GB2040492A

GB2040492A - Method and Composition for Treating Contact Lenses

Info

Publication number: GB2040492A
Application number: GB8000105A
Authority: GB
Original assignee: Allergan Pharmaceuticals Inc
Current assignee: Allergan Inc
Priority date: 1979-01-15
Filing date: 1980-01-02
Publication date: 1980-08-28
Also published as: ZA8054B; DE3000742A1; CA1136841A; IE49362B1; JPS5595926A; MX154425A; BR8000199A; ES487679A0; FR2446499B1; JPH0337165B2; SE8000157L; AU533669B2; IE800070L; SE447030B; DE3000742C2; GB2040492B; ES8103394A1; NL8000201A; FR2446499A1; IT1129653B

Abstract

The invention relates generally to a method and composition for the treatment of contact lenses, especially silicone and hydrophilic plastic contact lenses, to remove inorganic deposits and to prevent the formation of inorganic deposits on the lenses. One of the problems connected with these types of lenses is the formation, over a period of time, of insoluble inorganic deposits on the lenses. These deposits are thought to be primarily calcium based, e.g., calcium phosphate and calcium carbonate, but may also contain other inorganic materials and associated organic materials, e.g., protein. The presence of these insoluble inorganic deposits is a common cause of lens intolerance and decreased visual acuity. The method comprises contacting a contact lens with an aqueous solution containing an effective amount of a polymetaphosphate, gluconic acid or salts thereof as sequestering agent for a period of time sufficient to remove existing inorganic deposits and to prevent formation of inorganic deposits. The solution may be a preserved saline solution containing 0.01-20% by weight of the sequestering agent.

Description

SPECIFICATION Method and Composition for Treating Contact Lenses Field of the Invention The invention relates generally to a method and composition for the treatment of contact lenses to remove inorganic deposits and to prevent the formation of inorganic deposits on the lenses.

Background of the Prior Art Soft contact lenses may be divided into two broad categories, namely hydrophilic and hydrophobic lenses. Hydrophobic contact lenses are usually based on elastic and flexible silicone rubber (polysiloxane), and are generally made from cross-linked dimethyl polysiloxane.

A typical preparation of a silicone contact lens is disclosed in U.S. Patent No. 3,228,741, which is hereby incorporated by reference and comprises forming a mixture of a suitable polymerization catalyst, up to 40% of a silica filler, and the silcone polymer. Said mixture is then molded and cured by heating to cross-link the polysiloxane and to produce a finished clear lens.

Increased consumer acceptance of flexible silicone rubber lenses has created a need for a cleaning solution which can be used effectively with such lenses.

Hydrophilic soft contact lenses are hydrated gel lenses which can be prepared by copolymerizing hydrophilic organic monomers containing an olefinic double bond with a small amount of a cross-linking agent which usually contains two polymerizable olefinic double bonds.

These lenses are usually based on polyhydroxylated alkyl methacrylates and contain a polyhydroxylated alkyl methacrylate, such as polyhydroxyethyl methacrylate, cross-linked with, for example, an hydroxyethyl dimethacrylate.

One of the problems connected with these types of lenses is the formation, over a period of time, of insoluble inorganic deposits on the lenses. These deposits are thought to be primarily calcium based, e.g., calcium phosphate and calcium carbonate, but may also contain other inorganic materials and associated organic materials, e.g. protein. The presence of these insoluble inorganic deposits is a common cause of lens intolerance and decreased visual acuity.

Brief Summary of Invention I have now discovered a method and composition for the treatment of contact lenses, and especially silicone and hydrophilic plastic contact lenses, to remove inorganic deposits and to prevent the formation of inorganic deposits on the lenses.

The method comprises contacting a contact lens with an aqueous solution containing an effective amount of a sequestering agent selected from the group consisting of a polymetaphosphate, gluconic acid and salts thereof for a period of time sufficient to remove existing inorganic deposits and to prevent formation of inorganic deposits.

The composition comprises a preserved saline solution containing from about 0.01 to about 20% by weight of a sequestering agent selected from the group consisting of a polymetaphosphate, gluconic acid and salts thereof. The composition may additionally contain an agent for sterilizing the lenses.

Detailed Description of the Invention The sequestering agents which may be used in this invention are typically calcium sequestering agents such as, for example, polymetaphosphates, gluconic acid and salts thereof. Suitable polymetaphosphates include sodium polymetaphosphate and preferably sodium hexametaphosphate. Salts of gluconic acid which may be used include common inorganic salts such as the sodium, potassium and calcium salts as well as other salts such as, for example, calcium borogluconate.The preferred sequestering agent is sodium hexametaphosphate. Ali of the aforementioned compounds are well-known in the art, are commercially available, and have been used heretofore for industrial processes such as, for example, leather tanning, dying, laundry and textile processing, water softening, metal plating, mordanting fabrics and as photographic processing aids. Therefore, it was surprising to discover that periodic treatment of contact lenses with aqueous solutions of these compounds prevent the formation of inorganic deposits on the lenses without harming the lens or the eye of the user of the lens.

The amount of sequestering agent which may be used in the present invention ranges between about 0.01 and about 20% and preferably about 0.1 to about 5% by weight.

The sequestering agents may be manufactured in a number of convenient forms for use in the treatment described herein. For example, the sequestering agent could be delivered in the form of a dry, unit dosage from such as a tablet which would be dissolved in water prior to use. The sequestering agent could also form a part of a buffered or unbuffered preserved or unpreserved sterile, isotonic saline solution used to store the lenses. The sequestering agents described herein may also be incorporated into cold disinfecting systems containing lens preservatives and disinfectants.

The present invention may be further described and illustrated with reference to the following examples. It is to be understood, however, that the following examples are for the purpose of illustration and the invention is not to be regarded as limited to any of the specific compounds or formulations or conditions recited therein. Unless otherwise stated, percents are by weight.

Example I A hydrophilic contact lens (Polymacon) which has been worn for approximately two (2) years was examined and found to have a heavy visible film deposit. The lens was cleaned with an enzymatic cleaner for 24 hours with little effect.

The lens was then asepticized (heated to 1000C for 15 minutes) for two (2) cycles in a 20% solution of sodium hexametaphosphate in water.

The lens still retained some of the film-like material, but after one further treatment with the enzymatic cleaner, the lens was found to be free of film. This indicates that the deposit consisted of both inorganic and protein materials since the enzymatic cleaner rapidly (usually within four hours) and completely removes protein films from hydrophilic lenses.

Example II A hydrophilic human worn lens with an inorganic film was cleaned with an enzymatic contact lens cleaner for 24 hours. A heavy visible film remained on the lens. The lents was cut in half and one-half was asepticized (heated to 800C for 20 minutes) for four cycles in an aqueous solution containing 0.2% sodium hexametaphosphate, 0.1% boric acid, 0.01% disodium edetate, 0.85% sodium chloride preserved with 0.001% thimerosal at pH 7.4.

Following another three hour treatment with the enzyme cleaner solution, the lens was free of visible deposits. The other half of the lens treated in a similar manner, except that the aseptor cycle was omitted, still retained its heavy inorganic film.

Example III A hydrophilic human worn lens with an inorganic film was cleaned for four hours with the enzyme cleaner. No change in the film was noted.

It was then alternately asepticized (heated to 800C for 20 minutes) in an aqueous solution containing 0.2% sodium gluconate, 0.1% boric acid, 0.01% disodium edetate, 0.85% sodium chloride preserved with 0.0010/0 thimerosal at pH 7.4 (Formula No. 5945X) for 20 minutes and cleaned for several hours with the enzyme cleaner until three of these cycles had been completed.

Photomicrographs taken of the same area of the lens at each step show almost complete removal of the heavy inorganic deposit after the three cycles. No visible deposits remained.

Example IV Hydrophilic contact lenses were soaked in a 1% aqueous solution of calcium chloride for 30 minutes and then placed in test solutions for 23.5 hours. This was repeated for 80 cycles. Test Solution 1 was an aqueous solution containing 0.2% polysorbate 80, 1.92% propylene glycol, 0.033% alkyl triethanol ammonium chloride, 0.05% sodium bicarbonate, 0.002% sodium chloride, 0.0023% thimerosal, and Test Solution 2 contained the same ingredients plus 0.05% sodium hexametaphosphate.

Examination of the test lenses after 80 cycles revealed calcium carbonate deposits on the lenses treated with Test Solution 1. There were no deposits of calcium carbonate on lenses treated with Test Solution 2 demonstrating that the addition of sodium hexametaphosphate prevented the deposition of the insoluble calcium salts on hydrophilic contact lenses.

Claims

1. A method for the treatment of contact lenses to remove inorganic deposits and to prevent the formation of inorganic deposits on the lenses comprising contacting a contact lens with an aqueous solution containing an effective amount of a sequestering agent selected from the group consisting of a polymetaphosphate, gluconic acid and salts thereof for a period of time sufficient to remove inorganic deposits and to prevent formation of inorganic deposits on the lens.

2. The method as claimed in Claim 1, wherein the contact lens is selected from the group consisting of a silicone contact lens and a hydrophilic soft contact lens.

3. The method as claimed in Claim 1, wherein an effective amount of sequestering agent ranges between about 0.01 and about 20% by weight.

4. The method as claimed in Claim 3, wherein an effective amount of sequestering agent ranges between about 0.1 to about 1% by weight.

5. The method as claimed in Claim 1, wherein the aqeueous solution is a preserved saline solution.

6. The method as claimed in Claim 1, wherein the aqueous solution additionally contains an agent for sterilizing the lens.

7. The method as claimed in Claim 1, wherein the sequestering agent is sodium hexametaphosphate.

8. The method as claimed in Claim 1, wherein the sequestering agent is a salt of gluconic acid selected from the group consisting of sodium, potassium and calcium.

9. The method as claimed in Claim 1, wherein the sequestering agent is calcium borogluconate.

1 0. A method for the prophylactic treatment of contact lenses to prevent the formation of inorganic deposits on the lenses comprising periodially contacting a contact lens with an aqueous solution containing an effective amount of a sequestering agent selected from the group consisting of a polymetaphosphate, gluconic acid and salts thereof for a period of time sufficient to prevent formation of inorganic deposits on the lens.

11. A method for the treatment of contact lenses to remove inorganic deposits and to prevent the formation of inorganic deposits on the lenses comprising preparing an aqueous solution by combining with water, a solid, unit dosage form of a sequestering agent selected from the group consisting of a polymetaphosphate, gluconic acid and salts thereof and contacting a contact lens having inorganic deposits with the resulting aqueous solution for a period of time sufficient to remove the inorganic deposits on the lens.

12. A preserved saline solution containing from about 0.01 to about 20% by weight of a sequestering agent selected from the group consisting of a polymetaphosphate, gluconic acid and salts thereof.

1 3. The composition of Claim 1 2 wherein the sequestering agent is sodium hexametaphosphate.

14. The composition of Claim 12 additionally containing an agent for sterilizing for lens.

1 5. A method for the treatment of contact lenses as claimed in any one of claims 1 to 9, substantially as hereinbefore described.

1 6. A method for the prophylactic treatment of contact lenses as claimed in claim 10, substantially as hereinbefore described.

1 7. A method for the treatment of contact lenses as claimed in claim 11, substantially as hereinbefore described.

1 8. A preserved saline solution as claimed in any one of claims 12 to 14, substantially as hereinbefore described.