Multifocal ophthalmic lens having chromatic aberration correction

Abstract

To provide an ophthalmic lens that includes an optic comprising an anterior surface, a posterior surface and an optical axis.SOLUTION: At least one of the anterior and posterior surfaces has a surface profile including a base curvature, a refractive region having the base curvature, and a diffractive region comprising a diffractive profile including a plurality of diffractive steps. At least a portion of the diffractive profile constitutes a combination of a base diffractive profile defining multiple foci of the ophthalmic lens and a chromatic aberration correction structure that reduces longitudinal chromatic aberrations.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to ophthalmic lenses, and more particularly to ophthalmic lenses having chromatic aberration correction. [Background technology]

[0002] Intraocular lenses (IOLs) are routinely implanted in a patient's eye during cataract surgery to replace the natural crystalline lens. IOLs may include monofocal IOLs, which provide a single focus (e.g., distance vision), and multifocal IOLs, which provide two or more foci (e.g., trifocal IOLs, which provide distance, intermediate, and near vision). Multifocal IOLs may include diffractive surface profiles, which may include many concentric ring-like echelettes that diffract light in several directions simultaneously. Such diffractive surface profiles may provide multiple orders of diffraction and focus light into different images corresponding to different focal lengths of the lens.

[0003] Due to the dispersive properties of the lens and the eye, all IOLs (including multifocal IOLs) can exhibit chromatic aberration, where blue light focuses in front of the retina and red light focuses behind the retina. Such out-of-focus light can degrade the lens' overall efficiency in focusing broadband light energy onto the patient's retina and interfere with the patient's visual function, such as photopic vision at distance and low-contrast vision under mesopic conditions. This problem can be particularly troublesome for patients with multifocal IOLs, where light is split between multiple foci.

[0004] Therefore, there is a need for a multifocal IOL having an optical design that provides chromatic aberration correction. Summary of the Invention [Means for solving the problem]

[0005] The present disclosure relates generally to multifocal ophthalmic lenses (e.g., IOLs) that provide correction or reduction of chromatic aberration. More specifically, the present disclosure provides chromatic aberration correcting structures that, when added to a diffractive multifocal IOL surface profile, improve white light performance, particularly for distance vision under photopic and mesopic conditions.

[0006] In some embodiments, an ophthalmic lens includes an optical element including an anterior surface, a posterior surface, and an optical axis. At least one of the anterior surface and the posterior surface has a surface profile including a base curvature, a refractive region having the base curvature, and a diffractive region including a diffractive profile including a plurality of diffractive steps. At least a portion of the diffractive profile constitutes a combination of a base diffractive profile that defines a plurality of focal points of the ophthalmic lens and an achromatic structure that reduces longitudinal chromatic aberration.

[0007] In some embodiments, the present disclosure may provide one or more technical advantages. For example, a multifocal IOL may exhibit chromatic aberrations, where blue light focuses in front of the retina and red light focuses behind the retina. These chromatic aberrations may be at least partially due to the dispersion properties of the IOL itself and / or the dispersion properties of the eye in which the IOL is housed. The out-of-focus light resulting from chromatic aberrations may degrade the overall efficiency of the IOL in focusing broadband light energy onto the retina and may interfere with visual performance (e.g., low-contrast vision under mesopic conditions at distance). The addition of the chromatic aberration correction structures described herein may reduce the distance between the blue and red foci, which in turn effectively pushes the broadband white light to a focal point on the retina. Thus, the added chromatic aberration correction structures improve broadband white light image quality performance.

[0008] In addition to improving broadband white light image quality performance, chromatic aberration correction structures according to some embodiments of the present disclosure, when added to a diffractive multifocal IOL surface profile, may reduce a patient's perception of visual disturbances such as halos (i.e., the subjective perception of a bright ring around a light source). In particular, the addition of chromatic aberration correction structures to a diffractive profile as described herein may reduce the longitudinal chromatic aberration (LCA) of the lens-eye system, which may lead to a reduction in the size of out-of-focus blur for red and blue light. Because halos have been associated with out-of-focus blur, this reduction in out-of-focus blur may result in halo reduction and potentially better retinal image contrast.

[0009] For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which like reference characters indicate like features, and in which: [Brief description of the drawings]

[0010] [Figure 1A] 1 illustrates an exemplary embodiment of a multifocal IOL with chromatic aberration correction according to some embodiments of the present disclosure. [Figure 1B] 1 illustrates an exemplary embodiment of a multifocal IOL with chromatic aberration correction according to some embodiments of the present disclosure. [Figure 2A] 1 shows an exemplary surface profile of a multifocal IOL having a diffractive region that does not include an added chromatic aberration correcting structure. [Figure 2B] 1 shows an exemplary surface profile of a multifocal IOL having a diffractive region that does not include an added chromatic aberration correcting structure. [Figure 3A] 1 illustrates an exemplary surface profile of a multifocal IOL with chromatic aberration correction according to some embodiments of the present disclosure. [Figure 3B] 1 illustrates an exemplary surface profile of a multifocal IOL with chromatic aberration correction according to some embodiments of the present disclosure. [Figure 3C] 1 illustrates an exemplary surface profile of a multifocal IOL with chromatic aberration correction according to some embodiments of the present disclosure. [Figure 4A] 2 is an MTF plot showing both the white light performance and the green light performance of an exemplary IOL as depicted in FIG. 1 (including the chromatic aberration correction structures described herein) compared to a multifocal IOL excluding the chromatic aberration correction structures described herein, both in large and small apertures. [Figure 4B] 2 is an MTF plot showing both the white light performance and the green light performance of an exemplary IOL as depicted in FIG. 1 (including the chromatic aberration correction structures described herein) compared to a multifocal IOL excluding the chromatic aberration correction structures described herein, both in large and small apertures. [Figure 4C] 2 is an MTF plot showing both the white light performance and the green light performance of an exemplary IOL as depicted in FIG. 1 (including the chromatic aberration correction structures described herein) compared to a multifocal IOL excluding the chromatic aberration correction structures described herein, both in large and small apertures. [Figure 4D] 2 is an MTF plot showing both the white light performance and the green light performance of an exemplary IOL as depicted in FIG. 1 (including the chromatic aberration correction structures described herein) compared to a multifocal IOL excluding the chromatic aberration correction structures described herein, both in large and small apertures. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Those skilled in the art will understand that the accompanying drawings, described below, are for illustrative purposes only and are not intended to limit the scope of Applicant's disclosure in any way.

[0012] The present disclosure relates generally to multifocal ophthalmic lenses (e.g., IOLs) that provide chromatic aberration correction. More specifically, the present disclosure provides chromatic aberration correction structures that, when added to a diffractive multifocal IOL surface profile, improve white light performance, particularly for distance vision under photopic and mesopic conditions. In the following description, lens features that provide multifocality and chromatic aberration correction are described in the context of intraocular lenses (IOLs). However, the present disclosure is not limited to the disclosed embodiments. 、It is contemplated that these features may also be applied to other ophthalmic lenses, such as contact lenses. As used herein, the term "intraocular lens" (and its abbreviation IOL) is used to describe a lens that is implanted inside the eye to either replace the eye's natural lens or to otherwise enhance vision whether or not the natural lens is removed.

[0013] 1A-1B illustrate an exemplary embodiment of a multifocal IOL 100 with chromatic aberration correction according to some embodiments of the present disclosure. The IOL 100 includes an optic 102 having an anterior surface 104 and a posterior surface 106 disposed about an optical axis 108. The IOL 100 may further include a number of haptics 110 operable to position and stabilize the IOL 100, typically within the capsular bag of a patient's eye. Although haptics 110 having a particular structure are illustrated for illustrative purposes, the present disclosure contemplates haptics 110 having any suitable structure for stabilizing the IOL 100 within the capsular bag, within the ciliary sulcus, or any other suitable location within the eye.

[0014] In the following description, the front surface 104 of the optical system 102 is described as having a particular surface condition that provides multifocality and chromatic aberration correction. 、 It is contemplated that such features may additionally or alternatively be located on the rear surface 106 of the optical system 102 .

[0015] The anterior surface 104 of the optical system 102 may have a base curvature that corresponds to the base power of the IOL 100. In a multifocal IOL such as IOL 100, the base power of the IOL 100 typically corresponds to the patient's distance visual acuity. However, this need not be the case. For example, the non-dominant eye may have an IOL with a base power that is slightly lower than the corresponding distance power in order for the patient to improve the overall binocular visual acuity of both eyes. In some embodiments, the base curvature may be aspheric (as described in more detail below).

[0016] In addition to the base curvature, the anterior surface 104 of the optical system 102 may include multiple regions. For example, the anterior surface 104 may include a diffractive region 112, which may extend from the optical axis 108 to a first radial boundary, and a refractive region 114, which may extend from the first radial boundary to a second radial boundary (e.g., an end of the optical system 102). In some embodiments, the curvature of the diffractive region 112 may be modified relative to the base curvature. Although the anterior surface 104 of the optical system 102 is depicted and described as having only two regions (the diffractive region 112 and the refractive region 114), the present disclosure is not limited to the embodiments shown and described herein. 、 It is contemplated that the anterior surface 104 of the optical system 102 may include a surface profile having any suitable number of regions. By way of example only, the anterior surface 104 could alternatively include a surface profile having two refractive regions separated by a diffractive region.

[0017] In some embodiments, the diffractive region 112 includes a diffractive structure 116 having a plurality of diffractive steps (also known as sections) 118. The diffractive steps 118 may have a unique radial distance interval to generate positive interference at a unique focus. In principle, any diffractive structure 116 that generates positive interference via phase shifting in the interference sections may be adapted for use in the diffractive region 112 to generate a multifocal diffractive ophthalmic lens. Although the diffractive structure 116 of the diffractive region 112 is depicted by annular sections, these sections could conceivably be partial, such as semicircular sections or sector sections. Although the following description will be in terms of a diffractive structure 116 including annular diffractive steps 118, one skilled in the art should understand that suitable substitutions may be made in any embodiment disclosed herein.

[0018] At least a part of the diffractive structure 116 of the diffractive region 112 is a basic diffractive profile (for example, F diffractiveThe addition of a chromatic aberration correction structure may be characterized, at least in part, as a combination of a chromatic aberration correction structure (e.g., g(r) in Equations (5) and (11) below) and a chromatic aberration correction structure. As described in more detail below, the addition of a chromatic aberration correction structure may provide a multifocal IOL with better white light performance and / or reduced halo compared to a multifocal IOL that does not include an added chromatic aberration correction structure. To illustrate this difference, for example, the following disclosure first describes an example surface profile that does not include an added chromatic aberration correction structure.

[0019] In a multifocal IOL having a diffractive region 112 that does not include the added chromatic aberration correction structures described herein, the profile of the anterior surface 104 (including both the diffractive region 112 and the refractive region 114) may be defined as follows: Sag(r)=Z base (r) 0≦r≦r1 Sag(r)=Z base (r)+F diffractive (r,T)+Δ1r1≦r≦r2 Sag(r)=Z base (r)+Δ2r2≦r≦r3 Equation (1) Where: r represents the radial distance from the optical axis, Z base (r) represents the base curvature of the surface, F diffractive (r,T) represents the profile of the diffractive structure 116 that generates the multifocality in the design; T is the r 2 Represents periods in space, r1, r2, and r3 represent various radial junctions; Δ1 and Δ2 are constants that ensure the proper phase shift between the various sections of the IOL.

[0020] In an embodiment in which the diffractive region 112 extends from the optical axis 108 to a first radial boundary and the refractive region 114 extends from the first radial boundary to the end of the optical system 102, r1 may be equal to zero, r2 may define the first radial boundary, and r3 may define the end of the optical system 102.

[0021] In some embodiments where the base curvature of the anterior surface 104 of the optical system 102 is aspheric, Z base (r) may be defined as:

number

[0022] Although equation (2) is shown above to include up to n-th order transformation constants, the present disclosure 、 It is contemplated that equation (2) may be restricted to any suitable number of transformation constants (eg, only quadratic, fourth order, and sixth order transformation constants).

[0023] A diffractive structure F that splits the light into various orders corresponding to multiple viewing distances (i.e., diffractive regions 112). diffractive For (r,T), the spacing between adjacent orders is the period T(r 2 In space: Unit: mm 2 ) can be determined as follows:

number

[0024] This disclosure 、 Diffractive structure F diffractiveIt is contemplated that (r,T) may define any suitable diffractive profile, such as, for example, a bifocal diffractive profile, a trifocal diffractive profile, or an apodized diffractive profile. diffractive (r,T) can be expressed as:

number

number

number

[0025] As another example, the multifocal diffractive structure F diffractive (r,T) may define an apodized bifocal diffractive structure such as that described in US Pat. No. 5,699,142, the contents of which are incorporated herein by reference.

[0026] As yet another example, the multifocal diffractive structure F diffractive (r,T) may define a trifocal diffractive structure such as that described in US Pat. No. 9,335,564, the contents of which are incorporated herein by reference.

[0027] 2A-2B show the surface profile of a multifocal IOL having a diffractive region 112 that does not include the additional chromatic aberration correction structures described herein (designed according to Equations (1)-(3)). In particular, FIG. 2A depicts a plot of "Sag (mm) vs. Radius (mm)" that includes a diffractive step 118 within the diffractive region 112. To better illustrate the diffractive step 118, FIG. 2B is a plot of the same surface profile depicted in FIG. 2A, but with the addition of a diffractive step 118. diffractive Only the effect of (r,T) is shown. In the depicted example, F diffractive (r,T) defines an apodized bifocal diffractive structure in which the step height of the diffraction grating is reduced with increasing radial distance from the optical axis 108.

[0028] Due at least in part to the dispersive properties of the IOL itself and / or the eye in which the IOL may be housed, multifocal IOLs designed according to Equations (1)-(3) above, examples of which are depicted in Figures 2A-2B, may exhibit chromatic aberration in which blue light focuses in front of the retina and red light focuses behind the retina. Such defocused light may degrade the overall efficiency of the IOL in focusing broadband light energy onto the retina and may interfere with visual performance (e.g., low-contrast visual acuity under mesopic conditions at distance).

[0029] Thus, in some embodiments, the multifocal IOL described above may be modified to further include achromatic aberration correction structures added to the surface profile to generate a multifocal IOL 100 with chromatic aberration correction. In other words, at least a portion of the diffractive structures 116 of the diffractive region 112 may be characterized at least in part as a combination of a basic diffractive profile and achromatic aberration correction structures such that the optical system 102 (including the diffractive region 112 and the refractive region 114) generates multiple foci and exhibits reduced chromatic aberration. The achromatic aberration correction structures may include any suitable diffractive structures that, when added to the basic diffractive structures of the diffractive region of the multifocal IOL, reduce the amplitude of the longitudinal chromatic aberration compared to a multifocal IOL having a diffractive region that includes only the basic diffractive structures.

[0030] An exemplary chromatic aberration correction structure may be expressed as follows:

number

number

number

[0031] In some embodiments, r1' in Equation (5) may be equal to r1 in Equation (1) (which may be equal to zero as discussed above) and r2' in Equation (5) may be equal to r2 in Equation (1) (which may define the location of the first radial boundary separating the diffractive region 112 and the refractive region 114 as discussed above). In some other embodiments, r1' in Equation (5) may not be equal to r1 in Equation (1) and r2' in Equation (5) may not be equal to r2 in Equation (1). In such embodiments, r1' in Equation (5) may be greater than r1 in Equation (1) and r2' in Equation (5) may be less than r2 in Equation (1).

[0032] The step height h in equation (5) can correspond to an integer number of wavelengths:

number

[0033] In some embodiments, the period T g may be the same as the multifocal grating period T in equation (1). In some other embodiments, the period T g can be constrained by the following relation: T g =NT or T=NT g Formula (7) Where: N is an integer, T is the r of the original multifocal grating structure in Eq. (1). 2 Represents periods in space, T g is the added chromatic aberration correction structure 2 Represents a period in space.

[0034] The additional chromatic aberration correction structure defined by equation (5) can shift the light to another order than the standard grating contained within equation (1). This changes the focal length of the multifocal design by:

number

[0035] To compensate for such defocus shifts, the corresponding parts of the base curve can be adjusted as follows: Sag(r)=Z base (r) 0≦r≦r1 Sag(r)=Z base (r)+F diffractive (r,T)+Δ1' r1≦r≦r1' Sag(r)=Z' base (r)+F diffractive (r,T)+Δ1'' r1'≦r≦r2' Sag(r)=Z base (r)+F diffractive (r,T)+Δ1''' r2'≦r≦r2 Sag(r)=Z base (r)+Δ2' r2≦r≦r3 Equation (9) Where: r represents the radial distance from the optical axis, Z base (r) represents the base curvature correcting the patient's distance visual acuity as shown in Equation (2); Z' base (r) represents the base curvature that corrects the patient's distance visual acuity, taking into account the focus shift caused by the addition of the chromatic aberration correction structure in Eq. (5); F diffractive (r,T) represents the basic diffractive profile that provides multifocality in the design; T is the r of the basic diffraction profile 2 Represents periods in space, r1, r2, and r3 represent the junctions at the surface as shown in formula (1); r1' and r2' represent the junction points on the surface as shown in equation (5). Δ1' 、 Δ1'' 、 Δ1′″ and Δ2′ are constants that ensure the proper phase shift between the various sections of the IOL.

[0036] Z' in equation (9) base (r) can also be expressed as an aspheric surface as follows:

number

[0037] Although equation (10) is shown above to include up to n-th order transformation constants, the present disclosure 、 It is contemplated that equation (10) can be restricted to a maximum of 20th order transformation constants.

[0038] In some embodiments, the parameters (c', k', a2', a4', a6', ..., a n One or more of the parameters (ck, a2, a4, a6, ..., a ') in equation (2) are adjusted to compensate for the defocus shift Δf outlined in equation (8). n ) is adjusted for

[0039] A surface profile of the anterior surface 104 of IOL 100 having chromatic aberration correction (due to added chromatic aberration correction structures) that improves broadband white light performance can be achieved by combining equations (5) and (9) (or, alternatively, equation (1)) as follows: Thug achromatized_multifocal = sag(r) + g(r) Equation (11)

[0040] 3A-3C show a surface profile of a multifocal IOL 100 with chromatic aberration correction (designed according to Equation (11)) according to some embodiments of the present disclosure. In particular, FIG. 3A depicts a plot of "Sag (mm) vs. Radius (mm)" for an exemplary chromatically corrected multifocal IOL 100 including modified diffractive steps 118 resulting from the addition of the chromatic aberration correction structures described above. Also plotted is a surface profile without the chromatic aberration correction structures (the same profile depicted in FIG. 2A). By comparing the two, it can be seen that the addition of the chromatic aberration correction structures results in a more pronounced diffractive step 118. Also, the result of compensating for the defocus shift (see Equation (9) above and corresponding discussion) can be seen as a reduction in sag in the diffractive region 112 of the chromatically corrected multifocal surface profile. FIG. 3B is a plot showing only the added chromatic aberration correction structures g(r) as defined in Equation (5), while FIG. 3C is a plot of the same chromatically corrected multifocal surface profile depicted in FIG. 3A, but with the addition of F(r) as defined in Equation (5). diffractiveOnly the effects of (r,T) and g(r) are shown.

[0041] As discussed above, multifocal IOLs designed according to Equations (1)-(3), whose exemplary surface profiles are depicted in FIGS. 2A-2B, may exhibit longitudinal chromatic aberration (LCA) due to ocular dispersion and IOL material dispersion. In other words, blue light may be focused in front of the retina and red light may be focused behind the retina. The LCA of such a multifocal IOL may be characterized as follows:

number

[0042] When the multifocal design is modified via equation (11) to include the chromatic aberration correction structures described herein, the added chromatic aberration correction structures will reduce the LCA as follows:

number

[0043] In particular, because the wavelength of blue light is shorter than that of red light, the added structure g(r) always produces a negative ΔLCA. In other words, the added structure shortens the distance between the blue and red foci. This in turn effectively pushes the broadband white light to a focal point on the retina. Thus, the added chromatic aberration correction structure improves the broadband white light image quality performance.

[0044] Equation (13) can also be rewritten as:

number

[0045] 4A-4D are modulation transfer function (MTF) plots showing both white and green light performance of an exemplary IOL 100 (including the chromatic aberration correction structures described herein) compared to a multifocal IOL excluding the chromatic aberration correction structures described herein at both large and small apertures. As shown, IOL 100 provides improved white light performance at both large and small apertures while nearly maintaining green light performance at both large and small apertures.

[0046] It will be understood that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. It will also be understood that various presently unforeseen or unanticipated substitutions, modifications, variations, or improvements may be subsequently made by those skilled in the art, and that such substitutions, variations, or improvements are also intended to be encompassed by the appended claims.

Claims

1. 1. An ophthalmic lens comprising an optical element including a front surface, a back surface, and an optical axis, At least one of the front surface and the rear surface is The base curvature, a refractive region having the base curvature; a diffraction region including a diffraction profile including a plurality of diffraction steps; and at least a portion of the diffractive profile comprises: a base diffractive profile defining multiple focal points of the ophthalmic lens; Chromatic aberration correction structure that reduces longitudinal chromatic aberration It is a combination of The surface profile is defined as follows: [0010] where Sag(r) defines the surface profile of the Ophthalmic Lens excluding the chromatic aberration correction structure; g(r) defines the chromatic aberration correction structure; r ３ , r １ ' and r ２ ' represents a junction point on said surface profile, r represents the radial distance from the optical axis, T ｇ is the r of the chromatic aberration correction structure ２ Represents periods in space, 【number】 represents the floor function, where, 【number】 is a set of integers, h represents the step height of an ophthalmic lens.

2. The ophthalmic lens of claim 1 , wherein the base curvature corresponds to a base refractive power of the ophthalmic lens.

3. the diffractive region extends from the optical axis to a first radial boundary; The ophthalmic lens of claim 1 , wherein the refractive region extends from the first radial boundary to an edge of the optic.

4. The ophthalmic lens of claim 1 , wherein the base diffractive profile comprises an apodized diffractive profile.

5. r ３ The ophthalmic lens of claim 1 , wherein defines an outer edge of the optic. 【Request 6】 【Number 2】 2. The ophthalmic lens of claim 1.

7. The a ｎ 7. The ophthalmic lens of claim 6, wherein n=20 for

8. h=N ｈ λ / (. ＩＯＬ -. ｏｃｕｌａｒｍｅｄｉａ ); N ｈ is an integer, λ represents the design wavelength, n ＩＯＬ represents the refractive index of the ophthalmic lens, n ｏｃｕｌａｒｍｅｄｉａ The ophthalmic lens of claim 1 , wherein:

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