Intraocular lens

Abstract

An intraocular lens (IOL) is provided comprising one or more haptic portions and an optical portion. The IOL has a principal axis defined by the one or more haptic portions and an optical axis defined by the optical portion. The optical axis of the IOL is tilted with respect to the principal axis of the IOL. Accordingly, the tilt of a patient's natural crystalline lens may be better replicated post-cataract surgery.

Description

INTRAOCULAR LENSTECHNICAL FIELD

[0001] The present invention relates to an intraocular lens, more specifically to an intraocular lens having an incorporated tilt of the optical axis.BACKGROUND

[0002] Intraocular lenses (lOLs) are artificial lenses used in ophthalmic surgery to replace the eye's natural lens or to be inserted into the eye in addition to the eye’s natural lens. This surgical procedure is typically performed during cataract surgery, a common eye-related condition where the natural lens becomes cloudy and impairs vision. lOLs are useful because they restore clear vision after the removal of a clouded lens, allowing individuals to regain their visual acuity and quality of life.

[0003] lOLs come in various designs and materials to cater to different patient needs. They are typically made from biocompatible materials like silicone or acrylic, which are well-tolerated by the eye and minimize the risk of complications. One of the key features of lOLs is their ability to correct refractive errors. Some lOLs are Monofocal, meaning they provide clear vision at a specific distance (either near or far), and patients may still need glasses for other distances. On the other hand, multifocal or other accommodative lOLs may be designed to allow for clear vision at multiple distances, reducing dependence on glasses for tasks like reading or driving, while toric lOLs may be designed to correct astigmatism, a common condition where the cornea or lens is irregularly shaped, leading to blurred or distorted vision.

[0004] One limitation of current lOLs is their inability to account for the natural tilt and position variability of the human lens. The natural lens in the eye is not perfectly centred or aligned; it usually has a slight tilt or decentration. This anatomical variation is not taken into consideration during current IOL implantation processes. As a result, despite the successful restoration of visual acuity, the lack of alignment with the individual's unique lens tilt can lead to a reduction in stereopsis, meaning the patient is less able to perceive depth and three-dimensionality. This can affect tasks requiring fine depth perception, such as judging distances or performing intricate hand-eye coordination activities.

[0005] The present invention provides an IOL which is capable of aligning with an individual’s natural lens tilt, leading to improved patient stereopsis for patients undergoing ophthalmic surgery.SUMMARY OF THE INVENTION

[0006] Aspects of the invention are set out in the accompanying claims.

[0007] An intraocular lens (IOL) comprising: one or more haptic portions for securing the IOL to an eye of a subject, wherein the one or more haptic portions define a principal axis of the IOL; and an optical portion having an optical axis; wherein the optical axis of the optical portion is tilted with respect to the principal axis defined by the one or more haptic portions. Accordingly, the preoperative tilt of the natural crystalline lens may be more closely replicated, thereby providing improved stereopsis.

[0008] In some examples, the tilt of the optical axis with respect to the principal axis has a magnitude of at least 0.5 degrees. Furthermore, in some examples the tilt of the optical axis with respect to the principal axis is between 0.5 degrees and 9.0 degrees. As such, the lOLsaccording to the present disclosure are able to accommodate substantially any natural crystalline lens tilt.

[0009] In some examples, the one or more haptic portions comprise an annulus, wherein the optical portion is located within the annulus. As such, a flexible design may be provided which provides secure attachment of the optical portion and the haptic portion, while allowing the optical portion to be tilted with respect to the principal axis. In some cases, the annulus may be tilted with respect to the principal axis of the IOL, however in other cases the principal axis may be defined by the annulus.

[0010] In some cases, the optical portion is integrally formed with the one or more haptic portions. Alternatively, according to some examples the optical portion is configured to be removable from the annulus. As such, the optical portion can be easily swapped or adjusted, e.g. to adjust lens power for a given patient, thereby providing flexibility. In some cases, the annulus comprises a first surface configured to support the optical portion, wherein the first surface is configured to be located on a first side of the optical portion. As such, the optical portion may be easily removed from the annulus when required, while still being supported within the over IOL structure. Additionally, in some cases the annulus further comprises a second surface configured to support the optical portion, wherein the second surface is configured to be located on a second side of the optical portion opposite the first portion. As such, the optical portion may be securely held within the annulus.

[0011] In some examples, the optical axis is tilted towards an inferior-nasal, nasal and / or superior-nasal region of the IOL. As such, the tilt direction of a patient’s natural crystalline lens may be replicated.

[0012] According to particular examples, the IOL comprises: the inferior-nasal region configured to correspond to an inferior-nasal region of the eye of the subject; a nasal region configured to correspond to a nasal region of the eye of the subject; and a superior-nasal region configured to correspond to a superior nasal region of the eye of the subject. Advantageously, the optical axis may be tilted towards the inferior-nasal region of the IOL such that the inferior-nasal region of the IOL is configured, when secured to the eye of the subject, to be located further from a pupil of the eye of the subject than the superior-temporal region of the eye of the subject when placed behind the iris. Alternatively, the optical axis may be tilted towards the inferior-nasal region of the IOL such that the inferior-nasal region of the IOL is configured, when secured to the eye of the subject, to be located near from a pupil of the eye of the subject than the superior-temporal region of the eye of the subject when placed in front of the iris.

[0013] In some cases, the optical axis is defined by an axis of the one or more haptic portions. Furthermore, in some examples, the optical axis is defined by one or more distal ends of the one or more haptic portions. As such, the tilted lOLs according to the present example may be incorporated into various IOL and haptic designs.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Embodiments of the invention will now be described, by way of example only, with reference to the following figures. In accordance with one (or more) embodiments of the present invention the figures show the following:

[0015] Figure 1 illustrates an example of an intraocular lens (IOL) for insertion into a patient’s eye. The IOL includes an optical portion and one or more haptics for securing the IOL in place.

[0016] Figure 2 illustrates a simplified diagram of the human eye, including the natural crystalline lens, which may be replaced by IOL, for example in cataract surgery.

[0017] Figure 3 illustrates the natural tilt of crystalline lenses of the eye relative to the corneal topographic optical axis.

[0018] Figure 4 illustrates different regions of the eye, as define within ophthalmology.

[0019] Figure 5 illustrates a top-down view of an IOL according to an example of the present disclosure.

[0020] Figures 6A-E illustrates side-on views of various example lOLs according to the present disclosure.

[0021] Figures 7A and 7B illustrate perspective views of an example IOL according to the present disclosure.

[0022] Figures 8A-D illustrate a number of example haptic designs compatible with IOL according to the present disclosure.

[0023] Figure 9 illustrates a graph of measured preoperative lens tilt of a patient’s natural crystalline lens compared with the measured postoperative tilt of an IOL.

[0024] Figure 10 illustrates a flowchart for an example method for determining the tilt of the optical portion of an IOL according to an example of the present disclosure.

[0025] Figure 11 illustrates a flowchart for an example method for determining the properties of an IOL according to an example of the present disclosure.

[0026] Like reference characters refer to like elements throughout the figures and description.

[0027] Any reference to prior art documents in this specification is not to be considered an admission that such prior art is widely known or forms part of the common general knowledge in the field. As used in this specification, the words “comprises”, “comprising”, and similar words, are not to be interpreted in an exclusive or exhaustive sense. In other words, they are intended to mean “including, but not limited to”. The invention is further described with reference to the following examples. It will be appreciated that the invention as claimed is not intended to be limited in any way by these examples. It will also be recognised that the invention covers not only individual embodiments but also combination of the embodiments described herein.

[0028] The various embodiments described herein are presented only to assist in understanding and teaching the claimed features. These embodiments are provided as a representative sample of embodiments only, and are not exhaustive and / or exclusive. It is to be understood that advantages, embodiments, examples, functions, features, structures, and / or other aspects described herein are not to be considered limitations on the scope of the invention as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the spirit and scope of the claimed invention. Various embodiments of the invention may suitably comprise, consist of, or consist essentially of, appropriate combinations of the disclosed elements, components, features, parts, steps, means, etc., other than those specifically described herein. In addition, this disclosure may include other inventions not presently claimed, but which may be claimed in future.DETAILED DESCRIPTION

[0029] Eyes are susceptible to various conditions which can impact visual acuity (a measure of the ability of the eye to distinguish shapes and the details of objects at a given distance). One example is cataracts, where the eye’s natural lens becomes clouded, leading to blurred or hazy vision and eventual visual impairment if left untreated. In such cases, the natural lens may be replaced with an artificial lens, called an intraocular lens (IOL). The replacement of the natural lens with an IOL may restore clear vision for the patient and allow the patient to regain visual acuity. Figure 1 shows an example of an IOL 100 used in ophthalmic surgery. The IOL 100 includes an optical portion 110 and haptics 120. The optical portion 110 is the portion of the IOL 100 responsible for focusing light onto the retina. It is typically made of a clear, biocompatible material, often acrylic or silicone. The design of the optical portion 110 may determine e.g. whether the IOL 110 is monofocal (focused at one distance), multifocal (focused at multiple distances), toric (correcting astigmatism), or accommodating (able to change shape slightly for focusing). The haptics 120 are portions of the IOL 100 configured to secure or fix the IOL 100 within the eye. The haptics 120 are attached to the optical portion 110 and may include, for example, one or more appendages attached to the optical portion 110. The haptics 120 are attached to the optical portion 110 at one or more haptic junctions 130. The haptics help to stabilize the IOL 100 within the eye and attempt to ensure it remains in the correct position. The haptics 120 are usually made of the same biocompatible material as the optical portion 110.

[0030] The optical portion 110 of the IOL 100 has a particular lens power, which is the refractive power of the optical portion 110 and hence IOL 100. The lens power determines the degree to which the IOL 100 will focus light in order to provide clear vision, and may be measured in dioptres. Lens power for an IOL 100 may be chosen based on factors including the patient's eye measurements (such as axial length and corneal curvature) and the desired post-operative refractive outcome, for example whether to provide improved near or far-field vision.

[0031] lOLs, such as IOL 100, are inserted into a patient’s eye during ophthalmic surgery, during which the patient’s natural (crystalline) lens is removed and then replaced with the IOL. Figure 2 shows a diagram of the human eye 200 in which an IOL may be inserted, though it should be appreciated that an IOL may be inserted in a non-human eye. The eye 200 includes a lens 210 attached to a ciliary body 230 via zonules 240. While the remaining structure of the eye 200 will not be discussed in detail as they are understood by the skilled person in this technical field, the eye 200 also includes a pupil 220, cornea 250, iris 260 and retina 270, amongst other features. During ophthalmic surgery, the natural lens 210 is replaced with an IOL, such as IOL 100. The IOL 100 may e.g., be placed within the capsular bag in which the natural lens 210 was previously located. As such, the haptics 120 of the IOL 100 may conform to the shape of the capsular bag, where the inner surface of the capsular bag may apply pressure to the haptics 120, helping to anchor the IOL 100 in place. The haptics 120 help to distribute this force evenly, which helps prevent any localized stress points, and act to resist any forces that may attempt to displace or shift the IOL 100.

[0032] While replacing the natural crystalline lens with an IOL may correct much of the burden of refractive surgery by improving visual acuity, current lens replacement processes generally fail to reproduce the same level of stereopsis (i.e. depth perception) as the natural crystalline lens, a key feature of binocular vision. Moreover, IOL lens tilt (when the entire IOL becomes rotated relative to its implantation position) or decentration (when the IOL is displaced relative to the central axis of the eye) occurs in about 5-10% of patients after scleral-sutured posterior chamber lens implantation and can occur even after uncomplicated implantation procedures.Large amounts of IOL tilt may cause enough astigmatism to significantly affect quality of vision and is therefore generally seen as undesirable.

[0033] One of the reasons for the lack of patient stereopsis after lens replacement surgery is due to tilt of the natural crystalline lens. In particular, the natural crystalline lens is tilted relative to the centre of the cornea and to the surface of the retina. This creates a diagonal plane of focus, which is helpful to create depth perception. On average, the crystalline has a forward tilt of approximately 5 degrees in the nasal direction, as discussed, for example, in Chen et al., (2021), Distributions of crystalline lens tilt and decentration and associated factors in age- related cataract, J Cataract Refract Surg, 47(10), 1296-1301 , the entire contents of which are hereby incorporated by reference. The tilt of the natural crystalline lens may be relative to a corneal topographic optical axis of the eye.

[0034] This tilt of the natural crystalline lens is illustrated in Figure 3. Figure 3 shows a left eye 300L and a right eye 300R looking towards the top of the page. The left eye 300L has a natural lens 310L, where the equatorial axis 315L of the lens 310L is shown, the equatorial axis 315L being defined by the edge of the lens 210L. The optical axis 330L of the lens 310L is perpendicular to the equatorial axis 315L. The left eye 300L also has a corneal topographic optical axis of the eye 325L. As can be seen in Figure 3, the optical axis 330L of the lens 310L is tilted with respect to the corneal topographic optical axis 325L of the eye 300L. Furthermore, the 310L has non-zero decentration (the distance between the corneal topographic optical axis 325L of the eye 300L and optical axis 330L of the lens 310L along the equatorial axis 315L of the lens 310L).

[0035] The optical axis 330L of the lens 310L is generally tilted in the nasal direction (i.e., towards the nose). The right eye 300R generally has a corresponding layout to the left eye 300L. In particular, the optical axis 300R (defined by the equatorial axis 315R) of the lens 31 OR of the right eye 300R is tilted with respect to the corneal topographic optical axis 325R of the right eye 300R. The optical axis 330R of the lens 31 OR is also generally tilted in the nasal direction (i.e. towards the nose). As such, while the optical axes 330L, 300R of the lens 310L, 31 OR of the left and right eyes, 300L, 300R generally both point towards one another, in the nasal direction. It should be noted for the purposes of explanation that the optical axis of the lens being tilted towards the nasal direction means that the section of the optical axis of the lens located between the eye and the target (i.e. object the eye is pointed toward), is rotated from the corneal topographic optical axis towards the nose. In other words, the arrows on the axes 325L, 325R, 330L, 330R show the directions in which the respective axes are defined as pointing, and the direction in which the optical axes of the lens point are rotated (i.e. tilted) away from the corneal topographic optical axes in the nasal direction.

[0036] In addition to being tilted in the nasal direction, the optical axis 330 of natural crystalline lenses 310 is generally tilted downwards, such that the overall tilt of the crystalline lens 310 is in the inferotemporal (i.e. inferior-temporal) direction. In other words, the optical axis 330 of the crystalline lens 310 is tilted towards an inferotemporal region of the eye 300. Figure 4 illustrates the various regions of the eyes 300L, 300R, looking out of the page, as shown by pupils 410L and 41 OR. Regions 401 and 402 are closer to the nose than regions 403 and 404. As such, regions 401 , 402 may be collectively referred to as the nasal region of the eye 300. Conversely, regions 403 and 404 are closer to the temple than regions 401 and 402. As such, regions 403, 404 may be collectively referred to as the temporal region of the eye 300. Region 401 may be specifically referred to as the superior-nasal region, as the region 401 is closer to the forehead than region 402. Conversely, region 402 may be specifically referred to as the inferior-nasal (inferonasal) region. By similar logic, the region 403 may be referred to as thesuperior-temporal region, and the region 404 may be referred to as the inferior-temporal region.

[0037] On average, the tilt of the optical axis of the natural crystalline lens relative to the corneal topographic optical axis is approximately 5.16 degrees, however the exact angle will be different for each patient, and may differ for each eye of the same patient. This tilt of the optical axis of the natural crystalline lens relative to the corneal topographic optical axis may lead to a lack of stereopsis after lens replacement, as current lOLs are designed to align with the corneal topographic optical axis. That is, while a certain degree of tilt in the position of the inserted IOL may be produced due to imperfect surgery, the optical axis of lOLs, if positioned perfectly, is aligned to the corneal topographic optical axis.

[0038] According to the present invention, a new IOL is provided which, when implanted, provides patients with stereopsis levels comparable to pre-surgery levels. An IOL is provided comprising: one or more haptic portions for securing the IOL to an eye of a subject, wherein the one or more haptic portions define a principal axis of the IOL; and an optical portion having an optical axis; wherein the optical axis of the optical portion is tilted with respect to the principal axis defined by the one or more haptic portions.

[0039] Figure 5 shows an example of an IOL 500 according to an example of the present disclosure. The IOL 500 includes an optical portion 510 and a haptic portion 520. In the example of Figure 5, the haptic portion 520 includes one or more appendages 525, for example, similar to the haptics 120 included in the IOL 100 of Figure 1 , however other haptic designs may be utilised (as discussed in relation to Figures 8A-8D). Furthermore, the haptic portion 520 comprises an annulus 530 wherein the one or more appendages 525 are attached to the annulus 530. The optical portion 510 is located within and may be secured to the annulus 530. The haptic portion 520 of the IOL 500 defines a principal axis of the IOL 500, and the optical portion 510 defines an optical axis of the IOL 500, where the optical axis is tilted with respect to the principal axis. Accordingly, patient stereopsis levels can be improved. In particular, lOLs such as those exemplified in Figure 5 are able to replicate the tilt of the optical axis of the patient’s natural crystalline lens with respect to the corneal topographic optical axis (as discussed in relation to Figure 3), leading to improved stereopsis. The IOL 500 may be inserted using well-known surgical techniques for inserting lOLs into the eye.

[0040] The optical axis of the IOL may be the axis along which the optical portion has rotational symmetry (e.g. circular rotational symmetry or two or more orders of rotational symmetry), or the axis normal to the equatorial plane of the optical portion. However, the principal axis of the IOL, which is defined by the one or more haptic portions, may be defined in a number of different ways. In some examples, as shown in Figure 5, the haptic portion may include an annulus 530, to which one or more appendages 525 are attached. The principal axis of the IOL 500 may, in some cases, be defined by the annulus 530. For example, the principal axis of the IOL 500 may be defined by the axis along which the annulus has rotational symmetry. This example is illustrated in Figure 6A. Figure 6A shows an IOL 600, having an optical portion 601 located within an annulus 603, and one or more appendages 602 attached to the annulus 603 (the one or more appendages 602 and the annulus 603 may be referred to collectively as one or more haptic portions). The annulus 603 may have rotational symmetry (e.g. circular rotational symmetry or two or more orders of rotational symmetry), as illustrated in the annulus 530 in Figure 5. As such, the principal axis 605 of the lens 600 may be defined as the axis about which the annulus 603 has rotational symmetry (e.g. circular rotational symmetry or two or more orders of rotational symmetry). Alternatively, the principal axis 605 of the lens 600 may be defined as the axis normal to the equatorial plane 604 of the annulus603. Furthermore, as shown in Figure 6A, the optical axis 606 of the optical portion 601 may be tilted with respect to the principal axis 605. The annulus 603 and appendages 602 may be integrally formed with one another, or may be affixed to one another. Furthermore, the optical portion 601 may be affixed to the annulus 603, or may be integrally formed with the annulus 603 (and the one or more haptic portions as a whole).

[0041] In some examples, the annulus may also be tilted with respect to the principal axis of the IOL, as shown in Figure 6B. Figure 6B shows an IOL 610, having an optical portion 611 located within an annulus 613, and one or more appendages 612 attached to the annulus 613 (the one or more appendages 612 and the annulus 613 may be referred to collectively as one or more haptic portions). The annulus 613 may have rotational symmetry (e.g. circular rotational symmetry or two or more orders of rotational symmetry), as illustrated in the annulus 530 in Figure 5. In some examples, the principal axis 615 of the IOL 610 may be defined as being normal to the equatorial plane 614 of the one or more appendages 612. The optical axis 616 of the optical portion 611 is tilted with respect to the principal axis 615, and the annulus 603 may be tilted with respect to the principal axis 615 and / or the equatorial plane 614. The annulus 613 and appendages 612 may be integrally formed with one another, or may be affixed to one another. Furthermore, the optical portion 611 may be affixed to the annulus 613, or may be integrally formed with the annulus 613 (and the one or more haptic portions as a whole).

[0042] In addition, as shown in Figure 6B, in some examples the IOL 610 may also include one or more surfaces 617 configured to hold the optical portion 610 within the annulus 613. That is, rather than the optical portion 611 being fixed directly to the annulus 613, the optical portion 611 may be located between two surfaces 617a, 617b (as shown in Figure 6B), or may be affixed to one surface 617. As such, the optical portion 611 may be manufactured separately from the haptic portions(s), and may be removable and replaceable from the haptic portions. The surfaces may, for example, be formed of the same material as the optical portion 611 and / or haptic portion(s). While only shown in Figure 6B, it should be appreciated that all of the examples disclosed herein may include the one or more surfaces 617. Figures 7A and 7B show perspective views of an IOL 700 including an annulus 730, in a similar manner to the lOLs 600 and 610 discussed in relation to Figures 6A and 6B. The optical portion 710 of the IOL 700 is tilted with respect to the annulus 730, where the annulus forms part of one or more haptic portions 720, additionally including a plurality of appendages 725 attached to the annulus 730.

[0043] In some examples, the haptic portion(s) of the IOL may not include an annulus. Instead, one or more appendages may be attached directly to the optical portion. An example as shown in Figure 6C, which illustrates an IOL 620 having an optical portion 621 and one or more haptic portions 622 in the form of one or more appendages attached to the optical portion 621 . As with the other examples of the present disclosure, the optical axis 626 of the IOL 620 may be the axis along which the optical portion 621 has rotational symmetry (e.g., circular rotational symmetry or two or more orders of rotational symmetry), or the axis normal to the equatorial plane of the optical portion 621. In the present example, the principal axis 625 of the IOL 620 may be defined by the one or more haptic portions 622. For example, the principal axis 625 may be defined as the axis normal to the equatorial plane 624 of the one or more haptic portions 622, or the axis normal to a plane or axis along which the one or more haptic portions 622 are configured to extend. As with the other examples of the present disclosure, the optical axis 626 is tilted with respect to the principal axis 625.

[0044] In some examples, the principal axis of the IOL may be defined by the ends of the one or more haptic portions. For example, while in Figures 6A-6C the one or more appendages are shown as extending parallel to one another, and / or parallel to the equatorial plane of the haptic portion(s), Figure 6D shows an IOL 630 having an optical portion 631 and one or more haptic portions 632 (e.g. in the form of one or more appendages) which extend at an angle to one another and / or at an angle to the equatorial plane 634 of the haptic portion(s) 632. In this way, the principal axis 635 of the IOL 630 may be defined by the equatorial plane 634 of the haptic portion(s) 632 and / or by the normal to the plane 634 defined by the distal ends of the haptic portions 632. As with the other examples of the present disclosure, the optical axis 636 is tilted with respect to the principal axis 635. A further example is shown in Figure 6E, which shows an IOL 640 including an optical portion 641 and one or more haptic portions 642 (e.g. in the form of one or more appendages) which extend at an angle to one another. The principal axis 645 may be defined as the normal to the plane 644 defined by the distal ends of the one or more haptic portions 642. As with the other examples of the present disclosure, the optical axis 646 is tilted with respect to the principal axis 645.

[0045] The examples discussed above are each compatible with various types of haptic. Figures 8A-D show a selection of example haptic arrangements which are compatible with the present invention, however the specific examples shown herein should not be considered limiting, as various other haptic designs are also compatible with the present invention. Figure 8A shows an IOL 800a where the haptics 820a are in the form of a plurality of appendages attached directly to the optical portion 810a. In this example, the haptics 820a are attached to the optical portion 810a at points of the optical portion 810a removed from an edge of the optical portion 810a. Figure 8B shows an IOL 800b where the haptics 820b are in the form of a plurality of appendages attached directly to the optical portion 810b. In this example, the haptics 820b are attached to the optical portion 810b at points at an edge of the optical portion 810b. Figure 8C shows an IOL 800c where the haptics 820c are in the form of a plurality of appendages attached directly to the optical portion 810c at haptic junctions. The haptic junctions are regions of the haptics 820c proximal to the optical portion 810c which extend circumferentially around a sub-section of the optical portion 810c. Figure 8D shows an IOL 800d where the haptics 820d are in the form of one or more plates 820 attached to the optical portion 81 Od. While not shown in Figures 8A-8D, the haptic designs shown in Figures 8A-8D may each be utilised in combination with an annulus, as discussed above in relation to Figures 5, 6A, and 6B, or may be utilised without such an annulus. In addition, the examples discussed above are each compatible with various types of optical portion. For example, the optical portion may comprise a monofocal lens, a multifocal lens, a toric lens, a multifocal toric lens, or an enhanced monovision (EMV) lens, or any other form of lens.

[0046] According to the above-described examples, an IOL with an optical axis which is tilted with respect to a principal axis of the IOL is provided. Accordingly, the tilt of the natural crystalline lens of a patient may be replicated, leading to improved stereopsis. While the above examples of lOLs according to the present disclosure are described primarily in the context of the replacement of the eye’s natural crystalline lens, it should be appreciated that lOLs which are inserted into the eye in addition to the eye’s natural crystalline lens are also contemplated. Examples of such lOLs include a posterior chamber phakic intraocular lens (plOL), such as an implantable collamer lens (IOL). That is, a plOL, such as an IOL, may be provided with an optical axis which is tilted with respect to a principal axis of the plOL.

[0047] The direction and magnitude of the tilt of the natural crystalline lens may vary for each patient, and for each eye, and as such replicating the tilt of the natural crystalline lens may require bespoke tilt angles in the IOL. Moreover, as discussed above, postoperative lOLs mayexperience some tilt (i.e. rotation) relative to the intended implantation orientation. That is, the entire IOL (i.e. the principal axis of the IOL) may become tilted relative to the implantation position / orientation. may be chosen so as to account for the rotation of the IOL post-surgery. Studies have demonstrated that the magnitude and direction of rotation of postoperative lOLs are strongly correlated with the tilt of the preoperative natural crystalline lens (see e.g. Hirnschall, N., et al., (2017), Prediction of postoperative intraocular lens tilt using swept-source optical coherence tomography, J Cataract Refract Surg, 43(6), 732-736, the entire contents of which are hereby incorporated by reference). Therefore, the tilt and decentration of the crystalline lens can be used to predict postoperative IOL position.

[0048] An example of this correlation is shown in the graph of Figure 9. Figure 9 shows a graph showing for a number patients the preoperative tilt of their natural crystalline lens (on the x-axis) against the postoperative tilt of an IOL (on the y-axis). The solid trend line 910 shows the measured trend. In contrast, the dashed line 920 shows the ideal trend, where the postoperative tilt of the IOL is equal to the preoperative tilt of their natural crystalline lens. Therefore, in order to replicate the preoperative tilt of the natural crystalline lens, the optical portion of the lOLs according to the present disclosure are tilted with respect to the principal axis of the IOL.

[0049] The amount of tilt of the optical portion of the IOL with respect to the principal axis of the IOL may be set based on the measured preoperative tilt of the patient’s natural crystalline lens, for example according to the method 1000 shown in Figure 10. The method of Figure 10 may for example, be a computer-implemented invention which may be performed on a suitable computing apparatus. For example, a computing apparatus may include one or more processors coupled to one or more memories, and may also include a network interface, and one or more input / output (I / O) devices. According to the method of Figure 10, the preoperative tilt of the patient’s natural crystalline lens may be identified in step 1010. Identifying the preoperative tilt includes identifying a magnitude of the preoperative tile and may also include identifying an axis (i.e. direction) of the preoperative tilt. For a given measured preoperative lens tilt, a corresponding predicted IOL tilt is determined at step 1020, for example based on a predetermined trend (such as that shown by the solid line 910 in Figure 9). The predicted IOL tilt is then compared against the ideal IOL tilt (e.g. shown by the dashed trend line 920 in Figure 9) for the given measured preoperative lens tilt at step 1030 in order to calculate a difference between the predicted IOL tilt and the ideal IOL tilt. The difference between the predicted IOL tilt and the ideal IOL tilt is then determined as the tilt of the optical axis of an IOL in step 1040, according to the present disclosure. Therefore, the combination of the predicted IOL tilt and the tilt of the optical axis with respect to the principal axis of the IOL achieve and overall IOL optical axis tilt close to the tilt of the natural crystalline lens of the patient. In other words, the direction and magnitude of the tilt of the optical axis with respect to the principal axis of the IOL may be chosen so as to replicate as closely as possible the tilt of the optical axis of the patient’s natural crystalline lens with respect to the corneal topographic optical axis, which may also take into account a predicted tilt of the IOL as a whole.

[0050] Identifying (1010) the tilt of the patient’s natural crystalline lens may include receiving a user input indicating the patient’s natural crystalline lens, or receiving a communication (for example over a network via a network interface) including an indication of the patient’s natural crystalline lens. Identifying (1020) the predicted postoperative IOL tilt may include calculating the predicted postoperative IOL tilt based on a predicted trend line. An equation for the predicted trend line may be stored in memory or may be received, for example through user input or over a network. Furthermore, identifying the predicted postoperative IOL tilt may include transmitting over a network an indication of tilt of the patient’s natural crystalline lens,and receiving, over the network, an indication of the predicted postoperative IOL tilt. Calculating (1030) the difference between the predicted postoperative IOL tilt and the target postoperative IOL tilt may include comparing the predicted IOL tilt with a target IOL tilt. The target IOL tilt may be the measured preoperative IOL tilt, however in some cases the target IOL tilt may be different to the measured preoperative IOL tilt. Determining (1040) the tilt of the optical axis of the IOL with respect to the principal axis of the IOL may include outputting via one or more I / O devices an indication of the determined tilt, or transmitting an indication of the determined tilt over a network. It should furthermore be appreciated that the method according to Figure 10 may be performed by a single computing device, or may be performed in a distributed manner by multiple computing devices in communication with one another across a network or multiple networks.

[0051] The method described in relation to Figure 10 may also be embodied or encoded in a computer-readable medium, such as a computer-readable storage medium, containing instructions. Instructions embedded or encoded in a computer-readable medium may cause a programmable processor, or other processor, to perform the method, e.g., when the instructions are executed. Computer-readable media may include non-transitory computer- readable storage media and transient communication media. Computer readable storage media, which is tangible and non-transitory, may include random access memory (RAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electronically erasable programmable read only memory (EEPROM), flash memory, a hard disk, a CD-ROM, a floppy disk, a cassette, magnetic media, optical media, or other computer-readable storage media. The term “computer-readable storage media” refers to physical storage media, and not signals, carrier waves, or other transient media. As noted above, computer readable media may include transient communication media. Such communication media may occur within a single computer system or between multiple computer systems, and may take the form of transient signal-conveying media such as carrier waves and transmission signals.

[0052] Figure 11 illustrates a flowchart of an example process 1100 for determining the properties of a monofocal tilted IOL (TIOL) to be implanted. Step 1110 includes measuring the visual acuity of the individual with and / or without correction (if the individual has spectacle correction or contact lens correction). This assessment is helpful to determine to how much the cataractous lens has affected the visual acuity of such individual pre-operatively. Step 1120 involves taking a keratometry reading. Keratometry is an objective assessment used to measure the corneal refractive power of the eye, which can be expressed as a radius of curvature or optical power of the cornea. This objective measurement is to determine the K1 and K2 optical power of the cornea. The readings are used for the accurate optical power calculation for the Monofocal TIOLs according to the present disclosure.

[0053] Step 1130 includes performing Posterior Segment Optical Coherence Tomography (PS-OCT) for the patient’s retina. PS-OCT is a non-invasive method used to image the retinal layer of the eye. The procedure is performed to identify if the patient has any retinal pathology that can guard the final visual acuity. In the case any patient has any retinal pathology his final visual acuity will be lower than expected with the best corrected intraocular lens implant. Step 1140 includes performing Anterior Segment Optical Coherence Tomography (AS-OCT) for the patient’s natural crystalline lens. AS-OCT is a non-invasive high resolution cross-sectional imaging modality for the anterior segment of the eye where the crystalline lens is located. It has been identified that the crystalline lens is the most determining factor of intraocular lens tilt post operatively. Imaging the crystalline lens will give the original tilt of such individual that the Monofocal TIOLs are required to replicated in its design. The AS-OCT for an examplepatient may identify a crystalline lens tilt of 5.2° along the 182° axis. The tilt of the optical axis may therefore be determined to be 1.5°, for example using the method discussed above in relation to Figure 10. The axis of the tilt of the optical axis of the IOL may also be set to 180°.

[0054] Step 1150 includes performing an axial length and biometry measurement. That is, after the dilation of such individual the axial length of the eye ought to be operated is measured. Axial length is the length from the front surface of the cornea to the back surface of the retina. Once the axial length is determined, it may be used to calculate the required refractive power of the monofocal TIOLs within the biometry that the TIOL will be implanted in the operated eye. At step 1160, the monofocal TIOL dioptric power is determined. TIOLs according to the present disclosure are designed to incorporate tilt with in the lens to replicate the original crystalline lens. The dioptric power may be calculated e.g. using the following equations:C = S' (tan a)2where S’= perceived spherical power of a lens after a tilt, a = the required tilt, n = refractive index of a lens material (acrylic lens 1.49), C’= perceived cylindrical power of a lens after a tilt. As such, the properties of a TIOL according to the present disclosure may be determined. It should be appreciated that various steps of Figure 11 may be removed, replaced, and / or adapted in a variety of ways.Accordingly, from one perspective, there has been described an intraocular lens (IOL) is provided comprising one or more haptic portions and an optical portion. The IOL has a principal axis defined by the one or more haptic portions and an optical axis defined by the optical portion. The optical axis of the IOL is tilted with respect to the principal axis of the IOL. Therefore, the tilt of a patient’s natural crystalline lens may be better replicated post-cataract surgery.

Claims

CLAIMS1. An intraocular lens (IOL) comprising: one or more haptic portions for securing the IOL to an eye of a subject, wherein the one or more haptic portions define a principal axis of the IOL; and an optical portion having an optical axis; wherein the optical axis of the optical portion is tilted with respect to the principal axis defined by the one or more haptic portions.

2. The IOL according to claim 1 , wherein the tilt of the optical axis with respect to the principal axis has a magnitude of at least 0.5 degrees.

3. The IOL according to claim 2, wherein the tilt of the optical axis with respect to the principal axis is between 0.5 degrees and 9.0 degrees.

4. The IOL according to any preceding claim, wherein the one or more haptic portions comprise an annulus, wherein the optical portion is located within the annulus.

5. The IOL according to claim 4, wherein the annulus is tilted with respect to the principal axis of the IOL.

6. The IOL according to claim 4, wherein the principal axis is defined by the annulus.

7. The IOL according to any of claims 4-6, wherein the optical portion is configured to be removable from the annulus.

8. The IOL according to claim 7, wherein the annulus comprises a first surface configured to support the optical portion, wherein the first surface is configured to be located on a first side of the optical portion.

9. The IOL according to claim 8, wherein the annulus further comprises a second surface configured to support the optical portion, wherein the second surface is configured to be located on a second side of the optical portion opposite the first portion.

10. The IOL according to any of claims 4-9, wherein the optical portion is integrally formed with the one or more haptic portions.11 . The IOL according to any preceding claim, wherein the optical axis is tilted towards an inferior-nasal, nasal and superior-nasal region of the IOL.

12. The IOL according to claim 11 , wherein the IOL comprises: the inferior-nasal region configured to correspond to an inferior-nasal region of the eye of the subject; a nasal region configured to correspond to a nasal region of the eye of the subject; and a superior-nasal region configured to correspond to a superior nasal region of the eye of the subject.

13. The IOL according to claim 12, wherein the optical axis is tilted towards the inferiornasal region of the IOL such that the inferior-nasal region of the IOL is configured, when secured to the eye of the subject, to be located further from a pupil of the eye of the subject than the superior-temporal region of the eye of the subject when placed behind the iris.

14. The IOL according to claim 12, wherein the optical axis is tilted towards the inferiornasal region of the IOL such that the inferior-nasal region of the IOL is configured, when secured to the eye of the subject, to be located closer to a pupil of the eye of the subject than the superior-temporal region of the eye of the subject when placed in front of the iris.

15. The IOL according to any preceding claim, wherein the optical axis is defined by an axis of the one or more haptic portions.

16. The IOL according to any preceding claim, wherein the optical axis is defined by one or more distal ends of the one or more haptic portions.

Images