WO2008155612A1

WO2008155612A1 - A method for humidifying a contact lens

Info

Publication number: WO2008155612A1
Application number: PCT/IB2008/001473
Authority: WO
Inventors: Alessandro Filippo
Original assignee: Alessandro Filippo
Priority date: 2007-06-19
Filing date: 2008-06-09
Publication date: 2008-12-24
Also published as: ITPD20070208A1

Abstract

A method for humidifying a contact lens provides for the application of a liquid solution to a contact lens positioned on an eye of a user, wherein the liquid solution is applied to the contact lens by spraying.

Description

A METHOD FOR HUMIDIFYING A CONTACT LENS Description Technical Field

The present invention relates to a method for humidifying a contact lens, having the features set forth in the preamble of the main claim. It is also directed to a kit comprising at least one contact lens and a spray device, as set forth in the preamble of the independent claim 9. Technological Background The present invention is applicable to all types of contact lens but is preferably applied to soft contact lenses. These are composed of a solid matrix which is generally constituted by a polymer having high hydrophilic properties and in which a liquid component is dispersed in a relatively large amount of, for example, from 20% to 80% with respect to the total weight of the lens. The liquid component is typically composed of a 0.9% sodium chloride solution in purified water, generally known as a physiological solution or saline solution.

The fraction of liquid component present in the contact lens, in addition to improving the wearability characteristics of the lens, also contributes to the correct definition of the geometrical and optical properties thereof. It is therefore necessary for the liquid component of the lens always to be maintained at the intended levels, compensating for any losses of liquid with suitable humidifying. There is also a requirement to maintain correct humidifying of the lens in other types of lens, for example in silicone-based contact lenses, which have a coating or surface treatment which renders them hydrophilic. Losses of liquid fraction attributable to evaporation phenomena take place when the contact lens is in position on the user's eye, for example, in particular climatic situations, such as excessive wind, excessive exposure to the sun or excessive heat, or in air-conditioned or heated environments, or also in conditions of visual stress caused, for example, by the intensive use of a video terminal.

In these situations, often in open environments or at any rate not in the home, the user has to carry out a humidifying of the contact lenses. According to a first known method, this operation may consist in removing the contact lens from the eye and immersing it in a saline solution for a predetermined time, or applying to the contact Jens a few drops of saline solution, always after having removed it from the eye. However, this procedure involves the necessity of removing the lenses from the eye. This is an aspect which is particularly undesirable for the user because it is often not easy and is a potential source of hygiene problems (for example, the fact that the operation is often carried out in places where it is not possible to wash the hands satisfactorily) and, moreover, there is the not inconsiderable risk of dropping on the ground the lens which has been removed and soiling or even losing it. An alternative method provides for the application of a few drops of saline solution directly to the contact lens positioned on the eye. Although this obviates the necessity to remove the contact lens, the operation is often particularly uncomfortable for the user, as well as potentially dangerous owing to the possibility of contact between the eye and the mouth of the container of the liquid solution. In addition, this method has the disadvantage of introducing into the eye a large amount of liquid which may cause the displacement of the contact lens from its correct position, apart from the fact that a large proportion of the saline solution immediately escapes from the eye,

Description of the Invention The object of the present invention is to provide a method which is devised functionally to overcome the limits explained above with reference to the mentioned prior art.

That object is achieved by the present invention by a method for humidifying contact lenses carried out in accordance with the claims, which follow.

Brief Description of the Drawings

The features and advantages of the invention will emerge more clearly from the detailed description of a preferred embodiment thereof which is illustrated by way of non-limiting example with reference to the appended drawing in which the single Figure 1 is a diagrammatic view of an operative stage of the method for humidifying a contact lens according to the present invention.

Preferred Embodiment of the Invention

As illustrated in the Figure, the method described here provides that a contact lens 1 is moistened while it is in position on an eye 2 of the user, thus avoiding all of the complications mentioned above caused by any removal thereof.

According to a first aspect of the present invention, it is provided that the contact lens 1 is moistened by applying a liquid solution 3 thereto by spraying. To that end, the liquid solution 3 is advantageously contained within a spray device 4, by acting on which the user is able to bring about the delivery of a defined amount of liquid solution 3 through a nozzle 5 of the spray device 4.

In particular, it is desirable for the spray to be directed towards the contact lens 1 in such a manner as to cover the entire surface thereof, endeavouring at the same time not to affect areas outside the eye 2, thus limiting to the maximum extent any possible losses of liquid solution. The parameters contributing to achieving this effect are the distance from which the liquid solution 3 is sprayed towards the eye 2 and the angulation at which the liquid solution 3 is emitted from the nozzle 5.

The first parameter is preferably selected in such a manner that the spray device 4 is sufficiently close to ensure that the spray is directed accurately without, however, running the risk of coming into contact with the eye 2, even if only accidentally. On the basis of the above considerations, the distance at which the spray device 4 is preferably held during the stage of spraying the liquid solution 3 is from approximately 30 to approximately 150 mm.

On the basis of the above-mentioned distance, the nozzle 5 of the spray device 4 is dimensioned in such a manner as to spray the liquid solution 3 at an angulation of from approximately 5° to approximately 20°.

The liquid solution 3 is any substance in liquid form capable of humidifying the contact lens 1.

It should be mentioned that the expression "liquid solution", as used in the present context, is not limited to the strictly chemical definition of "mixture in completely homogeneous liquid phase" but extends to its more general meaning, which is moreover usual in the technical field of reference, of "liquid mixture", and therefore also includes emulsions and suspensions in liquid phase.

Since it is desirable for contact between the liquid solution 3 and the eye 2 to cause as little discomfort as possible, it is preferable for the liquid solution 3 to have a composition which is as similar as possible to that present on the ocular surface on which the contact lens 1 is positioned. For example, in a first preferred embodiment of the present method, it is provided that the liquid solution 3 is formed from purified water in which 0.9% sodium chloride is dissolved (physiological solution).

More preferably, it is also provided that the liquid solution 3 is formed from a lachrymal substitute, that is to say, from an aqueous solution containing an effective amount of compounds, typically polymers, that confer on the liquid solution chemico-physical properties that are as similar as possible to those of natural tears.

Polymers of this type are already knςwn in the field of ophthalmic treatments and include polysaccharides and the derivatives thereof, such as dextrans, galactoxyloglucans and glucosaminoglycans. Of these, hyaluronic acid and the derivatives thereof, or galactoxyloglucan extracted from tamarind seed (abbreviation TSP) are especially preferred.

The amounts of polymer present in the aqueous solution are calibrated in accordance with the specific chemico-physical characteristics desired, for example the percentage of hyaluronic acid (in the form of the sodium salt) or of TSP may be from 0.1% to 1%. Still with the aim of minimizing the sensory impact on the eye of the liquid solution sprayed towards the lens, it is advantageous if the size of the droplets is as small as possible, as far as allowed by the opposing requirement of keeping substantially all of the sprayed liquid solution within a predefined spray angle (in order to prevent it affecting in an uncontrolled manner a surface which is much larger than the exposed surface of the contact lens 1).

The liquid solution 3 is preferably contained inside the spray device 4 without the addition of propellants, in order to prevent such substances from coming into contact with the eye 2. In addition, the liquid solution 3 is advantageously free from preservatives, which are not necessary in the case of a spray-type application given that the liquid solution is closed off in an almost hermetic manner from the external environment. In a completely surprising manner, it is found that the spray application of the liquid solution 3 to the contact lens 1 while the latter is in position on the eye 2 does not cause any appreciable or substantial sensation of discomfort to the user.

This result is undoubtedly unexpected because it is known that spraying a liquid substance directly into the eye is generally very uncomfortable for the user, to the extent that these substances (for example eye-washes or artificial tears) are typically applied in drop form.

A possible explanation for this phenomenon consists in the fact that the contact lens 1 towards which the humidifying action is directed acts substantially as a shield for the subjacent corneal area of the eye which is extremely rich in nerve endings and therefore particularly sensitive to contact and temperature variation.

Advantageously, the liquid solution 3 is supplied inside the spray device 4 and can be sold separately or together with the contact lenses. The present invention thus achieves the object discussed above with reference to the mentioned prior art.

Claims

1. A method for humidifying a contact lens, which provides for the application of a liquid solution to a contact lens positioned on an eye of a user, characterized in that the liquid solution is applied to the contact lens by spraying.

2. A method according to claim 1, wherein the liquid solution is sprayed on to the contact lens at a spray angle of from 5° to 20°.

3. A method according to claim 1 or 2, wherein the liquid solution is sprayed on to the contact lens from a distance of from 30 mm to 150 mm.

4. A method according to one or more of the preceding claims, wherein the liquid solution is a lachrymal substitute.

5. A method according to claim 4, wherein the liquid solution comprises an amount of hyaluronic acid or the derivatives thereof of from 0.1% to 1%.

6. A method according to claim 4, wherein the liquid solution comprises an amount of galactoxyloglucan extracted from tamarind seed of from 0.1% to 1%.

7. A method according to one or more of the preceding claims, wherein the liquid solution is free from propellants.

8. A method according to one or more of the preceding claims, wherein the liquid solution is free from preservatives.

9. A kit comprising at least one contact lens and a liquid solution for humidifying the same, characterized in that it comprises a spray device for spraying the liquid solution on to the contact lens when the latter is in position on an eye of a user.