Patent Application
20110157546
The present invention relates to an ophthalmic system. More particularly, the invention relates to an ophthalmic system that performs blocking of blue light wavelengths (hereafter, “blue blocking”) in ophthalmic lenses, while presenting a cosmetically attractive product. “Ophthalmic system” as used here includes prescription or non-prescription ophthalmic lenses used, e.g., for glasses (or spectacles), sunglasses, contact lenses, intra-ocular lenses or corneal inlays, and treated or processed or combined with other components to provide desired functionalities described in further detail in the following.
Current research strongly supports the premise that short wavelength visible light (blue light) having a wavelength of approximately 400 nm-500 nm (nanometers or 10.sup.-9 meters) could be a contributing cause of AMD (age related macular degeneration). It is believed that the highest level of blue light absorption occurs at or near 450 nm. Research further suggests that blue light worsens other causative factors in AMD, such as heredity, tobacco smoke, and excessive alcohol consumption.
Light is made up of electromagnetic radiation that travels in waves. The electromagnetic spectrum includes radio waves, millimeter waves, microwaves, infrared, visible light, ultra-violet (UVA and UVB) and x-rays and gamma rays. The human retina responds only to the visible light portion of the electromagnetic spectrum. The visible light spectrum includes the longest visible light wavelength spectrum. The visible light spectrum includes the longest visible light wavelength of approximately 700 nm and the shortest of approximately 400 nm. Blue light wavelengths fall in the approximate range of 400 nm to 500 nm. For the ultra-violet bands, UVB wavelengths are from 290 nm to 320 nm and UVA wavelengths are from 320 nm to 400 nm.
The human retina includes multiple layers. These layers listed in order from the first exposed to any light entering the eye to the deepest include:
1) Nerve Fiber Layer
2) Ganglion Cells
3) Inner Plexiform Layer
4) Bipolar and Horizontal Cells
5) Outer Plexiform Layer
6) Photoreceptors (Rods and Cones)
7) Retinal Pigment Epithelium (RPE)
8) Bruch's Membrane
9) Choroid
When light is absorbed by the eye's photoreceptor cells, (rods and cones) the cells bleach and become unreceptive until they recover. This recovery process is a metabolic process and is called the “visual cycle.” Absorption of blue light has been shown to reverse this process prematurely. This premature reversal increases the risk of oxidative damage and is believed to lead to the buildup of the pigment lipofuscin in the retina. This build up occurs in the retinal pigment epithelium (RPE) layer. It is believed that aggregates of extra-cellular materials called drusen are formed in the RPE layer due to the excessive amounts of lipofuscin. Drusen hinder or block the RPE layer from providing the proper nutrients to the photoreceptors, which leads to damage or even death of these cells. To further complicate this process it appears that when lipofuscin absorbs blue light in high quantities it becomes toxic, causing further damage and/or death of the RPE cells.
The lighting and vision care industries have standards as to human vision exposure to UVA and UVB radiation Surprisingly, no such standard is in place with regard to blue light. For example, in the common fluorescent tubes available today, the glass envelope mostly blocks ultra-violet light but blue light is transmitted with little attenuation. In some cases, the envelope is designed to have enhanced transmission in the blue region of the spectrum.
Ophthalmic systems that provide blue blocking to some degree are known. However, there are disadvantages associated with such systems. For example, they tend to be cosmetically unappealing because of a yellow or amber tint that is produced in lenses by blue blocking More specifically, one common technique for blue blocking involves tinting or dyeing lenses with a blue blocking tint, such as BPI Filter Vision 450 or BPI Diamond Dye 500. The tinting may be accomplished, for example, by immersing the lens in a heated tint pot containing a blue blocking dye solution for some predetermined period of time. Typically, the dye solution has a yellow or amber color and thus imparts a yellow or amber tint to the lens. To many people, the appearance of this yellow or amber tint may be undesirable cosmetically. Moreover, the tint may interfere with the normal color perception of a lens user, making it difficult, for example, to correctly perceive the color of a traffic light or sign.
Efforts have been made to compensate for the yellowing effect of blue blocking For example, blue blocking lenses have been treated with additional dyes, such as blue, red or green dyes, to offset the yellowing effect. The treatment causes the additional dyes to become intermixed with the original blue blocking dyes. However, while this technique may reduce yellow in a blue blocked lens, it also reduces the effectiveness of the blue blocking by allowing more of the blue light spectrum through. Moreover, the technique may reduce the overall transmission of light wavelengths other than blue light wavelengths. This unwanted reduction may in turn result in reduced visual acuity for a lens user.
In view of the foregoing, there is a pressing need for an ophthalmic lens that will perform blue blocking with an acceptable level of blue light protection, while providing for acceptable color cosmetics, acceptable color perception for a user, and an acceptable level of light transmission for wavelengths other than blue light wavelengths.
Embodiments of the present invention relate to an ophthalmic system that performs effective blue blocking while at the same time providing a cosmetically attractive product, normal or acceptable color perception for a user, and a high level of transmitted light for good visual acuity.
More specifically, embodiments of the invention may provide effective blue blocking in combination with color balancing. “Color balancing” or “color balanced” as used herein means that the yellow or amber color, or other unwanted effect of blue blocking is reduced, offset, neutralized or otherwise compensated for so as to produce a cosmetically acceptable result, without at the same time reducing the effectiveness of the blue blocking. For example, wavelengths at or near 450 nm may be blocked or reduced in intensity. In particular, for example, wavelengths between about 440 nm to about 460 nm may be blocked or reduced in intensity. Furthermore, transmission of unblocked wavelengths may remain at a high level, for example at least 85%. Additionally, to an external viewer, the ophthalmic system may look clear or mostly clear. For a system user, color perception may be normal or acceptable.
An ophthalmic system according to embodiments of the present invention may comprise a blue blocking component posterior to a color-balancing component. Either of the blue blocking component or the color balancing component may be, or form part of, an ophthalmic component such as a lens. In other embodiments, the posterior blue blocking component and anterior color balancing component may be distinct layers on or adjacent to or near a surface or surfaces of an ophthalmic lens. Because the blue blocking component is posterior to the color balancing component, it will always be oriented with respect to a user so that incident light first strikes the color balancing component, before passing through the blue blocking component to be received by the user's eyes. The color-balancing component may reduce or neutralize a yellow or amber tint of the posterior blue blocking component, to produce a cosmetically acceptable appearance. For example, to an external viewer, the ophthalmic system may look clear or mostly clear. For a system user, color perception may be normal or acceptable. Further, because the blue blocking and color balancing tints are not intermixed, wavelengths in the blue light spectrum may be blocked or reduced in intensity and the transmitted intensity of incident light in the ophthalmic system may be at least 85% for unblocked wavelengths.
As discussed previously, techniques for blue blocking are known. The known techniques to block blue light wavelengths include absorption, reflection, interference, or any combination thereof. As discussed earlier, according to one technique, a lens may be tinted/dyed with a blue blocking tint, such as BPI Filter Vision 450 or BPI Diamond Dye 500, in a suitable proportion or concentration. The tinting may be accomplished, for example, by immersing the lens in a heated tint pot containing a blue blocking dye solution for some predetermined period of time. According to another technique, a filter is used for blue blocking The filter could include, for example, organic or inorganic compounds exhibiting absorption and/or reflection of and/or interference with blue light wavelengths. The filter could comprise multiple thin layers or coatings of organic and/or inorganic substances. Each layer may have properties, which, either individually or in combination with other layers, absorbs, reflects or interferes with light having blue light wavelengths. Rugate notch filters are one example of blue blocking filters. Rugate filters are single thin films of inorganic dielectrics in which the refractive index oscillates continuously between high and low values. Fabricated by the co-deposition of two materials of different refractive index (e.g. SiO.sub.2 and TiO.sub.2), rugate filters are known to have very well defined stop-bands for wavelength blocking, with very little attenuation outside the band. The construction parameters of the filter (oscillation period, refractive index modulation, number of refractive index oscillations) determine the performance parameters of the filter (center of the stop-band, width of the stop band, transmission within the band). Rugate filters are disclosed in more detail in, for example, U.S. Pat. No. 6,984,038, which is fully incorporated herein by reference. Another technique for blue blocking is the use of multi-layer dielectric stacks. Multi-layer dielectric stacks are fabricated by depositing discrete layers of alternating high and low refractive index materials. Similarly to rugate filters, design parameters such as individual layer thickness, individual layer refractive index, and number of layer repetitions determine the performance parameters for multi-layer dielectric stacks.
Color balancing according to embodiments of the invention may comprise imparting, for example, a suitable proportion or concentration of blue tinting/dye, or a suitable combination of red and green tinting/dyes to the color-balancing component, such that when viewed by an external observer, the ophthalmic system as a whole has a cosmetically acceptable appearance. For example, the ophthalmic system as a whole may look clear or mostly clear.
The surface cast layer may be formed on the convex side of the single vision lens, wafer or optical pre-form. Since the single vision lens, wafer or optical pre-form has been tinted or dyed to perform blue blocking, it may have a yellow or amber color that is undesirable cosmetically. Accordingly, the surface cast layer may, for example, be tinted with a suitable proportion of blue tinting/dye, or a suitable combination of red and green tinting/dyes.
The surface cast layer may be treated with color balancing additives after it is applied to the single vision lens, wafer or optical pre-form that has already been processed to make it blue blocking. For example, the blue blocking single vision lens, wafer or optical pre-form with the surface cast layer on its convex surface may be immersed in a heated tint pot which has the appropriate proportions and concentrations of color balancing dyes in a solution. The surface cast layer will take up the color balancing dyes from the solution. To prevent the blue blocking single vision lens, wafer or optical pre-form from absorbing any of the color balancing dyes, its concave surface may be masked or sealed off with a dye resist, e.g. tape or wax or other coating. This is illustrated in
It should be understood that the surface cast layer could be used in combination with a multi-focal, rather than a single vision, lens, wafer or optical pre-form. In addition, the surface cast layer could be used to add power to a single vision lens, wafer or optical pre-form, including multi-focal power, thus converting the single vision lens, wafer or optical pre-form to a multi-focal lens, with either a lined or progressive type addition. Of course, the surface cast layer could also be designed to add little or no power to the single vision lens, wafer or optical pre-form.
Referring now to
Referring now to
Any of the above-described embodiments of the present invention, or embodiments not explicitly disclosed herein, may be combined with one or more anti-reflective (AR) components. This is shown in
Further embodiments of the present invention are illustrated in
In
In
As discussed previously, filters are one technique for blue blocking. Accordingly, any of the blue blocking components discussed could be or include or be combined with blue blocking filters. Such filters may include rugate filters, interference filters, band-pass filters, band-block filters, notch filters or dichroic filters.
In other embodiments of the invention, one or more of the above-disclosed blue-blocking techniques may be used in conjunction with other blue-blocking techniques. By way of example only, a lens or lens component may utilize both a dye/tint and a rugate notch filter to effectively block blue light.
Any of the above-disclosed structures and techniques may be employed in an ophthalmic system according to the present invention to perform blocking of blue light wavelengths at or near 450 nm. For example, in embodiments the wavelengths of blue light blocked may be within a predetermined range centered at 450 nm. In embodiments, the range may extend from 450 nm±(plus or minus) about 10 nm (i.e., between about 440 nm and about 460 nm). In other embodiments, the range may extend from 450 nm±about 20 nm (i.e., between about 430 nm and about 470 nm). In still other embodiments, the range may extend from 450 nm±about 30 nm (i.e., between about 420 nm and about 480 nm). In still other embodiments, the range may extend from 450 nm±about 40 nm (i.e., between about 410 nm and about 490 nm). In still other embodiments, the range may extend from 450 nm±about 50 nm (i.e., between about 400 nm and about 500 nm). In embodiments, the ophthalmic system may limit transmission of blue wavelengths within the above-defined ranges to substantially 90% of incident wavelengths. In other embodiments, the ophthalmic system may limit transmission of the blue wavelengths within the above-defined ranges to substantially 80% of incident wavelengths. In other embodiments, the ophthalmic system may limit transmission of the blue wavelengths within the above-defined ranges to substantially 70% of incident wavelengths. In other embodiments, the ophthalmic system may limit transmission of the blue wavelengths within the above-defined ranges to substantially 60% of incident wavelengths. In other embodiments, the ophthalmic system may limit transmission of the blue wavelengths within the above-defined ranges to substantially 50% of incident wavelengths. In other embodiments, the ophthalmic system may limit transmission of the blue wavelengths within the above-defined ranges to substantially 40% of incident wavelengths. In still other embodiments, the ophthalmic system may limit transmission of the blue wavelengths within the above-defined ranges to substantially 30% of incident wavelengths. In still other embodiments, the ophthalmic system may limit transmission of the blue wavelengths within the above-defined ranges to substantially 20% of incident wavelengths. In still other embodiments, the ophthalmic system may limit transmission of the blue wavelengths within the above-defined ranges to substantially 10% of incident wavelengths. In still other embodiments, the ophthalmic system may limit transmission of the blue wavelengths within the above-defined ranges to substantially 5% of incident wavelengths. In still other embodiments, the ophthalmic system may limit transmission of the blue wavelengths within the above-defined ranges to substantially 1% of incident wavelengths. In still other embodiments, the ophthalmic system may limit transmission of the blue wavelengths within the above-defined ranges to substantially 0% of incident wavelengths. Stated otherwise, attenuation by the ophthalmic system of the electromagnetic spectrum at wavelengths in the above-specified ranges may be at least 10%; or at least 20%; or at least 30%; or at least 40%; or at least 50%; or at least 60%; or at least 70%; or at least 80%; or at least 90%; or at least 95%; or at least 99%; or substantially 100%.
At the same time as wavelengths of blue light are selectively blocked as described above, at least 85%, and in other embodiments at least 95%, of other portions of the electromagnetic spectrum may be transmitted by the ophthalmic system. Stated otherwise, attenuation by the ophthalmic system of the electromagnetic spectrum at wavelengths outside the blue light spectrum, e.g. wavelengths other than those at or near 450 nm may be 15% or less, and in other embodiments, 5% or less.
Additionally, embodiments of the present invention may further block ultra-violet radiation the UVA and UVB spectral bands as well as infra-red radiation with wavelengths greater than 700 nm.
Any of the above-disclosed ophthalmic system may be incorporated into an article of eyewear, including externally-worn eyewear such as eyeglasses, sunglasses, goggles or contact lenses. In such eyewear, because the blue-blocking component of the systems is posterior to the color balancing component, the blue-blocking component will always be closer to the eye than the color-balancing component when the eyewear is worn. The ophthalmic system may also be used in such articles of manufacture as surgically implantable intra-ocular lenses.
Several embodiments of the invention are specifically illustrated and/or described herein. However, it will be appreciated that modifications and variations of the invention are covered by the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11378317 | Mar 2006 | US |
| Child | 13014483 | US |
