Method and composition for rewetting and preventing deposits on contact lens

The present invention is directed to an ophthalmic solution for the treatment of contact lenses while worn in the eye. In particular, the composition contains ethoxylated glucose derivative, tyloxapol, and a polyoxyethylene-polyoxypropylene nonionic surfactant. The ophthalmic solution containing such a combination of components can be applied, in the form of drops, to the eye or to contact lens in the eye. In one embodiment of the invention, the composition is used for reducing unwanted lipid or protein deposition on extended-wear lenses, including lenses made from relatively hydrophobic materials such as silicon hydrogels.

FIELD OF THE INVENTION 
This invention relates to a composition and method for rewetting and 
preventing deposits on contact lenses. In particular, the composition is 
an ophthalmic solution comprising the combination of tyloxapol, an 
ethoxylated glucose, and a non-ionic surfactant comprising a 
polyoxyethylene-polyoxypropylene block polymer or adduct thereof. The 
composition inhibits the deposition of lipids and the like on contact 
lenses. 
BACKGROUND OF THE INVENTION 
Contact lenses in wide use today fall into two categories. First, there are 
the hard or rigid corneal type lenses that are formed from materials 
prepared by the polymerization of acrylic esters, such as 
polymethylmethacrylate (PMMA). Secondly, there are the gel, hydrogel or 
soft type of lenses made by polymerizing such monomers as 2-hydroxyethyl 
methacrylate (HEMA) or, in the case of extended wear lenses, made by 
polymerizing silicon-containing monomers or macromonomers. Solutions that 
wet the lenses before insertion in the eye are required for both the hard 
and soft types of contact lenses, although their formulations have tended 
to differ based on their different properties. After the contact lenses 
are inserted in the eye, ophthalmic solutions for rewetting, lubricating, 
and/or enhancing wearer comfort are sometimes applied to the eye by means 
of a drop dispenser. 
Isotonic solutions for improving the comfort of wearing soft contact lenses 
by being added directly to the contact lens in the eye are known. Such 
solutions typically contain viscosity enhancing agents, lubricants, 
surfactants, buffers, preservatives, and salts. For example, U.S. Pat. No. 
4,529,535 to Sherman discloses a rewetting solution that is particularly 
useful for rigid silicone copolymer contact lenses, including extended 
wear lenses. In one embodiment, the rewetting solution contains the 
combination of hydroxyethylcellulose, polyvinyl alcohol, and 
polyvinylpyrrolidone. 
U.S. Pat. No. 4,786,436 to Ogunbiyi, et al. discloses a wetting solution 
comprising collagen and other demulcents such as hydroxylethyl cellulose, 
methyl cellulose, carboxymethyl cellulose, hydroxypropyl methylcellulose, 
hydroxylpropyl-cellulose and the like. 
U.S. Pat. No. 4,748,189 to Su et al. discloses ophthalmic solutions for 
improving the exchange of fluid in the area outside a hydrogel contact 
lens in the area underneath the hydrogel contact lens, in order to permit 
tear exchange to occur, thereby preventing the accumulation of waste 
matter and debris under the lens. The solution contains a hydrogel 
flattening agent, for example urea, glycerin, propylene glycol, sorbitol, 
or an amino-ethanol. Surfactants that are useful in the solution include 
poloxamer and tyloxapol. Suitable lubricants include 
hydroxylethylcellulose, polyvinylalchol, and polyvinylpyrrolidone. 
U.S. Pat. No. 5,209,865 to Winterton et al. discloses a conditioning 
solution for contact lenses that comprises a combination of a poloxamine 
and a poloxamer surfactant each having an HLB (hydrophilic-lipophilic 
balance) of seven or below. The solution according to the invention forms 
a uniform hydrophilic film on a lens surface for which proteins have very 
little affinity. As such, a contact lens contacted by the solution is said 
to have a coating that provides a prophylactic effect to the lens. 
U.S. Pat. No. 5,604,189 and U.S. Pat. No. 5,773,396 to Zhang et al. 
disclose a composition for cleaning and wetting contact lenses comprising 
(i) a non-amine polyethyleneoxy-containing compound having an HLB of at 
least about 18, (ii) a surface active agent having cleaning activity for 
contact lens deposits that may have an HLB less than 18, and (iii) a 
wetting agent. Such compositions can include, as the wetting agent, an 
ethoxylated glucose derivative such as glucam, also disclosed in U.S. Pat. 
No. 5,401,327 to Ellis et al. Tyloxapol is a conventional surface active 
agent, used for example in Allergan's Complete.RTM. multipurpose solution, 
which agent has cleaning activity for contact-lens deposits and has an HLB 
less than 18. 
Unlike hard lenses, the soft type of contact lenses have a tendency to bind 
and concentrate significantly more fluids, environmental pollutants, water 
impurities. Likewise, the soft type of contact lenses is more susceptible 
to the deposition of protein or lipids or both. Thus, the use of enzymes 
or equivalent protein-removing agents has been conventionally employed for 
weekly or daily protein removal from worn lenses. In contrast, surfactant 
cleaning agents in daily lens care solutions are useful for the removal of 
lipid or lipid-like materials from the lenses. With the advent of extended 
wear lenses, however, in which lenses are worn overnight and even 
continuously over a plurality of whole days, night and day, the lens 
wearers no longer have the opportunity to remove, by means of the 
conventional lens care solutions, the depositions that have accumulated 
over the day. 
It would, therefore, be desirable to have a solution that could be applied 
to the eye that not only rewets the lens but also cleans and/or prevents 
the deposition of lipids until such time as the lens is removed from the 
eye and cleaned or disposed. However, it does not necessarily follow that 
cleaning agents that can be used in cleaning solutions in which contact 
lenses are immersed for several hours or more would be effective when 
applied in the form of eyedrops to a lens in the eye. In particular, 
cleaning agents that are designed to prevent the deposition of lipids on a 
lens must have an extended effect on a lens within the eye. At the same 
time, cleaning agents must be selected that are very safe and comfortable, 
especially as they would be expected to associate with the lens surfaces 
while in the eye. 
SUMMARY OF THE INVENTION 
The present invention is directed to a rewetting solution for contact 
lenses comprising an ethoxylated glucose derivative, tyloxapol, and a 
non-ionic surfactant comprising a polyoxyethylene-polyoxypropylene or 
adduct thereof. An ophthalmic solution containing such a combination of 
components can be applied in the form of drops to the contact lens while 
they are in the eye. Thus, a system useful to prevent the deposition of 
lipids as well as for rewetting or lubricating contact lenses while in the 
eye comprises an drop dispenser and a plastic container holding between 
about 1 and about 30 ml of an ophthalmic solution comprising: 
(a) an effective amount of ethoxylated glucose derivative, 
(b) an effective amount of tyloxapol, 
(c) an effective amount of a non-ionic surfactant comprising a 
polyoxyethylene-polyoxypropylene polymer or adduct thereof. 
Preferably, the non-ionic surfactant has a cloud point of at least 
50.degree. C., preferably above 90.degree. C., at a concentration of one 
percent. In one embodiment of the invention, the solution also comprises 
an effective amount of a polymeric demulcent. Preferably, the polymeric 
demulcent is a cellulosic polymer. 
Such a solution is especially advantageous for the treatment of soft lenses 
that are capable of use for extended wear. It is especially effective for 
use on silicone hydrogel lenses that potentially can be worn for seven 
days and even longer. Additional ingredients that may be included in a 
solution according to the present invention are a sequestering agent, 
which may be present in an amount of 0.01 to 2.0% by weight, and an 
effective amount of a buffering agent to maintain the pH between about 5.0 
and 8.0, preferably 5.5 to 7.5. 
The invention is also directed to a method of using the foregoing 
composition. The objects, features, and advantages of the various 
embodiments of the present invention will become more readily apparent 
from the following detailed description. 
DETAILED DESCRIPTION OF THE INVENTION 
The present invention is directed to an ophthalmic solution that is applied 
in the form of drops to a contact lens while it is worn in the eye and 
which is useful for rewetting or lubricating the lens as well as for 
prophylactically cleaning the lens by preventing the deposition of lipids 
or other depositions on the lens. 
As indicated above, while the present invention can be used in connection 
with a variety of soft lenses, it is especially useful with respect to 
hydrophilic lenses made from polymers having repeat units derived from 
hydrophilic monomers such as hydroxyethyl methacrylate, 
polyvinylpyrrolidone, dimethylacrylamide, methacrylic acid, or the like. 
These include hydrogels belonging to Groups I to IV (FDA categories). 
Group IV is distinguished from Groups I to III by having higher water 
content and is distinguished from Group I and II by being more ionic. 
Typically, Group IV lenses have a water content greater than 50% by 
weight. High water content is associated with materials having high oxygen 
permeability, resulting in the increasing popularity of Group IV lenses, 
especially disposable and frequent-replacement lenses. Such materials 
include, but are not limited to, bufilcon A, etafilcon A, methafilcon A, 
ocufilcon C, perfilcon A, phemfilcon A, and vifilcon A. Materials 
containing methacrylic acid monomers include methafilcon B, ocufilcon D, 
methafilcon A, and etafilcon A (USAN and the USAP Dictionary of Drug 
Names). Lenses made from the foregoing materials are commercially 
available from a variety of sources. Such lenses include daily-wear 
lenses, extended-wear lenses, planned-replacement lenses, and disposable 
lenses. 
The present invention can also be used in connection with soft lenses made 
from a silicone hydrogel material. Such lens materials, for example, are 
disclosed in U.S. Pat. No. 5,260,000 to Nandu, et al. (for example, see 
Formulation A). Such materials are known as balafilcon A. Lenses made from 
silicone hydrogel materials are more hydrophobic that other types of soft 
lenses and are, therefore, especially prone to lipid deposition. 
As indicated above, the lens-care ophthalmic solution of the invention for 
preventing lipid deposition on contact lenses requires the combination of 
an ethoxylated glucose derivative, tyloxapol, and a non-ionic surfactant 
that is a polyoxyethylene-polyoxypropylene block polymer or adduct 
thereof. It has been found that this combination of surfactants is not 
only effective in preventing the deposition of lipids, but is comfortable 
for use in the eye. Without wishing to be bound by theory, each of the 
three ingredients is believed to have a unique function in the 
combination; the non-ionic polyoxyethylene-polyoxypropylene surfactant is 
believed to function to some extent as a comfort agent, perhaps masking 
any potential irritation of the primary cleaner, as suggested in U.S. Pat. 
No. 5,604,189 to Zhang et al. The tyloxapol is believed to be the primary 
cleaning agent in the eye. The ethoxylated glucose derivative is believed 
to function as a wetting agent. As such, it may remain attached to the 
lens and assist in the spreading of the cleaner and the comfort agent on 
the lens. These separate functions, however, should not be viewed as 
clear-cut and exclusive. For example, the non-ionic 
polyoxyethylene-polyoxypropylene surfactant may have some cleaning effect, 
but not as much as the combination with the tyloxapol. Similarly, the 
surfactants are not as effective and not as durable in the absence of the 
wetting agent. Also, the attachment of one or more of the solution 
components to the lens in the eye is believed to reduce the hydrophobicity 
of the lens surface, especially in the case of a silicon hydrogel, which 
may reduce the affinity of lipids to the lens surface. The surfactants may 
not only prevent the deposition of lipids, but also to some extent may 
loosen deposits on the lens; wherein removal is assisted by the natural 
cleaning action of blinking. 
The non-ionic polyoxyethylene-polyoxypropylene surfactants employed in the 
present invention preferably have a cloud point of at least 50.degree. C. 
at a concentration of 1 percent and more preferably also has an HLB of at 
least 18. Such surfactants can be selected, for example, from the group of 
commercially available surfactants having the name poloxamine or 
poloxamer, as adopted by The CTFA International Cosmetic Ingredient 
Dictionary. Poloxamine surfactants consist of a 
poly(oxypropylene)-poly(oxyethylene) adduct of ethylene diamine having a 
molecular weight from about 7,500 to about 27,000 wherein at least 40 
weight percent of said adduct is poly(oxyethylene). Such surfactants are 
available from BASF Wyandotte Corp., Wyandotte, Mich., under the 
registered trademark "Tetronic". An analogous series of surfactants is the 
poloxamer series which is a polyoxyethylene, polyoxypropylene block 
polymer available from BASF Wyandotte Corp., Parsippany, N.J. 07054 under 
the trademark "Pluronic". 
The HLB of a surfactant is known to be a major factor in determining the 
emulsification characteristics of a nonionic surfactant. In general, 
surfactants with lower HLB values are more lipophilic, while surfactants 
with higher HLB values are more hydrophilic. The HLB values of various 
poloxamines and poloxamers are provided by BASF Wyandotte Corp., 
Wyandotte, Mich. 
Such surfactants are suitably employed in amounts from about 0.01 to about 
10 weight percent, preferably 0.1 to 5 weight percent of the solution. 
The ethoxylated glucose employed in the present solution preferably belongs 
to the class of compounds that are polyethylene glycol ethers of methyl 
glucose conforming generally to the formula: 
EQU CH.sub.3 --C.sub.6 H.sub.7 O.sub.2 --(OCH.sub.2 CH.sub.2).sub.n OH 
(available from Amerchol Corp., Edison, N.J., as Glucam.RTM. E-10) and 
methyl gluceth-20 (available from Amerchol Corp., Edison, N.J., as 
Glucam.RTM. E-20). Such compounds are suitably employed in amounts from 
about 0.01 to about 5 weight percent, preferably 0.1 to 2 weight percent 
of the solution. 
Tyloxapol is an oxyethylated tertiary octylphenol formaldehyde polymer. 
commercially available from a number of sources including Sanofi Winthrop, 
Inc. (NY, N.Y.) and Nycomed, Inc. (33 Riverside Drive, Rennselaer, N.Y. 
12144). It can be prepared as disclosed in U.S. Pat. No. 2,454,541 to Bock 
et al. It is a known surfactant, detergent, and surface-tension reducing 
agent that is soluble in water. It has been used as a cleaning agent in 
contact lens solutions, and the present invention is directed to the 
combination of components with advantageous properties rather than to the 
use of the individual components per se. 
Optionally, additional compatible surfactants that are known to be useful 
in contact lens wetting or rewetting solutions can be used in the 
solutions of this invention. The surfactant should be soluble in the lens 
care solution and non-irritating to eye tissues. Satisfactory non-ionic 
surfactants include polyethylene glycol esters of fatty acids, e.g. 
coconut, polysorbate, polyoxyethylene or polyoxypropylene ethers of higher 
alkanes (C.sub.12 -C.sub.18). Examples include polysorbate 20 (available 
from ICI Americas Inc., Wilmington, Del. 19897 under the trademark 
Tween.RTM. 20 and Tween.RTM. 80), polyoxyethylene (23) lauryl ether 
(Brij.RTM. 35), polyoxyethylene (40) stearate (Myrj.RTM. 52), 
polyoxyethylene (25) propylene glycol stearate (Atlas.RTM. G 2612). 
Brij.RTM. 35, Myrj.RTM. 52 and Atlas.RTM. G 2612 are trademarks of, and 
are commercially available from, ICI Americas Inc., Wilmington, Del. 
19897. 
Various other surfactants suitable for use in the invention can be readily 
ascertained, in view of the foregoing description, from McCutcheon's 
Detergents and Emulsifiers, North American Edition, McCutcheon Division, 
MC Publishing Co., Glen Rock, N.J. 07452 and the CTFA International 
Cosmetic Ingredient Handbook, Published by The Cosmetic, Toiletry, and 
Fragrance Association, Washington, D.C. 
In one embodiment of the invention, the solution also includes a non-ionic 
polymeric demulcent and viscosity builder. Such demulcents have a tendency 
to enhance the lens wearer's comfort by means of a film on the lens 
surface cushioning impact against the eye. Included among the 
water-soluble viscosity builders are the cellulosic polymers and 
derivatives thereof, for example, hydroxyethyl or hydroxypropyl 
methylcellulose, carboxymethyl cellulose, and cationic celluosic 
compounds, such as polyquaternium-10. Other polymeric demulcents include, 
for example, povidone, polyvinyl alcohol, and the like. Such viscosity 
builders may be employed in amounts ranging from about 0.01 to about 5.0 
weight percent or less. Suitably, the viscosity of the final formulation 
is between 1 cps and 50 cps, preferably at least 2 cps. Comfort agents 
such as glycerin, or propylene glycol can also be added. 
The preferred demulcent is hydroxypropyl methyl cellulose (HPMC). The HPMC 
used in the present invention suitably has a weight average molecular 
weight of about 5,000 to 1000,000,000. Such materials are sold by various 
companies, including--Dow Chemical (Midland, Mich.), for example 
Methocel.RTM. HPMC. In the present compositions, the HPMC is suitably 
present in an amount 0.01 to 10.0% by weight, preferably of between 0.05 
to 5.0 percent by weight. 
The present composition will contain a disinfecting amount of a 
preservative or an antimicrobial agent. A particularly preferred 
preservative is sorbic acid (0.15%). Antimicrobial agents are defined as 
organic chemicals that derive their antimicrobial activity through a 
chemical or physicochemical interaction with the microbial organisms. For 
example, biguanides include the free bases or salts of alexidine, 
chlorhexidine, hexamethylene biguanides and their polymers, and 
combinations of the foregoing. The salts of alexidine and chlorhexidine 
can be either organic or inorganic and are typically gluconates, nitrates, 
acetates, phosphates, sulphates, halides and the like. Preferred 
antimicrobial agents are the polymeric quaternary ammonium salts used in 
ophthalmic applications and the biguanides. More preferred are the 
biguanides and hexamethylene biguanides (commercially available from 
Zeneca, Wilmington, Del. under the trademark Cosmocil.TM. CQ), their 
polymers and water-soluble salts being most preferred. Generally, the 
hexamethylene biguanide polymers, also referred to as polyaminopropyl 
biguanide (PAPB), have molecular weights of up to about 100,000. Such 
compounds are known and are disclosed in U.S. Pat. No. 4,758,595 and 
British Patent 1,432,345, which patents are hereby incorporated herein by 
reference. The hydrochloride salt of polyhexamethylene biguanide is 
commercially available from Zeneca, Inc. under the trademark Cosmocil.RTM. 
CQ. This biguanide is often referred to as either "PHMB" or "PAPB," as 
herein, usually by the latter acronym corresponding to polyaminopropyl 
biguanide. Typically, biguanides are present in concentrations ranging 
from about 0.00001 to about 0.001% by weight. 
Aqueous solution according to the present invention can be prepared by a 
variety of techniques. One method includes the preparation of a 
HPMC-containing solution by initially heating about 80 percent of the 
distilled water to be used, to 80.degree. C. With agitation, the alkali 
metal chlorides, sequestering agents, buffering agents, surfactant, 
tyloxapol, and ethoxylated glucose are added. After the solution is cooled 
to room temperature, the sorbic acid is added, followed by the balance of 
distilled water. The solution can then be sterilized by forcing it through 
an 0.22 micron filter by means of a peristaltic pump, followed by 
packaging in sterilized plastic containers. 
In addition to the active ingredients described above, solutions according 
to the present invention may contain buffers, stabilizers, isotonic agents 
and the like which aid in making ophthalmic compositions more comfortable 
to the user. The aqueous solutions of the present invention are typically 
adjusted with tonicity agents to approximate the osmotic pressure of 
normal lachrymal fluids which is equivalent to a 0.9% solution of sodium 
chloride or 2.5% of glycerol solution. The solutions are made 
substantially isotonic with physiological saline used alone or in 
combination, otherwise if simply blended with sterile water and made 
hypotonic or made hypertonic the lenses will lose their desirable optical 
parameters. Correspondingly, excess salt or other tonicity agent may 
result in the formation of a hypertonic solution that will cause stinging 
and eye irritation. An osmolality of about 225 to 400 mOsm/kg is 
preferred, more preferably 280 to 320 mOsm/kg. 
The pH of the present solutions should be maintained within the range of 
5.0 to 8.0, more preferably about 6.0 to 8.0, most preferably about 6.5 to 
7.8. Suitable buffers may be added, such as boric acid, sodium borate, 
potassium citrate, citric acid, sodium bicarbonate, TRIS, and various 
mixed phosphate buffers (including combinations of Na.sub.2 HPO.sub.4, 
NaH.sub.2 PO.sub.4 and KH.sub.2 PO.sub.4) and mixtures thereof. Borate 
buffers are preferred, particularly for enhancing the efficacy of PAPB. 
Generally, buffers will be used in amounts ranging from about 0.05 to 2.5 
percent by weight, and preferably, from 0.1 to 1.5 percent. 
In addition to buffering agents, in some instances it may be desirable to 
include sequestering agents in the present solutions in order to bind 
metal ions that might otherwise react with the lens and/or protein 
deposits and collect on the lens. Ethylene-diaminetetraacetic acid (EDTA) 
and its salts (disodium) are preferred examples. They are usually added in 
amounts ranging from about 0.01 to about 0.2 weight percent. 
As indicated above, the present invention is useful for cleaning a contact 
lens while it is worn in the eye. Thus, as mentioned above, compositions 
of the present invention is especially advantageous with people who are 
prone to heavy lipid or like deposition or who wear lenses under an 
extended-wear regime. Extended wear is defined as a lens that is worn 
overnight, during sleep, preferably capable of wear for a week or more, 
even as long as one month. 
The compositions of the present invention are typically sold in a wide 
range of small volume containers from 1 to 30 ml in size, preferably 1 ml 
to 20 ml in size. Such containers can be made from HDPE (high density 
polyethylene), LDPE (low density polyethylene), polypropylene, 
poly(ethylene terepthalate) and the like. Flexible bottles having 
conventional drop dispensing tops are especially suitable for use with the 
present invention. 
Compositions according to the present invention may suitably be applied as 
follows. During wear, about one or two drops are placed directly onto each 
lens whenever needed. Thereafter, the wearer should blink several times. 
The following specific experiments and examples demonstrate the 
compositions and methods of the present invention. However, it is to be 
understood that these examples are for illustrative purposes only and do 
not purport to be wholly definitive as to conditions and scope. All 
percentages are by weight of the solution, unless indicated otherwise.

EXAMPLE 1 
An aqueous solution according to the present invention, useful as an 
eyedrop for contact lenses worn in the eye, can be prepared with the 
following ingredients in purified water: 
TABLE 1 
______________________________________ 
Ingredient gm % w/w 
______________________________________ 
Pluronic F127 poloxamer 
500.0 0.500 
Tyloxapol 100.0 0.100 
Glucam .RTM. E20 ethoxylated glucose 
100.0 0.100 
Sorbic Acid 165.0 0.165 
Boric Acid 677.0 0.677 
Sodium Borate 236.0 0.236 
Sodium Phosphate (Dibasic) 
310.0 0.310 
Sodium Chloride 155.0 0.155 
Potassium Chloride 107.0 0.107 
HPMC (E15-LV Premium) 
200.0 0.200 
Edetate Disodium 50.0 0.050 
Distilled Water Q.S. 100 kg 
Q.S. to 100% 
______________________________________ 
The formulation is prepared in bulk as follows. In a 316-grade stainless 
steel jacketed mixing vessel, hot purified water (75 to 85.degree. C.) is 
added in the amount of about 95-98% of final batch volume. Under agitation 
the HPMC is slowly added, and agitation continued for a minimum of 20 
minutes. The batch is then cooled to 20 to 25.degree. C. with continuous 
agitation and then mixed for a minimum of 30 minutes. With continued 
agitation, the poloxamer is slowly added and mixed for a minimum of 15 
minutes. Then the following batch quantities of the following ingredients 
are added in the order listed, wherein after one ingredient is dissolved 
or dispersed, the next is added: sodium chloride, potassium chloride, 
boric acid, sodium borate, EDTA, sodium phosphate, sorbic acid, tyloxapol, 
and glucam E-20 ethoxylated glucose. Agitation is maintained throughout 
the entire processing of the batch and the solution is mixed for a minimum 
of 60 minutes. Upon dissolution of these components, the batch is charged 
with purified water (at 20-35.degree. C.) to the final volume. The 
solution is mixed for a minimum of 20 minutes to ensure complete 
dissolution. If necessary, the pH is adjusted to 7.0-7.20 at 25.degree. C. 
with 2.5 N NaOH or 1N HCl. The osmolality is measured at 280-320 mOsm/Kg. 
The finished solution should be aseptically passed through a sterile 0.22 
.mu.m membrane filter. 
EXAMPLE 2 
This example illustrates the advantageous properties of a solution 
according to the present invention. In particular, 168 PureVision.RTM. 
contact lenses, made from balafilcon A silicone hydrogel material, were 
exposed to both a protein and lipid artificial deposition solution (ATS) 
in order to assess both the deposit inhibition of the formulation 
according to Example 1 ("Formulation A") compared to ReNu.RTM. Rewetting 
Drops which contains poloxamine, boric acid, sodium borate, sodium 
chloride, EDTA, and sorbic acid ("Comparative Formulation B") Comparative 
Formulation B consists of 0.35% sodium borate, 0.15% sorbic acid, 0.10% 
EDTA, 0.50% boric acid, 0.40% sodium chloride, and 0.10% poloxamine 
(Tetronic.RTM.) 1107. 
To test for deposit inhibition, lenses were preconditioned with the 
Formulation A by soaking the lens in the solution for one hour prior to 
deposition. After deposition and incubation, the lenses were then rinsed 
with ReNu.RTM. Saline (no sorbic acid) and analyzed for Protein and Lipid 
levels respectively. The testing was conducted as follows: 
A. Protocol for Testing Protein Deposit Inhibition: 
In the preparation of the standards, unworn Bausch & Lomb PureVision.RTM. 
lenses are taken out of their vials, left to air dry and then placed in 
glass test tubes along with standard BSA solution. An in vitro protein 
mixture consisting of lysozyme, lactoferrin, human serum albumin and mucin 
in MOPS buffer was used. The pH of the solution is adjusted to 7.2 using 
1N HCl and an osmolality equal to 326 mOsm. Seven Bausch & Lomb 
PureVision.RTM. lenses per test solution were preconditioned with the 
respective test formulations by soaking the lens in the formulation for 
one hour. The lenses were then removed from the formulation and placed in 
1.5 mls of the Protein Mix. The lenses were then incubated in the Protein 
mix at 37.degree. C. in a shaking water bath for 48 hours. Protein 
analysis was done using the colorimetric BCA analytical method (Sigma). 
The method employs the protein induced reduction of Cu(II) to Cu(I). A 
purple complex (Amax=562 nm) is formed following the addition of 
bicinchoninic acid (BCA) to the reduced copper. The intensity of the 
complex is shown to be directly proportional over the protein 
concentration range 5 .mu.g/ml to 2000 .mu.g/ml. Following incubation at 
37.degree. C., the rate of color development is slowed sufficiently to 
allow large numbers of samples to be done in a single run. The standard 
protein solution utilized was BSA with a standard concentration range of 0 
to 50 .mu.g. To each test tube was added 2 mls of a mixture of 
bicinchoninic acid (BCA) and Cu(II) Sulfate and vortexed. Tubes were then 
covered and placed in a water bath at 37.degree. C. for 15 minutes. After 
incubation, the purple complex develops. Samples and standards are read at 
562 nm in a Perkin Elmer Spectrophotometer. Protein concentration is 
determined from a standard plot of absorbency vs. concentration (.mu.g). 
Protein results reported represent total amount of bound protein. 
B. Protocol for Testing Lipid Deposit Inhibition: 
Seven Bausch & Lomb PureVision.RTM. lenses per test solution were 
preconditioned with the respective test formulations by soaking the lens 
in the formulation for one hour. The lenses were then removed from the 
formulation, and placed in 1.5 mls of a Lipid Mix. The Lipid Mix was a 
mixture of palmitic acid methyl ester (PAME), cholesterol, squalene and 
mucin in MOPS buffer. Mucin is utilized as a surfactant to aid in the 
solubilization of the lipids. Lenses were then incubated in the Lipid Mix 
at 37.degree. in a shaking water bath for 24 hours. After incubation, the 
lenses were then removed from the test solution and rinsed with ReNu.RTM. 
Saline (no sorbic acid) to remove any residual deposition solution. Lenses 
were then placed in glass vials for extraction. A three hour 1:1 
CHCl.sub.3 /MeOH extraction was subsequently followed by a three hour 
Hexane extraction. Extracts were then combined and run on a Hewlett 
Packard GC. The column utilized was an HP-Ultra 1 with an FID detector and 
He as the carrier gas. Standard solutions of each of the lipids in the 
deposition mix were made in 1:1 CHCl.sub.3 /MeOH and the concentration of 
lipid extracted from the lenses was determined. 
C. The Results: 
The Percent Deposit Inhibition for protein and lipid, respectively, was 
calculated by the following equation: 
##EQU1## 
where the control lens is Bausch & Lomb PureVision.RTM. balafilcon A lens 
deposited with the protein and lipid solution respectively. 
The protein and lipid deposition values for the Bausch & Lomb 
PureVision.RTM. control lenses (7.75 .mu.g and 381 .mu.g) respectively, 
provided a baseline with which to assess the potential cleaning efficacy 
and deposit inhibition attributes of each of the formulations tested. 
Table 2 below represents the protein raw data and deposit inhibition 
results relative to the control deposited lenses. Table 2A below 
represents the lipid raw data and deposit inhibition results relative to 
the control deposited lens. 
TABLE 2 
______________________________________ 
Protein Deposit Inhibition and Cleaning Efficacy Data 
Average Protein 
Deposition - 
Bausch & Lomb 
Average Protein 
% Total Protein 
Pure Vision Levels for Depo- 
Deposit 
Test Formulation 
Control lenses 
sit Inhibition (.mu.g) 
Inhibition 
______________________________________ 
Formulation A 
7.75 ug 5.74 ug 25.9 
Comparative 
7.75 ug 6.46 ug 16.6 
Form. B 
______________________________________ 
TABLE 2A 
______________________________________ 
Lipid Deposit Inhibition and Cleaning Efficacy Data and Results 
Average Lipid 
Deposition on 
Average Lipid 
% Total Lipid 
Pure Vision .RTM. 
Levels for Deposit 
Deposit 
Test Formulations 
Control lenses 
Inhibition (.mu.g) 
Inhibition 
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Formulation A 
381 .mu.g 273 .mu.g 28.3 
Comparative 
381 .mu.g 321 .mu.g 15.7 
Form. B 
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As shown in Table 2A, the Formulation A appears to inhibit lipid deposition 
indicating that the test formulations are coating the lens in such a way 
as to hinder lipid uptake. With respect to protein deposit inhibition, the 
data in Table 2 showed that the Formulation A was the better performer, 
with 25.9% inhibition of protein deposition relative to the control 
deposited lenses with deposit inhibition of 16.6 percent. 
EXAMPLE 3 
The objective of this study was to evaluate the safety and tolerability of 
Formulation A, according to Example 1, as a rewetting drop for a 
continuous-wear lens compared to the currently marketed ReNu.RTM. 
Rewetting Drops while wearing balafilcon A (Bausch & Lomb Purevision.RTM.) 
tinted contact lenses for 4 hours. Twenty (20) subjects were enrolled in a 
4 hour non-dispensing study comparing Formulation A to ReNu.RTM. Rewetting 
Drops. The subjects were all habitual soft spherical contact lens wearers. 
Their mean spherical Rx's were -3.25D in the test eyes and -3.00D in the 
control eyes. Subjects in both groups had less than 0.75D refractive 
cylinder. Each subject wore a pair of balafilcon A tinted contact lenses 
for approximately 4 hours. The eye receiving the test solution was 
randomly selected and remained constant for the duration of the study. 
Subjects were asked to place two drops of each solution into the 
appropriate eyes every hour until the four hour visit. The subjects and 
investigator were masked to solution identity. Prior to lens insertion a 
spherical refraction was performed through which high contrast visual 
acuity with high ambient illumination (HCHI) was measured. Corneal and 
conjunctival staining and limbal and bulbar injection were assessed with 
the slitlamp. Each subject was then fitted with a pair of balafilcon A 
tinted lenses of their power. Each lens was evaluated for centration and 
movement, comfort, and deposits/wettability. A spherical over-refraction 
was then performed. The endpoint of the over-refraction was compared to 
the refractive endpoint to determine the apparent "on-eye" lens power. 
LogMAR visual acuity under HCHI testing conditions was measured through 
the over-refraction. Finally, two drops of each solution were instilled 
into the appropriate eyes and the subject was asked to rate any sting/burn 
and the amount. Testing was repeated at the four hour visit in reverse 
order, with the exception that the baseline refraction was not repeated. 
Unless otherwise noted, a 2-way ANOVA incorporating Time and Solution was 
used to test for differences in each of the parametric dependent variables 
measured. Non-parametric data was analyzed by Friedman ANOVA. Differences 
at the p.ltoreq.0.05 level were considered to be statistically 
significant. For Formulation A, compared to ReNu.RTM. Wetting Drops 
(Comparative Solution B), there were no statistically significant 
differences in comfort, lens movement/centration or anterior ocular 
physiology. A statistically significant increase in apparent lens Rx power 
was found for the test and control solution eyes after four (4) hours. 
Mean difference in apparent lens Rx was less than -0.25D, which was 
considered clinically insignificant. After four hours, both test and 
control solution eyes showed a statistically lower sting/burn visual 
analog score (i.e. more sting/burn). Although one subject developed nasal 
congestion, bulbar injection and lid margin redness after using both drops 
for four (4) hours (test eye was slightly worse than control eye), this 
reaction resolved after discontinuation of the solutions. In conclusion, 
Formulation A appeared to be safe and tolerable for use as an eyedrop 
solution. 
While the invention has been described in conjunction with specific 
examples thereof, this is illustrative only. Accordingly, many 
alternatives, modifications, and variations will be apparent to those 
skilled in the art in light of the foregoing description and it is, 
therefore, intended to embrace all such alternatives, modifications, and 
variations as to fall within the spirit and scope of the appended claims.