Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-02-11
2001-08-21
Zitomer, Fred (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S261000, C526S310000, C526S312000, C526S320000, C526S329700, C526S328000
Reexamination Certificate
active
06277940
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a material for a soft intraocular lens. And more particularly it relates to a material for a soft intraocular lens, which is excellent in transparency and flexibility, can be inserted from a small incision, and has a high refractive index in spite of a high water content.
In order to make the size of the eye's injury small, which is cut in the operation of cataract by using an intraocular lens, it is desirable that an incision treated surgically is as small as possible. According to development of the phacoemulsificasion aspiration that the human's lens is broken by using an ultrasonic vibration and the fragment is sucked through a small cannula, human's lens can be removed through the incision not more than 2-3 mm.
However, since an intraocular lens usually has a diameter of about 6 mm, a large portion must be dissected in order to be inserted as it is. But various soft intraocular lenses have been recently developed, which are flexible and deformable, therefore, it becomes possible to be inserted through a small incision.
For instance, Japanese Unexamined Patent Publication No.292609/1992 discloses an intraocular lens obtained by co-polymerization of a monomer mixture, which contains at least two (meth)acrylate monomers containing an aromatic ring and a crosslinling monomer. Since the lens is certainly flexible, it can be deformed to the shape which is inserted through a small incision. But since an amount of (meth)acrylate monomers with an aromatic ring is comparatively large, it has a disadvantage of low mechanical strength. And it has another disadvantage that it is impossible to cut it by a mechanical process since the obtained polymer is soft.
Japanese Examined Patent Publication No.22565/1994 discloses the material for an intraocular lens of the copolymer, which comprises, as a main component, a hydroxyalkyl (meth)acrylate, (meth)acrylic acid ester and/or (meth)acrylic amide derivatives containing a ring structure such as a cycloalkyl group or a halogen atom except for a fluorine atom. The material for an intraocular lens can be inserted through a small incision, and it is excellent in a hydrophilic property and has a high refractive index. But a compatibility of the material component is low, therefore the transparency is desired to be improved more.
Japanese Unexamined Patent Publication No.73052/1997 discloses the material for a soft intraocular lens of the polymer, which comprises, as a main component, an acrylate containing predetermined amount of an aromatic ring and an alkyl acrylate containing a fluorine atom. The material for a soft intraocular lens has properties that a refractive index is comparatively high, recovery to the original shape is excellent, and an adhesiveness is low. But it is further desired that the polymer after polymerization is excellent in a mechanical processability, flexibility occurs by hydration after shaping, and the high refractive index is maintained at the hydration.
And Japanese Unexamined Patent Publication No.24052/1995 discloses the colored material for a soft intraocular lens as a soft intraocular lens for cyanopsia, which is obtained by adding a yellow colorant. It is usually possible to treat the soft material by extraction with an organic solvent or the like in order to remove the residual unpolymerized monomers therein. But the colorant of dispersion type disclosed in Japanese Unexamined Patent Publication No.24052/1995 is dissolved out in this extraction process, therefore the color of the lens forces to change.
It is an object of the present invention to provide a material for a soft intraocular lens which is excellent in transparency and flexibility, and can be inserted from a small incision. Further it has a high refractive index in spite of a high water content, and is excellent in mechanical processability into an intraocular lens shape in a xerogel state.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a material for a soft intraocular lens comprising a copolymer obtained by polymerizing the components for polymerization which contain (A)5-25% by weight of acrylate containing an aromatic ring represented by the general formula (I):
wherein R represents an aromatic ring of which hydrogen atom may be substituted by a substitutional group, X represents an oxygen atom or a direct bonding, and n represents an integer of 1 to 5,
(B)50-90% by weight of 2-hydroxyethyl (meth)acrylate, and
(C)5-45% by weight of a (meth)acrylate monomer except for the acrylate (A) containing an aromatic ring represented by the general formula (I) and 2-hydroxyethyl (meth)acrylate (B), wherein the coefficient of water absorption of its homopolymer is not more than 30% by weight.
REFERENCES:
patent: 4528311 (1985-07-01), Beard
patent: 5662707 (1997-09-01), Jinkerson
patent: 5814680 (1998-09-01), Imafuku
patent: 5891931 (1999-04-01), Leboeuf
patent: 6015511 (2000-01-01), Yasuda
patent: 0898972 (1999-03-01), None
patent: 9640303 (1996-12-01), None
Kawaguchi Toru
Niwa Kazuharu
Ojio Tatsuya
Browdy and Neimark
Menicon Co. Ltd
Zitomer Fred
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