Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Reexamination Certificate
1999-12-15
2001-09-11
Sugarman, Scott J. (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
C351S177000, C623S006620
Reexamination Certificate
active
06286955
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a biocompatible lens that is almost free from adhesion of lipid and proteins etc. in tears and is easily cleaned by being dipped in a washing liquid; and a method of producing the same.
DESCRIPTION OF THE PRIOR ART
Recently, contact lenses have been widely used for correcting near-sightedness instead of glasses, because wearing of glasses is troublesome. Various materials forming contact lenses have been developed. It is important that the materials hardly get their surface dirty with lipid and proteins in tears or induce allergic response during use of the lens. Therefore, biocompatible polymers are usually used for these materials.
Many concepts concerning the materials of contact lenses has been already disclosed or published. [see, for example, S. Nagaoka et. al., Biomaterials, 11,120, (1990); D. K. Han et.al., J.Biomed.mater.Res., 25,561 (1991); Japanese laid-open (unexamined) patent publication 63-163810, etc.] In these literatures and publications, it is reported that a medical compound containing a hydrophilic group such as a hydroxyl, carbonyl, amide, phosphoric, ether group or the like prevents a contact lens from being stained on its surface by lipid and proteins in tears. It is also reported that materials containing those groups mentioned above are easy to be cleaned and show good biocompatibility.
Furthermore, intraocular lens (artificial crystalline lens) that is implanted instead of an extracted cloudy crystalline lens after completion of the cataract operation has been also developed these days.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a biocompatible lens which comprises materials different from those medical compounds already reported, avoids adhesion of lipid and proteins in tears, is easily cleaned by being dipped in a washing liquid and exhibits biocompatibilities with tissue when implanted; and to provide a method of producing the same.
The inventor of the present invention has assiduously investigated to find a lens-surface modification method which is different from the prior arts and as a result, has found that alkoxyalkyl acrylate or alkoxyalkyl methacrylate polymers or copolymers have excellent properties capable of inhibiting adhesion of lipid and proteins in tears to lens and allowing easy washing out of the lipid and proteins adhered and that the above polymers can be used not only for a contact lens but also for an artificial crystalline lens.
That is, the biocompatible lens of the present invention is used for a contact lens that is contacted directly to the eyeball via tears and for a lens implanted in the eyeball. In the biocompatible lens of the invention, polyalkyl (meth)acrylate containing an alkoxy group or its copolymer is coated on the surface of a lens to exhibit excellent properties. In other words, the surface of the lens is covered with a layer of the coated polyalkyl (meth)acrylate containing an alkoxy group or its copolymer.
In the biocompatible lens of the invention, the layer of polyalkyl (meth)acrylate containing an alkoxy group or its copolymer may be formed onto the surface of the lens by means of graft-copolymerization. In the preparation process of the biocompatible lens of the invention, monomers of the above-mentioned polymers are graft-polymerized, by covalent bonding, with a polymer constituting the non-grafted lens. Therefore, the grafted polymer layer on the surface of the lens can not be easily peeled off and hence, effects such as inhibition of adhesion of lipid and proteins to the surface of the lens and easy washing out of the lipid and proteins adhered or the like can be maintained for a long time.
In the present invention, the alkoxy group introduced to the acrylates is preferably selected from the group consisting of a methoxy group and an ethoxy group.
Further, in the present invention, the above alkoxyalkyl (meth)acrylate (co)polymer is preferably at least one of those polymers such as poly-2-methoxyethyl acrylate, poly-2-methoxyethyl methacrylate, poly-2-ethoxyethyl acrylate, poly-2-ethoxyethyl methacrylate, poly-2-methoxybutyl acrylate and poly-2-methoxybutyl methacrylate.
Polyalkoxyalkyl (meth)acrylate may be a copolymer containing other monomer unit as far as it shows the characteristic properties of polyalkoxyalkyl (meth)acrylate. Examples of the monomers include alkyl (meth)acrylates such as methyl methacrylate, ethyl methacrylate and butyl acrylate, monomers containing nitrogen such as vinyl pyrrolidone, acrylic amide, N,N-dimethyl acrylic amide and isopropyl acrylic amide and monomers containing a reactive group such as glycidyl methacrylate, glycidyl acrylate, acrylic chloride and acryloyloxyethyl isocyanate. These copolymers may be any of random copolymer, graft-copolymer and block copolymer, but it is preferable that the copolymer contains block sequences of alkoxyalkyl (meth)acrylate.
The biocompatible lens of the present invention is produced in the following method comprising three steps. Namely, in the first step, activated radical species is induced on the surface of the lens; in the second step, monomers such as alkoxyalkyl (meth)acrylate or the like are coated onto the surface of the lens and in the third process, the above monomers are polymerized by active radical species generated on the surface of the lens as an initiator. According to the process of the present invention, alkoxyalkyl (meth)acrylate (co)polymers are grafted to the surface of the lens by covalent bonding. Consequently, they are hardly peeled off from the lens surface, compared with conventional polymer coating layers prepared by firstly coating a polymer dissolved in a solvent on a lens surface and then, curing the layer by heat treatment after removal of the solvent. On account of this reason, biocompatible lenses having characteristic properties such as inhibition of lipid and proteins in tears from adhering, easy washing out of lipid and proteins adhered, and long-term maintenance of biocompatibilities can be easily and simply manufactured.
The biocompatible lens of the present invention can be also produced easily and simply by the following method comprising three steps. That is, in the first step, an alkoxyalkyl (meth)acrylate copolymer is dissolved in an organic solvent, then in the second step, the polymer solution thus prepared is coated on the surface of the lens and finally in the third process, the solvent used for dissolving the polymer is removed by vaporization. In the third process, the polymer may be made insoluble by means of heat treatment or addition of additives containing a reactive group for cross linking the polymer. As the solvent, tetrahydrofuran, methylene chloride, chloroform and the like may be used.
Various materials can be used for the biocompatible lens in the present invention. Examples thereof are polymethyl methacrylate, (co)polymers containing silicon or fluorine and (co)polymers containing polyvinyl pyrrolidone, poly-2-hydroxyethyl methacrylate and plyvinyl alcohol as at least one component.
REFERENCES:
patent: 3876581 (1975-04-01), Neogi
patent: 4028295 (1977-06-01), Loshaek
patent: 5674283 (1997-10-01), Stoy
Sakai Tetsuya
Smith , Gambrell & Russell, LLP
Sugarman Scott J.
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