Patent Description:
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 <NUM> years. By the age of <NUM> years, the crystalline lens has often lost almost all elastic properties and has only 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".

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 diffractive 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 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 be in the form of a contact lens, most commonly a bifocal contact lens, or in any other form mentioned herein.

Multifocal (e.g. diffractive) intraocular lenses (IOLs) are intended to provide a patient with improved vision at different distances, such as near, intermediate and far. The near vision may generally correspond to vision provided when objects are at a distance of equal or less than <NUM> feet from a subject eye. Intermediate vision may generally correspond to vision for objects at a distance between about <NUM> feet and about <NUM>-<NUM> feet from a subject eye. Far vision may generally correspond to vision for objects at any distance greater than about <NUM>-<NUM> feet from a subject eye. Such characterizations of near, intermediate, and far vision correspond to those addressed in <NPL>.

Since multifocal IOLs provide multiple focal lengths, the focused image on the retina originating from the focal length that corresponds to the particular viewing distance is overlapping with unfocused images originating from the other focal lengths. This can create visual artifacts for the patient. Also, the transitions between echelettes in a diffractive multifocal may cause glare, halo, or similar visual artifacts; and the severity of said artifacts may increase with an increased number of echelettes. Furthermore, conventional approaches typically provide for near and far vision, but achieve unsatisfactory visual performance at intermediate distances. Relatedly, increasing the number of focal lengths in an IOL can exacerbate the aforementioned visual artifacts. Therefore, multifocal conventional ophthalmic approaches may fail to adequately improve visual performance at intermediate distances.

Intraocular lenses and methods for designing and manufacturing intraocular lenses are konwn from the documents <CIT> and <CIT>.

The present invention relates to a manufacturing system (<NUM>) for making an ophthalmic intraocular lens and a method for designing an intraocular lens, the intraocular lens having a first surface and a second surface disposed about an optical axis, the method comprising: defining a diffractive profile (<NUM>) including: a repetitive pattern of three echelettes (<NUM>, <NUM>, <NUM>) with transition zones (<NUM>, <NUM>) bounding each respective echelette (<NUM>, <NUM>, <NUM>), wherein each echelette has a maximum profile height expressed as a sum of a step height and a step offset, the step offset being defined as the height offset of the transition zone from an underlying base curve, and at least one of the three echelettes (<NUM>, <NUM>, <NUM>) in the repetitive pattern is connected to an adjacent echelette (<NUM>, <NUM>, <NUM>) by a step height of zero by matching a step offset of the adjacent echelette with the maximum height of the at least one echelette; and generating a diffractive lens surface based on the diffractive profile (<NUM>).

<FIG>, <FIG> illustrate multifocal IOL lens geometries, aspects of which are described in <CIT>, which is hereby incorporated by reference in its entirety.

<FIG> is a cross-sectional view of an eye E fit with a multifocal IOL <NUM>. As shown, multifocal IOL <NUM> may, for example, comprise a bifocal IOL. Multifocal IOL <NUM> receives light from at least a portion of cornea <NUM> at the front of eye E and is generally centered about the optical axis of eye E. For ease of reference and clarity, <FIG> 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 <NUM> are illustrated.

Each major face of lens <NUM>, 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 <NUM> 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 <NUM> 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>, a perimeter region of refractive multifocal lens <NUM> may have a power which is suitable for viewing at far viewing distances. The same refractive multifocal lens <NUM> 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 <NUM> shown in <FIG>. 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 enters from the front of the eye, the multifocal lens <NUM> directs light to form a far field focus 15a on retina 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 <NUM>, the focus on retina <NUM> may be the near field focus 15b instead. Typically, far field focus 15a is associated with <NUM>th diffractive order and near field focus 15b is associated with the <NUM>st diffractive order, although other orders may be used as well.

Bifocal ophthalmic lens <NUM> typically distributes the majority of light energy into two viewing orders, often with the goal of splitting imaging light energy about evenly (<NUM>%:<NUM>%), 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.

<FIG> show aspects of a conventional diffractive multifocal lens <NUM>. Multifocal lens <NUM> may have certain optical properties that are generally similar to those of multifocal IOLs <NUM>, <NUM> described above. Multifocal lens <NUM> has an anterior lens face <NUM> and a posterior lens face <NUM> disposed about optical axis <NUM>.

When fitted onto the eye of a subject or patient, the optical axis of lens <NUM> is generally aligned with the optical axis of eye E. The curvature of lens <NUM> gives lens <NUM> an anterior refractive profile and a posterior refractive profile. Although a diffractive profile may also be imposed on either anterior face <NUM> and posterior face <NUM> or both, <FIG> shows posterior face <NUM> with a diffractive profile. The diffractive profile is characterized by a plurality of annular diffractive zones or echelettes <NUM> spaced about optical axis <NUM>. While analytical optics theory generally assumes an infinite number of echelettes, a standard multifocal diffractive IOL typically has at least <NUM> echelettes, and may have over <NUM> echelettes. For the sake of clarity, <FIG> shows only <NUM> 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.

Conventional multifocal diffractive lenses typically provide for near and far field vision, neglecting visual performance at intermediate distances. Providing for an additional intermediate focal length by way of additional optical zones, e.g. by providing sets of at least two echelettes, can help to improve the visual performance at intermediate distances. However, as the number of optical zones increases, the risk of visual artifacts also increases. For example, in a quadrifocal diffractive lens having a near focal length, multiple intermediate focal lengths, and a far focal length; visual artifacts such as halos or glare may be visible to a user due to one or more of the boundaries between the optical zones.

<FIG> shows a diffractive multifocal IOL <NUM> having an intermediate focal length 15c between near and far focal lengths 15b, 15a. The addition of an intermediate focal length 15c can increase the performance of the IOL <NUM> for users by providing improved visual acuity for viewing objects in the range of about <NUM> feet to about <NUM>-<NUM> feet from the eye. In general, adding a focal length can permit a presbyopic eye to focus more readily on objects at different distances.

The diffractive profile of the diffractive multifocal IOL <NUM> may provide for the additional focal length beyond the near focal length and far focal lengths described above by employing sets of multiple echelettes. For example, the plurality of concentric diffractive echelettes forming the diffractive profile may be split up into sets of at least two echelettes. The sets are repeating over the optic. The sets of echelettes can direct light <NUM> toward the near field focus 15b and toward the intermediate field focus 15c. As described above with respect to diffractive multifocal IOLs, the far focus 15a may typically be with a <NUM>th diffractive order, while the near field focus 15b may be associated with a <NUM>nd diffractive order. The intermediate focus 15c may be associated with the <NUM>st diffractive order. However, different configurations are possible. For example, a diffractive multifocal IOL may instead be configured to direct light to the far focal length 15a in the <NUM>st diffractive order, while directing light to the intermediate and near focal lengths 15c and 15b by way of <NUM>nd and <NUM>rd diffractive orders of the echelettes. In other embodiments (a quadrifocal embodiment), an additional intermediate focus (a second intermediate focus) may be provided. Greater or lesser numbers of focuses may be provided as desired in other embodiments.

<FIG> shows a graphical representation of a portion of a parabolic diffractive profile <NUM>, according to embodiments encompassing a set of <NUM> echelettes that may repeat. The figure shows the set of <NUM> echelettes. In the exemplary diffractive profile <NUM>, echelettes <NUM>, <NUM>, and <NUM> are shown in the X direction (<NUM>) from a first, minimum radius r<NUM> to a maximum radius r<NUM><NUM>. The height of the surface relief pattern (from a plane bisecting the lens) is shown in the Y direction (<NUM>) in terms of the phase shift of the echelette (or Δ), and is plotted against the square of the radial distance (r<NUM>) from a central axis of the lens. The phase shift corresponds to a physical height or offset of the echelette from an underlying curve of the lens (Δo), and may be expressed in terms of wavelength. The echelettes <NUM>, <NUM>, <NUM> are shown arranged in an A, B, C arrangement, which may be repeated. The diffractive powers of the set of echelettes is driven by the specific geometry of the echelettes, including the change in height Δ<NUM>, Δ<NUM>, over the widths of each echelette <NUM>, <NUM>, <NUM>. The alternating arrangement may be referred to as a saw-tooth profile. Although only three echelettes are shown, it will be understood that any suitable number of echelettes may be positioned on a lens.

Each echelette is connected with each neighboring echelette, where present, by a transition zone. For example, the first echelette <NUM> connects with the second echelette <NUM> by a first transition zone <NUM>; and the second echelette <NUM> connects with the third echelette <NUM> by a second transition zone <NUM>. The transition zones <NUM>, <NUM> are step heights Δ<NUM>, Δ<NUM> from trailing edges of one echelette to leading edges of the next echelette. The first echelette <NUM> also transitions from a minimum height by third transition zone <NUM>.

The arrangement of the set of three echelettes <NUM>, <NUM>, <NUM> in a diffractive profile in <FIG> represents a general quadrifocal lens. <FIG>, however, shows a graphical representation of a generalized set of n echelettes, representing a general profile of a multifocal diffractive lens profile <NUM> having n add powers, and in total n+<NUM> powers. The profile is shown with the square of the lens radius r<NUM> (or ρ) on the X axis <NUM>, and the height of the profile, or phase shift, on the Y axis (<NUM>). The diffractive powers of the set of echelettes is driven by the specific geometry of the echelettes, including the radii (r<NUM>, r<NUM>,.

In a generalized case, where a profile height is maximum at ρi-<NUM> and minimum at ρi, the initial maximum profile height <NUM> may be expressed as a sum of a step height Δi-<NUM> and a step offset Δi-1o. The step offset is the height offset of the transition zone from the underlying base curve. The following maximum profile height <NUM> can be expressed as a sum of the following step height Δi and following step offset Δio. The slope of profile Δpi(ρ) (<NUM>) can be expressed in a generalized form as follows.

A diffractive profile can provide for multiple focal lengths (or foci) by providing different echelette geometries in series. For example, a diffractive profile having four focal lengths, as described above, can be created by providing three different diffractive echelettes in series (forming a set of three different diffractive echelettes). The three different diffractive echelettes can be repeated, leading to repeated sets of the three different diffractive echelettes, and a diffractive profile over a portion or all of a lens surface. In conventional lenses, the diffractive profile is repeated in a saw-tooth configuration, as shown in <FIG>.

According to certain embodiments of the present disclosure, a diffractive profile can be modified by manipulating the step heights Δi and following step offsets Δio between echelettes of different echelettes in a set of echelettes. For example, <FIG> shows a graphical representation illustrating a modified quadrifocal diffractive lens profile <NUM> in which a step height between two echelettes has been minimized to be essentially zero. By reducing a step height between two echelettes to zero, or about zero, the potential for that step height to generate visual artifacts such as straylight, rings, or halo can be reduced.

In the diffractive lens profile <NUM> of <FIG>, the square of the radius (r<NUM> or ρ) is shown on the X axis <NUM>, and the profile height (Δ) is shown on the Y axis <NUM>. The shape of the diffractive lens profile <NUM> is represented in relation to the square of the radius (r<NUM> or ρ), which is referred to as r-squared space. A first echelette <NUM> spans a first distance <NUM>; a second echelette <NUM> spans a second distance <NUM>, and a third echelette <NUM> spans a third distance <NUM>. Notably, the transition <NUM> between the first and second echelette <NUM>, <NUM> has been reduced to a step height of zero by matching an offset of the first echelette <NUM> with a maximum height of the second echelette <NUM>. A nonzero step height <NUM> is still shown between the second and third echelettes <NUM>, <NUM>.

A typical transition zone having a nonzero step height can cause unintended redirection or concentration of light behind the lens, which may contribute to various forms of dysphotopsia. For example, nonzero step height transition zones may cause straylight, halos, glare, or other optical aberrations to appear in the far focal length. As any of the transition zones may cause such optical aberrations, reducing the number of nonzero step-height transition zones can cause a significant reduction in the incidence of such optical aberrations.

In some embodiments, the reduction in optical aberrations may be enhanced by increasing the amount of light directed toward the far and intermediate focal lengths compared to the amount of light directed toward the near focal length. For example, a diffractive profile may be configured wherein a nonzero percentage of light is diverted to each of a near focal length, an intermediate focal length, and a far focal length, and the amount of light directed to the near focal length can be smaller than the amount directed to any other focal length. According to some embodiments, the echelettes may be arranged to direct light to the far focal length in the <NUM>th diffraction orders, the intermediate in the <NUM>st diffractive order, and the near focal length receives light via the 2nd diffractive order. In other embodiments, the echelettes may be arranged to direct light to the far focal length in the <NUM>st diffractive order, the intermediate focal length in the <NUM>nd diffractive order, and the near focal length receives light by way of the <NUM>rd diffractive order. In some cases, the amount of light directed to the far focal length can be greater than half of the total distribution of light that passes through the lens. The amount of light directed to the near focal length may generally be no more than <NUM>% of the total distribution of light that passes through the lens. A through-focus point spread function (PSF) of such an embodiment is illustrated in <FIG>. The horizontal axis <NUM> illustrates the total power of the lens. In this case the lens power for far vision <NUM> is <NUM> diopter. The vertical axis <NUM> illustrates the PSF, or light intensity. The peaks are shown for far vision <NUM>, for intermediate vision <NUM>, and for near vision <NUM>. The peak for near vision <NUM> is the lower than the peak for intermediate vision <NUM>, and the peak for intermediate vision <NUM> is lower than the peak for far vision <NUM>. Providing a light distribution, as discussed in regard to <FIG>, may be provided for an embodiment with a greater or lesser number of focal lengths, which may include a quadrifocal embodiment. For example, in a quadrifocal embodiment, the amount of light directed to the near focal length can be smaller than the amount directed to any other focal length. The amount of light directed to the far focal length can be greater than half of the total distribution of light that passes through the lens. The amount of light directed to the near focal length may generally be no more than <NUM>% of the total distribution of light that passes through the lens. In these embodiments, a diffractive profile having the aforementioned light distribution may or may not include a minimized or zero step height placed between echelettes. In an embodiment with a minimized or zero step height, the minimized or zero step height may be placed between suitable echelettes, particularly between any two echelettes in a repeating set of echelettes.

<FIG> shows a cross-sectional view of diffractive lens surface <NUM> having the quadrifocal lens profile that is shown in <FIG>, but here repeated over the optic of the lens.

In the exemplary diffractive lens surface <NUM>, the radius (r) is shown on the X axis <NUM> and a profile height (Δ) is shown on the Y axis <NUM>.

The diffractive lens surface <NUM> includes the set 803a of three echelettes 806a, 810a, 814a. The three echelettes 806a, 810a, 814a are the echelettes <NUM>, <NUM>, <NUM> shown in <FIG> (although shown in linear space in <FIG>, and not in r-squared space as shown in <FIG>). The set 803a is repeated over the optic to form repeated sets 803b, 803c, and so on, each comprising the same set defined in r<NUM>-space, configured to provide different focal lengths at respective diffractive powers. The diffractive profile accordingly includes a repetitive pattern (803a, 803b, 803c) of the echelettes repeated on the optical surface. For example, in first set 803a, a first echelette 806a, second echelette 810a, and third echelette 814a may be provided. The first echelette 806a, second echelette 810a, and third echelette 814a may each have a different profile than each other in r-squared space. The second set 803b may include a first echelette 806b, a second echelette 810b, and a third echelette 814b, each having the same profile in r-squared space as the respective first, second, and third echelettes 806a, 810a, 814a of the first set 803a. The third set 803c may include a first echelette 806c, a second echelette 810c, and a third echelette 814c, each having the same profile in r-squared space as the respective first, second, and third echelettes 806a, 810a, 814a of the first set 803a and the first, second, and third echelettes 806b, 810b, 814b of the second set 803b. The same pattern can repeat for any suitable number of sets.

The echelettes are defined in part by transition zones bounding each respective echelette. For example, regarding the first set 803a, the first echellette 806a is separated from the second echelette 810a by the first transition zone 808a; the second echelette 810a is separated from the third echelette 814a by a second transition zone 812a. The third echelette 814a is separated from the first echelette 806b of the second set 803b by the transition zone <NUM> between the sets 803a, 803b. Similarly, regarding the second set 803b, the first echellette 806b is separated from the second echelette 810b by the first transition zone 808b; the second echelette 810b is separated from the third echelette 814b by a second transition zone 812b. The third echelette 814b is separated from the first echelette 806c of the third set 803c by the transition zone <NUM> between the sets 803b, 803c. Regarding the third set 803c, the first echellette 806c is separated from the second echelette 810c by the first transition zone 808c; the second echelette 810c is separated from the third echelette 814c by a second transition zone 812c. The pattern repeats across the additional sets of echelettes.

As with conventional diffractive lenses, some of the transition zones (e.g. zones 812a, <NUM>, 812b, <NUM>) may have a nonzero step height. However, in accordance with embodiments, at least one pair of echelettes (e.g. zones 806a, 810a) is separated by a transition zone 808a having a step height of zero. At least one of the echelettes is connected to an adjacent echelette by a step height of zero. As the echelettes repeat across sets, further adjacent echelettes (e.g. echelettes 806b and 810b; 806c and 810c) may be separated by transition zones having step heights of zero (e.g. transition zones 808b, 808c).

Although the exact number of repeating sets shown in <FIG> is about six, any suitable number of repeating sets may be applied to a lens depending on the specific geometry of the echelettes and the width of the lens. For example, in certain embodiments, at least two sets repeating radially outward may be utilized. In some cases, the profile can extend over a total radius of approximately <NUM> millimeters (mm), as shown; but in other cases, the profile may extend from as little as about <NUM> to as much as about <NUM>.

<FIG> shows a graphical representation illustrating a second quadrifocal lens profile <NUM> according to certain embodiments of this disclosure. The quadrifocal lens profile <NUM> is shown in terms of profile height (or Δ), or phase shift, on the Y axis <NUM> against the square of the radius (or ρ) on the X axis <NUM> (in r-squared space). The profile <NUM> defines a set of three distinct echelettes <NUM>, <NUM>, <NUM> each spanning a respective portion <NUM>, <NUM>, <NUM> of the lens. In the quadrifocal lens profile <NUM>, for an A, B, C arrangement of three distinct echelettes, the minimum or zero step height <NUM> is positioned at the B-C transition between the second echelette <NUM> and the third echellete <NUM>. In this example, the minimum or zero step height <NUM> is convex, as the preceding or second echelette <NUM> is less steep than the subsequent or third echelette <NUM>. A non-zero step height <NUM> connects the first echelette <NUM> to the second echelette <NUM>.

As discussed above, the positioning of the minimized or zero step height may be adjusted. The example in <FIG> and <FIG> shows a configuration wherein, for an A, B, C arrangement of three distinct echelettes, the minimum or zero step height is positioned at the A-B transition. The example in <FIG> shows a configuration wherein, for an A, B, C arrangement of three distinct diffractive zones, the minimum or zero step height is positioned at the B-C transition. The transition having minimum or zero step height is convex, as an echelette <NUM> merged at its respective minimum height with a steeper echelette <NUM>. In <FIG>, the transition having minimum or zero step height is concave, as a steeper echelette <NUM> merged at its respective minimum height with a less steep echelette <NUM>.

A concave or convex transition may influence the performance of the profile, and the manufacturability. The size or extent of concave transitions may be minimized if lens is manufactured by molding. In contrast, the size or extent of convex transitions may be minimized if the lens is manufactured by lathe cutting.

<FIG> shows a graphical representation illustrating a trifocal lens profile <NUM> according to certain embodiments of this disclosure. The trifocal lens profile <NUM> is shown in terms of profile height (or Δ), or phase shift, on the Y axis <NUM> against the square of the radius (or ρ) on the X axis <NUM> (in r-squared space). The profile <NUM> defines a set of two distinct echelettes <NUM>, <NUM> each spanning a respective portion <NUM>, <NUM> of the lens. In the trifocal lens profile <NUM>, for an A, B arrangement of two distinct echelettes, the minimum or zero step height <NUM> is positioned at the A-B transition between the first echelette <NUM> and the second echelette <NUM>. In this example, the minimum or zero step height <NUM> is convex, as the preceding or first echelette <NUM> is less steep than the subsequent or second echelette <NUM>. The set of echelettes comprising the first echelette <NUM> and second echelette <NUM> may be repeated over the optic of the lens for any number of repetitions, as desired.

Any of the embodiments of lens profiles discussed herein may be apodized 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.

The structures and methods discussed herein may be used to produce a lens having any number of focal lengths (monofocal, bifocal, trifocal, quadrifocal, etc.), and the diffractive profiles discussed herein may be used to produce any number of focal points (at least one focal point). The diffractive profiles may be applied to cover an annulus of the first surface or the second surface. The lens may be characterized as a monofocal lens or extended depth of focus lens.

<FIG> is a simplified block diagram illustrating a system <NUM> for generating an ophthalmic lens based on a user input.

The system <NUM> includes a user input module <NUM> configured to receive user input defining aspects of the user of a lens and of the lens itself. Aspects of a lens may include anatomical dimensions like pupil size performance, and lens dimensions, among other attributes, and a diffractive lens prescription, which may be a multifocal prescription. A lens prescription can include, for example, a preferred optical power or optical power profile for correcting far vision and an optical power or optical power profile for near vision. In some cases, a lens 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 diffractive surface modeling module <NUM> can receive information about the desired lens from the user input module <NUM>, and can determine aspects of a multizonal lens. For example, the modeling module <NUM> can determine the shape of one or more echelettes of the diffractive profile of a diffractive lens, including the positioning, width, step height, and curvature needed to fulfill the prescription for each set of the echelettes, as well as the positioning of each set of echelettes. The multizonal diffractive surface modeling module <NUM> 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 diffractive surface modeling module <NUM> can be configured to generate performance criteria <NUM>, 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 lens prescription. The performance criteria can also include the severity of diffractive aberrations caused by lens surface. In some cases, the multizonal surface modeling module <NUM> 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 <NUM> for empirically determining the performance criteria <NUM>, so as to identify optical aberrations and imperfections not readily discerned via virtual modeling, and to permit iteration.

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

<FIG> is an example process <NUM> for generating a diffractive lens surface, in accordance with embodiments. The process <NUM> may be implemented in conjunction with, for example, the system <NUM> shown in <FIG>. Some or all of the process <NUM> (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 <NUM> includes receiving an input indicative of a diffractive lens prescription (act <NUM>). 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 generated including a repetitive pattern of at least two echelettes (act <NUM>). At least one of the at least two echelettes in the repetitive pattern may be connected to an adjacent echelette by a step height of zero (act <NUM>).

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 be generated having a base power that, in combination with the diffractive lens surface, meets the diffractive lens prescription (act <NUM>). A total lens surface can be generated based on both the refractive lens surface and the diffractive lens surface (act <NUM>). 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 <NUM>).

<FIG> is a simplified block diagram of an exemplary computing environment <NUM> that may be used by systems for generating the continuous progressive lens surfaces of the present disclosure. Computer system <NUM> typically includes at least one processor <NUM> which may communicate with a number of peripheral devices via a bus subsystem <NUM>. These peripheral devices may include a storage subsystem <NUM> comprising a memory subsystem <NUM> and a file storage subsystem <NUM>, user interface input devices <NUM>, user interface output devices <NUM>, and a network interface subsystem <NUM>. Network interface subsystem <NUM> provides an interface to outside networks <NUM> and/or other devices, such as the lens fabrication module <NUM> or lens testing module <NUM> of <FIG>.

User interface input devices <NUM> 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 <NUM> 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 <NUM>.

The display subsystem may be 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 <NUM> to a user.

Storage subsystem <NUM> 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 <NUM>. These software modules are generally executed by processor <NUM>. 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 <NUM> typically comprises memory subsystem <NUM> and file storage subsystem <NUM>. Memory subsystem <NUM> typically includes a number of memories including a main random access memory (RAM) <NUM> for storage of instructions and data during program execution.

Claim 1:
A method of designing an intraocular lens, the intraocular lens having a first surface and a second surface disposed about an optical axis, the method comprising:
defining a diffractive profile (<NUM>) including:
a repetitive pattern of three echelettes (<NUM>, <NUM>, <NUM>) with transition zones (<NUM>, <NUM>) bounding each respective echelette (<NUM>, <NUM>, <NUM>), wherein each echelette has a maximum profile height expressed as a sum of a step height and a step offset, the step offset being defined as the height offset of the transition zone from an underlying base curve, and
at least one of the three echelettes (<NUM>, <NUM>, <NUM>) in the repetitive pattern is connected to an adjacent echelette (<NUM>, <NUM>, <NUM>) by a step height of zero by matching a step offset of the adjacent echelette with the maximum height of the at least one echelette; and
generating a diffractive lens surface based on the diffractive profile (<NUM>).