CA1136841A

CA1136841A - Method and composition for treating contact lenses

Info

Publication number: CA1136841A
Application number: CA000343588A
Authority: CA
Inventors: Frederick D. Kleist
Original assignee: Allergan Pharmaceuticals Inc
Current assignee: Allergan Inc
Priority date: 1979-01-15
Filing date: 1980-01-14
Publication date: 1982-12-07
Also published as: GB2040492A; DE3000742C2; ES487679A0; AU5456280A; FR2446499A1; ZA8054B; NL8000201A; GB2040492B; SE8000157L; AU533669B2; DE3000742A1; IT1129653B; JPH0337165B2; SE447030B; BR8000199A; IE800070L; ES8103394A1; IE49362B1; JPS5595926A; IT8019122A0

Abstract

METHOD AND COMPOSITION FOR TREATING CONTACT LENSES
ABSTRACT

The invention relates generally to a method and composition for the treatment of contactlenses to remove inor-ganic deposits and to prevent the formatin 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 cabonate, 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 present invention provides a method and compo-sition for the treament of contct 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 acqueous solution containing an effective amount of a sequestering agent selected from the group consisting of a poly-metaphospate, gluconic acid and salts thereof for a period, of time sufficient to remove existing inorganic deposits and to prevent formation of inorganic deposits.

Description

113~i~341 METHOD AND COMPOSITION FOR TREATING CONTACT LENSES

FIELD OF THE INVENTIGN
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. Hydro-phobic contact lenses are usually based on elastic and flexiblesilicone rubber (polyslloxane), 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 and comprises forming a mixture of a suitable polymerization catalyst, up to 40g of a silica filler, and the silicone 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 polymerizab!e olefinic double bonds. These lenses are usually based on polyhydroxylated alkyl methacrylates and contain a polyhydroxyla-ted alkyl methacrylate, such as polyhydroxyethyl methacrylate, 30 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 brought to be primarily calcium based, e.g., calcium phospate and 35 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
1~ 40 I have now discovered a method and composition for the D

113~4~

treatment of contact lenses, and especia11y silicone and hydro-philic plastic contact lensesl ~o remove inorganic de?osits 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 poly~letaphosphate, 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 so1ution sontain~ng from about 0.01 to about 20% by weight of a sequester-ing agent selected from the group consisting of a polyT~taphos-phate, gluconic acid and salts thereof. The composition may addit10nally contain an agent for sterilizing the lenses.
DETAILED DESCRIPTION OF THE INVENTION
The sequestering agents which may be used in th~s in-vention are typically calcium sequesterins agents such as, for example, polymetaptlosphates, ~luconic acid and salts thereof.
Su1table polymetaphosphates include sodium polymetaphosphate and preferably sodium hexametaphosphate. Salts of gluconic acid which may be used include common inorganic salts such as the sodium, potasslum and calcium salts as well as other salts such as, for example, calc;um borogluconate. The preferred sequestering agent is sodium hexametaphosphate. All 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, dying9 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 depost~s on the lenses without harming ~he 7ens 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 2~%
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.
~or example9 the sequestering agent could be delivered in the fo~m of a dry, unit dosage from such as a tablet wh~ch would be dissolved 1 1;36~3~l1 in water prior to use. The sequesterinn agent could also forma part of a ~uffered or unt,uffered preserved or unpreserved sterile, isotonic saline solution used to store the lenses. The sequesterin~
agents described herein may also be incGrporated into cold disin-fecting systems containing lens preservatives and disinfectants.
The present invention may be further described and illus-trated with reference to the following examples. It is to be under-stood9 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) ~Jhcih had been worn for approximately two (2) years was examined and found to have a heavy visible film de~osit. The lens was cleaned with an enzymatic cleaner for ~4 hours ~ith little effect. The lens was then asepticized (heated to lO~C for 15 minutes) for two (~) cycles in a 20% solution of sodium hexametaphosphate in water.
The lens still retained some of the film-like material, bu~ after one further treatment with the enzy~atic cleaner, the lens was found to be free of film. This indicates that the ~eposit consisted of both inorganic and protein materials since the enzymatic cleaner rapidly (usually within four hours) and completely removes protein films from hydroph~lic 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 lens was cut in half and one-half was asepticized (heated to 80C for 20 minutes) for 30 four cycles in an aqueous solution containing 0.2% sodium hexameta- - phosphate, 0.1% boric acid, 0.01% disodium edetate, 0.85X sodium chloride preserved with 0.~01% thimerosal at pll 7.4. Follo~in~
another three hour treatment with the enzyme cleaner solution, the lens was free of Yisible deposits. The other half of the lens treated in a similar manner9 except that ~he aseptor cycle was omitted, still retaine~ its heavy inor~anic film.
EXAMPLE III
A hydroph~lic human worn lens w1th an inorganic film was cleaned for four hours wit~l the enzyme cleaner. tlo chan~e in *Trade mark 113~;84~

the film was noted. It was then alternately asepticized (heated to ~0C for 20 Ininutes) in an aqueous solution containing ~1.2X
sodiun~ gluconate~ ~.1% boric acid, O.OlX disodium edetate, 0.85%
sodium chloride preserved with 0.001% thimerosal at p~ 7.4 (Formula S No. 5945X) ~or 20 Minutes and cleaned for several hours with the enzyme cleaner until three of these cycles had been cornpleted.
Photomicrographs taken ot` the same area of the lens at each step show al~Dst complete removal of the heav~ inorganic deposit after the three cycles. No visible deposi~s re~ained.
EXAMPLE IY
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 8D cycles. Test Solution 1 was an aqueous 501ution containing ~.2% POLYSORBATE 80*
1.92% propylene glycol, 0.033~ alkyl triethanol ammonium chloride, 0.05% sodium bicarbonate, 0.002% sodium chlori~e, Q.0023% thimerosal, and Test Solution 2 contained the same in~redients plus 0.~5% --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 Tes~ Solution 2 demonstrating that the addition of sodium hexameta-phosphate prevented the deposition of the insoluble calcium salts on hydrophilic contact lenses.

*Trade mark

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 se-lected from the group consisting of a polymetaphosphate gluconic acid and salts thereof for a period of time sufficient to remove in-organic 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 aqueous 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.

10. A method for the prophylactic treatment of contact lenses to prevent the formation of inorganic deposits on the lenses comprising periodically contacting a contact lens with an aqueous solution contain-ing 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 de-posits 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.

13. The composition of Claim 12 wherein the sequestering agent is sodium hexametaphosphate.

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