Coating processes – Medical or dental purpose product; parts; subcombinations;... – Implantable permanent prosthesis
Reexamination Certificate
2000-12-06
2002-06-18
Beck, Shrive P. (Department: 1762)
Coating processes
Medical or dental purpose product; parts; subcombinations;...
Implantable permanent prosthesis
C427S162000, C427S164000, C427S284000, C351S16000R, C351S16000R, C623S006170
Reexamination Certificate
active
06406739
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to coatings for implantable ophthalmic lenses. In particular, the present invention relates to hydrophilic coatings that are applied to the edge of implantable ophthalmic lenses.
BACKGROUND OF THE INVENTION
Both rigid and foldable implantable ophthalmic lens materials are known. The most common rigid material used in ophthalmic implants is polymethyl methacrylate (“PMMA”). Foldable intraocular lens (“IOL”) materials can generally be divided into three categories: silicone materials, hydrogel materials, and non-hydrogel (“hydrophobic”) (meth)acrylic materials. See, for example,
Foldable Intraocular Lenses,
Ed. Martin et al., Slack Incorporated, Thorofare, N.J. (1993). For purposes of the present application, hydrophobic (meth)acrylic materials are (meth)acrylic materials that absorb less than approximately 5% water at room temperature.
As described in U.S. Pat. No. 5,755,786, IOLs, particularly IOLs designed for implantation through a small incision, can suffer from a problem of edge glare. The invention described in the '786 patent reduces edge glare by including means, such as a plurality of v-shaped grooves, on the optic edge's surface for reflecting visible light that contacts the edge surface away from the retina of the patient.
Other methods of reducing edge glare include those described in U.S. Pat. Nos. 5,693,093; 5,769,889; 4,808,181; and 4,605,409.
SUMMARY OF THE INVENTION
The present invention relates to hydrophilic coating compositions for surgical implants, particularly ophthalmic implants comprising silicone or hydrophobic (meth)acrylic materials. More specifically, the present invention relates to a coating material comprising an ophthalmically acceptable hydrophobic (meth)acrylic polymer and an ophthalmically acceptable hydrophilic polymer.
The present invention also relates to a method for reducing edge glare in implantable ophthalmic lenses. The method comprises applying a coating comprising an ophthalmically acceptable hydrophobic (meth)acrylic polymer and an ophthalmically acceptable hydrophilic polymer to an implant's optic edge surface. When hydrated, the coating is hazy or opaque and reduces or eliminates edge glare.
DETAILED DESCRIPTION OF THE INVENTION
Unless indicated otherwise, all amounts are expressed as %(w/w).
As used herein hydrophobic “(meth)acrylic polymer” means a hydrophobic methacrylic polymer, a hydrophobic acrylic polymer, or a hydrophobic copolymer containing both methacrylic and acrylic functional groups. As used herein, “hydrophobic” means the materials absorb less than approximately 5% water at room temperature.
The coating material of the present invention comprises an ophthalmically acceptable hydrophobic (meth)acrylic polymer and a hydrophilic polymer. When hydrated, the coating material has a T
g
less than 37° C., and preferably less than 15° C. The hydrophobic (meth)acrylic polymer ingredient in the coating material is preferably tacky to aid in attaching the coating material to the substrate. Many ophthalmically acceptable hydrophobic (meth)acrylic polymers are known, including those described in U.S. Pat. Nos. 5,290,892; 5,693,095; and 5,331,073, the entire contents of which are hereby incorporated by reference. Although aliphatic (meth)acrylate monomers can be used to form the hydrophobic (meth)acrylic polymer, the hydrophobic (meth)acrylate polymer preferably comprises at least one (meth)acrylic monomer that contains an aromatic group, such as those materials defined in U.S. Pat. No. 5,693,095:
wherein:
X is H or CH
3
;
m is 0-6;
Y is nothing, O, S, or NR, wherein 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
; and
Ar is any aromatic ring which can be unsubstituted or substituted with CH
3
, C
2
H
5
, n-C
3
H
7
, iso-C
3
H
7
, OCH
3
, C
6
H
11
, Cl, Br, C
6
H
5
, or CH
2
C
6
H
5
.
Suitable hydrophobic (meth)acrylic polymers include copolymers of 2-phenylethyl methacrylate (2-PEMA) and 2-phenylethyl acrylate (2-PEA).
After selecting the (meth)acrylic monomer(s), the hydrophobic (meth)acrylic polymer is formed using an initiator (generally about 2% or less). Any type of polymerization initiator may be used, including thermal initiators and photoinitiators. A preferred initiator is the benzoylphosphine oxide initiator, 2,4,6-trimethyl-benzoyidiphenylophosphine oxide (“TPO”), which can be activated by blue light or UV irradiation. Suitable thermal initiators include the conventional peroxides t-butyl peroctoate and bis-azoisobutronitrile. Suitable UV initiators include benzoin methyl ether, DAROCUR 1173 (2-hydroxy-2-methyl-1-phenyl-1-propanone) and DAROCUR 4265 (1:1 mixture of 2-hydroxy-2-methyl-1-phenyl-1-propanone and diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide) UV initiators.
The hydrophobic (meth)acrylic polymer optionally contains one or more ingredients selected from the group consisting of UV absorbers that are copolymerizable with the other (meth)acrylic ingredients; blue-light blocking colorants that are copolymerizable with the other (meth)acrylic ingredients; and chain transfer agents to minimize cross-linking.
Ultraviolet absorbing chromophores can be any compound which absorbs light having a wavelength shorter than about 400 nm, but does not absorb any substantial amount of visible light. Suitable copolymerizable ultraviolet absorbing compounds are the substituted 2-hydroxybenzophenones disclosed in U.S. Pat. No. 4,304,895 and the 2-hydroxy-5-acryloxyphenyl-2H-benzotriazoles disclosed in U.S. Pat. No. 4,528,311. The most preferred ultraviolet absorbing compound is 2-(3′-methallyl-2′-hydroxy-5′-methyl phenyl)benzotriazole. Suitable polymerizable blue-light blocking chromophores include those disclosed in U.S. Pat. No. 5,470,932. If a blue-light activated polymerization initiator is chosen and a blue-light blocking colorant is added, the polymerization initiator identity or concentration may have to be adjusted to minimize any interference.
Chain transfer agents, if present, are typically added in an amount ranging from 0.01 to 0.4%. Many chain transfer agents are known in the art. Examples of suitable chain transfer agents include 1-dodecanethiol and 2-mercaptoethanol.
The hydrophilic polymer contained in the coating materials of the present invention may be any ophthalmically acceptable hydrophilic polymer. Suitable hydrophilic polymers include, but are not limited to polyhydroxyethyl methacrylate (polyHEMA); polyacrylamide; polyglyceryl methacrylate and polyvinyl pyrrolidone (PVP). The most preferred hydrophilic polymer is PVP. These hydrophilic polymers are commercially available or can be made using known methods and are preferably obtained in a purified form in order to minimize extractables upon implantation of the coated IOL.
The hydrophilic polymer preferably has a molecular weight (weight avg.) in the range of 2,500-100,000. It is important that the hydrophilic polymer's molecular weight be great enough and be present in the hydrogel coating material in a sufficient amount to form hydrophilic domains capable of dispersing light. The hydrophilic polymer should not be too small, otherwise an appreciable amount of it may leach out of the coating after the coating is applied to the IOL. The hydrophilic polymer should not be too large, otherwise it may affect intraocular pressure in the event that some of the polymer leaches out of the coating. In the case of PVP, a molecular weight of 10,000 is preferred.
The coating material is formed by preparing an ophthalmically acceptable hydrophobic (meth)acrylic polymer, then purifying (if necessary or desired) the cured hydrophobic (meth)acrylic polymer via extraction in a suitable solvent, then dissolving the hydrophobic (meth)acrylic polymer and an ophthalmically acceptable hydrophilic polymer in a suitable solvent or mixture of solvents to form a coating solution. The proportion of hydrophobic (meth)acrylic polymer to hydrophilic polymer in the coating composition depends upon on the desired hydrated water content for the coating, the
LeBoeuf Albert R.
Sheets, Jr. John W.
Alcon Universal Ltd.
Beck Shrive P.
Markham Wesley
Ryan Patrick M.
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