Patent Application
20090292356
The present invention relates generally to the human eye and more particularly to intraocular lenses (IOLs).
The human eye in its simplest terms functions to provide vision by transmitting light through a clear outer portion called the cornea, and focusing the image by way of a lens onto a retina. The quality of the focused image depends on many factors including the size and shape of the eye, and the transparency of the cornea and lens. Age and/or disease often cause the lens to become less transparent. Thus, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is medically known as a cataract.
An accepted treatment for this condition is surgical removal of the lens and replacement of the lens function by an Intra-ocular lens (“IOL”). For many years most IOLs were made of polymethylmethacrylate (“PMMA”), a material with good optical characteristics and compatibility with the tissues of the eye. A disadvantage of PMMA, however, is that it is a very rigid material and an incision must be relatively large for implantation of the IOL. If the optical properties of the IOL are not correctly matched to a patient, a second IOL may be required.
All incisions in the eye are accompanied by trauma, and so, although foldable lenses have been a great improvement, there is still a need for an IOL that can be inserted through a smaller incision than previously possible.
Embodiments of the present invention provide an improved intraocular lens (IOL). A particular embodiment of the intraocular lens (IOL) includes a foldable optic. The IOL also includes multi-hinged haptics coupled to the foldable optic operable to position the IOL within an eye. Each of the multi-hinged haptics includes a first hinge and a second hinge farther from the foldable optic. The first hinge has a first thickness between an anterior side and a posterior side of the multi-hinged haptic, the second hinge has a second thickness between the anterior side and the posterior side of the multi-hinged haptic, and the first thickness is greater than the second thickness. Another embodiment of the present invention provides a method to correct the visual impairment of an aphakic patient by implanting such an IOL.
In an embodiment having multi hinged haptics, the haptics can include a gusset at the intersection of the haptic and the foldable optic, a distal portion having a widened portion, and a number of hinge-forming elbows spaced intermediate to the gusset in the widened portion. The elbows are sized and shaped to allow the haptic to flex while minimizing buckling and vaulting in the IOL.
In other embodiments, an IOL includes a foldable optic. The IOL also includes multi-hinged haptics coupled to the foldable optic. The hinged optics are angled posteriorly to a plane of optic. The foldable optic vaults posteriorly when the IOL is compressed to a diameter of about 10 mm.
Other advantages of the embodiments of the present invention will become more apparent to one skilled in the art upon reading and understanding the detailed description of the preferred embodiments described herein with reference to the following drawings.
For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings in which like reference numerals indicate like features and wherein:
Preferred embodiments of the present invention are illustrated in the FIGs., like numerals being used to refer to like and corresponding parts of the various drawings.
An improved design for an IOL is provided. This IOL includes an intraocular lens (IOL) and a number of haptics. The IOL passes optical energy.
The haptics mechanically couple to the IOL in order to position and secure the IOL within the eye.
IOL 200 may be positioned in the posterior chamber of the eye, replacing the natural lens. This position allows IOL 200 to correct the visual impairment of aphakia (absence of the natural lens). IOL 200 may have a biconvex optic that is shaped to provide increased depth of focus. The IOL 200 may be used in adult patients with and without presbyopia, who desire near, intermediate and distance vision with increased independence from glasses following cataract surgery. In particular embodiments, IOL 200 may include a diffractive optic that can deliver quality vision for various lighting situations. In brightly lit conditions, the central portion 204 sends light waves simultaneously to both near and distance focal points, while, in dimly lit conditions, the surrounding area 206 sends greater light energy to distance vision. It should be understood, however, that the haptics according to various embodiments may be used with any kind of optic suitable for a posterior chamber IOL, which include but are not limited to monofocal, multifocal, toric, spheric, aspheric, and accommodative IOLs.
Alterations to prior art IOLs that would allow for implantation through a reduced-site incision resulted in IOLs that were non-optically stable after implantation. These prior art attempts merely decreased the thickness of the optic and haptics, creating an unstable optic. Embodiments of the present invention provide unique features that result in an optically stable IOL in the compressed state. These features may be implemented in various combinations and include: (1) a reduced nominal optic edge 308 less than about 0.15 mm thick; and (2) angulated haptic/optic planes, ensuring that any vaulting of optic 306 will occur posteriorly. The novice would expect the lens to vault in the anterior direction because of the angle of the haptics compared to the optic. The design actually creates an unexpected, non-vaulting lens (when compressed to about 10 mm). A further advantageous feature is a multi (e.g., double) hinged haptic design. These features result in an optically sound and stable IOL when compressed to about 10 mm, while maintaining acceptable force (3.0E-04 N) in the haptics. As referred to herein, “about 10 mm” refers to an ordinary range of capsular bag variation in which the IOL would foreseeably be implanted.
IOL 300 may be positioned in the posterior chamber of the eye, replacing the natural lens. IOL 300 may have a biconvex optic In particular embodiments, IOL 200 may include a diffractive optic that can deliver quality vision for various lighting situations. In brightly lit conditions, the central portion 204 sends light waves simultaneously to both near and distance focal points, while, in dimly lit conditions, the surrounding area 206 sends greater light energy to distance vision. It should be understood, however, that the haptics according to various embodiments may be used with any kind of optic suitable for a posterior chamber IOL, which include but are not limited to monofocal, multifocal, toric, spheric, aspheric, and accommodative IOLs.
Haptics 302 may be molded in a single piece from the same material as optics 304 and 306. The material used to make IOL 300 may be any soft biocompatible material capable of being folded. Suitable materials are the hydrogel, silicone or acrylic materials described in U.S. Pat. Nos. 5,411,553 (Gerace, et al.), 5,403,901 (Namdaran, et al.), 5,359,021 (Weinschenk, III, et al.), 5,236,970 (Christ, et al.), 5,141,507 (Parekh) and 4,834,750 (Gupta). Optic 310 has an anterior side 314 and a posterior side 312 and may be of any suitable diameter, with between 4.5 mm and 7.0 mm being preferred and 5.5 mm being most preferred. Optic 310 may also be elliptical or oval. The thickness of optic 310 will vary depending on the dioptic power desired and the index of refraction for the material used, but generally will be between 0.4 mm and 1.5 mm.
IOL 300 attempts to maximize the diameter of optic 310 while minimizing the size of the surgical incision needed to implant IOL 300. The material used to make optic 310 may be modified to absorb ultraviolet radiation, or any other desired radiation wavelength.
Haptics 302 comprise gusset 316, first elbow 318, second elbow 324 and distal portion 320 having widened portion 322. Typical tolerances for these features are around 0.3 mm, so that differences within that tolerance should be considered “about” the nominal value. In one embodiment, the thickness of first elbow 318, second elbow 324 and distal portion 320 of haptic 302 is uniform, and preferably between about 0.30 mm and about 0.60 mm, with between about 0.40 mm and about 0.50 mm being more preferred and about 0.43 being most preferred. Gusset 316, however, has a thickness that is reduced toward anterior side 312 of optic 310. Gusset 316 preferably is between about 0.15 mm and about 0.60 mm thick, with between about 0.25 mm and about 0.35 mm thick being more preferred and about 0.30 mm being most preferred. This reduced thickness generally extends from edge 308 of optic 310. The relatively thin cross section of gusset 316 and edge 308 provides a thinner profile when IOL 300 is inserted through the surgical incision. The reduced thickness of gusset 316 also facilitates fluid circulation (e.g., viscoelastic) between posterior side 314 and anterior side 312 of IOL 300. Alternatively, gusset 316 or optic 310 may be provided with other means (such as holes, grooves, notches, micro-fenestration, or protuberances (all not shown)) to facilitate fluid flow between posterior side 314 and anterior side 312 of IOL 300. The relatively long length and radius of distal portion 320 provides greater contact with the capsular bag for better fixation when IOL 300 is implanted in the eye.
First elbow 318 and second elbow 324 create hinges that allow haptic 302 to flex while minimizing buckling and vaulting of optic 310. The relative thickness of the hinges and other portions of the haptics 302 can be adjusted according to the various considerations disclosed herein as being advantageous for various embodiments of the present invention. In particular embodiments, for example, the second elbow 324 may be made thinner than the first elbow 318, in the manner shown explicitly for the haptic-optic junction, which helps to minimize buckling and to maintain stability and to help the lens to vault only posteriorly. Also, widened portion 322 increases the stiffness of haptic 302 just past elbow 324, thereby increasing the strength of haptic 302 at a critical stress point.
The relatively long length and radius of distal portion 420 provides greater contact with the capsular bag for better fixation when IOL 400 is implanted in the eye. Elbow 418 creates a hinge allowing haptic 402 to flex while minimizing buckling and vaulting of optic 410. Widened portion 422 increases the stiffness of haptic 402 just past elbow 418, thereby increasing the strength of haptic 402 at a critical stress point.
Advantages of embodiments of the present invention provide for: (1) an IOL that can be folded and delivered into the capsular bag through a sub 2.1 mm incision; (2) a single-piece design that represents a significant reduction in IOL volume without sacrificing mechanical stability; and (3) an IOL that can be fabricated as one piece.
The relatively long length and radius of distal portion 520 provides greater contact with the capsular bag for better fixation when IOL 500 is implanted in the eye. First elbow 518 and second elbow 524 create hinges allowing haptic 502 to flex while minimizing buckling and vaulting of optic 510. Widened portion 522 increases the stiffness of haptic 502 just past first elbow 518 and second elbow 524, thereby increasing the strength of haptic 502 at a critical stress point.
Force B, due to the shortened transition area and steeper angle in this region of the haptics counteracts the upward vault expected from the angled haptics. This results in a nearly planar compressed state well below the target of 0.5 mm of vault. The remaining force C is the cause for the rotation of the optic. This unique interaction of the forces due to the new IOL design allows the lens to achieve existing design goals.
In summary, embodiments of the present invention provide an improved design for an IOL. This IOL includes a foldable optic and a number of haptics coupled to the optic. The haptics mechanically couple to the IOL in order to position and secure the IOL within the eye. In one embodiment, the haptics are multi hinged while another embodiment allows the haptics to be placed at an angle to the plane of the optic. The haptics flex while minimizing buckling and vaulting of the IOL in order to position and secure the IOL within the eye.
Although the present invention is described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the scope of the invention as described by the appended claims.
This application claims priority under 35 U.S.C. §119 to provisional application Ser. No. 61/055,356, filed on May 22, 2008, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61055356 | May 2008 | US |
