FR2584503A1 - Method for sterilising contact lenses - Google Patents

Abstract

The invention relates in particular to a method for processing a soft or hard contact lens in order to clean it, sterilise it and process it before application to the eye, characterised in that: - the said lens is placed in a sterilising solution comprising a solution of peracetic acid in hydrogen peroxide for a period of time ensuring in practical terms its sterilisation, - then the sterilising solution is removed from the lens, and - optionally, the lens is kept in a saline solution. r

Description

 The present invention relates to a method of treating contact lenses for cleaning and sterilization.

 Soft hydrophilic contact lenses have advantages over the so-called "hard" lenses, particularly with regard to the considerable possibilities of accommodation and wearing comfort, which need not be repeated here.

 However, they have the drawback of having to be cleaned regularly to eliminate the fouling of their surface dd to the electrostatic charges carried by the polymers which constitute them; this fouling constituting a culture medium favorable to the development of microorganisms.

Currently, for the maintenance and sterilization of flexible hydrophilic contact lenses, a solution of hydrogen peroxide at 38 (10 volumes). The use of hydrogen peroxide has many advantages, in particular this solution does not require the use of preservatives such as Chlorhexidine or
Thimerosol which present toxic or allergic risks and can contribute to the fixation of deposits on lenses.

 In addition, it avoids the use of thermal decontamination, the heat having the disadvantage of fixing the deposits of the lenses badly cleaned beforehand and of aging the lenses. The decontamination rate adopted to avoid these drawbacks, that is to say generally once a week, is clearly insufficient to avoid infectious complications. Thermal decontamination alone is generally insufficient and requires additional washing using surfactants and proteolytic enzymes.

 The use of hydrogen peroxide, simple, allows a cleaning superior to that of the other methods and a daily decontamination. It also prevents the lenses from yellowing as they age.

 However, the users of soft contact lenses often complain, in the case of the use of hydrogen peroxide, of the soaking times necessary to ensure sterilization which are approximately of the order of 20 minutes minimum because the antimicrobial activity hydrogen peroxide is weak and requires that this fairly long contact time be used.

 There are three types of methods currently used most commonly.

 First of all, the so-called flsepticonfl system (proposed by American Optical and Alcon-Medicornéa) which consists in soaking the lentils in hydrogen peroxide for 20 minutes in the evening then in a 9 0 / oxo saline solution in the presence of a metallic catalyst (based on platinum) the rest of the night.

 The main disadvantages of this method are, in addition to waiting 20 minutes in the evening to ensure sterilization, the fact that there is always a certain amount of hydrogen peroxide which is responsible for tingling in about one subject in 10.

 This is partly due to the rather poor efficiency of the metal catalyst used to decompose hydrogen peroxide, which must be replaced every three months.

 In addition, this process requires the use of a second special case for decomposition which is quite difficult to clean and cannot be sterilized in practice.

 The second system is the so-called "Lensan" system (marketed by Giefer). It consists of soaking the lentils overnight in hydrogen peroxide and then 10 minutes in the morning in a 9 O / oo saline solution containing a biocatalyst, in this case a catalase.

 This system provides better decontamination given the longer contact time with hydrogen peroxide and it seems that the removal of hydrogen peroxide before laying is better, but the long duration of soaking can deform certain lenses.

 The third system called "Oxycase" (marketed by Essilor-Contapharm) replaces the metallic or biological catalyst mentioned above by rinsing under a stream of tap water after soaking for 20 minutes in the evening in hydrogen peroxide and before soaking overnight in 9 O / oo saline solution.

 Again, we find the same drawback, namely, a 20-minute wait in the evening and the use of a second case.

 The present invention provides a method of treating a contact lens which makes it possible to avoid most of the drawbacks mentioned above.

More particularly, it is a method of treating a contact lens with a view to cleaning, sterilizing and treating it before it is placed in the eye, characterized in that
- Said lens is placed in the presence of a sterilization solution comprising a solution of peracetic acid in hydrogen peroxide for a period practically ensuring its sterilization;
- then, the sterilization solution is eliminated from the lens and the lens is possibly stored in a saline solution.

The sterilization solution can be disposed of in different ways, including
- by a flow of water such as tap water, or
- by the action of a biocatalyst degrading the active ingredients such as an enzyme, peroxidase or catalase.

 Preferably, the sterilization solution consists only of a solution of peracetic acid in hydrogen peroxide, this sterilization solution having an oxidizing power corresponding approximately to that of a solution of hydrogen peroxide whose concentration is 2 to 5%, preferably of the order of 2 to 3%.

 In the present description, and unless otherwise indicated, the hydrogen peroxide concentrations are given in percentage by weight / weight and the peracetic acid concentrations are given in ppm by weight.

 In a preferred embodiment of the method according to the present invention, the sterilization solution will contain 2 to 3% of hydrogen peroxide, preferably 2.7 to 2.8% of hydrogen peroxide, and 100 to 200 ppm of peracetic acid, preferably from 120 to 160 ppm of peracetic acid.

 The sterilization solution according to the invention may also contain a compound intended to reduce the acid odor of the solution, for example a nonionic surfactant usable in pharmacy or cosmetology.

The method according to the invention can be implemented as follows
A) Neutralization by tap water flow (12 minutes)
1) Massage-soaking of each lens in the palm of the hand with the solution according to the invention for 1 minute.

 Rinse each lens 30 seconds under the flow of tap water.

Soaking
either in serum (buffered or not) with a
non-irritant preservative (sorbic acid by
example)
either in serum (buffered or not) without
conservative.

 2) Massage each lens in the palm of the hand with the solution according to the invention for 20 seconds.

 Rinse under tap water.

 Soaking in the case containing the solution according to the invention for 1 minute.

 Rinsing of the lenses contained in the lens holder cap 1/2 minute under the tap water flow.

 Soaking in serum (buffered or not) without preservative (the case having been sterilized by the solution).

 3) Soaking and stirring of the lenses in a case allowing them to be stirred in the solution according to the invention for 1 minute.

 Rinsing of the lenses contained in the case 1/2 minute under the tap water flow.

 Soaking in serum, without preservative, as in the previous case.

 4) Soaking the lenses in their case containing the solution according to the invention, the case placed in an ultrasonic device for approximately 3 minutes.

 Rinsing of the lenses contained in the case 1/2 minute under the tap water flow.

 Soaking in preservative-free serum, as above.

B) Neutralization with a solution containing a
biocatalyst (catalase or peroxidase)
5) Massage-soaking of each lens in the palm of the hand with the solution according to the invention for 1 minute.

 Soaking in a solution containing a biocatalyst, from 5 minutes to overnight, in an autosterile case.

 Or, soak in a solution containing a biocatalyst, for 5 minutes, then soak in serum with preservative.

 6) Cleaning and sterilization as in 2, 3 or 4.

 Soaking in a solution containing a biocatalyst, from 5 minutes to overnight.

 Of course, most of the time, in order to recondition the lens, it will, after these various steps, be preserved in a saline solution 9 O / oo (buffered or not) overnight, for example.

 Of course, the durations indicated above are only orders of magnitude and can be increased without harming sterilization.

Tests carried out with a sterilization solution containing
. hydrogen peroxide, 2.76%
. peracdtic acid, 128 to 150 ppm,
pH: 2.6 have made it possible to demonstrate the considerable advantages of the process according to the present invention.

In particular, a preliminary comparative study carried out using the preceding product but diluted to 1/10 (v / v) and hydrogen peroxide at 3% (v / v) has shown that the lenses sterilized by the process of the present invention fulfilled for example the conditions implied by standard AFNOR T 72151 for three strains, namely
Pseudomonas aeruginosa, CNCM A 22
Streptococcus faecalis, ATCC 10541
Klebsiella pneumoniae, ATCC 10031, while the lenses sterilized with 3% hydrogen peroxide were not sterile for the three strains considered. Sterilization is also very complete since peracetic acid is described as having fungicidal, sporicidal and even antiviral activity.

 In addition, the toxicological and irritation study on the eye showed that in a situation approaching normal use, that is to say even after 10 minutes of soaking in the sterilization solution (i.e. 10 times more than the time necessary to ensure good sterilization) and rinsing under the flow of water from a distilled water tap, only 4 ppm of acetic acid remains.

 The residues of hydrogen peroxide observed are, moreover, roughly equivalent to those of the other methods.

 Even in the case of a false maneuver, that is to say of a lens put in place before rinsing and immediate removal of the lens due to the pain, the irritant effect is not greater than that of the hydrogen peroxide alone. Indeed, a drop of a solution of peracetic acid diluted to 400 ppm instilled in the eye of the rabbit does not cause irritation, however, the solution is three times more diluted (from 100 to 200 ppm) and the lens the thickest (strong hydrophilicity, power of 15 diopters) contains less than a drop.

 Tests carried out on the rabbit have shown that, even after 2 minutes, the irritation was not more important than for H2O2 - 10 volumes.

 Given the high acidity of peracetic acid, it was feared that this product would affect the properties of the materials making up the flexible hydrophilic lens.

 This is why tests have been continued in order to demonstrate the activity of the sterilizing solution on polyHEMA-based lenses.

 To do this, 6 lenses containing 38% of HEMA were used which were placed in a sterilization solution for 16 days, the sterilization solution being renewed every day. For comparison, 6 identical lenses were placed in a saline solution.

 The studies carried out on the two batches of lenses after this treatment have shown that there was no significant difference in the mechanical properties of the lenses of the two groups, similarly, it has been possible to highlight the fact that it there was no change in dimensions, refractive index or elastic deformation.

 Only strongly hydrophilic lenses placed in the presence of the solution shrink after soaking for 48 hours; this is not unexpected given the acidity of the solution used. However, these lenses, after rinsing, return to their original size by soaking in a buffer solution.

 The method according to the present invention therefore makes it possible to obtain more complete sterilization of the lenses under much simpler and faster conditions without the mechanical, physical and optical qualities of the lenses being affected.

Claims (15)

 1) Method for treating a contact lens for cleaning, sterilizing and treating it before placing it in the eye, characterized in that  - Said lens is placed in the presence of a sterilization solution comprising a solution of peracetic acid in hydrogen peroxide for a period practically ensuring its sterilization;  - then the sterilization solution is eliminated from the lens and the lens is possibly stored in a saline solution.  2) Method according to claim 1, characterized in that the sterilization solution consists only of a solution of peracetic acid in hydrogen peroxide.  3) Method according to one of claims 1 and 2, characterized in that the sterilization solution has an oxidizing power corresponding to that of a solution of hydrogen peroxide whose concentration is 2 to 5%.  4) Process according to claim 2, characterized in that the sterilization solution contains from 2 to 3% of hydrogen peroxide and from 100 to 200 ppm of peracetic acid.  5) Method according to claim 4, characterized in that the sterilization solution contains 2.7 to 2.8% of hydrogen peroxide and 120 to 160 ppm of peracetic acid.  6) Method according to one of claims 1 to 5, characterized in that the sterilization solution is removed by rinsing with water.  7) Method according to one of claims 1 to 5, characterized in that the sterilization solution is eliminated by placing in the presence of a biocatalyst.  8) Method according to claim 7, characterized in that the biocatalyst is a catalase or a peroxidase.  9) Method according to one of claims 1 to 7, characterized in that the lens is placed in the presence of the sterilization solution under conditions ensuring circulation of said solution around the lens.  10) Method according to one of claims 1 to 6, characterized in that the rinsing is carried out by maintaining the lens under a flow of water.  11) Method according to one of claims 1 to 10, characterized in that the treated lens is a hydrophilic lens based on an HRMA polymer.  12) Sterilization solution for contact lenses, characterized in that it contains 2 to 5 8 of hydrogen peroxide and 100 to 200 ppm of peracetic acid.  13) Solution according to claim 12, characterized in that it contains 2 to 3% of hydrogen peroxide.  14) Solution according to claim 13, characterized in that it contains 2.7 to 2.8% hydrogen peroxide and 120 to 160 ppm of peracetic acid.  15) Solution according to one of claims 12 to 14, characterized in that it additionally contains a nonionic surfactant.