Method of calculating optical characteristics of an optical system according to a given spectacle frame

Abstract

A method of calculating an optical system (OS) of an ophthalmic lens according to a given spectacle frame, said ophthalmic lens comprising a back surface (BS) and a front surface (FS) arranged to deliver an ophthalmic vision image (VI), a light-guide optical element having a proximal surface (PS) and a distal surface (DS), said light-guide optical element being arranged to output a supplementary image (SI), wherein the method comprises the steps of: providing at least a morpho-geometrical parameter data of the frame or of the light-guide optical element; optimizing the optical system (OS) according to at least the morpho-geometrical parameter data as a target.

Claims

1. A method of calculating optical characteristics of an optical system of an ophthalmic lens according to a given spectacle frame, said ophthalmic lens comprising a back surface and a front surface arranged to deliver an ophthalmic vision image, where the back surface is positioned closest to a wearer's eye when the ophthalmic lens is worn, the ophthalmic lens comprising a light-guide optical element having a proximal surface and a distal surface, said light-guide optical element being arranged to output a supplementary image to the wearer through an exit surface located on the proximal surface, the method comprising: obtaining, by processing circuitry, at least morpho-geometrical parameter data of the frame or of the light-guide optical element; and optimizing, by the processing circuitry, the optical system according to at least the morpho-geometrical parameter data as a target, the morpho-geometrical parameter data of the spectacle frame or of the light-guide optical element being chosen from the list consisting of a pantoscopic angle of the frame, a face form angle of the frame, a base curve of the frame and a contour of the frame, or a pantoscopic angle of the light-guide optical element, the optical system being optimized with the proviso that a distance d1 between the distal surface and the front surface and a distance d2 between the proximal surface and the back surface are equal to or more than 0.2 mm.

2. The method of calculating optical characteristics of an optical system as claimed in claim 1, further comprising: obtaining a desired viewing direction for the supplementary image; wherein the optical system is optimized also according to the desired viewing direction as a target.

3. The method of calculating optical characteristics of an optical system as claimed in claim 1, wherein the optical system is optimized also according to a target centre thickness and a target edge thickness of the ophthalmic lens.

4. The method of calculating optical characteristics of an optical system as claimed in claim 1, further comprising: obtaining prescription data of the wearer; wherein the optical system is optimized also according to prescription data of the wearer as a target.

5. The method of calculating optical characteristics of an optical system as claimed in claim 1, further comprising: obtaining an initial position of the light-guide optical element; wherein the optical system is optimized also by shifting and/or by tilting the initial position of the light-guide optical element.

6. The method of calculating optical characteristics of an optical system as claimed in claim 1, wherein the exit surface is defined by an angular aperture contour, denoted AC(,), said method also comprising: obtaining a wearer's accommodative effort threshold; and optimizing the optical system within AC(,), so that the wearer's accommodative effort is equal or less to the wearer's accommodative effort threshold when viewing at the supplementary image.

7. The method of calculating optical characteristics of an optical system as claimed in claim 6, wherein the front surface and the back surface of the optical system are simultaneously optimized, when (,) is out of the contour AC(,), to fulfil the wearer's ophthalmic vision.

8. The method of calculating optical characteristics of an optical system as claimed in claim 1, further comprising: obtaining design optical data; wherein the front surface and/or the back surface of the optical system is (are) optimized also according to said design optical data as a target.

9. The method of calculating optical characteristics of an optical system as claimed in claim 8, wherein the optimization of respectively the front surface or the back surface includes adding prism on a model ophthalmic lens front or back surface corresponding to the design optical data of a model ophthalmic lens.

10. A method for manufacturing an addition ophthalmic lens by machining a lens blank according to the optical system of claim 1.

11. An ophthalmic lens manufactured by machining a lens blank according to an optical system, the ophthalmic lens comprising: a back surface and a front surface arranged to deliver an ophthalmic vision image, where the back surface is positioned closest to a wearer's eye when the ophthalmic lens is worn; and a light-guide optical element having a proximal surface and a distal surface, the light-guide optical element being arranged to output a supplementary image to the wearer through an exit surface located on the proximal surface, wherein a difference (1) between an average sphere according to a gaze direction passing through the exit surface and an average sphere at a point of a periphery of the lens is greater than 4 Diopter, (1>4D), either on the front surface or on the back surface, the optical system being optimized according to at least morpho-geometrical parameter data of a spectacle frame or of the light-guide optical element as a target, the morpho-geometrical parameter data of the spectacle frame or of the light-guide optical element being chosen from the list consisting of a pantoscopic angle of the frame, a face form angle of the frame, a base curve of the frame and a contour of the frame, or a pantoscopic angle of the light-guide optical element.

12. A non-transitory computer readable medium including computer executable instructions, wherein the instructions, when executed by a computer, cause the computer to perform a method of calculating optical characteristics of an optical system of an ophthalmic lens according to a given spectacle frame, said ophthalmic lens comprising a back surface and a front surface arranged to deliver an ophthalmic vision image, where the back surface is positioned closest to a wearer's eye when the ophthalmic lens is worn, the ophthalmic lens comprising a light-guide optical element having a proximal surface and a distal surface, said light-guide optical element being arranged to output a supplementary image to the wearer through an exit surface located on the proximal surface, the method comprising: obtaining at least morpho-geometrical parameter data of the frame or of the light-guide optical element; and optimizing the optical system according to at least the morpho-geometrical parameter data as a target, the morpho-geometrical parameter data of the spectacle frame or of the light-guide optical element being chosen from the list consisting of a pantoscopic angle of the frame, a face form angle of the frame, a base curve of the frame and a contour of the frame, or a pantoscopic angle of the light-guide optical element, the optical system being optimized with the proviso that a distance d1 between the distal surface and the front surface and a distance d2 between the proximal surface and the back surface are equal to or more than 0.2 mm.

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) FIG. 2 is a horizontal cross section of an optical system calculated according to the invention in which back and front surfaces of the ophthalmic lens have been optimized according to the base curve of the frame as a target.

(4) FIG. 3 is a horizontal cross section of an optical system calculated according to the invention in which back and front surfaces of the ophthalmic lens have been optimized according to the face form angle of the frame as a target.

(5) FIG. 4 is a horizontal cross section of an optical system calculated according to the invention in which back and front surfaces of the ophthalmic lens have been optimized according to the face form angle of the frame as a target after a tilt of the light guide optical element from its initial position.

(6) FIG. 5 is a vertical cross section of an optical system calculated according to the invention in which back and front surfaces of the ophthalmic lens have been optimized according to the pantoscopic angle of the frame as a target.

(7) FIG. 6 is a vertical cross section of an optical system calculated according to the invention in which back and front surfaces of the ophthalmic lens have been optimized according to the pantoscopic angle as a target after a tilt of the light guide optical element from its initial position.

(8) FIGS. 7a and 7b are sketches of an eye of a wearer and of a light guide optical element arranged to output a supplementary image, where said figures illustrate the definitions of the pantoscopic angle of a frame and of the pantoscopic angle of a light-guide optical element.

(9) 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.

(10) Horizontal cross section should be understood as a cross section according to a plane (named horizontal plane) passing through the primary gaze direction and the two Center of Rotation of the Eye (both left and right);

(11) Vertical cross section should be understood as a cross section according to a plane (named vertical plane) perpendicular to the horizontal plane and passing through the primary gaze direction.

DETAILED DESCRIPTION OF THE DRAWINGS

(12) 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.

(13) 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.

(14) According to an embodiment the proximal surface PS and the distal surface DS are parallel surfaces;

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

(16) According to an embodiment the proximal surface PS and/or the distal surface DS is a (are) plane surface(s);

(17) According to an 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.

(18) 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.

(19) 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.

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

(21) 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 FS of the lens.

(22) 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.

(23) 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.

(24) 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.

(25) 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 OPS the surface corresponding to the exit surface ES on the distal surface. According to the present example the imaging part is substantially a rectangle which width is W and which high is H.

(26) According to a commonly used optical referential, the exit surface ES is defined by an angular aperture contour, denoted AC(,), 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.

(27) 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.

(28) FIGS. 1a and 1b 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.

(29) 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.

(30) 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.

(31) Following examples (examples 1 to 5) are given to illustrate embodiments of the method of the present invention.

EXAMPLE 1

Optimization of the Front Surface and the Back Surface According to a Base Curve of the Frame as a Target

(32) FIG. 2 represents an optical system of an ophthalmic lens 10 according to the prior art and a given spectacle frame 4 having a predetermined base curve of the frame.

(33) Said ophthalmic lens 10 comprises a back surface (BS) and a front surface (FS) arranged to deliver an ophthalmic vision (OV).

(34) Said ophthalmic lens 10 also comprises a light-guide optical element 2 arranged to input a supplementary image (SI) through an entry surface 5 and output said supplementary image (SI) through an exit surface 6 which is defined by an angular aperture contour, denoted AC(,) delimited by two directions 102 and 103.

(35) Such an ophthalmic lens 10 cannot be integrally contained within said frame 4.

(36) Thus, in this example, an optical system is calculated according to the predetermined base curve of the frame so as to provide an ophthalmic lens completely contained within the frame of the lens.

(37) In this example, the following parameters data have been provided: base curve value of the frame: 4 D desired viewing direction for the supplementary image 121 tilted of 0 with the horizontal plane and of 10 with the vertical plane; dimensions of the light guide optical element 3: 40 mm large, 25 mm height, 3 mm thick; position of said light guide optical element within the ophthalmic lens: the vector between the PRP (prism reference point) and the top left hand corner of the light-guide optical element defines the position of said guide within the lens. According to said example, said vector coordinates are x=27 mm; y=+12.5 mm; z=3.7 mm wearer's accommodative effort threshold (AET)=1.5 D.

(38) Firstly, the front FSa and back BSa surfaces of the ophthalmic lens 10a of the optical system (OS) have been optimized within AC(,), so that the wearer's accommodative effort is equal or less to the wearer's accommodative effort threshold (AET) when viewing at the supplementary image (SI).

(39) The optimization also takes account of the desired viewing direction for the supplementary image. In this example, the targeted prismatic deviation coming from the back surface is close to zero in the desired viewing direction. So, the viewing direction of the optical system is very close to the viewing direction of the optical light guide.

(40) Secondly, the front surface FSa and the back surface BSa of the optical system (OS) have been optimized when (,) is out of the contour AC(,) to generate different curvatures according to the base curve value as a target.

(41) According to an embodiment, optimization steps comprise: providing a lens design optimizing the front surface in order to match the base curve of the frame; optimizing the back surface in order to match the design (as described in patent WO 2007/017766 mentioned above).

(42) During the optimization process, the light optical element geometry (thickness, size) may be taken account so that to ensure that it is embedded between the front surface and the back surface of the lens. If the light optical element is smaller than the frame, this condition does not need to be respected for part of the lens that does not embed the optical element, thus allowing a larger range of curvature modification at the edge of the lens.

(43) Thus, the method according to the invention enables to provide an ophthalmic lens providing simultaneously both a suitable ophthalmic vision and a suitable supplementary vision to a wearer according to a base curve value of the frame as a target.

EXAMPLE 2

Optimization of the Front Surface and the Back Surface According to a Face Form Angle of the Frame as a Target

(44) FIG. 3 represents an optical system of an ophthalmic lens 10 of the prior art and a given spectacle frame 14 having a predetermined face form angle of the frame.

(45) Said ophthalmic lens 10 comprises a back surface (BS) and a front surface (FS) arranged to deliver an ophthalmic vision.

(46) Said ophthalmic lens 10 also comprises a light-guide optical element 22 arranged to input a supplementary image (SI) through an entry surface 15 and output a supplementary image (SI) through an exit surface 16 which is defined by an angular aperture contour, denoted AC(,).

(47) Such an ophthalmic lens 10 cannot be integrally contained within said frame 14.

(48) Thus, in this example, an optical system is calculated according to the predetermined face form angle of the frame so as to provide an ophthalmic lens completely contained within the frame of the lens.

(49) In this example, the following parameters data have been provided: face form angle of the frame=15; desired viewing direction for the supplementary image 131 tilted of 0 with the horizontal plane and of 10 with the vertical plane; dimensions of the light guide optical element 3 and position of said light guide optical element as defined in example 1; wearer's accommodative effort threshold (AET)=1.5 D

(50) Firstly, the front FSb and back BSb surfaces of the ophthalmic lens 10b of the optical system (OS) have been optimized within AC(,), so that the wearer's accommodative effort is equal or less to the wearer's accommodative effort threshold (AET) when viewing at the supplementary image (SI).

(51) The optimization also takes account of the desired viewing direction for the supplementary image. In this example, the targeted prismatic deviation coming from the back surface is close to zero in the desired viewing direction. So, the viewing direction of the optical system is very close to the viewing direction of the optical light guide.

(52) Secondly, the front surface FSb and the back surface BSb of the optical system (OS) have been optimized when (,) is out of the contour AC(,) according to the face form angle as a target.

(53) This optimization results in a concavo-convex shape of the front surface FSb and the back surface BSb of the ophthalmic lens 10b.

(54) Thus, the method according to the invention enables to provide an ophthalmic lens providing simultaneously both a suitable ophthalmic vision and a suitable supplementary vision to a wearer according to a face form angle of the frame as a target.

(55) During the optimization process, the light optical element geometry (thickness, size) may be taken account so that to ensure that it is embedded between the front surface and the back surface of the lens. If the light optical element is smaller than the frame, this condition does not need to be respected for the part of the lens that does not embed the optical element, thus allowing a larger range of curvature modification at the edge of the lens.

EXAMPLE 3

Optimization of the Front Surface and the Back Surface According to a Face Form Angle of the Frame as a Target (Tilt of the Light Guide Optical Element from its Initial Position)

(56) FIG. 4 represents an optical system of an ophthalmic lens 10c which is calculated according to a given spectacle frame 24 having a predetermined face form angle of the frame.

(57) Said ophthalmic lens comprises a back surface BSc and a front surface FSc arranged to deliver an ophthalmic vision.

(58) Said ophthalmic lens also comprises a light-guide optical element 23 arranged to output a supplementary image (SI) through an exit surface 26 which is defined by an angular aperture contour, denoted AC(,).

(59) In this example, the following parameters data have been provided: face form angle of the frame=20; desired viewing direction for the supplementary image 141 tilted of 0 with the horizontal plane and of 0 with the vertical plane; dimensions of the light guide optical element 3 and position of said light guide optical element as defined in example 1; wearer's accommodative effort threshold (AET)=1.5 D

(60) Firstly, the front FSc and back BSc surfaces of the ophthalmic lens of the optical system (OS) have been optimized within AC(,), so that the wearer's accommodative effort is equal or less to the wearer's accommodative effort threshold (AET) when viewing at the supplementary image (SI).

(61) Secondly, the light guide optical element 23 is tilted of 8 from the horizontal plane so as to provide an optical system having the predetermined face form angle.

(62) Thirdly, since the tilt of the light guide optical element generates a deviation of the supplementary image output from the exit surface 26, back surface BSc and front surface FSc of the optical system are optimized by adding: a prism 30 so as to adjust the supplementary image direction; a prism 29 so as to adjust the ophthalmic image direction.

EXAMPLE 4

Optimization of the Front Surface and the Back Surface According to a Pantoscopic Angle of the Frame as a Target

(63) FIG. 5 represents an optical system of an ophthalmic lens 10 according to a given spectacle frame (not shown on FIG. 5) having a predetermined pantoscopic angle of the frame.

(64) Said ophthalmic lens 10 comprises a back surface (BS) and a front surface (FS) arranged to deliver an ophthalmic vision.

(65) Said ophthalmic lens 10 also comprises a light-guide optical element 33 arranged to output a supplementary image (SI) through an exit surface 36 which is defined by an angular aperture contour, denoted AC(,).

(66) In this example, the following parameters data have been provided: pantoscopic angle of the frame=80; desired viewing direction for the supplementary image 151 tilted of 0 with the horizontal plane and of 10 with the vertical plane; dimensions of the light guide optical element 3 and position of said light guide optical element as defined in example 1; wearer's accommodative effort threshold (AET)=1.5 D

(67) Firstly, the front (FSd,FSd) and back (BSd,BSd) surfaces of the ophthalmic lens (10d,10d) of the optical system (OS) have been optimized within AC(,), so that the wearer's accommodative effort is equal or less to the wearer's accommodative effort threshold (AET) when viewing at the supplementary image (SI).

(68) Secondly, the front surface (FSd,FSd) and the back surface (BSd,BSd) of the optical system (OS) have been optimized when (,) is out of the contour AC(,) according to the pantoscopic angle as a target.

(69) For example, the front and back surfaces FSd and BSd are optimized according to a pantoscopic angle which is lower than the one for which the front and back surfaces FSd and BSd are optimized.

(70) Thus, the method according to the invention enables to provide an ophthalmic lens providing simultaneously both a suitable ophthalmic vision and a suitable supplementary vision to a wearer according to a pantoscopic angle of the frame as a target.

(71) During the optimization process, the light optical element geometry (thickness, size) may be taken account so that to ensure that it is embedded between the front surface and the back surface of the lens. If the light optical element is smaller than the frame, this condition does not need to be respected for the part of the lens that does not embed the optical element, thus allowing a larger range of curvature modification at the edge of the lens.

EXAMPLE 5

Optimization of the Front Surface and the Back Surface According to a Pantoscopic Angle of the Frame as a Target (Tilt of the Light Guide Optical Element from its Initial Position)

(72) FIG. 6 represents an optical system of an ophthalmic lens which is calculated according to a given spectacle frame (not shown on FIG. 6) having a predetermined pantoscopic angle of the frame.

(73) Said ophthalmic lens 10e comprises a back surface BSe and a front surface FSe arranged to deliver an ophthalmic vision.

(74) Said ophthalmic lens also comprises a light-guide optical element 52 arranged to output a supplementary image (SI) through an exit surface 46 which is defined by an angular aperture contour, denoted AC(,).

(75) In this example, the following parameters data have been provided: pantoscopic angle of the frame=75; desired viewing direction for the supplementary image 161 tilted of 0 with the horizontal plane and of 10 with the vertical plane; dimensions of the light guide optical element 3 and position of said light guide optical element as defined in example 1; wearer's accommodative effort threshold (AET)=1.5 D

(76) Firstly, the front FSe and back BSe surfaces of the ophthalmic lens 10e of the optical system (OS) have been optimized within AC(,), so that the wearer's accommodative effort is equal or less to the wearer's accommodative effort threshold (AET) when viewing at the supplementary image (SI).

(77) Secondly, the light guide optical element is tilted of 5 from the horizontal plane so as to provide an optical system having the predetermined pantoscopic angle.

(78) Thirdly, since the tilt of the light guide optical element generates a deviation of the supplementary image output from the exit surface 46, back surface and front surface of the optical system are optimized by adding: a prism 49 so as to adjust the supplementary image direction; a prism 50 so as to adjust the ophthalmic image direction.

(79) FIGS. 7a and 7b are sketches of an eye 100 of a wearer and of a light guide optical element 2 arranged to output a supplementary image in a spectacle lens capable of correcting the wearer's ophthalmic where said lens is incorporated in a frame.

(80) In these embodiments, the plane of the figures is a vertical plane.

(81) Axis 101 corresponds to the primary position of the eye, i.e. to an axis where ==0, and passing through the Center of Rotation of the eye (CRE).

(82) PAF represents the pantoscopic angle of the frame; it is the vertical component of the angle between the plane of the lens shape and the plane of the frame arms; the pantoscopic angle of the frame is thus defined only on the basis of geometric features of the frame. In FIGS. 7a and 7b, the plane of the lens shape refers to the plane perpendicular to the plane of the figures that encompasses dotted line 70; in these examples, the plane of the frame arms is a horizontal plane when the frame is worn by the wearer; said plane is the plane perpendicular to the plane of the figures that encompasses line 101. In said embodiment, the pantoscopic angle of the frame is about 75. According to other embodiments, the plane of the frame arms is not a horizontal plane.

(83) PALG represents the pantoscopic angle of the light-guide optical element; it is the angle between the normal to the plane of the exit surface of the light guide optical element and the line of sight of the eye in the primary position corresponding to axis 101 which corresponds to the axis where ==0.

(84) FIG. 7a shows an embodiment where the light-guide optical element is vertically centered on line 101; pantoscopic angle of the light-guide optical element, PALG, is then the angle between line 101 and the normal to the plane of the exit surface, ES.

(85) FIG. 7b shows an embodiment where the light-guide optical element is vertically shifted from line 101; line 111 is a line parallel to line 101 and intersecting the normal to the plane of the exit surface pantoscopic angle of the light-guide optical element; PALG, is then the angle between a line 111 and the normal to the plane of the exit surface, ES.

(86) As shown in examples 4 and 5, one can optimize the front surface and the back surface according to a pantoscopic angle of the frame as a target.

(87) One can optimize, on a similar way, the front surface and the back surface according to a pantoscopic angle of the light-guide optical element as a target.

(88) The invention has been described above with the aid of an embodiment without limitation of the general inventive concept; in particular the optimization criteria are not limited to the examples discussed.