High refractive index ophthalmic device materials

Details High refractive index ophthalmic device materials High refractive index ophthalmic device materials

2000-03-24

2002-03-05

Wu, David W. (Department: 1713)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S307500, C526S323000, C526S323100, C526S323200, C526S326000, C526S328500, C623S006110

Reexamination Certificate

active

06353069

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to high refractive index polymers and their use in ophthalmic lenses, particularly intraocular lenses that can be inserted through small incisions.
BACKGROUND OF THE INVENTION
In response to the development of cataractous lenses, it has become common to replace the lens with an artificial intraocular lens (IOL) in a surgical procedure. In order to reduce the trauma to the eye in cataract surgery, it is desirable to keep the incision through which the surgical procedure is conducted as small as possible. With the development of phacoemulsification surgery, in which the lens is fragmented by ultrasonic vibrations and the fragments aspirated through a small cannula, it has become possible to remove a lens through an incision no larger than 2-4 millimeters. However, since an IOL is typically at least five to six millimeters in diameter, an incision at least that large has to be made to permit the insertion of the IOL. In order to permit the use of the desirable small incision technique, various flexible, distortable, and inflatable IOLs have been devised.
Juergens, U.S. Pat. No. 4,619,662, discloses a collapsible intraocular lens with a hollow interior which can be evacuated to cause the lens to collapse to a relatively small size. The collapsed lens can then be inserted into the eye through a relatively small incision. After insertion, the interior of the lens is filled with an elastomer to expand the lens to the proper shape and dimension.
Mazzocco, U.S. Pat. No. 4,573,998, discloses a deformable intraocular lens that can be rolled, folded, or stretched to fit through a relatively small incision. The deformable lens is inserted while it is held in its distorted configuration, then released inside the chamber of the eye, whereupon the elastic property of the lens causes it to resume its molded shape. As suitable materials for the deformable lens, Mazzocco discloses polyurethane elastomers, silicone elastomers, hydrogel polymer compounds, organic or synthetic gel compounds and combinations thereof.
Keates et al., U.S. Pat. No. 4,619,657, disclose a flexible intraocular lens holder made from a flexible inert polymer, such as silicone rubber, which contains pockets for receiving individual lenses which are small enough to fit through a relatively small incision. The lens holder is folded or rolled and inserted through a small incision and thereafter several of the small lenses are inserted through the incision and into the pockets in the lens holder to form a composite intraocular lens.
A number of these known methods of providing an intraocular lens which can be inserted through a small incision have suffered from the excessive complexity of inflatable lenses or composite lenses. The deformable intraocular lenses are simpler to manufacture and use; however, when they are made of low refractive index materials, such as polyurethane elastomers and silicone elastomers, they must be relatively thick in order to provide a lens of the proper refractive power. The thicker the lens, the more difficult it is to deform or distort it into a shape which will fit through a small incision. Furthermore, the distortion required to force a thick lens through a small incision may exceed its elastic properties so that it breaks or will not recover its original shape when released within the eye. Therefore, lenses made from such materials are somewhat limited as to the minimum size to which they may be deformed.
Accordingly, recent efforts have focused on materials which can be used to form a flexible intraocular lens that can be simply rolled or folded into a configuration which will fit through a small incision. For example, U.S. Pat. No. 5,331,073 discloses foldable intraocular lens materials. The copolymeric materials disclosed in U.S. Pat. No. 5,331,073 optionally contain a hydrophilic monomer present in an amount sufficient to reduce the tackiness of the copolymer relative to a substantially identical copolymer lacking the hydrophilic monomer. Additionally, U.S. Pat. No. 5,290,892 discloses high refractive index acrylic materials which are foldable and thus capable of being inserted through small incisions.
In some cases, foldable acrylic intraocular lenses develop “glistenings” when implanted in humans or soaked in water at physiological temperatures. These microvacuoles appear to be pockets of water approximately 1 &mgr;m or greater in diameter. These glistenings are often too small to be seen by the naked eye, but are sometimes observed using a slit-lamp. Although glistenings have no detrimental effect on the function or performance of IOLs made from acrylic materials, it is nevertheless cosmetically desirable to minimize or eliminate them.
PCT Publication No. WO 97/24382 discloses a foldable intraocular lens material containing 2-phenylethylacrylate, 2-phenylethylmethacyrlate, and 0.1 to 10 mole % of a “third monomer of recognized hydrophilic character.” The hydrophilic monomer is intended to reduce the risk of glistenings. Suitable hydrophilic monomers include “monomers such as acrylic acid, methacrylic acid, hydroxyethylacrylate, hydroxyethylmethacrylate, acrylamide, methacrylamide, poly(ethylene glycol)acrylates (PEG-acrylates) and other similar monomers (preferably unsaturated compounds), especially those containing carboxyl-, hydroxyl-, sulphate, sulphonate-, amido or substituted amino-bearing groups, known to those skilled in the art of polymer chemistry.”
It is desirable for a number of reasons to limit the total amount of hydrophilic monomer to low amounts. For example, hydrophilic ingredients compromise the high refractive index of aryl acrylic hydrophobic materials because the hydrophilic ingredients themselves possess lower refractive indices and because the water taken up by the resulting material lowers the overall refractive index of the material. Despite the broad disclosure of suitable hydrophilic monomers in WO 97/24382, most are unable to eliminate glistenings when present at concentrations below 10 mole %.
SUMMARY OF THE INVENTION
This invention is directed to ophthalmic devices comprising high refractive index copolymers comprising a) two or more monomers of the structure:
wherein: X is H or CH
3
;
m is 0-10;
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
; and
b) a total of approximately 5 mole % or less of one or more monomers of the structure:
wherein: X is H or CH
3
;
W is —CH
3
or (CH
2
═C(—X)—C(═O)—); and
n is such that the weight average molecular weight is approximately 600-1000 if W is —CH
3
and approximately 400-1000 if W is (CH
2
═C(—X)—C(═O)—).
These copolymers can be used to form intraocular lenses that have high refractive indexes, are flexible and transparent, can be inserted into the eye through a relatively small incision, and recover their original shape after having been inserted. Moreover, IOLs made from these copolymers are free of glistenings compared to otherwise identical copolymers lacking a monomer of structure (II).
DETAILED DESCRIPTION OF THE INVENTION
The high refractive index copolymers used in preparing the ophthalmic devices of the present invention comprise a) two or more monomers of the structure:
wherein: X is H or CH
3
;
m is 0-10;
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
;
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 monomers of structure (I) include, but are not limited to: 2-ethylphenoxy methacrylate; 2-ethylphenoxy acrylate; 2-ethylthiophenyl methacrylate; 2-ethylthiophenyl acrylate; 2-ethylaminophenyl methacrylate; 2-ethylaminophenyl acrylate; phenyl methacrylate; phenyl acrylate; benzyl methacrylate; benz

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