Extended range and related intraocular lenses for presbyopia treatment

Abstract

Apparatuses, systems and methods for providing improved ophthalmic lenses, particularly intraocular lenses (IOLs), include features for reducing dysphotopsia effects, such as haloes and glare, in extended range of vision lenses. Exemplary ophthalmic lenses can include a central zone with a first set of three echelettes arranged around the optical axis, the first set having a profile in r-squared space. An intermediate zone includes a second set of three echelettes arranged around the optical axis, the second set having a profile in r-squared space that is different than the profile of the first set. A peripheral zone includes a third set of three echelettes arranged around the optical axis, the third set having a profile in r-squared space that is different than the profile of the first set and the profile of the second set.

Description

BACKGROUND

Embodiments of the present invention relate to vision treatment techniques and in particular, to ophthalmic lenses such as, for example, contact lenses, corneal inlays or onlays, or intraocular lenses (IOLs) including, for example, phakic IOLs and piggyback IOLs (i.e. IOLs implanted in an eye already having an IOL).

Presbyopia is a condition that affects the accommodation properties of the eye. As objects move closer to a young, properly functioning eye, the effects of ciliary muscle contraction and zonular relaxation allow the lens of the eye to change shape, and thus increase its optical power and ability to focus at near distances. This accommodation can allow the eye to focus and refocus between near and far objects.

Presbyopia normally develops as a person ages, and is associated with a natural progressive loss of accommodation. The presbyopic eye often loses the ability to rapidly and easily refocus on objects at varying distances. The effects of presbyopia usually become noticeable after the age of 45 years. By the age of 65 years, the crystalline lens has often lost almost all elastic properties and has only a limited ability to change shape.

Along with reductions in accommodation of the eye, age may also induce clouding of the lens due to the formation of a cataract. A cataract may form in the hard central nucleus of the lens, in the softer peripheral cortical portion of the lens, or at the back of the lens. Cataracts can be treated by the replacement of the cloudy natural lens with an artificial lens. An artificial lens replaces the natural lens in the eye, with the artificial lens often being referred to as an intraocular lens or “IOL”.

Monofocal IOLs are intended to provide vision correction at one distance only, usually the far focus. At the very least, since a monofocal IOL provides vision treatment at only one distance and since the typical correction is for far distance, spectacles are usually needed for good vision at near distances and sometimes for good vision at intermediate distances. The term “near vision” generally corresponds to vision provided when objects are at a distance from the subject eye at equal; or less than 1.5 feet. The term “distant vision” generally corresponds to vision provided when objects are at a distance of at least about 5-6 feet or greater. The term “intermediate vision” corresponds to vision provided when objects are at a distance of about 1.5 feet to about 5-6 feet from the subject eye. Such characterizations of near, intermediate, and far vision correspond to those addressed in Morlock R, Wirth R J, Tally S R, Garufis C, Heichel C W D, Patient-Reported Spectacle Independence Questionnaire (PRSIQ): Development and Validation. Am J Ophthalmology 2017; 178:101-114.

There have been various attempts to address limitations associated with monofocal IOLs. For example, multifocal IOLs have been proposed that deliver, in principle, two foci, one near and one far, optionally with some degree of intermediate focus. Such multifocal, or bifocal, IOLs are intended to provide good vision at two distances, and include both refractive and diffractive multifocal IOLs. In some instances, a multifocal IOL intended to correct vision at two distances may provide a near (add) power of about 3.0 or 4.0 diopters.

Multifocal IOLs may, for example, rely on a diffractive optical surface to direct portions of the light energy toward differing focal distances, thereby allowing the patient to clearly see both near and far objects. Multifocal ophthalmic lenses (including contact lenses or the like) have also been proposed for treatment of presbyopia without removal of the natural crystalline lens. Diffractive optical surfaces, either monofocal or multifocal, may also be configured to provide reduced chromatic aberration.

Diffractive monofocal and multifocal lenses can make use of a material having a given refractive index and a surface curvature which provide a refractive power. Diffractive lenses have a diffractive profile which confers the lens with a diffractive power that contributes to the overall optical power of the lens. The diffractive profile is typically characterized by a number of diffractive zones. When used for ophthalmic lenses these zones are typically annular lens zones, or echelettes, spaced about the optical axis of the lens. Each echelette may be defined by an optical zone, a transition zone between the optical zone and an optical zone of an adjacent echelette, and an echelette geometry. The echelette geometry includes an inner and outer diameter and a shape or slope of the optical zone, a height or step height, and a shape of the transition zone. The surface area or diameter of the echelettes largely determines the diffractive power(s) of the lens and the step height of the transition between echelettes largely determines the light distribution between the different powers. Together, these echelettes form a diffractive profile.

A multifocal diffractive profile of the lens may be used to mitigate presbyopia by providing two or more optical powers; for example, one for near vision and one for far vision. The lenses may also take the form of an intraocular lens placed within the capsular bag of the eye, replacing the original lens, or placed in front of the natural crystalline lens. The lenses may also be in the form of a contact lens, most commonly a bifocal contact lens, or in any other form mentioned herein.

Although multifocal ophthalmic lenses lead to improved quality of vision for many patients, additional improvements would be beneficial. For example, some pseudophakic patients experience undesirable visual effects (dysphotopsia), e.g. glare or halos. Halos may arise when light from the unused focal image creates an out-of-focus image that is superimposed on the used focal image. For example, if light from a distant point source is imaged onto the retina by the distant focus of a bifocal IOL, the near focus of the IOL will simultaneously superimpose a defocused image on top of the image formed by the distant focus. This defocused image may manifest itself in the form of a ring of light surrounding the in-focus image, and is referred to as a halo. Another area of improvement revolves around the typical bifocality of multifocal lenses. While multifocal ophthalmic lenses typically provide adequate near and far vision, intermediate vision may be compromised.

A lens with an extended range of vision may thus provide certain patients the benefits of good vision at a range of distances, while having reduced or no dysphotopsia. Various techniques for extending the depth of focus of an IOL have been proposed. For example, some approaches are based on a bulls-eye refractive principle, and involve a central zone with a slightly increased power. Other techniques include an a sphere or include refractive zones with different refractive zonal powers.

Although certain proposed treatments may provide some benefit to patients in need thereof, further advances would be desirable. For example, it would be desirable to provide improved IOL systems and methods that confer enhanced image quality across a wide and extended range of foci without dysphotopsia. Embodiments of the present invention provide solutions that address the problems described above, and hence provide answers to at least some of these outstanding needs.

BRIEF SUMMARY

Embodiments herein described include ophthalmic lenses with a first surface and a second surface disposed about an optical axis, and a diffractive profile imposed on one of the first surface or the second surface. The diffractive profile may include a central zone, a peripheral zone, and an intermediate zone positioned between the central zone and the peripheral zone. The central zone may include a first set of three echelettes arranged around the optical axis, the first set having a profile in r-squared space. The intermediate zone may include a second set of three echelettes arranged around the optical axis, the second set having a profile in r-squared space that is different than the profile of the first set. The peripheral zone may include a third set of three echelettes arranged around the optical axis, the third set having a profile in r-squared space that is different than the profile of the first set and the profile of the second set, the third set being repeated in series on the peripheral zone.

Embodiments herein described include ophthalmic lenses with a first surface and a second surface disposed about an optical axis, and a diffractive profile imposed on one of the first surface or the second surface. The diffractive profile includes a central zone, a peripheral zone, and an intermediate zone positioned between the central zone and the peripheral zone. The central zone includes a first set of three echelettes arranged about the optical axis, the first set including a zero step height between two of the three echelettes of the first set. The intermediate zone includes a second set of three echelettes arranged about the optical axis. The peripheral zone includes a third set of three echelettes arranged about the optical axis, the third set including a zero step height between two of the three echelettes of the third set, the third set being repeated in series on the peripheral zone.

Embodiments herein described include ophthalmic lenses with a first surface and a second surface disposed about an optical axis, and a diffractive profile imposed on one of the first surface or the second surface. The diffractive profile includes a central zone and a peripheral zone. The central zone includes a first set of three echelettes arranged around the optical axis, the first set having a profile in r-squared space. The peripheral zone includes a second set of three echelettes arranged around the optical axis, the second set being repeated in series on the peripheral zone and having a profile in r-squared space that is different than the profile of the first set.

Embodiments herein described also include manufacturing systems for making an ophthalmic lens. Such manufacturing system can include an input that accepts an ophthalmic lens prescription for a patient eye. A first module is configured to generate a diffractive profile based on the ophthalmic lens prescription. The diffractive profile includes a central zone, a peripheral zone, and an intermediate zone positioned between the central zone and the peripheral zone. The central zone includes a first set of three echelettes arranged around an optical axis, the first set having a profile in r-squared space. The intermediate zone includes a second set of three echelettes arranged around the optical axis, the second set having a profile in r-squared space that is different than the profile of the first set. The peripheral zone includes a third set of three echelettes arranged around the optical axis, the third set having a profile in r-squared space that is different than the profile of the first set and the profile of the second set, the third set being repeated in series on the peripheral zone. The manufacturing system includes a manufacturing assembly that fabricates the ophthalmic lens based on the diffractive profile.

Embodiments herein described also include manufacturing systems for making an ophthalmic lens. Such manufacturing system can include an input that accepts an ophthalmic lens prescription for a patient eye. A first module is configured to generate a diffractive profile based on the ophthalmic lens prescription. The diffractive profile includes a central zone and a peripheral zone. The central zone includes a first set of three echelettes arranged around an optical axis, the first set having a profile in r-squared space. The peripheral zone includes a second set of three echelettes arranged around the optical axis, the second set being repeated in series on the peripheral zone and having a profile in r-squared space that is different than the profile of the first set. The manufacturing system includes a manufacturing assembly that fabricates the ophthalmic lens based on the diffractive profile.

Embodiments herein described also include methods of designing an intraocular lens. Such methods can include defining a diffractive profile and generating a diffractive lens surface based on the diffractive profile. The diffractive profile may include a central zone, a peripheral zone, and an intermediate zone positioned between the central zone and the peripheral zone. The central zone includes a first set of three echelettes arranged around the optical axis, the first set having a profile in r-squared space. The intermediate zone includes a second set of three echelettes arranged around the optical axis, the second set having a profile in r-squared space that is different than the profile of the first set. The peripheral zone includes a third set of three echelettes arranged around the optical axis, the third set having a profile in r-squared space that is different than the profile of the first set and the profile of the second set, the third set being repeated in series on the peripheral zone.

Embodiments herein described also include methods of designing an intraocular lens. Such methods can include defining a diffractive profile and generating a diffractive lens surface based on the diffractive profile. The diffractive profile may include a central zone and a peripheral zone. The central zone includes a first set of three echelettes arranged around an optical axis, the first set having a profile in r-squared space. The peripheral zone includes a second set of three echelettes arranged around the optical axis, the second set being repeated in series on the peripheral zone and having a profile in r-squared space that is different than the profile of the first set.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a cross-sectional view of an eye with an implanted multifocal refractive intraocular lens;

FIG. 1B illustrates a cross-sectional view of an eye having an implanted multifocal diffractive intraocular lens;

FIG. 2A illustrates a front view of a diffractive multifocal intraocular lens;

FIG. 2B illustrates a cross-sectional view of a diffractive multifocal intraocular lens;

FIGS. 3A-3B are graphical representations of a portion of the diffractive profile of a conventional diffractive multifocal lens;

FIG. 4 is a graphical representation illustrating a lens profile for a diffractive lens according to certain embodiments of this disclosure;

FIG. 5 is a graphical representation illustrating a lens profile for a diffractive lens according to certain embodiments of this disclosure;

FIG. 6 is a simplified block diagram illustrating a system for generating a diffractive lens surface, in accordance with embodiments;

FIG. 7 illustrates an example process for generating a diffractive lens surface; and

FIG. 8 illustrates an example computing environment for facilitating the systems and processes of FIGS. 6 and 7.

DETAILED DESCRIPTION

Contemporary Lens Shapes and Diffractive Profiles

FIGS. 1A, 1B, 2A, 2B, 3A and 3B illustrate multifocal IOL lens geometries, aspects of which are described in U.S. Patent Publication No. 2011-0149236 A1, which is hereby incorporated by reference in its entirety.

FIG. 1A is a cross-sectional view of an eye E fit with a multifocal IOL 11. As shown, multifocal IOL 11 may, for example, comprise a bifocal IOL. Multifocal IOL 11 receives light from at least a portion of cornea 12 at the front of eye E and is generally centered about the optical axis of eye E. For ease of reference and clarity, FIGS. 1A and 1B do not disclose the refractive properties of other parts of the eye, such as the corneal surfaces. Only the refractive and/or diffractive properties of the multifocal IOL 11 are illustrated.

Each major face of lens 11, including the anterior (front) surface and posterior (back) surface, generally has a refractive profile, e.g. biconvex, plano-convex, plano-concave, meniscus, etc. The two surfaces together, in relation to the properties of the surrounding aqueous humor, cornea, and other optical components of the overall optical system, define the effects of the lens 11 on the imaging performance by eye E. Conventional, monofocal IOLs have a refractive power based on the refractive index of the material from which the lens is made, and also on the curvature or shape of the front and rear surfaces or faces of the lens. One or more support elements may be configured to secure the lens 11 to a patient's eye.

Multifocal lenses may optionally also make special use of the refractive properties of the lens. Such lenses generally include different powers in different regions of the lens so as to mitigate the effects of presbyopia. For example, as shown in FIG. 1A, a perimeter region of refractive multifocal lens 11 may have a power which is suitable for viewing at far viewing distances. The same refractive multifocal lens 11 may also include an inner region having a higher surface curvature and a generally higher overall power (sometimes referred to as a positive add power) suitable for viewing at near distances.

Rather than relying entirely on the refractive properties of the lens, multifocal diffractive IOLs or contact lenses can also have a diffractive power, as illustrated by the IOL 18 shown in FIG. 1B. The diffractive power can, for example, comprise positive or negative power, and that diffractive power may be a significant (or even the primary) contributor to the overall optical power of the lens. The diffractive power is conferred by a plurality of concentric diffractive zones which form a diffractive profile. The diffractive profile may either be imposed on the anterior face or posterior face or both.

The diffractive profile of a diffractive multifocal lens directs incoming light into a number of diffraction orders. As light 13 enters from the front of the eye, the multifocal lens 18 directs light 13 to form a far field focus 15a on retina 16 for viewing distant objects and a near field focus 15b for viewing objects close to the eye. Depending on the distance from the source of light 13, the focus on retina 16 may be the near field focus 15b instead. Typically, far field focus 15a is associated with 0^th diffractive order and near field focus 15b is associated with the Pt diffractive order, although other orders may be used as well.

Bifocal ophthalmic lens 18 typically distributes the majority of light energy into two viewing orders, often with the goal of splitting imaging light energy about evenly (50%:50%), one viewing order corresponding to far vision and one viewing order corresponding to near vision, although typically, some fraction goes to non-viewing orders.

Corrective optics may be provided by phakic IOLs, which can be used to treat patients while leaving the natural lens in place. Phakic IOLs may be angle supported, iris supported, or sulcus supported. The phakic IOL can be placed over the natural crystalline lens or piggy-backed over another IOL. It is also envisioned that the present disclosure may be applied to inlays, onlays, accommodating IOLs, pseudophakic IOLs, other forms of intraocular implants, spectacles, and even laser vision correction.

FIGS. 2A and 2B show aspects of a conventional diffractive multifocal lens 20. Multifocal lens 20 may have certain optical properties that are generally similar to those of multifocal IOLs 11, 18 described above. Multifocal lens 20 has an anterior lens face 21 and a posterior lens face 22 disposed about optical axis 24.

When fitted onto the eye of a subject or patient, the optical axis of lens 20 is generally aligned with the optical axis of eye E. The curvature of lens 20 gives lens 20 an anterior refractive profile and a posterior refractive profile. Although a diffractive profile may also be imposed on either anterior face 21 and posterior face 22 or both, FIG. 2B shows posterior face 22 with a diffractive profile. The diffractive profile is characterized by a plurality of annular diffractive zones or echelettes 23 spaced about optical axis 24. While analytic al optics theory generally assumes an infinite number of echelettes, a standard multifocal diffractive IOL typically has at least 9 echelettes, and may have over 30 echelettes. For the sake of clarity, FIG. 2B shows only 4 echelettes. Typically, an IOL is biconvex, or possibly plano-convex, or convex-concave, although an IOL could be plano-plano, or other refractive surface combinations.

FIGS. 3A and 3B are graphical representations of a portion of a typical diffractive profile of a multifocal lens. While the graph shows only 3 echelettes, typical diffractive lenses extend to at least 9 echelettes to over 32 echelettes. In FIG. 3A, the height 32 of the surface relief profile (from a plane perpendicular to the light rays) of each point on the echelette surface is plotted against the square of the radial distance (r² or ρ) from the optical axis of the lens (referred to as r-squared space). In multifocal lenses, each echelette 23 may have a diameter or distance from the optical axis which is often proportional to √n, n being the number of the echelette 23 as counted from optical axis 24. Each echelette has a characteristic optical zone 30 and transition zone 31. Optical zone 30 typically has a shape or downward slope that is parabolic as shown in FIG. 3B. The slope of each echelette in r-squared space (shown in FIG. 3A), however, is the same. As for the typical diffractive multifocal lens, as shown here, all echelettes have the same surface area. The area of echelettes 23 determines the diffractive power of lens 20, and, as area and radii are correlated, the diffractive power is also related to the radii of the echelettes. The physical offset of the trailing edge of each echelette to the leading edge of the adjacent echelette is the step height. An exemplary step height between adjacent echelettes is marked as reference number 33 in FIG. 3A. The step heights remain the same in r-squared space (FIG. 3A) and in linear space (FIG. 3B). The step offset is the height offset of the transition zone from the underlying base curve. An exemplary step offset is marked as reference number 421 in FIG. 4.

Conventional multifocal diffractive lenses typically provide for near and far vision, neglecting visual performance at intermediate distances. Providing for an extended range of vision can help to improve the visual performance at intermediate distances. In addition, providing for a zero-step height between transition zones may reduce visual artifacts such as halos or glare that may otherwise be visible to a user due to one or more of the boundaries between the optical zones.

FIG. 4 shows a graphical representation illustrating an embodiment of a diffractive profile 400. The diffractive profile 400 may result in a lens having an extended range of vision or a multifocal lens.

The diffractive profile 400, in the form of a sag profile, is shown extending outward from an optical axis 402. The diffractive zones, or echelettes, are shown extending radially outward from the optical axis 402, and would be arranged around the optical axis 402 (the other half of the diffractive profile 400 is not shown). The diffractive profile 400 is shown relative to the Y axis 404, which represents the height or phase shift of the diffractive profile 400. The height is shown in units of micrometers, and may represent the distance from the base curve of the lens. In other embodiments, other units or scalings may be utilized.

The height or phase shift of the diffractive profile 400 is shown in relation to the radius on the X axis 406 from the optical axis 402. The radius is shown in units of millimeters, although in other embodiments, other units or scalings may be utilized. The diffractive profile 400 may extend outward from the optical axis 402 for a radius of 3.0 millimeters (diameter of 6.0 millimeters), although in other embodiments the diffractive profile 400 may extend for a lesser or greater radius.

The diffractive profile 400 includes three sets 408, 410, 412 of diffractive zones or echelettes. The three sets include a first set 408 positioned at a central zone 414 of the lens. The second set 410 is positioned at an intermediate zone 416 of the lens. The third set 412 is positioned at a peripheral zone 418 of the lens. The third set 412 may be repeated in series on the peripheral zone 418.

The first set 408 is adjacent the optical axis 402. The first set includes three diffractive zones or echelettes 420a, 420b, 420c. The echelettes 420a, 420b, 420c are connected by transition zones 422a, 422b. The separation between the different echelettes 420a, 420b, 420c, as well as the separation between the echelettes of the other sets 410, 412, is indicated by the dashed step number line 424.

The first set 408 has a profile defined by the shape or slope of the echelettes 420a, 420b, 420c, and the step height and step offsets (as discussed previously) at the transition zones 422a, 422b, and the height of the first echelette 420a at the optical axis 402, and the height of the trailing end of echelette 420c at the transition zone 426. The first echelette 420a of the first set 408 has a negative slope extending from its leading end to its trailing edge or end at the transition zone 422a. The trailing end has a height corresponding to the step offset at the transition zone 422a. The leading end of the second echelette 420b is separated from the trailing end of the first echelette 420a by the step height corresponding to the transition zone 422a.

The second echelette 420b extends from its leading end to the trailing end at transition zone 422b and has a negative slope. The slope of the second echelette 420b may b e different than the slope of the first echelette 420a. The trailing end of the second echelette 420b has a height corresponding to the step offset at the transition zone 422b. The step offset at the transition zone 422b is less than the step offset at the transition zone 422a. The second echelette 420b continuously joins with the third echelette 420c at a zero step height. Thus, there is no step height at the transition zone 422b. The radius of curvature of the profile at the transition zone 422b changes however. The zero step height, in any of the sets of echelettes, may reduce visual artifacts such as halos or glare that may otherwise be visible to a user due to one or more of the boundaries between the optical zones.

The third echelette 420c of the first set 408 has a leading end connected to the second echelette 420b at the transition zone 422b. The third echelette 420c has a negative slope, which may be different than the slope of the second echelette 420b and the first echelette 420a. The third echelette 420c extends to its trailing end at the transition zone 426 between the first set 408 and the second set 410. The third echelette 420c may have a zero step offset at the transition zone 426.

Using the scaling shown in FIG. 4, the first set 408, and the central zone 414, may end at the radial distance of about 0.9 millimeters.

The profiles of each of the echelettes 420a, 420b, 420c, are different from each other. The different profiles are due to the differing step heights, step offsets, and slopes of each echelette 420a, 420b, 420c. In r-squared space (discussed previously), the profiles of the echelettes 420a, 420b, 420c, are different from each other, due to the differing step heights, step offsets, and slopes of each echelette 420a, 420b, 420c.

The second set 410 of echelettes may be adjacent the first set 408 of echelettes. The second set 410 includes three diffractive zones or echelettes 428a, 428b, 428c. The echelettes 428a, 428b, 428c are connected by transition zones 430a, 430b.

The second set 410 has a profile defined by the shape or slope of the echelettes 428a, 428b, 428c, and the step height and step offsets at the transition zones 430a, 430b, 426, and the height of the trailing end of echelette 428c at the transition zone 432. The first echelette 428a of the second set 410 connects to the first set 408 at the transition zone 426. The transition zone 426 has a step height that is larger than any of the step heights of the first set 408. The first echelette 428a has a negative slope extending from its leading end to its trailing end at the transition zone 430a. The trailing end has a height corresponding to the step offset at the transition zone 430a. The leading end of the second echelette 428b is separated from the trailing end of the first echelette 428a by the step height corresponding to the transition zone 430a. The step height of the transition zone 430a is less than the step height of the transition zone 426.

The second echelette 428b extends from its leading end to the trailing end at transition zone 430b and has a negative slope. The slope of the second echelette 428b may be different than the slope of the first echelette 428a. The trailing end of the second echelette 428b has a height corresponding to the step offset at the transition zone 430b. The step offset at the transition zone 430b is less than the step offset at the transition zone 430a.

The third echelette 428c of the second set 410 has a leading end connected to the second echelette 428b at the transition zone 430b. The step height of the transition zone 430b may be less than the step height of the transition zones 430a and 426. The third echelette 428c has a negative slope, which may be different than the slope of the first echelette 428a and the second echelette 428b. The third echelette 428c extends to its trailing end at the transition zone 432 between the second set 410 and the third set 412. The third echelette 428c may have a zero step offset at the transition zone 432. A non-zero step height may be between each of the echelettes of the second set 410.

Using the scaling shown in FIG. 4, the second set 410, and the intermediate zone 416, may end at the radial distance of about 1.35 millimeters.

The profiles of each of the echelettes 428a, 428b, 428c, are different from each other. The different profiles are due to the differing step heights, step offsets, and slopes of each echelette 428a, 428b, 428c. In r-squared space, the profiles of the echelettes 428a, 428b, 428c, are different from each other, due to the differing step heights, step offsets, and slopes of each echelette 428a, 428b, 428c.

The profile of the second set 410 is different than the profile of the first set 408. The different profiles are due to the differing step heights, step offsets, and slopes of the echelettes within the respective set 408, 410. In r-squared space, the profile of the second set 410 is different than the profile of the first set 408 due to the differing step heights, step offsets, and slopes of the echelettes within the respective set 408, 410.

The third set 412 of echelettes may be adjacent the second set 410 of echelettes. The third set 412 includes three diffractive zones or echelettes 434a, 434b, 434c. The echelettes 434a, 434b, 434c are connected by transition zones 436a, 436b.

The third set 412 has a profile defined by the shape or slope of the echelettes 434a, 434b, 434c, and the step height and step offsets at the transition zones 436a, 436b, 432, and the height of the trailing end of echelette 434c at the transition zone to the next adjacent set. The first echelette 434a of the third set 412 connects to the second set 410 at the transition zone 432. The transition zone 432 has a step height that is smaller than the step height of the transition zone 426 and larger than the step heights of the transition zones 422a, 430a, 430b. The first echelette 434a has a negative slope extending from its leading end to its trailing end at the transition zone 436a. The trailing end has a height corresponding to the step offset at the transition zone 436a. The step offset at the transition zone 436a is smaller than the step offsets of any of the first set 408 or second set 410.

The leading end of the second echelette 434b is separated from the trailing end of the first echelette 434a by the step height corresponding to the transition zone 436a. The step height of the transition zone 436a is less than the step height of the transition zone 426 and greater than the step height of the transition zones 422a, 430a, 430b.

The second echelette 434b extends from its leading end to the trailing end at transition zone 436b and has a negative slope. The slope of the second echelette 434b may b e different than the slope of the first echelette 434a. The trailing end of the second echelette 434b has a height corresponding to the step offset at the transition zone 436b. The step offset at the transition zone 436b is greater than the step offset at the transition zone 436a and transition zones 422b and 430b.

The third echelette 434c continuously joins with the second echelette 434b at a zero step height. Thus, there is no step height at the transition zone 436b. The radius of curvature of the profile at the transition zone 436b changes however.

The third echelette 434c of the third set 412 has a leading end connected to the second echelette 434b at the transition zone 436b. The third echelette 434c has a negative slope, which may be different than the slope of the second echelette 436b and the first echelette 434a. The third echelette 436c extends to its trailing end at the trailing end of the third set 412, and may have a zero step offset at the trailing end of the third set 412.

The profiles of each of the echelettes 434a, 434b, 434c, are different from each other. The different profiles are due to the differing step heights, step offsets, and slopes of each echelette 434a, 434b, 434c. In r-squared space, the profiles of the echelettes 434a, 434b, 434c, are different from each other, due to the differing step heights, step offsets, and slopes of each echelette 434a, 434b, 434c.

The profile of the third set 412 is different than the profile of the first set 408 and the profile of the second set 410. The different profiles are due to the differing step heights, step offsets, and slopes of the echelettes within the respective set 408, 410, 412. In r-squared space, the profile of the third set 412 is different than the profile of the first set 408 and the second set 410 due to the differing step heights, step offsets, and slopes of the echelettes within the respective set 408, 410, 412.

The third set 412 may be repeated in series on the peripheral zone 418 to form a repeated set 438. The repeated third set 412 may be scaled in radial size relative to the r-squared distance from the optical axis 402, as is known in the art. Thus, the step heights and step offsets of each set in the repeated set will remain the same, as well as the surface area of each echelette of the set. The slope of the echelettes of each set in the repeated set will remain the same in r-squared space. As such, the profile of each repeated third set 412 remains the same in r-squared space.

The repeated set 438 may include a series of eight third sets 412, as shown in FIG. 4. In other embodiments, greater or fewer numbers of third sets 412 may be utilized in the repeated set 438. In one embodiment, the repeated set 438 may span the entirety of the remaining portion of the lens such that the entirety of the remaining optical zone is filled (may extend out to a full 6 millimeter diameter). In other embodiments, the repeated set 438 may span only a portion of the lens.

The profile of each of the first nine echelettes 420a, 420b, 420c, 428a, 428b, 428c, 434a, 434b, 434c, of the diffractive profile 400, have different profiles from each other. The different profiles are due to the differing step heights, step offsets, and slopes of each of the first nine echelettes. In r-squared space, the profile of each of the first nine echelettes 420a, 420b, 420c, 428a, 428b, 428c, 434a, 434b, 434c are different from each other due to the differing step heights, step offsets, and slopes of each of the echelettes.

The surface area of the first echelette (420a, 428a, 434a) of each of the respective first, second, and third sets (408, 410, 412) is the same. The surface area of the second echelette (420b, 428b, 434b) of each of the respective first, second, and third sets (408, 410, 412) is the same. The surface area of the third echelette (420c, 428c, 434c) of each of the respective first, second, and third sets (408, 410, 412) is the same. As is apparent from FIG. 4, however the step heights and step offsets of the echelettes in the sets (408, 410, 412) differ. All echelettes shown in FIG. 4 have the same surface area.

The three echelettes 420a, 420b, 420c of the first set 408 do not repeat. If the echelettes 420a, 420b, 420c of the first set 408 were to repeat, then the optical characteristics may be defined by at least four diffractive orders corresponding to at least four diffractive powers. The repeated first set 408 may produce four diffractive orders that are useful for a patient's vision, corresponding to four diffractive powers that are useful for a patient's vision. The diffractive orders may include a 0^th order and orders 1^st through 8^th. The orders 2^nd through 5^th may be useful for a patient's vision. The 0^th and 1^st orders may be hyperopic (beyond far), and the 6^th, 7^th, and 8^th, may be on the myopic side.

If the first set 408 were to repeat, the repeated first set 408 may distribute light to diffractive orders, with the following light distribution of incident light to each of the four diffractive orders, and the diffractive power shown in Table 1 below:

	TABLE 1
	Diffractive	Diffractive	Light
	order	power	distribution
	2nd	2.5 D (Far)	37%
	3rd	3.75 D (1.25D add)	12%
	4th	5.0 D (2.5D add)	18%
	5th	6.25 D (3.75D add)	16%

The three echelettes 428a, 428b, 428c of the second set 410 do not repeat. If the echelettes 428a, 428b, 428c of the second set 410 were to repeat, then the optical characteristics may be defined by at least four diffractive orders corresponding to at least four diffractive powers. The repeated second set 410 may produce four diffractive orders that are useful for a patient's vision, corresponding to four diffractive powers that are useful for a patient's vision. The diffractive orders may include a 0^th order and orders Pt through 8^th. The orders 2^nd through 5^th may be useful for a patient's vision. The 0^th and 1^st orders may be hyperopic (beyond far), and the 6^th, 7^th, and 8^th, may be on the myopic side.

If the second set 410 were to repeat, the repeated second set 410 may distribute light to four diffractive orders, with the following light distribution of incident light to each of the four diffractive orders, and the diffractive power shown in Table 2 below:

	TABLE 2
	Diffractive	Diffractive	Light
	order	power	distribution
	2nd	2.5 D (Far)	45%
	3rd	3.75 D (1.25D add)	1%
	4th	5.0 D (2.5D add)	1%
	5th	6.25 D (3.75D add)	25%

As noted in Table 2, the light distribution to the 3^rd and 4^th diffractive order is relatively low, such that a repeated second set 410 may be considered to operate similar to a bifocal diffractive profile.

The three echelettes 434a, 434b, 434c of the third set 412 do repeat. The optical characteristics of the repeated set 438 may be defined by at least four diffractive orders corresponding to at least four diffractive powers. The repeated set 438 may produce four diffractive orders that are useful for a patient's vision, corresponding to four diffractive powers that are useful for a patient's vision. The diffractive orders may include a 0^th order and orders 1^st through 8^th. The orders 2nd through 5^th may be useful for a patient's vision. The 0^th and 1^st orders may be hyperopic (beyond far), and the 6^th, 7^th, and 8^th, may be on the myopic side.

The repeated set 438 may distribute light to four diffractive orders, with the following light distribution of incident light to each of the four diffractive orders, and the diffractive power shown in Table 3 below:

	TABLE 3
	Diffractive	Diffractive	Light
	order	power	distribution
	2nd	2.5 D (Far)	48%
	3rd	3.75 D (1.25D add)	7%
	4th	5.0 D (2.5D add)	5%
	5th	6.25 D (3.75D add)	15%

As noted in Table 3, the light distribution to the 3^rd and 4^th diffractive order is relatively low, such that the repeated set 438 may be considered to operate similar to a bifocal diffractive profile. The light distribution of the repeated set 438 may include more than 40% of incident light distributed toward a first diffractive power, less than 10% of incident light distributed toward a second diffractive power, less than 10% of incident light distributed toward a third diffractive power, and more than 10% of incident light distributed toward a fourth diffractive power. The second diffractive power may be between about 0.58 and 1.5 diopter, the third diffractive power may be between about 1.17 and 3 diopter, and the fourth diffractive power may be between about 1.75 and 4.5 diopter.

The diffractive powers and light distributions listed in each of Tables 1, 2, and 3 may vary to an amount that is “about” the listed amount. In other embodiments, the diffractive orders, powers and light distributions, listed in each of Tables 1, 2, and 3 may be varied as desired.

The diffractive powers of the lens may vary, depending on the desired performance of the design. The diffractive powers as listed in Tables 1-3 are intended for a design that provides adequate visual performance over the entire range of vision from far to intermediate distances and near. Lower diffractive powers may be beneficial if the desired performance is to emphasize good far and intermediate vision, while vision at near distances may be slightly reduced. Such lens design may have a second diffractive add power of 0.58 D, a third diffractive add power of 1.17 D and a fourth diffractive add power of 1.75 D. Some embodiments have diffractive add powers in-between these and those in Tables 1-3.

The combination of the non-repeating first set 408, second set 410, and the repeated set 438, may result in a diffractive profile producing an extended range of vision for the patient.

In one embodiment, the diffractive profile 400 may be positioned on a surface of a lens that is opposite an aspheric surface. The aspheric surface on the opposite side of the lens may be designed to reduce corneal spherical aberration of the patient.

In one embodiment, one or both surfaces of the lens may be aspherical, or include a refractive surface designed to extend the depth of focus, or create multifocality.

In one embodiment, a refractive zone on one or both surfaces of the lens may be utilized that may be the same size or different in size as one of the diffractive zones. The refractive zone includes a refractive surface designed to extend the depth of focus, or create multifocality.

FIG. 5 shows a graphical representation illustrating an embodiment of a diffractive profile 500. The diffractive profile 500 may result in a lens having an extended range of vision or a multifocal lens.

The diffractive profile 500 is configured similarly as the diffractive profile 400 shown in FIG. 4. However, the diffractive profile 500 includes a second set 510 of echelettes in an intermediate zone 516 that has a profile in r-squared space that is substantially identical to the profile of a first set 508 of echelettes in r-squared space.

Similar to the diffractive profile 400 shown in FIG. 4, the diffractive profile 500 is shown extending outward from an optical axis 502. The diffractive profile 500 is shown relative to the Y axis 504, which represents the height or phase shift of the diffractive profile 500, and is shown in units of micrometers, and may represent the distance from the base curve of the lens.

The height or phase shift of the diffractive profile 500 is shown in relation to the radius on the X axis 506 from the optical axis 502.

The diffractive profile 500 includes three sets 508, 510, 512 of diffractive zones or echelettes. The three sets include a first set 508 positioned at a central zone 514 of the lens. The second set 510 is positioned at an intermediate zone 516 of the lens. The third set 512 is positioned at a peripheral zone 518 of the lens. The third set 512 may be repeated in series on the peripheral zone 518.

The first set 508 may include three diffractive zones or echelettes 520a, 520b, 520c, which may be connected by transition zones 522a, 522b. The separation between the different echelettes 520a, 520b, 520c, as well as the separation between the echelettes of the other sets 510, 512, is indicated by the dashed step number line 524. The reference number 521 represents the step offset at the transition zone 522a.

The profile of the first set 508 may be the same as the profile of the first set 408 shown in FIG. 4. The properties of the first set 508 may be the same as the properties of the first set 408 shown in FIG. 4.

The second set 510 may include three diffractive zones or echelettes 528a, 528b, 528c, which may be connected by transition zones 530a, 530b. The second set 510 may be adjacent to the first set 508 and may be connected to the first set 508 with transition zone 526. The profile of the second set 510 in r-squared space is substantially identical to the profile of a first set 508 of echelettes in r-squared space. The step heights and offsets at transition zones 530a and 530b may be the substantially identical to those of respective transition zones 522a and 522b, and the slopes of the echelettes 528a, 528b, 528c may be substantially identical to those of the echelettes 520a, 520b, 520c.

The third set 512 may include three diffractive zones or echelettes 534a, 534b, 534c, which may be connected by transition zones 536a, 536b. The third set 512 may be adjacent the second set 510 and may be connected to the second set 510 with transition zone 532.

The profile of the third set 512 may be the same as the profile of the third set 412 shown in FIG. 4.

The third set 512 may be repeated in series on the peripheral zone 518 to form a repeated set 538, similar to the repeated third set 412 shown in FIG. 4. The properties of the third set 512 and the repeated set 538 may be the same as the respective third set 412 and repeated third set 438 of FIG. 4.

In one embodiment, the second set 510 may be excluded, such that only echelettes on a central zone and echelettes on a peripheral zone may be utilized in a diffractive profile. The echelettes on the central zone may be adjacent the echelettes on the peripheral zone.

In one embodiment, a diffractive profile may be configured such that the second set of echelettes in the intermediate zone has a profile that is the same as the second set 410 of echelettes shown in FIG. 4, and a first set of echelettes in a central zone has a profile in r-squared space that is substantially identical to the profile in r-squared space as the second set 410 of echelettes shown in FIG. 4.

The diffractive profiles disclosed herein may produce an extended range of vision for the patient.

The embodiments of diffractive profiles disclosed herein may be positioned on a surface of a lens that is opposite an aspheric surface. The aspheric surface on the opposite side of the lens may be designed to reduce corneal spherical aberration of the patient.

The embodiments of diffractive profiles disclosed herein may be utilized with one or both surfaces of the lens that may be aspherical, or include a refractive surface designed to extend the depth of focus, or create multifocality.

The embodiments of diffractive profiles disclosed herein may be utilized with a refractive zone on one or both surfaces of the lens that may be the same size or different in size as one of the diffractive zones. The refractive zone includes a refractive surface designed to extend the depth of focus, or create multifocality.

Any of the embodiments of lens profiles discussed herein may be a podized to produce a desired result. The apodization may result in the step heights and step offsets of the repeated sets being varied according to the apodization. The sets, however, are still considered to be repeating sets over the optic of the lens.

A zero step height may be positioned as desired between adjacent echelettes. For example, either echelette of a set of echelettes (e.g., two of three echelettes of a set), or all echelettes of a set of echelettes may have a zero step height. In one embodiment, adjacent sets of echelettes may have a zero step height.

Systems and Methods for Determining Lens Shape:

FIG. 6 is a simplified block diagram illustrating a system 600 for generating an ophthalmic lens based on a user input.

The system 600 includes a user input module 602 configured to receive user input defining aspects of the user and of a lens. The input may accept an ophthalmic lens prescription for a patient eye. Aspects of a lens may include an extended range of vision prescription, anatomical dimensions like a pupil size performance, and lens dimensions, among other attributes. An extended range of vision prescription can include, for example, a preferred optical power or optical power profile for correcting far vision and an optical power or optical p ower profile for near vision. In some cases, an extended range of vision prescription can further include an optical power or optical power profile for correcting intermediate vision at two, or in some cases more than two intermediate foci, which may fall between the optical powers or ranges of optical powers described above. A pupil size performance can include a pupil radius of a patient and the visual field to be optimized. These parameters can also be related to patient's life style or profession, so that the design incorporates patient's visual needs as a function of the pupil size. Lens dimensions can include a preferred radius of the total lens, and may further include preferred thickness, or a preferred curvature of one or the other of the anterior surface and posterior surface of the lens.

A multizonal diffractive surface modeling module 604 can receive information about the desired lens from the user input module 602, and can determine aspects of a multizonal lens. The multizonal diffractive surface modeling module 604 may generate a diffractive profile based on the ophthalmic lens prescription. For example, the modeling module 604 can determine the shape of one or more echelettes of the diffractive profile of a diffractive multifocal lens, including the positioning, width, step height, and curvature needed to fulfill the multifocal prescription for each subset of the echelettes, as well as the positioning of each subset of echelettes. The multizonal diffractive surface modeling module 604 can further determine the shapes of transition steps between echelettes. For example, transition steps may be smoothed or rounded to help mitigate optical aberrations caused by light passing through an abrupt transition. Such transition zone smoothing, which may be referred to as a low scatter profile, can provide for reductions in dysphotopsia by reducing the errant concentration of incident light behind the lens by the transition zones. By way of further example, echelette ordering, echelette offsets, and echelette boundaries may be adjusted to adjust the step heights between some adjacent echelettes. In particular, the multizonal diffractive surface modeling module can determine echelette offsets to set one or more step heights at echelette transitions to zero, or approximately zero, by these or similar methods. The generated diffractive profile may be any of the diffractive profiles disclosed in this application.

The multizonal diffractive surface modeling module 604 can be configured to generate performance criteria 612, e.g. via modeling optical properties in a virtual environment. Performance criteria can include the match of the optical power profile of the multizonal lens with the desired optical power profile based on the extended range of vision prescription. The performance criteria can also include the severity of diffractive aberrations caused by lens surface. In some cases, the multizonal surface modeling module 604 can provide a lens surface to a lens fabrication module for facilitating the production of a physical lens, which can be tested via a lens testing module 610 for empirically determining the performance criteria 612, so as to identify optical aberrations and imperfections not readily discerned via virtual modeling, and to permit iteration. The lens fabrication module may comprise a manufacturing assembly that may fabricate the ophthalmic lens based on the diffractive profile.

A refractive surface modeling module 606 can receive information from the user input 602 and multizonal surface modeling modules 604 in order to determine refractive aspects of the lens. For example, provided with an extended range of vision prescription and a set of diffractive powers that can be generated by a diffractive profile, the refractive surface modeling module 606 can provide a refractive geometry configured to provide a base power which, when combined with the diffractive surface, meets the requirements of the extended range of vision prescription. The refractive surface modeling module 606 can also generate performance criteria 612, and can contribute to providing a lens surface to a lens fabrication module 608 for facilitating the production of the physical lens.

FIG. 7 is an example process 700 for generating a diffractive lens surface, in accordance with embodiments. The process 700 may be implemented in conjunction with, for example, the system 600 shown in FIG. 6. Some or all of the process 700 (or any other processes described herein, or variations, and/or combinations thereof) may be performed under the control of one or more computer systems configured with executable instructions and may be implemented as code (e.g., executable instructions, one or more computer programs, or one or more applications) executing collectively on one or more processors, by hardware or combinations thereof. The code may be stored on a computer-readable storage medium, for example, in the form of a computer program comprising a plurality of instructions executable by one or more processors. The computer-readable storage medium may be non-transitory.

The process 700 may include a method of designing an intraocular lens and may include receiving an input of an ophthalmic lens prescription for a patient eye, which may b e an extended range of vision lens prescription (act 702). The input can include, e.g., a desired optical power profile for correcting impaired distance vision, a desired optical power profile for correcting impaired intermediate distance vision, a desired optical power profile for accommodating near vision, and any suitable combination of the above. Based on a desired optical power profile, a diffractive profile can be defined and generated including a central zone, a peripheral zone, and an intermediate zone positioned between the central zone and the peripheral zone. The generated diffractive profile may include a central zone including a first set of three echelettes arranged around the optical axis, the first set having a profile in r-squared space (act 704). The generated diffractive profile may include an intermediate zone including a second set of three echelettes arranged around the optical axis, the second set having a profile in r-squared space that is different than the profile of the first set (act 706). The generated diffractive profile may include a peripheral zone including a third set of three echelettes arranged around the optical axis, the third set having a profile in r-squared space that is different than the profile of the first set and the profile of the second set, the third set being repeated in series on the peripheral zone (act 708).

In one embodiment, a diffractive profile may be generated and utilized that includes a central zone and a peripheral zone. The central zone may include a first set of three echelettes arranged around the optical axis, the first set having a profile in r-squared space. The peripheral zone may include a second set of three echelettes arranged around the optical axis, the second set having a profile in r-squared space that is different than the profile of the first set. The second set may be repeated in series on the peripheral zone.

In one embodiment, the diffractive profile may include an intermediate zone positioned between the central zone and the peripheral zone. The intermediate zone may include a third set of three echelettes arranged around the optical axis, the third set having a profile in r-squared spaced that is substantially identical to the profile of the first set (in the central zone).

The diffractive lens profile of the multizonal diffractive lens surface may be used in combination with a known refractive base power. To that end, a refractive lens surface may b e generated having a base power that, in combination with the diffractive lens surface generated based on the diffractive profile, meets the extended range of vision lens prescription (act 710). A total lens surface can be generated based on both the refractive lens surface and the diffractive lens surface (act 712). The refractive lens surface can include a refractive lens curvature on the anterior surface of the lens, the posterior surface of the lens, or both. Instructions can be generated to fabricate an intraocular lens based on the generated total lens surface (act 714). A manufacturing assembly may fabricate the ophthalmic lens based on the instructions. The methods herein are not limited to the examples of diffractive profiles discussed here, and may extend to any of the diffractive lens profiles and ophthalmic lenses disclosed in this application.

Computational Methods:

FIG. 8 is a simplified block diagram of an exemplary computing environment 800 that may be used by systems for generating the diffractive profiles and ophthalmic lenses of the present disclosure. Computer system 822 typically includes at least one processor 852 which may communicate with a number of peripheral devices via a bus subsystem 854. These peripheral devices may include a storage subsystem 856 comprising a memory sub system 858 and a file storage subsystem 860, user interface input devices 862, user interface output devices 864, and a network interface subsystem 866. Network interface subsystem 866 provides an interface to outside networks 868 and/or other devices, such as the lens fabrication module 608 or lens testing module 610 of FIG. 6.

User interface input devices 862 may include a keyboard, pointing devices such as a mouse, trackball, touch pad, or graphics tablet, a scanner, foot pedals, a joystick, a touchscreen incorporated into the display, audio input devices such as voice recognition systems, microphones, and other types of input devices. User input devices 862 will often be used to download a computer executable code from a tangible storage media embodying any of the methods of the present disclosure. In general, use of the term “input device” is intended to include a variety of conventional and proprietary devices and ways to input information into computer system 822.

User interface output devices 864 may include a display subsystem, a printer, a fax machine, or non-visual displays such as audio output devices. The display subsystem may b e a cathode ray tube (CRT), a flat-panel device such as a liquid crystal display (LCD), a projection device, or the like. The display subsystem may also provide a non-visual display such as via audio output devices. In general, use of the term “output device” is intended to include a variety of conventional and proprietary devices and ways to output information from computer system 822 to a user.

Storage subsystem 856 can store the basic programming and data constructs that provide the functionality of the various embodiments of the present disclosure. For example, a database and modules implementing the functionality of the methods of the present disclosure, as described herein, may be stored in storage subsystem 856. These software modules are generally executed by processor 852. In a distributed environment, the software modules may be stored on a plurality of computer systems and executed by processors of the plurality of computer systems. Storage subsystem 856 typically comprises memory subsystem 858 and file storage subsystem 860. Memory subsystem 858 typically includes a number of memories including a main random access memory (RAM) 870 for storage of instructions and data during program execution and/or a read only member (ROM) 882.

Various computational methods discussed above, e.g. with respect to generating a multizonal lens surface, may be performed in conjunction with or using a computer or other processor having hardware, software, and/or firmware. The various method steps may be performed by modules, and the modules may comprise any of a wide variety of digital and/or analog data processing hardware and/or software arranged to perform the method steps described herein. The modules optionally comprising data processing hardware adapted to perform one or more of these steps by having appropriate machine programming code associated therewith, the modules for two or more steps (or portions of two or more steps) being integrated into a single processor board or separated into different processor boards in any of a wide variety of integrated and/or distributed processing architectures. These methods and systems will often employ a tangible media embodying machine-readable code with instructions for performing the method steps described above. Suitable tangible media may comprise a memory (including a volatile memory and/or a non-volatile memory), a storage media (such as a magnetic recording on a floppy disk, a hard disk, a tape, or the like; on an optical memory such as a CD, a CD-R/W, a CD-ROM, a DVD, or the like; or any other digital or analog storage media), or the like.

Claims

1. An ophthalmic lens comprising: a first surface and a second surface disposed about an optical axis; anda diffractive profile imposed on one of the first surface or the second surface, the diffractive profile including a central zone, a peripheral zone, and an intermediate zone positioned between the central zone and the peripheral zone, wherein: the central zone includes a first set of three diffractive echelettes arranged about the optical axis, the first set including a zero step height between two of the three diffractive echelettes of the first set;the intermediate zone includes a second set of three diffractive echelettes arranged about the optical axis; andthe peripheral zone includes a third set of three diffractive echelettes arranged about the optical axis, the third set including a zero step height between two of the three diffractive echelettes of the third set, the third set being repeated in series on the peripheral zone.

2. The lens of claim 1, wherein the third set has a profile in r-squared space, and the first set has a profile in r-squared space that is different than the profile of the third set.

3. The lens of claim 1, wherein the third set being repeated in series on the peripheral zone forms a repeated set that is configured to result in a light distribution of about 48% of incident light toward a first diffractive power, about 7% of incident light toward a second diffractive power, about 5% of incident light toward a third diffractive power, and about 15% of incident light toward a fourth diffractive power.

4. The lens of claim 3, wherein the second diffractive power is about 1.25 diopter, the third diffractive power is about 2.5 diopter, and the fourth diffractive power about 3.75 diopter.

5. The lens of claim 1, wherein the three echelettes of the first set include a first echelette, a second echelette, and a third echelette, with the third echelette being positioned radially outward from the first echelette, and the second echelette being positioned between the first echelette and the third echelette, and the zero step height being between the second echelette and the third echelette.

6. The lens of claim 5, wherein a non-zero step height is between the first echelette and the second echelette.

7. The lens of claim 1, wherein a non-zero step height is between each of the echelettes of the second set.

8. The lens of claim 1, wherein the three echelettes of the third set include a first echelette, a second echelette, and a third echelette, with the third echelette being positioned radially outward from the first echelette, and the second echelette being positioned between the first echelette and the third echelette, and the zero step height being between the second echelette and the third echelette.

9. The lens of claim 8, wherein a non-zero step height is between the first echelette and the second echelette.

10. The lens of claim 1, wherein each of the three echelettes of the second set have a different profile than each other in r-squared space.