Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Eye prosthesis – Intraocular lens
Reexamination Certificate
1999-07-20
2003-07-01
Prebilic, Paul B. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Eye prosthesis
Intraocular lens
C623S006560, C523S106000
Reexamination Certificate
active
06585768
ABSTRACT:
This application is 35 U.S.C. § 371 of PCT/JP98/05370, filed Nov. 30, 1998
FIELD OF THE INVENTION
The present invention relates to an intraocular lens and a process for the production of a one-piece intraocular lens. More specifically, the present invention particularly relates to a one-piece intraocular lens which can be inserted through a small incision by bending its optic portion when it is inserted into an eye, a process for the efficient production of the same, and a soft intraocular lens which permits the prevention of deformation of a soft optic portion caused by the shrink of a capsule after intraocularly inserted.
TECHNICAL BACKGROUND
In recent years, with an increase in the population of aged people, senile cataract patients are distinctively increasing. A treatment against cataract is carried out by removing a clouded nucleus and cortex of a crystalline lens and either correcting a vision with an eyeglass or a contact lens or inserting an intraocular lens, while it is general practice to employ a method in which a crystalline lens as a whole is removed and an intraocular lens is fixed.
The above intraocular lens comprises an optic portion which functions as a substitute lens for the crystalline lens removed due to cataract and a narrow and long filament-like haptic portion which is to fix and hold the optic portion in the central position in a capsule. It is known that the above intraocular lens includes an intraocular lens of a type which is formed by separately producing the haptic and optic portions and later combining them (sometimes called two-piece or three-piece type), and a one-piece intraocular lens formed by integrally producing the haptic and optic portions (sometimes called one-piece type). As a material for the optic portion, there has been mainly used polymethyl methacrylate (to be referred to as “PMMA” hereinafter) which is a hard material. The reason for the use of PMMA as a material for the above planting intraocular lens is that it is transparent and excellent in stability in organisms (biocompatibility) and that it has adequate machinability and can provide elaborate lenses stably. As a material for the hepatic portion for holding the above optic portion formed of PMMA, for example, a mono-filament of PMMA, polypropylene or polyimide has been used. Concerning the bonding of the above optical portion and haptic portion, as one type, a small hole for attaching the haptic portion is made in the optic portion, the haptic portion is inserted in the small hole after the optic portion is completed, then the haptic portion is fixed to the optic portion by staking or laser (two-piece or three piece type), or there is a one-piece type integrally formed of PMMA.
On the other hand, with a widened use of an ultrasonic emulsification aspiration method in recent years, there has been developed an intraocular lens which can be inserted through a small incision, for decreasing postoperative astigmatism and an operation stress. That is, the above intraocular lens is formed of a soft material as a material for the optic portion so that it can be bent so as to be inserted through a small incision.
Since, however, the soft material is difficult to machine, i.e., cut and polish unlike a conventional PMMA, the production of the optic portion generally uses a cast-molding method in which a monomer, a prepolymer or an oligomer as a material for forming the optic portion is polymerized in a mold. Further, since it is also difficult to mechanically make a small hole in the method of attaching the haptic portion, it is required to employ a method different from the conventional method.
For producing the above soft intraocular lens, various method, for example, shown below have been so far proposed.
(1) A method of producing an intraocular lens having an easily-non-removable haptic portion, in which the end portion of a filament constituting the haptic portion is permanently deformed to form a mechanical engagement portion having the form of a bulb, etc., or another filament having a mechanical engagement portion is bonded to the end of the former filament to form a terminal portion of the haptic portion and an optical member is mold-shaped with the terminal portion inserted (JP-A-62-142558, JP-A-62-152450).
(2) A method of producing an intraocular lens, in which a soft optical material is polymerized in a mold, then, a mold with a polymerized soft optical material in it is cooled to harden the soft material, a small hole in which a haptic portion is to be inserted and a small hole in which an anchor filament is to be inserted are mechanically made in the optic portion, then, the haptic portion is inserted in the haptic-portion-inserting small hole, a filament formed of the same material as that of the haptic portion is inserted in the anchor-filament-inserting small hole, an intersection of the haptic portion and the anchor filament is irradiated with a laser beam to fuse the haptic portion to the hole, and further, irradiation with a laser beam is effected along the inserting holes (JP-A-4-292609).
(3) A method of producing a foldable intraocular lens, in which a rod of a homopolymer or a copolymer of 2-hydroxyethyl methacrylate (HEMA) was prepared as a foldable optical member, the rod is placed in a tubular mold, a haptic portion is formed around the rod by polymerizing a hard material such as PMMA, then, a disc is obtained by cutting the rod, ground and polished to produce an intraocular lens and the lens is hydrated (allowed to contain water) (JP-A-4-295353).
(4) A method in which a flat plate is prepared from a crosslinked acrylic resin material, placed on a holder and cut into a disc with a lathe at a low temperature, the disc is cut to form a soft optic portion and then the soft optic portion is provided with haptic portions to obtain a three-piece type intraocular lens, or the above flat plate is cut into a material in the form of a lens to obtain an intraocular lens having a foldable optic portion and a soft haptic portion formed of the same soft material as the material of the optic portion (JP-A-1-158949).
(5) A method of producing an intraocular lens, in which an optical material having a diameter of 5 mm and a height of 20 mm was prepared by polymerization and then placed in the center of a cylinder having an inner diameter of 15 mm and a height of 20 mm, a monomer for forming a material of a haptic portion is polymerized in a circumferential portion thereof, and then, a material in the form of an intraocular lens is prepared by cutting and immersed in an alcohol for about 48 hours to soften the optic portion by esterification (JP-A-5-269191).
However, the above methods of producing intraocular lenses all have defects that the procedures are complicated and that the production efficiency is poor. That is, in the above method (1), it is required to make a plastic filament which is to form the haptic portion into a complicated form. The filament which is to form the haptic portion has a diameter of approximately 0.15 mm, and it is required to provide an extremely complicated and fine step for making the end portions of all the filaments in one form by melting the under heat. The haptic portion is required to have a form suitable for holding and fixing in an eye, and the form thereof is elaborately made by thermoforming. That is, when a soft optical material is produced in a mold so as to surround the above elaborately made haptic portion, the haptic portion is again exposed to heating and pressing steps, and the form and dimensions thereof may be altered.
In the above method (2), it is required to cool the material and make two holes, the hole for inserting the haptic portion and the anchor-filament-inserting hole which intersects with the former hole, and it is also required to insert the haptic portion and the anchor filament in the holes and attain the fusing of the haptic portion and the filling the hole with filament by repeatedly irradiating them with laser beam. Therefore, considerably complicated procedures are required.
In the above method (3), the opti
Hamano Migio
Shibuya Akihiko
Yamaya Takuji
Hoya Healthcare Corporation
Nixon & Vanderhye P.C.
Prebilic Paul B.
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