U.S. patent application number 12/581646 was filed with the patent office on 2010-02-18 for silicone contact lenses with wrinkled surface.
This patent application is currently assigned to BAUSCH & LOMB INCORPORATED. Invention is credited to Daniel M. Ammon, JR., Robert M. Braun, Jay F. Kunzler, Yu-Chin Lai, Ravi Sharma.
Application Number | 20100039613 12/581646 |
Document ID | / |
Family ID | 39186209 |
Filed Date | 2010-02-18 |
United States Patent
Application |
20100039613 |
Kind Code |
A1 |
Sharma; Ravi ; et
al. |
February 18, 2010 |
SILICONE CONTACT LENSES WITH WRINKLED SURFACE
Abstract
At least one of the surfaces of a silicone contact lens is a
wrinkled surface, providing the contact lens surface with a desired
topography. The wrinkled surface may include random ridges, either
over the entire surface of the lens, or in a desired pattern on the
surface of the lens.
Inventors: |
Sharma; Ravi; (Fairport,
NY) ; Braun; Robert M.; (Penfield, NY) ;
Ammon, JR.; Daniel M.; (Penfield, NY) ; Kunzler; Jay
F.; (Canandaigua, NY) ; Lai; Yu-Chin;
(Pittsford, NY) |
Correspondence
Address: |
Bausch & Lomb Incorporated
One Bausch & Lomb Place
Rochester
NY
14604-2701
US
|
Assignee: |
BAUSCH & LOMB
INCORPORATED
Rochester
NY
|
Family ID: |
39186209 |
Appl. No.: |
12/581646 |
Filed: |
October 19, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11611317 |
Dec 15, 2006 |
7625598 |
|
|
12581646 |
|
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Current U.S.
Class: |
351/159.34 |
Current CPC
Class: |
C08J 7/12 20130101; C08J
2351/00 20130101; C08G 18/61 20130101; C08J 2383/04 20130101; C08L
75/16 20130101; B29D 11/00076 20130101 |
Class at
Publication: |
351/160.H ;
351/160.R |
International
Class: |
G02C 7/04 20060101
G02C007/04 |
Claims
1. A contact lens comprising a silicone contact lens, wherein a
surface of the lens is wrinkled and includes raised ridges.
2. The contact lens of claim 1, wherein the wrinkled surface is on
a posterior surface of the contact lens, said wrinkled surface
facilitating fluid exchange between the lens and a cornea when the
lens is worn.
3. The contact lens of claim 1, wherein the wrinkled surface is a
silicate surface layer.
4. The contact lens of claim 1, comprised of a silicone hydrogel
copolymer.
5. The contact lens of claim 4, wherein the silicone hydrogel
copolymer is the reaction product of a monomeric mixture comprising
a polysiloxane-containing urethane prepolymer.
Description
[0001] This application is a continuation of application Ser. No.
11/611,317, filed Dec. 15, 2006.
FIELD OF THE INVENTION
[0002] This invention relates to a silicone contact lens wherein at
least one of the surfaces is a wrinkled surface, providing the
contact lens surface with a desired topography. Preferably, the
wrinkled surface is provided as a silicate coating on the contact
lens surface. Generally, the wrinkled surface comprises random
ridges, either over the entire surface of the lens, or in a desired
pattern on the surface of the lens.
BACKGROUND
[0003] Contact lenses made from silicone materials can generally be
subdivided into two major classes, namely hydrogels and
non-hydrogels. Non-hydrogels do not absorb appreciable amounts of
water; whereas, hydrogels can absorb and retain water in an
equilibrium state. Hydrogels generally have a water content greater
than about ten weight percent and more commonly between about
fifteen to about eighty weight percent.
[0004] Silicone contact lenses may tend to have relatively
hydrophobic, non-wettable surfaces. Thus, various publications
disclose methods for rendering the surface of silicone contact
lenses more hydrophilic to improve their biocompatibility or
wettability by tear fluid in the eye. Examples include U.S. Pat.
Nos. 6,193,369; 4,143,949; 5,135,297; 5,726,733; 6,550,915;
6,213,604; 6,348,507; 6,630,243; 6,428,839; 6,200,626; 6,440,571;
6,599,559; 4,055,378; 4,122942; 4,214,014; No. 4,143,949;
4,632,844; 4,312,575; 5,326,584; 4,312,575; U.S. Pat. Nos.
4,632,844; 6,638,563; and 5,760,100; WO 01/34312; WO 04/060431; WO
95/04609 and US 2005-0045589. Examples of commercial silicone
hydrogel contact lenses include: balafilcon A contact lenses, which
include plasma-oxidized silicate surfaces; and lotrafilcon A
contact lenses, which include plasma-deposited hydrocarbon coating
surfaces.
[0005] It is important for contact lenses to be comfortable during
wear. Also, it is important to avoid corneal edema, inflammation
and other adverse effects resulting from contact lens wear,
especially lenses intended for wearing for an extended period of
time. Finally, in the case of contact lenses having a modified
surface, it is important for the modified surface to be optically
clear and able to withstand manufacturing process conditions such
as hydration and autoclaving for sterilization, as well as cleaning
or disinfection treatments performed by the contact lens
wearer.
SUMMARY OF THE INVENTION
[0006] The invention provides a silicone contact lens, wherein a
surface of the lens is wrinkled and includes raised ridges.
[0007] Preferably, a wrinkled surface is provided on a posterior
surface of the contact lens, so as to facilitating fluid exchange
between the lens and a cornea when the lens is worn.
[0008] The invention also provides various methods of achieving the
wrinkled surface. Generally, the method comprises: providing a
silicone contact lens with a modified surface layer; swelling the
contact lens with a polymerizable swelling agent; and polymerizing
the swelling agent; whereby the modified surface layer becomes a
wrinkled surface.
DETAILED DESCRIPTION OF VARIOUS PREFERRED EMBODIMENTS
[0009] The present invention is advantageous for contact lenses
made of a silicone-containing polymer, and especially for silicone
hydrogel contact lenses intended for continuous wear for an
extended period. Hydrogels are a well-known class of materials that
comprise hydrated, cross-linked polymeric systems containing water
in an equilibrium state. Such materials are usually prepared by
polymerizing a mixture containing at least one silicone-containing
monomer and at least one hydrophilic monomer. Either the
silicone-containing monomer or the hydrophilic monomer may function
as a cross-linking agent (a cross-linker being defined as a monomer
having multiple polymerizable functionalities) or a separate
cross-linker may be employed. Applicable silicone-containing
monomeric units for use in the formation of silicone hydrogels are
well known in the art and numerous examples are provided in U.S.
Pat. Nos. 4,136,250; 4,153,641; 4,740,533; 5,034,461; 5,070,215;
5,260,000; 5,310,779; and 5,358,995.
[0010] Examples of applicable silicone-containing monomeric units
include bulky polysiloxanylalkyl (meth)acrylic monomers. An example
of bulky polysiloxanylalkyl (meth)acrylic monomers is represented
by the following Formula I:
##STR00001##
wherein:
[0011] X denotes --O-- or --NR--;
[0012] each R.sub.18 independently denotes hydrogen or methyl;
[0013] each R.sub.19 independently denotes a lower alkyl radical,
phenyl radical or a group represented by
##STR00002##
wherein each R.sub.19'independently denotes a lower alkyl or phenyl
radical; and
[0014] h is 1 to 10.
[0015] Some preferred bulky monomers are methacryloxypropyl
tris(trimethylsiloxy)silane or tris(trimethylsiloxy)silylpropyl
methacrylate, sometimes referred to as TRIS and
tris(trimethylsiloxy)silylpropyl vinyl carbamate, sometimes
referred to as TRIS-VC.
[0016] Such bulky monomers may be copolymerized with a silicone
macromonomer, which is a poly(organosiloxane) capped with an
unsaturated group at two or more ends of the molecule. U.S. Pat.
No. 4,153,641 to Deichert et al. discloses, for example, various
unsaturated groups, including acryloxy or methacryloxy.
[0017] Another class of representative silicone-containing monomers
includes silicone-containing vinyl carbonate or vinyl carbamate
monomers such as:
1,3-bis[4-vinyloxycarbonyloxy)but-1-yl]tetramethyl-disiloxane;
3-(trimethylsilyl)propyl vinyl carbonate;
3-(vinyloxycarbonylthio)propyl-[tris(trimethylsiloxy)silane];
3-[tris(trimethylsiloxy)silyl] propyl vinyl carbamate;
3-[tris(trimethylsiloxy)silyl] propyl allyl carbamate;
3-[tris(trimethylsiloxy)silyl]propyl vinyl carbonate;
t-butyldimethylsiloxyethyl vinyl carbonate; trimethylsilylethyl
vinyl carbonate; and trimethylsilylmethyl vinyl carbonate.
[0018] Another class of silicone-containing monomers includes
polyurethane-polysiloxane macromonomers (also sometimes referred to
as prepolymers), which may have hard-soft-hard blocks like
traditional urethane elastomers. Examples of silicone urethanes are
disclosed in a variety or publications, including Lai, Yu-Chin,
"The Role of Bulky Polysiloxanylalkyl Methacryates in
Polyurethane-Polysiloxane Hydrogels," Journal of Applied Polymer
Science, Vol. 60, 1193-1199 (1996). PCT Published Application No.
WO 96/31792 discloses examples of such monomers, which disclosure
is hereby incorporated by reference in its entirety. Further
examples of silicone urethane monomers are represented by Formulae
II and III:
E(*D*A*D*G).sub.a*D*A*D*E'; or (II)
E(*D*G*D*A).sub.a*D*G*D*E'; (III)
wherein:
[0019] D denotes an alkyl diradical, an alkyl cycloalkyl diradical,
a cycloalkyl diradical, an aryl diradical or an alkylaryl diradical
having 6 to 30 carbon atoms;
[0020] G denotes an alkyl diradical, a cycloalkyl diradical, an
alkyl cycloalkyl diradical, an aryl diradical or an alkylaryl
diradical having 1 to 40 carbon atoms and which may contain ether,
thio or amine linkages in the main chain;
[0021] * denotes a urethane or ureido linkage;
[0022] a is at least 1;
[0023] A denotes a divalent polymeric radical of Formula IV:
##STR00003##
wherein:
[0024] each Rs independently denotes an alkyl or fluoro-substituted
alkyl group having 1 to 10 carbon atoms which may contain ether
linkages between carbon atoms;
[0025] m' is at least 1; and
[0026] p is a number that provides a moiety weight of 400 to
10,000;
[0027] each of E and E' independently denotes a polymerizable
unsaturated organic radical represented by Formula V:
##STR00004##
wherein:
[0028] R.sub.23 is hydrogen or methyl;
[0029] R.sub.24 is hydrogen, an alkyl radical having 1 to 6 carbon
atoms, or a --CO--Y--R.sub.26 radical wherein Y is --O--, --S-- or
--NH--;
[0030] R.sub.25 is a divalent alkylene radical having 1 to 10
carbon atoms;
[0031] R.sub.26 is a alkyl radical having 1 to 12 carbon atoms;
[0032] X denotes --CO-- or --OCO--;
[0033] Z denotes --O-- or --NH--;
[0034] Ar denotes an aromatic radical having 6 to 30 carbon
atoms;
[0035] w is 0 to 6; x is 0 or 1; y is 0 or 1; and z is 0 or 1.
[0036] A representative silicone-containing urethane monomer is
represented by Formula (VI):
##STR00005##
wherein m is at least 1 and is preferably 3 or 4, a is at least 1
and preferably is 1, p is a number which provides a moiety weight
of 400 to 10,000 and is preferably at least 30, R.sub.27 is a
diradical of a diisocyanate after removal of the isocyanate group,
such as the diradical of isophorone diisocyanate, and each E'' is a
group represented by:
##STR00006##
[0037] Another class of representative silicone-containing monomers
includes fluorinated monomers. Such monomers have been used in the
formation of fluorosilicone hydrogels to reduce the accumulation of
deposits on contact lenses made therefrom, as described in U.S.
Pat. Nos. 4,954,587, 5,079,319 and 5,010,141. The use of
silicone-containing monomers having certain fluorinated side
groups, i.e. --(CF.sub.2)--H, have been found to improve
compatibility between the hydrophilic and silicone-containing
monomeric units, as described in U.S. Pat. Nos. 5,387,662 and
5,321,108.
[0038] In one preferred embodiment of the invention, a silicone
hydrogel material comprises (in bulk, that is, in the monomer
mixture that is copolymerized) 5 to 50 percent, preferably 10 to
25, by weight of one or more silicone macromonomers, 5 to 75
percent, preferably 30 to 60 percent, by weight of one or more
polysiloxanylalkyl (meth)acrylic monomers, and 10 to 50 percent,
preferably 20 to 40 percent, by weight of a hydrophilic monomer.
Examples of hydrophilic monomers include, but are not limited to,
ethylenically unsaturated lactam-containing monomers such as
N-vinyl pyrrolidinone, methacrylic and acrylic acids; acrylic
substituted alcohols, such as 2-hydroxyethylmethacrylate and
2-hydroxyethylacrylate and acrylamides, such as methacrylamide and
N,N-dimethylacrylamide, vinyl carbonate or vinyl carbamate monomers
such as disclosed in U.S. Pat. No. 5,070,215, and oxazolinone
monomers such as disclosed in U.S. Pat. No. 4,910,277. Other
hydrophilic monomers will be apparent to one skilled in the
art.
[0039] Silicone elastomer contact lenses are formed of a silicone
elastomer, such as various polydimethylsiloxane materials. In
contrast to silicone hydrogel copolymers, silicone elastomers are
more rubbery and hydrophobic, generally lack a hydrophilic
co-monomer, and do not absorb appreciable amounts of water.
[0040] The above silicone materials are merely exemplary, and other
materials for use as substrates that can benefit by this invention
have been disclosed in various publications and are being
continuously developed for use in contact lenses and other medical
devices. For illustrative purposes, the following description
focuses on silicone hydrogel copolymers, although various aspects
of the invention are applicable for silicone elastomer contact lens
materials.
[0041] Some monomer mixtures for silicone hydrogels include an
organic diluent in the initial monomeric mixture that is unreactive
with the monomeric components. Suitable organic diluents include,
for example, monohydric alcohols, with C.sub.6-C.sub.10
straight-chained aliphatic monohydric alcohols such as n-hexanol
and n-nonanol being especially preferred; diols such as ethylene
glycol; polyols such as glycerin; ethers such as diethylene glycol
monoethyl ether; ketones such as methyl ethyl ketone; esters such
as methyl enanthate; and hydrocarbons such as toluene. Generally,
the diluent when present is included at five to sixty percent by
weight of the initial monomeric mixture, with ten to fifty percent
by weight being especially preferred. The diluent may be removed
from the contact lens, after casting, by evaporation and/or
exchange with an extracting solvent.
[0042] Other additives commonly employed in the silicone hydrogel
monomer mixture include polymerization initiators, tints, and UV
absorbing agents, among others.
[0043] The initial monomer mixture is polymerized to form a
copolymer. Contact lenses may be manufactured by various
conventional techniques, to yield a shaped article having the
desired posterior and anterior lens surfaces. As examples,
spincasting methods are known, including those disclosed in U.S.
Pat. Nos. 3,408,429 and 3,660,545; and static casting methods are
known, including those disclosed in U.S. Pat. Nos. 4,197,266 and
5,271,875. Generally, static cast molding involves dispensing the
liquid monomer mixture in the mold cavity of a mold assembly
including a posterior mold part and an anterior mold part, the
posterior mold part including an optical mold surface for forming
the posterior contact lens surface, and the anterior mold part
including an optical mold surface for forming the anterior contact
lens surface. Then, while the monomer mixture is in this mold
cavity, the monomer mixture is exposed to thermal energy and/or
light energy to cure the monomer mixture and form the
copolymer.
[0044] According to conventional contact lens manufacturing, the
cast contact lens is removed from the mold assembly. The contact
lens is typically extracted with a solvent to remove any unrelated
monomers or other undesired materials from the cast lens; an
organic solvent, such as isopropyl alcohol, water, or an aqueous
solution may be used for extraction. The lens is hydrated and
packaged in an aqueous solution, whereby the silicone hydrogel
copolymer absorbs and retains water, and the packaged contact lens
is typically sterilized, such as by autoclaving.
[0045] For the methods of this invention, the cast contact lens may
be removed from the mold assembly prior to treating the lens.
Alternately, the cast contact lens may be retained on a mold part,
where one surface of the lens is exposed for treatment. Generally,
the lens will be treated by the methods of this invention
subsequent to casting of the lens, and prior to a final hydration
of the silicone hydrogel copolymer.
[0046] This invention provides at least one surface of the contact
lens with a wrinkled surface. Both the posterior and anterior
surfaces of the contact lens may have this wrinkled surface, or
only one of the surfaces may be wrinkled. Additionally, if desired,
only selected portions of the posterior and/or anterior surfaces
may be wrinkled. According to preferred embodiments, the posterior
surface of the lens is wrinkled so as to facilitate improved fluid
exchange between the posterior surface of the lens and the cornea
while the lens is worn.
[0047] The wrinkled surface generally includes a series of raised
ridges with depressions therebetween, wherein the raised ridges
have heights of 0.5 to 1000 nm with respect to such depressions.
More preferably, the raised ridges have heights of 10 to 600 nm
with respect to such adjacent depressions. The raised ridges will
generally be randomly interspersed. Individual raised ridges may
have various shapes, such as circular, cylindrical or curved
shapes.
[0048] Various contact lens publications seek to achieve a smoother
surface, under the theory that a smoother surface will be more
comfortable. In contrast, the present invention provides a contact
lens with a more textured surface, the textured surface not
compromising comfort but providing the contact lens surface with a
desired texture, such as to provide the improved fluid exchange
between the contact lens and the cornea.
[0049] According to various preferred embodiments, the contact lens
is initially provided with a modified surface layer, i.e., the
surface of the cast contact lens is modified, and subsequently,
this modified surface becomes the wrinkled surface. For example, a
surface of the lens contact lens may be modified by treating it
with plasma, or other energy.
[0050] As a further example, the contact lens surface may be
modified to provide a silicate surface layer thereon. The silicate
surface may be provided by subjecting the surface to strong
oxidation, whereby a considerable portion of the silicon at the
surface of the lens is converted to silicate. The silicate surface
may be formed by plasma treatment of the contact lens surface is an
oxygen-containing environment. The plasma surface treatment
involves passing an electrical discharge through the
oxygen-containing gas at low pressure. The electrical discharge is
usually at radio frequency (typically 13.56 MHz), although
microwave and other frequencies can be used. The term plasma herein
also encompasses corona discharge. The electrical discharge in a
plasma is absorbed by atoms and molecules in their gaseous state,
thus forming a plasma that interacts with the surface of the
contact lens. With an oxidizing plasma, e.g., O.sub.2 (oxygen gas),
water, hydrogen peroxide, air, and the like, the plasma tends to
etch the surface of the lens, creating radicals and oxidized
functional groups. Plasma treatment, when using an electric
discharge frequency of 13.56 Mhz, is suitably between about 10 and
1000 watts, preferably 100 to 500 watts, a pressure of about 0.001
to 5.0 torr, preferably 0.1 to 1.0 torr, for a time period of about
10 seconds to 60 minutes, preferably about 1-10 minutes. If both
surfaces are being treated, the sides may be treated concurrently
or sequentially.
[0051] As another example, a silicate surface layer may be formed
by exposing the contact lens surface to UV radiation in an ozone
environment.
[0052] After forming the modified surface layer, which in the
illustrated embodiment is a silicate surface layer, the contact
lens is swelled with a polymerizable swelling agent. This agent is
polymerizable, i.e., it is a monomeric material. Preferred agents
include ethylenic unsaturation, such that the agent is
polymerizable by free radical polymerization. This agent also
serves to swell the contact lens copolymeric material which is
exposed to the agent. Preferably, the agent swells the contact lens
copolymer by at least 15% by volume, more preferably, at least 25%
by volume. Representative swelling agents include alkyl
(meth)acrylates, especially n-butyl acrylate; alcohol-containing
(meth)acrylates, especially 2-hydroxyethyl methacrylate and
glyercol methacrylate; and epoxy-containing (meth)acrylates,
especially glycidyl methacrylate.
[0053] It is preferred that the swelling agent is mixed with a
cross-linking monomer, such as a di(meth)acrylated monomer.
Representative crosslinking monomers include ethylene glycol
dimethacrylate, diethyleneglycol methacrylate, hexamethylene
dimethacrylate, among others. It is also preferred that the
swelling agent is mixed with a polymerization initiator, for
example, a UV initiator if the swelling agent is polymerized with
UV radiation, or a thermal initiator if the swelling agent is
polymerized with thermal energy.
[0054] The contact lens may be immersed in the polymerizable
swelling agent. Alternately, the contact lens may be exposed to the
polymerizable swelling agent by other methods such as spraying or
dip coating. Generally, the contact lens should be exposed to the
swelling agent for sufficient time, generally one to ten minutes,
so that this agent penetrates beneath the modified surface layer,
preferably to a depth of at least 5 nm. Depending on the amount of
swelling, the silicate layer will become wrinkled to a varying
degree. The particular swelling agent used, and the time of
exposure of the contact lens with the swelling agent, may be varied
selectively to obtain a desired degree of wrinkling.
[0055] At this stage, it is preferred that excess polymerizable
swelling agent at the surface of the lens is removed. In other
words, it is desirable that there is a greater amount of this agent
remains at the depth of 5 nm and below, than nearer the surface.
The removal of excess swelling agent may be done by wiping, air
blow-off, or the like. If a more vigorous removal method is need, a
solvent may be used to remove the excess swelling agent. Suitable
solvents are those in which the swelling agent is soluble, for
example, acetone, ethanol, isopropanol, and tetrahydrofuran.
[0056] Subsequently, the swelling agent is polymerized, such as by
exposure to light energy (such as UV radiation) and/or thermal
energy. Polymerization of the swelling agent serves to stabilize
the wrinkled modified surface layer. In other words, the
polymerized swelling agent anchors the wrinkled modified surface
layer to the underlying silicone copolymer substrate, resulting in
a wrinkled, robust coating that does not delaminate from the
contact lens surface and in a wrinkled, durable wettable
coating.
[0057] Optionally, the surface of the contact lens may be further
modified, such as by grafting or plasma-deposition of a material to
the surface. For example, in the case where the contact lens
includes a silicate surface layer, a carbon layer may be deposited
thereon; an example is subjecting the surface to a plasma
polymerization deposition with a gas made from a diolefinic
compound having 4 to 8 carbon atoms, in the absence of oxygen, thus
forming a carbon layer on the surface on the lens; this carbon
layer may be rendered hydrophilic by subjecting it to a second
plasma oxidation or by applying a secondary coating of a
hydrophilic polymer which is attached thereto.
[0058] It will be appreciated that various combinations of surface
characteristics may be employed. As one specific example, a
silicate coating may be formed on both surfaces of the silicone
contact lens. The posterior side of the lens is treated for a
relatively longer period with the polymerizable swelling agent, so
that the posterior silicate surface layer becomes wrinkled, thus
providing a textured surface for fluid exchange when the lens is
worn. In contrast, the anterior side of the lens is treated for a
relatively shorter period with the polymerizable swelling agent, so
that the anterior surface has very little or no wrinkling; a carbon
coating or other coating may be applied to the silicate surface
layer on the anterior surface.
EXAMPLE 1
[0059] Table 1 discloses a monomer mixture for forming a silicone
hydrogel lens material useful for the present invention.
TABLE-US-00001 TABLE 1 Component Parts by Weight TRIS-VC 55 NVP 30
V.sub.2D.sub.25 15 VINAL 1 n-nonanol 15 Darocur initiator 0.2 tint
agent 0.05
[0060] The following materials are designated above:
TABLE-US-00002 TRIS-VC tris(trimethylsiloxy)silylpropyl vinyl
carbamate NVP N-vinyl pyrrolidone V.sub.2D.sub.25 a
silicone-containing vinyl carbonate as previously described in U.S.
Pat. No. 5,534,604. VINAL N-vinyloxycarbonyl alanine Darocur
Darocur-1173, a UV initiator tint agent
1,4-bis[4-(2-methacryloxyethyl)phenylamino] anthraquinone
EXAMPLE 2
[0061] Table 2 discloses a monomer mixture for forming a
polyurethane silicone hydrogel formulation useful in the present
invention.
TABLE-US-00003 TABLE 2 Component Parts by Weight ID3S4H 55 TRIS 20
DMA 25 UV Absorber 0.5 n-Hexanol 20 Irgacure-819 initiator 0.5 Tint
agent 150 ppm
[0062] The following materials are designated above:
TABLE-US-00004 TRIS tris(trimethylsiloxy)silylpropyl methacrylate
DMA N,N-dimethylacrylamide ID3S4H a polysiloxane-containing
urethane prepolymer of Formula (VI) where R.sub.27 is the residue
of isophorone diisocyanate, and having a molecular weight about
4000. Irgacure-819 a UV initiator
EXAMPLE 3
[0063] Table 3 discloses a monomer mixture for forming a
polyfumarate silicone hydrogel formulation useful in the present
invention.
TABLE-US-00005 TABLE 3 Component Parts by Weight F.sub.2D.sub.20 20
TRIS 40 DMA 40 n-Hexanol 5 Darocur initiator 0.5 Tint Agent 150
ppm
[0064] The following materials are designated above:
TABLE-US-00006 TRIS tris(trimethylsiloxy)silylpropyl methacrylate
DMA N,N-dimethylacrylamide F.sub.2D.sub.20 a silicone-containing
crosslinking resin as previously described in U.S. Pat. Nos.
5,374,662 and 5,496,871.
EXAMPLE 4
[0065] This Example illustrates a process for forming silicone
hydrogel contact lenses for a method of this invention. The monomer
mixture of Table 2 was injected onto a clean polypropylene anterior
mold half and covered with the complementary polypropylene
posterior mold half. The mold halves were compressed, and the
mixture was cured by exposure to UV radiation. The top mold half
was removed, and the lenses were maintained in a forced air oven to
remove the majority of the n-hexanol diluent. The lenses are
removed from the bottom mold half, extracted in isopropanol, and
then dried.
EXAMPLE 5
[0066] The lenses are placed in a Branson RF plasma unit (13.56
MHz), or similar unit, on a tray which elevates the lenses between
two electrodes and allows the flow of gas around the lenses. The
plasma unit is evacuated of air, then oxygen gas or air is
introduced into the chamber, and the plasma is ignited. After
completion of the plasma treatment, the lenses are removed from the
plasma unit and immersed in a mixture consisting of n-butyl
acrylate (75%), ethylene glycol dimethacrylate crosslinker (25%)
and photoinitiator (Igracure.RTM. 819 initiator). This
acrylate-containing mixture is allowed to remain on the silicate
layer until such time has evolved that sufficient penetration by
the swelling agent into the silicone hydrogel has taken place,
typically, but not limited to 1-5 minutes, and the silicate layer
assumes a wrinkled texture. After this time the excess
acrylate-containing mixture is removed by wiping the surface with a
clean cloth containing acetone. The lens samples are then placed in
a chamber and exposed to UV radiation, to polymerize the n-butyl
acrylate monomer mixture that has imbibed into the silicone
hydrogel copolymer. The lenses are then hydrated in deionized water
until equilibrated, followed by placing in borate buffered saline
and autoclaving at about 120.degree. C.
[0067] Optionally, prior to hydration, an additional coating may be
added to the posterior surface, the anterior surface, or both these
surfaces.
[0068] As an alternative to forming a silicate coating on the lens
surface, plasticizers may be used to create the wrinkled surface.
An illustration of this approach involves, initially, abstracting
hydrogen from the desired lens surface or portions thereof. For
example, a polymerization initiator may be applied to the contact
lens surface; commercially available initiators include
benzophenones, thioxanthones, and phosphine oxides, including those
available under the tradenames Irgacure and Darocur. An
initiator-containing solution is applied to and reacted with the
lens surface, such as by spray coating, a gas nebulizer or transfer
to the surface from the contact lens mold.
[0069] Once hydrogen is abstracted from the upper (near) regions of
the lens surface, free radicals will remain which are available to
react with vinyl-containing plasticizers in the near surface
region. Such plasticizers preferably include (meth)acrylate
functionality, such as: (meth)acrylated silicone based materials,
like (meth)acrylated poly(dimethyl siloxane)s; and (meth)acrylated
aromatic-containing compounds, like phenoxyethyl acrylate,
isoborneol acrylate, or benzyl acrylate. Other specific examples
include:
##STR00007##
[0070] These (meth)acrylated plasticizers may be applied to the
lens surface by the aforementioned methods of such as by spray
coating, a gas nebulizer or transfer to the surface from the
contact lens mold, followed by curing, including application of
heat, UV radiation or visible light. Then, the contact lens may be
treated with the swelling agents, discussed above. Generally, these
plasticizers are chosen so that once cured in the near region of
the contact lens, the resulting polymers have a different polymer
backbone structure and/or modulus from the contact lens bulk
copolymer. Infusion with swelling agents like n-butyl acrylate
create wrinkles, as disclosed above.
[0071] As a further alternative, the contact lens bulk copolymer
may include a co-monomer that provides the lens surface with
residual allyl groups. Examples of such co-monomers, included in
the initial monomer mixture used to cast the contact lens, are
allyl (meth)acrylates. The (meth)acrylate functionality of this
co-monomer reacts with the other co-monomers in the monomer
mixture, whereas the allyl functionality remains in the near region
of the contact lens. The allyl functionality may be reacted with a
hydrocarbon or silane compound with thio end groups. The
hydrocarbon or silane compound is a compound able to swell the
contact lens bulk copolymer, and further containing at least one
thio end group for reacting with the residual allyl functionality
of the bulk contact lens copolymer. The thio-terminated compounds
will covalently bind to the exposed allyl groups which will allow
the hydrocarbon and silane materials to interact and swell the
polymer in the near surface region, thus creating a mismatch in
polymer backbone and/or modulus. Then, a swelling agent such as
n-butyl acrylate may then be infused, as discussed above.
[0072] As an additional alternative, various polymeric materials,
including polylactides, polyglycolides, polydioxananes,
polycaprolactones, polyethylene glycols, polypropylene glycols,
polyethylene and propylene oxides, fluorocarbons, fluorosiloxanes,
polyurethanes, and copolymers thereof, have polymeric backbones and
moduli that differ from the contact lens bulk copolymer. The use of
a thin film or infused layer may be incorporated onto or within the
contact lens, to establish a polymer backbone and/or modulus
mismatch which will induce stress and ultimately promote wrinkling
once a swelling agent is infused into the polymer.
[0073] For any of the aforementioned methods, portions of the
contact lens surface may be masked during treatment, such that the
masked portions exhibit less wrinkling than the unmasked
portions.
[0074] It will be understood that various modifications may be made
to the embodiments disclosed herein. Therefore the above
description should not be construed as limiting, but merely as
exemplifications of preferred embodiments. Other arrangements and
methods may be implemented by those skilled in the art without
departing from the scope and spirit of this invention. Moreover,
those skilled in the art will envision other modifications within
the scope and spirit of the features and advantages appended
hereto.
We:
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