WO1993017720A1

WO1993017720A1 - Method and kit for disinfection of contact lenses

Info

Publication number: WO1993017720A1
Application number: PCT/CA1993/000093
Authority: WO
Inventors: Garth T. Webb
Original assignee: Webb Garth T
Priority date: 1992-03-10
Filing date: 1993-03-10
Publication date: 1993-09-16
Also published as: CA2062615A1

Abstract

A method of disinfecting plastic or rubber contact lenses comprises immersing, for a period of time sufficient to result in disinfection, the contact lenses in a solution containing a chlorine-releasing agent, wherein the amount of chlorine released is from 1 to 500 parts per million, preferably 10 to 20 ppm, and from 1 to 200 parts per million hydrogen peroxide, preferably. The invention further provides a kit for sterilizing soft contact lenses comprising a chlorine-releasing agent, hydrogen peroxide, an apparatus for producing a sterile saline and mixing the sterilizing solution and a holder for washing the lenses.

Description

METHOD AND KIT FOR DISINFECTION OF CONTACT LENSES

Field of the Invention

The present invention relates to methods and apparatus for disinfection of contact lenses, particularly plastic and rubber lenses.

Background of the Invention

Most contact lenses currently sold and used are hydrophillic or soft contact lenses, as opposed to hydro¬ phobic or hard lenses, due to the improved comfort of the user of such lenses and reduced irritation of the eye. However by their nature, it is necessary to maintain such hydrophillic lenses in a sterile condition. Any steri¬ lizing agent used must kill the bacteria on and in the lens, be harmless to the eye and have no effect on the shape or material of the lens. Improper disinfecting agents can alter the shape of the contact lens which renders them useless. A sterile saline solution is also used to store the lenses when not in use.

Most substances used for sterilization of contact lenses involve either substances which release halogens, in particular chlorine, when dissolved in water, or hydrogen peroxide. For example Canadian Patent No. 1,003,749 issued January 18, 1977 to Hydrophilics Interna¬ tional, Inc. discloses the use of sodium dichlorocyanurate, chlorinated trisodiu phosphate, potassium dich- lorocyanurate and trichloroisocyanuric acid in solution to sterilize soft contact lenses. The present inventor, in co- pending Canadian application no. 2,044,072-4 filed June 7, 1991, discloses the use of a small but effective amount of chloramine-T in concentration effective for disinfection but non-damaging to the eye and to the contact lenses. The use of chlorine alone may cause the lenses to be left with a yellow stain, however. Other methods involve the use of hydrogen peroxide as a sterilizing agent, but large quan¬ tities of peroxide are required for adequate sterilization. Up to now both chlorine and peroxide have not been used in combination for this purpose.

The sterilizing of contact lenses is generally carried out in a sterile saline solution. Currently, users are provided with a collection of bottles of sterile saline to use over a period of time. This method of providing saline is bulky and expensive. The present inventor has disclosed in co-pending Canadian patent application 2,025,- 106 filed September 11, 1990 and International application no. PCT/CA91/00056 a simple, portable device for storing and dispensing sterile saline. It comprises a resilient hollow container having a first outlet, a housing removably mounted on the container and having a second outlet and a passage communicating between the first and second outlet, a liquid-sterilizing filter mounted in the housing in the passage, and valve means for alternately opening and closing the second outlet, whereby pressure applied to the container forces a liquid stored in the container through said filter and out the second outlet when the valve is in an open position. This device permits sterile saline to be produced readily from tap water. There is a need therefore for a lens cleaning kit which incorporates this improved device to eliminate the previously bulky components of the prior art.

Summary of the Invention

The invention provides a method of disinfecting contact lenses comprising immersing, for a period of time sufficient to result in disinfection, the contact lenses in a solution containing a chlorine-releasing agent, wherein the amount of chlorine released is from 1 to 500 parts per million, preferably between 10 and 20 ppm, and from 1 to 1,000 parts per million hydrogen peroxide, preferably 40 to 80 ppm.

The invention further provides a kit for steril¬ izing soft contact lenses comprising a chlorine-releasing agent, hydrogen peroxide, an apparatus for producing a sterile saline and a container for immersing the lenses in the sterilizing solution.

Brief Description of the Drawings

In a drawing which illustrates a preferred em¬ bodiment of the invention: Figure 1 is a schematic diagram illustrating the kit of the invention.

Detailed Description of the Preferred Embodiment

According to the invention, a contact lens disinfectant solution is prepared by dissolving a suffi¬ cient amount of chloramine-T in a sterile saline solution to produce between 1 and 500 parts per million of chlorine in the water (preferably less than 200 ppm and between 10 and 20 ppm is preferred) . Hydrogen peroxide in a strength of less than 1000 ppm (40 to 80 ppm is preferred) is added to the saline also. The soft, hydrophillic contact lenses are immersed, for a period of time sufficient to result in disinfection, in the solution, which is effective for disinfection but non-damaging to the eye and to the contact lenses. The further step may be taken of adding buffers such as monosodium phosphate and dibasic sodium phosphate to the solution described in a quantity sufficient to neutralize the solution.

The invention is used by way of a kit l illus¬ trated schematically in Fig. 1. A suitable amount of a chlorine-releasing agent (e.g. chloramine-T) is provided in a pre-measured powder form in salt capsules or packets 3, which also provide the salt for the saline solution in a pre-measured amount. Hydrogen peroxide is provided in a 1 oz. spray atomizer container 5. A filter unit 7 of the type described in Canadian patent application 2,025,106 is provided as is a contact lens washer/holder 9 of the type disclosed in Canadian industrial design registration 67701 issued December 24, 1990. The lens or lenses are placed in holder 9. A spray of peroxide from atomizer 5 is sprayed into lens holder unit 9. Either distilled or tap water is added to filter unit 7 in the appropriate measured amount (use of distilled water results in improved filter life but tap water may also be used) . The salt packet with chlorine- releasing agent is dissolved in the water in the filter unit 7 to the appropriate concentrations noted above. The saline solution is then expelled from the filter unit as described in the above-noted application, causing it to be sterilized, into the lens washer/holder unit 9 which is operated in the usual manner to clean and sterilize the lens. Preferably the buffers noted above will be added to the saline, either in unit 7 or in the holder 9, and the lenses will be left overnight for sterilization (at least 4 hours is preferred, although sterilization may be a- chieved in considerably less time) . The resulting saline is of ophthalmic quality, non-irritating to the eye and can be used for subsequent storage of the lenses.

The invention provides a number of advantages. Chlorine alone in concentration tends to cause the lens to turn yellow due to partial oxidation of proteins. These partially oxidized proteins are retained in the porous lens material. The addition of peroxide apparently completes the oxidation process and de-ionizes the protein. Use of peroxide alone would require a much higher concentration of peroxide. Also the peroxide oxidizes the residual active chlorine which remains after disinfection. The reaction between H₂0₂ (hydrogen peroxide) and HOC1 (hydrochlorous acid) produces HC1 (hydrochloric acid) . The HC1 is neutral¬ ized by the buffering agent. The result is a saline that is non-irritating to the eye while effectively maintaining the lens sterile. The kit thus produces its own sterile saline from water for sterilizing and storage purposes, which saves considerable expense and storage size.

EXAMPLE

By way of example, 10⁶ germs of type staph dermatitis were added to 10 ml of water. Chloramine-T in powdered form was added to the 10 ml. of water to provide 10 parts per million of chlorine in the water. Hydrogen peroxide was added in a concentration of 60 parts per million. After 4 hours the solution was cultured and no growth was reported after 48 hours of incubation. A soft contact lens of class 4 material etasilicon - A (ACUVIEW™ ) was tested clinically in the solution for discolouration and no protein binding or yellow discolouration was noted. The amounts of living bacteria on the lens after removal were found to be mini¬ mal, and there was no detected alteration of the lens shape or material.

As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, .the scope of the invention is to be construed in accordance with the substance defined by the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method of disinfecting contact lenses comprising immersing, for a period of time sufficient to result in disinfection, a contact lens in a sterile saline solution containing from 1 to 500 parts per million chlorine and from 1 to 1000 parts per million peroxide.

2. The method of claim 1 wherein said amount of chlorine is from 1 to 200 parts per million.

3. The method of claim 1 wherein said amount of chlorine is approximately 10 to 20 parts per million.

4. The method of claim 1 wherein said amount of peroxide is approximately 40 to 80 parts per million.

5. The method of claim 3 wherein said period of time is between .1 and 8 hours.

6. The method of claim 1 comprising the further step of adding a buffer to the solution described in claim 1 in a quantity sufficient to neutralize said solution.

7. A kit for sterilizing contact lenses using water, said kit comprising a chlorine-releasing agent, hydrogen peroxide, an apparatus for producing a sterile saline and a container for immersing said lens in a sterilizing sol¬ ution.

8. The kit of claim 7 further comprising salt.

9. The kit of claim 7 further comprising a buffer.

10. A method of disinfecting contact lenses comprising: a) providing a kit for sterilizing soft contact lenses comprising a chlorine-releasing agent, hydrogen per¬ oxide, an apparatus for producing a sterile saline and a container for immersing said lens in a sterilizing solution; b) adding water and salt to said apparatus ar.d produc¬ ing said sterile saline; c) mixing said chlorine-releasing agent and said hydrogen peroxide in said saline to produce a steril- izing solution containing from 1 to 500 parts per million chlorine and from 1 to 1000 parts per million peroxide; and d) immersing, for a period of time sufficient to result in disinfection, a contact lens in said steril- izing solution in said container.

11. The method of claim 1 wherein said amount of chlorine is from 1 to 200 parts per million.

12. The method of claim 1 wherein said amount of chlorine is approximately 10 to 20 parts per million.

13. The method of claim 1 wherein said amount of peroxide is approximately 40 to 80 parts per million.

14. The method of claim 3 wherein said period of time is between .1 and 8 hours.