Haptic for accommodating intraocular lens

An intraocular lens is disclosed, with an optic that changes shape in response to a deforming force exerted by the zonules of the eye. A haptic supports the optic around its equator and couples the optic to the capsular bag of the eye. The region of contact between the optic and the haptic extends into the edge of the optic, similar to the interface between a bicycle tire and the rim that holds it in place. The haptic may be stiffer than the optic. The haptic may have the same refractive index as the optic. The haptic may include a saddle-shaped portion in contact with the adjustable optic, with a convex profile along an optical axis; and a concave profile in a plane perpendicular to the optical axis.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to intraocular lenses, and more particularly to accommodating intraocular lenses.

2. Description of the Related Art

A human eye can suffer diseases that impair a patients vision. For instance, a cataract may increase the opacity of the lens, causing blindness. To restore the patients vision, the diseased lens may be surgically removed and replaced with an artificial lens, known as an intraocular lens, or IOL. An IOL may also be used for presbyopic lens exchange.

The simplest IOLs have a single focal length, or, equivalently, a single power. Unlike the eye's natural lens, which can adjust its focal length within a particular range in a process known as accommodation, these single focal length IOLs cannot generally accommodate. As a result, objects at a particular position away from the eye appear in focus, while objects at an increasing distance away from that position appear increasingly blurred.

An improvement over the single focal length IOLs is an accommodating IOL, which can adjust its power within a particular range. As a result, the patient can clearly focus on objects in a range of distances away from the eye, rather than at a single distance. This ability to accommodate is of tremendous benefit for the patient, and more closely approximates the patient's natural vision than a single focal length IOL.

When the eye focuses on a relatively distant object, the lens power is at the low end of the accommodation range, which may be referred to as the “far” power. When the eye focuses on a relatively close object, the lens power is at the high end of the accommodation range, which may be referred to as the “near” power. The accommodation range or add power is defined as the near power minus the far power. In general, an accommodation range of 2 to 4 diopters is considered sufficient for most patients.

The human eye contains a structure known as the capsular bag, which surrounds the natural lens. The capsular bag is transparent, and serves to hold the lens. In the natural eye, accommodation is initiated by the ciliary muscle and a series of zonular fibers, also known as zonules. The zonules are located in a relatively thick band mostly around the equator of the lens, and impart a largely radial force to the capsular bag that can alter the shape and/or the location of the natural lens and thereby change its effective power.

In a typical surgery in which the natural lens is removed from the eye, the lens material is typically broken up and vacuumed out of the eye, but the capsular bag is left intact. The remaining capsular bag is extremely useful for an accommodating intraocular lens, in that the eye's natural accommodation is initiated at least in part by the zonules through the capsular bag. The capsular bag may be used to house an accommodating IOL, which in turn can change shape and/or shift in some manner to affect the power and/or the axial location of the image.

The IOL has an optic, which refracts light that passes through it and forms an image on the retina, and a haptic, which mechanically couples the optic to the capsular bag. During accommodation, the zonules exert a force on the capsular bag, which in turn exerts a force on the optic. The force may be transmitted from the capsular bag directly to the optic, or from the capsular bag through the haptic to the optic.

A desirable optic for an accommodating IOL is one that distorts in response to a squeezing or expanding radial force applied largely to the equator of the optic (i.e., by pushing or pulling on or near the edge of the optic, circumferentially around the optic axis). Under the influence of a squeezing force, the optic bulges slightly in the axial direction, producing more steeply curved anterior and/or posterior faces, and producing an increase in the power of the optic. Likewise, an expanding radial force produces a decrease in the optic power by flattening the optic. This change in power is accomplished in a manner similar to that of the natural eye and is well adapted to accommodation. Furthermore, this method of changing the lens power reduces any undesirable pressures exerted on some of the structures in the eye.

One challenge in implementing such an optic is designing a suitable haptic to couple the optic to the capsular bag. The haptic should allow distortion of the optic in an efficient manner, so that a relatively small ocular force from the ciliary muscle, zonules, and/or capsular bag can produce a relatively large change in power and/or axial location of the image. This reduces fatigue on the eye, which is highly desirable.

Accordingly, there exists a need for an intraocular lens having a haptic with increased efficiency in converting an ocular force to a change in power and/or a change in axial location of the image.

SUMMARY OF THE INVENTION

An embodiment is an intraocular lens for implantation in a capsular bag of an eye, comprising an adjustable optic; and a haptic protruding into the adjustable optic. The haptic is configured to transmit forces to alter at least one of the shape or the thickness of the adjustable optic.

A further embodiment is an intraocular lens for implantation in a capsular bag of an eye, comprising an adjustable optic having an optic stiffness and an optic refractive index; and a haptic having a haptic stiffness and a haptic refractive index for coupling the adjustable optic to the capsular bag. The haptic stiffness is greater than the optic stiffness. The haptic refractive index is essentially equal to the optic refractive index.

A further embodiment is a method of adjusting the focus of an intraocular lens having an adjustable optic having an annular recess, comprising applying a deforming force through a haptic in contact with the annular recess of the adjustable optic; and altering at least one parameter of the adjustable optic in response to the deforming force.

DETAILED DESCRIPTION OF THE DRAWINGS

In a healthy human eye, the natural lens is housed in a structure known as the capsular bag. The capsular bag is driven by a ciliary muscle and zonular fibers (also known as zonules) in the eye, which can compress and/or pull on the capsular bag to change its shape. The motions of the capsular bag distort the natural lens in order to change its power and/or the location of the lens, so that the eye can focus on objects at varying distances away from the eye in a process known as accommodation.

For some people suffering from cataracts, the natural lens of the eye becomes clouded or opaque. If left untreated, the vision of the eye becomes degraded and blindness can occur in the eye. A standard treatment is surgery, during which the natural lens is broken up, removed, and replaced with a manufactured intraocular lens. Typically, the capsular bag is left intact in the eye, so that it may house the implanted intraocular lens.

Because the capsular bag is capable of motion, initiated by the ciliary muscle and/or zonules, it is desirable that the implanted intraocular lens change its power and/or location in the eye in a manner similar to that of the natural lens. Such an accommodating lens may produce vastly improved vision over a lens with a fixed power and location that does not accommodate.

FIG. 1shows a human eye10, after an accommodating intraocular lens has been implanted. Light enters from the left ofFIG. 1, and passes through the cornea12, the anterior chamber14, the iris16, and enters the capsular bag18. Prior to surgery, the natural lens occupies essentially the entire interior of the capsular bag18. After surgery, the capsular bag18houses the intraocular lens, in addition to a fluid that occupies the remaining volume and equalizes the pressure in the eye. The intraocular lens is described in more detail below. After passing through the intraocular lens, light exits the posterior wall20of the capsular bag18, passes through the posterior chamber32, and strikes the retina22, which detects the light and converts it to a signal transmitted through the optic nerve24to the brain.

A well-corrected eye forms an image at the retina22. If the lens has too much or too little power, the image shifts axially along the optical axis away from the retina, toward or away from the lens. Note that the power required to focus on a close or near object is more than the power required to focus on a distant or far object. The difference between the “near” and “far” powers is known typically as the range of accommodation. A normal range of accommodation is about 4 diopters, which is considered sufficient for most patients.

The capsular bag is acted upon by the ciliary muscle25via the zonules26, which distort the capsular bag18by stretching it radially in a relatively thick band about its equator. Experimentally, it is found that the ciliary muscle25and/or the zonules26typically exert a total ocular force of up to about 10 grams of force, which is distributed generally uniformly around the equator of the capsular bag18. Although the range of ocular force may vary from patient to patient, it should be noted that for each patient, the range of accommodation is limited by the total ocular force that can be exert. Therefore, it is highly desirable that the intraocular lens be configured to vary its power over the full range of accommodation, in response to this limited range of ocular forces. In other words, it is desirable to have a relatively large change in power for a relatively small driving force.

Because the zonules' or ocular force is limited, it is desirable to use a fairly thin lens, compared to the full thickness of the capsular bag. In general, a thin lens may distort more easily than a very thick one, and may therefore convert the ocular force more efficiently into a change in power. In other words, for a relatively thin lens, a lower force is required to cover the full range of accommodation.

Note that there may be an optimum thickness for the lens, which depends on the diameter of the optic. If the lens is thinner than this optimum thickness, the axial stiffness becomes too high and the lens changes power less efficiently. In other words, if the edge thickness is decreased below its optimal value, the amount of diopter power change for a given force is decreased. For instance, for an optic having a diameter of 4.5 mm, an exemplary ideal edge thickness may be about 1.9 mm, with edge thicknesses between about 1.4 mm and about 2.4 having acceptable performance as well.

Note that the lens may be designed so that its relaxed state is the “far” condition (sometimes referred to as “disaccommodative biased”), the “near” condition (“accommodative biased”), or some condition in between the two.

The intraocular lens itself generally has two components: an optic28, which is made of a transparent, deformable and/or elastic material, and a haptic30, which holds the optic28in place and mechanically transfers forces on the capsular bag18to the optic28. The haptic30may have an engagement member with a central recess that is sized to receive the peripheral edge of the optic28.

When the eye10focuses on a relatively close object, as shown inFIG. 1, the zonules26relax and the capsular bag18returns to its natural shape in which it is relatively thick at its center and has more steeply curved sides. As a result of this action, the power of the lens increases (i.e., one or both of the radii of curvature can decrease, and/or the lens can become thicker, and/or the lens may also move axially), placing the image of the relatively close object at the retina22. Note that if the lens could not accommodate, the image of the relatively close object would be located behind the retina, and would appear blurred.

FIG. 2shows a portion of an eye40that is focused on a relatively distant object. The cornea12and anterior chamber14are typically unaffected by accommodation, and are substantially identical to the corresponding elements inFIG. 1. To focus on the distant object, the ciliary muscle45contracts and the zonules46retract and change the shape of the capsular bag38, which becomes thinner at its center and has less steeply curved sides. This reduces the lens power by flattening (i.e., lengthening radii of curvature and/or thinning) the lens, placing the image of the relatively distant object at the retina (not shown).

For both the “near” case ofFIG. 1and the “far” case ofFIG. 2, the intraocular lens itself deforms and changes in response to the distortion of the capsular bag. For the “near” object, the haptic30compresses the optic28at its edge, increasing the thickness of the optic28at its center and more steeply curving its anterior face27and/or its posterior face29. As a result, the lens power increases. For the “far” object, the haptic50expands, pulling on the optic48at its edge, and thereby decreasing the thickness of the optic48at its center and less steeply curving (e.g., lengthening one or both radius of curvature) its anterior face47and/or its posterior face49. As a result, the lens power decreases.

Note that the specific degrees of change in curvature of the anterior and posterior faces depend on the nominal curvatures. Although the optics28and48are drawn as bi-convex, they may also be plano-convex, meniscus or other lens shapes. In all of these cases, the optic is compressed or expanded by essentially forces by the haptic to the edge and/or faces of the optic. In addition, the may be some axial movement of the optic. In some embodiments, the haptic is configured to transfer the generally symmetric radial forces symmetrically to the optic to deform the optic in a spherically symmetric way. However, in alternate embodiments the haptic is configured non-uniformly (e.g., having different material properties, thickness, dimensions, spacing, angles or curvatures), to allow for non-uniform transfer of forces by the haptic to the optic. For example, this could be used to combat astigmatism, coma or other asymmetric aberrations of the eye/lens system. The optics may optionally have one or more diffractive elements, one or more multifocal elements, and/or one or more aspheric elements.

FIG. 3shows a deformable optic with an exemplary haptic, shown in isometric view and removed from the eye. The view ofFIG. 3shows that the haptic extends a full 360 degrees azimuthally around the edge of the optic, which is not seen in the cross-sectional view ofFIGS. 1 and 2.

The exemplary haptic ofFIG. 3has various segments or filaments, each of which extends generally in a plane parallel to the optical axis of the lens. For the exemplary haptic ofFIG. 3, the segments are joined to each other at one end, extend radially outward until they contact the capsular bag, then extend radially inward until they contact the edge of the optic. At the edge of the optic, the haptic segments may remain separate from each other, as shown inFIG. 3, or alternatively some or all segments may be joined together. Any or all of the width, shape and thickness of the segments may optionally vary along the length of the segments. The haptic may have any suitable number of segments, including but not limited to,4,6,8,10,12,14, and16.

Note that the region of contact between the optic and the haptic inFIG. 3extends into the edge of the optic, similar to the interface between a bicycle tire and the rim that holds it in place. This region of contact between the haptic and the optic is described and shown in much greater detail in the text and figures that follow.

FIG. 4shows an azimuthal slice of an optic41and a haptic42. Although only two segments of the haptic42are shown inFIG. 4, it will be understood that haptic42may extend fully around the equator of the optic41.

Of particular note is the interface between the haptic42and the optic41. The optic41inFIG. 4has an annular recess43around its edge, and the haptic42extends or protrudes into this annular recess, instead of merely contacting the optic at a cylindrical edge parallel to the optical axis.

This protrusion into the edge of the optic may allow for greater transfer of forces from the capsular bag, through the haptic, to the optic. There may be a greater coupling of these forces to the anterior and/or posterior surfaces of the optic, which may result in more distortion or deforming of these surfaces for a given distorting force. As a result, the limited capsular bag force may produce a greater distortion of the optic, and, therefore, a larger change in power and/or a larger axial translation of the image at the retina.

The optic41is made from a relatively soft material, so that it can distort or change shape readily under the limited deforming force initiated by the capsular bag and transmitted through the haptic42. An exemplary material is a relatively soft silicone material, although other suitable materials may be used as well. The stiffness of the optic41may be less than 500 kPa, or preferably may be between 0.5 kPa and 500 kPa, or more preferably may be between 25 kPa and 200 kPa, or even more preferably may be between 25 kPa and 50 kPa.

In contrast with the optic41, the haptic42is made from a relatively stiff material, so that it can efficiently transmit the deforming forces from the capsular bag to the optic41. An exemplary material is a relatively stiff silicone material, although other suitable materials may be used as well, such as acrylic, polystyrene, or clear polyurethanes. The haptic42may preferably be stiffer than the optic41. The stiffness of the haptic42may be greater than 500 kPa, or preferably may be greater than 3000 kPa.

Because the haptic42extends into the optic41in a region around its circumference, it also may extend into the clear aperture of the optic41. For this reason, the haptic may preferably be transparent or nearly transparent, so that it does not substantially block any light transmitted through the lens.

In addition, it is desirable that the interface between the optic41and the haptic42does not produce any significant reflections, which would produce scattered light within the eye, and would appear as a haze to the patient. A convenient way to reduce the reflections from the interface is to match the refractive indices of the haptic and the optic to each other.

A simple numerical example shows the effect of mismatch of refractive indices on reflected power. For a planar interface at normal incidence between air (refractive index of 1) and glass (refractive index of 1.5), 4% of the incident power is reflected at the interface. For such an interface between air and glass, there is no attempt to match refractive indices, and this 4% reflection will merely provide a baseline for comparison. If, instead of 1 and 1.5, the refractive indices differ by 4%, such as 1.5 and 1.56 or 1.5 and 1.44, there is a 0.04% reflection, or a factor of 100 improvement over air/glass. Finally, if the refractive indices differ by only 0.3%, such as 1.5 and 1.505 or 1.5 and 1.495, there is a 0.00028% reflection, or a factor of over 14000 improvement over air/glass. In practice, tolerances such as the 0.3% case may be achievable, and it is seen that a negligible fraction of power may be reflected at the interface between a haptic and an optic whose refractive indices differ by 0.3%. Note that the above base value of 1.5 was chosen for simplicity, and that the haptic and optic may have any suitable refractive index.

It is desirable that the refractive indices of the haptic and optic be essentially the same. For the purposes of this document, “essentially the same” may mean that their refractive indices are equal to each other at a wavelength within the visible spectrum (i.e., between 400 nm and 700 nm). Note that the haptic and optic may optionally have different dispersions, where the refractive index variation, as a function of wavelength, may be different for the haptic and the optic. In other words, if the refractive indices of the haptic and optic are plotted as a function of wavelength, they may or may not have different slopes, and if the two curves cross at one or more wavelengths between 400 nm and 700 nm, then the refractive indices may be considered to be essentially the same or essentially equal.

The exemplary haptic42has segments that are not joined at the edge of the optic41, and has a generally uniform thickness throughout. Note that these two qualities of the haptic may be varied, as shown inFIGS. 5 through 8.

InFIG. 5, the segments of the haptic52are joined at the edge of the optic51. The optic has an annular recess53, analogous to annular recess43ofFIG. 4. Note that at the edge of the optic, the haptic segments need not be all joined or all separate, but may be joined in adjacent pairs or in any other suitable scheme.

InFIG. 6, the haptic62has a variation in thickness along the edge of the optic61, so that the side opposite the annular recess63is essentially flat.

InFIG. 7, the haptic72has a variation in thickness along the edge of the optic71, so that the side opposite the annular recess73is convex.

InFIG. 8, the haptic82has an increasing thickness approaching the annular recess83of the optic81.

InFIGS. 4 through 8, each haptic is made from a single, relatively stiff material, and each optic is made from a single, relatively soft material. As an alternative, other materials having different stiffnesses may be introduced.

For instance,FIG. 9shows an optic91made from a soft material, a haptic92made from a stiff material94, and a third material95that is stiffer than the haptic stiff material94. Alternatively, the third material95may be less stiff than the haptic stiff material94. In this example, the third material95is in contact with the optic91at its annular recess93. For the purposes of this document, such a third material95may be considered to be part of the haptic92, although in practice it may optionally be manufactured as part of the optic91. Alternatively, there may be one or more materials used for the haptic and/or the optic, which may have the same or different stiffnesses.

InFIGS. 4 through 9, each optic has an annular recess with a generally smooth, curved, concave profile, along a direction parallel to the optical axis of the lens. (Similarly, each corresponding haptic has a generally smooth, curved, convex profile, along a direction parallel to the optical axis of the lens.) As an alternative, the profile need not be generally smooth, and/or need not be curved.

For instance, the optic101ofFIG. 10has an annular recess103with a concave profile that is not smooth but has corners, and is not curved but has straight portions. (Similarly, the haptic102has a convex profile with corners and straight portions.) In this case, one of the straight portions104is parallel to the optical axis of the lens, and the other two straight portions105and106are inclined with respect to a plane perpendicular to the optical axis.

InFIG. 10, the deepest portion of the profile falls along the straight portion103, although it may fall at a particular point rather than along a full line. The particular point may be a corner, or may be a point along a smooth curve. ForFIG. 10, the deepest portion passes through the midpoint of the lens (i.e., the plane halfway between the anterior and posterior surfaces of the optic).

As an alternative, the deepest portion of the profile may be located away from the midpoint of the lens, and may be located closer to either the anterior or posterior surfaces of the optic. For instance,FIG. 11shows a cross-section of an optic111and a portion of a haptic with such an asymmetric deepest portion114. A potential advantage of such asymmetry is that the deformation of the surfaces may be tailored more specifically than with a symmetric profile, so that one surface may deform more than the other under a deforming force exerted by the haptic. This may be desirable for particular optic shapes.

InFIGS. 4 through 10, each of the haptics is attached to the optic at only one end. As an alternative, the haptic may be attached to the optic at both ends. For instance, haptic272ofFIG. 27attaches to optic271at both ends. Optic271has annular recess273, analogous with the annular recesses ofFIGS. 4 through 11. Furthermore, the interior region of the haptic, shown as hollow inFIG. 27, may optionally be filled with a liquid or a gel having particular mechanical properties.

FIG. 28shows a haptic282similar to that inFIG. 27, but with a variation in thickness in the region opposite the annular recess283of the optic281. Similarly, the thickness may optionally be varied at any point on the haptic282.

For further clarification of the previous geometries,FIG. 29shows a small portion of a haptic292along with some geometrical constructs. InFIG. 29, the optical axis of the lens is vertical. The upper ellipse294corresponds to the circumference of the anterior (or posterior) surface of the lens, and the lower ellipse295corresponds to the circumference of the posterior (or anterior) surface of the lens. The haptic292has a portion296that may be considered saddle-shaped or hyperbolic, with a convex profile297along a direction parallel to the optical axis of the lens, and a concave profile298in a plane perpendicular to the optical axis of the lens. Similarly, the optic (not shown) would have a corresponding annular recess that contacts a portion296of the haptic. Although the convex profile297and concave profile298are shown as smooth and continuous curves, they may alternatively have one or more straight segments, and/or may alternatively be asymmetric with respect to the anterior or posterior surfaces of the optic.

It may be beneficial to describe in words the interface between the haptic and the optic for the various lenses shown in the figures. Consider a radial plane to be a plane that includes the optical axis of the lens. The intersection of the radial plane with the haptic/optic interface of the lens forms a so-called “cross-sectional curve.” The endpoints of the cross-sectional curve are to be referred to as anterior and posterior endpoints, respectively.

As seen from the figures, the cross-sectional curve protrudes into the optic. We may define this protrusion more precisely by comparing the cross-sectional curve with a so-called “cylindrical edge” of the optic, which is taken to be a line connecting the anterior and posterior endpoints of the cross-sectional curve. Note that this “cylindrical edge” need not be truly parallel to the optical axis. “Protrusion into the optic” may therefore be interpreted in any or all of the following manners:

(1) The separation between the cross-sectional curve and the optical axis is less than the separation between the cylindrical edge and the optical axis, for all points between the anterior and posterior endpoints. This includes the designs ofFIGS. 4-11,27and28, and includes additional designs in which the entire cross-sectional curve protrudes into the optic.

(2) The separation between the cross-sectional curve and the optical axis is less than the separation between the cylindrical edge and the optical axis, for at least one point between the anterior and posterior endpoints. This also includes the designs ofFIGS. 4-11,27and28, but may include additional designs in which only a portion of the cross-sectional curve protrudes into the optic.

As also seen from the figures, the cross-sectional curve may take on various shapes. For all of the designs shown in the figures, the cross-sectional curve extends inward toward the optical axis as one moves away from the anterior endpoint, reaches a “local minimum” or a “deepest portion” at which the cross-sectional curve is at its closest to the optical axis, then extends outward away from the optical axis as one approaches the posterior endpoint. Differences arise among the various designs in the character and location of the deepest portion, as well as the local curvature of the cross-sectional curve. Three such categories of differences are detailed below; these three categories are not intended to be all-inclusive.

(1) The cross-sectional curve does not contain any corners, discontinuities, or straight segments. This includes the designs ofFIGS. 4-9,27and28. Note that the “deepest portion” occurs at only one point along the cross-sectional curve. This category of curve may be referred to as a “continuous curve”. Note that a continuous curve may optionally extend in part outside the so-called “cylindrical edge” of the optic; the designs shown in the figures extend only into the cylindrical edge of the optic.

(2) The cross-sectional curve may contain at least one straight segment, but does not contain any corners or discontinuities. The straight segment may be located anywhere along the cross-sectional curve. The straight segment may be inclined with respect to the optical axis, or may be parallel to the optical axis. The straight segment may also be parallel to the optical axis at the “deepest portion,” so that the deepest portion may have a finite spatial extent, rather than a single location.

(3) The cross-sectional curve may contain at least one straight segment, and may contain at least one corner, but does not contain any discontinuities. This includes the designs ofFIGS. 10 and 11, which each contain three straight segments and two corners. In each of the designs ofFIGS. 10 and 11, as one moves away from the anterior endpoint, the cross-section curve contains a straight segment extending toward the optical axis, followed by a straight segment parallel to the optical axis, followed by a straight segment extending away from the optical axis as one approaches the posterior endpoint. For the designs ofFIGS. 10 and 11, the middle straight segment is the “deepest portion” of the curve, which is bounded on both sides by a segment that is inclined with respect to the optical axis and is also inclined with respect to both the anterior and posterior surfaces of the optic. InFIG. 10, the middle portion104is bounded on either side by straight portions105and106, and is symmetrically located between the anterior and posterior surfaces. InFIG. 11, the middle portion114is also bounded by straight portions, but is asymmetrically located between the anterior and posterior surfaces.

The following paragraphs describe a series of simulation results that compare the performance of the haptic designs ofFIGS. 4-8to each other and to a baseline design.

A series of finite element calculations were performed, each with identical materials, identical shapes for the optic, identical shapes for the annular recess in the optic, and identical shapes for the haptic portion that contacts the capsular bag of the eye. The haptic thickness was varied to correspond to the cases ofFIGS. 4 through 8. Finally a baseline case was calculated, in which the convex profile (analogous to element297inFIG. 29) was not convex, but was planar; in this baseline case, the haptic did not protrude or extend into the edge of the adjustable optic. The haptic thickness of the baseline case was the same as forFIG. 4.

The results of the calculations are expressed as a power change in diopters, where a larger number is better. The baseline case produced a power change of 2.94 diopters. The configuration ofFIG. 4produced a power change of 5.24 diopters. The configuration ofFIG. 5produced a power change of 4.99 diopters. The configuration ofFIG. 6produced a power change of 4.96 diopters. The configuration ofFIG. 7produced a power change of 5.62 diopters. The configuration ofFIG. 8produced a power change of 9.24 diopters. These power change values are all greater than the baseline case, and all exceed the 4 diopter value that is generally accepted as a full range of accommodation.

FIGS. 12 through 18show an exemplary haptic120in various plan and cross-sectional views, both with and without an optic130.FIG. 12is a cross-section drawing of a haptic120.FIG. 13is a cross-sectional drawing of the haptic ofFIG. 12, with an optic130.FIG. 14is the cross-section drawing of the haptic120and optic130ofFIG. 13, with additional hidden lines.FIG. 15is an end-on cross-sectional drawing of the haptic120and optic130ofFIG. 13.FIG. 16is a plan drawing of the haptic120ofFIG. 12.FIG. 17is a plan drawing of the haptic120ofFIG. 16, with an optic130.FIG. 18is the cross-section drawing of the haptic120and optic130ofFIG. 17, with additional hidden lines.

The haptic120ofFIGS. 12 through 18has eight filaments denoted by elements121athrough121h. Alternatively, the haptic120may have more or fewer than eight filaments (e.g., 3 filaments, 4 filaments, or16filaments). The filaments121a-hmay be connected at their outermost edge and may be unconnected at their innermost edge.

Note that the filaments121a-hmay vary in size along their lengths, from the innermost edge123to the ends of the filament adjacent to the outermost edge122of the haptic120. In particular, the filaments121a-hmay increase in cross-sectional dimensions with radial distance away from the center of the lens. In a direction parallel to the optical axis (vertical inFIG. 12), the outermost extent of the haptic filaments, denoted by length129, may be larger than the innermost extent of the haptic filaments, denoted by dimension128. Alternatively, the length129may be equal to or less than length128. Similarly, in a direction perpendicular to the optical axis (essentially in the plane of the lens), the filaments may be effectively wedge-shaped, with a greater radial extent at the outer edge than at the inner edge. The cross-section of each filament may be symmetric with respect to the plane of the lens, as shown inFIG. 12. Alternatively, the cross-section of one or more filaments may be asymmetric with respect to the plane of the lens, with differing amounts of material on anterior and posterior sides of the filament.

The outermost edge122of the haptic120mechanically couples the intraocular lens to the capsular bag of the eye. The haptic120may receive an optic130in its central region, which may be molded directly onto the haptic120. Alternatively, the optic may be manufactured separately from the haptic, then attached to the haptic.

The haptic120may have an optional lip or ridge124on one or both of the anterior and posterior faces, so that if an optic is molded directly onto the haptic120, the optic resides in the central portion of the haptic within the lip124. The lip124may be circularly symmetric on both faces of the haptic, as shown inFIGS. 12 through 18. Alternatively, the lip124may have a different radius on one or more filaments, so that optic material may extend out different radial distances along particular filaments. As a further alternative, the lip124may have different radii on the anterior and posterior faces of the haptic120.

Once the optic130is formed on, attached to, or placed within the haptic120, the haptic120protrudes into the edge131of the optic130. For the specific design ofFIGS. 12 through 18, portions of each filament121a-hextend into the edge131of the optic130, with the anterior and posterior faces of the optic130surrounding and/or encompassing the haptic filaments121a-hin the central portion demarcated by the lip124.

For a cross-section of the filaments121a-h, taken in a plane parallel to the optical axis of the lens (vertical inFIGS. 12 through 18), the cross-section has a particular profile that extends into the edge131of the optic130. The profile may contain one or more straight and/or curved portions, and may have a deepest portion at one or more points or along a straight segment. For instance, the profile inFIGS. 12 and 15has a generally straight portion125extending generally radially inward, followed by a generally straight portion126extending generally parallel to the optical axis, followed by a generally straight portion127extending generally radially outward. The generally straight portions125,126and127may optionally have one or more rounded portions151between them. Straight portions125and127may be generally parallel to each other, or may be generally inclined with respect to each other. The generally straight portion126may be generally parallel to the optical axis, as inFIGS. 12 and 15, or may alternatively be inclined with respect to the optical axis. The deepest portion of the profile ofFIGS. 12 and 15may be the straight portion126. The profile made up of segments125,126and127shown inFIGS. 12 and 15may be generally convex in a direction parallel to the optical axis of the lens.

Referring toFIG. 15, the axial thickness (i.e., along an axis parallel to the optical axis passing through the center of the optic130) of the portions of the haptic120disposed within the optic130may be selected to control the amount and/or distribution of an ocular force acting on the intraocular lens240. For example, in some embodiments, the performance (e.g., the change Diopter power of the optic130between accommodative and disaccommodative configurations) increases as the edge thickness increases. In such embodiments, other design constraints (e.g., optical performance or physical constraints of the eye) may, however, place an upper limit on the maximum optic edge thickness. In some embodiments, the portion of the haptic120inside the optic130has a maximum axial thickness that is at least one half a maximum axial thickness of the optic130along the optical axis, as clearly illustrated inFIG. 15. In other embodiments, the ring portion246of the haptic244has a maximum axial thickness that is at least 75% of a maximum axial thickness of the central zone. The advantages of the axial thickness the protruding portions of the haptic120may also be applied to other embodiments of the invention discussed herein.

In certain embodiments, the optic130is a multifocal optic. For example, the portion of the optic130between the ends126of the haptic120may comprise a first zone having a first optical power and the portion of the optic130into which the filaments121protrude may comprise a second zone having a second optic power that is different from the first optical power. In some embodiments, the optic130may change from a monofocal optic to a multifocal optic, depending upon the amount of ocular force on the haptic120and/or the state of accommodation of the eye into which the intraocular lens is inserted.

If the optic130may be molded directly onto the haptic120, the haptic120may be first expanded or contracted radially by an external force, prior to molding. The optic130may then be molded directly onto the expanded or contracted haptic120. After molding, the external force may be removed, and the haptic may return to its original size or fairly close to its original size, forming radial stresses within the optic130.

It is desirable that the haptic be made from a stiffer material than the optic, so that any distorting forces induced by the zonules or capsular bag are transmitted efficiently through the haptic to the optic, and efficiently change the shape of the optic. It is also desirable that the haptic and the optic have similar or essentially equal refractive indices, which would reduce any reflections at the interfaces between the haptic and the optic.

FIGS. 19 through 21show another exemplary haptic190in various plan views, both with and without an optic200.FIG. 19is a plan drawing of a haptic190.FIG. 20is a plan drawing of the haptic190ofFIG. 19, with an optic200.FIG. 21is the plan drawing of the haptic190and optic200ofFIG. 20, with additional hidden lines.

The haptic190ofFIGS. 19 through 21has eight filaments denoted by elements191athrough191h. Alternatively, the haptic190may have more or fewer than eight filaments. Filaments191a-hmay have non-uniformities along their lengths, such as width variations, height variations, and/or holes192a-h.

The holes192a-hmay desirably alter the mechanical properties of the respective filaments, so that a given zonular force may be transmitted efficiently into a distortion of the optic. The holes192a-hmay be triangular in shape, or may be any other suitable shape, such as round, square, rectangular, polygonal, and may optionally have one or more rounded corners and/or edges. Each hole may optionally vary in profile along its depth. There may optionally be more than one hole per filament. There may optionally be differing numbers of holes for different filaments. There may optionally be differently-shaped holes on the same filament.

Unlike the filaments121a-hofFIGS. 12 through 18, the filaments191a-hare connected at both their outermost edge and their innermost edge. The filaments191a-hare joined at an outer annular ring193and an inner annular ring194. The inner annular ring194may lie within the circumference of the optic200, as inFIGS. 19 through 21. Alternatively, the inner annular ring194may lie outside the circumference of the optic200, or may straddle the circumference of the optic200.

The dimensions of the inner annular ring194, specifically, the inner and outer diameters of the inner annular ring194, may be determined in part by the stiffness of the haptic190and/or the stiffness of the optic200. For instance, a stiffer haptic may require relatively little material, and the ratio may be fairly close to 1. Alternatively, a less stiff haptic may require more material, and the ratio may deviate significantly from 1.

FIGS. 22 through 26show another exemplary haptic220in various plan views, with an optic230.FIG. 22is a top-view plan drawing of a haptic220with an optic230.FIG. 23is a side-view plan drawing of the haptic220and optic230ofFIG. 22.FIG. 24is a side-view cross-sectional drawing of the haptic220and optic230ofFIG. 22.FIG. 25is a plan drawing of the haptic220and optic230ofFIG. 22.FIG. 26is a cross-sectional drawing of the haptic220and optic230ofFIG. 22.

The haptic220ofFIGS. 22 through 26has a more complex shape than the haptics shown inFIGS. 12 through 21. The haptic220has eight filaments221a-h, each of which has one end attached to an inner annular ring222and has the opposite end attached to an outer annular ring223. Alternatively, the haptic220may have more or fewer than eight filaments. In contrast with the haptics ofFIGS. 12 through 21, the haptic220contacts the capsular bag of the eye at one or more points along the filaments221a-hbetween the inner and outer annular rings222and223. In some embodiments, the filaments221a-hmay loop back on themselves, and may contact the capsular bag at one or more extrema along the loop, rather than at the outer annular ring223.

As with the inner annular ring194ofFIGS. 19 through 21, the inner annular ring222may lie inside the circumference of the optic230, once the optic230is placed within the haptic220, may lie outside the circumference of the optic230, or may straddle the circumference of the optic230.

In some embodiments, such as the disc-shaped intraocular lenses shown inFIGS. 12 through 21, the haptic filaments engage an equatorial region of the capsular bag. In many of these embodiments, the optical power of intraocular lens may be selected to provide a disaccommodative bias, although some embodiments may alternatively provide an accommodative bias.

In other embodiments, the haptic filaments may engage substantially the entire capsular bag, rather than just the equatorial region of the capsular bag. In some of these embodiments, the filaments may extend generally in a plane that includes the optical axis of the lens, and there may be uncontacted portions of the capsular bag in the regions between the filaments. In many of these embodiments, the intraocular lens has an accommodative bias, although some embodiments may alternatively use a disaccommodative bias.

For the designs ofFIGS. 12 through 26, the haptic may be pre-stressed, and the optic nay then be molded onto or attached to the haptic while the haptic is in the pre-stressed state. For instance, the haptic may be compressed or expanded radially prior to placing the optic within the haptic. The pre-stress may then be removed, and the lens may be allowed to relax to its substantially unstressed state, or a “natural” state. For a haptic that is much stiffer than the optic, the haptic may expand/contract by nearly the full compression/expansion amount, and the optic becomes expanded/compressed about its equator. In its expanded state, the optic is under radial tension.

This pre-stress may help reduce or eliminate buckling of the optic, if the optic is compressed. It may also reduce the need for a thicker optic for maximizing the power change for a given external force (e.g., an ocular force produced by the ciliary muscle, the zonules, and/or the capsular bag of the eye.) Furthermore, the pre-stress may allow for a so-called “fail-safe” design that allows only a certain amount of power change during accommodation; the lens may minimize the power change beyond a prescribed accommodation range. In addition, the pres-stress may reduce the amount of force required for a given power change.

The description of the invention and its applications as set forth herein is illustrative and is not intended to limit the scope of the invention. Variations and modifications of the embodiments disclosed herein are possible, and practical alternatives to and equivalents of the various elements of the embodiments would be understood to those of ordinary skill in the art upon study of this patent document. These and other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.