Contact lens cleaning compositions containing an enzyme and a carboxy vinyl polymer

Contact lens cleaning compositions containing a combination of an enzyme and a carboxy vinyl polymer, and a method of cleaning contact lenses with such compositions are described. The compositions are capable of cleaning soiled contact lenses very rapidly and completely due to a favorable interaction between the enzyme component and an abrasive precipitate formed by the carboxy vinyl polymer component when a small amount of the compositions is rubbed on the lenses.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to the field of contact lens care. More 
particularly, this invention relates to compositions for cleaning contact 
lenses which comprise an enzyme component and a carboxy vinyl polymer 
which forms an abrasive precipitate when the compositions are rubbed on 
contact lenses. 
2. Discussion of Related Art 
The cleaning of human-worn contact lenses is a problem which has been 
addressed in numerous prior art patents and other publications. Many of 
the previous attempts to solve this problem has focused on the use of 
particular types of surfactants; the following patents represent examples 
of such attempts: U.S. Pat. Nos. 3,882,036; 3,954,644; 4,046,706; and 
4,599,195. The use of enzymes has also been proposed as a solution to this 
problem; U.S. Pat. Nos. 3,910,296; 3,954,965; 4,096,870; 4,521,254; and 
4,609,493 describe this approach. A relatively recent approach addressing 
the cleaning problem utilizes polymeric particles as an abrasive material 
to physically remove deposits from the surface of the lens; this approach, 
which has been relatively successful, is described in U.S. Pat. No. 
4,493,783. U.S. Pat. Nos. 4,394,179 and 4,534,878 describe approaches 
wherein inorganic abrasive materials are utilized. U.S. Pat. No. 4,533,399 
describes the use of a fibrous web to clean contact lenses. 
There have been numerous other attempts to solve the cleaning problem in 
addition to those cited above. The following U.S. patents may be referred 
to for additional background information in this regard: 4,127,423; 
4,357,173; 4,421,665; 4,440,662; 4,500,441; and 4,504,405. 
A new approach to the cleaning problem is described in the copending and 
commonly assigned application of Van Duzee titled "CONTACT LENS CLEANING 
PRODUCT AND METHOD OF USE." This approach is based on the use of a 
nonwoven web impregnated with an enzyme to clean contact lenses. 
Another new approach is described in the copending and commonly assigned 
application of Bhatia, et al., titled "CONTACT LENS CLEANING COMPOSITION 
AND METHOD OF USE." This approach is based on the use of compositions 
comprising an enzyme and an abrasive particulate material to clean contact 
lenses. 
SUMMARY OF THE INVENTION 
A principal object of the present invention is the provision of 
compositions capable of rapidly and completely removing deposits of 
proteins, lipids, and other materials from contact lenses. A further 
object of this invention is the provision of a method of cleaning contact 
lenses using such compositions. 
The foregoing objects and other general objectives of the present invention 
are achieved by the provision of contact lens cleaning compositions which 
comprise an enzyme to facilitate chemical decomposition and removal of 
deposits from contact lenses, particularly deposits of protein and lipid 
materials; a carboxy vinyl polymer which is dissolved in the composition, 
but forms an abrasive precipitate when rubbed on a contact lens, thereby 
facilitating physical removal of such deposits; and a suitable carrier for 
the enzyme and carboxy vinyl polymer. It has been discovered that such 
compositions are capable of removing deposits of proteins, lipids, and 
other materials from the surfaces of contact lenses in a very efficacious 
manner. The extent of cleaning achieved with these compositions is at 
least comparable with the cleaning achieved with cleaning compositions of 
the prior art, and in most cases is significantly better than the cleaning 
achieved with prior art compositions. The compositions of the present 
invention have been found to clean contact lenses much more rapidly than 
prior art compositions capable of providing a comparable extent of 
cleaning. The present compositions therefore represent a major advancement 
in the field of contact lens cleaning agents. 
DESCRIPTION OF PREFERRED EMBODIMENTS 
The contact lens cleaning compositions of the present invention contain an 
amount of one or more enzymes sufficient to substantially reduce deposits 
of proteins, lipids, and other materials on the lens being treated. The 
amount of enzyme contained in the compositions will vary depending on 
factors such as the particular type of enzyme utilized and the activity of 
that enzyme, the type of contact lens being treated, the cleaning regimen 
being employed (e.g., daily or weekly), and the concentration of other 
components in the compositions. The compositions of the present invention 
will typically contain from about 0.1% to about 50.0% by weight of one or 
more enzymes. 
The enzymes which may be utilized in the present invention include all 
enzymes which are capable of removing deposits of proteins, lipids, and 
other materials from contact lenses safely and effectively. The "safely" 
requirement means that the enzymes must be relatively nontoxic to the eye 
at low concentrations, so that only mild ocular irritation will occur if a 
small amount of enzyme is inadvertently placed in the eye as the result of 
inadequate rinsing of a treated lens. The enzymes must also be capable of 
being easily removed from treated lenses by means of rinsing, and must not 
damage the contact lens being treated. Enzymes which meet the foregoing 
requirements are referred to herein as being "ophthalmically acceptable." 
Those skilled in the art will appreciate that the enzymes are also 
required to be chemically compatible with the other components of the 
present compositions. 
The enzymes utilized in the present invention will most frequently be 
enzymes having proteolytic and/or lipolytic activity, since deposits of 
proteins and lipids are formed on most, if not all, human worn contact 
lenses. Examples of suitable proteolytic enzymes include pancreatin 
papain, Prolase RH (available from G. B. Fermentation Corp.), ficin, and 
bromelain. Examples of suitable lipolytic enzymes include Lipase K-3000 
and Lipase AP6 (available from Amano Corp.), and pancreatic lipase. Those 
skilled in the art will readily appreciate that other proteolytic and 
lipolytic enzymes of plant, animal, bacterial, fungal or synthetic origin 
might also be employed in the present invention. Certain enzymes may 
require the presence of a stabilizing agent, such as acetylcysteine. Other 
methods of enzyme stabilization, such as bound enzyme systems and 
microencapsulated enzyme systems, may also be utilized. In a preferred 
embodiment of the present invention, enzyme stabilization is generally not 
a concern because the enzyme component of the lens cleaning compositions 
is packaged separately from the other components prior to use and is then 
combined with the other components at the time of initial use. This 
approach avoids the need for long-term enzyme stability in order to 
provide the compositions with a shelf-life of several months or more 
(i.e., roughly 18 months, generally), since the enzyme only needs to be 
stable for a relatively short time following combination of the enzyme and 
abrasive components (i.e., roughly 1 to 14 days, or in some cases slightly 
longer). This embodiment of the invention is described in greater detail 
below. 
The compositions of the present invention contain an amount of a carboxy 
vinyl polymer sufficient to substantially reduce all deposits present on 
the surfaces of a contact lens by forming an abrasive precipitate when 
rubbed on the surface of the lens, thereby facilitating physical removal 
of such deposits. The precipitate formed by the carboxy vinyl polymer 
component of the present compositions is particularly effective in 
removing loosely bound deposits from the surfaces of a lens, such as 
deposits of debris (e.g., lint) and cosmetic residues, as well as large 
deposits of proteins, lipids, and other materials. 
The carboxy vinyl polymers are contained in the present compositions in 
solubilized form. The mechanism by which these polymers form an abrasive 
precipitate when the compositions are rubbed on contact lenses is not 
completely understood at this time. It is believed that this precipitate 
is the result of water loss which occurs immediately when a few drops of 
the compositions are rubbed on a contact lens. This water loss results 
from a portion of the water in the compositions being taken up by the 
contact lens being treated, a portion of the water evaporating, and a 
generalized loss of the solubilizing effect of the water in the 
compositions as the compositions are spread out in a thin film when rubbed 
on contact lenses. This loss of water causes at least a portion of the 
carboxy vinyl polymer in the composition to come out of solution or 
"precipitate." The thus formed precipitate has been found to be very 
effective as an abrasive material in the cleaning of contact lenses, and 
may be used very advantageously for this purpose, because of the ease with 
which it can be removed from the lens after completion of cleaning by 
merely rinsing the lens to resolubilize the precipitated carboxy vinyl 
polymer. 
The carboxy vinyl polymers which may be utilized in the present invention 
have a molecular weight of from about 1,000,000 to about 6,000,000. The 
polymers have carboxylic functional groups, and preferably contain 2 to 7 
carbon atoms per functional group. These polymers include the 
carboxypolymethylene polymers available from the B. F. Goodrich Company 
under the name CARBOPOL. 
The amount of carboxy vinyl polymer contained in the present compositions 
will vary depending on factors such as the particular type of carboxy 
vinyl polymer utilized, the type of contact lens being treated (e.g., 
"hard" or "soft") and the cleaning regimen being employed. The 
compositions of the present invention will typically contain from about 
0.5% to about 25% by weight of one or more carboxy vinyl polymers. 
The compositions of the present invention further comprise a carrier which 
is compatible with both ocular tissue and the other components of the 
compositions, including the carboxy vinyl polymer and enzyme components. 
Carriers which meet these requirements are referred to herein as being 
"ophthalmically acceptable." The carrier will typically be aqueous, and 
may include a thickening agent, such as various celluloses known for such 
use in the art (e.g., cellulose, hydroxyethylcellulose, and methoxy 
cellulose); polyethylene glycol with a molecular weight distribution of 
about 400 to about 4,000; low molecular weight hydroxyethylmethacrylate; 
polyvinyl alcohol; polyvinylpyrrolidone; polysaccharide gums (e.g., 
xanthan gum) and mixtures thereof. 
The compositions may optionally further comprise one or more surfactants, 
preservatives, chelating agents, tonicity agents or antistatic agents. 
These types of ingredients are well known in the art. An exhaustive 
listing of illustrative examples of these ingredients is therefore 
believed to be both unnecessary and inappropriate. Representative examples 
of these types of ingredients include: surfactants such as 
polyoxyethylene/polyoxypropylene copolymers (e.g., PLURONIC 127); 
preservatives such as thimerosal, sorbic acid, POLYQUAD.RTM. (i.e., a 
polymeric germicide also known as ONAMER M, available from Onyx Chemical 
Co.), and benzalkonium chloride; chelating agents such as EDTA; tonicity 
agents such as sodium chloride and potassium chloride; and antistatic 
agents such as Foraperle B320 (available from Rilsan Corporation). 
As mentioned above, a preferred embodiment of the present invention 
utilizes a packaging arrangement wherein the enzyme component of the 
compositions is not combined with the remaining components of the 
compositions until time of use. This arrangement avoids the necessity for 
long-term shelf-life stability. The compositions packaged in this manner 
are particularly preferred for professional use by an eye care specialist, 
such as an ophthalmologist, optometrist, optician or trained technician. A 
composition packaged in this manner can be conveniently prepared for use 
by merely combining the enzyme with the remaining components of the 
composition and mixing the combined components by means of agitation 
(i.e., shaking and/or stirring). The type of packaging utilized is not 
critical, so long as the packaging is suitable for phermaceutical use. The 
use of a sealed foil packet for the enzyme component and a sealed plastic 
bottle for the remaining components of the composition represents a 
preferred packaging arrangement. With this arrangement, the enzyme is 
simply removed from the packet, added to the container, and mixed with the 
contents of the container to provide a contact lens cleaning composition 
according to the present invention. Depending on the precise nature of the 
formulation, this composition would be useful for either a single, 
immediate use or many uses extending over several days. 
The present invention also concerns a method of cleaning contact lenses 
utilizing the above-described compositions. This method comprises applying 
a small amount of the composition (e.g., a few drops if in liquid form) to 
the surfaces of the lens and rubbing the composition over the surfaces of 
the lens for a short time, normally for 30 seconds or less. The thus 
cleaned lens is then rinsed with a suitable contact lens rinsing solution 
(e.g., saline solution) to remove the cleaning composition and debris from 
the surface of the lens. As mentioned above, rinsing of the lens results 
in rehydration and consequent dissolution of the abrasive precipitate 
formed by the carboxy vinyl polymer. The dissolution of this precipitate 
helps to ensure that no abrasive material remains on lenses subsequent to 
cleaning with the present compositions; this represents a major advantage 
of the present invention. The lens will normally be completely cleaned at 
this point. Prior to reinsertion in the eye, the cleaned lens will 
normally be disinfected using various known disinfection methods, such as 
soaking in a disinfectant solution containing one or more germicides. 
The mechanism which enables the compositions of the present invention to 
clean contact lenses completely and rapidly is not totally understood. 
However, it is clear that the remarkable results achieved with these 
compositions ae attributable to a positive interaction between the enzyme 
component of the present compositions and the abrasive precipitate formed 
by the carboxy vinyl polymer component of the compositions. Prior art 
compositions containing enzymes have generally been capable of completely 
cleaning lenses, but have typically required an extended soaking period of 
15 minutes or more to achieve this cleaning. Prior art compositions 
containing an abrasive material have generally had the advantage of 
working very rapidly (i.e., in roughly one minute or less); however, the 
degree of cleaning achieved with these compositions has not been as 
complete as the cleaning achieved with enzyme-containing compositions. The 
prior art abrasive compositions have generally been very effective in 
removing large deposits from the surfaces of contact lenses, but have been 
less effective in removing minute deposits from the lens surface and have 
generally not been effective in removing deposits located beneath the 
surface of the lens in the pores or interstices of the lens. The 
compositions of the present invention have demonstrated a very surprising 
ability to clean soiled contact lenses both very rapidly and completely. 
The degree of cleaning achieved with the present compositions is much 
better than that achieved with prior art abrasive compositions, and the 
rapidity of cleaning is comparable or in some cases superior to that of 
prior art abrasive compositions.

EXAMPLE 1 
This example further illustrates the formulation of compositions according 
to the present invention. 
______________________________________ 
Concentration (w/v %) 
Composition 
Ingredient A B C 
______________________________________ 
Pancreatin 6X 
1.0 2.0 5.0 
CARBOPOL 2.0 2.0 2.0 
EX140 
Boric Acid 0.35 0.35 0.35 
Sodium Borate 
0.11 0.11 0.11 
Edetate Disodium 
0.1 0.1 0.1 
Sodium Chloride 
0.7 0.7 0.7 
POLYQUAD .RTM. 
0.001 + 10% 
0.001 + 10% 
0.001 + 10% 
Excess Excess Excess 
HCl/NaOH QS pH 5.5 QS pH 5.5 QS pH 5.5 
Purified Water 
QS 1000 mL QS 1000 mL QS 1000 mL 
______________________________________ 
These compositions may be prepared as follows. Approximately 400 mL of the 
purified water is added to an aspirator bottle provided with appropriate 
attachments (e.g., 0.2 micron millipore filter, tubing, etc.). The 
CARBOPOL EX140 is then added to the purified water in the aspirator and 
mixed thoroughly. The set up is then steam sterilized at 121.degree. C. 
under 15 lbs. pressure for 30 minutes, with continuous stirring until the 
solution has cooled. A second solution is then prepared by sequentially 
dissolving the sodium chloride, boric acid, edetate disodium, sodium 
borate, POLYQUAD.RTM. and pancreatin in approximately 500 mL of the 
purified water, and adjusting the pH of the resulting solution to 5.5. The 
second solution is then filtered into the first solution using a 0.2 
micron millipore filter assembly and mixed thoroughly. The final volume is 
then adjusted to 1000 mL with the remaining purified water.