Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
2001-11-02
2004-04-20
Peng, Kuo-Liang (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C556S437000, C556S458000, C528S043000, C526S279000, C525S288000
Reexamination Certificate
active
06723816
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to macromonomers useful in the manufacture of biocompatible medical devices. More particularly, the present invention relates to aromatic-based siloxane difunctional macromonomers capable of polymerization alone or copolymerization with other monomers. Upon polymerization or copolymerization, the subject macromonomers form polymeric compositions having desirable physical characteristics and refractive indices useful in the manufacture of ophthalmic devices.
BACKGROUND OF THE INVENTION
Since the 1940's ophthalmic devices in the form of intraocular lens (IOL) implants have been utilized as replacements for diseased or damaged natural ocular lenses. In most cases, an intraocular lens is implanted within an eye at the time of surgically removing the diseased or damaged natural lens, such as for example, in the case of cataracts. For decades, the preferred material for fabricating such intraocular lens implants was poly(methyl methacrylate), which is a rigid, glassy polymer.
Softer, more flexible IOL implants have gained in popularity in more recent years due to their ability to be compressed, folded, rolled or otherwise deformed. Such softer IOL implants may be deformed prior to insertion thereof through an incision in the cornea of an eye. Following insertion of the IOL in an eye, the IOL returns to its original pre-deformed shape due to the memory characteristics of the soft material. Softer, more flexible IOL implants as just described may be implanted into an eye through an incision that is much smaller, i.e., less than 4.0 mm, than that necessary for more rigid IOLs, i.e., 5.5 to 7.0 mm. A larger incision is necessary for more rigid IOL implants because the lens must be inserted through an incision in the cornea slightly larger than the diameter of the inflexible IOL optic portion. Accordingly, more rigid IOL implants have become less popular in the market since larger incisions have been found to be associated with an increased incidence of postoperative complications, such as induced astigmatism.
With recent advances in small-incision cataract surgery, increased emphasis has been placed on developing soft, foldable materials suitable for use in artificial IOL implants. In general, the materials of current commercial IOLs fall into one of three general categories: silicones, hydrophilic acrylics and hydrophobic acrylics.
In general, high water content hydrophilic acrylics or “hydrogels” have relatively low refractive indices, making them less desirable than other materials with respect to minimal incision size. Low refractive index materials require a thicker IOL optic portion to achieve a given refractive power. Silicone materials may have a higher refractive index than high-water content hydrogels, but tend to unfold explosively after being placed in the eye in a folded position. Explosive unfolding can potentially damage the corneal endothelium and/or rupture the natural lens capsule and associated zonules. Low glass transition temperature hydrophobic acrylic materials are desirable because they typically have a high refractive index and unfold more slowly and more controllably than silicone materials. Unfortunately, low glass transition temperature hydrophobic acrylic materials, which contain little or no water initially, may absorb pockets of water in vivo causing light reflections or “glistenings.” Furthermore, it may be difficult to achieve ideal folding and unfolding characteristics due to the temperature sensitivity of some acrylic polymers.
Because of the noted shortcomings of current polymeric materials available for use in the manufacture of ophthalmic implants, there is a need for stable, biocompatible polymeric materials having desirable physical characteristics and refractive index.
SUMMARY OF THE INVENTION
Soft, foldable, high refractive index, high elongation polymeric compositions of the present invention are produced through the polymerization of aromatic-based siloxane macromonomers, either alone or with other monomers. The subject macromonomers are synthesized through a two-phase reaction scheme. The polymeric compositions produced from the siloxane macromonomers so synthesized have ideal physical properties for the manufacture of ophthalmic devices. The polymeric compositions of the present invention are transparent, of relatively high strength for durability during surgical manipulations, of relatively high elongation, of relatively high refractive index and are biocompatible. The subject polymeric compositions are particularly well suited for use as intraocular lens (IOL) implants, contact lenses, keratoprostheses, corneal rings, corneal inlays and the like.
Preferred aromatic-based siloxane macromonomers for use in preparing the polymeric compositions of present invention have the generalized structures represented by Formula 1 and Formula 2 below,
wherein the R groups may be the same or different aromatic-based substituents; R
1
is an aromatic-based substituent or an alkyl; x is a non-negative integer; and y is a natural number.
Accordingly, it is an object of the present invention to provide transparent, polymeric compositions having desirable physical characteristics for the manufacture of ophthalmic devices.
Another object of the present invention is to provide polymeric compositions of relatively high refractive index.
Another object of the present invention is to provide polymeric compositions suitable for use in the manufacture of intraocular lens implants.
Another object of the present invention is to provide polymeric compositions that are biocompatible.
Still another object of the present invention is to provide polymeric compositions that are economical to produce.
These and other objectives and advantages of the present invention, some of which are specifically described and others that are not, will become apparent from the detailed description and claims that follow.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to novel aromatic-based siloxane macromonomers synthesized through a two-phase reaction scheme. The subject aromatic-based siloxane macromonomers are useful in the production of biocompatible polymeric compositions. The subject polymeric compositions have particularly desirable physical properties. The subject polymeric compositions have a relatively high refractive index of approximately 1.45 or greater and a relatively high elongation of approximately 100 percent or greater. Accordingly, the subject polymeric compositions are ideal for use in the manufacture of ophthalmic devices. The aromatic-based siloxane macromonomers of the present invention are generally represented by the structures of Formula 1 and Formula 2 below:
wherein the R groups may be the same or different C
6-30
aromatic-based substituents such as for example but not limited to
R
1
is a C
6-30
aromatic-based substituent as defined for R or a C
1-4
alkyl such as for example but not limited to methyl or propyl; x is a non-negative integer; and y is a natural number.
The aromatic-based siloxane macromonomers of the present invention may be synthesized through a two-phase reaction scheme. The first phase of the two-phase reaction scheme is a co-ring opening polymerization of a hydride functionalized cyclic siloxane with a methacrylate-capped disiloxane. The resultant silicone hydride-containing macromonomer is placed under high vacuum with heat to remove the unreacted silicone hydride cyclics. The second phase of the two-phase reaction scheme consists of a platinum-catalyzed hydrosilylation of an allylic functionalized aromatic with the hydride containing siloxane. The reaction is monitored for loss of hydride by both infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy. NMR analysis of the final product confirms the molecular structure. In producing the subject macromonomers, a thirty percent excess of the starting allylic aromatic was used and no attempt was made to remove the same following completion of the hydrosilylation. Synthesis of the subject aromatic-base
Kunzler Jay F.
Ozark Richard M.
Salamone Joseph C.
Seelye David E.
Bausch & Lomb Incorporated
Peng Kuo-Liang
Vacca Rita D.
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