NL8000201A - METHOD FOR REMOVING INORGANIC PRECIPES ON CONTACT LENSES AND METHOD FOR PREPARING A SOLUTION TO BE USED - Google Patents

Description

-1- 21107 / Vk / axle

Applicant: Allergan Pharmaceuticals, Inc., Irvine, California, United States

States of America.

Short designation: Method for removing inorganic deposits on contact lenses and method for preparing a solution to be used here.

The invention relates to a method for removing inorganic deposits on contact lenses and preventing inorganic deposits on lenses by immersing the contact lenses in an aqueous solution. The invention further relates to a method for preparing an aqueous solution to be used herein.

Soft contact lenses can be divided into two main categories, namely hydrophilic and hydrophobic lenses. Hydrophobic contact lenses 1- * are usually based on elastic and flexible silicone rubbers (polysiloxane) and are generally made from cross-linked dimethyl "polysiloxane.

An example of a method of manufacturing a silicone contact lens is disclosed in U.S. Pat. No. 3,228,741, which is hereby considered to be weld-in and consists of forming a mixture of a suitable polymerization catalyst up to 40% of a silica Fillers the silicone polymer. This mixture is then molded and cured by heating it to crosslink the polysiloxane to obtain a final clear lens. An increasing demand for flexible sylicon. rubber lenses have necessitated a cleaning agent that can be used to effectively clean such lenses.

Hydrophilic soft contact lenses are hydrated gel lenses J which can be prepared by copolymerizing hydrophilic organic monomers with an olefinic double bond and a small amount of a crosslinker usually containing two polymerizable olefinic double bonds. These lenses are usually based on polyhydroxylated alkyl methaerylates and contain a polyhydroxy-

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Taught alkyl methacrylate such as polyhydroxyethyl methacrylate, which is cross-linked, for example, a hydroxyethyl limethacrylate.

One of the problems associated with these types of lenses is the formation of insoluble inorganic precipitate at 0000201 over a period of time>

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-2- 21107 / Vk / as the lenses. These deposits probably consist mainly of calcium compounds such as calcium phosphate. and calcium carbonate, but may also contain other inorganic substances and related organic substances such as proteins. The presence of these insoluble inorganic precipitates usually causes the lens to not be tolerated and reduces vision.

The investigations made have shown a method and composition for treating contact lenses, in particular silicon and hydrophilic plastic contact lenses, in which the inorganic precipitate can be removed and inorganic precipitate can be prevented from forming on the lenses.

The method of the invention is characterized in that the aqueous solution contains an effective amount of a sequester agent selected from a group consisting of polymetaphosphate, gluconic acid 15 and its salts and is immersed for a sufficient period of time to remove inorganic precipitate and to prevent inorganic deposits from forming on the lens.

The composition contains a pretreated saline with about 0.01 to about 20 weight percent of a sequester agent selected from a group consisting of polymetaphosphate, gluconic acid and salts thereof. The composition may further contain a lens sterilizing agent.

The sequestering agents which can be used according to the invention are typical calcium sequestering agents such as, for example, poly-metaphosphates, gluconic acid and salts thereof. Suitable polymetaphosphates include sodium polymetaphosphate and preferably sodium hexametaphosphate. Gluconic acid salts that can be used include inorganic salts such as sodium, potassium and calcium salts, as well as other salts such as, for example, calcium boron gluconate. The preferred sequester agents are sodium hexametaphosphate. All of the above compounds are known compounds in the art and are commercially available and have hitherto been used for industrial processes such as, for example, leather tanning, dyes, detergents and textile processing products, water softeners, to coat metals 35, etchant and as auxiliaries in photography. It is therefore surprising that it has been found that periodic treatment of contact lenses with an aqueous solution of these compounds prevents the formation of inorganic deposits on the lenses without this 8000201 -3- 21107 / Vk / as agent having an adverse effect on the lens or on the eye of the user of the lens.

The amount of the sequestrant that can be used in accordance with the invention is between about 0.01 and about 20%, and preferably between about 0.1 and about 5 percent by weight.

The sequester agents can be prepared in a number of ways to be used in the treatment as indicated above.

For example, the sequestering agent can be fed in the form of a dry unit dosage in the form of a tablet, which is dissolved in water before use. The sequestrant may also form part of a buffered or unbuffered pretreated or non-pretreated sterile isotonic saline used to store the lenses. The sequestering agents described here may also include cold disinfection systems containing disinfectants and lens preservatives.

The invention will be further elucidated by means of the following non-limiting examples. The parts reported are parts by weight and percentages by weight if not the contrary.

/ example I

A hydrophilic contact lens (Polymacon) that has been worn for about two years was examined and found to contain a highly visible film-shaped precipitate. The lens was purified with an enzymatic detergent for 24 hours with only a small influence observed. The lens was then aseptically treated (heated to 100 ° C for 15 minutes) (two cycles) in a 20% solution of sodium hexaraetaphosphate in water. The lens still contained film-form material, but after further treatment with the enzymatic purifying agent, the lens was found to be free of film-form material. This indicates that the precipitate consisted of both inorganic and protein containing material because the enzymatic detergent quickly (usually within four hours) completely removed the protein film from the hydrophilic lens.

example II

A hydrophilic human-worn lens with an inorganic film was purified with an enzymatic contact lens cleaner for 24 hours. A heavy visible film remained on the lens.

The lens was cut half and half treated aseptically by heating it at 80 ° C for 20 minutes. an aqueous solution with 0.2% sodium hexametaphosphate, 0.1% boric acid, 0.01% disodium edetate, 0.85% sodium chloride pretreated with 0.001 "for 4 cycles in 3 C 0 0 2 0 1 -4-21107 / Vk / as thimerosal at pH 7.4 After the lens was again treated with the enzymatic detergent for three hours, the lens was free from visible precipitation 5. The other half of the lens was treated in a similar manner except that the aseptor cycles were omitted another heavy inorganic film remained.

example III

A hydrophilic human behavioral filter with an inorganic film was purified for four hours with an enzymatic detergent. No change in the film was observed. It was then aseptically treated (heated to 80 ° C for 20 minutes) in an aqueous solution containing 0.2% sodium gluconate, 0.1% boric acid, 0.01% disodium edetate, 0.85% sodium chloride pre-treated with 0.001% thimerosal at 15 pH 7.4 (Composition No. 5945X) for 20 minutes and purified with the enzymatic detergent for several hours until three of these cycles were completed. Photomicroscopic examination was performed by taking photomicrographs of the surface of the lens after performing each step showing almost complete removal of the heavy inorganic precipitate after three cycles. No visible deposits were left behind.

example IV

Hydrophilic contact lenses were immersed in a 1% aqueous solution of calcium chloride for 30 minutes and then stored in a test solution 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 substances plus 0.05% sodium hexametaphosphate .

Further examination of the test lenses after 80 cycles indicated that the calcium carbonate deposit on the lenses treated with test solution 1 was present. No precipitation of calcium carbonate was observed on the lenses treated with test solution 2, which showed that the addition of sodium hexametaphosphate prevented the formation of the insoluble calcium salt on hydrophilic contact lenses.

8Q 0 0 2 0 1 -CONCLUSIONS-

Claims (14)

A method for removing inorganic deposits on contact lenses and preventing the formation of inorganic deposits on lenses by immersing the contact lenses in an aqueous solution, characterized in that the aqueous solution contains an effective amount of a sequestrant; selected from a composition consisting of polymetaphosphate, gluconic acid and its salts, is immersed for a sufficient time to remove inorganic deposition deposits and to prevent inorganic precipitate from being deposited on the lens. A method according to claim 1, characterized in that the contact lens is selected from a group consisting of silicone contact lenses and a hydrophilic soft contact lens. 3. A method according to claim 1, characterized in that an effective amount of sequestrant varies from 0.01 to about 20% by weight. A method according to claim 3, characterized in that the effective amount of sequestrant varies from about 0.1 to about 1 weight percent. A method according to claim 1, characterized in that the aqueous solution is a pretreated salt solution. A method according to claim 1, characterized in that the aqueous solution further contains means for sterilizing the lens. A method according to claim 1, characterized in that the se-25 quest agent is sodium hexaraetaphosphate. A method according to claim 1, characterized in that the sequestrant is a salt of gluconic acid selected from the group consisting of sodium, potassium and calcium. Method according to claim 1, characterized in that the se-30 quest agent is calcium boron gluconate. 10. A method of prophylactically treating contact lenses to prevent the formation of inorganic precipitate on the lens, characterized in that a contact lens is periodically contacted with an aqueous solution containing an effective amount of a sequester agent selected from a group consisting of polyraetaphosphate, gluconic acid and its salts for a period of time long enough to prevent the formation of inorganic precipitate on the lens. Method of treating contact lenses to remove inorganic 3000201.Ji -6- 21107 / Wax deposition and to prevent the formation of inorganic deposition on the lens, characterized in that an aqueous solution is prepared by water mixing with a solid unit dosage form of a sequestrant selected from a group consisting of polymetaphosphate, 5 gluconic acid and its salts and contacting the inorganic precipitate contact lens with the resulting aqueous solution for a sufficient time to deposit the inorganic precipitate on the lens remove. 12. Agent consisting of a pretreated saline solution, characterized in that this agent contains about 0.01 to about 20 weight percent of a sequester agent selected from the group consisting of a polymetaphosphate, gluconic acid and salts thereof. 13. A composition according to claim 12, characterized in that the sequestrant is n atrium hexametaphosphate. Composition according to claim 12, characterized in that the agent also contains a sterilizing agent for lenses. 3000201