DEVICE FOR DETERMINING THE SHIFT OF THE REFRACTION VALUE OF THE EYE

Abstract

1. A device for determining a shift in a refractive value of an eye illuminated by a light beam emitted by a light source and transmitted through an optical filter, the device comprising: a memory (11) storing a value of an initial spectral characteristic of the light source (100), a value of an optical characteristic of the optical filter (200), and a refractive shift model (300) linking a magnitude associated with the shift to the spectral characteristic of the light beam; and a processor (12) programmed to determine (400) a value of the spectral characteristic of the light beam based on the value of the initial spectral characteristic of the light source and the value of the optical characteristic of the optical filter, and to determine (500) the shift based on the refractive shift model and the value of the spectral characteristic of the light beam.

Description

[Technical field]

[0001] The present disclosure relates to devices and methods for determining a shift in the refractive value of a subject's eye caused by an optical filter. [Background technology]

[0002] When a beam of light is transmitted to a subject's eye, different wavelengths of visible light are focused at different distances onto the retina where the image seen by the subject is formed.

[0003] Light of longer wavelengths, corresponding for example to red light, is focused to a point located slightly behind the retina, while light of shorter wavelengths, for example blue light, is focused to a point slightly in front of the retina. The amplitude of this defocus, i.e. the distance between the focal point and the retina, depends on the wavelength and is called "axial chromatic aberration" (LCA).

[0004] This phenomenon means that images of different colours, i.e. different wavelengths, or components of an image corresponding to different colours or different wavelengths, may have different clarity when viewed by a subject's eye.

[0005] On the other hand, the use of tinted lenses is becoming more and more common and increasingly specialized and complex. Tinted lenses are multi-colored optical filters.

[0006] Optical filters used in spectacles aim to protect the visual system and improve comfort and visual performance in different light conditions. For aesthetic purposes, colorful filters have also been proposed. They can be associated with lenses with or without vision correction.

[0007] Because light rays having different wavelengths have different focal positions within the eye, the use of optical filters that change the wavelength distribution of light transmitted to a subject's eye can alter the optimal focal point on the retina.

[0008] Applicant's experimental results show that a high ratio of long to short wavelengths in the light reaching the eye causes a significant hyperopic shift. A high ratio of short to long wavelengths results in a significant myopic shift. The amplitude of the myopic shift is greater than the amplitude of the hyperopic shift.

[0009] The refractive error shift caused by the presence of optical filters in front of a person's eyes can induce fatigue and reduce visual performance such as visual acuity, contrast sensitivity, and reading speed.

[0010] In other words, adding an optical filter in front of the eye may cause an ametropic shift in the subject's vision, which may reduce the comfort and quality of the subject's vision.

[0011] Specifically, when the refractive characteristics of the eye are determined to estimate the vision correction function of a corrective ophthalmic lens to improve a subject's vision, the refractive characteristics of the eye are determined to focus light having wavelengths between green and red light onto the retina so that the defocus associated with red light is equivalent to the defocus associated with green light.

[0012] The refractive characteristics of the eye, and therefore the vision correction function of corrective ophthalmic lenses, are determined using ambient natural light or artificial white light for clear lenses that have negligible absorption of visible light.

[0013] The addition of an optical filter may then alter the corrective effect of the thus determined corrective ophthalmic lens on the subject's eye.

[0014] To solve this problem, the actual spectral transmission of the selected lens or optical filter can be used to create a tailored prescription, taking into account the measurement of the wearer's refractive error, allowing the light to be perfectly focused on the retina, and the wearer will have clearer vision and less effort in accommodating.

[0015] Yet, obtaining such precise measurements requires precise methodologies and precise equipment, and these measurements are time consuming and tedious. Summary of the Invention [Means for solving the problem]

[0016] It is therefore one object of the present invention to provide a device for quickly and easily determining the shift in the refractive value of the eye introduced by an optical filter.

[0017] The above object is achieved according to the invention by providing a device for determining a shift in the refractive value of an eye of a subject illuminated by a light beam emitted by a light source, the shift being caused by an optical filter through which the light beam passes when transmitted to the eye of the subject, the device comprising one or more memories and one or more processors, - One or more memories one or more values ​​of one or more initial spectral characteristics of the illuminant; one or more values ​​of one or more optical characteristics of the optical filter; a refractive shift model that links a magnitude associated with the shift to one or more spectral characteristics of the light transmitted to the subject's eye; Remember, - One or more processors determining one or more values ​​of one or more spectral characteristics of the light beam transmitted through the optical filter to the subject's eye based on one or more values ​​of the one or more initial spectral characteristics of the light source and one or more values ​​of the one or more optical characteristics of the optical filter; determining a shift in refraction of the subject's eye based on the refraction shift model and the value of the spectral characteristic of the light transmitted through the optical filter to the subject's eye; is programmed to carry out the

[0018] Thanks to the device according to the present invention, the shift in the refraction of the subject's eye caused by the optical filter can be determined with minimal measurements based on the optical characteristics of the optical filter, which may be predetermined, known by any kind of means, or measured.

[0019] By virtue of determining the refractive error shift with the device according to the invention, - adapting the prescription based on the optical characteristics of the optical filter to improve the quality of vision or the visual comfort of the subject, for example by compensating the refractive shift caused by the filter with the refractive power of the corrective lens; - Using refractive shifts induced by optical filters to improve a subject's visual performance in certain conditions. For example, it is possible to consider using a myopic shift in near vision to take on the role of the spherical power of the corrective lens and to partially replace it.

[0020] The spherical power of a corrective ophthalmic lens can be replaced with the color of the lens for a particular activity of the subject.

[0021] The device according to the invention provides a tool for predicting the defocus associated with an optical filter with any spectral transmittance, without any actual measurements on a subject.

[0022] Thanks to the adapted prescription of the corrective ophthalmic lens taking into account the optical filters, it is possible to take into account the corresponding refractive error shift by taking into account the defocus and thus provide better visual performance and reduce fatigue.

[0023] Other advantageous features of the device according to the invention are: - the one or more values ​​of the one or more initial spectral characteristics of the light source include an initial spectrum of light emitted by the light source, and the one or more values ​​of the one or more optical characteristics of the optical filter include values ​​quantifying the transmission of light through the optical filter; - the one or more processors are programmed to determine a spectrum of the light beam transmitted through the optical filter to the subject's eye to determine one or more values ​​of one or more spectral features of the light beam transmitted through the optical filter to the subject's eye; - the one or more memories are further programmed to store data relating to one or more optical characteristics of the subject's eye, and the one or more processors are programmed to take these data into account to determine one or more values ​​of one or more spectral characteristics of the light beam transmitted through the optical filter to the subject's eye; - the data related to one or more optical characteristics of the eye includes data related to the transmission of light through the anterior part of the eye to the retina of the eye: - the one or more memories store weighting coefficients representative of light sensitivity of a retina of the subject's eye at one or more wavelengths, and the one or more processors are programmed to determine, taking into account the weighting coefficients, one or more values ​​of one or more spectral features of the light beam transmitted through the optical filter to the subject's eye; - the one or more spectral characteristics of the light beam transmitted through the optical filter to the subject's eye include wavelength statistics representative of a wavelength distribution of the spectrum of the light beam transmitted through the optical filter to the subject's eye; - wavelength statistics describing the wavelength distribution of a spectrum include the wavelength centroid of the spectrum; - the one or more memories store data relating to axial chromatic aberration of the eye as a function of a wavelength of light transmitted to the eye, and the refractive shift model includes a relationship between a refractive shift of the subject's eye and the axial chromatic aberration of the subject's eye at wavelength statistics; - the one or more values ​​of the one or more initial spectral characteristics of the light source include an initial spectrum of light emitted by the light source, and the one or more processors are programmed to determine, based on the initial spectrum of light emitted by the light source, reference wavelength statistics representative of a wavelength distribution of a reference spectrum of a reference light beam emitted by the light source in the absence of an optical filter and transmitted to the subject's eye, and the refractive shift model accounts for axial chromatic aberration of the subject's eye at the reference wavelength statistics; - the refractive shift model provides a shift value equal to the difference between the axial chromatic aberration of the eye at the wavelength statistics and the axial chromatic aberration of the eye at the reference wavelength statistics; - the one or more spectral characteristics of the light beam transmitted through the optical filter to the subject's eye include a spectrum of the light beam transmitted through the optical filter to the eye over a predetermined global wavelength range; - the one or more memories store fundamental shift values ​​associated with the predetermined fundamental wavelength ranges, and the refractive shift model includes a relationship between the refractive shift and a sum of the fundamental shift values ​​for all of the corresponding fundamental wavelength ranges included in the predetermined global wavelength range, weighted by an integral of the spectrum of light transmitted to the eye through the filter within the corresponding fundamental wavelength range; - the refractive shift model provides a shift value equal to the ratio between the sum and the integral of the spectrum of light transmitted to the eye through the filter within a given global wavelength range; - the base shift value is determined by minimizing the difference between each measurement of the refractive shift and a calculated value of the refractive shift given a database comprising a plurality of test spectra of light transmitted to the eye and corresponding measurements of the refractive shift in the eye, the calculated value of the refractive shift being determined using the relationship and the test spectrum of light transmitted to the eye to which the measurement of the refractive shift corresponds.

[0024] The present invention also relates to adaptive eyewear for a subject, the adaptive eyewear comprising: an ophthalmic lens having a variable refractive power and / or a variable filter, the amount of variation of which is controlled by a controller; - Devices as mentioned above Equipped with The device is in communication with a controller, which is programmed to determine a power variation and / or a shade variation of the ophthalmic lens taking into account a shift in the refraction of the subject's eye determined by the device.

[0025] The invention also relates to a method for determining a shift in the refractive value of an eye of a subject illuminated by a light beam emitted by a light source, the shift being caused by an optical filter through which the light beam passes when transmitted to the eye of the subject, the device comprising one or more memories and one or more processors, the method comprising: - determining one or more values ​​of one or more initial spectral characteristics of the light source; - determining one or more values ​​of one or more optical characteristics of the optical filter; - providing a refractive shift model that links a magnitude associated with the shift to one or more spectral characteristics of light transmitted to the subject's eye; - determining one or more values ​​of one or more spectral characteristics of a light beam transmitted through the optical filter to the subject's eye based on one or more values ​​of one or more initial spectral characteristics of the light source and one or more values ​​of one or more optical characteristics of the optical filter; - determining a shift in refraction of the subject's eye based on the refraction shift model and on values ​​of the spectral characteristics of the light transmitted through the optical filter to the subject's eye; Includes.

[0026] The following description, referring to the accompanying drawings, will make clear what constitutes the present invention and how it can be achieved. The present invention is not limited to the embodiments shown in the drawings. Thus, when features recited in the claims are followed by reference signs, it should be understood that such signs are included only for the purpose of enhancing the comprehension of the claims, and do not limit the scope of the claims. [Brief description of the drawings]

[0027] [Figure 1] 1 is a schematic diagram of a cross section of an eye showing an example of longitudinal chromatic aberration. [Diagram 2] 1 shows a block diagram illustrating the main parts of a device according to the invention and the steps of the method performed by this device; [Diagram 3]1 is an exemplary graph plotting radiance versus wavelength for a commercially available light source. [Figure 4] 1 is a graphical representation of the total transmittance of a transparent ophthalmic medium of human eyes of different ages plotted against wavelength. [Diagram 5] 1 is a graphical representation of the axial chromatic aberration of the eye as a function of wavelength. [Figure 6] 1 is a graphical representation of the response curves of the three different types of cones in the human eye as a function of wavelength; the cone response is the relative spectral sensitivity of L, M, and S, which is related to the absorption probability of a photon reaching the retina after filtering by the lens and macular pigment, or the front part of the eye, also called the anterior ocular media (which has no specific units). [Figure 7] 1 is a graphical representation of the cone response weighting factor as a function of wavelength. [Figure 8] 1 is a graphical representation of the transmission spectra of different filters as a function of wavelength. [Figure 9] 1 is a graphical representation of the refractive error shift measured and calculated by a first embodiment of a device of the present invention for different filters. [Figure 10] 4 is a graphical representation of refractive error shift calculated by a device of a first embodiment of the present invention for different filters and different light sources. [Figure 11] 4 is a graphical representation of wavelength ranges considered for an example of a light source spectrum in a second embodiment of the device of the present invention. [Figure 12] 13 is a graphical representation of the refractive error shift measured and calculated by a second embodiment of a device of the present invention for different filters. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] As mentioned in the introduction and shown in FIG. 1, due to the axial chromatic aberration of the human eye E, light rays having different wavelengths will exhibit different focal positions BF, RF in the eye E.

[0029] FIG. 1 shows the path of a light ray LB bounded by two light rays L1, L2 entering the eye E. The eyepiece EL focuses a portion of the light ray LB having a shorter wavelength, corresponding to the color blue, in front of the retina at a point BF corresponding to the light rays L'1, L'2, while a portion of the light ray LB having a longer wavelength, corresponding to the color red, behind the retina of the eye at a point RF corresponding to the light rays L''1, L''2. The defocus of the red light ray is the distance LCA1 between the retina and the point RF. The defocus of the blue light ray is the distance LCA2 between the retina and the point BF.

[0030] The situation considered below is shown diagrammatically in Fig. 1. An eye E of a subject receives a light beam LB emitted by a light source S having given spectral characteristics. An optical filter OF, shown in dashed lines in Fig. 1, is placed on the path of the light beam LB between the light source S and the eye E.

[0031] Such optical filters OF can comprise colored optical elements such as colored substrates, or can comprise colored optical films associated with a transparent or also colored base substrate. The color tone of the film / substrate can be obtained from a pigment composition that includes at least one absorbing dye or a combination of different absorbing dyes to define a colored film / substrate, a film / substrate for sunglasses, a film / substrate for anti-UV or blue light cut, a filtering film / substrate that filters a specific wavelength range of a light source, or a polar film / substrate.

[0032] Generally speaking, tinted films / substrates are defined to reduce the visible light transmission coefficient Tv of illuminant D65 taking into account the specific category of sunglasses they correspond to: - Optical elements with a visible light transmission Tv of 80% or more, also known as "category 0" optical elements; - optics with a visible light transmission Tv between 46% and 79%, also known as "category 1" optics; - Optics with a visible light transmission Tv between 18% and 45%, also known as "category 2" optics.

[0033] The optical filters described above may include at least one activatable absorbing dye. Various types of activatable dyes are well known to those skilled in the art. As a result, the optical filters may be switchable between different configurations, i.e. between an active state and an inactive state, by an external source, such as an external light source. Activatable dyes include, for example, photochromic or electrochromic type dyes.

[0034] The use of an optical filter OF changes the wavelength distribution of the light beam LB transmitted to the subject's eye E, and the overall clarity of the image seen by the subject can then be altered.

[0035] The present invention provides a device 10 and methodology for predicting the defocus caused by an optical filter OF for an eye E of a subject, without the need to perform any measurements involving the subject.

[0036] More precisely, this device is a device 10 for determining the shift in the refractive value of an eye E of a subject illuminated by a light beam LB emitted by a light source S, this shift being caused by an optical filter OF through which the light beam LB passes when transmitted to the eye E of the subject. This device 10 is represented diagrammatically in figure 2. This device 10 comprises one or more memories 11 and one or more processors 12, - One or more memories 11 one or more values ​​100 of one or more initial spectral characteristics of the illuminant S; one or more values ​​200 of one or more optical characteristics of the optical filter OF; a refractive shift model 300 that links a magnitude associated with the shift to one or more spectral characteristics of the light beam LB transmitted to the subject's eye E; Remember, - one or more processors 12 performing the steps of: a) determining 400 one or more values ​​of one or more spectral characteristics of a light beam LB transmitted through an optical filter OF to an eye E of a subject based on one or more values ​​100 of one or more initial spectral characteristics of a light source S and on one or more values ​​200 of one or more optical characteristics of an optical filter OF; b) determining 500 the shift in refraction of the subject's eye (E) based on the refraction shift model 300 and the values ​​of the spectral characteristics of the light beam LB transmitted to the subject's eye (E) through the optical filter OF; is programmed to carry out the

[0037] The one or more values ​​100 of the one or more initial spectral characteristics of the light source S may include, for example, an initial spectrum of the light emitted by the light source S.

[0038] The one or more values ​​200 of the one or more optical characteristics of the optical filter OF may include, for example, values ​​that quantify the transmission of light through the optical filter OF.

[0039] An example of an initial spectrum of a light source is shown in Figure 3, which shows a graph of the radiance of a commercially available screen as a function of wavelength. Alternatively, the initial spectrum of a light source may include a graph of intensity, luminous intensity, brightness, or any related magnitude, as a function of wavelength. The initial spectrum of a light source may also be stored as a standard illuminant, a table of brightness or luminous intensity values, values ​​of radiance, intensity, or a related magnitude, as a function of wavelength.

[0040] This initial spectrum can be measured thanks to a spectrometer or can be derived from information embedded in the source.

[0041] The one or more optical characteristics of the optical filter OF may include a graph or table of values ​​of transmission or transmittance of light through the optical filter OF.

[0042] The optical characteristics of the optical filter OF may also include an optical geometric description of the films and / or substrates that make up the optical filter OF, including the shapes of the diopters, their relative positioning, and the refractive indices of the materials.

[0043] The optical characteristics of the optical filter OF may also contain information about the axial chromatic aberration produced by the filter itself.

[0044] The transmittance value of a filter at a given wavelength is equal to the luminance of the light transmitted by the filter divided by the luminance of the incident light at that wavelength. The transmittance value of a filter at a given wavelength may also be defined as the radiance of the light transmitted by the filter divided by the radiance of the incident light at that wavelength.

[0045] The transmission value of a filter at a given wavelength is equal to the intensity of the light transmitted by the filter divided by the intensity of the incident light at that wavelength.

[0046] The information about the axial chromatic aberration can be provided as material dispersion, or the value of the axial chromatic aberration, or the coefficient of the axial chromatic aberration.

[0047] One or more values ​​of one or more spectral characteristics of the light beam LB transmitted through the optical filter OF to the subject's eye E may include the spectrum of the light beam transmitted through the filter determined by multiplying the initial spectrum of the light source by a value that quantifies the transmission rate of light through the optical filter OF at each wavelength.

[0048] The spectral characteristics of the light beam transmitted to the eye may also include the amount of axial chromatic aberration in the light beam, for example within the range of wavelengths contained in the light beam.

[0049] In this case, the one or more processors 12 are programmed in step a) to determine the spectrum of the light beam LB transmitted to the subject's eye E through the optical filter OF.

[0050] For example, the initial spectrum of the light source includes intensity, luminance, or radiance for a set of wavelengths, and the values ​​of one or more optical characteristics of the optical filter OF include filter transmission or transmittance values ​​for the set of wavelengths. The values ​​of the spectral characteristics of the light beam LB transmitted to the eye include the intensity of the light source multiplied by the transmission of the filter for each set of wavelengths, or the luminance or radiance of the light source multiplied by the transmittance of the filter for each set of wavelengths.

[0051] Of course, other factors or parameters may be taken into consideration.

[0052] Optionally, the one or more memories 11 may further store data relating to one or more optical characteristics of the subject's eye E, and the one or more processors 12 are programmed to take into account this data to determine one or more values ​​of one or more spectral characteristics of the light beam LB transmitted to the subject's eye E through the optical filter OF.

[0053] The data related to one or more optical characteristics of the eye E may for example include data related to the transmission of light through the front part of the eye to the retina of the eye E. The front part of the eye E corresponds to the part of the eye E located in front of the retina. This front part of the eye E actually presents a certain transmission function and acts as an additional optical filter placed in front of the retina, where the cells that detect the light rays are located.

[0054] In this case, the one or more processors 12 are programmed in step a) to determine the spectrum of the light beam LB transmitted through the optical filter OF to the subject's eye E, for example by multiplying the intensity or brightness value of the light source by the transmission or transmittance of the filter for each set of wavelengths and by the transmission or transmittance of the front of the eye for each wavelength.

[0055] The transmission or transmittance of the optical filter OF and / or of the front of the eye E may be measured in a pre-calibration step or may be retrieved from a database.

[0056] The transmittance or transmittance of the anterior part of the eye E may include a specific value customized for the subject, either by measuring the subject or by taking into account the subject's personal characteristics, such as the subject's age or the spectral transmittance of the anterior part of the eye or the anterior ocular media.

[0057] Examples of data relating to wavelength-dependent total transmittance of the anterior part of the eye for subjects of different ages are shown in Figure 4. In the figure, the data is presented as a graph of the transmittance of the anterior part of the eye versus wavelength.

[0058] Alternatively, the transmittance or transmittance of the anterior part of the eye E may comprise an average transmittance or transmittance determined for a reference population of subjects or for a given subject.

[0059] In a more sophisticated embodiment, the one or more memories 11 store weighting coefficients representative of the light sensitivity of the retina of the subject's eye E at one or more wavelengths. The one or more processors 12 are then programmed to determine, taking into account these weighting coefficients, one or more values ​​of one or more spectral features of the light beam LB transmitted through the optical filter OF to the subject's eye E.

[0060] Such weighting coefficients may be derived, for example, on the basis of response curves Response_S, Response_M, Response_L of retinal cells that detect light rays, based on three types of cones, denoted below as S, M and L. Data relating to the response curves of the eye's cones are available from the CIE (Commission Internationale de l'Eclairage) and are represented in FIG. 6, which shows the wavelength dependence of the light sensitivity of each type of cone. Light sensitivity may be defined as a function representing the number of photons absorbed by the retina for each wavelength.

[0061] The weighting factor Wf considered can be determined as a weighted average of the responses of the three types of cones to each wavelength. The weighting factor is calculated, for example, as Wf(λ)=ws×Response_S(λ)+wl×Response_L(λ)+wm×Response_M(λ), where ws, wm, and wl are three scalars that determine the weight of each cone response. An example showing how these scalars are determined is presented later.

[0062] A refractive shift model 300, linking the magnitude associated with the shift to one or more spectral characteristics of the light beam LB transmitted to the subject's eye E, may be determined using a machine learning algorithm trained on a reference database.

[0063] A preliminary step of the method according to the invention may therefore comprise building a reference database comprising measured refractive error values ​​of reference subjects.

[0064] This reference database is for example built on the basis of the results of psychovisual studies on a group of reference subjects. The refractive errors measured on these reference subjects, presented with different optical filters having predefined known spectral characteristics, are used to model the refractive error shift induced by the predefined optical filters.

[0065] In the example described below, the reference database contains data collected from a psychovisual study on 30 young adults. Measurements of refractive error shift were performed. For each subject-optical filter combination, the monocular equivalent sphere (MES) was measured for each eye by the subjective refraction method. The same measurements were performed without the optical filter. The age of each subject is also known.

[0066] Two different embodiments are described below.

[0067] The approach used in the first embodiment uses physiological parameters of the eye to calculate the defocus.

[0068] The approach used in the second embodiment determines the focus blur function based on experimental data.

[0069] First embodiment According to this embodiment, the one or more values ​​of the one or more initial spectral characteristics of the light source include an initial spectrum of light emitted by the light source. The one or more processors 12 are programmed to determine one or more values ​​of the one or more reference spectral characteristics of a reference light beam emitted by the light source and reaching the retina of the subject's eye E without any additional optical filter OF.

[0070] For example, the one or more processors 12 are programmed to determine a reference spectrum Spect_ref of a reference beam, which is determined, for example, by multiplying, for each wavelength, the initial spectrum Spect_source of the light source by the transmission or transmittance of the front of the eye Trans_eye, i.e. Spect_ref(λ)=Spect_source(λ)×Trans_eye(λ) is determined by.

[0071] The one or more processors are also programmed to determine one or more test spectral characteristics of a test light beam emitted by the light source and passing through an additional optical filter OF to a retina of the subject's eye.

[0072] For example, the one or more processors 12 may be programmed to determine a test spectrum of the test light beam, Spect_test, for example, by multiplying, for each wavelength, a reference spectrum Spect_ref of the light source by the transmission or transmittance of an optical filter Trans_filter, i.e., Spect_test(λ)=Spect_ref(λ)×Trans_filter(λ).

[0073] The one or more spectral features of the light transmitted through the optical filter to the subject's eye, i.e., the test spectrum, may include wavelength statistics that represent a wavelength distribution of the spectrum of the light transmitted through the optical filter to the subject's eye, i.e., the test spectrum, hereinafter referred to as "wavelength test statistics."

[0074] Similarly, one or more spectral characteristics of the light beam transmitted to the subject's eye E in the absence of an optical filter OF, i.e., the reference light beam, may include wavelength statistics that represent the wavelength distribution of the reference spectrum of the reference light beam emitted by the light source and transmitted to the subject's eye in the absence of an optical filter.

[0075] The one or more processors 12 are programmed to determine wavelength statistics representative of the wavelength distribution of a reference spectrum, hereinafter referred to as "reference wavelength statistics." The reference wavelength statistics are determined based on an initial spectrum of light emitted by the light source.

[0076] For example, the wavelength statistics representing the wavelength distribution of the test spectrum or of the reference spectrum include the wavelength centroids WLbar_test, WLbar_ref of the test spectrum or of the reference spectrum.

[0077] The wavelength centroids WLbar_test, WLbar_ref may be determined as a weighted average of the wavelengths of the spectrum, where the weighting coefficients are equal to the normalized values ​​(in terms of intensity, luminance, radiance, luminosity) of the spectrum at each wavelength. The following formula can be used to determine the wavelength centroid:

number

[0078] In this first embodiment, the one or more memories 11 further store data relating to the axial chromatic aberration of the eye as a function of the wavelength of the light beam transmitted to the eye.

[0079] An example of such data is shown in FIG. 5, which shows a graph of the axial chromatic aberration of the eye in diopters versus wavelength.

[0080] Alternatively, the data may include a table of axial chromatic aberration values ​​associated with corresponding wavelengths.

[0081] The axial chromatic aberration of the eye stored in the memory may be the average axial chromatic aberration for a human eye, or may be a customized axial chromatic aberration. The customized axial chromatic aberration may be determined based on the subject's personal characteristics, such as age, sex, type of refractive error, etc. It may be determined based on statistics of axial chromatic aberration for a population of subjects. The axial chromatic aberration of the subject's eye may also be measured.

[0082] The refractive shift model then includes the relationship between the refractive shift of the subject's eye and the axial chromatic aberration of the subject's eye over wavelength statistics.

[0083] In effect, the refractive shift model takes into account the axial chromatic aberration of the subject's eye at the reference wavelength statistics.

[0084] More precisely, the refractive shift model defines a shift value S equal to the difference between the axial chromatic aberration LCA of the eye at the test wavelength statistics WLbar_test (WLbar_test) and the axial chromatic aberration LCA of the eye at the reference wavelength statistics WLbar_ref (WLbar_ref), i.e. S=CA_test-CA_ref, where CA_test=LCA(WL_test) and CA_ref=LCA(WLbar_ref) (See Figure 5)

[0085] Optionally, the refraction shift model can take into account the axial chromatic aberration of the substrate of the optical filter in addition to the axial chromatic aberration of the eye, in which case the axial chromatic aberration value LCA(WLbar_test) or LCA(WLbar_ref) taken into account is the sum of the axial chromatic aberration of the substrate and the axial chromatic aberration of the eye.

[0086] As previously discussed, in a variant, one or more processors can be programmed to consider a weighting factor Wf(λ) for determining the reference spectrum. The weighting factor Wf(λ) is determined based on the response curves of three types of retinal cones: S, M and L (CIE data).

[0087] Such a weighting coefficient Wf(λ) can be derived, for example, based on the response curves Response_S(λ), Response_M(λ), and Response_L(λ) of retinal cells that detect light rays, based on three types of cones denoted as S, M, and L below.

[0088] The weighting factor Wf(λ) can be determined as a weighted average of the responses of the three types of cones to each wavelength, which is calculated, for example, as Wf(λ)=ws×Response_S(λ)+wl×Response_L(λ)+wm×Response_M(λ), where ws, wm, and wl are three scalars defined to determine the weight of each cone response.

[0089] For example, the one or more processors 12 may multiply the initial spectrum of the light source Spect_source by the transmission or transmittance of the front of the eye Trans_eye and a weighting factor Wf, i.e. Spect_ref(λ)=Spect_source(λ)×Trans_eye(λ)×Wf(λ) is programmed to determine a reference spectrum of the reference beam.

[0090] The one or more processors 12 are then programmed to determine a test spectrum Spect_test by taking into account the same weighting factor Wf and multiplying the reference spectrum Spect_ref of the light source by the transmission or transmittance of the optical filter Trans_filter, i.e. Spect_test(λ)=Spect_ref(λ)×Trans_filter(λ). The weighting factor Wf is taken into account in the value of the reference spectrum Spect_ref.

[0091] The weighting factor Wf(λ) may be determined by the following process.

[0092] For each reference subject of the population of reference subjects and for each filter of the set of reference filters, the refractive error shift is estimated by the method described above without weighting factors. The equivalent spherical shift for each eye of each subject is then measured for each filter.

[0093] Examples of implementations of these steps can be found in US Patent Publication No. 2020315448.

[0094] Then, for each filter, the scalar values ​​ws, wm and wl are determined by an optimization algorithm to minimize the difference between the estimated refractive error shift and the measured equivalent spherical shift for each eye of each subject. In this example, the optimization results are: ws=0.05, wm=-0.5, wl=0.87.

[0095] Here, the optimization space was not restricted to positive coefficients.

[0096] The resulting weighting factor Wf(λ) is shown in Figure 7. The weighting factor curve is positive everywhere.

[0097] Then, to test the method according to the first embodiment, this refractive shift model was applied to a new set of nine filters corresponding to a commercial sun lens and dopamine. Thanks to this method, a calculated shift was determined for each filter.

[0098] The spectra of each filter SA, SB, SC, SD, SE, SF, SG, SH, and SI of a new set of nine filters, designated sun lenses or filters A to I, are shown in Figure 8.

[0099] For each of the 30 reference subjects, the measured value of the refractive shift introduced by each filter of this new set of filters was also measured. The measured shift associated with each filter was obtained by averaging these measured values. The standard deviation of the 30 measured values ​​was determined. The calculated shift determined by the refractive shift model was then compared to the measured shift. The results are summarized in the table below.

[0100] [Table 1]

[0101] These results are also summarized in Figure 9, which shows the measured and calculated shift values ​​for each filter of the new set of nine filters. The results show that of the nine filters, five filters caused smaller refractive shifts and four filters caused larger refractive shifts.

[0102] More precisely, sun lenses B, C, E, F, and G caused refractive shifts smaller than 0.05D.

[0103] For these filters, the average measured refractive shifts are smaller than the standard deviation (sigma ≈ 0.09 D) across all 30 reference subjects. The average measured refractive shifts are also small compared to the usual prescription tolerances in lens manufacturing (approximately 0.12 D). Finally, the average measured refractive shifts are probably below the prescription sensitivity of most subjects. Therefore, these refractive shifts are considered negligible, and precise calculation of these shifts is not important.

[0104] Sun lenses A, D, H and I caused a refractive shift of greater than 0.1D.

[0105] For these filters, the average of the measured refractive shifts is greater than the standard deviation of the measured shift values ​​for the 30 reference subjects. Furthermore, some subjects are sensitive to these values ​​of refractive shift, which means that the subjects will be able to recognize this refractive shift. Therefore, these refractive shifts are considered to be significant.

[0106] For these filters, the refractive shift model described above accurately predicts the sign of the refractive shift. The mean absolute error on the refractive shift is 0.05D, which is satisfactory given the variance of the data.

[0107] Here, the calculated and measured refractive shifts were analyzed for a given light source having the spectrum shown in Figure 3. This particular light source has a higher radiance for the determined wavelength. To determine the effect of the light source on the calculated refractive shift, two different sunlight conditions were used: i) Early sunrise, color temperature ≒ 3000K ii) Noon sun, color temperature ≒ 5500K) took into consideration.

[0108] Other lighting conditions tested included a chart illuminated with 7 LED light sources, referenced as ETDRS in FIG. 10, and a commercially available screen with the spectrum of FIG. 3, designated CS.

[0109] The calculated refractive shifts for both sunlight conditions were determined and compared for a 45-year-old subject for a commercial screen CS with the spectrum of Figure 3 and for a chart illuminated with 7 LED light sources (EDTRS).

[0110] The results are shown in Fig. 10, which shows that for the four filters A, D, H and I, the calculated refractive shifts are relatively stable to the light source. The calculated refractive shifts can then be useful in different lighting conditions. The method according to the invention makes it possible to take into account the spectral characteristics of the light source used.

[0111] The method described above therefore makes it possible to determine with good precision the refractive shifts introduced by a filter due to different light sources, without making any measurements.

[0112] Second embodiment According to a second embodiment, the one or more spectral characteristics of the test light transmitted through the optical filter to the subject's eye include a test spectrum of the test light in a predetermined global wavelength range.

[0113] This predefined global wavelength range preferably covers the visible spectrum of light, which means, for example, that it corresponds to a wavelength range comprised between 380 and 800 nm, or between 400 and 700 nm.

[0114] In this embodiment, the predetermined global wavelength range is the fundamental wavelength range B i and each determined fundamental wavelength range B i The basic shift value S caused by i and is divided into

[0115] Basic wavelength range B i corresponds to a band of wavelengths, as shown diagrammatically in FIG.

[0116] The fundamental wavelength range Bi preferably covers the entire global range continuously, and B i =[λ i1 ,λ i2 [=[λ i , λ (i+1) [.

[0117] In practice, the one or more memories 11 store fundamental shift values ​​S associated with a given fundamental wavelength range Bi. i The refractive shift model stores the refractive shift and the fundamental wavelength range B included in the predetermined global wavelength range. i The corresponding fundamental wavelength range B for all i The fundamental shift value S weighted by the integral of the spectrum of the light transmitted to the eye through the filter OF within iThis includes the sum of and the relationship between.

[0118] As described in the first embodiment, for a given light source having a predetermined initial spectrum, the one or more processors 12 are programmed to determine a test spectrum of a test light beam. This test spectrum Spect_test(λ) is determined, for example, by multiplying the reference spectrum Spect_ref(λ) of the light source by the transmission or transmittance of an optical filter Trans_filter(λ), i.e., Spect_test(λ)=Spect_ref(λ)×Trans_filter(λ). The reference spectrum Spect_ref(λ) is determined, for example, by multiplying the initial spectrum Spect_source(λ) of the light source by the transmission or transmittance of the front of the eye Trans_eye(λ), i.e., Spect_ref(λ)=Spect_source(λ)×Trans_eye(λ), as described above.

[0119] The one or more processors may be programmed to take into account weighting factors, such as the weighting factors described in the first embodiment, when determining the reference spectrum.

[0120] The calculated refractive shift takes into account the fundamental shift in each band of the global wavelength range, weighted by the integral of the test spectrum in that band, and then summed weighted over the global wavelength range.

[0121] The refractive shift model provides a shift value that is equal to the ratio between the sum and the integral of the spectrum of light transmitted to the eye through the filter within a given global wavelength range.

[0122] The one or more processors 12 are then programmed to determine the calculated refractive shift using the following formula:

number

[0123] The base shift value Si is determined, for example, by considering a database including a plurality of test spectra of light transmitted to the eye and corresponding measurements of refractive shift in the eye, and minimizing the difference between each measurement of the refractive shift and the value of the refractive shift determined using the above-mentioned relationship and the test spectrum of light transmitted to the eye to which the measurement of the refractive shift corresponds.

[0124] In practice, as an example of a realization of this second embodiment, it is possible to define six fundamental wavelength ranges of 50 nm between 400 and 700 nm (as shown in FIG. 11).

[0125] Basic shift value S i is optimized to minimize the difference between the calculated and measured refractive shifts using a database of measured refractive shifts. As already mentioned for the first embodiment, this database can be obtained by collecting the refractive shifts measured using nine filters described as sun lenses A to I for 30 reference subjects.

[0126] The basic shift value S thus obtained i are summarized in Table 2 below.

[0127] [Table 2]

[0128] A comparison between the measured and calculated refractive shifts for the nine filters “Sun Lenses A-I” is shown in FIG.

[0129] It is noted that the calculated refractive shifts are very close to the measured refractive shifts, especially for the four filters A, D, H and I. The refractive shift model used in this second embodiment of the method is accurate.

[0130] In this example, the refractive shift model has six degrees of freedom, i.e., six basic refractive shifts S ivalues, whereas the refraction shift model of the first embodiment only has three degrees of freedom, i.e., three scalars for the weighting coefficients.

[0131] In another example of the second embodiment, it is possible to define three fundamental wavelength ranges of 100 nm between 400 and 700 nm.

[0132] The basic shift value S determined at that time i ' are summarized in Table 3 below.

[0133] [Table 3]

[0134] The results using the three fundamental wavelength ranges are as good as the results using the six fundamental wavelength ranges: the difference between the measured refractive shift and the refractive shift calculated according to the method of the present invention is less than 0.04D for all filters.

[0135] Optionally, the refractive shift model can take into account the axial chromatic aberration of the substrate of the optical filter in addition to the axial chromatic aberration of the eye. In that case, a basic shift value Si needs to be established for multiple substrate materials. When predicting the refractive shift for a given optical filter, the Si value corresponding to the specific substrate of the optical material should be used.

[0136] Thus, the device and method of the present invention make it possible to determine the refractive shift introduced by the filter OF to the subject's eye E easily, quickly and without the need to perform any measurements.

[0137] The refractive shifts calculated using the described devices and methods can be used for many different applications.

[0138] This can be used to modify the refractive power of corrective lenses, including filters, to compensate for this refractive shift and ensure precise vision correction.

[0139] The refractive power of the corrective lenses may be fixed and then modified before manufacturing the eyewear, in which case the device according to the invention can be integrated into a lens manufacturing computer that designs the lenses according to the selected optical filter functions.

[0140] In the case of an ophthalmic lens with variable refractive power and / or a variable filter, the refractive power can also be changed in real time, where the refractive power variation and / or the color variation are adjusted to take into account the refractive shift caused by the undetermined color tone of the optical filter. The device according to the present invention can be incorporated into a frame carrying an ophthalmic lens with variable refractive power and / or a variable filter, or into any device, preferably wearable by the subject, adapted to communicate with a controller that controls an ophthalmic lens with variable refractive power and / or a variable filter.

[0141] Thus, adaptive eyewear for a subject according to the present invention comprises: an ophthalmic lens having a variable refractive power and / or a variable filter, the amount of variation of which is controlled by a controller; a device as defined above according to the invention; Equipped with The device is in communication with a controller, which is programmed to determine a power variation and / or a shade variation of the ophthalmic lens taking into account a shift in the refraction of the subject's eye determined by the device.

[0142] Additionally, the refractive shift model may be modified to account for the index of the lens substrate and / or filter material. [Explanation of symbols]

[0143] 10 Devices 11. Memory 12 processors

Claims

1. A device (10) for determining the refractive shift of a subject's eye (E) irradiated by a light ray emitted from a light source (S), wherein the shift is caused by an optical filter (OF) through which the light ray passes as it is transmitted to the subject's eye (E), and the device (10) comprises one or more memories (11) and one or more processors (12). The one or more memory (11) mentioned above is One or more values ​​(100) of one or more initial spectral features of the light source (S), One or more values ​​(200) of one or more optical features of the optical filter (OF), A refractive shift model (300) that links the magnitude associated with the shift with one or more spectral features of the light ray transmitted to the subject's eye (E), Remember this, The one or more processors (12) described above are: Step (400) of determining one or more values ​​of one or more spectral features of the light rays transmitted to the subject's eye through the optical filter (OF) based on one or more values ​​of one or more initial spectral features of the light source (S) and one or more values ​​of one or more optical features of the optical filter (OF), Step (500) of determining the refraction shift of the subject's eye (E) based on the refractive shift model and the values ​​of the spectral features of the light rays transmitted to the subject's eye (E) through the optical filter (OF), A device (10) that is programmed to perform the following.

2. The device according to claim 1, wherein one or more values ​​of the one or more initial spectral features of the light source (S) include the initial spectrum of light emitted by the light source (S), and one or more values ​​of the one or more optical features of the optical filter (OF) include a value that quantifies the transmission of light passing through the optical filter (OF).

3. The device according to claim 1, wherein the one or more processors (12) are programmed to determine the spectrum of the light ray transmitted to the eye (E) of the subject through the optical filter (OF) in order to determine one or more values ​​of the one or more spectral features of the light ray transmitted to the eye (E) of the subject through the optical filter.

4. The device according to claim 1, wherein the one or more memories (11) further store data relating to one or more optical features of the subject's eye (E), and the one or more processors are programmed to take the data into consideration in order to determine one or more values ​​of one or more spectral features of the light rays transmitted to the subject's eye (E) through the optical filter (OF).

5. The device according to claim 4, wherein one or more memories (11) store weighting coefficients (Wf) representing the photosensitivity of the retina of the subject's eye (E) at one or more wavelengths, and one or more processors (12) are programmed to determine one or more values ​​of the one or more spectral features of the light rays transmitted to the subject's eye (E) through the optical filter (OF), taking the weighting coefficients (Wf) into consideration.

6. The device according to claim 1, wherein one or more spectral features of the light ray transmitted to the subject's eye (E) through the optical filter (OF) include wavelength statistics representing the wavelength distribution of the spectrum of the light ray transmitted to the subject's eye (E) through the optical filter (OF).

7. The device according to claim 6, wherein the wavelength statistical value representing the wavelength distribution of the spectrum includes the wavelength centroid of the spectrum.

8. The device according to claim 6, wherein the one or more memories (11) store data relating to the axial chromatic aberration of the eye (E) in accordance with the wavelength of light rays transmitted to the eye, and the refractive shift model includes a relationship between the refractive shift of the subject's eye and the axial chromatic aberration of the subject's eye in the wavelength statistics.

9. The one or more values ​​of one or more initial spectral features of the light source include the initial spectrum of light emitted by the light source (S). The one or more processors (12) are programmed to determine, based on the initial spectrum of the light emitted by the light source (S), a reference wavelength statistic representing the wavelength distribution of the reference spectrum of the reference ray emitted by the light source (S) and transmitted to the eye of the subject in the absence of the optical filter (OF), The device according to claim 8, wherein the refractive shift model takes into account the axial chromatic aberration of the subject's eye (E) in the reference wavelength statistics.

10. The device according to claim 9, wherein the refractive shift model provides a shift value equal to the difference between the axial chromatic aberration of the eye in the wavelength statistics and the axial chromatic aberration of the eye in the reference wavelength statistics.

11. The device according to claim 1, wherein the one or more spectral features of the light ray transmitted to the eye (E) of the subject through the optical filter (OF) include the spectrum of the light ray transmitted to the eye (E) through the optical filter (OF) over a predetermined global wavelength range.

12. The device according to claim 11, wherein one or more memories (11) store fundamental shift values ​​(Si) associated with a predetermined fundamental wavelength range (Bi), and the refractive shift model includes a relationship between the refractive shift and the sum of the fundamental shift values ​​(Si) weighted by the integral of the spectrum of light transmitted to the eye through the optical filter within the corresponding fundamental wavelength range (Bi) for all of the corresponding fundamental wavelength ranges (Bi) included in the predetermined global wavelength range.

13. The device according to claim 12, wherein the refractive shift model provides a shift value equal to the ratio between the sum and the integral of the spectrum of the light transmitted to the eye through the optical filter (OF) within a predetermined global wavelength range.

14. Adaptive eyewear for subjects, An ophthalmic lens having variable refractive power and / or a variable filter whose variation is controlled by a controller, A device according to any one of claims 1 to 13, Equipped with, Adaptive eyewear, wherein the device communicates with the controller, which is programmed to determine refractive power variations and / or color variations of the ophthalmic lens, taking into account the shift in the refraction of the subject's eye (E) as determined by the device.

15. A method for determining the refractive shift of a subject's eye (E) irradiated by a light ray emitted from a light source (S), wherein the shift is caused by an optical filter (OF) through which the light ray passes as it is transmitted to the subject's eye (E), and the device comprises one or more memories (11) and one or more processors (12), and the method is The steps include determining one or more values ​​of one or more initial spectral features of the light source (100), The steps include determining one or more values ​​of one or more optical features of the optical filter (200), The steps include providing a refractive shift model that links the magnitude associated with the shift with one or more spectral features of the light ray transmitted to the subject's eye (300), A step (400) of determining one or more values ​​of one or more spectral features of the light ray transmitted to the subject's eye (E) through the optical filter (OF) based on one or more values ​​of one or more initial spectral features of the light source (S) and one or more values ​​of one or more optical features of the optical filter (OF), Step (500) of determining the refraction shift of the subject's eye (E) based on the refractive shift model and the values ​​of the spectral features of the light rays transmitted to the subject's eye (E) through the optical filter (OF), A method that includes this.

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