Contact lens cleaning composition containing polyalklene oxide modified siloxanes

Compositions and methods are provided for cleaning and wetting of contact lenses, especially rigid, gas-permeable contact lenses. The compositions comprise low molecular weight polyalkylene oxide modified siloxanes, which are particularly effective in removing lipids from the surface of contact lenses.

BACKGROUND OF THE INVENTION 
The present invention is directed to filling the need for an improved 
product for removing lipid deposits from contact lenses, particularly RGP 
lenses, as well as providing compositions which improve the wettability 
and overall comfort of contact lenses. 
The removal of deposits of proteins and other materials from the surfaces 
of contact lenses has been the subject of extensive research in the 
contact lens care industry since large scale introduction of contact 
lenses in the 1960's. Much of the research has focused on the removal of 
protein deposits from contact lenses. There are today a number of cleaning 
products on the market which remove protein deposits on contact lenses. 
Enzyme-containing cleaners are especially effective in this regard. 
Although other types of soilants on contact lenses have received somewhat 
less attention than proteins, such deposits can also be quite troublesome 
to the wearers of contact lenses. This is particularly true of lipid 
deposits which have become increasingly recognized as a significant 
problem for wearers of contact lenses, especially the lenses classified as 
"rigid gas-permeable" or "RGP" lenses. See, e.g., S.W. Huth and H.G. 
Wagner, "Identification and Removal of Deposits on Polydimethylsiloxane 
Silicone Elastomer Lenses", International Contact Lens Clinic, 8 
(July-August), 19-27, 1981; D.E. Hart, "Contact Lens/Tear Film 
Interactions: Depositions and Coatings," In O.H. Dabezies, Jr. (Chief 
Editor), Contact Lenses (The CLAO Guide to Basic Science and Clinical 
Practice), Second Edition, Volume 2, Little, Brown and Company, Boston, 
1988, pp. 45.A-1-45.A-27; R.C. Tripathi and B.J. Tripathi, "Lens 
Spoilage." In O.H. Dabezies, Jr. (Chief Editor), Contact Lenses (The CLAO 
Guide to Basic Science and Clinical Practice), Second Edition, Volume 2, 
Little, Brown and Company, Boston, 1988, pp. 45.1-45.33; R.M. Grohe, 
"Special Clinical Considerations." In E.S. Bennett and R.M. Grohe 
(Editors), Rigid Gas-Permeable Contact Lenses, Professional Press 
Books/Fairchild Publications, New York, 1986. pp. 151-174. 
The use of polymeric surfactants in contact lens care products has been 
described in numerous publications. Reference is made to the following 
publications for further background concerning such usage: 
U.S. Pat. No. 3,171,752 (Rankin), issued Mar. 2, 1965; 
U.S. Pat. No. 3,767,788 (Rankin), issued Oct. 23, 1973; 
U.S. Pat. No. 4,048,122 (Sibley, et al.), issued Sep. 13, 1977; 
U.S. Pat. No. 4,493,783 (Su, et at.), issued Jan. 15, 1985; and 
U.S. Pat. No. 4,808,239 (Schafer, et al.), issued Feb. 28, 1989. 
In addition, various types of contact lens care products containing 
surfactants have been marketed in the United States and other countries. 
Those skilled in the art of contact lens care products will be generally 
familiar with such products, which include Lobob Daily Cleaner, Lobob 
Laboratories, San Jose, CA; LC-65, Allergan, Irvine, CA; Titan II, 
Barnes-Hind Pharmaceuticals, Inc., Sunnyvale, CA; and Opti-Clean.RTM., 
Alcon Laboratories, Inc., Fort Worth, TX, for example. The above-cited 
patent issued to Sibley, et al. is believed to relate to the Titan II 
product, which has been marketed by Barnes-Hind. The patent issued to Su, 
et al., relates to the Opti-Clean.RTM. product. 
Notwithstanding such surfactant containing products, there remains a need 
for improved products capable of achieving even greater cleaning of 
contact lenses. In view of the significant worldwide market for rigid 
gas-permeable (RGP) lenses, there is a particular need for products which 
are more effective in cleaning these lenses. RGP lenses are generally less 
susceptible to formation of protein deposits than are soft (hydrogel) 
contact lenses, especially those categorized as ionic, high-water-content 
lenses. However, RGP lenses are susceptible to formation of lipid 
deposits. Therefore, the removal of lipid deposits is today a principal 
focus of research in the area of cleaning products for RGP lenses. The 
need for a product which effectively removes lipid deposits from these 
lenses was a principal impetus for the present invention. 
A further motivation for the present invention was the need for a product 
which is generally effective in removing lipid deposits from all types of 
contact lenses, as well as enhancing the wettability of contact lenses. 
While other factors also contribute to lens-wear comfort, the wettability 
of a contact lens (i.e., the ability of the lens to become wetted with 
tear fluid which normally hydrates and lubricates the cornea upon blinking 
of the eye) is a critical factor with respect to the comfort of the lens 
when placed on the cornea. It is therefore highly desirable to treat the 
surface of contact lenses with a composition that enhances the wettability 
of the lenses while being worn. This is particularly true with RGP lenses 
and other types of lenses having a lower water content than soft, hydrogel 
type lenses. 
SUMMARY OF THE INVENTION 
The present invention is based on the discovery that certain compounds 
within the class of surfactants known as "hydrophilic silicones" (which 
includes compounds referred to as polyalkylene oxide modified siloxanes, 
polyalkyleneoxide modified polydimethylsiloxanes, 
dimethylsiloxane-alkylene oxide copolymers, and silicone polyalkyleneoxide 
copolymers) are extremely effective in cleaning and wetting contact 
lenses. This class of surfactants is known. Reference is made to the 
following publications for further information concerning these 
surfactants: U.S. Pat. Nos. 3,299,112, 4,025,456, and 4,071,483. See, 
generally, S.C. Vick, "Structure/Property Relationships for Silicone 
Polyalkyleneoxide Copolymers and Their Effects on Performance in 
Cosmetics," Soap/Cosmetics/Chemical Specialties, 36ff, May, 1984; and 
G.L.F. Schmidt, "Specific Properties of Silicone Surfactants", In D.R. 
Karsa (Editor), Industrial Applications of Surfactants, Special 
Publication No. 59, The Royal Society of Chemistry, Burlington House, 
London, 1987, pages 24-32. 
Surprisingly, it has been discovered that certain low molecular weight 
polyalkylene oxide modified siloxanes possess superior cleaning activity. 
The low molecular weight, polyalkylene oxide modified siloxanes of the 
present invention include a sufficiently high weight percent of the 
non-siloxane portion to achieve solubility in water. While the precise 
mechanism of the cleaning action is not fully understood, these 
surfactants are believed to remove lipid deposits and other materials from 
the surfaces of contact lenses by what may be generally described as 
surface-active displacement of the deposits by the polymeric surfactant. 
The compositions and methods of the present invention are considered to 
have unexpected and significant advantages over prior compositions and 
methods for cleaning and wetting contact lenses. The superiority of the 
present compositions in performing both of these functions is a chief 
advantage. Moreover, the superior cleaning ability of the compositions has 
practical significance. Many lens wearers are not appropriately diligent 
or compliant in implementing cleaning procedures recommended by lens care 
product manufacturers or ophthalmic practitioners. In such instances, the 
superior cleaning efficacy of the surfactant compositions of the present 
invention can compensate for less than optimal compliance, providing the 
lens wearer with a cleaner, more comfortable lens than otherwise would 
have been obtained. 
The present invention entails compositions containing the above-described 
surfactants, as well as methods of treating contact lenses with these 
surfactants. The compositions of the present invention may take various 
forms, depending on the intended uses of the compositions. Generally, the 
compositions of the present invention will find utility in previously 
known types of compositions for treating contact lenses which include one 
or more surfactants to facilitate cleaning or wetting of the lenses. The 
compositions will typically be aqueous solutions containing one or more 
polyalkylene oxide modified siloxanes in an amount sufficient to clean and 
wet the contact lenses being treated.

DETAILED DESCRIPTION OF THE INVENTION 
The polyalkylene oxide modified siloxanes utilized in the present invention 
have an average molecular weight of less than 700 daltons. Preferred 
compounds have a molecular weight of approximately 550 to 650 daltons and 
a non-siloxane weight percent of approximately 65% to 80%. Most preferred 
is a compound known as PS071, which is commercially available from Huls 
America, Inc., Piscataway, New Jersey. Product Number PS071 is described 
in the monograph "Silicon Compounds: Register and Review," 5th edition, R. 
Anderson, G.L. Larson and C. Smith, Editors, Huls America, Inc., 
Piscataway, New Jersey, 1991, page 276. PS071 is characterized by the 
following properties: 
viscosity 20 cSt; refractive index 1.4416, specific gravity 1.007, melting 
point 
0.degree. C., surface tension 23.6 dynes/cm. 
The preferred polyalkylene oxide modified siloxanes have the following 
formula: 
##STR1## 
wherein m has a value from 2 to 4 inclusive, n has an average value from 
about 6 to 10 inclusive, and R is an alkyl group containing from 1 to 4 
carbon atoms, such that the weight percent of the non-siloxane component 
(i.e., (C.sub.m H.sub.2m (OC.sub.2 H.sub.4).sub.n OR) is approximately 75% 
of the total average molecular weight and such average molecular weight is 
approximately 600 daltons. 
The most preferred compound, PS071, is represented by the structural 
formula above, wherein m=3, n=approximately 8-10 and R is a methyl group. 
Compounds with comparable molecular constitution and physicochemical 
properties include a surfactant known as Silwet L77, which is commercially 
available from Union Carbide Corporation, Danbury, Connecticut, and 
described in the product information brochure "Silwet Surface Active 
Copolymers," Union Carbide Corporation, 1985, and related product 
information sheets (Union Carbide Corporation, 1987). 
The amount of polyalkylene oxide modified siloxane utilized will depend on 
various factors, such as the type of composition in which the copolymer is 
contained and the function of the composition. For example, compositions 
designed for out-of-the-eye cleaning of contact lenses by means of soaking 
the lenses in the composition will typically contain a higher 
concentration of copolymer than a composition designed for wetting of 
contact lenses by means of instilling a small amount of the composition 
directly on the lenses while in the eye. The concentration of copolymer 
may also depend on other factors, such as the type of contact lenses being 
treated (e.g., "hard" or "soft") and the presence of other ingredients in 
the formulation. Those skilled in the art will appreciate that the amount 
of copolymer utilized will depend on these and possibly other factors. For 
purposes of the present specification, the amounts required to clean or 
wet are functionally referred to as, "an effective amount". Such amounts 
will typically be in the range of about 0.0001 percent by weight (wt. %) 
to about 0.5 wt. % for wetting compositions, and about 0.01 wt. % to about 
1.0 wt. % for cleaning compositions. 
The compositions of the present invention may contain one or more of the 
above-described surfactants. The compositions may take various forms. For 
example, the compositions may be formulated as aqueous solutions, or solid 
or semi-solid preparations, such as tablets or gels. The surfactants 
utilized in the present invention may also be utilized in combination with 
other components for cleaning contact lenses, such as other siloxane or 
nonsiloxane surfactants, enzymes or deposit-shearing particles (e.g., 
microscopic beads formed from organic polymers). 
The combined use of the above-described surfactants and one or more 
antimicrobial agents to clean and disinfect contact lenses by means of 
treatment with a single composition is another embodiment of the invention 
of particular interest. In this embodiment, the cleaning and disinfecting 
functions are combined into a single product: this simplifies the lens 
care regimen for contact lens wearers and generally makes the regimen more 
convenient. Examples of antimicrobial agents which may be combined with 
the above-described surfactants for this purpose include Polyquad.RTM. 
germicide (described below), benzalkonium chloride, chlorhexidine, 
polyaminopropyl biguanide and sorbic acid. 
The lens cleaning compositions of this invention may also include 
conventional formulation ingredients, such as preservatives, viscosity 
enhancing agents, tonicity agents, and buffers. A polymeric quaternary 
ammonium germicide known as "POLYQUAD".RTM. is a preferred preservative. 
The use of this germicide in contact lens care products is described in 
U.S. Pat. Nos. 4,407,791 and 4,525,346. Sorbic acid, which is also 
frequently utilized in contact lens care products, represents another 
preferred preservative. However, preservation of product can be achieved 
without the use of a conventional preservative. Such products may contain 
anionic, cationic and amphoteric surfactants in combination with 
polyalkylene oxide modified siloxanes. Solvents like propylene glycol or 
isopropyl alcohol, when added in sufficient amounts, can also eliminate 
the need for a conventional preservative. Viscosity enhancing agents which 
may be employed in the present invention include, for example, 
hydroxypropyl methylcellulose (HPMC) and dextrans. The tonicity agents, if 
employed, will typically comprise sodium chloride, potassium chloride, or 
a mixture thereof. The buffering agents may comprise, for example, boric 
acid, citric acid, phosphoric acid and pharmaceutically acceptable salts 
thereof with pharmacologically acceptable cations. The pH of the 
compositions may be adjusted using sodium hydroxide and hydrochloric acid; 
the present compositions preferably have a pH in the range of about 6.5 to 
about 7.8, and a tonicity in the range of about 200 mOsm/Kg to about 400 
mOsm/Kg. The selection of particular formulation ingredients and the 
inclusion of these ingredients in the present compositions are well within 
the abilities of a person skilled in the art of contact lens care 
products. Thus, embodiments of the present invention may function as "all 
purpose solutions" for contact lens care, capable of simultaneously 
cleaning, wetting, disinfecting and conditioning the lens either out of 
the eye or while being worn. 
The present invention also provides methods of cleaning and wetting contact 
lenses. The methods comprise contacting the lenses with the compositions 
for a time sufficient to achieve the desired objective, namely cleaning 
and/or wetting of the lenses. Various methods of contacting the lenses 
with the compositions may be utilized, depending on the type of 
composition utilized and the purpose of the treatment. For example, soiled 
lenses can be soaked in an aqueous solution containing one or more of the 
present compositions at room temperature in order to clean the lenses. If 
the lenses are excessively soiled or if it is desired to accelerate 
cleaning, heat or agitation (e.g., shaking or ultrasonic energy) can be 
applied to the vessel containing the solution. The lenses can also be 
cleaned by means of rubbing a small amount of a composition over the 
surfaces of the lenses. Such cleaning of the lenses also results in 
wetting of the lenses. Lenses can be wetted by soaking in a small volume 
of the composition for four to eight hours, for example. In addition, the 
lenses can be wetted by simply placing a small amount (e.g., one or two 
drops) of a composition directly on the lenses and placing the lenses on 
the eye. The instillation of a small amount of a composition on the lenses 
while being worn on the eye is also contemplated as a part of the present 
invention. Such instillation would effect both a cleansing and wetting of 
the lens in the eye. 
The following examples are presented to further illustrate the present 
invention, but should not be interpreted as limiting the scope of the 
invention in any way. 
Example 1 
RGP Daily Cleaner (Suspension Type) 
______________________________________ 
Component % w/v 
______________________________________ 
Nylon 11 2.50 
Dextran 70 6.9 
Sodium Borate 0.25 
Boric Acid 0.50 
Miranol 2MCA Modified 0.50 
Surfactant PS071 0.15 
Propylene Glycol 10.0 
Polyquad .RTM. 0.005 
Disodium Edetate 0.10 
Mannitol 1.20 
Sodium Hydroxide/Hydrochloric Acid 
adjust pH 
Purified Water qs 
______________________________________ 
Procedure 
Prepare and sterilize the following filtration assemblies: 
(i) 0.22 .mu.m hydrophilic type sterilizing grade filter and receiving 
vessel; 
(ii) 0.22 .mu.m nylon sterilizing grade filter and receiving vessel. 
Sterilize sufficient purified water, sodium hydroxide and hydrochloric acid 
for use in the following procedure. 
Add approximately 40% of the final volume of purified water to a calibrated 
autoclavable processing vessel equipped with a stir bar, hydrophobic vent 
and dip tube with outlet for packaging. Dissolve the Dextran 70 in the 
purified water with mixing. Add the Miranol 2MCA Modified and allow to 
disperse. Disperse the Nylon 11 with mixing. Sterilize this composition by 
heating to 121.degree. C. and holding this temperature for 30 minutes. 
Cool to room temperature (Composition A). 
To another vessel equipped with a stir bar add approximately 20% of the 
final volume of purified water. Dissolve the boric acid and mannitol in 
the latter with mixing and continue mixing for an additional 30 minutes. 
Dissolve the sodium borate and disodium edetate with mixing and then add 
the Polyquad.RTM. with mixing. Pass this solution through a 0.22 .mu.m 
pre-sterilized hydrophilic-type filtration assembly into a sterile 
receiver (Composition B). 
Add the propylene glycol to a vessel equipped with a stir bar, and disperse 
the PS07 1 surfactant in the latter with mixing (15 minutes). Pass this 
mixture through a 0.22 .mu.m pre-sterilized nylon filtration assembly into 
a sterile receiver (Composition C). 
Aseptically add Composition B and Composition C to Composition A, assuring 
complete addition by rinsing with sterile purified water, and mix 
thoroughly. Aseptically adjust the pH of the mixture with sterile purified 
water and mix for a minimum of 15 minutes to yield the above-specified RGP 
Daily Cleaner. 
Example 2 
Demonstration of Cleaning Efficacy of 
RGP Daily Cleaner (Example 1) 
RGP lenses were deposited with an artificial meibum (lipid mixture). The 
soiled lenses were placed in the baskets of a Kestral lens case along with 
5 ml of the RGP Daily Cleaner and allowed to soak for various periods of 
time (e.g., 2 hours, 4 hours, 6 hours). The percent of deposit remaining 
at the end of each soak period was determined by image analysis 
technology: 
______________________________________ 
Soak Time Hours 
% Deposit Remaining 
______________________________________ 
0 100 
2 3 
4 0 
6 0 
______________________________________ 
Example 3 
RGP Daily Cleaner (Suspension Type) 
______________________________________ 
Component % w/v 
______________________________________ 
Nylon 11 10.0 
Sodium Phosphate 0.67 
Sodium Biphosphate 0.17 
Sodium Chloride 0.52 
Surfactant PS071 0.10 
Tyloxapol 0.10 
Hydroxypropyl Methylcellulose 
0.60 
Polyquad .RTM. 0.001 
Disodium Edetate 0.10 
Sodium Hydroxide/Hydrochloric Acid 
adjust pH 
Purified Water qs 
______________________________________ 
Procedure 
The composition may be prepared in a manner similar to the procedure of 
Example 1. 
Example 4 
RGP Daily Cleaner (Solution Type) 
______________________________________ 
Component % w/v 
______________________________________ 
Surfactant PS071 0.1 
Tyloxapol 0.1 
Sodium Phosphate 0.67 
Sodium Biphosphate 0.17 
Sodium Chloride 0.52 
Hydroxypropyl Methylcellulose 
0.30 
Disodium Edetate 0.10 
Polyquad .RTM. 0.001 
Sodium Hydroxide/Hydrochloric Acid 
adjust pH 
Purified Water qs 
______________________________________ 
Procedure 
In a labeled, calibrated container with about 90% of the purified water, 
add and dissolve the following with continuous stirring: 
Disodium Edetate 
Sodium Phosphate 
Sodium Biphosphate 
Sodium Chloride 
Tyloxapol 
Surfactant PS071 
Hydroxypropyl Methylcellulose 
Polyquad.RTM. 
Adjust the pH of the composition to pH 7.0 and add purified water to 
volume. Sterilize a receiving container connected to a 0.22 .mu.m filter 
assembly. Sterile filter the composition and fill the container. 
Example 5 
RGP Daily Cleaner (Suspension Type) 
______________________________________ 
Component % w/v 
______________________________________ 
Nylon 11 2.50 
Sodium Borate 0.25 
Boric Acid 0.50 
Miranol 2MCA Modified 0.50 
Surfactant PS071 0.15 
Propylene Glycol 15.00 
Disodium Edetate 0.10 
Mannitol 1.20 
Sodium Hydroxide/Hydrochloric Acid 
Adjust pH 
Purified Water qs 
______________________________________ 
Procedure 
The composition is prepared in a manner similar to the procedure of Example 
1. 
Example 6 
RGP Wetting/Soaking Solution 
______________________________________ 
Component % w/v 
______________________________________ 
Polyvinyl Alcohol 78,000/88% 
0.75 
Hydroxyethylcellulose 15,000 
0.38 
Boric Acid 0.35 
Sodium Borate 0.11 
Mannitol 2.0 
Disodium Edetate 0.1 
Potassium Chloride 0.038 
Magnesium Chloride 0.02 
Calcium Chloride 0.0154 
Sodium Chloride 0.09 
Dextrose 0.092 
Surfactant PS071 0.05 
Pluronic P103 0.05 
Polyquad .RTM. 0.001 
Sodium Hydroxide/Hydrochloric Acid 
adjust pH 
Purified Water qs 
______________________________________ 
Procedure 
Sterilize a filtration assembly connected to a receiving vessel. In a 
calibrated, labeled aspirator with about 40% of the required purified 
water, add and disperse the PS071 surfactant, the Pluronic P103 and the 
polyvinyl alcohol. If required, heat to 80.degree. C. to disperse the 
polyvinyl alcohol. 
Add and disperse the hydroxyethylcellulose. Connect a filtration assembly 
and autoclave for 30 minutes at 121.degree. C. 
In another container with about 30% of the required purified water, add and 
dissolve the sodium borate. Add the mannitol and stir for at least 15 
minutes and then add the boric acid and stir for at least 30 minutes. 
Finally, add and dissolve the following with continuous stirring: 
Disodium Edetate 
Potassium Chloride 
Magnesium Chloride 
Calcium Chloride 
Sodium Chloride 
Dextrose 
Polyquad.RTM. 
Ascertain the pH of the salt solution and adjust the pH to 6.5. 
Sterile filter the salt solution into the solution containing the PS071 
surfactant/Pluronic P 103/hydroxyethylcellulose/polyvinyl alcohol. 
Adjust the pH to 7.4 and add sufficient purified water to volume. 
Example 7 
RGP Wetting/Soaking Solution 
______________________________________ 
Component % w/v 
______________________________________ 
Polyvinyl Alcohol 78,000/88% 
0.75 
Hydroxyethylcellulose 15,000 
0.38 
Potassium Chloride 0.038 
Magnesium Chloride 0.02 
Calcium Chloride 0.0154 
Sodium Chloride 0.714 
Sodium Phosphate 0.008 
Dextrose 0.092 
Surfactant PS071 0.01 
Pluronic F127 0.01 
Disodium Edetate 0.10 
Polyquad .RTM. 0.001 
Sodium Hydroxide/Hydrochloric Acid 
adjust pH 
Purified Water qs 
______________________________________ 
Procedure 
Sterilize a filtration assembly connected to a receiving vessel. 
In a calibrated, labeled aspirator with about 40% of the required purified 
water, add and disperse the PS071 surfactant, the Pluronic F127 and the 
polyvinyl alcohol. If required, heat to 80.degree. C. to disperse the 
polyvinyl alcohol. 
Add and disperse the hydroxyethylcellulose. Connect a filtration assembly 
and autoclave for 30 minutes at 121.degree. C. 
In another container with about 30% of the required purified water, add and 
dissolve the following with continuous stirring: 
Disodium Edetate 
Potassium Chloride 
Magnesium Chloride 
Calcium Chloride 
Sodium Chloride 
Sodium Phosphate 
Dextrose 
Polyquad.RTM. 
Ascertain the pH of the salt solution and adjust the pH to 6.5. 
Sterile filter the salt solution into the solution containing the PS071 
surfactant/Pluronic P103/hydroxyethylcellulose/polyvinyl alcohol. 
Adjust the pH to 7.0 and add sufficient purified water to volume.