Polymeric material for accommodating intraocular lenses

Abstract

The disclosure relates generally to a polymeric material for use in accommodating intraocular lenses for implantation in a lens chamber of a subject's eye. The present disclosure is directed to a polymeric material which comprises a fluorosilicone polymer and a silica component. The presently disclosed polymeric material is both optically clear and has a sufficiently low Young's modulus such that it can effectively respond to the eye's natural accommodative forces and thus can be used in accommodating intraocular lenses. When used in the fabrication of an intraocular lenses, the polymeric material disclosed herein protect the physical characteristics of the lens as the added hydrophobicity of the fluorosilicone polymer allows it to effectively resist diffusion of fluid from the eye and the adhesion of biologica materials.

Description

FIELD

The disclosure relates generally to a polymeric material for use in accommodating intraocular lenses for implantation in a lens chamber of a subject's eye.

BACKGROUND

Surgical procedures on the eye have been on the rise as technological advances permit for sophisticated interventions to address a wide variety of ophthalmic conditions. Patient acceptance has increased over the last twenty years as such procedures have proven to be generally safe and to produce results that significantly improve patient quality of life.

Cataract surgery remains one of the most common surgical procedures, with over 16 million cataract procedures being performed worldwide. It is expected that this number will continue to increase as average life expectancies continue to rise. Cataracts are typically treated by removing the crystalline lens from the eye and implanting an intraocular lens (“IOL”) in its place. As conventional IOL devices are primarily focused for distance visions, they fail to correct for presbyopia and reading glasses are still required. Thus, while patients who undergo a standard IOL implantation no longer experience clouding from cataracts, they are unable to accommodate, or change focus from near to far, from far to near, and to distances in between.

Surgeries to correct refractive errors of the eye have also become extremely common, of which LASIK enjoys substantial popularity with over 700,000 procedures being performed per year. Given the high prevalence of refractive errors and the relative safety and effectiveness of this procedure, more and more people are expected to turn to LASIK or other surgical procedures over conventional eyeglasses or contact lenses. Despite the success of LASIK in treating myopia, there remains an unmet need for an effective surgical intervention to correct for presbyopia, which cannot be treated by conventional LASIK procedures.

As nearly every cataract patient also suffers from presbyopia, there is convergence of market demands for the treatment of both these conditions. While there is a general acceptance among physicians and patients of having implantable intraocular lens in the treatment of cataracts, similar procedures to correct for presbyopia represent only 5% of the U.S. cataract market. There is therefore a need to address both ophthalmic cataracts and/or presbyopia in the growing aging population.

SUMMARY

The present disclosure is directed to a polymeric material which comprises a fluorosilicone polymer and a silica component. The presently disclosed polymeric material is both optically clear and has a sufficiently low Young's modulus such that it can effectively respond to the eye's natural accommodative forces and thus can be used in accommodating intraocular lenses. When used in the fabrication of an intraocular lenses, the polymeric material disclosed herein protect the physical characteristics of the lens as the added hydrophobicity of the fluorosilicone polymer allows it to effectively resist diffusion of fluid from the eye and the adhesion of biological materials.

Accordingly, in one aspect, provided herein is a polymeric material comprising a fluorosilicone polymer and up to about 30 weight % of a silica component, wherein the silica component has a surface area of at least about 280 m²/g.

In another aspect, provided herein is an implantable intraocular lens (IOL) comprising a polymeric material comprising a fluorosilicone polymer and up to about 30 weight % of a silica component, wherein the silica component has a surface area of at least about 280 m²/g.

In still another aspect, provided herein is an intraocular lens (IOL) device comprising a fluorosilicone polymer and up to about 30 weight % of a silica component, wherein the silica component has a surface area of at least about 280 m²/g. In one aspect, the intraocular lens (IOL) device comprises

(a) a first lens comprised of a fluorosilicone polymer and up to about 30 weight % of a silica component, wherein the silica component has a surface area of at least about 280 m²/g having a first Young's modulus;

(b) a second lens in spaced relation to the first lens along a central optical axis; and

(c) a circumferential portion encircling the first and second lens, the circumferential portion comprising an outer peripheral edge;

wherein at least one of a portion of the second lens and a portion of the circumferential portion is made of a material having a second Young's modulus; and wherein the first Young's modulus is less than the second Young's modulus.

Other objects, features and advantages of the described embodiments will become apparent to those skilled in the art from the following detailed description. It is to be understood, however, that the detailed description and specific examples, while indicating various embodiments of the present invention, are given by way of illustration and not imitation. Many changes and modifications within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications.

DETAILED DESCRIPTION

Specific, non-limiting embodiments of the present invention will now be described with reference to the drawings. It should be understood that such embodiments are by way of example and are merely illustrative of but a small number of embodiments within the scope of the present invention. Various changes and modifications obvious to one skilled in the art to which the present invention pertains are deemed to be within the spirit, scope and contemplation of the present invention as further defined in the appended claims.

Polymeric Material

The present disclosure is directed to a polymeric material comprising a fluorosilicone polymer and a silica component which is both optically clear and has a sufficiently low modulus such that it can effectively respond to the eye's natural accommodative forces and thus be used in accommodating intraocular lenses.

In one embodiment, the presently disclosed polymeric material comprises a fluorosilicone polymer and up to about 30 weight % of a silica component. The fluorosilicone polymer described herein is a crosslinked copolymer of dialkyl, diphenyl or phenylalkyl siloxane and a fluorinated dialkyl siloxane. Typically, the fluorosilicone polymer is a crosslinked copolymer of dialkyl, diphenyl or phenylalkyl siloxane and trifluoroalkyl(alkyl)siloxane, but can be a terpolymer or higher order polymer of diphenyl and/or phenylalkyl siloxane, dialkyl siloxane and trifluoroalkyl(alkyl)siloxane. In certain embodiments, the fluorosilicone polymer is a crosslinked copolymer of dialkyl siloxane, such as dimethyl siloxane, and trifluoroalkyl(alkyl)siloxane, such as 3,3,3-trifluoropropylmethyl siloxane. The ratio of dialkyl siloxane and trifluoroalkyl(alkyl)siloxane can be adjusted to tune the physical properties of the fluorosilicone polymer. For example, increasing the trifluoroalkyl(alkyl)siloxane can increase the hydrophobicity of the resulting fluorosilicone polymer. In some embodiments, the fluorosilicone polymer typically comprises at least about 25 mole % trifluoroalkyl(alkyl)siloxane, or about 25 mole % trifluoroalkyl(alkyl)siloxane, or about 30 mole % trifluoroalkyl(alkyl)siloxane, or about 35 mole % trifluoroalkyl(alkyl)siloxane, or about 40 mole % trifluoroalkyl(alkyl)siloxane, or about 50 mole % trifluoroalkyl(alkyl)siloxane or from about 25 mole % to about 50 mole %, or from about 25 mole % to about 40 mole % trifluoroalkyl(alkyl)siloxane.

In one embodiment, the fluorosilicone polymer is represented by formula (I):

wherein:

n and m are each independently 0 to about 500;

t is about 100 to about 1000;

each R¹ is independently alkyl or aryl;

R² is haloalkyl;

R³ is alkyl or haloalkyl;

R⁴ and R⁵ are independently alkyl, haloalkyl or aryl; and

each X is a crosslinker which links the polymer of formula (I) with a second polymer of formula (I).

In one embodiment, n is about 50, or about 100, or about 125, or about 150, or about 200, or about 250, or about 300, or about 350, or about 400, or about 450, or about 500. In one embodiment, m is about 50, or about 100, or about 125, or about 150, or about 200, or about 250, or about 300, or about 350, or about 400, or about 450, or about 500. In another embodiment, n is about 100, and m is about 150.

In any embodiment, t is about 100, or about 125, or about 150, or about 200, or about 250, or about 300, or about 350, or about 400, or about 450, or about 500, or about 550, or about 600, or about 650, or about 700, or about 750, or about 800, or about 850, or about 900, or about 950, or about 1000.

In one embodiment, each R¹ is alkyl. Suitable alkyl groups include, but are not limited to, C₁-C₆ alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, n-pentyl, n-hexyl, and the like. In another embodiment, each R¹ is methyl. In one embodiment, R³ is alkyl, such as defined for R¹. In another embodiment, R³ is methyl. In one embodiment, R⁴ is alkyl, such as defined for R¹. In another embodiment, R⁴ is methyl. In one embodiment, R⁵ is alkyl, such as defined for R¹. In another embodiment, R⁵ is methyl. In yet another embodiment, R⁴ and R⁵ are methyl. In still another embodiment, the fluorosilicone polymer is represented by formula (IA):

wherein:

n is from 1 to about 500;

m is from 0 to about 500;

t is about 100 to about 1000;

R² is haloalkyl;

R³ is alkyl or haloalkyl; and

each X is a crosslinker which links the polymer of formula (IA) with a second polymer of formula (IA).

In one embodiment, R² is a haloalkyl group comprising from 1 to 3 halo (provided at least one is fluoro) substituents. Exemplary haloalkyl groups include, but are not limited to, fluoromethyl, 2-fluorethyl, 2,2-difluoroethyl, and 3,3,3-trifluoropropyl. In one embodiment, R² is 3,3,3-trifluoropropyl.

The crosslinker is typically a methylhydrosiloxane-dimethylsiloxane copolymer with a methyl-hydrogen content of from about 30 to about 70 mole %. In some embodiments, the crosslinker has a chain length of from about 5 to about 30 repeating Si units (i.e., degree of polymerization).

In certain embodiments, the polymeric material provided herein has a degree of polymerization of from about 200 to about 500, or from about 300 to about 500, or about 400, or about 450.

In order to be used as an intraocular lens material, the polymeric material described herein should be optically clear. However, the fluorosilicone polymer and the silica component are not index matched. Thus the optical properties of the polymeric material must be maintained as the modulus is increased. Advantageously, the optical properties of the presently disclosed polymeric material can be tuned independently from the modulus. Several different factors contribute to the optical properties of the polymeric material, including the amount and particle size of the silica component.

Since the refractive index of the fluorosilicone polymer is low, it is contemplated that the particle size of the silica component should be as small as possible in order to obtain superior optical characteristics. In certain embodiments, the polymeric material provided herein has a refractive index of from about 1.35 to about 1.40, or from about 1.37 to from about 1.39, or about 1.38. Accordingly, the silica component as used herein has a surface area of at least about 280 m²/g, or at least about 300 m²/g, or at least about 310 m²/g, or at least about 320 m²/g, or at least about 330 m²/g, or at least about 340 m²/g, or at least about 350 m²/g. In certain embodiments, the silica component has an average particle size of less than about 11 nanometers. Fumed silica having an average particle size of about 7 nanometers in diameter is particularly suitable because the small particle size does not interfere with the wavelength of visible light and contributes to an improved optical resolution in the cured composition. Commercial fumed silica with particle sizes as low as 7 nm are commercially available (e.g., CABOT and Sigma). Typically, the silica component is present in an amount up to about 30 weight %, or 27 weight %, or about 25 weight %, or about 23 weight %, or about 20 weight %, or from about 20 to about 30 weight %.

The silica component as used herein is fumed or “activated” silica, which has been treated with a silazane. The amount of silica component should be such that the polymeric material is sufficiently reinforced, yet remains optically clear. Suitable silazanes and methods for carrying out the fumed silica treatment include the in situ reaction of small particle size fumed silica and are well known in the art. In such reactions, the silazane (e.g., hexamethyldisilazane) readily reacts with the hydroxyl functionalities on fumed silica, forming a trimethylsiloxane coating on the silica surface. In certain embodiments, the polymeric material provided herein has a Young's modulus of from about 10 psi to about 150 psi, or from about 50 psi to about 100 psi, or about 70 psi.

Other physical characteristics of the polymeric material can be modulated as well. In certain embodiments, the polymeric material provided herein has a tensile strength of from about 500 psi to about 1200 psi, or from about 700 psi to about 1000 psi, or about 900 psi. In certain embodiments, the polymeric material provided herein has a percent elongation of from about 400% to about 1000%, or about 600%.

Also provided herein are methods for making the above-described polymeric material. In certain embodiments, the method comprises the steps of:

(a) combining a vinyl end-capped fluorosilicone polymer with up to about 30 weight % of a silica component, wherein the silica component has a surface area of at least about 280 m²/g, to obtain a fluorosilicone base composition;

(b) adding a crosslinking agent and a curing agent to the fluorosilicone base composition; and

(c) curing the fluorosilicone base composition to obtain the polymeric material.

The vinyl end-capped fluorosilicone polymer can be synthesized using known methods from commercially available starting materials or purchased from commercial sources. For example, a vinyl end-capped trifluoropropylmethylsiloxane—dimethylsiloxane copolymer having a molecular weight of about 25,000 to about 35,000—is commercially available from Gelest. Alternatively, the vinyl end-capped fluorosilicone polymercan be synthesized as described in Example 1, for example. Suitable starting materials include, but are not limited to, alkylsiloxanes (e.g., octamethylcyclotetrasiloxane), haloalkylsiloxanes (e.g., trifluoropropyltrimethylcyclosiloxane), and the like. Suitable vinyl endblockers include, but are not limited to, vinyl-endblocked dimethyl siloxane oligomer.

In one embodiment, the fluorosilicone polymer has a long chain length, having a molecular weight of greater than 35,000 daltons, or greater than 50,000 daltons and, or greater than 70,000 daltons are desired.

In one embodiment, the fluorosilicone polymer is a compound of formula (II):

wherein:

• • n and m are each independently 0 to about 500;
  • t is from about 100 to about 1000;
  • each R¹ is independently alkyl or aryl;
  • R² is haloalkyl;
  • R³ is alkyl or haloalkyl; and
  • R⁴ and R⁵ are independently alkyl, haloalkyl or aryl.

The polymeric material described herein has a degree of crosslinking such that the material has a sufficiently low modulus to minimize any potential deformation caused by forces applied during its use as, for example, an accommodating intraocular lens, yet also be sufficiently solid as to minimize the permeation of the gel. In certain embodiments, the polymeric material is lightly crosslinked, having less than about 5 parts per hundred (pph) crosslinker, or less than about 4 pph, or less than about 2 pph, or less than about 1 pp, or about 1 pph. The crosslinker is typically a methylhydrosiloxane-dimethylsiloxane copolymer with a methyl-hydrogen content of from about 30 to about 70 mole %. In some embodiments, the crosslinker has a chain length of from about 5 to about 30 repeating Si units (i.e., degree of polymerization).

In one embodiment, the curing step comprises adding a platinum catalyst. The platinum group metal catalyst can be any of the compatible platinum group metal-containing catalysts known to catalyze the addition of silicone-hydrogen atoms to silicon-bonded vinyl radicals. Platinum group metal-containing catalysts can be any of the known forms which are compatible, such as platinic chloride, salts of platinum, chloroplatinic acid and various complexes, for example, silicone complexes with platinum metal-containing groups. The platinum group metal-containing catalyst can be used in any catalytic quantity, such as in an amount sufficient to provide at least about 0.1 ppm weight of platinum group metal (as elemental metal) based on the total weight of the composition. In certain embodiments, at least about 10 ppm, or at least about 20 ppm, or at least 30 ppm, or at least about 40 ppm by weight of platinum catalyst was used.

Implantable Intraocular Lens (IOL)

A device implanted in the eye naturally becomes exposed to the fluid in the eye and the fluid can, over time, diffuse through the device and have unintended and/or undesired effects on the physical characteristics of the device. Attempts have been made to coat ophthalmic devices with barrier layers to prevent such diffusion, but these procedures can be costly and time consuming. In addition, if an ophthalmic device contains a chamber or channel within the device which contains a fluid, there is a risk that that fluid can diffuse out of its fluid chamber and into the polymeric material. This results in a decrease in the amount of fluid that can be utilized by the IOL, as well as to possibly alter the physical characteristics of the polymeric material. Fluorocarbon-containing silicone monomers can enhance a polymer's resistance to the diffusion of fluid, and as such, the polymeric material described herein can be used in ophthalmic devices to resist the diffusion of fluid into or out of the device.

The IOLs can be fabricated from the disclosed polymeric material using known molding techniques, such as disposable or polished stainless steel mold, having a mold cavity in the shape required for the correct refraction of light for the material. In practice, the uncured fluorosilicone base composition is introduced into the mold cavity, in an amount dictated by considerations relating to the lens size, refractive power, and structure, and then cured. Several methods of molding the lens can be employed, including injection molding, liquid injection molding, compression molding, and transfer molding.

Intraocular Lens (IOL) Device

The presently disclosed intraocular lenses can be used in an intraocular device for implantation in a patent. Such devices are known in the art, and include, for example, those described in U.S. Pat. Nos. 7,662,180 and 7,875,661.

In certain embodiments, the presently disclosed intraocular lenses can be used as a power changing lens in a two-part accommodating IOL device in which the power changing lens and a primary lens are in sliding contact with one another within a lens chamber. In such systems, the power changing lens is sized and shaped to take on and respond to the radially-inward forces which are applied along the peripheral edge of the lens. In contrast, the primary lens does not participate in providing an accommodative response and thus is sized and shaped so as to avoid interfering or resisting the radial compressive forces that are applied to the power changing lens. This may be accomplished by controlling the relative diameters and thicknesses of the power changing lens and the primary lens to maximize the extent to which the radial compressive forces are applied onto the power changing lens and to minimize the extent to which these forces are applied onto the primary lens.

Accordingly, in one embodiment, provided herein is an intraocular lens (IOL) device comprising:

(a) a first lens comprised of the polymeric material as described herein having a first Young's modulus;

(b) a second lens in spaced relation to the first lens along a central optical axis; and

(c) a circumferential portion encircling the first and second lens, the circumferential portion comprising an outer peripheral edge;

wherein at least one of a portion of the second lens and a portion of the circumferential portion is made of a material having a second Young's modulus; and wherein the first Young's modulus is less than the second Young's modulus.

In practice, the first lens (i.e., the power changing lens) and the second lens (i.e., the primary lens) are in sliding contact with one another within a lens chamber. The lens chamber is filled with a fluid or gel having specific physical and chemical characteristics to enhance the range of refractive power provided by the IOL during accommodation. The fluid or gel is selected such that it cooperates with the power changing lens in providing a sufficient range of accommodation of up to at least 3 diopters, preferably up to at least 5 diopters, preferably up to at least 10 diopters and most preferably up to at least 15 diopters.

In addition, a lens comprised of the polymeric material described herein has a reduced likelihood of buckling in a patient from contact with the primary lens as the surface is significantly more oleophobic than other polymers typically used for IOLs.

In addition to use in an IOL, the polymeric material of the present disclosure can also be used in other ophthalmic devices such as, but not limited to, contact lenses, keratoprostheses, capsular bag extension rings, corneal inlays, corneal rings, or other ophthalmic devices. An exemplary alternative use would be in the field of breast implants, such that the polymers can be used as an exterior shell-like material to prevent leakage of an internal material.

EXAMPLES

Example 1

An exemplary polymeric material according to the present disclosure was prepared as follows.

Vinyl Endblocked 40 mole % Fluorosilicone Polymer

A vinyl endblocked 40 mole % fluorosilicone polymer for use in the fluorosilicone base was prepared as follows. 140 parts octamethylcyclotetrasiloxane (D4 cyclics), 100 parts trifluoropropyltrimethylcyclosiloxane (D3 fluorocyclics), 3.2 parts vinyl-endblocked dimethyl siloxane oligomer (vinyl endblocker), and 0.1 parts potassium siloxanolate catalyst were agitated in a polymerization vessel and heated to about 150° C. At 150° C., potassium siloxanolate catalyst was added to the polymerization vessel. Once polymerization was visually observed by an increased viscosity, polymerization was continued for about 3 hours.

After about 3 hours, the catalyst was de-activated by purging polymer with CO₂ for 1 hour and the polymer exposed to reduced pressure (minimum of 27″ Hg vacuum) at a temperature of from about 150° C. to about 180° C. until the volatile content reached an amount below about 3%.

Fluorosilicone Base

100 parts of the vinyl endblocked 40 mole % fluorosilicone polymer, 9 parts hexamethyldisilizane (HMDZ) and 3 parts water were added to a mixing vessel (e.g., sigma blade mixer). Once mixed, 60 parts activated silica (Tokuyama QS-30C fumed silica) was added in multiple additions until the silica was fully mixed into the fluorosilicone polymer. The composition was mixed at 80° C. for about 30 minutes, at which time the mixing vessel was heated to about 150° C. for about 3 hours under vacuum.

After about 3 hours, the heat and vacuum were removed. While the fluorosilicone base was still hot, additional fluorosilicone polymer was slowly added to the polymerization vessel until the silica content was reduced to approximately 25 parts. The fluorosilicone base was then dispersed in chlorinated solvent (i.e., perchloroethylene) to approximately 30% solids content, filtered through 1 micron media filter and subjected to heat and vacuum to remove solvent.

Polymeric Material Comprising a Fluorosilicone Polymer

Equal parts of A and B (Table 1) were mixed together, vacuum de-aired, and press cured in an ASTM test slab mold for about 10 minutes at 302° F. Cured test slab was allowed to equilibrate at room temperature for a minimum of 3 hours.

TABLE 1
Part A                       Part B
100 part fluorosilicone base 100 parts fluorosilicone base
5-15 ppm platinum catalyst   2 parts methyl hydrogen siloxane crosslinker
                             0.3 pph methyl vinyl cyclosilicone inhibitor

Mechanical properties of the fluorosilicone polymer are shown in Table 2. Surprisingly, the fluorosilicone polymer as described herein exhibits an enhanced tensile strength while maintaining a low modulus when compared to a non-fluorinated silicone polymer. In addition, it is contemplated that the fluorosilicone polymer described herein maintains a suitable optical clarity due to the low silica content.

	Fluorosilicone	Non-fluorinated
	polymer	silicone polymer
	Durometer (Shore A)	20	20
	Tensile strength	900 psi	475 psi
	% elongation	600%	300%
	100% modulus	70 psi	65 psi

The invention described and claimed herein is not to be limited in scope by the specific preferred embodiments disclosed herein, as these embodiments are intended as illustrations of several aspects of the invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims.

Claims

1. A polymeric material comprising a fluorosilicone polymer and up to about 30 weight % of a silica component, wherein the silica component has a surface area of at least about 280 m2/g, and wherein the fluorosilicone polymer comprises a polymer of formula

2. The polymeric material of claim 1, wherein the silica component has a surface area of from about 280 m2/g to about 350 m2/g.

3. The polymeric material of claim 1, comprising about 20% to about 27% of the silica component.

4. The polymeric material of claim 1, wherein the fluorosilicone polymer comprises a crosslinked copolymer of dialkyl, diphenyl or phenylalkyl siloxane and fluorinated dialkyl siloxane.

5. The polymeric material of claim 1, wherein the fluorosilicone polymer comprises a crosslinked copolymer of diphenyl, phenylalkyl, or dialkyl siloxane and trifluoroalkyl(alkyl)siloxane.

6. The polymeric material of claim 1, wherein R2 is 3,3,3-trifluoropropyl.

7. The polymeric material of claim 6, comprising at least about 25 mole % trifluoropropyl content.

8. The polymeric material of claim 1, having a refractive index of from about 1.35 to about 1.40.

9. The polymeric material of claim 1, having a tensile strength of from about 500 psi to about 1200 psi.

10. The polymeric material of claim 1, having a percent elongation of from about 400% to about 1000%.

11. The polymeric material of claim 1, having a degree of polymerization of from about 200 to about 500.

12. The polymeric material of claim 1, having a Young's modulus of from about 50 psi to about 100 psi.

13. The polymeric material of claim 1, wherein the crosslinker is a methylhydrosiloxane-dimethylsiloxane copolymer.

14. The polymeric material of claim 13, wherein the crosslinker has a chain length of from about 5 to about 30 repeating Si units.

15. The polymeric material of claim 13, wherein the crosslinker has a methyl-hydrogen content of from about 30 to about 70 mole %.

16. An implantable intraocular lens (IOL) comprising the polymeric material of claim 1.

17. A method of making the polymeric material of claim 1, comprising the steps of: (a) combining a vinyl end-capped fluorosilicone polymer with up to about 30 weight % of a silica component, wherein the silica component has a surface area of at least about 280 m2/g, to obtain a fluorosilicone base composition;(b) adding a crosslinking agent and a curing agent to the fluorosilicone base composition; and(c) curing the fluorosilicone base composition to obtain the polymeric material.

18. An intraocular lens (IOL) device comprising: (a) a first lens comprising the polymeric material of claim 1 having a first Young's modulus;(b) a second lens in spaced relation to the first lens along a central optical axis; and(c) a circumferential portion encircling the first and second lens, the circumferential portion comprising an outer peripheral edge;wherein at least one of a portion of the second lens and a portion of the circumferential portion is made of a material having a second Young's modulus; andwherein the first Young's modulus is less than the second Young's modulus.

19. A polymeric material comprising a crosslinked copolymer of dialkyl, diphenyl or phenylalkyl siloxane and fluorinated dialkyl siloxane, and up to about 30 weight % of a silica component, wherein the silica component has a surface area of at least about 280 m2/g, and wherein the polymeric material has a Young's modulus of from about 10 psi to about 150 psi.

20. A polymeric material comprising a crosslinked copolymer of diphenyl, phenylalkyl, or dialkyl siloxane and trifluoroalkyl(alkyl)siloxane and up to about 30 weight % of a silica component, wherein the silica component has a surface area of at least about 280 m2/g, and wherein the polymeric material has a Young's modulus of from about 10 psi to about 150 psi.

21. A polymeric material comprising a crosslinked terpolymer of diphenyl and/or phenylalkyl siloxane, dialkyl siloxane, and trifluoroalkyl(alkyl) siloxane, and up to about 30 weight % of a silica component, wherein the silica component has a surface area of at least about 280 m2/g, and wherein the polymeric material has a Young's modulus of from about 10 psi to about 150 psi.