Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
  • G02C7/00—Optical parts
  • G02C7/02—Lenses; Lens systems ; Methods of designing lenses
  • G02C7/04—Contact lenses for the eyes
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F9/00—Methods or devices for treatment of the eyes; Devices for putting in contact-lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
  • A61F9/02—Goggles
  • A61F9/022—Use of special optical filters, e.g. multiple layers, filters for protection against laser light or light from nuclear explosions, screens with different filter properties on different parts of the screen; Rotating slit-discs
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D11/00—Producing optical elements, e.g. lenses or prisms
  • B29D11/00009—Production of simple or compound lenses
  • B29D11/00038—Production of contact lenses

Definitions

• the present invention relates to compositions and methods for the protection of vision from incident electromagnetic radiation using plasmon resonant particles. More particularly, the invention relates to infrared radiation extinguishing eye protection and a process for producing infrared radiation extinguishing eye protection utilizing plasmon resonant particles. Most particularly, the invention relates to infrared radiation extinguishing contact lenses and a process for producing infrared radiation extinguishing contact lenses utilizing optically tunable nanoshells.
• Eye exposure to certain portions of the electromagnetic spectrum is known to be damaging to the cornea and to be the cause of several ocular pathologies. More specifically, while the visible light portion of the spectrum ranges from approximately 400-700 nm, those portions of the energy spectrum adjacent to visible light, namely ultraviolet radiation (approximately 200-400 nm), and infrared radiation (approximately 670-1200 nm) are known to be harmful to the eyes.
• ultraviolet radiation approximately 200-400 nm
• infrared radiation approximately 670-1200 nm
• Devices for protecting the eye from incident light include goggles, glasses, contact lenses and similar devices. Moreover, certain devices have been designed and developed to extinguish ultra-violet, visible, near-infrared or other wavelengths.
• films, reflective surfaces or additives have been used in these devices to alter eye color or appearance by selectively reflecting or absorbing different wavelengths.
• Infrared radiation in solar radiation has a lower level of intensity as well as a lower energy level, and generally is less damaging to the eye or tissue. Higher intensity infrared radiation is most commonly associated with lasers. Moreover, unlike UV-absorbing agents, there are very few substances known to absorb infrared radiation and remain relatively transparent in the visible. Those skilled in the art will understand that while carbon does in fact absorb infrared radiation, it is otherwise undesirable because it also absorbs light from other parts of the energy spectrum, including visible light, therefore reducing the ability to selectively extinguish certain wavelengths while maintaining transmission in other wavelengths. Colored or tinted contact lenses are commonly used to alter eye color for cosmetic reasons, but do not offer selective wavelength protection.
• Tinted lenses employ dyes or other additives to provide color without completely blocking the passage of visible wavelengths through the lens. These techniques are generally designed to avoid coloration of the pupil to create a natural appearance. Examples of these lenses are described in US patent 4,468,229; 4,460,523, 4,447,474; 4,355,135; 4,252,421; 4,157,892; 3,962,505; 3,679,504 and 2,524,811.
• Reflective coatings have also been described to reflect specific wavelengths to provide a color change to the iris of the eye, an example of which is described in US Patent 6,164,777.
• Patent US 4,669,834 describes the use of reflective material to protect the eye from electromagnetic radiation, including infrared wavelengths, wherein such reflective material Included metal particles, such as gold, platinum, stainless steel, silver, nickel, chrome, aluminum, and nickel alloys; other particulate matter, including ground oyster shells and mica.
• the specifications do not provide the optical properties of the materials described, which are well-known to provide the most significant extinction in the visible spectrum. In general, these metal particles have a plasmon resonance and will extinguish light principally in the visible wavelengths.
• US Patent 4,848,894 describes a method for eye protection from high-intensity optical radiation such as that from a laser.
• the invention contemplates the use of thin films, reflectors, filters or absorbing dyes. The degree and wavelength of protection described is inherent in the particular properties of the materials described.
• plasmon resonant particles can contribute significantly to the field of eye protection. While traditional protective techniques have varying levels of stability and selectivity for vision protection, plasmon resonant particles offer the ability to selectively extinguish, either by absorption or scattering, electromagnetic radiation in a broad range of the electromagnetic spectrum. Additionally, these materials can be produced In a biocompatible format to avoid damage to the eye when in close contact, such as in a contact lens format.
• Plasmon resonant particles are generally metallic particles which efficiently scatter optical light elastically because of a collective resonance of the conduction electrons in the metal.
• the magnitude, bandwidth and extinction peak of the plasmon resonance associated with a particle are dependent on the size, shape, structure and composition of the particle.
• the optical properties of a plasmon resonant particle can be significantly different than solid material.
• materials of a particular shape can have significantly different optical properties than materials of a similar shape but different size or of a similar size but different composition or of a similar shape but different composition.
• Plasmon resonant particles are available in many forms.
• One such form is a metal nanoshell, as more fully described in US Patent 6,344,272, incorporated herein by reference.
• plasmon resonant particles Another such form is a nanorod, as described in Journal of Physical Chemistry B, Volume '-OT ⁇ is include stars(Nanoletters, Volume 6, pg. 683 (2006), cubes, elliptical particles, as described in the enormous amount of literature. For a review see Optical Properties of Metal Clusters by Kreibig and Volmer, Springer-Verlag (1995).
• a common trait of plasmon resonant particles is the ability to manufacture such particles to have desired optical properties, including extinguishment of electromagnetic radiation in various parts of the spectrum.
• protective eyewear may be comprised of plasmon resonant particles selected from among various sizes, shapes and compositions.
• a contact lens must be functional and biocompatible, with different requirements than goggles or glasses.
• the appropriate characteristics of a good contact lens include oxygen permeability, wettability, material strength, and stability. These factors must be carefully balanced to achieve a useable contact lens. Oxygen permeability is paramount since the cornea receives its oxygen supply exclusively from contact with the atmosphere. Tear fluid wettability keeps the contact lubricated, allowing it to be worn comfortably on the eye.
• Contact lenses are typically hydrogels, a hydrated crosslinked polymeric system that contains water in an equilibrium state. In general, as the water content increases, the oxygen permeability also increases. These hydrogels are typically comprised of copolymers of N-vinyl-pyrolidone and methyl methacrylate, which have water content in the 70-80% range.
• any modification to a contact lens to provide infrared wavelength protection must not alter the biocompatibility, wettability, or oxygen permeability.
• any embedded material must be stable, not oxidize, and be easily embedded in a polymeric system.
• the present invention relates to compositions and methods for the protection of vision from incident electromagnetic radiation using plasmon resonant particles.
• the varying optical properties of plasmon resonant particles are used to selectively absorb or extinguish wavelengths in eyewear to minimize damage to the eyes from incident electromagnetic radiation.
• the desired parameters of vision protection can be determined through the selection from among plasmon resonant particles with different properties, the engineering design of such particles, the composition of mixtures of such particles, and the density of such particles within the device. Each of these is a controllable parameter that may be altered to select the desired level of vision protection from a specified wavelength.
• the eyewear may be goggles, glasses, contact lenses or the like. Such device could also be an implant.
• the invention relates to infrared radiation extinguishing eyewear, and more particularly, to contact lenses and a process for producing infrared radiation extinguishing contact lenses utilizing plasmon resonant particles.
• the plasmon resonant particles are optically tunable nanoshells.
• the invention relates to the addition of plasmon resonant particles to dyes, films or other additives or layers to provide additional protection to existing eyewear devices.
• Plasmon resonant particles in general, and nanoshells in particular, may be designed and consistently manufactured with peak plasmon resonances at desired wavelengths, including the near-infrared.
• a nanoshell is a nanoparticle consisting of a dielectric core and a metal shell. Plasmon resonance frequency is determined by the relative size of the core and the metal shell. With the capability to alter the relative size of the core and the metal shell, nanoshells are uniquely tunable nanoparticles, allowing a range of optical extinctions.
• the nanoshells may be fabricated in order to absorb other energy wavelengths, or other plasmon resonant particles may be fabricated to absorb infrared wavelengths.
• Contact lenses are manufactured by spincasting processes, cast molding processes, or a combination of these two methods.
• the plasmon resonant particles are introduced into the lens polymer prior to the particular lens manufacturing process.
• the plasmon resonant particles are coated on a contact lens after formation of the lens. The varying optical properties of plasmon resonant particles are used to selectively absorb or extinguish wavelengths to minimize damage to the eye from incident electromagnetic radiation.
• the desired parameters of vision protection can be determined through the selection from among plasmon resonant particles with different properties, the engineering design of such particles, the composition of mixtures of such particles, and the density of such particles within the device. Each of these is a controllable parameter that may be altered to select the desired level of vision protection from a specified wavelength.
• Fig. 1 illustrates the optical shift in a nanoshell based on the ratio of shell thickness to core size for a particular nanoshell size and composition.
• Fig. 2 illustrates the high correlation between predicted and observed optical properties for a nanoshell of specified dimensions and materials.
• Fig 3 illustrates the extinction of various concentrations and pathlengths of nanoshells confirming Lambert-Beer's Law for the pathlengths and nanoshell concentrations.
• Fig 4 illustrates the percent transmission of the nanoshell solution shown in Fig. 1 taken in a 0.2 mm pathlength cuvette.
• N * 8 " • ' ⁇ '' Ay ;;: 4"' l i! ⁇ syyi ; ' l fn i e : " 1 exiinction spectra of three different core-radii nanoshell compositions immersed in water as compared to the same particles :functionalized with PVP and dispersed in ethanol.
• Fig. 6 illustrates the extinction spectra of the: nanoshell solution from Fig. 1 dispersed in water versus the same nanoshells dispersed in HEMA, a common contact lens monomer.
• Fig. 7 illustrates the spectra and photographic images of two nanoshell-embedded contact lens prototypes.
• Fig. 8 illustrates the clarity of a digital camera image taken partially through the 0.3 mm contact lens described in Figure 7 as compared to the portion of the photo taken through air.
• Fig. 9 is a graphical illustration of the performance of nanoshell embedded soft contact lens.
• Nanoparticles and materials formed therefrom constitute an emerging subdiscipline in the chemical and materials science arts. While there is no universally agreed upon definition of when a small particle qualifies as a nanoparticle, particles with at least one dimension (d) ⁇ 100 nm are generally considered nanoparticles.
• nanoparticles includes particles with one dimension less than a micron.
• the most desirable nanoshells are » 100 nm.
• those skilled in the art generally acknowledged that various properties of a material PC chaTng/eU asS theO paBrti/cleJ. siBzeO apEpr3oac,hes mol,ecu.lar d,i.mensions. It is these unique properties of the nanomaterial that make it useful for various applications.
• solid metal nanoparticles i.e. solid, single metal spheres of uniform composition and nanometer dimensions
• metal nanoparticles especially the coinage metals
• This so-called plasmon resonance is due to the collective coupling of the conduction electrons in the metal sphere to the incident electromagnetic field. This resonance can be dominated by absorption or scattering depending on the dimensions of the nanoparticle with respect to the wavelength of the incident electromagnetic radiation.
• a strong local field enhancement in the interior of the metal nanoparticle is associated with this plasmon resonance.
• a serious practical limitation to realizing many applications of solid metal nanoparticles is the inability to position the plasmon resonance at technologically important wavelengths.
• Solid nanoparticles such as gold and silver, absorb light in the optical regions of the human.
• solid gold nanoparticles of 10 ran in diameter have a plasmon resonance centered approximately at 520 nm. This plasmon resonance cannot be controllably shifted by more than approximately 100 nanometers by varying the particle diameter or the specific embedding medium.
• nanoparticles A new class of nanoparticles has recently emerged wherein a non-conducting inner layer is coated with a layer of conducting material, thereby forming a conducting shell around a non-conducting core. These materials may be spherical, ellipsoidal, or other shapes. These nanoparticles are referred to as nanoshells and have been demonstrated to have capabilities of absorbing electromagnetic radiation maximally at wavelengths in the visible or infrared regions of the electromagnetic spectrum.
• nanoshells are formed of a silica core and a gold or silver shell. Moreover, the ratio of shell thickness to core size dictates the optical shift or absorption capabilities of the nanoshell. In a concentric geometry such as a nanoshell, this absorption is shifted to higher wavelengths.
• nanoshells have dynamic optical extinctions that can be tuned as desired.
• gold and silver nanoshells can be fabricated that will absorb or scatter light at various wavelength along the electromagnetic spectrum, particularly in the visible and infrared regions.
• Fig. 1 illustrates a nanoshelFs optical shift as the ratio of shell thickness to core size is altered.
• a 120 run diameter silica core is utilized. Different shell thicknesses ranging from 20 nm to 5 nm are shown. Keeping the core diameter constant, as the shell thickness decreases, the plasmon resonance peak shifts from lower frequency wavelengths to higher frequency wavelengths along the energy spectrum.
• the bar on the left illustrates the very narrow band of wavelengths extinguished by solid metal nanoparticles.
• the plasmon resonance of metal nanoshells is governed by Mie scattering theory.
• Mie scattering has accurately described the plasmon resonance of gold nanoshells, silver nanoshells, and electromagnetic contributions to the surface enhanced Raman response.
• the plasmon resonance of a core shell structure is determined by the physical dimensions and the optical dielectric properties of the core, shell, and medium.
• Fig. 2 shows a calculated Mie scattering spectrum (dashed line) and the corresponding measured spectrum of an "off the shelf nanoshell solution (solid line) characterized by UV/VIS spectra of a gold nanoshell solution with a silica core radius of 58 nm and a 13 nm gold shell dispersed in water.
• the correlation between the measured and calculated optical response of nanoshells has been verified extensively.
• this nanoshell effectively filters P C ouIt ⁇ 750lU-90S0i n OmB w. /hiJlel. a 0llo0w0ing3 opti .ca ,l c ,lari .ty.
• the optical properties of a particular nanoshell can be predicted during the design phase.
• gold and silver nanoshells can be reproducibly fabricated with a silica core ranging from 80-500 nm in diameter with shell thickness ranging from 7-35 nm. As illustrated by Fig. 1, this allows for a tuning range from 630-2500 nm, covering the visible and infrared regions of the electromagnetic spectrum.
• the use of other materials will allow nanoshells of different dimensions, with diameters smaller than 80 nm, and with extinction properties ranging from the visible through far infrared.
• the outer shell of a nanoshell utilized in the invention is formed of gold.
• Gold nanoshells are uniquely suited for laser eye protection in a contact lens format. Gold is biocompatible, so there are no toxicity concerns, and gold nanoshells have a characteristic dip in the plasmon resonance at the maximum efficiency of the human eye. Further, the optical cross-section of a particular nanoshell may be significantly larger than the physical cross- section at the plasmon resonance peak in the near-infrared, allowing the particle to absorb significant light relative to dyes and other particles.
• other plasmon resonant particles can provide similar optical shifts.
• nanorods when linearly polarized light is aligned along the long axis of the rod, can absorb near-infrared wavelengths.
• nanoshells as a spherical material, avoid the concerns inherent in attempting to achieve infrared protection with polarization dependence.
• “hollow” nanoparticles have been produced that have similar optical properties. See “Metal nanostrcutures with hollow interiors", Sun, YG; Mayers, B;Xia, YN, ADVAN MATER, Volume: 15, April 17, 2003, pages 641-646. These materials may be spherical or other shapes.
• the disks are manufactured by spincasting processes, cast molding processes, or a combination of these two methods.
• the blanks are formed from the polymerization of the monomers.
• the nanoshells are deposited in the polymers for contact lenses.
• the nanoshells are manufactured as usual, and then functionalized with polyvinylpyrrolidone (PVP) or polyvinylalcohol (PVA). These coatings create a protective layer of the nanoshells that allows them to be centrifuged and redispersed into organic solvents, such as ethanol or toluene, and saline. See Fig. 5.
• nanoshells were dispersed in 2-hydroxyethylmethacrylate (HEMA), a popular monomer in the contact lens manufacturing process, without the use of a protective PVP or PVA layer.
• HEMA 2-hydroxyethylmethacrylate
• the nanoshell concentration can easily be adjusted to compensate for different lens thickness, and hence different contact lens prescriptions, or desired thickness with no prescription.
• the foregoing is preferred because the plasmon resonant nanoshell can easily be incorporated into the current manufacturing processes of contact lenses that are based on polymer technologies.
• the nanoshells are incorporated prior to the implementation of the cutting and lathing process, there is only minimal modification to manufacturing.
• the foregoing invention is also economically feasible.
• the physical amount of gold in a nanoshell solution is extremely small. While higher concentrated solutions and greater extinction are feasible, in one desired embodiment, the concentration of nanoshells is less than 0.15% by volume.
• one nanoshell solution has a silica core radius of 151 nm and a 17 nm thick gold shell. Given a relatively large contact lens blank of 14.5 mm diameter and 1 cm thickness, to achieve a desired nanoshell optical density, the nanoshell concentration is 5.5xlO 10 particles/ml. This contact lens would be 0.11% nanoshells by volume. Thus, the cost of gold in this contact lens blank is negligible.
• Nanoshells have the added benefit that they remain stable in a saline environment in a similar fashion via polyvinylalcohol (PVA) with minimal effect on the plasmon resonance.
• PVA polyvinylalcohol
• the standard method for manufacturing soft contact lenses following the initial polymerization and cutting is to soak the contact lens in a saline solution. Contact lenses are also stored in a saline solution.
• each nanoshell has an extinguishing curve that can be characterized by a peak and a trough, which can be expressed as a peak to trough ratio.
• the peak to trough ratios of typical nanoshell solutions varies from 2 to 7.
• a higher peak to trough ratio allows the maximum protection in the near-infrared regions and the maximum transmission in the visible spectrum.
• the peak-to-trough ratio increases as the core radius increases, and the resultant plasmon resonance moves towards the infrared.
• ti ⁇ e p"eak-to-trbugn' ratio ' decreases with increasing shell thickness, and the plasmon resonance moves towards the visible.
• the peak-to-trough ratio and the plasmon resonance shift are more sensitive to core radius changes than shell thickness changes. Given this trend, the peak-to-trough ratio of the nanoshell responsible for blocking the 670-850 run range will determine the overall transmission in the visible range of the human eye.
• the peak to trough ratio of a nanoshell having a silica core radius of ⁇ 151 nm and a gold shell thickness of 17 nm yields a peak-to-trough ratio that extinguished the 670-850 nm range.
• the extinction cross-section (in m ) can also be calculated as a function of core radius and shell thickness.
• the optimal nanoshell for a partial region of the energy spectrum, regardless of concentration (since altering the concentration moves the entire curve up and down) is as follows:
• the optimal nanoshell for extinguishing the light from 670-850 nm wavelength, while allowing the most transmittance in the visible range of 400-670 nm has a core radius of 150 nm and a shell thickness of 17 nm, an example of this is shown in Fig. 4.
• the optimal nanoshell for extinguishing the light from 1030- 1200 nm, while allowing the most transmittance in the visible range of 400-670 nm has a core radius of 370 nm and a shell thickness of 15 nm. In one embodiment, the optimal nanoshell for extinguishing the light from 850-1030 nm, while allowing the most transmittance in the visible range of 400-670 nm, has a core radius of 300 nm and a shell thickness of 17 nm.
• suitable core radius' range from 58 to 215 nm with varying shell thicknesses.
• the nanoshells are deposited on at least one surface of the manufactured lens, or alternatively, on both the front and back surfaces of the lens. " Those s ' kme ' ⁇ in " the art ' will appreciate that this method is less desirable because it adds and additional step to the manufacturing process.
• a contact lens is typically 0.19 mm to 0.4 mm thick.
• Cuvettes with 0.2 mm and 0.5 mm pathlengths were used. Using these cuvettes, as well as our standard 1 cm pathlength cuvettes, the optical response of the same nanoshell solution as described in Fig. 1 , with different concentrations, was used to test the Lambert-Beer absorption law. The results are shown in Fig. 3.
• the optical characteristics of the nanoshells demonstrated in Fig. 1 were measured in 0.2 mm and 0.5 mm pathlength cuvettes (typical contact lens thickness) to determine the appropriate nanoshell concentration.
• the percent transmission of the 0.2 mm cuvette is shown in Fig. 4.
• the desired concentrations were determined to be 5.5xl0 ⁇ 10 nanoshell/ml and 2.21xl0 ⁇ 10 nanoshells/ml for the 0.2 mm and 0.5 mm pathlength cuvettes, respectively, which achieved extinction of greater than 95% in the near-infrared spectrum. These concentrations represent less than 0.15% by volume of nanoshells. Higher concentrated solutions and greater extinction are feasible. These measurements were taken from nanoshell solution dispersed in water.
• nanoshells were manufactured as usual, and then functionalized with polyvinylpyrrolidone (PVP) or polyvinylalcohol (PVA). These coatings create a protective layer of the nanoshells that allows them to be centrifuged and redispersed into organic solvents, such as ethanol or toluene, and saline. This process is demonstrated in Fig. 5.
• PVP polyvinylpyrrolidone
• PVA polyvinylalcohol
• HEMA 2-hydroxyethylmethacrylate
• FIG. 7 is a photo taken through the 0.3 mm contact lens, illustrating clarity.
• Fig. 9 illustrates the flexibility of production of contact lenses using plasmon resonant particles, using 530 nm in the visible (the wavelength of high sensitivity of the human eye) and -850 nm in the near infrared. As illustrated in Fig. 9, to achieve 30% transmission at 530nm, 99% protection at the 850 nm wavelength can be achieved. 90% protection at this wavelength would result in approximately 60% transmission. Similar comparison can be made from this graphical illustration.
• the foregoing tunable nanoshell-based contact lens as described herein blocks harmful wavelengths while allowing high luminescence in visible spectra.
• the lenses are particularly useful in delivering protection in the region of 670 nm to 1200 nm. Additionally, these plasmon resonant nanostructures embedded in a contact lens will have no haze, distortion, aberration, prism, or artifacts that impair visual performance or create distractions the visual field.
• the performance of the lens can be adjusted to meet the customer specifications, within the limits of the intrinsic properties of the materials.
• the concentration of the nanoshells can easily be increased to block >99% in the infrared region, while remaining relatively transparent in the visible range, wherein the transmission exceeds that of an average pair of sunglasses.
• Nanoshells have been demonstrated to be relatively inexpensive to manufacture and have a high safety profile when used in vivo. This is particularly true of gold nanoshells.

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  • 2006-05-10 JP JP2009509525A patent/JP2009536549A/ja active Pending
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