Diffractive multifocal ophthalmic lens with chromatic aberration correction function

Abstract

Certain embodiments provide an intraocular lens (IOL) (200) that includes a lens body (202) having a front surface (202A) and a rear surface (202P), and a diffraction structure (208) having a plurality of echelette gratings (210) formed on at least one of the front surface or the rear surface. The surface profile of the diffraction structure includes a base surface profile configured to diffract incident light at one or more diffraction orders, and a chromatic aberration surface profile including an increased step height of the plurality of echelette gratings and a phase offset between adjacent echelette gratings of the plurality of echelette gratings with respect to the base surface profile.

Description

Background Art

[0001] Briefly, the human eye functions to provide vision by transmitting light through a transparent outer portion called the cornea and forming an image on the retina by means of the lens. The quality of the formed image depends on many factors including the size and shape of the eye, as well as the transparency of the cornea and the lens. When the transparency of the lens decreases due to age or disease, the amount of light that can be transmitted to the retina decreases, resulting in a decrease in vision. Such an impairment of the eye's lens is medically known as cataract. The generally recognized treatment for this condition is to surgically remove the lens and replace the function of the lens with an intraocular lens (IOL).

[0002] The IOL is replaced with the eye's natural lens and is used in both refractive lens exchange surgery and cataract surgery to correct refractive abnormalities. Among them are diffractive multifocal IOLs. However, in some cases, such diffractive multifocal IOLs may cause chromatic aberration, which can have an adverse effect on vision and contrast sensitivity.

Summary of the Invention

Means for Solving the Problems

[0003] Aspects of the present disclosure provide an intraocular lens (IOL) including a lens body having a front surface and a rear surface, and a diffractive structure having a plurality of echelette gratings formed on at least one of the front surface or the rear surface. The surface profile of the diffractive structure includes a base surface profile configured to diffract incident light at one or more diffraction orders, and a color cancellation surface profile including an increasing step height with respect to the base surface profile within the plurality of echelette gratings and various phase offsets that are integer multiples of the design wavelength between adjacent echelette gratings among the plurality of echelette gratings.

[0004] Aspects of the present disclosure also provide an intraocular lens (IOL) including a lens body having a front surface and a rear surface, and a diffraction structure having a plurality of echelette gratings formed on at least one of the front surface or the rear surface. The diffraction structure is configured to provide a first focus for distance vision, a second focus for intermediate vision, and a third focus for near vision for incident light having a design wavelength, and a shift of the first focus of less than 0.30 diopters for incident light having a wavelength with a difference of 50 nm from the design wavelength.

[0005] Aspects of the present disclosure further provide an intraocular lens (IOL) including a lens body having a front surface and a rear surface, and a diffraction structure having a plurality of echelette gratings formed on at least one of the front surface or the rear surface. The surface profile of the diffraction grating includes a base surface profile configured to diffract incident light at one or more diffraction orders, and a chromatic aberration reduction surface profile including a plurality of echelette gratings having an increasing step height with respect to the base surface profile, and at least one of the increasing step heights is a non-integer multiple of the design wavelength.

[0006] To enable a more detailed understanding of the above features of the present disclosure, a more specific description of the present disclosure briefly summarized above can be obtained by referring to the embodiments, some of which are shown in the accompanying drawings. However, it should be noted that the accompanying drawings show only some aspects of the present disclosure, and the present disclosure may admit other equally valid embodiments.

Brief Description of the Drawings

[0007]

Figure 1A

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[0008] For ease of understanding, where possible, the same elements common to each figure are designated with the same reference numerals. It is contemplated that the elements and features of one embodiment may be advantageously incorporated into other embodiments without further mention.

[0009] The embodiments described herein provide a multifocal intraocular lens (IOL) having a diffraction structure designed for chromatic aberration correction, as well as methods and systems for fabricating the same. In certain embodiments, the step height of the echelette grating of the diffraction structure and the phase offset of the echelette grating of the diffraction structure are configured such that the diffraction orders effective for correcting chromatic aberration can be used for distance vision, intermediate vision, and near vision. For example, the step height of each of the echelette gratings can be adjusted by an amount not limited to an integer multiple of the design wavelength to shift the diffraction orders available for distance vision, intermediate vision, and near vision. In addition, the phase offset between adjacent echelette gratings can be configured to further control chromatic aberration without performing a diffraction order shift and without varying the diffraction efficiency by various integer multiples of the design wavelength. Therefore, the IOLs according to the embodiments described herein provide increased design options while simultaneously improving chromatic aberration correction.

[0010] The chromatic aberration (i.e., the change in focus with respect to wavelength) of a diffractive multifocal IOL lens having a chromatic aberration correction function is due to either the dispersion characteristics of the lens material (i.e., the change in refractive index with respect to wavelength) or the lens structure. In the case of a refractive lens, as in the example shown in FIG. 1A, longer wavelengths are focused at a greater distance, because the refractive index of a typical lens material decreases as the wavelength increases. On the other hand, a diffractive lens exhibits the opposite chromatic aberration, as in the example shown in FIG. 1B. The diffraction angle is proportional to the wavelength, and thus longer wavelengths are focused at a shorter distance. Therefore, in a lens having a diffractive lens portion and a refractive lens portion, as shown in FIG. 1C, the chromatic aberration due to the refractive lens portion can be compensated by the chromatic aberration due to the diffractive lens portion, and thus the overall chromatic aberration of the lens can be corrected. Furthermore, the diffraction angle of the diffractive lens portion depends on the diffraction order. Therefore, in the embodiments described herein, the diffraction structure of the diffractive lens portion is adjusted so as to be able to use a diffraction order that effectively corrects the overall chromatic aberration.

[0011] FIG. 2A shows a top view of an intraocular lens (IOL) 200 according to a particular embodiment. FIG. 2B shows a side view of a cross-sectional view of the IOL 200. The IOL 200 includes a lens body 202 and a haptic portion 204 coupled to a peripheral non-optical portion of the lens body 202.

[0012] The lens body 202 can be made of a biocompatible material such as modified poly(methyl methacrylate) (PMMA), modified PMMA hydrogel, hydroxyethyl methacrylate (HEMA), PVA hydrogel, other silicone polymer materials, hydrophobic acrylic polymer materials, such as AcrySof® and Clareon® available from Alcon, Inc., Fort Worth, Texas. The diameter φ of the lens body 202 is about 4.5 mm to about 7.5 mm, for example about 6.0 mm. It should be noted that the shape and curvature of the lens body 202 are shown for illustrative purposes only, and other shapes and curvatures are also included within the scope of the present disclosure. For example, the lens body 202 shown in FIG. 2B has a biconvex shape. In other examples, the lens body 202 can have a plano-convex shape, a convex-concave shape, or a plano-concave shape.

[0013] The haptic portion 204 is coupled (e.g., adhesively or welded) to the peripheral portion of the lens body 202 or is molded with a portion of the lens body 202, thereby extending outwardly from the lens body 202 and engaging the outer peripheral wall of the eye's lens capsule to hold the lens body 202 in a desired position of the eye, and includes hollow radially extending struts (also referred to as "haptics") 204A and 204B. The haptics 204A and 204B can be made of modified poly(methyl methacrylate) (PMMA), modified PMMA hydrogel, hydroxyethyl methacrylate (HEMA), PVA hydrogel, other silicone polymer materials, hydrophobic acrylic polymer materials, such as biocompatible materials such as AcrySof® and Clareon® available from Alcon, Inc., Fort Worth, Texas. The haptics 204A and 204B typically have radially outer ends that define arcuate terminal portions. The terminal portions of the haptics 204A and 204B can be spaced apart by a length L of about 6 mm to about 22 mm, such as about 13 mm. The haptics 104A and 104B have a specific length such that when in contact with the equatorial region of the lens capsule after insertion, the terminal portions generate a slight engagement pressure. FIG. 1A shows one exemplary configuration of the haptics 204A and 204B, but any plate haptic or other type of haptic can also be used.

[0014] The IOL 200 is a multifocal IOL (having multiple foci, such as bifocal, trifocal, quadrifocal, and pentafocal IOLs), which is characterized by a base curvature 206 and a diffraction structure 208 formed on the front surface 202A of the lens body 202. The diffraction structure 208 diffracts incident light into a plurality of diffraction orders, and the light energy, power, or intensity of the incident light is divided among these plurality of diffraction orders. Therefore, the diffraction efficiency of each diffraction order is less than 100%. Although the diffraction structure 208 is shown only on the front surface 202A of the lens body 202 in FIG. 2B, the diffraction structure 208 may be formed on the rear surface 202P of the lens body 202 or on both the front surface 202A and the rear surface 202P of the lens body 202.

[0015] The diffraction structure 208 includes a plurality of echelette gratings 210. The circular echelette grating 210A is centered on the optical axis 212 of the lens body 202 and has the smallest radius. The annular echelette grating 210B adjacent to the circular echelette grating 210A is centered on the optical axis 212 of the lens body 202 and has a radius larger than the minimum radius. The annular echelette grating 210C adjacent to the annular echelette grating 210B is centered on the optical axis 212 of the lens body 202 and has a radius larger than the radius of the annular echelette grating 210B. In certain embodiments, the echelette grating 210 includes one or more annular echelette gratings (not numbered in FIG. 2A) surrounding the annular echelette grating 210C. As shown in FIG. 2B, the step height of the echelette grating 210 can be different for each echelette grating. In some embodiments, the step height of the echelette grating 210 is constant across the surface of the lens body 202. The spacing (i.e., radial distance) between adjacent echelette gratings 210 may vary or be constant across the surface of the lens body 202. The step height of the echelette grating 210 is expressed in units of Δn·λ, where Δn is the difference in refractive index between the lens body 202 and the surrounding medium in which the lens body 202 is disposed.

[0016] In some embodiments, the diffraction structure 208 is used to provide a bifocal lens having two focal lengths for near and far vision. The bifocal lens may utilize a first diffraction order for far vision and a second diffraction order for near vision. In other embodiments, the diffraction structure 208 may provide a trifocal lens having three focal lengths for near, intermediate, and far vision. The trifocal lens may utilize a zero-order diffraction for far vision, a first-order diffraction for intermediate vision, and a second-order diffraction for near vision. In other embodiments, the diffraction structure 208 is used to provide a quadrifocal lens. The quadrifocal lens may utilize a zero-order diffraction for far vision, a second-order diffraction for intermediate vision, a third-order diffraction for near vision, and the first-order diffraction may be suppressed.

[0017] In certain embodiments described herein, to optimize overall chromatic aberration correction, the diffractive structure 208 is adjusted to shift the diffraction orders used for distance vision, intermediate vision, and near vision by adjusting the step height a of the echelette grating 210 and the phase offset φ between adjacent echelette gratings 210.

[0018] Figure 3 shows the surface profile F diffractive (x) of the diffractive structure 208 showing the variation in height of the echelette grating 210 on an exemplary multifocal lens. The surface profile F diffractive (x) shows the variation in height of the echelette grating 210 with respect to the base curvature 206. As shown in the figure, the circular echelette grating 210A has a radius r1 (x1 = r1 2 ), a step height a1, and a phase offset φ1 with respect to the base curvature 206. The annular echelette grating 210B surrounding the circular echelette grating 210A has a radius r2 (x2 = r2 2 ), a step height a2, and a phase offset φ2 with respect to the circular echelette grating 210A. The annular echelette grating 210C surrounding the annular echelette grating 210B has a radius r3 (x3 = r3 2 ), a step height a3, and a phase offset φ3 with respect to the annular echelette grating 210B.

[0019] In certain embodiments, as shown in Figure 3, the surface profile F diffractive (x) of the diffractive structure 208 for the three echelette gratings 210A, 210B, 210C is repeated, whereby the echelette grating with radius r4 (x4 = r4 2 ) has the same step height and phase offset as the echelette grating 210A (i.e., step height a1 and phase offset φ1), and the echelette grating with radius r5 (x5 = r5 2 ) has the same step height and phase offset as the annular echelette grating 210B (i.e., step height a2 and phase offset φ2), and the echelette grating with radius r5 (x5 = r5 2 ) 2 ​​​​​​​​​​​​​​​​) The echelle grating has the same step height and phase offset (i.e., step height a3 and phase offset φ3) as the echelle grating 210C.

[0020] The diffraction order can be shifted by increasing all of the step heights a1, a2, a3 and adjusting the phase offsets φ1, φ2, φ3 individually. The total increase in step height can be a non-integer multiple of the wavelength λ. The phase offsets φ1, φ2, φ3 can be increased or decreased by an integer multiple of the wavelength λ, without adversely affecting the diffraction efficiency or order at the design wavelength, and without adversely affecting chromatic aberration. Therefore, the phase offsets φ1, φ2, φ3 can be adjusted to optimize the correction of overall chromatic aberration by increasing or decreasing the phase offset by an integer multiple of the wavelength λ.

Example

[0021] FIG. 4A shows the surface profile F diffractive (x) of a diffractive structure (e.g., diffractive structure 208) having an echelle grating (e.g., echelle grating 210) on an exemplary four-focus lens (referred to as the "basic design"). The surface profile F diffractive (x) of the basic design, also referred to as the "base surface profile", is denoted as F base (x). The surface profile F diffractive (x) with respect to the base curvature of the diffractive structure (e.g., base curvature 206) is shown in units of λ·Δn, where λ is the design wavelength (e.g., 550 nm) and Δn is the difference in refractive index between the lens and the surrounding medium in which the lens is disposed. Here, x = r 2 where r is the radial distance from the optical axis of the lens (e.g., optical axis 212) and is normalized by the period (r3). FIG. 4B shows the diffraction efficiency at the design wavelength for various diffraction orders of an exemplary four-focus lens of the basic design. In this example, the zero-order diffraction can be used for distance vision, the second-order diffraction can be used for intermediate vision, and the third-order diffraction can be used for near vision. The first-order diffraction can be suppressed.

[0022] Figure 4C shows the surface profile F of a diffractive structure (e.g., diffractive structure 208) having an Echelette grating (e.g., Echelette grating 210) on an exemplary four-focus lens (referred to as "Shift + 3 design"). diffractive (x). In the Shift + 3 design, the surface profile F diffractive (x) is the base surface profile F base (x) with a color suppression profile F achromatizing (x) added thereto. In the color suppression profile F achromatizing (x), all the step heights a of the Echelette grating are increased by one wavelength λ from the base surface profile F base (x). The diffraction orders that provide high diffraction efficiency are shifted by 3 compared to those of the basic design (shown in Figure 4B), as shown in Figure 4D. In this example, the third-order diffraction can be used for distance vision, the fifth-order diffraction can be used for intermediate vision, and the sixth-order diffraction can be used for near vision. The fourth-order diffraction can be suppressed.

[0023] Figure 4E shows the surface profile F of a diffractive structure (referred to as "Shift + 5 design") having an Echelette grating on an exemplary four-focus lens. diffractive (x). In the Shift + 5 design, the surface profile F diffractive (x) is the base surface profile F base (x) with a color suppression profile F achromatizing (x) added thereto. In the color suppression profile F achromatizing (x), all the step heights a of the Echelette grating 210 are increased by 5 / 3 wavelengths λ from the base surface profile F base (x), and its phase offsets are φ1 = 0, φ2 = -1 / 3, φ3 = -2 / 3 wavelengths λ. In one exemplary case, the step height of the Echelette grating 210 is the base surface profile F base(x) includes wavelengths of a1 = 1.68, a2 = 1.70, a3 = 1.59 from (x), and the phase offsets can be φ1 = 0, φ2 = -0.35, φ3 = -0.6 wavelengths, and these are values that can be obtained using other numerical optimization techniques. The diffraction orders that provide high diffraction efficiency are shifted by 5 compared to those of the basic design (shown in FIG. 4B), as shown in FIG. 4F. In this example, the 5th order diffraction can be used for far vision, the 7th order diffraction can be used for intermediate vision, and the 8th order diffraction can be used for near vision. The 6th order diffraction can be suppressed.

[0024] FIG. 4G shows the surface profile F diffractive (x) of a diffraction structure (referred to as a "shift + 4 design") having an echelette grating on an exemplary four - focus lens. In the shift + 4 design, the surface profile F diffractive (x) is the base surface profile F base (x) with the achromatic profile F achromatizing (x) added, and in the achromatic profile F achromatizing (x), all the step heights a of the echelette grating 210 are increased by 4 / 3 wavelength λ from the base surface profile F base (x), and its phase offsets are φ1 = 0, φ2 = 1 / 3, φ3 = -1 / 3 wavelength λ. In an exemplary case, the step heights of the echelette grating 210 include a1 = 1.35, a2 = 1.36, a3 = 1.31 wavelengths from the base surface profile F base (x), and the phase offsets can be φ1 = 0, φ2 = 0.3, φ3 = -0.3 wavelengths, and these are values that can be obtained using other numerical optimization techniques. The diffraction orders that provide high diffraction efficiency are shifted by 4 compared to those of the basic design (shown in FIG. 4B), as shown in FIG. 4H. In this example, the 4th order diffraction can be used for far vision, the 6th order diffraction can be used for intermediate vision, and the 7th order diffraction can be used for near vision. The 5th order diffraction can be suppressed.

[0025] FIG. 4I shows the surface profile F diffractive(x) is shown. In the shift +2 design, the surface profile F diffractive (x) is the base surface profile F base (x) with the bleaching profile F achromatizing (x) added to it, and in the bleaching profile F achromatizing (x), all of the step heights a of the echelle grating 210 are increased by 2 / 3 wavelength λ from the base surface profile, and the phase offsets are φ1 = 0, φ2 = -1 / 3, φ3 = -2 / 3 wavelength λ. The diffraction orders providing high diffraction efficiency are shifted by 2 compared to those of the basic design (shown in FIG. 4B), as shown in FIG. 4J. In this example, the second-order diffraction can be used for far vision, the fourth-order diffraction can be used for intermediate vision, and the fifth-order diffraction can be used for near vision. The third-order diffraction can be suppressed. In certain embodiments, the shift +2 design can be advantageous, particularly when used with an IOL material having lower material dispersion.

[0026] FIG. 5A shows the modulation transfer function (MTF) of an exemplary four-focus lens of the basic design shown in FIGS. 4A and 4B. The MTF was evaluated at the focal plane with a spatial resolution of 100 lm / mm (lines per millimeter) (also referred to as "spatial frequency") using a 3-mm (photopic) aperture, thereby determining the depth of focus (also referred to as "defocus") of the lens. The peak positions for 0 diopters, 1.5 diopters, and 2.5 diopters with respect to the design wavelength (550 nm) correspond to the zero-order diffraction for far vision, the second-order diffraction for intermediate vision, and the third-order diffraction for near vision, respectively. As can be seen from FIG. 5A, this lens exhibits a significant amount of chromatic aberration. All of the peak positions shift significantly at shorter wavelengths (500 nm) and longer wavelengths (600 nm). For example, the magnitude of the shift is 0.35 diopters for a wavelength of 600 nm and 0.45 for a wavelength of 500 nm. In certain embodiments, the magnitude of the shift depends on the dispersion characteristics of the lens material.

[0027] FIG. 5B shows the MTF of an exemplary four-focus lens of the shift +3 design shown in FIGS. 4C and 4D, where the bleaching profile F achromatizingIn (x), all of the step heights a of the echelle grating 210 are the base surface profile F base is increased by one wavelength λ from (x). Compared to the basic design, the shift of the peak position for wavelengths other than the design wavelength (550 nm) is reduced. In particular, the shifts of the peaks at 1.5 diopters (for intermediate vision) and 2.5 diopters (for near vision) are significantly reduced. The peaks are shifted by approximately 0.3 diopters to approximately 0.2 diopters for shorter wavelengths (500 mm) and longer wavelengths (600 nm), respectively. In certain embodiments, the magnitude of the shift depends on the dispersion characteristics of the lens material.

[0028] FIG. 5C shows the MTF of an exemplary 4-focus lens of the shift +5 design shown in FIGS. 4E and 4F, where the achromatic profile F achromatizing In (x), all of the step heights a of the echelle grating 210 are the base surface profile F base is increased by 5 / 3 wavelengths λ from (x), and the phase offsets are φ1 = 0, φ2 = -1 / 3, φ3 = -2.3 wavelengths λ. Compared to the basic design, the shifts of the peak positions at 0 diopters (for distant vision), 1.5 diopters (for intermediate vision), and 2.5 diopters (for near vision) are all significantly reduced. In distant vision, the peak positions at the three wavelengths are well aligned, and thus negligible chromatic aberration is achieved. The shift of the peak at 0 diopters (for distant vision) due to the chromatic aberration of the dispersion characteristics of the lens material is reduced using diffraction orders that are shifted by 5 compared to those of the basic design. In intermediate / near vision, although significantly reduced compared to the basic design, residual chromatic aberration may remain.

[0029] FIG. 5D shows the MTF of an exemplary 4-focus lens of the shift +4 design shown in FIGS. 4G and 4H, where the achromatic profile F achromatizing In (x), all of the step heights a of the echelle grating 210 are the base surface profile F base(x) is increased by 4 / 3 wavelengths λ, and the phase offsets are φ1 = 0, φ2 = 1 / 3, and φ3 = -1 / 3 wavelengths λ. The amount of peak shift is between the "shift + 3" design and the "shift + 5" design. In the "shift + 3" design, far vision is not corrected much, and in the "shift + 5" design, intermediate / near vision is overcorrected. On the other hand, in the "shift + 4" design, chromatic aberration has the same magnitude at all positions. The magnitude of the shift depends on the dispersion characteristics of the lens material.

[0030] System for designing an IOL FIG. 6 shows an exemplary system 600 for designing, configuring, and / or forming an IOL 200. As shown, system 600 includes, but is not limited to, a control module 602, a user interface display 604, an interconnect 606, an output device 608, and at least one I / O device interface 610, and the I / O device interface 610 can enable connection of various I / O devices (e.g., keyboard, display, mouse device, pen input, etc.) to system 600.

[0031] The control module 602 includes a central processing unit (CPU) 612, a memory 614, and a storage 616. The CPU 612 can read and execute programming instructions stored in the memory 614. Similarly, the CPU 612 can acquire and store application data in the memory 614. The interconnect 606 transmits programming instructions and application data among the CPU 612, the I / O device interface 610, the user interface display 604, the memory 614, the storage 616, the output device 608, etc. The CPU 612 can represent a single CPU, multiple CPUs, a single CPU having multiple processing cores, etc. In addition, in certain embodiments, the memory 614 represents volatile memory such as random access memory. Further, in certain embodiments, the storage 616 can be non-volatile memory such as a disk drive, a solid state drive, or an aggregate of storage devices distributed across multiple storage systems.

[0032] As shown, the storage 616 includes input parameters 618. The input parameters 618 include the lens base power and refractive index of the lens body. The memory 614 includes a calculation module 620 for calculating control parameters such as the step height and phase offset of the echelette grating of the diffraction structure. In addition, the memory 614 includes input parameters 622.

[0033] In certain embodiments, the input parameters 622 correspond to the input parameters 618 or at least a subset thereof. In certain embodiments, when calculating the control parameters, the input parameters 622 are read from the storage 616 and executed within the memory 614. In such an example, the calculation module 620 includes executable instructions for calculating the control parameters based on the input parameters 622. In certain other embodiments, the input parameters 622 correspond to parameters received from the user through the user interface display 604. In such embodiments, the calculation module 620 includes executable instructions for calculating the control parameters based on the information received from the user interface display 604.

[0034] In certain embodiments, the calculated control parameters are output via the output device 608 to a lens manufacturing system configured to receive the control parameters and form a lens accordingly. In certain other embodiments, the system 600 itself represents at least a part of the lens manufacturing system. In such embodiments, the control module 602 then causes the hardware components (not shown) of the system 600 to form a lens according to the control parameters. Details of the lens manufacturing system are known to those skilled in the art and are omitted here for brevity.

[0035] Method for forming IOL FIG. 7 shows an exemplary operation 700 for forming an IOL (e.g., IOL 200). In some embodiments, step 710 of operation 700 is performed by one system (e.g., system 600), and step 720 is performed by a lens manufacturing system. In some other embodiments, both steps 710 and 720 are performed by a lens manufacturing system.

[0036] In step 710, control parameters such as the step height and phase offset of the echelle grating of the diffraction structure are calculated based on input parameters (e.g., the lens base power and refractive index of the lens body). The calculations performed in step 710 are based on one or more of the embodiments described herein. Various optimization techniques or algorithms may be used to select appropriate step heights and phase offsets of the echelle grating of the refractive structure to optimize or maximize achromatism. For example, a method may be used to numerically minimize an error function for calculating the difference between the target refractive efficiency and the actual refractive efficiency by varying the design parameters.

[0037] As an alternative to using various optimization techniques to select appropriate step heights and phase offsets of the echelle grating of the refractive structure to optimize or maximize achromatism, a method may be used to identify the step height and phase offset of the echelle of the diffraction structure to achieve a shift in the diffraction order.

[0038] FIG. 8 shows an exemplary method for identifying an appropriate step height and phase offset of a diffraction structure to shift the diffraction order by 1 with respect to a base profile. In particular, FIG. 8 shows a base profile 810 having a corresponding series of diffraction orders 840 centered on the 0th order. To shift the diffraction order of the base profile 810 by 1 (i.e., to implement a “shift +1” design), the phase of the base profile 810 can be raised using a 1-wave wedge 820 across the entire base profile 810 in the manner shown in FIG. 8, resulting in a diffraction structure 830 having a corresponding series of diffraction orders 850. As shown in the figure, there is a 1st order shift (i.e., from the 0th order to the 1st order) in the diffraction order 850 with respect to the diffraction order 840. It should be noted that in this specification, a wedge is a triangular structure corresponding to the shape of a right triangle. In the embodiment of FIG. 8, the wedge 820 has a side 870 whose length defines a 1-wave wedge. In other embodiments, as will be described later, wedges of various integer waves can be used. For example, a 2-wave wedge (the length of its corresponding side is twice the length of the side 870 of the 1-wave wedge 820), a 3-wave wedge, or other multi-wave wedges can be used.

[0039] FIG. 9 shows various exemplary diffraction structures including diffraction structure 830 and other profiles or modified types having the same set 850 of diffraction orders. Other modified types of diffraction structure 830 are shown as diffraction structures 960 and 970. As shown in the figure, diffraction structures 830, 960, and 970 all have the same diffraction order 850, and thus all achieve the same diffraction efficiency shift +1 design. Modified types 960 and 970 can be formed by shifting (e.g., decreasing) the phase of one or more echelle gratings 934 and 936 of diffraction structure 830 by an integer multiple of the design wavelength. For example, with respect to diffraction structure 830, in diffraction structure 960, the phase of echelle grating 936 is decreased by one wavelength over the entire echelle grating. Note that diffraction structure 960 has the same diffraction efficiency as diffraction structure 830 at the design wavelength. In other examples, with respect to diffraction structure 830, in diffraction structure 970, the phase of echelle grating 934 is decreased by one wavelength over the entire echelle grating. Also note that diffraction structure 970 has the same diffraction efficiency as diffraction structures 830 and 960 at the design wavelength. By shifting the phases of echelle gratings 934 and 936 in other ways, diffraction structures having the same shift +1 design and diffraction efficiency can be fabricated.

[0040] Note that FIGS. 8 and 9 show only the formation of diffraction structures by the shift +1 design, but it should be noted that diffraction structures with further shifted diffraction orders can also be formed using similar techniques. For example, in the case of a shift +2 design, the phase of base profile 810 can be raised using a two-wavelength wedge over the entire base profile 810 to form a diffraction structure having a series of diffraction orders centered around the second order. In such an example, other modified types or profiles of the resulting diffraction structure can be generated by shifting down the phase of one or more echelle gratings of the resulting diffraction structure by one or more integer multiples of the design wavelength. Such modified types can similarly have a series of diffraction orders centered around the second order and can have the same diffraction efficiency as the diffraction structure obtained by raising the phase of base profile 810 using a two-wavelength wedge.

[0041] Returning again to FIG. 7, at step 720, an IOL (e.g., IOL 200) is formed using suitable methods, systems, and apparatuses typically used in the manufacture of lenses, which are known to those of ordinary skill in the art, based on the calculated control parameters such as the step height and phase offset of the echelette grating of the diffraction structure.

[0042] Embodiments described herein provide a multifocal intraocular lens (IOL) having a diffraction structure with chromatic aberration corrected. In a multifocal IOL according to embodiments described herein, chromatic aberration due to the dispersion characteristics of the lens material of the refractive lens portion of the IOL is compensated by chromatic aberration of the diffraction portion of the IOL, and the overall chromatic aberration of the IOL is corrected. The overall chromatic aberration of the IOL can be optimized by adjusting the step height and phase offset of the diffraction structure of the diffraction portion of the IOL. Such adjustment provides more diverse design options for optimizing chromatic aberration correction. For example, by enabling the step height of the echelette grating to be adjusted by an amount other than an integer multiple of the design wavelength, more precise control of chromatic aberration correction may be possible. Optionally, the visual impairment performance may also be improved by providing a smaller step height.

[0043] The foregoing relates to embodiments of the present disclosure, but other and further embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure, the scope of which is determined by the claims set forth in the following claims.

Claims

1. Intraocular lenses (IOLs) The lens body, including the front and rear, A diffraction structure having a plurality of echelet gratings formed on at least one of the front surface or the rear surface, Includes, The surface profile of the diffraction structure is A base surface profile configured to diffract incident light to one or more diffraction orders, It is a matte surface profile, The step height of the plurality of echellet grids is increased with respect to the base surface profile, and Phase offset between adjacent Echellet lattices of the plurality of Echellet lattices A matte surface profile including, Intraocular lenses (IOLs), including those mentioned above.

2. The IOL according to claim 1, wherein at least one of the increased step heights is a non-integer multiple of the design wavelength.

3. The IOL according to claim 1, wherein the one or more diffraction orders provide far vision, mid-vision, and near vision.

4. The IOL according to claim 3, wherein the achromatic surface profile shifts one or more diffraction orders by 4 to provide far view, mid-view, and near view.

5. The IOL according to claim 3, wherein the achromatic surface profile shifts one or more diffraction orders by 5 in order to provide far view, mid-view, and near view.

6. The IOL according to claim 3, wherein the achromatic surface profile shifts one or more diffraction orders by 2 to provide far view, mid-view, and near view.

7. The IOL according to claim 1, wherein the lens body comprises a hydrophobic acrylic polymer material.

8. The IOL according to claim 1, further comprising one or more haptics coupled to the lens body.

9. Intraocular lenses (IOLs) A lens body having a front and a rear section, A diffraction structure having a plurality of echelet gratings formed on at least one of the front surface and the rear surface, Includes, The diffraction structure is configured to provide a first focus for far vision, a second focus for mid-range vision, and a third focus for near vision with respect to incident light having a design wavelength. An intraocular lens (IOL) wherein the first focal shift is less than 0.3 diopters for incident light having a wavelength that is 40 to 70 nm different from the design wavelength.

10. The surface profile of the diffraction structure is A base surface profile configured to diffract incident light at one or more diffraction orders, It is a matte surface profile, The increased step height of the plurality of echellet grids with respect to the base surface profile, and Phase offset between adjacent Echellet lattices of the plurality of Echellet lattices A matte surface profile including, The IOL according to claim 9, including the IOL.

11. The IOL according to claim 10, wherein at least one of the increased step heights is a non-integer multiple of the design wavelength.

12. The IOL according to claim 10, wherein the one or more diffraction orders provide far vision, mid-vision, and near vision.

13. The IOL according to claim 12, wherein the achromatic surface profile shifts one or more diffraction orders by 4 to provide far view, mid-view, and near view.

14. The IOL according to claim 12, wherein the achromatic surface profile shifts one or more diffraction orders by 5 to provide far view, mid-view, and near view.

15. The IOL according to claim 12, wherein the achromatic surface profile shifts one or more diffraction orders by 2 to provide far view, mid-view, and near view.

16. The IOL according to claim 10, wherein the lens body comprises a hydrophobic acrylic polymer material.

17. The IOL according to claim 10, further comprising one or more haptics coupled to the lens body.

18. Intraocular lenses (IOLs) A lens body having a front and a rear section, A diffraction structure having a plurality of echelet gratings formed on at least one of the front surface or the rear surface, Includes, The surface profile of the diffraction structure is A base surface profile configured to diffract incident light at one or more diffraction orders, Achromatic surface profile comprising a plurality of echellet gratings having increased step heights with respect to the base surface profile, wherein at least one of the increased step heights is a non-integer multiple of the design wavelength, Intraocular lenses (IOLs), including those mentioned above.

19. The IOL according to claim 18, wherein the one or more diffraction orders provide far vision, mid-vision, and near vision.

20. The IOL according to claim 19, wherein the achromatic surface profile shifts one or more diffraction orders by 4 to provide far view, mid-view, and near view.

21. The IOL according to claim 19, wherein the achromatic surface profile shifts one or more diffraction orders by 5 to provide far view, mid-view, and near view.

22. The IOL according to claim 18, wherein the lens body comprises a hydrophobic acrylic polymer material.

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