MXPA99007081A - Progress ads lenses - Google Patents

Abstract

The present invention relates to ophthalmic lenses, in particular, the invention provides ophthalmic lenses with reduced astigmatism, the lenses are composed of a surface and a compensation surface, whose geometries are defined by segments of a suitable size to be defined by a order of one tenth x, and polynomial with Zerni coefficients

Description

PROGRESSIVE ADDICTION LENSES FIELD OF THE INVENTION The present invention relates to ophthalmic lenses. In particular, the invention provides ophthalmic lenses with reduced astigmatism.

BACKGROUND OF THE INVENTION The use of ophthalmic lenses for the correction of ametropia is well known. For example, progressive addition lenses ("PALs") are used for the treatment of presbyopia. In the frontal, or convex, surface of a PAL, it is provided in three zones: a remote addition zone with a restricting energy for near vision; and an intermediate zone between the distance and near zones, with a refractive energy for intermediate distance vision. An astigmatism introduced or caused by one or more of the lens surfaces, or a lens astigmatism are inherent in ophthalmic lenses, such as PALs. In the PALs, for example, the design of the front surface of the lenses is typically restricted by the need to provide a distance zone and a zone of addition of maximum amplitude connected by the intermediate zone that obeys the following conditions: f ( x, y, z) is continuous; df (x, y, z) / r3 (x, y) is continuous; and ¿^ (x, y, z,) / < 3 (x2, y2, xy) is continuous in x, y, z. This surface inevitably introduces an astigmatism in the lens. Generally, the posterior, or concave surface of a lens is not used to compensate for the astigmatism introduced by the frontal surface and, in fact, can also contribute to lens astigmatism. In contrast, the back surface is typically a spherical or toric surface that is intended to be combined with the front surface to provide the user's required prescription. Any number of lens design has been treated to reduce astigmatism by lens. However, although known designs provide some minimal reduction in astigmatism, large areas in the peripheries of the lenses can not yet be used due to astigmatism.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagrammatic view of a front surface and a lens of the invention. Figure 2 is a plan view of a compensation surface of a lens of the invention. Figure 3 is a side view of one embodiment of the lens of the invention.

Figure 4 is a sectional view of the radio distribution of the energy of the general optical zone on a front surface of a lens of the invention. Figure 5 is a plan view of a compensation surface of a lens of the invention. Figure 6 is a plan view of a compensation surface of a lens of the invention.

DESCRIPTION OF THE INVENTION AND ITS MODALITIES PREFERRED The present invention provides lenses, as well as methods for their design and production, in which the astigmatism is reduced by lens, or the astigmatism caused by one or more of the lens surfaces. For purposes of the invention, "lens" or "lenses" refers to any ophthalmic agent including, without limitation, eyeglasses, contact lenses, infraocular lenses and the like. Preferably, the lens of the invention is a telescope and, more preferably, the glasses are a progressive addition lens or a lens in which one or more surfaces provide areas with adequate refractive energy for distance, near and intermediate vision. . In the lenses of the invention, lens astigmatism reductions are achieved by using the compensation surface that compensates for the astigmatism introduced by one or more of the other lens surfaces. "Compensation" means that the lens astigmatism is reduced by about 15% or more, preferably by about 25% or more, more preferably by about 35% or more in the nominal addition energy or desired addition energy of the lens. In one embodiment, the invention comprises, consists essentially of, and consists of a lens having an astigmatism caused by at least one lens surface, the lens comprises, consists essentially of, and consists of a front surface and a compensation surface that compensates for astigmatism by lens. The lenses of the invention can be made of any known material suitable for construction. If the lens is of a homogeneous composition, referring to the fact that the lens material is of a uniform refractive index, the compensation surface may be the back surface of the lens. For example, the lens may have a toroidal, spherical compensation surface designed to compensate for the astigmatism introduced by the front lens surface. Alternatively, the lens may have multilayers, the compensation surface between the front and rear lens surfaces. Thus, in another embodiment, the invention comprises, consists essentially of, and consists of a lens having an astigmatism caused by at least one lens surface, the lens comprising, consisting essentially of, and consisting of a front surface, a surface posterior, and a compensating surface that compensates for astigmatism per lens. The back surface can be of any desired shape such as spherical, spherical, cylindrical or toroidal. The lens of the invention is produced by the method comprising, consisting essentially of, and consisting of the steps of: a) dividing a front surface of a lens into a first plurality of segments, each of the plurality of segments of a size suitable for an order of one tenth of x, and polynomial with Zernike coefficients to define a geometry for each segment; b) providing a compensation surface divided into a second plurality of segments of a suitable size for an order of one tenth x, and polynomial with Zernike coefficients to reduce the geometry for each segment; c) optimize the compensation surface to reduce astigmatism by lens. Although the method for producing and designing the lens of the invention can be used to design any lens, the invention will find its greatest utility in lenses having a surface that produces astigmatism, such as PALs generally, in PALs, said surface will be on the front surface, but can also be found on the back surface. The design method of the invention begins with a three-dimensional description of the front surface by any method known in the art. The front surface can contain the required curves for a PAL and be divided into remote, near and intermediate vision zones, the intermediate vision zone has a gradual change in the refractive energy along an eye path from the area to distance to the near. In the present invention, the front surface is divided or segmented into a number of segments, shown in Figure 1 as 101 to 125. The geometry of each segment is defined in terms of a tenth order x, and polynomial with Zernike coefficients . The number of zones, or segments, is determined by dividing the total area of the surface by the maximum area that can be covered by each segment. One skilled in the art will recognize that said maximum area, or segment size, will depend on the portion of the surface under consideration as well as a consideration of the maximum area that can be adequately molded using a single order of one tenth x, and polynomial with coefficients Zernike. In this way, the maximum area of a segment can vary from, for example, the distance energy zone to the intermediate zone. The coefficients of each polynomial are computed to provide the desired energy profile, to minimize astigmatism, and to provide subsidence or depth at segment boundaries, and the like. Said coefficients can be computed by any known method, for example using the commercially available optical design software. With reference to Figure 1, the axes of coordinates x, y and of the front surface are orthogonal to each other and tangent to the lens surface of their origins. The subsidence of the surface, z, is perpendicular to the plane x, y. The order of a tenth polynomial can be obtained by any known optimization procedure, such as the use of commercial optimization software. The precise polynomial will depend on the weights placed in the various limits that define the boundary conditions of each optimization task. Such limits include, without limitation, continuities of subsidence and tilt with adjacent zones, minimization of Zernike coefficients, variations in energy, and the like. By placing a larger weight on any limit, given the optimization it is directed towards the object. For example, a segment with reduced astigmatism can be obtained if the limitation of sinking continuity is reduced. The mismatch, or discontinuity of the collapse between segments for front surface of the lens of the invention preferably ranges from about 0 to about 0.01 microns. A total of 25 zones are used in Figure 1, which cover a circular area of 23 mm radius. Generally, the front surface is defined in terms of a base spherical surface with sufficient energy to provide the desired distance division correction. The subsidence corresponding to the additional energy desired in each point is added to the base sphere. It is a discovery of the invention that the use of a polynomial and a lower or a tenth order provides an insufficient segment fit. Likewise, it has been discovered that polynomials of an order greater than one tenth are problematic since they are difficult to optimize and require a greater number of computations.

Then a compensation surface is provided. The compensation surface is divided into a number of segments as shown in Figure 2. The number and geometry of the segments is determined as for the front surface. The purpose of the compensation surface is to reduce the astigmatism per lens to approximately 15% or more, preferably approximately 25% or more, more preferably approximately 35% or more of the nominal addition energy of the lens. The compensation surface is defined in terms of a base sphere and a point by point outputs from the sphericity required for the desired compensation. The geometry of each segment of the compensation surface is defined by an order of one tenth x, and polynomial with Zernike coefficients determined as described for the front surface and using an optimization procedure, such as for example one that includes a task of ray tracing that selects a certain diameter of pupil, and then measuring the size and shape of the image on a constructed image surface before optimization starts. The compensation surface is then optimized so that the astigmatism is reduced by lens. One skilled in the art will recognize that any number of optimization methods known in the art can be used, such as for example those described in "General Optics and Optical Design" P. Pouroulis and J. MacDonald, Oxford Univ. Press (1997) incorporated herein by reference.

For example, the test functions can be combined with the front surface geometry and optimized to minimize the Zernike coefficients that control astigmatism. The optimization can be carried out by any known method, such as the use of optical design software and the allocation of weights suited to the Zernike coefficients that control astigmatism. Alternatively, optimization is achieved by creating an image surface and optimizing the eye's rotation point that compensates for the surface segment using a merit function that includes image quality or place size in the image planes as well as the Zernike coefficients that most directly control astigmatism. Additional limits can also be placed on the organization protocol, such as energy as a function of the x and y coordinates, and prism. The collapse of each polynomial in the limits of each segment can be such that a discontinuity of the continuous compensation surface is formed. Continuity refers to the mismatch of the collapse of the segments is approximately 2 microns or more. A continuous surface refers to the mismatch being less than about 2 microns. Preferably, a continuous surface is used. Other limits may be given in order to ensure that the energy, astigmatism and prism inclinations are continuous at the segment boundaries. The compensation surface is designed to provide symmetrical radially aspherical and radially asymmetric corrections for the radially symmetrical and radially asymmetric astigmatisms of the frontal and / or posterior surface. Alternatively, the compensation surface is designed to provide radially spherical asymmetric corrections and a back surface is used to provide radially symmetrical corrections. In the lens of the present invention, if a toric correction in addition to the multifocal addition energy is required, the posterior surface of the lens must be placed with the toric axis in a specific angular orientation with respect to the umbilical meridian. In such a case, the compensation surface can not form the back surface of the lens because the back surface can not provide the composition for lens astigmatism. Thus, in such cases, one or more compensation surfaces between the front and rear surfaces provide all the astigmatism compensation per lens. In an embodiment of the present invention, the compensation surface can form the posterior lens surface, prior to the application of any coating, as long as the toric correction is not required. The compensation surface can also be provided with radially symmetric spherical corrections to minimize spherical aberration and also improve the quality of the image. One skilled in the art will recognize that the shape of the compensation surface will be determined if the surface is used on the rear surface of the lens or an intermediate surface on the front and back surface.

The back surface of the lens of the invention is provided by defining the surface in terms of two radii of curvatures, corresponding to the base and toric curves as well as a radial spherical component that is defined in terms of conical section. The back surface is designed using segments defined by an order of one tenth x, and polynomials with Zernike coefficients, as in the case of the front and offset surfaces. The base curve of the back surface is selected to provide the spherical correction required by the prescription. In addition to providing the correct spherical and toric energies, the back surface can be deflected to provide corrections of a higher order of the Zernike coefficients, such as the correction of a one-third order for a comma, the correction of a one-quarter order for spherical aberration. Those skilled in the art know that the quality of the retinal image is significantly affected by the aberrations that arise from Zernike coefficients of a higher order, in addition to the coefficients of a lower order that control the focal mismatch and astigmatism. The lens of the invention can be made by any convenient method. Preferably, the lens is made by manufacturing a lens having a front surface of a specified geometry and a compensation surface with the desired geometry. The optical material used to form the lens of the invention can be any molten processable thermoplastic resin, including without limitation a biphenol-A polycarbonate, or a thermosetting resin, including without limitation diethylene glycol bisalyl carbonate. The material can be formed in a lens by any known method, such as injection, compression or cast molding, or a combination thereof, using any convenient means of polymerization. In the case where a back surface is provided in addition to the compensation surface, the lens can be formed by any known method. Preferably, a preform, which is located on a front surface and a compensation surface with the desired geometries, is placed with its concave surface in juxtaposition with an O-mold of the mold surface from which it is designed to provide the geometry of desired back surface, such as a toroidal, spherical surface. The space between the preform and the mold is filled with a polymerizable resin and then polymerized to form a rigid, adherent layer that is permanently attached to the preform, the angular orientation between the main meridian on the front surface and the toric axis of the mold can be adjusted before starting the polymerization so that the formed toric axis is in the desired orientation. In a preferred embodiment, the back surface provides only the toric correction, although one skilled in the art will recognize that it is possible to add any desired geometry by recessing the addition surface to the back surface.

In an alternative embodiment of the invention, a layer is provided that is limited by the front surface and the compensation surface that is fabricated from an optical material of a high refractive index, with a refractive index of at least 1.57. Suitable materials include, without limitation, polycarbonate, thermosetting materials incorporating high index monomers, such as styrenes, 4-vinyl anisole, divinylbenzene, terminated acrylate and methacrylate monomers containing aromatic moieties such as bisphenol-A mono- and diacrylate alkoxylated, acrylate of finished aromatic polyurethanes, aromatic epoxides, or thermoplastic materials such as aromatic polyethers, polysulfides and polyethermides. A second layer bonded by the compensation surface and the rear lens surface is provided because it is made of a material with a refractive index of less than about 1.57. The efficiency of the compensation provided by the compensation surface will depend on the difference in the refractive indices of the two layers. The exit of the sphericity, as measured by the subsidence required for compensation, increases with the difference in the refractive indices of the layers. In the embodiment, a part or all of the spherical energy desired by the layer link can be provided by the front and compensation surfaces and the toric energy can be provided by the layer bonded by the compensation and subsequent surface. The difference in the refractive indexes used is the maximum that can be obtained considering the material selected and the need to minimize the interfacial reflection. As an alternative embodiment of the lens of the invention, a part or all of the desired compensation for the compensation surface may be incorporated in the front surface. The back surface is made of a material having a refractive index of at least 1.57, allowing the reduction of the difference in refractive indices between the two layers to be smaller. Said lens can be formed by molding, casting, or grinding the front surface of an optical preform, whose geometry provides a part or all of the spherical and addition energy desired. The concave surface of the preform forms the compensation surface, whose surface is molded, emptied, or shredded to provide the desired compensation geometry. The preform is made of a material that has at least 1.57 refractive index. The surface of the back lens is formed in the preform by any convenient means, preferably by the provision of a mold and the polymerization of a resin layer located between the concave preform surface and the mold surface. The resin refractive index is selected to provide the desired difference in the indices between the layer bonded by the front and offset surface and said bond by the compensation surface and the back surface of the lens. In another alternative embodiment of the invention, one or more compensation surfaces are used to reduce the reflection of said surface and provide correction for the chromatic aberration as shown in Figure 3. With reference to Figure 3, a surface is provided front 31, a first compensation surface 32, and a second compensation surface 33. The back surface 34 provides the toric correction. The material used for the second compensation layer 33 can be selected to have a chromatic dispersion opposite to that of the material used by the first compensation layer 32. Suitable materials useful for correcting chromatic aberration are materials that incorporate strongly absorbent chromoshores in near infrared wavelengths although they have little or no optical absorption on the visible wavelength scale. Examples of such materials include, without limitation, naphthalocyanines exhibiting a strong ligand-filled absorption on the 900 to 1000 nm scale and d2 ad metal complexes with near-infrared ligand-filled absorptions, ie, Fe2 +, Co2 +, Ni2 + chelates, and similar. Preferably, more than one compensation surface is used to correct the chromatic aberration. In another alternative, the restriction that provides continuity of subsidence between the adjacent segments of the compensation surface can be selectively removed in order to further reduce the astigmatism in the segments. It is important to ensure that the resulting subsidence discontinuity does not introduce an unacceptable level of prism jump by adjusting the weights coupled to the minimization of the prism discontinuity during the optimization procedure until the discontinuity is equal to or less than approximately 0.5. diopter. In yet another embodiment, one or more compensation surfaces are used, whose surfaces are continuous, discontinuous, or a mixture thereof. In yet another embodiment, the compensation surface is composed of continuous or discontinuous portions. The invention will be made even clearer by a consideration of the following non-limiting examples.

EXAMPLES EXAMPLE 1 The front surface of a lens of the invention was designed by dividing a surface diameter of 23 mm as shown in Figure 1 into twenty one segments, 101 to 125. Each segment was defined in terms of the order of one tenth, Zernike polynomial described in table 1. The weights together with the minimization of the discontinuity of the collapse in the limits of the segments were adjusted until the discontinuity was 0.01 microns. Table 1 lists the coefficients in the order of a tenth polynomial used for coupling segment 101. Figure 4 shows the distribution of radius in the general optical zone of the front surface CodeV, design software was used commercially available optical from Optical Research Associates, Pasadena California, to mold the optical development of said lens and measure sink values as needed in order to change the magnitude of aggregate energy from 2.00 diopter to 1.75 diopter.

TABLE 1 EXAMPLE 2 Figure 5 illustrates the x and y coordinates of the segments that constitute a compensation surface of the invention. Segment 51 contains the optical center of the lens and is the channel with a flexible zone to the spherical section. Segment 52 is the distance zone and the left sphere. Segment 51 is described by the order of a tenth polynomial described in Table 2 obtained by optimizing said segment for the minimum astigmatism and the best image quality and an image surface as described above. The optimization protocol of specific weights assigned to the collapse is limited to the upper part, y =, 10.0, line, seconds derived from order using the continuity conditions shown in Table 1, Zernike coefficients, and the size of the image point formed on the image surface. The discontinuity of the collapse with channel segment 602 was maintained at a value of 0.01 microns. Table 2 lists the coefficients of the polynomial developed to describe segment 53. The wings, segments 54 and 55, are one-tenth order polynomials optimized with subsidence, inclinations, Zernike coefficients, and dot size on the image surface.

TABLE 2 EXAMPLE 3 Figure 6 shows a discontinuous compensation surface of the invention or surface with a subsidence discontinuity exceeding approximately 2 microns. The spherical zone is represented by segment 601 and channel 602 having an upper bending zone. Segment 601 is spherical and segment 602 is described by a polynomial of the order of one tenth obtained by optimizing said segment for the minimum astigmatism and the best image quality in an image surface. The optimization protocol assigned in specific weights to the sinking is limited to the upper part, and line y = 10.0, the second order derives the continuity conditions that are described in table 1, Zernike coefficients. And the point size of the image formed on the image surface. Similarly, segment 603 of the addition energy zone was described by a polynomial of order of one tenth maintaining the discontinuity of the collapse with channel segment 602 below the value of 0.01 microns. The wings 604 and 603, are horizontal strips optimized with weight in the limit of sinking, but allowing the discontinuity of the sinking is due to a maximum specified value of 15 microns, although it limits the first derivatives as well as the second derivatives and the Zernike coefficients. The weight in the continuity of the prism is relaxed to allow the discontinuity of the prism up to a maximum level of 0.25 diopter.

Claims (28)

NOVELTY OF THE INVENTION CLAIMS

1. A lens having an astigmatism caused by at least one lens surface, the lens comprising a front surface and a compensation surface, characterized in that the compensation surface compensates for the astigmatism per lens.

2. The lens according to claim 1, further characterized in that the lenses are spectacles.

3. The lens according to claim 2, further characterized in that the glasses are a progressive addition lens.

4. The lens according to claim 1, further characterized in that the compensation surface is a continuous surface.

5. The lens according to claim 1, further characterized in that the compensation surface is a discontinuous surface.

6. The lens according to claim 1, further characterized in that the compensation surface comprises a plurality of segments.

The lens according to claim 6, further characterized in that each of the plurality of segments is defined by an order of one tenth x, and polynomial with Zernike coefficients.

8. - The lens according to claim 1, further comprising at least one additional compensation surface.

9. The lens according to claim 8, further characterized in that at least one of the additional compensation surfaces is a discontinuous surface.

10. A lens having an astigmatism caused by at least one lens surface, the lens comprising a front surface and a discontinuous compensation surface, further characterized in that the compensation surface compensates for astigmatism by lens.

11. The lens according to claim 10, further characterized in that the lens is a spectacle lens of progressive addition.

12. The lens according to claim 10, further characterized in that the compensation surface comprises a plurality of segments.

13. The lens according to claim 12, further characterized in that each of the plurality of segments is defined by an order of one tenth x, and polynomial with Zernike coefficients.

14. The lens according to claim 10, further comprising at least one additional compensation surface.

15. The lens according to claim 14, further characterized in that at least one of the additional compensation surfaces is continuous.

16. - A lens having an astigmatism caused by at least one lens surface, the lens comprising a front surface and a continuous compensation surface, further characterized in that the compensation surface compensates for lens astigmatism.

17. The lens according to claim 16, further characterized in that the lens is a spectacle lens of progressive addition.

18. The lens according to claim 16, further characterized in that the compensation surface comprises a plurality of segments.

19. The lens according to claim 18, further characterized in that each of the plurality of segments is defined by an order of one tenth x, and polynomial with Zernike coefficients.

20. The lens according to claim 16, further comprising at least one additional compensation surface.

21. The lens according to claim 20, further characterized in that at least one of the additional compensation surfaces is discontinuous.

22. A progressive addition eyeglass lens having an astigmatism caused by at least one lens surface, the lens comprising a front surface and a discontinuous compensation surface, comprising a plurality of segments, further characterized by each of the Segments are defined by an order of one tenth x, and polynomial with Zernike coefficients.

23. The lens according to claim 22, which also comprises at least one additional compensation surface.

24. The lens according to claim 23, further characterized in that at least one of the additional compensation surfaces is continuous.

25. A progressive addition eyeglass lens having an astigmatism caused by at least one lens surface, the lens comprising a front surface and a discontinuous compensation surface, comprising a plurality of segments, further characterized in that each of the Segments are defined by an order of one tenth x, and polynomial with Zernike coefficients.

26. The lens according to claim 25, further comprising at least one additional compensation surface.

27. The lens according to claim 26, further characterized in that at least one of the additional compensation surfaces is discontinuous.

28. A method for providing a lens comprising the steps of: a) dividing a front surface of a lens into a first plurality of segments, each of the plurality of segments of a suitable size for an order of one tenth x, and polinomiai with Zernike coefficients to define the geometry of each segment; b) providing a compensation surface, divided into a second plurality of segments and a suitable size for an order of one tenth x, and polynomial with coefficients Zernike to define a geometry for each segment; and c) optimizing the compensation surface to reduce astigmatism per lens of the lens.