Patent Description:
Tinted eyeglasses are well-known for long time for protecting the eyes against excessive light, in particular excessive sun light. They are designed for filtering out UV light which is harmful for the human eyes, and also part of the visible light so as to avoid the wearer to be dazzled. But such reduction in the visible light causes the pupillary constriction to lessen, which increases in turn optical aberrations that exist in the image formed on the retina, and also reduces the depth of field. Therefore, by increasing the pupillary diameter, the tinted eyeglasses cause a reduction in the image quality of human vision.

Document <CIT> discloses a lens or shield suitable to provide protection to wearer's eyes from harmful part of the light spectrum, while selectively transmitting more of a certain wavelength range of the light spectrum that has a therapeutic benefit, such as healing or general mood modifier. Such lens or shield may have light transmittance values below <NUM>% for wavelength values from <NUM> (nanometer) to <NUM>, and increased transmittance values in the wavelength range from <NUM> to <NUM>. In particular, lenses or shields disclosed in <CIT> have a relative transmittance maximum at around <NUM> to <NUM>, and substantially attenuate light by more than <NUM>% in the wavelength range of about <NUM> to <NUM>.

Document <CIT> also discloses a light filter related to circadian rhythms.

But another issue relates to circadian rhythms of some human physiological functions. Indeed, there are non-visual physiological functions which are activated based on melanopsin, this latter being sensitive to part of the visible light which enters into the eyes. Melanopsin has a maximum light absorption range which extends between <NUM> and <NUM> for the light wavelength values, and entrance into the eyes of light within this wavelength range during the day participates in maintaining circadian rhythms for the physiological functions concerned. In particular, sleep disorders and mood disorders have been observed to occur in case of insufficient exposure to light with wavelength values between <NUM> and <NUM>.

From this situation, there is a need to have eyeglasses which provide an efficient protection against excessive light intensity, without causing disorders for physiological functions which are based on part of the light which enters into the eyes.

Another need relates to tinted eyeglasses which provide an appropriate trade-off between protection against blue-violet light hazard and transmission of light which is effective for non-visual physiological functions.

To this end, a first aspect of the invention proposes an ophthalmic tinted lens according to claim <NUM>.

The visual transmission TV which is effective for human vision being less than <NUM>% means than the invention lens is not clear, but it is efficient for reducing dazzling when ambient light intensity is important. Lower values for the visual transmission TV mean improved protection against dazzling. In particular, the value of the visual transmission TV being less than or equal to <NUM>% and higher than <NUM>% means that the tinted lens may be of class <NUM>, <NUM> or <NUM> according to Standard ISO <NUM>-<NUM>.

The condition about the FC-value being higher than a lower limit, this limit possibly varying with the TV-value, means than the lens transmits the light which is effective for the non-visual physiological effect in a sufficient extent for ensuring that this effect still participates to at least one circadian biological rhythm. Higher values for the chronobiological factor FC mean that the non-visual physiological effect with its circadian rhythm is maintained in a greater extent.

In addition, the lower limit for the FC-value depending on the value of the visual transmission TV expresses the trade-off between producing an efficient protection against excessive light intensity and maintaining the circadian rhythm for the non-visual physiological effect.

Furthermore, since the light which is effective for the non-visual physiological effect participates to enhancing the amplitude of pupillary constriction (i.e. reducing pupil size compared to standard sunglasses) and enhancing the sustainability of the pupillary constriction, the FC-value being higher than the lower limit also ensures that the pupillary constriction is at least partly maintained by the invention tinted lens. The benefits of the pupillary constriction, including better retina protection, reduced optical aberrations and increased depth of field for the image which is formed on the retina, are also maintained as a consequence.

According to the claimed invention, the visual transmission value TV may be computed using the following first formula: <MAT> where:.

The spectral transmittance T(λ) is expressed as a percentage value, namely ranging between <NUM> and <NUM>. This leads to the TV-value computed according to formula (<NUM>) to range from <NUM> to <NUM> too.

In the frame of the present invention, photopic vision means vision in daylight conditions. In particular, the spectral intensity distribution Es of the solar light which is used for computing the TV-value according to formula (<NUM>) may match the CIE Standard illuminant D65.

Furthermore, the chronobiological factor FC is an average value of the spectral transmittance values T(λ) across the wavelength range <NUM> to <NUM>, or <NUM> to <NUM>, these ranges corresponding to maximum sensitivity of melanopsin.

In particular, the chronobiological factor FC may be computed using one of the following formulae: <MAT> or <MAT>.

According to the claimed invention, the ophthalmic tinted lens further has a value of a blue-violet protection factor FBV for quantifying an efficiency of the lens to protect the human eye against hazard due to blue-violet solar light. This blue-violet protection factor FBV is computed as <NUM> minus another value which quantifies a third light amount ratio which relates to light belonging to the wavelength range <NUM> to <NUM> and also transmitted through the lens. Then, the TV-value and the FBV-value expressed as percentage values may meet the following condition: FBV > -<NUM> x TV + <NUM> if <NUM>% ≤ TV ≤ <NUM>%.

High values for the blue-violet protection factor FBV mean that the invention lens provides high protection against the retinal hazards of the blue-violet light.

The blue-violet protection factor FBV is computed as <NUM> minus an average value of the spectral transmittance values T(λ) across the wavelength range <NUM> to <NUM>, this range corresponding to maximum retinal hazard due to blue-violet light.

In particular, the blue-violet protection factor FBV according to the claimed invention is computed using the following formula: <MAT>. As before, the spectral transmittance values T(λ) which are expressed as percentage values ranging from <NUM> to <NUM> are to be used in this formula for obtaining the FBV-value. This leads to the FBV-value thus computed to range from <NUM> to <NUM> too.

Advantageously, the FC-value and the FBV-value expressed as percentage values may meet the following condition: FC > -<NUM> x FBV + <NUM>.

Preferably, a global efficiency factor FTOT which is equal to a sum of the FC-value and FBV-value expressed as percentage values, divided by two, may be higher than <NUM>%. This lower limit for the global efficiency factor FTOT indicates that the invention lens combines maintenance of at least one circadian rhythm related to the non-visual physiological effect, pupil constriction and sufficient protection against blue-violet light hazard.

A second aspect of the invention provides a solar protection equipment which comprises a spectacle frame suitable for fitting on a wearer's face, and two ophthalmic tinted lenses each in accordance with the first invention aspect. The ophthalmic tinted lenses are then mounted within the spectacle frame.

A third aspect not forming part of the claimed invention proposes an ophthalmic tinted lens which has a light transmittance spectrum extending at least from <NUM> to <NUM> for the wavelength values λ. This lens comprises a light-absorbing material which is effective for producing the light transmittance spectrum, said light transmittance spectrum exhibiting:.

The light-absorbing material which is effective for producing the light transmittance spectrum incorporates a specific mix of dyes and absorbers. In order to have the first average transmittance range T(λ) lower than <NUM>·TV at the first wavelength range between <NUM> and <NUM>, and get significantly high λ-derivative value of T(λ) calculated between the wavelength values <NUM> and <NUM>, at least one selective dye may be used, which absorbs in the range <NUM> - <NUM> selectively when compared to the other range <NUM> - <NUM>. In addition, to get the second transmittance value of between <NUM>% and <NUM>% at the second wavelength value between <NUM> and <NUM> but with significant high absolute value of the λ-derivative value of T(λ) calculated between the wavelength values <NUM> and <NUM>, at least one first absorber is used according to the invention, which absorbs in the range <NUM> - <NUM> and/or around <NUM>, selectively when compared to said other range <NUM> - <NUM> and also selectively with respect to the wavelength range <NUM> - <NUM>. In particular embodiments of the invention, dyes absorbing at the same time in the ranges <NUM> - <NUM> and <NUM> - <NUM>, such as Exciton ABS <NUM>, Yamada FDB002 and/or Gentex A102 may be used. The light transmission features of each dye and the light absorption features of each absorber may be measured when this dye or absorber is dissolved in Trivex™ matrix or in polyurethane, with a concentration of between <NUM>,<NUM> (milligram) to <NUM> per <NUM> (gram) of Trivex™ or polyurethane, depending on the dye or absorber of concern, and also depending on an intended optical path length comprised between <NUM> and <NUM>.

Generally for the third aspect, the ophthalmic tinted lens may further have one or several of the following additional features:.

A fourth aspect not forming part of the claimed invention proposes a process for manufacturing an ophthalmic tinted lens, which comprises:.

The process may then further comprise producing the ophthalmic tinted lens based on the light-absorbing material which incorporates the at least one dye and at least one first absorber in accordance with their respective concentrations.

Other features and advantages of the invention will become more apparent from the embodiment examples which are described hereafter, for illustration purpose but without limiting the invention.

In <FIG>, reference number <NUM> denotes an ophthalmic tinted lens which is exposed to impinging light. The light ray R passes through the lens <NUM> and enters into the eye <NUM> of a wearer who is equipped with the ophthalmic tinted lens <NUM>. To this purpose, the lens <NUM> is mounted into a spectacle frame <NUM> so as to form the solar protection equipment <NUM>.

The spectral light transmittance T(λ) of the ophthalmic tinted lens <NUM> can be measured in a well-known manner, for example using a spectrophotometer. As a nonlimiting example, the light ray R may be oriented perpendicular to the lens <NUM> during the measurements. Then, the visual transmission TV of the lens <NUM>, which quantifies the intensity ratio of the light which participates to human photopic vision, may be calculated using the above formula (<NUM>), where the spectral intensity values of the illuminant D65 may be used for the spectral intensity distribution Es, as defined by the standard ISO <NUM>-<NUM>:<NUM>. The spectral sensitivity profile V of the human eye for photopic vision is defined by CIE Standard ISO <NUM>:<NUM>/CIE S005/E-<NUM>.

The chronobiological factor FC may be provided generally by the following second formula: <MAT> where:.

The FC-value thus computed ranges from <NUM> to <NUM>, since the spectral transmittance values T(λ) to be inputted in formula (<NUM>) range from <NUM> to <NUM>.

In preferred embodiments of the invention, the spectral intensity distribution Es of solar light, which is used for computing the TV-value and FC-value, may match the CIE Standard illuminant D65.

Possibly, m<NUM> may equal <NUM> and m<NUM> may equal <NUM>.

When the chronobiological factor FC is directed to at least one melanopsin-based physiological effect, the spectral sensitivity profile M may be a spectral absorption profile of melanopsin. In this way, the FC-value quantifies an efficiency of the invention tinted lens to maintain at least one circadian rhythm for a melanopsin-based physiological effect. <FIG> reproduces a spectral absorption of melanopsin as recovered from widely available documents. The horizontal axis of this diagram indicates the wavelength values λ in nanometers, and the vertical axis indicates the melanopsin absorption values, corresponding to M(λ). The melanopsin absorption values for both wavelength values <NUM> and <NUM> are about <NUM> when the maximum absorption value is set to unity. So, the spectral sensitivity profile M for each wavelength value between <NUM> and <NUM> but outside the range from <NUM> to <NUM>, is much less than the maximum value of this spectral sensitivity profile M, such maximum value occurring for a value of the wavelength λ which is comprised between <NUM> and <NUM>. Then, for a melanopsin-based physiological effect, the chronobiological factor FC can be more focused on the melanopsin absorption range when m<NUM> equals <NUM> and m<NUM> equals <NUM>, or m<NUM> equals <NUM> and m<NUM> equals <NUM>.

So, when the non-visual physiological effect which is considered is based on melanopsin, the spectral absorption profile of melanopsin can be used for the spectral sensibility profile M. Then, it may be considered that the Es(λ)-values of the spectral intensity distribution of the solar light are almost constant across the wavelength range from <NUM> to <NUM>, and that the spectral sensitivity profile M has a crenel-shape with values M(λ) which are almost equal to zero outside the wavelength range from <NUM> to <NUM>, and almost constant non-zero values M(λ) between <NUM> and <NUM>. Then, these conditions lead to the FC-value being computed as <MAT> when m<NUM> = <NUM> and m<NUM> = <NUM>, which involves simplified and more rapid calculations. Similar reasons apply for using alternatively m<NUM> = <NUM> and m<NUM> = <NUM>.

Low TV-values indicate that the ophthalmic tinted lens reduces significantly the amount of visible light which enters into the wearer's eye, and high FC-values indicate that the ophthalmic tinted lens produces good transmission for the light part which is effective for the non-visual physiological effect. In <FIG>, the horizontal axis of the diagram displayed indicates the TV-values, and the vertical axis indicates the FC-values calculated according to the above simplified formula with m<NUM> = <NUM> and m<NUM> = <NUM>. The diagram compares in this first coordinate system, locations of lenses existing prior to the present invention to lenses which meet the invention. The left segment of the boundary L<NUM> corresponds to the condition FC = <NUM> x TV + <NUM> for <NUM>% ≤ TV ≤ <NUM>%, and the right segment of the boundary L<NUM> corresponds to the condition FC = <NUM> x TV + <NUM> for <NUM>% < TV ≤ <NUM>%. <FIG> thus shows that the lenses which existed before the present invention are located in the lower right part of the diagram, with respect to the boundary L<NUM>, whereas the invention lenses are located in the upper left diagram part. This distribution indicates the improvement which is brought by the invention lenses for transmitting light which is effective for a melanopsin-based non-visual physiological effect, while producing a protection against dazzling.

The particular invention sample which is indicated with a square in the diagrams of <FIG> and called Mirror will be described later.

When the non-visual physiological effect which is desired to be maintained while the wearer is equipped with the lens <NUM>, is melanopsin-based, the sub-part of the spectral range of visible light to be transmitted efficiently through the lens is from about <NUM> to about <NUM>. However, it is well-known that the blue-violet light with wavelength values below <NUM> or <NUM> is harmful for the retina and participates to the ageing of the eye. It is therefore preferable that the lens <NUM> provides protection against such blue-violet light below <NUM> at the same time it provides efficient transmission between <NUM> and <NUM>. Then, the following formula (<NUM>) allows quantifying such protection against harmful blue-violet light: <MAT> where:.

The diagram of <FIG> shows two spectral profiles of the harmful blue-violet light, denoted B(λ) and B'(λ) respectively, and which can be used alternatively in formula (<NUM>). The profile B(λ) is that contained in Standard ISO <NUM>-<NUM>, and the profile B'(λ) is that disclosed in the PlosOne reference indicated above.

In a way similar to that applied for the chronobiological factor FC as initially expressed according to formula (<NUM>), it may be considered that the Es(λ)-values of the spectral intensity distribution of solar light are almost constant across the wavelength range from <NUM> to <NUM>, and that the harmful blue-violet profile B(λ) or B'(λ) is similar to a crenel-shape, with values which are almost equal to zero outside the wavelength range from <NUM> to <NUM>, and almost constant non-zero values between <NUM> and <NUM>. Then, the FBV-value may be computed as <MAT>, which involves simplified and more rapid calculations. In <FIG>, the horizontal axis of the diagram displayed indicates the TV-values again, but the vertical axis indicates the FBV-values calculated in this simplified way. The diagram compares in this second coordinate system, locations of the lenses existing prior to the present invention to the lenses which meet the invention. The continuous straight line L<NUM> corresponds to formula FBV = -<NUM> x TV + <NUM> for <NUM>% ≤ TV ≤ <NUM>%. <FIG> then shows that the lenses which existed before the present invention are located in the lower left part of the diagram, with respect to the boundary line L<NUM>, whereas the invention lenses are located in the upper right diagram part. This distribution indicates the improvement which is brought by the invention lenses for protecting against the blue-violet light hazard while simultaneously producing an efficient protection against dazzling.

In <FIG>, the horizontal axis of the diagram displayed indicates the FBV-values, and the vertical axis indicates the FC-values. The diagram compares in this third coordinate system, locations of the lenses existing prior to the present invention to the lenses which meet the invention. The continuous straight line L<NUM> corresponds to formula FC = -<NUM> x FBV + <NUM>. <FIG> then shows that the lenses which existed before the present invention are located mainly in the lower left part of the diagram, with respect to the boundary line L<NUM>, whereas the invention lenses are located in the upper right diagram part. This distribution indicates the improvement which is brought by the invention lenses for producing an efficient protection against harmful blue-violet light while transmitting enough light effective for the melanopsin-based non-visual physiological effect.

The half-sum of both FC- and FBV-values quantifies the capability of a lens to provide an efficient protection against harmful blue-violet light and simultaneously transmitting light which is effective for the melanopsin-based non-visual physiological effect. In <FIG>, the horizontal axis of the diagram displayed indicates the TV-values, and the vertical axis indicates the values for FTOT = <NUM>·(FC+FBV). The diagram compares in this fourth coordinate system, locations of the lenses existing prior to the present invention to the lenses which meet the invention. The continuous straight line L<NUM> corresponds to FTOT = <NUM>%. The diagram shows that the lenses which existed before the present invention are located in the lower part of the diagram, with respect to the boundary line L<NUM>, whereas the invention lenses are located in the upper diagram part. This distribution indicates the improvement which is brought by the invention lenses for producing efficient protection against harmful blue-violet light while being efficient for transmitting light effective for the melanopsin-based non-visual physiological effect.

Table <NUM> below recites the dies and absorbers that are used for three invention lenses which are labelled #<NUM>, #<NUM> and #<NUM>, with their respective concentrations. For these three lenses, the lens base material is Trivex™ as supplied by PPG Industries, and which is based on polyurethane polymer. The concentrations are expressed in mg (milligram) of each dye or absorber for <NUM> of the resulting blend of Trivex™ with the dies and absorbers. Commercial suppliers are also indicated between parentheses.

These dyes and absorbers match the transmission and absorption features recited in the general part of the description for the third invention aspect. In particular, the dyes are mainly responsible for the shape of the lens transmittance profile for wavelength values between <NUM> and <NUM>, whereas the absorbers are mainly responsible for the shape of the lens transmittance profile for wavelength values between <NUM> and <NUM>. For reciting the connections with the general part of the invention description:.

With these compositions, lens #<NUM> is blue-green in transmission and has a transmission colorimetric a*-value which is equal to -<NUM>, lens #<NUM> is greyish in transmission and has another transmission colorimetric a*-value which is equal to -<NUM>, and lens #<NUM> is greyish in transmission too but with a*-value of -<NUM>.

A further ophthalmic tinted lens in accordance with the invention has been produced from the above lens #<NUM>, by applying the following transmission-selective stack on the convex face of this lens: silica (SiO<NUM>): <NUM> (nanometer), zirconia (ZrO<NUM>): <NUM>, silica: <NUM> and zirconia: <NUM>, and also by applying the antireflective coating called Crizal F® and produced by Essilor on the concave face of the lens. This further ophthalmic tinted lens has been labelled Mirror in <FIG>, and #<NUM>-Mirror/AR in table <NUM> below and <FIG>.

Still another ophthalmic tinted lens in accordance with the invention has been produced from the lens #<NUM>, by applying the antireflective coating Crizal F® on both its concave and convex faces. The tinted lens thus obtained is labelled #<NUM>-AR/AR in table <NUM> below and <FIG>.

With the dyes and absorbers of table <NUM> and their respective concentrations, the following numerical values have been obtained for the above described lenses, using the illuminant D65 and the calculation parameters indicated therein:.

<FIG> compares spectral light transmittance profiles of four among these invention lenses, with three lenses which existed before the invention. The horizontal axis indicates the wavelength values λ in nanometers, from <NUM> to <NUM>, and the vertical axis indicates the spectral light transmittance values T(λ) for all lenses. The thickness of the base lens material for the seven lenses is <NUM> (millimeter). It appears that the invention lenses exhibit profiles which are much more shaped, with lower transmittance values for wavelength values below <NUM>, higher transmittance values between <NUM> and <NUM>, and a deeper decrease of the transmittance between about <NUM> and <NUM>. The four invention lenses considered in <FIG> are #<NUM>-AR/AR, #<NUM>-Mirror/AR, #<NUM> and #<NUM>. Each of them has a average transmittance value in the wavelength range <NUM> - <NUM> which amounts to between <NUM>% and <NUM>%. Transmittance is higher than <NUM>% in the range <NUM> - <NUM> for all lenses represented.

<FIG> also shows the narrow wavelength ranges <NUM> - <NUM> and <NUM> - <NUM>, in which the slopes of the T(λ)-curves may be calculated. Line constructions are also provided for drawing a first slope P<NUM> equal to <NUM> %·nm-<NUM> and a second slope P<NUM> equal to -<NUM> %·nm-<NUM>. Then, it can be checked that the slopes of the transmittance curves for the four invention lenses are steeper than P<NUM> in the range <NUM> - <NUM>, and the slopes in the range <NUM> - <NUM> for the same curves are steeper than P<NUM>.

In addition, clinical studies have shown that such ophthalmic tinted lens according to the invention causes a benefit in the pupillary amplitude of constriction of <NUM>%, and in the constriction sustainability of <NUM>%, vs a standard solar lens.

Claim 1:
Ophthalmic tinted lens (<NUM>) having a visual transmission value TV for quantifying a first light intensity ratio which relates to light effective for human vision and transmitted through the lens in daylight condition, and a value of a chronobiological factor Fc for quantifying a second light amount ratio which relates to light effective for a non-visual physiological effect and also transmitted through the lens, the light effective for the non-visual physiological effect being also involved in the human vision,
wherein the TV-value and the FC-value expressed as percentage values meet the following condition: FC > <NUM> x TV + <NUM> with <NUM>% ≤ TV ≤ <NUM>%, or FC > <NUM> x TV + <NUM> with <NUM>% < TV ≤ <NUM>%, wherein the visual transmission value TV is computed using the following formula: <MAT> where:
λ is light wavelength within the visible range <NUM> to <NUM> of the human vision,
T(λ) is a spectral transmittance value of the ophthalmic tinted lens at wavelength λ, expressed as a percentage value,
V(λ) is a value at wavelength λ of a spectral sensitivity profile V of a human eye for photopic vision, and
Es(λ) is a value at wavelength λ of a spectral intensity distribution Es of solar light,
and the chronobiological factor Fc is an average value of the spectral transmittance values T(λ) across the wavelength range <NUM> to <NUM>, or <NUM> to <NUM>, said range corresponding to maximum sensitivity of melanopsin and,
wherein the chronobiological factor is computed using the following formula: <MAT>
and wherein the lens comprises a light absorbing material which incorporate a mix of dies and absorbers, and wherein at least one absorber absorbs in the range <NUM> - <NUM> and/or around <NUM>, selectively when compared to said other range <NUM> - <NUM> and also selectively with respect to the wavelength range <NUM> - <NUM>, wherein the lens further having a value of a blue-violet protection factor FBV for quantifying an efficiency of the lens to protect the human eye against hazard due to blue-violet solar light, said blue-violet protection factor FBV being computed as <NUM> minus another value which quantifies a third light amount ratio which relates to light belonging to the wavelength range <NUM> to <NUM> and also transmitted through the lens,
wherein the TV-value and the FBV-value expressed as percentage values meet the following condition: FBV > -<NUM> x Tv + <NUM> if <NUM>% ≤ Tv ≤ <NUM>% and,
wherein <MAT>