Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Reexamination Certificate
2000-11-29
2004-05-11
Schwartz, Jordan M. (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
C623S006370, C623S006560
Reexamination Certificate
active
06733122
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to optical systems, in particular centered optical systems such as intraocular lenses, contact lenses, etc.
BACKGROUND OF THE INVENTION
It is known that the human eye is a complex optical system whose role is to transmit to the brain the images arriving thereat. One of the essential components is the lens. The crystalline lens, located behind the iris, is a transparent gelatinous mass contained in the lens sac.
Opacification of the crystalline lens may occur with increasing age (cataract). All that can be done in that case is to remove the defective crystalline lens and replace it with an artificial crystalline lens or an intraocular lens.
The artificial crystalline lenses known to date are essentially made of acrylic materials, for example polymethyl methacrylate or copolymers thereof, or of silicone derivatives. They have relatively low refractive indices. For silicones, refractive indices of between 1.41 and 1.46 are currently available in the best of cases. For strong corrections, it is thus necessary to use intraocular lenses whose faces have a large curvature and which are consequently very thick in their optical axis.
In order to obtain the best correction without inducing astigmatism defects, it is also necessary to introduce the intraocular lens by making the smallest possible incision. To do this, flexible materials of the largest possible refractive index are sought so as to obtain a very thin intraocular lens.
In a healthy eye the crystalline lens is capable, under the action of muscles, the zonulae, which act upon the lens sac, of modifying its radius of curvature so as to adapt itself to close vision or distant vision.
Replacing the crystalline lens with an intraocular lens no longer allows accommodation to take place.
OBJECT OF THE INVENTION
One of the aims of the present invention is to produce an optical system such as an intraocular lens which overcomes the drawbacks of those of the prior art.
SUMMARY OF THE INVENTION
More specifically, the subject of the present invention is an optical system, in particular an intraocular lens or contact lens, characterized in that it is made of a material whose optical refractive index shows variations in at least one given direction.
According to one characteristic of the invention, the said material is a homogeneous material whose refractive index is variable as a function of its chemical composition.
According to another characteristic of the invention, the said material is a heterogeneous material with molecular orientations which vary in different zones.
According to another characteristic of the invention, the said material is a homogeneous material capable of modifying its optical refractive index when it is subjected to the action of external phenomena.
Another application is the production of bifocal contact lenses, allowing a simultaneous correction of two visual defects (for example myopia and presbyopia):
either by juxtaposition of two materials, a central material and a peripheral material, of similar nature but of different indices, by means of different degrees of grafting onto the same matrix;
or by juxtaposition of two different domains of the same material, the two domains having refractive indices that are different by virtue of a molecular orientation;
or by producing a material whose index varies under the effect of a mechanical stress, for example the pressure of the eyelids.
REFERENCES:
patent: 3800594 (1974-04-01), Hutchings et al.
patent: 4373218 (1983-02-01), Schachar
patent: 4842601 (1989-06-01), Smith
patent: 5136669 (1992-08-01), Gerdt
patent: 5172143 (1992-12-01), Baude et al.
patent: 5258024 (1993-11-01), Chavel et al.
patent: 5731909 (1998-03-01), Schachar
patent: 0 407 294 (1991-01-01), None
by Y. Koike et al., “Gradient-index contact lens”,Applied Optics, vol. 34, No. 22, Aug. 1995, pp. 4669-4673.
Feurer Bernard
Mauzac Monique
Ioltech
Schwartz Jordan M.
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