ES2350557B1 - PROCEDURE FOR THE DESIGN OF A PROGRESSIVE AND CORRESPONDING OPTICAL LENS. - Google Patents

Abstract

Design procedure of an ophthalmic lens progressive and corresponding lens.

Design procedure of an ophthalmic lens progressive, which comprises an upper zone (7) between the zone of far vision (1) and the upper edge of the lens and an area lower (9) between the near vision zone (3) and the lower edge of the lens, which comprises an optimization stage in which part of a predesigned lens and the aberrations are redistributed sides of the lens around an outside area (15), defined from a frame chosen by the future lens user, so that at least one of the intersections between the upper (7) and lower (9) zones with the outer zone (15), the aberrations adopt higher values than they had in the predesigned lens

Description

Design procedure of an ophthalmic lens progressive and corresponding lens.

Field of the Invention

The invention relates to a method of design of a progressive ophthalmic lens, where the lens comprises a far vision zone, a near vision zone and a corridor which extends between both zones, where between the vision zone far and the upper edge of the lens extends an upper area and between the near vision zone and the lower edge of the lens is extends a lower area. The procedure includes some stages from:

- physiological and prescription data collection of a user,

- selection of a mount,

- frame data collection, including mount perimeter data, and

- optionally taking positioning data of the lens with respect to the user's eye, taking into account the selected mount.

The invention also relates to a lens. progressive ophthalmic finished as indicated and to the corresponding progressive bevel ophthalmic lens.

State of the art

Progressive ophthalmic lenses are known. comprising the aforementioned areas of far vision, near vision and runner. The far vision zone and the near vision zone they have different powers and this causes the present lens optical aberrations that are typically distributed in the lateral areas on both sides of the progression corridor of power, inevitable and inherent in the fact that there are several differentiated optical powers. These optical aberrations, which are undesirable but unavoidable, they may be, in a non-limiting manner, the field curvature, oblique astigmatism, comma, etc. There are various techniques to reduce and distribute these aberrations to along the surface of the lens so that they affect what minimum possible to the user. Additionally, it is possible that the user require astigmatic correction. This astigmatic correction is it can also include in the lens by means of the so-called prescription astigmatism. Logically in the physical lens overlapping prescription astigmatism and optical aberrations cited, but during the procedures of lens design these features are treated in a way differentiated

Thanks to the existing techniques of optimization of optical aberrations, preferably referring to the distribution of aberrations associated with the progression of lens power such as oblique astigmatism, coma and the field curvature among others, greater comfort has been achieved for the wearer of the progressive lenses and, consequently, has managed to popularize these lenses. In this description and claims shall be called lateral aberrations to all those optical aberrations that are a consequence of the progression of progressive lens power, including the oblique astigmatism, comma and field curvature.

It is known to take into account various physiological data as well as the mount chosen by the user in the Progressive lens selection procedure best suited for the user. For example, in certain cases data are taken on the positioning of the lens with respect to the user's eye, taking consider the selected mount. Examples of this can be find in documents ES 2,253,391 and WO 2009/133887 A1.

In documents EP 1.830.222 A1, EP 1.950.601 A1, JP 2004163787 A, and WO 2009/135058 A2 various are described manufacturing procedures for progressive lenses that have in count the mount chosen by the user.

However, there is still a need to find procedures that further improve the treatment of optical aberrations present in the lens, and especially the distribution of lateral aberrations associated with the progression of
power.

In the present description and claims has used the nomenclature of ISO 13666, in which establish the following definitions:

- semi-finished lens (in English: semifinished lens blank): piece of preformed material that only has one finished optical surface,

- finished lens (in English: finished lens): lens whose two sides have the final optical surfaces, this finished lens may be beveled (to adjust its perimeter to a certain mount) or not.

In the present description and claims considers that the expression "finished lens" always refers to The lens without beveling. Bevel lens is used specifically the expression "finished bevel lens".

Summary of the invention

The invention aims to overcome these inconvenience This purpose is achieved through a procedure of the type indicated at the beginning characterized in that it comprises a lens optimization stage comprising the following subcaps:

- calculation of the target power values and prescription astigmatism for the far vision zone, the zone near vision and the corridor, depending on the data physiological and prescription of the user and, optionally, of the positioning data,

- generation or selection of a lens predesigned, where the predesigned lens has certain lateral aberration values, preferably astigmatism associated with the progression of lens power, in areas upper and lower,

- definition of a useful area, defined from of the perimeter of the mount (and preferably consisting of the area included in the perimeter of the mount), and an outside area outside the perimeter of the mount, and location of the useful area in the lens (preferably considering the correct positioning of the lens with respect to the user's eye according to the user morphology), where the perimeter divides the upper zone in an upper outer zone and an inner upper zone and the zone lower in a lower outer zone and a lower zone inside,

- redistribution of at least one of the lateral lens aberrations, preferably astigmatism associated with the power progression of the lens, where during redistribution is distributed the lens aberration chosen around of the outer zone allowing, in at least one of the upper outer and lower outer areas, adopt values superior to those in the pre-designed lens.

In the present description and claims pre-designed lens means a lens that is taken as the point of heading for the optimization stage according to the invention. It is a lens that has been calculated by any method other than of the present invention, preferably without taking into account the mount chosen by the user, and most preferably without having in Count the perimeter of the mount. The predesigned lens may have been calculated beforehand, so that the optician can arrange of a plurality of pre-designed lenses from which you can choose the most appropriate at the time of optimization according to the invention, or it can be a lens that is generated (calculated) in the time to do the optimization according to the invention.

Indeed, usually progressive lenses conventional (and predesigned lenses that are usually used in the design of conventional progressive lenses) have been calculated regardless of the mount that will be used by the Username. This has the consequence that the location is unknown exact of the useful area. Consequently, conventional lenses (and conventional pre-designed lenses) try to keep the upper and lower areas with aberration values lateral, particularly astigmatism associated with progression, the lowest possible since all that part of these areas upper and lower that is finally within the useful area will be an area frequently used by the user and is not known of in advance what size it would be, so you have to extend them until the total diameter of the lens to cover any form of mount possible. Therefore, the existence of lateral aberrations in non-negligible values in these areas would be a source of discomfort for the user if they were finally within the perimeter of the user's mount. However, in the present invention takes into account that while in the upper areas inside and bottom inside the presence of lateral aberrations It is highly inadvisable (and should be reduced to a minimum), in change in the upper outer and lower outer areas can have any value of lateral aberrations (and, in fact, of any aberration) since these zones will be finally eliminated during chamfering, so its optical properties are totally irrelevant. Instead, by redistributing the aberrations lateral (preferably the distribution of associated astigmatism to progression) allowing in the upper outer areas and lower exterior adopt higher values than the lens clip art can be achieved in other parts of the lens, specifically within the useful area, the values of the lateral aberrations are reduced and / or softened, which Improves user comfort.

It is not necessary for the optimization process simultaneously affect both zones (the upper exterior and the lower exterior), since an optimization can be done that affects Only one of them.

In general, optimization can include the treatment of one of the lateral aberrations (preferably the astigmatism associated with the progression of lens power) or of more than one. Therefore, when making reference in this description and claims of the chosen lateral aberration, should understood that it also includes the case in which it was chosen more than one.

Preferably the redistribution of the chosen lateral aberration is done through a process of redistribution in which an objective value of the lateral aberration chosen not null for at least one of the upper outer and lower outer areas, preferably being the target value between 30% and 70% of the maximum value present in the useful area for said lateral aberration, and very preferably between 40% and 60% of the maximum value present in the useful area for said lateral aberration. Indeed, as previously mentioned, the usual procedures try to make lateral aberrations be the lowest possible in the upper and lower areas, so the target values are usually 0. Also, in the procedures conventional upper and lower zones are not divided into mount function (which, when defining a useful area, divides them into upper outer, upper inner, lower outer and lower interior), so there is no differential treatment of These subzones. When a predesigned lens is selected, these 4 zones have zero or very lateral aberration values little ones. When non-null target values are set (or even clearly elevated) to the outside areas (upper exterior and / or exterior exterior) a redistribution of the lateral aberrations around the entire lens, getting a reduction and smoothing of the lateral aberrations present in the useful area, particularly in the temporal and nasal areas.

Advantageously in the optimization process establish initial parameters that include values power target, target values of lateral aberration chosen, values of power tolerances and aberration chosen side and a weight function, where the process of optimization is done through a merit function, where you establish, for the outer zone, aberration tolerances lateral choice greater than aberration tolerances chosen side provided in the useful area. Indeed, at allow greater tolerances in the outside area is allowed to the lateral aberration chosen is redistributed by the outer zone "with freedom". Conceptually, the ideal would be for the tolerance in the outer zone was infinite, but to avoid numerical calculation problems, the infinite value is replaced by a value large enough to achieve the effect wanted.

Preferably set for the area external weight function values lower than for the area useful, preferably normalized values are established less than 0.2, most preferably less than 0.1. Effectively, in this way the weight function does not take into account (or has little in mind) what happens in the outer zone. Ideally, the function of weight has a value of 0 in the outer zone, but again for calculation reasons, it is preferable that the value is not exactly 0, so it is replaced by a value small enough as to achieve the desired effect (whatever happens in the area outside not relevant to the merit function). Preferably the weight function is normalized (takes values between 0 and 1), in which case the values of the weight function in the Outside area are less than 0.2, or even less than 0.1.

Advantageously in the optimization process perform a displacement stage of at least one of the maximum nasal and temporal astigmatism associated with the progression of lens power, present in the pre-designed lens, moving it away from far, near vision and corridor areas. Indeed, both maxima (nasal and temporal) are present in the conventional progressive ophthalmic lenses. As already commented above, predesigned lenses are calculated without take into account any saddle, so it is common that these Maximum remain within the useful area. The present invention proposes move them away from far, near and corridor vision areas, it is say, separate them to the right and left, bringing them closer to the respective nasal and temporal borders. To shift these maximums, preferably it is done by local changes in surfaces spline that describe the astigmatism of objective progression and that They comprise these maximums. Ideally the maximums move up to that reach the edge of the useful area. However, again for calculation reasons, it is advantageous that the maximum is not exactly at the edge of the useful area (to avoid calculation singularities), but it is advantageous that the maximum substantially coincides with the perimeter of the useful area. Substantially it should be understood that is close enough so that closer proximity it no longer means an improvement in the distribution of astigmatism associated with the progression that is appreciable by the user.

It is not essential to simultaneously do the displacement of both maxima, but it is also possible that the procedure includes the displacement of only one of the maximum

Alternatively, the perimeter of the useful area (which is the perimeter of the mount chosen by the user) for some nasal and temporal dimensions of the perimeter of the useful area, and at least one of the maximum until it substantially coincides with its respective dimension nasal or temporary, respectively. Indeed, the use of these dimensions simplifies the calculation and allows to obtain results satisfactory

The maximum displacement affects locally to the distribution of powers and astigmatisms Progression derivatives. Preferably it is forced that these changes do not affect power distributions and astigmatism associated with progression in areas of distant vision, near and in the corridor.

Preferably an ellipse of vision is defined. The vision ellipse is the area of the useful area that is most eye transit and, therefore, is the area most used by the Username. Logically it includes the areas of distant and near vision And the broker. Preferably it is centered on the control point of prism. Preferably their semi-axes are calculated from the user viewing angles and vertex distance. The vertex distance is preferably considered to be between 24 and 32 mm (most preferably between 27 and 29 mm). The vertical angle of view is preferably considered to be between 35º and 45º (most preferably between 38º and 42º), and that the horizontal viewing angle is between 25º and 35º (most preferably between 28º and 32º. A solution particularly advantageous is obtained when the semi-major axis is 23 mm (corresponding to a viewing angle of 40º with respect to the center from the user's eye and considering a vertex distance of 28 mm) and the lower half axis is 16 mm (corresponding to an angle of 30º look with respect to the center of the user's eye and with the same vertex distance of 28 mm). This vision ellipse is used to give the corresponding area a "favor deal" in the sense that worse optical characteristics are required than the far and near vision areas and the corridor, but better than to the rest of the useful area. Preferably this is done by assigning them higher values in the weight function than the rest useful area

A subject of the invention is also a lens progressive ophthalmic finished, where the lens comprises an area of distant vision, a near vision zone and a corridor that extends between the far vision zone and the near vision zone, where between the far vision zone and the upper edge of the lens an upper zone extends and between the near vision zone and the lower edge of the lens extends a lower area, characterized in that it comprises a useful area, defined from the perimeter of a certain preselected mount, and preferably consisting of the area within the perimeter of the mount, and an outside area outside the perimeter of the mount, where the perimeter divides the upper zone into a zone upper outer and upper inner zone and lower zone in a lower outer zone and a lower inner zone, where in at least one of the upper outer and lower outer areas has an astigmatism associated with the power progression of the Lens greater than 0.25 Dp.

Preferably the upper inner areas and Inner lower have an astigmatism associated with the progression of lens power less than 0.12, preferably less than 0.06.

Brief description of the drawings

Other advantages and features of the invention they are appreciated from the following description, in which, without no limitation, preferential modes of embodiment of the invention, mentioning the drawings that are accompany. The figures show:

Figs. 1a and 1b, lens schemes progressive ophthalmic with the various areas mentioned in the present description and claims.

Fig. 2 a diagram of an ophthalmic lens progressive with the perimeter of the mount and the vision ellipse.

Figs. 3a, 3b and 3c, schematic views of astigmatism distribution maps associated with progression, as examples of lateral aberrations, in which the astigmatism shift associated with the progression of agreement with the process of the invention.

Figs. 4a and 4b, some distribution maps of weight functions according to the invention.

Figs. 5a and 5b, the distribution map of astigmatism associated with the progression of an ophthalmic lens progressive before and after applying the procedure optimization according to the invention.

Detailed description of some embodiments of the invention

In the present description and claims they have cited various parts of a progressive ophthalmic lens finished In Figs. 1a and 1b are shown schematically each of them. Fig. 1a shows the far vision zones 1, near vision 3 and corridor or hall 5, which are the zones Conventional lenses of the state of the art progressive lenses. Above the far vision zone 1 extends the zone upper 7, and below the near vision zone 3 extends the lower zone 9. In Fig. 1b the perimeter 11 of a mount which, once properly positioned on the lens, defines a useful zone 13 and an outer zone 15, which is the area that will be removed during the bevelling stage. The part of the upper zone 7 comprised in useful zone 13 is the upper zone interior 17, while the part of the upper zone 7 comprised in the outer zone 15 is the upper outer zone 19. Similarly they can define the lower inner zone 21 and the lower zone outside 23. Additionally, in Fig. 1b they are shown, with a stroke dashed, the lines that determine the highest maximum, lower, nasal and temporal, that is the upper 25, lower 27, nasal 29 and temporal 31 of the useful area 13.

Another example of lens is shown in Fig. 2 ophthalmic with the useful area 13 defined by the mount, in which it has also included the ellipse of vision 33. In general the form of the useful area 13 is coincident with the surface delimited by the perimeter 11 of the mount, but that does not have to be that way. The useful area 13 may have other geometries that, even if they come defined by the perimeter 11 of the mount are not exactly matching. Thus, for example, it can be defined as useful area 13 the one delimited by the rectangle formed by the upper dimensions 25, inferior 27, nasal 29 and temporal 31. Or it can be defined as zone useful some other simple geometric shape that approximates the area of the perimeter 11 (inscribed rectangles, inscribed ellipses, etc.). These Simple geometries may be of interest in various cases, such as for example to simplify and accelerate optimization calculations or to perform the optimization in those cases in which it is not It has the complete data of the perimeter of the mount.

As previously mentioned, the basic objective of the invention is to take advantage of the area that will remain outside the mount (i.e. the outer zone 15) once the Lens has been beveled. This way you can get lenses with less lateral aberrations (and, in particular, with less astigmatism associated with progression), because it makes them more comfortable for users regardless of the type of design of Progressive chosen, which will not vary in important areas for vision (far vision zone 1, near vision zone 3 and runner 5). In the examples of Figs. 3a, 3b, 3c, 5a and 5b se show some cases in which the lateral aberration chosen is the astigmatism associated with progression. However, the results and Conclusions are generalizable to any other lateral aberration. Figure 3a shows the astigmatism associated with the progression of A standard design On the finished lens the perimeter 11 of the mount chosen by the user, represented schematically using a rectangle. You can see that there are large areas with a null or almost null astigmatism that finally They will be removed during the chamfering operation. Since in the At the time of designing the progressive lens, it is not known the frame that finally choose the user and since the areas above the far vision zone 1 and below near vision zone 3 they can be very important optimally (since, if they remain within the perimeter 11 of the mount will be areas of frequent use by the user), conventional lens design techniques progressive tends to maintain the upper zone 7 and the lower zone 9 with the least possible astigmatism and, in general, with the smallest possible aberrations However the reality is that a part important of these upper 7 and lower 9 zones will be eliminated during chamfering, specifically the upper outer areas 19 e lower outside 23. Consequently, conventional techniques of progressive lens design are conditioned by the fact try to optimize the optical properties of areas that later they will be eliminated. The procedure of the present invention provides the improvement of distinguishing between useful area 13 and the outer zone 15. Thus, in the present example, during the The method according to the invention redistributes the astigmatisms associated with progression as shown in the figure 3b. In other words, the upper outer zone 19 is "invaded" and the lower outer zone 23 with astigmatism which results in a reduction of maximum astigmatism values present in the useful area 13. Since finally only useful area will remain 13 the overall result is a beveled lens with lower aberrations astigmatic derived from the progression. This is shown in the figure 3c.

The methodology used is as follows:

- First, they are determined from the physiological data of the user and the frame chosen by the user, a set of distances and values that preferably they already include the correct positioning of the lens with respect to the eye taking into account the morphology of the user and the mount.

- The dimensions are determined below upper 25, lower 27, nasal 29 and temporal 31 of useful area 13 together with the conventional data, such as positions of the areas of near vision 3, far vision 1, and the corridor 5. The value and position of the ellipse of vision 33, centered on prism control point 35.

- Target values of prescription power and astigmatism for the vision zone faraway 1, near vision zone 3 and corridor 5 based on the previous data.

- A pre-designed lens is generated or selected make it a good starting point for the process of optimization

- With all the above information are determined the initial values for the optimization process. Specifically astigmatism values associated with progression are determined and of target power as well as tolerance values of astigmatism associated with progression and potency. Preferably astigmatism associated with the allowed progression (as a value objective) in the upper outer 19 and lower outer 23 it is between 40% and 60% of the astigmatism associated with the maximum progression present in the useful area 13. As regards to astigmatism tolerances associated with progression, preferably a tolerance that is between 80% and a 120% higher than the maximum allowable tolerance in the useful area 13. Additionally, in areas that have 0 diopters (Dp) as the value astigmatism target associated with progression are assigned preferably a tolerance of 0.06 Dp. It also determines the weight function, preferably taking into account the ellipse of vision 33. Preferably also the stage of displacement of the nasal and temporal maxima of astigmatism associated with progression This is preferably done by introduction of changes in surface control points spline that define the surroundings of the maxima, so that generate local changes that displace these maximums but not affect the optical properties of the lens in its sections central, in particular in areas of near vision 3, of vision faraway 1 and in corridor 5.

- Then redistribution is performed of astigmatism associated with progression, as mentioned previously.

Once the surface to be machined has been determined through the optimization process, the machining of the same (usually the concave surface of the lens) to get thus the progressive ophthalmic lens finished. Finally you can bevel the lens to get the final product and be able to be mounted on the mount.

A distribution map is shown in Fig. 4a of weights according to the invention. According to a solution preferred of the invention, the weight function has been normalized, of so that their values range from 0 to 1. They can be recognized approximately the various areas of the lens, such as the areas of near vision 3, far vision 1, corridor 5, perimeter 11 of the mount and the vision ellipse 33. In this specific example, the part of the outer zone 15 that remains within the vision ellipse 33 has a greater weight than the remaining parts of the outer zone 15. While, as discussed above, this part of the vision ellipse 33 will be finally eliminated, however, the fact of giving it a greater weight than the rest of the outer zone 15 allows, in certain cases, get better results in the area useful 13 (and / or faster processing). It is also observed that the intersection of the useful area 13 with the vision ellipse 33 It has a greater weight than the remaining parts of the useful area 13. Finally you can also see how the vision zones near 3 and far vision 1 and runner 5 are assigned the Greater weight. In Fig. 4b another distribution map of weights in which the perimeter 11 defines only the area of the lens whose weight is less than 0.2.

In Figs. 5a and 5b show an example comparison between an astigmatism distribution map in a conventional lens, on which the perimeter 11 has been superimposed of the mount chosen by the user (Fig. 5a) and a map of astigmatism distribution of a lens according to the invention (Fig. 5b). In this specific case during optimization astigmatism has been redistributed only around the area lower exterior 23. Comparing both maps it can be seen that the useful area 13 designed according to the invention has about astigmatism values associated with minor progression and a smoother distribution of them.

Claims (11)

1. Procedure for designing a lens progressive ophthalmic, where said lens comprises a vision zone far away (1), a near vision zone (3) and a corridor (5) that extends between said far vision zone (1) and said zone of near vision (3), where between said far vision zone (1) and the upper edge of said lens extends an upper area (7) and between said near vision zone (3) and the lower edge of said Lens extends a lower area (9), which comprises stages from: - physiological and prescription data collection of a user, - selection of a mount, - data collection of said mount, including perimeter data (11) of said mount, - optionally taking positioning data of the lens with respect to the user's eye, taking into account the selected mount, characterized in that it comprises an optimization stage of said lens comprising the following sub-stages: - calculation of the target power values and prescription astigmatism for said far vision zone (1), said near vision zone (3) and said corridor (5), depending on said physiological and prescription data of the user and, optionally, of said positioning data, - generation or selection of a lens predesigned, where said predesigned lens has certain lateral aberration values, preferably astigmatism associated with the progression of lens power, in these areas upper (7) and lower (9), - definition of a useful area (13), defined from the perimeter (11) of said mount, and preferably consisting of the area within the perimeter (11) of said mount, and an outer zone (15) outside the perimeter ( 11) of said frame, and location of said useful zone (13) in said lens, where said perimeter (11) divides said upper zone (7) into an upper outer zone (19) and an inner upper zone (17) and said lower zone (9) in a lower outer zone (23) and a lower inner zone
(twenty-one), - redistribution of at least one of the lateral aberrations of the lens, preferably said astigmatism associated with the progression of potency, where during said redistribution is distributed said lateral aberration of the lens around said outer zone (15) allowing, at minus one of said upper outer (19) and lower outer zones (23), adopt values higher than what you had on that lens predesigned Method according to claim 1, characterized in that said redistribution of at least one of the lateral aberrations is carried out by means of a redistribution process in which an objective value of said non-zero lateral aberration is defined for at least one of said zones upper outer (19) and lower outer (23), preferably said lateral aberration being astigmatism associated with the power progression of the lens, and preferably the objective value of said lateral aberration being between 30% and 70% of the value maximum of said lateral aberration present in said useful zone (13), and very preferably between 40% and 60% of the maximum value of said lateral aberration present in said useful zone
(13). 3. Method according to one of claims 1 or 2, characterized in that said optimization process establishes initial parameters comprising objective power values, objective values of said lateral aberration, values of power tolerances and said aberration lateral and a weight function, where said optimization process is carried out by means of a merit function, where, for said outer zone (15), tolerances of said lateral aberration are established greater than the tolerances of said lateral aberration provided in said zone useful (13). 4. Method according to claim 3, characterized in that for said outer zone (15) values of the weight function are established lower than for said useful zone (13), preferably standardized values of less than 0.2 are established, most preferably under 0.1. 5. Method according to any of claims 1 to 4, characterized in that in said optimization process a displacement stage of at least one of the nasal and temporal astigmatism maxima associated with the progression present in said pre-designed lens is carried away from said said areas of distant vision (1), near (3) and of said corridor (5). Method according to claim 5, characterized in that at least one of said maximums is displaced until it substantially coincides with said perimeter (11). 7. Method according to claim 5, characterized in that nasal (29) and temporal (31) dimensions are determined, and at least one of said maximums is displaced until it substantially coincides with its respective nasal (29) or temporal (31) dimension. ), respectively. Method according to any one of claims 1 to 7, characterized in that a vision ellipse (33) is defined. 9. Method of manufacturing a bevelled progressive ophthalmic lens characterized in that it comprises a design stage according to any one of claims 1 to 8, a machining stage of at least one of the concave and convex surfaces according to the results of said stage of design, and a beveling stage of said lens according to said perimeter (11). 10. Finished progressive ophthalmic lens, wherein said lens comprises a far vision zone (1), a near vision zone (3) and a corridor (5) that extends between said far vision zone (1) and said zone of near vision (3), where between said far vision zone (1) and the upper edge of said lens an upper zone (7) extends and between said near vision zone (3) and the lower edge of said lens extends a lower zone (9), characterized in that it comprises a useful zone (13), defined from the perimeter (11) of a certain preselected mount, and preferably consisting of the area comprised within the perimeter (11) of said mount, and a outer zone (15) outside the perimeter (11) of said mount, wherein said perimeter (11) divides said upper zone (7) into an upper outer zone (19) and an inner upper zone (17) and said lower zone (9 ) in a lower outer zone (23) and a lower inner zone (21), where in at least one of said upper outer (19) and lower outer (23) zones has an astigmatism associated with the progression of lens power greater than 0.25 Dp. 11. A lens according to claim 10, characterized in that said upper inner (17) and lower inner (21) areas have an astigmatism associated with the power progression of the lens less than 0.12, and most preferably less than 0.06.