MXPA98008839A - Progress lens - Google Patents

Abstract

An ophthalmic lens element that includes a lens surface having a superior vision zone that provides a good optical quality with a low power, preselected surface over a large area of vision. The predetermined power is determined by the prescription of the patient distance (Rx), the horizontal adjustment position being usually determined by the distance between the user's pupils, and the vertical adjustment position is usually determined by means of the midpoint of the vertical frame a lower vision zone of greater surface power that provides a greater margin of vision for intermediate distances, and a relatively low astigmatism corridor that extends between, where the contours of the average surface power and / or the surface astigmatism within from the lower viewing area, the upper vision zone and the corridor are generally symmetrical around a vertical lens meridian

Description

PROGRESSIVE LENS DESCRIPTION OF THE INVENTION: The present invention relates to a progressive ophthalmic lens and in particular to progressive ophthalmic lenses having an ophthalmic function in the distant view region. It is a feature of the present invention to provide spectacles designed specifically for distance and intermediate vision and to provide improved user flexibility, with an improved angular range of visual fields and greater tolerance for adjusting varibility. Numerous progressive lenses are known in the prior art and progressive lenses generally have a distant and intermediate vision zone in which the intermediate zone joins the intermediate and distant zone in an aesthetically acceptable manner, in the sense that it does not present discontinuity in the lens that is visible to people who observe the user's glasses. The intermediate zone must be optically acceptable in the sense that there should be no line or corridor called the path of the eye along which the line of sight moves when going between the intermediate and distance zones, and along which the optical power of the lens increases more or less uniformly. It is normal to select an eye path with a slope to accommodate the natural convergence of the eyes along the path. However, in order to provide at least acceptable distance and intermediate zones, commitments must be made in any or all of the zones. Furthermore, in the prior art, in order to provide a range or margin of distance and intermediate areas in relation to the optical power that allows an optimum adjustment of the glasses for most of the patients, an abundant family of progressive lenses that They present different powers of distance and intermediate zone have become necessary. It would be an important advance in the technique if lenses could be designed that required a smaller family of individual types of lenses to meet the needs of distance vision and in the intermediate zone of a wide range of patients. This would be very similar to the number of unprocessed parts in a series of single vision reading lenses. In the prior art, the high power shift between the intermediate vision and distance zones results in large aberrations that greatly restrict the allowed adjustment positions for the lenses. It would be an important advance in the technique if the ophthalmic lenses could be designed with a reduced sensitivity to horizontal adjustment errors (such as errors in the pupil distance of the user) and in the height of vertical adjustment in reference to the measurement errors of the structure and conformation of the face. This would make such lenses similar in their ease of adjustment to single vision reading lenses. It is therefore an object of the present invention to overcome or at least alleviate one or more of the difficulties including the lenses with a surface having a superior vision zone that provides good optical quality at a predetermined low surface power over an area large vision, the predetermined power is determined by the prescribing distance of the seeing, (Rx) the horizontal adjustment position usually determined by the user's intermediate pupillary distance, and the vertical adjustment position usually determined by the center point of the vertical structure; a lower surface power high vision zone provides an improved vision margin for intermediate or smaller viewing distances; and a corridor of relatively low astigmatism extends intermediate; wherein the contours of the average surface power and / or the surface astigmatism within the upper vision zone, lower vision zone and corridor are generally symmetric with respect to a vertical meridian of the lens. In contrast to the prior artIt is a feature of the present invention to give emphasis to both distance and intermediate vision, with the aim of providing glasses designed specifically for distance and intermediate vision. This results in a lens that is superior to conventional progressive lenses for distance and intermediate vision and also superior to single-vision distance lenses in providing an extended range or range of distances where vision is well delineated. In order to do this the distance vision zone has been specified having a precise optical power and a large size and the lower power zone is determined indirectly from the distance power through the addition of a power change to the optical power of the distance vision zone. The magnitude of this distance change can be selected so that the power of the resulting lower zone is generally adequate for intermediate distance vision. There may not be a portion of the lens that is suitable for intermediate vision. In the progressive lens element according to the present invention, the optical quality can be brought to a maximum in the upper vision zone and the optical power of the lower vision zone is determined indirectly by the application of an increase in power from the optical power of the upper vision zone. This can mean a limited area of vision that can be covered within the lower vision zone by the vertical and horizontal movement of the eyes only.

A consequence of the lenses that preferably provide only a distance and intermediate vision is that the total power change between the upper and lower zones will be substantially lower than in a conventional progressive lens. The resulting reduced power gradient leads to a broader runner that is more tolerant of horizontal adjustment errors, and less sensitive to vertical adjustment errors compared to conventional progressive lenses with the same power progression length. Applicants have further discovered that the eye trajectories used to design the progressive lenses of the prior art do not provide the desired visual fixation of the user for the intermediate tasks in the lower portion of the lens. The applicants have discovered that the locus of the user's visual fixation can generally coincide with the vertical meridian of the lens element, can be set in general horizontal to the nasal direction within the lower vision zone, suitable for vision intermediate. Therefore, it is a preferred aspect of the present invention that a progressive ophthalmic lens including a lens surface having a superior vision zone that provides good optical quality at a predetermined low surface power in a large viewing area is provided.; the predetermined power is determined by the distance prescribing distance (Rx) the horizontal adjustment position is determined by the user's internal pupillary distance. And the position of the vertical adjustment is determined by the central point of the vertical structure; A lower surface power high vision zone provides an improved vision margin for intermediate or smaller distances; and a relatively low astigmatism corridor that extends intermediate; the lens element has a progressive design depending at least in part on the visual fixation site, the visual fixation site is generally established nasally within the lower vision zone, the degree of horizontal settlement increases with increasing power of addition. Preferably the medium surface power contours and / or the surface astigmatism within the lower vision zone, upper vision zone and corridor are symmetrical with respect to a vertical meridian of the lens. The variation in the lens amplification gives a required variation or adjustment of the setting on the lens surface to correct the positioning point on the visual fixation site, such as the measurement point of the lower area, so that the convergence appropriate can be achieved for the working distance and the visual task. The amplification of the lens can in turn be influenced by surface recommendations including the thickness of the lens and the pantoscopic leaning of the lens. The length of the horizontal array is determined by the consideration of the lens magnification and the visual convergence requirements of the user in the lower viewing area. The determination of visual convergence requires consideration of the minimum working distance for intermediate vision. The horizontal setting of the lower vision zone, when present, may vary up to about 2.m, preferably up to about 1.50mm, depending on the prescribing requirement of the particular user. A typical value is approximately l.25mm for a +2. OOD distance prescription. In general, the extension of the lateral establishment will increase with the addition power of the user. By the term "visual fixation locus" place of visual fixation, we understand the set of points that are the intersection of the surface of the lens and the line of vision of the patient when the patient is fixed on objects in the median plane. The term does not mean a path of continuous eye movement. Rather, the place of visual fixation indicates the set of points corresponding to objects placed in different ways in the median plane. As a result, the points in different places on the place of visual fixation are provided having a sufficient power for a comfortable use of the appropriate object distances. In the preferred embodiments of the present invention, the visual fixation site lies along a line of essentially zero astigmatism in the intermediate region. In the distance vision zone, the zero surface astigmatism line widens into an area of essentially zero surface astigmatism. By corridor we understand an area below the zone of variable power distance linked by nasal and temporal contours of tolerable aberration for foveal vision. In a preferred embodiment the visual fixation site lies at the horizontal center points between the nasal and temporal contours of tolerable aberration for foveal vision. The corridor has a corridor length (L) that corresponds to the length of the segment of the visual fixation site that extends from the vertical height where the visual progression begins at the vertical height of the intermediate zone measurement point. For example, in a typical lens element according to the invention, the power progression starts at the height of the adjustment cross (FC). As used herein the term "lens element" refers to all forms of refractory optical bodies employed in the ophthalmic art, including but not limited to pieces of finished lenses that require further elaboration for the prescription of a particular patient. They also include all the moulders used in the manufacture of progressive glass lenses and molds for the casting of progressive lenses in polymeric material such as the material sold for the CR39 brand. As used herein the term "astigmatism" refers to surface astigmatism which is a measure of the degree to which the curvature of the lens varies between intersecting planes that are normal to the surface of the lens at a point on the surface. Here the term lens meridian is used referring to an imaginary line of symmetry drawn through the power progression center of a lens as adjusted for the user. Here the term zone width is used as the horizontal distance between similar contours of surface astigmatism, surface power, optical power, or lack of definition index or other appropriate optical properties defining an optical quality threshold, for example 0.50 D contour of surface astigmatism.

Preferably the upper vision zone of the progressive ophthalmic lens according to the invention defines a relatively large distance of the vision zone. The predetermined optical power of the upper vision zone may for example be from about -10.0 D to + 10.0 D. In a particularly preferred arrangement, the upper vision zone may be sufficient to allow a full aperture distance consistent with a magnifying glass lens. a single vision, at an approximate height of 10mm above the geometric center of the lens element. The progressive ophthalmic lens can be designed to have uniform power growth from the center of one vision zone to the other along a corridor of relatively low astigmatism. The corridor or path of the eye between the low vision zone and the upper vision zone in this mode can generally extend along the vertical lens meridian. This can be contrasted with a traditional progressive lens where the slow path has slope. An advantage is, what is to be understood, that there is no need to produce separate right and left lenses. This also allows for simplified lens processing and processing procedures. The corridor or path of the eye may be relatively broad and preferably relatively short, offering a short transition from one vision zone to the other. The progression length can vary from about 5% to 95% of the nominal addition power. The magnitude of progression power along the corridor may reach from about 0.50 D to 2.50 D. In another more preferred aspect, the average surface power and / or surface astigmatism contours may be uniformly separated above and below the region of the surface. lens runner. Such uniform separation of the contours creates a continuous expansion of the width of the fields of vision, but preferably with a minimum tendency to close the upper or lower ends of the lens. This can be compared to the two viewing zones that would result if the lens were built to grow symmetrically from design centers that corresponded substantially with the centers of those viewing areas. In a preferred embodiment, the lens surface can be described by equations of the types presented in US Pat. Nos. 4, 676,610 and 4,838,675 of the applicants, which are incorporated by reference. The elements of progressive ophthalmic lenses can be of the reduced gloss type, for example as described in the international patent application PCT / AU97 / 00180 of the applicants which is included as reference.

The progressive ophthalmic lens element can be a glass lens for the sun, for example of the type described in the international patent application PCT / J97 / 00188"Improved one-vision lens" of the applicants, which is included as reference. The ophthalmic lens can be formulated from any suitable material. A polymeric material can be used. The polymeric material can be of any suitable type. The polymeric material may include a thermoplastic or thermosetting material. A material of the diallyl glycol carbonate type can be used. The polymeric article can be formed from crosslinkable polymeric pouring compositions, for example as described in US application 4,912, 155. In application 07 / 781,392, in Australian application 50581/93 and 50582/93 and in European patent 453159 A2 , which are included by reference. Such cross-linked polymeric pouring compositions may include a diacrylate or dimethacrylate monomer (such as polyoxyalkylene glycol diacrylate or dimethacrylate or a fluorene diacrylate or bisphenol dimethacrylate) and a polymerizable comonomer, for example methacrylates, acrylates, vinyls, vinyl ethers, allyls , aromatic olefins, ethers, polythiols and the like. For example, in Australian application 81216/87 which is incorporated by reference, the applicant describes a crosslink coating composition that includes at least one polyoxyalkylene glycol diacrylate or dimethacrylate and at least one polyfunctional unsaturated crosslinking agent. Furthermore, in the Australian application 75160/91 which is included by reference, the applicant describes a polyoxyalkylene glycol diacrylate or dimethacrylate.; a monomer including a recurring unit derived from at least one polymerizable bisphenol monomer radical capable of forming a homopolymer having a high refractive index of more than 1.55 and a urethane monomer having 2 or 6 terminal groups selected from a group comprising acrylic and methacrylic groups. Such polymer formulations are UV cured or cured by a combination of UV and thermal treatment. The range of optical lenses sold under the designations "Spectralite" by the applicants has been found favorable. The polymeric material may include a dye, preferably a photochromic dye, which for example, may be added to the monomeric formulation used to produce the polymeric material. The variation of the color depth can be minimized by incorporating a pigment or dye into one or more layers of the optical article. The ophthalmic lens element according to the present invention can further include standard additional coatings on the front or back surface including electrochromic coatings. The front surface of the lens may include an anti-reflective (AR) coating, for example, of the type described in US Pat. No. 5,704,692 of the applicants, which is included by reference. The front surface of the lens may include an abrasion resistant coating for example of the type described in US Pat. No. 4,954,591 of the applicants, which is included as a reference. In an especially preferred form, the laminated ophthalmic article may include an inner layer that provides the desired optical properties of the type described in Applicant's international application PCT / AU 96/00805, which is included as a reference. The front and rear surfaces may also include one or more additions, used in casting compositions such as inhibitors, dyes, including thermochromic and photochromic dyes, for example as described above, polarizing agents, UV stabilizers and materials capable of modifying the refractive index. The ophthalmic lens element according to the present invention can be designed using a method similar to that described in the applicant's international patent application PCT / E97 / 00105, which is included as a reference. Accordingly, in another aspect of the present invention, there is provided a method for designing a progressive ophthalmic lens element, wherein the lens element is formed by: a) providing a representation of a progressive lens surface in the form of a surface function base having a superior viewing area that provides good optical quality at a predetermined lower surface power over a large viewing area; that predetermined power is determined by the distance prescription of the one who sees (Rx) the horizontal adjustment position is usually determined by the distance between the user's pupils, and the vertical adjustment position is normally determined by the center point of the vertical structure; a lower vision area of higher surface power provides an improved range of vision for intermediate or lower viewing distances; and a corridor of relatively low astigmatism extends intermediate; wherein the medium surface power and / or surface astigmatism contours within the lower vision zone, the upper vision zone and the corridor are generally symmetric with respect to a vertical lens meridane. b) modify the base surface function of the lens surface based on a selected merit function to maximize the viewing width and minimize the surface astigmatism; and c) mold a lens having a surface area of lens formed according to the modified surface function; Step b) can be carried out by finite element methods. A merit function can be used to achieve the desired location of the selected isoastigmatism curves. One or both of the nasal and temporal isoastigmatisrao curves of the selected diopter value can be adjusted locally as required to give the corridor centerline the desired slope at the locations consistent with the required power progression. The analysis of the finished elements can be used to solve the corresponding ophthalmic problem. In a preferred aspect, the lens surface includes a relatively short corridor where the surface power increases approximately linearly from the upper vision area to the lower vision zone. In another preferred embodiment, where the visual fixation site has to establish a horizontal distance as described above, the method further includes: d) rotating all or part of the representation of the lens surface to achieve horizontal settlement and variation of establishment required by the progressive increase of power in the corridor.

The rotation stage can be applied before or after the modification step b). The present invention will now be described more fully with reference to the accompanying drawings and examples. It should be understood that the following description is only by way of example and is not limiting, for the generality of the invention. Manufacture of lenses and associated tool. The methods for producing progressive lenses from a final surface function are well known to the technicians. For example, the manufacture of such progressive lenses can be carried out using the aforementioned final surface function to provide height values for a multiplicity of points, for example in centers at 1 millimeter, and then by means of a controlled milling machine numerically, producing a porous ceramic moulder with a surface configuration corresponding to the aforementioned height values. The porous ceramic moulder, thus prepared, can then be used in a conventional manner to form a progressive surface of a lens of glass lens shapes by buckling techniques. The porous moulder can also be used to form a mold part, which can be used to form the progressive surface in a cast lens in a conventional lens casting process. The techniques of such shapers are described, for example, in US Pat. No. 4,062,629 to Inthop 9 see columns 14 and 19). It is evident that, due to the inherent limitations of the milling process and the need to then perform one or more steps before reaching the desired progressive lens surface in a lens or in a lens shape, the surface of the progressive lens obtained does not can match in a mathematically exact way with the expressions used to generate the instructions of the milling machine. Another inaccuracy inherently induced in the process is caused by the fact that milling machines necessarily employ a finite grid size. The correspondence between the final surface final surface function and the fabricated surfaces will vary slightly as it moves from the former to the lens or from the former to the mold to the lenses. However, it has been found in practice that the variations introduced in this way are limited and do not result in a lens whose performance is unpredictable. The mold of the lenses is clearly the tangible article whose shape will almost correspond to the final surface function. The present invention will be described more fully with reference to the appended examples and drawings. It should be understood, however, that the description that follows is only illustrative and should not be taken in any way as restrictive of the generality of the invention described above.

Figures 1 (a), (b) and (c) illustrate the surface of astigmatism contours, the mid-surface power contours and the path profile of the eye, respectively of a progressive lens element according to the present invention having a base area of 5.00 D and 0.50D of adding power. Figures 2 (a), (b) and (c) illustrate the contours of surface astigmatism contours of average surface power and profile of the ocular trajectory, respectively of a progressive lens element according to the present invention having 5. OOD of base area and 1.00 D of power addition. EXAMPLE 1 The following description illustrates the operation of the method of the present invention by means of specific numerical examples. A progressive lens element having a base area of 5.00 D and 0.50D of addition power, as illustrated in Figure 1 (a), (b) and (c) according to the present invention was constructed from the following way: The required characteristics of the lens element are the following: Base 5.00 D @ 1.530 Addition 0.50 D material index 1.50 Distance L of the eye rotation axis 27 mm Distance RX 0.00D Distance of intermediate refraction Zref 2.00 m Length of the corridor 10 mm EXAMPLE 2 Example 2 illustrates a progressive lens having a base curve of 5.00 D and an additive power of 1.0 D. A progressive lens element having a base area of 5.00 D l.OOD additive power, as illustrated in Figure 2 (a), (b) and (c) according to the present invention was constructed as before. The required characteristics of the lens element are the following: Base 5.00 D @ 1.530 Addition 0.50 D Index of the material 1.50 Distance L of the axis of eye rotation 27 mm RX of the distance 0.00D Distance of the intermediate refraction Zref 2.00 m Length of the corridor 10 mm Finally, it should be understood that various modifications and / or alterations can be made without departing from the spirit of the present invention as indicated herein.

Claims (17)

1. CLAIMS 1. - An ophthalmic lens element that includes a lens surface having a superior viewing area that provides a good optical quality with a low power predetermined surface over a large viewing area. The predetermined power is determined by the prescription of the patient distance (Rx), the horizontal adjustment position being normally determined by the distance between the user's pupils, and the vertical adjustment position is usually determined by means of the midpoint of the vertical frame; a lower vision zone of higher surface power that provides a greater margin of vision for intermediate distances; and a relatively low astigmatism corridor that extends between; where the contours of the average surface power and / or the surface astigmatism within the lower vision zone, the upper vision zone and the corridor are generally symmetrical around a vertical lens meridian.
2. 2. - A progressive lens element according to claim wherein the optical quality is maximized in the upper vision zone and the optical power of the lower vision zone is determined indirectly by the application of an increase in energy of the optical power of the upper vision zone.
3. 3. - A progressive lens element according to claim 2 in which the upper vision zone is adapted for distance vision and the lower vision zone is adapted to the intermediate vision.
4. 4. - A progressive lens element according to claim 1, wherein the lens element has a progressive design depending at least in part on the visual fixation point, the visual fixation point is usually set nasally within the lower vision area, the degree of horizontal fixation increases with increasing addition power.
5. 5. - A progressive lens element according to claim 3 in which the width of the upper vision zone provides a full opening distance view at a height of approximately 10 mm above the geometric center of the lens element.
6. 6. A progressive lens element according to claim 1 in which the total power change between the upper and lower viewing zones is substantially less than would be recommended for a conventional reading setting.
7. 7. A progressive lens element according to claim 6 in which the resulting reduced power gradient leads to a broader corridor.
8. 8. - A progressive lens element according to claim 7 in which the surface power increases approximately line from the datum line to the intermediate reference point in the lower vision zone.
9. 9. A progressive lens element according to claim 7, wherein the runner has an advance length of about 5 mm to 20 mm and a forward advance of magnitude of about 0.50D to 2.50 D.
10. 10. - A progressive lens element according to claim 1 in which the average surface power is almost constant above the horizontal line passing through the center of the lens and all variations in average power and surface astigmatism occur below of this line.
11. 11. - A progressive lens element according to claim 1 wherein the contours of the average surface power and / or the surface astigmatism are generally uniformly separated on either side of the region of the lens corridor, such so there is a constant expansion of the width of the visual fields.
12. 12. - A progressive ophthalmic lens element that includes a lens surface having a superior viewing area that provides good optical quality with a predetermined low surface power over a large viewing area; the predetermined power is determined by the prescription of the patient's distance (Rx) the horizontal adjustment position is determined by the distance between the user's pupils, and the vertical adjustment position is usually determined by means of the midpoint of the frame vertical; a lower vision zone of higher surface power that provides a greater margin of vision for intermediate or smaller viewing distances; and a relatively low astigmatism corridor that extends there; a lens element having a progressive design depending at least partially on the visual fixation point, the visual fixation point is generally set nasally within the lower vision zone, the degree of horizontal fixation increases with increasing addition power.
13. 13. - A progressive lens element according to claim 12 in which the contours of the average surface power and / or the surface astigmatism within the lower viewing zone, the upper viewing zone and the corridor are generally symmetric about of a vertical lens meridian.
14. 14. - A progressive lens element according to claim 12, wherein the horizontal adjustment varies up to about 2.0 mm depending on the additive power of the user.
15. 15. - A method for designing a progressive ophthalmic lens element, in which the lens element is formed by: a) providing a representation of a progressive lens surface in the form of a base surface function having a viewing area top that provides good optical quality at a predetermined lower surface power over a large area of vision; that predetermined power is determined by the distance prescribing distance (Rx) normally determined by the horizontal adjustment position by the distance between the user's pupils, and the vertical adjustment position is normally determined by the center point of the vertical structure; a lower vision area of higher surface power provides an improved range of vision for intermediate or lower viewing distances; and a corridor of relatively low astigmatism extends intermediate; where the medium surface power and / or surface astigmatism contours within the lower vision zone, the upper vision zone and the corridor are generally symmetric with respect to a vertical lens lens, b) modify the Base surface function of the lens surface based on a selected merit function to maximize the viewing width and minimize the surface astigmatism and c) molding a lens having a lens surface formed in accordance to the modified surface function.
16. 16. - A method according to claim 15 which further includes d) rotating all or part of the representation of the lens surface to achieve a horizontal settlement and the variation of establishment required by the progressive increase of power in the corridor.
17. 17. - A progressive ophthalmic lens element substantially as described above with reference to any of the examples.