Method and ophthalmic element for stimulating a non-visual physiological effect

Abstract

A computed factor allows quantifying the efficiency of a light filter to stimulate a non-visual physiological effect which is responsive to light entering into a subject's eye. The efficiency factor is based on a spectral light transmittance of the filter over the wavelength visible range, on a spectral sensitivity profile of the non-visual physiological effect, and on a spectral distribution of the light which enters into the subject's eye without using the filter. Such efficiency factor is useful in particular for an ophthalmic element designed for stimulating a non-visual physiological effect which is based on melanopsin light-absorption.

Claims

1. A transparent ophthalmic element for stimulating at least one non-visual physiological effect, the element having a spectral filtering effect according to a spectral light transmittance T expressed as percentage values over the wavelength visible range [380 nm -780 nm], wherein: the element has an efficiency factor F that is greater than or equal to 30, said efficiency factor F is represented by the following equation: $F=100-\frac{{\int }_{380\mathrm{nm}}^{780\mathrm{nm}}E\left(\lambda \right).Math.M\left(\lambda \right).Math.T\left(\lambda \right).Math.d\lambda }{{\int }_{380\mathrm{nm}}^{780\mathrm{nm}}E\left(\lambda \right).Math.M\left(\lambda \right).Math.d\lambda }$ wherein: λ, is light wavelength within the visible range; T(λ) is the transmittance value of the element at wavelength λ; M(λ) is a value of the spectral sensitivity profile M of the non-visual physiological effect at wavelength λ; and E(λ) is a value of the spectral distribution E of the light intensity at wavelength λ, corresponding to at least part of the light which enters into the wearer's eye without using the filter; wherein the efficiency factor value is greater than or equal to K−b*, K being a coefficient greater than or equal to 1, and b* being a CIE Lab colorimetric parameter for the light transmitted through the element; wherein the at least one non-visual physiological effect is stimulated by reducing a light amount which enters the wearer's eye and which is comprised within a spectral sensitivity range of melanopsin, and the spectral sensitivity profile M is a spectral sensitivity profile of melanopsin; and wherein the ophthalmic element comprises a transparent matrix material, and also comprises a first absorber which is distributed within the transparent matrix material, wherein said first absorber has a first light-absorption maximum between 460 nm and 510 nm for a wavelength value of a light impinging on the ophthalmic element.

2. The transparent ophthalmic element according to claim 1, wherein the spectral intensity distribution E relates to daylight, an incandescent light source, an electroluminescent diode, a display backlight or a fluorescent light source.

3. The transparent ophthalmic element according to claim 1, wherein coefficient K equals 1.2 and b* is less than 84.

4. The transparent ophthalmic element according to claim 1, wherein the transmittance T of the element has a profile with at least two local-minimum zones and at least one local-maximum zone within the wavelength visible range, a first one of said local-minimum zones containing a local-minimum wavelength located within the melanopsin absorption wavelength range, and a second one of said local-minimum zones containing another local-minimum wavelength located outside the melanopsin absorption wavelength range, and the local-maximum zone being intermediate in wavelength between said first and second local-minimum zones.

5. The transparent ophthalmic element according to claim 4, wherein the second local-minimum zone overlaps at least part of a melanopsin regeneration spectral range, light with wavelength contained within said melanopsin regeneration spectral range stimulating a regeneration of melanopsin molecules after said melanopsin molecules have absorbed light with wavelength contained in the melanopsin absorption wavelength range.

6. The transparent ophthalmic element according to claim 1, wherein the first absorber has a first light-absorption maximum between 487 nm and 497 nm for the light wavelength with a full width at half maximum of less than 40 nm, when said first absorber is dissolved in methylene chloride.

7. The transparent ophthalmic element according to claim 1, further comprising a second absorber which is also distributed within the transparent matrix material, wherein said second absorber has a second light-absorption maximum between 550 nm and 630 nm for the wavelength value of the light impinging on the ophthalmic element.

8. The transparent ophthalmic element according to claim 7, wherein the second absorber has a second light-absorption maximum between 579 nm and 589 nm for light wavelength with a full width at half maximum of less than 30 nm, when said second absorber is dissolved in methylene chloride.

9. The transparent ophthalmic element according to claim 7, wherein the first absorber and the second absorber are each provided in an amount such that the efficiency factor F of the ophthalmic element is greater than 30 and b* is less than 10.

10. The transparent ophthalmic element according to claim 1, wherein the element remains in one of at least two states, each state corresponding to one value for the efficiency factor F which is distinct from the value relating to the other state, and wherein the element switches between both states.

11. The transparent ophthalmic element according to claim 10, further comprising a controller real-time controlling the current state of the element, and controlling a switching to the other state based on at least one of the following criteria: at least one feature of the light currently reaching the element; a history of at least one feature for the light which has reached the element during a time period; an age of the wearer of the element; behaviour data and/or lifestyle data of the wearer of the element; and at least one control action entered by the wearer of the element.

12. The transparent ophthalmic element according to claim 1, forming at least part of an eyeglass or at least part of an ophthalmic patch to be fitted on an eyeglass.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1 to 3 are spectral diagrams for several filters designed by implementing the invention; and

(2) FIG. 4 is a cross-section of an eyeglass in accordance with the invention.

(3) For clarity sake, element sizes which appear in FIG. 4 do not correspond to actual dimensions or dimension ratios.

DETAILED DESCRIPTION OF THE INVENTION

(4) Although the invention can be applied to any non-visual physiological effect, it is now described for such effects which are stimulated by melanopsin as an example.

(5) Melanopsin is the third photoreceptor in human retina, recently discovered (˜year 2000). This is a natural photopigment, contained in only 1 to 3% of retinal ganglion cells, which generates signals intended to non-visual areas of brain. These signals participate in particular to regulating various non-visual biological functions, including mood, body temperature, pupillary reflex, hormonal behaviours and also features of the biological time of a human being. It is also well-known that sleeping is improved when melatonin hormone is produced, but melatonin production is inhibited by light-stimulation of melanopsin. In some situations, it may be desired to inhibit at least some of the melanopsin-based effects for improving the behaviour of a subject. This may be useful for subjects having irregular or upset rhythms, for example due to jet lag, shift work or prolonged light exposure to self-luminous devices in the evening.

(6) Light absorption for melanopsin occurs for light having wavelengths comprised in the range from 410 nm (nanometer) to 580 nm, from 450 nm to 530 nm for half-maximum sensitivity, and from 460 nm to 510 nm for highest sensitivity, as represented in the diagram of claim 1. In this diagram, x-axis represents wavelength values A over the visible range from 380 nm to 780 nm, and y-axis represents the spectral absorption values A.sub.m(λ) of melanopsin expressed as percent values of incident light. Therefore, light with wavelengths within this absorption range stimulates melanopsin-based non-visual physiological effects. Exact values of A.sub.m(λ) are available in scientific literature.

(7) To this purpose, goggles and spectacles have been proposed which have a light-filtering effect adapted for melanopsin sensitivity spectrum. Such known goggles and spectacles comprise a long-pass absorptive filter with cut-off wavelength from the range 510 nm to 530 nm. Such know goggles and spectacles strongly affect the perception of colour and the scotopic vision, and they are seen as aesthetically displeasing. Indeed, such goggles appear yellow-orange. They have a very high b* value indicating an absence of colour neutrality. In addition, these known goggles and spectacles do not integrate any intermediate efficiency or modulating effect.

(8) Furthermore, it is difficult to determine the efficiencies of several of these devices with respect to melanopsin-based physiological effects since commonly used parameters such as mean light transmission or colorimetric parameters do not match the melanopsin absorption range. For addressing this issue, the present invention introduces the following efficiency factor F:

(9) $\begin{array}{cc}F=100-\frac{{\int }_{380\mathrm{nm}}^{780\mathrm{nm}}E\left(\lambda \right).Math.M\left(\lambda \right).Math.T\left(\lambda \right).Math.d\lambda }{{\int }_{380\mathrm{nm}}^{780\mathrm{nm}}E\left(\lambda \right).Math.M\left(\lambda \right).Math.d\lambda }& \left(1\right)\end{array}$
where E(λ) is the value at wavelength λ of the light intensity distribution E corresponding to incident light entering into the wearer's eye when no goggles or spectacles is worn, expressed in unit W.Math.m.sup.−2.Math.nm.sup.−1, M(λ) is the value at wavelength λ of the spectral sensitivity profile M of the non-visual physiological effect, expressed as a multiplicative factor applied to the light intensity distribution E, and T(λ) is the value at wavelength λ of the light transmission of the goggles or spectacles, expressed as a percentage value. In the particular case of a melanopsin-based physiological effect, the spectral absorption values A.sub.m(λ) of melanopsin are to be used for the values M(λ), possibly expressed as percentage values. The efficiency factor F is then suitable for quantifying the efficiency of the goggles or spectacles for blocking the light components having wavelength values within the absorption range of melanopsin. F equaling 100 means that all light within the absorption range of melanopsin is filtered out by the goggles or spectacles, and F equaling 0 means that the goggles or spectacles have no influence on the melanopsin-based physiological effects. Diagram of FIG. 1 also shows four filter profiles denoted T.sub.F30, T.sub.F50, T.sub.F80 and T.sub.F90 which correspond respectively to values of about 30, about 50, about 80 and about 90 for the efficiency factor F. Obviously, the invention efficiency factor F may be applied to vision devices other than goggles and spectacles, used only as examples in the present description.

(10) But although the filter profiles T.sub.F30, T.sub.F50 and T.sub.F80 show some efficiency of the related vision devices with respect to the melanopsin-based physiological effects, these devices exhibit intense color in transmission, such that color rendering may be altered for the wearers of these devices. Because the long pass absorptive filters corresponding to the profiles T.sub.F30, T.sub.F50 and T.sub.F80 are designed to reduce or block light when wavelength is below 527 nm, the devices appear yellow or orange in transmission. This transmission colour can be quantified with the well-known b* colorimetric parameter, for example measured or computed for illuminant A or for one illuminant from the series D and F as defined in CIE standard, for example illuminant D65. Practically, designing filters with high values for the efficiency factor F with respect to melanopsin-based physiological effects may lead to high values for b* colorimetric parameter, which are detrimental for colour rendering.

(11) Several ways may be implemented for alleviating this problem of colour rendering, which are now indicated and may be implemented separately or in combination of at least two of them: modifying the filter profiles T.sub.F30, T.sub.F50 and T.sub.F80 shown in FIG. 1 so as to obtain new profiles with reduced light transmission values in the melanopsin absorption wavelength range, namely between 460 nm and 510 nm, but with increased light transmission values for at least some wavelength values below 460 nm and at least some other wavelength values above 510 nm. Put another way, the profile may advantageously exhibit a local-minimum zone corresponding to the melanopsin absorption wavelength range, but also two local-maximum zones located below 460 nm and above 510 nm respectively. In this way, the local-maximum zone located below 460 nm tends to lower the value of the b* colorimetric parameter by re-introducing violet light components in the light transmitted by the vision device to the wearer's eye. This may be called a “selectivity effect”. Diagram of FIG. 2 is similar to that of FIG. 1 with the melanopsin absorption profile again, but where the additional profiles labelled T′F.sub.30, T′F.sub.50 and T′F.sub.80 corresponds to the second profile type currently described. The profiles T′F.sub.30, T′F.sub.50 and T′F.sub.80 correspond substantially to the same values for the efficiency factor F as the profiles T.sub.F30, T.sub.F50 and T.sub.F80, respectively, since T.sub.F30 and T′F.sub.30 have similar values over the melanopsin absorption range as shown in FIGS. 1 and 2, and also for T.sub.F50 and T.sub.F50, and also again for T.sub.F80 and T′F.sub.80. another way for improving colour rendering of the vision devices without decreasing the efficiency factor values consists in designing the transmission profile of the filter so that it exhibits another local-minimum zone in addition to a first local-minimum zone which is superposed to the melanopsin absorption range. Both local-minimum zones are then separated by a local-maximum zone which may be located just above 520 nm. The second local-minimum zone, above the melanopsin absorption range and the local-maximum zone reduces the contribution of the high wavelength values in the b* colorimetric parameter, thereby reducing the value of this latter. This may be called a “colour-balancing effect”. Diagram of FIG. 3 is similar again to that of FIG. 1, but where the additional profiles labelled T″F.sub.30, T″F.sub.50 and T″F.sub.ao corresponds to the third profile type currently described. The profiles T″.sub.30, T″.sub.50 and T″.sub.F80 also correspond substantially to the same values for the efficiency factor F as the profiles T.sub.F30, T.sub.F50 and T.sub.F80, respectively, for the same reason as already mentioned, when, using again the same spectral absorption profile of melanopsin. Actually, the filter profiles shown in FIG. 3 are combinations of selectivity and colour balancing profile types (second and third profile types). It combines a local-maximum zone below 460 nm, a local-minimum zone in the melanopsin absorption range between 460 nm and 510 nm, another local-maximum zone between 510 nm and 550 nm, and another local-minimum zone between 550 nm and 630 nm. selecting a trade-off between stimulating efficiently the melanopsin-based physiological effects and limiting the b* parameter value. Such trade-off may be expressed as the efficiency factor F being higher than or equal to K×b*, where K is a coefficient higher than or equal to 1. Positive feedbacks have been received from wearers using devices with K-coefficient equalling 1.2 and b* being less than 84. Maintaining the trade-off condition of F less than or equal to 1.2×b* with lower values for the b* colorimetric parameter leads to improved vision devices. Preferably, the value of a* colorimetric parameter is positive or zero, for the same illuminant as used for b*.

(12) A special requirement for colour rendering through each filter may be expressed in terms of Q-signal values for automotive driving applications. Known Q-signal requirements may be complied with by the filter, for ensuring that base colours can be identified clearly by a subject through the filter. Each filter in accordance with the invention meets the Q-signal value limitations better than prior art long pass filters profile types which are yellow-orange.

(13) Actually, melanopsin has dual light sensitivity: it absorbs light in the wavelength range 460 nm-510 nm and consequently stimulates non-visual physiological effects as explained before, but also absorbs at about 560 nm-600 nm, mostly 580 nm, for melanopsin regeneration. Indeed, when melanopsin molecules absorb light with wavelength between 460 nm and 510 nm, they are converted from a first molecule state to a second molecule state which is no longer sensitive to light of between 460 nm and 510 nm. But they are then sensitive to light with wavelength comprised between 550 nm and 630 nm which causes them to transform back into the first state. Thus, melanopsin can be regenerated with light in this latter wavelength range. Then, a completed way to inhibit the non-visual physiological effects which are melanopsin-based consists in inhibiting melanopsin regeneration in addition to reducing or suppressing exposure to light which produces stimulation of the non-visual physiological effects. This may be obtained with filter transmission profiles of the third type as disclosed before, by locating the second local-minimum zone at the melanopsin regeneration wavelength range, namely superposing the second local-minimum zone of a filter transmission profile of the third type with wavelength range 550 nm-630 nm. Profiles in FIG. 3 correspond to such implementation. This is called “dual-melanopsin effect” by the inventors.

(14) For rendering in an improved manner such dual-melanopsin effect, the spectral sensitivity profile M(λ) to be used for computing the efficiency factor F may be a combination of the respective spectral sensitivity profiles of both molecular states of melanopsin. When linear combination is used, M(λ)=α.sub.1.Math.M.sub.1(λ)+α.sub.2.Math.M.sub.2(λ), where M.sub.1(λ) is the spectral sensitivity profile of a first one of the molecular states of melanopsin, M.sub.2(λ) is the spectral sensitivity profile of a second one of these molecular states of melanopsin, and α.sub.1 and α.sub.2 are weighting factors. M.sub.1(λ) and M.sub.2(λ) may be the respective spectral absorption profiles of both melanopsin states, which are known from scientific literature. The spectral absorption profile M.sub.1(λ) peaks between 460 nm and 510 nm, and the spectral absorption profile M.sub.2(λ) peaks between 550 nm and 630 nm. For example, the weighting factors α.sub.1 and α.sub.2 may both equal 0.5, or α.sub.1 may equal 0.75 and α.sub.2 may equal 0.25 as another example.

(15) The light intensity distribution E may be that of any illuminant known in the art. It may also be spectral intensity distribution of any actual light source, for example which is to be used by the wearer of the invention ophthalmic element, including daylight, an incandescent light source, an electroluminescent diode, a display backlight or a fluorescent source. But the light intensity distribution may also be a combination of light amounts originating from several light sources, each one corresponding to a separate light intensity distribution E.sub.i, i being a positive integer from 1 to N, where N is the number of sources. In such case, a separate efficiency factor F.sub.i may be computed for one same filter or ophthalmic element but for each light source i, according to the following formula (1′):

(16) $\begin{array}{cc}{F}_i=100-\frac{{\int }_{380\mathrm{nm}}^{780\mathrm{nm}}{E}_i\left(\lambda \right).Math.M\left(\lambda \right).Math.T\left(\lambda \right).Math.d\lambda }{{\int }_{380\mathrm{nm}}^{780\mathrm{nm}}{E}_i\left(\lambda \right).Math.M\left(\lambda \right).Math.d\lambda }& \left(1^{\prime }\right)\end{array}$
Then, a combined efficiency factor F may be calculated from these separate efficiency factors F.sub.i by linear combination according to formula (2):

(17) $\begin{array}{cc}F=\frac{1}{N}\underset{i=1}{\overset{i=N}{.Math.}}{w}_i.Math.F_i& \left(2\right)\end{array}$
where w.sub.i is a weighting factor for light source i. Such averaged efficiency factor F as resulting from formula (2) makes it possible to fit an actual light composition experienced by a subject at one time, or also to fit a light composition which varies between several exposure periods. For the first case, when the actual light originates simultaneously from N light sources, each weighting factor w.sub.i may correspond to the light intensity of the light source i integrated over the visible range, divided by the total light intensity summed over the N light sources, also integrated over the visible range. For the second case where the subject is exposed to different light sources during respective durations, each weighting factor w.sub.i may correspond to the fraction of exposure duration for light source i, divided by the sum of the exposure durations for all N light sources. Each light source i for these multiple exposure situations may be daylight, an incandescent light source, an electroluminescent diode, a display backlight or a fluorescent source independently from the other light sources.

(18) Once the above rules for designing a filter dedicated for stimulating a non-visual physiological effect have been provided, producing such filter comprises selecting appropriately parameters or components of the filter, including die molecules, filter thickness and die concentrations for an absorption-based filter, or including a light-wave propagation medium, thickness of the light-wave propagation medium, interface forming materials or interface layers for a reflection-based filter. Possibly, several filters of various types may be combined by lamination on one another for obtaining a resulting filter profile which matches a target profile designed according to the invention.

(19) Such filter may be self-supported, in particular for a vision device such as eyeglasses, goggles, mask, protection sheet, helmet window, etc. Possibly, it may also be laminated between protective transparent films for reducing scratches and allowing easy cleaning.

(20) Alternatively, the filter may be laminated on a transparent substrate for producing the desired stimulation of the non-visual physiological effect in addition to visual functions provided by the transparent substrate. In particular, the transparent substrate may be an eyeglass lens for ophthalmic applications. Such eyeglass lens may be an ametropia-correcting lens, or a solar protection lens, or a base eyeglass lens dedicated to any other purpose. Possibly, the solar protection function may be provided not only by the substrate, but may result from the combination of the substrate with the filter, or may be provided by the filter only. Also possibly, the filter may form an ophthalmic patch to be applied on an eyeglass.

(21) If several filters are combined, some of them may be laminated on a first face of the substrate, and the other filters may be laminated on a second face of the substrate, opposite the first face. In such case, the filters of both faces may be similar or different.

(22) Each filter may be laminated on a substrate-forming lens, this substrate-forming lens possibly bearing functional layers, by lamination process as taught in EP 1 866 144.

(23) FIG. 4 illustrates an eyeglass obtained by laminating a filter designed according to the invention on a substrate-forming ophthalmic lens. Reference numbers 1 and 2 denote the ophthalmic lens and the filter, respectively.

(24) More specifically, eyeglasses which can be used as substrates may be lenses aimed at correcting the wearer's vision, protecting the wearer's eyes and/or enhancing the wearer's vision. Non-limiting examples of suitable ophthalmic lenses include non-corrective (also called plano or afocal lenses) and corrective lenses, including single vision or multi-vision lenses like bifocal, trifocal or progressive lenses, which may be either segmented or non-segmented. Such ophthalmic lenses may be semi-finished lenses or finished lenses, and in general any type of ophthalmic substrate used in ophthalmic industry, for eyeglasses but also contact lenses. It may be out of mineral glass or organic material.

(25) The organic material for the substrate-forming lens may be a thermoplastic material, selected from polyamides, polyimides, polysulfones, polycarbonates, polyurethanes and copolymers thereof, poly(ethylene terephtalate) and polymethylmethacrylate (PMMA), for instance. As used herein, polycarbonate (PC) is intended to mean either homopolycarbonates or copolycarbonates or block-copolycarbonates. (Co)polymer is intended to mean a copolymer or a polymer, and (meth)acrylate is intended to mean an acrylate or a methacrylate.

(26) The organic material for the substrate-forming lens may be also a thermoset material, selected from cycloolefin copolymers such as ethylene/norbornene or ethylene/cyclopentadiene copolymers, homo- and copolymers of allyl carbonates of linear or branched aliphatic or aromatic polyols, such as homopolymers of diethylene glycol bis(allyl carbonate) (CR 39®), homo- and copolymers of (meth)acrylic acid and esters thereof, which may be derived from bisphenol A, polymers and copolymers of thio(meth)acrylic acid and esters thereof, polymers and copolymers of allyl esters which may be derived from Bisphenol A or phtalic acids and allyl aromatics such as styrene, polymers and copolymers of urethane and thiourethane, and polymers and copolymers of sulphide, disulfide and episulfide, and combinations thereof, for instance.

(27) Particularly recommended substrate-forming lenses include those substrates obtained through (co)polymerization of the diethyleneglycol bis-allyl-carbonate, marketed for example under the trade name CR-39® by the PPG Industries company (ORMA® lenses, ESSILOR), or polythiourethanes/polysulfides, marketed for instance under MR series by Mitsui, or allylic and (meth)acrylic copolymers, having a refractive index between 1.54 and 1.58. Still another organic material which is suitable for the substrate-forming lens is that marketed under trade name Trivex® by PPG Industries company, and which is obtained from nitrogen-enriched urethane-based pre-polymer.

(28) All the materials cited here-above for the substrate-forming lens when the invention filter is supported by such substrate-forming lens, may also be used as filter matrix materials for self-supported filters. In these latter cases, dies molecules may be distributed within the matrix material.

(29) When the filter is supported by a substrate-forming lens, the matrix material of the filter may also be a varnish, or may be a polyurethane-based layer as those described in U.S. Pat. Nos. 6,187,444 and 7,258,437.

(30) A filter which implements the invention may have a single layer or multilayer structure. It may be deposited directly onto the substrate-forming lens. In some applications, the substrate-forming lens is coated with one or more functional coatings prior to depositing the filter. In other applications, one or more functional coatings are coated on the filter. These functional coatings commonly used in optics may be, without limitation, an impact-resistant primer layer, an abrasion-resistant coating and/or a scratch-resistant coating, a polarizing coating, a photochromic coating or a tinted coating. Coatings capable of modifying the surface properties, such as hydrophobic and/or oleophobic coatings (antifouling, antistain, antifog), may also be deposited onto the exposed surface of the last functional coating along a direction away from the substrate.

(31) In particular, coatings may be used in combination with the filter for aesthetic matters, in particular for selecting the colour and intensity of the light-reflection produced by the ophthalmic element from light originating from the wearer's environment, including daylight from sky.

(32) Filters in accordance with the invention, and which are directed to melanopsin-based physiological effects have been produced using one or two absorbers produced by Exciton, Inc. in Dayton, Ohio, US. The first absorber is referred to as P491 and has an absorbance peak at wavelength value of 492+/−1 nm in methylene chloride (CH.sub.2Cl.sub.2), corresponding to the absorbance range of melanopsin. Full width at half maximum for the P491 absorbance peak is about 32 nm. The second absorber is referred to as ABS 584L and has an absorbance peak at wavelength value of 584+/−2 nm in methylene chloride, corresponding to the regeneration range of melanopsin. Full width at half maximum for the ABS 584L absorbance peak is about 22 nm.

(33) Three filters have been produced using the following absorber amounts incorporated in one clear substrate material for forming ophthalmic lenses: filter F1: 1.2 mg (milligram) of absorber Exciton P491 per 100 g (gram) of clear substrate material, without any Exciton ABS 584L filter F2: 1.2 mg (milligram) of absorber Exciton P491 and 0.9 mg of absorber Exciton ABS 584L per 100 g (gram) of clear substrate material filter F3: 2.4 mg (milligram) of absorber Exciton P491 per 100 g (gram) of clear substrate material, without any Exciton ABS 584L

(34) For comparison, a filter FO is comprised on the clear substrate material without any absorber. All four filters have one and same thickness value for the measured or assessed features which are displayed in the following table:

(35) TABLE-US-00001 TBV(%) TBT(%) TA(%) Tv(%) b* F x(%) y(%) F1 71 51 97 90 17 27 28 NS F2 73 52 58 77 6 32 62 50 F3 66 34 95 87 23 35 78 50 F0 95 99 98 98 1.4 1 — — TBV: transmission value over the wavelength range 415-455 nm (blue-violet color) TBT: transmission value over the wavelength range 460-510 nm (blue-turquoise colour) TA: transmission value over the wavelength range 570-600 nm (amber colour) Tv: visual transparency over the range 380-780 nm for human eye b*: colorimetric parameter of CIE Lab model, positive b*-values denoting yellowish hue and negative b*-values denoting bluish hue F: the invention efficiency factor, computed using the spectral absorption profiles M.sub.1(λ) and M.sub.2(λ) of both molecular states of melanopsin, M.sub.1(λ) peaking between 460 nm and 510 nm, and M.sub.2(λ) peaking between 550 nm and 630 nm, and the following weighting factors for the linear combination: α.sub.1 = 0.75 and α.sub.2 = 0.25 x: the increase in melatonin production with respect to the filter F0 y: the decrease in sleep latency with respect to the filter F0

(36) In this table, the column features are the following ones when calculated for the illuminant D65 of CIE:

(37) The three filters F1 to F3 implement the selectivity effect previously described, and the higher value of the efficiency factor for the filter F3 with respect to the filter F1 is due to the higher concentration of the absorber Exciton P491. As another consequence of the high absorber concentration, the b*-value of the filter F3 is higher than that of the filter F1.

(38) The filter F2 recovers a low value for the colorimetric parameter b*, thanks to the colour-balancing effect which is provided by the absorber Exciton ABS 584L with respect to the absorber Exciton P491. It also appears that the physiological effectiveness of the absorber Exciton ABS 584L in the melanopsin regeneration range is substantially similar to that of doubling the amount of the absorber Exciton P491.

(39) In most preferred implementations, the ophthalmic element which is provided with light-filtering features according to the invention may be a smart element. In the frame of the present description, smart ophthalmic element denotes an ophthalmic element which is capable of switching between two optical states and maintaining each state, each state corresponding to a value for the element efficiency factor F which is distinct from the value relating to the other state. Switching of the element may be controlled or triggered by various control parameters, such as the activity, time in the day, ambient light intensity, etc.

(40) But preferably, such smart ophthalmic element implementing the invention is electrically controlled. Light filters which can be varied in filtering capabilities are well known, for example based on cholesteric liquid crystals. A controller may be combined with the smart ophthalmic element for real-time controlling the current state of the element, and also controlling a switching to the other state. Criteria for triggering a switching may include: at least one feature of the light currently reaching the ophthalmic element, for example the light intensity. Possibly, state with minimum value for the efficiency factor may be controlled below a first level for the ambient light intensity, then an increasing value for the efficiency factor may be controlled when ambient light intensity increases, until saturation occurs at a second level for the ambient light intensity; a history related to a feature for the light which has reached the ophthalmic element during a time period. For example, one may use a time-integrated light amount which is comprised in the melanopsin absorption range, when the element is designed for efficiency with respect to melanopsin-based non-visual physiological effects; the age of the wearer of the element, since it is known that elder people are less sensitive to light components in the blue range. Then it may be suitable to adapt the filtering efficiency of the ophthalmic element so as to reduce blue light attenuation for elder people; behaviour data and/or lifestyle data of the wearer of the element. For example, switching of the ophthalmic element into a state for improving sleeping quality may be controlled at desired or predetermined hours with respect to activity or schedule of the subject; a control action which is entered by the wearer of the ophthalmic element. An input button or tactile area may be provided on the element for switching controlled by the wearer; and colour appearance preferred by the wearer. As an example, a wearer may appreciate warm colours, meaning that it is pleasant for him to have visual perception of his environment with low level blue light components. Then it is possible for him to access higher values for the efficiency factor F, for example for an ophthalmic element which is designed for stimulating melanopsin-based non-visual physiological effects.

(41) Although the invention has been described in more details for melanopsin-based non-visual physiological effects, with colorimetric issues entailed by the location of the melanopsin absorption range within the visible range, it is clear that the efficiency factor F as introduced can be applied to any other non-visual physiological effect.

(42) Also the invention has been described mainly for spectacle eyeglasses, including ametropia-correcting or solar protection eyeglasses, but it can be implemented for any other ophthalmic element, including contact lenses, goggles, eye protection masks, helmet windows, etc.