MXPA99009766A - Progressive addition lenses - Google Patents

Abstract

La invención provee lentes de adición progresiva en los cuales se reduce el astigmatismo no deseado del lente y se incremento la anchura del canal a través de las zonas de visión intermedia y cercana en comparación a los lentes de adición progresiva convencionales;este resultado se consigue combinando dos o más superficies de adición progresiva, cuyas superficies combinadas proveen el aumento dióptrico agregado del lente.

Description

PROGRESSIVE ADDICTION LENSES FIELD OF THE INVENTION The present invention relates to multifocal ophthalmic lenses. In particular, the invention provides progressive addition lenses in which the undesirable lens astigmatism is reduced without compromising the functionality of distance and channel widths through the intermediate and near vision zones, as compared to progressive addition lenses. conventional BACKGROUND OF THE INVENTION The use of ophthalmic lenses for the correction of ametropia is well known. For example, multifocal lenses, such as progressive addition lenses ("PAL") are used for the treatment of presbyopia. The surface of a PAL provides far, intermediate and near vision in a continuous and gradual progression of dioptric increase that increases vertically from the far focus to the near focus, or from the top to the bottom of the lens. PALs are attractive to the user because PALs are free from visible edges between the different dioptric augmentation zones found in other multifocal lenses, such as bifocal and trifocal lenses. However, an inherent disadvantage in PAL lenses is the undesirable astigmatism of the lens, or the astigmatism introduced or caused by one or more of the lens surfaces. Generally, the undesirable astigmatism of the lens is located on either side of the near vision zone of the lens and at or near its approximate center it reaches a maximum level that corresponds approximately to the added dioptric increase of near lens vision . Generally, a PAL with an aggregate magnification of 2.00 diopters and channel length of 15 mm will have a maximum localized unwanted astigmatism of approximately 2.00 diopters. The channel width of the lens will be approximately 6 mm in which the unwanted astigmatism is less than or equal to a threshold value of 0.75 diopters. A variety of lens designs have been tried in an attempt to reduce unwanted astigmatism or to increase the minimum channel width or both. However, the current most advanced progressive addition lenses provide only a minimal decrease in unwanted astigmatism while having larger areas in the peripheries of lenses that can not be used due to unwanted astigmatism. Therefore, there is a need for a PAL that reduces the maximum localized unwanted astigmatism, and at the same time, provides an increase in the minimum channel width.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1a is a side view of a lens of the invention. Figure 1b is an astigmatism map of the lens of the Figure 1 a. Figure 2a is a side view of a lens of the invention. Figure 2b is an astigmatism map of the lens of the Figure 2a. Figure 3 is a side view of a lens of the invention. Figure 4a is a side view of a lens of the invention. Figure 4b is an astigmatism map of the Lens of the Figure 4a. Figure 5a is a side view of a lens of the invention. Figure 5b is an astigmatism map of a progressive surface of the lens of Figure 5a. Figure 5c is an astigmatism map of a progressive surface of the lens of Figure 5a. Figure 5d is an astigmatism map of the lens of Figure 5a.

DESCRIPTION OF THE INVENTION AND ITS PREFERRED MODALITIES The present invention provides progressive addition lenses, as well as methods for their design and production, in which the maximum localized unwanted astigmatism is reduced, which is associated with a certain added dioptric increase compared to the lenses of the prior art. Additionally, the width of distance, or width around the optical center of the lens that is free of 0.50 diopters or more of unwanted astigmatism, and a minimum width of the lens channel are suitable for use by the lens user. For purposes of the inventionWith "channel" is meant the vision corridor that is free of astigmatism of approximately 0.75 diopters or greater when the user's eye is scanning from the zone of distance to the near and back area. By "lens" or "lens" is meant any ophthalmic lens including, without limitation, eyeglass lenses, contact lenses, intraocular lenses and the like. Preferably, the lens of the invention is a lens for spectacles. It is a discovery of the invention that the maximum localized astigmatism can be reduced by combining two or more progressive addition surfaces each providing an added dioptric increase that is combined with that of the other surface or surfaces to produce a lens with a higher added dioptric increase than that of individual surfaces. By "added dioptric increase" is meant the amount of dioptric increase difference between the near and far vision zones of a progressive addition surface. The lens of the invention exhibits less localized unwanted maximum astigmatism and a wider channel than would be expected by producing a lens with the same added dioptric magnification using only a progressive addition surface. Furthermore, it is a discovery of the invention that the use of more than one progressive addition surface ensures that the dioptric distance increase and the total added dioptric increase necessary to correct the user's vision are not compromised. It is even another discovery of the invention that when the areas of added dioptric magnification of the progressive surfaces are misaligned with respect to each other, the resulting total unwanted localized maximum astigmatism of the lens is less than the sum of the localized maximum unwanted astigmatism supplied by the individual added dioptric increases of each of the surfaces of progressive addition. By the term "progressive addition surface" is meant a continuous impet spherical surface having far and near vision zones and a zone of increasing dioptric magnification connecting the far and near vision zones. By the term "localized unwanted maximum astigmatism" is meant the highest measurable level of astigmatism in an area of unwanted astigmatism on a surface of a lens. In one embodiment, the lens of the invention consists, consists essentially of, and consists of: a) a first progressive addition surface having one or more areas of localized unwanted maximum astigmatism, and a first added dioptric increase; and b) a second progressive addition surface having one or more areas of localized unwanted maximum astigmatism and a second added dioptric increase, the progressive addition surfaces being disposed in relation to each other so that a portion or all of the areas of maximum localized unwanted astigmatism are not aligned and where the added diopter lens magnification is the sum of the first and second aggregate dioptric increases. In another embodiment, the invention provides a method for producing a lens consisting of, consisting essentially of and, consisting of the steps of: a) supplying at least a first and a second progressive addition surface, having the first addition surface progressive one or more areas of undesired localized maximum astigmatism and a first added dioptric increase, and the second progressive addition surface having one or more areas of unforeseen maximum localized astigmatism and a second added dioptric increase and b) disposing the first and second surfaces of progressive addition such that a portion or the total of the unforeseen localized maximum astigmatism areas are not aligned and the added dioptric magnification of the lens is the sum of the first and second aggregate dioptric increases. By the term "misaligned" is meant that the surfaces, and therefore the areas of unwanted astigmatism, are positioned or arranged in relation to one another so that a portion or the total of the areas of maximum astigmatism do not The desired location of a surface does not substantially match one or more of the unwanted maximum astigmatism areas located on the other surface. Preferably, the misalignment is such that none of the areas of maximum unwanted astigmatism located on one surface substantially coincide with those on the other surface. The progressive addition surfaces used in the lens of the invention can be misaligned by any of a number of methods. For example, the optical centers of fas surfaces can be displaced, one with respect to the other, either laterally or vertically or both. By "optical center" is meant the point on a surface intersected by the optical axis of the lens. One skilled in the art will recognize that, if the optical centers are displaced laterally, the minimum channel width is reduced by the same degree of displacement. Therefore, a progressive addition lens design using a lateral displacement preferably uses progressive addition surfaces with wider channel widths to compensate for the decrease in channel width caused by the displacement. Alternatively, if the optical centers of the surfaces are displaced vertically, the length of the channel will increase. By "channel length" is meant the distance along the central meridian of the surface between the optical center and the upper end of the near vision zone. Therefore, a design using such a displacement preferably uses progressive addition surfaces with shorter channel lengths to compensate. As another alternative, by keeping the optical centers of the progressive surfaces coincident with one another, the centers can be rotated with respect to each other. In a preferred embodiment, each surface is designed to be asymmetric around the center line of its channel. In this case, the areas of maximum unwanted localized astigmatism of the surfaces do not substantially coincide when rotating the optical axes around an axis joining the optical centers of the surface. By "asymmetric" it is meant that the magnification and astigmatism maps of the surface are asymmetric around the central meridian of the surface. The lateral and vertical displacements are made in such a way that dioptric increases in distance and close vision of the lenses are conserved. To properly take the introduction of the prismatic lens magnification, the displacements must be presented so that the optical center of a progressive addition surface moves along a curve that is parallel to the distance curve of the other progressive addition surface. In the case of rotations, the surfaces are rotated around their optical centers so that the distance and near increases are not substantially affected. One skilled in the art will recognize that the rotational misalignment may be in addition to the misalignment performed for purposes of reducing unwanted astigmatism. The amount of misalignment, or vertical displacement, lateral displacement or rotation of the optical centers, is a sufficient amount to prevent substantial overlap, or coincidence, of the areas of undesired maximum localized astigmatism of the progressive addition surfaces. More specifically, it is believed that the misalignment leads to an inequality in the direction of the astigmatic vectors associated with a surface relative to the corresponding astigmatic vectors of the other surface which results in the maximum localized unwanted maximum astigmatism for the final lens being less than if the vectors were aligned. The lateral or vertical displacement may be from about 0.1 mm to about 10 mm, preferably from about 1.0 mm to about 8 mm, more preferred from about 2.0 mm to about 4.0 mm. The rotational displacements may be from about 1 to about 40 °, preferably from 5 to 30 °, more preferred from 10 to about 20 °. As another additional alternative for misalignment, each surface can be designed so that the channel length of the surfaces is of different lengths. In this modality, the areas of maximum unwanted localized astigmatism of the surfaces do not align when the optical centers of the surfaces are aligned. As a result, unwanted astigmatism is reduced compared to a lens of the same total added dioptric increase. The greater the difference between the channel lengths, the greater the reduction in the maximum unwanted localized astigmatism. However, the channel lengths should not be so large as to produce an inequality in the near vision zones so that the close view of the lens user is not compromised. The lenses resulting from this modality will have a channel length that falls between the length of each surface and that depends on the added dioptric increase with ei that each surface contributed to the total added dioptric increase of the lens. The difference in channel length between the surfaces may be from about 0.1 mm to about 10 mm, preferably from 1 mm to about 7 mm, more preferably from 2 mm to about 5 mm. Each of the progressive addition surfaces can be independently on the convex or concave surface of the lens or in a layer between the outer concave surface and the outer convex surface of the lens. Other surfaces, such as spherical and toric surfaces, designed to adapt the lens to the ophthalmic prescription of the lens user may be used in combination with, or in addition to, one or more of the progressive addition surfaces. For example, a progressive addition surface may be combined with a toric surface, such as a concave surface that is a progressive addition surface and has a cylindrical increase in a particular axis. In this case, it is not necessary to provide an added dioptric increase and a cylindrical increase in each combination of desired axis for the lenses. Rather, it has been found that, because the added dioptric increase decreases relatively slowly when one moves horizontally away from the center of the aggregate zone towards the periphery of the lens, a rotational misalignment of the surfaces of the lens can be used. up to about + or -25, preferably + or -20, more preferred + or - 15 ° as long as the desired added dioptric increase for the lens is still achieved. The added dioptric increase of each of the progressive addition surfaces used in the invention is selected so that the sum of its added dioptric increases is substantially equal to the value needed to correct the near vision acuity of the lens user. Additionally, the aggregate dioptric increase of each surface is selected in view of the maximum localized unwanted astigmatism associated with a determined near dioptric increase. Each of the added dioptric increases of the progressive addition surface can be independently from +0.01 diopter to approximately +3.00 diopter, preferably +0.25 diopter to approximately +2.00 diopter, more preferred from around +0.50 to approximately +1 .50. diopters. Similarly, the distance and near dioptric increases for each surface are selected so that the sum of the increases is the value needed to correct the near and distance vision of the user. Generally, the dioptric distance increase for each surface will be within the range of approximately 0.25 diopters to approximately 8.50 diopters. Preferably, the dioptric increase of the distance zone of the concave surface can be + or - from about 2.00 to about 5.50 diopters and for the convex surface + or -approximately 0.5 to 8.00 diopters. The dioptric gain of near vision for each of the surfaces will be approximately 1 .00 diopters to approximately 12.00 diopters. The progressive addition surfaces and lenses of the invention can be formed by any convenient method such as, without limitation, thermoforming, molding, polishing, casting or the like. In a preferred method, an optical preform having a progressive addition surface is used and a second progressive addition surface is emptied onto the preform. In a more preferred method, a preform of the concave surface is used which is a progressive addition surface with a spherical base increase and a cylindrical increase and a progressive addition surface is formed on the front surface by any convenient method of preference by emptying and more preferably by surface casting. The invention will be further clarified by consideration of the following non-limiting examples.

EXAMPLES EXAMPLE 1 Referring to Figure 1 a, the lens 10 of the invention having a convex progressive addition surface 1 1 and a concave progressive addition surface 12 is shown. The surface 1 1 has a zone 13 of distance with a curvature of 6.00 diopters and a zone 18 close with a curvature of 7.00 diopters. The surface 12 has a distance zone 19 with a curvature of 6.00 diopters and a near zone 21 with a curvature of 5.00 diopters. The resulting distance increase of the lenses is 0.00 diopters and the added diopter lens increase is 2.00 diopters, with 1.00 diopters contributed by each of the surfaces 1 1 and 12. As shown in Figure 1a, the optical centers 16 and 17 convex and concave respectively, are displaced one with respect to the other by 4.0 mm. Figure 1b is an astigmatism map of the lens 10 which illustrates the misalignment of the surfaces. Areas 22 and 23 are those of unwanted astigmatism for surfaces 1 1 and 12 respectively. Locations 14 and 15 of the maximum localized astigmatism do not overlap and, therefore, are not additive. The value of 1.90 D of maximum unwanted astigmatism localized for this lens is shown in Table 1 and is significantly less than the value of 2.20 D found in a conventional PAL of the same nearby dioptric increase.

TABLE 1 EXAMPLE 2 A lens with two surfaces of progressive addition, whose misalignment is 8.00 mm is used. The misalignment results in a maximum unwanted localized astigmatism reduction of 0.30 D compared to the prior art lens of Table 1.

EXAMPLE 3 As shown in figures 2a and 2b, the lens is shown with a concave progressive addition surface 25. The surface 25 has curvatures of the near and distance zone of 6.00 and 5.00 diopters, respectively, the convex surface 24 is also shown with curvatures of distance zone and close of 6.00 and 7.00 diopters. The optical center 27 of the surface 25 is rotated by a, an amount of 10 degrees, with respect to the optical center 26 of the convex progressive surface 24. In Figure 2b, the astigmatism map of lens 20 is shown. Areas 31 and 32 show areas of unwanted astigmatism for surfaces 24 and 25, respectively. Areas 28 and 29 of localized unwanted maximum astigmatism for surfaces 24 and 25, respectively, are also shown.

Table 2 shows that the resulting lens has a localized unwanted maximum astigmatism of 1.90 diopters compared to 2.10 diopters for a lens of the prior art.

TABLE 2 EXAMPLES 4-6 The concave progressive addition surface of a lens is rotated 20, 30, and 40 degrees around its optical center with respect to the convex progressive addition surface. The rotations result in maximum unwanted localized astigmatisms of 1.85, 1.75 and 1.41 diopters, respectively, as shown in Table 2.

EXAMPLE 7 Figure 3 shows a concave progressive addition surface 34 positioned between the surfaces 33 and 35 of the lens 30. The lens 30 is made of an optical preform 38 having a refractive index of 1.60 and a pouring layer 39 having an index of refraction of 1.50. The convex surface 33 of the preform 38 has the optical center 36, a curvature of distance of 6.50 diopters and a near curvature of 8.50 diopters. The concave surface 34 of the preform 38 has an optical center 37, a distance curvature ("DC") of 6.50 diopters and a near curvature ("NC") of 0.50 diopters obtained with the formula: NC = DC - aggregate increase x - 1.00 ni - n2 where n, is the refractive index of the optical preform 38 and n2 is the refractive index of the layer 39. The optical center 37 is displaced vertically downwards 4 mm with respect to the optical center 36. The concave surface 35 of the layer 39 includes a cylindric increase of -2.00 D to correct the astigmatism of the user. The lens 30 has an increase in distance of 0.00 diopters, a total dioptric aggregate increase of 3.00 diopters, which is reached by the added dioptric increase of 2.00 diopters of surface 33 and the added dioptric increase of 1.00 diopters of surface area 34 combined. The maximum localized unwanted astigmatism is less than that of a conventional lens with an added dioptric increase inSouth. 3. 00 diopters.

EXAMPLE 8 In figure 4a the lens 50 having a convex ace 51 and a concave ace 52 is shown. The ace 51 is a progressive addition ace with optical center 53. The ace 52 is a combination of progressive-toric addition ace having an optical center 54 displaced vertically downwards 4 mm with respect to the optical center 53. The figure 4b shows the astigmatism map for lens 50 showing the displacement. Areas 55 and 56 are the areas of unwanted astigmatism, with 57 and 58 being their respective localized maximum unwanted astigmatism areas, respectively, for aces 51 and 52. ll is the toric axis for ace 52. The overlap of aces of progressive addition is such that although the near vision and distance zones are conserved, the location of the maximum astigmatisms 57 and 58, located unwanted of each ace do not coincide, and therefore, its effect is not additive .

EXAMPLE 9 The lens 60 is shown in Figure 5a in which a convex progressive-facing ace 61 is shown oriented to the left in combination with a concave progressive addition ace 62 oriented to the right. Each ace is shown individually in Figures 5b and 5c, respectively. The optical centers 63 and 64 of each of the aces are rotated so as to be optically aligned. In Figure 5d it is shown that the left and right orientation of the aces provide misalignment of areas 65 and 66 of unwanted astigmatism of aces 61 and 62, respectively. The maximum unwanted astigmatism localized for the lenses 60 is 1.70 diopters listed in Table 3.

TABLE 3 EXAMPLE 10 An optical preform is produced containing a spherical convex ace with a curvature of 6.00 diopters. The concave ace of the preform is a progressive toric ace with a base spherical curvature of 6.00 diopters, a cylinder curvature of 4.00 diopters on an axis placed on the 0-180 axis, and a near vision zone with an aggregate increase of 1 .00. The near vision zone is placed on the concave toric ace of the preform at 1 1 .25 degrees clockwise from the bottom of the lens (the 270 degree axis). The resulting preform has a distance increase of 0.00 diopters, a cylindrical increase of -2.00 diopters to an axis of 0 degrees and an aggregate increase of 1.00 diopters. A progressive addition glass mold with a base curvature of 6.0 diopters and an added magnification of 1.00 diopters placed on the 270 degree axis is used to empty a UV curable resin layer onto the convex ace of the preform using conventional ace draining techniques. The resulting lens has an increase in distance of 0.00 diopter, a cylinder of -2.00 diopter on the axis of 0 degrees, and an aggregate increase of 2.00 diopter. The misalignment of 1.25 degrees of the frontal and posterior aggregate increases results in a reduction of the localized unwanted maximum astigmatism relative to a lens of the prior art.

Claims (26)

1. NOVELTY OF THE INVENTION CLAIMS 1 .- A lens consisting of a first progressive addition surface having one or more areas of localized unwanted maximum astigmatism and a first added dioptric increase and a second progressive addition surface having one or more areas of maximum unwanted astigmatism located and a second added dioptric increase, the surfaces of progressive addition being disposed in relation to each other such that a portion or all of the areas of localized unwanted maximum astigmatism are misaligned and characterized by the added dioptric increase of the lens is the sum of the first and second aggregate dioptric increases.
2. 2. The lens according to claim 1, further characterized in that the surfaces are arranged in such a way that a portion of the localized unwanted maximum astigmatism areas are misaligned.
3. 3. The lens according to claim 1, further characterized in that the surfaces are arranged in such a way that the total of the areas of maximum localized unwanted astigmatism are misaligned.
4. 4. The lens according to claim 1, further characterized because the progressive addition surfaces are misaligned such that the optical centers of the surfaces are displaced vertically, horizontally, or a combination of both with respect to each other.
5. 5. The lens according to claim 1, further characterized in that the progressive addition surfaces are misaligned such that the optical centers of the surfaces are rotated with respect to each other.
6. 6. The lens according to claim 5, further characterized in that the progressive addition surfaces are asymmetric.
7. 7. The lens according to claim 1, further characterized in that the first and second progressive addition surfaces further comprise a channel having a channel length, the length of the first progressive surface channel being of a different length than the of the second surface of progressive addition.
8. 8. The lens according to claim 1, further characterized in that it comprises a concave surface and a convex surface, the first progressive addition surface being on the concave surface and the second progressive addition surface being on the convex surface.
9. 9. The lens according to claim 1, further characterized in that it consists of a concave surface, a convex surface and a layer in between the two, the first progressive addition surface being on the concave surface or the convex surface and being the second surface of progressive addition in the layer between the concave and convex surfaces.
10. 10. A spectacle lens consisting of a first progressive addition surface having one or more areas of localized unwanted maximum astigmatism and a first added dioptric increase and a second progressive addition surface having one or more areas of maximum astigmatism undesired localized and a second added dioptric increase, the progressive addition surfaces being arranged in relation to each other such that a portion or the total of the unforeseen localized maximum astigmatism areas are misaligned and characterized because the increase The added diopter of the lens is the sum of the first and second aggregate dioptric increases. 1.
11. The spectacle lens according to claim 10, further characterized in that the surfaces are arranged in such a way that a portion of the areas of maximum localized unwanted astigmatism are misaligned.
12. 12. The spectacle lens according to claim 10, further characterized in that the surfaces are arranged in such a way that the total of the areas of maximum localized unwanted astigmatism are misaligned.
13. 13. The spectacle lens according to claim 10, further characterized in that the progressive addition surfaces are misaligned in such a way that the optical centers of the surfaces are displaced, one with respect to the other, vertically, horizontally, or a combination of both.
14. 14.- The lens for eyeglasses in accordance with the claim 11 or 12, further characterized in that the progressive addition surfaces are misaligned such that the optical centers of the surfaces are displaced, one with respect to the other, vertically between about 0.1 mm and 10 mm.
15. 15.- The lens for eyeglasses in accordance with the claim 11 or 12, further characterized in that the progressive addition surfaces are misaligned such that the optical centers of the surfaces are offset, one with respect to the other, laterally between about 0.1 mm and 10 mm.
16. 16.- The lens for eyeglasses in accordance with the claim 11 or 12, further characterized in that the progressive addition surfaces are misaligned such that the optical centers of the surfaces are displaced vertically and horizontally with respect to each other, each of the displacements being independently between 0.1 mm and 10 mm .
17. 17.- The lens for eyeglasses in accordance with the claim 1 or 12, further characterized in that the progressive addition surfaces are misaligned so that the optical centers of the surfaces are rotated approximately between 1 and 40 degrees with respect to each other.
18. 18. - The lens for eyeglasses in accordance with the claim 17, further characterized in that the progressive addition surfaces are asymmetric.
19. 19. The lens according to claim 10, further characterized in that the first and second progressive addition surfaces each additionally comprise a channel having a channel length, the length of the first progressive surface channel being of a different length. to that of the second progressive addition surface, the difference in channel length being from about 0.1 to about 10 mm.
20. 20. The lens according to claim 10, further characterized in that it consists of a concave surface and a convex surface, the first progressive addition surface being on the concave surface and the second progressive addition surface being on the convex surface.
21. 21. The lens according to claim 10, further characterized in that it comprises a concave surface, a convex surface and a layer in between the two, the first progressive addition surface being on the concave surface or the convex surface and the second progressive addition surface being in the layer between the concave and convex surfaces.
22. 22. A method for producing a lens comprising the steps of: providing at least a first and a second progressive addition surface, the first progressive addition surface having one or more areas of localized unwanted maximum astigmatism and a first added dioptric increase and having the second progressive addition surface having one or more areas of localized unwanted maximum astigmatism and a second added dioptric increase; and arranging the first and second progressive addition surfaces such that a portion or the total of the unforeseen localized maximum astigmatism areas are misaligned and the added dioptric magnification of the lens is the sum of the first and second aggregate dioptric increases.
23. 23. The method according to claim 22, further characterized in that the arrangement of the progressive surfaces is performed in such a way that the misalignment of the surfaces is achieved by moving the optical centers of the surfaces one with respect to the other, making rotating the optical centers of the surfaces one with respect to the other, or providing each of the surfaces with a channel having a channel length that is different from that of the other surface.
24. 24. The method according to claim 22, further characterized in that the arrangement of the progressive surfaces is performed in such a way that the misalignment of the surfaces is achieved by displacement of the optical centers of the surfaces, one with respect to the other, vertically or horizontally.
25. 25. The method according to claim 22, further characterized in that the arrangement of the progressive surfaces is carried out in such a way that the misalignment of the surfaces is achieved by rotating, one with respect to the other, the optical centers of the surfaces.
26. 26. The method according to claim 22, further characterized in that the arrangement of the progressive surfaces is performed in such a way that the misalignment of the surfaces is achieved by providing each of the surfaces with a channel having a channel length that It is different from the other surface.