Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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1 337320
CONTACT LENS CLEANING WITH DISSOLVING ABRADANT
DESCRIPTION
Technical Field
The present invention relates to the cleaning of hard
and soft contact lenses. As is by now well known, contact lenses
accumulate proteinaceous and lipid-type deposits which must be
removed from the lens to promote clear vision and proper hygiene.
A variety of products have been proposed for this purpose. Some
are based on the action of enzymes or surfactants.
PRIOR ART
Another type of product, disclosed in U.S. Patent No .
4,394,179, comprises small, insoluble particles which are rubbed
against the lens surface to dislodge debris. Such a product runs
the risk of damaging the surface of the lens over a number of
successive uses, and requires extremely thorough washing of the
lens to ensure that every particle has been removed from the lens
before the lens is reinserted into the eye. Otherwise,
irritation and even tissue damage can be inflicted on the eye.
There is thus a need for a product for removing
deposits from hard and soft contact-lenses which will not damage
the lens and which will pose a reduced risk that unwanted
irritating particles would be introduced into the eye. While
facial cleansers containing dissolving abradant cleansers have
been disclosed in U.S. Patent No. 4, 048 ,123 and U.S. Patent No .
3,944,506, it has long been believed that such cleansers would
be damaging to contact lenses, particularly soft contact lenses.
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2 1 337320
SummarY of the Invention
In one aspect, the present invention comprises abradant
compositions for cleaning contact lenses, comprising:
as an abradant component;
an effective amount of a slightly water soluble, non-toxic
physiologically acceptable room temperature solid inorganic acid
having a ~x;rum particle size of about 40 microns, especially
10about 10 microns and in both instances no more than about 0.01
wt.% of the particles being larger and preferably no particles
being larger. In both instances (i.e., where the particles are
about 40 microns or about 10 microns), smaller particles may be
present, or;
15as an effective amount of a slightly water soluble, non-
toxic physiologically acceptable inorganic salt having a particle
size less than about 210 microns, preferably not more than 105
microns;
where said inorganic acid or said inorganic salt has a
hardness less than about 6 on the Mohs scale, preferably less
than about 4 on the Mohs scale.
Preferably, the compositions further comprise an amount
of liquid less than the amount required to dissolve at ambient
temperature the entire amount of said inorganic acid or said
inorganic salt.
In another aspect, the present invention comprises a
composition comprising the components defined above, and further
comprising one or more surfactants.
3 1 337320
Detailed DescriPtion of the Invention
As indicated, the present invention provides effective
cleaning of hard and soft contact lenses and is safe to the lens
and safe to the eye of the lens wearer. Other advantages will
be apparent from the following description.
The lens cleaning and disinfecting regimen in
accordance with the present invention is useful with any contact
lenses of the hard and soft type. Hard lenses include the well-
known lenses made from poly(methylmethacrylate), as well as those
based on various monomers in which a substituted silicone (such
as tris(trimethylsiloxy)silyl) is connected through an alkylene
bridge to an acrylic or methacrylic moiety. Soft lenses with
which the present invention is useful include any of the large
variety of hydrophilic homopolymers and copolymers, including
those based on hydroxyethylmethacrylate alone or copolymerized
with, for example, vinyl pyrrolidone, methacrylic acid,
methylmethacrylate, diacetone acrylamide and the like. Examples
of other suitable hydrophilic lens polymers abound in the
literature and will be readily apparent to those of ordinary
skill in the art. Soft lenses with which the present invention
is useful also include those soft, non-hydrophilic lenses made
from various modifications of silicone rubber.
The abradant component is preferably sparingly soluble
in water, normally being soluble in water in an amount of less
than about 30 weight percent at 40C and less than about 10
weight percent at 20C. The abradant component should have a
solubility in water at 20C of at least 0.5 weight percent, and
usually at least 1 weight percent, and preferably at least about
3 weight percent. The abradant component must be non-toxic and
4 1 337320
non-irritating to the eye.
The abradant component must have particle size such
that rubbing the lens in the palm of a hand under normal finger
pressure will not damage the lens. Where the abradant component
comprises particles of a room temperature solid inorganic acid,
such particles will have a particle size of about 40 microns,
especially about 10 microns and in both instances no more than
about 0.01 wt.~ of the particles will be larger, but preferably,
no particles will be larger. In both instances, (i.e., where the
room temperature solid inorganic acid particles are about 40
microns or about lo microns) smaller particles may be present so
that the particles comprising the about 40 micron particles in
one instance or the about 10 micron particles in the other
instance will comprise in either instance from about 98~ to about
99% of the particles. Of course, any of the abradant components
can be a mixture of particles having a variety of particle sizes.
A particle size of less than about 210 microns (U.S. Sieve Series
No. 70), preferably less than about 105 microns, and more
preferably less than about 74 microns is generally satisfactory
where the abradant component comprises the inorganic salt. In
the more preferred embodiments, at least 99% should be about 210
microns or smaller, and preferably at least 98% is about 149
microns or smaller (and more preferably at least 98% is about lOS
microns or smaller) for such inorganic salt.
The abradant component will generally have a hardness
less than about 6 and preferably falling in the range of about
1.5 to about 4 on the Mohs scale. The hardness and size of the
particles are both significant to the ability of the particles
to remove proteinaceous and lipid material from the surface of
the lens, without damaging the lens itself. The size of the
particles will also affect the rapidity with which the particles
1 337320
dissolve upon contact with additional amounts of water when the
lens is rinsed and/or stored in an appropriate solution. As
indicated, however, the abradant component must be sparingly
soluble in water so that the lens cleaning composition of the
present invention can be prepared and stored for hours, days or
weeks without the abradant component dissolving into the liquid
which is present in the composition.
The most preferred room temperature solid inorganic
acid abradant component useful in this invention comprises boric
acid Boric acid, as that term is used herein is intended to
include grades of boric acid (e.g., H3BO3) such as boric acid
impalpable NF that are available from standard commercial
sources, as well as various boric acid compounds and
compositions, such as mixtures of boric acid (e.g., H3BO3) with
salts to change its solubility in water (i.e., decrease or
increase its solubility), such salts comprising alkali metal
salts including alkali halides, sulfates or borates. For
example, the water solubility of boric acid (H3BO3) is decreased
by sodium chloride and lithium chloride and is increased by
sodium sulfate, potassium chloride and potassium sulfate. Basic
anions and other nucleophiles such as fluorides and borates
increase the solubility of boric acid (H3BO3). By adding such
salts to the boric acid, the degree of solubility can be
controlled and consequently, the amount of particles in the boric
acid solution can be controlled, i.e., increased or decreased.
Boric acid suitable for the present invention (including mixtures
thereof with such salts) is further described in Kirk-Othmer,
EncYclopedia of Chemical Technoloqy, Third Edition; Vol. 4, pp.
71-80, 108-110.
The preferred inorganic salt component useful in this
invention is sodium borate, by which is meant any of the salts
6 1 337320
of sodium and borate (e.g., boric acid or boric acid anhydride).
The most preferred sodium borate is borax, that is, sodium borate
decahydrate. Satisfactory borax products useful in the practice
of this invention include those known as "NF Grade" borax in the
powdered or impalpable grades available commercially from U.S.
Borax Company.
The abradant component should be present in undissolved
form in the cleaning composition in an amount effective to
perform the desired lens cleaning function. The amount will
generally be in a range up to about 50% by weight of the
composition. Lesser amounts, i.e., less than 30% or even less
than 20~ can also be employed, provided that the amount of water
and the other components present are adjusted accordingly so that
the abradant component does not dissolve upon standing.
Generally, the undissolved abradant should comprise at least 1,
and preferably at least 5, weight percent of the composition.
The composition of the present invention also
preferably includes a surfactant component, by which is meant one
or more surfactants. Although the surfactant component strictly
speaking is not required for the abradant component to perform
its function, the surfactant aids in removal of lens deposits.
In addition, it has been surprisingly found that the combination
of a surfactant component with the abradant component works
better than either component used alone. The surfactant
component should comprise one or more compounds capable of
solubilizing one or more of the types of soilants known as lipid
material, mucins, and proteinaceous material, thereby aiding in
the removal of such soilants from the lens surface. The
surfactant component should have an HLB value of about 7 to about
18.
7 1 337320
Among different anionic surfactants usable in the
invention, particular mention may be made of the alkaline salts,
ammonium salts, amine salts or amino alcohol salts of the
following compounds:
the alkylsulfates, alkylether sulfates, alkylamide
sulfates and ether sulfates, alkylarylpolyether sulfates,
monoglyceride sulfates,
the alkylsulfonate, alkyl amide sulfonates, alkylaryl
sulfonates,
alpha-olefine sulfonates,
the alkyl sulfosuccinates, alkyl ethersulfosuccinates,
alkylamide sulfosuccinates,
the alkylsulfosuccinamates,
the alkyl sulfoacetates, the alkylpolyglycerol
carboxylates,
the alkyl phosphates, alkylether phosphates,
the alkylsarcosinates, alkylisethionates, alkyl
taurates,
the alkyl radical of all these compounds being a carbon
chain of 12 to 18 atoms of carbon.
Useful anionic surfactants can be represented by the
formula ROSO3M, ROC(O)CH2SO3M or RO(C2H40)XSO3M wherein R is alkyl
or alkenyl of about 10 to about 20 carbon atoms, x is 1 to 10,
and M is a water-soluble cation such as ammonium, sodium,
potassium, or triethanolamine. The alkyl ether sulfates useful
in the present invention include condensation products of
ethylene oxide and monohydric alcohols having about 10 to about
20 carbon atoms. Preferably, R has 14 to 18 carbon atoms in the
alkyl sulfates, alkyl ether sulfates, and alkyl sulfoacetates.
The alcohols can be derived from fats, such as coconut oil or
tallow, or can be synthetic. Such alcohols are reacted with 1
to 10, and preferably 3, moles of ethylene oxide and the
8 1 337320
resulting mixture of molecular species is sulfated and
neutralized.
Other examples of anionic surfactants include the
reaction products of fatty acids esterified with, e.g.,
isethionic acid and neutralized with sodium hydroxide, where the
fatty acids are derived, for instance, from coconut oil; or
sodium or potassium salts of fatty acid amides of methyl tauride
in which the fatty acids, for example, are derived from coconut
oil. Still other anionic surfactants include those designated
as succinamates. This group includes such surfactants as
disodium N-octadecylsulfosuccinamate; tetra sodium N-(1,2-
dicarboxyethyl)-~-octadecylsulfosuccinamate; and dioctyl esters
of sodium sulfosuccinic acid. Other suitable anionic surfactants
include olefinsulfonates having about 12-24 carbon atoms.
In addition, one or more non-ionic surfactants are also
useful. Useful non-ionic surfactants include those having the
formula:
(Acyl)-(OAlk)nOH
wherein (Acyl) is derived from a C12-C20 fatty acid such as oleic,
lauric, or palmitic acid, and (OAlk) is a polyoxyalkylene moiety
in which each alkylene unit "Alk" has the formula CzH4 or C3H6 and
n is 2 to 60. Other satisfactory non-ionic surfactants include
those having the formula (Alk) - (OAlk)nOH wherein (Alk) is a
saturated or a monosaturated alkyl or alkylene moiety having 10
to 20 carbon atoms and (OAlk) and n are as defined above.
Further examples of satisfactory non-ionic surfactants include
those generically known as "polysorbate", which can be generally
defined as various mixtures of C12-C20 fatty acid esters of
sorbitol, and sorbitol anhydride condensed with 4-20 moles of
9 1 :~37320
ethylene oxide.
One group of preferred surfactants are the non-ionic
surfactants known as hydroxyalkylated surfactants and
polyoxyalkylated surfactants. Extremely effective at very low
concentrations are N-hydroxyalkylated carboxamides of fatty acids
of from 10-18 carbon atoms, preferably of from 12-14 carbon atoms
and having no or one site of olefinic unsaturation. There will
normally be up to two hydroxyalkyl groups of from 2-3 carbon
atoms, which may be same or different.
Thepolyoxyalkylated non-ionic surfactants may comprise
solely a chain of 2 to 60 polyoxyalkylene groups of from 2-3
carbon atoms each, or may have such a polyoxyalkylene chain
lS bonded directly or indirectly to an aliphatic chain of from 10-10
carbon atoms. The polyoxyalkylene chain may be a homo-oligomer
or co-oligomer, with the homo-oligomer normally being ethyleneoxy
groups and the co-oligomer being a random or block co-oligomer
of ethyleneoxy and propyleneoxy groups.
Another satisfactory non-ionic surfactant is
polyalkyleneoxy modified silicone, which is a silicone modified
with polyalkyleneoxy groups wherein each alkylene group contains
2 or 3 carbon atoms. Illustrative compositions are described in
U.S. Patent Nos. 2,834,748 and 3,505,377. The compositions
employed in this invention have a viscosity at 25C of from about
900-1600 cs, more usually from about 100-1500 cs. The specific
gravity at 25C will be about 20-22, more usually about 21 dynes
per cm. The surface tension at a concentration of 1% in water
25C will generally be from about 25-28, more usually from about
26-27 dynes per cm. At a concentration of 1 weight percent in
water, the cloud point will be below 50C, usually below about
40C, and will usually be above about 30C. The silicone polymer
1 337320
will usually be a block copolymer with the polyalkyleneoxy
polymer.
The siloxy units are preferably dimethylsiloxy units
while the alkylenoxy units are preferably ethyleneoxy or 1,2-
propyleneoxy units. The number ratio of ethyleneoxy units to
other units (dimethylsiloxy and propyleneoxy) will be at least
0.5:1 and generally not more than about 5:1; usually not more
than about 2:1. The molecular weight of the copolymer will
generally be from about 4,000 to 10,000, preferably about 5,000
to 7,500. The terminal groups of the polymer will usually be a
C1-C3 alkylsiloxy group at one end and alkoxy group of from 1 to
6 carbon atoms at the other end.
The preferred siloxane-polyoxyalkylene copolymers
employed in this invention will have the following formula:
TSi(o(siMe2o)x(cnH2no)yy)3
wherein:
each of the chains may be the same or different, the values
given for x and y being the average over the entire composition;
x is a number in the range of 3 to 10, usually 4 to 8;
y is a number in the range of 20 to 50, usually 25 to 40;
n is an integer of from 2 to 3;
T is alkyl of from 1 to 3 carbon atoms, usually methyl; and
Y is alkyl of from 1 to 6 carbon atoms, usually 3 to 4
carbon atoms.
More preferably, the siloxane-polyoxyalkylene block
copolymer will have the following formula:
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1 337320
11
TSi (O (SiMe20) x (CzH40) a (C3H6o) bY) 3
wherein:
each of the ~.h~i nc may be the same or different, the
values given x, a and b being the average over the entire
composition;
x is a number in the range of 4 to 8, usually 5 to 7;
a is a number in the range of 15 to 30, usually 15 to
25;
b is a number in the range of 10 to 20, usually 12 to
16; and.
the other symbols have been defined previously.
Another satisfactory surfactant is a fatty acid amide
or nitrogen analog thereof, of an amine which is at least
disubstituted by from 2 to 3 aliphatic groups, two of the groups
having oxygen containing substituents such as oxy or carbonyl,
particularly non-oxo carbonyl. For the most part, the fatty acid
amides which are employed in the subject invention will have the
following formula:
X~
ll m
R - C - ~ - Y
wherein:
R is a saturated or mono-saturated alkyl or alkylene
group, preferably saturated, of from 9 to 18, preferably 9 to 13,
usually 11 carbon atoms;
X is oxygen or nitrogen;
m is 0 when X is oxygen and 1 when X is nitrogen,
wherein the nitrogen to which Y and Z is attached is positive;
1 337320
12
Y is an aliphatically saturated group of from 2 to 4
carbon atoms and from 1 to 3 oxygen atoms as the only
heteroatoms, the oxygen atoms being present as hydroxy or other,
there being at least two carbon atoms between heteroatoms, or
S carboxy, with the proviso that when oxygen is present as carboxy,
the carbonyl group may be present as the acid or its
physiologically acceptable salt, e.g., sodium; and
Z is a saturated aliphatic group of two to three,
usually two carbon atoms and from 1 to 2 oxygen atoms as the only
heteroatoms, which may be present as hydroxy, ether, or carbonyl
and the carbonyl group may be present as the acid or a
physiologically acceptable salt.
When the fatty acid amide is of the formula when m is
0, it will for the most part have the formula:
R1 _ C - N _
lz
wherein:
R1 comes within the definition of R;
y1 and Z1 are the same or different and are
hydroxyalkyl of from 2 to 3 carbon atoms, the oxygen and nitrogen
being separated by at least 2 carbon atoms.
When the fatty acid amide is of the formula when m is
1, it preferably has the following formula:
N
R" - C ~ N - Y"
Z "
13 1 337320
wherein:
R" comes within the definition of R;
Y" is an aliphatically saturated carboxylic acid group
of from 2 to 4 carbon atoms having from 0 to 1 ethereal oxygen
and free of other heterofunctionalities;
Z" is an aliphatically saturated carboxylic acid group
of from 2 to 3 carbon atoms, and free of other
heterofunctionalities;
wherein the acids and quaternary ammonium groups have
lo physiologically acceptable cations, e.g., zwitterion, proton, or
alkali metal (preferably sodium).
Of particular interest are compounds of the following
formula:
N~\~
R - C - ~ - CH2CH20cH2co2Na
CH2C02Na
wherein R is of from 9-13 carbon atoms, usually 11 carbon atoms.
The imidazoline compounds may be prepared in accordance
with the teaching of U.S. Patent No. 2,586,496.
Of particular interest are the lauramide of
diethanolamine and 2-undecyl-3-carboxymethyl-3-(2'-
(carboxymethoxy)-ethyl)-l-imidazoline, usually as the disodio
hydroxy salt.
Particularly, in combination with the diethanolamine
amide or homolog, small amounts of organic salts of
diethanolamine or its homologs may be used, particularly salts
1 337320
14
of fatty acids of from 16 to 18 carbon atoms having from 0 to l
site of ethylenic unsaturation, e.g., oleate salts or alkyl-
benzenesulphonate salts, wherein the alkyl group is straight or
branched chain, and is normally of from 6 to 18, more usually
from 8 to 14 carbon atoms. When present, the salts will
generally be used in a mole ratio of salt to amide in the range
of 1:2-4, more usually 1:3. That is, from about 20 to 33,
usually 25 mole ~, of the amide is replaced with the salt.
Satisfactory surfactants are commercially available
under a wide variety of trade names, such as *"Pluronic",
*"Steol", *"Miranol", *"Tween", *"Igepal", *"Brij", and *"Myrj".
These surfactants include those with the following general
formulas:
"Pluronic": Poly oxyalkylene compounds of the formula
HO(cH2cH2o)x(cH(cH3)cH2o)y(cH2cH2o)zH
wherein the sum of (x + y + z) is 2-60.
"Steol" : Alkali (e.g., sodium or ammonium) salt of the
sulfate ester of the polyethylene glycol either of lauryl
alcohol, the ester having the formula
CH3(CH2)10cH2(ocH2cH2)1-12oso3-
"Miranol": Amphoteric surfactants having the formula
RC(o)NHcH2cH2N(R1)1-2(cH2)1-2cooH
wherein RC(0) is the acyl radical of coconut, lauric, stearic,
*Trade mark
1 337320
caprylic, or oleic acid; and R1 is -CH2CH20H, -CH2CH20CH2CH2COOH,
an alkali salt thereof, or -CH2COOH or an alkali salt thereof.
"Tween":
~ 2 ~7)wH
(OCH2C~2) OH
C~2C~2 ) yOEI
CH2-(oc~2c~2)a~(Ac
wherein (a + w + x +y) is 4-20; and (Acyl) is an acyl group
cont~;n;ng 10-20 carbon atoms which is saturated or mono-
saturated.
"Igepal": Ethoxylated alkyl phenol having the general
formula
C9Hl9c6H4 (OCH2CH2) nOH
wherein n is 4-50.
"Brij": Polyethylene glycol ether of stearyl, oleyl,
cetyl, or lauryl alcohol, having the general formula
R-(ocH2cH2)noH
wherein n is 2-30 and R is the de-hydroxylated residue of the
alcohol.
"Myrj": Polyethylene glycol ester of stearic acid,
having the general formula
R-(ocH2cH2)noH
16 1 337320
wherein n is 2-60 and R is the stearoyl acyl radical.
The surfactant component can also comprise an
ampholytic detergent, which will normally be a betaine having an
aliphatic carbon chain bonded to nitrogen of from about 10-18
carbon atoms, preferably from about 10-14 carbon atoms.
The surfactant component is generally present in an
amount effective to aid in the removal of proteinaceous and/or
lipid materials (preferably both types of material) from the
contact lens surface. Amounts of about 0.1 to about 70 weight
percent, preferably about 1 to about 60 weight percent and more
preferably about 10 to about 50 weight percent, of the
composition are satisfactory.
Individual surfactants or combinations of surfactants
may be employed with the total concentration being in the
indicated range. The above description is meant to be
illustrative and not limiting; other examples of satisfactory
surfactants meeting the objective described herein will be
apparent to the skilled practitioner and are intended to be
within the scope of the present invention.
The composition of the present invention should also
contain a small amount of liquid, to aid in spreading the
composition onto the lens surface during the cleaning operation.
Amounts as low as about 3 weight percent of the composition, more
usually at least about 5 weight percent of the composition, can
be present. Water is the preferred liquid, but it should be
recognized that if the surfactant component is liquid (even a
viscous liquid) which can be spread onto the lens surface then
water is not necessary. The liquid can also comprise up to about
50 or even 75 weight percent of the composition. As noted
1 337320
17
herein, the amount of water and/or other liquid present will
depend on the amount of the abradant component present, as the
amount of liquid must be less than that which will completely
dissolve the abradant content of the composition. In other
words, there must be sufficient abradant component with respect
to the liquid content so that the composition is super-saturated
as to the abradant.
The compositions useful in the present invention can
range in consistency from a slurry having approximately the
consistency of water, to a cream or paste. To adjust the
viscosity to the desired thickness, the relative amounts of
liquid (e.g., water), surfactant and abradant component can be
adjusted accordingly. Alternatively, the composition can also
contain one or more additives in an amount effective to adjust
the viscosity so that it can be applied smoothly to the lens and
will remain in contact with the lens during the rubbing operation
rather than simply running off like water. Satisfactory
thickeners for this purpose include such polymers as polyoxy-
ethylene, guar gum, methyl cellulose, methylhydroxypropylcellulose, polypropylhydroxyethyl cellulose, locust bean gum,
hydroxypropyl guar gum, hydroxyethyl cellulose, hydroxypropyl
cellulose and starch derivatives such as hydroxyethylamylose.
The amount of the thickener will generally be in the range of
about 0.1 to about 20 weight percent, depending on the desired
consistency of the final product in accordance with the
objectives described herein.
Ophthalmologically acceptable buffers, while not
essential in this composition if borax is the abradant component,
can be added to achieve the desired pH which is generally in the
range of 5-10, preferably from about 7-10. Illustrative buffers
include borate, phosphate, citrate, carbonate and lactate,
18 l 337320
although other physiologically acceptable buffers may be
employed. The buffer concentration will generally be from about
o.os to 0.5 weight percent, normally being about 0.1 weight
percent.
The compositions useful in the present invention can
readily be prepared by mixing the indicated ingredients with
agitation. The additives can be added incrementally, preferably
while maintaining an excess of the abradant component to avoid
the undesired dissolution of that component. In best practice
the composition after preparation is then sterilized, to ensure
that no contamination introduced during formulation results in
microbial growth in the composition. The composition after
preparation is filled into appropriate plastic bottles and
sterilized by gamma radiation of about 2.5 megarads.
It will be appreciated that the composition of this
invention can also be prepared aseptically by using ingredients
which have been sterilized prior to incorporation into the final
product and by formulating the ingredients under sterile
conditions.
Another aspect of the present invention is that the
composition can be sterilized by autoclaving it in a sealed
chamber, for instance, at a sterilizing temperature on the order
of 100-130C, at a pressure from atmospheric to about 20 psi, and
for about 10-60 minutes, without loss of the desired particle
size distribution or loss of the material to dissolution.
Specifically, the composition is continuously stirred while it
is being sterilized, while it is cooling back to ambient
temperature, and for at least about 5 hours after it returns to
ambient temperature. In addition, the composition is cooled from
sterilizing temperature to ambient temperature under controlled
19 1 337320
gradual cooling conditions which permit reprecipitation of a
large number of nuclei. For example, cooling the composition
steadily from 121C to 25C over a period not less than 30
minutes, while continuously stirring as described above, permits
retention of the desired small particle size distribution
described above. The conditions permit the composition to be
sterilized under autoclaving conditions without undergoing any
loss of the desired particle size characteristics of the
composition.
The present invention can be used by simply depositing
a small amount (0.1 - 3 ml) thereof onto the surface of the lens
to be cleaned, and then rubbing the lens between the fingers or
in the palm of a hand, for an effective time such as 10-30
seconds. The abradant component particles help dislodge lens
soilants from the lens surface through the rubbing action. The
lens is then rinsed thoroughly, preferably with a commercially
available saline solution. The rinsing step causes the abradant
component particles to dissolve rapidly, and washes the com-
position off the lens surface as noted herein, especially if therinsing solution contains an ophthalmologically acceptable
additive to increase the solubility of the abradant component,
such as potassium chloride or nucleophiles (borate and fluoride)
where boric acid (H3BO3) is the abradant component. Such
additives are more fully described in Kirk-Othmer, suPra. The
lens can be immediately reinserted into the eye, without fear
that undissolved particles will remain which will irritate or
damage the eye tissues.
Alternatively, the cleaning step described herein can
be performed at the end of the day, following which the lens is
placed in a suitable storage solution overnight. The user can
be very confident that any residual abradant particles will
_ .
1 337320
dissolve into the storage solution and will not cause discomfort
when the lens is reinserted into the eye the next day.
It is a further advantage that in the preferred
embodiments employing borax, the borate anion formed by
dissolution into the storage solution is completely compatible
with the other components of that solution. The use of borax
also means that one need not add a preservative to the
composition (although such an additive remains optional). In
addition, the borate anion formed by the borax helps maintain the
pH at an alkaline level in use on the lens surface, thereby
assisting in the removal of proteinaceous material from the lens.
The invention will be further illustrated in the
following examples:
21 1 337320
EXAMPLE 1
A composition suitable for cleaning hard and soft contact
5 lenses was prepared by thoroughly mixing together the following
components in the indicated amounts.
Amount
ComPonents (wt. ~)
Purified water 45.8
Steol 4N (28%)
(Sodium lauryl ether sulfate surfactant) 20.0
Organosilicone L-720
(Non-ionic surfactant, Union Carbide)1.0
*Cab-O-Sperse 143 ~ 10.0
(Colloidal fumed silica 17%)
Sodium chloride, USP 6.0
Boric acid impalpable NF 15.0
*Arlacel 165 2.2
20 (Glycerol and polyoxyethylene glycol stearate)
The resulting composition was a suspension, which when
shaken became an effective contact lens cleaner.
*Trade mark
22 1 33~320
EXAMPLE 2
A composition suitable for cleaning hard and soft contact
lenses was prepared by thoroughly mixing together the following
components in the indicated amounts.
Amount
ComPonents rwt. %)
Organosilicone L-720
(Non-ionic surfactant, Union Carbide) 1.0
MYRJ 52 tNon-ionic surfactant) 1.0
Steol 4N
(Sodium lauryl ether sulfate surfactant) 9.0
Hydroxylethyl cellulose (viscosity builder) 0.4
Borax impalpable NF (abradant) 33.0
Purified water 55.6
The resulting composition was a suspension, which when
shaken became an effective contact lens cleaner.
