WO2018142405A1

WO2018142405A1 - Ophthalmic lens and method of designing such lens

Info

Publication number: WO2018142405A1
Application number: PCT/IL2018/050116
Authority: WO
Inventors: Avishai DAGAN; Alexander SHUR
Original assignee: Shamir Optical Industry Ltd
Current assignee: Shamir Optical Industry Ltd
Priority date: 2017-02-02
Filing date: 2018-02-01
Publication date: 2018-08-09
Anticipated expiration: 2019-08-02

Abstract

An ophthalmic single vision lens is presented, which is configured in accordance with original prescription parameters for vision correction of a patient. The lens has an aspheric modified surface such that as worn orientation of the lens corresponding to a relatively small physical pantoscopic tilt Ti provides visual quality corresponding to a substantially spherical lens surface having an optical power of the original prescription and orientation with simulated pantoscopic tilt T2 significantly higher than the physical pantoscopic tilt Ti, while maintaining the original prescription parameters within the aspheric modified surface.

Description

OPHTHALMIC LENS AND METHOD OF DESIGNING SUCH LENS

TECHNOLOGICAL FIELD AND BACKGROUND

The present invention relates to ophthalmic lenses for eyeglasses or spectacles, in particular single vision lenses, and method of designing such lenses.

Single vision lenses have one, consistent focal power, i.e. the same power of correction across its whole surface, to correct a single vision condition. In the process of manufacturing corrective lenses for eyeglasses or spectacles used to correct defects in a person's vision, various factors may be used to form the final lenses. Integration of the lens into the selected frame and how the frame sits or rests on a person's face in relation to the person's eye(s) also needs to be taken into account. Accordingly, various measurements may need to be taken to ensure that the lenses, once manufactured and mounted to the spectacle frames, are positioned so that the corrective properties of the lenses are optimized.

The ophthalmic measurements may include one or more of the following: frame relating parameter(s), a back vertex distance (BVD) measurement, a seg height measurement (optional for single vision lenses, relevant for progressive or multifocal lenses), and a pupillary distance measurement. The frame relating parameter(s), or so-called wear parameter(s), may include one or more of following: frame pantoscopic tilt, frame panoramic tilt, frame BVD, frame width, frame height, bridge width or distance between lenses (DBL) when mounted in the frame.

The need to measure frame relating parameters is associated with the fact that the frames are not straight up and down, instead the eyeglasses are positioned at an angle or tilt relative to the eyes. Most of the time, all eyewear must sit on a patient with a certain angle towards the face from the lower rim. This lower rim tilt towards the cheeks presents a pantoscopic tilt (frame alignment in the up and down position of the frame). The pantoscopic tilt is typically of 9-10 degrees.

Techniques for adjusting standard ophthalmic prescription in manufacturing eyeglass ophthalmic lenses for correcting vision of a patient have been developed. For example, US Patent Publication No. 2015/077704, assigned to the assignee of the present application, describes a method for adjusting an original prescription to be used in manufacturing an ophthalmic lens for correcting vision of a patient. According to this method, an original prescription is obtained being based on an eye vision measurement performed by virtue of a real optical system, and supplementary input data associated with the eye vision measurement is obtained; at least such original prescription data and the supplementary input data are used for calculating a simulated optical system simulating the real optical system; and then at least the original prescription data and the simulated optical system are used to reflect the effect of the supplementary input data on the eye vision measurement, for calculating an adjusted prescription.

GENERAL DESCRIPTION

As noted above, a single vision ophthalmic lens has one, consistent focal power (patient's prescribed power of correction) across its entire surface, to correct for a single vision condition. Such single vision lenses are typically spherical lenses, i.e. have a substantially symmetrical distribution of optical properties (power and distortions map) with respect to at least a horizontal central plane of the lens. It has been observed that single vision lenses, when fitted to frames with a substantial pantoscopic tilt (about 9 degrees), provide a better solution for visual comfort / performance. Thus, according to conventional approach, the optical properties of a symmetrical single vision lens are considered for the condition that the lens is fitted at a 9 degree pantoscopic tilt. Reference is made to Fig. 1 illustrating the general meaning of the term "pantoscopic tilt" and the other terms/parameters involved. The pantoscopic tilt is understood to mean an angle in a vertical plane formed by the visual axis of an eye in a primary viewing position (line of sight) and by the normal to the plane tangential to the rear face of the lens at the intersection of the primary viewing direction with the lens.

Generally, the pantoscopic tilt is commonly defined as either (i) the angle of a line connecting the upper and lower rim above and below the fitting position/point with gravity, or (ii) the angle of the vertical tangent at the fitting point of the front surface of the lens with gravity. The term fitting position or fitting point refers to a point on a lens as mounted in a spectacle frame, being the point of intersection of a user's line of sight with the lens surface when the user is looking straight ahead. In the conventional "single vision" lens' design, the fitting point practically coincides with the far vision zone (i.e. a geometric location / region on the free of distortion lens' surface typically used by a wearer when observing, far objects).

The term "primary position" is understood as the mean position of the eye relative to the head, when looking straight ahead at an object situated at eye level. The terms "vertex distance ", "back vertex distance ", or "BVD " refer to a distance between the back surface of the lens when in the final orientation (corresponding to the wear parameter, i.e. pantoscopic tilt) and the corneal apex (front surface of the eye). It should be noted that, for high myopes, the BVD is determined as a distance from the center of rotation (COR) of the eye to the back vertex sphere of the lens, when the patient is gazing at a far object (and not from the corneal apex). It should be noted that the term "pantoscopic tilt" is commonly used to describe the vertical angle of the lenses as they sit of the patient's face, while the term "panoramic tilt" is used to describe the horizontal, or 'wrap' angle of the frame, i.e. the degree of the lens tilt around the vertical axis. As indicated above, it is a conventional approach that the optical properties of a single vision lens fitted at about 9 degree pantoscopic tilt should be used as the target for designing a single vision lens. However, the inventors have found that although most Myopic individuals prefer the typical pantoscopic tilt due to the improved visual experience / optical performance of the lens, certain facial structures limit the tilts possible to introduce with a frame.

In this connection, reference is made to Figs. 2A and 2B, exemplifying an effect of the pantoscopic tilt for spectacles with ophthalmic lenses worn by individuals having Asian-type and Caucasian-type facial structures. It is evident that the facial features in the facial structure of Fig. 2A can accommodate only a low pantoscopic tilt geometrically due to the flat nature of the facial features. Additionally, it has been found that the Asian population performs a significant number of reading tasks, and that the reading posture of Asians vs. North Americans differs. On average, Asians hold reading material higher and closer to the eye than Europeans or North Americans, requiring consideration when designing a lens for a population with Myopia and high myopia.

The present invention provides a novel ophthalmic lens configuration for individuals whose face constitution and predisposition to Myopia require a special approach for a lens design. Such individuals have facial structure requiring a so- called "substantially flat" design of the spectacles' frame, enabling the actual relatively small pantoscopic tilt, not exceeding 5 degrees (e.g. about 4-5 degrees or even (almost) zero pantoscopic tilt), as well as substantially zero panoramic tilt.

It should be understood that the actual pantoscopic tilt is a physical pantoscopic tilt of the lens in its so-called "as worn" orientation, i.e. corresponding to the lens position when mounted in the spectacles frame and worn by the patient. The ophthalmic lens of the invention is configured for a relatively small physical pantoscopic tilt in its as worn orientation. For the purposes of the present application, the expression "relatively small physical pantoscopic tilt" refers to a physical pantoscopic tilt not exceeding 6 degrees, i.e. from 6 degrees to almost zero or zero physical pantoscopic tilt. In the description below, the terms "zero pantoscopic tilt", "almost zero pantoscopic tilt", and "relatively small pantoscopic tilt" are used interchangeably having the same meaning of physical pantoscopic tilt not exceeding 6 degrees. The invention provides a novel ophthalmic single vision lens, which is designed in accordance with original prescription parameters (at least patient's prescribed optical power, e.g. for far vision correction), and has an aspheric modified surface such that the lens, when positioned/oriented at a relatively small physical pantoscopic tilt Ti (almost zero tilt) provides visual quality corresponding to a substantially spherical lens surface orientation with simulated significantly higher pantoscopic tilt T2 while maintaining said original prescription parameters.

The term "physical pantoscopic tilt" should be distinguished from the term "simulated pantoscopic tilt": As described above, the physical pantoscopic tilt is a commonly used feature describing / relating to the as worn orientation of the lens, and according to the present invention such physical pantoscopic tilt is relatively small, up to zero tilt. The simulated pantoscopic tilt is a lens' feature introduced by the present invention, and is higher (about 9-12 degrees) than the physical pantoscopic tilt (almost zero, or generally not exceeding 6 degrees). The simulated pantoscopic tilt actually defines the target lens map or so-called optical 'eye point' data (i.e. optical power and distortion distributions/profiles) as experienced by the patient wearing the lens), which is to be provided by the modified lens surface intended to be used / oriented with the physical pantoscopic tilt. To this end, the modified lens surface is characterized by the predetermined curvature profile(s) of the lens' front and/or rear surface(s) and possibly also predetermined lens' thickness profile providing the desired modified optical properties over the lens surface. More specifically, the curvature profile is defined by varying radius of the lens' surface curvature over one or more portions of the lens (aspherical lens) such that the peripheral distortions are measured up to 0.25 diopters, and a minor optical power addition is induced in the surface. The optical properties of a lens surface are defined by the local curvature of the lens front and back surfaces. Moreover, a lens may also be defined by "as worn" optical characteristics, taking into consideration the situation of the person wearing the lenses. Reference can be made to EP0927377, EP0990939, and WO2010/100528 defining a lens with "as worn" optical characteristics, may be calculated from a ray-tracing program, for a given lens. Further, as known, it is possible to define a wearer optical power and astigmatism, in each viewing direction. Possible definitions of the optical power and the astigmatism of the lens, in the wearing conditions, can be calculated as explained in the article by B. Bourdoncle et al., entitled "Ray tracing through progressive ophthalmic lenses", 1990. Wearing conditions, the optical power and the astigmatism may be calculated so that the prescription is fulfilled for a wearer wearing his spectacles in the wearing conditions.

Thus, the ophthalmic single vision lens of the invention is designed in accordance with original prescription data (set of parameters) and has a modified lens surface providing modified lens target map (optical target data, as explained above), such that the intended orientation of the modified lens surface (when mounted in a spectacles frame) with substantially zero physical pantoscopic and/or panoramic tilts, provides vision of a simulated pantoscopic tilt of up to 9-10 degrees. It should be understood that the modification of the lens' surface is aimed at, while enabling its mounting/orienting with the almost-zero physical tilt (flat frame), providing optical power and distortion profiles substantially matching (highly correlated with) the original prescription (i.e. required vision correction), and the optical power addition and aberration (distortion) profiles substantially matching (highly correlated with) those for a spherical lens mounted at a physical pantoscopic tilt of up to 9 - 12 degrees (providing a simulated pantoscopic tilt of 9 - 12 degrees).

In this connection, it should be noted that, when describing the single vision lens, the terms far vision zone and near vision zone may be used to refer to geometric locations / regions on the free of distortion lens' surface typically used by a wearer when observing, respectively, far and near located objects; and the term intermediate zone refers to a free of distortion surface region of the lens between the far and near vision geometrical locations. The size of each of such zones is typically described as a horizontal width of an optical area (surface area of the lens) of the respective zone free of distortions/aberrations.

Considering the above features of the lens, the ophthalmic single lens (far vision correction) of the invention has a modified surface configured with predetermined optical power and distortion profiles experienced by the patient wearing the lens, such that, when the lens is oriented with a relatively small (almost-zero) physical pantoscopic tilt, it maintains the prescribed optical power within a far vision zone of the lens and provides good intermediate and near vision properties, while said optical power and distortion profiles correspond to relatively high simulated pantoscopic tilt. More specifically, the lens' surface defines distortion-free far, intermediate and near vision zones surrounded by peripheral distortions, where the geometry (curvature profile(s) as described above) of the lens' surface is configured with a certain predetermined asymmetry in the horizontal meridian of the lens, i.e. the upper lens map data differs from the lower lens map data (power and distortion distributions). This asymmetry provides that the distortion-free intermediate and near vision zones are wider and the distortion- free far vision zone is narrower, as compared to the conventional (symmetric, spherical) single vision lens with the same prescribed optical power. The lens with the so-modified surface, when mounted in a substantially flat frame (generally, oriented with relatively small, e.g. almost-zero, physical pantoscopic tilt), provides the prescribed optical power within the distortion-free far vision zone and maintains good intermediate and near vision properties in the distortion-free intermediate and near vision zones.

Thus, according to one broad aspect of the invention, there is provided an ophthalmic single vision lens configured in accordance with original prescription parameters for vision correction of a patient, wherein said lens has an aspheric modified surface such that as worn orientation of the lens corresponding to an almost-zero physical pantoscopic tilt Ti provides visual quality corresponding to a substantially spherical lens surface orientation with simulated pantoscopic tilt T₂ of about 9-10 degrees, while maintaining said original prescription parameters.

The aspheric modified surface configuration defines lens map data of the visual quality corresponding to the substantially spherical lens surface orientation with the simulated pantoscopic tilt T₂ and the original prescription parameters.

The aspheric modified surface configuration is characterized by a predetermined curvature profile of the lens surface such that the lens map data when analyzed with a physical relatively small pantoscopic tilt (e.g. of zero or almost-zero degrees) correlates to the target lens map data of an 'eye-point' analysis of a spherical lens fitted with a relatively large physical pantoscopic tilt (e.g. of 9 degrees). The lens map data defines distortion-free far, intermediate and vision zones surrounded by peripheral distortions, such that the distortion-free intermediate and near vision zones are wider and the distortion-free far vision zone is narrower as compared to a single vision spherical lens having an optical power parameter similar to that of the original prescription.

According to another broad aspect of the invention, there is provided an ophthalmic single vision lens configured in accordance with original prescription parameters for vision correction of a patient, wherein said lens has an aspheric modified surface such that as worn orientation of the lens corresponding to a relatively small physical pantoscopic tilt Ti provides visual quality corresponding to a substantially spherical lens surface having an optical power of said original prescription and orientation with simulated pantoscopic tilt T2 significantly higher than said physical pantoscopic tilt Ti, while maintaining said original prescription parameters.

According to yet further aspect of the invention, it provides an ophthalmic single vision lens, wherein said lens is configured in accordance with original prescription parameters for a patient including patient's prescribed vision correction parameters and patient's prescribed as worn orientation of the lens with almost-zero pantoscopic and panoramic tilts, said lens having an aspheric modified surface satisfying the prescribed as worn orientation of the lens and the prescribed vision correction parameters, while providing visual quality corresponding to a substantially spherical lens surface orientation with simulated pantoscopic tilt of about 9-10 degrees.

The invention, in its yet further aspect provides spectacles having a frame configured with an almost-zero panoramic tilt, and patient's prescribed single vision ophthalmic lenses mounted in said frame to provide an as worn orientation of each lens with an almost-zero pantoscopic tilt, wherein each of said lenses is configured in accordance with the patient's original prescription parameters for vision correction, and has an aspheric modified surface such that the as worn orientation of the lens with the almost-zero physical pantoscopic tilt provides visual quality corresponding to a substantially spherical lens surface having optical power parameter similar to that of the original prescription and orientation with simulated pantoscopic tilt of about 9-10 degrees, while maintaining said original prescription parameters within said aspheric modified surface.

The invention also provides a method for use in designing a single vision ophthalmic lens for a patient according to patient's original prescription data. The method comprises: providing input data comprising: said original prescription data, and pantoscopic tilt data, said pantoscopic tilt data comprising data indicative of a desired relatively small physical pantoscopic tilt value (e.g. almost-zero physical pantoscopic tilt) for the lens orientation in an as worn position and a desired relatively high simulated pantoscopic tilt value (typically, up to 9-10 degrees simulated pantoscopic tilt) for simulated visual quality of the lens when in said as worn orientation; analyzing acceptable tolerances for at least some parameters of the original prescription and generating a corresponding lens map data comprising optical power and distortion distribution meeting requirements for the original prescription data (this lens map data is used as the target data for the lens design optimization); analyzing said lens map data and said pantoscopic tilt data, and determining data indicative of a modified aspheric lens surface configuration such that said modified aspheric lens surface defines a modified lens map data providing visual quality of the lens while in the as worn positon with said physical pantoscopic tilt simulating that of a substantially spherical lens surface orientation with said simulated pantoscopic tilt, while maintaining said original prescription parameters within said modified aspheric lens surface.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic illustration of the meaning of a pantoscopic tilt;

Figs. 2 A and 2B demonstrate an effect of the pantoscopic tilt for spectacles with ophthalmic lenses worn by individuals having Asian-type and Caucasian-type facial structure;

Fig. 3 is a flow diagram of a method of the invention for designing a single vision lens to be used (worn) with a physical zero (or relatively small) pantoscopic tilt while operating with a simulated relatively large (e.g. about 9 degrees) pantoscopic tilt;

Figs. 4A-4D and 5A-5E show the results of simulations conducted by the inventors to compare the lens map features for lenses designed using the conventional approach for as worn condition of the physical pantoscopic tilt of 9 degrees and lenses having similar optical power but designed according to the principles of the invention; and

Fig. 6 is a block diagram of a lens designing system of the invention for carrying the method of the present invention. DETAILED DESCRIPTION OF EMBODIMENTS

As described above, the present invention provides a novel design / configuration of a single vision lens (having prescribed optical properties) by providing a modified aspherical optical surface of the lens such that, when this surface is positioned at a physical, relatively small (almost zero) pantoscopic tilt Ti it provides the same visual quality and optical properties as if it was a spherical surface at simulated relatively higher pantoscopic tilt T2.

The meaning of the physical pantoscopic tilt (e.g. of about 9 degrees) of the lens position commonly used in spectacles is illustrated in Fig. 1. As described above, the pantoscopic tilt is commonly defined as the angle of a line connecting the upper and lower rim above and below the fitting position with gravity, or the angle of the vertical tangent at the fitting point of the front surface of the lens with gravity.

As illustrated in Figs. 2A and 2B, such commonly used pantoscopic tilt is practically impossible for individuals differing in face constitutions and predisposition to Myopia. These are typically individuals having Asian-type facial structure, requiring a substantially zero panoramic tilt of the spectacles' frame. In the description below, such frame orientation/position is referred to as "flat" or "substantially flat". Considering that the commonly used (physical) pantoscopic tilt is about 9-

10 degrees (or even up to 12 degrees), the lens of the present invention is configured for use (orientation) with the physical pantoscopic tilt not exceeding 5 degrees. In some embodiments, the lens design of the present invention is targeted to the actual physical pantoscopic tilt Ti being zero or close to zero, referred to herein at times as almost-zero tilt, while simulating by its viewing properties the pantoscopic tilt T2 of about 9-10 degrees. Generally, the lens design of the present invention provides that the physical pantoscopic tilt Ti is much smaller than the simulated pantoscopic tilt T2, Ti < T2I, e.g. T2 is about 9-12 degrees, while Ti does not exceed 6 degrees. Thus, in some embodiments, the technique of the invention is aimed at designing a single vision lens of a prescribed optical power (generally, original prescription data) for use with a substantially flat frame (pantoscopic tilt is zero or almost zero). The lens design, i.e. configuration of the lens surface defining the lens optical characteristics (at times referred to as "lens map data"), is such as to simulate the vision with a pantoscopic tilt of about 9 degrees.

The inventors have also checked the principles of the invention for designing such lens for variable B VDs as function of the original prescription. In this connection, the following should be noted: The BVD (distance between the back surface of the lens when in the final orientation (corresponding to the wear parameters, e.g. pantoscopic tilt) and the front surface (apex) of the cornea) is dependent on the frame and how it sits on face (oriented/aligned with respect to the user's face). When the frame is chosen, it affects the actual optical power through the lens. The BVD is commonly measured by the Eye Care Practitioner (ECP) and supplied with the prescription. If the lens while in frame becomes positioned too far from the eyes, the lens effective power for myopes will be reduced. Hence, adjustment of BVD is more critical if the prescribed optical power is relatively high (more than ±4 diopter). Such adjustments are even more critical for aspheric lenses. For the purposes of lens optimization, the distance between the center of rotation (COR) or the eye to the back surface of the lens is necessary. For high myopes, the distance to the eye-center of rotation can be larger, since the probability of the eye being longer in high myopia is greater. In this case, the axial length of the eye can be taken as a function the Eye prescription. The definition of BVD, including the axial lens, i.e. measured from the center of rotation (COR) of the eye to the back vertex sphere of the lens when the patient is gazing at a far object, can account for this relationship. In other words, for the purposes of lens optimization with respect to BVD in case of high myopes, the COR is the reference point.

In the case of stock lenses, or pre-molded lenses per prescription, an average BVD is assumed for the target optimized lens, e.g. 27 mm. In this case, the average BVD for Myopes with a relatively high prescription will increase proportionally with the prescription power. In other words, the axial length of the eye component of the BVD is taken as a function of the prescription power. In another embodiment, the proposed lens can be optimized accounting for a BVD per lens prescription according to a predetermined function of the extent of Myopia.

Reference is made to Fig. 3 showing a flow diagram 10 of the main steps in a method according to the invention for designing the lens configuration for use with a desired physical pantoscopic tilt Ti which would simulate the "preferred" simulated pantoscopic tilt T2 significantly higher than the desired physical pantoscopic tilt Ti. The lens design is aimed at obtaining a modified lens surface, which on the one hand, meets the requirement of original prescription within predetermined acceptable tolerances, and on the other hand, simulates the optical properties of the surface (gives feeling to wearer) of a spherical lens positioned/orientated with simulated pantoscopic tilt T2 while being actually oriented with a desired physical pantoscopic tilt Ti, where Ti«T2. The parameters describing the lens surface modification mainly include curvature profile(s) of the lens' surface(s) and possibly also thickness profile of the lens.

Thus, initially, input data indicative of the original prescription data OP for single vision ophthalmic lens for correcting vision of a specific patient is provided (step 12). The original prescription data is typically provided by an eyeglass prescriber (e.g., optometrist, ophthalmologist) and specifies the values of all parameters the prescriber has deemed necessary to construct and/or dispense ophthalmic lenses appropriate for a specific patient. The parameters which can be included in the original prescription data for single vision correction for each eye of the patient may include at least two or more of the following: far vision sphere power, far vision cylinder power, far vision cylinder axis, far vision prism power and direction, far vision base, and pupillary distance, BVD, Fitting Height.

Typically, the above parameters of the original prescription OP of a single vision ophthalmic lens correspond to the lens position/orientation with no pantoscopic tilt, TOP=0. In some cases, the original prescription data can take into account the lens position with commonly used physical pantoscopic tilt TOP, or the measured pantoscopic tilt, typical being TOP=9-10 degrees.

Thus, data indicative of the physical pantoscopic tilt TOP defined by the original prescription data is determined/identified (step 14). This physical pantoscopic tilt TOP is either zero or almost zero or is the commonly used pantoscopic tilt, TOP= 9-10 degrees.

Practically, the original prescription data OP defines / allows certain tolerance for each of one or more parameters of the original prescription. Such tolerance data for n parameters (n>l), TDi, . . . TDN, may be supplied as part of (identified from) the original prescription data OP, or may be determined (step 16) by analyzing the parameters of the original prescription OP using any known suitable analysis scheme.

Independently, data indicative of the desired physical pantoscopic tilt Ti for which the lens is to be designed while simulating the wearer's feeling of simulated pantoscopic tilt T2 (where typically T2»Ti) is provided (step 18). In the preferred embodiment, the desired physical pantoscopic tilt is "almost-zero" tilt.

The input data, including the original prescription parameters OP (and possibly the pantoscopic tilt TOP if other than zero tilt TOP is included in the original prescription data) and respective tolerance data TD, is analyzed to determine lens map data LMP (step 20). Generally speaking, the lens map data LMP is indicative of acceptable optical power distribution and distortion distribution within the lens surface based on the prescribed optical power to be maintained within the lens and the acceptable size and geometry for the distortion-free surface of the lens to provide desired visual properties of the lens. More specifically, such lens map data LMP is indicative of acceptable configuration for the arrangement of distortion- free far, near and intermediate vision zones. The acceptable configuration defines, for each of these zones, limits (ranges) for size and geometry of the lens surface region to be occupied by the respective zone, and for geometric location of the zone within the lens surface with respect to orientation of the corresponding viewing axis (line of sight). The lens map data LMP may be created based on the input data, or determined as optimization of the previously provided reference data, using the original prescription data OP and the tolerance data TD.

The lens map data LMP and the pantoscopic tilt data indicative of the physical (e.g. almost-zero) and preferred simulated (e.g. about 9 degrees) pantoscopic tilts Ti and T2, then undergo processing and analyzing stage (step 22) to determine output data indicative of modified aspheric lens surface MLS data (step 24). The modified aspheric lens surface MLS data includes the curvature profile(s) of the lens surface(s) and possibly also the lens' thickness profile, and may optionally include data indicative of a corresponding modified lens map data LMPmod. In this connection, it should be understood that the curvature profiles of the lens' front and rear surfaces might be different.

This disclosure contemplates that the shape of the lens, such as, for example, the shape of the rear surface and/or front surface of the lens can be determined from the original prescription data received from an eye care professional. The original prescription data can include optical powers (e.g., spherical and cylinder power) that provide distance or intermediate distance vision correction. The original prescription data can further include additional power that may be needed for near vision, mono far pupillary distance (PD), fitting height (FH) (measured from the center of the pupil to the lower rim of the frame), frame width, frame height, and DBL (Distance Between Lens), trace data or any combination thereof. The prescription data can also include a prism correction, if needed.

The shape of the rear surface and/or front surface of the lens can be determined using a computer implemented method, which includes determining a size and/or shape and/or location of the lens features, e.g. the location used for far vision. The computer implemented method may be configured to optimize the sizes and/or shape of the various regions of the lens (e.g., central, peripheral), such that the resulting lens provides the prescribed prescription power with reduced aberrations. The computer implemented method may be configured to determine defined properties such that the resulting lens is an aspherical single vision lens having the properties discussed herein. The computer implemented method uses an initial surface, a target optical property surface incorporating the desired features of the lens, and a weighting surface. An optimization may be performed, using a cost function, in order to obtain the closest physical result possible to the defined target optical properties. For example, the computer implemented method can use an optical analysis of a spherical lens worn with a pantoscopic tilt of 9 degrees as the target optical properties surface.

The determined shape of the lens can be used to shape, for example, a mold to be used for molding multiple lenses, or the rear or front surface of a lens blank using freeform manufacturing technology. Accordingly, the lens design that provides the prescribed spherical, cylindrical and prism powers for lenses can be obtained using software methods and reproduced on one or more surfaces of a lens blank with available freeform manufacturing equipment.

The inventors have shown that the resulting modified lens map data LMPmodfor the modified aspheric lens' surface, which is designed for the physical almost-zero pantoscopic tilt Ti of the lens, is in good correlation with the lens map data corresponding to pantoscopic tilt T2 of about 9 degrees. Hence, the wearer of the "flat" frame spectacles with substantially zero pantoscopic tilt of the lens will have feeling of 9 degrees pantoscopic tilt.

In this connection, reference is made to Figs. 4A-4D and Figs. 5A-5E, showing the results of simulations performed by the inventors.

Figs. 4A-4D show various features of the lens map data LMD for conventional single vision spherical lenses designed for the main optical powers of -6 Sph Diop. Here, Figs. 4A-4B show, respectively, the cylindrical distortion distribution and the optical power distribution within the -6 Sph conventional lens prior to be mounted in the spectacles frame, i.e. zero pantoscopic and panoramic tilts condition; and Figs. 4C and 4D show the cylindrical distortion and the optical power distributions for the same lens for the commonly used "as worn" condition of 9 degrees pantoscopic tilt.

As shown in these figures for the conventional spherical lens design, the 9 degrees pantoscopic tilt results in somewhat more distorted far vision zone (i.e. smaller/narrower distortion-free region in the far vision zone) but wider distortion- free near and intermediate zones. It appears that the user experiences better comfort due to the wider clean intermediate and near vision zones which compensate for the narrowing of the far vision zone. Therefore, about 9 degree pantoscopic tilt is the preferred one and widely used.

Figs. 5A-5D illustrate corresponding features of the single vision aspheric lens designed according to the invention for the prescribed optical powers of -6 Sph Diop; and Fig. 5E shows the cylindrical and optical power addition profiles resulting from the curvature of the modified surface of this lens. Figs. 5A-5B show the lens map data, i.e. cylindrical distortion distribution (Fig. 5 A) and optical power distribution (Fig. 5B), for the -6 Sph aspheric lens in its simulated "as worn" condition corresponding to the zero physical pantoscopic and panoramic tilts. As shown, the lens map data corresponds to a good overall performance of the lens. Figs. 5C-5D show the modified lens map data formed by the distortion distribution (Fig. 5C) and optical power distribution (Fig. 5D) for the same optical power lens but with the modified surface corresponding to the simulated 9 degrees pantoscopic tilt. As shown, the so-modified lens map data is in good correlation with that of Figs. 4C-4D. As shown in Fig. 5E, the modified lens' surface of the lens of the present invention has curvature profile (i.e. varying radius of the lens' surface) such that the peripheral regions of the lens have distortions measured up to 0.25 diopters and minor optical power addition.

Fig. 6 shows a block diagram of a system 100 of the invention for carrying out the above described method for designing the lens of the present invention. The system 100 includes a control unit 102 which is configured for data communication (e.g. wireless communication using any known suitable communication techniques) with a lens data provider system 104. The lens data provider system 104 may be constituted by an external storage device where at least a part of the previously measured lens data (original prescription data OP) is stored and/or by a measurement device. The control unit 102 is typically a computer device having such main utilities as data input and output utilities 106 and 108, memory, and a data processor and analyzer utility 110.

The control unit 102 receives input data indicative of the original prescription data (parameters) OP for a specific single vision ophthalmic lens to be designed with the modified lens surface corresponding to the "as worn" condition of zero or relatively small physical pantoscopic tilt Ti while simulating "user feeling" of relatively large pantoscopic tilt T2. The input data may also include the tolerance data TD for at least some parameters of the original prescription data OP; and/or the data processor and analyzer utility 110 may include the tolerance data analyzer module 110A which determines such tolerance data TD for the given lens prescribed data. The data processor and analyzer utility 110 includes a lens map analyzer module 110B which is configured and operable to analyze the original prescription data OP and the tolerance data TD and generate the corresponding lens map data LMP. Further provided in the data processor and analyzer utility 110 is a lens map modifier module HOC which is configured and operable to analyze the corresponding lens map data LMP and the pantoscopic tilt data indicative of the desired physical and simulated pantoscopic tilts Ti and T2, and determine the optimal modified lens map data LMPmod. The optimal modified lens map data LMPmod meets the requirements of the viewing optical quality corresponding to the prescribed optical power and the simulated pantoscopic tilt T2. To this end, the lens map modifier module HOC utilizes one or more models (stored in the memory) describing a relation between lens map data and lens' surfaces parameters (curvature and/or thickness) and applies iterative algorithms to the received lens map data LMP, by varying the lens' surfaces parameters, to determine the optimally acceptable modified lens map data LMPmod. Then, the control unit generates output data of the corresponding modified surface' parameters (curvature and thickness profiles).

Claims

CLAIMS:

1. An ophthalmic single vision lens configured in accordance with original prescription parameters for vision correction of a patient, wherein said lens has an aspheric modified surface such that as worn orientation of the lens corresponding to a relatively small physical pantoscopic tilt Ti provides visual quality corresponding to a substantially spherical lens surface having an optical power of said original prescription and orientation with simulated pantoscopic tilt T2 significantly higher than said physical pantoscopic tilt Ti, while maintaining said original prescription parameters within said aspheric modified surface.

2. The ophthalmic lens according to Claim 1, wherein said physical pantoscopic tilt does not exceed 6 degrees, and the simulated pantoscopic tilt is up to 12 degrees.

3. The ophthalmic lens according to claim 1 or 2, wherein the relatively small physical pantoscopic tilt Ti is an almost-zero tilt, and the simulated significantly higher pantoscopic tilt T2 is of about 9-10 degrees.

4. The ophthalmic lens according to any one of the preceding claims, wherein said aspheric modified surface configuration defines lens map data of the visual quality corresponding to said substantially spherical lens surface orientation with the simulated pantoscopic tilt T2 and said original prescription parameters.

5. The ophthalmic lens according to claims 3 or 4, wherein the aspheric modified surface configuration is characterized by a predetermined curvature profile of the lens surface such that a peripheral region of the lens surface have distortions measured up to 0.25 diopters and relatively small optical power addition.

6. The ophthalmic lens according to any one of the preceding claims, wherein the modified lens surface is optimized for a back vertex distance (BVD) selected in accordance with the original prescription parameters and a predetermined function of an extent of Myopia.

7. The ophthalmic lens according to any one of claims 4 to 6, wherein the lens map data defines asymmetric distortion distribution within the lens.

8. The ophthalmic lens according to any one of claims 4 to 7, wherein the lens map data defines distortion-free far, intermediate and vision zones surrounded by peripheral distortions, such that the distortion-free intermediate and near vision zones are wider and the distortion-free far vision zone is narrower as compared to a single vision spherical lens having an optical power parameter similar to that of the original prescription.

9. An ophthalmic single vision lens, wherein said lens is configured in accordance with original prescription parameters for a patient including patient's prescribed vision correction parameters and patient's prescribed as worn orientation of the lens with almost-zero pantoscopic and panoramic tilts, said lens having an aspheric modified surface satisfying the prescribed as worn orientation of the lens and the prescribed vision correction parameters, while providing visual quality corresponding to a substantially spherical lens surface orientation with simulated pantoscopic tilt T2 of about 9-12 degrees.

10. A spectacles having a frame configured with a relatively small physical pantoscopic tilt 7i, and patient's prescribed single vision ophthalmic lenses mounted in said frame to provide an as worn orientation of each lens with said physical pantoscopic tilt 7i, wherein each of said lenses is configured according to any one of the preceding claims.

11. A method for use in designing a single vision ophthalmic lens for a patient according to patient's original prescription data, the method comprising: providing input data comprising: said original prescription data, and pantoscopic tilt data, said pantoscopic tilt data comprising data indicative of a desired relatively small physical pantoscopic tilt value for the lens orientation in an as worn position and a desired relatively high simulated pantoscopic tilt value for simulated visual quality of the lens when in said as worn orientation; analyzing acceptable tolerances for at least some parameters of the original prescription and generating a corresponding lens map data comprising optical power and distortion distribution meeting requirements for the original prescription data; analyzing said lens map data and said pantoscopic tilt data, and determining data indicative of a modified aspheric lens surface configuration such that said modified aspheric lens surface defines a lens map data providing visual quality of the lens while in the as worn positon with said physical pantoscopic tilt corresponding to a substantially spherical lens surface orientation with said simulated pantoscopic tilt, while maintaining said original prescription parameters within said modified aspheric lens surface.

12. The method according to Claim 11, wherein said physical pantoscopic tilt is almost zero, and said simulated pantoscopic tilt is up to 9-12 degrees.

13. The method according to claim 11, wherein said physical pantoscopic tilt does not exceed 6 degrees, and said simulated pantoscopic tilt is up to 12 degrees.