GB2518378A

GB2518378A - Intraocular Lenses

Info

Publication number: GB2518378A
Application number: GB1316612.9A
Authority: GB
Inventors: Timothy Paine
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-09-18
Filing date: 2013-09-18
Publication date: 2015-03-25
Also published as: WO2015040411A2; GB201316612D0; WO2015040411A3

Abstract

An intraocular lens to be implanted in a human eye has a lens body 112 and a plurality of elongate lens body supports 114. The lens body has an anterior side 116 that in use faces outwardly of the eye and a posterior side 118 that faces inwardly of the eye. The lens body supports project from the lens body and are configured to permit fixing of the lens body onto the exterior of the capsular bag of the human eye, such that contraction or relaxation of the ciliary muscle acts on the lens body supports to apply a focussing force which deforms the lens body. The lens body supports may have hooks 126 to secure the lens around the periphery of the capsular bag. The lens body supports may be adjustable in length using a series of protrusions (244, see figure 6) and indentations 246.

Description

INTRAOCULAR LENSES

Field of the Invention

The invention relates intraocular lenses.

S

Background to the Invention

The lens of the human eye is originally flexible and focuses for vision at different distances by deforming so as to change its thickness in the axial direction of the eye. For near vision the lens is relatively fat, or thick, and for distance vision it is stretched so that it becomes relatively thin. The lens cannot have a blood supply and consequently with age will tend to become stiffer and misty. As the lens becomes stiffer, the range of clear vision is reduced. This is why older people often require reading spectacles, bifocals or varifocals.

The mistiness is cataract.

For the treatment of cataracts it is known to perform a surgical procedure in which the cataracted lens is removed from the eyeball through a small incision made in the wall of the cornea and repaccd by an artificial intraocu'ar lens. One known surgical procedure involves the extracapsular removal of the cataracted natural lens, leaving portions of the lens sack, or capsular bag, intact to hold the implanted intraocular lens. The intraocular lens is folded and inserted into the capsular bag where it unfolds. The intraocular lens has two side struts called haptics that press against the inner side of the capsular bag to hold the lens in place within the capsular bag.

Summary of the Invention

The invention provides an intraocular lens as specified in claim 1.

The invention also includes an intraocular lens as specified in claim 21.

The invention also includes an intraocular lens as specified in claim 27.

Brief Description of the Drawings

In order that the invention may be well understood, some non-limiting examples will now be described with reference to the drawings in which: Figure 1 is a schematic side section view of a human eye; Figure 2 is a schematic front elevation of an intraocular lens; Figure 3 is a schematic side elevation of the intraocular lens of Figure 2 shown in a relaxed condition; Figure 4 is a view corresponding to Figure 3 showing the intraocular lens in a deformed condition; Figure 5 is a schematic illustration showing the intraocular lens of Figures 2 to 3 implanted in a human eye; Figure 6 is an cnlarged side elevation of a part of another intraocular lens; and Figure 7 is a schematic illustration of a focussing operation of another intraocular lens.

Detailed Description

Referring to Figure 1, a human eye 10 comprises a cornea 11 and a lens sack, or capsular bag, 12 disposed in a posterior chamber 14 that is disposed rearwardly, or inwardly, of the iris 16. The capsular bag 12 contains a crystalline lens 18 and is connected with ciliary muscle 20 by zonules 22. The ciliary muscle 20 can move between a contracted condition shown in Figure 1 in which the lens 18 is relatively fat for near vision and a relaxed condition in which the lens is pulled to make it relatively thin for distance vision.

Specifically, in the contracted position shown in Figure 1, the lens 18 is relatively fat, or thick, in the axial direction through the centre of the eye that is indicated by line 24 and when the lens is pulled by the ciliary muscle, that thickness is reduced.

Referring to Figures 2 to 4, an intraocular lens 110 to be implanted in a human eye comprises a lens body 112 and a plurality of elongate lens body supports 114. The lens body 112 has an anterior side 116 and a generally oppositely disposed posterior side 118.

When implanted in a human eye, the anterior side 116 faces outwardly of the eye towards the cornea 11 and the posterior side 118 faces generally inwardly towards the back of the eye and the optic nerve 26. The lens body supports 114 project from the lens body 112 and are configured to permit the fixing of the lens body to the exterior of the capsular bag 12 of the eye.

The front elevation of the lens body 112 has a generally circular profile. The lens body 112 is flexible and in its relaxed condition (shown in Figure 3) is relatively thick in the axial direction of the lens body that is indicated by the lens body axis 120. The shape of the lens body 112 in the relaxed condition, including its thickness, is selected to provide a desired lens strength for near vision. The flexibility of the lens body 112 is such that it can be stretched to make it relatively thin in the axial direction, for example as illustrated by Figure 4. The configuration of the lens body 112 is selected such that when suitably stretched, it will provide a desired lens strength for distance vision. For example, the lens body 112 may be configured to havc a strength of 30.00 dioptrcs whcn rclaxcd and 22.00 dioptres when stretched for distance vision. For a myopic patient having, for example, a spectacles prescription of -3.50 dioptres, the lens body 112 may have a strength of 26.50 dioptres in its relaxed, near vision, condition and 18.50 dioptres when stretched for distance vision. Thus, the lens body 112 may be configured such that it can deform sufficiently to provide at least an 8.00 dioptre range of lens strength.

In some examples, the lens body 112 may be about 9.00 mm in diameter and have a thickness of approximately 6.00 mm at the lens body axis 120 when in the relaxed, near vision, condition (dmaxi in Figure 3). In some cxamplcs, when stretched for distance vision the thickness may have reduced to approximately 4.00 mm (drn, in Figure 4). Thus, for some examples at least, a lens body 112 may be configured to deform by approximately 2.00 mm bctwccn its near vision and distance conditions.

The lens body supports 114 are relatively rigid and project from the periphery 122 of the lens body 112. In the illustrated example the lens body supports 114 project in a generally radially outwards direction with respect to the lens body axis 120. The lens body supports 114 may, for example, be struts embedded in the lens body 112. The lens body supports 114 are spaced apart at regular intervals about the periphery of the lens body 112. The number of lens body supports 114 and the spacing between them can be selected so as to provide sufficiently secure and stable attachment to the capsular bag 12 of a human eye, without unduly adding to the amount of work needed to attach the lens 110 to the capsular bag and a sufficiently uniform deformation of the lens body for focussing to provide clear S vision across the prescribed range of distances. In some examples, there may be six lens body supports, although for other examples more may be necessary.

The lens body supports 114 each have a first end that is secured to, or embedded in, the lens body 112 and a free end 126. The free ends 126 of the lens body supports 114 are configured to permit them to attach the lens body 112 to the exterior of the capsular bag 12 or to the zonules 22. In the illustrated example, the free ends 126 are hooked to permit the intraocular lens 110 to be hooked onto the exterior of the capsular bag 12 around its perimeter. The hooked free ends 126 point away from the anterior side 116 of the lens body 112 such that whcn fixed to the capsular bag the lens body 112 is disposcd forwardly of the capsular bag.

The lens body 112 may, for example, be made of silicone or silicone hydrogel. The lens body 112 may incorporate yellow dye, blue light or other known filtering means, to filter out unwanted parts of the visible or invisible spectrum. The lens body supports 114 may be made of a relatively more rigid surgically approved plastics material and may co-moulded with the lens body.

Comparing Figure 5 with Figure 1, the human eye 10 has undergone a surgical procedure known as phacoemulsification. This may first involve making a small incision in the cornea 11 through which a tool is inserted to remove a portion of the anterior side of the capsular bag 12. Thcn a tool is inserted into the capsular bag 12 to break up and emulsify the lens 18 by means of ultrasonics, following which the lens is removed by a suction tool.

Once the lens is cleaned from the capsular bag 12, an intraocular lens 110 can be implanted in the eye 10 by attaching it to capsular bag in such a way that it is disposed externally of the capsular bag.

An intraocular lens 110 having a lens body 112 with the desired lens strength is inserted into the eye through the incision in the cornea 11, which may need to be widened for the purpose. The lens body 112 is positioned in the anterior chamber 14 in front of the capsular bag 12. The hooked free ends 126 of thc lcns body supports 114 arc thcn systematically hooked over the periphery 130 of the capsular bag through the zonules 22.

This process gradually deforms the lens body 112 so that when it is fitted onto the capsular bag 12 it is in the stretched condition shown in Figure 4 and configured for distance vision.

When the ciliary muscle 20 contracts, the lens body 112 returns towards its relaxed condition, thickening the lens body to focus for nearer vision and when they relax it is stretched again for distance vision. In this way, the lens body 112 is able to function in similar fashion to the natural lens 18 that has been removed from the eye. As shown in Figure 5, when fitted in place, the intraocular lens 110 is disposed forwardly of the capsular bag 12 and is attachcd to the exterior of the capsular bag.

Figure 6 illustrates another example of an intraocular lens 210 to be implanted in a human eye. Features of the intraocular lens 210 the same as, or similar to, those of the intraocular lcns 110 are given thc same rcfcrencc numerals, incrcmentcd by 100, and may not bc described in detail again.

The intraocular lens 210 comprises a lens body 212 that is flexible and can be deformed between a relaxed condition in which it has a desired strength for near vision and an extended condition in which it has a desired strength for distance vision. The intraocular lens 210 has a plurality of length adjustablc lens body supports 214. The lens body supports 214 have hooked free ends 226 that allow the intraocular lens 220 to be secured to the capsular bag 12 or zonules 22 ofa human eye in similar fashion to the intraocular lens 110.

The lens body 212 is provided with respective tubes 240 to receive the first ends of the lens body supports 214 (ie the opposite end to the hooked free end 226). The tubes 240 each define a passage 242 to receive the respective lens body supports 214. The passage 240 may be a blind bore or a through-hole. The passages 240 are provided with a plurality of formations 244. The formations 244 are arranged as series along at least a portion of the length of the tube 240. In the illustrated example, the formations 244 are a series of annular ribs disposed in spaced apart relation along the length of the passage 242. In the illustrated example, the formations 244 are generally semi-circular in cross-section, although any other suitable profile may be used. The lens body supports 214 are provided S with a series of formations 246 to interengage the formations 244 of the tubes 240. In the illustrated example, the formations 246 are annular depressions, or grooves, configured to mate with the formations 244 of the tubes 240.

The interengagement of the formations 244, 246 defines a series of length adjustment positions to make the lens body supports 214 length adjustable. This arrangement permits the surgeon to adjust the tension of the lens body 212 and thereby adjust the lens strength.

In the illustrated example, the formations 244 are projections that engagc in depressions provided in thc lens body supports 214. It will be apprcciatcd that this is not essential and that the lens body supports 214 may be provided with projections to engage in depressions provided in the tube. Furthermore, it is not essential that the projections or depressions are annular as shown in the illustrated example. The projections may extend around a relatively small part of the circumference of the lens body supports/tube to engage in depressions that similarly extend around a relatively small part of the circumference of the lens body supports/tube. In general it is desirable that in the case of non-annular depressions, the depressions extend around a greater portion of the circumference than the projections they mate with in order to avoid aligument issues. In another example, the formations on the tubes and lens body supports may be resilent tines that have a radial extent configured such that they overlap when the lens body supports are inserted into their respective tubes. The interengaging tines would act in similar fashion to a ratchet mechanism in defining a series of length adjustment positions.

The lens bodies 112, 212 of the intraocular lens 110, 210 have a relaxed condition in which they are relatively fat, or thick, to provide a lens strength suited for near vision. The lens bodies 112, 212 are stretched to make thom thinner for distance vision by the ciliary muscle 20, which pulls on the lens body via the lens body supports. When the ciliary muscle 20 contracts, the lens bodies 112, 212 will tend towards their relaxed condition by virtue of the resilience of the lens body material, so that the thickening of the lens for near vision is not soley dependent on the force applied by the cilary muscle. It will be understood that the lens bodies 112, 212 will tend to be able to accommodate a greater degree of deformation, and so variation in lens strength, than a lens body that has a relaxed condition in which it is configured for distance vision and has to be squashed by compressive forces applied by the ciliary muscle.

Referring to Figure 7, an intraocular lens 310 is shown fitted to the exterior of a capsular bag 12 of a human eye. The intraocular lens 310 has a lens body 312 and a plurality of lens body supports 314 with hooked free ends 326 that allow the intraocular lens 310 to be secured to the exterior of the capsular bag 12 or zonules 22 of a human eye in similar fashion to the intraocular lenses 110, 210. The lens body 312 may be approximately 6.00 mm in diamctcr and approximately 3.5 mm thick.

The intraocular lens 310 differs from the intraocular lens 110, 210 in that the lens body 312 is substantially rigid. The configuration of the lens body 312 is designed to provide a desired strength for near vision. The lens body supports 314 are connected with the lens body 312 such as to permit relative pivoting movement between the lens body and lens body supports, for example by a spring hinge connection. The action of the cilary muscles 20 of the human eye that is transmitted to the capsular bag 12 via the zonules 22 causes the pivoting movement of the lens body supports 314 relative to the lens body 312 and that pivoting movement causes the lens body to move back and forth in the eye to focus for different distances. In Figure 7, the back and forth movement is indicated by arrow 315 and is generally along the lens axis 320. The intraocular lens 310 may be configured such that the movement of the lens body 312 provides a variation in lens strength of around 8.00 dioptres.

In general, an intraocular lens 110, 210 or 310 may be configured based on an initial consideration of a lens strength required to give a desired correction for a patient's distance vision and then providing for a range of focussing power of 6.00 to 10.00 dioptres obtained by stretching the lens body 112, 212 or 312 from its relaxed condition to the condition in which it gives the desired correction for distance vision. It is currently anticipated that for most patients a range of focussing power of 8.00 dioptres will be sufficient.

Claims

CLAIMSAn intraocular lens to be implanted in a human eye, said intraocular lens comprising a lens body and a plurality of elongate lens body supports, said lens body having an anterior side that in use faces outwardly of the eye and a posterior side that faces inwardly of the eye and said lens body supports projecting from said lens body and being configured to permit fixing of the intraocular lens in the eye externally of the capsular bag such that movements of the ciliary muscle of the cyc act on thc lens body supports to apply a focussing force to said lens body.
2. An intraocular lens as claimed in claim 1, wherein said lens body supports are configured to permit fixing of the lens body such that said posterior side faces an anterior sidc of thc capsular bag.
3. An intraocular lens as claimed in claim 1 or 2, wherein said lens body supports extend generally radially outwardly of said lens body.
4. An intraocular lens as claimed in any onc of thc prcccding claims, wherein thcrc are at least three said lens body supports disposed in evenly spaced apart relation on a pitch circle diameter centred on an axial centre of said lens body.
5. An intraocular lens as claimed in any one of the preceding claims, wherein the lens body supports arc configurcd to pcrmit fixing of thc lens body onto thc cxtcrior of thc capsular bag or the zonules of the eye.
6. An intraocular lens as claimcd in claim 5, wherein cach said lens body support has a frcc end configured to engage the exterior of the capsular bag or the zonulcs of the eye to permit said fixing of the intraocular lens.
7. An intraocular lens as claimed in claim 6, wherein said free ends arc hooked.
8. An intraocular lens as claimed in claim 7, wherein said hooked free ends point away from said anterior side of the lens body.
9. An intraocular lens as claimed in any one of the preceding claims, wherein said lens body supports each have a length and are configured to be length adjustable.
10. An intraocular lens as claimed in claim 9, wherein said lens body supports are configured to be length adjustable by sliding movement relative to said lens body.
11. An intraocular lens as claimed in claim 10, wherein said lens body supports are received in respective passages fixed with respect to said lens body and said lens body supports are slidable in said passages.
12. An intraocular lens as claimed in claim 11, wherein said lens body supports are provided with first formations coilfigured to interengage second formations provided in said passages to define a series of length adjustment positions.
13. An intraocular lens as claimed in claim 12, wherein said first formations comprise projections.
14. An intraocular lens as claimed in any one of the preceding claims, wherein said lens body is a flexible body having a rest condition in which it is shaped to provide a lens strength for near vision.
15. An intraocular lens as claimed in claim 14, wherein said lens body is configured to have a strength at least substantially 26.00 and 30.00 dioptres when in said relaxed condition.
16. An intraocular lens as claimed in claim 14 or 15, wherein in said rest condition a first maximum distance dmaxi between said anterior and posterior sides of said lens body is greater than a second distance diimx2 between said anterior and posterior sides when, in usc, said lens body is deformed by action of ciliary muscle of the eye.
17. An intraocular lens as claimed in claim 16, wherein said lens body is configured to have a strength at least substantially between 18.00 and 22.00 dioptres when said distance between said anterior and posterior surfaces is said second distance dmax2.
18. An intraocular lens as claimed in claim 17, wherein said lens body is configured such that the difference between and d12 provides a variation in lens strength of substantially 6.00 to 10.00 dioptres.
19. An intraocular lens as claimed in any one of claims 1 to 8, wherein said lens body supports connect with said lens body so as to permit relative pivoting movement between said lens body supports and said lens body so that said lens body can move away from and towards said capsular bag in rcsponsc to contraction and rclaxation of thc muscles of said human eye.
20. An intraocular lens as claimed in claim 19, wherein said lens body supports are connected with said lens body via respective spring hinges.
21. An intraocular lens to be implanted into the human eye, said intraocular lens comprising a lens body and a plurality of length adjustable elongate lens body supports projecting from the lens body and configured to attach the intraocular lens to the eye.
22. An intraocular lcns as claimcd in claim 21, wherein said lens body supports are configured to be length adjustable by sliding movement relative to said lens body.
23. An intraocular lens as claimed in claim 22, wherein said lens body supports are received in respective passages fixed with respect to said lens body and said lens body supports are slidable in said passages.
24. An intraocular lens as claimed in claim 23, wherein said lens body supports arc provided with first formations configured to intcrcngage second formations provided in said passages to define a series of length adjustment positions.
25. An intraocular lens as claimed in claim 24, wherein said first formations comprise projections.
26. An intraocular lens as claimed in any one of claims 21 to 25, wherein said lens body is a flexible body having a rest condition in which it is shaped to provide a lens strength for near vision.
27. An intraocular lens to be implanted into the human eye, said intraocular lens comprising a lens body and a plurality of elongate lens body supports projecting from the lens body and configured to attach the intraocular lens to the eye, said lens body being a flexible body having a rest condition in which it is shaped to provide a lens strength for ncar vision and dcformable to an cxtcndcd condition in which it is shaped to provide a lens strength for distance vision.
28. An intraocular lens as claimed in claim 27, wherein said lens body is configured to be deformaNe to provide a variation of lens strength of at least 8.00 dioptres.
29. An intraocular lens substantially as hereinbefore described with reference to Figures 2 to 5, 6 or 7.