Abstract
The object of the invention relates to an artificial ophthalmic lens (20) that contains an anterior optical surface (21) and a posterior optical surface (22), where the anterior optical surface (21) and the posterior optical surface (22) have a common optical axis (23), and at least one of the anterior optical surface (21) and the posterior optical surface (22) is a multifocal optics (24) that at least partly has a multifocal optical diffractive profile (25). A cross apodized profile part (25) is formed on the diffractive profile (25), in other words phase shifting elements (27) are provided on the diffractive profile (25) that alternately form the elements of a decreasingly apodized series (40) and an increasingly (reversed) apodized series (41) in such a way that the decreasing and increasing elements of the two series (40, 41) form envelope curves that meet at a common intersection point (45). The object of the invention also relates to a method for the production of such an artificial ophthalmic lens (20).
Claims
1. A multifocal artificial ophthalmic lens (20) that contains an anterior optical surface (21) and a posterior optical surface (22), where the anterior optical surface (21) and the posterior optical surface (22) have a common optical axis (23), and at least one of the anterior optical surface (21) and the posterior optical surface (22) is a multifocal optics (24) at least partly comprising a multifocal optical diffractive profile (25), wherein a cross apodized profile part (25) is formed on the diffractive profile (25), and phase shifting elements (27) are provided on the diffractive profile (25) that alternately form the elements of a decreasingly apodized series (40) and an increasingly (reversed) apodized series (41) in such a way that the decreasing and increasing elements of the two series (40, 41) define envelope curves that meet at a common intersection point (45).
2. The multifocal artificial ophthalmic lens according to claim 1, wherein starting from the optical axis (23) the height of every odd-numbered phase shifting element (27) decreases monotonously as a function of distance from the optical axis (23), and the height of every even-numbered phase shifting element (27) increases monotonously as a function of distance from the optical axis (23).
3. The multifocal artificial ophthalmic lens according to claim 1, wherein starting from the optical axis (23) the height of every odd-numbered phase shifting element (27) increases monotonously as a function of distance from the optical axis (23), and the height of every even-numbered phase shifting element (27) decreases monotonously as a function of distance from the optical axis (23).
4. The multifocal artificial ophthalmic lens according to claim 2, wherein the diffractive profile (25) contains an non-apodized diffractive profile part (42) that peripherally surrounds the cross apodized profile part (25).
5. The multifocal artificial ophthalmic lens according to claim 2, wherein the diffractive profile (25) contains an apodized diffractive profile part (43) that peripherally surrounds the cross apodized profile part (25).
6. The multifocal artificial ophthalmic lens according to claim 2, wherein the common intersection point of the envelope curves is at or within the boundary of the cross apodized profile part (25) of the diffractive profile (25) or within it.
7. The multifocal artificial ophthalmic lens according to claim 2, wherein the entire diffractive profile (25) is cross apodized.
8. The multifocal artificial ophthalmic lens according to claim 1, wherein the multifocal optics (24) has a purely refractive optical refractive zone (44) peripherally surrounding the diffractive profile (25).
9. The multifocal artificial ophthalmic lens according to claim 4, wherein the number of the phase shifting elements (27) in the cross apodized profile part (25) of the diffractive profile (25) is between five and twenty.
10. The multifocal artificial ophthalmic lens according to claim 1, further comprising haptics (26).
11. A method of producing a multifocal artificial ophthalmic lens (20), which artificial lens contains an anterior optical surface (21) and a posterior optical surface (22), where the anterior optical surface (21) and the posterior optical surface (22) have a common optical axis (23), and at least one of the anterior optical surface (21) and the posterior optical surface (22) is a multifocal optics (24) at least partly comprising a multifocal optical diffractive profile (25), wherein the method comprises forming cross apodization on the diffractive profile (25) by providing phase shifting elements (27) that alternately form the elements of a decreasingly apodized series (40) and an increasingly (reversed) apodized series (41) in such a way that the decreasing and increasing phase shifting elements (27) of the two series (40, 41) form envelope curves that meet at a common intersection point (45).
12. The method according to claim 11, wherein the method comprises producing the phase shifting elements (27) using a material removal process.
13. The method of claim 12, wherein the material removal process comprises machining.
14. The method of claim 11, wherein the method further comprises producing the phase shifting elements by hot forming.
15. The method of claim 11, wherein the method further comprises producing the phase shifting elements by injection moulding.
16. The multifocal artificial ophthalmic lens according to claim 4, wherein the number of the phase shifting elements (27) in the cross apodized profile part (25) of the diffractive profile (25) is between five and seven.
Description
BRIEF DESCRIPTION OF DRAWINGS
[0027] FIG. 1 depicts a schematic side view of an exemplary embodiment of the present invention.
[0028] FIG. 2a depicts a front view of an exemplary embodiment of the artificial ophthalmic lens according to the invention.
[0029] FIG. 2b depicts a front view of another exemplary embodiment of the artificial ophthalmic lens according to the invention.
[0030] FIG. 3a depicts an embodiment of the artificial ophthalmic lens according to the invention where the decreasing and increasing (reversed) apodizations meet at a common intersection point within the diffractive profile, while the part of the diffractive profile outside of the intersection point is non-apodized.
[0031] FIG. 3b depicts an embodiment of the artificial ophthalmic lens according to the invention where the decreasing and increasing (reversed) apodizations meet at a common intersection point within the diffractive profile, while the part of the diffractive profile peripheral with respect to the intersection point is decreasingly apodized, and the multifocal optics contains further refractive zones peripheral to (outside of) the cross apodized diffractive profile.
[0032] FIG. 3c depicts an embodiment of the artificial ophthalmic lens according to the invention where the decreasing and increasing (reversed) apodizations meet at a common intersection point within the diffractive profile and continue beyond the intersection point, and the multifocal optics contains further refractive zones peripheral to the cross apodized diffractive profile.
[0033] FIG. 3d depicts an embodiment of the artificial ophthalmic lens according to the invention where the decreasing and increasing (reversed) apodizations meet at a common intersection point within the diffractive profile and continue beyond the intersection point, and the multifocal optics contains further refractive zones peripheral to the intersection point.
[0034] FIG. 4a shows the modulation transfer function (MTF) of an artificial ophthalmic lens in accordance with FIG. 3d and measured using an instrument operating as an optical bench.
[0035] FIG. 4b shows the simulated modulation transfer function (MTF) of an artificial ophthalmic lens in accordance with FIG. 3a.
[0036] FIG. 5 depicts a schematic diagram showing the possible dimensioning of the phase shifting elements of the cross apodization according to the invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS ACCORDING TO THE INVENTION
[0037] The artificial ophthalmic lens described in the present invention may be an artificial lens implanted in the capsular bag, the ciliary sulcus or in the anterior chamber, and may be a contact lens, or an artificial lens that can be implanted in the cornea using an inlay or onlay technique. The Figures presented above relate to some types of the implantable artificial lens, but other lens types may also be formed using the principle according to the invention.
[0038] FIG. 1 depicts a schematic side view of an exemplary embodiment of an artificial ophthalmic lens 20 according to the present invention, in which it can be seen that the artificial ophthalmic lens 20 contains an anterior optical surface 21 and a posterior optical surface 22. The anterior optical surface 21 and the posterior optical surface 22 have a common optical axis 23. In the case of the present embodiment the posterior optical surface 22 is formed as a multifocal optics 24, which partly has a multifocal optical diffractive profile 25. The present embodiment is also provided with haptics 26, since an implantable artificial lens is shown in FIG. 1.
[0039] FIG. 2a depicts a front view of a possible embodiment of the artificial ophthalmic lens according to the invention, where the inner zone falling closer to the optical axis 23 of the multifocal optics 24 provided with haptics 26 has a multifocal optical diffractive profile 25, and a monofocal peripheral refractive zone 44 surrounding it.
[0040] FIG. 2b depicts a front view of another possible embodiment of the artificial ophthalmic lens according to the invention, where the entire multifocal optics 24, also provided with haptics 26, is provided with a multifocal optical diffractive profile 25.
[0041] A significant feature of the implementation of the multifocal (trifocal-bifocal) optical performance is the diffractive profile 25, which is located on the anterior optical surface 21 or the posterior optical surface 22 of the artificial ophthalmic lens. The phase shifting elements (phase shifting zones) closer to the optical axis 23 of the diffractive profile 25 at least partially form a profile that enhances three diffraction orders. The phase shifting elements further away from the optical axis 23 at least partially form a profile that enhances two diffraction orders when using an annular aperture centered on the optical axis 23.
[0042] An important feature of such a diffractive profile with trifocal-bifocal optical performance is the so-called cross apodized profile part (cross apodization). A possible implementation of cross apodization is that when starting from the optical axis 23 the height of every odd-numbered phase shifting element (in other words the distance between the base point and the peak of the given phase shifting element) decreases monotonously as a function of distance from the optical axis 23, where a central zone is the first phase shifting element, and starting from the optical axis 23 the height of every even-numbered phase shifting element increases monotonously as a function of distance from the optical axis 23. Another implementation of cross apodization is that when starting from the optical axis 23 the height of every odd-numbered phase shifting element increases monotonously as a function of distance from the optical axis 23, where a central zone is the first phase shifting element, and starting from the optical axis 23 the height of every even-numbered phase shifting element decreases monotonously as a function of distance from the optical axis 23.
[0043] FIG. 3a depicts a possible implementation of the multifocal optics with trifocal-bifocal optical performance in which the phase shifting elements 27 of the cross apodized profile part 25 of the diffractive profile 25 can be divided, in a direction perpendicular to the optical axis 23, into a decreasingly apodized series 40 and an increasingly (reversed) apodized series 41, in other words cross apodization is provided, at least partly, on the diffractive profile 25. The decreasing and increasing elements of the series 40 and 41 meet at a common intersection point 45. In other words envelope curves that intersect at the common intersection point 45 may be fitted onto the phase shifting elements of the decreasing apodization series 40 and onto the phase shifting elements of the increasingly apodized series 41, as it can be seen in FIGS. 3a to 3d. In the case of the present examples the envelope curves are straight lines, but, naturally, other shaped envelope curves are conceivable, such as envelope curves that decrease or increase according to a polynomial function.
[0044] In FIG. 3a the intersection point 45 is at the boundary of the cross apodized profile part 25, however, other embodiments are also conceivable in the case of which the intersection point 45 is within the boundary of the cross apodized profile part 25 (see FIG. 3c), or in the case of which the intersection point 45 is outside of the boundary of the cross apodized profile part 25, in other words the phase shifting elements 27 of the decreasingly apodized series 40, and the phase shifting elements 27 of the increasingly apodized series 41 do not actually meet in size. In case of a particularly preferred embodiment the intersection point 45 is on the external boundary of the cross apodized profile part 25, whereby the profile of the artificial ophthalmic lens 20 outside of this boundery may be continued at the height of the intersection point, as it can be seen in the case of the present embodiment. In the present case a non-apodized diffractive profile part 42 is provided outwards from the intersection point 45 (in other words moving outwards in the radial direction perpendicular to the optical axis 23). The heights of the phase shifting zones of the non-apodized diffractive profile part 42 are the same, and its optical performance is bifocal. In the case of this embodiment the non-apodized diffractive profile part 42 forms a circular ring symmetrical around the optical axis 23. In other words in the case of this embodiment the diffractive profile 25 contains the central cross apodized profile part 25, and the non-apodized diffractive profile part 42 surrounding it peripherally.
[0045] In FIG. 3b a different exemplary embodiment of the multifocal optics with trifocal-bifocal optical performance can be seen, in the case of which the central cross apodized profile part 25 of the diffractive profile 25 is formed by a decreasingly apodized series 40 and by an increasingly (reversed) apodized series 41 of phase shifting elements 27 in a direction perpendicular to the optical axis 23, the envelope curves of which meet at a common intersection point 45, in other words the central part of the diffractive profile 25 is cross apodized. The diffractive profile 25 is formed as a diffractive profile part 43 that is decreasingly apodized outwards from the intersection point 45 perpendicular to the optical axis. The apodized diffractive profile 43, similarly to the non-apodized diffractive profile 42, preferably surrounds the inner part of the diffractive profile 25 in a ring shape. In the case of this embodiment the multifocal optics 24 is provided with a refractive zone peripherally surrounding the diffractive profile 25.
[0046] FIG. 3c presents a different possible embodiment of the multifocal optics with trifocal-bifocal optical performance according to the invention, in which the phase shifting elements 27 of the diffractive profile 25 form a decreasingly apodized series 40 and an increasingly (reversed) apodized series 41 alternatingly in a direction perpendicular to the optical axis 23 in such a way that the common intersection point 45 of the envelope curves fitted onto the decreasing and increasing elements of the two series 40, 41 fall within the boundary of the cross apodized profile part 25 of the diffractive profile 25, as opposed to the previously shown embodiments, in the case of which the intersection point 45 falls on the boundary of the cross apodized profile part 25. In the case of the present embodiment the cross apodized profile part 25 of the diffractive profile 25 continues outwards from the intersection point 45 in such a way that the elements of the decreasingly apodized series 40 and the increasingly (reversed) apodized series 41 continue to be provided beyond the common intersection point 45. In the case of this embodiment the multifocal optics 24 is also provided with a refractive zone 44 peripherally surrounding the diffractive profile 25.
[0047] FIG. 3d presents a preferred embodiment of the multifocal optics 24 with trifocal-bifocal optical performance in which the entire diffractive profile 25 can be divided, in a direction perpendicular to the optical axis 23, into a decreasingly apodized series 40 and an increasingly (reversed) apodized series 41 of phase shifting elements 27. The boundary of the phase shifting zone of the diffractive profile most distant from the optical axis 23 essentially coincides with the intersection point 45, in other words with the intersection point of the envelope curves that can be fitted onto the phase shifting elements 27 of the series 40, 41. In other words, the diffractive profile 25 is formed substantially until the intersection point 45. The phase shift of the first (odd numbered) phase shifting element 27 of the embodiment presented in FIG. 3d falls in the range of 0.55 . . . 0.59.Math., while the phase shift of the second (even numbered) zone falls in the range of 0.30 . . . 0.34.Math.. The phase shift of the phase shifting elements 27 of the decreasingly apodized series 40 (odd numbered zones) is a monotonously decreasing function of distance measured from the optical axis 23. The phase shift of the phase shifting elements 27 of the series 41 (even numbered zones) is a monotonously increasing function of distance measured from the optical axis 23. The phase shift of the phase shifting elements 27 at the intersection point 45 of the diffractive profile 25 is in the range 0.42 . . . 0.46.Math..
[0048] The total number of the phase shifting elements 27 in the cross apodized profile part 25 of the diffractive profile 25 is preferably between five and twenty, even more preferably between five and seven, still even more preferably seven.
[0049] The cross apodized profile part 25 of the diffractive profile 25 may be combined with any known lens structure, in other words the artificial ophthalmic lens may be toric, aspherical or free-form.
[0050] The quantitative assessment of the image formation of the embodiment illustrated in FIG. 3d can be seen in FIG. 4a, which shows the modulation transfer function (MTF) of the artificial ophthalmic lens 20 according to the present invention measured on an optical bench at a spatial frequency of 50 line pairs/mm. The curve 28 shown with solid line relates to an test aperture diameter of 2.0 mm, the curve 29 shown with dashed line relates to an aperture of 3.0 mm, and the curve 30 shown with dotted line relates to an aperture of 4.5 mm, which apertures correspond to the various typical pupil diameters. In the present case the intersection point 45 is located at 1.5 mm from the optical axis 23, in other words the radius of the aperture belonging to the broken line curve 29 extends until the intersection point 45. The MTF curves illustrate how the image formation quality changes as a function of object distance. The MTF curves obtained at the various apertures are determined by the depth of focus dependent on aperture diameter and by the intensity distribution together. On the basis of FIG. 4 it maybe determined that in the case of a small aperture (narrow pupil), in other words when the phase shifting elements 27 of the diffractive profile closest to the optical axis 23 take part in the image formation, the MTF curve (solid line curve 28) displays extremely great trifocality. It can be clearly seen on the solid line curve 28 that the proximity of the peaks corresponding to the two most distant foci results in an extended depth of focus (EDoF), which ensures better intermediate distance vision for the user. The great degree of trifocality occurring at small apertures, and the aforementioned EDoF optics are the result of the large height differences between the phase shifting elements 27 of decreasing and increasing height close to the optical axis 23. This height difference drops moving away from the optical axis as a result of the cross apodization according to the invention up until the intersection point 45, which also results in the reduction in trifocality (see dashed line curve 29). In practice, the dashed line curve 29 corresponds to an optical performance similar to the trifocal lenses used widely in clinical practice. Therefore the artificial ophthalmic lens 20 according to the invention retains the proven characteristic shown by the broken line 29 while at the same time it is capable of ensuring imaging properties that produce better intermediate vision in the case of smaller apertures.
[0051] By increasing the aperture beyond the intersection point 45 the refractive zone 44 also becomes involved in the imaging, which reduces the trifocal character even more. Therefore the dotted line curve 30 belonging to the largest aperture is mainly monofocal.
[0052] FIG. 4b illustrates the imaging of the artificial ophthalmic lens 20 according to FIG. 3a. The solid line curve 28 relates to a 2.0 mm diameter test aperture, the broken line curve 29 to a 3.0 mm aperture, and the dotted line curve 30 to a 4.5 mm aperture. With the appropriate selection of the zone around the periphery of the cross apodized profile part 25 of the diffractive profile 25 various types of optical performance can be created at the largest apertures in accordance with the various demands. For example, the dotted line curve 30 shown in FIG. 4a displays a substantially monofocal optical performance, but the dotted line curve 30 in FIG. 4b is purely bifocal as a consequence of the non-apodized diffractive profile part 42. With the increase of the size of the pupil the optical performance of the embodiment presented in FIG. 3b changes from trifocal to bifocal and monofocal. With the increase of the size of the pupil the embodiment presented in FIG. 3c changes from trifocal to bifocal, then again into trifocal (MTF curves not illustrated).
[0053] FIG. 5 depicts a schematic diagram illustrating the possible dimensioning of the phase shifting elements of the cross apodization according to the invention, where the letters a, b and c mark the height of the central zone (first phase shifting element), of the phase shifting element next to the central zone, and of the phase shifting element at the intersection point 45, respectively, and Rint refers to the distance of the intersection point 45 from the optical axis 23. It should be noted that in the case of those embodiments where the intersection point 45 is further outside from the boundary of the cross apodized profile part 25, the height c can be determined indirectly, such as by using interpolation. For the diffractive profile 25 according to the invention the ratio of the b/a heights is preferably between 0.30 and 0.95, more preferably between 0.4 and 0.70, and the ratio of the c/a heights is preferably between the b/a height and 1. The distance Rint of the intersection point 45 from the optical axis 23 is preferably between 0.6 mm and 3.0 mm, more preferably between 1.25 mm and 2.5 mm.
[0054] The invention also relates to a method for the production of an artificial ophthalmic lens 20 that contains an anterior optical surface 21 and a posterior optical surface 22, where the anterior optical surface 21 and the posterior optical surface 22 have a common optical axis 23, and at least either the anterior optical surface 21 or the posterior optical surface 22 is a multifocal optics 24 that has at least a partially multifocal optical diffractive profile 25.
[0055] In the course of the method according to the invention cross apodization, determined by the phase shifting elements 27 of a decreasingly apodized series 40 and of an increasingly (reversed) apodized series 41, is provided on the diffractive profile 25 at least partially in such a way that the decreasing and increasing phase shifting elements 27 of the series 40, 41 meet at a common intersection point 45.
[0056] In the case of a preferred embodiment of the method according to the invention the phase shifting elements 27 are produced using a material removal process, preferably using machining (removing by turning) or hot forming, preferably injection moulding.
[0057] The advantage of the present invention is that depending on the diameter of the pupil various intensity distributions can be created, and the number of focal points can also be varied.
