HK1186372B - Intraocular lens implant - Google Patents

Description

Intraocular lens implant

Technical Field

The present invention relates to intraocular lens implants, methods of manufacturing intraocular lens implants, and kits for manufacturing intraocular lens implants.

Background

Replacement of the natural lens of the human eye with an intraocular lens implant may be indicated when the natural lens hardens due to aging and accommodation becomes no longer feasible. For a long time, lens implants that allow accommodation have included replacing the natural lens material of the human eye with synthetic lens material. In addition to adapting the lenses to individual needs (e.g., to a particular refractive index), the materials from which they are made can be difficult to select for contradictory requirements, namely, on the one hand, the lens implant is required to be adjustable, and on the other hand, it is required to be durable and long-lived.

Recently, it has been proposed to replace a single lens implant by a lens implant with two viewing elements (i.e. two lenses coupled to each other by means of a spring element). Such lens implants can be referred to, for example, in US2005/0228401A 1. The lens implant includes an anterior portion including a front member and an anterior offset member. The crystal also includes a rear portion that includes a rear viewing element and a rear offset element. The anterior and posterior portions meet at first and second apices of the intraocular lens. The anterior and posterior portions and/or the apex changes in response to the force separating the visuals. Lens implants are designed to be implanted within the lens capsule of the eye.

In the absence of any external forces, the lens implant has a shape in which the viewing elements are at their maximum separation along the optical axis. The visuals can move toward one another in response to relaxation of the ciliary muscles to achieve a shape corresponding to a lens implant state suitable for distance vision (which state is also referred to herein as a non-accommodating state). Relaxation of the ciliary muscle may cause the zonular fibers to become tensioned and draw the lens capsule axially outward, which causes a force against the spring member of the lens implant within the lens capsule and compresses the viewing element. The result is a lens capsule comprising a lens implant having a more planar shape. At the other extreme, the ciliary muscle contracts to allow zonular fibers to relax. The lens implant, in particular its spring element, extends from its tensioned state to its relaxed state, so that the viewing elements are separated from one another. The lens implant then has a spherical shape corresponding to the state for near vision, also called the accommodation state.

In another embodiment illustrated in figures 38A and 38B of the subject document, a lens implant is provided with two offsets adjacent to two viewing elements, the offsets being sized such that their apices abut the zonular fibers and ciliary muscle in the non-accommodated state. Here, the lens implant is configured such that it will remain in the non-adjusted state in the absence of an external force. Thus, when the ciliary muscle contracts, it pulls the apex closer, which causes the offset to fail and the optic to separate and reach an accommodation state. When the ciliary muscle relaxes, the force applied to the apex is reduced and the visuals re-approach each other and transition the lens implant to the non-accommodating state.

Both variants are not considered ideal in view of the adaptation of the lens implant to its natural environment. In a first variant, the relaxed state of the lens implant provides spaced apart viewing elements, which in turn results in a shape that indicates an accommodation state of the lens implant for near vision. This does not reflect the shape of the natural lens material without the lens capsule when not exposed to any external forces: in contrast, natural lens material has a flat shape representing a non-accommodated state suitable for distance vision.

According to a second version, the relaxed state of the lens implant looks the opposite of the first variant, and the shape of the lens implant now represents the non-accommodating state of the lens adapted for distance vision. However, the activation of such lens implants and the shape of such lens implants are not considered to be an optimal adaptation of such lens implants to their environment. One reason for this is that the ciliary muscles of the human eye typically do not directly drive and engage these crystals.

Disclosure of Invention

Accordingly, one problem to be solved by the present invention is to provide intraocular lens implants adapted to the physiology of the eye and suitable for long term deployment within the lens capsule.

According to a first aspect of the present invention, there is provided an intraocular lens implant comprising: a first visual and a second visual; a spring member for varying the distance between the first and second viewing elements along the optical axis of the lens implant and thereby varying the focal length of the lens implant. The lens implant is designed to have a shape suitable for distance vision when the spring element is in its relaxed state. The spring constant of the spring element is of such a magnitude that a force generated by the lens capsule of the eye for holding the lens implant transforms the spring element from its relaxed state into a stretched state.

According to another aspect of the present invention, there is provided an intraocular lens implant comprising: a first visual and a second visual; a spring member for varying the distance between the first and second viewing elements along the optical axis of the lens implant and thereby varying the focal length of the lens implant. The lens implant is designed to have a shape suitable for distance vision when the spring element is in its relaxed state. The spring constant of the spring element has a value of less than 550 mN/mm. More specifically, the lens implant is designed to have a shape adapted for near vision when the spring element is in a stretched state, whereby the distance between the first and second viewing elements in the stretched state of the spring element exceeds the distance between the first and second viewing elements in a relaxed state of the spring element. Thus, the lens implant is designed to require an external tension to stretch the spring element from its relaxed state to its stretched state.

Such lens implants are designed to reflect the properties of the natural lens and its excitation mechanism and to follow as closely as possible the physiological properties of the eye. First, although this lens implant is designed with several components, i.e. comprising two or more viewing elements and a spring element between the viewing elements, it is still designed with a flattened shape without any external force, which shape represents the shape of the natural lens enabling distance vision, i.e. sometimes this is also referred to as the non-accommodating state of the lens. This shape reflects the shape of the natural lens and thus serves optimally for any accommodation process as well as any other physiological process.

It is also desirable that the lens implant, in its relaxed state, has a shape suitable for distance vision, and is capable of being transformed from that shape to a shape suitable for near vision. In the prior art, however, this state is achieved by a member protruding from the optic of the lens implant and attempting to directly engage the ciliary muscle, and this excitation does not reflect the excitation used by the human eye.

The lens implant of the present invention contemplates that the ciliary muscle itself does not push the lens implant or the lens capsule, since this excitation is not in accordance with the natural accommodation and can only be switched from the excitation mechanism used by the natural eye to this different excitation mechanism by training the ciliary muscle and the human brain. Instead, in the case of the human eye, upon contraction of the ciliary muscle, the zonular fibers relax and no longer stretch the lens capsule, which previously served to maintain the lens capsule in a flat, elongated state.

It was observed that it is the lens capsule itself that causes the lens material to transition from a flat shape representing far vision to a more spherical shape representing near vision with no or little interaction of the zonular fibers. The lens capsule consists of a basement membrane which is built at its periphery by the construction of the envelope epithelial cells during lens material growth. The lens capsule surrounding the lens is elastic and without any other external forces, the surface of the lens capsule tends to have the shape of the smallest surface per unit volume, i.e. a spherical shape. This is why the combination of lens material and lens capsule has a spherical-like shape desired for near vision without any external forces. However, the tension forces built up by the lens capsule need to overcome the spring force generated by the spring element of the lens implant in the direction of elongation of the spring element. This tension may be in the range of 2 to 50g/mm in the direction of the optical axis for different individuals. The spring constant of the spring element may therefore preferably have a value of less than 20 mN/mm. In either case, the spring constant of the spring element may preferably have a value of less than 550mN/mm, and more preferably have a value equal to or less than 500mN/mm, and more preferably have a value of less than 300 mN/mm.

In the design step, the spring constant of the spring element of the lens implant is of such a size that the force generated by the lens capsule transforms the spring element from its relaxed state into a stretched state (i.e. pulls the spring element). The direction of the transition is determined by the direction of action of the spring element and is typically the optical axis direction of the lens implant. In a very advantageous embodiment, the spring constant is dimensioned such that not only the lens capsule is able to stretch the spring element and thereby enlarge the distance of the viewing element along the optical axis, but also such that the lens capsule is able to separate the viewing element by a distance representing the shape of near vision. The transition should preferably be effected only by the tension in the lens capsule.

It is believed that although the lens of the present invention includes two separate viewing elements, the lens of the present invention may closely approximate the shape and size of the natural lens material, and the lens implant and its actuation may conform to the natural lens and its actuation. Since the excitation is the same as the natural lens, i.e. in particular without the ciliary muscle acting directly on the lens implant, the person implanting the lens does not need to experience, learn and adapt to the different ways of excitation/accommodation of the ciliary muscle in combination with the lens implant holder directly. Furthermore, it is believed that as long as the lens material can be replicated by a synthetic lens implant having its optimal shape and size, the basement membrane forming the lens capsule can better engage with the lens implant due to a better fit and thereby better avoid corrosion and haze. It is believed that the envelope epithelium, which constitutes the basement membrane, will show better sustainability when engaged with a calibrated lens implant that conforms to the shape and excitation of the natural lens.

Further embodiments of the aspects of the invention are mentioned in the dependent claims.

According to another aspect of the present invention, there is provided a method of manufacturing a lens implant according to any of the preceding embodiments. The natural lens is measured. More specifically, the shape and size of the natural lens is measured by, for example, any imaging technique. Data derived from the above measurements may be used to form a lens implant. A spring element may be formed with a spring constant such that it is stretchable under tension caused by the lens capsule surrounding the natural lens. Such tensions may be measured or evaluated. At least one of the two visuals having the desired optical power may be formed from the desired optical power derived from the measurements described above.

According to another aspect of the present invention, there is provided a kit for manufacturing a lens implant according to any of the preceding embodiments. The kit may include a plurality of viewing elements with different focal lengths and/or different shapes and a spring element for retaining the viewing elements.

Any embodiments described with reference to the device should be similarly applicable to the method and kit. Synergistic effects may be obtained with different combinations of the embodiments, although these combinations are not described in detail.

It should also be noted that while all embodiments of the invention relating to methods may be performed in the order of steps described, this is not the only substantial order of method steps. All different orders and combinations of method steps are considered to be described herein.

Drawings

The aspects defined above and further aspects, features and advantages of the present invention can also be derived from the examples of embodiment described below and are explained with reference to these examples. The invention can be described in more detail below with reference to examples of embodiments but to which the invention is not limited.

FIG. 1 shows a longitudinal cross-sectional view of an exemplary intraocular lens implant according to an embodiment of the present invention, wherein FIG. 1a shows the implant in a relaxed state and FIG. 1b shows the implant in a stretched state;

FIG. 2 shows a longitudinal cross-sectional view of an exemplary intraocular lens implant implanted in the lens capsule according to an embodiment of the present invention, wherein FIG. 2a shows the lens capsule in a stretched state and FIG. 2b shows the capsule in a relaxed state;

FIG. 3 shows a longitudinal cut view of the anterior portion of a human eye;

fig. 4 shows a longitudinal sectional view of an anterior segment of an eye with an implant according to an embodiment of the invention in a state adjusted to use distance vision; and

FIG. 5 shows a longitudinal sectional view of an anterior portion of an eye with an implant according to an embodiment of the invention in a state adjusted to use near vision;

Detailed Description

Similar or related elements in the various figures may have the same reference numerals.

In fig. 3, a simplified cross-sectional view of the front of a human eye is preferably shown, comprising a cornea 5, an iris 4 and a lens 1, wherein the lens 1 contains a lens substance 3 in a lens capsule 2. The lens 1 is connected to the ciliary muscle 6 via zonular fibres 7. The ciliary muscle 6 has the form of a ring which can contract and relax. Contraction of the ciliary muscle 6 results in accommodation of what is believed to be the eye focusing into near vision. Relaxation of the ciliary muscle 6 results in a less accommodative state, also referred to as the non-accommodative state of the eye in preparation for distance vision.

In a state where the lens 1 is suitable for distant vision, the ciliary muscle 6 may relax as shown in fig. 3. In this state, the zonular fibers 7 strain and pull the edges of the lens capsule 2 axially outward, so that the lens 1 has a rather flat shape under the dragging force generated by the ciliary muscle 6 and transmitted to the lens capsule 2 by the zonular fibers 7. Thus, the lens capsule 2 itself is not in a relaxed state, but is stretched axially so that it has a rather flat shape, rather than a spherical shape. This configuration of the rather flat shape of the lens 1 enables distance vision, since the lens 1 is not in a shape providing near field focal length.

When switching from distance to near vision, the ciliary muscle 6 contracts so that the diameter of the ciliary muscle 6 around the lens 1 decreases. As a result, the tension of the zonule fibers 7 is reduced, and the zonule fibers 7 can hold the lens 1 only, but do not apply any additional axial force to the lens 1. In this state, i.e. the state in which the lens is not subjected to any external forces, the lens 1 relaxes from its flat shape and returns to its spherical-like shape for near vision, wherein the focal length of the lens 1 for near vision is much smaller than for far vision.

It was observed that the lens substance 3 had a rather flat shape to be suitable for distant vision when no external force was applied to the lens 1. However, when the lens substance 3 is to be encapsulated in the lens capsule 2, also in the absence of any external forces, the lens substance 3 will deform and change from a flatter shape to a more spherical shape for near vision. The lens capsule includes fibers that are constructed during construction of the lens material. In the absence of any external force, these fibers give the lens capsule the lowest energy shape, which results in the smallest surface per unit volume, which appears as a sphere or more preferably a sphere-like structure.

In summary, in the absence of any external force being applied to the lens capsule, the lens material/lens capsule combination will have a rather spherical form, which indicates that the lens is suitable for near vision. As the zonular fibres 7 age with the contracting ciliary muscle 6, the forces generated by the lens capsule are sufficient to affect this deformation of the lens material 3. And returning to distance vision, the dominant surface tension paradigm of near vision will be replaced by outward stretching of the edge of the lens capsule 2 by zonular fibers 7 that cause the zonular fibers 7 to become tensioned in response to relaxation of the ciliary muscle 6. As a result, the lens capsule 2 is stretched axially and has a rather flat form suitable for distance vision.

A lens implant in this context is understood to be an implant that replaces the lens material rather than the lens capsule. Thus, the lens implant is intended to be inserted into the lens capsule.

The embodiment of the invention of fig. 1 shows a longitudinal cut view of an exemplary intraocular lens implant 11. The intraocular lens implant 11 comprises two viewing elements 12 and 13 and a spring element 14 located between the viewing elements 12 and 13. The lens implant 11 is a simple view that is readily understood by those skilled in the art, and other shapes of viewing elements, other forms of spring elements, etc. may also be encompassed by the lens implant 11.

Axis a-a' indicates the optical axis of the lens implant 11. Axis B-B' indicates the longitudinal axis of the lens implant 11. The spring member 14 is connected to both the viewing members 12 and 13 and is arranged such that the distance between the viewing members 12 and 13 along the optical axis can be changed under the influence of a force applied to the viewing members 12 and 13. The sample focus on the optical axis is indicated as FP.

In fig. 1a, the spring element 14 is in its relaxed state, i.e. no external forces act on the spring element 14 or the viewing elements 12 and 13. Fig. 1a shows a lens implant 11, for example, after manufacture and before implantation. Spring element 14 has a distance such that in its relaxed state viewing elements 12 and 13 are spaced apart from each other such that lens implant 11 is focused within this distance.

In this relaxed state, the width w of lens implant 11 along optical axis A-A' between the outer surfaces of first and second viewing elements 12 and 13 may preferably be between 2.5mm and 5.5mm when spring element 14 is in its relaxed state, and more preferably between 3.8mm and 4.0mm when spring element 14 is in its relaxed state.

In contrast, the spring element 14 in fig. 1b is in the extended state of extension, i.e. an external force is applied to the spring element 14 or the viewing elements 12 and 13 and causes the distance between the viewing elements 12 and 13 to increase, and in particular exceeds the distance between the viewing elements 12 and 13 in the unloaded state of the spring element 14 in fig. 1 a. At this point, the distance separating viewing elements 12 and 13 causes lens implant 11 to focus proximally, e.g., at focal point FP. The spring element 14 is in this case in a tensioned state.

In this stretched state, the width of the lens implant 11 along the optical axis a-a' between the outer surfaces of the first and second viewing elements 12 and 13 may preferably be between 2.7mm and 5.7mm when the spring element 14 is in its stretched state, and more preferably between 4.0mm and 4.2mm when the spring element 14 is in its stretched state.

Fig. 2 shows a longitudinal cut-away view of an exemplary intraocular lens implant 11 according to an embodiment of the present invention now implanted in the lens capsule. For the purpose of illustration, it is assumed that there is no other force interaction than the spring force of the spring member 14 and the tension force inherent to the lens capsule 2 (of course also gravity).

In fig. 2b, the lens capsule 2 is in its relaxed state and has the lowest energy shape. Assuming no external force is applied to this implant/capsule combination. It is apparent that the relaxed state of the combination of lens implant 11 and lens capsule 2 is not equivalent to the relaxed state of lens implant 11 itself. Conversely, the lens implant 11 is in its stretched state and adjusted to near distance. The force with which the lens implant 11 switches from its intrinsic relaxed state according to fig. 1a to its stretched state according to fig. 2b is caused by the lens capsule 2. The lens capsule 2 has the lowest energy shape without any external force application, i.e. the lens capsule 2 is in its spherical-like shape as long as the spring members 14 of the lens implant 11 do not resist. The tension forces, in particular the surface tension forces, built into the lens capsule 2 are responsible for this conversion.

However, if the spring element 14 of the lens implant 11 can be designed with such an extremely high spring constant that the spring element 14 will stretch only when a large force is applied, the resistance force caused by the lens capsule 2 will not be sufficient to exceed the spring force and the distance between the viewing elements 12 and 13 will not vary significantly.

In a preferred embodiment, the spring constant of the spring element 14 has a value of less than 550 mN/mm.

In a preferred embodiment, the spring constant of the spring element 14 has a value of less than 20 mN/mm.

In another preferred embodiment, the spring constant of the spring element 14 has a value of more than 2.5 mN/mm.

In another preferred embodiment, the spring constant of the spring element 14 has a value of more than 10 mN/mm.

Any combination of the above ranges of spring constants may be considered as a preferred embodiment: the spring constant may be designed to have one of a range of 2.5mN/mm to 20mN/mm, a range of 10mN/mm to 20mN/mm, a range of 2.5mN/mm to 550mN/mm, and a range of 10mN/mm to 550 mN/mm.

Considering the gravitational field strength, the above range can be described as one of the following: less than 55g/mm, greater than 0.25g/mm, greater than 1g/mm, in a range between 0.25g/mm and 55g/mm, in a range between 1g/mm and 55g/mm, in a range between 0.25g/mm and 2g/mm, or in a range between 1g/mm and 2 g/mm.

For this reason, the spring constant of the spring element 14 may be of such a magnitude that the force generated by the lens capsule 2 transforms the spring element 14 from its relaxed state into a stretched state. In other words, the force generated by the lens capsule 2 needs to exceed the resistance of the spring element 14 in the direction of the optical axis a-a' of the lens implant 11. In a particularly preferred embodiment, the force generated by the lens capsule 2 in this direction needs to exceed the spring force by an amount to allow the travel of the two viewing elements 12 and 13 away from each other until the lens implant 11 is in a condition to enable the near vision force illustrated in fig. 2 b. In a preferred embodiment, the force caused by a mass on the order of g or mg may achieve spring pull in the mm or sub-mm range.

In fig. 2a, the lens capsule 2 is far from its preferred balloon-like shape, but rather has a considerable length and is flat. On the other hand, the lens implant 11 in the lens capsule 2 is now close to its relaxed state, which is defined as the state in which the spring element 14 is in a relaxed state. When the spring member 14 itself returns from its stretched state as shown in fig. 2b to its relaxed state as shown in fig. 2a, it must overcome the tension exerted by the lens capsule 2. This tension may be overcome by a force (as indicated by arrow E) applied to the upper edge of the lens capsule 2. This force may be caused by relaxation of the ciliary muscle 6, which in turn causes tightening of the zonular fibres 7.

The lens implant 11 implanted in the eye is shown in longitudinal cut view in fig. 4. The lens capsule 2 surrounds the lens implant 11. Zonule fibres 7 axially attached to the lens capsule 2 are in their stretched state. A fairly flat capsule/implant combination is formed (at least flatter than the spherical body of lens implant 11 of fig. 5, where the flat capsule/implant combination of fig. 4 represents a state/shape for distance vision). According to fig. 4, relaxation of the ciliary muscle 6 in turn causes tensioning of the zonular fibres 7, which tensioning of the zonular fibres 7 stretches the lens capsule 2.

Fig. 5 in turn shows a longitudinal sectional view of the eye of fig. 4, but in a state adjusted for near vision. Between the states of fig. 4 and 5, the actor (i.e., ciliary muscle 6) contracts to accommodate for near vision. When the ring muscle contracts, the zonular fibers 7 relax and no longer pull the edges of the lens capsule 2. The lens capsule 2 thus has a lowest energy shape like a sphere to the extent allowed by the spring member 14 of the lens implant 11.

Generally, for the intraocular lens implant of the present invention, it is beneficial that the longitudinal dimension of the lens implant along the optical axis in the relaxed state of the spring member is smaller than the longitudinal dimension of the lens implant along the optical axis in the stretched state. This allows the lens implant to adapt to near rather than far vision when in its actuated state. In near vision, the focal distance, which is the distance between the focal point on the optical axis to the lens implant, is smaller than in far vision.

More specifically, the lens implant lacks elements that engage the ciliary muscle upon contraction of the ciliary muscle. That is, the shape of the lens implant is not directly or indirectly controllable by contraction of the ciliary muscle. In other words, the shape of the lens implant will not be affected by the contracting ciliary muscle. Preferably, the shape of the lens implant is influenced only by forces induced via the two viewing elements. This may include the omission of a protrusion designed to shorten the distance between the optic and the ciliary muscle or zonular fibers to engage between the ciliary muscle or zonular fibers. Advantageously, the lens implant lacks elements that exceed the height of the lens capsule in its relaxed state, wherein said height is defined along axis B-B' of fig. 1 a. Advantageously, the lens implant lacks elements projected above the viewing element height in the direction of the viewing element's longitudinal axis. In other words, the upper edge of the viewing element may terminate the crystal in the direction of the longitudinal axis of the crystal.

The viewing element and the spring element may advantageously be integrally formed as a single piece, or alternatively may be formed at least from separate viewing elements and spring elements. The optic may include a lens with an add power, as well as a lens with a negative power.

A kit for manufacturing a lens implant according to one of the previous embodiments may be provided, the kit comprising a plurality of viewing elements having different focal lengths and/or different shapes and at least one spring element for retaining the viewing elements. By means of the kit, individual lens implants can be assembled at an ophthalmic clinic and subsequently the lens implant can be used to replace the patient's lens at the ophthalmic clinic. By means of the kit, a crystal can be selected that matches the patient's desired refractive index, size and shape.

The lens implant preferably conforms to the natural lens in the patient's eye that it should replace. Thus, the lens implant preferably comprises an outer surface which in the implanted state is in contact with the lens capsule, wherein the outer surface has a size and shape adapted to the specific natural lens material. In order to achieve the above requirements, measurements are made of the natural lens, which may be achieved, for example, by computerized imaging from which a computerized model of the lens is obtained. The lens implant can be formed according to the mold and thus can be formed according to the size and shape of the natural lens as allowed by the independent viewing elements and spring elements.

In the previous embodiment, the lens capsule 2 is closed after insertion of the lens implant 11. However, a precise incision, such as a circular incision, may be generated by laser techniques in front of the lens capsule 2, wherein the incision is aligned with the optical axis a-a' such that the incision may not close and remain open even after insertion of the lens implant 11.

While the preferred embodiment to the invention has been illustrated and described, it is to be understood that the invention is not so limited, but rather may be embodied in various specific applications and practices within the scope of the appended claims.

Claims (21)

1. An intraocular lens implant, comprising:

a first viewing element (12) and a second viewing element (13),

a spring element (14) for changing the distance between the first and second viewing elements (12, 13) along the optical axis (A-A') of the lens implant (11) and thereby changing the focal length of the lens implant (11),

wherein the spring member is in a relaxed state in the absence of any external force, and the spring member is in a stretched state when an external force is applied to the spring member,

wherein the lens implant (11) is designed to have a shape providing a focal length suitable for distance vision when the spring element (14) is in its relaxed state,

wherein the spring constant of the spring element (14) is of such a magnitude that a force generated by the lens capsule (2) of the eye for holding the lens implant (11) transforms the spring element (14) from its relaxed state into a stretched state, and

wherein the distance between the first and second viewing elements (12, 13) in the stretched state of the spring element (14) exceeds the distance between the first and second viewing elements (12, 13) in the relaxed state of the spring element (14).

2. An intraocular lens implant comprising:

a first viewing element (12) and a second viewing element (13),

a spring element (14) for changing the distance between the first and second viewing elements (12, 13) along the optical axis (A-A') of the lens implant (11) and thereby changing the focal length of the lens implant (11),

wherein the spring member is in a relaxed state in the absence of any external force, and the spring member is in a stretched state when an external force is applied to the spring member,

wherein the lens implant (11) is designed to have a shape providing a focal length suitable for distance vision when the spring element (14) is in its relaxed state, an

Wherein the spring constant of the spring element (14) has a value of less than 550mN/mm, and

wherein the distance between the first and second viewing elements (12, 13) in the stretched state of the spring element (14) exceeds the distance between the first and second viewing elements (12, 13) in the relaxed state of the spring element (14).

3. The intraocular lens implant of claim 1 or 2,

wherein the lens implant (11) is designed to have a shape providing a focal length suitable for near vision when the spring element (14) is in a stretched state.

4. The intraocular lens implant of claim 1 or 2,

wherein the lens implant (11) is designed to require an external tensile force to stretch the spring element (14) from its relaxed state to its stretched state.

5. The intraocular lens implant of claim 1 or 2,

wherein the spring constant of the spring element (14) has a value of less than 20 mN/mm.

6. The intraocular lens implant of claim 1 or 2,

wherein the spring constant of the spring element (14) has a value of more than 2.5 mN/mm.

7. The intraocular lens implant of claim 1 or 2,

wherein the spring constant of the spring element (14) has a value of more than 10 mN/mm.

8. The intraocular lens implant of claim 1 or 2,

wherein a width (w) of the lens implant (11) along the optical axis (A-A') between the outer surfaces of the first and second viewing elements (12, 13) is between 2.5mm and 5.5mm in a relaxed state of the spring element (14).

9. The intraocular lens implant of claim 1 or 2,

wherein the width (w) of the crystal implant (11) along the optical axis (A-A') is between 3.8mm and 4.0mm in the relaxed state of the spring element (14).

10. The intraocular lens implant of claim 1 or 2,

wherein the width (w) of the crystal implant (11) along the optical axis (A-A') is between 2.7mm and 5.7mm in the stretched state of the spring element (14).

11. The intraocular lens implant of claim 1 or 2,

wherein the width (w) of the lens implant (11) is between 4.0mm and 4.2mm in the stretched state of the spring element (14).

12. Lens implant according to claim 1 or 2, wherein the spring constant of the spring element (14) is of such a size that the force generated by the lens capsule (2) transforms the spring element (14) from its relaxed state into a stretched state, said stretched state being such that the lens implant (11) is shaped to appear as a lens accommodating to near vision.

13. Lens implant according to claim 1 or 2, wherein the longitudinal dimension of the lens implant (11) along the optical axis (a-a ') in the relaxed state of the spring element (14) is smaller than the longitudinal dimension of the lens implant (11) along the optical axis (a-a') in the stretched state.

14. Lens implant according to claim 1 or 2, wherein the viewing element (12, 13) comprises an outer surface for contacting the lens capsule (2) in the implanted state.

15. Lens implant according to claim 1 or 2, wherein the lens implant (11) lacks elements for direct or indirect engagement with the contracting ciliary muscle (6), more particularly the lens implant (11) is designed to be controlled solely by forces induced via the viewing elements (12, 13).

16. Lens implant according to claim 1 or 2, the lens implant (11) being devoid of elements projected above the height of the viewing elements (12, 13) in the direction of the longitudinal axis (B-B') of the viewing elements (12, 13).

17. Lens implant according to claim 1 or 2, wherein the upper edge of the viewing element (12, 13) terminates the lens implant (11) in the direction of the longitudinal axis (B-B') of the lens implant (11).

18. Lens implant according to claim 1 or 2, wherein the viewing elements (12, 13) and the spring element (14) are formed integrally.

19. Lens implant according to claim 1 or 2, wherein the first viewing element (12) is a lens with a positive optical power and the second viewing element (13) is a lens with a negative optical power.

20. A method for manufacturing a lens implant according to any of the preceding claims, comprising:

measuring the natural lens to be replaced by the lens implant (11),

forming a spring element (14), said spring element (14) having a spring constant such that it is stretchable under tension caused by a lens capsule surrounding the natural lens, and

at least one of the two visuals (12, 13) is formed from a desired optical power derived from the above measurements.

21. Kit for manufacturing a lens implant according to any of claims 1-19, comprising a plurality of viewing elements (12, 13) with different focal lengths and/or different shapes and a spring element (14) for holding the viewing elements (12, 13).