Systems and methods for determining rounding values ​​for optical characteristics suitable for providing refractive correction to improve the vision of a subject.

Abstract

The present invention relates to a system for determining a rounding value of an optical feature suitable for providing refractive correction for improving the vision of a subject, comprising one or more processors programmed to perform the following steps: a) determining a first test value and a first increment of variation of the optical feature; b) performing a first trial of a subjective test, wherein two distinct first optical conditions are determined based at least on the first test value; c) determining a second test value of the optical feature based on the first test value, the first increment of variation, and the result of the first trial; d) performing a second trial of a subjective test, wherein two distinct second optical conditions are determined based at least on the second test value; e) determining an intermediate value of the optical feature based on the result of the first trial and the result of the second trial; and f) determining a rounding value of the optical feature by rounding the intermediate value to a reference value, wherein the rounding modifies the refractive correction of the ophthalmic lens to less than a predetermined basic refractive value.

Description

Technical Field

[0001] The present invention relates to a system and method for determining rounding values ​​of optical characteristics suitable for providing refractive correction for improving the vision of a subject. Background Technology

[0002] Manufacturing ophthalmic lenses suitable for improving a subject's vision requires determining the values ​​of optical characteristics suitable for that subject. To determine these values, eye care professionals typically perform subjective tests on the subject using appropriate optical devices. Numerous documents describe apparatus and methods for determining these values ​​of the ophthalmic lens's optical characteristics. These optical characteristics may include, for example, spherical power, cylindrical power, or cylindrical axis.

[0003] Typically, the subjective test comprises several steps (hereinafter referred to as trials), during which the subject is asked to consider test values ​​of an optical feature to compare two different optical conditions. Thus, the subjective test corresponds to a sequence of trials. Depending on the subject's feedback on this comparison (hereinafter referred to as the subject's answer), the eye care professional increments the test values, and in the next trial of the subjective test, presents the subject with two new different optical conditions based on the incremented test values. This process is repeated until the subject gives a specific answer or combination of answers. The prescribed value for that optical feature is then typically determined based on the test values ​​used in the final trial of the subjective test.

[0004] To determine the accurate value of this optical characteristic, the new device allows eye care professionals to use small increments between successive tests of subjective assessment. For example, a comprehensive refractive instrument using variable lenses allows for increments of less than 0.2D.

[0005] In this case, the determined optical characteristic values ​​are accurate, but do not take into account the standard values ​​of optical characteristics of commercially available ophthalmic lenses.

[0006] Ophthalmic lenses with arbitrary optical characteristics are practically unavailable on the market. Only a set of predetermined values ​​(hereinafter referred to as "standard values") for each optical characteristic are available.

[0007] Furthermore, using devices and methods with small increments between successive trials of a subjective test often leads to prolonged examination time and the risk that the subject may not perceive any difference between the two successive trials of the subjective test. Therefore, eye care professionals may need to shorten the test if the subject being tested becomes impatient, stressed, experiences eye fatigue, or lacks focus.

[0008] Therefore, there is also a need for an apparatus and method in which the increment will, on the one hand, allow the subject to clearly understand the subjective test, and on the other hand, reduce the examination time while avoiding exceeding the correct value of the optical characteristics. Summary of the Invention

[0009] Therefore, one object of the present invention is to provide a system for determining rounding values ​​of optical characteristics suitable for providing refractive correction for improving the vision of a subject, the system comprising an optical device for performing a subjective test and a computer, the subjective test comprising evaluating the visual performance of the subject placed in two different optical conditions, the computer comprising one or more processors programmed to perform the following steps:

[0010] a) Determine the first test value of the optical feature and the first increment of change of the optical feature.

[0011] b) Using the optical device, perform a first trial of the subjective test, wherein two distinct first optical conditions are determined based at least on the first test value.

[0012] c) Determine a second test value for the optical feature based on the first test value, the first change increment, and the result of the first test performed in step b).

[0013] d) Using the optical device, perform a second test of the subjective test, wherein two distinct second optical conditions are determined based at least on the second test value.

[0014] e) Determine an intermediate value for the optical feature based on the results of the first test performed in step b) and the results of the second test performed in step d).

[0015] f) The rounding value of the optical feature is determined by rounding the intermediate value to a reference value, wherein the rounding modifies the refractive correction of the ophthalmic lens to be less than a predetermined basic refractive value.

[0016] The phrase "modifying the refractive correction of the ophthalmic lens to be less than a predetermined baseline refractive value" means that the difference in refractive correction provided by an ophthalmic lens that presents an optical characteristic value equal to this intermediate value and an ophthalmic lens that actually presents a rounded value of that optical characteristic value will be less than the baseline refractive value. The "refractive correction" of this lens corresponds to the overall optical power of the lens obtained using its optical characteristics (such as spherical power, cylindrical power, and axis).

[0017] This reference value refers, for example, to a predetermined standard value. This reference value may be included, for example, in a set of predetermined standard values ​​for the corresponding optical features that can be ordered or manufactured.

[0018] Therefore, due to the system according to the invention, the rounded value of the optical feature can correspond to the standard value of the optical feature. This allows obtaining a value of the desired optical feature that is compatible with the standard values ​​currently used to manufacture the lens.

[0019] These predetermined standard values ​​are preferably regularly spaced discrete values. The basic refractive value represents this regular interval. In practice, it is equal to the difference between two successive standard values ​​in a set of standard values.

[0020] In the examples described here, the standard value is equal to a multiple of the basic refractive value. A "multiple" means that the standard value is the product of the basic refractive value and an integer. For example, spherical lenses are typically prescribed and manufactured as a multiple of 0.25D.

[0021] In this case, when the intermediate value of the optical feature is different from a multiple of the predetermined basic refractive value, the processor can be programmed to round the intermediate value to the nearest or second nearest multiple of the predetermined basic refractive value in step e).

[0022] The system according to the invention can also take into account the subject's personal characteristics. This provides the system with adaptability. Here, in a general sense, personal characteristics are any characteristics related to the subject's physical or optical conditions.

[0023] Therefore, the processor can be further programmed to determine the first increment of change in step a) based at least on the subject’s first human characteristic.

[0024] Adapting this increment of change (here, the first increment of change, but also any subsequent increments of change) to the subject allows, for example, a reduction in the number of subjective tests to be performed before determining the intermediate value of the optical characteristic.

[0025] When the difference between two different optical conditions is based on the increment of change, adapting the increment of change to the subject also prevents uncertain answers when the subject cannot perceive the difference between the two optical conditions.

[0026] For example, in a spherical power determination test, this increment can increase with the subject's age. For a 20-year-old subject with good vision, it could be equal to 0.30D; for a 50-year-old subject with myopia, it could be equal to 0.55D; and for an 85-year-old patient presenting with multiple conditions, it could be equal to 1.30D.

[0027] The processor can also be further programmed to round the intermediate value in step f) according to a rounding method that depends on at least a second personal characteristic of the subject or on the type of subjective test performed. The second personal characteristic may be the same as the first personal characteristic or may be another personal characteristic that is different from the first personal characteristic.

[0028] For example, this also allows for selection between the closest or second closest multiple of the predetermined baseline refractive value based on the subject's age. For instance, for younger subjects, the intermediate value can be rounded to the lower of the closest or second closest multiple to prevent their eyes from becoming accustomed to the correction. For older subjects, the intermediate value can be rounded to the higher of the closest or second closest multiple to ensure that the correction adequately improves their vision.

[0029] As another example, for subjects with myopia, the intermediate value is preferably rounded to the lower of the nearest or second nearest multiple, while for subjects with hyperopia, the intermediate value is preferably rounded to the lower of the nearest or second nearest multiple.

[0030] For subjects who primarily need correction for distance vision (e.g., professional drivers), the intermediate value is preferably rounded to a lower value, while for subjects who primarily need correction for near vision, the intermediate value is preferably rounded to a higher value among the closest or second closest multiples.

[0031] The intermediate value can also be rounded so that the difference between the rounded value and the value obtained from the subject's previous optical equipment is the smallest possible difference.

[0032] Other advantageous and non-limiting features of the system according to the invention are:

[0033] - The first person characteristic includes at least one of the following data relating to the subject: age, type of refractive error, visual acuity, requests regarding their visual performance or current visual correction devices, historical data including the subject's current correction, condition, visual needs or activities, chosen eyeglass frames, chosen ophthalmic lenses, and optical characteristics of the subject's eyes.

[0034] - The second person characteristic includes at least one of the following data relating to the subject: age, type of refractive error, visual acuity, requests regarding their visual performance or current visual correction devices, historical data including the subject's current correction, condition, visual needs or activities, chosen eyeglass frames, chosen ophthalmic lenses, and optical characteristics of the subject's eyes.

[0035] -The processor is further programmed to determine two distinct first optical conditions based on the first change increment in step b);

[0036] - During the subjective test, the subject is placed in the two different optical conditions by achieving at least one of the following:

[0037] - Displays targets placed in red and green environments.

[0038] - Add cross-cylinder lenses at two different positions in front of the subject's eyes.

[0039] - Place two lenses with different spherical powers in front of the subject's eyes.

[0040] - Display two targets of different sizes.

[0041] - Place different lenses in front of the subject's right and left eyes;

[0042] -The optical feature includes at least one of the following:

[0043] -The spherical power of the ophthalmic lens

[0044] - The cylindrical power of the ophthalmic lens

[0045] - The cylinder axis of the ophthalmic lens.

[0046] -The difference in spherical power between two ophthalmic lenses placed in front of the right and left eyes;

[0047] -The processor is further programmed to perform the following steps:

[0048] g) Determine the current test value and the current increment of change based on the results of previous experiments and the previous test values ​​corresponding to the previous experiments.

[0049] h) The current trial that performs the subjective test includes assessing the subject's visual performance in two different current optical conditions determined at least based on the current test value.

[0050] i) Modify the current test value based on the current experiment and the current increment of change, and modify the current increment of change based on the result of the current experiment.

[0051] as well as,

[0052] Optionally, repeat steps h) and i).

[0053] Furthermore, the processor is programmed to determine the intermediate value based on the current test value in step e);

[0054] - The processor is further programmed to determine and / or modify the current change increment in step g) based on the degree of certainty of the results of the previously performed test;

[0055] - The current change increment is less than the predetermined basic refractive value;

[0056] -The processor is further programmed to modify it in step i) by decreasing the value of the current change increment;

[0057] - The processor is further programmed to perform step e) in the following cases:

[0058] - The current test value increased and decreased or decreased and increased successively in the last two successive trials, or

[0059] - The second test value is higher than the first test value, and the current test value determined in step g) is less than the second test value, or

[0060] - The second test value is less than the first test value, and the current test value determined in step g) is higher than the second test value;

[0061] - The processor is further programmed to perform step e) in the following cases:

[0062] - During the final trial, the subject evaluated the two final, different optical conditions to provide equivalent visual performance, and

[0063] - During the previous trial conducted prior to the final trial, the subject evaluated one of the two different prior optical conditions to provide better visual quality than the other prior optical condition.

[0064] The present invention also relates to a method for determining rounding values ​​of optical characteristics suitable for providing refractive correction for improving the vision of a subject, the method being performed by the system described above and including steps a) to f). Attached Figure Description

[0065] The following description, which is presented with reference to the accompanying drawings which are considered to be non-limiting examples, will help to understand the invention and how it is implemented.

[0066] In the attached diagram:

[0067] - Figure 1 This is a schematic diagram of the system according to the present invention;

[0068] - Figure 2 This is an illustrative representation of the invention based on... Figure 1A block diagram of the steps of a system implementation for determining rounding values ​​of optical characteristics suitable for providing refractive correction for improving the vision of a subject;

[0069] - Figure 3 Is Figure 1 A schematic diagram of the first decision tree of the first trial sequence of the first subjective test programmed in the first embodiment of the system for determining the spherical power value of an ophthalmic lens, wherein each trial of the first subjective test includes displaying a target placed in red and green environments;

[0070] - Figure 4 Is Figure 1 A schematic diagram of a second decision tree for a second trial sequence of a second subjective test programmed in a second embodiment of the system, designed to determine the cylinder axis value of an ophthalmic lens, wherein each trial of the second subjective test includes adding a cross cylinder at two different positions in front of the subject's eye;

[0071] - Figure 5 It is an illustration of a user interface that eye care professionals can use to determine rounded values ​​of optical characteristics;

[0072] - Figure 6 Is Figure 1 A schematic diagram of a third decision tree for a third test sequence of a third subjective test programmed in a third embodiment of the system, designed to determine the spherical power value of an ophthalmic lens, wherein each test of the third subjective test includes placing two lenses with different spherical powers in front of the subject's eye.

[0073] - Figure 7 Is Figure 1 A schematic diagram of the fourth decision tree of the fourth trial sequence of the fourth subjective test programmed in the fourth embodiment of the system, designed to determine the spherical power value of an ophthalmic lens under accommodative relaxation of the subject, wherein each trial of the fourth subjective test includes displaying two targets of different sizes;

[0074] - Figure 8 Is Figure 1 A schematic diagram of a fifth decision tree for a fifth trial sequence of a fifth subjective test programmed in a fifth embodiment of the system, designed to determine binocular balance values ​​of two ophthalmic lenses suitable for a subject’s eyes, wherein each trial of the fifth subjective test includes showing different lenses placed in front of the subject’s right and left eyes. Detailed Implementation

[0075] Figure 1 System 1 according to the present invention includes an optical device 2 and a computer 3.

[0076] The optical device 2 is suitable for performing subjective tests by providing the subject with two different optical conditions.

[0077] As will be described in more detail later, different subjective tests can be performed to determine the optical characteristics of ophthalmic lenses. Each subjective test is associated with a specific optical condition provided to the subject. These optical conditions, and therefore the optical devices suitable for providing them, can have different characteristics depending on the optical characteristics determined by the corresponding subjective test.

[0078] The optical feature may include refractive optical features (i.e., optical features measured in diopters) or orientation (i.e., optical features representing angles, such as those measured in degrees).

[0079] Here, the optical characteristics include, for example, one or more of the following: spherical power, cylindrical power, cylindrical axis, and the difference in spherical power between the right and left eyes.

[0080] Therefore, the subjective test may include one or more of the following:

[0081] - Two-color test to determine spherical lens power

[0082] - Cross-cylinder test to determine cylinder power and / or axis.

[0083] - Acuity test without adjustment or relaxation to determine spherical lens power.

[0084] - Acuity testing under relaxed conditions to determine spherical lens power.

[0085] - Binocular balance test.

[0086] Detailed examples will be provided later.

[0087] Therefore, the corresponding optical device may include optical means for:

[0088] - A test lens with optical characteristics equal to the test value is placed in front of the subject's eyes, and a target including a symbol placed in a red or green environment is simultaneously displayed.

[0089] - Display a target with multiple elements, and add cross-cylinder lenses placed sequentially at two different positions in front of the subject's eye, depending on the cylinder axis test values.

[0090] - Two test lenses with optical characteristics equal to two different test values ​​(different spherical powers) are placed successively in front of the subject's eyes, and the target is displayed.

[0091] - Place a test lens with optical characteristics equal to the test value in front of the subject's eyes, and display two targets of different sizes.

[0092] - Different test lenses are placed simultaneously in front of the subject's right and left eyes, and a target is displayed for each eye.

[0093] In practice, the optical device 2 includes, for example, a comprehensive refractive instrument equipped with test lenses having variable optical characteristics.

[0094] As a variant, the optical device 2 may also include a set of test lenses with different values ​​of the optical characteristics.

[0095] Additionally, the optical device 2 includes a means for displaying the target. The means for displaying the target can be any type of display device, such as a screen. It can include an active digital screen (such as a liquid crystal display) or a passive screen and projection device.

[0096] Depending on the subjective test being performed, the optical device 2 may also include a cross-cylinder lens.

[0097] Optical device 2 Figure 3 , Figure 4 , Figure 6 , Figure 7 and Figure 8 The first through fifth subjective tests shown are described in more detail.

[0098] Computer 3 includes, for example, one or more processors and one or more memories. Here, specifically for implementation... Figure 2 The steps shown, including instructions for determining rounding values ​​of optical characteristics suitable for providing refractive correction of an ophthalmic lens to improve the subject's vision, are stored in the one or more memories. The one or more processors are then programmed to perform these steps.

[0099] Here, computer 3 includes a user screen for displaying information to eye care professionals and an input device that allows eye care professionals to interact with the computer. The input device may include a keyboard, mouse, touchscreen, voice controller, the modern touch-enabled user screen itself, or any other known input device.

[0100] Figure 5 An example of a user interface displayed on a user's screen is shown, which is described in more detail using a second subjective test performed according to the method of the present invention.

[0101] Here, computer 3 includes a communication device that allows the computer to connect to optical device 2 and command the optical device (e.g., command the target screen of optical device 2).

[0102] Figure 2 A method, implemented by System 1, is demonstrated for determining rounding values ​​of optical characteristics suitable for providing refractive correction for improving the vision of a subject.

[0103] In all embodiments of the present invention, the method includes the following steps:

[0104] a) Determine (400) the first test value of the optical feature and the first increment of change of the optical feature.

[0105] b) Using the optical device to perform a first test of the (500) subjective test, wherein two distinct first optical conditions are determined based at least on the first test value.

[0106] c) Determine (600) a second test value for the optical feature based on the first test value, the first change increment, and the result of the first test performed in step b).

[0107] d) Using the optical device to perform a second test of the subjective test (700), wherein two distinct second optical conditions are determined based at least on the second test value.

[0108] e) Determine (800) an intermediate value for the optical feature based on the results of the first test performed in step b) and the results of the second test performed in step d).

[0109] f) Determine the rounding value of the optical feature by rounding the intermediate value to a reference value, wherein the rounding modifies the refractive correction of the ophthalmic lens to less than a predetermined basic refractive value.

[0110] This method is not limited to two trials of subjective testing. In fact, the number of trials of the subjective test required to determine the intermediate value can be more than two.

[0111] The processor can be further programmed to perform the following steps:

[0112] g) Determine (710) the current test value and the current increment of change based on the results of previous trials and based on the previous test values ​​corresponding to the previous trials.

[0113] h) The current trial performing the subjective test described in (720) includes evaluating the visual performance of the subject placed in two different current optical conditions determined at least based on the current test value.

[0114] i) Modify (730) the current test value based on the current experiment and the current increment of change, and modify the current increment of change based on the result of the current experiment.

[0115] as well as,

[0116] Optionally, repeat steps h) and i).

[0117] And in step e), the intermediate value is determined based on the current test value.

[0118] In the following text, the term "current" refers to any subjective test following the first and second tests, and the test value and increment of change associated with this current test. In step i), modifying the current test value and the current increment of change means that these two parameters are incremented, updated, or adjusted.

[0119] In general, a prior test refers to any test that occurred before the current test. It can be the first test, the second test, or any other test that occurred before the current test. In practice, the current test value, and optionally the current increment of change, is determined based on the test value and / or increment of change of the previous test. It can be the second test or any other test that occurred before the current test. However, given the sequential nature of tests, the current test value and the current increment of change still depend on the test values ​​and increments of change of all prior tests.

[0120] Step a)

[0121] In the first step a), the first test value V1 of the optical feature is determined.

[0122] The first test value can be determined based on the subject's historical data, the results of previous subjective tests, or objective measurements.

[0123] For example, this first test value can be obtained from the subject's previous optical equipment. This determination of the first test value is particularly meaningful when the subject is already wearing ophthalmic lenses and when he / she wishes to adjust his / her current correction.

[0124] The first test value may also be determined based on the results of other prior subjective tests or based on the results of previous trials of the same subjective test. The previous trial of the subjective test may have been performed by the same eye care professional performing the method according to the invention prior to step a). Another prior subjective test may have been performed prior to the current subjective test or in the past by the same eye care professional or another eye care professional.

[0125] In this case, the determination of the first test value can take into account the degree of certainty of the result of the subjective test.

[0126] When the optical characteristic is a refractive optical characteristic, the first test value can be determined by an objective refractive test. This objective refractive test can be performed using a retinoscopy device or an automated refractometer that can be included in the optical device 2. This objective refractive test can be performed by the same eye care professional who performed step a) prior to step a). It can also be performed by another eye care professional, or it can have been performed in the past.

[0127] The first test value can also be determined by an eye care professional based on the subject’s personal characteristics or a combination of personal characteristics.

[0128] The subject's personal characteristics may include either the first or the second personal characteristics described below.

[0129] Additionally, in the first step a), the first change increment I1 is determined.

[0130] The first increment of change I1 can be a predetermined value, depending on the subjective test performed in step b).

[0131] It can also be determined based on the results of other previous subjective tests or the results of previous trials based on the same subjective test.

[0132] In this case, the determination of the first increment of change can take into account the degree of certainty of the results of the subjective test.

[0133] In an embodiment, the processor is programmed to determine the first change increment I1 in step a) based at least on the subject’s first human characteristic.

[0134] The first personal characteristic may include, for example, at least one of the following data relating to the subject: age, type of refractive error, visual acuity, requests regarding their visual performance or current visual correction devices, including the subject's history of current correction, medical conditions, visual needs or activities, chosen eyeglass frames, chosen ophthalmic lenses, and the optical characteristics of the subject's eyes. The optical characteristics of the subject's eyes may include, for example, eye aberrations, eye opacity, and objectively measured optical characteristics of the eyes. The first personal characteristic may also include a range relating to the subject's sensitivity, that is, the magnitude of their ability to perceive changes in refractive correction from lenses.

[0135] For example, when determining the spherical lens power, such as in the first subjective test, the third subjective test, and the fourth subjective test, for subjects with low visual acuity (e.g., 3 / 10), the first increment of change is preferably greater than 1D, while for subjects with high visual acuity (e.g., 12 / 10), the first increment of change is preferably less than 0.5D or 0.3D.

[0136] As will be described later, the first change increment I1 is used in step c) to determine the second test value V2 used in the second trial of the subjective test.

[0137] Preferably, the first increment of change I1 is higher than the baseline refractive value. This first increment of change I1 is, for example, higher than 0.3D or 10 degrees. This allows for rapid convergence to a test value representing the required correction for the subject. In other words, this allows for a reduction in the number of trials required to determine the rounding value of the optical characteristic. The first increment of change I1 used in the first trial of this subjective test is also preferably higher than the increment value used in further trials of this subjective test, as described in more detail below.

[0138] Step b)

[0139] Two distinct first optical conditions are determined based at least on this first test value V1.

[0140] After determining the first test value V1, in step b), the first trial of the subjective test is performed.

[0141] Therefore, two distinct first optical conditions, S1 and S2, are determined at least based on the first test value V1 and presented to the subject via the optical device 2. During the first trial of this subjective test, the subject is asked to gaze at one or more targets through one or more test lenses whose characteristics (e.g., their spherical power or their orientation) are based on the first test value 1. Here, the targets are displayed on the target screen of the optical device 2.

[0142] These two different first optical cases, S1 and S2, can also take into account the first variation increment I1. For example, this is the case of the third subjective test, which will be described later.

[0143] During the first trial of this subjective test, the subject is asked to compare two first optical conditions S1 and S2; that is, based on the subject's perception, they are asked to assess which of the two first optical conditions S1 and S2 provides better visual performance. To obtain this information, depending on the subjective test performed, an eye care professional may ask, for example, "In which condition do you see the target better?" or "Which target do you see better?"

[0144] It is possible that, in either of the first optical conditions S1 or S2, the subject is unable to clearly distinguish the target. In this case, the subject assesses in which condition he can better distinguish the target.

[0145] The results of this subjective test include the subject's answers to assess which of the two first optical conditions, S1 and S2, provides better visual quality, for example, as an answer to one of the reference questions above. In this way, the results here could include one of three different answers:

[0146] i) First answer: The subject indicated that, given optical condition S1, S2, provided better visual quality, or in other words, better visual performance, than the other optical condition S2.

[0147] ii) Second answer: The subject indicated that the other optical condition S2 of the two optical conditions S1 and S2 provided better visual quality, in other words, better visual performance than the previously considered optical condition S1;

[0148] iii) Third answer: The subject indicated that the two optical conditions S1 and S2 provided equivalent visual performance, or that he could not choose the better optical condition between the two. This final instruction demonstrates an answer of "I don't know".

[0149] As a variant, the answer can be defined as follows: the first answer can indicate that neither optical condition provides good visual quality, the second answer can indicate that both optical conditions provide good visual quality, and the third answer can indicate that one of the two optical conditions provides good visual quality.

[0150] In the following text, for each experiment, the two optical cases will be represented by the same references S1 and S2, although they differ in each experiment. The optical case referenced by S1 in each experiment is hereinafter referred to as the first type of optical case, while the optical case referenced by S2 in each experiment is hereinafter referred to as the second type of optical case. As will be explained in detail later, the first type of optical case has common characteristics or common differences with respect to the second type of optical case.

[0151] For example, in a two-color test, the optical situation S1 corresponding to a green target would be type one, while the optical situation S2 corresponding to a red target would be type two. In a sharpness test, the optical situation S1 corresponding to a target with lower sharpness or a lens with lower spherical power would be type one, while the optical situation S2 corresponding to a target with higher sharpness or a lens with higher spherical power would be type two.

[0152] The optical conditions marked S1 or S2 correspond to each other.

[0153] In practice, eye care professionals input the results of this subjective test into a computer via an input device. For example, in... Figure 5On the user interface shown, when the result of the first test is the first answer, the eye care professional selects (e.g., by clicking) the left button 50. When the result is the second answer, he selects the right button 52. When the result is the third answer, he selects the center button 51.

[0154] exist Figure 3 , Figure 4 , Figure 6 , Figure 7 and Figure 8 The first through fifth subjective tests, as shown, describe in more detail the experimentation of the subjective tests and the dependence of the two optical conditions on the test values ​​and the possible increments of change.

[0155] Step c)

[0156] In step c), a second test value V2 for the optical feature is determined. This second test value V2 is determined specifically based on the first test value V1, the first change increment I1, and the results of the first test performed in step b).

[0157] The determination of the second test value can take into account the degree of certainty of the results of the first test.

[0158] Here, the second test value V2 is calculated, for example, as the sum or difference between the first test value V1 and the first change increment I1, that is, by adding or subtracting the first change increment I1 to the first test value V1. For example... Figure 3 As shown, the second test value V2 can therefore be calculated according to the following equation V2=V1±I1, where the sign ± indicates the + or - sign.

[0159] The second test value V2 can also be calculated as a weighted sum or difference between the first test value V1 and the first change increment I1. For example... Figure 6 As shown, the second test value V2 can therefore be calculated according to the following equation V2=V1±C x I1, where C is the actual positive coefficient, for example, included between 0.1 and 5, preferably included between 0.5 and 2.

[0160] The results of the first test determine 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.

[0161] Depending on the subjective test, obtaining the first or second answer as the result of the first test will cause the second test value V2 to be greater than or less than the first test value V1, respectively.

[0162] Depending on the subjective test, obtaining the third answer as the result of the first trial causes the second test value V2 to be greater than or less than the first test value V1. In other words, in the first trial of this subjective test, the third answer is processed as either the first answer or the second answer.

[0163] In fact, obtaining a third answer as the result of the first trial can be seen as a misunderstanding of the subjective test by the subject. Therefore, the second test value V2 is also determined to be higher or lower than the first test value V1 after the third answer. Depending on the subjective test, as long as the third answer is obtained successively as the result of subsequent trials, the test value increases or decreases from one trial to the next.

[0164] In a preferred embodiment, the second increment of change I2 is further determined, for example, based on the results of the first test and based on the first increment of change I1. Preferably, the second increment of change I2 is less than the first increment of change I1: it decreases. Also preferably, the second increment of change I2 may be lower than the baseline refractive value.

[0165] As a variant, the second increment is larger than the baseline refractive value. This allows for the performance of rapid subjective tests.

[0166] The determination of this second increment can take into account the degree of certainty of the results of the first experiment.

[0167] Step d)

[0168] In step d), two different second optical conditions are determined based on the second test value V2, one being S1 of the first type and the other being S2 of the second type, and the second test of the subjective test is performed using these different second optical conditions.

[0169] The second trial of the subjective test is similar to the first trial. The difference between the second and first trials is that the two different optical conditions S1 and S2 provided to the subject depend on the second test value V2, rather than on the first test value V1.

[0170] In the same manner as the first experiment, two different second optical cases S1 and S2 can also take into account the second variation increment I2.

[0171] During the second trial of this subjective test, the subject was asked to compare two second optical scenarios to assess which one provided better visual performance. The result of this second trial was also determined by the subject's first, second, or third answer.

[0172] The first answer corresponds to the subject indicating that the second optical condition S1 of the first type provides better visual performance among the two second optical conditions, the second answer corresponds to the subject indicating that the second optical condition S2 of the second type provides better visual performance, and the third answer corresponds to the subject indicating that the two second optical conditions S1 and S2 provide equivalent visual performance or that he cannot choose the better optical condition among the two second optical conditions.

[0173] Step g)

[0174] The first and second trials described above can actually correspond to the two initial trials performed when the test sequence of the subjective test begins. They can also correspond to any two successive trials in the test sequence.

[0175] More generally, during each trial of this subjective test, the subject is asked to compare two current optical conditions, one of type 1 S1 and the other of type 2 S2, to assess which of the two current optical conditions provides better visual performance.

[0176] Therefore, the further steps of the method according to the invention are described below in a more general manner.

[0177] In step g), the current test value VC is determined. The current test value VC is determined by considering the results of previous tests and subjective tests. Here, the current test value VC is also determined by considering previous increments of change.

[0178] The previous test value, previous increment of change, and previous trial are referred to below as the previous test value, increment of change, and trial. It can be the second test value, the second increment of change, and the second trial.

[0179] Since all test values ​​are determined by taking into account previous test values ​​and previous trial results, the current test value is determined in particular by taking into account the second test value V2, the result of the second trial of the subjective test performed in step d), and the second change increment I2.

[0180] The current test value VC is calculated, for example, as the sum or difference between the previous test value VP and the previous increment of change IP. The current test value V2 can therefore be calculated according to the following equation: VC = VP ± IP.

[0181] The current test value VC can also be calculated as a weighted sum or difference between the previous test value VP and the previous change increment IP. The current test value VC can therefore be calculated according to the following equation: VC = VP ± C x IP, where C is the actual positive coefficient, for example, included between 0.5 and 2.

[0182] The results of previous trials of this subjective test determine whether the current test value VC is higher or lower than the previous test value VP.

[0183] In practice, depending on the subjective test, the first answer (the subject indicates the first type of optical condition S1) and the second answer (the subject indicates the second type of optical condition S2) will respectively cause the current test value VC to be higher or lower than the previous test value VP.

[0184] Depending on the subjective test and the results of previous trials, the third answer either leads to the calculation of the current test value VC or directly determines the intermediate value VI. More precisely, when the result of previous trials is the first or second answer, the third answer directly leads to the determination of the intermediate value VI.

[0185] Furthermore, the current increment of change (IC) can be determined, for example, based on the results of previous subjective tests and based on previous increments of change.

[0186] Here, the processor can be further programmed to determine the current change increment IC and / or the current test value based on the degree of certainty of the results of the previous test (preferably the previous test).

[0187] In a general manner, to account for the subject's degree of certainty, confidence data indicating the subject's degree of certainty when giving a first, second, or third answer is collected and recorded in the one or more memories, and associated with the corresponding answer for each trial of the subjective test. Here, the degree of certainty is defined as in document US2019261848. Therefore, the confidence data may be based on a measurement of the duration it takes for the subject to give their answer while viewing the target, or on other measurements via sensors, such as a pressure sensor associated with a button the subject uses to record their answer. Any means known to those skilled in the art can be used.

[0188] For example, when the current test result is either the first or second answer but uncertain—that is, when the degree of certainty is below a predetermined threshold—it is preferable to reduce the increment of change. In practice, this means that the current test value is close to the correction required for the subject.

[0189] When the degree of certainty is high, the first or second answer may be treated as the third answer.

[0190] Step h)

[0191] At least based on the current test value VC, two different current optical conditions can be determined, one is type 1 S1 and the other is type 2 S2.

[0192] The current trial of this subjective test was conducted by presenting the subject with two current optical conditions.

[0193] The current test is similar to the first and second tests.

[0194] In the same manner as the first and second trials, two different current optical conditions S1 and S2 can also be determined based on the second current incremental IC.

[0195] During the current trial of this subjective test, the subject is asked to compare two current optical conditions to assess which provides better visual quality. The result of this current trial is also determined by the subject's first, second, or third answer.

[0196] Step i)

[0197] 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 based on the current change increment IC.

[0198] Here, the updated current test value VCup after modification is calculated, for example, as the sum or difference between the current test value VC and the current change increment IC. This updated current test value VCup can therefore be calculated according to the following equation: VCup = VC ± IC.

[0199] In practice, the first answer and the second answer will cause the current test value VC to increase or decrease respectively, that is, the updated current test value is lower or higher than the current test value.

[0200] Depending on the subjective test and the results of the first and second trials, the third answer causes an increase or decrease in the current test value VC; that is, it determines the updated current test value that is higher or lower than the current test value, or directly determines the intermediate value VI. More precisely, when the result of the previous trial test (i.e., the first trial, the second trial, or the current trial) is the first or second answer, the third answer causes the direct determination of the intermediate value VI.

[0201] After modifying the current test value, i.e. after calculating the updated current test value VCup, the current change increment IC is modified based on the results of the current test.

[0202] The updated test value VCup will be considered as the current test value in the next current trial.

[0203] In the same manner as determining the current test value, the processor can be further programmed to modify the current increment of change based on the degree of certainty of the results of the previous trials.

[0204] Here, preferably, after several repetitions of steps h) and i), for example, 1 to 4 repetitions, the current increment of change is less than the predetermined basic refractive value.

[0205] In this way, the current test value VC can have a smaller precision than the baseline refractive value. Therefore, this current test value can accurately represent the correction required by the subject. Consequently, the intermediate value VI determined in step e) also accurately represents the correction required by the subject.

[0206] As a variant, this current increment of change can be greater than the predetermined baseline refractive value. This allows for the performance of rapid subjective testing.

[0207] In one embodiment, the processor is further programmed to modify the current change increment in step i) by decreasing the value of the current change increment.

[0208] This also allows for the determination of very precise current test values, i.e., with an accuracy higher than the baseline refractive value.

[0209] The processor stops repeating steps h) and i) or does not execute them at all when either the first or second stopping condition occurs. In other words, the processor executes step e) when these stopping conditions occur.

[0210] The first stopping condition occurs under the following conditions:

[0211] - During the final trial of this subjective test, in other words, during the last executed trial, the subject evaluates two final, different optical conditions to provide equivalent visual performance; that is, the result of this final trial is the third answer, and

[0212] - During the prior trial of the subjective test performed before the final trial, the subject evaluated one of two different prior optical conditions to provide better visual quality than the other prior optical condition, i.e., the result of the final trial was the first answer or the second answer.

[0213] Here, the final trial of the subjective test is the second trial or any further current trial. The previous trial can be any trial performed before the final trial. More precisely, the previous trial is the one performed before the final trial.

[0214] When this first stopping condition occurs, it means that the test value taken during this final trial accurately represents the correction required by the subject.

[0215] The second stopping condition occurs under the following circumstances:

[0216] - The current test value has successively increased and decreased or decreased and increased in the last two successive trials, or

[0217] - The second test value is higher than the first test value, and the current test value determined in step g) is less than the second test value, or

[0218] - The second test value is less than the first test value, and the current test value determined in step g) is higher than the second test value.

[0219] For example, when three successive trials, referred to as the first trial, the second trial, and the current trial, have been performed, the second stopping condition may occur under the following conditions:

[0220] - The updated current test value is higher than the current test value, and the current test value is lower than the second test value, or

[0221] - The updated current test value is lower than the current test value, and the current test value is higher than the second test value.

[0222] The second stopping condition allows for the faster determination of the intermediate value VI (i.e., by performing fewer trials) compared to simply waiting for the first condition to occur. In practice, this means that the intermediate value VI can be determined even if a third answer is not given, i.e., even if the correction required by the patient is not tested as a test value during the trial.

[0223] In this case, the determined median value VI is included between the two final test values. For example, here, the median value VI is determined as the average between the two final test values. This allows for the determination of the median value IC that accurately represents the correction required for the subject.

[0224] Step e)

[0225] In step e), the intermediate value VI of the optical feature is determined based on the results of the first and second test performed in steps b) and d).

[0226] As described above, depending on the results of the first and second trials, step e) can be performed immediately after step d). In this case, only the first and second trials are performed.

[0227] For example, this is the case when the first stopping condition occurs after the second trial.

[0228] In this case, the median value VI is equal to the second test value V2.

[0229] As described above, depending on the results of the first and second trials, step e) can be performed immediately after step g). In this case, only the first and second trials are performed.

[0230] For example, when the second stopping condition occurs after the current test value is determined in step g), i.e. when the second test value is higher than the first test value and the current test value determined in step g) is less than the second test value, or when the second test value is less than the first test value and the current test value determined in step g) is higher than the second test value, the intermediate value VI can be calculated as the average value between the current test value and the second test value.

[0231] When further experiments are conducted, the current test value VC and the current increment of change are determined, and the determination of the intermediate value VI is also based on the current test value VC and the current increment of change VI.

[0232] When further testing is conducted, the intermediate value VI can, for example, be equal to the last test value or be calculated as the average between the two last test values.

[0233] For example, when the current test value increases and decreases or decreases and increases successively in the last two successive trials (i.e., in the last two implementations of steps h and i), the intermediate value VI can be calculated as the average value between the two last current test values.

[0234] As an example, if the result of the current test is the third answer, the intermediate value VI can be determined to be equal to the current test value.

[0235] Step f)

[0236] After determining the intermediate value VI, the rounding value of the optical feature is determined by rounding the intermediate value VI to a reference value.

[0237] The rounding is performed so that the refractive correction of the ophthalmic lens is modified to be less than the predetermined basic refractive value.

[0238] When the optical feature is a refractive optical feature, this means that the difference between the rounded value and the median value is less than the basic refractive value.

[0239] When this optical characteristic is the cylinder axis, it means that the orientation difference between the rounded value and the median value is perceived by the subject as a change in cylinder power smaller than the basic refractive value. In fact, in a manner well-known in the field of cylinder lenses, a change in the cylinder axis orientation causes a refractive change in the cylinder power. Therefore, a modification to the cylinder axis can be translated into a modification of the cylinder power.

[0240] Therefore, when the optical feature is the cylinder axis, modifying the refractive power of the ophthalmic lens to be less than the predetermined basic refractive value means that the refractive change in the cylinder power caused by the change in the cylinder axis is less than the predetermined basic refractive value.

[0241] For example, when the cylindrical power is less than 1.5D, the axis can be rounded to a multiple of 5 degrees. However, when the cylindrical power is greater than 1.5D, rounding to 5 degrees may cause a change in cylindrical power greater than 0.25D. Therefore, when the cylindrical power is greater than 1.5D, this intermediate value is preferably rounded to a multiple of 2 degrees.

[0242] The observed refractive changes also depend on the cylindrical power of the test lens itself.

[0243] This baseline refractive value can be determined by an eye care professional based on the precision of the prescription they intend to provide. A baseline refractive value might be, for example, 0.25D.

[0244] As mentioned above, this reference value is a standard value used in the manufacture of ophthalmic lenses. Here, when the optical feature is a refractive optical feature, the reference value is more accurately defined as a multiple of the basic refractive value. When the optical feature is a cylinder axis, the reference value is defined as a multiple of a given angle, such as five degrees.

[0245] Here, when the optical feature is a refractive optical feature, one or more processors of the optical device 2 are more precisely programmed to round the intermediate value to the nearest or second nearest multiple of the predetermined basic refractive value when the intermediate value of the optical feature is different from a multiple of the predetermined basic refractive value.

[0246] For example, when the intermediate value VI determined in step e) is 0.87D and the basic refractive value is 0.25D, the nearest or second nearest multiple of 0.25D is 0.75D and 1D. Therefore, the intermediate value VI can be rounded to 0.75D or 1D.

[0247] In the same manner, when the optical feature is a cylindrical axis, 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 given angle when the intermediate value of the optical feature is not a multiple of the given angle.

[0248] For example, when the intermediate value VI determined in step e) is 17 degrees and the basic refractive value is 5 degrees, the multiples of 5 degrees closest to and second closest to 17 degrees D are 15 degrees and 20 degrees: the intermediate value VI can be rounded to 15 degrees or 20 degrees.

[0249] Here, the processor is further programmed to round the intermediate value VI according to a rounding method that depends at least on a second personal characteristic of the subject or on the type of subjective test performed.

[0250] The second person characteristic includes, for example, at least one of the following data relating to the subject: age, type of refractive error, visual acuity, requests regarding their visual performance or current visual correction devices, including the subject's history of current correction, condition, visual needs or activities, chosen eyeglass frames, chosen ophthalmic lenses, and the optical characteristics of the subject's eyes.

[0251] For example, for subjects whose age exceeds a threshold, the median value VI is preferably rounded to the higher of the closest and second closest values, while for subjects whose age is below the threshold, the median value VI is preferably rounded to the lower of the closest and second closest values.

[0252] Following the example of the median value VI determined in step e) being 0.87D, for older subjects, the median value VI is preferably rounded to a higher value, i.e., 1D, while for younger subjects, the median value VI is preferably rounded to a lower value, i.e., 0.75D.

[0253] According to other examples, for subjects with visual acuity exceeding a given threshold and / or no need regarding their visual performance or current visual equipment and / or no specific condition, with low visual needs, or with activities that do not require improvement in visual acuity, the median value may be rounded to the lower of the nearest or second nearest multiple. For subjects with visual acuity below the threshold, and / or a need regarding their visual performance or current visual equipment, and / or with a specific condition, and / or with high visual needs, and / or with activities that require improvement in visual acuity, the median value may be rounded to the higher of the nearest or second nearest multiple.

[0254] Now for reference Figures 3 to 8 Five subjective tests are described, each comprising a sequence of tests. The sequence of tests includes all steps a) to f) of the method according to the invention, and thus allows for the determination of a rounded value for the optical characteristic. Hereinafter, when a test value is determined to be the sum of a previous test value and a previous increment of change, it is referred to as an increase. Conversely, when a test value is determined to be the difference between a previous test value and a previous increment of change, it is referred to as a decrease.

[0255] Here, in most of the described examples, the first answer corresponds to indicating that the first type of optical condition S1 gives better visual performance than the other type of optical condition, the second answer corresponds to indicating that the second type of optical condition S2 gives better visual performance than the other type of optical condition, and the third answer corresponds to indicating that the first type and the second type of optical conditions S1 and S2 both give equivalent visual performance.

[0256] As a variation, such as the description related to the fourth subjective test, the first answer could correspond to indicating that neither optical condition provides good visual quality, the second answer could correspond to indicating that both optical conditions provide good visual quality, and the third answer could correspond to indicating that one of the two optical conditions provides good visual quality.

[0257] The first and second answers will be represented in the diagram by referring to the corresponding optical conditions S1 and S2. The third answer will be represented in the diagram by referring to M.

[0258] exist Figure 3 , Figure 4 , Figure 6 , Figure 7 and Figure 8 The text uses a common reference for the first, second, and third answers.

[0259] First subjective test

[0260] Figure 3 The decision tree for the first subjective test sequence is shown.

[0261] In this first subjective test, the optical characteristic of the ophthalmic lens is spherical power.

[0262] Each test involves displaying two targets, each including a symbol placed in a red and green environment, and providing the subject with a test lens with a test spherical power value.

[0263] This subjective test is often referred to as the "two-color test." Here, this subjective test is a monocular test. The rounding value is determined for one eye. The sequence can be performed a second time for the other eye or in parallel. In this latter case, the first subjective test can therefore be a binocular test.

[0264] The target is displayed on the target screen of the optical device 2.

[0265] In the first type of optical situation S1, the first of the two targets includes a symbol displayed against a uniform green background. The symbol includes, for example, a target or a geometric shape.

[0266] In the second type of optical scenario S2, the second target of the two targets includes a symbol displayed against a uniform red background. The symbol includes, for example, a visual target or a geometric shape. This second symbol may be the same as the first symbol.

[0267] During each trial, the subject was asked to view two targets through a test lens with a test spherical power equal to the test value and to identify which target's symbol appeared clearer.

[0268] In step a), Figure 3 The first test value, marked as 100, can be determined, for example, as the subject's current correction, or based on objective or subjective measurements.

[0269] For the first test, the test spherical power of the test lens is equal to the first test value V1.

[0270] If the subject sees the symbol more clearly on a green background than on a red background, then the result of the first trial is answer 110. Optically, this means that the test spherical power of the test lens is insufficient to provide adequate correction for the subject's eye. Therefore, in the next trial, it is increased. In step d), Figure 3 The second test value V2 is then determined as the sum of the first test value V1 and the first change increment I1, marked as 10.

[0271] If the subject sees the symbol more clearly against a red background than against a green background, then the result of the first test is the second answer, 120. Optically, this means that the spherical power of the test lens is too strong to provide adequate correction for the subject's eye. Therefore, in the next test, it is reduced. In step d), Figure 3 The value is marked as 20, and the second test value V2 is then determined as the difference between the first test value V1 and the first change increment I1.

[0272] More generally, when the result of the experiment is the first answer 110, 221, 211, 231, the test value is increased, and when the result of the experiment is the second answer 120, 222, 212, 232, the test value is decreased.

[0273] If the subject sees the symbol equally clearly against both green and red backgrounds, then the result of the first test is the third answer, 130. Optically, this means that the spherical power of the test lens is appropriate.

[0274] However, as mentioned above, obtaining a third answer as the result of the first trial is considered a misunderstanding of the test by the subject. Here, in this case, in step d), marked 30, the second test value V2 is also determined as the sum of the first test value V1 and the first change increment I1, as if the result of the first trial was the first answer.

[0275] If the result of successive trials is the third answer 233, the test value is determined to be the sum of the previous test value and the previous increment of change, i.e., increase.

[0276] Here, the median value VI (i.e., the rounded value) is sought to be the lower spherical power, in diopters, that produces equally clear signs in both optical conditions S1 and S2. Therefore, obtaining a second answer (the sign on the red background is clearer) is necessary before determining the median value. In fact, this is the only answer that ensures the experimental spherical power value is below the appropriate value for the subject's visual correction. This also avoids accommodation by the subject, as it could bias the determination of the median value.

[0277] That's why Figure 3 The expression in the text represents all branches of the decision tree that determine the intermediate value VI, including the second answer 212, 120, and 232 at a single point.

[0278] For example, when the results of two successive trials are the first answer 110, 211, 231, and then the second answer 212, the intermediate value VI1 is determined. In this case, the intermediate value VI1 is equal to the current test value VC, in step g) or i). Figure 3 The value VC is marked as 11, which is determined to be the difference between the previous test value V2 and the previous increment of change I2, where the previous increment of change I2 is equal to half of its preceding increment of change I1. Therefore, the current test value VC is the average of the previous two test values ​​V2 and V1. This situation corresponds to the second stopping condition.

[0279] When the results of two successive trials are the second answer 120, 222, and then the first answer 221, the intermediate value VI2 can also be determined. In this case, the intermediate value VI2 is equal to the current test value VC', in step g) or i). Figure 3 The value marked as 21 is determined to be the sum between the previous test value V2' and the previous increment of change I2', where the previous increment of change I2' is half of its preceding increment of change I1. This also corresponds to the second stopping condition.

[0280] An intermediate value VI3 can also be determined when the results of two successive trials are the second answer 120, 222, and then the third answer 223. In this case, the intermediate value VI3 is equal to the previously tested value V2' determined in steps c), g), or i). This situation corresponds to the first stopping condition.

[0281] Finally, when the results of two successive trials are the third answer 130, 233, 213, and then the second answer 232, the intermediate value VI4 can also be determined. In this case, the intermediate value VI4 is equal to the current test value VC”, in step g) or i). Figure 3 The value marked as 31 is determined to be the difference between the previous test value V2” and the previous change increment I2”, where the previous change increment I2” is equal to its previous change increment I1.

[0282] Preferably, the increment of change decreases between the first and last trials of the sequence. More preferably, it decreases from one trial to the next. For example, the first increment of change V1 is equal to 1D, and the second increment of change V2 is equal to 0.3D.

[0283] In another example, the current increment of change is calculated as the increment of change from the previous trial (preferably the one before the previous trial) multiplied by a coefficient strictly less than 1. Subsequently, this current increment of change preferably becomes even lower than the baseline refractive value. The baseline refractive value is, for example, 0.25D.

[0284] In this first sequence, in step f), the rounding value is determined by rounding the intermediate value to the nearest or second nearest multiple of the basic refractive value. As mentioned above, this rounding method can depend on the individual characteristics of the subject.

[0285] Second subjective test

[0286] Figure 3 The decision tree for the second subjective test is shown.

[0287] This second subjective test is often referred to as the "cross-cylinder test." It involves placing cross-cylinder lenses in two different positions—in this case, two different orientations—in front of the subject's eye. This subjective test is a monocular test. The rounding value is determined for one eye. The sequence can be performed a second time for the other eye.

[0288] In this example of the second subjective test, the optical feature is the cylindrical axis. However, similar subjective tests and similar decision trees can also be used to determine the cylindrical power.

[0289] During each trial, the subject was asked to view, for example, a target displayed on a target screen in optical device 2 through a trial lens (which is referred to as the "Jackson cross cylinder lens" and here as the cross cylinder lens).

[0290] In the first type of optical situation S1, the cross-cylinder is positioned in a first orientation.

[0291] In the second type of optical situation S2, the cross-cylinder lens is positioned with a second orientation. Here, the second orientation is the result of rotating 90 degrees relative to the first orientation around the eye's gaze axis, such that the positive and negative axes of the cross-cylinder lens are interchanged.

[0292] Here, the positive axis is defined as the axis where the power of the cross-cylinder lens is maximum, for example, equal to +0.25D or +0.5D. The negative axis is defined as the axis where the power of the cross-cylinder lens is minimum, for example, equal to -0.25D or -0.5D.

[0293] When determining the cylinder axis, for each test, the cross cylinder is positioned relative to the test cylinder axis value. Here, the test cylinder axis value is an angle in degrees relative to a predetermined direction, such as the horizontal direction. In the first type of optical case S1, the positive axis of the cross cylinder is oriented to be rotated counterclockwise at 45 degrees to the test cylinder axis value, and in the second type of optical case S2, the positive axis of the cross cylinder is oriented to be rotated clockwise at 45 degrees to the test cylinder axis value.

[0294] In the first test, the cylindrical lens axis value was equal to the first test value. In the second test, the cylindrical lens axis value was equal to the second test value. In the current test, the cylindrical lens axis value was equal to the current test value.

[0295] exist Figure 5 In the experiment, the cylindrical lens axis value is represented by the letter A and marked as 53. Figure 5 In this experiment, the axis value of the cross-cylinder is equal to 17 degrees. The cross-cylinder is represented by a circle and marked as 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.

[0296] For this subject, in two optical conditions S1 and S2, the target appeared unclear when viewed through the cross-cylinder lens. During the subjective test, an eye care professional could ask, "In which condition was the target less blurry?"

[0297] Therefore, in a general manner, when the result of the experiment is the first answer 110, 221, 211, 231, the test value is increased, and when the result of the experiment is the second answer 120, 222, 212, 232, the test value is decreased.

[0298] Unless all previous trials result in the third answer, when the result is the third answer 213 or 223, the intermediate values ​​VI1 and VI5 are determined to be equal to the final test values ​​V2 and V2. This corresponds to the first stopping condition.

[0299] In the first subjective test, obtaining a third answer as the result of the first trial is considered a misunderstanding of the subjective test by the subject. Here, in this case, the second test value V2' is determined 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 was the first answer.

[0300] If the result of successive trials is the third answer 233, the test value is determined to be the sum of the previous test value and the previous increment of change, i.e., increase.

[0301] In the first subjective test, if the results of two successive trials are the first answer 110, 211, 231, followed by the second answer 212, or vice versa, the second answer 120, 222, followed by the first answer 221, then intermediate values ​​VI2 and VI4 are determined. In this case, intermediate values ​​VI2 and VI4 are equal to the current test values ​​VC and VC”, which are determined as the difference or sum between the previous test values ​​V2 and V2” and the previous increments I2 and I2”, respectively, where the previous increments I2 and I2” are equal to half of their preceding increment I1. This situation corresponds to the second stopping condition.

[0302] Finally, when the results of two successive trials are the third answer 130, 233, and then the second answer 232, the intermediate value VI3 can also be determined. 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 increment of change I2', where the previous increment of change I2' is equal to its preceding increment of change I1.

[0303] Preferably, the increment of change decreases between the first and last tests in the sequence. More preferably, it decreases from one test to the next. For example, the first increment of change V1 is equal to 15 degrees, and the second increment of change V2 is equal to 7 degrees. Subsequently, the current increment of change may become even lower than the baseline refractive value. The baseline refractive value is, for example, 5 degrees.

[0304] In this second sequence, in step f), the rounded value can be determined by rounding the intermediate value to the nearest or second nearest multiple of the given angle. Here, the intermediate value is preferably rounded to the lower of the nearest or second nearest multiples of the given angle. As mentioned above, this rounding method can depend on the individual characteristics of the subject.

[0305] It is also possible to determine the cylinder power suitable for providing refractive correction to improve the subject's vision. Figure 4 The decision tree shown in the diagram is also applicable to the determination of the cylindrical lens power. When determining the cylindrical lens power, the test value is the refractive value. For each test, the cross cylinder is oriented relative to the previously determined cylinder axis. Here, in the second type of optical case S2, the negative axis of the cross cylinder is aligned with the negative axis of the cylinder axis.

[0306] Here, the cross-cylinder has a test cylinder power value. In the first test, the test cylinder power value is equal to the first test value. In the second test, the test cylinder power value is equal to the second test value. In the current test, the test cylinder power value is equal to the current test value.

[0307] The first test value V1 is, for example, +0.25D or -0.25D.

[0308] In the first type of optical situation S1, when the subject sees the target more clearly, that is, has better visual performance, the test value (i.e., the cylindrical power value) increases. In the second type of optical situation S2, when the subject sees the target more clearly, that is, has better visual performance, the test value (i.e., the cylindrical power of the cross-cylinder) decreases.

[0309] The first increment of change may depend on the difference between the cylindrical power value obtained from the subject's previous optical equipment and the first test value: the greater the difference, the greater the increment of change.

[0310] Cylinder axis and power are one way to represent cylinder, but other representations exist, such as the J0 and J45 representations described in document EP2018061207. Figure 4 The decision tree representation in the text also applies to the J0 and J45 representations, for example, by setting J45 to a certain value and seeking J0, then setting J0 to the found value and seeking J45.

[0311] Third subjective test

[0312] Figure 6 The decision tree for the third subjective test is shown.

[0313] In this third subjective test, the optical characteristic determined is spherical power. The test involves placing two lenses with different spherical powers in front of the subject's eye. This subjective test is a monocular test. The rounding value is determined for one eye. This subjective test can be performed a second time for the other eye.

[0314] In the first type of optical situation S1, the subject views the target through a first experimental lens, which is displayed, for example, on a target screen of the optical device 2. The first experimental lens is characterized by a first experimental spherical power value.

[0315] In the second type of optical situation S2, the subject views the same target through a second test lens. This second test lens is characterized in that its second test spherical power value differs from that of the first test spherical power value.

[0316] During each trial, the subject was asked to view the target successively through a first trial lens and then through a second trial lens.

[0317] Here, the intermediate value VI (i.e., the rounding value) is sought to be the lower spherical power, in diopters, that gives the same sharp target in both optical conditions S1 and S2.

[0318] In step a), Figure 3The value is marked as 100. This first test value can be determined, for example, as the subject's current correction, or based on objective measurements.

[0319] During the subjective test, an eye care professional can ask, "In which situations do the letters appear clearer?"

[0320] For the first test, the spherical power value is equal to the first test value V1 minus the first change increment. For the second test, the spherical power value is equal to the first test value.

[0321] More generally, for each test, in the first type of optical condition, the first test spherical power value is equal to the test value minus the increment of change, and in the second type of optical condition, the second test spherical power value is equal to the test value.

[0322] For each test, the first test lens can be presented before or after the second test lens.

[0323] If the target seen by the subject using the first test lens is clearer than that seen using the second test lens, then the result of the test is the first answer. Optically, this means that the spherical power of the second test lens is too strong to provide adequate correction for the subject's eye. When the result of the first test is the first answer 110, in step d), Figure 6 The value is marked as 10, and the second test value V2' is determined to be the difference between the first test value V1 and the first change increment I1, which is equal to the first test spherical power value.

[0324] If the target seen by the subject using the second test lens is clearer than that seen using the first test lens, then the result of the first test is the second answer. Optically, this means that the spherical power of the second test lens is insufficient to provide adequate correction for the subject's eye. When the result of the first test is the second answer 120, in step d), Figure 3 The second test value, marked as 20, is determined as a weighted sum between the first test value V1 and the first increment of change I1. More precisely, the second test value V2 is determined as the weighted sum of the first test value V1 and the first increment of change I1, with a coefficient C less than 1. For example, the weighting coefficient C equals 0.625. More generally, the test value decreases when the result of the experiment is the first answer 110, 221, 211, 231, and increases when the result of the experiment is the second answer 120, 222, 212, 232.

[0325] If the subject sees the target equally clearly in both optical conditions S1 and S2, then the result of the first trial is the third answer 130.

[0326] However, as mentioned above, obtaining a third answer as the result of the first trial is considered a misunderstanding of the test by the subject. Here, in this case, in step d), marked 30, the second test value V2” is also determined 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 is the first answer.

[0327] If the result of successive trials is the third answer 233, the test value is determined to be the difference between the previous test value and the previous increment of change, i.e., a decrease.

[0328] Here, to facilitate the subject's understanding of the subjective test, that is, to help the subject see the difference between the first optical conditions S1 and S2, the first change increment I1 is very high, for example, greater than 0.35D.

[0329] When 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 sum between the second test value V2” and the second increment I2”. In this case, the second increment I2” is greater than the first increment V1. For example, the second increment I2” is 1.625 times the first increment I1.

[0330] In addition to this specific branch of the decision tree, the increment of change is preferably reduced between the first and last trials of the sequence.

[0331] When the result is the third answer 223, 212, 300, the second test lens provides appropriate correction to the subject's eye. Then, the intermediate values ​​VI1, VI3, VI5 are determined to be equal to the current test values ​​V2, V2', VC', which are equal to the second test spherical power values. This corresponds to the first stopping condition. The only exception is where the result of the first test is the third answer 130, and the result of the second test is also a branch of the third answer 232.

[0332] In the first and second sequences, when the results of two successive trials are the first answer 110, 211, 231, followed by the second answer 212, or vice versa, the second answer 120, 222, 232, 302, followed by the first answer 221, 301, the intermediate values ​​VI2 and VI4 are determined, for example. In this case, the intermediate values ​​VI2 and VI4 are equal to the current test values ​​VC and VC.

[0333] Preferably, the increment of change decreases between the first and last tests in the sequence. Preferably, it decreases from one test to the next. For example, the first increment of change V1 can be greater than 1D, and the second increment of change V2 can be less than 1D. Subsequently, the current increment of change can become even lower than the baseline refractive value. The baseline refractive 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 baseline refractive value. As mentioned above, this rounding method can depend on the individual characteristics of the subject.

[0334] Fourth Subjective Test

[0335] Figure 7 The decision tree for the fourth subjective test sequence is shown.

[0336] In this first subjective test, the optical characteristic of the ophthalmic lens is spherical power.

[0337] Each test involves displaying two targets of different sizes and providing the subject with a test lens with the test spherical power value.

[0338] This subjective test is often referred to as the "fogging / defogging test." This subjective test is a monocular test. The rounding value is determined for one eye. The sequence can be performed a second time for the other eye.

[0339] In the first type of optical situation S1, the subject views the first target through a test lens. The size of the first target seen by the subject at the viewing distance corresponds to a first acuity value.

[0340] In optical scenario S2, the subject views a second target smaller than the first target through the same experimental lens. The size of the second target perceived by the subject at their observation distance corresponds to a second acuity value.

[0341] During each trial, the subject was asked to view two targets through a test lens with a test spherical power equal to the test value and to identify which target's symbol appeared clearer.

[0342] These two goals are, for example, a few lines of letters on a vision chart. For instance, for the first trial, the first goal is 4 / 10 of the lines, and the second goal is 8 / 10 of the lines. The magnitudes of the first and second goals can vary from one trial to the next.

[0343] Here, in the optional initial part of the sequence (in Figure 7 During the period (not indicated in the text), the size of the first and second targets can be increased until the subject can clearly read at least the first target.

[0344] Here, the result of the experiment is the first answer when the subject cannot clearly read the letters of either the first or second objective. The result is the second answer when the subject can clearly read the letters of both the first and second objectives. The result is the third answer when the subject can clearly read the letters of the first objective but cannot clearly read the letters of the second objective.

[0345] Here, in the first step a), the first test value can be determined, for example, as the subject's current correction, or based on an objective or subjective measurement, plus a determined refractive value, for example, greater than 1D. This increase in the determined refractive value corresponds to the initial fogging step. In effect, in the first part of this sequence, fogging can relax the subject's accommodation.

[0346] Then, the test value is increased as long as the subject can clearly read the second objective, i.e., as long as the result of the successive trials is the second answer 130. For example... Figure 7 As shown, when the result of the first test is the second answer 120, in step c) Figure 7 Marked as 20, the second test value V2 is calculated as the sum between the first test value V1 and the first change increment I1.

[0347] This increase in the test value corresponds to the first part of the sequence: the fogging step. Here, during the fogging step, the increment of change preferably remains constant.

[0348] Then, at the point where the subject can clearly read only the first objective—that is, when the result of the trial is the third answer—the test value is reduced. For example, in Figure 7 In step g), when the result of the second test is the third answer 223, the current test value VC is calculated as the difference between the second test value V2 and the second change increment I2, marked as 21.

[0349] This first reduction in the test value marks the beginning of the second part of the sequence: the defogging step. Here, at the start of the second part of the sequence, the second target is set to a predetermined high sensitivity, for example, a row corresponding to a sensitivity of 10 / 10.

[0350] Then, the test value is reduced as long as the subject can clearly read only the first objective, i.e., when the result of the successive trials is the third answer 300.

[0351] Here, during the defogging step, the increment of change preferably decreases from one test to the next.

[0352] Then, at the moment when the subject can clearly read the second objective, i.e., when the result of the trial is the second answer 301, the median value VI is determined to be equal to the current test value VC. Here, when the second answer is obtained using the second objective corresponding to the predetermined desired acuity, the median value is determined to be equal to the current test value.

[0353] In step f), the rounding value is determined by rounding the intermediate value to the nearest or second-nearest multiple of the basic refractive value. The basic refractive value is, for example, 0.25D. As mentioned above, this rounding method can depend on the individual characteristics of the subject.

[0354] Fifth Subjective Test

[0355] Figure 8 The decision tree for the fifth subjective test is shown.

[0356] In this fifth subjective test, the optical characteristic determined is the difference in spherical power between the right and left eyes. The test involves placing two lenses with different spherical powers in front of each of the subject's eyes.

[0357] This subjective test is a binocular test. The rounding value is determined for both eyes. In the first type of optical situation S1, the subject views the target, for example, displayed on the target screen of the optical device 2, through the left test lens with his left eye. The left test lens is characterized by its left test spherical power value.

[0358] In the second type of optical situation S2, the subject views the same target with his right eye through the right test lens. The right test lens is characterized by a right test spherical power value that differs from that of the left test spherical lens.

[0359] During each trial, the subject was instructed to view the target sequentially through the left test lens with their left eye and then through the right test lens with their right eye. An obstruction could be placed in front of one eye to allow the subject to view the target using only the other eye.

[0360] Here, the intermediate value VI (i.e., the rounding value) is sought as the difference between the left and right test spherical lens power values ​​when the target is equally clear in both eyes.

[0361] In step a), Figure 3 Marked as 100, the first test value can be determined, for example, based on the subject’s current correction or based on two objective monocular measurements (one for the right eye and one for the second eye) as the difference in spherical power between the right and left eyes.

[0362] During the subjective test, an eye care professional can ask, "In which situations do the letters appear clearer?"

[0363] For the first test, the spherical power value of the left test is equal to the spherical power previously determined in the left monocular test plus the determined refractive value, which is 0.5D in this case, and the spherical power value of the right test is equal to the spherical power previously determined in the right monocular test plus the determined refractive value.

[0364] If the target seen by the subject using the left test lens (i.e., with the left eye) is clearer than the target seen using the right test lens, then the result of the test is the first answer. When the result of the first test is the first answer 110, in step d), Figure 8 The value is marked as 10, and the second test value V2 is determined to be the sum of the first test value V1 and the first change increment I1. This means that for the second test, the difference between the spherical power values ​​of the left and right tests increases.

[0365] If the target seen by the subject using the right test lens (i.e., with the right eye) is clearer than the target seen using the left test lens, then the result of the test is the second answer. When the result of the first test is the second answer 120, in step d), Figure 8 The value is marked as 20, and the second test value V2' is determined to be the difference between the first test value V1 and the first increment of change I1. This means that for the second test, the difference between the spherical power values ​​of the left and right tests decreases.

[0366] Preferably, the left and right test spherical power values ​​are modified by the same amount in a symmetrical manner. For example, when the difference between the left and right test spherical power values ​​increases by 0.3D, the higher of the two increases by 0.15D, and the lower of the two decreases by 0.15D.

[0367] Here, neither the left nor the right test spherical power value can be lower than a threshold. This threshold is, for example, -0.05D. For instance, when the difference between the left and right test spherical power values ​​must be increased by 0.3D, and when the lower value is equal to 0D, the lower value is reduced to -0.05D and the higher value is increased by 0.25D.

[0368] More generally, when the result of the experiment is the first answer 110, 221, 211, 231, the test value is increased, and when the result of the experiment is the second answer 120, 222, 212, 232, the test value is decreased.

[0369] If the subject sees the target equally clearly in both optical conditions S1 and S2, then the result of the first trial is the third answer 130.

[0370] However, as mentioned above, obtaining a third answer as the result of the first trial is considered a misunderstanding of the test by the subject. Here, in this case, in step d), marked 30, the second test value V2” is also determined 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 is the second answer.

[0371] If the result of successive trials is the third answer 233, the test value is determined to be the difference between the previous test value and the previous increment of change, i.e., a decrease.

[0372] Preferably, the increment of change decreases between the first and last trials of the sequence.

[0373] Unless all previous trials result in the third answer, when 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.

[0374] In the second subjective test, when the results of two successive trials are the first answer 110, 211, 231, followed by the second answer 212, or vice versa, the second answer 120, 222, followed by the first answer 221, intermediate values ​​VI2 and VI4 are determined, for example. In this case, intermediate values ​​VI2 and VI4 are equal to the current test values ​​VC and VC', which are determined as the difference or sum between the previous test values ​​V2 and V2' and the previous increments I2 and I2', respectively, where the previous increments I2 and I2' are equal to half of their preceding increment I1. This situation corresponds to the second stopping condition.

[0375] Finally, when the results of two successive trials are the third answer 130, 233, and then the first answer 231, the intermediate value VI5 can also be determined. In this case, the intermediate value VI5 is equal to the current test value VC”, which is determined as the sum between the previous test value V2” and the previous change increment I2”, where the previous change increment I2” is equal to half of its previous change increment I1.

[0376] Preferably, the increment of change decreases between the first and last trials in the sequence. More preferably, it decreases from one trial to the next. For example, the first increment of change V1 can be greater than 1D, and the second increment of change V2 can be less than 1D. Subsequently, the current increment of change can become even lower than the baseline refractive value. The baseline refractive value is, for example, 0.25D.

[0377] In this fifth sequence, in step f), the rounding value is determined by rounding the intermediate value to the nearest or second nearest multiple of the basic refractive value. As mentioned above, this rounding method can depend on the individual characteristics of the subject.

[0378] The sequences associated with different subjective tests can be executed one after another in a well-known manner. For example, it is preferable to execute the sequence of the fifth subjective test after executing the sequence of the fourth subjective test twice (once for the left eye and once for the right eye).

[0379] In the example of the subjective test above, the rounding value is determined at the end of the test sequence for each subjective test.

[0380] When performing a series of subjective tests, that is, performing several different subjective tests in succession, the rounding value for determining the sought optical feature can be performed at the end of the test sequence of each subjective test or at the end of all subjective tests.

[0381] In this last case, the accurate, unrounded value of the optical feature determined by the previously performed subjective test can be used for subsequent subjective tests. In practice, the accurate, unrounded value of the optical feature determined by the previously performed subjective test corresponds to the aforementioned intermediate value.

[0382] In particular, when determining the cylindrical axis power and cylindrical power of a cylindrical ophthalmic lens, it is preferable to consider the median value representing the cylindrical axis when performing subjective testing to determine the cylindrical power.

[0383] The rounded value of the two intermediate values ​​determined by the subjective tests used to determine the cylinder axis and cylinder power can be rounded after both subjective tests have been performed. In this way, the determination of the intermediate value representing the cylinder power is more accurate because it takes into account the intermediate value of the cylinder axis rather than its rounded value.

[0384] In one variant, when performing a subjective test series, only the final intermediate value determined in the last sequence can be rounded. Previous series can be used only to determine the exact first test value.

[0385] For example, when only the spherical power difference between the right and left eyes is sought, the fifth subjective test is preferably performed in step a) using the intermediate value determined in the first or fourth subjective test for the left eye and the intermediate value determined in the first or fifth subjective test for the left eye.

Claims

1. A system for determining rounding values ​​of optical characteristics suitable for providing refractive correction for improving the vision of a subject, the system comprising an optical device for performing a subjective test and a computer, the subjective test comprising evaluating the visual performance of the subject placed in two different optical conditions, the computer comprising one or more processors programmed to perform the following steps: a) Determine the first test value of the optical feature and the first increment of change of the optical feature. b) Using the optical device to perform a first trial of the subjective test, wherein two distinct first optical conditions are determined based at least on the first test value. c) Determine a second test value for the optical feature based on the first test value, the first change increment, and the result of the first test performed in step b). d) Using the optical device to perform a second test of the subjective test, wherein two distinct second optical conditions are determined based at least on the second test value. e) Determine an intermediate value for the optical feature based on the results of the first test performed in step b) and the results of the second test performed in step d). f) Determine the rounding value of the optical feature by rounding the intermediate value to a reference value, wherein the rounding modifies the refractive correction of the ophthalmic lens to be less than a predetermined basic refractive value.

2. The system according to claim 1, wherein, When the intermediate value of the optical feature is different from a multiple of the predetermined basic refractive value, the processor is programmed to round the intermediate value to the nearest or second nearest multiple of the predetermined basic refractive value in step f).

3. The system according to any one of claims 1 and 2, wherein, The processor is further programmed to determine the first increment of change in step a) based at least on the subject’s first human characteristic.

4. The system according to claim 3, wherein, The first personal characteristics include at least one of the following data relating to the subject: age, type of refractive error, visual acuity, requests regarding their visual performance or current vision correction devices, historical data including the subject's current correction, medical condition, visual needs or activities, chosen eyeglass frames, chosen ophthalmic lenses, and optical characteristics of the subject's eyes.

5. The system according to claim 1, wherein, The processor is further programmed to round the intermediate value in step f) according to a rounding method that depends on at least a second person characteristic of the subject or on the type of subjective test performed.

6. The system according to claim 5, wherein, The second personal characteristic includes at least one of the following data relating to the subject: age, type of refractive error, visual acuity, requests regarding their visual performance or current visual correction devices, historical data including the subject's current correction, condition, visual needs or activities, chosen eyeglass frames, chosen ophthalmic lenses, and optical characteristics of the subject's eyes.

7. The system according to claim 1, wherein, The processor is further programmed to determine the two different first optical conditions based on the first change increment in step b).

8. The system according to claim 1, wherein, During the subjective test, the subject is placed in the two different optical conditions by achieving at least one of the following: - Displays targets placed in red and green environments. - Add cross-cylinder lenses at two different positions in front of the subject's eyes. - Place two lenses with different spherical powers in front of the subject's eyes. - Display two targets of different sizes. - Place different lenses in front of the subject's right and left eyes.

9. The system according to claim 1, wherein, The optical feature includes at least one of the following: -The spherical power of the ophthalmic lens - The cylindrical power of the ophthalmic lens - The cylinder axis of the ophthalmic lens. - The difference in spherical power between two ophthalmic lenses placed in front of the right and left eyes.

10. The system according to claim 1, wherein, The processor is further programmed to perform the following steps: g) Determine the current test value and the current increment of change based on the results of previous experiments and the previous test values ​​corresponding to the previous experiments. h) The current trial that performs the subjective test includes evaluating the visual performance of the subject placed in two different current optical conditions determined at least based on the current test values. i) Modify the current test value based on the results of the current experiment and based on the current increment of change, and modify the current increment of change based on the results of the current experiment. as well as, Optionally, repeat steps h) and i). Furthermore, the processor is programmed to determine the intermediate value based on the current test value in step e).

11. The system according to claim 10, wherein, The processor is further programmed to determine and / or modify the current change increment in step g) based on the degree of certainty of the results of the previous experiment performed.

12. The system according to claim 10, wherein, The current change increment is less than the predetermined basic refractive value.

13. The system according to claim 10, wherein, The processor is further programmed to modify it in step i) by decreasing the value of the current change increment.

14. The system according to claim 10, wherein, The processor is further programmed to perform step e) in the following cases: -The current test value increases and decreases or decreases and increases successively in the last two successive trials, or - The second test value is higher than the first test value, and the current test value determined in step g) is less than the second test value, or - The second test value is less than the first test value, and the current test value determined in step g) is higher than the second test value.

15. The system according to claim 1, wherein, The processor is further programmed to perform step e) in the following cases: - During the final trial, the subjects evaluated the two different final optical conditions to provide equivalent visual performance, and - During the previous trial performed prior to the final trial, the subject evaluated one of the two different previous optical conditions to provide better visual quality than the other previous optical condition.

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