Filter and method for determining the filter taking into account the spectral transmittance of the ocular medium of the wearer's eye

Abstract

The present invention relates to a method for determining at least one filter for a visual device intended to be placed in front of a user's eye, the at least one filter being capable of improving the user's visual comfort and / or visual performance, the method comprising the following steps: ‑ determining the spectral transmittance of the ocular medium of at least one eye of the user; and ‑ determining at least one filter based on the determined spectral transmittance of the user's ocular medium, such that the filter has a spectral transmittance distribution comprising: o a first portion having a maximum transmittance value between 380 nm and a predetermined wavelength threshold, o a second portion with decreasing transmittance values ​​between the predetermined wavelength threshold and 670 nm. The present invention also relates to a filter whose spectral transmittance is calculated based on the spectral transmittance of the user's ocular medium. The present invention further relates to a set of filters, wherein each filter in the set has a spectral transmittance based on the spectral transmittance of the ocular medium of users of different ages.

Description

Technical Field

[0001] The present invention relates to the manufacture of visual devices, such as ophthalmic lenses.

[0002] More particularly, the present invention relates to a method for determining at least one filter for a visual device intended to be placed in front of the eyes of a user. Background Art

[0003] Sunglasses are often used for comfort and protection, but they can impair visual perception when the environment is not bright enough. With aging, the lens darkens and yellows, and cataracts may develop. The overall and spectral transmission of the ocular media continuously evolves. The ocular media is the transparent material of the eye and includes the cornea, aqueous humor, lens, and vitreous humor.

[0004] Figure 1 A graph showing the total transmittance of a transparent ocular medium of an aging human eye as a function of wavelength is shown. As can be seen from the graph, the transmittance of the ocular medium decreases in the shortest wavelengths (<525 nm), while the sensitivity remains unchanged for long wavelengths (>600 nm) [CIE 203 2012 - Transmittance data reaching the retina for a healthy aging eye].

[0005] In addition to the reduction in sensitivity of photoreceptors and transmission of ganglion cells, it also leads to differences in light sensitivity, visual performance, and light comfort or discomfort between wearers of different ages. For the elderly, wearing inappropriate sunglasses may affect their visual performance.

[0006] Furthermore, color adaptation to the yellow tint of the lens occurs gradually [Delahunt, Webster, Ma, Werner, Long-term renormalization of chromatic mechanisms following cataract surgery, Visual Neuroscience, 2004], and the effect is reversed after cataract surgery. If the initial distortion of color vision is gradual, the color perception can be harsh and potentially disturbing.

[0007] Until now, neither sunglasses nor filters have taken into account the lens opacities that occur with age, either in a general or individual manner. In fact, the measurement of ocular media is complex.

[0008] Therefore, there is a need for a filter that is able to take into account the specificities of the user's ocular media, especially as they age, to improve their visual perception. Summary of the Invention

[0009] To this end, the present invention provides a method for determining at least one filter for a visual device intended to be placed in front of the eyes of a user, said at least one filter being capable of improving the visual comfort and / or visual performance of said user, the method comprising the following steps:

[0010] - determining the spectral transmittance of the ocular medium of at least one eye of said user; and

[0011] - determining at least one filter based on the determined spectral transmittance of the user's ocular medium, such that the filter has a spectral transmittance distribution comprising

[0012] o a first portion having a maximum transmittance value between 380 nm and a predetermined wavelength threshold,

[0013] o A second portion in which the transmittance value decreases between the predetermined wavelength threshold and 670 nm.

[0014] Determining the filter based on the spectral transmittance of the ocular medium allows the filtering function of the filter to be closely adapted to the eye characteristics of the user. In particular, the spectral transmittance in the visible light range can be balanced.

[0015] The determined filter can take into account the user's age to improve light comfort without affecting vision. Therefore, it is possible to produce similar light intensity and closer color perception for users of different ages, especially for young wearers and older wearers.

[0016] Wearing the improved filter before cataract surgery can reduce the time it takes for color to return after surgery, which takes several months on average.

[0017] Furthermore, it allows for providing older adults with sunglasses that are not so dark as to reduce visual performance.

[0018] Determining the spectral transmittance of the filter with a spectral transmittance distribution having said first and second portions allows compensating for transmittance losses of the ocular medium while maximizing light entering the user's eye and eye stimulation over a large wavelength range.

[0019] According to an embodiment of the determination method, the maximum transmittance value is between 70% and 100%.

[0020] According to an embodiment of the determination method, the second portion decreases continuously from the maximum transmittance value to a minimum target transmittance value, the minimum target transmittance value corresponding to a wavelength between 630 nm and 670 nm.

[0021] According to one embodiment of the determination method, the method further comprises the step of determining a target transmittance value, the filter being determined such that the minimum transmittance value is between -10% and +10% of the target transmittance value. Preferably, the minimum transmittance value is between -5% and +5% of the target transmittance value.

[0022] According to one embodiment of the determination method, the spectral transmittance of the user's ocular medium is determined based on a measurement of the user. This measurement can be performed directly on the user's eye, i.e., in situ, or indirectly, for example, based on data corresponding to the user's eye. This data can include, for example, an image of the user's ocular medium.

[0023] According to one embodiment of the determination method, the spectral transmittance of the ocular medium of the user is determined based on the age of the user. In doing so, no specific measurements are performed on the user to determine the spectral transmittance of the ocular medium of his eye. Instead, the spectral transmittance is determined based on general data that correlates spectral transmittance with age. For example, Figure 1 The data in can be considered as the basis for determining the spectral transmittance of the user.

[0024] An example of such a determination may include first determining the overall transmittance of a lens for a reference age (e.g., for a 20-year-old wearer). The specific transmittance of the ocular medium of a given wearer is then determined based on this overall reference transmittance. In particular, a lens that matches the needs of a given wearer can be determined by dividing the reference transmittance by the specific transmittance of the ocular medium for the given wearer's age.

[0025] According to one embodiment of the determination method, the spectral transmittance of the user's ocular medium is determined based on a spectral transmittance test.

[0026] According to one embodiment of the determination method, the spectral transmittance test comprises the step of measuring the absolute scotopic threshold. "Absolute scotopic threshold" refers to the lowest level of brightness or illuminance perceived by the wearer after dark adaptation.

[0027] According to one embodiment of the determination method, the spectral transmittance test includes a step of measuring absolute light discomfort. "Absolute light discomfort" refers to the level of brightness or illuminance perceived by the wearer at a certain level of discomfort (e.g., just noticeable, unbearable, etc.).

[0028] According to one embodiment of the determination method, the spectral transmittance test includes a step of equalizing the photopic brightness. "Photopic brightness" refers to the level of brightness within the photopic field (higher than 1 cd / m 2 threshold, preferably 100cd / m2).

[0029] According to an embodiment of the determination method, the ocular medium of the user is a lens.

[0030] According to one embodiment of the determination method, the spectral transmittance of the filter is calculated as follows:

[0031] T(λ,age)=T Ref (λ) / T crystalline (λ,age)

[0032] Among them, for T Ref (λ) / T crystalline (λ,age)>1, T(λ,age)=1.

[0033] According to one embodiment of the determination method, the at least one filter is determined to have a variable spectral transmittance depending on the wavelength. This allows closely adapting the filter to the distribution of the spectral transmittance of the user's ocular medium.

[0034] According to one embodiment, the determination method is a computer-implemented method. The present invention also provides a computer program product comprising instructions for performing the method described above. The computer program product is advantageously configured to perform the method according to the present disclosure in any of its execution modes.

[0035] The present invention further provides an apparatus comprising a memory having recorded thereon the computer program as described above, the apparatus optionally further comprising a processor and a graphical user interface coupled to the memory.

[0036] The present invention also provides a filter for a visual device intended to be placed in front of an eye of a user, wherein the spectral transmittance of the filter is calculated based on the spectral transmittance of the ocular medium of the user, so that the filter has a spectral transmittance distribution comprising:

[0037] o a first portion having a maximum transmittance value between 380 nm and a predetermined wavelength threshold,

[0038] o A second portion in which the transmittance value decreases between the predetermined wavelength threshold and 670 nm.

[0039] This filter closely considers the Figure 1The results observed in 2012, namely that with age the transmittance of the ocular medium decreases at the shortest wavelengths, while the sensitivity remains constant for the long wavelengths [CIE 203 2012 - Transmittance data reaching the retina for a healthy aging eye]. Long-wavelength cut-off filters were therefore developed, i.e. filters that transmit shorter wavelengths than long wavelengths, in order to balance the maximum sensitivity at the longest wavelengths due to yellowing of the lens.

[0040] According to one embodiment of the filter, the predetermined wavelength threshold is between 425 nm and 525 nm. This allows obtaining further compliance with Figure 1 The results observed in the filter.

[0041] The present invention further provides a set of filters for a visual device intended to be placed in front of an eye of a user, wherein each filter in the set has a spectral transmittance based on the spectral transmittance of an ocular medium of a user of different ages, the spectral transmittance of each filter in the set of filters being calculated such that the filter has a spectral transmittance profile comprising:

[0042] o a first portion having a maximum transmittance value between 380 nm and a predetermined wavelength threshold,

[0043] o A second portion in which the transmittance value decreases between the predetermined wavelength threshold and 670 nm. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] For a more complete understanding of the description provided herein and its advantages, reference is now made to the following brief description taken in conjunction with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

[0045] Figure 1 is a graph showing the total transmittance of a transparent ocular medium of an aging human eye as a function of wavelength [from CIE203 2012 - Transmittance data reaching the retina for an healthy aging eye].

[0046] Figure 2 is a graph showing the level of comfort or discomfort for different age groups depending on the dominant wavelength.

[0047] Figure 3 is a graph showing the theoretical spectral transmittance distribution of different lenses depending on wavelength.

[0048] Figure 4 is a graph showing the theoretical spectral transmittance distribution and the corresponding calculated spectral transmittance distribution of different lenses depending on wavelength. DETAILED DESCRIPTION

[0049] In the following description, the drawings are not necessarily drawn to scale, and for the purpose of clarity and brevity or for informational purposes, certain features may be shown in summary or schematic form. In addition, although the manufacture and use of various embodiments are discussed in detail below, it should be understood that many inventive concepts that can be implemented in a variety of contexts are provided as described herein. The embodiments discussed herein are merely representative and do not limit the scope of the invention. It will also be apparent to those skilled in the art that all technical features defined with respect to the method can be transposed to the device, either individually or in combination, and conversely, all technical features defined with respect to the device can be transposed to the method, either individually or in combination.

[0050] The terms "comprise" (and any grammatical variations thereof, such as "comprises" and "comprising"), "have" (and any grammatical variations thereof, such as "has" and "having"), "contain" (and any grammatical variations thereof, such as "contains" and "containing"), and "include" (and any grammatical variations thereof, such as "includes" and "including") are open-ended linking verbs. They are used to indicate the presence of the features, integers, steps or components or groups they describe, but do not exclude the presence or addition of one or more other features, integers, steps or components or groups thereof. Thus, a method or step in a method that "comprises," "has," "contains," or "includes" one or more steps or elements has those one or more steps or elements, but is not limited to having only those one or more steps or elements.

[0051] The claimed method allows determining at least one filter for a visual device intended to be placed in front of a user's eyes.

[0052] The visual device may be an ophthalmic lens or a pair of ophthalmic lenses, which may be active lenses, or a sun lens or a pair of sun lenses, or an ophthalmic sun lens or a pair of ophthalmic sun lenses. The visual device may be in the form of a glass lens, a contact lens, or an intraocular lens. For example, the visual device may be a pair of progressive lenses. The sun lens may be any of types 0, 1, 2, 3, or 4.

[0053] The at least one filter can improve the visual comfort and / or visual performance of the user.

[0054] A filter can be determined for each eye of an individual. In this case, the filters determined for each eye can be the same or different. Likewise, the filters can even be selected so as to provide a good compromise between the two eyes of an individual.

[0055] The filter is determined by first determining the spectral transmittance of the ocular medium of at least one eye of the user. The ocular medium is the transparent material of the eye and may include the cornea, aqueous humor, lens, and vitreous body. Preferably, the ocular medium of the user under consideration may be only the lens. The filter may be determined based on the spectral transmittance of one or both eyes of the wearer.

[0056] The spectral transmittance of the lens can be obtained based on general data (e.g. Figure 1 , determined based on the CIE transmittance curve of the ocular medium of the aging eye) or dedicated measurements (objective or psychovisual).

[0057] The filter is then determined based on the determined spectral transmittance of the user's ocular media.

[0058] The at least one filter may include a set of filters, wherein each filter in the set has a spectral transmittance based on the spectral transmittance of an ocular medium of a user of a different age.

[0059] This determined method is described in detail below.

[0060] like Figure 1 As shown, with age, fewer short wavelengths reach the retina because they are absorbed by the lens. Consequently, older observers are less sensitive to shorter wavelengths of light. Depending on the spectral properties of light, it can cause varying degrees of light comfort or discomfort. This effect was demonstrated in a study evaluating light comfort at different wavelengths.

[0061] Figure 2 The light sensitivity of a first group of young observers 10 and a second group of elderly observers 20 is shown. In particular, Figure 2 The graph shows the average values ​​recorded by each group of observers for different wavelength values. The higher the value between 0 and 5, the more pleasant the light is.

[0062] As can be seen in the graph, younger people have lower absolute scores for all wavelengths (1.22 for younger observers and 3.10 for older observers) due to the higher transmittance of the eye lens. In fact, due to the higher spectral transmittance of the ocular medium, the discomfort experienced by younger observers is higher than that for older observers.

[0063] Furthermore, it appears that wavelengths of 619nm and 660nm are judged by older observers to be less comfortable than lower wavelengths. Thus, it can be seen that the decrease in spectral transmittance of the ocular medium with aging is not uniformly distributed. This suggests that filtering longer wavelengths can balance comfort and produce the same relative perception as in younger people. The effect of a neutral filter on young adults may mirror that of a cyan filter on older adults.

[0064] Therefore, a universal filter that reduces the transmission of wavelengths above 525 nm can be provided for the elderly to increase their comfort with light.

[0065] Instead of a generic filter, a specific filter may be determined for a given wearer.

[0066] A first embodiment relates to determining the specific spectral transmittance of the wearer's ocular medium based on a reference spectral transmittance of a reference wearer, for example a 20-year-old.

[0067] First, a reference spectral transmittance of the ocular medium of a reference wearer is determined. This reference spectral transmittance can be based on Figure 1 to determine the results.

[0068] The transmitted light through the lens can be defined as follows:

[0069] T(λ,age)=T Ref (λ) / T crystalline (λ,age),

[0070] in

[0071] T Ref (λ)=T lens (λ)*T crystallineXyearsold (λ)

[0072] in

[0073] T Ref (λ) is the spectral transmittance of the filter to be determined

[0074] T lens (λ) is the spectral transmittance of a given lens

[0075] T crystallineXyearsold (λ) is the reference spectral transmittance of the ocular medium of a reference wearer of age x

[0076] λ is the wavelength

[0077] As an example, assume a neutral 85% Tv lens with T for a 20 year old reference lens (λ)=0.85:

[0078] TRef (λ)=0,85*T crystalline20yearsold (λ)

[0079] For older wearers, a lens can be calculated for λ[380;700]nm:

[0080] T(λ,age)=T Ref (λ) / T crystalline (λ,age)

[0081] Among them, for T Ref (λ) / T crystalline (λ, age)>1, T(λ, age)=1

[0082] This mathematical relationship is Figure 3 As shown, the T of the first lens 30 and the second lens 40 of a 60-year-old wearer is lens (λ) are 80% and 40%, respectively. These graphs show the spectral transmittance depending on the wavelength.

[0083] It can be seen that the filter is determined to have a non-uniform spectral transmission distribution in the visible spectrum. In particular, short wavelength values ​​are filtered less to accommodate the larger reduction in transmittance of the ocular medium in the shortest wavelengths (<525nm).

[0084] Each of the first lens 30 and the second lens 40 has a respective spectral transmittance profile defining a first portion and a second portion. The first lens 30 defines a first portion 32 and a second portion 34. The second lens 40 defines a first portion 42 and a second portion 44.

[0085] The first portion has a maximum transmittance value between 380 nm and a predetermined wavelength threshold. The transmittance value of the second portion decreases between the predetermined wavelength threshold and 670 nm. In other words, the spectral transmittance distribution has a substantially decreasing distribution from 380 nm to 670 nm.

[0086] The second portion preferably has a continuously decreasing transmittance value. A variation in transmittance value of 20% within this decreasing portion is contemplated, with a 10% variation being most preferred. In other words, the second portion may locally increase within a short wavelength range (e.g., 50 nm) but generally decrease between the predetermined wavelength threshold and 670 nm.

[0087] The spectral transmittance distribution is defined such that the second portion decreases continuously from the maximum transmittance value to a minimum target transmittance value. The minimum target transmittance value is located at a wavelength between 630 nm and 670 nm. Thus, the spectral transmittance distribution substantially decreases from the maximum spectral transmittance value to the minimum transmittance value from 380 nm to 670 nm, with a local deviation of 20%, most preferably 10%.

[0088] The maximum transmittance value is preferably between 70% and 100%.

[0089] Target transmittance values ​​can also be determined to establish Figure 3 Theoretical spectral transmittance distribution is shown. The target transmittance value corresponds to a theoretical minimum spectral transmittance value at a wavelength between 630 nm and 670 nm. The minimum transmittance value is between -10% and +10% of the target transmittance value, and most preferably between -5% and +5% of the target transmittance value.

[0090] For example, the target transmittance values ​​of the first lens 30 and the second lens 40 are 80% and 40%, respectively.

[0091] The predetermined wavelength threshold is determined based on the target transmittance value of the filter. For the first lens 30, the predetermined wavelength threshold is approximately 525 nm. For the second lens 40, the predetermined wavelength threshold is approximately 425 nm.

[0092] Figure 4 Shown Figure 3 The theoretical spectral transmittance distribution 30 or the target spectral transmittance distribution 40 of the filter and its corresponding calculated spectral transmittance distribution 50 or the actual spectral transmittance distribution 60. The calculated spectral transmittance distribution 50 of the first lens 30 defines a first portion 52 and a second portion 54. The calculated spectral transmittance distribution 60 of the second lens 40 defines a first portion 62 and a second portion 64.

[0093] According to a preferred embodiment, the spectral transmittance variation between the theoretical spectral transmittance distribution and the calculated spectral transmittance distribution is lower than or equal to 30% in the first portion and lower than or equal to 10% in the second portion.

[0094] Alternatively, a different formula for T(λ,age) can be used so that the transmission loss of the eye lens is compensated over a larger wavelength range (but at a disadvantage in terms of global transmission):

[0095] T(λ,age)=aT Ref (λ) / T crystalline (λ,age)

[0096] where a<1

[0097] For a. TRef(λ) / Tcrystalline(λ,age)>1, T(λ,age)=1

[0098] This alternative formulation allows shifting the mutation (T=1) towards shorter wavelengths.

[0099] A second embodiment relates to determining the specific spectral transmittance of the wearer's ocular medium in dependence on the measurement.A specific lens prescription can be prescribed for each individual wearer by means of a personalized measurement of the spectral transmittance of the lens.

[0100] The spectral transmission of the filter can be determined based on psychovisual experiments designed to balance light sensitivity across the visible light range.

[0101] The wearer's specific spectral transmission can be obtained by measuring the absolute scotopic threshold and absolute light comfort or discomfort for several wavelengths (at least at 400, 500 and 600 nm, ideally every 50 nm), or using a photopic brightness equalizer according to wavelength (at least between 400 nm, 500 nm and 600 nm).

[0102] A psychovisual experiment using measurements of absolute scotopic threshold may include the following steps:

[0103] - Use increasing illuminance or brightness (e.g. 10-8 cd / m 2 to 1cd / m 3 ) to provide controlled and uniform lighting,

[0104] - providing a controlled spectrum, for example using colored LEDs or using selective filters coupled to a white light source,

[0105] - irradiating the wearer with controlled uniform lighting with a controlled spectrum,

[0106] - Ask the wearer to signal the moment he is able to perceive the stimulus,

[0107] - This experience can be repeated for several dominant wavelengths (eg at least at 400 nm, 500 nm and 600 nm, ideally every 25 nm).

[0108] A psychovisual experiment using a measure of absolute light discomfort may include the following steps:

[0109] - using increasing illuminance or brightness (e.g. from 1 cd / m 2 Up to 500cd / m 2 To provide controlled and uniform lighting,

[0110] - providing a controlled spectrum, for example using colored LEDs or using selective filters coupled to a white light source,

[0111] - irradiating the wearer with controlled uniform lighting with a controlled spectrum,

[0112] - The wearer was asked to rate the discomfort of the light for each stimulus,

[0113] - This experience can be repeated for several dominant wavelengths (eg at least at 400 nm, 500 nm and 600 nm, ideally every 25 nm).

[0114] A psychovisual experiment using a measure of absolute light discomfort may include the following steps:

[0115] - provides controlled and uniform illumination, alternating between two different spectra (or different dominant wavelengths),

[0116] - Illuminate the wearer with controlled, uniform lighting,

[0117] - Ask the wearer to adjust the brightness of the first stimulus in order to balance the brightness of the different spectra (colors). The starting point of brightness can be 100 cd / m 2 about,

[0118] - This experience can be repeated for several dominant wavelengths (eg at least at 400 nm, 500 nm and 600 nm, ideally every 25 nm).

[0119] These measurements can be reproduced with different eccentricities within the field of view. The results will be taken into account to produce a lens with gradient filtering function. The spatial transmittance of the lens can be defined as a variation of the spatial transmittance of the ocular medium.

[0120] For aesthetic purposes, a wearer may prefer a grey lens. Color balancing can be performed to improve the aesthetics of the lens while maintaining the spectral transmittance distribution determined using the claimed method.

[0121] To produce lenses with the specified filters, dyes with specific absorption in the red of the spectrum can be used, thereby maintaining the best possible transmittance below 550 nm (the blue range of the spectrum). Furthermore, the dyes used preferably have low haze and improved selectivity, as well as compatibility with the lens manufacturing process. Low haze is less than 1%, preferably less than 0.5%. Process compatibility means no degradation after thermal curing or processing (molding / tinting). Selectivity refers to an absorption peak (λmax) in the visible range of 650 to 680 nm, with a Full Width Half Mass (FWHM) > 75 nm.

[0122] In certain embodiments, the method according to the present invention is computer-implemented. That is, the computer program product comprises one or more sequences of instructions accessible to a processor and, when executed by the processor, causes the processor to perform the steps of the method for determining the spectral transmittance of the ocular medium of at least one eye of the user and determining at least one filter as described above.

[0123] The sequence(s) of instructions may be stored in one or more computer-readable storage media (including a predetermined location in the cloud).

[0124] While representative methods and apparatus have been described in detail herein, those skilled in the art will recognize that various substitutions and modifications may be made without departing from the scope described and defined by the appended claims.

Claims

1. A method for determining at least one filter for a visual device intended to be placed in front of a user's eyes, said at least one filter being capable of improving the user's visual comfort and / or visual performance, said method comprising the following steps: - determining the spectral transmittance of the ocular medium of at least one eye of the user based on measurements of the user or based on the age of the user; as well as - determining at least one filter based on the determined spectral transmittance of the user's ocular medium, such that the filter has a spectral transmittance distribution comprising o a first portion having a maximum transmittance value between 380 nm and a predetermined wavelength threshold, said predetermined wavelength threshold being between 425 and 525 nm, o A second portion of reduced transmittance values ​​between said predetermined wavelength threshold and 670 nm.

2. The method according to claim 1, wherein The maximum transmittance value is between 70% and 100%.

3. The method according to claim 1 or 2, wherein: The second portion decreases continuously from the maximum transmittance value to a minimum target transmittance value corresponding to a wavelength between 630 nm and 670 nm. 4 . The method of claim 3 , further comprising the step of determining a target transmittance value, the filter being determined so that the minimum target transmittance value is between −10% and +10% of the target transmittance value.

5. The method according to claim 1 or 2, wherein: The spectral transmittance of the user's ocular media is determined based on a spectral transmittance test.

6. The method according to claim 5, wherein: The spectral transmittance test includes the step of measuring the absolute scotopic threshold.

7. The method according to claim 5, wherein: The spectral transmittance test includes the step of measuring absolute light discomfort.

8. The method according to claim 5, wherein The spectral transmittance test includes the step of equalizing photopic brightness.

9. The method according to claim 1 or 2, wherein: The user's ocular medium is the lens.

10. The method according to claim 1 or 2, wherein: The spectral transmittance of the filter is calculated as follows: T(λ,age)=T Ref (λ) / T crystalline (λ,age) Among them, T Ref (λ)=T lens (l)*T crystallineXyearsold (l), Among them, T Ref (λ) is the spectral transmittance of the filter to be determined, T lens (λ) is the spectral transmittance of a given lens, T crystallineXyearsold (λ) is the reference spectral transmittance of the ocular medium of a reference wearer of x years old, λ is the wavelength.

11. A filter for a visual device intended to be placed in front of a user's eyes, wherein: The spectral transmittance of the filter is calculated based on the spectral transmittance of the user's ocular medium, so that the filter has a spectral transmittance distribution, the spectral transmittance distribution including: o a first portion having a maximum transmittance value between 380 nm and a predetermined wavelength threshold, said predetermined wavelength threshold being between 425 and 525 nm, o a second portion having a reduced transmittance value between said predetermined wavelength threshold and 670 nm, Therein, the spectral transmittance of the ocular medium of at least one eye of the user is based on a measurement of the user or on the age of the user.

12. A set of filters for a visual device intended to be placed in front of a user's eyes, wherein: Each filter in the set has a spectral transmittance based on the spectral transmittance of an ocular medium of a user of a different age, the spectral transmittance of each filter in the set of filters being calculated such that the filter has a spectral transmittance distribution comprising: o a first portion having a maximum transmittance value between 380 nm and a predetermined wavelength threshold, said predetermined wavelength threshold being between 425 and 525 nm, o a second portion having a reduced transmittance value between said predetermined wavelength threshold and 670 nm, Therein, the spectral transmittance of the ocular medium of at least one eye of the user is based on a measurement of the user or on the age of the user.

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