Contact lens stabilization designs

Abstract

An ophthalmic lens including an anterior surface and a posterior surface meeting at a lens edge, a central optic zone providing optical correction for a user, a peripheral zone extending from said optic zone radially to said lens edge, and at least a first patterned zone positioned within the peripheral zone including a plurality of circumferential grooves or ridges.

Description

[0001]

[0002] CONTACT LENS STABILIZATION DESIGNS

[0003] Field of the Invention

[0004] The present invention relates to ophthalmic lenses having a stabilization design that incorporates patterned surfaces, and has particular application to toric soft contact lenses.

[0005] Background

[0006] Myopia or nearsightedness is an optical or refractive defect of the eye wherein rays of light from an image focus to a point before they reach the retina. Myopia generally occurs because the eyeball or globe is too long or the cornea is too steep. A minus or negative powered spherical lens may be utilized to correct myopia. Hyperopia or farsightedness is an optical or refractive defect of the eye wherein rays of light from an image focus to a point after they reach or behind the retina. Hyperopia generally occurs because the eyeball or globe is too short or the cornea is too flat. A plus or positive powered spherical lens may be utilized to correct hyperopia.

[0007] Astigmatism is an optical or refractive defect in which an individual's vision is blurred due to the inability of the eye to focus a point object into a focused image on the retina. Corneal astigmatism is caused by a non-rotationally symmetric curvature of the cornea. A normal cornea is spherical whereas in an individual with corneal astigmatism the cornea is more curved or steeper in one direction than another, thereby causing an image to be stretched out into two-line foci rather than focused to a single point. A cylindrical lens rather than a spherical lens may be utilized to resolve astigmatism.

[0008] Corneal astigmatism may be corrected using a hard or rigid gas permeable contact lens. In this case, a fluid or tear film or lens may exist between the posterior surface of the rigid contact lens and the cornea. This fluid or tear lens follows or assumes the shape of the back surface of the contact lens. Since the index of refraction of the fluid or tear lens is nearly a match for the cornea, the corneal toricity is optically neutralized or reduced. In these cases, a toric lens will not be required. However, rigid gas permeable contact lenses and hard contact lenses are generally less comfortable than soft or hydrogel contact lenses. Since soft or hydrogel contact lenses wrap around the cornea, a fluid lens is generally not found, and the tear fluid more closely resembles a thin film. In this case, a toric lens design is required.

[0009] To address the asymmetry of the cornea in astigmatic patients, toric soft contact lenses have two different powers in two orientations that are perpendicular to one another. Essentially, a toric lens has one power, spherical, for correcting myopia or hyperopia, and one power, cylinder, for correcting astigmatism built into a single lens. All contact lenses tend to rotate on eye due to the forces exerted on the contact lens by the eyelids during blinking as well as eyelid and tear film movement. For spherical lenses this is not an issue, but for toric lenses rotation may provide sub-optimal vision if proper alignment is not maintained. For this reason, toric soft contact lenses include mechanical features built into the lens to provide angular stability during wear ("stabilization zones" or "stabilization design"). There are two distinct approaches used by soft contact lens manufacturers: unidirectional ballast-type lenses (prism ballast and peri-ballast) where stability is provided by a thick zone located at the bottom peripheral region of the lens and bidirectional designs where the angular stability is provided by maximizing the lens-eyelid interaction via two stabilization regions located along the horizontal meridian of the lens as shown, for example, in U.S. Patent No. 6,939,005 Although stabilization zones of these types work to minimize angular rotation on eye, there is a tradeoff between optimizing comfort and optimizing angular (rotational) stability of the lens, since thicker stabilization zones cause increased lens awareness. Increased awareness typically translates to a decrease in lens comfort, and for this reason there is a limit on the thickness that can be employed. Additionally, the contact lens design has to accomplish two things; namely, to rotate to the proper orientation on insertion and to maintain that orientation through the wear period. A static design that relies solely on thickness variation requires tradeoffs in performance between these two modes.

[0010] U.S. Patent No. 9,927,633 discloses a toric contact lens design where the stabilization zones incorporate surface modified zones rather than incorporating designs relying exclusively on varying thickness. It would be desirable to provide improved designs for lens stabilization that incorporate into the lens specifically designed surface patterns that further optimize, alone or in combination with optimized mechanical stabilization zone designs, rotational stability and lens comfort.

[0011] Summary

[0012] Provided herein is an ophthalmic lens including an anterior surface and a posterior surface meeting at a lens edge, a central optic zone providing optical correction for a user, a peripheral zone extending from said optic zone radially to said lens edge, and at least a first patterned zone positioned within said peripheral zone, where the patterned zone includes a plurality of circumferential grooves or ridges. The grooves or ridges may each be defined by a height, a width and a pitch therebetween.

[0013] In alternate embodiments, the height may be less than 0.050 mm, less than 0.040 mm, less than 0.030 mm or less than 0.010 mm. The height, width and pitch may be the same for each of the ridges or grooves, or may be different. The first patterned zone may have at least three circumferential grooves or ridges at successively increasing radii from the lens center.

[0014] In other embodiments, the plurality of circumferential grooves or ridges may extend over an angular span of 60 to 150 degrees, the pitch may range from 0.010mm to 0.050mm and / or the average moment of the lens during blink on eye may be between 0.30 N.pm and 1.10 N.pm.

[0015] The at least one patterned zone may be positioned on a lateral side of the lens, and may be symmetric or asymmetric relative to the horizontal meridian. There may be first and second patterned zones positioned on respective first and second lateral sides of the lens, which also may be asymmetric or symmetric relative to the horizontal meridian. In one embodiment, the maximum thickness of the lens is located in the peripheral zone along the horizontal meridian.

[0016] Also provided is an ophthalmic lens including an anterior surface and a posterior surface meeting at a lens edge and having a thickness differential therebetween, a central optic zone providing optical correction for a user, a peripheral zone extending from said optic zone radially to the lens edge, and at least a first stabilization zone positioned within the peripheral zone. The lens a maximum thickness differential within said stabilization zone, and the stabilization zone further includes a plurality of circumferential grooves or ridges.

[0017] Brief Description of the Drawings

[0018] Fig. la and lb illustrate different strategies for incorporating patterned regions or zones as described herein;

[0019] Fig. 2a illustrates an exemplary pattern according to the present disclosure;

[0020] Fig. 2b is an enlarged view of the pattern of Fig. 2a;

[0021] Fig. 3a and 3b illustrate exemplary angular spans according to the present disclosure;

[0022] Fig. 4 illustrates an exemplary inclination angle and fillets for a pattern according to the present disclosure;

[0023] Fig. 5 illustrates an exemplary ramp angle according to the present disclosure;

[0024] Fig. 6 is a table illustrating simulation results for various exemplary patterned regions or zone designs;

[0025] Figs. 7a and 7b, Figs. 8a and 8b, Figs. 9a and 9b, Figs. 10a and 10b, and Figs. 11a and lib are thickness differential plots and thickness differential heat maps respectively for various patterned designs according to the present disclosure; and

[0026] Fig. 12 illustrates an exemplary prior art lens having dual stabilization zones that vary in thickness.

[0027] Detailed Description

[0028] In a soft contact lens (SCL) / eye system, there isn't any surface-to-surface contact because a tear film exists between the eyelid and the SCL (pre-lens tear film), and between the SCL and the surface of the cornea / sclera (post-lens tear film). Hence, the principle driving the motion of the SCL on eye is that of elasto-hydrodynamic lubrication (EHL). The lenses described herein are specifically designed to optimize stability and comfort using principles of EHL.

[0029] There are two main strategies that can be employed to enhance SCL rotational stability with surface patterns when EHL is taken into account: design zones that decrease EHL (strategy A) or design zones that increase EHL (strategy B). Given the already high lubricity of the SCL interface, strategy A has the potential to create higher differential EHL zones, but strategy B has the potential to provide better comfort.

[0030] For strategy A, EHL can be decreased through two effects: (1) a higher drag for low tear film thickness; and (2) a higher viscosity with low tear film thickness. In other words, strategy A works by creating surface patterns that will reduce the local thickness of the tear film and create locally higher friction forces. These effects are enhanced by employing open patterns that allow the tear film to flow under the eyelid pressure. Examples of these include pimples, ridges or channels / grooves which can be employed in peripheral regions (i.e., zones 101 illustrated in Fig. la) of the lens to create rotational torque when the zones are in the lid-lens interface (i.e., when the lens is mis-rotated).

[0031] For strategy B, surface patterns can be created that increase the tear film thickness, thus increasing EHL, using the opposite of the two principles of strategy A. The effects are created using closed patterns, such as indents or dimples, that create locally lower frictional forces. These features enhance EHL by (1) micro-hydrodynamic effect, (2) entrapping additional lubricant into the contact area; and (3) providing micro-reservoirs that supply lubricant to the interface. One embodiment is to create EHL zones in the vertical front surface peripheral region of the SCL (i.e., zones 102 in Fig. lb), thus creating rotational torque when the zones are not located in the lid-lens interface.

[0032] Strategy C is a combination of A and B, where enhanced EHL is created in some regions of the lens and reduced EHL in others. For example, the vertical periphery of the SCL could have EHL zones, while the horizontal zones could have anti-EHL zones. Alternatively, or in addition, the back surface of the lens could also employ EHL zones to increase the rotational speed of the lens. Another combination alternative would be to take advantage of a non-rotationally symmetric shape of the pattern. For example, when the lens is not properly oriented the shape of the pattern creates an anti-EHL effect, thus increasing rotational force, but when the lens is properly oriented, the orientation of the pattern creates enhanced EHL, reducing rotational forces.

[0033] In order to develop optimized lens designs using patterned regions or zones that leverage EHL effects in the eye, an EHL computational model was developed to optimize the location, distribution and size of the patterned zones. Current EHL computation models are not suitable for use in modeling EHL zones of the type described herein, as they were designed for larger and thicker zones designs (such as mechanical thickness variations in current mechanical stabilization zone designs), and not mechanical design variations as seen in patterned surfaces that are much smaller in nature.

[0034] This new model calculates the dissipated energy E difference between the left and right side of the eyelid (EL R) during down-blink and up-blink. If (EL R) is positive, the torque is counterclockwise, and has the effect of rotating the lens counterclockwise. Conversely, if (EL R) is negative, the effect of the imparted torque is to rotate the lens clockwise. The total amount of displacement per blink is a sum of the displacement due to (EL R) and the displacement due to the static lid pressure (during the interblink period). As such, the metric to optimize is the time- weighted torque:

[0035] Tq = ti * Tqi + tbk* Tqbk, where Tqis the total torque during a full blink in N.pm.s, Tq; is torque imparted during the interblink period, Tqbk is the torque imparted during the down blink and the up blink, tj is the duration in seconds of the interblink, and tbk is the time in seconds of the down blink and the up blink. An example is provided below:

[0036] Example:

[0037] Blink - 0.26 seconds

[0038] Interblink - 3.00 seconds

[0039] Torque - calculated Lens with thick stabilization zones and patterns ~ (0.3 * 3.0 + 4.5 * 0.26) [ N. / m.s] - 2.1 [ N. / m.s]

[0040] Lens with pattern only =(0.0 * 3.0 + 3.2 * 0.26) [ N. / m.s] - 0.8 [ N.jum.s]

[0041] For patterned zones of the type described in Designs 1-3, Tqi is set equal to zero, as there is minimal, if any, impact from these zones during the interblink period. For surface patterns, the geometry of these features is defined by multiple parameters, including the type of features (i.e., parallel ridges, grooves, chevrons etc.), the number of ridges or channels / grooves, heigh, width, pitch, angular span, inclination, and surface smoothing (i.e., fillet). For example, exemplary circumferential ridges are shown in Fig. 2a. A plurality of ridges 200a, 200b, 200c are positioned circumferentially around a center point of the lens, and at successive, incremental radial distances. The ridges and channels are defined as shown in Fig. 2b by height (h), width (w) and pitch (p). For simplicity, the same nomenclature is used herein for both ridges and channels where, for example, "height" of a ridge is the dimension extending beyond the surface of the lens, and "height" of a groove / channel is the dimension extending within or into the surface of the lens.

[0042] Angular span A is illustrated in Figs. 3a and 3b, where Fig. 3a illustrates an angular span A of 68 degrees and Fig. 3b illustrates an angular span A of 40 degrees. Fig. 4 illustrates an exemplary inclination, where height h of the ridge is shown on the y-axis and distance on the x- axis. In this embodiment, the transition to the ridge begins at point 400, and reaches a linear inclination 402 of 20 degrees. An inferior fillet radius R of 0.030 mm forms the transition from the point 400 to the 20 degree inclination over a distance of 0.0217 mm. A superior fillet radius R2 forms the transition from the inclination to the top of the ridge. The "ramp angle" RA of the ridges or grooves is illustrated in Fig. 5, and defines the transition at each of first 502 and second 504 ends of the ridge or groove from the no-feature surface to the full height features (ridge or channel). The illustrated embodiment reflects a ramp angle of 10 degrees.

[0043] Using the equations and pattern geometries described above, optimal configurations or a range of configurations, can be determined that maximize Tqbk (the torque imparted during the down blink and the up blink). Simulation results for various groove and ridge dimensions and geometries are set forth in Fig. 6. As can be seen in columns 601 and 602, ridges or grooves having the same dimensions result in different average moments experienced by the lens during blink (i.e., 2.02 N.pm versus 1.29 N.pm). Similarly, where all other dimensions are held constant, merely changing the height of a groove / ridge will affect the average moment as shown in columns 603 and 604, as will changing other dimensions as can be seen in Fig. 6.

[0044] Leveraging the principles and modeling described above, patterned designs can be applied to any exemplary contact lens having a central optic zone that includes sphere and cylinder correction, and a peripheral zone surrounding the optic zone. The patterned designs described in detail below have circumferential ridges or grooves over an angular span of 120 degrees, which is centered on the horizontal axis. The angular span, however, may vary from 60 to 150. Further, although the embodiments described in detail below have two patterned zones positioned on lateral first and second sides of the lens and centered around the horizontal axis (symmetric), other embodiments may include a single patterned zone, may include different sizes or designs in patterned zones in the respective lateral sides, or one or more zones that are offset from the horizontal meridian or positioned elsewhere (i.e., on or near the vertical meridian).

[0045] Design 1 is illustrated in Figs. 7a-b for a -3.0D lens. Fig. 7a illustrates the radial thickness differential of the lens, with line 700 illustrating the radial thickness (y-axis) of the lens across the radial distance (x-axis) along the vertical meridian. The maximum thickness is 0.2300 mm located in the outer periphery of the lens. Line 702 represents the radial thickness from the lens center to the lens edge along the horizontal meridian and carries the structured pattern in the peripheral region. Line 704 represents the difference in thickness between the vertical meridian and horizontal meridian and provides the pattern depth. Fig. 7b is thickness map of Design 1. Design 1 further has the following design features:

[0046] Pattern Type: Channels

[0047] Number of Channels: 3

[0048] Start of first channel: 4.90mm

[0049] Channel Width: 0.300mm

[0050] Channel Depth: 0.040mm

[0051] Pitch: 0.250mm

[0052] Inclination: 40 Degrees

[0053] Superior Fillet: 0.010 mm Inferior Fillet: 0.100 mm

[0054] Span: 70 degrees

[0055] Ramp Angle: 25 degrees

[0056] Average moment during blink: 0.721 N.pm

[0057] Span as set forth above is the angular range over which the channels exist. The pattern is blended along the angular direction at each end over a 20 degree span (i.e., 20 degree ramp angle), leaving the full pattern over an 80 degree span. According to the model, the average moment experienced during blink as a consequence of the patterned design for Design 1 is 0.721 N.pm.

[0058] Design 2 also includes circumferential grooves, but with the following design features:

[0059] Pattern Type: Channels

[0060] Number of Channels: 3

[0061] Start of first channel: 4.90mm

[0062] Channel Width: 0.300mm

[0063] Channel Depth: 0.010mm

[0064] Pitch: 0.400mm

[0065] Inclination: 30 degrees

[0066] Superior Fillet:0.010mm

[0067] Inferior Fillet: 0.100 mm

[0068] Span: 70 degrees

[0069] Ramp Angle: 25 degrees

[0070] Average moment during blink: 0.085 N. pm

[0071] The radial thickness differential for Design 2 is shown in Fig. 8a, and a thickness map in Fig. 8b. Similar to Design 1 of Fig. 7a, the maximum thickness differential is 0.230mm. Lines 800, 802 and 804 are analogous to the representations of lines 700, 702 and 704 in Fig. 7a.

[0072] Design 3 includes five circumferential ridges rather than three channels as in Designs 1 and 2.

[0073] Pattern Type: Ridges

[0074] Number of Channels: 5

[0075] Start of first channel: 4.90mm

[0076] Channel Width: 0.200mm

[0077] Channel Depth: 0.030mm Pitch: 0.150mm

[0078] Inclination: 40 degrees

[0079] Superior Fillet: 0.020 mm

[0080] Inferior Fillet: 0.100 mm

[0081] Span: 70 degrees

[0082] Ramp Angle: 25 degrees

[0083] Average moment during blink: 1.021 N.pm

[0084] Analogous thickness differential and thickness heat maps are shown in Figs. 9a and 9b respectively.

[0085] Designs 1-3 described above depend exclusively on blinking for rotational stability and do not include mechanical stabilization zones having increased thickness. Performance can be further improved in combination with traditional mechanical stabilization features that also contribute to rotational stability between blinks (i.e., torque Tqi during the interblink period is not zero). As noted previously, for known dual stabilization zone designs such as that shown in Fig. 12, rotational stability typically improves as thickness differential in the stabilization zones increases, but comfort is adversely affected as thickness differential increases. Adding a patterned designs such as described herein in combination with a thickness differential in the stabilization zones, achieves similar rotational stability performance with thinner mechanical stabilization zones, further improving patient comfort.

[0086] Design 4 is a combination (or hybrid) stabilization zone design where a patterned design is applied to a -3.0D toric lens that is commercially available from Johnson & Johnson Vision Care, Inc. under the name Acuvue® Oasys 1 Day for Astigmatism. The toric lens has a thickness differential of 0.190 mm, with the pattern design of Design 1 applied within the stabilization zones. The thickness differential map for this lens is illustrated in Fig. 10a, and the thickness heat map in Fig. 10b. The average moment during blink as calculated is 0.328 N.pm.

[0087] Design 5 is also a hybrid lens identical to Design 4 other than the lens having a maximum thickness differential of 0.100 mm rather than 0.190 mm. The thickness differential for this lens is shown in Fig. 11a and the thickness heat map in Fig. lib. The average moment during blink is calculated to be 0.558 N.pm. As can be seen from the examples described in detail above, applying patterned designs in zones of a soft contact lens that are specifically designed to alter EHL properties of the lens can achieve rotational stability for toric lenses. When applied alone, or in combination with a mechanical stabilization zone design that varies in thickness, pattern designs of the type described herein may improve the combination of performance and comfort for patients or users.

[0088] Although shown and described are preferred embodiments, it is apparent that departures from specific designs and methods described and shown will suggest themselves to those skilled in the art and may be used without departing from the spirit and scope of the invention. The present invention is not restricted to the particular constructions described and illustrated, but should be constructed to cohere with all modifications that may fall within the scope of the appended claims.

Claims

What is Claimed is:

1. An ophthalmic lens, comprising: an anterior surface and a posterior surface meeting at a lens edge, a central optic zone providing optical correction for a user, a peripheral zone extending from said optic zone radially to said lens edge, and at least a first patterned zone positioned within said peripheral zone, said patterned zone including a plurality of circumferential grooves or ridges.

2. The ophthalmic lens according to claim 1, wherein said grooves or ridges are each defined by a height, a width and a pitch therebetween.

3. The ophthalmic lens according to claim 2, wherein said height is less than 0.050 mm.The ophthalmic lens according to claim 3, wherein said height is less than 0.040mm4. The ophthalmic lens according to claim 4, wherein said height is less than 0.030mm.

5. The ophthalmic lens according to claim 4, wherein said height is less than 0.010mm.

6. The ophthalmic lens according to claim 2, wherein said height, width and pitch are the same for each of plurality of circumferential grooves or ridges.

7. The ophthalmic lens according to claim 1, wherein said first patterned zone further comprises at least three circumferential grooves or rides at successively increasing radii from a lens center.

8. The ophthalmic lens according to claim 7, having five circumferential ridges or grooves.

9. The ophthalmic lens according to claim 7, having three circumferential ridges or grooves.

10. The ophthalmic lens according to claim 1, wherein said plurality of circumferential grooves or ridges extend over an angular span of 60 to 150 degrees.

11. The ophthalmic lens according to claim 2, wherein said pitch ranges from 0.010mm to 0.050mm.

12. The ophthalmic lens according to claim 1, wherein an average moment of said lens during blink on eye is between 0.30 and 1.100.

13. The ophthalmic lens according to claim 1, wherein said at least one patterned zone is positioned on a lateral side of said lens.

14. The ophthalmic lens according to claim 13, wherein said at least one patterned zone is symmetrical relative to a horizontal meridian.

15. The ophthalmic lens according to claim 13, wherein said at least one patterned zone is asymmetrical relative to a horizontal meridian.

16. The ophthalmic lens according to claim 13, having first and second patterned zones positioned on first and second lateral sizes of said lens respectively.

17. The ophthalmic lens according to claim 16, wherein said first and second patterned zones are symmetrical relative to a horizontal meridian.

18. The ophthalmic lens according to claim 17, wherein a maximum thickness of said lens is located in said peripheral zone along said horizonal meridian.

19. The ophthalmic lens according to claim 16, wherein said first and second patterned zones are asymmetrical relative to a horizontal meridian.

20. The ophthalmic lens according to claim 19, wherein a maximum thickness of said lens is located in said peripheral zone along said horizontal meridian.

21. An ophthalmic lens, comprising: an anterior surface and a posterior surface meeting at a lens edge, wherein said lens has a thickness differential between said anterior and posterior surfaces, a central optic zone providing optical correction for a user, a peripheral zone extending from said optic zone radially to said lens edge, and at least a first stabilization zone positioned within said peripheral zone,wherein said lens has a maximum thickness differential within said stabilization zone, and wherein said stabilization zone further comprises a plurality of circumferential grooves or ridges.

22. The ophthalmic lens according to claim 21, wherein said grooves or ridges are defined by a height, a width and a pitch therebetween.

23. The ophthalmic lens according to claim 22, wherein said height is less than 0.050 mm.

24. The ophthalmic lens according to claim 23, wherein said height is less than 0.040mm25. The ophthalmic lens according to claim 24, wherein said height is less than 0.030mm.

26. The ophthalmic lens according to claim 25, wherein said height is less than 0.010mm.

27. The ophthalmic lens according to claim 22, wherein said first patterned zone further comprises at least three circumferential grooves or ridges at successively increasing radii from a center of said lens.

28. The ophthalmic lens according to claim 27, having five circumferential ridges or grooves.

29. The ophthalmic lens according to claim 27, having three circumferential ridges or grooves.

30. The ophthalmic lens according to claim 21, wherein said plurality of circumferential grooves or ridges extend over an angular span of 60 to 150 degrees.

31. The ophthalmic lens according to claim 22, wherein said pitch ranges from 0.010 to 0.050mm.

32. The ophthalmic lens according to claim 21, wherein the average moment during blink of said lens on eye ranges from 0.30 N.pm and 1.100 N.pm.

33. The ophthalmic lens according to claim 21, wherein said at least one patterned zone is positioned on a lateral side of said lens.

34. The ophthalmic lens according to claim 33, wherein said at least one patterned zone is symmetrical relative to a horizontal meridian.

35. The ophthalmic lens according to claim 33, wherein said at least one patterned zone is asymmetrical relative to a horizontal meridian.

36. The ophthalmic lens according to claim 33, having first and second patterned zones positioned on first and second lateral sizes of said lens respectively.

37. The ophthalmic lens according to claim 36, wherein said first and second patterned zones are symmetrical relative to a horizontal meridian.

38. The ophthalmic lens according to claim 37, wherein a maximum thickness of said lens is located in said peripheral zone along said horizonal meridian.

39. The ophthalmic lens according to claim 36, wherein said first and second patterned zones are asymmetrical relative to a horizontal meridian.

40. The ophthalmic lens according to claim 39, wherein a maximum thickness of said lens is located in said peripheral zone along said horizontal meridian.

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