WO2007015001A1

WO2007015001A1 - Presbyopia correcting multifocal lens

Info

Publication number: WO2007015001A1
Application number: PCT/FR2006/001862
Authority: WO
Inventors: Michel Pavillon; Gérard PERRIN
Original assignee: Laboratoire Precilens
Priority date: 2005-08-02
Filing date: 2006-08-01
Publication date: 2007-02-08
Also published as: FR2889601A1; FR2889601B1; EP1910889A1

Abstract

The multifocal lens comprises a spherical power short sighted vision area (VP), a preferably spherical distance vision area (VL) and at least one progressive intermediate vision area (VI), which are selected in such a way that a transition line (Cl, C2) between each adjacent pair of areas belongs to a plane which is tangent to said pair areas on any plane of a diametrical cross-section.

Description

Multifocal lens for the correction of presbyopia.

The present invention relates to a so-called "progressive" lens, which lens may be a contact lens or an intraocular implant. In the following, in particular to describe the state of the art, reference will be made to the case of a contact lens.

Progressive lenses, like progressive spectacle lenses, are intended to correct presbyopia.

Presbyopia is due to a loss of flexibility of the lens, resulting in a loss of accommodative power

(which ranges from approximately 20 diopters at birth to 4 diopters at around 45-48 years). On a practical level, presbyopia manifests itself, as we know, by an extension of the minimum distance of distinct vision. A presbyopic subject therefore needs a correction to find a good near vision.

Several solutions are proposed to him to do this:

- single-hearth, half-moon or other glasses (near-vision correction only) with double focus or triple focus (correction, step-by-step, near vision, far vision, and possibly intermediate vision). progressive (continuous correction of vision from near to far vision)

- or lenses. with so-called "alternating" vision: in such lenses, the far vision zone (hereinafter VL) occupies the center of the lens and the near vision zone (hereinafter VP) is located on the periphery of the lens. lens, concentrically or not at the VL area; the VP area is placed in front of the pupil, when the wearer lowers the eyes, while it is the VL zone which is placed there when the wearer looks straight ahead, the lens having to be sufficiently mobile for the expected optical effect to be obtained; so-called "simultaneous" vision: the optical zones are concentric and the mobility of the lens must be reduced to the minimum so that the lens remains centered and the optical effect is satisfactory: the images in VL and VP are formed simultaneously along of the visual axis, and the brain selects the best image.

The invention relates to a lens of the "simultaneous vision" type.

Are known from EP-AO 184 490 as a _lens "simultaneous vision." This lens has an aspherical face whose power varies continuously from the center to the periphery, the lens may have either an internal face in the form of "torus-pumpkin" and an outer face "torus-spindle" or the opposite.

The complexity of the shape of this lens requires particularly demanding manufacturing conditions.

It has now been found that a lens at least as satisfactory as the lens according to EP-A-0 184 490 can be obtained by adopting another geometry. More specifically, the lens according to the invention which comprises, in a manner known per se, an outer face and an inner face, a near vision zone, a far vision zone and an intermediate vision zone, is characterized. in that said near vision zone is of spherical power, said intermediate vision zone is progressive, and the near vision, far vision and intermediate vision zones are such that in any plane of section diametric, the transition line between each pair of adjacent areas belongs to a plane tangent to the zones of said pair.

By spherical power zone is meant that the zone brings a paraxial beam of parallel rays on a single outbreak (OIML R 93 - 1999 Edition) or, expressed in d ^! other words, that the area is defined by a spherical inner face and a spherical outer face.

Unlike the lens known from EP-AO 184 490, the zone of near vision of the lens according to the invention is therefore not progressive (that is to say multifocal) but of spherical power ( that is to say monofocal). This geometry improves and stabilizes the visual performance (sharpness, visual comfort, etc.). In a preferred embodiment, the far vision zone is also of spherical power, for the same reason.

As indicated above, in the lens according to the invention, the zones of near vision, far vision and intermediate vision are such that, in any diametral plane of cut, the transition line between each pair of adjacent areas belongs to a plane tangent to the areas of said pair. This feature avoids image jumps and reduces optical aberrations. According to a first possibility, the near vision zone is located at the center of the lens and the far vision zone is located at the periphery of the lens.

Alternatively, the far vision zone is located in the center of the lens and the near vision area is located at the periphery of the lens.

In either case, the intermediate vision zone is located between the near vision zone and the far vision zone.

The optical power of a given area being the sum of the optical effects of the outer face and the inner face of said zone, the progressive power zone of the lens according to the invention may have an aspheric outer face and a spherical inner face. , a spherical outer face and an aspheric inner face, or an outer aspherical face and inner face.

The lenses according to the invention can be manufactured by molding or by turning from a biocompatible material that will lead to a soft, rigid or rigid gas permeable lens.

In the case of molding, using a mold comprising, in a manner known per se, a male part and a female part adapted to cooperate to define a cavity adapted to receive a polymerizable material, the female part and the male part having a geometry made by machining and which is identical, to that of the corresponding faces of the expected lens. In the case of turning, it is better to use the latest generation machining equipment (nanotechnology) to avoid polishing the turned lens. In fact, failing this, the turned lens may include traces of turning which will have to be eliminated by polishing, which sometimes causes deformations that alter the optical quality of the lens. However, it is also possible, depending on the materials or other parameters, to adapt a light polishing.

Obtaining a finished lens without polishing gives it a geometry that is both complex and precise, and above all perfectly reproducible.

The invention will be better understood on reading the following description made with reference to the accompanying drawings in which: - Figure la is a diametral section of a lens according to a first embodiment of the invention;

FIG. 1b is a curve of the powers of the lens of FIG. 1a, as a function of the distance from the optical axis;

FIG. 1c is a curve of the powers, as a function of the distance from the optical axis, of a variant of the type of lens illustrated in FIG.

- Figure Id is a detail, on a larger scale, of the encircled area I of Figure la;

FIG. 1a is a detail, on a larger scale, of the encircled zone II of FIG. FIG. 2a is a diametral section of a lens according to a second embodiment of the invention;

FIG. 2b is a curve of the powers of the lens of FIG. 2a, as a function of the distance from the optical axis;

FIG. 2c is a curve of the powers, as a function of the distance ^' from the optical axis, of a variant of the type of lens illustrated in FIG. 2a; FIG. 3 is a curve of the powers, as a function of the distance from the optical axis, of a personalized variant of the type of lens illustrated in FIG. and

FIG. 4 is a curve of the powers, as a function of the distance from the optical axis, of another personalized variant of the type of lens illustrated in FIG.

If we examine Figure la, we see a lens 1 whose optical axis is indicated at X-X '. The outer face (convex face in the drawing) of the lens comprises three concentric zones, namely a near-vision central zone VP, a peripheral vision zone VL far and, between them, an intermediate zone VI. The near vision zone VP is of spherical surface, that is to say that its radius of curvature Ro is constant over the entire portion delimited by the circle or transition line C1. The intermediate vision zone VI is itself an aspherical surface, that is to say that, in the zone delimited between the circle C1 and the circle or transition line C2, the radius of curvature varies. The far vision zone VL, which occupies the periphery of the lens from the circle C2 may be of aspherical surface, but is preferably of spherical surface.

As shown in Figure Id, at the level of the transition line C1, there exists a plane T1 tangential to both the VP area and the VI zone. Similarly, as shown in Figure 1c, at the level of the transition line C2, it There exists a T2 plane tangent to both zone VI and zone VL.

If we now examine the curve of Figure Ib, where the axis of the powers can be likened to the optical axis and where the curve illustrates the power variation on a half-lens, the power is maximum and constant in the central zone of the lens, corresponding to the VP of spherical power, then it decreases abruptly in the intermediate vision zone VI of progressive power, to be, again, constant but minimal in the VL zone, of spherical power.

A variant is illustrated by the curve of FIG. 1c where, as in FIG. 1b, the power is maximum and constant in the area VP, and minimum and constant in the peripheral area VL but, instead of decreasing sharply beyond the circle C1, in the intermediate vision zone VI of progressive power, the power decreases first slowly, then more markedly and again gently approaching the circle C2. If we now examine FIG. 2a, we see that, unlike FIG. 1a, it is the far vision zone VL that occupies the central part of the lens bounded by the circle C2 'and the zone near vision VP occupying the peripheral part beyond the circle Cl '. Zone VL is of spherical power, with an outer surface of constant radius of curvature R1, as is also spherical power zone VP. The intermediate zone VI is of progressive power.

This inversion of the VP and VL zones is evident from Figure 2b. This curve shows that beyond the circle C2 'the power increases sharply in the zone VI to finally equalize the power of the area VP at the level of the circle Cl'.

A variant is illustrated by the curve of FIG. 2c where, as in FIG. 2b, the power is minimum and constant in the VL zone, and maximum and constant in the peripheral zone VP, but instead of growing suddenly beyond the circle C2 ', in the intermediate vision zone VI of progressive power, the power first grows gently, then more markedly and again gently approaching the circle Cl'. FIGS. 3 and 4 show that it is possible to customize the lenses according to the invention by modifying, for example, the diameter of the area VP (the diameter of the area VP2 of FIG. 4 is smaller than the diameter of the area VP1 of Figure 3), that of the intermediate zone (the diameter of the VI2 zone 4 is less than the diameter of the VII area in Figure 3) ^'and of the VL region (the diameter of the VL2 zone Figure 4 is larger than the diameter of the area VL1 of Figure 3). It is understood that this same type of variation is possible in the configuration where the VL occupies the central zone of the lens instead of occupying the peripheral portion.

The lenses according to the invention are manufactured by molding or by turning, preferably without polishing. The lenses can be made of any biocompatible materials whether they are of the flexible, hard, rigid gas-permeable or combined type.

It is understood that the invention is not limited to the embodiments described and shown. In particular, the lens according to the invention could have several intermediate zones, called sub-zones, instead of just one. The intermediate zone or one or more intermediate sub-zones could be elliptical, parabolic, hyperbolic or ogival. When the intermediate zone is subdivided into several zones, at least one, but not all, sub-zones may be spherical. If the lens has an intermediate zone subdivided into a plurality of sub-areas, the transition line between each pair of adjacent sub-areas shall belong to a plane tangent to the sub-areas of said pair. The non-progressive face may be spherical or toric.

Claims

A multifocal lens having an outer face and an inner face, a near vision zone, a far vision zone and at least one intermediate vision zone, characterized in that said near vision zone (VP) is spherical power, said intermediate vision zone (VI) is progressive, and the near vision (VP), far vision (VL) and intermediate vision (VI) zones are such that, in any plane of In a diametrical section, the transition line (C1, C2; Cl ', C2') between each pair of adjacent zones belongs to a tangent plane (T1, T2) to the zones of said pair.

2. Lens according to claim 1, characterized in that the far vision zone (VL) is of spherical power.

3. The lens according to claim 1 or 2, characterized in that the near vision zone (VP) is located in the center of the lens and the far vision zone (VL) is located at the periphery of the lens.

4. The lens according to claim 1 or 2, characterized in that the far vision zone (VL) is located at the center of the lens and the near vision zone (VP) is located at the periphery of the lens.

5. Lens according to any one of claims 1 to 4, characterized in that said intermediate vision zone (VI) is located between the near vision zone (VP) and the far vision zone (VL).

The lens according to any one of claims 1 to 5, which is a contact lens.

The lens of any one of claims 1 to 5, which is an intraocular implant.