Abstract:
A container for disinfecting and storing a contact lens comprising a container having a nonporous but oxygen-permeable, water-impermeable liner that forms a continuous barrier layer to allow oxygen to escape but prevent water from escaping when the container becomes pressurized, such as when an oxidative disinfectant is neutralized catalytically to generate free oxygen (O 2 ). A rigid shell against which the liner is disposed is porous to oxygen and includes a main body and a cap removably attachable to an upper rim of the main body. The container also may have a lens holder for supporting a contact lens. The liner may be on the inside of the shell, or vice versa. The liner may be on the inside of the cap which has openings through which the liner expands when the container becomes pressurized as an indicator that the disinfecting process is underway. The liner may be constructed of a nonporous silicone and the shell of polyethylene or other rigid plastic that can be constructed as a highly gas-porous enclosure.

Description:
FIELD OF THE INVENTION 
       [0001]    Containers for holding and disinfecting contact lenses, in particular that prevent water leakage where the disinfecting process creates pressure in the container. 
       BACKGROUND OF THE INVENTION 
       [0002]    Use of hydrogen peroxide for the chemical sterilization or disinfecting of soft contact lenses is well-known in the art. Such lenses are generally disinfected inside particularly-crafted contact lens holders. Hydrogen peroxide is an oxidative disinfectant which, as part of the disinfection process, breaks down into water and oxygen. For such disinfection systems, the container holding the lenses and the disinfectant must be designed to allow oxygen to escape to prevent excess buildup of vapor pressure and potential explosion or rupture of the container. 
         [0003]    For example, U.S. Pat. No. 4,637,919 discloses a lens disinfecting container with a filter cartridge for use with oxidative disinfectants. This allows oxygen produced by decomposing hydrogen peroxide to escape from the device. Other attempts to solve this problem include U.S. Pat. No. 4,396,583 where a gas-permeable, liquid-impermeable membrane is loosely fitted inside a space in a cap of the device. The membrane is positioned between the disinfecting chamber and apertures located in the cap. The apertures in the cap allow gas which has passed through the membrane to escape. 
         [0004]    Unfortunately, neither the &#39;583 patent nor the &#39;919 patent adequately solve the problem of venting the oxygen created during hydrogen peroxide decomposition while providing a leak-proof and non-clogging container. The &#39;919 patent provides a container with minimal surface area to allow oxygen to escape. In addition, leakage is a potential problem as the filter cartridge is not adequately secured inside the aperture into which it is placed. Moreover, the filter cartridge would have a tendency to clog because of its minimal surface area. The &#39;583 patent is also inadequate because it provides a membrane which can be easily dislodged so that the container is likely to leak. 
         [0005]    There remains a need for a contact lens disinfecting container with a gas-permeable, liquid-impermeable member fixed securely thereto which can properly and adequately vent oxygen created during hydrogen peroxide decomposition without clogging or leaking. 
       SUMMARY OF THE INVENTION 
       [0006]    The present application provides a container for disinfecting and storing contact lenses including a main body defining within an inner space and having an open end, a lens holding means for supporting at least one contact lens within the inner space, a cap for sealably covering the open end of the main body, and a gas-permeable, liquid-impermeable liner disposed against the main body and cap to provide a continuous barrier layer surrounding the inner space when the cap attaches to the main body. 
         [0007]    The present containers provide devices for disinfecting and storing a contact lens comprising a main body including an open end, a lens holding means for supporting at least one contact lens within the container, a cap for sealably covering the open end of the container wherein the cap having an internal and external surface, and an oxygen-permeable, water-impermeable liner secured to the inner or outer surfaces of the main body and cap. 
         [0008]    The foregoing and other features and advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view of a disinfectant container for contact lenses as disclosed herein partially cutaway to show an internal basket assembly for supporting contact lenses within an inner space; 
           [0010]      FIG. 2  is an exploded perspective of a cap of the container of  FIG. 1  and the internal basket assembly; 
           [0011]      FIG. 3  is a vertical sectional view through a midline of the container of  FIG. 1  showing one embodiment of a leak-proof inner liner and rigid porous outer shell; 
           [0012]      FIG. 3A  is an enlarged view of one section of the container wall from  FIG. 3  showing the leak-proof liner and porous shell and illustrating a transport mechanism for the escape of oxygen from the inner space to the exterior of the container; 
           [0013]      FIG. 4  is a detailed sectional view an upper end of the container of  FIG. 3  showing an alternative configuration for the leak-proof liner; 
           [0014]      FIG. 5  is a detailed sectional view an upper end of an alternative container of the present application much like the embodiment of  FIG. 3  with a leak-proof inner liner and rigid porous outer shell; and 
           [0015]      FIG. 6  is a detailed sectional view an upper end of another alternative container of the present application with a leak-proof outer liner and rigid porous inner shell. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    The containers disclosed herein can be used with all contact lenses such as conventional hard, soft, rigid gas permeable, and silicone lenses. The container is preferably employed with soft lenses, such as those commonly referred to as hydrogel lenses. Hydrogel lenses are typically prepared from monomers, such as hydroxyethylmethacrylate, vinylpyrrolidone, glyceryl-methacrylate, methacrylic acid or acid esters and the like. Such hydrogel lenses include disposable, extended wear and continuous wear lenses. 
         [0017]    The present containers provide receptacles for disinfecting and storing a contact lens in solution, in particular using oxidative disinfectant solutions which generate oxygen during the disinfectant process and thus increase the pressure within the containers. Particularly useful oxidative disinfectant components are hydrogen peroxide or one or more other peroxide-containing compounds. Precursors to chlorine dioxide, such as stabilized purite, are also effective. The containers disclosed herein are useful with any disinfectant or, for that matter, storage solution that generates oxygen during the disinfectant process or over time, thus necessitating some form of pressure release. 
         [0018]    For hydrogen peroxide, a 0.5% (w/v) concentration, for example, in an aqueous liquid medium, is often effective as a disinfectant component. It is preferred to use at least about 1.0% or about 2.0% (w/v) hydrogen peroxide which concentrations reduce the disinfecting time over that of the 0.5% (w/v) peroxide concentration. No upper limit is placed on the amount of hydrogen peroxide which can be used with the present containers except as limited in that the oxidative disinfectant component should have no substantial detrimental effect on the contact lens being treated or on the eye of the wearer of the treated contact lens. An aqueous solution containing about 3% (w/v) hydrogen peroxide is very efficacious. 
         [0019]    When an oxidative disinfectant is used in the present invention, preferably a reducing or neutralizing catalyst in an amount sufficient to chemically reduce or neutralize substantially all of the oxidative disinfectant, for example, hydrogen peroxide, is employed. Neutralizing components are well known to those of skill in the art and include catalytic elements such as platinum, as well as catalase. Preferably, a non-bovine derived form of catalase is utilized. Preferably, a catalase produced by  Aspergillus niger  or  Micrococcus luteus  is used. Use of such catalases is disclosed in U.S. Pat. Nos. 5,362,647 and 5,521,091. 
         [0020]      FIGS. 1 and 2  illustrate a container  10  of the present application defined by a rigid shell  12  having a main body  14  and a cap  16 . The cap  16  includes a flat circular top wall  17  and a circumferential side wall  18 . As seen in the exploded view of  FIG. 2  and also with reference to  FIG. 3 , internal threads  19  on the inside of the circumferential side wall  18  mate with external threads provided on an upper tubular lip  21  of the main body  14 . When the cap  16  is screwed onto the main body  14 , a closed inner space  22  (see  FIG. 3 ) sized to receive one or more contact lenses is defined. 
         [0021]      FIG. 1  illustrates a portion of the container  10  cut away to show a lens-holding basket assembly  23 , which is seen in greater detail in  FIG. 2 . 
         [0022]      FIG. 2  provides an exploded perspective of the cap  16  and internal basket assembly  23 . The cap  16  includes a lens basket mounting plug  24  depending axially downward from a central point under the top wall  17  ( FIG. 1 ). The lens-holding basket assembly  23  comprises a supporting frame  26  fixed below a frame stem  28  with horizontal shaft-like gudgeons  30  upon which opposed lens covers  32  are attached via snap-fittings  34 . The opposed lens covers  32  can rotate upward and then downward on the gudgeons  30  to cover opposed convex lens receiving surfaces  27  on the supporting frame  26 . Each lens cover  32  may be secured to the supporting frame  26  with a claw  36  which snaps over one of two lower bosses  38 . Of course, this is just one example of a lens-holding basket, and the application incorporates many others. 
         [0023]      FIG. 3  provides a cross-sectional view of the container  10  with contact lenses  40  held within two separate convex receptacles defined by the internal basket assembly  23 . As mentioned, the container  10  includes a rigid shell  12  defined by the main body  14  having an open upper end, and the cap  16  screwed thereon. In addition to the rigid shell  12 , a liner  42  is provided to prevent water leaking from the container. In the embodiment of  FIG. 3 , the liner  42  is intimately disposed against the inner surfaces of the rigid shell  12 , and thus provides an inner liner. As will be explained below, however, the liner  42  may also be disposed only outside of the rigid shell  12 . 
         [0024]    Since the container  10  is formed in two parts, so is the rigid shell  12  and the liner  42 . In particular, the liner  42  includes a first liner section  44  disposed against the inner surfaces of the main body  14  and a second liner section  46  against the inner surfaces of the cap  16 . Both the first and second sections  44 ,  46  may be affixed to the respective inner wall surfaces with glue, welding, or the like, or may be coated thereon. When the cap  16  is screwed onto the main body  14 , the first and second sections  44 ,  46  of the liner  42  come into intimate contact in such a manner as to ensure a continuous barrier layer of water-impermeable material surrounding the inner space  22 . More particularly, the first liner section  44  includes a generally tubular side wall that extends up to an upper rim at the top edge of the upper tubular lip  21  of the main body  14 , and both the first liner section  44  and the lip  21  come into direct contact with the wider second liner section  46  under the cap  16 . Contact between the upper edge of the side wall  48  and underside of the second liner section  46  creates a small amount of compression which provides an adequate seal to prevent water from passing therebetween. This seal or seam between the first and second sections  44 ,  46  therefore ensures a continuous barrier layer of the material of the liner  42  around the inner space  22 , except at the mounting plug  24 . 
         [0025]    To complete the continuous barrier layer of water-impermeable material surrounding the inner space  22 , the lens basket mounting plug  24  is desirably made of a water-impermeable rigid material, in contrast to the rest of the rigid shell  12 . The mounting plug  24  can easily be molded separately and then inserted into a close-fit aperture on the cap  16  and sealed therein with thermal welding, adhesives or the like. To simplify the container, the suspended lens-holding basket  23  may be replaced with one that merely fits closely within the inner space  22 , thus eliminating the mounting plug  24 . Embodiments of this configuration are shown and described herein. 
         [0026]    The second liner section  46  disposed under the cap  16  is desirably an annular disc as seen in  FIG. 2  having a central aperture  48  that receives the mounting plug  24  for the lens basket assembly  23 . The central aperture  48  is in intimate contact with the mounting plug  24  to provide a seal therebetween. In a preferred embodiment, the disc-shaped second liner section  46  is secured to the cap  16  via gluing, welding or other well-known securing method. Preferably the second liner section  46  is welded ultrasonically to the cap  16 . The entire top surface or just the outer and inner edges of the second liner section  46  are secured such as by welding to the internal surface of the cap  16  so as to prevent any fluid passage from the inner space  22  between the second liner section  46  and the mounting plug  24 . 
         [0027]    Alternatively, the plug  24  into which the frame stem  28  inserts may be constructed of the same rigid porous material as the entire lid  16 , with the underside surfaces of the plug covered with the second liner section  46 , such as being coated with a silicone layer. For instance,  FIG. 4  shows an alternative configuration for the leak-proof liner  42  wherein the mounting plug  24  is formed along with and of the same material as the rest of the cap  16 , and where the second liner section  46  continues inward around all of the lower surfaces of mounting plug. This allows the basket stem  28  to be inserted into the plug  24  to form a completely sealed cap liner. 
         [0028]    Still further, a lid  16  constructed entirely of silicone may be an option too, though silicones are typically not firm enough for that purpose. Thus, there could be a hard plastic outer threaded rim over which a silicone rubber “sheet” is fitted, with the silicone part also having a plug that serves to anchor the basket stem  28 . Such a configuration would also reduce constraint on expansion of the silicone at higher pressure, thus providing greater pressure relief and/or greater visibility of the oxidative process working. 
         [0029]    The material of the liner  42  is such that water is prevented from leaking out of the inner space  22 . In a preferred embodiment, the liner  42  is formed of a silicone material that is highly oxygen-permeable yet water-impermeable even when a pressure in the inner space  22  exceeds an external pressure so as to permit oxygen to permeate through the liner. At the same time, the material of the rigid shell  12  is relatively porous to oxygen, such as a porous polyethylene, which therefore allows the oxygen that permeates through the liner to escape to the atmosphere. In the preferred material, i.e., non-porous silicone rubber, there are no identifiable pores. The passage of O 2  (and some other gases) occurs purely by being solubilized into the polymer from one surface and emitted from the polymer at the opposite surface. The flow of gas is driven by the O 2  concentration difference on the two sides of the polymer layer, and O 2  “dissolves” into the material and moves therethrough due to the concentration gradient. Thus, as O 2  concentration and pressure increase during peroxide neutralization, the flow of O 2  is from the inside to outside surface of the silicone liner, allowing eventual equilibration to near-atmospheric pressure inside the lens case. This is not the same as migration through pores in a membrane, as with earlier so-called “water-impermeable” materials such as GoreTex®, available from W. L. Gore &amp; Associates, Inc., Newark, Del. 
         [0030]      FIG. 3A  is a depiction of the venting process whereby oxygen bubbles generated within the inner space  22  are forced against the inner liner  42 ; the first liner section  44  in this case. Dashed arrows through the first liner section  44  indicate the transit of oxygen through the liner due to its oxygen transmissibility or permeability. In other words, oxygen is soluble in the material of the liner  42 . However, the liner material is completely nonporous and non-permeable or has near zero permeability to water molecules, so only oxygen escapes through it. The oxygen then passes easily through the outer shell  12  due to its porosity, as indicated by the rightward arrows. 
         [0031]    One particularly suitable material for the liner  42  is a silicone rubber or siloxane that is hydrophobic and has high oxygen permeability. Some materials are purportedly non-permeable to water, such as polytetrafluoroethylenes (PTFE) having pore size between 0.01 μm to 100 μm (i.e., Goretex®), but in practice these materials leak water under pressure and have proven less than optimum for use as contact lens containers. 
         [0032]    In the illustrated embodiment, the cap  16  includes at least one aperture  50  extending through the circular top wall  17 .  FIG. 1  shows three such apertures, though more or less may be provided. It should be noted that the second liner section  46  may be secured to the underside of the cap  16  at locations only around the mounting plug  24  and around the apertures  50 , such as with welds. 
         [0033]    To use the container  10  of the present invention, the lens holding basket assembly  23  receives contact lenses that are held in place by the opposed lens covers  32 . A hydrogen peroxide sterilizing solution as described is then poured into the open end of the container  10 . The cap  16  is then attached to the container. As the hydrogen peroxide decomposes into water and oxygen, the oxygen will transit through the oxygen-permeable, liquid-impermeable liner  42  and through the porous outer shell  12 , as described above, or through one of the apertures  50 . Under ambient conditions, water will not leak through the liner  42  or through the welds which bond the second liner section  46  to the cap  16 . As provided above, a catalyst may be provided before or after the hydrogen peroxide sterilizing solution has been added and the lenses disinfected to destroy any residual hydrogen peroxide. 
         [0034]      FIG. 4  also shows regions  52  of the second liner section  46  that flex outward into or through the apertures  50  from the internal pressure. These bubbles of liner  42  material are visible from above, and thus indicate to the user that the disinfectant process is working. Markings on the outer surface of the regions  52  may enhance the visibility, such as geometric shapes that deform when the regions bow outward or alphanumeric characters that enlarge. Additionally, the apertures  50  also serve as a safety valve of sorts to accommodate any increase in neutralization rate that might occur for any reason. 
         [0035]      FIG. 5  shows another configuration of lens container  60  having a rigid, porous outer shell  62  and an inner water-permeable, oxygen-soluble liner  64 . A cap  66  has a large orifice  68  in the top center that allows an inner liner  70  bonded under the cap to expand to the outside region of the cap when pressure accumulates inside the lens case, as seen in dashed line at  72 . This bulging phenomenon supplies additional headspace for expansion of the gas (during the early part of neutralization, when oxygen is released at the highest rate, and thus reduces the maximum pressure that could occur during the neutralization process. This configuration may also serve as an indicator that the peroxide has reached a certain stage in the neutralization process and that oxygen has sufficiently been eliminated from inside the case. In this configuration no lens basket plug is provided in the cap  66 , and thus a lens holding basket is simply placed into the inner space. 
         [0036]    A still further configuration of container is to provide the cap structure shown in either  FIG. 4  or  5 , coupled with a water impermeable main body portion of the outer shell. That is, only the cap portion of the rigid outer shell will be porous, and the water impermeable liner contacting the open mouth of the main body so that all of the oxygen escapes through the cap. Of course, this lessens the capacity for pressure release, but providing a large surface area of oxygen-permeable liner under the cap may be enough. 
         [0037]    Although the rigid, porous shell is conventionally used on the outside of the container, and the water-permeable, oxygen-soluble liner on the inside, it is also feasible to reverse the relative positions of these two elements. For instance,  FIG. 6  illustrates a container  80  having an inner rigid porous shell  82  surrounded by a water-permeable, oxygen-soluble liner outer liner  84 . The inner shell  82  includes a main body  86  having an upper open mouth onto which a cap  88  screws. The outer liner  84  includes a lower first section  90  coated or bonded to the outside of the main body  86  and an upper second section  92  coated or bonded to the outside of the cap  88 . The first and second liner sections  90 ,  92  extend slightly beyond the main body  86  and cap  88  at their abutment so that they compress slightly together, as shown. Furthermore, a portion  94  of the second liner section  92  may extend inward on the cap  88  to a short way up the inner threading so as to ensure contact and a seal with the lower first liner section  90 . The inwardly-extending liner portion  94  also functions as a locking mechanism in the final turn to insure airtight closure with no leakage even as pressure builds. This creates a complete liner  84  surrounding the space inside of the container to prevent water leakage. At the same time, oxygen passes easily through the porous inner shell  82  and then permeates through the outer liner  84 . A section of the upper second section  92  of the liner  82  may be left unbonded to the cap  88  so that it bulges outward when the inside of the container becomes pressurized, thus providing an indicator of proper functioning. 
         [0038]    Although not shown, the containers described herein could also incorporate a tablet dispensing mechanism in the cap so that multiple day in neutralization could be accomplished without the inconvenience of a separate neutralizer tablet package. That is, when an oxidative disinfectant is used, a reducing or neutralizing catalyst is preferable in an amount sufficient to chemically reduce or neutralize substantially all of the oxidative disinfectant. Therefore, for example, the separate mounting plug  24  illustrated in  FIG. 3  may be provided with a dispenser to allow periodic introduction of a neutralizer tablet as needed. 
         [0039]    In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims.