Patent Description:
It has been known for several years that light within the visible range plays a role with respect to non-visual physiological effects for human beings. In particular, part of the visible light participates to regulating circadian rhythms of a subject.

Then, helping to maintain or adapt circadian rhythms may be beneficial for a subject experiencing jet lag or shift work with irregular work periods and rest periods, or sleep troubles. To this purpose, <CIT> proposes method and device for maintaining circadian rhythm in a subject by selectively blocking or reducing retinal exposure to light of wavelengths less than <NUM> (nanometer) during night time. These methods and devices are based on the discovery that the sleep hormone melatonin is affected by light: melatonin secretion is said to be suppressed by nocturnal exposure to light with wavelength between <NUM> and <NUM>.

To the same purpose, <CIT> proposes method and device for inhibiting melatonin suppression by light, by blocking more than <NUM> percent of incident wavelengths of light having a wavelength range less than, at or about <NUM>, while transmitting more than <NUM>% of non-blocked wavelengths of light. In this way, light-induced suppression of melatonin production can be inhibited when the method and device of <CIT> are implemented at night. In addition, <CIT> discloses that the device used may implement a filter, and may be a user-operable lens, possibly incorporated in an eyewear such as spectacles, goggles, contact lenses and safety glasses. Another document related to the optimization of light for therapeutic effects is <CIT>.

Starting from this situation, one object of the present invention consists in.

providing a device intended for stimulating a non-visual physiological effect, with a quantified assessment of its efficiency.

For meeting at least one of these objects or others, the present invention proposes a method for producing an ophthalmic element as recited in claim <NUM>.

Dependent claims state possibilities for carrying out the method.

In the frame of the invention, the phrase "stimulating at least one non-visual physiological effect" encompasses any modification of the non-visual physiological effect which is produced by the filter, including triggering, activating, enhancing, reducing, inhibiting and blocking the non-visual physiological effect.

The efficiency factor takes into account the spectral features of the filter, and also the spectral features of the non-visual physiological effect and those of the light. Thus, the efficiency factor is a true assessment of the filter efficiency with respect to the non-visual physiological effect in at least one specific light environment.

These and other features of the invention will be now described with reference to the appended figures, which relate to preferred but not-limiting embodiments of the invention.

For clarity sake, element sizes which appear in <FIG> do not correspond to actual dimensions or dimension ratios.

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.

Melanopsin is the third photoreceptor in human retina, recently discovered (~ year <NUM>). This is a natural photopigment, contained in only <NUM> to <NUM>% 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.

Light absorption for melanopsin occurs for light having wavelengths comprised in the range from <NUM> (nanometer) to <NUM>, from <NUM> to <NUM> for half-maximum sensitivity, and from <NUM> to <NUM> for highest sensitivity, as represented in the diagram of claim <NUM>. In this diagram, x-axis represents wavelength values λ over the visible range from <NUM> to <NUM>, and y-axis represents the spectral absorption values Am(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 Am(λ) are available in scientific literature.

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 cutoff wavelength from the range <NUM> to <NUM>. 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.

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 a method for producing an ophthalmic element. This method is defined by the following efficiency factor F: <MAT> 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·m-<NUM>·nm-<NUM>, 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 Am(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 <NUM> means that all light within the absorption range of melanopsin is filtered out by the goggles or spectacles, and F equaling <NUM> means that the goggles or spectacles have no influence on the melanopsin-based physiological effects. Diagram of <FIG> also shows four filter profiles denoted TF30, TF50, TF80 and TF90 which correspond respectively to values of about <NUM>, about <NUM>, about <NUM> and about <NUM> for the efficiency factor F.

But although the filter profiles TF30, TF50 and TF80 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 TF30, TF50 and TF80 are designed to reduce or block light when wavelength is below <NUM>, the devices appear yellow or orange in transmission. This transmission colour is quantified with the well-known b* colorimetric parameter, in examples not covered by the invention measured or computed for illuminant A or for one illuminant from the series D and F as defined in CIE standard, and according to the invention measured or computed for 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.

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:.

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.

Actually, melanopsin has dual light sensitivity: it absorbs light in the wavelength range <NUM> - <NUM> and consequently stimulates non-visual physiological effects as explained before, but also absorbs at about <NUM> - <NUM>, mostly <NUM>, for melanopsin regeneration. Indeed, when melanopsin molecules absorb light with wavelength between <NUM> and <NUM>, they are converted from a first molecule state to a second molecule state which is no longer sensitive to light of between <NUM> and <NUM>. But they are then sensitive to light with wavelength comprised between <NUM> and <NUM> 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 <NUM> - <NUM>. Profiles in <FIG> correspond to such implementation. This is called "dual-melanopsin effect" by the inventors.

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<NUM>·M<NUM>(λ) + α<NUM>·M<NUM>(λ), where M<NUM>(λ) is the spectral sensitivity profile of a first one of the molecular states of melanopsin, M<NUM>(λ) is the spectral sensitivity profile of a second one of these molecular states of melanopsin, and α<NUM> and α<NUM> are weighting factors. M<NUM>(λ) and M<NUM>(λ) may be the respective spectral absorption profiles of both melanopsin states, which are known from scientific literature. The spectral absorption profile M<NUM>(λ) peaks between <NUM> and <NUM>, and the spectral absorption profile M<NUM>(λ) peaks between <NUM> and <NUM>. For example, the weighting factors α<NUM> and α<NUM> may both equal <NUM>, or α<NUM> may equal <NUM> and α<NUM> may equal <NUM> as another example.

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 Ei, i being a positive integer from <NUM> to N, where N is the number of sources. In such case, a separate efficiency factor Fi may be computed for one same filter or ophthalmic element but for each light source i, according to the following formula (<NUM>'): <MAT> Then, a combined efficiency factor F may be calculated from these separate efficiency factors Fi by linear combination according to formula (<NUM>): <MAT> where wi is a weighting factor for light source i. Such averaged efficiency factor F as resulting from formula (<NUM>) 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 wi 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 wi 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.

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.

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.

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.

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.

Each filter may be laminated on a substrate-forming lens, this substrate-forming lens possibly bearing functional layers, by lamination process as taught in <CIT>.

<FIG> illustrates an eyeglass obtained by laminating a filter designed according to the method of the invention on a substrate-forming ophthalmic lens. Reference numbers <NUM> and <NUM> denote the ophthalmic lens and the filter, respectively.

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.

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.

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 <NUM>®), 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.

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-<NUM>® 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 <NUM>,<NUM> and <NUM>,<NUM>. 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.

All the materials cited here-above for the substrate-forming lens when the filter obtained by the method of the invention 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.

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 patents <CIT> and <CIT>.

A filter obtained by the method of 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.

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.

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 <NUM> +/- <NUM> in methylene chloride (CH<NUM>Cl<NUM>), corresponding to the absorbance range of melanopsin. Full width at half maximum for the P491 absorbance peak is about <NUM>. The second absorber is referred to as ABS <NUM> and has an absorbance peak at wavelength value of <NUM> +/- <NUM> in methylene chloride, corresponding to the regeneration range of melanopsin. Full width at half maximum for the ABS <NUM> absorbance peak is about <NUM>.

Three filters have been produced using the following absorber amounts incorporated in one clear substrate material for forming ophthalmic lenses:.

For comparison, a filter F0 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:.

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

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.

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 <NUM> with respect to the absorber Exciton P491. It also appears that the physiological effectiveness of the absorber Exciton ABS <NUM> in the melanopsin regeneration range is substantially similar to that of doubling the amount of the absorber Exciton P491.

In most preferred implementations, the ophthalmic element obtained by the method of the invention, and which is provided with light-filtering features 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..

But preferably, such smart ophthalmic element obtained by the method of 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:.

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.

Claim 1:
Method for producing an ophthalmic element adapted for see-through when used by a wearer equipped with said element, and adapted 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 [<NUM> - <NUM>],
wherein the element is adapted so that a value of an efficiency factor F computed for said element is higher than or equal to <NUM>, preferably higher than <NUM>, more preferably higher than <NUM>, said efficiency factor value being computed based on the transmittance T, on a spectral sensitivity profile M of the non-visual physiological effect, and on a spectral distribution E of light intensity corresponding to at least part of the light which enters into the wearer's eye without using the filter, said efficiency factor F for the filter is computed using the following formula: <MAT> wherein:
λ is light wavelength within the visible range;
T(A) is the transmittance value of the filter at wavelength A, T(A) is expressed as a percentage value;
M(A) is a value of the spectral sensitivity profile M of the non-visual physiological effect at wavelength A, M(A) is expressed as a percentage value; and
E(A) is a value of the spectral distribution E of the light intensity at wavelength λ
E(λ) is expressed in watt per square meter and per nanometer,
and wherein the efficiency factor value is higher than or equal to K x b*, K being a coefficient higher than or equal to <NUM>, and b* being a CIE Lab colorimetric parameter for the light transmitted through the element, CIE illuminant D65 being used for assessing the b* value;
wherein the at least one non-visual physiological effect is stimulated by reducing a light amount which enters into the wearer's eye and which is comprised within a spectral sensitivity range of melanopsin, and the spectral sensitivity profile M which is used for computing the efficiency factor value of the element is a spectral sensitivity profile of melanopsin, the method comprising a step of producing the ophthalmic element comprises selecting appropriately parameters or components of the ophthalmic element, including die molecules, filter thickness and die concentrations for an absorption-based filtering, 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.