WO2005031443A1

WO2005031443A1 - Contact lens with a cosmetic effect

Info

Publication number: WO2005031443A1
Application number: PCT/IT2003/000591
Authority: WO
Inventors: Alessandro Filippo
Original assignee: Safilens S.R.L.
Priority date: 2003-10-01
Filing date: 2003-10-01
Publication date: 2005-04-07
Also published as: AU2003279518A1

Abstract

A contact lens (1) is described which comprises an optical body (3) in which a plurality of reflective particles (2) are dispersed; at least 75% of the particles have dimensions distributed variously between 10 and 60 microns.

Description

Contact lens with a cosmetic effect

DESCRIPTION

Technical field of the invention The present invention relates to a contact lens with a cosmetic effect according to the preamble to the main claim. Technological background of the invention In the technical field in question, there are known cosmetic contact lenses which are intended mainly for young people and which comprise an optical body made of polymer material in which reflective particles are dispersed, the purpose of which is to produce a sparkle effect in the lens when it is struck by light. Lenses of the type indicated are known, for example, from International patent application No. 02/31585 in the name of Novartis, which describes a contact lens in which reflective particles (known as in the field as "glitters") having an average diameter of at least 100-120 microns are incorporated. However, lenses of this type are subject to some important production limitations. Although, on the one hand, the particles must in fact have dimensions large enough to produce an appreciable optical sparkle effect, on the other hand, these dimensions cause a great deal of trouble at the production stage, as explained further below. A first response to the consequent need to minimise the dimensions of the reflective particles as far as possible is contained in the Applicant's International patent application No. PCT/IT03/00156 which provides for the use of prismatic reflective particles which are characterized in that they have finely faceted reflective surfaces in order to reflect and refract incident light at different angles. They are much more effective than conventional glitters and thus, for a given aesthetic effect achieved, permit the use of particles having smaller average dimensions, of the order of 70-80 microns. Lenses containing dispersed glitters having dimensions smaller than those indicated above with reference to conventional and prismatic glitters have not shown any appreciable aesthetic effect. However, even the solution with prismatic reflective particles does not completely overcome the limitations mentioned above with reference to the production of the lenses, in particular of disposable lenses. In fact, to ensure a high degree of comfort, these lenses are very thin, generally with a thickness of between 80 and 150 microns for a lens with zero dioptric power. Given that the dimensions of the lens and of the reflective particles (even prismatic particles) incorporated therein are comparable, in order to ensure that no particles project from the surfaces of the lens, it is necessary to carry out extremely careful checking of the individual lenses, with a clear increase in production costs, or to produce thicker lenses, thus detracting from the user's comfort. Moreover, these lenses must be mass-produced, preferably by moulding, in order to be economically favourable. Description of the invention The problem underlying the present invention is that of providing a contact lens with a cosmetic effect, which is designed structurally and functionally to overcome the limitations discussed above with reference to the prior art mentioned. Within the scope of this problem, a principal object of the invention is to provide a contact lens which can be produced on an industrial scale at low cost. A further object is to permit the production of soft contact lenses, in particular of the disposable type, that are intended especially for vision in poor light conditions. Another object is to provide a contact lens which can confer on the user's eyes a novel aesthetic impact which is less artificial than that of known lenses but which does not adversely interfere with the user's vision (particularly with peripheral vision) or cause eye irritation. This problem is solved and these objects are achieved by the invention by means of a contact lens with a cosmetic effect formed in accordance with the appended claims. Brief description of the drawings The characteristics and the advantages of the invention will become clearer from the detailed description of a preferred embodiment thereof which is described by way of non-limiting example with reference to the appended drawing in which Figure 1 is a perspective view of a lens formed in accordance with the present invention.

Preferred embodiment of the invention With reference to the single appended drawing, a contact lens formed in accordance with the present invention is generally indicated 1. Preferably, the lens 1 is disposable and has a thickness of between 80 and 150 microns. It may also have properties for correcting visual defects such as, for example, myopia, hypermetropia, or astigmatism. In this context, the term "disposable" indicates a soft contact lens for frequent replacement, for example, daily, weekly or monthly replacement. The lens 1 comprises an optical body 3 produced by moulding with the use of polymer materials which are conventional per se within the technical field in question, such as HEMA or derivatives thereof. A convex surface 4, a concave surface 5, and an iris region 6 which is superimposed on the user's iris in use are defined in the optical body 3. A plurality of reflective particles, all indicated 2, are dispersed in the optical body 3 and are fully incorporated within the optical body 3 so as not to come into contact with the user's eye and to prevent undesired eye irritation.

It should be noted that, in the drawing, for greater clarity, the dimensions of the particles 2 are deliberately exaggerated in comparison with those of the lens. The particles 2 are preferably provided in the optical body 3 purely in the iris region 6 so that they do not adversely affect the visual capacity of the lens 1 but, in order to achieve a different cosmetic effect, they may also be provided in an annular region 7 outside and around the iris. According to a principal characteristic of the invention, the reflective particles 2 have dimensions such that at least 75% have dimensions distributed between 10 and 60 microns. It has in fact been found that, with the use of reflective particles having dimensions that are distributed over a relatively large range of values, an unexpected synergic effect is achieved between the particles; this effect can enhance the luminosity characteristics of the particles and confer a novel aesthetic effect on the lens 1. This advantageously permits the use of particles of generally smaller dimensions, the average of which is between 20 and 40 microns, preferably between 25 and 30 microns, as against the 70 - 80 microns or 100 - 120 microns which are necessary to achieve an adequate sparkle effect with glitters (prismatic or conventional, respectively) having substantially uniform dimensions. With the use of particles having the dimensional distribution of the present invention, the sparkle of the fraction of particles with larger dimensions is clearly perceptible by virtue of the presence of the fraction of particles with smaller dimensions which create a kind of "metallized" background of the lens 1. As well as conferring on the lens 1 a general effect of three-dimensionality and depth so as to give the impression that the reflective particles are disposed directly on the iris, this background accentuates the light reflected by the particles with larger dimensions which, otherwise, would not be perceptible in normal conditions. In particular, tests carried out by the Applicant have shown good results with lenses in which the particles had the following dimensional distribution:

- particles with dimensions of between 15 and 25 microns: 45% - 55%,

- particles with dimensions of between 25 and 35 microns : 25% - 35%, - particles with dimensions of between 35 and 50 microns: 10% - 20%,

- particles with dimensions of less than 15 microns or more than 50 microns: less than 10%. The best results were obtained with lenses in which the particles had the following dimensional distribution: - particles with dimensions of between 15 and 25 microns: about 50%,

- particles with dimensions of between 25 and 35 microns: about 30%,

- particles with dimensions of between 35 and 50 microns: about 15%, - particles with dimensions of less than 15 microns or more than 50 microns: less than 5%. The fraction of particles having dimensions of between 15 and 25 microns constitutes the above-mentioned "metallized" background on which the sparkle of the fraction with larger dimensions stands out and, in order for its presence to be effective, should not be less than 40%. The reflective particles 2 are preferably produced by a process of pulverization of conventional glitters and each particle consequently has a generally irregular shape. As a result, the dimension attributed to each particle is necessarily an averaged value of the various dimensions thereof that can actually be measured. The starting glitters are preferably made of heat-resistant material suitable for use in a moist/aqueous environment. They are typically produced from films, for example metallized or otherwise treated polyester films, and may be of various colours although the preferred colours are gold and silver. The lens 1 is manufactured by means of a first moulding step in which a first layer of the optical body 3 is formed, a second step in which the desired quantity of reflective particles 2 is arranged preferably on the concave surface of the optical body 3, and a third step in which a second layer of the optical body 3 is applied, again by moulding, to cover the reflective particles 2. It should be noted that, by virtue of the small dimensions of the particles 2, they can easily be incorporated in the polymer material constituting the two layers of the optical body 3, without the need for increased thicknesses of the lenses or additional checks. Although the example described above relates to a disposable lens, the invention may be applied in similar manner to conventional soft contact lenses (for example, for yearly replacement) or to hard or semi-hard lenses, as will be clear to a person skilled in the art. Similarly, the lens may be made by a turning process instead of by moulding. The invention thus achieves the objects proposed, also affording many advantages over the known solutions cited above, amongst which is the fact that these contact lenses can be mass-produced with low production costs. A further advantage is that, by virtue of the very small average dimensions of the particles used, these lenses have an insignificant impact on the user's peripheral vision, even when the pupil is in a condition of maximum dilation and the particles are arranged on the iris region of the lens. This characteristic is very important, bearing in mind the most likely type of use for lenses of this kind. In fact they are destined particularly for use in poorly lit environments such as discotheques or night clubs in which, as the pupil dilates, it may suffer from the presence of opaque bodies directly on its periphery. A further advantage is that the aesthetic effect achieved by the contact lens according to the invention is entirely novel and characteristic in comparison with known cosmetic lenses.

Claims

1. A contact lens with a cosmetic effect, comprising an optical body (3) in which a plurality of reflective particles (2) are dispersed, characterized in that at least 75% of the particles have dimensions that are distributed variously between 10 and 60 microns.

2. A lens according to Claim 1 in which the average of the dimensions of the particles is between 20 and 40 microns.

3. A lens according to Claim 2 in which the average of the dimensions of the particles is between 25 and 30 microns.

4. A lens according to one or more of the preceding claims in which a fraction of at least 40% of the particles has dimensions of between 15 and 25 microns.

5. A lens according to one or more of the preceding claims in which the fraction of particles having dimensions of between 15 and 25 microns is between 45% and 55%, the fraction of particles having dimensions of between 25 and 35 microns is between 25% and 35%, the fraction of particles having dimensions of between 35 and 50 microns is between 10% and 20%, and the fraction of particles having dimensions of less than 15 microns or more than 50 microns is less than 10%.

6. A lens according to Claim 5 in which the fraction of particles having dimensions of between 15 and 25 microns is about 50%, the fraction of particles having dimensions of between 25 and 35 microns is about 30%, the fraction of particles having dimensions of between 35 and 50 microns is about

15%, and the fraction of particles having dimensions of less than 15 microns or more than 50 microns is less than 5%.

7. A lens according to one or more of the preceding claims in which the particles (2) are dispersed in an iris region (6) defined on the optical body (3).

8. A lens according to one or more of the preceding claims in which the particles (2) are dispersed in an annular region (7) surrounding an iris region

(6) defined on the optical body.

9. A lens according to one or more of the preceding claims in which the reflective particles (2) are produced by a process of pulverization of conventional "glitters".

10. A lens according to one or more of the preceding claims in which the overall thickness of the lens is between 80 and 150 microns.

11. A lens according to one or more of the preceding claims which is of the disposable type.