FR2479491A1 - PROCESS FOR REMOVING SOIL FROM THE SURFACE OF CONTACT LENSES - Google Patents

Abstract

ONE PROCESS FOR REMOVING SOIL FROM THE SURFACE OF CONTACT LENSES CONSISTS OF IMMERSING THEM IN AN AQUEOUS SOLUTION CONTAINING HYPOHALOGENOUS ACID SALT; SOIL, ESPECIALLY PROTEIN SOIL, CAN EASILY QUICKLY REMOVE.

Description

The present invention relates to a method for removing soiling which

adhere to the surface of the lenses

of contact.

  The contact lenses currently on the market fall into two groups, contact lenses which do not absorb water and contact lenses which absorb water. In these two types of contact lenses, stains such as lipids and proteins contained in the tears stick to the surface of the lenses during the period in which they are worn. Consequently, the removal of these stains sticking to the surface of the lenses poses a significant problem of handling the

contact lenses.

  When these stains are not sufficiently removed

  born, the optical properties of the lenses are altered and

  Soiling can make wearing lenses unpleasant.

  and also cause significant damage to the eye tissue.

  It is therefore necessary that, after removing the lenses, we

  quickly removes stains that stick to their surface.

  It is known that the use of a surfactant is effective in removing stains, in particular lipids

  that stick to the surface of the lenses. However, a surfactant

  active is not very effective in removing stains other than

  lipids, in particular for removing protein stains.

So when we just wash contact lenses with

  a usual cleaning solution containing a surfactant

active, stains such as proteins remain on the surface of the lenses and, when these lenses are not worn, the stains strongly stick to their surface in the form of white crystals or a thin film which impair the optical properties and by therefore greatly reduce the service life of

contact lenses.

  This trend is particularly clear in the case of water absorbing contact lenses made of a polymer whose main component is a hydrophilic monomer such as 2-hydroxyethyl methacrylate or N-vinylpyrrolidone. These water absorbing contact lenses are made of water absorbing material and, by use, the lenses are easily

  tendency to conetituetra - i * .r r ation of various micro-

organisms and it is essential to carry out steri

  boiling at regular intervals to prevent this spread. However, during the boiling treatment, stains, such as proteins adhering to the surface of the lenses, are denatured, so that they stick even more

strongly on the surface.

  Also, in addition to the well-known non-water absorbing contact lenses, mainly made of polymethacrylate

  methyl, in recent years rubber contact lenses

silicone cauldron and contact lenses made of materials

containing a silicone-type component have been marketed.

These contact lenses have a higher tendency than polymethyl methacrylate contact lenses to adsorb stains,

  such as proteins, on their surface.

It is common that, with contact lenses of all types, adhesion of stains to the surface is a problem.

  important handling, although the degree of adhesion of the soil

lures varies according to the materials of which the contact lenses are made, the state of the eye of the user, the mode of handling

and conditions of employment.

  The invention relates to a method for removing dirt from the surface of contact lenses; and a method for easily and quickly removing soil, in particular proteins, from the surface of

contact lenses.

Other characteristics and advantages of the invention

  will emerge from the description which follows.

  The Applicant has discovered that a hypo- acid salt

  halogenous is very effective in quickly removing stains, especially proteins, which stick to the surface of lenses

of contact.

  The invention relates to a method for removing dirt from the surface of contact lenses, which consists in 3. immersing a contact lens in an aqueous solution containing

a salt of hypohalogenous acid for an effective duration.

  The invention will now be described in detail.

The term "hypohalogenous acid salt" here refers to a water-soluble compound capable of producing a hypohalogenite ion

in water.

  Examples of salts of hypohalo acids

  genes used in the invention the alkali metal or alkaline earth metal salts of hypohalogenous acids such as hypochlorous acid, hypobromous acid and hypoiodous acid, for example hypochlorites, hypobromites and hypoiodites of lithium, sodium , potassium, magnesium or calcium. These hypohalogenous acid salts can be used individually or as a mixture. Among the aforementioned salts, metal hypobromites are preferred from the point of view of effectiveness.

  alkaline and alkaline earth metal hypobromites.

To clean contact lenses, the salt of hypohalogenous acid is used in the form of an aqueous solution. An aqueous solution of a hypohalogenous acid salt can be prepared in various ways, for example it is possible to use: a process (1) according to

  which is prepared and stored in a suitable container a solution

  tion of a hypohalogenous acid salt and used as such or after dilution to a desired concentration with water

distilled or purified water; a method (2) according to which

  protects a salt of hypohalogenous acid in the form of a tablet, powder or granules and, when treating contact lenses, this salt is dissolved in distilled water or purified water to prepare a aqueous solution of the hypohalogenous acid salt having the desired concentration; or a method (3) according to which a tablet, a powder or granules of a compound capable of dissolving in water, such as purified or distilled water, is used,

and produce a hypohalogenite ion.

  The above method (1) is the simplest, but an aqueous solution of a salt of hypohalogenous acid is generally

unstable and cannot be stored for an extended period of time.

  Therefore, methods (2) and (3) are more practical.

  In a typical example of method (2), when the

hypohalogenous acid salt is a calcium salt such as hypo-

calcium chlorite, it is preferably used in the form of a tablet, powder or granules. A tablet, powder or granules can also be used, in combination with potassium bromide, to produce the hypobromite ion in an aqueous solution. For example, a calcium hypochlorite tablet, powder or granules can be used in combination with an aqueous solution, a bromide tablet, powder or granules

potassium.

  As examples of compounds used in the process (3) above, there may be mentioned the sodium salt of N, N-dichlorotaurine, N, N'dichlorodimethyl-5,5 hydantoine, N-bromosuccinimide and N, Ndichloroglycine. These compounds can be used in the form of

  tablets, powders or granules.

  The amount of hypohalogenous acid salt and the duration of the contact lens immersion treatment have no effect.

  strict limitation in the invention but, in general, it is desired to

  table that the concentration of the hypohalogenous acid salt in an aqueous solution suitable for immersion treatment is understood

  between approximately 1 ppm and approximately 20,000 ppm and the duration of the treatment

  immersion is between approximately 3 min and approximately 24 h. In general, the higher the concentration of a hypohalogenous acid salt, the shorter the duration of the immersion treatment. However, in the case of treating contact lenses absorbing water, it is desirable to use a salt of hypohalogenous acid in concentrations as low as possible to remove the stains under the effect of the action. soft of the hypohalogenite ion, because the elimination of the salt of hypohalogenous acid remaining in the lenses after treatment is facilitated and an undesirable effect of the salt, such as deterioration of the material of the lenses, is avoided. For example, the water absorbing contact lenses are immersed in an aqueous solution containing about 1 to about 50 ppm of a hypohalogenous acid salt for about 3 to 24 hours. After the completion of the immersion treatment, the contact lenses are removed from the aqueous solution and the salt is removed

  hypohalogenous acid remaining from treated contact lenses.

  In the case of contact lenses that do not absorb water, the salt of hypohalogenous acid remaining on the surface of contact lenses can be easily removed by sufficient rinsing of contact lenses with water such as water. tap. In the case of water-absorbing contact lenses, it is difficult to sufficiently remove the remaining hypohalogenous acid salt, since the material of the contact lenses absorbs water. In this case, it is therefore necessary, before rinsing, to subject the contact lenses treated by immersion to a treatment rendering hypohalogenous acid harmless. The treatment rendering harmless the salt of hypohalogenous acid remaining in contact lenses absorbing water can be carried out with a reducing agent, for example an alkali metal or alkaline earth metal salt of thiosulfuric acid, such as

  than sodium thiosulfate, potassium thiosulfate and thio-

calcium sulfate, ascorbic acid or saccharides such as glucose, mannose, galactose and lactose. After completion of the immersion treatment, the contact lenses are removed from the immersion solution and immersed in an aqueous solution of a reducing agent rendering the remaining hypohalogenous acid salt harmless. One can of course, after having dipped the lenses of

contact in an aqueous solution containing a hypohalo acid salt

  generous for a sufficient period, add to the aqueous solution

  a reducing agent and dissolve it.

When saccharides such as glucose, mannose, galactose and lactose are used as the reducing agent, it can also be arranged that this reducing agent is present in an aqueous solution of the hypohalogenous acid salt at the start of the immersion treatment intended to remove stains. The reducing agent is dissolved in an aqueous solution of a hypohalogenous acid salt before the contact lens immersion treatment is carried out. In this case, the salt of hypohalogenous acid can be reduced, in other words rendering the treatment solution harmless, without harming the action of removal by the salt of hypohalogenous acid of the stains sticking to the surface of the lenses. , because the action of the salt of hypohalogenous acid on the reducing agent is slower than the action on the stains. This procedure is therefore particularly desirable, as it prevents contact lenses from being damaged by a

  too long stay in the treatment solution.

  The quantity of reducing agent does not pose any particular problem, provided that a reducing agent is used in an amount sufficient to react with all of the acid salt

hypohalogenous used.

  After rendering the hypohalo acid salt harmless

  generous or its aqueous solution, the contact lenses are sufficiently rinsed with a physiological saline solution at 0.9% by weight

  so that the lenses can be worn without any problem.

  The invention is illustrated by the following nonlimiting examples.

EXAMPLE 1

Protein stains are made to adhere to water absorbing contact lenses (trade name "MENICON SOFT" manufactured by Toyo Contact Lens Co., Ltd.) in the following manner:

  five contact lenses in 100 ml of an aqueous solution

1 g of lysozyme and 0.9 g of sodium chloride dissolved in distilled water for 6 h, then the lenses are removed from the aqueous solution and rinsed with a small amount of physiological salt water. Each lens is placed in a container containing 1 ml of physiological salt water, the containers are closed with a stopper and heated to boiling for 15 min. The contact lenses are removed from the containers and their surface is cleaned with a contact lens puff (trade name "NEWCLEAN PUFF" manufactured by Toyo Contact Lens Co., Ltd.) and cleaning fluid (trade name "MENI CLEAN" made by Toyo Contact

Co., Ltd.). This cleaning is repeated seven times for each lens.

  It is confirmed that each lens is completely covered with a

  white protein film, i.e. lysozyme.

The contact lenses thus soiled are immersed in 5 ml of aqueous solution at 4 ppm, 10 ppm, 20 ppm, 30 ppm or ppm of sodium hypochlorite for 16 h. The degree of elimination of the stains is observed with a stereoscopic microscope (type NMTrd stereoscopic microscope with black background manufactured by

OLYMPUS OPTICAL COMPANY LIMITED).

  In the case of treatment with aqueous solutions at 30 ppm and 50 ppm, the stains are completely eliminated from the lenses which regain their transparency. In the case of treatment with the 20 ppm aqueous solution, some stains remain

on the surface of the lens. In the case of treatment with the solu-

  tion at 4 ppm and 10 ppm, more than half of the stains remain. However, aqueous solutions of sodium hypochlorite at low concentrations, that is to say at 4 ppm, 10 ppm and 20 ppm, remain effective in practice when the periodic treatment is carried out to avoid adhesion of the stains to the surface of

water absorbing contact lenses.

EXAMPLE 2

  The elimination of soiling is studied as follows

  Protein lures by the hypobromite ion produced by reaction of bro-

ripe potassium and calcium hypochlorite in distilled water: immerse in an aqueous solution of 20 g of potassium bromide dissolved in 10 ml of distilled water five contact lenses that do not absorb water (non-commercial "MENICON 02" manufactured by

  Toyo Contact Lens Co., Ltd.) contaminated with protein and available

  sout in the aqueous solution 25 mg of calcium hypochlorite with 61% of active chlorine. After 5 min, the lenses are removed and washed sufficiently with tap water. We observe the surface condition of the

  lenses with a stereoscopic microscope.

For all contact lenses, soiling is removed and the lenses return to their original transparency.

EXAMPLE 3

As described in Example 2, contact lenses absorbing water similar to those used in

Example 1.

  After having allowed the calcium hypochlorite to dissolve for 5 min, the five lenses are sufficiently rinsed with physiological saline water at 0.9% and the degree of removal of the stains is observed with a stereoscopic microscope. For all contact lenses, soiling is removed and the lenses

are transparent.

  This process is suitable for the rapid removal of soil.

  lures on the surface of contact lenses in an ophthalmic hospital

logic or an optician.

EXAMPLE 4

Five water-absorbing contact lenses similar to those used in Example 1, the surface of which has been contaminated with proteins and 25 mg of calcium hypochlorite containing 61% active chlorine are dissolved in the aqueous solution. After 2 h, we remove

  the lenses and they are rinsed sufficiently with phy salt water

0.9% siological. We observe with a stereoscopic microscope the

degree of soil removal.

  The surface of all contact lenses thus treated does not present any stains and the lenses have their original transparency. Also, after 2 h, we do not observe the

presence of hypohalogenite ions in the aqueous treatment solution.

EXAMPLE 5

To prepare a processing liquor, 30 mg is added

  of N, N'-dichlorodimethyl-5,5-hydantoin, 25 mg of potassium bromide-

sium and 50 mg of sodium carbonate to 10 ml of distilled water and stirred vigorously. Five non-water-absorbing contact lenses similar to those used in Example 2, whose surface is contaminated with a protein, are immersed in the treatment liquid for min. And the condition of the surface of the lenses is examined as described. in Example 2. All the contact lenses thus treated are free from dirt on their surface and have

their original transparency.

  Of course, various modifications can be made by a person skilled in the art to the devices or processes which have just been described solely by way of nonlimiting examples.

without departing from the scope of the invention.

o

R E V E N D I CA T 1 0 N S

  1. A method for removing dirt from the surface of contact lenses, characterized in that it consists in immersing a contact lens in an aqueous solution containing a salt of hypohalogenous acid for an effective period. 2. Method according to claim 1, characterized in that the hypohalogenous acid salt is at least one element of the group consisting of the alkali metal salts and the alkaline earth metal salts of hypochlorous acid, of acid hypobromous

and hypoiodous acid.

  3. Method according to claim 1, characterized in that

  the salt of hypohalogenous acid is a compound soluble in water capa-

  ble to produce a hypohalogenite ion, this compound being chosen from

  the sodium salt of N, N-dichlorotaurine, N, N'-dichlorodimethyl-

5.5 hydantolin, N-bromosuccinimide and N, N-dichloroglycine.

4. Method according to claim 1, characterized in that

  that, after immersion, the contact lenses are rinsed with water.

5. Method according to claim 1, characterized in that

  that contact lenses are contact lenses do not absorb

  not water and in that they are treated with a reducing agent

  after immersion to make the hypohalo acid salt harmless

generous remaining.

  6. Method according to claim 1, characterized in that the contact lenses are contact lenses absorbing water and in that the aqueous solution contains a saccharide as

reducing agent.