Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
  • G02C7/00—Optical parts
  • G02C7/02—Lenses; Lens systems ; Methods of designing lenses
  • G02C7/06—Lenses; Lens systems ; Methods of designing lenses bifocal; multifocal ; progressive
  • G02C7/061—Spectacle lenses with progressively varying focal power
• • G—PHYSICS
  • G02—OPTICS
  • G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
  • G02C7/00—Optical parts
  • G02C7/02—Lenses; Lens systems ; Methods of designing lenses
  • G02C7/024—Methods of designing ophthalmic lenses
  • G02C7/025—Methods of designing ophthalmic lenses considering parameters of the viewed object
• • G—PHYSICS
  • G02—OPTICS
  • G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
  • G02C7/00—Optical parts
  • G02C7/02—Lenses; Lens systems ; Methods of designing lenses
  • G02C7/024—Methods of designing ophthalmic lenses
  • G02C7/028—Special mathematical design techniques
• • G—PHYSICS
  • G02—OPTICS
  • G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
  • G02C2202/00—Generic optical aspects applicable to one or more of the subgroups of G02C7/00
  • G02C2202/08—Series of lenses, lens blanks

Definitions

• the present invention relates to a set of progressive multifocal ophthalmic lenses; it also relates to a method for determining an ergorama for a set of progressive multifocal ophthalmic lenses, said ergorama associating for each lens a point aimed at each direction of gaze under the conditions of wear. Finally, it also relates to a process for defining a progressive ophthalmic lens.
• Progressive multifocal ophthalmic lenses are now well known. They are used to correct presbyopia and allow the wearer of glasses to observe objects over a wide range of distances, without having to remove their glasses. Such lenses typically include a far vision zone, located at the top of the lens, a near vision zone, located at the bottom of the lens, an intermediate zone connecting the near vision zone and the vision zone. from afar, as well as a main progression meridian crossing these three zones.
• Document FR-A-2 699 294 describes in its preamble the various elements of such a progressive multifocal ophthalmic lens, as well as the work carried out by the applicant to improve the comfort of the wearers of such lenses. Reference is made to this document for more details on these various points.
• the Applicant has also proposed, for example in patents US-A-5,270,745 or
• these progressive multifocal lenses comprise an aspherical front face, which is the face opposite to the wearer of the glasses, and a spherical or toric rear face, directed towards the wearer of the glasses.
• This spherical or toric face makes it possible to adapt the lens to the ametropia of the user, so that a progressive multifocal lens is generally defined only by its aspherical surface.
• an aspherical surface is generally defined by the altitude of all its points.
• n being the refractive index of the material of the lens, are called mean sphere or power and cylinder.
• Families of progressive multifocal lenses are defined, each lens of a family being characterized by an addition, which corresponds to the variation in power between the far vision area and the near vision area. More precisely, the addition, noted ⁇ . corresponds to the power variation between a point 1, of the far vision zone and a point P of the near vision zone, which are respectively called far vision measurement point and far vision measurement point close up, and which represent the points of intersection of the gaze and the surface of the lens for a vision at infinity and for a vision of reading.
• the addition varies from one lens to another in the family between a minimum addition value and a maximum addition value.
• the minimum and maximum values of addition are 0.75 diopters and 3.5 diopters respectively, and the addition varies from 0.25 diopters to 0.25 diopters from one lens to another in the family.
• Lenses of the same addition differ in the value of the mean sphere at a reference point, also called the base.
• the invention provides a progressive multifocal ophthalmic lens whose aesthetics are improved and which has increased performance compared to known lenses while preserving the ease of adaptation of semi-finished lenses to a wearer. While retaining this ease of implementation, the invention ensures that the adaptation of the lenses by simple machining of the rear face does not induce vision defects, even when the rear face is different from the rear lace used for optimization.
• the invention proposes a set of progressive multifocal ophthalmic lenses, determined by means of ergoramas associating for each lens a point aimed at each direction of gaze under the conditions of wear, in which for a lens under the conditions of wear, a carrier power is defined in a viewing direction and for an object point as the sum of the object proximity and the image proximity of said object point, in which each of the lenses has a first and a second surface, the first surface being a surface progressive multifocal; a far vision zone, a near vision zone and a main progression meridian crossing these two zones, the far and near vision zones and the meridian being sets of directions of gaze under the conditions of wear; an addition of power A equal to the variation in carrier power for the target point of the ergorama between a direction of reference gaze in the far vision zone and a direction of reference gaze in the near vision zone; and in which, the variations along the meridian, of the carrying power for the target point of the ergorama.
• the lenses are substantially identical for all the lenses of the game having the same addition.
• the lenses each have a prescribed addition chosen from a discrete set, the difference in power addition A between two lenses of the set having the same prescribed addition being less than or equal to 0.125 diopters.
• an astigmatism aberration in a direction of the gaze under the conditions of the wear being defined for an object point, that for any lens, on the meridian, the astigmatism aberration for the point targeted by the ergorama is less than or equal to 0.2 diopters.
• an aberration of astigmatism in a direction of gaze under the conditions of wear being defined for an object point, for each of the lenses in the conditions of wear, the angular width in degrees between the lines for which the astigmatism aberration for the ergorama points is 0.5 diopters, at 25 ° below a lens mounting point has a value greater than 15 / ⁇ + 1, A being the addition of power.
• an astigmatism aberration in a direction of gaze under the conditions of wear being defined for an object point, that for each of the lenses under the conditions of wear, the angular width in degrees between the lines for which the astigmatism aberration for the ergorama points is 0.5 diopters, at 35 ° below a lens mounting point has a value greater than 21 / A + 10, A being the addition of power.
• an aberration of astigmatism in a direction of gaze under the conditions of wear being defined for an object point, for each of the lenses in the conditions of wear, the solid angle bounded by the lines for which the astigmatism aberration for the ergorama points is 0.5 diopters, and the points located at a 45 ° angle from a lens mounting point has a value greater than 0.70 steradians.
• the difference in carrying power between the target point of the ergorama and the object points whose proximity has a difference with the proximity of said target point between 0 and 0.5 diopters is less than or equal to 0.125 diopters in absolute value.
• the difference in carrying power between the target point of the ergorama and the object points whose proximity presents a difference with the proximity of said target point less than I diopter in absolute value es (less than or equal to 0.125 diopters in absolute value.
• an aberration of astigmatism in a direction of gaze under the conditions of wear being defined for an object point, for each of the lenses in the conditions of wear, in the far vision zone, in each direction of the look, the difference in astigmatism aberration between the target point of the ergorama and the object points whose proximity presents a difference with the proximity of said target point between 0 and 0.5 diopters, is less than or equal to 0.125 diopters in value absolute
• an astigmatism aberration in one direction of gaze under the conditions of wear being defined for an object point, as for each of the lenses in the conditions of wear, in the near vision zone, in each direction of the look, the difference in astigmatism aberration between the target point of the ergorama and the object points whose proximity presents a difference with the proximity of said point targeted in absolute value less than 1 diopter, is less than or equal to 0.125 diopters in absolute value.
• the invention also proposes a method for determining an ergorama for a set of progressive multifocal ophthalmic lenses, said ergorama combining for each a point lens aimed at each direction of view in the door conditions, including the steps of
• the step of determining the direction of the gaze for the other object points of the environment may include, for each of said other points
• the subject of the invention is a process for defining a piogressive ophthalmic lens, by optimizing the optical characteristics of an ophthalmic lens, said optical characteristics being calculated at the corners of the optimization using a pi ogiamme of trace of i have, in the door conditions
• the optical characteristics can be the carrying power and the aberration of astigmatism, under the conditions of the carried.
• the optimization consists in minimizing by iterations the differences between the optical characteristics of the lens and the target values, and the power values obtained according to the target are used as target values for the carrier power.
• process referred to above for defining a progressive ophthalmic lens the optimization consists in minimizing by iterations the differences between the optical characteristics of the lens and the target values, and the values of astigmatism are used as target values for the aberration of astigmatism.
• optimization advantageously consists in varying a variable aspherical layer added to said starting lens.
• Figure 10 a representation similar to that of Figure 8, in which we have however added the graphical representations of the carrier optical powers for lenses corresponding to the extreme optical powers for each base;
• R j and R- are the maximum and minimum radii of curvature expressed in meters, and n the index of the material constituting the lens.
• the invention proposes to define the characteristics of the lenses not only in terms of mean sphere or cylinder, but to take into consideration the situation of the wearer of the lenses.
• Figure 1 shows a diagram of an eye and lens optical system for this purpose.
• the median plane of the lens is inclined relative to the vertical by an angle corresponding to the usual inclination of spectacle frames. This angle is for example 12 °.
• a given direction of gaze corresponds to a point .1 of the sphere of the vertices, and can also be located, in spherical coordinates. by two angles alpha and beta.
• the angle alpha is the angle formed between the line Q'J and the horizontal plane passing through the point Q '
• the angle beta is the angle formed between the line Q'J and the vertical plane passing by point
• a given direction of the gaze corresponds to a point .1 of the sphere of the vertices or to a couple (alpha, beta).
• an object proximity PC we define, for a point M on the corresponding light ray, an object proximity PC) as the inverse of the distance MJ between point M and point.
• This astigmatism aberration corresponds to the astigmatism of the beam of rays created by the aspherical front surface and the spherical rear surface.
• an ergorama is also defined, which gives proximity to an object and a carrying power for each eye detection.
• the ergorama is defined for " ⁇ a given situation of the carrier. Ie for an additional ametropia couple.
• the ergorama is thus a function which has four variables - ametropia. addition, and direction of the gaze in the form of alpha and beta angles - associates two values - object proximity and carrier power
• the ergorama thus defined can be determined by physiological studies and tests. 0 eigonomic and postural, and by the knowledge of optical laws. We can in particular consider
• a method of determining the ergorama is described, for a given ametropia, for example by a power at point L of far vision, and for a given addition.
• the detection of the gaze and the power for looking at the point of near vision are determined.
• Figure 2 shows a flowchart * î of the different stages of defining the reference point for near vision and calculating the Donders curve of the wearer As explained above, we start by determining the direction of gaze and the power to look at the point of near vision.
• the standard carrier has the following characteristics: it is isometric and orthophoric, the two eyes accommodate the same quantity and move the same quantity. in case of version el symmetrically in case of vergence; the pupillary distance is 65mm. the distance between glass and center of eye rotation of 27mm, the distance between center of eye rotation and center of rotation of the head is 100mm. and the pantoscopic angle is 12 °.
• the center of ocular rotation is the point noted Q 'in Figure 1.
• the inclination of the head is given by the position of the plane of FRANCFOR T relative to the horizontal, as explained in patent applications FR- ⁇ -2,683,642 and FR-A-2,683,643 in the name of the applicant .
• the standard lowering of the eyes is 33 ° and the lowering of the head of 35 ° so that the work plan is parallel to the average vertical horopter.
• step 20 We then choose a work environment, step 20.
• Figure 2 to then position the standard carrier chosen in step 10.
• the central point M located at the 2/3 highs of this document is the place where the wearer naturally places his gaze and will constitute a first point of reference, for near vision.
• This point M is placed at the near vision distance given by the addition and for a total inclination of the standard gaze of 68 °. or the sum of 33 ⁇ and 35 ° relative to the horizontal.
• step 30 of FIG. 2 a lens is introduced and the variations in the direction of gaze caused by the presence of the lens are calculated.
• One carries out the corresponding calculations in approximation of thin lens, in all the points of the sphere of the vertices. In other words, we consider at all points of the sphere of vertices an infinitesimal thin lens whose Tax passes through the optical center of rotation of the eye.
• FIG. 3 schematically shows the right eyes OD and the left OG and in dotted lines the direction of gaze, to look at the reference point for near vision M.
• the carrying power, in the direction corresponding to the gaze of point M is equal to the sum of the distance vision power and the addition.
• a thin lens having a corresponding power represented by dotted lines in FIG. 3
• the rays are deflected, as shown in solid lines in FIG. 3, so that the fixed point is no longer the point M but point M '.
• Figure 3 shows a plan view: it is however clear that deviations are generated not only in a horizontal plane, but also in a vertical plane.
• step 20 The inclination determined in step 20 is thus modified by the introduction of the glass onto the optical path because of the prismatic deviations induced by the power encountered on the glass which must be equal to the prescribed VL power increased by the prescribed addition. .
• step 40 of FIG. 2 the movements of the eyes and possibly of the head making it possible to correct these prismatic deviations are determined.
• the vertical prismatic deviation is compensated by a vertical movement of the eyes and by movements of the head to be able to fix this point.
• the part of each organ in this compensation depends on the ametropia of the wearer. For powers VL less than -2 diopters, it is considered that the compensation is completely ensured by the eyes. For ametropia of +2 diopters and beyond, the part of the head in the compensation is total, that is to say that the eyes do not move.
• the thin lens approximation calculations are again carried out at any point of the vertex sphere, as explained with reference to step 30.
• step 40 the movements of the eyes and possibly of the head were determined making it possible to correct these prismatic deviations, and therefore the direction of the gaze to look at the reference point of near vision.
• step 50 of FIG. 2 the subjective accommodation of the wearer is calculated from the position thus determined.
• the power on the lens, the position of the lens in front of the eye and the object distance to look at the reference point of near vision we know the power on the lens, the position of the lens in front of the eye and the object distance to look at the reference point of near vision.
• step 60 of FIG. 2 knowing this accommodation, and the direction of the gaze, the Donders law applicable to the wearer is determined. This law provides, as a function of age, a relationship between convergence and accommodation.
• Figure 4 shows a graphical representation of Donders' law.
• the abscis.se shows the convergence in m. and ordinate accommodation in diopters.
• the curve in broken lines shows the relationship between these two quantities, for a young carrier (25 years).
• the solid and mixed lines curves show the relationship between these two quantities, respectively, for wearers aged 41 and 50.
• the limit of the horizontal part of the Donders curve is given by the maximum accommodation of the wearer, which depends on age. Age is related to addition, based on clinical studies.
• the wearer For scanning the document, it can generally be said that the wearer only moves his head to compensate for vertical prismatic deviations according to the rule described above. Most of the scanning of the document is therefore ensured by eye movements. Above the document, the head and the eyes move simultaneously to reach a final position such that the inclination of the eyes is zero when the inclination of the head is zero.
• a strategy for scanning the environment is thus defined, ie a set of points looked at in the environment, and associated positions of the eyes and the head.
• step 100 we take a point from the environment.
• the environment is described in angular coordinates originating from the center of rotation of the eye for the lens from which the calculations are carried out, and the scanning is carried out in an incremental manner from degree to degree starting from the position the lowest possible (80 °) in the sagittal plane.
• step 1 10 for this point in the environment, we calculate a convergence, in the absence of a lens: in fact, we know the distance from the point to the center of rotation of the eye, and the pupillary distance of the wearer.
• step 120 knowing this convergence and the Donders curve of the wearer, an accommodation is determined, and the power required on the lens is calculated.
• the Donders curve provides accommodation as a function of convergence; we calculate the power as a thin lens approximation, as explained above with reference to step
• Step 130 of FIG. 5 corresponds mutat is mutandis to step 30 of FIG. 2.
• the introduction of the lens having the power determined in step 120 causes prismatic deviations which require for compensation of the movements of the eyes and the head therefore a modification of the distance from the point looked at and of the convergence.
• the thin lens approximation calculations are carried out at every point of the vertex sphere.
• step 140 the new accommodation and the new power caused by these modifications are calculated.
• step 150 we go to the next point, in the environment, following the scanning strategy explained above, and we go back to step 1 10.
• a table of values for the right eye and a table of values for the left eye containing for each angular position of the eye in the orbit, therefore for each point of a glass, an associated power and object distance.
• This definition of ergorama also makes it possible to define a main meridian of progression on a glass, by a set of gaze directions.
• the main meridian of progression is advantageously defined from the ergorama and corresponds, for an ametropia and a given addition, to all the directions of the gaze corresponding to points of the environment located in the sagittal plane.
• FIG. 6 shows the typical appearance of an ergorama along the meridian, in diopters, as a function of the angle alpha between the direction of gaze and the horizontal plane passing through the point Q ', for an ametropia corresponding to a zero power in far vision, and an addition of 2.00 diopters.
• FIG. 6 shows only the variations of the ergorama as a function of the angle alpha. In fact, as a first approximation, we can reasonably consider that the ergorama is only a function of the angle alpha and that it does not varies little depending on the beta angle. Typically, the ergorama is zero at the far vision control point, and it has a value of the order of 2.5 to 3.5 diopters at the near vision control point.
• the invention proposes to consider, for the optimization of the aspherical face of a lens, not the values of mean sphere and of the cylinder, but the values of optical power and astigmatism aberration.
• the taking into account of these optical and no longer surface values allows a better definition of the aspherical face of the lenses and a better preservation of the optical properties of the lenses, with constant addition, for different powers.
• Figure 7 shows an example of the basic cut which does not matter! be used for the production of lenses according to the invention. Ligure 7 represents on the ordinate the values of the bases, and on the abscissa, the values of the optical powers corresponding to the reference point.
• the invention proposes to define the lenses using a program for optimizing the optical parameters of the lenses, with the following characteristics.
• a merit function to be used for optimization, by choosing a target and weights for the different areas of the target.
• the goal of the optimization program starting from a lens to be optimized, is to get as close as possible to the target lens.
• a merit function representative of the differences between the lens to be optimized and the target lens. defined as follows. For a set of points of the lens, or of the sphere of the vertices, or again of gaze directions, indexed by a variable i, we consider the function of merit written in the form: where pj is a weighting of point i;
• VJ is the value of the j-th type of parameter at point i
• C is the target value of the j-th type of parameter at point i
• WJ is the weighting of the j-th type of parameter at point i.
• the weighting p points i makes it possible to assign a more or less significant weight to the various regions of the lens. It is preferable to provide a significant weighting on the meridian, and to decrease the weighting with the distance compared to the meridian.
• V- is measured for point i by a ray tracing program, using the definitions of carrier power and astigmatism aberration given above, from the proximity value provided by the ergorama.
• V: ⁇ is the carrier power value measured at point i
• Vp is the astigmatism aberration value measured at point i. More specifically, we can proceed as follows. In the alpha beta direction of point i. the ray from the center of rotation of the eye, which crosses the rear face of the lens, the lens, then the front face and opens into object space is constructed by a ray tracing program. We then consider the object point located on the ray thus drawn at a distance from the front face of the brightened glass, unlike the proximity object given by the ergorama for the alpha beta direction.
• the values C- are the target values: in the example, C: ⁇ is the carrying power value and Cp is the astigmatism aberration value, at point i.
• WJ is the weighting of the j-th type of parameter at point i. We can thus privilege, for a given point, the carrying power or the astigmatism.
• a method of amortized least squares or any other optimization method known per se.
• the lens of the invention has a flatter front surface than a lens of the prior art.
• this starting lens it is advantageous to start from this starting lens, add a layer to be optimized to the aspherical surface, and only modify this layer in the optimization process.
• a layer to be optimized to the aspherical surface For example, one can use a tablecloth by a Zernike polynomial; this makes it easier to calculate ray tracings, the Zernike polynomial being transcribed in terms of altitudes at the end of the optimization process, so as to obtain a map of the altitudes of the points of the aspherical face.
• Using a method of amortized least squares the merit function defined above, and such a starting lens, it suffices to carry out a dozen iterations, to arrive in most cases at a lens having good performance.
• the invention makes it possible to obtain almost identical results regardless of the optical power of the carrier, for a given addition.
• the following figures show examples of lenses according to the invention and of known lenses.
• the following definitions of the far vision zone, the intermediate vision zone and the near vision zone are used below: these zones defined as the set of gaze directions or corresponding points of the lens in which the astigmatism aberration is less than 0.5 diopters.
• the lines consisting of points for which the astigmatism aberration has a value are called iso-astigmatism lines.
• the viewing area in the far vision area is then the area that the eye scans in the far vision area, ie between the lines of iso-astigmatism at 0.5 diopters, the edge of the lens and above the geometric center of the lens.
• the width of field in near vision is then the angular width at the height of the measurement point of near vision, between the lines of iso-astigmatism 0.5 diopters.
• Figure 8 shows the variation of the optical power along the meridian, for the different additions, from 0.75 to 3.5 diopters.
• the elevation of the gaze or angle alpha, in degrees, is plotted on the abscissa in FIG.
• the variation in optical power with respect to the optical power is represented at the reference point: this variation is zero at the reference point, located on the front face of the lens 8 mm above the geometric center, i.e. at a neighbor alpha angle of 8 °.
• FIG. 8 shows the different optical optimization powers, which are those defined above (-4.5, - 1.5. 1 .3 and 4.75 diopters).
• the optical power along the meridian is almost identical whatever the power at the reference point in VI J. in other words, the invention makes it possible to ensure "optical mono-design", ie optical performance for the wearer in the intermediate space, ie in the eye glass space, which .are independent of the power in VL. It is easy to deduce from FIG. 8 the target values of the optical power along the meridian, which are almost reached.
• FIG. 9 shows by comparison the corresponding graphic representations, for a lens of the prior art. It is seen in Figure 9 a larger dispersion values of the optical power for a given addition in the unction different powers in VL. This clearly shows how the invention makes it possible to improve the performance of known lenses.
• FIG. 10 shows a representation analogous to that of FIG. 8. in which, however, graphic representations of the carrier optical powers have been added for lenses corresponding to the extreme optical powers for each base, for example -2.25 and 0 diopters for the base 3.5 diopters. It can be seen in FIG. 10 that the variations in optical power along the meridian still correspond substantially to the target values of FIG. 8. In other words, the invention still provides comparable optical performance, even when the rear faces which have served for optimization are replaced by different rear faces.
• Figure 1 1 shows for comparison the corresponding graphic representations, for a lens of the prior art. We see in Figure 1 1 a much greater dispersion of the values of the optical power, for a given addition, according to the different powers in VL.
• FIG. 12 shows the results obtained according to the invention, in terms of variation compared to the ergorama.
• the different curves in Figure 12 show the variation of optical power along the meridian, when we deviate from the ergorama by a value between +2.00 diopters, and -2.00 diopters, with steps of 0.25 diopters.
• the lowest curve in the figure corresponds to a deviation of +2.00 diopters, and the highest curve corresponds to a deviation of -2.00 diopters.
• On the ordinate are the variations relative to the target optical power, and on the abscissa the elevation of the gaze (angle alpha), the curves of FIG. 12 correspond to a lens according to the invention, of an addition +3.50, and with an optical power of 5 diopters at the reference point (base 6.2 diopters).
• Figure 13 shows corresponding results for the aberration of astigmatism.
• the variations in the astigmatism aberration remain small, even when one departs from the ergorama used in the invention.
• the astigmatism aberration variations remain below 0. 125 diopters for deviations from the ergorama up to 0 and 0.50 diopters.
• deviations from the ergorama can reach 1 diopter without the astigmatism aberration varying by more than 0.125 diopter.
• the field width does not vary by more than 15% around the nominal value when the difference in the ergorama is less than one diopter.
• the viewing area (area inside the iso-astigmatism at 0.5 diopters) does not vary more than 15% when the deviation from the ergorama is less than 1 diopter.
• Figures 14 to 22 show the results obtained thanks to the invention, in comparison with the results of lenses according to the prior art.
• FIGS. 14 to 22 show, for a lens of the prior art and for lenses according to the invention, lines of level of the optical power (or of the aberration of astigmatism), ie lines formed of points having an identical optical power (or an aberration of identical astigmatism).
• the lines are shown for values of optical power (or astigmatism aberration) ranging from 0.25 to 0.25 diopters; only the integer or half-integer values of the optical power (or the aberration of astigmatism) are shown in the figures, and the intermediate values (0.25. 0.75. 1.25 etc.) are not shown in the figures.
• the lenses are represented in a coordinate system in spherical coordinates, the beta angle being plotted on the abscissa and the angle alpha on the ordinate.
• Figures 14 to 16 show a lens of the prior art, of diameter 70 mm; the front face of this lens is a progressive multifocal surface, base 2 diopters, of addition 2.
• the rear face is chosen so as to present an optical power in far vision of - 4.5 diopters, and has a prism of 1.36 ° .
• the plane of the glass is inclined relative to the vertical by 12 °, and has a thickness in the center of 1 .2 mm.
• the value of q ′ of 27 mm mentioned with reference to FIG. 1 has been considered.
• Figure 14 shows the level lines of optical power
• Figure 15 shows the level lines of astigmatism aberration.
• Figure 16 shows the optical power, and the minimum and maximum optical powers along the optical meridian.
• the optical power is -4.5 diopters.
• the astigmatism aberration is 0.26 diopters.
• the optical power is -2.10 diopters.
• the astigmatism aberration is 0.19 diopters.
• the actual optical addition is therefore 2.4 diopters.
• Figures 17 to 19 show corresponding figures for a first lens according to the invention, of diameter 70 mm; the front face of this lens is a progressive multifocal surface, basic 2.0 diopters, of addition 2.0.
• the rear face is chosen so as to present an optical power in far vision of -4.5 diopters, and has a prism of 1.36 °.
• the plane of the glass is inclined relative to the vertical by 12 °, and has a thickness in the center of 1.2 mm.
• the value of q ′ of 27 mm mentioned with reference to FIG. 1 has been considered.
• Figure 17 shows the level lines of the optical power
• Figure 18 shows the level lines of the astigmatism aberration
• Figure 19 shows the optical power, and the minimum and maximum optical powers along the optical meridian.
• the optical power is -4.50 diopters.
• the astigmatism aberration is 0.02 diopters.
• the optical power is -2.50 diopters.
• the astigmatism aberration is 0.01 diopters.
• the actual optical addition is therefore 2.00 diopters.
• Figures 20 to 22 show corresponding figures for a second lens according to the invention, identical to the first, with however a base of 5.3 diopters, an addition of 2 diopters, and an optical power of 3 diopters, and a thickness in the center of
• Figure 20 shows the optical power level lines
• Figure 21 shows the level lines of astigmatism aberration.
• Figure 22 shows the optical power, and the minimum and maximum optical powers along the optical meridian.
• the optical power is 3 diopters.
• the astigmatism aberration is 0.02 diopters.
• the optical power is 5.06 diopters.
• the astigmatism aberration is 0.01 diopters.
• the real optical addition is therefore 2.06 diopters.
• the comparison of these ligures makes it possible to clearly highlight the advantages of the invention.
• the invention makes it possible, compared with the prior art, to take good account of s.- different rear faces, and to obtain satisfactory results for the wearer, not in terms of mean sphere and cylinder. , but of optical power and astigmatism aberration.
• there is a sharp decrease in the astigmatism aberration along the meridian the optical power, minimum optical power and maximum optical power curves being almost identical in the lenses of the invention.
• the astigmatism aberration remains less than 0.2 diopters along the meridian.
• FIGS. 18 and 21 have similar gaits, and provide zones of far vision of near vision that are substantially identical, and more extensive than in the lens of figure 15.
• the width of field in near vision, in the two lenses of the invention, is respectively 24 ° and 26 °. In the lens of the prior art, it is only 18 °.
• the field width is greater in the two lenses of FIGS. 1 7 to 22 as in the other lenses of the invention at 21 / A + 10 degrees, A being the addition.
• the invention proposes a set of lenses in which the optical performances of the different lenses are substantially identical for the same addition. regardless of the optical power at the measurement point of the far vision area, this corresponds to a "single optical design". More precisely, according to the invention, the far vision viewing area, defined above, varies by less than 15% for the same addition, whatever the optical power at the point of measurement of the far vision area. .
• the width of field in near vision which is also defined above, varies by less than 1% for the same addition, whatever the optical power at the point of measurement of the far vision zone.
• front face and rear face i.e. to provide that the multifocal aspherical surface of the lens is turned towards the wearer, without this modifying the invention.

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• 1996
  • 1996-09-20 FR FR9611478A patent/FR2753805B1/fr not_active Expired - Lifetime
• 1997
  • 1997-09-09 US US09/254,698 patent/US6318859B1/en not_active Expired - Lifetime
  • 1997-09-09 BR BR9711399A patent/BR9711399A/pt not_active Application Discontinuation
  • 1997-09-09 CA CA002265705A patent/CA2265705C/en not_active Expired - Lifetime
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  • 1997-09-09 JP JP10514335A patent/JP2001503155A/ja active Pending
  • 1997-09-09 DE DE69714273.6T patent/DE69714273T3/de not_active Expired - Lifetime
  • 1997-09-09 ES ES97940198T patent/ES2181024T5/es not_active Expired - Lifetime
  • 1997-09-09 EP EP97940198.1A patent/EP0927377B2/fr not_active Expired - Lifetime
  • 1997-09-09 WO PCT/FR1997/001583 patent/WO1998012590A1/fr not_active Ceased
• 2009
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