The invention relates generally to the field of intraocular lens (IOL), and more particularly, to accommodative IOLs for correction of a patient's vision.
Intraocular lenses (IOL) have been developed for implantation in a person's eye to replace the natural crystalline lens which/that has been clouded by cataract, for example. Traditional cataract surgery involving replacement of a patient's natural lens generally has been successful at providing most patients with high quality distance vision. However, in the past, with some types of IOL's, external vision correction (i.e., reading glasses) has been required for near vision tasks, such as reading a computer screen or print in a book.
More recently, IOLs have been developed to provide a more extended depth of focus for cataract patients that can enable adjustment of vision in response to natural accommodation of the patient's eye. For example, a curvature changing IOL can have a particular base refractive power when it is uncompressed (i.e., before implantation into the eye). When implanted in the eye, the IOL ideally should stay in its uncompressed state before the IOL experiences the natural accommodative forces of the eye. However, current IOLs generally can become compressed to some extent when implanted in the eye and remain in such a condition even before the IOLs undergo accommodation, thus undesirably varying or affecting the base refractive power of the IOL. This changes the refractive power of the IOLs which is undesirable because it becomes challenging to determine what the refractive power of the lens is going to be at distance once it is implanted. Additionally, such lenses further can suffer from contrast sensitivity and visual disturbances like halos and glare.
Accordingly, there is a need for an accommodating intraocular lens that provides high quality near, intermediate and distance vision in response to the accommodation of a patient's eye without visual disturbances and without reduced contrast.
Briefly described, the present invention generally relates to an intraocular lens that is adapted to be inserted into a patient's eye for adjusting the vision thereof. The intraocular lens can be implanted into the patient's eye, such as within the capsular bag thereof, and generally will include a lens element comprising a first optic, a second optic, a third optic, and a fourth optic generally arranged in stacked series. The optics of the lens element can be formed of various optic materials, such as acrylic, silicone and/or hydrogel materials, having different properties. For example, the second optic can be formed of a material of a first stiffness, while the third optic can be formed of a material of a second stiffness that can be different from the first stiffness of the second optic. In addition, the first and fourth optics can be formed of a material of still a further different stiffness than the first stiffness of the material of the second topic and/or the second stiffness of the material of the third optic. Such varying or different stiffness's of the optics can enable varying degrees or amounts of deformation of the optics to facilitate changes in focal points of the IOL. As implanted, the IOL can have a base refractive power, establishing an initial/first or base focal point of the IOL.
The intraocular lens further generally comprises at least one haptic element connected to the lens element, and projecting radially outward therefrom to a location such that the distal ends thereof will be engaged by portions of the ciliary body of the patient's eye. When the patient's eye undergoes accommodation, the ciliary body generally moves inwardly and/or forwardly, causing the at least one haptic element to be moved axially away from the lens element. Such outward movement of the at least one haptic element, and the further flattening of the capsular bag of the eye during accommodation thereof causes compression of one or more of the optics, with at least the second optic being compressed against the first optic and deformed with respect to the first optic to provide a second, adjusted or intermediate focal point for the IOL. Continued compression of the lens element in response to further accommodation of the patient's eye additionally can cause compression and/or deformation of the third optic with respect to the fourth optic so as to provide further a third, adjusted focal point for the IOL distinct from the first focal point.
As such, an intraocular lens system is described that provides monofocal vision at multiple focal points and may restore pre-presbyopia vision to cataract patients.
Various other objects and advantages of the invention will become apparent to those skilled in the art based on the following drawings and detailed description.
Those skilled in the art will appreciate and understand that, according to common practice, the various features of the drawings discussed below are not necessarily drawn to scale, and that dimensions of various features and elements of the drawings may be expanded or reduced to more clearly illustrate the embodiments of the present invention described herein.
As illustrated in the drawings, the intraocular lens (IOL) 100, 500, 600 formed according to the principles of the present invention, is designed to provide monofocal vision at multiple focal points during accommodation of a patient's eye. Accommodation is the process by which the eye changes optical power (by changing natural lens curvature or shape) to maintain focus on an object as its distance from the eye changes. This accommodative process is achieved by contraction or relaxation of the ciliary muscles or body of the patient's eye, acting on the capsular bag B so as to cause deformation of the lens of the eye to adjust focus thereof. Specifically, when the ciliary muscles contract (accommodation), the capsular bag is released from tension. When the ciliary muscles relax (disaccommodation), the capsular bag is pulled and flattened by tension in the zonules connecting the ciliary muscles to the capsular bag.
The IOL, illustrated in the Figures in different embodiments 100 (
The first optic 110, the second optic 120, the third optic 130, and the fourth optic 140 of lens element 105, generally will be formed of soft, flexible, and typically hydrophilic, optical materials, such as silicone, acrylics (for example, AcrySof® acrylic optical material from Alcon Laboratories), hydrogels and/or combinations thereof. The second optic 120 and the third optic 130 further may be formed of or contain a liquid material. In this case, each of the second optic 120 and the third optic 130 further may be encapsulated within a thin, flexible membrane capable of deformation as the fluid material is compressed and/or moved therein.
The second optic 120 generally is formed of a material having a first stiffness and the third optic 130 is formed of a material having a second stiffness. Additionally, the first optic 110 and fourth optic 140 can be formed of a material of a third or different stiffness than the first stiffness of the material of the second optic 120 and the second stiffness of the material of the third optic 130. The first optic 110 and the fourth optic 140 typically will be formed of a material with the highest stiffness among the optics, for example, having a modulus of elasticity on the order of 2+ Megapascals, although greater or lesser stiffness also may be provided and can be of a fixed or negligible base optical power to provide a desired initial correction and/or base or initial focal point when the IOL 100 is in its disaccommodated state. The third optic 130 may be formed of a material with a lower stiffness, such as having a modulus of elasticity in the order of 300-500 Kilopascals, while the second optic 120 may be formed of a material with a least stiffness having a modulus of elasticity in the order of 10-100 Kilopascals, (i.e., stiffness of the material of the third optic can be lower than the stiffness of the material forming the first optic 110 and the fourth optic 140 but higher than the stiffness of the material forming the second optic 120). The optics 110, 120, 130, and 140 may be formed of different materials with different stiffness. Alternatively, the optics 110, 120, 130, and 140 may be formed of the same material having different thicknesses to provide varying stiffness, or the optics 110 and 140 may be formed of a same first material with a desired stiffness, and the optics 120 and 130 may be formed of a same second material with varying thicknesses to provide varying degrees of stiffness and/or resilience.
As further illustrated in
In some embodiments, as illustrated in
Prior to accommodation or when the eye is in a disaccommodated state, IOL 100 generally rests in the capsular bag in a substantially flattened configuration (not otherwise illustrated in the figures) and is held by zonules Z exerting an axial pulling force on the capsular bag when the ciliary muscle or body portions are in a relaxed state. In this state, the at least one haptic element 150 barely contacts the ciliary body, though it may not be affixed to the ciliary body and the ciliary muscles are relaxed, and lens element 105 has its maximum focal length for distant viewing (i.e., a first base or initial focal point for distance vision). Alternatively, the haptics can compress the optics when the capsular bag is flattened and release them when relaxed, in which case the mechanical arrangement can be appropriately modified.
When the eye undergoes accommodation, as indicated in
At least one haptic element 541/542 may be connected to a distal edge 543 of at least one of the first, second, third, or fourth optics. In this embodiment, the at least one haptic element generally will comprise a pair of resilient haptic elements 541/542 attached to the distal edge of at least the first and fourth optics on opposite sides thereof. The haptic elements may comprise resilient elements, here shown as resilient members 545a, 545b, 555a, 555b in the form of curved, circular or “spring-like” elements extending between the first and fourth optics along the distal edges thereof. It will, however, be understood that other configurations of resilient haptic elements having a shape memory and/or desired amount of resilience to apply an expansive force to the optics of lens element 505 as needed also can be used and that the “spring” configuration shown in the drawings is for illustrative principles. As shown in
The first optic 510, the second optic 520, the third optic 530, the fourth optic 540, and fifth optic 550 of lens element 505 generally will be formed of soft, flexible and typically hydrophilic materials, such as silicone, acrylics (for example, AcrySof®), hydrogels and/or combinations thereof. Also, the resilient haptic elements can be formed from a similar material or a material with greater rigidity, and at least a portion of the haptic elements can be formed with or attached to one or more of the optics of the lens element. The second optic 520 and the third optic 530 may be formed of a liquid material. In this case, each of the second optic 520 and the third optic 530 may be encapsulated within a thin flexible membrane capable of deformation as the fluid material is compressed and/or moved therein.
The first optic 510, fourth optic 540 and fifth optic 550 are formed of a material of a first stiffness. The second optic 520 and the third optic 530 can be formed of a material having a second stiffness or different stiffness than the first stiffness of the material of the first, fourth and fifth optics. The first optic 510, the fourth optic 540, and the fifth optic 550 may be formed of a material with highest stiffness among the optics, for example, having a modulus of elasticity in the order of 2+ Megapascals, although greater or lesser stiffness also may be provided and can be of a fixed or negligible optical power to provide a desired correction and/or focal point when the IOL 500 is in its disaccommodated state. The second optic 520 and third optic 530 may be formed of a material with a lower stiffness (i.e., the stiffness of the material of the second optic 520 and third optic 530 can be different from and generally will be lower than the stiffness of the material forming the first optic 510, the fourth optic 540, and the fifth optic 550).
Prior to accommodation or when the eye is in a disaccommodated state, IOL 500 generally floats in the capsular bag in a substantially flattened configuration, (not otherwise illustrated in the figures) and is held by zonules exerting an axial pulling force on the capsular bag when the ciliary muscle or body portions are in a relaxed state. In this state, the at least one haptic element 541/542 barely contacts the ciliary body, though it may not be affixed to the ciliary body, the ciliary muscles are relaxed, and lens element 505 has its maximum focal length for distant viewing (i.e., a first focal point for distance vision).
When the eye undergoes accommodation, the ciliary body contracts. Contraction of the ciliary body causes compression of lens element 505. Contraction of the ciliary muscles/body causes engagement of the ciliary muscles/body with the at least one haptic element 541/542. Such engagement in turn causes movement of the at least one haptic element away from the lens element 105, causing deformation of at least one of first optic 510, second optic 520, third optic 530, or fourth optic 540. When compressed axially, lens element 505 undergoes a first degree of compression. This causes compression of resilient members 555a, 555b first because they are formed of a material having a reduced stiffness than that of the material forming resilient members 545a, 545b thereby applying compressive forces on the fourth optic 540 and fifth optic 550. The compressive forces cause deformation of third optic 530 with respect to the fourth optic 540 and fifth optic 550. This deformation of the third optic 530 provides an intermediate focus (i.e., second adjusted focal point). When compressed further, the lens element 505 undergoes a second degree of compression. This causes compression of resilient members 545a, 545b as well thereby applying compressive forces on the first optic 510 and fifth optic 550. The compressive forces cause deformation of the second optic 520 with respect to the first optic 510 and fifth optic 550 as well, providing another focus (i.e., third focal point).
As such, the IOL 100/500 provides multiple distinct focal points. Utilizing three or more different materials, each with different stiffness can provide three or more distinct focal points. Alternatively, utilizing two materials but with varying haptic stiffness also provides multiple distinct focal points. When implanted in the eye, IOL 100/500 can have has a pre-defined base power. As long as the sizing of the IOL 100 is right (i.e., not too big to be compressed early when implanted), these distinct focal points can enable desired accommodating changes of the refractive power of the IOL at varying distances unlike existing IOLs.
Simple optical calculations assuming that first optic 110/510, fourth optic 140/540, and fifth optic 550 (for IOLs 100, 500) are of negligible power and assuming an index of refraction for all the materials of 1.5418 suggest the following:
Anterior deformable radius refers to the deformation of the radius/curvature of the second optic. Posterior deformable radius refers to the deformation of the radius/curvature of the third optic. Radii and indices of refraction may be varied to achieve desired near, intermediate and distance refractive powers.
It will be understood that while IOL 100/500 is shown and described in example embodiments as having two to four haptic elements or sets of haptic elements spaced about the periphery of the lens element 105/505, any number of haptic elements may be used to support lens element 105/505 as long as lens element 105/505 is substantially centered with respect to the haptics, without departing from the scope of this disclosure.
The foregoing description generally illustrates and describes various embodiments of the present invention. It will, however, be understood by those skilled in the art that various changes and modifications can be made to the above-discussed construction of the present invention without departing from the spirit and scope of the invention as disclosed herein, and that it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as being illustrative, and not to be taken in a limiting sense. Furthermore the scope of the present disclosure shall be construed to cover various modifications, combinations, additions, alterations, etc. above and to the above-described embodiments, which shall be considered to be within the scope of the present invention. Accordingly, various features and characteristics of the present invention as discussed herein may be selectively interchanged and applied to other illustrated and non-illustrated embodiments of the invention, and numerous variations, modifications, and additions further can be made thereto without departing from the spirit and scope of the present invention as set forth in the appended claims.
This application claims the priority of U.S. Provisional Patent Application No. 61/740,571 filed on Dec. 21, 2012.
Number | Date | Country | |
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61740571 | Dec 2012 | US |