Note: Descriptions are shown in the official language in which they were submitted.
~2~
-2-
B~CKGROUND OF THE INVENTION
Just as there are marked differences in the structure
and composition of hard PMMA, silicone, silicone copolymer
gas-permeable contact lenses and soft contact lenses,
there are also marked differences in the maintenance, care
and treatment of the various types of hard, silicone,
silicone copolymer and soft lenses. While patient care
and treatment of hard contact or conventional contact
lenses is relatively simple and uncomplicated, the proper
care and treatment of silicone and silicone copolymer
lenses (gas-permeable) and the newer soft and hydrophilic
lenses has proved to be more complex, time consuming and
costly to the patient.
The primary difference between the conventional hard
lS contact lens and the silicone copolymer lenses and the
more complex soft lenses is the hydrophobic nature of the
silicone copolymer lenses and marked increase in the polar
or water attracting centers of the hydrophilic gel material
from which the soft contact lenses are made. It is this
property of the hydrophilic gel lens that gives the soft
lens its own unique physical properties and clinical
behavior. This polar or water attracting center of the
gel material is represented in the hydroxyethyl metha-
crylate bond as a hydroxyl group (-OH) which attracts and
holds large amounts of water. It is this high water
content held in the expanded matrix of the hydrophilic gel
lens which leads to the special difficulties in cleaning
and disinfecting or asepticising the soft hydrophilic
lens. The hydrophilic nature of soft contact lenses makes
the lenses vulnerable to bacterial contamination. While
studies have demonstrated that bacteria cannot penetrate
the actual intramolecular pores of the hydrophilic lens,
except in defective lenses, the bacteria have an affinity
for protein and tear deposits on the surfaces of the lens
--3--
matrix. In particular, the tears and fluids absorbed by
the soft lenses serve as excellent bacterial culture
media. If defects or nicks occur in the lenses either
during manufacture or subsequent patient wear, bacteria
may find a haven to grow and be sheltered from superficial
lens cleaning and disinfection.
Potentially harmful fungi are also a possible danger
to the soft contact lens. Fungi, like bacteria, can
thrive in tear secretions, other fluids or deposits and
penetrate the lens material directly if enzymatic degrada-
tion of the lens material has taken place.
Similarly, any substantial residual proteinaceous
or tear secretion deposits or lipid deposits remaining in
or on the lens may readily overwhelm and inactivate the
most effective germicidal components of a disinfecting
system, and may thus serve to act as a growth media for a
variety of potentially harmful microorganisms and fungi.
Therefore, it is important that prior to storing the soft
contact lenses in a disinfecting solution, protein and
lipid deposits be removed from the lens surfaces so that
the disinfectant properties of the sterilizing solution or
method will not be overwhelmed by gross organic or inorganic
deposits and pollutants. Therefora, an effective cleaning
step or steps is an essential and mandatory part of any
effective soft lens treatment and maintenance regimen.
Numerous methods of cleaning soft contact lenses to
remove only protein deposits exist. For example, the soft
lenses can be rinsed in tap water in an attempt to remove
protein deposits. Tap water rinsing is virtually ineffec-
tive, removing only from about 1% to about 10% of theaccumulated debris on the ler.s surfaces. Boiling the soft
contact lenses in a saline solution is partially effective,
removing generally from about 5% to 15% of the debris
located on the lens surfaces. Other cleaning methods
include the use of hydrogen peroxide an~ sodium chloride
f~ 74
solutions. Hydrogen peroxide is ineffective since it will
actually oxidize and change the color of the lenses. Use
of high concentrations of sodium chloride aids in removing
some encrustations because of the friction created in
rubbing the lenses with a sodium chloride solution.
However, this method is harmful to the lenses because
scratching of the lens surfaces occurs. Enzymatic cleaners
do not remove deposits such as salts, lipids and mucin.
In addition, the enzymatic cleaners may also discolor the
soft contact lenses. A more detailed discussion of various
types of cleaning procedures and compositions is found in
the April 1978 issue of Review of Optometry in a series of
three articles, one each by: Irving J. Arons; Jerome S.
Lieblein, O.D.; and Frederick D. Kleist and Jon C.
Thorson, M.D.
Therefore, a need has arisen for an effective composition
to remove protein, lipid and other deposits which tend to
remain on gas permeable and soft contact lenses after a
wearing period has been completed. A need has also arisen
for a gas permeable and soft contact lens cleaner that can
be easily rinsed from the lens surfaces after cleaning has
been accomplished and that does not contain components
which significantly bind to the lens or are otherwise
deleterious to the lens material.
Since contact lenses are susceptible to bacteria and
fungi, the cleaner should contain a preservative system to
insure that the cleaning solution does not become contami-
nated by such organisms, the use of which co-lld transfer
the organisms to the lenses. Compounds such as thimerosal
potassium sorbate, chlorhexidine, and sorbic acid when used
as the main preservative, which are known for use in
preservative systems for maintaining a solution sterile or
essentially sterile have been used. However, these com-
pounds have drawbacks in that they can discolor lenses and
also be concentrated in the lens matrix and cause irritation,
7~
-5-
sensitization, excessive burning and red eye, which can
prevent the patient from wearing the lenses. With the
advent of extended wear lenses, it becomes even more
important to avoid such problems, since those lenses can
remain in the eye for several weeks.
,,i
~l2~7~
--6--
SUMMARY OF THE INVENTION
In one aspect, this invention relates to novel and
effective silicone, silicone copolymer (gas permeable) and
soft contact lens preservative systems and prophylactic
cleaning compositions for removing deposits from the
surface of the lenses. More particularly, this invention
relates to highly effective silicone, silicone copoIymer
and soft contact lens cleaners for use after each wearing
day is completed that remove lipids and proteins from the
surfaces ot the lenses and a preservative system which
avoids hypersensitivity problems associated with preserva-
tive systems containing sorbic acid, potassium sorbate,
thimerosal or chlorhexidine, for example. The invention
is especially suitable for use on silicone, silicone
copolymer and soft lenses (such as HEMA contact lenses,
for example~ including extended wear contact lenses. The
invention is also suitable for use in connection with hard
contact lenses.
In another aspect, this invention relates to a soft
contact lens cleaning composition that will remove both
proteins, lipids and other foreign deposits from the
surfaces of the contact lens thereby eliminatin~ inter-
ference with wearing comfort which can be caused by such
deposits. In addition, the cleaning composition helps
maintain clear vision throughout each wearing period. In
another aspect, this invention relates to an efficient
cleaner for soft contact lenses that is simple to use an~
can be easily rinsed from the contact lens after the
cleaning is completed.
In accordance with the invention, a preservative
system is provided that is incorporated in a contact lens
cleaning solution. The preservative system is effactive
for maintaining the solution sterile, preventing bacteria
and other organisms from contaminating the solution after
~.2~ f~
--7--
its container has been opened and an initial use has been
made of a portion of the solution, for example. While
intended primarily for use in connection with soft contact
lenses, the preservative system may also be used in con-
nection with hard contact lenses.
The preservative system of the invention is safe and
effective and is not deleterious to the human eye or
ocular tissue. Thus, if a cleanin~ composition containing
the preservative system is not ade~uately rinsed from the
lens, harmful effects and/or discomfort does not occur.
Further, the preservative system does not discolor soft
contact lenses and is not otherwise deleterious to soft
lenses. Accordingly, the shortcomings of preservative
systems containing compounds such as sorbic acid, potassium
sorbate, thimerosal or chlorhexidine, for example, are
avoided.
The preservative system of the invention for use in a
contact lens cleaning composition is trimethoprim, present
in an effective amount to maintain the sterility of the
cleaning composition. ~hile various adjuvant bactericides
may also be present in the composition, it has been dis-
covered that trimethoprim alone is effective in maintaining
the sterility of a contact lens cleaning composition.
Thus, if desired, no other bactericides need be present in
the cleaning composition. Various adjuvant bactericides
that can optionally be included are ethylenediaminetetraacetic
acid (EDTA) or a water soluble salt thereof and sorbic
acid. Ascorbic acid, or a salt thereof, and/or benzyl
alcohol, may be utilized in place of or in addition to
sorbic acid. Usually, an effective amount of trimethoprim
is from about 0.05% to about 2.0% by wei~ht of the total
composition. Generally, if present, the adjuvant bacteri-
cides are present as follows: EDTA, from about 0.025% to
about 0.5%; sorbic acid, from about 0.001% to about 0.35%;
and benzylalcohol from about 0.1% to about 5.0%, all by
weight of the total composition~ It is to be understood
that the desired effect, maintaining sterility, can also
be achieved by using higher concentrations of the fore-
going compounds. Ascorbic acid, or a salt thereof, may be
present in an effective amount, usually of from about 0.1%
to about 20% calculated as ascorbic acid. Suitable salts
of ascorbic acid include the sodium and calcium salts
thereof.
In accordance with another aspect of the present
invention, a method is provided for maintaining the steri-
lity of contact lens cleaning formulations which method
includes providing in the formulation a preservative
system in accordance with the invention. The sterility of
the solution is preserved while avoiding the use of bacteri~
cides which are absorbed by soft lenses and which are
incompatible with ocular tissue or otherwise cause eye
irritation and/or lens discoloration.
In accordance with the preferred aspects of the
present invention, a highly effective prophylactic soft
contact lens cleaning composition is provided. The pre-
ferred cleaning composition is an aqueous solution that
effectively removes protein, lipid and other deposits and
materials that tend to adhere to the lens surfaces which
are accumulated from normal lens wearing. The preferred
cleaning composi~ion according to the invention can be
easily and ~uickly rinsed from the lens surfaces after
cleaning is accomplished.
Preferably, the aqueous cleaning composition according
to the invention comprises a non-ionic detergent system, a
preservative system, a rinsing aid, and has a tonicity of
from about 1.0 to about 2.0 and a pH of from abo~t 6.0 to
about 7Ø
In accordance with one embodiment of the invention,
an aqueous cleaning composition is provided that is espe-
cially suitable for cleaning soft contact lenses. The
_9_
cleaning composition contains a preservative system of theabove description and a cleaning component or components.
Any suitable detergent or other type of cleaning component
may be utilized that is suitable for cleaning contact
lenses. If the cleaning composition is intended for
cleaning soft contact lenses, then the detergent or cleaning
component should be suitable for use with soft contact
lenses.
The surfactants which are employed generally should
be completely miscible with water at the concentrations
employed and generally should provide a clear solution.
In addition, the surfactant must be stable under the
disinfecting conditions, must not act adversely with the
soft contact lens, nor with other materials present in the
solution and, finally, must not irritate the eye. There-
fore, the surfactant must not be adsorbed by the soft
contact lens, while preferably being capable of solubilizing
the proteinaceous and lipid materials adsorbed on the lens
and preventing redeposition during the disinfectian treatment
and subseguent storage.
One group of suitable surfactants is the non-ionic
surfactants, particularly hydroxyalkylated surfactants and
polyoxyalkylated surfactants. Extremely effective at very
low concentrations are N-hydroxyalkylated carboxamides of
~`atty acids of from 10-18 carbon atoms, preferably of from
12-14 carbon atoms and having from 0-1 site of olefinic
unsaturation as the only unsaturation, preferably saturated.
There will normally be two hydroxyalkyl groups of from
2-3 carbon atoms, which may be the same or different.
The polyoxyalkylated non ionic detergents may be
solely polyo~yalkylene groups of from 2-3 carbon atoms or
may have a polyoxyalkylene chain bonded directly or indi-
rectly to an aliphatic chain of from 10-18 carbon atoms.
The alkyl containing group may be a sorbitan ester, an
alkylphenyl, alkyl, a carboxylic acid, or the like. The
~10~ 7~7~
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. These various non-
ionic detergents are commercially available under a widevariety of trade marks, such as Tween, Igepal, Pluronic,
Brij, and Myrj. The alkylene oxy chains will generally
range on the average from about 5 to 60 oxyalkylene units.
The ampholytic detergen-ts will normally be betaines
having an aliphatic carbon chain bonded to nitrogen of
from about 10-18 carbon atoms, preferably from about
10-14 carbon atoms. Of particular interest are compounds
of the following formula
N
R - C - N - CH2CH20CH2C02
Il
CH2CO2Na
wherein R is of from 9-13 carbon atoms, usually ll carbon
atoms.
More specifically, the non-ionic cleaner may be a
poly(oxyethylene) - poly(oxyethylene) block copolymer.
Suitable block copolymers include those sold under the
trademark "Pluronic" by the ~ASF-Wyandotte Chemical Corp.,
for example. Examples of suitable amphoteric surfactants
and methods of making them are found in U.S. Patent
Nos. 2,781,349; 2,781,350; 2,781,351; 3,231,580; 3,231,581;
3,452,042; 3,658,895; and 3,697,452. Especially suitable
amphoteric surfactants are available from the Miranol
Chemical Company, Inc. under the trade mark Miranol Ampho-
teric Surface Active Agents. One specific amphoteric
surfactant is available as Miranol H2M concentrate.
It is to be understood that the invention is not
limited to the foregoing types of cleaners, detergents or
,
surfactants. Any type of material which can be used to
clean contact lenses and which is compatible with the
preservative system of the present invention and is other-
wise suitable for use in a contact lens cleaning solution
can be utilized, whether an a~ueous solution or a gel.
Noniconic, aniconic or cationic detergents may be utilized.
Preferably, the non-ionic detergent system comprises
three distinct types of non-ionic detergents. One of the
non-ionic detergents is a polyoxypropylene-polyoxyethylene
block copolymer having a molecular weight of from about
1,100 to about 14,000. Preferably, the polyoxyethylene or
hydrophilic unit of the block copolymer is about 70% to
about 80% of the total molecular weight of the block
copolymer, the remainder of the block copolymer being
composed of polyoxypropylene or hydrophobic unit. The
block copolymer is generally present in an amount of from
about 1.0% to about 15.0% by weight of the total aqueous
composition. Another type of detergent in the non-ionic
detergent system is an amphoteric surface active agent,
generally present in an amount of from about 0.5% to about
8.0% by weight of the total aqueous composition. The
preferred amphoteric surface active agent is 2-Cocoyl-2-
imidazolinium lauryl sulfate-1-carboxymethyloxyethyl-1
carboxymethyl disodium. The other type of non-ionic
detergent present in the detergent system of the preferred
composition according to the invention is an alkylaryl
polyether alcohol that is water soluble. The preferred
type of alkylaryl polyether alcohol is an isoctylphenoxy-
polyethoxy~thanol. This component is generally present in
30 an amount of from about 0.005% to about 8.0% by ~eight of
the total aqueous composition.
Preferably, propylene glycol is present in the cleaning
compositions in accordance with the invention in an amount
of from about 0.005% to about 5.0% by weight of the total
aqueous composition. Propylene glycol helps provide ~or
-12-
ease of rinsing the cleaning composition from the contact
lens surface and also acts as a preservative of the compo-
sition and a thickening agent.
Compositions in accordance with the invention gene-
rally have a pH of from about 6.0 to about 7.0 and preferablyfrom about 6.0 to about 6.5. This slightly alkaline pH
helps to dissolve protein and alds in rinsing the composi-
tion from the lens. Sodium bicarbonate may be present in
the composition, generally from about 0.01% to about 3.0%
by weight of the total composition for adjustment of pH.
The soft contact lens cleaning compositions according
to the invention preferably have a tonicity of from about
1.0 to about 2Ø Thus, the compositions of the invention
can be mildly hypertonic to help prevent possible absorp-
tion into the lens matrix of foreign matter, bacteria orother residue which could build up and cause contamination
problems and deterioration and discoloration of the lens
itself. However, a hypotonic cleaning solution could be
used and would not interfere with the cleaning ability and
rinseability of the solution. The remainder of the com-
position is purified water U.S.P.
-13-
DETAILED DESCRIPTION OF THE INVENTION
The use of appropriate antiseptic bactericidal and
fungicidal chemical agents requires that the selected
chemical agents be compatible with all other components of
the solution as well as with the contact lens material.
The essential considerations in determining the optimum
antibacterial and antifungal agents are: (1) does not
bind to protein; and (2) does not react with or absorb to
the soft lens material or matrix. The preservative systems
of the invention meet these requirements.
According to the invention, the preservative system,
which provides antibacterial and antifungal activity, will
usually include rom about 0.05% to about 2.0% trimethoprim,
preferably from about 0.075% to about 0.3% and most preferably
about 0.1% by weight of the total composition. Trimethoprim
is also known as 2,4-Diamino-5-~3,4,5-trimethoxybenzyl)-
pyrimidine and as syraprim. See, for example, The Merck
Index, eighth edition, pg. 1,077.
While not necessary for a suitable preservative
system that maintains sterility of a contact lens cleaning
composition adjuvant bactericides may be present in the
preservative system, as previously described.
When ascorbic acid is utilized, preferably monothio-
glycerol is included in an amount effective to stabilize
the ascorbic acid compound. Most preferably, in this
embodiment monothioglycerol is present in a weight ratio
of monothioglycerol to the ascorbic acid compound, calcu-
lated on the basis of ascorbic acid, of l:SO. Thus, for
example, if the concentration of the ascorbic acid compound
is 10%, calculated on the basis of ascorbic acid, the
concentration of monothioglycerol is 0.2% by weight.
When ascorbic acid is utilized in the preservative
system, in order to increase the shelf life, the composi-
tions are formulated and packaged in an atmosphere that is
-14-
substantially devoid of free oxygen. For example, the
compositions can be formulated and sealed in sterile
containers, in the presence of a nitrogen or carbon dioxide
atmosphere. Further, it is advantageous for the ascorbic
acid compound to be packaged in a non-transparent container
to reduce degradation that can be caused by ultraviolet
radiation. The ascorbic acid could also be packaged
separately, until the time of use, for example.
The preferred prophylactic cleaning compositions of
the present invention also include propylene glycol.
Propylene glycol is usually present in an amount of from
about 0.005% to about 5.0% by weight of the total aqueo~ls
composition.
The preferred concentration of propylene glycol is
about 1.0% by weight of the total aqueous composition.
Propylene glycol acts as a humectant, increases the viscosity,
body and feel of the cleaner without interfering with the
detergent action of the detergent system. In addition,
the propylene glycol also acts as a preservative and
fungal growth inhibitor. Further, the propylene glycol
aids in eliminating fogging of the soft contact lenses,
which in itself is a major problem to soft contact lens
wearers. Another important aspect of propylene glycol in
the prophylactic composition of the present invention is
that it permits the composition to be easily rinsed rom
the lens after cleaning has been accomplished.
The inclusion of ethylenediaminetetraacetic acid or a
water soluble salt of ethylenediaminetetraacetic acid
serves as a buffering and preservative component of the
composition according to the invention, and has also been
demonstrated to have antibacterial and antiungal properties.
The preferred salt of ethylenediaminetetraacetic acid is
disodium ethylenediaminetetraacetate (disodium EDTA or
disodium edetate). Other salts of EDTA which may be
utilized include, for example, mono-, di-, tri- and tetra-
-15-
alkali metal salts. Benzyl alcohol can also be included,
usually in an amount of from about 0.1% to about 5.0% by
weight of the total composition.
The non-ionic detergent system of the composition
according to the invention preferably contains three
different types of non-ionic surface acting agents or
detergents, each of which should be compatible with the
contact lens material. The synergistic effect of the
combined detergents causes both proteins and lipids to be
removed from the lens surfaces when the cleaning composi-
tion according to the invention is used. The three types
of non-ionic detergents preferably present in the composi-
tion of the present invention are: (1) a polyoxypropylene-
polyoxyethylene block copolymer; (2~ an amphoteric surface
active agent; and (3) an alkylaryl polyether alcohol.
Satisfactory results can also be obtained with an embodiment
of the invention having the following two types of non-ionic
detergents: (1) an amphoteric surface active agent; and
(2) an alkylaryl polyether alcohol. It is to be unerstood
~0 that the detergent system can comprise an anionic deterqent,
a cationic detergent, a nonionic detergent or any combina-
tion thereof.
The block copolymer used in the preferred composition
of the present invention are polyoxypropylene-polyoxyethylene
block copolymers which are compatible with soft contact
lenses. The block copolymers for use in accordance with
the preferred embodiment of the invention have a molecular
weight of about 1,100 to about 1~,000 and a water solubi-
lity in excess of 10 grams per 100 milliliters. Preferably,
about 70% to about 85% of the total molecular weight of
the block copolymer consists of the hydrophilic polyoxyethy-
lene group with the remaining weight of the molecule
representing the hydrophobic polyoxypropylene bas~ and
possesses relatively low foaming characteristics.
~L2~
-16-
One group of block copolymers suitable for use in the
composition according to the present invention are those
sold by BASF-Wyandott Corporation of Wyandott, Michigan,
under the trademark "Pluronic." The following Pluronic
block copolymers are suitable for use in the composition
of the present invention and are set forth for example and
not limitation: Pluronic F-68, Pluronic F-77, Pluronic P-75,
Pluronic P-65, Pluronic L-64, Pluronic F-87, Pluronic F-88,
Pluronic F-98, Pluronic F-108 and Pluronic F-127. The
block copo~ymer is generally present in the preferred
composition of the present invention in an amount of from
about 1.0% to about 15.0% by weight of the total aqueous
composition, and preferably comprises about 6.0% by weight
of the total aqueous composition. Preferably, the block
copolymer used in accordance with the invention has rela-
tively low foaming characteristics.
The preferred type of amphoteric surface active agent
is 2-Cocoyl 2-imida~olinium lauryl sulfate-1-
carboxymethyloxyethyl-1-carboxymethyl disodium which is
also sold un~er the trade name "Miranol 2 ~CA Modified" by
the Miranol Chemical Company, Inc. of Irvington, New
Jersey. The amphoteric surface active agent is present in
the preferred composition of the present invention in an
amount of from about 0.5% to about 8.0% of the total
weight of the a~ueous composition and preferably comprises
about 3.0% of the total aq~leous composition. One substitute
for "Miranol 2 MCA Modified" is "Miranol MHT" which is
also sold by the Miranol Chemical Company, Inc.
The third type of non-ionic detergent which may be
present in the detergent system is an alkylaryl polyether
alcohol. The preferred type of alkylaryl polyether alcohol
in the composition of the present invention is isooctyl
phenoxypolyethoxyethanol. The most preferred type of iso-
octylphenoxypolyethoxyethanol contains about 9 units of
ethoxyethanol per unit of isooctylphenol and has a molecular
-
37~
-17-
weight of about 630. The most preferred alkylaryl polyether
alcohol is sold under the trademark "Triton ~-lO0" by the
Rohm & Haas Company of Philadelphia, Pennsylvania. The
alkylaryl polyether alcohol is present in a concentration
of from about 0.005% to about 5.0%, and preferably about 1.0%,
by weight of the total aqueous composition. The alkylaryl
polyether alcohols are also known as octylphenolethylene-
oxide. The alkylaryl polyether alcohol complements the
cleansing characteristics of the block copolymers and
helps to remove ocular secretions, proteinaceous deposits
and other materials which may be deposited upon the surfaces
of the lens.
The remainder of the composition is purified water
U.S.P. and preferably includes combinations of essentially
neutral and alkaline salts compatible with ocular tissue
and soft contact lens material which are water soluble,
generally present in a concentration to pro~ide an aqueous
composition salt content equivalent to from about 1.2 to
~about 1.7 tonicity. Thus, the soft contact lens cleaning
;20 solutions o~ in the present invention can be mildly hypertonic
which helps in the prevention of possible absorption into
the lens matrix of foreign matter, protein, lipids and
bacteria which could build up and cause contamination
problems and deterioration and discoloration of the lens
itself. Sodium chloride can be present in the soft contact
lens cleaning composition in an amount from about 0.05% to
about 2.0% by weight of the total aqueous composition and
preferably in an amount of about 0.7~8% by weight of the
total aqueous composition. Potassium chloride is another
salt which is preferably used in conjunction with sodium
chloride and should generally be present in an amount of
from about 0.05% to about 2.0% by weight of the total
agueous composition and preferably in an amount of about
0.28% by weight of the total aqueous composition.
L/~L
-18-
The pH of the soft contact lens cleaning composition
of the present invention is preferably slightly alkaline.
The preferred pH range is from about 6.0 to about 6.5.
Sodium bicarbonate can be present in the composition in an
amount from about 0.01% to about 3.0% by weight of the
total a~ueous composition and preferably in an amount of
about 0.1% by weight of the total a~ueous composition.
The a~ueous cleaning compositlons according to the
present invention are preferably utilized as part of the
total patient regimen for maintaining and treating soft
and semi-hard contact lenses. Thus, an effective method
of contact lens storage is an important part of any effec-
tive soft or semi-hard contact lens treatment and mainte-
nance regimen. Separate cleaning of the lenses with the
preferred cleaning composition according to the present
invention helps to insure that gross organic or inorganic
deposits and pollutants are removed, including both proteins
and lipids from the surfaces of the lenses to minimize
wearing discomfort and to maximi~e clear vision with sot
contact lenses. The preferred cleaning composition accord
ing to the present invention allows for a rapid and eficient
cleaning of the lens without any need for excessive rubbing.
For example, excessive rubbing between a thumb and fore-
finger could cause tearing or scratching of the lens
which, in addition to beiny deleterious from a vision
standpoint, could also permit the accumulation of dirt and
other deposits into the scratches and/or tears. In addi-
tion, the preferred soft contact lens cleaning composition
according to the present invention allows for fast and
easy rinsing of the cleaning composition from the lens
after cleaning has been accomplished which reduces the
amount of wear and tear exerted on the lens from cleaning.
Use of the composition also eliminates the need for use of
an enzymatic cleaner.
--19--
Whereas the present invention has been described with
respect to specific embodiments thereof, it will be under-
stood that various changes and modifications will be
suggested to one skilled in the art and it is intended
that the invention encompass such changes and modifica-
tions as fall within the scope o the appended claims.
