Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Reexamination Certificate
2001-10-29
2004-03-23
Seidleck, James J. (Department: 1711)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
C351S044000, C351S163000, C351S164000, C351S166000, C351S167000, C351S168000, C351S169000, C428S412000, C428S423100, C428S704000
Reexamination Certificate
active
06709107
ABSTRACT:
The present invention relates to the field of composite ophthalmic lenses made, in particular, of organic polymeric materials.
Ophthalmic lenses, and especially spectacle lenses, are optical lenses used for the modification or correction of the vision of patients, in particular of those suffering from defects of vision such as ametropias or presbyopia.
The properties that such lenses must possess are numerous.
They must have optical surfaces of high quality, possess a high degree of transparency and lead to a minimum of optical or chromatic aberrations while remaining thin and light. The lenses must also be resistant to abrasion, shock, to static constraints and be capable of being tinted at the request of the client.
Composite ophthalmic lenses, comprising several layers of organic (and possibly mineral) material have been known for a long time.
They have the merit of taking advantage of the intrinsic properties of each of the materials used.
Moreover, and in a general manner, the process for obtaining them is flexible and is particularly attractive for obtaining ophthalmic lenses combining several optical surfaces for vision correction.
In particular, in order to obtain them, it is possible to use a preform possessing a certain optical power and to mould on to this preform a layer of material, the geometry of the surface of which will modify the initial correction contributed by the preform.
This technique is adapted to construct, for example, a lens comprising a multifocal powered area at the front face, designed to correct presbyopia and, at the rear face, a toric surface designed to correct an astigmatism.
In this case, a layer is moulded on to the front face of a performed lens comprising a rear toric surface. The layer is moulded such that it confers a multifocal power correction on the final lens.
The final desired article is thus obtained without having to carry out a surface processing operation.
This process is described in the prior art, with many variants.
The U.S. Pat. No. 3,248,460 describes a process for obtaining a composite bifocal lens made of organic material, starting from a perform or basic lens, already possessing a certain optical power.
The material to be moulded is placed in a mould, one of the parts of which is constituted by this basic lens.
The material to be moulded is polymerised so as to obtain, by addition of ancillary material to the basic lens, a composite lens of greater power than the basic lens.
This patent gives only a few details concerning the choice of materials to be used.
The U.S. Pat. No. 4,190,621 describes a process for obtaining toric and bifocal lenses.
This process consists of moulding a fine film of material on to a toric, unifocal perform.
The mould used has the same radius of curvature as the preform and a hollow part, the geometry of which is complementary to the geometry of the bifocal area desired in the final composite lens. The moulding is performed on the front face.
In practice, the material to be moulded described is constituted essentially of a monomer of the diethylene glycol diallylcarbonate type, known by its trade name CR39®.
The U.S. Pat. No. 4,873,029 describes composite lenses with a tinted layer.
The lenses are also produced starting from CR39®.
The U.S. Pat. Nos. 5,147,585 and 5,178,800 describe processes for obtaining composite ophthalmic lenses starting from preforms already possessing a first initial correcting power.
The materials used are the polymers obtained starting from CR39® or HIRI® (allyl monomer leading to a polymer with a refractive index of the order of 1.55).
Other materials such as polycarbonate or polymers obtained from styrene derivatives, among others, are mentioned.
The patent application WO-93/21010 describes a composite lens comprising in front an optical preform at least 100 micrometers thick and the hardness of which is at least that of a bare CR39® material and a polymeric layer at the rear the resistance to shock of which is at least that of a bare CR39® material.
The process recommended for obtaining the composite lens is the moulding of the film resistant to shock on to the rear face of the preform.
The U.S. Pat. No. 5,512,371 describes a composite lens comprising an optical quality preform and a hardened part made of organic material, adhering to this preform having a higher resistance to abrasion than the preform and a lower chromatic aberration.
The patent describes more particularly the case of a polycarbonate preform, on the front face of which has been deposited a material of the CR39® type.
The patent application WO-98/03894 describes an ophthalmic lens constituted by the combination of two optical elements of opposite powers leading to a lens with a high Abbe number. The material constituting the optical element of the front part may be a high index polymer obtained from a monomer derived from styrene or divinylbenzene.
The composite lenses described in the prior art possess a certain number of serious drawbacks:
The composite lenses are usually thicker than the lenses obtained from a single basic material, whereas the wearers look for lenses as thin as possible for aesthetic reasons.
Usually, the materials used for the different layers constituting the composite lens possess different refractive indices, and this may lead to optical aberrations.
Usually also, the moulding material undergoes a considerable degree of shrinkage on polymerisation, after being placed in contact with the preform, and this leads to internal tensions within the composite lens which may make the latter more fragile.
In addition, as the preform is thin, these tensions may also lead to uncontrollable deformations of the optical surface of the latter, which it is impossible to correct.
The objective of the present invention is to provide a composite ophthalmic lens and a process for obtaining the latter which resolve the above problems.
The composite ophthalmic lens according to the invention comprises adjacent first and second layers defining between them an interface:
the first layer, at least 200 micrometers thick, of a first polymeric material with a refractive index of at least 1.60, and preferably greater or equal to 1.65 forms a front part of said lens and has a front face constituting a front optical surface S1,
the second layer, at least 200 micrometers thick, of a second polymeric material forms a rear part of said lens and has a rear face constituting a rear optical surface S2, and
the interface between these two layers constitutes an optical surface S3 and is parallel to the rear face of the second layer.
Preferably, the front optical surface S1 is a multifocal, i.e. at least bifocal, or progressive surface whereas the rear optical surface S2 is spherical or toric.
In the context of the present application, a distinction is made between the front and rear parts and the front and rear faces of the composite lens or of one of the layers constituting the composite lens, by taking as reference the eye of the wearer for whom the lens is designed under the normal conditions of use of this lens.
The front part or front face of the lens or of a layer included in this lens is the part, face or layer furthest from the eye of the wearer. The rear part or rear face or rear layer is the part, face or layer closest to the eye.
By optical surface is meant a surface of optical quality.
By progressive surface is meant a surface which comprises at least an area conferring progressive power correction.
Overall, the composite lens according to the invention comprises a front part constituted by a first layer of a very high refractive index which confers, through the intermediary of its two optical surfaces S1 and S3, the entire corrective capacities of the lens.
The second layer forming the rear part of the composite lens constitutes a so-called “plane” lens or lens element, i.e. the two faces that delimit it, constituting the two optical surfaces S2 and S3, are parallel faces and this second layer thus contributes, overall, no appreciable modification to the correction contributed by the first layer of v
Cabeza Stéphane
Jiang Peiqi
Menduni Gilbert
Essilor International (Compagnie Generale d'Optique)
Fulbright & Jaworski L.L.P.
Ribar Travis B
Seidleck James J.
LandOfFree
Composite ophthalmic lens and method for obtaining same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Composite ophthalmic lens and method for obtaining same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Composite ophthalmic lens and method for obtaining same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3220066