EP2294473A1

EP2294473A1 - Ophthalmic glass and spectacles comprising at least such one glass

Info

Publication number: EP2294473A1
Application number: EP08805585A
Authority: EP
Inventors: Guy Gerbaud
Original assignee: ICE FOSTER Ltd
Current assignee: ICE FOSTER Ltd
Priority date: 2008-05-19
Filing date: 2008-05-19
Publication date: 2011-03-16
Also published as: WO2009141509A1; US8506074B2; US20110181834A1

Abstract

Ophthalmic glass comprising at least one aspherical face with an optical centre (PR) and a geometrical centre, and comprising in succession a top vision region, an intermediate vision region and a bottom vision region, with a principal meridian of progression (MP) traversing said three vision regions of the aspherical face, the glass being noteworthy in that the top vision region is adapted for mid-distance vision, the bottom vision region is adapted for near-distance vision, and the intermediate vision region is adapted for intermediate distance vision, and in that the optical centre (PR) of said aspherical face is in said intermediate vision region, said optical centre (PR) coinciding with the geometrical centre of the aspherical face. This glass is particularly suitable for people with emmetropic longsightedness.

Description

OPHTHALMIC GLASS AND LENSES COMPRISING AT LEAST ONE SUCH

GLASS

The present invention relates to an ophthalmic lens and to a pair of spectacles comprising at least one such ophthalmic lens.

It relates more particularly to an ophthalmic lens for the compensation of presbyopia corresponding to a decrease in accommodation of the lens due to the natural aging of the eye.

Presbyopic individuals are divided into two main categories:

- presbyopic ametopes, that is to say individuals who, prior to their presbyopia, have a visual defect, called ametropia, such as a defect in myopia, hyperopia or astigmatism; and

- presbyopic emmetropia, that is to say, individuals who, prior to their presbyopia, have no visual defect.

The present invention relates even more particularly to a progressive ophthalmic lens for presbyopic emmetopes.

For the compensation of presbyopia, it is known to use a unifocal convex glass or a progressive ophthalmic lens. The unifocal convex glass is conventionally adapted to near-distance vision, that is to say at a reading distance of between 20 and 40 cm, preferably of the order of 33 cm. The dioptric values compensating for presbyopia range from + 0.75 to +3.5 diopters per half or quarter diopter, to account for the rapid evolution of presbyopia. Thus, the presbyopic emmetropic is made to change regularly its glasses according to the evolution of this ocular disorder and, if a glass of power + 0.75 or + 1, 00 diopter is sufficient to the prima-presbyte or individual at the beginning from his presbyopia, he will soon be obliged to use increasingly convex glasses up to a value of + 3.00 to 3.50 diopters. If a unifocal lens brings a clear vision for the reading, it however considerably reduces the distance of vision by a loss of depth of field and that all the more as the convex value of the glass is high. Due to the increasing use of computer instruments, presbyopic emmetropics also need a lens that gives them clear vision at a so-called intermediate distance corresponding to a working distance on a computer screen. ; this intermediate distance, located beyond the near distance or reading distance mentioned above, is between 40 and 90 cm, preferably of the order of 50 to 80 cm.

Computer work often requires the simultaneous viewing of an object at close range, such as a reading document and keyboard at close range, and an intermediate distance object, in this case the computer screen. To meet the dual need for near-distance vision and intermediate distance, the presbyopic emmetropic would have no choice but to have two pairs of single-lens glasses, one dedicated to near-vision vision. another dedicated to intermediate distance vision.

The multifocal progressive ophthalmic lens, known in particular from FR 2,683,642, is conventionally used to compensate for presbyopia while allowing the wearer of glasses to observe objects in a wide range of distances without removing his pair of glasses. . Such a glass includes an aspherical face having:

an upper zone of vision adapted for distant vision, that is to say for an infinite vision that is useful in particular for driving a motor vehicle, said zone being located in the upper part of the lens;

- A lower zone of near-distance vision, adapted for reading, said zone being located in the lower part of the glass; and

an intermediate zone connecting the upper zone of vision to the lower zone of vision, called the intermediate zone of vision.

Usually, the aspherical face corresponds to the front face of the lens, which is the face opposite to the wearer of the pair of spectacles, whereas the rear face of the lens, which is the face directed towards the wearer of the pair of spectacles, is spherical type. This spherical face makes it possible to adapt the lens to the ametropia of the wearer, so that the progressive multifocal ophthalmic lens is generally defined by its aspherical surface. Such progressive lenses thus have the primary purpose of compensating for the ametropia of the wearer in the upper part, corresponding to the upper zone of far vision, but also the presbyopia in the lower part, corresponding to the lower zone of near-distance vision. . The intermediate zone of vision of these progressive lenses is generally very narrow between the above-mentioned lower and upper zones of vision. In the current state of the art, it is found that progressive lenses require a wearer who watches a computer screen to raise the head and aim in the narrow zone of intermediate vision. This non-ergonomic position is a source of discomfort for presbyopes.

Mounting in a spectacle frame of a pair of progressive multifocal ophthalmic lenses requires great precision and can only be achieved by one skilled in the art. The assembly can only be performed after a series of measurements that take into account the position of the frame on the wearer's face. The accuracy of positioning the reference point in the frame is essential with such glasses.

The state of the art can also be illustrated by the teaching of the patent application FR 2 769 997. In this application, it is intended to compensate for presbyopia to use a multifocal ophthalmic lens having an aspherical face having a main meridian of substantially umbilical and vertical progression and whose reference point for near vision is located about 10 mm below the geometric center of the lens. This particular lens thus has an optical center for a near vision under the geometric center with a decrease of sphere from this point to the top of the lens. This lens of the multifocal type, which also makes it possible to compensate for an ametropia, can not be mounted simply in a frame because it also requires certain measurements taken together with the appearance of the wearer. The assembly can also be done by a person skilled in the art.

It is also known from the patent application FR 2 844 365, a spectacle lens having an aspherical face having a main meridian of non-umbilical progression and comprising: a central part adapted for intermediate distance vision, in particular for work on computer, the average transmission power in this central portion being substantially constant;

an upper part situated on an upper side of the central part, the average transmission power decreasing in this upper part; and

a lower part situated on a lower side of the central part, the average transmission power increasing in this lower part.

This glass has the disadvantage of offering two parts, respectively lower and upper, very narrow. Thus, the narrow upper zone impairs the peripheral visual perception in proximity vision by a restricted lateral field. The present invention is intended in particular to solve all or some of the aforementioned disadvantages, and proposes for this purpose an ophthalmic lens having at least one aspherical face having an optical center, a geometric center and successively comprising an upper zone of vision, an intermediate zone. a vision zone and a lower zone of vision, as well as a principal meridian of progression traversing the three said zones of vision of the aspherical face, said lens being remarkable in that the upper zone of vision is adapted to medium-range vision, the lower zone of vision is adapted to near-distance vision and the intermediate zone of vision is adapted to the intermediate distance vision, and in that said aspherical face has its optical center in said intermediate zone of vision, said optical center being confused with the geometric center of the aspheric face.

For the purposes of the present application, the different zones of vision are defined as follows:

the zone of vision at near distance corresponds to a viewing zone at a reading distance of between 20 and 40 cm, preferably of the order of 33 cm;

the intermediate distance vision zone corresponds to a viewing zone at a working distance on a computer screen comprised between 40 and 90 cm, preferably of the order of 50 to 80 cm, beyond the distance of reading above and below average distance;

the medium-distance vision zone corresponds to a viewing zone at a distance of the order of one meter, preferably between 80 cm and 5 m, more preferably between 1 m and 3 m, beyond the aforementioned intermediate distance and beyond the infinity which is classically associated with a vision from a distance.

Thus, the upper zone of vision is adapted for medium-range vision, and not for infinite vision or far vision, and the lower zone of vision is adapted for near-distance vision, so that the difference power between these two areas is relatively small compared to that of progressive multifocal conventional lenses. The intermediate zone of vision therefore has a relatively low or gentle variation in power or mean sphere, thus ensuring a comfort of vision. The invention thus meets the visual problem of the presbyopic emmetropic by proposing a glass dedicated mainly to its visual need to intermediate distance, such as the distance to a computer screen, while preserving near-distance vision and also providing a large depth of field with a wide lateral field for a working environment. The optimum comfort of the glass according to the invention is located at the optical center, coincides with the geometric center, for a privileged vision at intermediate distance.

This lens for presbyopic emmetropic individuals, does not allow of course to compensate for an ametropia, but is perfectly suited for near-distance vision and intermediate distance.

In a particular embodiment of the invention, the main meridian of progression is of the substantially umbilical type, that is to say on which the astigmatism is minimal or even zero, and vertical.

Thus, the glass is particularly simple to implement and can be used indifferently to the right and left in a spectacle frame, and mainly requires when mounted in the mount to ensure the vertical alignment of the main meridian progression.

Advantageously, the aspherical face is substantially symmetrical with respect to said main meridian of progression. The invention thus meets the dual need of emmetropic presbyopes for a glass adapted to computer tasks. The glass can be mounted simply in a frame such as a unifocal convex spherical glass. In this way, this glass may for example be pre-mounted in a spectacle frame. In one embodiment, the upper zone of vision corresponds to a zone of the aspherical face situated above the optical center and having a substantially constant mean sphere on the main meridian of progression, and whose value is between 0.2 and 2.0 diopters and preferably between 0.3 and 1, 7 diopters. This upper zone of vision is thus particularly adapted to a medium distance vision.

In a particular embodiment, the lower zone of vision corresponds to a zone of the aspherical face situated below the optical center and having a substantially constant mean sphere on the main meridian of progression, and whose value is between 0.8 and 3.5 diopters, preferably between 1.0 and 3.0 diopters. This lower zone of vision is thus particularly adapted to a vision at close distance

In an advantageous embodiment, the intermediate zone of vision corresponds to an area of the aspherical face having a mean sphere variation along the main meridian of progression between the upper and lower zones of vision.

This variation of the average sphere is sufficiently soft or low to allow a great comfort of intermediate distance vision for the wearer; said intermediate zone of vision being framed by the upper zone for medium-distance vision and the lower zone for near-distance vision.

This average sphere variation is advantageously between 0.6 and 2.2 diopters, preferably between 0.75 and 2.0 diopters.

According to one characteristic, the value of the average sphere at the optical center of the glass, on the main meridian of progression, is between 0.5 and 2.5 diopters, preferably between 0.7 and 2.25 diopters.

According to another characteristic, the progression height, in the intermediate zone of vision, along the main meridian of progression is less than or equal to 35 mm, preferably less than or equal to 33 mm.

The progression height is sufficiently high so that the width of the intermediate zone of vision is not narrow and thus offers a great comfort of intermediate distance vision for the wearer. Advantageously, the width of the umbilical meridian delimited by the iso-cylinder curves less than or equal to 0.2 diopters, preferably 0.17 diopters, at the optical center of the glass is at least sufficient to cover a rotation angle of the eye between about 6 ° and 8 ° when the lens is about 14 mm distant from the eye. This angle of rotation of the eye from 6 ° to 8 ° corresponds to the angle beyond which it is commonly accepted that the head of an individual starts to rotate to maintain a greater visual comfort; the invention thus provides a great lateral comfort of intermediate distance vision for the wearer. In a particular embodiment, the umbilical meridian width delimited by the iso-cylinder curves less than or equal to 0.2 diopter, preferably 0.17 diopters, at the optical center of the glass is at least 3 mm.

With such a width, the glass can cover the angle of rotation of the eye between 6 ° and 8 ° to provide a great lateral comfort of intermediate distance vision for the wearer.

According to an advantageous characteristic of the invention, the iso-cylinder curves, preferably the iso-cylinder curves less than or equal to 0.25 diopters, are substantially parallel to the main meridian of progression in the intermediate zone of vision. Thus, the glass has in its central part a large and comfortable progression area for intermediate distance vision.

The invention also relates to spectacles comprising at least one lens as described above.

According to an advantageous characteristic, the spectacles comprise two glasses symmetrical with respect to the median plane of symmetry of said spectacles.

Other characteristics and advantages of the present invention will appear on reading the detailed description below, of an example of non-limiting implementation, with reference to the appended figures in which:

FIGS. 1a to 1e are graphs representing the variation of the average sphere along the principal meridian of progression of different embodiments of the lens according to the invention, in which the abscissa axis is graduated in dioptre for the sphere values mean, and where the y-axis is graduated in millimeters for the distance from a central point to the meridian;

FIG. 2a is a front view of a cylinder card of a glass according to the invention illustrating several iso-cylinder curves less than 0.50 diopters; and FIG. 2b is a perspective view of the cylinder card illustrated in FIG. 2a with only the iso-cylinder curve equal to 0.17 diopters, with an illustration of an eye located at a predetermined distance from the glass and a corner sector associated with a rotation of the eye in a horizontal plane. A glass according to the invention comprises at least one aspherical face having a geometric center and an optical center which coincide at the point PR in Figures 1a to 1e. This point PR corresponds to the design reference point of the glass, sometimes called the centering point of the glass, and can be defined as follows: a light ray coming from the infinite and passing through the glass at the reference point PR ₁ or center optical, does not undergo any angular deviation.

The aspherical face has at each point a mean sphere value and a cylinder value.

This aspherical face has three different areas of vision:

- An upper zone of vision, located in the upper part of the glass from an upper edge of said glass, and adapted for a medium distance vision, already defined as a vision at a distance of about one meter;

- A lower zone of vision, located in the lower part of the glass from a lower edge of said glass, and adapted for near-distance vision, already defined as a vision at a reading distance; an intermediate zone of vision, located between the lower and upper zones of vision in the central part of said lens, and adapted to an intermediate distance vision, between a medium distance vision and a near distance vision, and already defined as a vision suitable for working on a computer screen. These three zones of vision are crossed by a main meridian of progression MP which passes through the optical center PR; said optical center PR being located in the intermediate vision zone.

In addition, the main meridian of progression MP is substantially vertical and umbilical. Likewise, the surface of the aspherical face is substantially symmetrical with respect to its main meridian of substantially vertical and umbilical progression MP.

Thus, the aspherical face of the glass is substantially symmetrical and the vertical axis y of the glass is a main meridian of umbilical progression allowing to use the same glass indifferently for the right eye and for the left eye. The glass can thus be mounted in an eyeglass frame by keeping the axis of symmetry y vertical.

The main meridian of progression MP is continuous, that is to say between the lower and upper zones of vision is provided the intermediate zone of vision whose power, or average sphere, varies continuously along the meridian main progression of MP, and connects continuously to said lower and upper viewing areas.

The main meridian of progression MP is substantially symmetrical with respect to the optical center PR of the glass coincides with the geometric center. In a variant not shown, the progression meridian MP is not symmetrical with respect to said optical center PR so that the glass has an asymmetry in its vertical progression.

In the upper zone of vision, located above the optical center PR, the mean sphere is substantially constant over the main meridian of progression MP and equal to a given value SA between 0.2 and 2.0 diopters, and preferably between 0.3 and 1, 7 diopters.

In the lower zone of vision, located below the optical center PR, the mean sphere is substantially constant over the main meridian of progression MP and equal to a given value SB of between 0.8 and 3.5 diopters, and preferably between 1, 0 and 3.0 diopters.

In the intermediate zone of vision, the mean sphere varies progressively over the principal meridian of progression MP between the values SA and SB of average sphere on the principal meridian of progression MP of respectively the upper and lower zones of vision. In this intermediate zone of vision, along the main meridian of progression MP, the average sphere variation V is between 0.6 and 2.2 diopters, preferably between 0.75 and 2.0 diopters.

The height of the progression is thus between the two points situated on the principal meridian of progression MP, below and above the optical center PR of the glass, representing for the low point B the maximum value SB of the mean sphere and for the high point At the minimum value SA of the mean sphere. Thus, the average sphere is substantially constant on the main meridian of progression MP below the maximum average sphere point SB SB, and the mean sphere is substantially constant on the main meridian of progression MP above the average sphere point A minimum SA.

The height H of progression in the intermediate zone of vision, along the main meridian of progression MP between points A and B, is less than or equal to 35 mm, preferably less than or equal to 33 mm. Such a height H is thus adapted to allow the eye to run vertically (from top to bottom or from bottom to top) before the head follows. while maintaining a vision via said intermediate zone of vision, being frequently admitted that such a vertical stroke corresponds to a viewing angle of about 26 °.

On the upper part of the main progression meridian MP located in the intermediate zone of vision near the optical center

PR, the aspherical face has a medium sphere allowing a good intermediate distance vision adapted to clearly visualize a computer screen located for example at about 60 to 80 cm.

The value SC of the average sphere at the optical center PR of the glass, on the main meridian of progression MP ₁ is between 0.5 and 2.5 diopters, preferably between 0.7 and 2.25 diopters.

On the part of the main progression meridian MP located below the optical center PR, the aspherical face has an increase in the average sphere allowing good near-distance vision, such as a reading distance of the order of 30 cm, whereas above the optical center PR on the principal meridian of umbilical MP progression, the aspherical face presents a significant decrease in the mean sphere allowing a large depth of field of up to approximately 2 to 3 m depending on the mode of production. In the various embodiments illustrated in FIGS. 1a to 1e, the aspherical face has different values of mean sphere and progression height, with:

- SA the minimum mean sphere on the main meridian of progression MP; SB the maximum mean sphere on the main meridian of progression MP;

- SC the mean sphere at the optical center PR on the principal meridian of progression MP;

- V the mean sphere variation between points A and B along the main meridian of progression MP;

H the height of progression along the principal meridian of progression MP.

Thus, in the different embodiments illustrated in FIGS. 1a to 1e, the aspherical face has the following values: in FIG. 1a: SA = 0.3 diopters, SB = 1.0 diopters, SC = 0.75 diopters, V = 0.7 diopters and H = 25 mm; in FIG. 1b: SA = 0.5 diopters, SB = 1.5 diopters, SC = 1.0 diopters, V = 1.0 diopters and H = 27 mm;

in FIG. 1c: SA = 0.75 diopters, SB = 2.0 diopters, SC = 1.25 diopters, V = 1.25 diopters and H = 29 mm; in FIG. 1d: SA = 1, 25 diopters, SB = 2.5 diopters, SC = 1.75 diopters, V = 1, 25 diopters and H = 26 mm;

in FIG. 1e: SA = 1, 7 diopters, SB = 3.0 diopters, SC = 2.25 diopters, V = 1.3 diopters and H = 31 mm.

As illustrated in FIGS. 2a and 2b, the width L of umbilic meridian delimited by the iso-cylinder curves less than or equal to 0.2 diopter, preferably less than or equal to 0.17 diopters, at the optical center of the glass is at a minimum sufficient to cover an angle of rotation of the eye Ω between 6 ° and 8 ° with respect to the central axis of vision AC passing through the optical center PR, when the lens is approximately 14 mm distant from the eye , to allow the wearer to turn his eyes without having to turn his head while maintaining a good vision. FIGS. 2a and 2b of course correspond to an exemplary embodiment of a lens according to the invention, the isocylinder curves thus illustrated being different for each lens and in particular for each variation of the average sphere V along the main meridian of progression.

Thus, the width L of umbilical meridian delimited by the iso-cylinder curves less than or equal to 0.2 diopters, preferably less than or equal to 0.17 diopters, at the optical center PR of the glass is at least 3 mm. The glass according to the invention is of the convex type, and has at least one aspherical face associated with another face which may be spherical or aspherical. Thus, different combinations are possible:

an aspheric front face and an aspheric rear face, each aspherical face being as described above and therefore each having a main meridian of substantially umbilical and vertical progression;

an aspheric front face and a spherical rear face;

a spherical front face and an aspheric rear face.

Glasses equipped with lenses according to the invention are not designed to compensate for an ametropia, but are perfectly adapted to presbyopic emmetopes wishing to work on a computer with great comfort of vision both for the computer screen and for the keyboard and documents at a reading distance, without having to change glasses.

In addition, the glasses according to the invention can be mounted simply in a frame. The main concern of the editor is to place the geometric centers of the two lenses of the mount on the same horizontal of the mount and symmetrically on either side of the nose (the vertical axis) of the mount to a value corresponding to a gap mean pupillary

(physiological data), and to ensure that the main meridian of progression is vertical and correctly oriented. These glasses can be pre-mounted, particularly because of the ease of mounting glasses, and be sold as is.

Of course the implementation example mentioned above is not limiting and other details and improvements can be made to the glass according to the invention, without departing from the scope of the invention.

Claims

1. Ophthalmic lens having at least one aspherical face having an optical center (PR), a geometric center and successively comprising an upper zone of vision, an intermediate zone of vision and a lower zone of vision, and a principal meridian of progression (MP) crossing the three so-called vision zones of the aspherical face, characterized in that the upper zone of vision is adapted to medium-range vision, the lower zone of vision is adapted to near-distance vision and the intermediate zone vision is adapted to the intermediate distance vision, and in that said aspherical face has its optical center (PR) in said intermediate zone of vision, said optical center (PR) coinciding with the geometric center of the aspherical face.

2. Glass according to claim 1, wherein the aspherical face has the main meridian of progression (MP) is of the substantially umbilical and vertical type.

3. Glass according to claim 2, wherein said aspherical face is substantially symmetrical with respect to said main meridian of progression (MP).

4. The lens as claimed in claim 1, in which the upper zone of vision corresponds to a zone of the aspherical face situated above the optical center (PR) and having a substantially constant mean sphere on the principal meridian. of progression (MP), and whose value (SA) is between 0.2 and 2.0 diopters and preferably between 0.3 and 1, 7 diopters.

Glass according to any one of claims 1 to 4, in which the lower zone of vision corresponds to an area of the aspherical face situated below the optical center (PR) and having a substantially constant mean sphere on the main meridian. of progression (MP), and whose value (SB) is between 0.8 and 3.5 diopters, preferably between 1.0 and 3.0 diopters.

Glass according to any one of claims 1 to 5, wherein the intermediate zone of vision corresponds to a zone of the aspherical face having a mean sphere variation along the main meridian of progression (MP) between the upper zones. and lower vision, said average sphere variation (V) being between 0.6 and 2.2 diopters, preferably between 0.75 and 2.0 diopters.

7. Glass according to any one of claims 1 to 6, wherein the value (SC) of the average sphere at the optical center (PR) of the glass, on the main meridian of progression (MP), is between 0.5 and 2.5 diopters, preferably between 0.7 and 2.25 diopters.

Glass according to any one of claims 1 to 7, wherein the height of progression (H) in the intermediate zone of vision, along the main meridian of progression (MP), is less than or equal to 35 mm, preferably less than or equal to 33 mm.

9. Glass according to any one of claims 1 to 8, wherein the width (L) of umbilical meridian delimited by the iso-cylinder curves less than or equal to 0.2 diopters, preferably 0.17 diopters, in the center The optical glass is at least sufficient to cover an angle of rotation of the eye (Ω) between about 6 ° and 8 ° when the glass is distant from the eye by about 14 mm.

10. Glass according to any one of claims 1 to 9, wherein the width (L) of umbilical meridian delimited by the iso-cylinder curves less than or equal to 0.2 diopters, preferably 0.17 diopters at the optical center. glass is at least 3 mm.

11. Glass according to any one of claims 1 to 10, wherein the iso-cylinder curves, preferably the iso-cylinder curves less than or equal to 0.25 diopters, are substantially parallel to the main meridian of progression. (MP) in the intermediate zone of vision.

Glasses comprising at least one glass according to any one of claims 1 to 11.