CONTACT LENS AND METHOD FOR THE PRODUCTION OF A CONTACT LENS

Abstract

A contact lens (1) comprises an optical zone (5) extending with a first diameter (A) about an optical axis (X) of the lens, and is provided with a first dioptric power and a central region (6), extending about the optical axis (X) with a second diameter (B), smaller than the first diameter, inside which is provided an optically inactive zone (7) with a diameter smaller than 0.5 mm.

Claims

1. A contact lens (1) comprising: an optical zone (5) extending with a first diameter (A) about an optical axis (X) of said lens and provided with a first dioptric power, and a central region (6), inside and contiguous with said optical zone (5), extending about said optical axis with a second diameter (B) smaller than said first diameter, wherein an optically inactive zone (7) is provided inside said central region (6) extending about said optical axis with a third diameter (C) smaller than approximately 0.5 mm.

2. The contact lens according to claim 1, wherein said optically inactive zone (7) is provided with a second dioptric power that differs from said first dioptric power by at least 6-8 diopters.

3. The contact lens according to claim 2, wherein said central region (6) has a progressive asphericality that joins in a continuous manner said second dioptric power of said optically inactive zone (7) with said first dioptric power of said optical zone (5).

4. The contact lens according to claim 3, wherein said central region (6) and said optically inactive zone (7) have a dioptric power that varies in a linear manner from said optical axis (X) to said first dioptric power at said optical zone (5).

5. The contact lens according to claim 4, wherein, at said optical axis (X), said second dioptric power differs from said first dioptric power by 10 diopters.

6. The contact lens according to claim 1, wherein said second diameter (B) is between 0.8 mm and 1.6 mm.

7. The contact lens according to claim 1, wherein said third diameter (C) is between 0.16 mm and 0.32 mm.

8. The contact lens according to claim 1, wherein said first dioptric power of said optical zone is designed to correct an ametropia.

9. The contact lens according to claim 1, for correcting presbyopia.

10. The contact lens according to claim 1, for correcting an ametropia.

11. A method for the production of a contact lens, comprising the steps of: providing an optical zone (5) extending with a first diameter (A) about an optical axis of said lens, with a first dioptric power, and identifying a central region (6) of said contact lens, inside and contiguous with said optical zone and extending about said optical axis with a second diameter (B) smaller than said first diameter, and providing an optically inactive zone (7) inside said central region (6) and extending about said optical axis with a third diameter (C) less than approximately 0.5 mm.

12. The method according to claim 11, wherein said optically inactive zone (7) is shaped so as to have a second dioptric power that differs from said first dioptric power by at least 6-8 diopters.

13. The method according to claim 12, wherein said central region (6) is shaped so as to have a progressive asphericality that joins in a continuous manner said second dioptric power of said optically inactive zone (7) with said first dioptric power of said optical zone (5).

14. The method according to claim 13, wherein said central region (6) and said optically inactive zone (7) are shaped so as to have a dioptric power that varies in a linear progression from said optical axis (X) to said first dioptric power at said optical zone (5).

15. The method according to claim 14, wherein, at said optical axis (X), said second dioptric power differs from said first dioptric power by 10 diopters.

16. The method according to claim 11, wherein said second diameter (B) is between 0.8 mm and 1.6 mm.

17. The method according to claim 11, wherein said third diameter (C) is between 0.16 mm and 0.32 mm.

18. The method according to claim 11, wherein said first dioptric power corresponds to a focal equivalent calculated as the mean of: a first nominal dioptric power calculated for the correction of a spherical ametropia, and a second nominal dioptric power calculated for the correction of astigmatism.

19. The method according to claim 11, wherein said first dioptric power corresponds to a focal equivalent calculated as the mean of: a first nominal dioptric power calculated for the correction of an ametropia for long-distance vision, and a second nominal dioptric power calculated for the correction of presbyopia for short-distance vision.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The characteristics and advantages of the invention will be made clearer by the following detailed description of a preferred embodiment, given by way of non-limiting example, with reference to the accompanying drawings, in which:

[0058] FIG. 1 is a perspective view of a contact lens produced according to the present invention,

[0059] FIG. 2 is an axial cross-section view of the contact lens of FIG. 1,

[0060] FIG. 3 is a graph illustrating the progressive variation in the dioptric power of the contact lens of FIG. 1 as a function of the distance from the optical axis.

PREFERRED EMBODIMENT OF THE INVENTION

[0061] In the drawings, the numeral 1 indicates the whole of a contact lens produced according to the present invention.

[0062] The lens 1 is preferably a soft contact lens made from a HEMA-based hydrogel, with a liquid component consisting of a lachrymal substitute formed by a physiological solution suitably supplemented with sodium hyaluronate and/or TSP.

[0063] The lens 1 comprises a body 2 in which are defined two surfaces 3 and 4, opposite each other, respectively convex and concave, making the lens 1 suitable to be applied on to the eye of a user.

[0064] The surfaces 3 and 4 are suitably shaped to refract the light that passes through them according to a predefined dioptric power, generically variable from one point of the lens to another, as described below in greater detail.

[0065] The contact lens 1 has an essentially circular shape in plan view, extending about an optical axis X of the lens, and has a diameter D of approximately 14 mm, making it suitable to be applied on to the eye of a user.

[0066] On the contact lens 1 are defined an optical zone 5, extending with a first diameter A about the optical axis X, and a central region 6, extending about the optical axis X with a second diameter B, smaller than the first diameter A, inside which is further defined an optically inactive zone 7, extending about the optical axis X with a third diameter C, smaller than the second diameter B.

[0067] The first diameter A of the optical zone 5 is approximately 11 mm, while the second diameter B of the central region B is approximately 1.2 mm and the third diameter C is approximately 0.5 mm.

[0068] The optical zone 5 is provided with a first dioptric power, while the optically inactive area 7 is provided with a second dioptric power that differs from the first dioptric power by at least 6 dioptres.

[0069] In the preferred embodiment described here, the entire central region 6 and the optically inactive zone 7 are provided with a dioptric power that varies in a linear manner according to the distance from the optical axis X between a minimum value, equal to the first dioptric power at the border between the optical zone 5 and the central region 6, and a maximum value at the optical axis X.

[0070] The maximum value of the second dioptric power, at the optical axis X, differs from the first dioptric power by 10 dioptres.

[0071] In the embodiment example described and illustrated here, the optical zone 5 is designed to correct a myopia of −3.50 dioptres in a person approximately 55 years of age with a degree of presbyopia of +2.00 dioptres.

[0072] In this case, the focal equivalent, calculated as the mean of the first nominal dioptric power of −3.50, relating to correction of the myopia, and the second nominal dioptric power of +2.00, relating to correction of the presbyopia, is −2.50 dioptres.

[0073] The first dioptric power of the optical zone corresponds to the focal equivalent of −2.50 dioptres calculated above.

[0074] The optically inactive zone 7 therefore has a second dioptric power of −12.50 dioptres at the optical axis X. Alternatively, the optically inactive zone 7 could have a second dioptric power of +7.50 dioptres at the optical axis X.

[0075] FIG. 3 illustrates the progressive variation in the dioptric power of the lens 1 as the distance from the optical axis X changes. From this it will be seen that the dioptric power in the optically inactive zone 7 and the central region 6 varies in a linear manner from the maximum at the optical axis X to the minimum value equal to the first dioptric power with which it is connected to the optical zone 5.

[0076] The lens 1 allows both good short-distance vision and good long-distance vision.

[0077] In a second embodiment example, not illustrated in the attached drawings, the optical zone of the contact lens is designed to correct a myopia of −3.50 dioptres combined with an astigmatism of −1.50 dioptres along one of the two axes.

[0078] In this case, the focal equivalent, calculated as the mean of the first nominal dioptric power of −3.50, relating to correction of the myopia, and the second nominal dioptric power of −1.50, relating to correction of the astigmatism, is −4.25 dioptres.

[0079] The optical zone has a first dioptric power corresponding to the focal equivalent of −4.25 calculated above.

[0080] The optically inactive zone therefore has a second dioptric power of −14.25 (or +5.75) dioptres at the optical axis.

[0081] In this case, thanks to the increased depth of field, the contact lens allows improved long-distance vision.

[0082] In other embodiments of the invention, the optical zone of the contact lens is designed to correct hypermetropia, possibly combined with astigmatism, or myopia and hypermetropia, possibly combined with astigmatism, in the presence of presbyopia.

[0083] The present invention therefore solves the problem described above with reference to the prior art, while simultaneously offering numerous other advantages, including the ability to satisfy, with a single lens, differing needs in terms of the correction of visual defects. It will be appreciated that the contact lens described in detail above, having a first dioptric power of −2.50, allows the correction of different pairs of nominal dioptric powers deriving from myopia and presbyopia or from myopia and astigmatism. For example, the same focal equivalent of −2.50 arises from a myopia of −3.00 combined with a presbyopia of +1.00, or from a myopia of −3.75 and a presbyopia of +2.50, or from a myopia of −3.00 combined with an astigmatism of +1.00.

[0084] The invention therefore allows a substantial reduction in the number of possible combinations of the optical characteristics of the lenses, with obvious immediate advantages in terms of production and stock maintenance.

[0085] Naturally, a person skilled in the art will be able to create further modifications and variants in order to satisfy specific and contingent application needs, and any such variants and modifications remain within the scope of protection defined by the claims that follows.