U.S. patent application number 13/721267 was filed with the patent office on 2013-05-02 for preparation of antimicrobial contact lenses with reduced haze using swelling agents.
This patent application is currently assigned to JOHNSON & JOHNSON VISION CARE, INC.. The applicant listed for this patent is JOHNSON & JOHNSON VISION CARE, INC.. Invention is credited to Stephen R. Beaton, Yongcheng Li.
Application Number | 20130109778 13/721267 |
Document ID | / |
Family ID | 39808856 |
Filed Date | 2013-05-02 |
United States Patent
Application |
20130109778 |
Kind Code |
A1 |
Li; Yongcheng ; et
al. |
May 2, 2013 |
PREPARATION OF ANTIMICROBIAL CONTACT LENSES WITH REDUCED HAZE USING
SWELLING AGENTS
Abstract
This invention relates to antimicrobial lenses containing metals
and methods for their production.
Inventors: |
Li; Yongcheng; (St.
Augustine, FL) ; Beaton; Stephen R.; (Jacksonville,
FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JOHNSON & JOHNSON VISION CARE, INC.; |
Jacksonville |
FL |
US |
|
|
Assignee: |
JOHNSON & JOHNSON VISION CARE,
INC.
Jacksonville
FL
|
Family ID: |
39808856 |
Appl. No.: |
13/721267 |
Filed: |
December 20, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13010117 |
Jan 20, 2011 |
8361355 |
|
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13721267 |
|
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12055654 |
Mar 26, 2008 |
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13010117 |
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60909009 |
Mar 30, 2007 |
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Current U.S.
Class: |
523/106 |
Current CPC
Class: |
A61L 27/54 20130101;
A61L 12/088 20130101; A61L 2300/102 20130101; A61L 2300/106
20130101; A61L 2300/404 20130101; G02B 1/043 20130101; A61L
2300/104 20130101 |
Class at
Publication: |
523/106 |
International
Class: |
G02B 1/04 20060101
G02B001/04 |
Claims
1-15. (canceled)
16. An antimicrobial lens comprising, a metal salt, made by a
method comprise the steps of (a) treating a cured lens, with a
solution comprising salt precursor and a swelling agent, (b)
treating the lens of step (a) with solution comprising a swelling
agent for an appropriate time, and (c) treating the lens of step
(b) with a solution comprising a metal agent and a swelling
agent.
17. The antimicrobial lens of claim 16 wherein the swelling agent
is aqueous isopropanol, or aqueous propylene glycol.
18. The antimicrobial lens of claim 16 wherein the swelling agent
is about 30% to about 70% aqueous isopropanol.
19. The antimicrobial lens of claim 16 wherein the swelling agent
is 50% aqueous isopropanol.
20. The antimicrobial lens of claim 16 wherein the swelling agent
is aqueous propylene glycol.
21. The antimicrobial lens of claim 16 wherein the salt precursor
is selected from the group consisting sodium chloride, sodium
iodide, sodium bromide, sodium sulfide, lithium chloride, lithium
iodide, lithium bromide, lithium sulfide, potassium bromide,
potassium chloride, potassium sulfide, potassium iodide, rubidium
iodide, rubidium bromide, rubidium chloride, rubidium sulfide,
caesium iodide, caesium bromide, caesium chloride, caesium sulfide,
francium iodide, francium bromide, francium chloride, francium
sulfide, and sodium tetrachloro argentate
22. The antimicrobial lens of claim 16 wherein the salt precursor
is sodium iodide.
23. The antimicrobial lens of claim 16 wherein the metal agent is
selected from the group consisting of silver nitrate, silver
triflate, or silver acetate, silver sulfate, silver
tetrafluoroborate, silver sulfate, zinc acetate, zinc sulfate,
copper acetate, and copper sulfate.
24. The antimicrobial lens of claim 16 wherein the metal agent is
silver nitrate.
25. The antimicrobial lens of claim 16 wherein the appropriate time
is about 10 to about 40 seconds.
26. The antimicrobial lens of claim 16 wherein the appropriate time
is about 20 to about 30 seconds.
27. The antimicrobial lens of claim 16 wherein one or more of the
solutions of steps (a), (b), and (c) comprise a dispersing
agent.
28. The antimicrobial lens of claim 16, wherein the dispersing
agent is selected from the group consisting of
polyvinylpyrrolidone, polyvinylalcohol and derivatives, glycerine,
polyethylene oxide, poly(dimethyl acrylamide),
poly(N-vinyl-N-methylacetamide), cysteine, methionine, sodium
sulfide, sodium thiosulfate, and sodium thiocyanate.
29. The antimicrobial lens of claim 16 wherein the dispersing agent
is polyvinylpyrrolidone K90.
30. The antimicrobial lens of claim 16 wherein the swelling agent
is selected from the group consisting of extracting solvents as
disclosed in U.S. Pat. No. 7,112,652.
Description
RELATED APPLICATION
[0001] This application is a divisional of U.S. patent application
Ser. No. 13/010,117, filed on Jan. 20, 2011, which is a
continuation of U.S. patent application Ser. No. 12/055,654 filed
on Mar. 26, 2008, now abandoned and provisional filing of U.S. Pat.
App. Ser. No. 60/909,009, which was filed on Mar. 30, 2007 and
claims priority of that application.
FIELD OF THE INVENTION
[0002] This invention relates to methods of preparing antimicrobial
lenses
BACKGROUND OF THE INVENTION
[0003] Contact lenses have been used commercially to improve vision
since the 1950s. The first contact lenses were made of hard
materials. They were used by a patient during waking hours and
removed for cleaning. Current developments in the field gave rise
to soft contact lenses, which may be worn continuously, for several
days or more without removal for cleaning. Although many patients
favor these lenses due to their increased comfort, these lenses can
cause some adverse reactions to the user. The extended use of the
lenses can encourage the buildup of bacteria or other microbes,
particularly, Pseudomonas aeruginosa, on the surfaces of soft
contact lenses. The build-up of bacteria and other microbes can
cause adverse side effects such as contact lens acute red eye and
the like. Although the problem of bacteria and other microbes is
most often associated with the extended use of soft contact lenses,
the build-up of bacteria and other microbes occurs for users of
hard contact lens wearers as well.
[0004] U.S. Pat. No. 5,820,918 discloses medical devices made from
a water absorbable polymer material with a medical compound having
low solubility in aqueous solutions such as an antiseptic or
radiopaque compound. However, the procedures disclosed in the
examples yield opaque devices which are not suitable for ophthalmic
devices such as contact lenses.
[0005] Therefore, there is a need to produce contact lenses that
inhibit the growth of bacteria or other microbes and/or the
adhesion of bacteria or other microbes on the surface of contact
lenses. Further there is a need to produce contact lenses which do
not promote the adhesion and/or growth of bacteria or other
microbes on the surface of the contact lenses. Also there is a need
to produce contact lenses that inhibit adverse responses related to
the growth of bacteria or other microbes. Still further there is a
need to produce the foregoing contact lenses in a manner that
produces a lens of clarity suitable to permit a user to clearly see
from said lenses. These needs are met by the following
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0006] This invention includes a method of preparing an
antimicrobial lens comprising, a metal salt, wherein said method
comprises the steps of [0007] (a) treating a cured lens, with a
solution comprising a salt precursor and a swelling agent, [0008]
(b) treating the lens of step (a) with solution comprising a
swelling agent for an appropriate period of time, and [0009] (c)
treating the lens of step (b) with a solution comprising a metal
agent and a swelling agent.
[0010] As used herein, the term, "antimicrobial lens" means a lens
that exhibits one or more of the following properties, the
inhibition of the adhesion of bacteria or other microbes to the
lenses, the inhibition of the growth of bacteria or other microbes
on lenses, and the killing of bacteria or other microbes on the
surface of lenses or in an area surrounding the lenses. For
purposes of this invention, adhesion of bacteria or other microbes
to lenses, the growth of bacteria or other microbes on lenses and
the presence of bacteria or other microbes on the surface of lenses
are collectively referred to as "microbial colonization."
Preferably, the lenses of the invention exhibit a reduction of
viable bacteria or other microbe of at least about 0.25 log, more
preferably at least about 0.5 log, most preferably at least about
1.0 log (.gtoreq.90% inhibition). Such bacteria or other microbes
include but are not limited to those organisms found in the eye,
particularly Pseudomonas aeruginosa, Acanthamoeba species,
Staphylococcus. aureus, Escherichia. coli, Staphylococcus
epidermidis, and Serratia marcesens.
[0011] As used herein the term "swelling agent" refers substances
that increase the size of a lens. As defined hereinafter the lenses
of the invention absorb water after they are cured. This absorbance
of water gives a lens that has water equilibrated dimensions (i.e.
diameter, water content). These dimensions are different depending
upon the composition of the lens formulation. Swelling agents may
be used on lenses after they are cured or after they have absorbed
water and have reached their water equilibrated dimensions. Such
agents increase the dimensions of the lens beyond that of its water
equilibrated dimensions. It is preferred that the swelling agents
of the invention be used to treat lenses that have absorbed water
to their water equilibrated dimensions. Examples of swelling agents
include but are not limited to extracting solvents as disclosed in
U.S. Pat. No. 7,112,652, entitled "Solvents Useful in the
Preparation of Polymers Containing Hydrophilic and Hydrophobic
Monomers", which is hereby incorporated by reference. Particularly
examples of swelling agents include but are not limited to aqueous
isopropanol, aqueous propylene glycol, ethylene glycol-n-butyl
ether, diethylene glycol-n-butyl ether, diethylene glycol methyl
ether, ethylene glycol phenyl ether, propylene glycol methyl ether,
dipropylene glycol methyl ether, tripropylene glycol methyl ether,
propylene glycol methyl ether acetate, dipropylene glycol methyl
ether acetate, propylene glycol-n-propyl ether, dipropylene
glycol-n-propyl ether, tripropylene glycol-n-butyl ether, propylene
glycol-n-butyl ether, dipropylene glycol-n-butyl ether,
tripropylene glycol-n-butyl ether, tripropylene glycol-n-propyl
ether, proplyene glycol phenyl ether, dipropylene glycol dimethyl
ether, butyl acetate, dipropylene glycol methyl ether acetate, and
diproplyeneglycol dimethyl ether. The preferred swelling agents are
about 30% to about 70% aqueous isopropanol and about 30% to about
70% aqueous propylene glycol, where the particularly preferred
swelling agent is about 30% to about 70% aqueous isopropanol, more
preferably 50% aqueous isopropanol. It is preferred that the
swelling agent does not increase the size of the lenses beyond the
size of the lenses after step (a).
[0012] As use herein, the term "metal salt" means any molecule
having the general formula [M].sub.a [X].sub.b wherein X contains
any negatively charged ion, a is .gtoreq.1, b is .gtoreq.1 and M is
any positively charged metal selected from, but not limited to, the
following Al.sup.+3, Co.sup.+2, Co.sup.+3, Ca.sup.+2, Mg.sup.+2,
Ni.sup.+2, Ti.sup.+2, Ti.sup.+3, Ti.sup.+4, V.sup.+2, V.sup.+3,
V.sup.+5, Sr.sup.+2, Fe.sup.+2, Fe.sup.+3, Au.sup.+2, Au.sup.+3,
Au.sup.+1, Pd.sup.+2, Pd.sup.+4, Pt.sup.+2, Pt.sup.+4, Cu.sup.+1,
Cu.sup.+2, Mn.sup.+2, Mn.sup.+3, Mn.sup.+4, Zn.sup.+2, and the
like. Examples of X include but are not limited to CO.sub.3.sup.-2,
NO.sub.3.sup.-1, PO.sub.4.sup.-3, Cl.sup.-1, I.sup.-1, Br.sup.-1,
S.sup.-2, O.sup.-2 and the like. Further X includes negatively
charged ions containing CO.sub.3.sup.-2 NO.sub.3.sup.-1,
PO.sub.4.sup.-3, Cl.sup.-1, I.sup.-1, Br.sup.-1, S.sup.-2, O.sup.-2
and the like, such as C.sub.1-5alkylCO.sub.2.sup.-1. As used herein
the term metal salts does not include zeolites, disclosed in
WO03/011351. This patent application is hereby incorporated by
reference in its entirety. The preferred a is 1, 2, or 3. The
preferred b is 1, 2, or 3. The preferred metals ions are Mg.sup.+2,
Zn.sup.+2, Cu.sup.+1, Cu.sup.+2, Au.sup.+2, Au.sup.+3, Au.sup.+1,
Pd.sup.+2, Pd.sup.+4, Pt.sup.+2, Pt.sup.+4, Ag.sup.+2, and
Ag.sup.+1. The particularly preferred metal ion is Ag.sup.+1.
Examples of suitable metal salts include but are not limited to
manganese sulfide, zinc oxide, zinc sulfide, copper sulfide, and
copper phosphate. Examples of silver salts include but are not
limited to silver nitrate, silver sulfate, silver iodate, silver
carbonate, silver phosphate, silver sulfide, silver chloride,
silver bromide, silver iodide, and silver oxide. The preferred
silver salts are silver iodide, silver chloride, and silver
bromide. The lenses of the invention are ophthalmic lenses (a
detailed description of these lenses follows) and the clarity of
the lenses is of concern to users.
[0013] The amount of metal in the lenses is measured based upon the
total weight of the lenses. When the metal is silver, the preferred
amount of silver is about 0.00001 weight percent (0.1 ppm) to about
10.0 weight percent, preferably about 0.0001 weight percent (1 ppm)
to about 1.0 weight percent, most preferably about 0.001 weight
percent (10 ppm) to about 0.1 weight percent, based on the dry
weight of the lens. With respect to adding metal salts, the
molecular weight of the metal salts determines the conversion of
weight percent of metal ion to metal salt. The preferred amount of
silver salt is about 0.00003 weight percent (0.3 ppm) to about 30.0
weight percent, preferably about 0.0003 weight percent (3 ppm) to
about 3.0 weight percent, most preferably about 0.003 weight
percent (30 ppm) to about 0.3 weight percent, based on the dry
weight of the lens.
[0014] The term "solution" refers to aqueous or organic
compositions that dissolve salt precursors. The preferred solutions
are aqueous. Solutions may contain buffered salts such as sodium
borate/boric acid, excipients, surfactants, wetting agents and the
like. The term "salt precursor" refers to any compound or
composition that contains a cation that may be substituted with
metal ions. The concentration of salt precursor in its solution is
between about 0.00001 to about 10.0 weight percent, (0.1-100,000
ppm) more preferably about 0.0001 to about 1.0 weight percent,
(1-10,000 ppm) most preferably about 0.001 to about 0.1 weight
percent (10-1,000 ppm) based upon the total weight of the solution.
Examples of salt precursors include but are not limited to
inorganic molecules such as sodium chloride, sodium iodide, sodium
bromide, sodium sulfide, lithium chloride, lithium iodide, lithium
bromide, lithium sulfide, potassium bromide, potassium chloride,
potassium sulfide, potassium iodide, rubidium iodide, rubidium
bromide, rubidium chloride, rubidium sulfide, caesium iodide,
caesium bromide, caesium chloride, caesium sulfide, francium
iodide, francium bromide, francium chloride, francium sulfide,
sodium tetrachloro argentate, and the like. Examples of organic
molecules include but are not limited to tetra-alkyl ammonium
lactate, tetra-alkyl ammonium sulfate, quaternary ammonium halides,
such as tetra-alkyl ammonium chloride, bromide or iodide. The
preferred salt precursor is selected from the group consisting of
sodium chloride, sodium iodide, sodium bromide, lithium chloride,
lithium sulfide, sodium sulfide, potassium iodide, potassium
sulfide, potassium bromide, potassium chloride, and sodium
tetrachloro argentite and the particularly preferred salt precursor
is sodium iodide.
[0015] The term "metal agent" refers to any composition (including
aqueous solutions) containing metal ions. Examples of such
compositions include but are not limited to aqueous or organic
solutions of silver nitrate, silver triflate, or silver acetate,
silver sulfate, silver tetrafluoroborate, silver sulfate, zinc
acetate, zinc sulfate, copper acetate, copper sulfate, and the
like, where the concentration of metal agent in solution is about 1
.mu.g/mL or greater. The preferred metal agent is aqueous silver
nitrate, where the concentration of silver nitrate is the solution
is about greater than or equal to 0.0001 to about 2 weight percent,
more preferably about greater than 0.001 to about 0.1 weight
percent based on the total weight of the solution. The term
"treating" refers to any method of contacting solutions containing
any combination of swelling agent, metal agent, or salt precursor
with the lens wherein the preferred method is immersing the lens in
such solutions. Treating can include heating the lens in such
solutions, but, preferred treatments are carried out at ambient
temperatures and below. The time of this treatment can last
anywhere from about 10 seconds to about 24 hours, preferably from
about 30 seconds to about 60 minutes. With respect to step (a) is
also preferred that treating is conducted at ambient temperature
followed by cooler temperatures.
[0016] As used herein, the term "lens" refers to an ophthalmic
device that resides in or on the eye. These devices can provide
optical correction, wound care, drug delivery, diagnostic
functionality, cosmetic enhancement or effect or a combination of
these properties. The term lens includes but is not limited to
contact lenses, intraocular lenses, overlay lenses, ocular inserts,
punctual plugs, and optical inserts made of materials that can
absorb water. Lenses may be made from hydrogels, which include but
are not limited to silicone hydrogels, and fluorohydrogels.
[0017] For example the term lens includes but is not limited to
those made from the soft contact lens formulations described in
U.S. Pat. No. 5,710,302, WO 9421698, EP 406161, JP 2000016905, U.S.
Pat. No. 5,998,498, U.S. patent application Ser. No. 09/532,943,
U.S. Pat. No. 6,087,415, U.S. Pat. No. 5,760,100, U.S. Pat. No.
5,776,999, U.S. Pat. No. 5,789,461, U.S. Pat. No. 5,849,811, and
U.S. Pat. No. 5,965,631. In addition, metal salts of the invention
may be added to commercial soft contact lenses. Examples of soft
contact lenses formulations include but are not limited to the
formulations of etafilcon A, genfilcon A, lenefilcon A, polymacon,
acquafilcon A, balafilcon A, galyfilcon A, senofilcon A and
lotrafilcon A. The preferable lens formulations are etafilcon A,
balafilcon A, acquafilcon A, galyfilcon A, lotrafilcon A, and
silicone hydrogels, as prepared in U.S. Pat. No. 5,998,498, U.S.
Ser. No. 09/532,943, a continuation-in-part of U.S. patent
application Ser. No. 09/532,943, filed on Aug. 30, 2000,
WO03/22321, U.S. Pat. No. 6,087,415, U.S. Pat. No. 5,760,100, U.S.
Pat. No. 5,776,999, U.S. Pat. No. 5,789,461, U.S. Pat. No.
5,849,811, and U.S. Pat. No. 5,965,631. These patents as well as
all other patent disclosed in this paragraph are hereby
incorporated by reference in their entirety.
[0018] Preferably the metal salts are added to lenses made from
silicone hydrogel components. A silicone-containing component is
one that contains at least one [--Si--O--Si] group, in a monomer,
macromer or prepolymer. Preferably, the Si and attached O are
present in the silicone-containing component in an amount greater
than 20 weight percent, and more preferably greater than 30 weight
percent of the total molecular weight of the silicone-containing
component. Useful silicone-containing components preferably
comprise polymerizable functional groups such as acrylate,
methacrylate, acrylamide, methacrylamide, N-vinyl lactam,
N-vinylamide, and styryl functional groups. Examples of silicone
components which may be included in the silicone hydrogel
formulations include, but are not limited to silicone macromers,
prepolymers and monomers. Examples of silicone macromers include,
without limitation, polydimethylsiloxane methacrylated with pendant
hydrophilic groups as described in U.S. Pat. Nos. 4,259,467;
4,260,725 and 4,261,875; polydimethylsiloxane macromers with
polymerizable functional group(s) described in U.S. Pat. Nos.
4,136,250; 4,153,641; 4,189,546; 4,182,822; 4,343,927; 4,254,248;
4,355,147; 4,276,402; 4,327,203; 4,341,889; 4,486,577; 4,605,712;
4,543,398; 4,661,575; 4,703,097; 4,837,289; 4,954,586; 4,954,587;
5,346,946; 5,358,995; 5,387,632 ; 5,451,617; 5,486,579; 5,962,548;
5,981,615; 5,981,675; and 6,039,913; polysiloxane macromers
incorporating hydrophilic monomers such as those described in U.S.
Pat. Nos. 5,010,141; 5,057,578; 5,314,960; 5,371,147 and 5,336,797;
macromers comprising polydimethylsiloxane blocks and polyether
blocks such as those described in U.S. Pat. Nos. 4,871,785 and
5,034,461, combinations thereof and the like. All of the patents
cited herein are hereby incorporated in their entireties by
reference.
[0019] The silicone and/or fluorine containing macromers described
in U.S. Pat. Nos. 5,760,100; 5,776,999; 5,789,461; 5,807,944;
5,965,631 and 5,958,440 may also be used. Suitable silicone
monomers include tris(trimethylsiloxy)silylpropyl methacrylate,
hydroxyl functional silicone containing monomers, such as
3-methacryloxy-2-hydroxypropyloxy)propylbis(trimethylsiloxy)methylsilane
and those disclosed in WO03/22321, and mPDMS containing or the
siloxane monomers described in U.S. Pat. Nos. 4,120,570, 4,139,692,
4,463,149, 4,450,264, 4,525,563; 5,998,498; 3,808,178; 4,139,513;
5,070,215; 5,710,302; 5,714,557 and 5,908,906.
[0020] Additional suitable siloxane containing monomers include,
amide analogs of TRIS described in U.S. Pat. No. 4,711,943,
vinylcarbamate or carbonate analogs described in U.S. Pat. No.
5,070,215, and monomers contained in U.S. Pat. No. 6,020,445,
monomethacryloxypropyl terminated polydimethylsiloxanes,
polydimethylsiloxanes,
3-methacryloxypropylbis(trimethylsiloxy)methylsilane,
methacryloxypropylpentamethyl disiloxane and combinations thereof.
All of the references mentioned in this application are hereby
incorporated by reference in their entirety.
[0021] As used herein the term "appropriate time" refers to
duration that the solution of step (b) is in contact with the lens
after step (a). The preferred appropriate time is about 10 seconds
to about 30 seconds, most preferably about 20 seconds.
[0022] It has been found that ophthalmic devices produced by the
methods of the invention incorporate metal salts with a minimal
amount of haze. Preferably, the lenses of the invention are
optically clear, with optical clarity comparable to lenses such as
lenses made from etafilcon A, genfilcon A, galyfilcon A, lenefilcon
A, polymacon, acquafilcon A, balafilcon A, and lotrafilcon A.
Specifically, lenses of the present invention have a percent haze
that is less than about 100%, preferably less than about 50%, more
preferably less than about 25%, even more preferably less than 20%,
even more preferably, between less than about 15%.
[0023] The percentage of haze is measured using the following
method. A hudrated test lens in borate buffered saline (SSPS) is
placed in a clear 20.times.40.times.10 mm glass cell at ambient
temperature above a flat black background, illuminating from below
with a fiber optic lamp (Titan Tool Supply Co. fiber optic light
with 0.5'' diameter light guide set at a power setting of 4-5.4) at
an angle 66.degree. normal to the lens cell, and capturing an image
of the lens from above, normal to the lens cell with a video camera
(DVC 1300C:19130 RGB camera with Navitar TV Zoom 7000 zoom lens)
placed 14 mm above the lens platform. The background scatter is
subtracted from the scatter of the lens by subtracting an image of
a blank cell using EPIX XCAP V 1.0 software. The subtracted
scattered light image is quantitatively analyzed, by integrating
over the central 10 mm of the lens, and then comparing to a -1.00
diopter CSI Thin Lens.RTM., which is arbitrarily set at a haze
value of 100, with no lens set as a haze value of 0. Five lenses
are analyzed and the results are averaged to generate a haze value
as a percentage of the standard CSI lens.
[0024] The term "cured" refers to any of a number of methods used
to react a mixture of lens components (ie, momoner, prepolymers,
macromers and the like) to form lenses. Lenses can be cured by
light or heat. The preferred method of curing is with radiation,
preferably UV or visible light, and most preferably with visible
light. The lens formulations of the present invention can be formed
by any of the methods know to those skilled in the art, such as
shaking or stirring, and used to form polymeric articles or devices
by known methods.
[0025] For example, the antimicrobial lenses of the invention may
be prepared by mixing reactive components and any diluent(s) with a
polymerization initator and curing by appropriate conditions to
form a product that can be subsequently formed into the appropriate
shape by lathing, cutting and the like. Alternatively, the reaction
mixture may be placed in a mold and subsequently cured into the
appropriate article.
[0026] Various processes are known for processing the lens
formulation in the production of contact lenses, including
spincasting and static casting. Spincasting methods are disclosed
in U.S. Pat. Nos. 3,408,429 and 3,660,545, and static casting
methods are disclosed in U.S. Pat. Nos. 4,113,224 and 4,197,266.
The preferred method for producing antimicrobial lenses of this
invention is by molding. In the case of hydrogel lenses, for this
method, the lens formulation is placed in a mold having the
approximate shape of the final desired lens, and the lens
formulation is subjected to conditions whereby the components
polymerize, to produce a hardened disc that is subjected to a
number of different processing steps including treating the
polymerized lens with liquids (such as water, inorganic salts, or
organic solutions) to swell, or otherwise equilibrate this lens
prior to enclosing the lens in its final packaging. These methods
are further described in U.S. Pat. Nos. 4,495,313; 4,680,336;
4,889,664; and 5,039,459, which are hereby incorporated herein by
reference. Polymerized lenses that have not been swelled or
otherwise equilibrated are considered cured lenses for purposes of
this invention.
[0027] Additional components may be added to one of more of the
steps of the invention. Dispersing agents as described in U.S.
patent application Ser. No. 11/924,694, entitled "Processes to
Prepare Antimicrobial Contact Lenses," which is hereby incorporated
by reference includes examples of such components. The preferred
dispersing agents include but are not limited polyvinylpyrrolidone
("PVP"), polyvinylalcohol ("PVA") and derivatives, glycerine,
polyethylene oxide ("PEO"), poly(dimethyl acrylamide),
poly(N-vinyl-N-methylacetamide), cysteine, methionine, sodium
sulfide, sodium thiosulfate, and sodium thiocyanate. The
concentration of dispersing agents in the solutions is as disclosed
in U.S. patent application Ser. No. 11/924,694. The particularly
preferred dispersing agent is PVP, most particularly PVP K90.
[0028] An example of the method of the invention follows.
Senofilcon A lenses are taken from the manufacturing line after
curing and hydration with deionized water. The lenses are soaked in
an aqueous solution containing sodium iodide (1000 ppm) and a 50%
aqueous isopropanol solution. The lenses remain in the
afore-mentioned solutions for about 20 minutes at 25.degree. C. and
are cooled to 0.degree. C. for another 20 minutes. The lenses are
removed from the solution and rinsed with a solution of 50% aqueous
isopropanol for about 20 to 30 seconds. The lenses are removed from
said solution and placed in a solution of 50% aqueous isopropanol
and 5% aqueous silver nitrate for about five minutes. The lenses
are removed from these solutions and are rinsed with borate
buffered packaging solution (1.4% % sodium sulfate with 30 ppm of
methyl cellulose pH 7.3). These lenses contain between 15 and 20
.mu.g of silver and a haze value of about 20%.
[0029] Further, the invention includes an antimicrobial lens
comprising, a metal salt, made by a method comprise the steps of
[0030] (a) treating a cured lens, with a solution comprising salt
precursor and a swelling agent, [0031] (b) treating the lens of
step (a) with solution comprising a swelling agent for an
appropriate time, and [0032] (c) treating the lens of step (b) with
a solution comprising a metal agent and a swelling agent.
[0033] The terms antimicrobial lens, metal salt, salt precursor,
metal agent, swelling agent solution, appropriate time, and
treating all have their aforementioned meanings and preferred
ranges.
[0034] The aforementioned methods and devices of the invention are
meant to illustrate the invention and suggest methods and devices
that embody the invention. Those knowledgeable in contact lenses as
well as other specialties may find other methods of practicing the
invention. However, those methods are deemed to be within the scope
of this invention.
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