Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Eye prosthesis – Intraocular lens
Reexamination Certificate
2000-09-19
2002-06-25
Willse, David H. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Eye prosthesis
Intraocular lens
C623S006470
Reexamination Certificate
active
06409762
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a monobloc intraocular lens made of a flexible material which can be rolled or folded, but which is sufficiently elastic for the lens to regain, after being implanted in an ocular housing, a functional shape corresponding to its initial shape, namely exhibiting a shape memory.
BACKGROUND OF THE INVENTION
Former generations of intraocular lenses were made of a rigid material (such as PMMA) and, in order to be implanted in the eye, a large incision had to be made in the cornea (usually of the order of 6 mm corresponding to the diameter of the optic part of the lens) which presented many disadvantages (post-operative astigmatism, greater risks of surgical complications etc).
In order to overcome these disadvantages, lenses have been proposed made of a flexible material such as silicone or materials described as “hydrogels”, or “acrygel”, or “acrylic” (this term having a different meaning from its common one) which are PMMAs (polymethylmethacrylate) and/or HEMA (hydroxyethylmethacrylate) hydrated to more than 16%, in particular between 24% and 28%. These lenses can be folded or rolled and can be implanted through a smaller incision, in particular through the incision made in order to introduce an instrument into the eye necessary for prior surgical treatment (for example a 3 mm to 3.5 mm incision for ablation of the crystalline lens by phacoemulsification).
Nevertheless, the flexibility of this material then presents the problem of the mechanical stability of the lens after implantation. In particular, in the case of capsular lenses, since the capsular sac has initially a diameter of the order of 10 to 11.5 m, it retracts radially after ablation of the crystalline lens, to a diameter of the order of 9.5 mm or even less.
In order to oppose this retraction, bicomponent lenses have been proposed of which the optic part is flexible while the haptic parts are made of rigid PMMA. These lenses have a complex structure and there is a risk of their flexible optic part deforming under the effect of radial stresses transmitted by the rigid haptic parts.
On the other hand, monobloc lenses have been proposed made of a flexible material, designed to be adapted to radial deformations of the ocular housing. In particular, monobloc lenses are known (EP-579 528) made of a flexible material comprising a central optic part in the shape of a disc defining a principal plane of the lens and a haptic part comprising:
two loops, so-called contact loops, designed to come into contact with an inner wall of the eye, each of these contact loops having the general shape of a convex circular arc, with a convexity directed outwards radially with respect to the optic part, these contact loops being both inscribed in the same circle with a diameter of the order of 11 mm,
for each contact loop, two linking elements extending between the optic part and the contact loop, the lens having, seen in plan, and before implantation, an initial shape which is symmetrical overall with respect to the two perpendicular axes of symmetry contained within the principal plane.
Nevertheless, phenomena of angular displacements (tilt) and/or axial displacements and/or radial displacements (eccentricity) and/or deformations, in particular bending movements, are also sometimes noticed with these lenses after implantation.
Certain monobloc lenses have also been proposed having the haptic parts tilted with respect to the principal plane of the optic part, so that deformations can occur in flexion perpendicular to this principal plane. Nevertheless, with these lenses, the risk of premature displacement and/or deformation phenomena is not overcome. Moreover, these tilted lenses present a not inconsiderable risk of error in positioning the axial direction. Indeed, the relatively small direction of tilt is virtually undetectable by the surgeon, taking into account in particular the flexibility of the material. In addition, since the lens is folded and/or rolled when implanted, an error is possible in assessing the direction of deployment of the lens.
SUMMARY OF THE INVENTION
The object of the invention is to overcome these disadvantages, by providing a monobloc intraocular lens made of a flexible material with a shape memory which can adapt to radial retraction of the ocular housing in which it is implanted without risk of premature displacements or deformations of the optic part.
The object of the invention is more particularly to provide a monobloc intraocular lens of which the haptic part is deformable radially so as to be adapted to the radial retraction of the ocular housing, in particular for the capsular sac with a value of the diameter of the order of 9.5 mm, but which can reach a diameter of the order of 8.5 mm, the optic part remaining in the same principal plane, the symmetries of the lens being at least substantially preserved during deformations of the haptic art (under the effect of stresses which are assumed to be uniformly distributed), the optic part remaining centred on the same axis and not undergoing perceptible deformation affecting its optical properties.
The object of the invention is also to provide a lens which is, and remains, perfectly stable in the ocular implantation housing.
The object of the invention is also to provide a lens which can be easily inserted and in particular may be inserted through a smaller incision, in particular 3 to 3.5 mm, the lens being folded and/or rolled, and without the risk of error in the axial direction in which the lens is inserted by the surgeon.
The object of the invention is also to provide a lens which is simple and inexpensive to produce.
The object of the invention is more particularly to provide a posterior chamber lens, in particular a capsular lens, namely one intended to be implanted in the capsular sac or a lens intended to be implanted in the sulcus.
The object of the invention is also to provide a lens which can be applied to an adult as well as to a child.
To this end, the invention concerns a monobloc intraocular lens made of a flexible material which can be folded or rolled, but which is sufficiently elastic so that the lens regains, after being implanted in an ocular housing with a mean diameter equal to &phgr;m, a functional shape corresponding to its initial shape, comprising a central optic part in the shape of a disc having an optical axis and defining a principal plane of the lens perpendicular to the optical axis, and a haptic part comprising
two loops in contact with an inner wall of the eye, each of these contact loops having an external surface with a generally convex-shaped curve with a convexity directed outwards radially with respect to the optic part,
for each contact loop, two linking elements extending between the optic part and the contact loop, the lens having, seen in plan, and before implantation, an initially overall symmetrical shape with respect to the two perpendicular axes of symmetry contained within the principal plane, the so-called horizontal principal axis and vertical principal axis,
the external surface of each contact loop having a trace in the principal plane which is a convex curve defining an apex of intersection with the horizontal principal axis, and two points, referred to as end points, equidistant from the horizontal principal axis between which the radius of curvature is always greater than 2.5 mm,
wherein:
the circle passing through the apex and the two end points of each contact loop has a diameter &phgr;a greater than or equal to &phgr;m and less than &phgr;m+1.5 mm,
the apices of the two contact loops are separated from each other by a distance D different from &phgr;a and greater than &phgr;a,
the linking elements are adapted so that they can be deformed in flexion in the principal plane in the direction of a reduction in the radial dimensions of the lens by bringing the contact loops towards each other and the optic part, while preserving the symmetry of the lens with respect to the two horizontal and vertical principal axes, and at least substantially without deformati
David Florian
Pynson Joël
Chauvin Opsia, Z.A.C.
Willse David H.
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