Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Reexamination Certificate
2000-11-10
2003-07-22
Schwartz, Jordan M. (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
C351S16000R
Reexamination Certificate
active
06595639
ABSTRACT:
The present invention generally relates to ophthalmic lens design and more specifically relates to junctionless ophthalmic lenses and methods for manufacturing ophthalmic lenses having junctionless, three dimensional surfaces.
Contact lens design typically involves a number of steps. The back surface, i.e. posterior surface, of the lens is frequently designed first based on the shape of the cornea and a desired cornea-lens fitting relationship. The front surface, i.e. anterior surface, of the lens is constructed to obtain the necessary refractive correction for the eye and the desired lens performance. Such performance depends on a number of factors, including, but not limited to, lens mass distribution to provide effective eyelid interaction to achieve desired lens movement and lens position, other configurational considerations to provide for the comfort of the.lens wearer and the like.
It is known that the surface topographies of a normal human cornea are often not spherical. For example, it is well known that the corneal surface of an eye has a curve that generally flattens from the center of the cornea to the periphery. A typical approach to create a flatter peripheral lens surface and adequate edge clearance between the edge of the lens and the underlying cornea/conjunctiva, has been to generate a series of conic section curves, each having a radius of curvature larger (i.e. flatter) than the preceding one. Both the anterior and posterior surfaces of conventional contact lens designs have been described in two dimensions by a series of rotationally symmetric surface segments. The surface segments may or may not be offset from the axis of symmetry.
Conventionally designed lenses have been therefor described in two dimensions, such as by a series of rotationally symmetric surface segments, and may be mathematically described thereby. The mathematical descriptions of two dimensional surface sections are made smooth and continuous by compositing, for example, splines or polynomials or blending of the sections. Such smooth, continuous surfaces can be considered to be free of junctions, or junctionless. Thus, ophthalmic lens surfaces with junctions have segments which intersect at discontinuities which can cause discomfort and/or one or more other reductions in lens performance. Thus, it is advantageous to provide an ophthalmic lens with one or more substantially junctionless surfaces.
Ducharme U.S. Pat. No. 5,452,031, which is incorporated in its entirety herein by reference, discloses a contact lens and method for manufacturing a contact lens having a smooth, junctionless surface. More specifically, the Ducharme patent discloses a method for defining the shape of the contact lens surface by relating the corneal surface to a reference curve. The reference curve may be derived from the use of piecewise polynomials and splines, based on point coordinates, resulting in a junctionless surface topography. A computer controlled lathe receives the spline data and generates a signal indicating the necessary lens form to be cut.
Vayntraub U.S. Pat. No. 5,815,237 which is incorporated in its entirety herein by reference, discloses a method for making a contact lens having a peripheral zone surface defined by an exponential function. Similarly, Vayntraub U.S. Pat. No. 5,815,236 and also incorporated in its entirety herein by reference, discloses a method for making a contact lens having a peripheral zone surface defined by a logarithmic function.
Although more closely approximating the curvature of a human eye than earlier spherically based contact lens forms, these now conventional lens computer aided design methods, which are based on using polynomial and spline based interpolations, or exponential and logarithmic mathematical functions, result in a lens constrained to a two dimensional description of the surface topography.
The surface topography of a normal human cornea is often unique and includes areas of irregularity, asymmetry and asphericity that can not adequately be described in two dimensions. Likewise the lens anterior or posterior lens surface shape required to achieve optimal lens performance cannot be adequately described in two dimensions. Particularly in such cases, conventional two dimensional computer aided lens design methods are insufficient.
Designing a lens in two dimensions is inadequate when one or more of the posterior or anterior surfaces involves an asymmetric component, that is a rotationally asymmetric component. Although computer controlled manufacturing techniques have facilitated manufacture of lenses in recent years, such techniques in practice have had only limited application and are inadequate in design and production of lenses having one or more asymmetric components, particularly lenses for use in or on an eye, such as contact lenses, intraocular lenses and corneal onlay lenses. This is because current art in lens design necessarily requires assumptions and compromises to the design by the averaging and compositing of many two dimensional surfaces. Such assumptions and compromises can result in reduced lens performance, both optically and based on user comfort.
It would be advantageous to provide new ophthalmic lenses and methods of designing and producing ophthalmic lenses which address one or more of the concerns with prior lenses, lens designs and production methods.
SUMMARY OF THE INVENTION
New ophthalmic lenses and methods for ophthalmic lens design and manufacture have been discovered. The present lenses and methods offer significant advantages over conventional lenses and methods by providing ophthalmic lenses having substantially smooth, junctionless, three dimensional surfaces which may include one or more rotationally asymmetric components. Lenses produced by the methods in accordance with the invention may include, but are not limited to, ophthalmic lenses structured and adapted for use in or on an eye, for example, all types of contact lenses, such as toric contact lenses, monofocal and multifocal contact lenses and the like intraocular lenses (IOLs), such as anterior chamber IOLs, posterior chamber IOLs and the like, corneal onlay lenses, such as lenses affixed on the cornea, lenses placed or affixed in the cornea and the like. In addition, methods of the present invention may be utilized during corneal refractive laser surgery, for example in the shaping of the cornea.
The present invention provides methods for designing and manufacturing ophthalmic lenses having one or more substantially smooth, junctionless, three dimensional surfaces, for example, wherein the surface or surfaces may have one or more asymmetrical components. The scope of the present invention also includes such lenses, tooling inserts and mold sections used to manufacture such lenses, and methods of producing such tooling inserts and mold sections.
Advantageously, the present invention provides one or more additional, for example, relative to the prior art, degrees of freedom to control lens shape, surface contour, distribution of mass, optical power location and the like parameters within the lens design. Consequently, enhanced ophthalmic lens performance, for example, related to comfort, fitting, vision and/or lens positioning are provided by the present invention.
It will be appreciated that the present methods are especially advantageous when applied to lens design where constraints of symmetry would otherwise present a disadvantage. For example, the methods are very well suited for the design of toric contact lenses, for example a toric contact lens including a posterior toric optical zone and an anterior surface shaped to provide the lens with appropriate optical power and a thickness profile facilitating lens orientation and stabilization in the form of a ballast.
Moreover, the present invention provides for enhanced reproducibility of the ophthalmic lens dimensions and surfaces. The present invention very effectively complements modern CNC lathes which have been used to produce ophthalmic lenses.
In one broad aspect of the present invention, methods for pr
Back Arthur
Ho Arthur
Hollrigel Greg S.
Ocular Sciences, Inc.
Schwartz Jordan M.
Stout, Uxa Buyan & Mullins, LLP
Uxa Frank J.
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