WO2020039020A1

WO2020039020A1 - Blue light filter lens

Info

Publication number: WO2020039020A1
Application number: PCT/EP2019/072441
Authority: WO
Inventors: Steffen GEIPEL; Gerold BAECKER
Original assignee: Dsm Ip Assets B.V.
Priority date: 2018-08-24
Filing date: 2019-08-22
Publication date: 2020-02-27
Also published as: TW202033989A

Abstract

An optical lens with an improved blue edge filter, wherein the distinctive but cosmetically unacceptable yellow color of blue edge filter lenses is masked by at least one masking dye. Preferably, the optical lens of the invention protects the eye from damaging blue light and also from UV radiation. The blue edge filter lens does not have any negative impact on the human circadian rhythm.

Description

BLUE LIGHT FILTER LENS

Technical field

The present invention relates to the manufacturing of optical lenses with a blue edge filter. It also relates to the prevention of age-related macular degeneration (AMD).

Background of the invention

Damage to the eye’s macula has several causes. One factor is the impact of blue light. Therefore, the macula needs blue light protection.

The eye contains lutein and zeaxanthin which absorb blue light. A lack of lutein and/or zeaxanthin increases the risk of macula damage (of. Stringham, et al.“Effects of macular carotenoid supplementation on visual

performance, sleep quality, and adverse physical symptoms in those with high screen time exposure,” published in Foods, 2017).

Optical lenses with a blue edge filter protect the human eye from harmful blue light. US 9,885,885 discloses a blue edge filter optical lens substantially transmitting blue light greater than 450 nm.

Some commercially available light sources emit significant amounts of light at 455 nm. Thus, known blue edge filter optical lenses transmitting blue light greater than 450 nm do not give sufficient protection from devices

emitting blue light at 455 nm. Furthermore, commercially available blue edge filter optical lenses have a cosmetically unacceptable yellow, often lemon-like color. Thus, there is a need for a new blue edge filter lens, which gives better protection from damaging blue light and/or which does not have a

cosmetically unacceptable yellow color. Summary of the invention

A lens which absorbs blue light up to 460 nm (instead of up to 450 nm only) gives better protection from damaging blue light. However, such lenses are known to trigger unwanted tiredness. Thus, there is a need for a new blue edge filter lens,

— which gives better protection from damaging blue light, and

— which does not trigger unwanted tiredness, and

— which does not have a cosmetically unacceptable yellow color. This problem is solved by providing a blue edge filter lens,

— which has its edge at 460 nm, and

— which allows partial transmittance of blue light having wavelengths of approx. 480 nm +/-15 nm, and

— whose yellow color is masked. Tiredness is linked to the human circadian rhythm. Said rhythm is regulated by melatonin secretion. Melanopsin, which prevents melatonin secretion, has a peak spectral sensitivity in the region of 480 nm. Blocking light having a wavelength of 480 nm triggers a higher than normal melatonin secretion during daytime. Partial transmittance of blue light having wavelengths of approx. 480 nm +/-15 nm prevents unwanted tiredness.

One can think of two types of blue edge filter lenses: blue edge filter lenses which are suitable for manufacturing sunglasses (i.e. dark lenses) and blue edge filter lenses which are meant for the continuous, everyday use independent of the weather conditions (i.e. light tint lenses). Blue edge filter lenses meant for such continuous use should be suitable for night-time driving. Thus, there is a need for a new blue edge filter lens,

— which does not trigger unwanted tiredness, and

— which gives better protection from damaging blue light, and

— which does not have a cosmetically unacceptable yellow color, and

— which is suitable for night-time driving. This problem is solved by providing a blue edge filter lens,

— which has its edge at 460 nm, and

— whose yellow color is masked, and

— which has a luminous transmission factor T_v of at least 75% and meets other relevant regulatory/legal requirements.

Glasses should not impair traffic signal detection. This also applies to relatively dark sunglasses. Otherwise, they cannot be worn when driving a car. Thus, there is a need for a new blue edge filter lens,

— which gives better protection from damaging blue light, and

— which gives protection from UV light and the brightness of visible light, and

— which does not impair traffic signal detection and

— which does not have a cosmetically unacceptable yellow color.

This problem is solved by providing a blue edge filter lens,

— which has its edge at 460 nm, and

— which absorbs UV at 380 nm and/or 400 nm and which is of filter

category 2 or 3, and

— which has relative visual attenuation quotients Q in accordance with the applicable regulation/law, and

— whose yellow color is masked.

A lens of filter category 2 or 3 has a certain darkness, as known from commercially available sunglasses. Sunglasses are used on sunny days only. Therefore, unwanted tiredness due to melatonin secretion is not a major concern for sunglasses.

The present invention also relates to the use of a dispersion which comprises red, green and/or blue dye for masking the yellow color of a blue edge filter lens. For tinting an optical lens, the lens is submerged in an aqueous dye dispersion. According to the invention, a blue edge filter lens with a cosmetically acceptable color is obtained by submerging the lens in at least two aqueous dye dispersions, one aqueous dispersion containing a yellow dye dispersion for filtering damaging blue light, the other aqueous dispersion containing at least one masking dye to mask the lens’ cosmetically

unacceptable lemon-like color.

Surprisingly, a better result is achieved when the lens to be dyed is first submerged into the aqueous yellow dye dispersion. The thus obtained yellowish lens is then submerged in at least one aqueous masking dye dispersion to mask the cosmetically unacceptable lemon-like color. If the opposite order is used (i.e. first submersion in the masking dye and then submersion in the yellow dye), a spotted lens instead of a uniformly tinted lens is obtained. Spotted lenses have an irregular, random color distribution and are therefore not suitable for sale. Furthermore, the tinting process can be controlled more easily if the lighter yellow dye is applied before applying the darker masking dye.

Tinting an optical lens is an art in itself. Parameters influencing the color of the lens (and thus the lens’ absorption) include the submersion time (i.e. the duration of the submersion) and the concentration of the dye in the aqueous dye dispersion. Tinting according to rigid Standard Operation Procedures (SOP) often fails because submersion time must be adapted to the decreasing concentration of the dye in the aqueous dye dispersion. Said concentration decreases over time as each tinted lens‘consumes’ some dye. Therefore, even nowadays, lenses are often tinted manually under visual inspection. Industrial workers doing such manual tinting need a well-trained color perception. The manufacturing method of the present invention allows for the required visual control.

Thus, the present invention also relates to a manufacturing method, wherein an undyed lens [provided in step a)] is submerged in the yellow dye dispersion [step b)] before being submerged in the masking dye dispersion [step c)]. The transmission curve of the thus obtained lens may be measured at any suitable time. In case the obtained lens still has a cosmetically unacceptable yellow color and/or transmits more light than desired, step a) and/or step b) may be repeated to get a lens with the desired properties.

The dye should then be fixed. In case of a lens comprising or consisting of at least one organic polymer, said fixation is done by heating the tinted lens to a certain temperature for a certain period of time. Surprisingly, the fixation of the dye of the blue edge filter lens of the invention is more effective if a temperature from 1 10°C to 125°C is applied for a duration from 15 minutes to 25 minutes.

The present invention also relates to the prevention of age-related macular degeneration (AMD). According to the invention, macula damages are prevented by blocking blue light at two instances: in front of the eye and within the eye. Such twofold approach is realized by wearing glasses with blue edge filter lenses and by taking a dietary supplement that comprises lutein and/or zeaxanthin. Therefore, kits comprising glasses of the invention and the dietary supplement of the invention are given to consumers. Preferably, such kits are given to consumers whose macular pigment optical density is below average.

Detailed description of the invention

The blue edge filter lens of the invention is preferably an optical lens. Due to a masking dye, it does not have a cosmetically unacceptable yellow color.

Definitions

Opticians use“optical lenses” to manufacture glasses. Glasses which contain one lens only are referred to as monocle. In most cases, glasses have two lenses. The lens of the invention is preferably an optical lens which preferably comprises or consists of at least one organic polymer such as polycarbonate or polyurethane.

By convention, the three primary colors are red, green, and blue. If all three primary colors are showing, the result is white. When red and green combine, the result is yellow. In the context of the present invention, the term“yellow dye” refers to a dye which absorbs damaging blue light at least partially. In the context of the present invention,“damaging blue light” is blue light having a wavelength of 460 nm or less. Light having a wavelength from 465 nm to 495 nm is referred to as“good blue light” as such light is involved the regulation of the human circadian rhythm. “Transmittance” is the fraction of incident light, or other radiation, that passes through a substance at a particular wavelength. In the context of the present invention, it is typically the fraction of the original incident radiation (e.g. light) that passes a lens at a particular wavelength. It can be expressed as a decimal or as a percentage. If transmittance is plotted against a series of wavelengths, then a transmission curve is produced.

In the context of the present invention,“absorption” and“to absorb” are to be understood in a broad manner and refers to incident light, or other radiation, that does not pass through a substance at a particular wavelength.

Expressions such as“absorbs at 380 nm” are used synonymously with expressions such as“absorbs radiation having a wavelength of 380 nm”.

The transmission curve of an edge filter shows at a certain wavelength a sharp slope, referred to as edge. A“blue edge filter lens” absorbs blue light while allowing transmission of light exceeding a certain minimal wavelength. Most known blue edge optical lenses have an edge at 450 nm, i.e. they allow substantial transmission of light having a wavelength greater than 450 nm.

Sunglasses protect the eye from UV radiation and to a certain degree from the brightness of visible light. The term“visible light” refers preferably to radiation having a wavelength from 380 nm to 780 nm. The more visible light a lens absorbs, the darker the lens is. In the context of the present invention, the expression“filter category” refers to one of five filter categories (cf.

TABLE 1 ). Said are used to classify the darkness of a lens.

Table 1

The“luminous transmission factor T_v” expresses the effect of a filter over a range of wavelengths (e.g. from 380 nm to 780 nm). In the context of the present invention, the luminous transmission factor T_v is preferably the overall transmission of a lens when being exposed to a standard light source. The standard light source is preferably standard illuminant D65 as determined by the Commission Internationale de I’Eclairage (CIE); it replicates a daylight source. T_v is preferably measured according to DIN EN ISO 123 12-1. In a preferred embodiment of the invention, the blue edge filter lens is suitable for night-time driving. In the context of the present invention,“suitable for night-time driving” means:

1. the lens is of filter category 0 and/or has a luminous transmission factor T_v of at least 75%; and

2. for wavelengths between 475 nm and 650 nm, the transmittance of the lens is not less than 0.20, preferably not less than 0.19, of the luminous transmission factor T_v; and 3. the relative visual attenuation quotient Q of the lens is not less than 0.80 for red signal light, not less than 0.70 for blue signal light, not less than 0.60 for yellow and for green signal lights, wherein the relative spectral distribution of radiation emitted by incandescent signal lights is applied in accordance with AS/NZS 1067.2, Clause 7.8.

Item 3 of above list relates to traffic signal detection. In the context of the present invention, a blue edge filter lens which“does not impair traffic signal detection” has a relative visual attenuation quotient Q of not less than 0.80 for red signal light, not less than 0.70 for blue signal light, not less than 0.60 for yellow and green signal lights, wherein the relative spectral distribution of radiation emitted by incandescent signal lights is applied in accordance with AS/NZS 1067.2, Clause 7.8.

Most clear lenses absorb some UV radiation, in particular UV radiation at wavelengths shorter than 290 nm. For UV absorption at longer wavelengths, the lens is treated with an UV absorbing composition. According to European standard EN 1836:2005, a lens provides UV protection if not more than 5% of the rays at 380 nm are transmitted. In some countries (e.g. US), transmittance protection for radiation of up to 400 nm ("UV400") is required.

In the context of the present invention, the term“blue edge filter lens being suitable for the manufacturing of sunglasses” refers to a treated lens of filter category 0, 1 , 2, 3 or 4 which absorbs more UV radiation than an untreated lens made of the same material.

The vast majority of plastics lenses are dip-dyed: a lens is placed in a hot liquid and the dye penetrates the surface (sometimes up to a depth of about 1 mm), producing an even appearance. Liquids that are used for dyeing ocular lenses typically contain particles. Therefore, said liquids might require stirring when the lens is submerged. The term“dispersion” as used in the context of the present invention refers preferably to a liquid that comprises undissolved particles. In a less preferred embodiment, all particles are solved, i.e. the dispersion of the invention is a solution.

A“kit” refers to a set of at least two different articles. Even though the articles are different, they serve the same purpose. In the context of the present invention, the unifying purpose is the prevention of age-related macular degeneration (AMD).

Method of manufacturing a blue edge filter lens

The present invention relates to a method of manufacturing a blue edge filter lens, said method comprising the steps:

a) providing an undyed lens, said lens comprising or consisting of at least one organic polymer,

b) submerging the lens of step a) in an aqueous yellow dye dispersion, and

c) masking the yellow color of the lens obtained in step b) at least partially by submerging the lens obtained in step b) in an aqueous masking dye dispersion,

wherein the duration of step b) is preferably at least 20 minutes, and wherein the lens obtained in step b) is preferably rinsed before performing step c).

The lens obtained in step c) should have a cosmetically acceptable color, i.e. the undesired yellow color should be sufficiently masked. If this is not the case, the lens obtained in step c) may be submerged for a second in the aqueous masking dye dispersion of step c).

Preferably, the transmittance of the lens obtained in step b) and/or step c) is measured. Whereas a complete transmission curve can be measured, it may be sufficient to measure the transmittance at 460 nm only. To give better protection from bad blue light, the lens transmits preferably less than 6% of incident light of a wavelength of 460 nm. In case the lens obtained in step b) transmits at the respective wavelength more than desired, the lens may be submerged for a second time in the aqueous yellow dye dispersion of step b). For many yellow dyes, the molar extinction coefficient is rather low at 460 nm which can be compensated to a certain degree by applying longer submersion times (of. principles of Beer Lambert law).

The transmittance of the blue edge filter lens of the invention is at 490 nm preferably at least 5 times higher, more preferably at least 6 times higher than the transmittance of the same blue edge filter lens at 460 nm. Thus, preferably, the transmittance is measured at least at 460 nm and at 490 nm.

In case the lens obtained in step c) does not fulfill this requirement, suitable measures need to be taken. For example, if transmittance at 460 nm is higher than desired, a masking dye having a non-zero molar extinction coefficient at 460 nm can be used to reduce transmittance at said wavelength. Similarly, if transmittance at 470 nm, 480 nm or 490 nm is lower than desired, yellow dyes having a particularly low molar extinction coefficient at said wavelengths can be used to reduce absorbance at said wavelengths and/or the lens whose yellow color is to be masked is submerged for a shorter time in the aqueous masking dye dispersion. The latter will reduce the darkness of the lens, i.e. might reduce the filter category.

The method of the invention may comprise further steps e.g. to provide the blue edge filter lens with an antireflection coating and/or a hardening coating and/or to activate the undyed lens before step b).

In some embodiments of the invention, step c) is split up in multiple steps, i.e. the lens obtained in step b) may be submerged in more than one aqueous masking dye dispersion. An additional dispersion may be used when a blue edge filter lens is to be manufactured that gives a particular UV protection. Thus, the method of the present invention is preferably a method of manufacturing a blue edge filter lens with a UV filter.

Dye dispersions comprise molecules that provide the lens with a color.

Typically, when applying the tinting process of the invention, said molecules migrate 0.1 mm or more into the organic polymer of the lens. The exact penetrations depth depends inter alia on the duration of step b) and the temperature of the aqueous yellow dye dispersion. The duration of step b) is preferably from 20 minutes to 120 minutes, more preferably from 30 minutes to 100 minutes and most preferably from 40 minutes to 90 minutes, wherein the temperature of the aqueous yellow dye dispersion is preferably from 50°C to 150°C, more preferably from 60°C to 130°C, and most preferably from 80°C to 1 10°C. Dyes which can be used in the method of the invention are commercially available e.g. at Cerium Optical Products (Kent, UK) or at Brain Power International Ltd (Warwickshire, England). The preferred yellow dye is N-[4-(2-hydroxy-5-methylphenylazo)phenyl]acetamide, also known as Disperse Yellow 3. Preferably, the yellow dye dispersion used in step b) comprises Disperse Yellow 3.

Thus, a preferred embodiment of the present invention relates to a method of manufacturing a blue edge filter lens, said method comprising the steps: a) providing an undyed lens, said lens comprising or consisting of at least one organic polymer,

b) submerging the lens of step a) in an aqueous liquid comprising

Disperse Yellow 3, and

wherein the duration of step b) is preferably from 40 minutes to 90 minutes, and/or

wherein the temperature of said aqueous liquid comprising Disperse Yellow 3 is preferably from 80°C to 1 10°C, and

wherein the lens obtained in step b) is preferably rinsed before performing step c), and optionally

wherein the lens obtained in step c) is submerged for at least a second time in the aqueous masking dye dispersion of step c) in case said lens obtained in step c) has a cosmetically unacceptable color. Any dye which is capable of masking the yellow color (e.g. the color of

Disperse Yellow 3) may be used as masking dye. Preferred masking dyes are commercially available at Cerium Optical Products (Kent, UK) and are sold under the brands Cactus 1.6, Laurel, Pink 2, Green, Marron, Red, Grey, Midnight and Special Brown. In a preferred embodiment of the invention, the aqueous masking dye dispersion comprises at least one compound which absorbs UV radiation at least partially. To fix the dyes, the dyed lens is preferably heated. Any commercially available oven may be used for this purpose. Typically, a temperature from 80°C to 150°C, preferably from 100°C to 140°C and most preferably from 1 10°C to 130°C is applied. If the dyes are not properly fixed, the lens is prone to discoloration. Such discoloration occurs during follow-up manufacturing steps (e.g. provision of an antireflection coating) and/or during daily use due to e.g. UV exposure. Surprisingly, fixation is particularly effective if a relatively high temperature is applied for a relatively short period of time. Preferably, a temperature from 1 10°C to 130°C (more preferably from 1 10°C to 125°C) is applied for a duration from 15 minutes to 25 minutes. In the most preferred embodiment, a temperature 120°C is applied during 25 minutes for fixing the dye.

The fixation of the dye is particularly effective if the undyed lens comprises or consists of at least one thermosetting polymer. Such polymers are

commercially available. Preferably, the undyed lens comprises or consists of at least one polyurethane (e.g. resin MR8 from Mitsui Chemicals) and/or at least one polycarbonate being preferably allyl diglycol carbonate (e.g. CR-39, also known as Columbia resin).

An apparatus suitable for implementing the method of the present invention is disclosed in WO 90/05207. Said document also discloses the structure of CR-39 and other organic polymers that can be used to manufacture the undyed lens of the invention (WO 90/05207, page 7, lines 17-29).

Furthermore, it discloses ingredients of preferred dye dispersions

(WO 90/05287, page 7, line 30 to page 8, line 14). Thus, a preferred embodiment of the present invention relates to a method of manufacturing a blue edge filter lens, said method comprising the steps: a) providing an undyed lens, said lens comprising or consisting of at least one polyurethane or at least one polycarbonate,

b) submerging the lens of step a) in an aqueous liquid comprising

Disperse Yellow 3, and c) masking the yellow color of the lens obtained in step b) at least partially by submerging the lens obtained in step b) in an aqueous masking dye dispersion, and

d) heating the lens obtained in step c) to a temperature of preferably at least 100°C, more preferably to a temperature of at least 1 10°C for a duration from preferably 15 minutes to 25 minutes,

wherein the lens obtained in step b) is preferably rinsed before performing step c), and

wherein the lens obtained in step c) is preferably rinsed before performing step d). In one embodiment of the invention, the blue edge filter lens also provides UV protection. Thus, the present invention also relates to a method of

manufacturing a blue edge filter lens also providing UV protection, said method comprising the steps:

b) submerging the lens of step a) in an aqueous yellow dye dispersion, and c) masking the yellow color of the lens obtained in step b) at least partially by submerging the lens obtained in step b) in an aqueous masking dye dispersion,

wherein said masking dye comprises at least one compound that absorbs UV light at least partially.

The herein described method of manufacturing a blue edge filter lens is preferably a method of manufacturing an optical blue edge filter lens. Blue edge filter lens

The edge of the blue edge filter lens of the invention is preferably at 460 nm (i.e. not at 450 nm). Thus, the transmittance of the blue edge filter lens of the invention is at 490 nm preferably at least 5 times higher, more preferably at least 6 times higher than the transmittance of the same blue edge filter lens at 460 nm. In this embodiment, the transmittance of said lens at 460 nm is preferably less than 6%, more preferably less than 5%.

For a blue edge filter lens of filter category 0 or 1 (i.e. light tint), the

transmittance of said lens at 490 nm is preferably at least 29%, more preferably at least 35% and most preferably at least 40%, whereas the transmittance of said lens is at 490 nm preferably at least 5 times higher, more preferably at least 6 times higher than the transmittance of the same blue edge filter lens at 460 nm.

In one embodiment of the invention, the blue edge filter lens gives triple protection: protection from UV radiation, protection from damaging blue light and protection from the brightness of visible light. To provide a lens with sound UV protection, the lens can be dipped into a suitable commercially product such as“Shades UV 400nm Clear” available at Cerium Optical Products (Tenterden, Kent TN30 7DE). A blue edge filter lens giving triple protection is typically of filter category 2, 3 or 4 (i.e. it looks as dark as sunglasses). As a result thereof, when looking at its transmission curve, the edge is not as sharp/steep as the edge of a blue edge filter lens of filter category 0 or 1.

In one embodiment, the blue edge filter lens of the invention transmits less than 6%, preferably less than 5% of light having a wavelength of 460 nm, whereas the transmittance of said blue edge filter lens is at 490 nm preferably at least 5 times higher, more preferably at least 6 times higher than at 460 nm.

In another embodiment, the blue edge filter lens of the invention transmits less than 6%, preferably less than 5% of light having a wavelength of 460 nm, whereas the transmittance of said blue edge filter lens at 490 nm is preferably at least 29%, more preferably at least 35% and most preferably at least 40%.

In yet another embodiment, the blue edge filter lens of the invention is suitable for night-time driving and transmits less than 6%, preferably less than 5% of light having a wavelength of 460 nm, whereas the transmittance of said blue edge filter lens is at 490 nm preferably at least 5 times higher, more preferably at least 6 times higher than at 460 nm.

In yet another embodiment, the blue edge filter lens of the invention does not impair traffic signal detection and transmits less than 6%, preferably less than 5% of light having a wavelength of 460 nm, whereas the transmittance of said blue edge filter lens is at 490 nm preferably at least 5 times higher, more preferably at least 6 times higher than at 460 nm.

In yet another embodiment, the blue edge filter lens of the invention transmits less than 6%, preferably less than 5% of light having a wavelength of 460 nm and transmits less than 1 % of UV light having a wavelength of 380 nm and transmits less than 1 % of UV light having a wavelength of 400 nm, whereas the transmittance of said blue edge filter lens at 490 nm is preferably at least 29%, more preferably at least 35% and most preferably at least 40%, and whereas said blue edge filter lens. Other preferred embodiments of the invention (numbered from #1 to #7) are listed in TABLE 2. In each of these embodiments, the transmittance of the respective lens is at 490 nm preferably at least 5 times higher, more preferably at least 6 times higher than the transmittance of the same lens at 460 nm.

Table 2 The blue edge filter lens of the invention is preferably obtained by the method of the present invention. Thus, the blue edge filter lens of the invention is preferably an optical blue edge filter lens.

Although not wishing to be bound by theory, it is believed that the yellow dye migrates into the organic polymer of the lens to occupy some of the polymer’s “empty spots”. In the subsequent step, the masking dye then migrates into the organic polymer of the lens to occupy those“empty spots” which are still available. The thus obtained distribution of the at least two dyes in the organic polymer is then fixed by the herein described heating step. Surprisingly, a uniformly tinted lens is obtained when the yellow dye migrates first into the organic polymer. In contrast, if the tinting process begins with the masking dye, the distribution of the dye in the outer parts of the polymer is such that a randomly spotted lens is obtained. A spotted lens is useless and cannot be sold. Thus, the present invention relates to a blue edge filter lens preferably obtained by a method comprising the steps:

a) providing an undyed lens, said lens comprising or consisting of at least one polyurethane or at least one polycarbonate,

b) submerging the lens of step a) in an aqueous yellow dye dispersion, and

c) masking the yellow color of the lens obtained in step b) at least partially by submerging the lens obtained in step b) in an aqueous masking dye dispersion, and

d) heating the lens obtained in step c) for fixation of the dyes,

wherein said yellow dye absorbs a blue light at least partially.

Preferably, the yellow dye is applied such that the dyed (i.e. tinted) lens transmits less than 6% of incident light of a wavelength of 460 nm. For the very first lens of a production series, this can be easily checked by using a spectrophotometer. For the following lenses, the first lens can be used as reference for visual inspection.

The person skilled in the art can then find a suitable aqueous masking dye dispersion, using commercially available dyes or mixtures of commercially available dyes. In fact, the tint of the final lens is mostly a question of personal choice. Some clients prefer a greenish tint whereas others prefer a more orange tint.

The aqueous masking dye dispersion of the invention may comprise one dye only or more than one dye. Suitable dyes are commercially available and are typically brown, red or green dyes.

Prevention of age-related macular degeneration (AMD)

The blue edge filter lens of the invention protects the eye from damaging blue light, similar to the eye’s lutein and/or zeaxanthin. Thus, to prevent AMD in the most effective way, the use of blue edge filter lens of the invention is combined with the intake of lutein and/or zeaxanthin.

The intake of lutein and/or zeaxanthin is particularly meaningful if the macular pigment optical density is below average. For measuring macular pigment optical density, a MPS II Macular Pigment Screener (Elektron Eye Technology, Cambridge, UK) can be used.

In one embodiment, the invention relates to a kit comprising glasses and at least one dietary supplement, wherein said dietary supplement comprises lutein and/or zeaxanthin, and wherein said glasses comprise at least one blue edge filter lens according to the invention.

In another embodiment of the invention, the kit comprises glasses having two blue edge filter lenses and a package leaflet, said package leaflet recommending the oral intake of lutein and/or zeaxanthin. In said embodiment, the blue edge filter lenses are preferably blue edge filter lenses according to the invention.

In yet another embodiment of the invention, the kit comprises a dietary supplement and a package leaflet, wherein said package leaflet recommends wearing glasses which protect the eye from damaging blue light protection. In said embodiment, the dietary supplement comprises preferably lutein and/or zeaxanthin. Figures

FIGURE 1 shows the transmission curve of a blue edge filter lens of category 1 (T_v = 73.7%). At 460 nm, the transmittance of the lens is 5.8%. At 490 nm, the transmittance is 7.5 times higher (43.9%). The lens provides for UV protection (transmittance at 380 nm: 0.1 %; transmittance at 400 nm: 0%). The relative visual attenuation quotient Q of the lens is 1.09 for red signal light, 0.85 for blue signal light, 1.07 for yellow signal light and 0.98 for green signal light. Thus, the lens does not impair traffic signal detection. Similar to the previous figure, FIGURE 2 also shows the transmission curve of a blue edge filter lens of category 1 (T_v = 74.9%). However, the edge is less sharp. At 490 nm, the transmittance is 29% only. Thus, the lens of figure 2 is expected to have a higher impact on the human circadian rhythm than the lens of figure 1. Nonetheless, the lens of figure 2 gives excellent protection from bad blue light (transmittance at 450 nm: 1.3%; transmittance at 460 nm: 3.5%).

FIGURE 3 shows the transmission curve of a blue edge filter lens of category 2 (T_v = 23.7%). At 460 nm, the transmittance of the lens is 2.1 %. At 490 nm, the transmittance is 6.5 times higher (13.8%). The lens does not impair traffic signal detection and provides for UV protection (transmittance at 380 nm: 0.1 %; transmittance at 400 nm: 0%). It also protects from the brightness of visible light, in addition to giving protection from UV radiation and from damaging blue light and protection. At 490 nm, transmittance is relatively low. Thus, like any sunglasses, the lens may have an impact on the human circadian rhythm, in particular if worn inside a building over a longer period of time (which is not the prototypical use of sunglasses).

FIGURE 4 shows the transmission curve of a blue edge filter lens of category 3 (Tv = 12.7%). Thus, the lens is darker than the lens of figure 3. At 460 nm, the transmittance of the lens is 1.2%. At 490 nm, the transmittance is 6 times higher (7.2%). The lens provides for UV protection (transmittance at 380 nm: 0.1 %; transmittance at 400 nm: 0%) and does not impair traffic signal detection. At 490 nm, transmittance is low (7.2%). The lens gives triple protection: protection from UV radiation, protection from damaging blue light and protection from the brightness of visible light.

Examples Example 1a (CR-39)

Step a)

An undyed lens made of CR-39 (also known as Columbia resin 39) is provided.

Step b)

An aqueous yellow dye dispersion is provided, said dispersion consisting of 100 ml OPTOChrome 88E gelb (available at Optoconsult GmbH, Bestensee, Germany) and 750 ml deionized water. Said yellow dye dispersion is heated to a temperature of 96°C. The lens of step a) is then submerged into the heated yellow dye dispersion for a duration of 55 minutes. During this tinting process, the yellow dye dispersion is preferably being stirred. The thus obtained lens has a cosmetically unacceptable yellowish color. It is rinsed with deionized water before doing step c).

Step c)

An aqueous masking dye dispersion is provided, said dispersion consisting of 100 ml OPTOChrome 79B Rot4 (available at Optoconsult GmbH, Bestensee,

Germany) and 750 ml deionized water. Said masking dye dispersion is heated to a temperature of 96°C. The lens obtained in step b) is then submerged in the heated masking dye dispersion for a duration of 1.5 minutes. During this tinting process, the masking dye dispersion is preferably being stirred. The transmittance of the thus obtained lens is measured and the masking of the yellow color is checked by visual inspection. Both checks were successful, i.e. the transmission curve and the color of the lens fulfilled the requirements. Thus, there was no need to submerge the lens for a second time in a dye dispersion. Step d)

The lens obtained in step c) is heated to a temperature of 92°C for a duration of 1.5 hours. This fixation step is done in a commercially available oven.

Example 1b (CR-39)

Example 1 a is repeated. This time, however, the lens obtained in step c) is heated to a temperature of 120°C for a duration of 20 minutes only. The thus obtained lens is more stable when exposed to UV light, i.e. the fixation step has been more effective.

Example 2a (MR8)

Step a)

An undyed lens made of MR8 (commercially available at Mitsui Chemicals) is provided. Step b)

To color MR8, activation is needed. Thus, the lens provided in step a) is submerged in commercially available activator liquid OPTOChrome Activator 1.6 klar (available at BOW-Berliner Optik Welt, Germany) for about 10 minutes. An aqueous yellow dye dispersion is provided, said dispersion consisting of 1 18 ml BPI Filter Vision UV Blue Winter Sun (available at Brain Power International Ltd, Warwickshire, England) and 1000 ml deionized water. Said yellow dye dispersion is heated to a temperature of 96°C. The lens is then submerged into the yellow dye dispersion for a duration of 4.5 minutes. During this process, the composition is stirred to prevent the sedimentation. The thus obtained lens has a very bright lemon-yellow color. It is rinsed with deionized water before doing step c).

Step c)

An aqueous masking dye dispersion is provided, said dispersion consisting of 100 ml OPTOChrome 79B Rot4 (available at Optoconsult GmbH, Bestensee, Germany) and 750 ml deionized water. Said masking dye dispersion is heated to a temperature of 96°C. The lens obtained in step b) is then submerged in the heated masking dye dispersion for a duration of 1 minute. During this tinting process, the masking dye dispersion may be stirred. The thus obtained lens had still a cosmetically unacceptable, lemon-yellow color. Thus, step c) was repeated for a second time to obtained a lens with a cosmetically acceptable color. In total, the lens was submerged for about 10 minutes in the masking dye dispersion.

Step d)

Example 2b (MR8)

Example 2a is repeated. This time, however, the lens obtained in step c) is heated to a temperature of 120°C for a duration of 20 minutes only. The thus obtained lens is more stable when exposed to UV light, i.e. the fixation step has been more effective.

Example 3 (brown sunglasses; CR-39)

Example 1 a is repeated. However, in example 3, further dyes are used to provide a darker lens that is suitable for the manufacturing of sunglasses.

Step a)

An undyed lens made of CR-39 (also known as Columbia resin 39) is provided. Step b)

An aqueous yellow dye dispersion is provided, said dispersion consisting of 100 ml OPTOChrome 88E gelb (available at Optoconsult GmbH, Bestensee, Germany) and 750 ml deionized water. Said yellow dye dispersion is heated to a temperature of 95°C. The lens of step a) is then submerged into the heated yellow dye dispersion for a duration of 58 minutes. During this tinting process, the yellow dye dispersion may be stirred.

Step c)

An aqueous masking dye dispersion is prepared as follows: 250 ml Shades Brunex is mixed with 750 ml deionized water. The obtained mixture is then heated to a temperature of 95°C under optional stirring. After having reached said temperature, 100 ml Shades Amethyst is added and thus obtained mixture is heated to a temperature of 95°C under optional stirring. After having reached said temperature, 40 ml Shades Pink is added and thus obtained mixture is heated to a temperature of 95°C under optional stirring. Finally, 40 ml Optoconsult 55D blau is added and the thus obtained mixture is heated to a temperature of 95°C under optional stirring. Thus, a masking dye dispersion is provided which comprises water and multiple dyes. All dyes are commercially available at Cerium Optical Products (Kent, UK) or at

Optoconsult GmbH (Bestensee, Germany).

The lens obtained in step b) is then submerged in the heated masking dye dispersion for a duration of 1.5 minutes for achieving 75% absorption. To achieving 85% absorption, step b) is repeated such that that total duration of tinting step b) is 2.5 minutes. Step d)

The lens obtained in step c) is heated to a temperature of 92°C for a duration of 1 .5 hours.

Example 4 (green sunglasses; CR-39) Example 1 a is repeated. However, in example 4, further dyes are used to provide a greenish lens that is suitable for the manufacturing of sunglasses.

Step a)

Step c)

An aqueous masking dye dispersion is prepared as follows: 250 ml Shades Midnight is mixed with 750 ml deionized water. The obtained mixture is then heated to a temperature of 95°C under optional stirring. After having reached said temperature, 80 ml Shades Black Midnight is added and thus obtained mixture is heated to a temperature of 95°C under optional stirring. After having reached said temperature, 30 ml Shades Brunex is added and thus obtained mixture is heated to a temperature of 95°C under optional stirring. Finally, 8 ml Optoconsult 88E is added and thus obtained mixture is heated to a temperature of 95°C under optional stirring. Thus, a masking dye dispersion is provided which comprises water and multiple dyes. All dyes are

commercially available at Cerium Optical Products (Kent, UK) or at

Optoconsult GmbH (Bestensee, Germany).

The lens obtained in step b) is then submerged in the heated masking dye dispersion for a duration of 2 minutes.

An additional aqueous masking dye dispersion is then prepared, consisting of 100 ml Shades Green (Cerium Optical Products, Kent, UK) and 750 ml deionized water. Said additional aqueous masking dye dispersion is heated to a temperature of 95°C. The lens is then submerged into this additional aqueous masking dye dispersion for a duration of 90 seconds. After this additional tinting step, a green lens is obtained. Fixation of the colors by heating is recommended. Examples 5 and 6 (brown and green sunglasses; MR8)

Examples 3 and 4 are repeated. However, in examples 5 and 6 a lens made of MR8 instead of a lens made of CR-39 is used. Accordingly, the lenses must be activated similar to example 2a before repeating the processes of example 3 and 4, respectively. As a result, a brown (example 5) and a green blue edge filter lens (example 6) having UV protection is obtained. Both lenses are suitable for the manufacture of sunglasses.

Example 1 (manufacturing of glasses)

Several glasses were manufactured. To do so, lenses of examples 1 to 6 were built into commercially available eyeglass frames.

Claims

1. Method of manufacturing a blue edge filter lens, said method

comprising the steps:

b) submerging the lens of step a) in an aqueous yellow dye dispersion, and

c) masking the yellow color of the lens obtained in step b) at least partially by submerging the lens obtained in step b) in an aqueous masking dye dispersion.

2. Method according to claim 1 , further comprising the step:

d) heating the lens obtained in step c) for a duration from 15 minutes to 25 minutes at a temperature from 1 10°C to 130°C.

3. Method according to claim 1 or 2, wherein the transmittance of the lens obtained in step b) and/or step c) is measured at least at 460 nm, and wherein said lens obtained in step b) or step c) is submerged for a second time in the aqueous yellow dye dispersion of step b) in case said lens obtained in step b) or step c) transmits more than 6% of incident light of a wavelength of 460 nm.

4. Method according to any one of claims 1 to 3, wherein the aqueous

masking dye dispersion of step c) comprises red, green and/or blue dye, and wherein said masking dye dispersion comprises preferably at least one red dye.

5. Method according to any one of claims 1 to 4, wherein the lens obtained in step c) is submerged for a second time in the aqueous masking dye dispersion of step c) in case said lens obtained in step c) has a cosmetically unacceptable color.

6. Method according to any one of claims 1 to 5, wherein said undyed lens comprises or consists of at least one thermosetting polymer, and/or wherein said undyed lens comprises or consists of at least one polyurethane or at least one polycarbonate, and wherein said polycarbonate is preferably allyl diglycol carbonate.

7. Blue edge filter lens obtainable by the method according to any one of claims 1 to 6.

8. Blue edge filter lens preferably according to claim 7, wherein said blue edge filter lens transmits less than 6%, preferably less than 5% of light having a wavelength of 460 nm, whereas the transmittance of said blue edge filter lens is at 490 nm preferably at least 5 times higher, more preferably at least 6 times higher than at 460 nm.

9. Blue edge filter lens according to claim 7 or 8, wherein said blue edge filter lens is suitable for night-time driving, and/or wherein said blue edge filter lens is of filter category 0 or 1 , whereas the transmittance of said blue edge filter lens at 490 nm is preferably at least 29%, more preferably at least 35% and most preferably at least 40%.

10. Blue edge filter lens according to claim 7 or 8, wherein said blue edge filter lens does not impair traffic signal detection, and/or wherein said blue edge filter lens is of filter category 2 or 3.

1 1. Blue edge filter lens according to any one of claims 7 to 10, wherein said blue edge filter lens transmits less than 1 % of UV light having a wavelength of 380 nm and/or wherein said blue edge filter lens transmits less than 1 % of UV light having a wavelength of 400 nm.

12. Glasses comprising at least one, preferably at least two blue edge filter lenses according to any one of claims 7 to 11.

13. Kit comprising at least one blue edge filter lens and at least one dietary supplement.

14. Kit according to claim 13, wherein said kit comprises glasses of claim 12, and/or

wherein said at least one dietary supplement comprises lutein and/or zeaxanthin, and/or

wherein said kit comprises a package leaflet which recommends to protect the eyes by wearing glasses with blue edge filter lenses and by taking a dietary supplement which comprises lutein and/or zeaxanthin.

15. Use of a dispersion which comprises red, green and/or blue dye for

masking the yellow color of a blue edge filter lens.