Method of calculating an optical system of a progressive addition ophthalmic lens being arranged to output a supplementary image

Abstract

A progressive ophthalmic spectacle lens (10) capable of correcting a wearer's ophthalmic vision and having a back surface (BS) and a front surface (FS), said lens comprising a light guide optical element arranged to output a supplementary image (SI) to the wearer through an exit surface (ES) of said light guide optical element, where the exit surface (ES), the back surface (BS) and an optical material located between said exit surface (ES) and said back surface (BS) form an optical device (OD) and wherein said optical device (OD) comprises an area of stabilized optical power.

Claims

1. A method of calculating and manufacturing an optical system of a progressive addition ophthalmic lens having a power variation observed thereon of at least 0.5 Diopter, the progressive addition ophthalmic lens being capable of correcting wearer's vision and having a back surface and a front surface, arranged to deliver a corrected ophthalmic vision image to the wearer through the back surface, where the back surface is positioned closest to a wearer's eye when the progressive addition ophthalmic lens is worn, the progressive addition ophthalmic lens comprising an embedded light guide optical element having an exit surface and an opposite surface and being arranged to output a supplementary image to the wearer through the exit surface of said light guide optical element, the method comprising: a calculation step including calculating the optical system by optimizing the back surface of the optical system to provide an accommodation effort that is less than or equal to the wearer's residual accommodative effort when viewing from the corrected ophthalmic vision image to the supplementary image and vice versa; and a manufacturing step including machining a lens blank according to the optical system calculated in the calculation step, wherein the progressive addition ophthalmic lens is chosen from within a list consisting of: a lens having a far vision zone, an intermediate vision zone and a near vision zone, a lens having an intermediate vision zone and a near vision zone, a lens having a far vision zone and an intermediate vision zone.

2. The method of calculating and manufacturing an optical system as claimed in claim 1, wherein the progressive addition ophthalmic lens has a power variation observed thereon of at least 0.75 Diopter.

3. A non-transitory computer readable medium comprising one or more stored sequence of instruction that is accessible to a processor and which, when executed by the processor, causes the processor to carry out at least the steps of claim 1.

4. The method of calculating and manufacturing an optical system as claimed in claim 1, wherein the exit surface is defined by an angular aperture contour, denoted AC(,), being the eye declination angle and being the eye azimuth angle, further comprising the successive steps of: providing prescription data of the wearer; providing an optical target that has a virtual optical function according to the wearer's prescription data where the optical power of said optical target is denoted P.sub.OT(,); and calculating the average sphere value D.sub.FS(,), of the front surface, so that it fulfils the requirement of following equation (E1), when (,) is within the contour AC (,): $\begin{array}{cc}{P}_{\mathrm{OT}}\left(,\right)-\frac{1}{-\frac{1}{P_{\mathrm{rem}}}}{D}_{\mathrm{FS}}\left(,\right)P_{\mathrm{OT}}\left(,\right)-\frac{1}{\mathrm{ELD}-\frac{1}{P_{\mathrm{prox}}}}& \left(\mathrm{E1}\right)\end{array}$ wherein: P.sub.prox is the proximity of the Punctum proximum value expressed in diopter; P.sub.rem is the proximity of the Punctum remotum value expressed in diopter; ELD is chosen within the list consisting of the measured wearer's eye-lens distance expressed in meter; the standard wearer's eye-lens distance expressed in meter; ELD=0.

5. The method of calculating and manufacturing an optical system as claimed in claim 4, wherein the proximity of the Punctum proximum value, P.sub.prox, and the proximity of the Punctum remotum value, P.sub.rem, are chosen within a list consisting of: constant data of a model eye; data of a model eye varying as a function of the age of the wearer; data of a model eye varying as a function of the prescription of the wearer; data of a model eye varying as a function of the age and the prescription of the wearer; measured data done with the actual wearer's eye.

6. The method of calculating and manufacturing an optical system as claimed in claim 5, wherein the method comprises further steps of: providing a set of data and/or equations defining the exit surface (ES(R,,)) and the opposite surface (OPS(R,,)) of the light guide optical element according to (R,,) coordinates, where R is the distance of a point when considering the Center of Rotation of the Eye as the originate; providing the refractive indexes between the different surfaces within the list consisting of the back surface, the front surface of the progressive addition ophthalmic lens, the exit surface, the opposite surface of the light guide optical element; and optimizing simultaneously the average sphere value D.sub.BS(,) over the back surface and the front surface according to the optical target, to the requirements of equation E1 and to wearer's prescription data as targets.

7. The method of calculating and manufacturing an optical system as claimed in claim 5, wherein P.sub.prox is replaced by P.sub.conf in equation E1 where P.sub.conf is the Punctum comfort value expressed in diopter, corresponding to a reduced accommodation effort for the wearer which is compatible with extended use of the system.

8. The method of calculating and manufacturing an optical system as claimed in claim 4, wherein P.sub.prox is replaced by P.sub.conf in equation E1 where P.sub.conf is the Punctum comfort value expressed in diopter, corresponding to a reduced accommodation effort for the wearer which is compatible with extended use of the system.

9. The method of calculating and manufacturing an optical system as claimed in claim 8, wherein the method comprises further steps of: providing a set of data and/or equations defining the exit surface (ES(R,,)) and the opposite surface (OPS(R,,)) of the light guide optical element according to (R,,) coordinates, where R is the distance of a point when considering the Center of Rotation of the Eye as the originate; providing the refractive indexes between the different surfaces within the list consisting of the back surface, the front surface of the progressive addition ophthalmic lens, the exit surface, the opposite surface of the light guide optical element; and optimizing simultaneously the average sphere value D.sub.BS(,) over the back surface and the front surface according to the optical target, to the requirements of equation E1 and to wearer's prescription data as targets.

10. The method of calculating and manufacturing an optical system as claimed in claim 4, wherein the method comprises a further step, when D.sub.FS(,) values obtained within the contour AC(,) corresponds to a sphero-toric surface, of using this sphero-toric surface over the front surface when (,) is out of the contour AC(,), then optimizing the back surface according to a chosen design data as a target.

11. The method of calculating and manufacturing an optical system as claimed in claim 10, wherein the method further comprises: providing a set of data and/or equations defining the exit surface (ES(R,,)) and the opposite surface (OPS(R,,)) of the light guide optical element according to (R,,) coordinates, where R is the distance of a point when considering the Eye Center of Reference as the originate; providing the refractive indexes between the different surfaces within the list consisting of the back surface, the front surface of the progressive addition ophthalmic lens, the exit surface, the opposite surface of the light guide optical element; providing a desired direction for the supplementary image delivered by the light-guide optical element; and optimizing the back surface according to the requirements of the wearer's prescription data and the desired direction for the supplementary image as targets.

12. The method of calculating and manufacturing an optical system as claimed in claim 4, wherein the method comprises a further step of selecting a front surface within a plurality of front surface base-curves where the chosen front surface base-curve is the one which approaches the requirements of equation (E1), when (,) is within the contour AC(,).

13. The method of calculating and manufacturing an optical system as claimed in claim 12, wherein the method comprises further steps of: providing a set of data and/or equations defining the exit surface (ES(R,,)) and the opposite surface (OPS(R,,)) of the light guide optical element according to (R,,) coordinates, where R is the distance of a point when considering the Eye Center of Reference as the originate; providing the refractive indexes between the different surfaces within the list consisting of the back surface, the front surface of the progressive addition ophthalmic lens, the exit surface, the opposite surface of the light guide optical element; providing a desired direction for the supplementary image delivered by the light-guide optical element; and optimizing the back surface according to the requirements of the wearer's prescription data and the desired direction for the supplementary image as targets.

14. The method of calculating and manufacturing an optical system as claimed in claim 4, wherein the method further comprises: providing a set of data and/or equations defining the exit surface (ES(R,,)) and the opposite surface (OPS(R,,)) of the light guide optical element according to (R,,) coordinates, where R is the distance of a point when considering the Center of Rotation of the Eye as the originate; providing the refractive indexes between the different surfaces within the list consisting of the back surface, the front surface of the progressive addition ophthalmic lens, the exit surface, the opposite surface of the light guide optical element; and optimizing simultaneously the average sphere value D.sub.BS(,) over the back surface and the front surface according to the optical target, to the requirements of equation E1 and to wearer's prescription data as targets.

15. A progressive addition ophthalmic lens having a power variation observed thereon of at least 0.5 Diopter, the progressive addition ophthalmic lens being capable of correcting wearer's vision and having a back surface and a front surface, arranged to deliver a corrected ophthalmic vision image to the wearer through the back A surface, where said back surface is positioned closest to a wearer's eye when the progressive addition ophthalmic lens is worn, the progressive addition ophthalmic lens comprising a light guide optical element arranged to output a supplementary image to the wearer through an exit surface of said light guide optical element, wherein the progressive addition ophthalmic lens is arranged so as to enable the wearer of said lens to provide an accommodation effort that is less than or equal to the wearer's residual accommodative effort when viewing from the corrected ophthalmic vision image to the supplementary image and vice versa, wherein the progressive addition ophthalmic lens is chosen from within a list consisting of: a lens comprising a far vision zone, an intermediate vision zone and a near vision zone, a lens comprising an intermediate vision zone and a near vision zone, a lens comprising a far vision zone, and an intermediate vision zone.

16. The progressive addition ophthalmic lens as claimed in claim 15, wherein: the supplementary image is output in at least a zone of the intermediate vision zone and/or of the near vision zone; and the mean sphere of the front surface is at least 2 Diopter.

17. The progressive addition ophthalmic lens as claimed in claim 15, wherein: the progressive addition ophthalmic lens is chosen within the list consisting of a lens comprising a far vision zone, an intermediate vision zone and a near vision zone; and a lens comprising a far vision zone and an intermediate vision zone; the supplementary image is output in at least a zone of the far vision zone; and the mean sphere of the front surface is equal to or less than 2 Diopter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Examples will now be described with reference to the accompanying drawings wherein:

(2) FIGS. 1a and 1b are sketches of an eye of a wearer and of an ophthalmic spectacle lens capable of correcting the wearer's ophthalmic vision and comprising a light guide optical element arranged to output a supplementary image.

(3) Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help improve the understanding of the embodiments of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) FIGS. 1a and 1b are sketches that illustrate the principle of a spectacle lens 10 which provides both an ophthalmic vision OV and a supplementary vision by outputting a supplementary image SI to an eye 100 of a wearer. The spectacle lens is capable of correcting a wearer's ophthalmic vision; it has a back surface BS and a front surface FS where the back surface is positioned closest to the wearer's eye when the spectacle lens is worn; said spectacle lens also comprises a light guide optical element 2 arranged to output a supplementary image SI to the wearer through an exit surface ES of said light guide optical element.

(5) The lens 10 consists of at least two transparent and refringent materials, which may be any organic or mineral material used in the ophthalmic field. The light guide optical element 2 is inserted between the back surface BS and the front surface FS. The light guide optical element 2 has two opposite faces named proximal surface PS and distal surface DS where the proximal surface is closer to the eye of the wearer than the distal surface when the spectacle lens is worn. Accordingly the proximal surface PS is the surface of the light guide optical element which is the closest from the back surface BS and the distal surface DS the surface of the light guide optical element which is the closest from the front surface FS.

(6) According to the embodiment of FIGS. 1a & 1b, the proximal surface PS and the distal surface DS are parallel surfaces;

(7) According to another embodiment, the proximal surface PS and the distal surface DS are non-parallel surfaces;

(8) According to the embodiment of FIGS. 1a & 1b, the proximal surface PS and/or the distal surface DS is a (are) plane surface(s);

(9) According to another embodiment, the proximal surface PS and/or the distal surface DS is a (are) curved surface(s); such a curved surface is for example a spherical surface, a toric surface, a sphero-toric surface; such a curved surface can also be an aspherized spherical or toric or sphero-toric surface.

(10) A first transparent and refringent material is situated around the light guide optical element 2; the light guide optical element 2 is made of a second transparent and refringent material; the refractive indexes of said two materials may be identical, slightly different or significantly different.

(11) According to the present embodiment, the lens 10 has a convex front surface FS and a concave back surface BS. The surfaces FS and BS have respective curvatures which together determine, with the value(s) of light refractive index(es) of the material(s) between said two surfaces, an optical power of the spectacle lens, for the ophthalmic vision OV.

(12) In the frame of the present invention, this optical power varies between the directions of sight so as to provide a multifocal vision.

(13) The light guide optical element 2 is appropriate for bringing supplementary light from a source 3 which is not represented in detail so as to produce a supplementary image SI. The structure of the light guide optical element 2 is not the subject of this description, and reference can be made to other documents available on this subject. One example of a suitable light optical element is described in patent document WO2005024491 or in patent document WO200195027 in the name of the LUMUS Company. Generally, this invention can apply to any light optical element embedded in the lens providing supplementary image, for which the supplementary image may be distorted or modified by the optical properties of the back surface BS of the lens.

(14) The lens 10 has a front portion 13 which is between the light guide optical element 2 and the front surface FS, and a rear portion 12 which is between the light guide optical element 2 and the back surface BS.

(15) The light guide optical element 2 is limited transversely within an area of the lens 10 in certain directions approximately parallel to the faces FS and BS. In such a configuration, the front portion 13 and the rear portion 12 of the lens 10 extend beyond a peripheral edge 2e of the light guide optical element 2. The lens 10 then has an intermediate portion 11 which extends beyond the edge 2e of the light guide optical element 2 and which continually links the portions 13 and 12 to a peripheral edge E of the lens 10.

(16) The light guide optical element 2 is virtually divided in two zones 2a and 2b separated by a virtual edge 2e. Zone 2a is the imaging part wherefrom does the supplementary image come from according to the eye of the wearer; zone 2b is a propagation part wherein the supplementary image is propagated from the source 3 without supplying an image to the wearer.

(17) The edge of zone 2a is the contour of the supplementary image output by the light guide optical element; said supplementary image intercepts the proximal surface PS according to an exit surface ES. One names opposite surface OS the surface corresponding to the exit surface ES on the distal surface. According to the present example the imaging part is substantially a rectangle whose width is W and whose height is H.

(18) According to a commonly used optical referential, the exit surface ES is defined by an angular aperture contour, denoted AC(,), a being the eye declination angle and being the eye azimuth angle. , pole is the center of rotation, CRE, of the eye 100 of the wearer behind the lens. 101 corresponds to the axis where ==0.

(19) According to an example, the aperture AC may be +/15 (degree) either side of an optical axis of the supplementary vision, which passes through the center of the exit surface ES. Said aperture is defined in the azimuthal plane by |.sub.1|+|.sub.2|. It is defined in the perpendicular plane by |.sub.1|+|.sub.2|. The generatrix lines of the limit of the angular aperture contour intersect the back surface BS of the lens in an area in which the two visions, ophthalmic and supplementary, are superposed. In the configuration of FIGS. 1a and 1b, the respective optical axes of the ophthalmic vision and of the supplementary vision are one and the same, but they may be distinct.

(20) FIGS. 1a and 1 b represent the spectacle lens in the position of use by the wearer. The eye of the wearer 100 is therefore situated behind the lens 10 on the side of the back surface so that it receives, on the one hand, light OV originating from the environment which is situated in front of the lens, and, on the other hand, the light corresponding to the supplementary image SI which is brought by the light guide optical element 2. The light beams of the two lights OV and SI correspond respectively to the ophthalmic vision and to a supplementary vision. They respectively form, after having passed through the pupil 120, an ophthalmic image and a supplementary image on the retina 110 of the wearer. The reference 130 designates the iris of the wearer which surrounds his pupil 120. The direction in which the wearer is looking corresponds to the optical axis of the eye 100. It intersects the surfaces FS and BS of the spectacle lens at respective points which vary when the eye 100 turns in the orbit of the wearer.

(21) Given that the light OV passes through the two surfaces FS and BS of the lens, they both contribute to optical characteristics of the lens which are relative to the ophthalmic vision. However, the light SI does not pass through the surface FS, so that this surface does not contribute to optical characteristics of the lens which are relative to the supplementary vision. Because of this difference between the lights OV and SI, they do not present convergence characteristics which are identical after they have passed through the back surface BS of the lens. For this reason, the ophthalmic and additional images which are formed on the retina may not be simultaneously clear.

(22) The expression optical characteristics of lens which are relative to one or other of the ophthalmic and supplementary visions should be understood notably to mean an optical power value, astigmatism values, optical distortion values, etc., of the lens for each direction in which the wearer looks.

(23) Following examples are given to illustrate embodiments where an ophthalmic spectacle lens capable of correcting the wearer's ophthalmic vision and comprising a light guide optical element arranged to output a supplementary image according to FIGS. 1a and 1b is designed to fulfill the requirements of the present invention.

(24) According to said embodiments the proximal surface PS and the distal surface DS are parallel and plane surfaces. According to other possible embodiments, the proximal surface PS and the distal surface DS are non-parallel and/or curved surfaces.

(25) According to an example, the residual accommodation effort of a wearer is determined by an ophthalmologist or an eye care practitioner (ECP); according to said embodiment, the ophthalmologist or eye care practitioner (ECP) simultaneously measures the proximity of the Punctum proximum value, the proximity of the Punctum remotum value expressed in diopter and the Punctum comfort value.

(26) Thanks to those measurements, one can determinate the data that can be used to fulfill the requirements of Equation (E1) for a given wearer, and thus determine the range of average sphere value D.sub.FS(,) of the front surface (FS), when (,) is within the contour AC(,), that provides an accommodation effort that is less than or equal to the wearer's residual accommodative effort when viewing from the corrected ophthalmic vision image (CVI) to the supplementary image (SI) and vice versa.

(27) According to another example, the residual accommodation effort of a wearer is determined according to data that are determined for a standard wearer as a function of the age (in years) of the standard wearer and as a function of prescription of said wearer.

(28) Tables 1 and 2 show examples P.sub.rem, P.sub.prox, P.sub.conf (expressed in diopter), where table 1 corresponds to an emmetropic wearer (no correction is needed) and table 2 to a myopic wearer needing a 2 diopters correction;

(29) TABLE-US-00001 TABLE 1 Age 40 45 50 55 60 P.sub.rem 0 0 0 0 0 P.sub.conf 3 2 0.5 0.3 0.25 P.sub.prox 5 3 1.5 1.2 1

(30) TABLE-US-00002 TABLE 2 Age 40 45 50 55 60 P.sub.rem 2 2 2 2 2 P.sub.conf 5 4 2.5 2.3 2.25 P.sub.prox 7 5 3.5 3.2 3

(31) Thanks to those tables, one can determinate the data that can be used to fulfill the requirements of Equation (E1) for a given wearer, and thus determine the range of average sphere value D.sub.FS(,) of the front surface (FS), when (,) is within the contour AC(,), that provides an accommodation effort that is less than or equal to the wearer's residual accommodative effort when viewing from the corrected ophthalmic vision image (CVI) to the supplementary image (SI) and vice versa.

(32) Based on the range of average sphere value D.sub.FS(,) when (,) is within the contour AC(,), one can provide the front surface (FS) of the lens.

(33) For example, one can select a semi-finished lens among a set of semi-finished lens having front surface (FS) geometry complying with the range of average sphere value D.sub.FS(,).

(34) As an alternative, it is also possible to calculate a new front surface (FS) complying the range of average sphere value D.sub.FS(,).

(35) The semi-finished or new calculated front surface (FS) can be a progressive surface, a regressive surface, a spherical surface, and the curvature may be no constant on the surface.

(36) Among all front surface (FS) complying with the range of average sphere value D.sub.FS(,), one can select a front surface (FS) having the preferred geometry, for example the geometry that best fits with the geometry of the frame.

(37) Once the front surface (FS) is selected or calculated, it is then possible to build the whole back surface taking into account the prescription data of the wearer.

(38) One can for example make an optimization of said back surface according to a desired design optical data.

(39) One can also choose a preferred gaze direction to make an optimization of said back surface.

(40) Once the back surface is calculated, one can calculate the optical system (OS) of a progressive addition ophthalmic lens capable of correcting wearer's vision and having a back surface (BS) and a front surface (FS), arranged to deliver a corrected ophthalmic vision image (CVI) and to output a supplementary image (SI).

(41) The optical system (OS) of the calculated progressive addition ophthalmic lens (and a lens manufactured accordingly) provides an accommodation effort that is less than or equal to the wearer's residual accommodative effort when viewing from the corrected ophthalmic vision image (CVI) to the supplementary image (SI) and vice versa.

(42) The invention has been described above with the aid of embodiments without limitation of the general inventive concept; in particular the parameters are not limited to the examples discussed.