CA1152843A

CA1152843A - Abrasive-containing contact lens cleaning materials

Info

Publication number: CA1152843A
Application number: CA000352199A
Authority: CA
Inventors: Joseph C. Salamone; Edward J. Ellis
Original assignee: Polymer Technology Corp
Current assignee: Polymer Technology Corp
Priority date: 1979-06-25
Filing date: 1980-05-16
Publication date: 1983-08-30
Also published as: JPH0381136B2; GB2055118A; JPS566215A; FR2459993A1; DE3021034A1; IT8022938A0; FR2459993B1; IT1131637B; AU537744B2; DE3021034C3; AU5931080A; GB2055118B; DE3021034C2

Abstract

ABSTRACT OF THE DISCLOSURE

New cleaning solutions for contact lens have a surface active agent, an inorganic abrasive, and a suspending agent to provide a suspension in an aqueous solution or organic liquid.

Description

SSKa 1 ABRASIVE-CONTAIN~IRG CONTACT LENS CLEANIRG ~ATERIALS

BACKGROUND~OF THE INVENTION
.
It has long been recognized in the art that contact lenses must remain free of surface deposits in order to maintain their wearing comfort and optimum vision and reduce the potential~for ocular change.
Unfortunately, contact lenses are susceptible to acquiring surface deposits from exogenous sources (mascara> hair spray, etc.) and endo-genous sources (mucous,oily meibomian secretions, etc.). Silicone containing contact lenses are the most vulnerable o~ all contact lenses to the acquisition of tenacious, waxy surface deposits that are dif-f7cuit, ;f not impossible, to totally rernove without damaging the -~
lens.
15 ~ Previous hard and soft contact lens cleanlng solutions have used a variety of water soluble clean~ing agents, ;n addition to water soluble hydrating polymers in sterile~homogenous aqueous solution.
Other cleaning agents~have employed thixotropic synthetic water soluble polymers and thixotropic synthetic clays with detergents to give stiff ~ .
20 gels for the cleaning of hard contact lenses. ~ -~- Abrasive materials have not been used in contact lens cleaning solutions heretofore perhaps because such abrasives would be con-sidered to scratch the surface of the plast;c contact lens, thus leading to a reduction in optical clarity as well as enhanced eye irritation.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a contact lens cleaning material which consists essentially of a surface active agent, an inorganic abrasive and a suspending vehicle which material is highly useful as a cleaner enabling superior cleaning of silicone-containing ~ ,3 1 plastic contact lenses while also useful as a cleaner and/or cleaner-polisher for other contact lens materials~
It is still another object of this invention to provide a method of cleanjng of ophthalmlc contact lens which method comprises applying a cleaning solution containing an abrasive to a surface of the lens and abrading said surface to remove unwanted surface deposits if present without changing the power of the contact lens.
According to the invention, a contact lens cleaning material consists essentially of a surface active agent, an inorganic abrasive and a suspending vehicle such as water or an organic liquid. Means are provided to maintain the surface active agent and abrasive in substantially uniform suspension so that the solution is capable of cleaning a contact lens without adversely affecting the lens. The materi~l is preferably a liquid solution but can be in a paste form.
The cleaner can have a polishing action as where the abrasive materials ~re increased. Preferably the abrasive is in a small particle size range so as not to scratch the lens when used.
According to the method of this invention an ophthalmic contact lens is cleaned by abrading the surface of the lens in the presence of a cleaning solution con~aining an abrasive, a surface active agent, a liquid vehicle and a suspending agent. The cleaning solution is applied and the surface of the lens abraded to remove unwanted sur face deposits ~f present without changing the power of the contact lens. ~y increasing the abrasive, and applying substantial pressure over a longer time period, the material can be used as a polish although it is preferred to use it as a cleaner polisher.
It is a feature of this invention that there is multifold enhance-ment of the cleaning effectiveness of certain surface active agents increasing the friction produced as the surface active agent is rub-bed over the plastic surfaces. This is accomplished by the intro-duction into the surface active agent solution of solid abrasive particles the size and concentration of which can be varied accord-ing to the function desired for the Formulation. The particle size normally utilized is comparable to, or smaller than, the abrasive l used to polish lens surfaces during manufacture as is conventionally known. The particles remain uniformly suspended in the surface active agent solution without settling since settling could vary the effectiveness of the cleaner,and without aggregating which could cause scratches on the lens surface.
It is another feature of this invention that the suspending agent for the abrasive particles is such that the overall suspension ls stable substantially indefinitely. The cleaning solution may contain sterili7ing and buffering agents as well as a fragrance.
In certain cases it may be possible to utilize a surfactant for both sus-pending the abrasive particles and providing cleaning action. However it is more common to use a high concentrat10n of a water soluble salt or an organic polymer to act as a suspending agent.
Although the cleaning solutions described in this application are especially useful for cleaning and/or cleaning and polishing hard, gas permeable contact lenses containing siloxane, they are also use-ful for contact lenses fabricated from polymethyl meth~crylate,silicones and cellulose acetate butyrate as well as other plastics and other materials used for ophthalmic contact lenses.
DESCRIPTION OF PREFERRED EMBODIME~ITS
-The preferred formulation of the novel contact lens cleaning ~ -solution of this invention utilizes a surface active agent with an abrasive for ccmbined chemical and mechanical cleaning action and a suspending agent for the abrasive such that a stable suspension is ~ormed, in an aqueous solution.
The preferred surface act;ve agents are detergents or sur-factants such as anonic sulfates conforming to the following general structure:
Cn Yn+1 (~H2CH2o)x S03 R
where x varies from O to lO
n varies from 8 to 20 R is Na , K , NH4 ~aMg , HN (CH2CH20H)3 Examples of such detergents include:
sodium lauryl sulfate 1 sodium cetyl sulfate sodium octyl sulfate sodium tridecyl sulfate sodium oleyl sulfate sodium tridecyl ether sulfate triethanolamine lauryl sulfate ammonium lauryl ether sulfate sodium lauryl ether sulfate magnesium lauryl sulfate The abrasive compound or compounds are water-insoluble inor-ganic compounds employed for their abrasive characteristics.
The abrasive materi~al is a hard, tough substance containing many sharp projecting cutting edges or points and ;n ordinary use is used for grindi-ng, smoothing and polishing. Such abrasives include various types of silica, alumina, manganese oxides, zirconium oxides and carbonates. It is preferred to employ abrasives with an average partlcle size of 10 microns or less.
Such abrasives could be chosen from:
Silicas 2Q Aluminas ; Kaolin Calcium carbonate Zirconium oxide The suspending agent or agents in this composition must pro-~25 vide a stable suspens;on of the abrasive in the c1eaning solution.
Such suspension could be achieved by increasing the viscosity of the aqueous solution~through the addition of soluble salts or hydrophilic polymers or by the addition of water soluble neutral or i-onic polymers which can interact with the surface of one or more inorganic abrasive particles, thus preventing or hindering pre-cipitation from occurring.
Such suspending agents can be one or more of the ~ollowlng:
alkali metal halides (hlgh concentration) alkaline earth metal salts (moderate concentration) polyvlnyl alcohol .. .

, .

:

- ~5;~
..

1 polyacrylamide hydrolyzed polyacrylamide polyacrylic acid xanthan gum hydroxyethyl cellulose carboxymethyl cellulose cellulose sul~ate : : methyl cellulos~e methyl:hydroxyethyl cellulose ~ : 10 methyt hydroxypropyl cellulose : ~ : poly-N-vinylpyrrblidone guar gum : carboxymethyl guar gum hydroxyethyl gua~r::gum ~15 hydrolyzed polyacrylonitrile starch hydrolyzed~palyacrylonitrile 2-acrylamido-

2-methylpropane sulfonate starch clays such as ben:tonite, montorillonite and hectorite neutral, cationic and:anionic detergents ;;~ : partially acetylated cellulose : gelatin polyethylene glycol and oxide :K-carageenan Buffering agents can be used and are preferably those commonly employed in the art within a pH range of 5 to 8, and usually between : 7 and 8. Such buffers include boric acid, sodium borate, phos-phor~c acid, disodium phosphate and sodium bicarbonate.
The use of salts as suspending agents generally renders the cleaning solution sterile; however, in cases where sterility must be imparted, ant;-microbial compounds can be used. Such compounds include chlorhexidine, benzalkonium chloride, phenyl mercuric acetate, phenyethyl alcohol, methyl or propyl paraben, cetyl pyridinium chloride, thimerosal and the like, in possible coniunction with EDTA.

1 Fragrances ~uch as wintergreen or peppermint can be used if desired.
In the simplest fashion, the contact lens is cleaned by im-mersing the lens in the cleaning solution or spraying the lens and by providing agitation of the solution such as by rubbing, shaking, or wiping of the cleaning solution on the lens surface. The lens ;s then rinsed with water and inserted directly into the eye or it is placed in a soaking and/or wetting solution prior to insertion.
Specific examples of this invention are given below but are not meant in any way to li~mit this invention.
EXAMPLE I
Formulation:
Sodium tridecyl ether sulfate (30%) 80 gms dist~lled water 160 gms sodium chlorlde 20 gms silica (9 micron average3 24 gms The surfactant is mixed with the water then the sodium chloride is added and mixing continued until a thick solution is obtained.
The silica powder is added to the solution and blended thoroughly until a smooth viscous~suspension is achieved. No settling of the abrasive was noted~after eight months of shelf storage.

; EXAMPLE II
Formulation:
Sodium tridecyl ether sulfate (30%) 133 gms distilled water 267 gms sodium chloride 30 gms silica (9 micron average) 8 gms Preparation was identtcal to that described in Example I.
EXAMPLE III
Formulation:
Sodium tr;decyl ether sulfate (30%) 133 gms distilled water 267 gms sodium chloride 30 gms silica (9 micron average) 1 gm Preparation was identical to that described in Example I.

~7-Formulation: A B C
sodium tridecyl ether sulfate (30%) 133 gms 133 gms 133 gms distilled water 267 267 267 sodium chloride 30 30 silica (9 micron average) 12 - -Cleaning solutions were prepared in the same manner as that described in Example I.
; Contact lenses having a high silicone content characteris~ically ~;~ 10 develop a tenacious waxy surface deposit that is difficult and often imposslble to remove with solvents, surfactants or polishing without damaging the surfaces of the lenses. Such deposits are best visu-alized by studying a rinsed and dried lens against~a black background (with a self-illuminating binccular microscope and can be quantitated by grading l to 4 according to surface area and thickness (opaque-ness), a rating of 4 indicating~a severe deposit. Sixty pairs of lenses having roughly symmetrical surface deposits of grade 2 or ; greater were subjected to the followlng procedure: one lens of each ,oalr was c~leaned manually uslng formulation "A". The companion lenses were broken up into three groups of twenty. One group was cleaned manually wi~th formulation "B", the second group with formu-lation "C" and the final group with various commercial contact lens cleaners (solutions and gels).~ It was found that formulation "B"
and "C" were equally effective but that formulation "A" was manifold more effecbive~than ~brmulation "B" or "C" ;n al1 cases. In fact, formulation "B" and "C" were relatively ineffective in removing grade 4 deposits~whereas this invention (formulation "A") was very effect;ve in all cases. Finally, none of the commercial contact lens cleaners was more ef~ective than formulations "B" and "C" and many were less effective. This example points out the utility of a suspended abrasive in providing improved cleaning action over simple s-urfactant solutions.

' ' ~5~3 , The cleaning solution described in Example III was provided to a number of patients at the commencement of their wearing newly fabricated hard contact lenses (conta;ning silicone). They were in-structed to clean their lenses nightly with this formulation. Theirlenses were inspected after 6 months and compa~ed with the lenses of a similar group of subjects who cleaned their lenses nightly with a variety of commercial contact lens cleaners. The lenses of patients using the cleaning solution of Example III were significantly Freer of surface deposits and were, as a rule, more comfortable.
The cleaning solution described in Example III was also given to a small group of conventional polymethyl methacrylate contact lens wearers who complained of blurred vision as the result of the develop-ment of "dry" spots on the front surfàce of their lenses that recurred when cleaned nightly~by~a variety of commercial contact lens cleaners, solvents, or polishing. In all cases, the nightly use of this inven-tion eliminated the hydrophobic or dry areas and the subjects' vision remained clear during their daily wearing schedule.

EXAMPLE VI
The surfaces of all hard contact lenses eventually become scratched. Conventional polishes remove shallow scratches and smooth the ridges adjacent to deeper scratches thereby improving the com-fort and optics of the lenses. However, many of these scratched contact lenses also have signi~icant surface deposits which are not removed by polishing. In fact, polishing contact iens surfaces that have heavy deposits may simply spread and redistribute the de-posits thereby reduclng the surface wettability even Further. The cleaning solution described in Example ~ combines the function bf a cleaner (to remove surface film) and a polish (to remove surface scratches) and it is far more effectTve than using a cleaner and a polish in separate operations. A cleaner!polish such as described in Example I is then particularly useful to the practitioner for restoring the optics and wettability of hard contact lenses.

Formulation:
Sodium tridecyl ether sulfate (30)100 gms 4% HEC solution 200 gms aluminum oxide (0.06 micron) 10 gms Dissolve 4% by weight hydroxy ethyl cellulose (cellos;ze QP-40, a product of Union Carbide Corp. of New York, New York) in distilled wa~er. The surfactant is then added and the solution mixed well.
The aluminum oxide is then blended thoroughly into this solution until a smooth viscous solution is achieved.
This Example demonstrates the use of a water soluble polymer to suspend the abrasive powder.

EXAMPLE VIII
Formulation:
sodium ~ridecyl ether sulfate (30%)100 gms distilled water 200 gms hydrite lO (kaolin clay) 30 gms : 20 sodium chloride 25 gms The preparation was identical to that described in Example I, ; This Example demonstrates the use of kaolin, a material which imparts a "milder" abrasive action when compared to silica or alumina.
;~ ~ 25 ~ ~ ~
EXAMPLE I~X
Formulation:
sodium tridecyl ether sulfate (30Y)100 gms gl,ycerin 200 gms silica (9 micron average~ 3 gms The surfactant was dissolved in glycerin then the silica was hlended into this solution.
This Example demonstrates the use of an organic liquid in con-junction with the surfactant to achieve a transparent cleaning solution.

- lo -Formulation:
A B C
sodium tridecylether sulfate (30%) 100 gms 125 gms ammonium lauryl ether sulfate (27%) - - lOOgms silica (4 micron average) 30 gms - 35 gms hydrite 10 (kaolin clay) - 75 gms The abrasive powder is mixed with the surfactant, under moderate shear, to for~ a stable~paste.
This Example demonstrates the use of the surfactant as a supsend-ing agent for the abrasive to form a paste cleaner.

EXAMPLE XI
:::
~ 1:5 Formulation:
: :
triethanolamine lauryl sulfate (40%) 75 gms distilled water 520 gms xanthan gum 10 gms silica (4 micron average) 18 gms Dissol~ve xanthan gum in distilled watèr. The surfactant is then added and the solution mixed~well. The silica is then blended ::
thoroughly into this solution until a smooth viscous solution is achieved.
This Example ~demonstrates the use of a water soluble polymer to suspend the abrasive powder.

:

1 While specific Examples o~ the invention have been shown and described, many variations are possible. When the cleaning solutions of this invention are used only as cleanersg the surface active agents preferably comprise from 1 to 30% by weight of the materlal, the abra-sive particles from 0.1 to 5% by welght and the carrier vehicle such aswater from 98.9 to 69.9% by weight ~ith a suspending agent based on 100 parts of the above being from 5 to 25 parts when inorganic salts are used and from 1 to 10 parts when polymers are used~ The same suspend-ing agents are used when the cleaning solution is used to act as a cleaner-polisher but here the surfactant amount may range from 1 to 30% by weight and the abrasive amount is raised to from 5 to 25% by weight while the water or other suspending vehicle is used to bring the material to 100%. When a paste rather than a free flowing liquid is desired, the surfactant can carry from 15 to 40% by weight of the surface active agent, from 20 to 50% by weight of an abrasive and the balance water or other solvent which is water soluble. Of course, one or more surface active agents, abrasives or solvents can be used in a single composition if desired.
The particle sizes oF the abrasives can vary greatly but they are preferably that standardly used for lens polishing in the ophthalmic industry. P~rticle sizes of silica for example with an av~rage of 9 microns and a range of from 1 to 20 microns with an upper limit of 30 microns in the form of Syloid 63, a trademarked product of Davison Chemlcal l~. R. Grace Co. of Baltimore, Mary1and can be used.
Other size ranges are possible.
In all cases, the surface active agent in the form of a de-ter~ent or surfactant acts along with the abrasive to combine the best qualities of both wh~ch can result in synergistic action to clean contact lenses in accordance ~ith the method of this invention.
While surface active agents have been specifically noted in this application, other surface active agents can be used. Such agents associate in water to form a colloldal particle known as a micelle. The structure is such that the hydrophobic hydrocarbon chains are inside remote from the solvent and the polar head groups are on the surface of the partlcle. The presence of micelles in an ,;

_12_ 1 aqueous solution endows it with minute regions which are predominantly hydrophobicin nature. This allows for high solubility in water and good wetting of the matenials.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. 1. A method of cleaning an ophthalmic contact lens, said method comprising, applying a cleaning solution containing an abrasive and a surface active agent to a surface of said lens and abrading said surface to remove unwanted surface deposits if present without changing the power of said contact lens, said cleaning solution consisting essentially of from about 1 to about 30% by weight surface active agent and a small amount of adhesive in an amount of from about 0.1% by weight to an amount and particle size low enough to give a cleaning action without changing the power of said lens.

2. A method in accordance with the method of claim 1 wherein said cleaning solution further comprises a suspending vehicle and means to maintain said surface active agent and abrasive in substantially uniform suspension so that said solution is capable of cleaning a contact lens without adversely affecting said lens.

3. A method in accordance with the method of claim 2 wherein said suspending vehicle is water and said suspending means is selected from the class consisting of inorganic salts and hydrophilic polymers, said suspending vehicle being in an amount up to 100%.

4. A contact lens cleaning material consisting essentially of, a surface active agent in an amount of from about 1% to about 30%
weight, an inorganic abrasive in an amount of from about 0.1% to an amount and particle size low enough to give a cleaning action without changing the power of said lens, an aqueous suspending vehicle, and means to maintain said surface active agent and abrasive in substantially uniform suspension so that said solution is capable of cleaning a contact lens without adversely affecting said lens.

5. A contact lens cleaning material in accordance with claim 4 wherein said solution is in liquid form with said water being in an amount up to 100%.

6. A contact lens cleaning material in accordance with claim 4 wherein said material is in a semi-viscous paste form.

7. A contact lens cleaning material in accordance with claim 4 wherein said abrasive is silica.

8. A contact lens cleaning material in accordance with claim 4 wherein said surfactant is in an amount of from 1 to 30% by weight, said abrasive is in an amount of from 0.1 to 25% by weight and said vehicle is water in an amount up to 100% with said means being a suspending agent selected from the class consisting essentially of inorganic salts and hydrophilic polymers.

9. A contact lens cleaning material in accordance with claim 4 wherein said surfactant is in an amount of from 15 to 40% by weight, said abrasive is silica in an amount of from 20 to 50% by weight and said vehicle is water in an amount up to 100% with said means being a suspending agent selected from the class consisting essentially of inorganic salts and hydrophilic polymers.

10. A contact lens cleaning material in accordance with claim 4 wherein said abrasive is selected from the class consisting essential-ly of silica, alumina, kaolin, calcium carbonate, zirconium oxide and mixtures thereof.

11. A cleaning material in accordance with claim 4 wherein said surface active agent has the following general formula:

Cn H2n+1O (CH2CH2O)x SO3-R+

where x varies from 0 to 10 n varies from 8 to 20 R+ is Na+, K+, NH+ ?Mg++,HN+(CH2CH2OH)3.

12. A method in accordance with claim 3 wherein said abrasive is silica.