Foldable ophthalmic and otorhinolaryngological device materials

Details Foldable ophthalmic and otorhinolaryngological device materials Foldable ophthalmic and otorhinolaryngological device materials

2000-08-23

2003-03-04

Zalukaeva, Tatyana (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S292500, C526S307500, C526S312000, C526S323100, C526S292300, C526S323200, C526S286000, C526S313000, C526S320000, C623S006110, C351S159000

Reexamination Certificate

active

06528602

ABSTRACT:

FIELD OF THE INVENTION
This invention is directed to acrylic device materials. In particular, this invention relates to soft, high refractive index acrylic device materials particularly suited for use as intraocular lens (“IOL”) materials.
BACKGROUND OF THE INVENTION
With the recent advances in small-incision cataract surgery, increased emphasis has been placed on developing soft, foldable materials suitable for use in artificial lenses. In general, these materials fall into one of three categories: hydrogels, silicones, and acrylics.
In general, hydrogel materials have a relatively low refractive index, making them less desirable than other materials because of the thicker lens optic necessary to achieve a given refractive power. Silicone materials generally have a higher refractive index than 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. Acrylic materials are desirable because they typically have a high refractive index and unfold more slowly or controllably than silicone materials.
U.S. Pat. No. 5,290,892 discloses high refractive index, acrylic materials suitable for use as an IOL material. These acrylic materials contain, as principal components, two aryl acrylic monomers. They also contain a cross-linking component. The IOLs made of these acrylic materials can be rolled or folded for insertion through small incisions.
U.S. Pat. No. 5,331,073 also discloses soft acrylic IOL materials. These materials contain as principal components, two acrylic monomers which are defined by the properties of their respective homopolymers. The first monomer is defined as one in which its homopolymer has a refractive index of at least about 1.50. The second monomer is defined as one in which its homopolymer has a glass transition temperature less than about 22° C. These IOL materials also contain a cross-linking component. Additionally, these materials may optionally contain a fourth constituent, different from the first three constituents, which is derived from a hydrophilic monomer. These materials preferably have a total of less than about 15% by weight of a hydrophilic component.
U.S. Pat. No. 5,693,095 discloses foldable ophthalmic lens materials comprising a total of at least 90% by weight of only two principal lens-forming monomers. One lens-forming monomer is an aryl acrylic hydrophobic monomer. The other lens-forming monomer is a hydrophilic monomer. The lens materials also comprise a cross-linking monomer and optionally comprise a UV absorber, polymerization initiators, reactive UV absorbers and reactive blue-light absorbers.
SUMMARY OF THE INVENTION
Improved soft, foldable acrylic materials which are particularly suited for use as IOLs, but which are also useful as other ophthalmic or otorhinolaryngological devices, such as contact lenses, keratoprostheses, corneal rings or inlays, otological ventilation tubes and nasal implants have now been discovered. These materials contain only one principal lens-forming component: an aryl acrylic hydrophobic monomer. The materials of the present invention comprise at least about 80% by weight of the principal monomeric component. The remainder of the material comprises a cross-linking monomer and optionally one or more additional components selected from the group consisting of UV-light absorbing compounds and blue-light absorbing compounds.
Among other factors, the present invention is based on the finding that acrylic copolymers suitable for use as foldable IOL materials can be synthesized using only one principal aryl acrylic hydrophobic monomer, reducing or eliminating difficulties, such as physico/chemical heterogeneity, associated with curing copolymers that contain two or more principal device-forming monomers.
DETAILED DESCRIPTION OF THE INVENTION
The ophthalmic or otorhinolaryngological device materials of the present invention comprise only one principal device-forming monomer. For convenience, the device-forming monomer may be referred to as a lens-forming monomer, particularly with reference to an IOL. The materials of the present invention, however, are also suitable for use as other ophthalmic or otorhinolaryngological devices such as contact lenses, keratoprostheses, corneal inlays or rings, otological ventilation tubes and nasal implants.
The aryl acrylic hydrophobic monomers suitable for use as the sole lens-forming monomer in the materials of the present invention have the formula
wherein: A is H, CH
3
, CH
2
CH
3
, or CH
2
OH;
B is (CH
2
)
m
or [O(CH
2
)
2
]
n
;
C is (CH
2
)
w
;
m is 2-6;
n is 1-10;
Y is nothing, O, S, or NR, provided that if Y is O, S, or NR, then B is (CH
2
)
m
;
R is H, CH
3
, C
n
H
2n+1
(n=1-10), iso-OC
3
H
7
, C
6
H
5
, or CH
2
C
6
H
5
;
w is 0-6, provided that m+w≦8; and
D is H, C
1
-C
4
alkyl, C
1
-C
4
alkoxy, C
6
H
5
, CH
2
C
6
H
5
or halogen.
Preferred aryl acrylic hydrophobic monomers for use in the materials of the present invention are those wherein A is CH
3
, B is (CH
2
)
m
, m is 2-5, Y is nothing or O, w is 0-1, and D is H. Most preferred are 4-phenylbutyl methacrylate, 5-phenylpentyl methacrylate, 2-benzyloxyethyl methacrylate, and 3-benzyloxypropyl methacrylate.
Monomers of structure I can be made by known methods. For example, the conjugate alcohol of the desired monomer can be combined in a reaction vessel with methyl methacrylate, tetrabutyl titanate (catalyst), and a polymerization inhibitor such as 4-benzyloxy phenol. The vessel can then be heated to facilitate the reaction and distill off the reaction by-products to drive the reaction to completion. Alternative synthesis schemes involve adding methacrylic acid to the conjugate alcohol and catalyzing with a carbodiimide or mixing the conjugate alcohol with methacryloyl chloride and a base such as pyridine or triethylamine.
The materials of the present invention comprise a total of at least about 80%, preferably at least about 85%, by weight or more of the principal lens-forming monomer.
The copolymer materials of the present invention are cross-linked. The copolymerizable cross-linking agent used in the copolymers of this invention may be any terminally ethylenically unsaturated compound having more than one unsaturated group. Suitable cross-linking agents include, for example: ethylene glycol dimethacrylate; diethylene glycol dimethacrylate; allyl methacrylate; 1,3-propanediol dimethacrylate; 2,3-propanediol dimethacrylate; 1,6-hexanediol dimethacrylate; 1,4-butanediol dimethacrylate; CH
2
═C(CH
3
)C(═O)O—(CH
2
CH
2
O)
n
—C(═O)C(CH
3
)═CH
2
where n=1-50; and CH
2
═C(CH
3
)C(═O)O(CH
2
)
t
O—C(═O)C(CH
3
)═CH
2
where t=3-20; and their corresponding acrylates. The most preferred cross-linking monomer is CH
2
═C(CH
3
)C(═O)O—(CH
2
CH
2
O)
n
—C(═O)C(CH
3
)═CH
2
where n is such that the number-average molecular weight is about 400, about 600, or, most preferably, about 1000.
The chosen cross-linking agent should be soluble in the chosen monomer of structure I to minimize curing problems. When n approaches the upper end of the range of 1-50, the CH
2
═C(CH
3
)C(═O)O—(CH
2
CH
2
O)
n
—C(═O)C(CH
3
)═CH
2
cross-linker may not be soluble at desired levels in some monomers of structure 1, even with the aid of heat or sonication.
Generally, only one cross-linking monomer will be present in the device materials of the present invention. In some cases, however, combinations of cross-linking monomers may be desirable. If combinations of two or more types of cross-linking agents are used, none of the cross-linking agents may be CH
2
═C(CH
3
)C(═O)O—(CH
2
CH
2
O)
n
—C(═O)C(CH
3
)═CH
2
wherein n=2-50.
Generally, the total amount of the cross-linking component is at least 0.1% by weight and, depending on the identity and concentration of the remaining components and the desired physical properties, can range to about 20% by weight. The pref

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