High refractive index aromatic-based prepolymers

Details High refractive index aromatic-based prepolymers High refractive index aromatic-based prepolymers

2001-11-02

2004-08-17

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...

C528S032000, C528S041000, C528S085000, C528S038000, C556S414000, C556S440000

Reexamination Certificate

active

06777522

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to prepolymers useful in the manufacture of biocompatible medical devices. More particularly, the present invention relates to aromatic-substituted polysiloxane prepolymers capable of copolymerization with one or more other monomers to form polymeric compositions having desirable physical characteristics and refractive indices for use in the manufacture of ophthalmic implants.
BACKGROUND OF THE INVENTION
Since the 1940's optical 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 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 higher refractive indices 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 devices, there is a need for stable, biocompatible polymeric materials having desirable physical characteristics and refractive indices.
SUMMARY OF THE INVENTION
Soft, foldable, high refractive index, high elongation, polymeric compositions of the present invention are synthesized through the copolymerization of aromatic-substituted polysiloxane prepolymers with one or more aromatic monomers, alkyl monomers, hydrophilic monomers or a combination thereof. Production processes of the present invention using the subject aromatic-substituted polysiloxane prepolymers, produce materials having desirable physical properties for use in the manufacture of ophthalmic devices. The polymeric compositions of the present invention are transparent and have relatively high strength for durability during surgical manipulation, relatively high elongation and relatively high refractive index. The subject polymeric compositions are particularly well suited for use in the manufacture of ophthalmic devices such as intraocular lens (IOL) implants, contact lenses, keratoprostheses, corneal rings, corneal inlays and the like.
Preferred aromatic-substituted polysiloxane prepolymers for use in the production of the polymeric compositions of present invention have a structure generally represented by Formula 1 below, which may be produced from precursors having a structure generally represented by Formula 2 below:
wherein the V groups may be the same or different unsaturated photo or thermal polymerizable substituents of the general structure R
3
CH═C(R
4
)(CH
2
)
p
(W)
q
(Z)
q
(Ar)
q
R
5
; the R groups may be the same or different saturated C
1-10
hydrocarbon substituents; the R
1
groups may be the same or different alkyl substituents; the R
2
groups may be the same or different alkyl substituents, fluoroalkyl substituents or alkyl-fluoroalkyl substituents with ether linkages therebetween, or the same or different aromatic substituents; the L groups, which may or may not be present in the subject prepolymers, may be the same or different urethane, urea, carbonate or ester linkages; y is a natural number greater than 4 representing the sum of siloxane moieties with randomly differing R
2
groups as defined above with a molar ratio of aromatic substituents to alkyl substituents no less than 1:4; x is a natural number such that the prepolymer molecular weight is at least approximately 1000 and refractive index is at least approximately 1.45 or greater; m is a natural number greater than 4 representing the sum of siloxane moieties with randomly differing R
2
groups as defined above with a molar ratio of aromatic substituents to alkyl substituents no less than 1:4 such that the prepolymer molecular weight is at least approximately 1000 and refractive index is at least approximately 1.45 or greater; R
3
is selected from the group consisting of hydrogen, C
1-10
alkyl and —CO—U—R
1
; R
4
is selected from the group consisting of hydrogen and methyl; R
5
is a C
1-10
divalent alkylene radical; the W group is selected from the group consisting of —CO— and —OCO—; the Z group is selected from the group consisting of —O— and —NH—; the Z
1
groups may be the same or different selected from the group consisting of —OH and —NH
2
; the Ar groups may be the same or different C
6-30
aromatic radicals; p is a non-negative integer less than 7; q is either 0 or 1; and U is selected from the group consisting of —OC
1-12
alkyl radical, —SC
1-12
alkyl radical and —NHC
1-12
alkyl radical.
Accordingly, it is an object of the present invention to provide transparent, biocompatible polymeric compositions having desirable physical characteristics and relatively high refractive indices.
Another object of the present invention is to provide polymeric compositions having relatively high refractive indices and good clarity.
Another object of the present invention is to provide polymeric compositions suitable for use in the manufacture of ophthalmic devices.
Another object of the present invention is to provide polymeric compositions suitable for use in the manufacture of intraocular lens implants.
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 nove

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