CONTACT LENS PACKAGING

Abstract: The present invention relates to the use of a physiologically compatible surfactant, in solution, in a contact lens package, as an ocular lubricant. An example of such a surfactant is disodium cocoamphodiacetate.

Description: CONTACT LENS PACKAGING This invention relates to soft contact lenses and the initial packaging thereof. In particular the invention is concerned with the packaging of disposable contact lenses. The use of disposable contact lenses is becoming increasingly popular. Developments in the marketing and use of soft contact lens products means that users no longer wish to have the inconvenience of caring for their contact lenses. Additionally, recent new manufacturing technologies have been developed which allow for the manufacture of soft contact lenses of such low cost that they can be discarded at the end of each working day. Thus there is a move away from extended wear lenses towards single use, one-day wear, lenses. Until recently, however, lens removal from the eye and cleaning every day has been the generally accepted method of lens wear. Conventionally, soft contact lenses are thus provided packaged in saline (having the advantage of low cost) which is of typically 0.5% to 0.9% w/v concentration, this corresponding approximately to the composition of the tear film (i.e. the mucus layer or lipid layer) found in the eye. The composition of the saline is generally also chosen so as to have a target pH substantially equal to seven e.g. between pH 7.0 and 7.2. The reason for this is that some users may suffer some initial discomfort, commonly in the form of a brief stinging sensation, where the pH value of the lens packing solution is not substantially equal to seven. A pH value of seven has thus traditionally been accepted in the contact lens industry as the standard pH value of lens packing solutions. Commonly, the saline composition includes a buffer to maintain the pH value at substantially seven. The lenses are normally individually packaged in sealed containers or packets containing the saline composition. When first used, each lens is removed from its packet and usually placed directly on the user's eye. One disadvantage of the use of buffered saline is that it can nevertheless also cause initial discomfort, for some wearers (in fact, approximately one in one thousand wearers) whose eye pH is not substantially equal to seven and thus does not match the pH of the buffered saline packing solution. Such discomfort is commonly in the form of a stinging sensation of a more pronounced nature than that suffered by some wearers where no buffer is used, and can last for anything between a few minutes to an hour or more. While such discomfort may be endurable upon first use of a lens where that lens is intended for extended wear e.g. a lens designed for use over a one month or three month period, such discomfort is less acceptable where the lens is intended only for single use, one-day wear. Additionally, more general discomfort problems are often suffered by wearers of soft contact lenses who suffer from dry-eye conditions and/or who work or live in dry environments e.g. air conditioned offices or homes. A dry atmosphere causes the lens surface to become dry which, in turn, results in wearer discomfort. Furthermore, in some instances where the wearer uses certain medications (e.g. antihistamines, decongestants, diuretics, muscle relaxants, tranquilisers and motion sickness medications) these can cause dryness of the eye. This, in turn, results in increased lens awareness and discomfort for the wearer. A known way of improving wearer comfort is to use eye drops of an ocular lubricant which may be applied directly into the wearer's eye, while the lens is being worn, in order to provide symptomatic relief, at least to some extent. Such eye drops may be used to ease the initial discomfort of wearers using a new lens or lenses for the first time, or for providing relief to wearers suffering from dry-eye effects. The disadvantage of such eye drops is that they require to be obtained separately and are administered following insertion of the contact lens i.e. when the user is already suffering discomfort, thus adding cost and inconvenience to the wearer. It may moreover be awkward or inconvenient for a wearer to always carry a supply of eye drops, and/or to apply the drops in a public place. Moreover, such eye drops tend to provide only rather short term relief. It is an aim of the present invention to avoid or reduce one or more of the foregoing disadvantages. According to a first aspect the present invention comprises the use of a physiologically compatible surfactant, in solution, in a contact lens package, as an ocular lubricant. Various suitable surfactants are known in the art. Preferred surfactants include alkylaminocarboxyglycinate components. One which may be mentioned by way of example is disodium cocoamphodiacetate. Preferably said solution contains a surfactant which is a physiologically acceptable salt of a compound according to the general formula (I) : wherein R represents a C 8 -C 18 substituted or unsubstituted alkyl or alkenyl. Desirably said salt is a physiologically acceptable alkali metal or alkaline earth metal salt. The presence of the surfactant solution in the contact lens package ensures that any fluid transferred to the eye with a lens, when the lens is initially transferred from the packet to the eye, will include a quantity of the surfactant thereby substantially avoiding discomfort to the wearer. The surfactant may be included in a packing solution in the contact lens package. It is believed that the use of the surfactant in the lens package may ease any initial discomfort suffered by wearers whose eye pH does not match the pH of the packing solution. It is further believed that where the pH of the packing solution is generally neutral and not less than six there is no need to include a buffer in the packing solution as the surfactant will act to ease any initial wearer discomfort. The invention is particularly advantageous where the lens package contains a one-day wear lens for which the packing solution is the only solution which the lens will experience (since the lens will not be subject to any further cleaning or storing after it has been worn) . Where the surfactant used in the contact lens package is reversibly absorbed to a greater or lesser extent into the lens itself, this has the further advantage of providing a slow or extended release of surfactant onto the eyeball, in use of the lens, thus providing improved wearer comfort over an extended period of time and for much longer than the period over which the effects of any lubricant coating the surface of the lens will be experienced. It will be appreciated therefore and for the avoidance of doubt that references herein to ocular lubrication includes materials therefore and lubrication between the eye and the lens. The invention also includes use of an ocular lubricant as a packing solution in a contact lens packet containing a disposable contact lens. Various ocular lubricants are known in the art. Suitable ocular lubricants generally comprise an effective lubricating amount of a lubricant compound such as a surfactant, for example, disodium cocoamphodiacetate, in aqueous solution. An example of commercially available disodium cocoamphodiacetate is that sold under the MIRANOL (Trade Mark) brand name (grade C2M CONC NP) by Rhone-Poulenc Chemicals. In general there may be used from 100 to 5000 parts per million (ppm) , preferably from 200 to 2000 ppm, e.g. about 450 ppm of lubricant compound in the ocular lubricant solution, which may also, if desired, contain one or more other substances commonly used in packing solutions such as preservatives or bacteriostats. An example of a suitable preservative is borax. According to another aspect, the invention provides a contact lens package comprising a sealed container, containing a soft contact lens and a contact lens packing solution, the lens being immersed in the packing solution, wherein the packing solution comprises an ocular lubricant. The ocular lubricant may be an aqueous solution of a surfactant, such as disodium cocoamphodiacetate. The packing solution may further include physiologically compatible or isotonic saline. Preferably, the ocular lubricant comprises a surfactant dissolved in saline. The packing solution may also include a buffer for maintaining the pH value of the packing solution substantially equal to seven. An example of a buffer suitable for use with saline and which is physiologically compatible is sodium phosphate (or potassium phosphate) at a concentration of 0.01M. Potassium hydrogen phosphate and potassium dihydrogen phosphate may also be used. The concentration of the surfactant in the packing solution may be in the range of 100 to 5000 ppm e.g. 450 ppm. Preferably the quantity of surfactant in the packing solution is chosen so as to provide effective ocular lubrication, aε well as minimising the propensity to froth which may be exhibited by the surfactant-containing packing solution when shaken. The sealed container may be any suitable generally inert packaging material providing a reasonable degree of protection to the lens, such as glass or preferably a plastics material such as a polyalkene, PVC, polyamide etc. According to a further aspect, the present invention provides a method of reducing contact lens insertion discomfort to a disposable lens wearer, comprising the steps of providing an ocular lubricant in a packing solution of a packaged un-used disposable contact lens, and inserting said disposable contact lens into the eye of the contact lens wearer. In this manner, any solution transferred to the eye with the lens when this is placed in the eye for the first time, will contain a quantity of ocular lubricant. Furthermore, additional quantities of ocular lubricant which may have been absorbed within the lens itself may be gradually released onto the eyeball in use of the lens. Conveniently the ocular lubricant is added to a conventional packing solution (e.g. physiologically compatible saline) and mixed therewith, prior to introduction thereof into a container holding a contact lens, and sealing of the container. Alternatively the ocular lubricant could be added directly to a conventional packing solution previously introduced into a container for a contact lens, prior to sealing of the container. The contact lens may be present in the packing solution when the ocular lubricant iε added, or introduced subsequently before sealing of the container. The invention also includes a method of manufacturing a contact lens package comprising a contact lens in a sealed container, and comprising the steps of: i) moulding a contact lens in a mould comprising at least first and second mould portions; ii) hydrating and cleaning said lens in a container comprising at least one of said mould portions; iii) introducing a packing solution with ocular lubricant to the container with said lens supported therein; and iv) sealing the container. Preferably the method also includes the step of sterilising the contents of the container. Sterilisation may take place prior to, or most conveniently after, sealing of the container and may be effected by any suitable method known in the art e.g. by balanced autoclaving of the sealed container at temperatures of approximately 120°C or above. From the foregoing information it can be seen that the invention provides in a particularly convenient and economic manner improved comfort for the contact lens wearer which is of particular benefit to the wearer of single use, one-day- wear lenses and avoids the inconvenience of purchasing and administering special ocular lubricants, for example, in the form of eye drops. Example 1 One illustration of packaging a disposable contact lens according to the invention will now be described. A mixture made up of 11-12% sodium chloride and 89-88% disodium cocoamphodiacetate (a coconut base surfactant) was added to a quantity of 0.9% w/v saline (aqueous sodium chloride) in a ratio of 0.05% "mixture" to 99.95% "saline", to produce a final packing solution in which the disodium cocoamphodiacetate was present in a concentration of substantially 450 ppm. The final packing solution was introduced into individual lens packets, each containing a disposable soft contact lens, during the lens package manufacturing process, prior to sealing of the packet and sterilisation of the lens packet contents. The lens packets may each comprise one half of a mould in which a lens iε manufactured, and in which mould portion the lens is hydrated and cleaned according to the method described in our International PCT patent application no. PCT/GB96/02467, prior to the introduction of the packing solution into the lens packets. The method of moulding a contact lens and the packaging thereof is preferably that disclosed in United Kingdom Patent Publications No. GB 2237240 and GB 2237241 and European Patent Publication No. 367513 all in the name of British Technology Group and which are incorporated herein by reference thereto. Example 2 User Trials - During a one month period 1765 contact lenses packages containing no surfactant were supplied to users. Of those there were 16 reported instances (0.91%) of severe stinging and discomfort in the eye as the contact lens was inserted into the eyeball. During another one month period 3526 contact lenses containing surfactant were supplied to users. Of those there was 1 (one) (0.03%) reported instance of severe stinging and discomfort in the eye.

Claims: CLAIMS 1. The use of a physiologically compatible surfactant, in solution, in a contact lens package, aε an ocular lubricant, 2. The use of a physiologically compatible surfactant as claimed in claim 1 wherein said solution contains a surfactant which is a physiologically acceptable salt of a compound according to the general formula (I) : wherein R represents a C 8 -C 18 substituted or unsubstituted alkyl or alkenyl. 3. The use of a physiologically compatible surfactant as claimed in claim 2 wherein said salt is a physiologically acceptable alkali metal or alkaline earth metal salt. 4. The use of a physiologically compatible surfactant aε claimed in claim 2 or 3 wherein R represents a C 12 -C 14 substituted or unsubstituted alkyl or alkenyl. 5. The use of a physiologically compatible surfactant as claimed in any one of claims 1 to 4 wherein said surfactant is disodium cocoamphodiacetate. 6. The use of a physiologically compatible surfactant as claimed in any one of claims 1 to 5 wherein said surfactant is included in a packing solution in the contact lens package. 7. The use of a physiologically compatible surfactant as claimed in any one of claims 1 to 6 wherein said contact lens package contains a contact lens. 8. The use of a surfactant as claimed in claim 7 wherein said contact lens is a soft single or one-day use type contact lens. 9. The use of a surfactant as claimed in any one of claims 1 to 8 wherein said solution is buffer free and has a pH in the range from 6 to 8. 10. The use of a surfactant as claimed in any one of claims 1 to 9 wherein said solution is an aqueous packing solution including physiologically compatible saline. 11. The use of a surfactant as claimed in claim 10 when dependent on any one of claims l to 8 wherein said packing solution includes a buffer for maintaining the pH value of the saline substantially equal to seven. 12. The use of a surfactant as claimed in any one of claims 1 to 11 wherein the concentration of the surfactant in solution is in the range of 100 to 5000 ppm. 13. The use of a surfactant as claimed in claim 11 wherein the concentration of said solution is in the range from 400 to 500 ppm. 14. The use of a surfactant as claimed in any one of claims 1 to 13 wherein said solution includes at least one of a preservative and a bacteriostat. 15. A contact lens package comprising a sealed container, containing a soft contact lens and a contact lens packing solution, the lens being immersed in the packing solution characterised in that said packing solution comprises an ocular lubricant. 16. A contact lens package as claimed in claim 15 wherein said ocular lubricant is an aqueous solution of a surfactant. 17. A contact lens package as claimed in claim 15 or claim 16 wherein said surfactant is as defined in any one of claims 2 to 5. 18. A contact lens package aε claimed in any one of claims 15 to 17 wherein said packing solution includes at least one of a physiologically compatible saline, and a buffer for maintaining the pH value of the packing solution substantially equal to seven. 19. A method of reducing contact lens insertion discomfort to a disposable lens wearer, comprising the steps of providing an ocular lubricant in a packing solution of a packaged un-used disposable contact lens, and inserting said disposable contact lens into the eye of the contact lens wearer. 20. A method according to claim 19 which includes the preliminary stepε of adding said ocular lubricant to a conventional packing solution and mixing therewith, prior to introduction of the mixture into a container holding a contact lens, and sealing of the container. 21. A method according to claim 19 wherein said ocular lubricant is added directly to a contact lens packing solution provided in the container, prior to sealing of said container. 22. A method according to any one of claims 19 to 21 wherein said ocular lubricant is a surfactant as defined in any one of claims 2 to 5. 23. A method of manufacturing a contact lens package comprising a contact lens in a sealed container, and comprising the steps of: i) moulding a contact lens in a mould comprising at least first and second mould portions; ii) hydrating and cleaning said lens in a container comprising at least one of said mould portions; iii) introducing a packing solution with ocular lubricant to the container with said lens supported therein; and iv) sealing the container. 24. A method according to claim 22 which includes the step of sterilising the contents of the container. 25. The use of a physiologically compatible surfactant in the manufacture of a contact lens packing solution for providing an ocular lubricant effect.

Inventors: HAMILTON RONALD SHADE, HAMILTON, RONALD, SHADE
Applicants: AWARD PLC, HAMILTON RONALD SHADE, HAMILTON, RONALD, SHADE
Application year: 1996
Main classification: C11D3
IPC codes: A61L12, C11D1, C11D3