SE447030B - PROCEDURE AND WATER DISPOSAL FOR TREATMENT OF CONTACT LENSES - Google Patents

Description

One of the problems associated with this type of lens is the formation, after some time, of insoluble inorganic coatings on the lenses. These coatings are primarily thought to be based on calcium, e.g. calcium phosphate or calcium carbonate, but may also contain other inorganic material and accompanying organic material, e.g. protein. The presence of these insoluble inorganic coatings is a common reason why the lenses are not tolerated and reduced visual acuity.

The present invention provides a method and composition for treating contact lenses, especially silicone and hydrophilic plastic contact lenses, to remove inorganic coatings and to prevent the formation of inorganic coatings on the lenses.

The method comprises contacting a contact lens with an aqueous solution containing from 0.01 to 20% by weight of a separating agent constituting hexametaphosphate, glyconic acid or salts thereof or calcium borogluconate and heating the solution in contact with the lens for a period of time sufficient. to remove inorganic coatings and to prevent the formation of inorganic coatings on the lens.

The aqueous solution is a preserved saline solution and may further contain an agent for sterilizing the lenses.

The release agents that can be used according to the present agents are typical calcium release agents such as e.g. hexametaphosphates, glyconic acid and its salts. A preferred hexametaphosphate is sodium hexametaphosphate. Salts of glyconic acid that can be used include common inorganic salts such as e.g. sodium, potassium and calcium salts, as well as salts of eg calcium boroglyconate. All the above-mentioned compounds are well known in the art, they are commercially available and have hitherto been used in industrial processes such as e.g. tanning of leather, dyeing, in laundries and textile preparation, water softening, metal plating, pickling of fabrics and as aids in photographic procedures. Thus, it was surprising to find that periodic treatments of the contact lenses with aqueous solutions containing these compounds prevent the formation of inorganic coatings on the lenses without damaging the lens or the eye of persons using the lens.

The amount of separating agent that can be used in the present invention is between 0.01 and 20% by weight and preferably between 0.01 and about 5% by weight.

The release agent may be manufactured in a number of suitable forms for use in the treatment described herein. For example. the separating agent can be distributed in the form of a dry unit dose from e.g. a tablet, which is dissolved in water before use. The separating agent may also form part of a buffered or non-buffered sterile, isotonic saline solution which has been used to store the lenses in The separating agent described herein may also be incorporated into cold disinfection systems containing means for preserving the lenses and disinfecting them.

The present invention can be further described and illustrated with reference to the following examples. However, the following examples are for illustrative purposes only and the invention is not to be construed as limited to any of the particular compounds or formulations or conditions described herein. Unless otherwise stated, the percentages are expressed in% by weight.

EXAMPLE 1 A hydrophilic contact lens (polymacon) which had been worn for about 2 years was examined and found to have a highly visible surface coating. The lens was cleaned with an enzymatic cleaner for 24 hours. with little effect. Thereafter, the lens was made germ-free (heating to 1000 for 15 minutes) for 2 cycles in a 20% solution of sodium hexametaphosphate in water. Some of the film-forming material was still present on the lens, but after further treatment with the enzymatic cleaner, the lens was released from the film coating. This indicates that the coating consisted of both inorganic material and proteinaceous material, since the enzymatic cleaner quickly, usually within 4 hours, and completely removes protein coatings from hydrophilic lenses.

EXAMPLE II A hydrophilic, single-use, lens with an inorganic film coating was cleaned with an enzymatic contact lens cleaner for 24 hours. A highly visible film remained on the lens. The lens was divided into two halves and one half was made bacteria-free (heating to 800 for 20 minutes) for 4 cycles in an aqueous solution containing 0.2% sodium hexametaphosphate, 0.1 l boric acid, 0.01% disodium edetate, , 85% sodium chloride preserved with 0.001% thimerosal at pH 7.4. After another 3 hours. treatment with the enzyme detergent solution, the lens was free of visible coatings. The other half of the lens, which was similarly treated, except that the bactericidal cycle was excluded, still had the strong inorganic film coating.

EXAMPLE III A hydrophilic, single-use, lens with an inorganic film coating was cleaned for 4 hours. with the enzymatic detergent. No change in occupancy was noted. Thereafter, it was made germ-free (heated to 8096 for 20 minutes) alternately in an aqueous solution containing 0.2% sodium gluconate, 0.1 l of boric acid. 0.01% disodium edetate, 0.85% sodium chloride preserved with 0.00l% thimerosal at pH /, 4 (Compound No. 5945X) for 20 minutes. and was cleaned for several hours with the enzymatic detergent until three of these cycles were completed. Microphotographs taken over the same area of the lens at each step show an almost complete g POOR QUALITY.

Claims (12)

25 50 35- 40 447 050 4 removal of the strong inorganic coating after three cycles. No visible coatings 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 No. 1 was an aqueous solution containing 0.2% polysorbate 80, 1.92% propylene glycol, 0.033% alkyltriethanolammonium chloride, 0.05% sodium bicarbonate, 0.002% sodium chloride, 0.002? % thimerosal and test solution # 2 contained the same ingredients plus 0.0 I An examination of the test lenses after 80 cycles revealed coatings of calcium cartonate on the lenses treated with test solution # 1. There was% sodium hexametaphosphate. no coatings of calcium carbonate on the lenses treated with Test Solution No. 2, which shows that the addition of sodium hexametaphosphate prevented a coating of insoluble calcium salt on the hydrophilic contact lenses. PATENT REQUIREMENTS A method of treating contact lenses to remove inorganic coatings and to prevent the formation of inorganic coatings on the lenses, characterized in that a contact lens is allowed to come into contact with an aqueous solution containing from 0.01 to 20% by weight. % of a separating agent, consisting of hexametaphosphate, glyconic acid or salts thereof or calcium borogluconate and that the solution is heated in contact with the lens for a period of time sufficient to remove inorganic coatings and to prevent the formation of inorganic coatings on the lens. Process according to Claim 1, characterized in that the aqueous solution is a preserved saline solution. 3. A method according to claim 1 or 2, characterized in that the contact lens is a silicone contact lens or a hydrophilic, soft contact lens. 4. A method according to claim 1, 2 or 3, characterized in that the effective amount of the separating agent is present in an amount of between 0.1 - 1% by weight. Process according to any one of the preceding claims, characterized in that the separating agent is a salt of glyconic acid, constituting sodium, potassium or calcium. I I _ Process according to one of the preceding claims, characterized in that the separating agent is sodium hexametaphosphate. px »._ ('xr 30 35 ih] 447 050 5 Aqueous solution, characterized in that it contains between 0.01 to 20% by weight of a separating agent, constituting hexametaphosphate, glycune acid or its salts or calcium boroglucanate. 8. A solution according to claim 7, characterized in that it additionally contains a preservative. Salary according to Claim 7 or 8, characterized in that the solution is isotonic. 10. A solution according to claim 7 or 8, characterized in that the solution contains 0.85% by weight of ~ ~ sodium chloride. Solution according to any one of claims 7-10, characterized in that the separating agent is sodium hexametaphosphate. Solution according to any one of claims 7-11, characterized in that it further contains an agent for sterilizing the lens. POOR QUALITY