BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to apparatus and methods for sensing the neutralization of an oxidant, such as a disinfectant used, e.g., for disinfecting or sterilizing contact lenses.

2. Related Art

Oxidant solutions are widely used in the medical and related fields for a variety of purposes. For example, the use of disinfectant oxidants, such as hydrogen peroxide, in disinfecting or sterilizing processes is well known. Hydrogen peroxide solutions are widely used for disinfecting a broad range of articles and devices, including medical instruments, dental appliances, catheters, syringes and contact lenses, to name just a few.

Typically, such articles are placed in an oxidant for a treatment period, e.g., a bath of 3% by volume hydrogen peroxide for a period of time suitable to allow the articles to be sufficiently disinfected or sterilized. However, when these articles are removed from the oxidant (e.g., hydrogen peroxide bath), a residual amount of oxidant (e.g., hydrogen peroxide) typically remains on such articles. Upon placing these articles in contact with living tissue, the residual oxidant may cause damage to the tissue cells or, at the very least, irritation to the patient. This problem is especially significant when the treated article is made from materials that absorbs the oxidant (soft contact lenses are an example of articles which are made from such absorbent materials) .

Known processes for addressing this problem include processes wherein the treated article is subjected to a

bath of a neutralization liquid for neutralizing or diluting the residual oxidant, or an excess amount of a neutralizing material such as catalase is placed in the hydrogen peroxide bath. Typically, the article must be left in the resulting neutralization bath for a period of time to allow a suitable neutralization of the residual oxidant. If the article is removed from the neutralization bath before a suitable neutralization period has passed, unneutralized residual oxidant may be present on the article with enough concentration to create the problems noted above. Therefore, the ability to determine when residual oxidant (e.g., hydrogen peroxide) is sufficiently neutralized would provide significant advantages. Various treatment processes and systems for disinfecting articles, such as medical instruments or devices and contact lenses, are known. For example, U.S. Patent 4,521,375 to Houlsby (issued June 4, 1985), U.S. Patent 4,568,517 to Kaspar, et al. (issued February 4, 1986), U.S. Patent 4,863,627 to Davies, et al. (issued September 5, 1989), U.S. Patent 4,880,601 to Andermann, et al. (issued November 14, 1989), U.S. Patent 4,976,921 to Itagaki, et al. (issued December 11, 1990) and U.S. Patent 5,011,661 to Schafer, et al. (issued April 30, 1991) each describe systems and processes wherein an article, such as a contact lens, is disinfected in a disinfecting solution, such as an aqueous solution of H ₂ 0 ₂ (hydrogen peroxide) and thereafter a neutralizing agent, such as a catalyst for decomposing residual H ₂ 0 ₂ , is added to the H ₂ 0 ₂ . For example, platinum is used to catalyze the degradation of H ₂ 0 ₂ in a system made by CIBA VISION. However, it is di icult to determine the time needed to effect neutralization with a platinum catalist. Platinum becomes less effective with use as its surface becomes contaminated.

Another problem confronting the soft contact lens user occurs when the user adds a neutralizing agent such as catalase to a disinfecting solution such as 3% H ₂ 0 ₂ . In such case, all of the solutions are clear. If the user forgets whether or not the catalase was added to in the H ₂ 0 ₂ solution, the user may mistake an unneutralized solution for a neutralized one.

As noted above, it would be advantageous to be able to determine when a suitable neutralization time has passed, whereafter the article may be removed from the H ₂ 0 ₂ bath and safely used. Past practices for determining the lapse of a suitable neutralization time include processes wherein a color indicator is added to the neutralization solution. The above-noted patent to Davies, et al. , describes an example of such a system wherein phenolphthalein or a redox indicator such as methylene blue and triphenylmethane dyes are added to the neutralization solution so as to cause the solution to change from a colored state (indicating that the solution is in a oxidized, state, therefore containing an undesirable amount of residual hydrogen peroxide) to a colorless state (when the hydrogen peroxide is sufficiently reduced) .

However, the colorizing agents employed in such systems must be compatible with the article being disinfected and the manner in which the article is used. For example, if the disinfected article is a contact lens, the colorizing agent must be compatible with the material from which the lens is made and also to the lens wearer's eye. Many known colorizing agents, such as potassium iodide, phenolphthalein and redox indicators are toxic. They also are known to stain the lens. Therefore, if these agents are added to the neutralization solution, the amount and concentration of colorization agent must be carefully controlled, and, even then, may result in undesirable side effects.

As will be explained in further detail below, the present invention relates to a system for detecting the sufficient neutralization of a disinfecting agent or other oxidant, without the need to add colorizing agents to a neutralization solution, by detecting and indicating the ability of the H ₂ 0 ₂ solution to generate an electric potential. While general apparatus for detecting the ability of an oxygen containing solution to generate an electric potential has been known for quite some time (see, e.g., U.S. Patent 3,313,720 to Robinson, issued April 19, 1963, and U.S. Patent 4,409,183 to Fischer, issued October 11, 1983), applicant is unaware of any prior apparatus or processes for detecting neutralization of a disinfectant or other oxidant by detecting the ability of an oxidant solution to generate an electric potential.

SUMMARY OF THE DISCLOSURE

The present invention relates to apparatus and methods for detecting the sufficient neutralization of an oxidant, such as a disinfectant, and to oxidant treatment systems and processes which employ such apparatus and methods. According to an embodiment of the invention, an article, such as a soft contact lens, is disinfected in a bath of disinfecting solution, such as a hydrogen peroxide solution. After a suitable time period in the disinfectant bath, a neutralization agent is added to the bath so as to form a neutralizing solution to neutralize or dilute residual disinfectant in the bath and on or absorbed in the article. Alternatively or in addition, a platinum body may be located in the disinfecting solution as a neutralizer. Applicant has recognized that typical oxidant treatment solutions, such as a hydrogen peroxide containing disinfectant solution, have electrolytic properties and, therefore, the ability to generate a small electric potential. Applicant has also recognized that unneutralized residual oxidant in a neutralization solution (e.g., in the early stages of the neutralization period) will provide the neutralization solution with electrolytic characteristics and the ability to generate a detectible electric potential. Applicant has further recognized that this electric potential can be used to detect the presence of an undesired quantity or concentration of unneutralized oxidant or disinfectant in the neutralization solution. This detection can be accomplished by placing electrodes in the neutralization solution and detecting the electric potential generated between the electrodes due to the electrolytic properties of the oxidant containing neutralization solution.

Apparatus for detecting the ability of the neutralization solution to generate an electric

potential, according to an embodiment of the invention, includes first and second electrodes of different types of materials disposed in the neutralization solution and separated from each other. A lead connected to each electrode extends to a voltage meter for detecting the electric potential between the two electrodes. Alternatively, the electric potential generated between the two electrodes may be used to power an electric indicating device, such as a light emitting diode, an incandescent light bulb, a liquid crystal display, a buzzer, or other visual or audible indicators.

Alternatively, the electric potential generated between the electrodes may be used to provide a switching control signal for controlling the switching state of an electric switch, such as a transistor switch. The controlled electric switch is used to turn on or off an indicating device powered by an external source.

As a result, the neutralization detection process and apparatus, according to embodiments of the present invention, can provide a simple, easy to use and accurate detection of the presence of a concentration of residual oxidant, such as disinfectant, in a neutralization solution without the need to add toxic chemicals (or any other indicating chemicals) to the neutralization solution. An embodiment of the present invention is particularly useful for the detection of the neutralization of residual disinfectant in a contact lens neutralization solution.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description of embodiments of the invention will be made with reference to the accompanying drawings, wherein like numerals designate corresponding parts in the several figures.

Figure 1 is a schematic diagram of a detection apparatus according to a first embodiment of the invention.

Figure 2 is a schematic diagram of a detection apparatus according to a second embodiment of the invention.

Figure 3 is a schematic diagram of a detection apparatus according to a third embodiment of the invention. Figure 4 is a schematic diagram of a detection apparatus according to a fourth embodiment of the invention.

Figure 5 is a perspective view of a contact lens container according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description is of the best presently contemplated mode of carrying out the invention. This description is not to be taken in a limiting sense but is made merely for the purpose of illustrating general principles of embodiments of the invention. The scope of the invention is best defined by the appended claims.

The present invention relates to apparatus and methods for detecting the sufficient neutralization or dilution of a residual oxidant, such as a disinfectant used for disinfecting medical devices, contact lenses, or the like. While embodiments of the invention may be used for treating various types of medical instruments, dental appliances, catheters, syringes, artificial implants, or the like, the illustrated embodiments and the embodiments described below are directed to contact

lens disinfecting and neutralizing systems. However, it will be understood that embodiments of the invention may be used with various types of oxidant treatments for treating various types of medical instruments, devices, or the like, as noted above.

According to an embodiment of the invention, a process for disinfecting a contact lens prior to placing the lens over a user's cornea involves placing the lens in a disinfectant bath. In an embodiment of the invention, the lens is placed in a container of disinfectant solution for a period of time. Preferably, the disinfectant solution is composed of about 10 ml of three percent H ₂ 0 ₂ (also known as hydrogen peroxide) in distilled water. Other suitable disinfectant solutions include solutions containing chlorine (Cl ₂ ) , chlorine dioxide (C10 ₂ ) or ozone (0 ₃ ) . Embodiments of the invention may employ other oxidants or disinfectant solutions which, when combined with a neutralizing agent, provide a neutralization solution having electrolytic properties that diminish as the oxidant or disinfectant neutralizes. The disinfectant solution sold under the trademark OXYSEPT ^* , of Allergan, Inc. is a suitable disinfectant solution.

The contact lens may be left in the disinfectant solution for a suitable period of time to ensure that the lens is sufficiently disinfected. Preferably, the lens is left in the disinfectant solution overnight. However, a shorter time period, such as ten minutes may be sufficient. After a suitable disinfectant time period, a neutralizing agent is added to the bath to form a neutralization solution bath and a neutralization period begins. During the neutralization period, residual disinfectant in the neutralization solution is neutralized according to a well known neutralization process. The lens is left in the neutralization bath for a period of time (typically ranging from ten

minutes to several hours) for neutralization or dilution of the residual disinfectant. After some time period following the addition of neutralizing agent to the bath, the residual disinfectant in the bath becomes sufficiently neutralized (e.g., the concentration of unneutralized disinfectant becomes sufficiently low) such that the contact lens may be removed from the bath and safely and comfortably placed over a wearer's cornea. Preferably, where 3% H ₂ 0 ₂ is employed for a soft contact lens, the neutralization solution comprises adding a tablet of catalase. However, other suitable neutralization agents may be employed, such as sodium thiosulfate, platinum, palladium, barium sulfate, sodium hydroxide, manganese dioxide. The neutralization solution may be formed in the disinfectant bath by adding neutralization agent, e.g., in tablet or liquid form, to the disinfectant bath. While the above-described disinfection and neutralization steps employ a single container for two separate baths, a disinfectant solution bath and a neutralization solution bath, it will be understood that two separate containers may also be used for the disinfection and neutralization baths, respectively. With the two container method, first a lens is placed in a container of disinfectant solution (the disinfectant bath) . Then, the lens is removed from the disinfectant bath and placed in another container holding neutralization solution (the neutralization bath) for neutralizing residual disinfectant solution clinging to or absorbed in the contact lens. Alternatively or in addition, platinum neutralization may be effected by locating a platinum body in the disinfectant solution bath (or the neutralization solution bath in a two bath system) .

Certain types of contact lenses are relatively highly absorbent due to the materials used in

manufacturing such lens. For example, soft contact lens tend to be relatively highly absorbent and, therefore, absorb some of the disinfectant solution from the disinfectant bath. When the lens is in the neutralization bath, the residual disinfectant clinging to or absorbed in the lens will tend to disperse within the neutralization solution. Residual disinfectant in the neutralization solution is neutralized during a neutralization period, in a manner similar to that of above described single container neutralization method. Alternatively, the disinfectant solution may be removed from the container and neutralization solution added to the same container following the disinfectant period. As yet a further alternative, a time released neutralizing agent may be added to the disinfectant so as to automatically neutralize the disinfectant after a suitable disinfecting period has passed (e.g., see U.S. Patent 4,863,627 to Davies, et al. and U.S. Patent 4,568,517 to Kaspar, et al., both note above). However, each of these methods result in a neutralization bath containing residual disinfectant which must be neutralized over a period of time before the contact lens can be removed from the bath and safely and comfortably used. In order to avoid removing the lens from the neutralization solution before a suitable amount of residual disinfectant has been neutralized or diluted to make the lens safe to wear, a process and apparatus for detecting sufficient neutralization of the residual disinfectant is employed. This involves the placement of electrodes in the neutralization solution and the detection of an electric potential generated between the electrodes.

This concept is based, in part, on the recognition that a neutralization solution containing a sufficient concentration of unneutralized residual oxidant will act as an electrolyte. For example, a neutralization

solution containing a three percent H ₂ 0 ₂ solution of residual disinfectant will act as an "electrolyte" capable of generating an oxidative electric potential. When two electrodes, composed of two different types of materials, respectively, are placed in a separated relationship within the "electrolyte", an electric potential will be generated between the two electrodes. This electrical potential may be sensed with a volt meter. Alternatively or in addition, the electric potential may be used to power an electronic visual or audible display, or may be used to control a switching device, such as a switching transistor. Through various electronic connections, as exemplified below, the electric potential generated between the electrodes may be used to power and/or control indicating devices for indicating whether or not a sufficient amount of residual disinfectant has been neutralized or diluted.

Figure 1 is a schematic diagram of a neutralization detection system according to a first embodiment of the present invention. A container 10 of neutralization solution 12 serves as a neutralizing solution bath for a contact lens 14. Prior to the neutralization bath, the contact lens 14 was disinfected in an oxidant disinfectant bath (not shown) , as discussed above. As a consequence of the disinfectant bath, a residual amount of oxidant disinfectant (e.g., H ₂ 0 ₂ ) is present in the neutralizing solution during the neutralization process. As a result, the neutralization solution exhibits electrolytic properties.

As the neutralization process proceeds, residual disinfectant present in the neutralization solution is neutralized and the concentration of unneutralized disinfectant diminishes. In this manner, the electrolytic properties of the neutralization solution diminish with the progression of the neutralization period. Accordingly, the ability of the neutralization

solution to generate an electric potential diminishes with the progression of the neutralization period. A irst metal electrode 16 and a second metal electrode 18 are at least partially disposed in the neutralization solution 12. Preferably, the electrodes are made of (or are coated with) metals which are known to be inert and biologically compatible with the ultimate user of the lens 14.

The first electrode 16 is made of or coated with a metal which is different from the metal which the second electrode 18 is made of or coated with. These two metals will dissolve differently in an oxidant containing solution such that the metals acquire electric charges of different polarities in a manner which is well known in the electrolyte battery art. In this manner, when the electrodes are placed in an oxidant containing neutralization solution, an electric potential is generated between the electrodes of a magnitude dependant upon the concentration of unneutralized oxidant in the solution.

One electrode, e.g., the first electrode 16, will be positively charged (relative to the other electrode 18) and will, therefore, be considered the anode. The other electrode, e.g., the second electrode 18, will acquire a negative charge (compared to the first electrode) and will, therefore, be considered the cathode. The combination of the electrolyte properties of the neutralization solution 12 with residual disinfectant dispersed therein and the two electrodes 16 and 18 form a rudimentary electrolyte battery structure (hereinafter referred to as "the rudimentary battery structure") which generates a potential between the first and second electrodes.

In a preferred embodiment, the electrode which forms the cathode is made of titanium. The anode electrode is also made of titanium coated with a material, such as ruthenium, which will allow the

titanium to act as an anode. However, other suitable metals may be used for the electrodes. For example, suitable substitutes for titanium include platinum, palladium, carbon or other biologically inert metals. The anode electrode may be titanium coated with other types of rare earth metals. Alternatively, the anode may be made of such rare earth metals rather than being merely coated with such metals.

In the early stages of the neutralization period, the neutralization solution may contain a large enough concentration of unneutralized oxidant to act as an electrolyte capable of generating an electric potential within a range of voltages. A voltage within this range will be referred to herein as a "high voltage". In a later stage of the neutralization period, the neutralization solution would have neutralized enough of the residual oxidant contained therein that the solution will not be capable of generating an electric potential over a predefined magnitude. A voltage below this predefined magnitude (including 0 volts) will be referred to herein as a "low voltage".

A current path comprising a first lead 20, a second lead 22 and a load 24 are connected between the first and second electrodes 16 and 18. Specifically, one end of the first lead 20 is connected to the first electrode 16 and the other end of the lead 20 is connected to the load 24. One end of the lead 22 is connected to the second electrode 18 and the other end of the lead 22 is connected to the load 24. The load 24 is shown in Figure 1 as a load resistance device for simplicity. However, it will be recognized that load resistance 24 represents at least one of several types of indicating devices such as a voltage meter for detecting and displaying the potential between the first and second electrodes, a current meter for detecting and displaying current flowing between the electrodes, a visual display device

(such as an LED, LCD, incandescent bulb, or the like) or an audible display device (such as a buzzer or the like) . The load 24 receives power from the rudimentary battery structure formed by the electrodes and electrolyte composition of the neutralization solution and residual disinfectant dispersed therein.

According to an embodiment of the invention, the load 24 comprises a visual or audible display device which provides a visible or audible signal upon being supplied with a high voltage but not when the device is supplied with a low voltage. The display device may be such that any voltage below the high voltage range would not be sufficient to power the device, whereas a voltage within the high voltage range would be sufficient to power the device. Alternatively, a switching device (not shown) may be connected between the display device and the rudimentary battery structure for switching the display device on in response to a high voltage and switching the display device off in response to a low voltage. Such display devices and switching devices are well known.

Figure 2 illustrates a detection system according to a second embodiment of the invention. In Figure 2 , the lead from one electrode, e.g., the first electrode 16 is connected to the control input of a voltage or current controlled switch 26. The signal on lead 16 controls the operation of switch 26 to selectively open or close the circuit between the input terminal of switch 26 and the output terminal of switch 26. Such current or voltage controlled switches 26 are well known. Examples of such switches are typical voltage or current controlled transistor switches. However, other suitable controllable switches may be employed without departing from the scope of the invention. In the Figure 2 embodiment, a power source 28 is connected to the input terminal of switch 26 and a load 30 is connected between the output terminal of switch

26 and ground. The second electrode 18 is also connected to ground through the second lead 22.

In this arrangement, the existence of a sufficiently high concentration of disinfectant in the neutralization solution 12 will cause the rudimentary battery structure to generate a high voltage between electrodes 16 and 18 and a corresponding high voltage signal along lead 20. The presence of this high voltage signal on lead 20 controls switch 26 to conduct current supplied to the input terminal of switch 26 from power source 28 to the output terminal of switch 26 and, therefore, to load 30. Load 30 is, thereby, supplied with power from power source 28.

Load 30 may be any suitable type of electronic indicating device such as discussed above. However, since load 30 is powered by external power source 28, as opposed to by the power generated from the rudimentary battery structure, load 30 may be chosen from devices which consume a greater amount of power than, for example, load 24 shown in Figure 1.

Moreover, in this embodiment, power source 28 may be either an AC or a DC power source and load 30 may be a corresponding AC or DC electronic indicating device. Figure 3 shows another embodiment of the present invention wherein a lead connected to an electrode, e.g., lead 20 connected to electrode 16, is connected as a control input of a first switch S-1. A power source 28 is connected to the input terminal of switch S-1 and a load L-l is connected to the output terminal of S-1 in a manner similar to the manner in which power source 28 and load 30 are connected to switch 26 in Figure 2. Similar to switch 26 in Figure 2, switch S-l operates so as to conduct current from power source 28 to load L-l when a sufficient voltage (e.g., a high voltage) or a signal of sufficient current magnitude is provided at the control input of switch S-1. The control signal will be sufficient to place switch S-1

in a conducting mode (conducting power from power source 28 to a load L-l) when a sufficiently high concentration of unneutralized residual disinfectant is in the neutralization solution 12. On the other hand, when the concentration of unneutralized residual disinfectant in neutralization solution 12 is relatively low, the signal, if any, (e.g., a low voltage) generated on lead 20 by the rudimentary battery structure will not be of sufficient magnitude to control switch S-1 to conduct current from power source 28 to load L-l. Thus, upon neutralization of a sufficient amount of unneutralized disinfectant, the neutralization solution 12 will not be able to generate a sufficient high voltage or current signal to turn switch L-l on and the load L-l will, therefore, not be supplied with power through switch S-1.

Switch S-2 operates in an opposite manner from switch S-1. That is, switch S-2 operates to conduct power between its input terminal and its output terminal when the signal at the control terminal is low. On the other hand, switch S-2 operates to open the circuit between its input and its output terminals when the signal at its control terminal is of a sufficiently high magnitude (e.g., a high voltage). This type of switch device is well known. The input terminal of switch S-2 is connected to power source 28 and the output of switch S-2 is connected to a second load L-2.

With the arrangement shown in Figure 3, power is supplied to load L-2 when the signal on lead 20 is of a sufficiently low magnitude (e.g., a low voltage). However, when the signal on lead 20 is high, power is cut off from load L-2 and is supplied to load L-l. Therefore, load L-l is energized when, e.g., a high voltage is provided from the rudimentary battery structure, and load L-2 is energized when, e.g., a low

signal is provided from the rudimentary battery structure.

Thus, the indicating device represented by load L-l may be used to indicate an unsafe condition (a condition wherein the residual disinfectant is not sufficiently neutralized) . The indicating device represented by load L-2 may be used as a safe condition indicating device (for indicating the condition wherein the residual disinfectant in neutralization solution 12 is sufficiently neutralized) . In a preferred embodiment, loads L-l and L-2 comprise red and blue light emitting devices, respectively. According to this embodiment, a red light will be energized during an unsafe condition and a blue light will be energized during a safe condition. Such an indicating structure provides a very simple, easy to use system for indicating when residual disinfectant is sufficiently neutralized. In alternative embodiments, both the first and second switches L-2 may have their control terminals connected to lead 20. In that arrangement, the first switch S-1 and the load L-l are optional.

Figure 4 shows another embodiment of the present invention wherein the electrodes are connected to logic circuitry, such as digital logic devices. Referring to Figure 4, the magnitude of the voltage between leads 20 and 22 is compared with a predefined threshold voltage magnitude via a voltage comparing circuit 21. Suitable voltage comparing circuits are well known.

When the magnitude of the voltage produced by the rudimentary battery structure is above the threshold magnitude, the comparing circuit 21 outputs a high level signal. However, if the magnitude of the voltage produced by the rudimentary battery structure is below the threshold magnitude, the comparing circuit 21 outputs a low level signal. The output of the comparing circuit 21 is connected to the control terminal of a first switch 23.

First switch 23 has an input connected to a power source 25 and an output connected to a display device 27, such as a visual or audible display device of the type described above with regard to the embodiments of Figures 1-3. The first switch 23 operates so as to conduct current from power source 25 to display device 27 when a high level signal is provided at the control input of switch 23. The first switch 23 does not conduct current from power source 25 to display device 27 when a low level signal is provided at the control input of switch 23.

The Figure 4 embodiment has a second switch 29 and second display device 31. However the second switch 29 and the second display device 31 are optional. Alternatively, the second switch may be connected and the first switch 23 and device 27 would be optional. The control input of the second switch is connected to the control input of the first switch 23. The second switch 29 operates so as to conduct current from power source 25 to display device 31 when a low level signal is provided at the control input of switch 29. The second switch 29 does not conduct current from power source 25 to display device 31 when a high level signal is provided at the control input of switch 29. As a result, the first display device 27 is energized and the second display device 31 is not energized when the output of the comparing circuit is at a high level. However, when the output of the comparing circuit is at a low level, the second display device 31 is energized and the first display device 27 is not energized.

As a result, the apparatus provides a simple, easy to use and operate system which allows a user to readily identify whether or not the oxidant is sufficiently neutralized in the neutralization solution. That is, the energization of the first display device 27 indicates that the oxidant is not

sufficiently neutralized. On the other hand, the energization of the second display device 31 indicates that the oxidant is sufficiently neutralized. In a preferred embodiment, the first and second display devices provide respectively different displays, e.g., emit different light colors or different sounds, such that an identification of which display is being energized can be even more simplified.

According to an embodiment of the present invention, the container of neutralization solution and the electrodes of the rudimentary battery structure are formed as part of a contact lens storage container. Typically, contact lenses are stored individually in small, closable containers capable of holding disinfectant and neutralization solutions. An embodiment of the present invention comprises the inclusion of electrodes in the container structure so that the neutralization solution containing container itself operates as a rudimentary battery structure. Referring to the Figure 5 embodiment, a container 32 includes a solution receptacle 34 and a cap 36 designed to secure to and close the receptacle. The receptacle 34 defines a hollow interior 38 which can hold a predefined amount of solution, such as 10 ml of neutralization solution. First and second electrodes 40 and 42 extend from the cap 36 into the interior of the receptacle 34 when the cap is secured to the receptacle. An electrical circuit and electronic display, such as any of those discussed above with regard to Figures 1-4 or any other suitable circuitry and display, is mounted to the cap 36. Preferably, much or all of the electronics are provided in miniature form, e.g., on an integrated circuit chip, so as to be readily mounted to a small cap 36. In Figure 5, cap 36 is provided with an integrated circuit chip 44 defining a circuit similar to that shown in Figure 3, a red light emitting display 46 and

a blue light emitting display 48 corresponding to the red and blue light emitting devices discussed above with respect to Figure 3. The container shown in Figure 5, except for the electrodes and electronics, has an overall configuration similar to a well known contact lens container design. However, it will be understood that other suitable container configurations may be provided with electrodes and electronics in accordance with embodiments of the present invention. • When the cap 36 is secured to the receptacle 34, the electrodes 40 and 42 are at least partially submerged in the neutralization solution held in the interior of the receptacle. As a result, a circuit as shown in the schematic diagrams of Figure 3 or 4 is formed. The system operates in a manner as discussed above with respect to Figures 3 or 4. However, the system is incorporated in the lens user's contact lens storage container, providing additional convenience to the lens user. According to further embodiments of the invention, at least one of the electrodes 16, 18, 40 and 42 is made of or coated with a neutralizing catalyst. In such embodiments, a neutralization agent is added to a bath by virtue of immersing the electrodes in the bath. Embodiments as described above provide for the detection of the concentration of unneutralized disinfectant in a solution by detecting (and/or displaying) voltage or current generated by the solution in a rudimentary battery structure. Further embodiments provide for the detection of the concentration of unneutralized disinfectant in the solution by detecting the conductivity or resistivity of the solution.

In particular, the concentration of disinfectant oxidants in the solution affect the ability of the solution to conduct an electrical current. Solutions having higher concentrations of unneutralized

disinfectant oxidants will tend to have a higher conductivity (lower resistance to current flow) than solutions with lower concentrations of unneutralized disinfectants. In this regard, the relative concentration of unneutralized disinfectant in the solution can be detected or measured by detecting or measuring the relative conductivity of the solution.

This can be accomplished by, for example, connecting an external electrical power source (not shown) across electrodes immersed in the solution

(e.g., across electrodes 16 and 18 or across electrodes 40 and 42) . A current sensor (not shown) can be connected in series with the power source so as to detect or measure the magnitude of current flowing between the electrodes. However, in order for any current to flow, a conductivity path between the immersed ends of the electrodes, through the solution, must be present. The ability of the solution to conduct current will thereby affect the magnitude of current flowing between the electrodes for a particular power source output potential. Since the ability of the solution to conduct current (the conductivity of the solution) is dependent on the concentration of unneutralized disinfectant in the solution, the magnitude of current detected or measured by the current sensor can provide a detection or measurement of the concentration of unneutralized oxidant disinfectant present in the solution. Similarly, the magnitude of the voltage across the power source for a given power source current output (e.g., detected or measured by a voltage sensor connected in parallel to the power source can provide a detection or measurement of the concentration of unneutralized oxidant disinfectant in the solution. It is believed that a current flow through the solution, as desribed above, can accelerate or stimulate (or itself effect) the degradation of oxidant

in the solution. Thus, illustrated embodiments as described above can further include an external electrical power source (not shown) connected across electrodes 16 and 18 or across electrodes 40 and 42 to improve the rate of oxidant degradation in the solution. Alternatively, the power source (not shown) may be capable of effecting the oxidant degradation without the need for chemical neutralizing agents. In this regard, a power source and current sensor (or voltage sensor) arrangement as discussed above can provide both functions of accelerating, stimulating or effecting the degradation of oxidant disinfectant in the solution and monitoring the affect of the degradation. While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention.

The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, rather the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.