placed successively in front of the subject's eye at two different positions according to the astigmatism axis test value, - successively placing two trial lenses with optical characteristics equal to two different test values ​​(different spheres) in front of the subject's eye to display the target; - A trial lens with optical characteristics equivalent to the test value is placed in front of the subject's eye, and two targets of different sizes are displayed. - Place different trial lenses simultaneously in front of the subject's right and left eyes, displaying a target for each eye This includes optical means for

[0038] In practice, the optical instrument 2 comprises, for example, a phoropter with a trial lens having variable optical characteristics.

[0039] As a variant, the optical instrument 2 may also include a set of trial lenses with different values ​​for said optical characteristics.

[0040] Additionally, the optical instrument 2 includes a device for displaying the target, which can be any kind of display device, such as a screen, which can include active digital screens, such as liquid crystal displays, or passive screens and projection devices.

[0041] Depending on the subjective test to be performed, the optical instrument 2 may also include a cross cylinder.

[0042] The optical device 2 will be described in more detail with respect to the first to fifth subjective tests shown in FIGS.

[0043] The computer 3 includes, for example, one or more processors and one or more memories, wherein instructions for performing the steps shown in Figure 2 for identifying rounded values ​​of optical characteristics of an ophthalmic lens adapted to provide refractive correction to improve the subject's vision are stored in the one or more memories, and the one or more processors are accordingly programmed to perform these steps.

[0044] Here, the computer 3 includes a user screen for displaying information to the eye care professional, and input devices for enabling the eye care professional to interact with the computer, which may include a keyboard, a mouse, a touch screen, voice control means, the user screen itself if it is touch sensitive, or any other known input means.

[0045] An example of a user interface displayed on a user screen is shown in FIG. 5, which will now be used to explain in more detail the second subjective test performed by the method of the present invention.

[0046] Here, the computer 3 includes communications equipment that allows the computer to be connected to the optical device 2 and to be able to command it, for example to command the target screen of the optical device 2 .

[0047] FIG. 2 illustrates a method performed by system 1 for identifying rounded values ​​of optical characteristics of an ophthalmic lens adapted to provide refractive correction to improve a subject's visual acuity.

[0048] In all embodiments of the present invention, the method comprises: a) identifying a first test value of the optical characteristic and a first increment of change of the optical characteristic (400); b) performing (500) a first trial of a first subjective test using the optical instrument, wherein two first different optical conditions are identified based on at least a first test value; c) determining (600) a second test value of the optical characteristic based on the first test value, the first change increment and the results of the first trial performed in step b); d) performing a second trial of the subjective test using the optical instrument (700), wherein two second different optical conditions are identified based on at least a second test value; e) determining (800) an intermediate value of the optical characteristic based on the results of the first trial performed in step b) and the results of the second trial performed in step d); f) determining the rounded value of the optical characteristic by rounding the intermediate value to a reference value (900), wherein the rounding modifies the refractive correction of the ophthalmic lens by less than a predetermined base power value. Includes.

[0049] The method is not limited to performing two trials of subjective testing, and in fact the number of trials of subjective testing required to identify the intermediate value may be greater than two.

[0050] The processor g) identifying a current test value and a current increment of change based on the results of a previous trial and the previous test value corresponding to said previous trial (710); h) performing a current trial of the subjective test (720), which includes assessing the subject's visual performance in two different current optical situations identified based on at least the current test values; i) modifying the current test value based on the results of the current trial and the current change increment, and modifying the current change increment based on the results of the current trial (730); and Optionally, repeating steps h) and i); In step e), determining the intermediate value based on a current test value; The device may be further configured to:

[0051] In the following, the term "current" refers to any trial of the subjective test after the first and second trials and the test value and change increment associated with this current trial. In step i), modifying the current test value and the current change increment means that these two parameters are increased, updated or adjusted.

[0052] A previous trial generally refers to any trial performed before the current trial. In practice, the current test value and, optionally, the current increment of change are determined based on the test value and / or increment of change of the immediately preceding trial, which could be the second or any other trial performed before the current trial. However, due to the continuity of trials, the current test value and current increment of change still depend on the test values ​​and increments of all of the preceding trials.

[0053] Step a) In a first step a), a first test value V1 of the optical characteristic is determined.

[0054] The first test value may be identified based on historical subject medical data, past subject test results, or objective measurements.

[0055] The first test value may be obtained, for example, with an optical instrument previously used by the subject. Identifying the first test value is of particular interest when the subject already wears ophthalmic lenses and when the subject wishes to adjust their current correction.

[0056] The first test value may also be determined based on the results of another previous subjective test or a previous trial of the same subjective test. The previous trial of the subjective test may have been performed by the same eye care professional immediately prior to step a) performing the method according to the present invention. The other previous subjective test may have been performed by the same or another eye care professional immediately prior to or prior to the current subjective test.

[0057] In this case, the first test value is determined taking into account the degree of certainty of the result of the subjective test.

[0058] If the optical feature is a photorefractive optical feature, the first test value may be determined by objective refraction testing. The objective refraction testing may be performed using a retinoscope or an autorefractometer, which may be included in optical instrument 2. The objective refraction testing may be performed immediately before step a) by the same eye care professional who performs step a). It may also be performed by another eye care professional, or may have been performed in the past.

[0059] The first test value may also be determined by an eye care professional based on a personal characteristic or combination of personal characteristics of the subject.

[0060] The personal characteristics of the subject may include any of the first and second personal characteristics described below.

[0061] Additionally, in a first step a), a first change increment I1 is identified.

[0062] The first change increment I1 may be a predetermined value depending on the subjective test performed in step b).

[0063] This may also be determined based on the results of other previous subjective tests or the results of previous trials of the same subjective test.

[0064] In this case, the determination of the first change increment may take into account the degree of certainty of the results of the subjective test.

[0065] In an embodiment, the processor is programmed in step a) to identify the first change increment I1 based on at least a first personal characteristic of the subject.

[0066] The first personal characteristics may include, for example, at least one of the following data about the subject: age, type of refractive error, visual acuity, dissatisfaction with one's visual performance or current vision correction devices, the subject's treatment history including current correction, medical condition, vision needs or activities, selected spectacle frames, selected ophthalmic lenses, and optical characteristics of the subject's eye. The optical characteristics of the subject's eye may include, for example, ocular aberrations, ocular opacity, and objectively measured optical characteristics of the eye. The first personal characteristics may also include a measure related to the subject's sensitivity, i.e., the subject's ability to recognize differences in the refractive correction of lenses.

[0067] For example, when determining spherical power in, for example, the first, third, and fourth subjective tests for a subject with low visual acuity (e.g., 3 / 10), the first change increment is preferably greater than 1D, and for a subject with high visual acuity (e.g., 12 / 10), the first change increment is preferably less than 0.5D or 0.3D.

[0068] As described below, the first change increment I1 is used in step c) to identify a second test value V2 to be used in the second trial of the subjective test.

[0069] Preferably, the first change increment I1 is higher than the base power value. The first change increment I1 is, for example, greater than 0.3D or 10 degrees. This allows for quick convergence to a test value that represents the correction the subject needs. In other words, this reduces the number of trials required to identify the rounded value of the optical characteristic. The first change increment I1 used in the first trial of the subjective test is also preferably greater than the increment value used in the other trials of the subjective test, as will be explained in more detail below.

[0070] Step b) Two first different optical situations are identified based on at least the first test value V1.

[0071] After identifying the first test value V1, in step b) a first trial of the subjective test is performed.

[0072] For this purpose, two first optical situations S1, S2 are identified based on at least the first test value V1 and are presented to the subject by the optical instrument 2. During a first trial of the subjective test, the subject is instructed to gaze at one or more targets through a number of trial lenses whose characteristics, for example their spherical power or their orientation, are based on the first test value 1. Here, the targets are displayed on a target screen of the optical instrument 2.

[0073] In two first different optical situations S1, S2, the first variable device I1 is also considered, for example in the case of the third subjective test described below.

[0074] During the first trial of the subjective test, the subject is instructed to compare the two first optical situations S1, S2, i.e., to evaluate which of the first optical situations S1, S2 provides better visual performance according to the subject's perception. To obtain this information, in the subjective test performed, the eye care professional can ask, for example, "In which case do you see the target better?" or "Which target do you see better?"

[0075] It is possible that the subject can clearly distinguish the target in either of the first optical situations S1 and S2, in which case the subject evaluates in which situation the target can be better distinguished.

[0076] The result of the subjective test trial consists of the answer the subject provides to one of the above questions by assessing which of the two first optical situations S1, S2 provides the better quality of vision. Thus, here, the result can consist of one of three types of answers: i) First answer: The subject indicates that, of two optical situations S1 and S2, one optical situation S1 provides better quality of vision, in other words better visual performance, than the other optical situation S2. ii) Second answer: The subject indicates that of the two optical situations S1, S2, the other optical situation S2 provides better quality of vision, in other words better visual performance, than the previously considered optical situation S1. iii) Third response: the subject indicates that the two optical conditions S1, S2 provide equivalent visual performance or that they are unable to choose a better optical condition from the two. This last indication indicates the response "I don't know."

[0077] Alternatively, the answers may be defined as follows: a first answer may be an indication that neither of the two optical situations provides good quality vision, a second answer may be an indication that both optical situations provide good quality vision, and a third answer may be an indication that one of the two optical situations provides good quality vision.

[0078] In the following, two optical situations are designated by the same reference characters S1 and S2 for each trial, but they differ from trial to trial. The optical situation designated by S1 in each trial will be referred to below as a first type of optical situation, and the optical situation designated by S2 in each trial will be referred to below as a second type of optical situation. As will be explained in more detail below, the first type of optical situation has common characteristics or common differences with respect to the second type of optical situation.

[0079] For example, in a red-green test, the optical situation S1 corresponding to a green target would be of the first type, and the optical situation S2 corresponding to a red target would be of the second type. In a visual acuity test, the optical situation S1 corresponding to a lower visual acuity target or a lens with a lower spherical power would be of the first type, and the optical situation S2 corresponding to a higher visual acuity target or a lens with a higher spherical power would be of the second type.

[0080] The optical situations denoted S1 or S2 correspond to each other.

[0081] In practice, the eye care professional inputs the results of the subjective test trials into the computer 3 using an input device. For example, on the user interface shown in Figure 5, the eye care professional selects, for example by clicking, the left button 50 when the result of the first trial is the first answer. The professional selects the right button 52 if the result is the second answer. The professional selects the middle button 51 if the result is the third answer.

[0082] The subjective test trials and the dependence of the two optical conditions on the test values ​​and possibly the change increments are explained in more detail in the first to fifth subjective tests shown in FIGS.

[0083] Step c) In step c), a second test value V2 of the optical characteristic is determined based, inter alia, on the first test value V1, the first change increment I1, and the results of the first trial of the subjective test performed in step b).

[0084] The identification of the second test value may take into account the degree of certainty of the results of the first trial.

[0085] Here, the second test value V2 is calculated, for example, as the sum or difference of the first test value V1 and the first change increment V1, i.e., by adding or subtracting the first change increment I1 to or from the first test value V1. For example, as shown in Figure 3, the second test value V2 can therefore be calculated according to the formula V2 = V1 ± I1, where the sign ± indicates a + or - sign.

[0086] The second test value V2 may also be calculated as the weighted sum or difference between the first test value V1 and the first change increment I1. For example, as shown in Figure 6, the second test value V2 may therefore be calculated according to the formula V2 = V1 ± C × I1, where C is the true positive coefficient, for example, between 0.1 and 5, preferably between 0.5 and 2.

[0087] The result of the first trial determines whether the second test value V2 is higher or lower than the first test value V1, and therefore whether the first change increment I1 is added to or subtracted from the first test value V1.

[0088] Depending on the subjective test, a first answer or a second answer is obtained as a result of the first trial, which leads to whether the second test value V2 is greater or smaller than the first test value V1, respectively.

[0089] In response to the subjective test, a third response is obtained as a result of the first trial, which determines whether the second test value V2 is greater than or less than the first test value V1. In other words, in the first trial of the subjective test, the third response is treated as either the first or second response.

[0090] In fact, obtaining a third answer as a result of the first trial may be considered as the subject misinterpreting the subjective test. Therefore, the second test value V2 is also identified as being higher or lower than the first test value V1 after the third answer. Depending on the subjective test, as long as a third answer is continuously obtained as a result of successive trials, the test value is increased or decreased from one trial to the next.

[0091] In a preferred embodiment, the second change increment I2 is further determined, for example, based on the results of the first trial and the first change increment I1. Preferably, the second change increment I2 is smaller than the first change increment I1, which is reduced. Also preferably, the second change increment I2 may be lower than the basic degree value.

[0092] In a variant, the second change increment is greater than the basic power value, which allows a fast subjective test to be performed.

[0093] The determination of the second change increment may take into account the degree of certainty of the results of the first trial.

[0094] Step d) In step d), two second different optical conditions, i.e., one S1 of the first type and one S2 of the second type, are identified based on the second test value V2, and a second trial of the subjective test is performed using these second different optical conditions.

[0095] The second trial of the subjective test is similar to the first trial, except that the two different optical situations S1 and S2 presented to the subject depend on the second test value V2 rather than the first test value V1.

[0096] Similar to the first trial, a second change increment I2 can be considered in two second different optical situations S1, S2.

[0097] During the second trial of the subjective test, the subject is instructed to compare the two second optical conditions and rate which of the two second optical conditions provides better visual performance. The outcome of the second trial is also a first, second, or third response by the subject.

[0098] A first response corresponds to the subject indicating that of the two second optical situations, the second optical situation S1 of the first type provides better visual performance, a second response corresponds to the subject indicating that the second optical situation S2 of the second type provides better visual performance, and a third response corresponds to the subject indicating that the two second optical situations S1, S2 provide equal visual performance or that the subject is unable to choose a better optical situation from the two second optical situations.

[0099] Step g) The first and second trials mentioned above may actually correspond to the two initial trials performed when starting a sequence of trials in a subjective test, and they may correspond to any two consecutive trials within the trial sequence.

[0100] More generally, during each trial of the subjective test, the subject is instructed to compare two current optical conditions, one S1 of the first type and one S2 of the second type, and to evaluate which of the two current optical conditions provides better visual performance.

[0101] The subsequent steps of the method according to the invention are therefore described in a more general manner below.

[0102] In step g), a current test value VC is determined. The current test value VC is determined by taking into account the results of the preceding test values ​​and the preceding trial of the subjective test. Here, the current test value VC is determined by taking into account the preceding incremental change.

[0103] The previous test value, previous change increment and previous trial correspond below to the immediately previous test value, change increment and trial, which may be the second test value, second change increment and second trial.

[0104] Since all of the test values ​​are determined taking into account the previous test values ​​and the results of the previous trials, the current test value is determined taking into account, in particular, the second test value V2, the result of the second trial of subjective testing performed in step d), and the second change increment I2.

[0105] The current test value VC is calculated, for example, as the sum or difference of the previous test value VP and the previous change increment IP. The current test value V2 can therefore be calculated by the formula VC=VP±IP.

[0106] The current test value VC can also be calculated as the weighted sum or difference of the previous test value VP and the previous change increment IP. The current test value VC can therefore be calculated by the formula VC=VP±C×IP, where C is the true positive coefficient, e.g., 0.5-2.

[0107] The results of the previous trial of subjective testing identify whether the current test value VC is higher or lower than the previous test value VP.

[0108] Indeed, depending on the subjective test, a first response (the subject exhibits a first type of optical situation S1) and a second response (the subject exhibits a second type of optical situation S2) will respectively lead to a current test value VC that is higher or lower than the previous test value VP.

[0109] Depending on the results of the subjective test and the preceding trial, the third answer leads to either calculating the current test value VC or directly determining the intermediate value VI. More precisely, when the result of the preceding trial is the first or second answer, the third answer leads to directly determining the intermediate value VI.

[0110] Additionally, a current change increment IC may be determined based on, for example, the results of a previous subjective test and the previous change increment.

[0111] Here, the processor may be further programmed to identify the current change increment IC and / or the current test value based on the degree of certainty of the results of a previous trial performed, preferably the previous trial.

[0112] Generally, to account for the subject's degree of certainty, confidence data indicating the subject's degree of uncertainty in making the first, second, or third response is collected, recorded in the one or more memories, and associated with the response corresponding to each trial of the subjective test, where the degree of certainty is determined as described in U.S. Patent Application Publication No. 2019261848. The confidence data may therefore be based on measurements of the time it takes the subject to respond while looking at the target, or other measurements by a sensor, such as a pressure sensor associated with the button the subject uses to record their response. Any means known to those skilled in the art may be used.

[0113] For example, if the result of the current trial is a first or second answer but is uncertain, i.e., the degree of certainty is below a predetermined threshold, the change increment is preferably decreased, which in practice means that the current test value is close to the correction required for the subject.

[0114] If the degree of certainty is high, the first or second answer may be treated as a third answer.

[0115] Step h) Two different current optical situations, one of a first type S1 and one of a second type S2, are identified based on at least the current test value VC.

[0116] The present trial of the subjective test is conducted by presenting the subject with two present optical situations.

[0117] The current trial is similar to the first and second trials.

[0118] Similar to the first and second trials, two different current optical situations S1, S2 may also be identified based on the second current increment IC.

[0119] During the current trial of the subjective test, the subject is instructed to compare the two current optical conditions and rate which of the two current optical conditions provides the better quality of vision. The outcome of the current trial is also the subject's first, second, or third response.

[0120] Step i) After step h), in step i), the current test value VC is modified to determine an updated test value VCup based on the result of the current trial of the subjective test and the current change increment IC.

[0121] Here, the corrected updated current test value VCup is calculated, for example, as the sum or difference of the current test value VC and the current change increment IC. The updated current test value VCup can therefore be calculated by the formula VCup=VC±IC.

[0122] In effect, the first and second answers respectively lead to an increase or decrease of the current test value VC, ie an updated current test value that is lower or higher than the current test value.

[0123] Depending on the subjective test and the results of the first subjective test and the second trial, the third response leads to either an increase or a decrease in the current test value VC, i.e., to the identification of an updated current test value higher or lower than the current test value, or to the direct identification of the intermediate value VI. More precisely, the third response leads to the direct identification of the intermediate value VI if the result of the preceding trial test (i.e., the first, second, or current trial) is the first or second response.

[0124] After modifying the current test value, ie, calculating the updated current test value VCup, the current change increment IC is modified based on the results of the current trial.

[0125] The updated test value VCup is considered as the current test value in the next current trial.

[0126] Similar to identifying the current test value, the processor may be further programmed to modify the current change increment based on the degree of certainty of the results of the preceding trial.

[0127] Here, preferably, after steps h) and i) are repeated several times, preferably 1 to 4 times, the current change increment is smaller than the predetermined basic degree value.

[0128] In this way, the accuracy of the current test value VC may be less than the basic value. Therefore, the current test value can accurately represent the correction required for the subject. Therefore, the intermediate value VI identified in step e) also accurately represents the correction required for the subject.

[0129] As a variant, the current change increment may be greater than said predetermined basic value, which allows for a fast subjective test to be performed.

[0130] In one embodiment, the processor is further programmed in step i) to modify the current change increment by decreasing its value.

[0131] This allows for very accurate current test values, i.e., with greater accuracy than the basic value.

[0132] The processor stops repeating steps h) and i) or does not perform them at all when the following first or second stop conditions occur: In other words, when these stop conditions occur, the processor immediately performs step e).

[0133] The first stopping condition occurs when: - if, during the final trial of the subjective test, i.e., during the last trial performed, the subject evaluates the two final different optical situations as providing an equal visual performance, i.e., the result of the final trial is the third answer, and - if, during a previous trial of the subjective test carried out before said final trial, the subject evaluates one of two different previous optical situations as providing a better quality of vision than the other previous optical situation, i.e., the result of the final trial is the first or second answer.

[0134] The final trial of the subjective test here is the second trial or any other future current trial. The preceding trial can be any trial performed before the final trial. Here, the preceding trial is more specifically the previous trial performed immediately before the final trial.

[0135] If the first stopping condition occurs, this means that the test value tested during the final trial accurately represents the correction required for the subject.

[0136] The second stopping condition occurs when: - If the current test value increases and decreases or decreases and increases consecutively in the last two trials, or - the second test value is greater than the first test value and the current test value determined in step g) is less than the second test value, or - if the second test value is less than the first test value and the current test value determined in step g) is greater than the second test value.

[0137] For example, if three consecutive trials, called the first, second, and third trials, are performed, the second stopping condition may occur if: - the updated current test value is greater than the current test value and the current test value is less than the second test value, or - The updated current test value is less than the current test value and the current test value is greater than the second test value.

[0138] The second stopping condition allows the intermediate value VI to be identified more quickly (i.e., in fewer trials) than if only waiting for the first condition to occur. In fact, the intermediate value VI can be identified even without the third answer, i.e., even if the correction required by the patient is not tested as a test value during the trial.

[0139] In this case, the identified intermediate value VI is between the last two test values. For example, here, the intermediate value VI is identified as the average of the last two test values. This allows for the identification of an intermediate value IC that accurately represents the correction required for the subject.

[0140] Step e) In step e), an intermediate value VI of the optical characteristic is identified based on the results of the first and second trial tests performed in steps b) and d).

[0141] As mentioned above, depending on the results of the first and second trials, step e) may be performed immediately after step d), in which case only the first and second trials are performed.

[0142] For example, this is the case when the first stopping condition occurs after the second trial.

[0143] In this case, the intermediate value VI is equal to the second test value V2.

[0144] As mentioned above, depending on the results of the first and second trials, step e) may be performed immediately after step g), in which case only the first and second trials are performed.

[0145] For example, this is the case when a second stopping condition occurs after the current test value is identified in step g), i.e., when the second test value is greater than the first test and the current test value identified in step g) is less than the second test value, or when the second test value is less than the first test and the current test value identified in step g) is greater than the second test value, the intermediate value VI can be calculated as the average of the current test value and the second test value.

[0146] When yet another trial is performed, a current test value VC and a current change increment are identified, and the identification of an intermediate value VI is also based on the current test value VC and the current change increment VI.

[0147] When further trials are performed, the intermediate value VI can be calculated, for example, equal to the last test value or as the average between the last two test values.

[0148] For example, if the current test value is successively increased and decreased or decreased and increased in the last two consecutive trials, i.e., during the last two executions of steps h) and i), the intermediate value VI can be calculated as the average of the last two current test values.

[0149] For example, if the outcome of the current trial is the third answer, the intermediate value VI can be specified to be equal to the current test value.

[0150] Step f) After identifying the intermediate value VI, a rounded value of the optical characteristic is identified by rounding the intermediate value VI to a reference value.

[0151] The rounding is performed such that the refractive correction of the ophthalmic lens is corrected by less than a predetermined base power value.

[0152] If the optical feature is a dioptric optical feature, this means that the difference between the rounded value and the midpoint value is less than the base power value.

[0153] When the optical feature is the astigmatism axis, this means that the difference in direction between the rounded value and the intermediate value is perceived by the subject as a change in astigmatism power that is less than the base power value. In fact, as is well known in the field of cylindrical lenses, a change in the direction of the astigmatism axis results in a change in the power of the astigmatism. As a result, a correction of the astigmatism axis can be translated as a correction of the astigmatism axis.

[0154] Therefore, when the optical feature is an astigmatism axis, modifying the refractive correction of the ophthalmic lens by less than a predetermined base power value means that the power change in the astigmatism power caused by the change in the astigmatism axis is less than the predetermined base power value.

[0155] For example, if the astigmatism power is less than 1.5 D, the axis may be rounded to a multiple of 5 degrees. If the astigmatism power is greater than 1.5 D, rounding to a multiple of 5 degrees allows for a change in astigmatism power of greater than 0.25 D. Thus, if the astigmatism power is greater than 1.5 D, the intermediate value is preferably rounded to a multiple of 2 degrees.

[0156] The observed power change also depends on the astigmatic power of the test lens itself.

[0157] The base power value may be specified by an eye care professional based on the accuracy of the prescription they intend to issue. The base power value may be, for example, 0.25D.

[0158] As mentioned above, the reference value here is a standard value used in the manufacture of ophthalmic lenses. Where the optical characteristic is a dioptric optical characteristic, the reference value is more precisely defined as a multiple of the base power value. Where the optical characteristic is an astigmatism axis, the reference value is defined as a multiple of an angle, for example, 5 degrees.

[0159] Here, if the optical path length is an optical characteristic of light refraction, the one or more processors of the optical device 2 are more precisely programmed to round the intermediate value of the optical characteristic to the nearest or second nearest multiple of the predetermined basic power value if the intermediate value differs from a multiple of the predetermined basic power value.

[0160] For example, if the intermediate value VI identified in step e) is 0.87D and the basic power value is 0.25D, the nearest and second nearest multiples of 0.25D are 0.75D and 1D. Therefore, the intermediate value VI can be rounded to 0.75D or 1D.

[0161] Similarly, if the optical feature is an astigmatism axis, the one or more processors of the optical device 2 are more precisely programmed to round the intermediate value of the optical feature to the nearest or second nearest multiple of the certain angle if the intermediate value differs from the certain angle.

[0162] For example, if the intermediate value VI identified in step e) is 17 degrees and the base power value is 5 degrees, the closest and second-closest multiples of 5 degrees to 17 degrees D are 15 degrees and 20 degrees, and the intermediate value VI can be rounded to 15 degrees or 20 degrees.

[0163] Here, the processor is further programmed to round the intermediate value VI according to a rounding method that depends on at least one second personal characteristic of the subject or the type of subjective test performed.

[0164] The second personal characteristics include, for example, at least one of the following data about the patient: age, type of refractive error, visual acuity, dissatisfaction with one's visual performance or current vision correction devices, treatment history including the subject's current correction, medical condition, visual needs or activities, selected spectacle frames, selected ophthalmic lenses, optical characteristics of the subject's eyes.

[0165] For example, for subjects aged above the threshold, the intermediate value VI is preferably rounded to the higher of the nearest and second nearest values, and for subjects aged below the threshold, the intermediate value VI is preferably rounded to the lower of the nearest and second nearest values.

[0166] Taking the example where the intermediate value VI identified in step e) is 0.87D, for older subjects the intermediate value VI is preferably rounded to the higher value, i.e., 1D, and for younger subjects the intermediate value VI is preferably rounded to the lower value, i.e., 0.75D.

[0167] According to another example, for subjects whose visual acuity is above a certain threshold and / or who are not dissatisfied with their visual performance or current vision correction devices and / or who have no particular medical condition, low visual needs, and who do not engage in activities requiring visual improvement, the midpoint value can be rounded to the nearest multiple, whichever is lower. For subjects whose visual acuity is below a threshold and / or who are dissatisfied with their visual performance or current vision correction devices and / or who have a particular medical condition, high visual needs, and / or who engage in activities requiring visual improvement, the midpoint value can be rounded to the nearest multiple, whichever is higher.

[0168] Five subjective tests, each including a sequence of trials, will now be described with reference to Figures 3 to 8. The sequence of trials includes all of steps a) to f) of the method according to the invention, and thus allows for the determination of one rounded value of the optical characteristic. In the following, if a test value is determined as the sum of the previous test value and the previous change increment, it is said to be increased. Conversely, if a test value is determined as the difference between the previous test value and the previous change increment, it is said to be decreased.

[0169] Here, the first answer corresponds to an indication that in most of the examples described, a first type of optical situation S1 provides better visual performance than the other, the second answer corresponds to an indication that a second type of optical situation S2 provides better visual performance than the other, and the third answer corresponds to an indication that both the first and second types of optical situations S1, S2 provide equal visual performance.

[0170] As a variation, for example as described with respect to the fourth subjective test, a first response may correspond to an indication that neither of the two optical situations provides good quality vision, a second response may correspond to an indication that both of the optical situations provide good quality vision, and a third response may correspond to an indication that one of the two optical situations provides good quality vision.

[0171] The first and second responses are designated in the figures by the references of the corresponding optical situations S1 and S2, and the third response is designated in the figures by the reference M.

[0172] In Figures 3, 4, 6, 7 and 8, common reference numerals are used for the first, second and third answers.

[0173] First self-examination The decision tree for the first subjective test sequence is shown in Figure 3.

[0174] In this first subjective test, the optical characteristic of the ophthalmic lens is the spherical refractive power.

[0175] Each trial involves displaying two targets containing symbols placed in red and green environments, respectively, and providing the subject with a trial lens having a trial spherical power.

[0176] This subjective test is often called the "red-green test." Here, this subjective test is a monocular test. The rounded values ​​are determined for one eye. The sequence can be performed a second time or in parallel for the other eye. In the latter case, the first subjective test can therefore be a binocular test.

[0177] The target is displayed on a target screen of the optical instrument.

[0178] In a first type of optical situation S1, the first of the two targets comprises a symbol displayed on a uniform green background, the symbol comprising, for example, a target or a geometric shape.

[0179] In a second type of optical situation S2, the second of the two targets includes a symbol displayed on a uniform red background. The symbol may include, for example, a target or a geometric shape. The second symbol may be the same as the first symbol.

[0180] During each trial, the subject is instructed to view two targets through a trial lens having a trial sphere value equal to the test value and to identify which target has the symbol appearing sharper.

[0181] In step a), designated 100 in FIG. 3, a first test value can be determined, for example, as the subject's current correction or based on objective or subjective measurements.

[0182] In the first trial, the trial sphere of the trial lens is equal to the first test value V1.

[0183] If the symbol appears clearer to the subject on a green background than on a red background, the result of the first trial is a first answer 110. Optically, this means that the trial sphere of the trial lens is insufficient to provide adequate correction for the subject's eye being tested. It is therefore increased in the next trial. In step d), shown at 10 in FIG. 3, a second test value V2 is therefore determined as the sum of the first test value V1 and the first change increment I1.

[0184] If the sign appears clearer to the test value on a red background than on a green background, the result of the first trial is a second answer 120. Optically, this means that the spherical power of the trial lens is too strong to provide adequate correction for the subject's eye being tested. It is therefore reduced in the next trial. In step d), shown at 20 in FIG. 3, a second test value V2 is therefore determined as the difference between the first test value V1 and the first change increment I1.

[0185] More generally, if the trial results in a first answer 110, 221, 211, 231, the test value is increased, and if the trial results in a second answer 120, 222, 212, 232, the test value is decreased.

[0186] If the symbol appears equally sharp to the subject on the green and red backgrounds, the result of the first trial is the third response 130. Optically, this means that the spherical power of the trial lens is appropriate.

[0187] However, as mentioned above, obtaining a third answer as a result of the first trial is considered a misinterpretation of the test by the subject, where in this case a second test value V2 is also determined in step d) indicated at 30 as the sum of the first test value V1 and the first change increment I1, i.e., as if the result of the first trial were the first answer.

[0188] As long as the result of the successive trial is the third answer 233, the test value is determined as the sum of the previous test value and the previous change increment, ie, is increased.

[0189] Here, the intermediate value VI, and therefore the rounded value, is determined as the lower spherical refractive index in diopters that provides an equally sharp sign in the two optical situations S1 and S2. As a result, a second answer (with a sharper sign on a red background) must be obtained before the intermediate value can be determined. In fact, this is the only answer that can ensure that the trial spherical power value is lower than the value appropriate for the subject's vision correction. This also avoids subjective adjustments that could bias the determination of the intermediate value.

[0190] Thus, all branches of the decision tree shown in FIG. 3 that lead to the identification of intermediate value VI contain the second answer 212, 120, 232 at one point.

[0191] The intermediate value VI1 is determined, for example, when two consecutive trials result in a first answer 110, 211, 231 followed by a second answer 212. In this case, the intermediate value VI1 is equal to the current test value VC determined in step g) or i) indicated by 11 in FIG. 3 as the difference between the previous test value V2 and the previous change increment I2, where the previous change increment I2 is equal to half the previous change increment I1. The current test value VC is therefore the average of the two previous test values ​​V2, V1. This case corresponds to the second stopping condition.

[0192] An intermediate value VI2 may also be determined when two consecutive trials result in a second answer 120, 222 followed by a first answer 221. In this case, the intermediate value VI2 is equal to the current test value VC' determined in step g) or i) indicated at 21 in Figure 3 as the sum of the previous test value V2' and the previous change increment I2', where I2' is half the immediately preceding change increment I1. This case also corresponds to the second stopping condition.

[0193] An intermediate value VI3 may also be determined when two consecutive trials result in the second answer 120, 222 followed by the first answer 223. In this case, the intermediate value VI3 is equal to the previous test value V2' determined in step c), g) or i). This case corresponds to the first stopping condition.

[0194] Finally, an intermediate value VI4 can also be determined when two consecutive trials result in a third answer 130, 233, 213 followed by a second answer 232. In this case, the intermediate value VI4 is equal to the current test value VC'' determined in step g) or i) shown at 31 in FIG. 3 as the difference between the previous test value V'' and the previous change increment I'', which is equal to the immediately preceding change increment I''.

[0195] Preferably, the change increment is decreased between the first and last trial of the sequence, preferably from one trial to the next, for example, the first change increment V1 is equal to 1D and the second change increment V2 is equal to 0.3D.

[0196] In another example, the current change increment is calculated as the change increment value of the preceding trial, preferably the previous trial, multiplied by a factor strictly less than 1. The current change increment is then preferably much lower than the base power number, which is, for example, 0.25D.

[0197] In this first sequence, in step f), the rounded value is determined by rounding the midpoint value to the nearest or second nearest multiple of the base value. As mentioned above, the rounding method may depend on the personal characteristics of the subject.

[0198] Second self-awareness test The decision tree for the second subjective test is shown in 3.

[0199] The second subjective test is often called the "cross-cylinder test." This means that a cross-cylinder is placed in front of the subject's eye in two different positions, here in two different orientations. This subjective test is monocular. The rounded values ​​are determined for one eye. This sequence can be performed a second time for the other eye.

[0200] In this example of the second subjective test, the optical feature is the axis of astigmatism. However, a similar subjective test with a similar decision tree may be used to identify the power of astigmatism.

[0201] During each trial, the subject is instructed to view a target displayed, for example, on the target screen of optical instrument 2, through a trial lens known as a "Jackson cross cylinder," herein referred to as a cross cylinder.

[0202] In a first type of optical situation S1, the cross cylinder is positioned in a first orientation.

[0203] In a second type of optical situation S2, the cross cylinder is positioned at a second orientation, where the second orientation is rotated 90 degrees around the gaze axis of the eye with respect to the first orientation, and the plus and minus axes of the cross cylinder are interchangeable.

[0204] Here, the positive axis is defined as the axis where the cross cylinder has the maximum degree of rotation, e.g., +0.25D or +0.5D, and the negative axis is defined as the axis where the cross cylinder has the minimum degree of rotation, e.g., -0.25D or -0.5D.

[0205] To identify the astigmatism axis, for each trial, the cross cylinder is positioned relative to a trial astigmatism axis value, where the trial astigmatism axis value is an angle, expressed in degrees, with a predetermined direction, e.g., horizontal. In a first type of optical situation S1, the positive axis of the cross cylinder is rotated 45 degrees counterclockwise from the trial astigmatism axis value, and in a second type of optical situation S2, the positive axis of the cross cylinder is rotated 45 degrees clockwise from the trial astigmatism axis value.

[0206] In the first trial, the trial astigmatism axis value is equal to the first test value. In the second trial, the trial astigmatism axis value is equal to the second test value. In the current trial, the trial astigmatism axis value is equal to the current test value.

[0207] In Figure 5, the trial astigmatism axis is represented by the letter A, designated 53. In Figure 5, the trial astigmatism power value is equal to 17 degrees. The cross cylinder is represented by the circle, designated 54. The positive axis of the cross cylinder passes through the two first poles 55 of the cross cylinder, and the negative axis of the cross cylinder passes through the two second poles 56 of the cross cylinder.

[0208] To the subject, in both optical situations S1 and S2, the target viewed through the cross cylinder is blurred. During subjective testing, the eye care professional may ask, "In which situation is the target blurrier?"

[0209] Thus, in general, when the trial results in a first answer 110, 221, 211, 231, the test value is increased, and when the trial results in a second answer 120, 222, 212, 232, the test value is decreased.

[0210] Unless all previous trials have resulted in the third answer, when the result is the third answer 213, 223, the intermediate values ​​VI1, VI5 are therefore determined to be equal to the last test values ​​V2, V2″. This corresponds to the first stopping condition.

[0211] As with the first subjective test, obtaining the third answer as a result of the first trial is considered a misinterpretation of the subjective test by the subject, where in this case the second test value V2' is specified as the sum of the first test value V2 and the first change increment I1, i.e., as if the result of the first trial had been the first answer.

[0212] As long as the result of the successive trial is the third answer 233, the test value is determined as the sum of the previous test value and the previous change increment, ie, is increased.

[0213] Similar to the first subjective test, intermediate values ​​VI2, VI4 are determined, for example, when the results of two consecutive trials are a first response 110, 211, 231 followed by a second response 212, or conversely, a second response 120, 222 followed by a first response 221. In this case, intermediate values ​​VI2, VI4 are equal to current test values ​​VC, VC'', which are determined as the difference or sum, respectively, of previous test values ​​V2, V2'' and previous change increments I2, I2'', which are equal to half of the immediately preceding change increment I1. This case corresponds to the second stopping condition.

[0214] Finally, an intermediate value VI3 can also be determined when two consecutive trials result in a third answer 130, 233 followed by a second answer 232. In this case, the intermediate value VI3 is equal to the current test value VC', which is determined as the difference between the previous test value V2' and the previous change increment I2', which is equal to the immediately preceding change increment I1.

[0215] Preferably, the change increment is decreased between the first and last trials of the sequence. Preferably, this is decreased from one trial to the next. For example, the first change increment V1 is equal to 15 degrees, and the second change increment V2 is equal to 7 degrees. Then, the current change increment can be much lower than the base power value. The base power value is, for example, 5 degrees.

[0216] In this second sequence, in step f), the rounded value can be determined by rounding the midpoint value to the nearest or second nearest multiple of an angle, where the midpoint value is preferably rounded to the nearest or second nearest lower multiple of an angle. As mentioned above, the rounding method can depend on the individual characteristics of the patient.

[0217] The astigmatism power of an ophthalmic lens adapted to provide refractive correction to improve the subject's vision may also be determined. The decision tree shown in FIG. 4 is also applied to determining the astigmatism power. When determining the astigmatism power, the test value is the power value. For each trial, the cross cylinder is oriented with respect to a predetermined astigmatism axis. Here, in the second type of optical situation S2, the negative axis of the cross cylinder is aligned with the negative axis of the astigmatism axis.

[0218] Here, the cross cylinder has a trial astigmatism value. For the first trial, the trial astigmatism value is equal to the first test value. For the second trial, the trial astigmatism value is equal to the second test value. For the current trial, the trial astigmatism value is equal to the current test value.

[0219] The first test value V1 is, for example, +0.25D or −0.25D.

[0220] If the subject sees the target as sharper, i.e., providing better visual performance, in the first type of optical situation S1, the test value and therefore the value of the astigmatism power are increased. If the subject sees the target as sharper, i.e., providing better visual performance, in the second type of optical situation S2, the test value of the cross cylinder and therefore the value of the astigmatism power are decreased.

[0221] The first change increment may depend on the difference between the astigmatism power value obtained from the subject's previous optical device and the first test value, the greater the difference, the greater the change increment.

[0222] The axis of astigmatism and power is one way to represent cylinder, but there are other representations, such as the J0, J45 representation described in document EP 2018061207. The decision tree shown in Figure 4 can also be applied to the J0, J45 representation, for example by setting J45 to a predetermined value, solving for J0, then setting J0 to the obtained value and solving for J45.

[0223] Third self-awareness test The third subjective test decision tree is shown in Figure 6.

[0224] In this third subjective test, the optical characteristic determined is spherical power. The test consists of placing two lenses of different spherical surfaces in front of the subject's eye. This subjective test is monocular. A rounded value is determined for one eye. The subjective test can be performed a second time for the other eye.

[0225] In a first type of optical situation S1, the subject views a target displayed, for example, on a target screen of the optical instrument 2, through a first trial lens. The first trial lens is characterized by a first trial spherical power value.

[0226] In a second type of optical situation S2, the subject views the same target through a second trial lens characterized by a second trial spherical power value that differs from the first trial surface power value.

[0227] During each trial, the subject is instructed to view the target sequentially through the first and then the second trial lens.

[0228] Here, the intermediate value VI, and therefore the rounded value, is determined as the lower spherical power at which an equally sharp target appears in the two optical situations S1, S2.

[0229] In step a), designated 100 in FIG. 3, a first test value can be determined, for example, as the subject's current correction or based on an objective measurement.

[0230] During subjective testing, the eye care professional may ask, "In which situation do you see the letters clearly?"

[0231] In the first trial, the first trial sphere power value is equal to the first test value V1 minus the first change increment. The second trial sphere power value is equal to the first test value.

[0232] More generally, for each trial, in a first type of optical situation, the first trial spherical refraction value is equal to the test value minus the change increment, and in a second type of optical situation, the second trial spherical refraction value is equal to the test value.

[0233] In each trial, the first trial lens may be presented before or after the second trial lens.

[0234] If the target appears sharper to the subject with the first trial lens than with the second trial lens, the result of the trial is the first answer. Optically, this means that the spherical power of the second trial lens is too strong to provide adequate correction for the subject's eye being tested. If the result of the first trial is the first answer 110, then in step d) shown at 10 in FIG. 6, a second test value V2' is therefore determined as the difference between the first test value V1 and the first change increment I1, i.e., equal to the first trial spherical power value.

[0235] If the target appears sharper to the subject with the second trial lens than with the first trial lens, the result of the first trial is the second answer. Optically, this means that the spherical power of the second trial lens is insufficient to provide adequate correction for the subject's eye being tested. If the result of the first trial is the second answer 120, then in step d) shown at 20 in FIG. 3, a second test value V2 is determined as the weighted sum of the first test value V1 and the first change increment I1. More precisely, the second test value V2 is determined as the sum of the first test value V1 and the first change increment I1 weighted by a coefficient C less than 1. For example, the weighting coefficient C is equal to 0.625. More generally, if the result of the trial is the first answer 110, 221, 211, or 231, the test value is decreased, and if the result of the trial is the second answer 120, 222, 212, or 232, the test value is increased.

[0236] If the target appears equally sharp to the subject in both optical conditions S1 and S2, the outcome of the first trial will be the third response 130.

[0237] However, as mentioned above, the third answer obtained as a result of the first trial is considered a misinterpretation of the test by the subject, where in this case a second test value V2″ is also determined in step d) indicated at 30 as the difference between the first test value V1 and the first change increment I1, i.e., as if the result of the first trial were the first answer.

[0238] As long as the result of a successive test is a third answer 233, the test value is determined as the difference between the previous test value and the previous change increment, ie, is decreased.

[0239] Here, to make it easier for the subject to understand the subjective test, that is, to help the subject recognize the difference between the first optical conditions S1 and S2, the first change increment I1 is large, for example, greater than 0.35D.

[0240] If the result of the first trial is the third answer 130 and the result of the second trial is the second or third answer 232, the current test value VC' is calculated as the difference between the second test value V2'' and the second change increment I2''. In this case, the second change increment I2'' is greater than the first change increment V1. For example, the second change increment I2'' is 1.625 times the first change increment I1.

[0241] Except for this particular branch of the decision tree, the change increment is preferably decreased between the first and last trial of the sequence.

[0242] When the result is the third answer 223, 212, 300, the second trial lens provides the appropriate correction for the subject's eye being tested. The intermediate values ​​VI1, VI3, VI5 are therefore identified as equal to the current test values ​​V2, V2', VC', i.e., equal to the second trial sphere power values. This corresponds to the first stopping condition. The only exception is the branch where the result of the first trial is the third answer 130 and the result of the second trial is also the third answer 232.

[0243] As with the first and second sequences, intermediate values ​​VI2, VI4 are determined, for example, when the result of two consecutive trials is a first answer 110, 211, 231 followed by a second answer 212, or conversely a second answer 120, 222, 232, 302 followed by a first answer 221, 301. In this case, intermediate values ​​VI2, VI4 are equal to current test values ​​VC, VC''.

[0244] Preferably, the change increment is decreased between the first and last trials of the sequence. Preferably, this is decreased from one trial to the next. For example, the first change increment V1 can be greater than 1D, and the second change V2 can be less than 1D. Then, the current change increment can be much lower than the basic power value. The basic power value is, for example, 0.25D. In this third subjective test, in step f), the rounded value is determined by rounding the intermediate value to the nearest or second nearest multiple of the basic power value. As mentioned above, the rounding method can depend on the subject's personal characteristics.

[0245] Fourth self-examination The decision tree for the fourth subjective test sequence is shown in Figure 7.

[0246] In this first subjective test, the optical characteristic of the ophthalmic lens is the spherical refractive power.

[0247] Each trial involves displaying two targets of different sizes and providing the subject with a trial lens having a trial spherical power value.

[0248] This subjective test is often called the "fogging / defogging test." This subjective test is monocular. Rounded values ​​are determined for one eye. The sequence can be performed a second time for the other eye.

[0249] In a first type of optical situation S1, a subject views a first target through a trial lens, the size of the first target corresponding to a first visual acuity value when viewed at the subject's viewing distance.

[0250] In optical situation 2, S2, the subject views a second target, smaller than the first target, through the same trial lens. The size of the second target corresponds to the subject's second visual acuity when viewed at the subject's viewing distance.

[0251] During each trial, the subject is instructed to view two targets through a trial lens having a trial sphere power value equal to the test value and identify which target has the symbol appearing sharper.

[0252] The two targets may be, for example, lines of letters on an eye chart. For example, in a first trial, the first target is a line at 4 / 10 and the second target is a line at 8 / 10. The sizes of the first and second targets may vary from trial to trial.

[0253] Here, in an optional initial portion of the sequence (not shown in Figure 7), the size of the first and second targets may be increased until the subject can clearly read at least the first target.

[0254] Here, the outcome of the trial is a first response if the subject cannot clearly read the letters in either the first or second target, a second response if the subject can clearly read the letters in both the first and second targets, and a third response if the subject can clearly read the letters in the first target but cannot clearly read the letters in the second target.

[0255] Here, in the first step a), the first test value can be determined, for example, as the subject's current correction or based on objective or subjective measurements, plus a predetermined power value, for example, greater than 1D. Adding such a predetermined power value corresponds to an initial fogging test. In fact, in the first part of the sequence, fogging allows the subject to relax accommodation.

[0256] Thus, the test value is increased as long as the subject can clearly read the second target, i.e., as long as successive trials result in the second response 130. As shown in Figure 7, when the first trial results in the second response 120, a second test value V2 is calculated in step c), indicated at 20 in Figure 7, as the sum of the first test value V1 and the first change increment I1.

[0257] Such an increase in the test value corresponds to the first part of the sequence, i.e. the fogging step, during which the change increment is preferably kept constant.

[0258] Thus, when the subject can clearly read only the first target, i.e., when the trial results in the third answer, the test value is decreased. For example, in Figure 7, when the second trial results in the third answer 223, the current test value V is calculated in step g) indicated at 21 as the difference between the second test value V and the second change increment I.

[0259] This initial decrease in test value marks the beginning of the second portion of the sequence, the defogging step, where at the start of the second portion of the sequence, a second target is set at a line corresponding to a predetermined high visual acuity, e.g., 10 / 10 visual acuity.

[0260] Thus, as long as the subject can clearly read only the first target, ie, when the response on the successive trial is the third response 300, the test value is reduced.

[0261] Here, during the defogging step, the change increment is preferably decreased from one trial to the next.

[0262] Thus, the intermediate value VI is identified as equal to the current test value VC when the subject can clearly read the second target, i.e., when the trial results in the second response 301. The intermediate value is now identified as equal to the current test value when the second response is obtained on the second target, where the second response corresponds to the predetermined desired visual acuity.

[0263] In step f), the rounded value is determined by rounding the intermediate value to the nearest or next nearest multiple of the base dioptric power, e.g., 0.25 D. As mentioned above, the rounding method may depend on the subject's personal characteristics.

[0264] Fifth self-examination The fifth subjective test decision tree is shown in Figure 8.

[0265] In this fifth subjective test, the optical characteristic identified is the difference in spherical power between the left and right eyes. The test consists of placing two lenses of different spherical surfaces in front of each eye of the subject.

[0266] This subjective test is a binocular test. Rounded values ​​are determined for both eyes. In a first type of optical situation S1, the subject looks with his left eye at a target displayed, for example, on a target screen of the optical instrument 2, through a left trial lens. The left trial lens is characterized by a left trial spherical power value.

[0267] In a second type of optical situation S2, the subject views the same target with his right eye through a right trial lens characterized by a right trial spherical power value that differs from the left trial spherical power value.

[0268] During each trial, the subject is instructed to view the target with the left eye through the left trial lens, then with the right eye through the right trial lens. A mask can be placed in front of one eye so that the subject can only see the target with the other eye.

[0269] Here, the intermediate value VI, and therefore the rounded value, is determined as the difference between the left trial spherical power value and the right trial spherical power value at which the target appears equally sharp to both eyes.

[0270] In step a), shown at 100 in FIG. 3, a first test value can be determined, for example, as the difference in spherical refractive power between the left and right eyes based on the subject's current correction or two objective monocular measurements, one for the right eye and one for the second eye.

[0271] During subjective testing, the eye care professional may ask, "In which situation do you see the letters more clearly?"

[0272] For the first trial, the left trial spherical power value is equal to the spherical power previously determined in the monocular test for the left eye plus a predetermined power value, here 0.5D, and the right trial spherical power value is equal to the spherical power previously determined in the monocular test for the right eye plus a predetermined power value.

[0273] If the subject sees the target sharper with the left trial lens, i.e., with the left eye, than with the right trial lens, the result of the trial is the first answer. When the result of the first trial is the first answer 110, in step d) shown as 10 in Figure 8, the second test value V2 is therefore determined as the sum of the first test value V1 and the first change increment I1. This means that for the second trial, the difference between the left trial spherical power value and the right trial spherical power value is increased.

[0274] If the subject sees the target sharper with the right trial lens, i.e., with the right eye, than with the left trial lens, the result of the trial is the second answer. When the result of the first trial is the second answer 120, in step d) shown at 20 in FIG. 8, the second test value V2' is therefore determined as the difference between the first test value V1 and the first change increment I1. This means that for the second trial, the difference between the left trial spherical power value and the right trial spherical power value is reduced.

[0275] Preferably, the left trial spherical power value and the right trial spherical power value are symmetrically modified by the same amount, for example, if the difference between the left trial spherical power value and the right trial spherical power value is increased by 0.3D, the higher of these values ​​is increased by 0.15D and the lower of these two values ​​is decreased by 0.15D.

[0276] Here, neither the left trial spherical power value nor the right trial spherical power value can be lower than a threshold value, which is, for example, −0.05 D. For example, if the difference between the left trial spherical power value and the right trial spherical power value must be increased by 0.3 D and the lower value is equal to 0 D, the lower value is reduced to −0.05 D and the higher value is increased by 0.25 D.

[0277] More generally, if the trial results in a first answer 110, 221, 211, 231, the test value is increased, and if the trial results in a second answer 120, 222, 212, 232, the test value is decreased.

[0278] If the target appears equally sharp to the subject in both optical conditions S1 and S2, the outcome of the first trial is the third response 130.

[0279] However, as mentioned above, obtaining a third answer as a result of the first trial is considered a misinterpretation of the test by the subject, where in this case a second test value V2″ is also identified in step d) indicated at 30 as the difference between the first test value V1 and the first change increment I1, i.e., as if the result of the first trial were the second answer.

[0280] As long as the result of a successive test is a third answer 233, the test value is determined as the difference between the previous test value and the previous change increment, ie, is decreased.

[0281] Preferably, the change increment is preferably decreased between the first and last trial of the sequence.

[0282] Unless all previous trials have resulted in the third answer, if the result is the third answer 213, 223, the intermediate values ​​VI1, VI3 are determined to be equal to the last test values ​​V2, V2'. This corresponds to the first stopping condition.

[0283] Similar to the second subjective test, intermediate values ​​VI2, VI4 are determined, for example, when two consecutive trials result in a first response 110, 211, 231 followed by a second response 212, or conversely, a second response 120, 222 followed by a first response 221. In this case, intermediate values ​​VI2, VI4 are equal to current test values ​​VC, VC', which are determined as the difference or sum of previous test values ​​V2, V2' and previous change increments I2, I2', which are equal to half of the immediately preceding change increment I1. This case corresponds to the second stopping condition.

[0284] Finally, an intermediate value VI5 can also be determined when two consecutive trials result in a third answer 130, 233 followed by a first answer 231. In this case, the intermediate value VI5 is equal to the current test value VC'', which is determined as the sum of the previous test value V2'' and the previous change increment I2'', which is equal to half of the immediately preceding change increment I1.

[0285] Preferably, the change increment is decreased between the first and last trials of the sequence. Preferably, this is decreased from one trial to the next. For example, the first change increment V1 can be greater than 1D, and the second change V2 can be less than 1D. Thereafter, the current change increment can be much smaller than the base power value. The base power value is, for example, 0.25D.

[0286] In this fifth sequence, in step f), the rounded value is determined by rounding the midpoint value to the nearest or second nearest multiple of the base value. As mentioned above, the rounding method may depend on the personal characteristics of the subject.

[0287] In a well-known manner, the sequences for the different subjective tests may be performed successively, for example, a fifth subjective test sequence is preferably performed after two fourth subjective tests, once for the left eye and once for the right eye.

[0288] In the above example of subjective testing, the rounded value is determined at the end of the sequence of trials of each subjective test.

[0289] When performing a series of subjective tests, i.e., several different subjective tests performed in succession, determining the rounding value of the desired optical characteristic can be done at the end of the sequence of trials of each subjective test or at the end of all subjective tests.

[0290] In this last case, the exact, unrounded value of the optical feature determined through a previously performed subjective test may be used in the subsequent subjective test. In fact, the exact, unrounded value of the optical feature determined through a previously performed subjective test corresponds to the aforementioned intermediate value.

[0291] In practice, when determining the astigmatic axis power and astigmatic power of a cylindrical ophthalmic lens, an intermediate value representing the astigmatic axis is preferably taken into account when performing a subjective test to determine the astigmatic power.

[0292] The rounded values ​​of both intermediate values ​​determined through subjective tests to determine the astigmatism axis and the astigmatism power can be rounded after both subjective tests are performed, and thus the determination of the intermediate value representing the astigmatism power is more accurate because it takes into account the intermediate value of the astigmatism axis, rather than its rounded value.

[0293] In one variation, when performing a series of subjective tests, only the last intermediate value identified in the last sequence is rounded. The previous series of tests may only serve to identify the correct initial test value.

[0294] For example, if only the difference in spherical surfaces between the left and right eyes is sought, the fifth subjective test is preferably performed in step a) using the median value determined for the left eye in the first or fourth subjective test and the median value determined for the left eye in the first or fifth subjective test.

Claims

1. 1. A system (1) for identifying rounded values ​​of optical characteristics of an ophthalmic lens adapted to provide refractive correction to improve at least the visual acuity of a subject, comprising: an optical instrument (2) for performing a subjective test including assessing the visual performance of said subject placed in two different optical situations (S1, S2); and a computer (3), a) determining (400) a first test value (V1) of the optical characteristic and a first increment of change (I1) of the optical characteristic; b) performing (500) a first trial of the subjective test using the optical instrument (2), wherein two first different optical situations (S1, S2) are identified based on at least the first test value (V1); c) determining (600) second test values ​​(V2, V2', V2'') of the optical characteristic based on the first test value (V1), the first change increment (I1) and the results (110, 120, 130) of the first trial performed in step b); d) performing (700) a second trial of the subjective test using the optical instrument (2), wherein two second different optical situations (S1, S2) are identified based on at least the second test values ​​(V2, V2', V2''); e) determining (800) intermediate values ​​of the optical characteristics (VI1, VI2, VI3, VI4, VI5) based on at least the results (110, 120, 130) of the first trial performed in step b) and the results (212, 213, 221, 223, 231, 232) of the second trial performed in step d); f) determining the rounded values ​​of the optical characteristics by rounding the intermediate values ​​(VI1, VI2, VI3, VI4, VI5) to a reference value (900), wherein the rounding modifies the refractive correction of the ophthalmic lens by less than a predetermined base power value. and a computer (3) including one or more processors programmed to implement the above.

2. 2. The system (1) according to claim 1, wherein in step f), the processor is programmed to round the intermediate values ​​(VI1, VI2, VI3, VI4, VI5) of the optical characteristics to the nearest or second nearest multiple of the predetermined basic power number if the intermediate values ​​(VI1, VI2, VI3, VI4, VI5) of the optical characteristics are different from a multiple of the predetermined basic power number.

3. 3. The system (1) according to claim 1 or 2, wherein the processor is further programmed in step a) to determine the first change increment (I1) based on at least a first personal characteristic of the subject.

4. 4. The system (1) according to claim 3, wherein the first personal characteristics comprise at least one of the following data about the subject: age, type of refractive error, visual acuity, dissatisfaction with their visual performance or current vision correction devices, medical history data including the subject's current correction, medical condition, visual needs or activities, selected spectacle frames, selected ophthalmic lenses, optical characteristics of the subject's eyes.

5. 2. The system (1) of claim 1, wherein the processor is further programmed in step f) to round the intermediate values ​​(VI1, VI2, VI3, VI4, VI5) according to a rounding method that depends on at least a second personal characteristic of the subject or the type of subjective test performed.

6. 6. The system (1) according to claim 5, wherein the second personal characteristics comprise at least one of the following data about the subject: age, type of refractive error, visual acuity, dissatisfaction with their visual performance or current vision correction devices, medical history data including the subject's current correction, medical condition, visual needs or activities, selected spectacle frames, selected ophthalmic lenses, optical characteristics of the subject's eyes.

7. 2. The system (1) of claim 1, wherein the processor is further programmed in step b) to identify the two first different optical situations (S1, S2) based on the first change increment (I1).

8. The subject, during the subjective test, - displaying targets placed in red and green environments; - adding a cross cylinder in front of the subject's eye at two different positions; - placing two lenses of different spheres in front of the subject's eye; - displaying two targets of different sizes; - placing different lenses in front of the right and left eyes of the subject 2. The system (1) according to claim 1, wherein the system (1) is placed in said two different optical situations (S1, S2) by realizing at least one of the following:

9. The optical characteristics are: the spherical power of said ophthalmic lens, - the astigmatism power of said ophthalmic lens, - the astigmatism axis of said ophthalmic lens, - the difference in spherical power between two ophthalmic lenses placed in front of the right and left eyes The system (1) according to claim 1, comprising at least one of:

10. The processor: g) determining (710) current test values ​​(VC, VC', VC'') and current change increments (IC) based on the results of the preceding trials (211, 212, 213, 221, 222, 223, 231, 232, 233, 300, 301, 302) and the preceding test values ​​(V1, V2, V2', V2'', VC, VC', VC'') corresponding to said preceding trials; h) performing a current trial of the subjective test (720), which comprises evaluating the subject's visual performance in two different current optical situations (S1, S2) identified based on at least the current test values ​​(VC, VC', VC''); i) modifying (730) the current test values ​​(VC, VC', VC'') based on the results of the current trial (211, 212, 213, 221, 222, 223, 231, 232, 233, 300, 301, 302) and the current change increment (IC), and modifying the current change increment (IC) based on the results of the current trial (211, 212, 213, 221, 222, 223, 231, 232, 233, 300, 301, 302); and further programmed to perform 2. The system (1) of claim 1, wherein the processor is programmed in step e) to determine the intermediate values ​​(VI1, VI2, VI3, VI4, VI5) based on the current test values ​​(VC, VC', VC'').

11. 11. The system (1) of claim 10, wherein the processor is further programmed to determine in step g) and / or modify in step i) the current change increment (IC) based on a degree of certainty of the results (211, 212, 213, 221, 222, 223, 231, 232, 233, 300, 301, 302) of the previous trials performed.

12. 11. The system (1) of claim 10, wherein the current change increment (IC) is less than the predetermined base degree value.

13. 11. The system (1) of claim 10, wherein the processor is further programmed to modify the current change increment (IC) in step i) by decreasing its value.

14. The processor: - if the current test values ​​(VC, VC', VC'') are consecutively increased and decreased or decreased and increased in the last two consecutive trials, or the second test value (V2, V2', V2'') is greater than the first test value (V1) and the current test value (VC, VC', VC'') determined in step g) is less than the second test value (V2, V2', V2''), or if the second test value (V2, V2', V2'') is smaller than the first test value (V1) and the current test value (VC, VC', VC'') determined in step g) is larger than the second test value (V2, V2', V2''), The system (1) of claim 10, further programmed to perform step e).

15. The processor: - if, during the second trial or future trials, the subject evaluates the two different optical situations (S1, S2) as providing equivalent visual performance; and if, during the second trial or a previous trial performed before the future trial, the subject evaluates one of the two different optical situations (S1, S2) as providing a better quality of vision than the other optical situation (S1, S2); The system (1) of claim 1, further programmed to perform step e).

16. 1. A method for identifying a rounded value of an optical characteristic of an ophthalmic lens adapted to provide a refractive correction to improve a subject's visual acuity, comprising: a) determining (400) a first test value (V1) of the optical characteristic and a first increment of change (I1) of the optical characteristic; b) performing (500) a first trial of a subjective test using an optical instrument (2), wherein two first different optical situations (S1, S2) are identified based on at least the first test value (V1); c) determining (600) second test values ​​(V2, V2', V2'') of the optical characteristic based on the first test value (V1), the first change increment (I1) and the results (110, 120, 130) of the first trial performed in step b); d) performing (700) a second trial of the subjective test using the optical instrument (2), wherein two second different optical situations (S1, S2) are identified based on at least the second test values ​​(V2, V2', V2''); e) determining (800) intermediate values ​​of the optical characteristics (VI1, VI2, VI3, VI4, VI5) based on at least the results (110, 120, 130) of the first trial performed in step b) and the results (212, 213, 221, 223, 231, 232) of the second trial performed in step d); f) determining the rounded value of the optical characteristic by rounding the intermediate values ​​(VI1, VI2, VI3, VI4, VI5) to a reference value, wherein the rounding modifies the refractive correction of the ophthalmic lens by less than a predetermined base power value; A method comprising:

Images