Plastic and nonmetallic article shaping or treating: processes – Optical article shaping or treating – Composite or multiple layer
Patent
1996-06-11
1998-06-09
Vargot, Mathieu D.
Plastic and nonmetallic article shaping or treating: processes
Optical article shaping or treating
Composite or multiple layer
264 25, 264 27, 425808, 425812, B29D 1100
Patent
active
057628360
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of making an intraocular implant including a lens that is flexible, i.e. a lens that can be folded.
2. Description of Related Art
Intraocular implants are becoming widespread. They constitute a system for correcting human eyesight which can, in some cases, replace contact lenses or external correcting eyeglasses. An intraocular implant is essentially constituted by an optical portion that is generally circularly or slightly oval in shape constituting the correcting lens system proper, and by a haptic portion which serves for installing, fixing, and holding the lens portion in the correct position inside the eye.
The most recent intraocular implants are of a monolithic PMMA structure, i.e. the lens and the haptic portion are cut out from a single block of that material. The haptic portion usually comprises two curved and flexible loop-like portions extending from opposite sides of the lens portion and being connected thereto at two points of its periphery that are substantially diametrically opposite.
To provide suitable optical correction, the lens portion must have a diameter of about 5 mm to 6 mm. Given that the material used is rigid, at least in the portion thereof constituting the lens, it is necessary to make an incision in the patient's cornea that is at least 6 mm long, and in practice longer still because of the presence of the haptic portions.
It should also be emphasized that very many implants of that type have been developed, in particular those described in French patent applications Nos. 2 676 358 and 2 676 357, with the implants differing essentially in the shape and the dimensional characteristics of the loops forming the haptic portion, which characteristics are adapted, in particular, to the requirements of practitioners who install such implants in the eyes of patients. In other words, the manufacturers of intraocular implants have now thoroughly mastered defining in particular the loops of such implants, their mechanical properties, in particular concerning bending, and the stability over time of those mechanical characteristics. The operation of removing the natural lens, which operation is usually performed immediately before installing an implant, at least a posterior chamber implant, used to require an incision of large size to be made in the cornea, so monolithic PMMA implants were very well adapted insofar as the incision necessarily made for the cataract operation was quite large enough.
Nowadays, a cataract operation is usually performed by the "phaco-emulsification" operating technique. That technique enables the opaque natural lens to be removed by inserting into the eye an ultrasound probe that is fitted with an irrigation and suction system. The combined action of ultrasound and a flow of BSS serves to remove the natural lens by emulsification.
Compared with prior techniques, that operating technique has the advantage that the instruments used for removal purposes can be inserted into the eye via an incision of small size only made in the cornea, using a knife that is precalibrated to 3.2 mm. It will thus be understood that it would be advantageous to have implants capable of being inserted into the eye via the incision made for the phaco-emulsification operation, i.e. through an incision having a length of about 3 mm or 4 mm.
It will also be understood that monolithic PMMA implants are rigid and unsuitable for that purpose. That is why development has begun on "flexible" intraocular implants which are made, at least in the lens portion thereof, out of a flexible material, thus enabling the lens portion to be folded prior to insertion into the eye through the incision, with the lens portion returning to its initial shape after being put into place in the eye. At present, two broad types of substance are used for making flexible lenses. These substances are usually referred to generically firstly as "flexible acrylics" and secondly as "polysiloxane gel". These substances have the
REFERENCES:
patent: 4501715 (1985-02-01), Barfield et al.
patent: 5074942 (1991-12-01), Kearns et al.
patent: 5182053 (1993-01-01), Creaseman et al.
patent: 5217491 (1993-06-01), Vanderbilt
Copy of European Search Report issued for PCT/FR95/01344.
Bos Gilles
Ortuno Angel
Villain Franck
Vargot Mathieu D.
W.K. & Associes
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