EP2419781A1

EP2419781A1 - Method of determining an ophthalmic lens

Info

Publication number: EP2419781A1
Application number: EP10719386A
Authority: EP
Inventors: Jean-Pierre Chauveau; Frédéric Dubois; Cyril Guilloux; Christian Joncour; Mélanie TESSIERES; Hélène De Rossi
Original assignee: Essilor International Compagnie Generale dOptique SA
Current assignee: EssilorLuxottica SA
Priority date: 2009-04-17
Filing date: 2010-04-19
Publication date: 2012-02-22
Also published as: CN102498430A; BRPI1014913A8; JP5893553B2; CA2758984A1; JP2012524293A; CN102498430B; BRPI1014913B1; US20150309338A1; WO2010119183A1; BRPI1014913A2; US9482884B2; WO2010119435A1

Abstract

The invention relates to a method of determining an ophthalmic lens for a wearer's eye, the method comprising the following steps: measurement, on the wearer in binocular vision, of the three-dimensional coordinates of the centre of rotation (COR) of the wearer's eye; measurement (10) of at least one viewing direction in a natural posture; determination of the desired position of the ophthalmic lens; calculation of the characteristics of the ophthalmic lens using the measured coordinates and the determined position and the measured direction in the natural posture. Measuring the position of the centre of rotation of the eye in binocular vision ensures that the lens obtained is best adapted for the wearer.

Description

METHOD FOR DETERMINING AN OPHTHALMIC LENS

The present invention relates to a method for determining an ophthalmic lens for a wearer. The method can be applied indifferently for a single or multifocal prescription. It also applies to microstructured glasses (pixelized glasses, diffractive glasses, Fresnel ...), adaptive lenses, index gradient lenses and more generally any other type of ophthalmic lens.

The invention also extends to the method for calculating the parameters for trimming and manufacturing an ophthalmic lens obtained according to the determination method. It may be prescribed to a wearer a power correction, positive or negative

(hyperopic or myopic carrier); the lens used for this type of prescription is a spherical or aspherical lens. An astigmatic carrier has, in a plane perpendicular to the direction of gaze, a prescription of different power along different axes; the prescription is usually expressed as a prescription of a first power value, corresponding to the power along a main axis and a second power value along an axis perpendicular to the main axis. The lens used for this type of prescription is a toric or atoric lens. In the following, the term "unifocal prescription" is used to describe the correction proposed for such carriers.

For presbyopic wearers, the value of the power correction is different in far vision and in near vision, because of the difficulties of accommodation in near vision. The prescription is then composed of a power value in far vision and a representative addition of the power increment between the far vision and the near vision. Ophthalmic lenses that compensate for presbyopia are multifocal lenses; the most suitable being the progressive multifocal lenses, on which the power varies continuously. Bifocal or trifocal lenses are also known, with breaks in continuity on the surface of the lens. The multifocal prescription is then referred to as the correction proposed for such carriers.

It is known to optimally calculate the front and / or rear faces of multifocal and unifocal lenses. For example, WO-A-98/12590 discloses a method for optimally determining a set of multifocal ophthalmic lenses. This document proposes to define the set of lenses by considering the optical characteristics of the lenses and in particular the power and the oblique astigmatism, under the conditions of the wearing. The lens is optimized by ray tracing, from an ergorama associating with each direction of view in the conditions of the carried a target object point. It is also known from EP-A-0 990 939 a method for optimally determining an ophthalmic lens for a wearer having an astigmatism prescription. This document proposes to choose a reference lens and to use a method of rays and minimize the difference between residual astigmatism and astigmatism of the reference lens. Residual astigmatism is defined in this document as the difference in amplitude and in axis between the prescribed astigmatism and the astigmatism generated by the lens. This method allows a better adaptation of the lenses to the astigmatic carriers, avoiding the optical aberrations induced by the addition of a toric surface. The calculation is made in a reference linked to the eye, which allows to take into account the torsional effect of the eye when the wearer looks in an eccentric direction.

Moreover, in recent years we have sought to personalize progressive ophthalmic lenses to better meet the needs of each wearer. It is thus known from WO-A-2007/068819 a method of optimally determining a set of progressive ophthalmic lenses for a given wearer to whom a power addition has been prescribed for near vision, the method comprising a step of measurement of individual physiological parameters of the wearer in near vision. The method also comprises a step of determining an ergorama associating, on each lens, a point aimed at each direction of view in the conditions of the wear and a step of determining a target of power failure and a target of resulting astigmatism for each direction of gaze under the wearing conditions, the target power defect and the resulting target astigmatism being determined from the measured physiological parameters of the wearer. The method further comprises calculating the power required on each lens for said ergorama by successive iterations to achieve the target power failure and target astigmatism defect for each direction of gaze.

It is also known from WO-A-2007/068818 a method of customizing the progression length of a progression lens.

It is also known from documents of measurements of physiological parameters and in particular the position of the center of rotation of the eye. Thus, the document WO-A-2008/132356 describes a method for determining the position of the center of rotation of the eye

US-B-6,637,880 discloses a method of ray tracing and lens optimization, taking into account the distance between a reference point of the rear surface of the lens and the center of rotation of the lens. eye of a wearer. This distance is obtained by adding the distance between the reference point of the rear surface and the vertex of the cornea on the one hand, and the distance between the vertex of the cornea and the center of rotation of the eye, on the other hand go. The distance between the reference point of the rear surface and the vertex of the cornea is calculated from data relating to the chosen frame; the document only proposes to take into account the shape of the wearer's head, data on the lens, the characteristics of the frame and the conditions of the wear, without providing details on the calculation. The distance between the vertex of the cornea and the center of rotation of the eye is obtained by measuring the depth of the eye and by applying a statistical law, connecting the depth of the eye and the distance between the top of the cornea and the center of rotation of the eye. In this document, the position of the center of rotation of the eye taken into account is not the actual position. As a result, the lens obtained by optimization does not perfectly satisfy the wearer. There is therefore a need for a method of determining an ophthalmic lens that satisfies the carriers better.

For this, the invention proposes a method for determining an ophthalmic lens for an eye of a wearer, the method comprising the steps of: measuring, on the carrier in binocular vision, the three-dimensional coordinates of the center of rotation of the eye of the wearer; measuring at least one direction of gaze in natural posture; determining the desired position of the ophthalmic lens; calculating the characteristics of the ophthalmic lens using the measured coordinates of the center of rotation of the eye, the determined position of the lens and the at least one viewing direction measured in natural posture.

According to one variant, the calculation step comprises a step of positioning a starting ophthalmic lens in the determined position and a step of modifying the starting ophthalmic lens by analyzing wave fronts.

According to a variant, the calculation step comprises a step of positioning a starting ophthalmic lens in the determined position and an optimization step, starting from the starting lens, by ray tracing depending on the measured coordinates and the determined position.

According to one embodiment, the method comprises a step of measuring on the wearer in binocular vision the position of the pupil of the eye relative to the center of rotation of the eye and in which the calculation step uses the position of the measured pupil.

According to one embodiment, the calculation step is carried out in a reference frame linked to the wearer's head, and / or in a frame linked to a frame, and / or in a frame linked to the wearer's eye.

According to one embodiment, the method further comprises a measurement step on the carrier in binocular vision, three-dimensional coordinates of the center of rotation of each eye of the wearer and wherein the calculation step is carried out in a reference frame which is function of the three-dimensional coordinates of the center of rotation of each eye of the wearer.

According to one embodiment, the step of measuring the three-dimensional coordinates of the center of rotation of the eye is carried out under conditions of natural posture of the wearer.

According to one embodiment, the center of rotation of the eye is the center of optical rotation.

According to the embodiments, the at least one viewing direction measured in natural posture is the primary direction of gaze and / or the gaze direction when the wearer look in near vision. Several directions of gaze can be measured in natural posture.

According to one embodiment, at the step of measuring the at least one viewing direction, a distance from the lens to the center of rotation of the eye is measured corresponding to the distance between the intersection of the primary direction of view with the rear face of the lens and the center of rotation of the eye, and in the calculation step, the calculation uses said measured distance.

According to one embodiment, at the step of measuring the at least one viewing direction, an orientation of the lens and a position of the lens are measured, and at the calculation step, the calculation uses said orientation of the lens. lens and said lens position measured. The invention also relates to a method for calculating the mounting and / or shaping parameters of an ophthalmic lens for a wearer and a frame chosen by the wearer, comprising the steps of:

- Determination of an ophthalmic lens according to the method of the invention;

measuring the position of the frame in the reference used for the measurement and determination steps;

calculation of the mounting and / or shaping parameters of the ophthalmic lens as a function of the position of the lens and the frame in the reference.

The invention also relates to a method for simulating an image viewed by a wearer through an ophthalmic lens, comprising the steps of: measuring, on the carrier in binocular vision, the three-dimensional coordinates of the center of rotation of an eye of the eye; carrier;

- measurement of at least one gaze direction in natural posture;

- positioning of the lens; the measurement and positioning steps taking place or being brought back in the same reference,

- Calculation of an image seen by the carrier by ray tracing taking into account the measured position of the eye's center of rotation, the viewing direction measured in natural posture and the position of the lens.

According to one embodiment, the simulation method comprises a measurement step in the reference of the position of the pupil of the eye and in which the calculation step uses the position of the measured pupil.

The invention also relates to a method of manufacturing an ophthalmic lens, comprising the steps of:

measuring at a first point on the carrier in binocular vision, three-dimensional coordinates of the center of rotation of an eye of the wearer and the position of a frame chosen by the wearer, in a same reference frame;

- measurement of at least one gaze direction in natural posture; - transmission to a second point of the coordinates and the position measured;

determination, at the second point, of the lens by calculation using the coordinates and the position measured; and

- manufacture of the lens thus determined. According to one embodiment, the manufacturing method further comprises a measurement step at the first point of angles representative of the natural posture of the wearer in the reference frame, in which

the transmission step includes transmitting the measured posture angles and

the determination step uses the measured posture angles. According to one embodiment, the manufacturing method further comprises a step of:

measuring the position of the frame in the reference used for the determination;

calculating the clipping parameters of the ophthalmic lens as a function of the position of the lens and the frame in the reference; and - trimming the lens.

The invention also relates to a data set comprising:

the three-dimensional coordinates measured, on the carrier in binocular vision, in a reference frame, of the center of rotation of an eye of a wearer;

angles representative of the natural posture of the wearer in the same reference frame; - the position of a mount in the same frame.

The invention also relates to a simulator of an image viewed by a wearer through an ophthalmic lens, the simulator comprising calculation means adapted to implement the simulation method according to the invention and image display means. calculated by the calculation means. The invention also relates to a computer program, comprising program means for performing the steps of the method for determining an ophthalmic lens according to the invention, when said program operates on a computer; as well as a computer program product comprising program code means stored on a computer readable medium, for carrying out the steps of the method of determining an ophthalmic lens according to the invention, when said product of program runs on a computer.

The invention also relates to a computer program, comprising program means for performing the steps of the simulation method according to the invention, when said program runs on a computer; as well as a computer program product comprising program code means stored on a computer readable medium, for implementing the steps of the simulation method according to the invention, when said program product is operating on a computer . According to one variant, the method for determining an ophthalmic lens as described above is characterized in that during the calculation step, the characteristics of the ophthalmic lens are calculated by locally modifying the ophthalmic lens at the point of impact with the average radius passing through the center of rotation of the measured eye for a given gaze direction.

Other features and advantages of the invention will appear on reading the following detailed description of the embodiments of the invention, given by way of example only and with reference to the drawings which show: FIG. 1, a flowchart an example of implementation of a method for determining an ophthalmic lens by wavefront propagation analysis;

FIG. 2, a flowchart of another example of implementation of a method for determining an ophthalmic lens by optimization by ray tracing; FIG. 3 is a flow diagram of an exemplary implementation of a method for calculating the clipping parameters of an ophthalmic lens;

- Figure 4, a flow chart of an example of implementation of a method of manufacturing an ophthalmic lens;

- Figure 5, a flow chart of an example of implementation of a simulation process of an ophthalmic lens;

- Figures 6 and 7, graphical representations of the optical characteristics of a lens of the prior art for a medium carrier;

FIGS. 8 to 10, graphical representations of the optical characteristics of a lens of the prior art for a real carrier; and FIGS. 11 to 13, graphical representations of the optical characteristics of a lens determined by the determination method for a real carrier; FIGS. 14 to 16, schematic representations illustrating the effect of a non-zero head posture; FIGS. 17 to 21, graphical representations of the astigmatism defects for several lenses according to whether the posture parameters are taken into account or not; Figures 22 to 24, schematic representations of an optical system eye and lens.

Figures 22 to 24 show schematics of optical eye and lens systems, to illustrate the definitions used in the description. More precisely, the figure

22 represents a diagram of a perspective view of such a system illustrating the parameters α and β used to define a gaze direction. Fig. 23 is a view in a plane vertical parallel to an anteroposterior axis of the wearer's head and passing through the center of rotation of the eye in a case where the parameter β is 0.

We call Q 'the center of rotation of the eye; the axis QT ', shown in FIG. 23 in phantom, is the horizontal axis passing through the center of rotation of the eye and extending in front of the wearer - in other words, the axis QT' corresponds to the primary direction the look. This axis intersects the complex surface of the lens at a point called a mounting cross, which is materialized on the lenses to allow positioning of the lenses by an optician. We define the point O, intersection point of the rear surface of the lens and the axis QT '. We define a sphere of vertices, of center Q ', and of radius q', which is tangent to the rear surface of the lens at a point on the horizontal axis.

A given direction of gaze - shown in solid lines in Figure 23 - corresponds to a position of the eye in rotation around Q 'and at a point J of the sphere of the vertices; the angle β is the angle formed between the axis QT 'and the projection of the line Q'J on the horizontal plane containing the axis QT'; this angle appears in the diagram of FIG. 22. The angle α is the angle formed between the axis Q'J and the projection of the line Q'J on the horizontal plane containing the axis QT '; this angle appears in the diagrams of FIGS. 22 and 23. A given direction of gaze therefore corresponds to a point J of the sphere of vertices or to a pair (α, β). The lower the value of the lowering angle of the gaze α, the lower the gaze and the lower the value, the more the gaze is lifted. The image of a point of the object space, in a direction of gaze, and at a given object distance, is formed between two points S and T corresponding to minimum and maximum focal distances, which would be sagittal focal distances and tangential in the case of surfaces of revolution. On the optical axis, the image of a point of the object space at infinity is formed at the point F '. The distance D is the focal length of the eye-lens system. An ergorama is called a function associating with each direction of the gaze the usual distance from the object point. Typically, in far vision in the primary direction of gaze, the object point is infinite. In near vision, in a direction substantially corresponding to an angle α of the order of 35 ° and at an angle β in absolute value of the order of 5 ° to the nasal side, the object distance is of the order of 30 to 50 cm. For more details on a possible definition of an ergorama, see FR-A-2 753 805 (US-A-6 318 859). This document describes an ergorama, its definition and its modeling process. A particular ergorama is to take only points to infinity. For the process of the invention, it is possible to consider points at infinity or not. The ergorama can also be a function of the wearer's ametropia. Using these elements, we can define a power and an astigmatism, in each direction of the gaze. For a gaze direction (α, β), we consider an object point M at an object distance given by the ergorama. In the object space, we define, for the point M on the corresponding light ray, a close object ProxO as the inverse of the distance MJ between the point M and the point J of the sphere of the vertices:

ProxO = 1 / MJ

This allows a calculation of object proximity in the context of a thin lens approximation at any point of the sphere of vertices, which is used for the determination of the ergorama. For a real lens, it is possible with the aid of a ray tracing program to consider the object proximity as the inverse of the distance between the object point and the front surface of the lens, on the corresponding ray.

Still for the same direction of gaze (α, β), the image of a point M having a given object proximity is formed between two points S and T respectively corresponding to minimum and maximum focal distances (which would be sagittal focal distances). and tangential in the case of surfaces of revolution). We call near image of the point M, the quantity Proxl:

By analogy with the case of the thin lens, we thus define, in a given direction of gaze and for a given object proximity, ie for a point of the object space on the corresponding light ray, an optical power Pui as the sum of the nearness image and the proximity object.

Pui = Pr oxO + Pr oxl

With the same notations, we define in each direction of the gaze and for a given object proximity, Ast astigmatism as

This definition corresponds to the astigmatism of the ray beam created by the lens.

We note that the definition provides, in the primary direction of gaze, the classic value of astigmatism. The angle of the astigmatism commonly called axis is the angle γ. The angle γ is measured in the reference (Q ', x _m , y _m , z _m ) linked to the eye and corresponds to the angle at which the S or T image is formed as a function of the convention used. with respect to the direction z _m in the plane (Q ', z _m , y _m ).

Thus, possible definitions of the optical power and the astigmatism of the lens, under the conditions of the wear, which can be calculated as explained in the publication of B. Bourdoncle and others, "Ray tracing through progressive ophthalmic lenses", 1990 International Lens Design Conference, DT Moore ed., Proc. Soc. Photo. Opt.

Instrum. Eng. Standard port conditions are the position of the lens relative to the eye of an average wearer, defined in particular by a pantoscopic angle of -8 °, a lens-eye distance of 12 mm, the curve of 0 °. Other conditions could also be used. The port parameters can be calculated using a ray tracing program for a given lens. Optical power and astigmatism may also be calculated in such a way that the prescription is reached at the reference point for distance vision or for a wearer wearing his spectacles under wearing conditions or as measured by a lensometer. .

FIG. 24 represents a perspective view in a configuration where the parameters α and β are non-zero. It thus highlights the effect of the rotation of the eye by showing a fixed reference {x, y, z} and a reference {x _m , y _m , z _m } linked to the eye. The reference {x, y, z} originates from the point Q '. The x axis is the Q'O axis and is oriented from the lens to the eye. The y axis is vertical and upward. The z axis is such that the reference {x, y, z} is orthonormal direct. The mark {x _m , y _m , z _m } is linked to the eye and has the center Q '. The axis x _m corresponds to the direction JQ 'of the gaze. Thus, for the primary direction of gaze, the two marks {x, y, z} and {x _m , y _m , z _m } coincide.

The invention uses, for determining the characteristics of an ophthalmic lens, the position of the center of rotation of the eye and the desired position of the ophthalmic lens relative to the center of rotation of the eye. At least one gaze direction in natural posture is measured. The position of the center of rotation of the eye is measured on the wearer in binocular vision. The characteristics of the lens are calculated using the coordinates of the center of rotation of the eye measured, the position of the desired lens determined relative to the center of rotation of the eye as well as the direction measured in natural posture.

The lens obtained by such a determination method has the advantage of taking into consideration a very precise position of the center of rotation of the eye. This makes it possible to obtain lenses that are better adapted to the wearer: the characteristics of the lens are calculated by zones on the lens each adapted to a given gaze direction which, in the case of the invention, is the real direction of gaze of the wearer. This allows an exact power correction for the considered carrier since for each direction of gaze the wearer will use a particular area of the lens that has been calculated to be used precisely in this way.

The proposed solution applies not only to progressive multifocal lenses, but also to lenses for a single-limb prescription. It is also possible to use the method with multifocal lenses, such as bifocal lenses or trifocal lenses. The determination method also applies to a lens optimized for particular wearing conditions.

The application of the method to the determination of a lens for an eye of the wearer is described below; the method can be applied to the determination of a lens for each of the eyes of a wearer. For this purpose, it suffices to calculate each of the lenses successively, it being understood that the measurement of the position of the center of rotation of each eye is measured in binocular vision.

FIG. 1 illustrates a flow chart of an exemplary implementation of a method for determining an ophthalmic lens for a wearer by wavefront propagation analysis. The determination method comprises a step 10 of measuring, on the carrier in binocular vision, three-dimensional coordinates of the center of rotation of an eye of the wearer.

The position of the center of rotation of a measured eye depends on the measurement conditions. In particular, a measurement of the three-dimensional coordinates of the center of rotation of the eye on a carrier in binocular vision gives a more accurate measurement of the actual position of the centers of rotation in the same frame.

The device described in WO-A-2008/132356 can be used for the measurement of the three-dimensional coordinates of the center of rotation of the eye. The invention is not limited to the use of this apparatus, and another apparatus may be used to measure the three-dimensional coordinates of the center of rotation of the eye. In any case, it is essential according to the invention that the measurement of the center of rotation of an eye is performed in binocular vision. Advantageously, the determination of the position of the center of rotation of the eye can be done by several successive measurements, in order to refine the accuracy of the measuring apparatus if necessary.

Successive measurements of the position in space (i.e., three-dimensional coordinates) of one eye and then the other eye - always in binocular vision - can be made.

It may also be advantageous to simultaneously measure the position of the center of rotation of the right eye and the left eye. After this step 10, the position of the center of rotation of the eye in space is known.

This position is given by three-dimensional coordinates in a coordinate system. As explained below, a reference change can be made to facilitate lens calculations.

The determination method according to FIG. 1 further includes a step 15 of measuring at least one gaze direction in natural posture. Such a step 15 is described more specifically in the following description.

In step 20, a determination is made of the desired position of the ophthalmic lens. For this determination, the apparatus described in WO-A-2008/132356 can be used again by providing the wearer with a frame he has chosen, with test lenses. Any other method may also be used, such as, for example, a traditional measurement of the position of the lens in the frame chosen by the wearer. It is advantageous to make this determination on the frame chosen by the wearer, which allows the adaptation of the frame to the wearer, and therefore a more accurate measurement of the desired position of the lens in the frame; one could also measure the physical characteristics of the wearer, and use the dimensions measured in advance of the chosen frame; this solution for simulating the position of the lens has the advantage of not requiring the mounting. The determination of the position of the lens can therefore result from a measurement or a simulation.

From this positioning step, it is possible to take into account the parameters for mounting and / or trimming the lens in a frame. Indeed, these parameters can change the spatial position of the lens in the frame. We can cite, for example, the location of the bevel: the lens-eye distance (or lens -center of rotation of the eye) is not the same if the bevel is positioned on the front face of the glass or on the rear face . The curvature of the glass can also affect the position (especially if the optician does not dress the frame). This step also makes it possible to calculate the necessary ribs for centering the lenses distance between the two centers of rotation of the eye (CROg, CROd) (which advantageously replaces the measurement of the interpupillary distance (ISO 13666 standard) with a conventional pupillometer). -differences inter CRO in the plane of the mount (by half-gaps inter CRO it is necessary to hear the distance which separates the projection of the center of rotation of the eye (CRO) according to the direction of gaze when the eye looks right ahead an eye-level object with the medial line of the eyeglass frame) mounting heights right eye and left eye in the plane of the frame II is also advantageous to use the same apparatus for the measurement of the coordinates of the center of rotation of the eye and for determining the desired position of the ophthalmic lens, since this avoids a change of reference to have, in the same reference, the position in the space, of the center of e rotation of the eye and the desired lens. Measurements with different devices are nevertheless possible with a simple change of reference. After the steps 10, 15 and 20, the desired position of the ophthalmic lens and the position of the center of rotation of the eye are known. The relative position, in space, of the desired lens and the center of rotation of the eye of the wearer is therefore known. In the example, the position of the center of rotation of the eye in step 10 was first determined, then a direction of gaze in the natural posture of the wearer in step 15, then the desired position of the At the same time, it is possible to proceed in the reverse order: in the same way, a relative position, in space, of the desired lens and the center of rotation of the eye of the wearer would be obtained in the same way. The determination method also includes a step of calculating the characteristics of the lens, using the coordinates of the center of rotation of the eye and the determined position of the desired lens. In the example of FIG. 1, it is possible, for example, to adapt this step of calculating a unifocal lens, that is to say a lens intended for a myopic or hypermetropic wearer, to whom it would be traditionally supplied. a spherical or toric lens.

The calculation step comprises the choice of a starting lens, which is for example, for the case of a single-vision prescription, the spherical or toric lens corresponding to the prescription of the wearer. This starting lens is the one that simplifies the calculation step the most, but one could use another starting lens.

In step 30, the starting lens is then positioned in the position determined in step 20. This positioning step does not involve physically arranging the lens in the frame; it consists simply of placing, for the calculation, the starting lens in the desired relative position relative to the center of rotation of the eye. In practice, it is possible to use for this positioning a representation of the starting lens in the form of a computer representation. The positioning step can be carried out using one or the other of the marks proposed below and by defining the position of the computer representation of the lens in this reference. For an astigmatism prescription, the position of the main axes of the lens is of course taken into account. As explained with reference to step 20, the trimming / mounting parameters for positioning the starting lens can be considered.

In step 40, the lens is calculated from the starting lens thus positioned, and knowing the position of the center of rotation of the eye and the direction measured in natural posture in step 15. For this purpose, wavefront analysis can be performed through the lens. The propagation of the wave fronts through the lens makes it possible to model the optical function of the lens as well as its associated defects and aberrations. The effects of the modifications made to the lens (modification of, for example, the front or rear surface in the case of a conventional lens characterized by the phenomena of refraction of the light or modification of, for example, the phase function in the case of a lens; diffractive lens) can therefore be studied and quantified so as to obtain the desired optical characteristics for the lens for the considered wearer.

Considering the lens trim / edit parameters, the geometric modification of the lens can lead to a change in the spatial position, if the trim / edit parameters are again applied to the modified lens. We can recalculate the parameters and then modify the lens again. The calculation loop can be stopped if the difference between the old and the new parameters is in an order of magnitude that does not influence the geometry of the new lens. We can also stop the calculation loop in case of divergence, and in the latter case impose other parameters of clipping / editing.

At the end of step 40, the characteristics of the lens were determined. As the method takes into account the position of the center of rotation of the eye measured in binocular vision, it is ensured that the center of rotation of the eye used for the calculation of the lens is very close to the center of rotation of the eye real, so that the lens is actually adapted to the wearer.

Taking into account the measurement, on the carrier in binocular vision, of the three-dimensional coordinates of the center of rotation of the eye of the wearer, in the context of the method of determining an ophthalmic lens for an eye of a wearer (determination monocular lens of an ophthalmic lens) also significantly improves the comfort of the wearer. This improvement in comfort is linked in particular to the fact that it is thus possible to take into account the segment defined by the center of rotation of the left eye and the center of rotation of the right eye (CROg-CROd). This segment is in fact a data that can be advantageously taken into account in the monocular determination of the ophthalmic lens. This segment makes it possible to spatially connect the two eyes of the wearer between them in a precise manner and therefore despite a monocular calculation of the lens, the relative position of the two eyes of the wearer can be taken into account to further clarify the calculation by taking into account notions of binocular vision. The two glasses for the same wearer are calculated separately but these calculations can, thanks to this measurement, be made interdependently to improve the visual comfort of the wearer in binocular vision.

Since the method also uses the determination of the desired position of the lens, the lens obtained by the method is not affected by a change in position due to the mount. If for example a carrier has a mount having a large inclination, this inclination is taken into account in the determination of the characteristics of the lens; the wearer therefore has a lens adapted to its prescription.

FIG. 2 illustrates a flow chart of an exemplary implementation of a method for determining an ophthalmic lens by optimization by ray tracing.

As in the example of FIG. 1, the determination method comprises a step 10 of measuring, on the carrier in binocular vision, the three-dimensional coordinates of the center of rotation of an eye of the wearer, a measurement step of minus a gaze direction in natural posture and a step 20 of determining the desired position of the ophthalmic lens. At the end of these three steps, we have the relative position, in space, of the center of rotation of the eye and the lens, as it will actually be worn by the wearer.

The calculation step includes choosing a starting lens. This starting lens does not correspond to a physical lens but to a computer modeling. This lens of departure can be chosen in different ways. This can be the one that simplifies the most the optimization step that follows. But one could also use another starting lens, for example, corresponding to given constraints, for example geometric types.

In step 60, the starting lens is then positioned in the position determined in step 20. The remarks made above with respect to step 30 apply, mutatis mutandis.

In step 70, the lens is calculated from the starting lens thus positioned and knowing the position of the center of rotation of the eye. For this purpose, one can proceed by optimization, from the starting lens, by ray tracing. The rays used are determined according to the center of rotation of the measured eye and the position of the lens.

The calculation step 70 may be carried out in different ways and in particular by optical optimization by an optimization program as described in the EP-A documents.

A-0 990 939 or WO-A-2007/017766. As explained with reference to FIG. 1, it is also possible for a better precision to take into consideration the parameters of trimming / mounting of the lens in a chosen frame.

The step of calculating the characteristics of the lens (steps 30 and 40 in FIG.

60 and 70 in FIG. 2) makes it possible to take into account, in the determination of the lens, the more precise binocular measurement of the real position of the center of rotation of the eye in a reference mark obtained at measurement step 10. This results in a lens having improved optical properties with respect to a determined lens without a precise consideration of the three-dimensional coordinates of the center of rotation of the wearer's eye, in binocular vision. Here, optical properties are understood to mean the quality of the image perceived by the wearer.

The optical properties thus include the power failure or the astigmatism defect. The calculation step also takes into account the position of the lens, as actually worn by the wearer, which is determined in step 20.

The calculation step also takes into account the direction measured in natural posture, as performed in step 15.

The lens is thus better adapted to the wearer for whom it is intended. The visual comfort of the wearer is thus maximized.

In the example of Figure 1 we considered a single-point prescription to illustrate the choice of the starting lens. However, the solution of wavefront analysis can be applied to other types of prescriptions (multifocal, for example) for all types of lenses (conventional lenses as well as microstructured glasses, adaptive glasses or gradient glasses). index).

The example of Figure 2 is particularly suitable for a multifocal prescription: the distribution of the rays during the ray tracing depending on the area of vision considered. It is also possible to apply the ray tracing optimization method to unifocal prescriptions, or for an atoric lens, for micro-structured glasses (pixilated glasses, diffractive glasses, Fresnel lenses), adaptive glasses or gradient-gradient glasses. index. The improvement of the optical properties mentioned above is illustrated by the examples of FIGS. 6 to 13. In this example, it is sought to determine a progressive lens for the following prescription:

- prescribed sphere: 4 diopters,

- prescribed cylinder: 0 diopters, - 0 ° axis,

- addition: 2 diopters.

The glass index is 1.665 and the diameter of the glass is 65 mm. The optical characteristics presented next in FIGS. 6 to 13 were obtained by calculation. Figures 6 and 7 relate to a lens of the prior art for a medium carrier for which the lens has been optimized by taking into account a theoretical position of the center of rotation of the eye. Here is meant mean carrier a carrier whose distance between the center of rotation of the eye and the glass is 26mm; this distance corresponds to the sum of the distance between the center of rotation of the eye and the vertex of the cornea and the distance between the vertex of the cornea and the glass, the latter also being called the glass-eye distance. Fig. 6 is a graphical representation of lines of equal power, i.e., formed lines of points having an identical power value. FIG. 6 thus makes it possible to display a power card. Figure 7 shows the lines of equal astigmatism. Figure 7 is thus a graphical representation of the astigmatism defect. The power at the far vision point is 4.00 diopters and 6.04 diopters at the near vision point. The astigmatism defect is 0.00 diopters at the far vision point and 0.13 diopters at the near vision point.

Figures 8 and 9 respectively show a power card and an astigmatism defect card for the same lens of the prior art (so always optimized for the average wearer) in the case of a real carrier. For the actual carrier selected, the distance between the center of rotation of the eye and the vertex of the cornea is 11 mm and the glass-eye distance is 10 mm. Moreover, FIG. 10 shows the power along the meridian, with a power definition similar to that given in document EP-A-0 990 939. The abscissas are graduated in diopters, and the ordinates give the direction of gaze; the solid line shows the power, and the broken lines the quantities 1 / JT and 1 / JS defined in FIG. 1 of EP-A-990 939, for object distances corresponding to an ergorama representative of the distances of the object points in each direction look and simulate a medium object space. FIG. 10 thus gives access to the lack of power and astigmatism along the meridian.

The power in the far vision direction is 4.02 diopters and 6.35 diopters in the near vision direction. The astigmatism defect is 0.03 diopters in the far vision direction and 0.59 diopters in the near vision direction. The comparison between FIGS. 6 and 8 shows, in particular, the appearance of a near vision power error. The comparison of Figures 7 and 9 show that when a real carrier is considered, the astigmatism may vary. In particular, in the example under consideration, the astigmatism fields are not as clear in far vision and near vision as when an average wearer was considered.

FIGS. 11 and 12 respectively show a power card and an astigmatism defect card for a lens obtained by the determination method according to the invention for the same real carrier. Figure 13 illustrates the defect of power and astigmatism according to the meridian for the lens for the same real carrier. The lens was determined as proposed with reference to FIG. 2 by ray tracing by positioning the lens in the desired position relative to the center of rotation of the eye in space, measured for the actual wearer in binocular vision. In Fig. 11, the power in the far vision direction is 4.00 diopters and 6.03 diopters in the near vision direction. In FIG. 13, the astigmatism defect is 0.00 diopters in the far vision direction and 0.20 diopters in the near vision direction. The optical performances obtained by the lens obtained by the determination method according to the invention are therefore comparable to the performances obtained in the case of FIGS. 6 and 7. The comparison of FIG. 10 with FIG. 13 also shows that the lens optimized according to FIG. method of determination has better optical properties than the lens of the prior art. As a result, a lens obtained by the determination method is better adapted to the wearer than the lens of the prior art.

In order to further improve the optical properties of the lens, it is advantageous that the center of rotation of the eye measured at measurement step 10 is the optical center of rotation rather than the center of mechanical rotation. Heinz DIEPES, Refraktionsbestimmung, ISBN 3-922269-50-8, DOZ Verlag, Optische Fachverofflichung GmbH Heidelberg contains the definition known to those skilled in the art for the center of optical rotation and the center of mechanical rotation. Indeed, in practice, the average radius that arrives in the wearer's eye passes through the optical center of rotation. The three-dimensional coordinates of this center of optical rotation can be determined in binocular vision by simultaneous binocular fixation of a target.

In the example of Figure 2, the method may also include a measuring step in the reference of the position of the pupil of the eye. The calculation step can then use the position of the pupil measured. This makes it possible to better take into account the aberrations that depend on the pupil. This results in an improvement in the image perceived by the wearer which thus comprises fewer aberrations.

Several different references can be envisaged for the implementation of the calculation step. In particular, the marker may be a marker linked to the wearer's head. Such a marker has the advantage of being easily accessible during the step of measuring the position of the center of rotation of the eye; it also remains easily accessible for the determination stage.

When the measuring step 10 is performed on a carrier carrying a mount, the mark may be linked to the mount. This provides a benchmark independent of the wearer. The measurement of the position of the center of rotation of the eye can be done directly in a frame linked to the frame. The determination of the position of the lens then simply consists in centering the lens in the frame, either by using the usual boxing parameters, or, as explained below, with a measurement under the natural posture conditions of the viewing directions of the frame. carrier. The implementation of the manufacture of the lens is also facilitated by the use of such a marker, especially if the step 10 of measuring the position of the center of rotation of the eye is not performed in the same place as the calculation step; it is sufficient that both places involved in the manufacture can have a mount of the same model.

It is also possible that the marker is a marker linked to the eye. A reference linked to the eye is a reference mark of which one of the axes is the primary direction of the gaze. This makes it possible to obtain a calculation step that is simpler to implement because the ray traces are made in a reference frame, one of whose axes is the optical axis of the eye-lens optical system.

It is also possible to use a benchmark calculated according to the three-dimensional coordinates of each of the centers of rotation of the wearer. Such a mark can be defined in particular in the following way: choice of the first axis passing through the two measured centers of rotation choice of the second axis such as including the mediator of the segment defined by the two centers of rotation and parallel to the plane of Frankfurt choice of third axis as it is perpendicular to the two previous axes. This has the advantage of allowing to position the head relative to the object space and to govern the kinematics of the two rotating eyes around their center of rotation.

The measuring step 10 can be carried out under the natural posture conditions of the wearer. By natural posture is meant the natural tendency of a wearer to take a preferential position of the head which is not that of a straight head when looking at a reference point. The preferred position may be characterized by posture angles with respect to a reference posture which may for example be the right head posture. Taking into account the conditions of the natural posture makes it possible to obtain a lens that is still better suited to the wearer's needs. Compared to the traditional method, in which it is assumed that the wearer always has the right head in far vision, the measurement in the natural posture conditions makes it possible to better take into consideration the real position of the wearer. If for example the wearer has in far vision head slightly bent forward, the far vision zone will be higher on the lens than with respect to the position of the far vision zone in a traditional lens. In the same way, it is also possible to take into account the natural posture condition when the wearer is looking in near vision, for example when the wearer reads a document. If, for example, the wearer has near vision the head slightly oriented on the side, the near vision area will be shifted to the same side on the lens as compared to the position of the near vision area in a conventional lens. In the traditional method, it is assumed that the wearer always looks at an object located in the sagittal plane when he looks closely at the vision.

Another method as illustrated by the flowcharts of FIGS. 1 and 2 is to perform an additional step in which at least one gaze direction in natural posture is measured. The effect of a non-zero head posture on the ophthalmic correction of a wearer is more particularly illustrated by the comparison of FIGS. 14 and 15. These two figures correspond to a particular illustration for the horizontal natural posture when the wearer looks in vision from a distance. A similar illustration would highlight the effect of a non-zero vertical natural posture. In Figure 14, two eyes with their correction lens are shown. In this situation, the natural posture of the head corresponds to a right head posture, that is to say a zero head posture. The coordinates of the rotation centers of the left eye noted OG and the right eye noted OD are given in a calculation reference R which is chosen arbitrarily. The calculation reference R is a three-dimensional coordinate system whose axes are the x, y and z axes. In this reference R, the coordinates xg, yg and zg are those of the center of rotation of the left eye and the coordinates xd, yd and zd are those of the center of rotation of the right eye. Each lens is positioned and oriented relative to the corresponding center of rotation. Each lens thus has a proper inclination linked to the frame. It is thus possible to define for each lens a specific three-dimensional mark denoted Ri g for the lens of the left eye and Ri_d for the lens of the right eye.

According to FIG. 14, the origin of the marker Ri g is the point G which corresponds to the intersection of the primary direction of gaze (gaze direction of the wearer when he is asked to look far ahead in front of him) and the face back of the lens. Thus, if the axes of the reference Ri_g are denoted xi_g, yi_g and zi_g, the axis yi_g is parallel to the axis y while the axis xi_g corresponds to tangent to the rear face of the lens in G. The axis zi_g being such that xi_g, yi_g and zi g form a direct trihedron. As a result, the axis zi g is normal to the rear surface in G. In addition, the reference mark of the left lens Ri g is deduced from the reference mark R by a rotation of angle βg around the y-axis in the plane (x, z), the rotation being effected in the counterclockwise direction, ie the counterclockwise direction. Thus, the axes xi_g and x on the one hand and zi_g and z on the other hand form an angle βg between them. The angle βg is linked to the frame.

According to FIG. 14, the origin of the marker Rj_d is the point D which corresponds to the intersection of the primary direction of gaze (gaze direction of the wearer when he is asked to look far ahead in front of him) and the rear face of the lens. Thus, if the axes of the reference Ri_d are denoted xi_d, yi_d and zi_d, the axis yi_d is parallel to the axis y while the axis xi_d corresponds to tangent to the rear face of the lens in D. The axis zi_d being such that xi_d, yi_d and zi_d form a direct trihedron. As a result, the axis zi_d is normal to the rear surface in D. In addition, the mark of the left lens Ri_d is deduced from the reference R by a rotation of angle βd around the y axis in the plane (x , z), the rotation being carried out anti-clockwise, ie clockwise. Thus, the axes xi_d and x on the one hand and zi_d and z on the other hand form an angle -βd between them. The angle βd is linked to the frame.

In a manner similar to FIG. 14, specific three-dimensional markers denoted Ri 'g for the lens of the left eye and Ri' d for the lens of the right eye are defined in the case of FIG. in Figure 15, the natural posture of the head is non-zero. For the sake of simplicity, all of the above notations and definitions are used for mount-related benchmarks with a "'" index. Thus, the axes xi'_g and x on the one hand and zi'_g and z on the other hand form an angle β'g between them. Similarly, the axes xi 'd and x on the one hand and zi' d and z on the other hand form an angle -β'd between them. The intersection of the primary direction of gaze with the rear face of the lens of the left eye is noted G 'and the intersection of the primary direction of gaze with the back side of the lens of the right eye is the point D '. To aid understanding, FIG. 15 illustrates at the same time the primary direction of gaze in the case of a natural position of the non-zero head (illustrated by the arrows in full lines) and the primary direction of gaze in the case of a natural position of the null head (illustrated by the arrows in dashed lines).

Figure 16 is an enlarged view of Figure 15 for the left eye. In comparison with FIG. 15, it is then found that the inclination of the lenses in the plane formed by the x and z axes is modified between a zero horizontal natural posture and a non-zero horizontal natural posture. This means that the angles βg and β'g are different. The other modification relates to the respective positions of the points G and G '. For ease of comparison, the point G has been indicated in FIG. 16, knowing that it no longer corresponds to the primary direction of the wearer in natural posture. Nevertheless, it is possible to observe that the lens is off-center by an amount ΔXg along the x axis and away from a quantity ΔZg along the z axis of the center of rotation of the left eye OG. The quantity ΔXg corresponds to the difference in coordinates along the x-axis between the point G 'and the point G whereas the quantity corresponds to the difference in coordinates along the z-axis between the point G' and the point G. In such a way similar, although the enlarged figure is not shown, the angles βd and β'd are different and the lens of the right eye is off-center by an amount ΔXd along the x axis and away from a quantity ΔZd according to the z axis of the center of rotation of the right eye OD. The quantity ΔXd corresponds to the difference in coordinates along the x axis between the point D 'and the point D whereas the quantity corresponds to the difference in coordinates along the z axis between the point D' and the point D.

Thus, the comparison of FIGS. 14 to 16 shows that the positions and orientations of the lenses in the case of a non-zero head posture are different with respect to the zero head posture situation. This implies that head posture induces changes in the use of lenses.

These changes also appear by comparison of the performances of the lenses in use condition illustrated from FIGS. 17 to 21 presenting astigmatism defect cards for lenses having the same prescription as the lenses of FIGS. 6 to 13 described previously. One of the performances is represented by the astigmatism defect maps of FIGS. 17 and 18. These astigmatism defects are represented in a reference frame linked to the left eye as defined in FIG. 24. For the two maps, the directions manholes are expressed in the origin reference defined when the wearer has a null head port. The gaze direction (α = 0, β = 0) corresponds to the primary gaze direction when the head port is zero. The card according to FIG. 17 corresponds to the case of a zero head posture whereas in the case of the card according to FIG. 18, the wearer has a non-zero head posture such as: β'g = βg -5 °. This shows that a non-zero head posture changes the distribution and amount of astigmatism of the lens when the lens has been optimized with the null head port condition. For example, in Fig. 17, the astigmatism defect in the far vision direction is 0.00 diopters and in the viewing direction near 0.13 diopters, and in Fig. 18 the astigmatism defect in the direction far vision is 0.05 diopters and in the direction of vision of nearly 0.49 diopters. In addition, a loss of right / left symmetry is observed on both sides of the meridian 12 in FIGS. 17 and 18. The meridian corresponds to the mean direction of gaze when the wearer looks from vision to vision from close. In addition, the iso-astigmatism curves are shifted to the nasal side.

The effects highlighted above for non-zero horizontal head posture also exist in the case of non-zero vertical head posture. In such a situation, the vertical inclination angle around x in the y, z plane would be modified and the lens would be eccentric vertically along y and away from or closer to the optical rotation center according to the considered eye. In addition, in the case of a non-zero horizontal head posture and non-zero vertical head posture, there would be a combination of the previously mentioned effects, namely a change in horizontal and vertical tilt angles as well as that a decentration of the lens both horizontally and vertically and a change in the distance between the lens and the center of rotation of the associated eye. Distance between the lens and the center of rotation of the eye means the distance between the point of intersection of the primary direction of view with the rear face of the lens on the line z and the center of rotation of the eye. eye.

As a result, the position of the lens with respect to the center of rotation of the eye and in particular the directions of the gaze retained for the calculations of power and astigmatism are more representative of the reality when the posture is taken into consideration. rather than an average posture determined by statistical methods or zero posture. Such a benefit can be demonstrated by comparing Figures 18 and 19. These are each cards representing the astigmatism defect for two lenses. For each of the figures, the horizontal natural posture of the wearer is such that β'g = βg - 5 °. These astigmatism defects are represented in a reference linked to the left eye as defined in FIG. 24. For the two maps, the manhole directions are expressed in the origin reference defined when the wearer has a head port. nothing. The gaze direction (α = 0, β = 0) corresponds to the primary gaze direction when the head port is zero. For the lens according to the example of FIG. 18, the posture was not taken into account in the calculation of the characteristics of the ophthalmic lens whereas for the lens according to the example of FIG. 19, the natural posture of the wearer has been taken into account in the calculation of the characteristics. It is then possible to note that the distribution of astigmatism is different between the two situations. In particular, in FIG. 18, the astigmatism defect in the far vision direction is 0.05 diopters and in the viewing direction close to 0.49 diopters, and in FIG. 19, the astigmatism defect in the direction far vision is 0.00 diopters and in the direction of vision nearly 0.18 diopters. In addition, the symmetry of the distribution of the astigmatism defect is found in relation to the situation where the head posture is zero (see Figure 17). Taking into account the natural posture of the wearer in the calculation of the ophthalmic lens therefore makes it possible to better adapt the lens to the wearer.

According to one embodiment, it is possible not to take into account the decentering effects induced by the natural posture of the wearer in the calculation. Only the modification of the orientation of the lens and the change of the distance between the lens and the center of rotation of the associated eye are then taken into account in the calculation of the characteristics of the lens. This simplifies the calculation while maintaining good performance for the lens because the optician can during the centering operation offset the decentering effect by off-centering the lens. This is illustrated by the examples in FIGS. 20 and 21. These are each cards representing the astigmatism defect for two lenses. For each of the figures, the horizontal natural posture of the wearer is such that β'g = βg - 5 °. These astigmatism defects are represented in a reference linked to the left eye as defined in FIG. 24. For the two maps, the manhole directions are expressed in the origin reference defined when the wearer has a head port. nothing. The gaze direction (α = 0, β = 0) corresponds to the primary gaze direction when the head port is zero. The lens according to the example of FIG. 20 was obtained by not taking into account any effect due to non-zero head posture (modification of the orientation of the lens, change of the distance between the lens and the center of rotation of the lens). the eye, induced decentering) in the calculation. On the contrary, the modification of the orientation of the lens and the change of the distance between the lens and the center of rotation of the eye have been taken into account during the calculation for the lens according to the example of FIG. In both cases, the decentering effect was taken into account by the optician during the centering operation. It is observed that when no effect is taken into account during the calculation but that the effect of the decentering is compensated by the optician, the lines of iso-astigmatism are not shifted towards the nasal side. In comparison with Figure 18, this is explained by the operation performed by the optician. But, the distribution of astigmatism defects is different compared to the case of Figure 17 corresponding to a zero natural posture and the symmetry of the distribution is lost. This is not the case of the lens according to the example of Figure 21. This shows that only taking into account the change in the orientation of the lens and the change in the distance between the lens and the center rotation of the associated eye in the calculation makes it possible to find the performance of the lens optimized with a zero head wearing condition provided that the optician compensates for the decentering induced by the non-zero head posture.

The use of the measurement of the center of rotation of the eye in binocular vision is also proposed in a method for calculating the clipping parameters of an ophthalmic lens for a wearer and a frame chosen by the wearer. FIG. 3 illustrates a flowchart for implementing such a method. The method comprises a step 100 for determining an ophthalmic lens according to the determination method described above with reference to FIGS. 1 and 2. Thus, according to the example of FIG. 3, step 100 comprises three steps that are the step 105 of measuring the position of the center of rotation of the eye in binocular vision in a marker, the step 110 of measuring the position of the pupil in the marker, the step 115 of measuring at least one direction in natural posture and step 120 for determining the position of the frame relative to the center of rotation of the eye.

Step 130 is the step of calculating the characteristics of the lens, from a starting lens positioned in the desired position relative to the center of rotation of the eye. The method also comprises a step 140 for calculating the clipping parameters of the ophthalmic lens as a function of the position of the lens and the frame in the reference. The knowledge of the clipping parameters of the lens makes it possible to machine or cut the contour of the lens to adapt to the frame chosen by the wearer. Once used, the clipping information obtained makes it possible to obtain lenses that are particularly well adapted to the wearer.

This is particularly the case when using a measurement of the directions of the gaze of the wearer in a natural posture. Instead of considering directions of gaze for an average wearer - for example a direction of the gaze in far vision corresponding to the right head - one can consider the natural posture of the wearer, horizontally or vertically.

The use of the information or clipping data is done during a lens trimming step that can be performed in the same place as the place where the computation step 130 was performed or in a different place.

More generally, other data sets may be used for the manufacture of a lens. For example, a data set may include the three-dimensional coordinates, measured on a carrier in binocular vision, of the center of rotation of an eye of a wearer, expressed in a marker. The data set also includes the position in the same frame of a mount. The data set may also include angles representative of the natural posture of the wearer in the same frame. Such data sets have the advantage of making it possible to obtain, by calculation, lenses that are well adapted to the wearer.

Thus, the previously described data sets can in particular be used in a method of manufacturing a lens. Figure 4 is a flow chart of an example of implementation of such a manufacturing method. The method comprises a step 200 of measuring at a first point, on the carrier in binocular vision, three-dimensional coordinates of the center of rotation of an eye of the wearer in a marker. The first point can be a place for selling lenses. At this measurement step 200, the position of a frame chosen by the wearer is also measured in the same frame.

The manufacturing method further comprises a step 220 of the transmission to a second point of the coordinates and the measured position. The second point may be in particular a prescription laboratory which, from any semi-finished glasses, obtains lenses having the characteristics of the prescription of the wearer. In the transmission step 220, it is possible to transmit other data such as the prescription of the wearer that the ophthalmologist or the optician usually notes in the form of a triplet (sphere, cylinder, axis) in a given convention. either "positive cylinder" or "negative cylinder". As the ophthalmologist (or optician) can also measure carrier specific wearing conditions, including the eye-to-eye distance, the pantoscopic angle and the curvature of the selected frame can also be transmitted to step 220 of transmission.

The manufacturing method also comprises a step 230 for determining, at the second point, the lens by calculating the characteristics of the lens by ray tracing. passing through the center of rotation of the eye measured from an initial lens positioned in the reference relative to the center of rotation of the eye.

The manufacturing method further comprises a step 240 for manufacturing the lens thus determined. The manufacture can be implemented in any place. It may be the first and second place but another place is possible. For example, the prescription laboratory may receive the data transmitted at the transmission step 220 in the second location and implement the manufacturing at a third location. The second location can then be a central processing data transmitted and the third place a factory for manufacturing lenses. Such a method has the advantage of allowing a faster manufacture of the glasses, the lens being able to be manufactured just after the measurement.

The manufacturing method can also comprise the steps of measuring the position of the frame in the reference used for the determination, calculating the contouring parameters of the ophthalmic lens as a function of the position of the lens and the frame in the reference frame. and trimming the lens. This makes it possible to obtain a cut-out lens adapted to the wearer.

The method may further comprise a step 210 of measuring at the first point angles representative of the natural posture of the wearer in the reference. According to the example of FIG. 4, the step 210 for measuring the natural posture takes place after the measurement, for the wearer in binocular vision of the three-dimensional coordinates of the center of rotation of an eye of the wearer. Nevertheless, it is possible to carry out these two measurement steps 200, 210 in a separate order.

The transmission step 220 can then comprise the transmission of the measured posture angles and the determination step 230 can use the measured posture angles. The manufactured lens is thus better suited to the wearer. The use of the measurement of the center of rotation of the eye in binocular vision is also proposed for a simulator of an image seen by a wearer through an ophthalmic lens. Such a simulator is thus adapted to implement a method of simulating an image seen by a wearer through an ophthalmic lens. FIG. 5 illustrates an exemplary flow chart for implementing such a simulation method. The simulation method comprises a step 300 of measuring, on the wearer in binocular vision, three-dimensional coordinates of the center of rotation of an eye of the wearer in a reference frame. By way of illustration, just as for the determination method described above, the marker may be a marker linked to the head of the wearer, a marker may be linked to the frame when a frame has been selected or a marker linked to the eye. The simulation method also comprises a step 305 for measuring at least one gaze direction in natural posture. The simulation method further comprises a step 310 of positioning the lens in the same frame.

The method also includes a step 320 of calculating an image seen by the wearer by ray tracing through the center of rotation of the eye and the lens. Since the simulation process takes into account the real position of the center of rotation of the eye, the simulated image is closer to reality than if an approximate position of the center of rotation of the eye had been taken into account. The calculation also takes into account the gaze direction measured in natural posture.

The simulation method may further comprise a measurement step in the reference of the position of the pupil of the eye. The calculation step 320 then uses the position of the measured pupil. This makes it possible to better simulate the image because the impact of out-of-field aberrations that depend on pupil size on the image is calculated more accurately.

The simulator for implementing this method comprises calculation means adapted to implement the simulation method; it can be associated with means known per se data entry. The simulator further comprises means for displaying the calculated image. It is thus possible to show a wearer the difference between a lens according to the invention and a conventional lens, to enable him to appreciate the effects of the invention.

In the above description, we have seen that the method of determining an ophthalmic lens for an eye of a wearer comprises a step of calculating the characteristics of the ophthalmic lens using the measured coordinates and the determined position. We have also seen that this calculation step could be declined according to either a step of modifying the starting ophthalmic lens by wavefront analysis or alternatively by optimizing, starting from the starting lens, by tracing of radiation-dependent rays. measured coordinates and the determined position. Other variants are also possible. For example, according to a third alternative, during the calculation step, the characteristics of the ophthalmic lens are calculated by local modification of the ophthalmic lens at the point of impact with the mean radius passing through the center of rotation of the measured eye. for a given gaze direction. According to this third alternative, it is thus possible to obtain desired optical properties from, for example, pre-calculated data stored in a database. These pre-calculated data can be, for example, pieces of surfaces or geometric characteristics to be applied locally to the surface such as, for example, a radius of curvature or asperity coefficients.

Claims

1. A method for determining an ophthalmic lens for an eye of a wearer, the method comprising the steps of: measuring (10), on the wearer in binocular vision, the three-dimensional coordinates of the center of rotation of the eye the bearer;

measuring (15) at least one gaze direction in natural posture;

- determining (20) the desired position of the ophthalmic lens;

calculating the characteristics of the ophthalmic lens by using the measured coordinates of the center of rotation of the eye, the determined position of the lens and the at least one view direction measured in natural posture.

The method of claim 1, wherein the calculating step comprises:

a positioning step (30) of a starting ophthalmic lens in the determined position; a step of modifying (40) the ophthalmic lens of departure by analyzing wave fronts.

The method of claim 1, wherein the calculating step comprises:

a step of positioning an ophthalmic lens of departure in the determined position; an optimization step, starting from the starting lens, by ray tracing depending on the measured coordinates and the determined position.

The method according to claim 1, 2 or 3, wherein the method comprises a step of measuring on the wearer in binocular vision the position of the pupil of the eye relative to the center of rotation of the eye and in which the calculation step uses the position of the measured pupil.

5. The method according to one of claims 1 to 4, wherein the calculation step is carried out in a reference frame linked to the wearer's head, and / or in a frame linked to a frame, and / or in a landmark linked to the eye of the wearer.

6. The method according to one of claims 1 to 4, further comprising a measurement step on the carrier in binocular vision, three-dimensional coordinates of the center of rotation. each eye of the wearer and in which the calculation step is carried out in a reference which is a function of the three-dimensional coordinates of the center of rotation of each eye of the wearer.

7. The method according to one of claims 1 to 6, wherein the step of measuring the three-dimensional coordinates of the center of rotation of the eye is carried out under natural posture conditions of the wearer.

8. The method according to one of claims 1 to 7, wherein the center of rotation of the eye is the optical center of rotation.

9. The method according to one of claims 1 to 8, wherein the at least one view direction measured in natural posture is the primary viewing direction.

The method according to one of claims 9, wherein at the step of measuring the at least one viewing direction, a distance from the lens to the center of rotation of the eye is measured corresponding to the distance between the intersection of the primary direction of gaze with the rear face of the lens and the center of rotation of the eye, and in the calculation step, the calculation uses said measured distance.

11. The method according to one of claims 1 to 10, wherein the at least one gaze direction measured in natural posture is the direction of gaze when the wearer looks in near vision.

12. The method according to one of claims 1 to 10, wherein several viewing directions are measured in natural posture.

The method according to one of claims 1 to 12, wherein at the step of measuring the at least one viewing direction, an orientation of the lens and a position of the lens are measured, and at step calculation, the calculation uses said orientation of the lens and said position of the lens measured.

14. A method of calculating the mounting and / or trimming parameters of an ophthalmic lens for a wearer and a frame chosen by the wearer, comprising the steps of:

- determining an ophthalmic lens according to the method of one of claims 1 to 13;

measuring the position of the frame in the reference used for the measurement and determination steps; calculation of the mounting and / or shaping parameters of the ophthalmic lens as a function of the position of the lens and the frame in the reference.

15. A method of simulating an image viewed by a wearer through an ophthalmic lens, comprising the steps of: measuring, on the carrier in binocular vision, the three-dimensional coordinates of the center of rotation of an eye of the wearer;

- measurement of at least one gaze direction in natural posture,

16. The simulation method according to claim 15, wherein the method comprises a step of measuring in the reference of the pupil position of the eye and wherein the calculating step uses the position of the measured pupil.

17. A method of manufacturing an ophthalmic lens, comprising the steps of:

- measurement of at least one gaze direction in natural posture,

- transmission to a second point of the coordinates and the position measured;

determination, at the second point, of the lens by calculation using the coordinates and the position measured; and - manufacture of the lens thus determined.

The method of claim 17, further comprising a step of measuring at the first point angles representative of the natural posture of the wearer in the marker, wherein

the transmission step comprises the transmission of the measured posture angles and the determination step uses the measured posture angles.

19. The method according to one of claims 17 or 18, further comprising a step of:

measuring the position of the frame in the reference used for the determination; calculating the clipping parameters of the ophthalmic lens as a function of the position of the lens and the frame in the reference; and

- clipping of the lens.

19. A set of data comprising: the three-dimensional coordinates measured, on the carrier in binocular vision, in a reference frame, of the center of rotation of an eye of a wearer;

angles representative of the natural posture of the wearer in the same reference frame;

- the position of a mount in the same frame.

20. A simulator of an image seen by a wearer through an ophthalmic lens, the simulator comprising calculation means adapted to implement the simulation method according to one of claims 15 or 16 and means for visualizing the image. image calculated by the calculation means.

21. A computer program, comprising program means for performing the steps of any one of claims 1 to 13, when said program is running on a computer.

A computer program product comprising program code means stored on a computer readable medium, for implementing any one of claims 1 to 13, when said program product is operating on a computer.

23. A computer program, comprising program means for performing the steps of one of claims 15 or 16, when said program is running on a computer.

A computer program product comprising program code means stored on a computer readable medium, for implementing one of claims 15 or 16, when said program product is operating on a computer.

25. The method of determining an ophthalmic lens according to claim 1, characterized in that during the calculation step, the characteristics of the ophthalmic lens are calculated by local modification of the ophthalmic lens at the point of impact with the radius. means passing through the center of rotation of the measured eye for a given gaze direction.