Patent Application
20060001186
The present invention relates to intraocular lenses (hereinafter “IOL”) having at least one optic and at least one haptic. More particularly, in a preferred embodiment, the invention relates to an IOL blank and intermediate assembly for the manufacture of an IOL. In a further preferred embodiment, the invention relates to a method of manufacturing an IOL having first and second optics interconnected by at least one haptic, the optics being movable with respect to each other to provide accommodative effect to an eye. The invention also relates to an IOL made according to the method.
Dual optic AIOLs having first and second optics interconnected by one or more haptics are known. See, for example, Sarfarazi U.S. Pat. Nos. 5,275,623; 6,423,094 and 6,488,708. A method of manufacturing a dual optic AIOL is disclosed in copending application Ser. No. 10/445,762 filed May 27, 2003, the entire disclosure of which is incorporated herein by reference. In that application, the AIOL is injection molded using a mold insert that is removable from the mold core. The mold insert and mold core halves together form the first and second AIOL optic cavities and haptic cavities that interconnect the optic cavities. Once the mold material is introduced and cured in the mold cavity, the mold is opened and the mold insert is removed with the formed AIOL still attached thereto. A paddle arm is attached to the mold insert to assist in handling the mold insert. Since the mold material is flexible (e.g., silicone), the molded AIOL may be carefully stretched off the mold insert with the mold insert passing through the space between two haptics.
While the above described application provides an effective method of manufacturing a dual optic AIOL, it would be desirable to have a semi-finished AIOL blank from which a variety of differently sized and shaped AIOLs may be formed. It would further be desirable to have a semi-finished AIOL and mold insert assembly to facilitate further processing of the semi-finished AIOL into a finished AIOL. Although the invention is described herein in relation to an AIOL having first and second optics, it is understood the invention is applicable to single optic IOLs which may or may not provide an accommodative effect to an eye in which it is implanted.
In a first aspect, the present invention provides a method of manufacturing an AIOL having first and second optics and at least one finished haptic extending therebetween. The method comprises the steps of forming the first and second optics with a semi-finished haptic extending therebetween which is larger than the finished haptic or haptics. The finished haptics are formed by removing or reducing a portion of the semi-finished haptic or haptics. This manufacturing method allows a semi-finished AIOL blank to be initially formed from which a variety of differently sized and shaped finished haptics may be formed. This increases efficiencies in manufacturing in that a single mold tool may be used to create the semi-finished AIOL from which the finished AIOL is made. Thus, separate mold tools need not be made for each haptic size and configuration being manufactured, thereby reducing time and cost to manufacture. The AIOL may be made from any desired and appropriate IOL material with soft materials (e.g., silicone) being preferred to allow the AIOL to be compressed and inserted through a small incision in the eye.
In another aspect, the present invention provides an AIOL blank for making a finished AIOL having first and second optics with one or more haptics extending therebetween. The AIOL blank includes at least one semi-finished haptic larger than the finished haptic or haptics of the finished AIOL. A portion of the semi-finished haptic or haptics of the AIOL blank may be removed or otherwise reduced in area to achieve the desired finished haptic size and shape.
In yet another aspect, the invention provides an assembly comprising a mold insert and an AIOL blank formed about the insert. The insert may be part of an injection mold core and cavity for molding an AIOL blank having first and second optics with at least one semi-finished haptic extending between the first and second optics. The mold insert includes first and second optical surfaces for forming the facing surfaces of the first and second optics of the finished AIOL. The haptic or haptics of the AIOL extend about the insert and interconnect the first and second AIOL optics. Thus, the surfaces of the insert extending between the first and second optical surfaces thereof form the inside surfaces of the AIOL haptic or haptics. The mold core in which the mold insert is positioned in the mold machine forms the remaining surfaces of the AIOL.
After introducing and curing the mold material in the mold cavity, the mold is opened and the mold insert is removed therefrom with the IOL blank formed about and remaining with the insert. The mold insert may thereafter be used as a fixture for holding the AIOL blank when performing any desired processing operations on the AIOL blank (e.g., processing the haptics into their finished form, polishing, extraction, hydration, inspection etc.). At any desired stage, the AIOL may be removed from the mold insert (i.e., before or after one or more subsequent processing steps). This may be done by molding the AIOL with a side opening and carefully stretching the soft AIOL off of the insert, for example. In this regard, the mold insert may be attached to a handle that forms the opening in the semi-finished haptic and wherethrough the mold insert is retracted. Alternatively, the semi-finished haptic may not include a molded-in opening, but rather an opening is cut into the semi-finished haptic while the AIOL is still on the mold insert. The AIOL may then be stretched off the mold insert by retracting the mold insert through the cut opening. Alternatively, one or all the haptics may be cut from the semi-finished haptic while the AIOL remains on the insert. Other possible AIOL-mold insert separation techniques include deforming, collapsing or destroying (sacrificing) the mold insert itself, leaving the AIOL intact and unharmed. In this regard, the mold insert may be made from a variety of materials acceptable for this purpose.
It may also be desirable to form semi-finished optic(s) that may be reduced in area (e.g., diameter) to form the finished optic(s) in a manner similar to the formation of the finished haptics from the semi-finished haptic.
Referring to
Light is focused by the human eye by being refracted through the cornea and then refracted again through the bi-convex natural crystalline lens and is focused on a retina at the back of the eye. Vision from infinity to 250 millimeters is accommodated by varying the shape of the natural crystalline lens 32. More specifically, images at infinity are focused by the ciliary muscle 30 relaxing which permits their peripheral expansion and thus tensioning the zonula 36. Tension of the zonula draws the equator of the capsular bag radially outward and foreshortens the thickness of the lens 32, providing for distance vision. In contrast, near vision is accommodated in a human eye by the ciliary muscles contracting which releases tension on the zonula allowing the lens 32 to thicken into its natural state and thus focusing near objects upon the retina for transmission to the brain by the optic nerve.
A human eye adapts readily to variations in focal length and seamlessly enables a human to view objects at infinity as well as near vision instantly without conscious accommodation. Notwithstanding the perfect vision enjoyed by a majority of the population, an inability to view objects at infinity, or myopia, is frequently encountered. This visual impairment can be corrected by refractive lenses held by frames (spectacles), wearing contact lenses, or refractive surgery. In addition, certain humans do not focus near vision well. This is known as hyperopia and their vision can also be corrected by conventional refractive techniques. In certain instances of severe lack of accommodation these conventional procedures become undesirable and alternative procedures are needed. Although a youth of ten years in age has an ability to change the diopter power by fourteen diopters, this ability gradually decreases with age and by fifty or so the ability of the human eye to accommodate variation in focal length becomes essentially zero. This condition is referred to as presbyopia and a patient often requires correction for both near and far vision. This can be achieved by wearing bifocal glasses or contacts or undergoing refractive surgery for distance and wearing glasses for reading purposes.
In addition to the foregoing more conventional limitations on 20/20 vision in instances of juvenile disease, trauma, and more frequently through age, the natural crystalline lens 32 becomes rigid and opaque to the passage of light. This condition is referred to as a cataract which can be corrected by removal of the lens 32 by a number of techniques, however, the most commonly performed surgery is known as extracapsular extraction. In this procedure, an annular opening in the capsular bag 34 is fashioned about the anterior visual center of the lens, centered by the iris, and then emulsifying and aspirating the hardened lens material. At least one procedure for phacoemulsification, irrigation and aspiration, is disclosed in a U.S. Pat. No. 5,154,696. Once the natural crystalline lens is removed, a bi-convex, fixed focal length optic, of about six millimeters in diameter, is typically fitted into the capsular bag and held in position by radially extending haptics. Although cataract surgery and insertion of an IOL is the most frequently performed surgical procedure in the United States and has achieved a considerable degree of sophistication and success, the IOL is selected with a diopter to achieve for distance vision and near vision must be corrected by wearing reading glasses.
Finally, retinal disease or damage can impair human vision and one form is known as macular degeneration which usually occurs with advance in age. The symptom of macular degeneration can be alleviated, to a degree, by providing high diopters in the 30 to 70 range such that the rods and cones available to receive sight are utilized to their fullest.
From the foregoing context it will be appreciated that improvements in the eye care industry can be made with respect to correction of vision such as hyperopia presbyopia, replacement of vision following cataract extraction and treatment of retinal dysfunction such as macular degeneration.
Referring now to
The forward or anterior optic 42 is preferably bi-convex as depicted in
In one exemplary accommodating IOL system 40, the anterior optic 42 and posterior optic 44 are coupled together by at least one, but preferably a plurality of haptics 46 extending therebetween. The haptics are connected to the peripheral edges of the anterior and posterior optics and are positioned around the peripheral edges of the optics in substantially equidistant peripheral locations. In a preferred embodiment, the haptics subtend an angle of thirty to forty degrees as viewed in a direction of line of sight, (see
Discussion is now turned to the inventive methods and assemblies provided for the manufacture of an AIOL having first and second optics interconnected by at least one haptic.
Referring to
According to a first aspect of the present invention, a method of manufacturing an AIOL having first and second optics and at least one finished haptic extending therebetween is provided. The method comprises the steps of forming the first and second optics with a semi-finished haptic extending therebetween which is larger than the finished haptic or haptics. The finished haptics are formed by removing a portion of the semi-finished haptic or haptics. This manufacturing method allows a semi-finished AIOL 140 to be initially formed from which a variety of differently sized and shaped finished haptics may be formed. This increases efficiencies in manufacturing in that a single mold tool may be used to create the semi-finished AIOL 140 from which the finished AIOL 40 is made. In other words, separate mold tools need not be made for each haptic size and configuration being manufactured.
Thus, in a preferred embodiment, the manufacture of an AIOL system such as AIOL system 40 begins with forming an AIOL blank 140 having first and second optics 142, 144 interconnected by at least one semi-finished haptic 146. The semi-finished haptic 146 has a circumference C1 (
In another aspect, the present invention provides an AIOL blank 140 having first and second optics 142, 144 interconnected by at least one semi-finished haptic or haptics 146 larger than the finished haptic or haptics 46 of the finished accommodating AIOL 40. The semi-finished haptic or haptics 146 of the AIOL blank 140 may be cut or otherwise reduced in area to achieve the desired finished haptic size and shape.
In yet another aspect, the invention provides an assembly comprising a mold insert 150 and an AIOL blank 140 formed about the insert 150 (
After introducing and curing of the mold material in the mold cavity, the mold is opened and the mold insert 150 is removed therefrom with the AIOL blank 140 formed about and remaining with the insert 150. If desired, the mold insert 150 may thereafter be used as a fixture for holding the AIOL blank 140 when performing any desired subsequent AIOL processing operations on the AIOL blank 140 (e.g., cutting of the haptics into their finished form, polishing, extraction, hydration, inspection etc.). At any desired stage, the AIOL blank 140 may be removed from the mold insert 150 (i.e., before or after one or more subsequent processing steps (see
If desired, one or more tabs such as tab 143 seen in
It is noted that the invention is applicable to single optic IOLs as well as dual optic IOLs. In this embodiment, a single optic having one or more haptics attached thereto (e.g., in the shape of haptics 46) would be molded on the mold insert and easily removed therefrom by pulling the optic away from the mold insert. The handle could still be provided on the mold insert for ease of handling the insert and IOL together during subsequent processes such as those discussed above. As in previous embodiments, a semi-finished haptic larger than the finished haptic(s) may be molded and thereafter reduced in size to form the finished haptic(s).
