HK1205564B - Multifocal contact lenses and related methods and uses to improve vision of presbyopic subjects - Google Patents

Description

Multifocal contact lenses for improving vision of presbyopic subjects, and related methods and uses

The present application claims the benefit of prior U.S. provisional patent application No. 61/594,859 filed on 3/2/2012, in accordance with 35u.s.c. § 119(e), which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates to multifocal contact lenses and methods of making and using multifocal contact lenses, as well as batches and sets of multifocal contact lenses.

Background

Contact lenses have been described as useful for correcting presbyopia. Some methods and devices for treating presbyopia or improving vision in presbyopic subjects have been described in, for example, EP0201231a1, EP2183639a1, GB2086605A, US5220359, US5715031, US5754270, US5771088, US5835192, US6322213, US6520638, US6540353, US7517084, US7625086, US7753521, US20090051870a1, US20100321632a1, US2011310347a1, WO0008516 and WO 0135880.

As one example, in a monocular vision correction system, a presbyopic person wears one contact lens designed only to correct distance vision in one eye (e.g., the lens has a single marking of spherical power to correct distance vision) and a second contact lens designed only to correct near vision in the other eye (e.g., the lens has a single marking of spherical power to correct near vision). Monocular vision correction appears to provide better results for presbyopic subjects (e.g., low Add patients) who require low Add power correction. Higher-addition individuals tend to experience more visual discomfort or visual impairment, such as blurred images, etc., when utilizing the monocular vision system.

As another example, multifocal contact lenses having aspheric optics to provide a relatively smooth transition of optical power across the lens or multifocal contact lenses having different optic zones that alternate between distance and near optical powers are also described as being useful for correcting presbyopia. Examples of contact lenses for correcting presbyopia include: ACUVUE OASYS for presbyopia (Weikan corporation (Vistakon), Jackson Wille, FL, USA; a lens pair consisting of two center-distance lenses); PUREVISION MULTIPIFOCAL (Bausch & Lomb, Rochester, NY, USA, NY); lens pair consisting of two center-near (center-near) anterior surface aspheric lenses); AIR OPTIX AQUA MULTIFOCAL (Ciba Vision), Dulus, Georgia, U.S.A. (Duluth, GA, USA); lens pair consisting of two center near aspheric lenses); and FREQUENCY 55multifocal, pro clear multifocal and bifinizymatic lenses (each from cropao optics, pleisenton, CA, USA); lens pair consisting of a central distance lens and a central near lens).

Although multifocal contact lenses provide vision improvement for many presbyopic subjects, multifocal contact lenses can produce secondary or "ghost" images, as perceived by the individual. This ghosting may be due to a defined region and/or narrow transition between the distance and near optical powers of the multifocal contact lenses. Providing both clear distance visual acuity and clear near visual acuity for an individual remains a challenge, let alone reducing or avoiding visual discomfort or visual impairment, such as ghosting, loss of contrast, etc., while achieving this goal. This challenge is especially true for individuals who require intermediate or high add powers in contact lenses, such as individuals who require add power correction greater than +1.00 diopters.

To address this challenge and to meet the needs of ophthalmologists (ECPs) and presbyopic persons, contact lens manufacturers currently offer a variety of lens options for ECPs to select from and to prescribe. While ECP and the relatively large number of choices available to an individual or patient appear to be beneficial, the large number of choices can reduce the efficiency of ECP by requiring more time to find a desired lens combination for a particular individual from the large number of choices. It is also undesirable for contact lens manufacturers or distributors, or both, to provide a large number of lens combinations to an ECP, as increasing the number of lens designs and combinations for different spherical powers and add powers results in an increase in inventory that must be made and stored to provide to the ECP or individual.

Based on the ever increasing population of presbyopic subjects, there remains a need in the art for new multifocal contact lenses that provide effective vision correction for presbyopic subjects.

Disclosure of Invention

The present invention satisfies the need for multifocal contact lenses that provide the desired levels of distance and near visual acuity without significantly compromising distance visual acuity and without unduly introducing additional visual impairment, particularly for presbyopic subjects requiring add power in excess of +1.00 diopters (e.g., moderate and high add presbyopic subjects). As used herein, a presbyopic subject is understood to be a person with presbyopia, and the phrase "presbyopic subject" is used interchangeably with presbyopic subject (presbyope). If the presbyopic subject is a patient of an ophthalmologist (ECP), the presbyopic subject may be referred to herein as a presbyopic subject. At the same time, the present invention meets the following needs: simplifying the process of fitting the ECP to multifocal contact lenses and simplifying the process of manufacturing multifocal contact lenses by contact lens manufacturers.

The present invention is based on the following findings: as discussed herein, multifocal contact lenses that utilize aspheric power profiles in the optic zone within a certain range or within certain parameters can provide better binocular visual acuity than that obtained with existing multifocal contact lenses without introducing additional visual impairments, such as ghosting, loss of contrast, etc., even though the monocular visual acuity for any eye (e.g., only one eye) at near and distance viewing distances is less than the binocular visual acuity at near and distance viewing distances.

As discussed herein, with the present lenses and the present methods, a presbyopic subject (e.g., a moderate or high addition presbyopic subject) is optimally or best corrected monocular for distance vision of the individual's dominant eye, monocular overcorrection for distance vision of the individual's non-dominant eye, and binocular under-correction for add power (i.e., under-corrected add power in both lenses). As one non-limiting example (provided for illustrative purposes only), a myopic presbyope may require a prescription of-3.00 diopters (D) to correct distance vision for each eye (i.e., the non-dominant and dominant eyes), and may require an add power of +1.75D to correct the lack of accommodation associated with presbyopia. According to the present invention, a multifocal contact lens having a distance vision refractive power of-3.00D and an add power of less than +1.75D (e.g., a lens having an add power value of +0.75D to + 1.50D) as described herein will be prescribed for the dominant eye of a presbyopic subject, and a lens having a distance vision refractive power positive of greater than-3.00D (e.g., a lens labeled as a lens having a distance vision refractive power value of-2.75D to-1.75D) and an add power of less than +1.75D (e.g., a lens labeled as an add power value of +0.75D to + 1.50D) will be prescribed for the non-dominant eye thereof. For example, the add power of the lens may be +0.75D, +1.00D, +1.25D, or + 1.50D. As yet another example, lenses having add powers of about +1.75D or +2.00D may be prescribed for higher add presbyopes requiring add powers greater than + 2.00D. As used herein, distance vision refractive power refers to the power of a contact lens effective to correct the distance vision of a presbyopic subject; the phrase distance vision power may be used interchangeably with the term distance power, as used in the art. Also, as used herein, the words "a" or "an" mean one or more, and are synonymous with "at least one. Plural refers to two or more, and is synonymous with "multiple". The term including as used herein is an open-ended term that is intended to have the same meaning as including.

With the present multifocal contact lenses, methods and uses, presbyopic subjects can utilize visual treatment of the brain to compensate for reduced monocular visual acuity and provide perceptually superior binocular visual acuity compared to the monocular visual acuity provided by either lens alone. As described herein, this may be achieved by: aspheric multifocal contact lenses are provided to the dominant eye of the presbyopic subject and similar aspheric multifocal contact lenses are provided to the non-dominant eye of the presbyopic subject, but the distance vision refractive power of the lens for the non-dominant eye is more positive than the distance vision refractive power of the presbyopic subject required to provide visual acuity of 20/30 or 20/20 or better. For example, by providing one of the multifocal contact lenses described herein to the non-dominant eye of a presbyopic subject, whose distance vision refractive power is +0.25 diopters to +1.25 diopters more positive than the distance vision requirement of the presbyopic subject, the presbyopic subject's binocular visual acuity improves as compared to its monocular visual acuity due to the binocular summation. That is, monocular refractive blur caused by the overcorrected lens on the non-dominant eye hardly affects binocular visual acuity, and the image quality of the distance image perceived by the presbyopic subject (as determined by the combined image from the lenses in the dominant and non-dominant eyes) is better than the individual image from either eye. The degraded image of the non-dominant eye resulting from the far vision overcorrection of the non-dominant eye may actually increase and improve the contrast of the image from the dominant eye.

As described in more detail herein, the present multifocal contact lenses each have an aspheric power profile in the optic zone in an attempt to reduce or minimize the power variation across the optic zone and particularly the central 5mm diameter portion of the optic zone, and still provide acceptable distance and near vision visual acuity for both eyes. The aspheric power profile is designed to provide an effective add power while also providing a less steep rate of change to maintain adequate near vision correction across the central portion of the optic zone and reduce vision impairments such as ghosting, flare, etc. The improved clinical outcome observed with the present multifocal contact lenses and methods and uses is monocular balance contrast loss and overcorrection (i.e., in only one eye), but binocular under-correction of the add power (i.e., in both eyes of the individual). This combination helps to reduce binocular contrast loss. As can be appreciated from the present specification, a new system and method for improving vision of presbyopic subjects or presbyopes is described and provides simplicity to contact lens manufacturers by reducing inventory requirements, ease to ECP by reducing the number of effective choices available for ECP selection and fitting to presbyopic subjects, and thereby reducing chair time (chair time) for presbyopic successful vision improvement and providing sufficient binocular far and near visual acuity without introducing additional visual impairment. These improvements relate to the shape of the aspheric power profile, reduced variability of the power profile within the lens for different distance vision refractive powers, an effective amount of monocular overcorrection for the distance vision refractive power of the non-dominant eye, and an effective amount of binocular undercorrection for the add power of the presbyopic subject.

In one aspect, the present invention relates to multifocal contact lenses (e.g., two or more multifocal contact lenses). Further, in this aspect, the invention relates to methods of using multifocal contact lenses, such as methods of supplying multifocal contact lenses to an ophthalmologist (ECP), methods of supplying multifocal contact lenses to a presbyopic subject, methods of fitting a presbyopic subject with multifocal contact lenses, and methods of improving vision or visual acuity of a presbyopic subject with multifocal contact lenses of the invention. In this regard, multifocal contact lenses and methods can be understood as referring to ECPs, contact lens manufacturers, contact lens distributors, contact lens retailers, or presbyopic subjects, or a combination thereof.

According to the above aspect, the multifocal contact lenses include a first multifocal contact lens for the dominant eye of the presbyopic subject and a second multifocal contact lens for the non-dominant eye of the presbyopic subject. Each of the first multifocal contact lens and the second multifocal contact lens includes an optic zone. The optical zone is surrounded by a peripheral zone. The optical zone has an optical zone center and an optical zone perimeter spaced radially away from the optical zone center and defining a boundary between the optical zone and the peripheral zone. The optic zone has an aspheric power profile extending from the optic zone center to the optic zone perimeter and providing a near vision refractive power and a distance vision refractive power or distance power as used in the art such that each of the multifocal contact lenses has an add power. The add power is the absolute difference in power between the near vision power and the distance vision power (thus, as used herein, the add power is always positive). According to this aspect of the invention, the first multifocal contact lens has a distance vision refractive power effective to provide 20/30 (Snellen notation) or better high contrast visual acuity to the dominant eye of the presbyopic subject at a viewing distance of at least 6 meters. In terms of diopter (D), the distance vision refractive power may be from +20.00D to-20.00D, and the appropriate distance vision refractive power is selected to provide the desired distance vision acuity to the presbyopic subject. The second multifocal contact lens has a near vision refractive power effective to provide high contrast visual acuity of 20/30 (snellen notation) or better to the presbyopic subject's non-dominant eye at a viewing distance of about 60 centimeters or less. The second multifocal contact lens also has a distance vision refractive power that is offset by about +0.25 diopters to about +1.25 diopters relative to the distance power correction for the non-dominant eye of the presbyopic subject. According to this aspect and the present teachings, binocular visual acuity provided to a presbyopic subject by first and second multifocal contact lenses worn simultaneously is greater than monocular visual acuity provided to the presbyopic subject by either the first multifocal contact lens or the second multifocal contact lens alone.

Other features of the above aspects will be apparent from the following detailed description, drawings, examples, and claims.

In a second aspect, the present invention relates to a batch or batches of multifocal contact lenses and methods of manufacturing a batch or batches of multifocal contact lenses. In this regard, the batch or batches of multifocal contact lenses and the present methods can be understood to relate to the perspective of the contact lens manufacturer.

According to this second aspect, a batch of multifocal contact lenses for improving vision of presbyopic subjects is provided. The batch comprises, consists essentially of, or consists of a plurality of multifocal contact lenses (e.g., two or more) that can be provided in a package. Each of the multifocal contact lenses includes an optic zone and a peripheral zone, as described above. The optical zone has an optical zone center and an optical zone perimeter spaced radially away from the optical zone center and defining a boundary between the optical zone and the peripheral zone. The optic zone has an aspheric power profile extending from the optic zone center to the optic zone perimeter and providing a near vision refractive power and a distance vision refractive power such that each of the multifocal contact lenses has an add power, wherein the add power is the absolute difference in power between the near vision refractive power and the distance vision refractive power, as described herein. The plurality of multifocal contact lenses includes a plurality of first multifocal contact lens groups. Each first multifocal contact lens group includes multifocal contact lenses that provide a unique single distance vision refractive power for the first multifocal contact lens group (e.g., one group has a distance vision refractive power of-2.00D, and a second group has a distance vision refractive power of-3.00D, etc.). The aspheric power profile of each of the multifocal contact lenses within a single contact lens group provides a single add power selected from a value of about 0.75 diopters to 2.00 diopters over a radial distance of 2.5mm from the optic zone center of each lens in the series. For example, the single add power of each multifocal contact lens of a single contact lens group can be 0.75D, 1.00D, 1.25D, 1.50D, 1.75D, or 2.00D, as measured along a radius of 2.5mm from the center of the optic zone. The add power provided by the aspheric power profile of the individual multifocal contact lenses of any first multifocal contact lens group varies by no more than ± 0.25D from the add power provided by the relative aspheric power profiles of the plurality of multifocal contact lenses. As used herein, the relative aspheric power profile is an average of the power profiles of a plurality of multifocal contact lenses, and wherein the distance vision refractive power at a radial distance of 2.5mm is fixed at 0.00 diopters. Therefore, the aspheric power profile is normalized so that the power of the lens at a radial distance of 2.5mm is 0.00D. The add power of individual multifocal contact lenses in the group may vary from the relative aspheric power profile by plus or minus (±) 0.25D. Thus, if the add power of the relative aspheric power profile is 1.10D, the add power of the individual multifocal contact lenses may be 0.85D to 1.35D. The aspheric power profiles of the individual multifocal contact lenses of any first multifocal contact lens group also have similar shapes. In particular, along the power profile, the aspheric power profile differs by no more than ± 0.375D from a relative aspheric power profile of the plurality of multifocal contact lenses for each radial distance measured along the power profile. Thus, along a 2.5mm radial distance, the individual power profile varies by no more than 0.375D in either direction (positive or negative). In a method of manufacturing one or more batches of multifocal contact lenses, the method includes the step of forming a plurality of multifocal contact lenses from a polymerizable composition (e.g., a lens formulation). The contact lens can be a lathed contact lens, wherein the aspheric refractive power profile is lathed directly on the polymer; a contact lens can be static cast molded, wherein an aspheric power profile is machined on a metal insert used to form a contact lens mold; or may be a spin cast contact lens in which the aspheric power profile is machined on a metal insert used to shape a single mold surface on which the polymeric composition may be placed for curing.

Other features of the second aspect will be apparent from the following detailed description, drawings, examples and claims.

In a third aspect, the present invention relates to one or more sets of multifocal contact lenses for improving vision of presbyopic subjects. As one example, one set of this aspect may be understood as a fitting set of the present multifocal contact lenses. As further described herein, a set of multifocal contact lenses includes a dominant eye series and a non-dominant eye series (e.g., multifocal contact lenses for placement on a dominant eye or a non-dominant eye, respectively, of an individual). The dominant eye series and the non-dominant eye series may be presented as two different series of lenses, each having its own distance refractive power. Alternatively, the dominant eye series and the non-dominant eye series may be presented as a single set of lenses, with the ECP selecting a first multifocal contact lens from the set for placement on the dominant eye of the individual and the ECP selecting a second multifocal contact lens from the set for placement on the non-dominant eye of the individual. According to this third aspect, methods of providing multifocal contact lenses are also disclosed. In this regard, one or more sets of multifocal contact lenses and the present methods can be understood as referring to the point of view of a contact lens manufacturer, ECP, contact lens distributor, or contact lens retailer.

According to this third aspect, a set of multifocal contact lenses for improving vision of presbyopic subjects is provided. As described herein, a set comprises, consists essentially of, or consists of (i) a dominant eye series of multifocal contact lenses and (ii) a non-dominant eye series of multifocal contact lenses. Each multifocal contact lens in each series includes an optic zone having an optic zone center and an optic zone perimeter. The optical zone perimeter is radially spaced away from the optical zone center and defines a boundary between the optical zone and the peripheral zone. The optic zone has an aspheric power profile extending from the optic zone center to the optic zone perimeter and providing a near vision refractive power and a distance vision refractive power such that each of the multifocal contact lenses has an add power. As described herein, the add power is the absolute difference in power between the near vision power and the distance vision power. The dominant eye series includes a plurality of dominant eye patient lens sets (e.g., two or more patient lens sets that can be labeled as available for medium add and high add individuals, low add and medium add individuals, low add and high add individuals, or low add individuals, medium add individuals, and high add individuals) that are associated with the add power needs of the presbyopic subject or patient. The plurality of patient lens sets includes a first dominant eye patient lens set including a multifocal contact lens group. The group includes multifocal contact lenses that provide a unique distance vision refractive power, as described herein. Each group includes at least one multifocal contact lens (i.e., one or more multifocal contact lenses). The aspheric power profile of each multifocal contact lens of the dominant eye patient lens set provides a single add power selected from a value of about 0.75 diopters to 2.00 diopters over a radial distance of 2.5mm from the optic zone center of each lens of the series. The add power provided by the aspheric power profile of the individual multifocal contact lenses of the first dominant eye patient lens set varies by no more than ± 0.25 diopters from the add power provided by the relative aspheric power profile of the multifocal contact lenses of the first dominant eye patient lens set. As described herein, the relative aspheric power profile is an average of the power profiles of the plurality of multifocal contact lenses of the first dominant eye patient lens set and wherein the distance vision refractive power at a radial distance is fixed at 0.00 diopters.

The one or more non-dominant eye series further includes a plurality of patient lens sets associated with add power requirements of presbyopic subjects or patients. The plurality of patient lens sets includes a first non-dominant eye patient lens set including multifocal contact lenses, wherein the aspheric power profile of each of the multifocal contact lenses of the first non-dominant eye patient lens set provides a single add power selected from a value of about 0.75 diopters to 2.00 diopters within a radial distance of 2.5mm from the optic zone center of each lens of the first non-dominant eye patient lens set so long as the distance vision provided by the aspheric power profile of the multifocal contact lenses of the first non-dominant eye patient lens set is offset by about +0.25 diopters to about +1.25 diopters relative to the distance power correction to the presbyopic subject.

The method of this third aspect includes the step of manufacturing a plurality of multifocal contact lenses having an aspheric power profile in the optic zone as described herein. The manufactured multifocal contact lenses are packaged in contact lens packages. The packaged multifocal contact lenses as described herein are provided to a contact lens distributor, a contact lens retailer, or an ECP, or a combination thereof. The packaged multifocal contact lenses so provided include a dominant eye series and a non-dominant eye series, as described above.

Other features of the third aspect will be apparent from the following detailed description, drawings, examples and claims.

In a fourth aspect, the present invention provides methods of using the present multifocal contact lenses. For example, methods of prescribing multifocal contact lenses to presbyopic subjects are described. In this regard, the method can be understood as a point of view relating to ECPs or other individuals or entities prescribing contact lenses to humans.

According to this fourth aspect, the method of prescribing multifocal contact lenses to a presbyopic subject comprises the step of fitting a presbyopic subject with a pair of multifocal contact lenses. So adapted presbyopic subjects require an add power correction of at least 1.25D (e.g., 1.25D to 3.00D). The first multifocal contact lens of the pair includes a first aspheric power profile derived from a first nominal aspheric power profile. The second multifocal contact lens of the pair includes a second aspheric power profile derived from the first nominal aspheric power profile, but the second aspheric power profile provides or has a distance vision refractive power that is offset by about +0.25D to about +1.25D relative to the distance power correction for the presbyope non-dominant eye. For such a fitting, the monocular distance visual acuity for each eye wearing each contact lens is different, and the binocular summation is maintained when the first and second contact lenses are worn simultaneously. The method may optionally include fitting a second multifocal contact lens pair, wherein the aspheric power profile of the first multifocal contact lens in the second pair is the same as the first aspheric power profile of the first multifocal contact lens, and the aspheric power profile of the second contact lens in the second pair provides an area under the curve (AUC) that is between 5% and 45% greater than the AUC of the aspheric power profile of the first multifocal contact lens in the second pair. The method may further comprise the step of performing an eye examination to determine an ocular dominance. The method may further include the steps of determining a prescription for a presbyopic subject and prescribing the presbyopic subject with the first and second multifocal contact lenses.

Other features of the fourth aspect will be apparent from the following detailed description, drawings, examples and claims.

Other aspects and embodiments of the lenses, batches, sets, methods and uses of the invention will be apparent from the following description, drawings, examples and claims. As can be understood from the above and the following description, each feature described herein and each combination of two or more features described herein is included within the scope of the present invention provided that the features included in such a combination are not mutually inconsistent. In addition, any feature or combination of features may specifically exclude any embodiment of the invention.

Drawings

Figures 1A-1F illustrate multifocal contact lenses of the invention. Fig. 1A is an illustration of a first multifocal contact lens. Fig. 1B is an illustration of a second multifocal contact lens. Figure 1C illustrates the aspheric power profile of the contact lens of figure 1A from the center of the optic zone of the lens (0mm) to about the periphery of the optic zone (a radial distance of about 4.1 mm). Figure 1D illustrates the aspheric power profile of the contact lens of figure 1B from the center of the optic zone of the lens (0mm) to about the periphery of the optic zone (a radial distance of about 4.1 mm). Figure 1E is an enlarged view of figure 1C illustrating the aspheric power profile at a radial distance of 2.5 mm. Figure 1F is an enlarged view of figure 1D illustrating the aspheric power profile at a radial distance of 2.5 mm.

Figure 2A illustrates the aspheric power profile of lens a of the present invention and the aspheric power profile of lens B as a comparison. The shaded portion depicts the area under the curve (AUC) of the aspheric power profile of lens a.

Figure 2B illustrates the aspheric power profile of lens a of the present invention and the aspheric power profile of lens B as a comparison. The shaded portion depicts the area under the curve (AUC) of the aspheric power profile of lens B.

Fig. 3 is a graph illustrating logMAR values as a measure of visual acuity for a subject with moderate addition of light under high illumination and high contrast conditions for lens a and lens B of fig. 2A and 2B.

Fig. 4 is a graph illustrating logMAR values as a measure of visual acuity for individuals with moderate addition of light under low light and low contrast conditions for lenses a and B of fig. 2A and 2B.

Fig. 5 is a graph illustrating logMAR values as a measure of visual acuity for a highly dosed individual under high illumination and high contrast conditions for lenses a and B of fig. 2A and 2B.

Fig. 6 is a graph illustrating logMAR values as a measure of visual acuity for a highly sighted individual under low light and low contrast conditions for lenses a and B of fig. 2A and 2B.

FIG. 7 is a table of different acuity scales, as understood by those of skill in the art.

Fig. 8 is an illustration of a set of present multifocal contact lenses.

Fig. 9 is an illustration of a manufacturing process that may be used to manufacture the multifocal contact lenses of the present invention, batches thereof, groups thereof, and groups thereof.

Fig. 10A-10D illustrate one batch of multifocal contact lenses of the invention. Fig. 10A illustrates a batch including multiple multifocal contact lens groups, each group corresponding to a unique distance refractive power. Figure 10B illustrates aspheric power profiles of three multifocal contact lenses of the invention. The shaded areas depict the amount of variability in power distribution along the radial distance that an individual lens may have, and are still understood to be within the teachings of the present invention. Figure 10C illustrates the add power of the three lenses of figure 10B. The add power may vary +/-0.25 diopters (D). Figure 10D illustrates aspheric power profiles of three multifocal contact lenses of the invention, each having a unique distance vision refractive power (i.e., -1.50D, -3.00D, and-4.00D).

Fig. 11A illustrates a second group of multifocal contact lenses that can be used with the batch illustrated in fig. 10A. Figure 11B illustrates an aspheric power profile of the second group of multifocal contact lenses of figure 11A (lens C) having an AUC greater than lens a and less than lens B.

Figure 12 is a graphical illustration of the rate of change of power over a radial distance of 2.5mm for lens a, lens B and lens C of figure 11B.

Fig. 13 is an illustration of a set of multifocal contact lenses similar to that of fig. 8.

Detailed Description

As described herein, the present invention is based on the following findings: multifocal contact lenses comprising an optic zone having an aspheric power profile to provide add power correction can be used and can be made to provide a presbyopic subject with a desired degree of distance visual acuity and a desired degree of near visual acuity without unduly impairing or adversely affecting distance visual acuity and without unduly introducing additional visual impairment, particularly for presbyopic subjects requiring add power correction in excess of +1.00 diopters (D), such as moderate and high add presbyopic subjects. For the present multifocal contact lenses and the present methods, a presbyopic subject (e.g., a moderate addition or high addition presbyopic subject) is optimally or best monocular corrected for distance vision in the individual's dominant eye, and monocular overcorrection is performed for distance vision in the individual's non-dominant eye, and binocular under-correction is performed for the add power relative to the add power correction required by the presbyopic subject (e.g., no overcorrection is performed for the non-dominant eye). According to the present teachings, the present multifocal contact lenses improve near vision without unduly disturbing distance vision and without unduly introducing additional ghosting compared to existing bifocal and multifocal contact lens products. With the present multifocal contact lenses, balancing distance vision and near vision between the two eyes can improve multifocal vision in presbyopic subjects. Unlike monocular vision systems that produce a loss of cortical sum, the present multifocal contact lenses maintain binocular cortical sum. Binocular cortical summation or binocular summation as used herein refers to an increase in binocular response compared to monocular response when sensitivity of the dominant eye is equal to sensitivity of the non-dominant eye, as described in the following documents: pardhan et al, Optometry and Vision Science (1990), Vol.67, No. 9, p.688-; and palland et al, ophthalmology journal (ophthal. physiol. opt.), (1990), Vol.10, month 1, 33-36, The effect of monocular defocus on binocular contrast sensitivity (The effect of monocular de-focus on binocular contrast sensitivity). Unlike prior bifocal and multifocal systems, which tend to cause more visual impairment (e.g., ghosting, loss of contrast, etc.), the present multifocal contact lenses not only provide clear distance visual acuity and clear near visual acuity for moderate and high degree add presbyopic subjects, but do so without introducing additional visual impairment.

Multifocal contact lenses are described herein. The multifocal contact lenses of the invention can be used to improve or correct vision in presbyopic subjects. As understood by those skilled in the art, presbyopic subjects have a dominant eye and a non-dominant eye. Ocular dominance can be determined by the ophthalmologist (ECP) using conventional methods, such as the "lens fogging" technique, the meiers (Miles) test, the polenta (Porta) test, the Dolman (Dolman) method, the pinhole test, and the like. Presbyopia usually begins to manifest in people of age 40 years or older. Presbyopes are typically divided into low add groups (requiring up to 1.00 diopter (D) of add power correction); a moderate add group (requiring 1.25D to 1.75D add power correction); or a height add group (requiring add power correction of 2.00D or greater). Typically, highly-undersized presbyopic subjects require an undersea power correction of less than 3.00D.

The multifocal contact lenses described herein include a first multifocal contact lens and a second multifocal contact lens. As used herein, the first multifocal contact lens is the dominant eye for the presbyopic subject and the second multifocal contact lens is the non-dominant eye for the presbyopic subject. That is, each contact lens will be placed on the respective eye of the presbyopic subject.

Each of the first multifocal contact lens and the second multifocal contact lens includes an optic zone. The optical zone of each has an optical zone center and an optical zone perimeter. The optical zone perimeter is radially spaced away or separated from the optical zone center. The optical zone perimeter defines a boundary or edge between the optical zone and the peripheral zone of the contact lens. The optical zone as defined by the optical zone perimeter can be viewed using conventional lens inspection devices and techniques (e.g., interferometers, etc.).

The optic zone of each multifocal contact lens has an aspheric power profile. The aspheric power profile extends from the optic zone center to the optic zone perimeter. For an aspheric power profile, a near vision refractive power and a distance vision refractive power are provided, and thus, multifocal contact lenses each have an add power. The multifocal contact lenses of the invention may be either center distance aspheric or center near aspheric. A central distance aspheric surface is a multifocal contact lens with distance vision power or distance power located at the center of the lens. A central near aspheric surface is a multifocal contact lens with near vision power or near power at the lens center. The distance power corresponds to the relatively more negative part of the power profile and the near power corresponds to the relatively more positive part of the profile. For simplicity, the following description will be based on multifocal contact lenses that are center near aspheres. It is to be understood that the present multifocal contact lenses and methods are not limited to multifocal contact lenses that are center-near aspheric, unless otherwise specified.

As used herein, the add power is the absolute difference in power between the near vision power and the distance vision power. The near power zone of the aspheric power profile corresponds to the zone of the profile (or optic zone) where the power is most positive. In the context of the present invention (including the illustrated embodiments of multifocal contact lenses), the near power zone refers to the central zone of the optical zone that is 2mm in diameter (1 mm radial distance from the center of the optical zone). The distance power zone of the aspheric power profile corresponds to the region of the profile (or optic zone) where the optical power is most negative. In the context of the present invention (including the illustrative embodiments), distance power zone refers to the zone surrounding the central zone and starting at 1.25mm from the center of the optical zone and extending to 2.25mm from the center of the optical zone. The near power of the near power zone refers to the average power of the distance power zone. The distance power of the distance power zone refers to the average power of the distance power zone. Thus, the add power of the present multifocal contact lenses can be understood as the absolute difference between the average distance power and the average near power. The add power of the present multifocal contact lenses, including batches and groups of the present multifocal contact lenses disclosed herein, can be at least 0.50D. In embodiments further described herein, the multifocal contact lenses have an add power of about 0.75D to no greater than 2.00D. For example, the add power may be about 0.75D, about 1.00D, about 1.25D, about 1.50D, about 1.75D, or 2.00D. Preferably, the add power value of the multifocal contact lenses of the invention is between 0.75D and 2.00D.

A first multifocal contact lens of the multifocal contact lenses has a distance vision refractive power effective to provide high contrast visual acuity to the presbyopic subject's dominant eye at a viewing distance of at least 6 meters of 20/30 (snellen notation) or better. In other words, the first multifocal contact lens optimally or best corrects for distance vision in the presbyope dominant eye at distance of distance viewing (i.e., 6 meters or more) and provides clear high contrast visual acuity. Visual acuity is measured using conventional techniques, as understood by those skilled in the art. For example, visual acuity may be determined during an eye examination procedure using a snellen eye chart or logMAR chart. FIG. 7 illustrates a graph of a sensitivity scale, such as Schnellon notation (in foot, meter, or decimal notation), and corresponding logMAR values. Distance vision refractive power refers to the refractive power required to achieve the conscious best distance correction of the presbyope's dominant eye.

The near vision refractive power of the second multifocal contact lens can be effective to provide high contrast visual acuity to the presbyopic subject's non-dominant eye of 20/30 (snellen notation) or better at a viewing distance of about 60 centimeters or less (e.g., about 40 cm). In other words, the second multifocal contact lens provides clear or acceptably high contrast visual acuity to presbyopic subjects at close viewing distances (e.g., 60cm or less). Near vision power is the amount of optical power required to correct the near visual acuity of an individual. Additionally, the distance vision refractive power of the second multifocal contact lens is offset by about +0.25D to about +1.25D relative to the distance power correction for the presbyope non-dominant eye. The distance vision refractive power of the second multifocal contact lenses of the invention can be offset by +0.25D, +0.50D, +0.75D, +1.00D, or +1.25D relative to the distance power correction of the non-dominant eye. In certain embodiments, including the illustrated embodiment, the shift in distance vision refractive power of the second multifocal contact lens is +0.75D or + 1.00D.

The combination of the first and second multifocal contact lenses described above provides the presbyopic subject with binocular visual acuity greater than monocular visual acuity provided by the first multifocal contact lens or the second multifocal contact lens alone. As described herein, with reference to the results of the examples, with the multifocal contact lenses of the invention, a presbyopic subject can be provided with a lens pair (i.e., a first and a second multifocal contact lens) to improve her vision by maintaining the sum of the binocular cortex of individuals of any age (e.g., 40 to 70 years, etc.).

Examples of the present multifocal contact lenses 10 are illustrated in fig. 1A-1F. A first multifocal contact lens 12 is illustrated in fig. 1A and a second multifocal contact lens 22 is illustrated in fig. 1B. The first multifocal contact lens 12 includes an optic zone 14 and a peripheral zone 17 surrounding the optic zone 14. Optical zone 14 has an optical zone center 11 and an optical zone perimeter 13 radially spaced away from optical zone center 11. Radius 15 is illustrated as extending from optical zone center 11 to optical zone perimeter 13. The second multifocal contact lens 22 includes an optic zone 24 and a peripheral zone 27 surrounding the optic zone 24. Optical zone 24 has an optical zone center 21 and an optical zone perimeter 23 spaced radially away from optical zone center 21. Radius 25 is illustrated as extending from optical zone center 21 to optical zone perimeter 23.

In embodiments of the present multifocal contact lenses, the diameter of the optic zone is about 7.00mm to about 9.00mm, and thus, a radius such as radius 15 or radius 25 can be 3.5mm to 4.5mm from the center of the optic zone. As shown in fig. 1C and 1D, aspheric power profiles 19 and 29 of the multifocal contact lenses 12 and 22, respectively, are illustrated over a radius of about 4.1mm such that the optic zone diameter of each of the multifocal contact lenses is about 8.2 mm. Figure 1E is an enlarged graphical illustration of figure 1C depicting the aspheric power profile over a radial distance of 2.5 mm. Figure 1F is an enlarged graphical illustration of figure 1D depicting the aspheric power profile over a radial distance of 2.5 mm. As discussed herein, the focus of the present invention is on the optic zone and the 2.5mm radius of the aspheric power profile, as many presbyopic subjects dilate the pupil diameter to about 5.0 mm. Thus, the central 5.0mm diameter of the optic zone significantly affects the acceptance of the vision correction provided by multifocal contact lenses.

As shown in fig. 1C-1F, the aspheric power profile has a relatively more positive power toward the lens center (i.e., the power at the lens center is more positive than the periphery), and thus, the multifocal contact lenses 12 and 22 can be understood as near-center aspheric surfaces. In other words, the power of the lens is more negative in the periphery of the optical zone relative to the center of the optical zone. In addition, the aspherical power profiles 19 and 29 are normalized so that the distance vision refractive power is set to 0D. This is done for illustration purposes only. In fact, a multifocal contact lens of the invention with a distance power of-3.00D will actually have an aspheric power profile with a power of about-3.00D at a radial distance of 2.5 mm.

Thus, it can be understood that the aspheric power profiles illustrated herein are provided for illustration purposes only to supplement the teachings of the present application. In addition, the illustrated aspheric power profile can be understood to correspond to a nominal or target power profile for use in the present multifocal contact lens designs, or can be understood to represent a relative aspheric power profile as defined herein. The actual power profile of the multifocal contact lenses measured using the optical instrument may be different than that illustrated, similar to those shown in fig. 10D. Furthermore, since the aspheric power profiles illustrated herein are normalized to 0.0D at a radial distance of 2.5mm, these profiles do not account for the true power of each lens (e.g., the actual distance power of the different lenses, e.g., -3.00D, -2.00D, -1.50D, etc.) or overcorrection of the non-dominant ophthalmic lens.

The aspheric power profile of the multifocal contact lenses can be measured or determined using conventional equipment and methods, such as by using interferometers, wavefront sensors, and the like, as understood by those skilled in the art. Some examples of suitable wavefront sensors include those provided by the european union (Optocraft) (erlang, Germany) or rote leigh (rotex) (orer, Israel) or Shack-Hartmann (Shack-Hartmann) wavefront sensors (cleaver (Clear-Wave), albert Medical Optics-wavefront science (Abott Medical Optics-Wave front sciences), Albuquerque, NM, USA). Additionally, the aspheric power profile of the multifocal contact lenses of the invention can be described or characterized by any suitable mathematical function or equation, as understood by those skilled in the art. For example, the aspheric power profile of the multifocal contact lenses of the invention can be expressed as an even-order polynomial, a Zernike (Zernike) polynomial, or the like.

For the present multifocal contact lenses, the aspheric power profile of the first multifocal contact lens and the aspheric power profile of the second multifocal contact lens provide a high contrast visual acuity difference between the first multifocal contact lens and the second multifocal contact lens that is at least one line of the snellen visual acuity chart or the logMAR visual acuity chart at a viewing distance of at least 6 meters.

For the present multifocal contact lenses, the aspheric power profile of the first multifocal contact lens and the aspheric power profile of the second multifocal contact lens are such that the difference in high contrast visual acuity between the first multifocal contact lens and the second multifocal contact lens is less than half a row of the snellen acuity chart or the logMAR visual acuity chart at a viewing distance (i.e., a medium distance) of about 60 centimeters to about 1.5 meters.

For the present multifocal contact lenses, the aspheric power profile of the first multifocal contact lens and the aspheric power profile of the second multifocal contact lens provide a high contrast visual acuity difference between the first multifocal contact lens and the second multifocal contact lens that is at least one line of the snellen visual acuity chart or logMAR visual acuity chart at a viewing distance (i.e., near viewing distance) of no greater than 60 centimeters.

As mentioned herein, any previous multifocal contact lenses can include a first multifocal contact lens and a second multifocal contact lens whose distance vision refractive power can effectively provide different monocular distance visual acuity for each eye wearing each contact lens, and still maintain binocular summation when the lenses are worn simultaneously.

In addition to providing add power correction, multifocal embodiments of the present invention may also include cylindrical correction to correct astigmatism in an individual. Thus, the first multifocal contact lens or the second multifocal contact lens or both may include a toric optic zone having a cylindrical refractive power effective to correct astigmatism in a presbyopic subject. Some non-limiting examples of cylindrical powers that may be used in the present toric multifocal contact lenses include-0.75D, -1.25D, -1.75D, -2.25D, and-2.75D, as well as cylindrical powers having values between any of these listed powers. Accordingly, the cylindrical power values of the present toric multifocal contact lenses can range from-0.75D to-2.75D. As discussed herein, if toric multifocal contact lenses are provided in a series of lenses, the cylindrical refractive power of the series may be-0.75D to-2.75D, or any subset thereof, such as-0.75D to-2.25D, -1.00D to-2.25D, and so forth.

The present multifocal contact lenses can be either hard contact lenses or soft contact lenses. Preferably, the multifocal contact lenses are soft contact lenses. A soft contact lens, as used herein, is a contact lens that can be folded upon itself without breaking. The present multifocal contact lenses can be hydrogel contact lenses. Hydrogel contact lenses, as used herein, refer to hydrated contact lenses having an Equilibrium Water Content (EWC) of at least 10%. Typically, the EWC is between 20% and 90%, and preferably, the EWC of the present multifocal contact lenses is between 30% and 70%. The present contact lenses may also be silicone hydrogel contact lenses. As used herein, a silicone hydrogel contact lens is a hydrogel contact lens that includes silicon or a silicone component. Examples of some hydrogel or silicone hydrogel lens formulations for use in the multifocal contact lenses of the invention have the following U.S. Adopted Names (United States addressed Names, usa): etafilcon A (etafilcon A), turnera filcon A (nelfilcon A), halafilcon A (hiafilcon A), mexafilcon A (metafilcon A), olofilcon A (ocufilcon A), olofilcon B, olofilcon C, olofilcon D, olofilcon A (omafilcon A), balafilcon A (balafilcon A), lotaficon A (lotafilcon A), lotafilcon B, caffeicin A (galyffilcon A), pinofilcon A (senofilcon A), naftificon A (narafilcon A), naftificon B, hypertafilcon A (stafilcon A), or stafffilcon A (stafilcon A).

Fig. 2A and 2B illustrate aspheric power profiles for two different multifocal contact lens a and lens B. Lens a is represented as an aspheric power profile providing an add power between 1.00D and 1.25D. Lens B is represented as an aspheric power profile providing an add power of about 2.00D. The shaded area of fig. 2A corresponds to the area under the curve (AUC) of lens a. The shaded area of fig. 2B corresponds to the AUC of lens B. The AUC for lens B was approximately 47% greater than the AUC for lens a. This can be attributed to the increased add power and the greater rate of change (diopter/mm) (e.g., similar to slope) observed for the lens B power profile. According to the invention, the power profile of the multifocal contact lenses of the invention provide an AUC that is similar to lens a or less than 147% of the AUC of lens a (e.g., less than the AUC of the power profile of lens B). The AUC for any power profile can be calculated using any conventional technique, such as the trapezoidal Rule (Trapezoid Rule), the Simpson 1/3Rule (Simpson's 1/3Rule), or the regression equation integral. In the present application, AUC is calculated using the trapezoidal rule. Briefly, the curve is divided into a series of trapezoids, each trapezoid having an area. AUC corresponds to the sum of the trapezoidal areas. An example of an equation for calculating AUC can be described as: AUC ═ 2 (the sum of two adjacent Y values)/X (the difference of two adjacent X values), where Y corresponds to diopter and X corresponds to millimeters, as shown in the figure.

As described below, including the examples, the distance visual acuity of a presbyopic subject wearing a pair of lens a multifocal contact lenses according to the present invention is significantly improved compared to the same presbyopic subject wearing a pair of lens B multifocal contact lenses. In high light, high contrast conditions, the intermediate vision acuity of the lens a wearer is improved compared to the lens B wearer. In addition, despite the under-correction of the binocular add power, the near vision provided by the lens pair of lens a to the lens a wearer is substantially the same as the near vision provided by the lens pair of lens B to the lens B wearer. This was observed for both moderate and high vignettes. For example, fig. 3 illustrates logMar values under high illumination and high contrast conditions for a moderately caucasian presbyopic subject of a lens pair of the present invention lens a or a lens pair of comparative lens B. As will be appreciated by those skilled in the art, a relatively more negative logMAR value indicates better or clearer visual acuity. Thus, a value less than 0logMAR corresponding to 20/20 (snellen notation) indicates better visual acuity than a value greater than 0 logMAR. As shown in fig. 3, the lens a wearer has improved distance and intermediate visual acuity and fairly near visual acuity compared to the same wearer wearing the lens pair of lens B. As shown in fig. 4, at low light and low contrast, the distance vision acuity is better for lens a wearer than for lens B wearer, and the near vision is equal.

FIG. 5 is similar to FIG. 3, except for highly undersized presbyopic subjects. As shown in fig. 5, at high illumination and high contrast, the highly add lens a wearer has improved distance visual acuity with comparable intermediate and near visual acuity. FIG. 6 is similar to FIG. 4, except for highly undersized presbyopic subjects. As shown in fig. 6, at low light and low contrast, the highly add lens a wearer has improved distance visual acuity and equal near visual acuity.

For fig. 3-6, high and low illumination refer to relative illumination within the visual acuity evaluation area, and high contrast and low contrast refer to relative contrast of the letters read compared to the background of the letters, as understood by those of skill in the art.

Thus, as shown in fig. 3-6, the present multifocal contact lenses provide substantially improved visual acuity (e.g., good distance and near vision without compromising distance vision) for presbyopic subjects with moderate addition and high addition as compared to the following multifocal contact lenses: has a relatively high add power (e.g., about 2.00D or greater) and the AUC of the aspheric power profile is at least about 47% greater than the AUC of the aspheric power profile of the multifocal contact lenses of the invention.

The multifocal contact lenses of the invention can be manufactured in a variety of ways. For example, a contact lens may be lathed from a polymer rod or a polymer button, wherein the aspheric power profile is machined on the surface of the polymer rod or button using a lathe. Alternatively, the contact lens may be spin cast, wherein a single female mold is formed, for example, by injection molding, and which has a concave surface with the aspheric power profile of the present contact lenses. Alternatively, the contact lenses can be static cast molded, which involves polymerizing a lens formulation or polymerizable composition between a male mold member and a female mold member. In a preferred method, the contact lens is static cast molded, as described herein with reference to FIG. 9.

Fig. 9 illustrates a static cast molding manufacturing method 100. The method begins with forming an optical insert at step a. This forming involves lathing an optical surface on the surface of a metal insert (denoted 101 in fig. 9) with the tip of a lathe 103. The lathed optical insert is then placed in the plate 105 of the injection molding machine 107. At step B, the second plate 109 is moved into contact with the plate 105 to form a contact lens mold cavity proximate the optical insert. A mold forming material, such as a polystyrene, polypropylene, or vinyl alcohol mold forming material, is injection molded into the contact lens mold cavity to produce a male mold member 111 and a female mold member 113. At step C, a volume of polymerizable composition can be dispensed on the concave surface of the female mold member 113. At step D, the male and female mold members are placed in contact with each other to form a contact lens mold assembly 115 having a contact lens molding cavity 117 containing a polymerizable composition. At step E, the contact lens mold assembly is placed in a curing system 119 that allows the polymerizable composition to polymerize. Polymerization is typically carried out using heat, ultraviolet light, or a combination thereof. The contact lens mold assembly is removed from the curing system 119 and the male and female mold members are demolded or separated from each other. The polymerized contact lens product remains adhered to either the male or female mold members. In fig. 9, the polymerized contact lens product 121 is still adhered to the concave surface of the female mold member. At step F, the polymerized contact lens product is delensed or separated from the female mold member. Delensing can be performed using a liquid, or it can be performed mechanically without the use of a liquid. At step G, the delensed contact lens product is placed into the cavity of the primary contact lens package 123. In fig. 9, the primary contact lens package is a blister package. At step H, the blister pack is sealed and sterilized by autoclaving or the like. At step I, the sterilized blister pack 125 is placed in a secondary package 127, illustrated in fig. 9 as a carton. The secondary package may then be placed in a cabinet 129 at step J for use, for example, in a fitted lens set as described herein, or may be packaged in a tertiary package for shipping or storage.

In accordance with the present invention, a method of supplying an ECP with multifocal contact lenses for presbyopic subjects is provided. As described herein, a presbyopic subject has a dominant eye and a non-dominant eye that can be determined by ECP. The present methods comprise the steps of manufacturing the present multifocal contact lenses as described herein. The method further comprises the step of providing multifocal contact lenses to an ophthalmologist for fitting a presbyopic subject with the first multifocal contact lens and the second multifocal contact lens. As described herein, the first multifocal contact lens provided to the ECP has a distance vision refractive power effective to provide the presbyopic subject with high contrast visual acuity of 20/30 or better at a viewing distance of at least 6 meters, and the second multifocal contact lens has a near vision refractive power effective to provide the presbyopic subject with high contrast visual acuity of 20/30 or better at a viewing distance of about 60 centimeters or less, and has a distance vision refractive power offset by about +0.25D to about +1.25D relative to the distance power correction for the non-dominant eye of the presbyopic subject. The binocular visual acuity provided to the presbyopic subject by the simultaneous wear of the first and second multifocal contact lenses is greater than or improved over the monocular visual acuity provided to the presbyopic subject by the first multifocal contact lens or the second multifocal contact lens alone. Thus, binocular visual acuity is better than either monocular visual acuity at both near and far viewing distances.

In another method, a method of supplying multifocal contact lenses to a presbyopic subject is provided. Such a method includes the step of receiving an order for multifocal contact lenses as described herein, such as the first and second multifocal contact lenses described above or as illustrated in fig. 1A-1F. After receiving the order, the method includes the step of providing multifocal contact lenses to the presbyopic subject. As described herein, the first multifocal contact lens provided to the ECP has a distance vision refractive power effective to provide the presbyopic subject with high contrast visual acuity of 20/30 or better at a viewing distance of at least 6 meters, and the second multifocal contact lens has a near vision refractive power effective to provide the presbyopic subject with high contrast visual acuity of 20/30 or better at a viewing distance of about 60 centimeters or less, and has a distance vision refractive power offset by about +0.25D to about +1.25D relative to the distance power correction for the non-dominant eye of the presbyopic subject. The binocular visual acuity provided to a presbyopic subject by the simultaneous wear of the first and second multifocal contact lenses is greater than or improved over the monocular visual acuity provided to a presbyopic subject by the first multifocal contact lens or the second multifocal contact lens alone. In some methods, the receiving step optionally includes the step of receiving a prescription for the presbyopic subject for the first and second multifocal contact lenses.

Another method of using the present multifocal contact lenses involves fitting a presbyopic subject with multifocal contact lenses. A method of fitting a presbyopic subject comprises the steps of selecting a first multifocal contact lens for a dominant eye of the presbyopic subject and selecting a second multifocal contact lens for a non-dominant eye of the presbyopic subject. Each of the first and second multifocal contact lenses is as described above, and the first multifocal contact lens has a distance vision refractive power effective to provide high contrast visual acuity of 20/30 or better to the presbyopic subject's dominant eye at a viewing distance of at least 6 meters, and the second multifocal contact lens has a near vision refractive power effective to provide high contrast visual acuity of 20/30 or better to the presbyopic subject's non-dominant eye at a viewing distance of about 60 centimeters or less, and has a distance vision refractive power offset by about +0.25 diopters to about +1.25 diopters relative to the distance vision refractive power correction for the presbyopic subject's non-dominant eye. Binocular visual acuity provided to a presbyopic subject by a pair of simultaneous multifocal contact lenses is greater than monocular visual acuity provided by multifocal contact lenses alone. The method may further comprise the step of determining which eye of the presbyopic subject is the dominant eye. The method may further comprise the step of prescribing the first and second multifocal contact lenses to a presbyopic subject.

Another method of using the present multifocal contact lenses involves improving vision in presbyopic subjects. A method of improving vision in a presbyopic subject comprises the step of providing to the presbyopic subject any of the present multifocal contact lenses. Contact lenses are provided for self-application by an individual on his or her eye. In some fields, the method may include the proviso that the step of wearing by the individual is not part of the method of the invention.

In the above method, the distance vision refractive powers of the first and second multifocal contact lenses are effective to provide different monocular distance visual acuity for each eye wearing each contact lens (e.g., the dominant eye is fully corrected for distance vision and the non-dominant eye is over-corrected for distance vision), and binocular summation is still maintained.

Any of the present multifocal contact lenses can be used in the methods described herein, and in certain embodiments, the first and second multifocal contact lenses are near-center aspheric multifocal contact lenses; in certain embodiments, one or both of the first and second multifocal contact lenses comprises a toric optical zone effective to correct astigmatism in a presbyopic subject; and in certain embodiments, the multifocal contact lenses are hydrogel or silicone hydrogel contact lenses.

Another aspect of the present invention relates to batches of multifocal contact lenses, as described herein. In manufacturing the present multifocal contact lenses on a commercial scale, it is desirable to produce multiple contact lenses in parallel and accumulate the contact lenses so produced in batches. Typically, contact lenses are also accumulated in a group of a single distance power so that they can be packaged in a secondary package containing one or more lenses of the same distance power. As can be appreciated, due to manufacturing tolerances and instrument variability in measuring the power profile, the aspheric power profile of the present multifocal contact lenses can appear slightly different from the nominal or target power profile used to design the lenses. Unlike some existing multifocal contact lenses, which show a significant add power difference within a group of multifocal lenses having different distance powers, or show a power profile shape difference within a group of multifocal contact lenses having different distance powers, the present multiple batches are produced such that the multifocal contact lenses within a group are substantially similar to one another. For example, along the radial distance of the power profile, the add power of the multifocal contact lens may vary plus or minus (±)0.25D, and the aspheric power profile may vary ± 0.375D. Thus, multiple multifocal contact lens groups may be generated according to the present disclosure based on a single nominal or target aspheric power profile used to design multifocal contact lenses.

Thus, one batch of the present multifocal contact lenses includes a plurality of multifocal contact lenses. Each multifocal contact lens includes an optic zone having an optic zone center and an optic zone perimeter radially spaced away from the optic zone center. The optical zone perimeter defines a boundary between the optical zone and the peripheral zone of the contact lens. The optic zone has an aspheric power profile extending from the optic zone center to the optic zone perimeter and providing a near vision refractive power and a distance vision refractive power such that each of the multifocal contact lenses has an add power. As described herein, the add power is the absolute difference in power between the near vision power and the distance vision power.

The batch of the plurality of multifocal contact lenses includes a plurality of first multifocal contact lens groups. For example, the plurality of multifocal contact lenses may be divided into multifocal contact lens groups. As one example, if the plurality of contact lenses is 1,000 contact lenses, then the plurality may comprise 10 groups of 100 contact lenses. Each first multifocal contact lens group includes multifocal contact lenses having a unique single distance vision refractive power corresponding to the distance power index of the first multifocal contact lens group. As one example, the first multifocal contact lens group may include one multifocal contact lens group having a distance refractive power of-3.00D, one multifocal contact lens group having a distance refractive power of-3.25D, one multifocal contact lens group having a distance refractive power of-3.50D, one multifocal contact lens having a distance refractive power of-3.75D, one multifocal contact lens having a distance refractive power of-4.00D, and so forth. The first group of multifocal contact lenses can have multifocal contact lenses with distance refractive powers of +20.00D to-20.00D (0.25D increments) (in other words, the group can have multifocal contact lenses with a single distance refractive power of +20.00D to-20.00D or any value therebetween).

As noted above, within the first multifocal contact lens group, the aspheric power profiles of each multifocal contact lens within a single group having, for example, a single distance refractive power are substantially similar to one another. For example, the total amount of add power provided by the aspheric power profile is substantially similar, and the aspheric power profile shape is substantially similar. The similarity arises from the use of a single nominal or target aspheric power profile in the design of individual groups of multifocal contact lenses.

More specifically, the aspheric power profile of each multifocal contact lens within a single contact lens group provides an add power selected from a value of about 0.75D to 2.00D over a radial distance of 2.5mm from the optic zone center of each lens of the group. For example, the add power may be 0.75D, 1.00D, 1.25D, 1.50D, or 1.75D. The add power of any individual multifocal contact lens varies by no more than ± 0.25D from the add power provided by the relative aspheric power profiles of the plurality of multifocal contact lenses. As used herein, relative aspheric power profile refers to the average of the power profiles of a plurality of multifocal contact lenses within a single group, and with the distance vision refractive power at a radial distance of 2.5mm fixed at 0.00D.

In addition, the aspheric power profile has a similar shape. More specifically, along the power profile for each distance measured, the aspheric power profile of the individual multifocal contact lenses of any first multifocal contact lens group differs by no more than ± 0.375D from the relative aspheric power profile of the plurality of multifocal contact lenses within a single group. For example, if the power of the lens is measured in 0.05mm increments along a 2.5mm radius, the power at any one of the 0.05mm increments is within 0.375D of the power of the relative aspheric power profile at the same location.

Reference is made to fig. 10A-10D for an illustration of batches of multifocal contact lenses of the present invention. Fig. 10A illustrates a batch 40 of multifocal contact lenses. The batch 40 includes a plurality 42 of multifocal contact lenses. The plurality 42 of multifocal contact lenses includes a plurality of first multifocal contact lens groups 44. Each multifocal contact lens group 44 has multifocal contact lenses that provide a unique single distance vision refractive power. These unique single powers are represented in fig. 10A as (for example and without limitation) -3.00D, -3.25D, -3.50D, -3.75D, and-4.00D. Thus, in a first multifocal contact lens group 44 labeled-3.00D distance vision refractive power, one or more multifocal contact lenses within the group, each distance refractive power is about-3.00D.

Figure 10B illustrates the similarity of power profiles for multifocal contact lenses within a single group. The power profile labeled lens a is similar to that illustrated in figures 1E and 1F. However, in fig. 10B, the power distribution of the lens a represents the above-described relative aspheric power distribution. In other words, it is the average of the power profiles of the individual multifocal contact lenses within the group, and the distance refractive power at a radial distance of 2.5mm is 0.00D. The shaded area represents a spread of ± 0.375D from the relative aspheric power profile. Two other multifocal power profiles are illustrated by the lines labeled lens a' and lens a ". Each of these aspheric power profiles is within a 0.375D tolerance from the relative aspheric power profile, as described above, and is thus an example of the present batch of multifocal contact lenses.

Figure 10C illustrates the relative aspheric power profile (lens a) and the add powers of two multifocal contact lenses (lens a' and lens a "). The error bar of the addition power of the lens a reflects a tolerance of the addition power with respect to the aspherical power profile of ± 0.25D. The add powers of both lens a' and lens a "are within a 0.25D tolerance.

Fig. 10D illustrates an example of aspheric power profiles for multiple batches of multifocal contact lenses of the invention, but for three different groups. One trace relates to a group of multifocal contact lenses having a distance refractive power of-1.50D, one trace relates to a group of multifocal contact lenses having a distance refractive power of-3.00D, and one trace relates to a group of multifocal contact lenses having a distance refractive power of-4.00D. As can be appreciated from fig. 10D, the aspheric power profiles of the multifocal contact lens embodiments of the present invention are substantially similar even within different lens groups (e.g., different distance refractive powers).

According to the present invention, in some embodiments of the present multiple batches, one batch comprises a plurality of multifocal contact lenses, which also comprises a plurality of second multifocal contact lens groups. Simply stated, the aspheric power profile of the multifocal contact lenses of the second multifocal contact lens group is different than the aspheric power profile of the multifocal contact lenses of the first multifocal contact lens group. In more detail, the second group of multifocal contact lenses comprises multifocal contact lenses that provide a unique single distance vision refractive power, as described above for the first group. The aspheric power profile of each multifocal contact lens of the second multifocal contact lens group provides an AUC that is between 5% to 45% greater than the AUC of the relative aspheric power profile of the multifocal contact lenses of the first multifocal contact lens group.

An example of the second group of contact lenses is illustrated in fig. 11A with reference numeral 52. The second contact lens group 52 is similar to the first contact lens group 42, except that the power profile of the multifocal contact lenses of the second contact lens group 52 is different than the power profile of the first contact lens group 42. As described herein, the visual acuity of multifocal contact lenses having a power profile similar to that of lens B illustrated in fig. 11B does not perform as well as the multifocal contact lenses of the present invention, e.g., the power profile is similar to that of multifocal contact lenses represented as lens a in fig. 11B. According to this second multifocal contact lens group, the multifocal contact lenses may have an aspheric power profile as referenced for lens C in fig. 11B. The AUC (shaded area) provided by the power profile of lens C is between 5% and 45% greater than the AUC provided by the power profile of lens a. Lenses in the second multifocal contact lens group having the power profile can be used to further improve vision for presbyopic subjects who require add power correction of 2.00D or greater.

In some embodiments, the AUC of the multifocal contact lens group is greater than the AUC of the relative aspheric power profile of the multifocal contact lenses of the first multifocal contact lens group by an amount less than 35%.

As discussed herein, not only is the amount of add power critical to the teachings of the present invention, but the rate of change of optical focus within a 2.5mm radius is also critical. It is believed that the greater the rate of change (e.g., steeper slope), the greater the visual discomfort to the presbyopic subject, because the transition from near to far power is greater over shorter distances. For example, visually, it is apparent that the slope of the power profile of lens B of figure 11B at about 0.75mm to about 1.5mm is steeper than the corresponding slope of the power profile of lens a.

Figure 12 illustrates the power rate of change (D/mm) of the power profile of lens a, lens B and lens C of figure 11B as a function of radial position. The power rate of change is determined by calculating the first derivative of each power profile. Figure 12 illustrates that the absolute values of the maximum power rate of change for lens a are about 0.7-0.8D/mm, lens C is about 0.9D/mm, and lens B is about 1.5D/mm.

Thus, according to the teachings of this disclosure, some embodiments provide individual multifocal contact lenses having an aspheric power profile with a maximum power rate of change absolute value greater than 0.0D/mm and less than 0.9D/mm in any of the present multiple batches.

As discussed herein, multifocal contact lenses in multiple batches of the present invention can be provided as lens pairs that are effective in providing improved visual acuity to a presbyopic subject as compared to the visual acuity provided to the presbyopic subject by either multifocal contact lens of the pair alone. Additionally, in certain embodiments of the present batches, the multifocal contact lenses are near-center aspheric multifocal contact lenses. Multifocal contact lenses can include a toric optic zone having a cylindrical power (e.g., any cylindrical power of about-0.75D to about-2.75D) effective to correct astigmatism in a presbyopic subject. The multifocal contact lenses in the plurality of batches may be hydrogel or silicone hydrogel contact lenses, as described herein.

The present invention also provides methods of manufacturing batches of multifocal contact lenses.

A method of manufacturing a batch of multifocal contact lenses includes the step of forming a plurality of multifocal contact lenses from a polymerizable composition. As discussed herein, the lens can be formed by forming a polymer button and lathing an aspheric power profile on the surface of the polymer button. Alternatively, the lens may be statically cast molded from a mold having an aspheric power profile provided by a contact lens mold formed using a metal insert having an aspheric power profile machined thereon. As discussed herein, each multifocal contact lens includes an optic zone having an optic zone center and an optic zone perimeter radially spaced away from the optic zone center. The optical zone perimeter defines a boundary between the optical zone and the peripheral zone. The optic zone has an aspheric power profile extending from the optic zone center to the optic zone perimeter and providing a near vision refractive power and a distance vision refractive power such that each of the multifocal contact lenses has an add power, wherein the add power is the absolute difference in power between the near vision refractive power and the distance vision refractive power.

As described in the context of the multiple batches of the present invention and repeated herein for clarity, the plurality of multifocal contact lenses comprises a plurality of first multifocal contact lens groups. Each first multifocal contact lens group includes multifocal contact lenses that provide a unique single distance vision refractive power for the first multifocal contact lens group (such as the group described in fig. 10A). The aspheric power profile of each multifocal contact lens within a single contact lens group provides a single add power selected from a value of about 0.75 diopters to 2.00 diopters over a radial distance of 2.5mm from the optic zone center of each lens in the series, and the add power provided by the aspheric power profile of the individual multifocal contact lenses within any first multifocal contact lens group varies by no more than ± 0.25 diopters from the add power provided by the relative aspheric power profiles of the plurality of multifocal contact lenses. The relative aspheric power profile is an average of power profiles of a plurality of multifocal contact lenses and wherein the distance vision refractive power at a radial distance of 2.5mm is fixed at 0.00 diopters. Additionally, along the power profile for each measured radial distance along the power profile, the aspheric power profile of the individual multifocal contact lenses of any first multifocal contact lens group differs by no more than ± 0.375 diopters from the relative aspheric power profile of the plurality of multifocal contact lenses.

In some methods, a further step is provided and is a step of forming a plurality of second multifocal contact lens groups, the power profiles of which are different from the power profile of the first multifocal contact lens group, as described above. Each second multifocal contact lens group includes multifocal contact lenses that provide a unique single distance vision refractive power for the second multifocal contact lens group, and the aspheric power profile of each of the multifocal contact lenses in the second multifocal contact lens group provides an AUC that is between 5% to 45% greater than the AUC of the relative aspheric power profile of the multifocal contact lenses in the first multifocal contact lens group.

In the present methods, forming may comprise the step of designing the multifocal contact lenses to have an aspheric power profile, wherein the aspheric power profile of individual multifocal contact lenses of the plurality of multifocal contact lenses have a maximum rate of change of power having an absolute value greater than 0.0D/mm and less than 0.9D/mm.

The method may further comprise the step of providing a plurality of multifocal contact lenses as lens pairs effective to provide a presbyopic patient with improved visual acuity compared to the visual acuity provided to the presbyopic patient by either multifocal contact lens of the pair alone.

In the method, forming can comprise the step of polymerizing a polymerizable composition in a contact lens mold assembly having a contact lens-shaped cavity in each assembly, and as illustrated in fig. 9. Additionally, the method may comprise the steps of: forming a contact lens mold member insert to provide an optic zone of a plurality of multifocal contact lenses, and forming a first contact lens mold member using the contact lens mold member insert, and placing the first contact lens mold member in contact with a second contact lens mold member to form a contact lens mold assembly, as also illustrated in fig. 9. Alternatively, in the present methods, the forming step can comprise polymerizing the polymerizable composition in a mold to form a polymerized composition, and machining the polymerized composition into the batch of multifocal contact lenses.

Any of the manufacturing methods of the present invention may further comprise the steps of: packaging individual multifocal contact lenses in a primary contact lens package, and placing a single group of packaged multifocal contact lenses of either the first group or the second group in a secondary package, wherein the secondary package comprises indicia identifying a single distance refractive power of a group of multifocal contact lenses and optionally an add power of a multifocal contact lens of the group.

Aspects of the invention also relate to sets of multifocal contact lenses and related methods. One example of a group used in the context of the present invention is an adaptation group, as understood by those skilled in the art. Multiple fitting sets are provided to the ECP such that the ECP can fit an individual with different contact lenses to determine contact lenses that provide an acceptable level of vision improvement and comfort, as discussed herein. The sets of multifocal contact lenses according to the invention include a series of multifocal contact lenses, such as a series of multifocal contact lenses for the dominant eye of a presbyopic subject and a series of multifocal contact lenses for the non-dominant eye of a presbyopic subject. The two series may be present as distinct units, such as two separate series of lenses, or may be provided as a single unit, with all multifocal contact lenses present in a single system, but the dominant eye series and the non-dominant eye series become well-defined when two lenses are selected for presbyopic subjects.

Thus, in accordance with the present invention, one group of the present invention will now be described. A group of multifocal contact lenses for improving vision of presbyopic subjects includes the dominant eye series and the non-dominant eye series. When the set is a fitting set, the set may be understood as a device or article, as understood by those skilled in the art, in which a first multifocal contact lens and a second multifocal contact lens are packaged together in a device to provide an ECP. The ECP may select a first multifocal contact lens and a second multifocal contact lens based on the teachings of the present invention, and the multifocal contact lenses may be used in a fitting procedure for a presbyopic subject.

As described herein, each multifocal contact lens in each series includes an optic zone having an optic zone center and an optic zone perimeter spaced radially away from the optic zone center. The optical zone perimeter defines a boundary between the optical zone and the peripheral zone of the contact lens. The optic zone has an aspheric power profile extending from the optic zone center to the optic zone perimeter and providing a near vision refractive power and a distance vision refractive power such that each of the multifocal contact lenses has an add power. The add power is the absolute difference in power between the near vision power and the distance vision power, as described herein.

In various sets of the present invention, the dominant eye series includes a plurality of dominant eye patient lens sets (e.g., two or more dominant eye patient lens sets). The dominant eye patient lens set is associated with the add power needs of the presbyopic subject (e.g., moderate add, high add and low add). The dominant eye series may include dominant eye patient lens sets, such as a medium and high add set, a low and medium add set, a low and high add set, or a low, medium and high add set. One example is illustrated in fig. 8, as further described herein.

The plurality of dominant eye patient lens sets includes a first dominant eye patient lens set, such as a medium add light set. The first dominant eye patient lens set comprises a multifocal contact lens group comprising multifocal contact lenses that provide a unique distance vision refractive power, as described herein for multiple batches of the present invention. Each contact lens group includes at least one multifocal contact lens. Since each group has a unique distance vision refractive power, the first dominant eye patient lens set can be understood to include a plurality of multifocal contact lenses having distance vision refractive powers of +20.00D to-20.00D, or any value therebetween. In some embodiments, the distance vision refractive power of the multifocal contact lenses of the first dominant eye patient lens set may be-10.00D to +6.00D (in different increments, such as 0.25D increments). A subset of those ranges of distance vision refractive power are also included within the scope of the sets of multifocal contact lenses of the invention. Thus, for the dominant eye series of the intermediate addition patient lens set, the multifocal contact lenses of the intermediate addition patient lens set may be provided in a distance power range of +20.00D to-20.00D (as one example, -10.00D to + 6.00D). Similar ranges may be provided for the high add patient lens set and the low add patient lens set.

The aspheric power profile of each multifocal contact lens of the first dominant eye patient lens set provides a single add power selected from a value of about 0.75D to 2.00D over a radial distance of 2.5mm from the optic zone center of each lens of the series. The aspheric power profile of this shape can be understood with the aid of the description and drawings of figures 1A-1F and 10B-10D and 11B. In some embodiments, the add power value is 1.00D to 1.90D. For example, the add power may be about 1.00D, 1.10D, 1.20D, 1.25D, 1.30D, 1.40D, 1.50D, 1.60D, 1.70D, 1.75D, 1.80D, or 1.90D or any value therebetween. As another example, in some embodiments of the sets of the present invention, the add power value is in the range of 0.75D to 1.75D.

The add power provided by the aspheric power profile of the individual multifocal contact lenses of the first dominant eye patient lens set varies by no more than ± 0.25D from the add power provided by the relative aspheric power profile of the multifocal contact lenses of the first dominant eye patient lens set. Similar to that described herein, the relative aspheric power profile corresponds to an average of the power profiles of the plurality of multifocal contact lenses of the first dominant eye patient lens set with the distance vision refractive power at a radial distance of 2.5mm fixed at 0.00D.

The multi-set, non-dominant eye series of the present invention also includes a plurality of patient lens sets. More specifically, the non-dominant eye series includes a plurality of non-dominant eye patient lens sets related to the add power needs (e.g., moderate add, high add, and low add) of the presbyopic subject, as described above for the dominant eye patient lens set. The plurality of non-dominant eye patient lens sets includes a first non-dominant eye patient lens set including multifocal contact lenses. The aspheric power profile of each of the multifocal contact lenses of the first non-dominant eye patient lens set provides a single add power selected from a value of about 0.75D to 2.00D over a radial distance of 2.5mm from the optic zone center. The add power of these lenses is similar or identical to the dominant eye patient lens set. However, the distance vision refractive power provided by the aspheric power profile of the multifocal contact lenses of the first non-dominant eye patient lens set is offset by about +0.25D to about +1.25D relative to the distance power correction for the presbyopic subject.

One set of the invention may also include a second non-dominant eye patient lens set as a component of the non-dominant eye series. In such an embodiment, the aspheric power profile of each multifocal contact lens of the second non-dominant eye patient lens set provides an AUC that is between 5% to 45% greater than the AUC of the relative aspheric power profile of the multifocal contact lenses of the first non-dominant eye patient lens set. In some embodiments, the AUC of the aspheric power profile of the lens of the second non-dominant eye patient lens set is less than 35% greater than the relative aspheric power profile, and in some other embodiments the AUC is less than 30% greater than the relative aspheric power profile. One example of such an aspheric power profile for the second non-dominant eye patient lens set is illustrated at lens C in fig. 11B.

In a plurality of sets including a second non-dominant eye patient lens set, the aspheric power profile of each multifocal contact lens of the second non-dominant eye patient lens set provides a single add power of no greater than 2.00 diopters over a radial distance of 2.5mm from the optic zone center of each lens of the second non-dominant eye patient lens set, and the aspheric power profile of the multifocal contact lenses of the second non-dominant eye patient lens set is offset by about +0.25 diopters to about +1.25 diopters relative to distance power correction for a presbyopic subject.

In any of the present pluralities, along the power profile, for each radial distance measured along the power profile, the relative aspheric power profile of the multifocal contact lenses of the dominant eye series and the relative aspheric power profile of the multifocal contact lenses of the non-dominant eye series differ from each other by less than ± 0.375D.

Any of the above-described multi-set non-dominant eye series may further include a third non-dominant eye patient lens set comprising multifocal contact lenses, such as a low addition patient lens set. Along the power profile, for each radial distance measured along the power profile, the average aspheric power profile of each multifocal contact lens of the third non-dominant eye patient lens set differs by less than ± 0.375D from the average aspheric power profile of the multifocal contact lenses of the first dominant eye patient lens set.

In any of the above-described sets of multifocal contact lenses, the aspheric power profile of the multifocal contact lenses in the non-dominant eye series has a maximum power rate of change greater than 0.00D/mm and less than 1.00D/mm. For example, the maximum power rate of change may be less than 0.95D/mm. In some embodiments, the maximum power rate of change may be expressed as an absolute value of about 0.7D/mm to about 0.8D/mm. In some embodiments, the maximum power rate of change occurs at a radial distance of about 2.0mm to about 2.5 mm. These embodiments can be used for medium add patient lens sets and low add patient lens sets. In some embodiments, the maximum power rate of change may be expressed as an absolute value of about 0.7D/mm to about 0.9D/mm, and it may be present at a radial distance of about 0.8mm to about 2.2 mm. These embodiments can be used for a high add patient lens set if desired.

In any of the above groups, the dominant eye series of multifocal contact lenses and the non-dominant eye series of multifocal contact lenses may be grouped in lens pair groups. The lens pair groups include a first patient lens pair group for, for example, moderate presbyopic subjects, a second patient lens pair group for, for example, high presbyopic subjects, and a third patient lens pair group for, for example, low presbyopic subjects, such that any multifocal contact lens pair of the lens pair groups is effective to provide improved visual acuity to the presbyopic subject as compared to the visual acuity provided to the presbyopic subject by either multifocal contact lens of the pair alone.

As described herein, in any of the present lens sets, the multifocal contact lenses can be near-center aspheric lenses, can include a toric optic zone for correcting astigmatism, or can be hydrogel or silicone hydrogel contact lenses, or a combination thereof.

In some embodiments of the present multi-sets, the dominant eye series of multifocal contact lenses and the non-dominant eye series of multifocal contact lenses are grouped in lens pair sets comprising a moderate addition lens pair set and a low addition lens pair set and a high addition lens pair set. The pair of high add lens pairs comprises a) a first multifocal contact lens providing an add power correction of about 1.50D to 2.00D and having an aspheric power profile effective to improve visual acuity of a presbyope's dominant eye; and b) a second multifocal contact lens providing an add power correction of about 1.50D to 2.00D and having the following aspheric power profile: the distance vision power correction is offset by about +0.25D to about +1.25D relative to the distance power correction for presbyopic subjects.

In some embodiments of the present lens sets, the dominant eye series of multifocal contact lenses and the non-dominant eye series of multifocal contact lenses are grouped in lens pair sets comprising a moderate add lens pair set and a low add lens pair set and a high add lens pair set comprising two multifocal contact lenses, at least one of the two multifocal contact lenses providing an add power correction greater than 2.00 diopters.

One example of a set of the present invention is illustrated in fig. 8. In this example, the set may be understood as a fitting set. A set 30 includes a dominant eye series 32 and a non-dominant eye series 34. The dominant eye series 32 includes a plurality of dominant eye patient lens sets 32A, 32B and 32C. The non-dominant eye series includes a plurality of non-dominant eye patient lens sets 34A, 34B and 34C. The patient lens sets each correspond to the add power needs of the presbyopic subject. For example, patient lens sets 32A and 34A correspond to low add presbyopic subjects; patient lens sets 32B and 34B correspond to moderate add presbyopes; patient lens sets 32C and 34C correspond to height add presbyopes. As illustrated in this set 30, each lens shares a common single aspheric power profile, denoted as labeled lens a, as described herein. For patient lens set 34B, the non-dominant eye is overcorrected +0.25D to +1.25D, and preferably overcorrected +0.75D for the moderate addition individuals. For patient lens set 34C, the non-dominant eye is overcorrected +0.25D to +1.25D, and preferably overcorrected +0.75D or +1.00D for the highly additive individual.

Another example of a set of lenses of the invention is illustrated in FIG. 13. This lens set 130 is identical to the lens set 30 of FIG. 8, except that for the non-dominant eye series patient lens set for presbyopes of advanced adduction, the lenses of this patient lens set 134C have different aspheric power profiles as represented by the labeled lens C, which can be seen in the lens C power profile of FIG. 11B. Although the power profile of lens C provides a greater AUC than the power profile of lens a, it is overcorrected to about +0.25D to about +1.25D for distance vision, and preferably, overcorrected to +0.75D or + 1.00D.

As described herein, in addition to monocular visual acuity differences and binocular visual acuity improvements, the present multifocal contact lenses are also manufactured with reduced variability across batches of lenses and across the lens' distance power range. For example, unlike some multifocal contact lenses in which the add power varies as the distance power of the lenses in the lens set varies, the present multifocal contact lenses maintain a substantially constant add power over different distance powers of the lenses. Additionally, in the present lens sets, unlike some other prior multifocal contact lenses, less than three add powers are required in a series of lenses. In addition, unlike existing multifocal contact lenses, variability in the shape of the refractive power distribution is reduced in lenses of different distance refractive powers.

The present invention also relates to methods of providing multifocal contact lenses for improving vision of presbyopic subjects, according to the teachings and sets of the present invention. The method comprises the step of manufacturing a plurality of multifocal contact lenses, as described herein. Preferably, the multifocal contact lenses are manufactured using a static cast molding process, as illustrated, for example, in fig. 9. Each multifocal contact lens includes an optic zone having an optic zone center and an optic zone perimeter spaced away from the optic zone center. The optical zone perimeter defines a boundary between the optical zone and the peripheral zone of the contact lens. The optic zone has an aspheric power profile extending from the optic zone center to the optic zone perimeter and providing a near vision refractive power and a distance vision refractive power such that each of the multifocal contact lenses has an add power, wherein the add power is the absolute difference in power between the near vision refractive power and the distance vision refractive power. The method further comprises the step of packaging the multifocal contact lenses in contact lens packages to produce packaged multifocal contact lenses. The contact lens package may comprise a primary package, such as a blister pack or a vial; secondary packages, such as cartons, containing one or more contact lens packages; or a tertiary package, such as a carton, containing one or more secondary packages.

The packaged multifocal contact lenses are provided to a contact lens distributor, a contact lens retailer, or an ECP, or a combination thereof. The packaged contact lenses include a dominant eye series of multifocal contact lenses and a non-dominant eye series of multifocal contact lenses.

The dominant eye series includes a plurality of dominant eye patient lens sets associated with the presbyope add power requirements, as described above. The plurality of patient lens sets includes a first dominant eye patient lens set including a multifocal contact lens group including multifocal contact lenses that provide a unique distance vision refractive power. Each group includes at least one multifocal contact lens, and the aspheric power profile of each multifocal contact lens of the first dominant eye patient lens set provides a single add power selected from a value of about 0.75 diopters to 2.00 diopters over a radial distance of 2.5mm from the optic zone center of each lens of the series. The add power provided by the aspheric power profile of the individual multifocal contact lenses of the first dominant eye patient lens set varies by no more than ± 0.25D from the add power provided by the relative aspheric power profile of the multifocal contact lenses of the first dominant eye patient lens set. As described herein, wherein the relative aspheric power profile corresponds to an average of the power profiles of the plurality of multifocal contact lenses of the first dominant eye patient lens set and wherein the distance vision refractive power at a radial distance of 2.5mm is fixed at 0.00D.

The non-dominant eye series of the present method includes a plurality of patient lens sets associated with the add power needs of the presbyopic subject, as described herein. The plurality of patient lens sets includes a first non-dominant eye patient lens set including multifocal contact lenses, the aspheric power profile of each multifocal contact lens in the first non-dominant eye patient lens set providing a single add power selected from a value of about 0.75 diopters to 2.00 diopters over a radial distance of 2.5mm from the optic zone center of each lens in the first non-dominant eye patient lens set, and the distance vision refractive power provided by the aspheric power profile of the multifocal contact lenses in the first non-dominant eye patient lens set is offset by about +0.25 diopters to about +1.25 diopters relative to distance power correction for a presbyopic subject.

In some embodiments of the present methods, a non-dominant eye series of packaged contact lenses is provided comprising a second non-dominant eye patient lens set comprising multifocal contact lenses. The aspheric power profile of each multifocal contact lens of the second non-dominant eye patient lens set provides an AUC that is between 5% to 45% greater than the AUC of the relative aspheric power profile of the multifocal contact lens of the first non-dominant eye patient lens set, as described above.

In the above method, the aspheric power profile of each multifocal contact lens of the second non-dominant eye patient lens set can provide a single add power of no greater than 2.00D within 2.5mm radial distance from the optic zone center of each lens of the second non-dominant eye patient lens set, and the aspheric power profile of the multifocal contact lenses of the second non-dominant eye patient lens set is offset by about +0.25D to about +1.25D relative to the distance power correction for the presbyopic subject.

In any of the above methods, along the power profile, for each radial distance measured along the power profile, the relative aspheric power profile of the multifocal contact lenses in the dominant eye series and the relative aspheric power profile of the multifocal contact lenses in the non-dominant eye series may differ from each other by less than ± 0.375D.

In any of the above methods, the non-dominant eye series may comprise a third non-dominant eye patient lens set comprising multifocal contact lenses, wherein along the power profile, for each radial distance measured along the power profile, the mean aspheric power profile of each multifocal contact lens in the third non-dominant eye patient lens set differs by less than ± 0.375D compared to the mean aspheric power profile of the multifocal contact lenses in the first dominant eye patient lens set.

As discussed herein, in certain embodiments, the aspheric power profile of the multifocal contact lenses in the non-dominant eye series have an absolute maximum power rate of change of less than 1.0D/mm (e.g., 0.7D/mm to 0.9D/mm). As yet another example, an aspheric power profile at a radial distance of about 2.0mm to about 2.5mm may have an absolute value of about 0.7 diopters/mm to about 0.8 diopters/mm.

In some methods, the dominant eye series of multifocal contact lenses and the non-dominant eye series of multifocal contact lenses are grouped in lens pair groups, the lens pair groups comprising a first patient lens pair group, a second patient lens pair group, and a third patient lens pair group, such that any multifocal contact lens pair in the lens pair groups is effective to provide the presbyopic subject with improved visual acuity compared to the visual acuity provided to the presbyopic subject by either multifocal contact lens of the pair alone.

Other methods of using multifocal contact lenses are also provided. For example, the method can be understood as involving the perspective of an ECP or other similar person or entity responsible for eye examination and prescription of contact lenses. The method does not involve a step of treating a presbyopic subject, as the multifocal contact lenses are worn by the individual themselves to provide temporary vision correction or vision improvement (i.e., correct vision when the individual wears multifocal contact lenses). When the individual removes the multifocal contact lenses, the individual's vision remains uncorrected.

As provided by the present invention and as understood from the disclosure herein, a method of prescribing multifocal contact lenses to a presbyopic subject comprises the step of fitting the presbyopic subject with a pair of multifocal contact lenses. A presbyopic subject is a moderate or high degree of addition subject, or in other words, a presbyopic subject requires an addition power correction of at least 1.25D (e.g., 1.25D to 3.00D). Thus, presbyopic subjects require an add power correction of one of 1.25D, 1.50D, 1.75D, 2.00D, 2.25D, 2.50D, 2.75D, or 3.00D. According to these methods, many presbyopic subjects require 1.25D to 2.50D of add power correction.

In a multifocal contact lens pair so fitted, the first multifocal contact lens includes an aspheric power profile derived from a first nominal or target aspheric power profile, and the second multifocal contact lens of the pair includes a second aspheric power profile derived from the first nominal aspheric power profile. While the aspheric power profiles of the first and second multifocal contact lenses are derived from a single nominal aspheric power profile, the aspheric power profile of the second multifocal contact lens provides a distance vision refractive power that is offset by about +0.25D to about +1.25D relative to the distance power correction for the presbyope non-dominant eye. Thus, the monocular distance visual acuity for each eye wearing each contact lens is different (e.g., the dominant eye is fully corrected for distance vision, and the non-dominant eye is over-corrected for distance vision), and the binocular summation is still maintained.

The aspheric power profiles of the first and second multifocal contact lenses are substantially similar, as described above with reference to figures 10A-10D. It can be generally understood that the first and second multifocal contact lenses, which may or may not have different distance vision refractive powers (depending on the distance vision correction desired in each eye of the individual), have aspheric power profiles derived from a single nominal or target aspheric power profile used to design the multifocal contact lenses. Additionally, although it is derived from a single nominal aspheric power profile, the aspheric power profiles of the first and second multifocal contact lenses may be slightly different due to manufacturing tolerances and inspection techniques, as described herein. Unlike existing multifocal contact lenses, however, the multifocal contact lenses of the present invention have substantially similar aspheric power profiles over the distance vision refractive power range (e.g., -20.00D to + 20.00D; or-10.00D to + 6.00D; or-6.00D to 0.00D, etc.) and for presbyopic subjects requiring different degrees of add power correction. In contrast, some prior multifocal contact lenses have a first aspheric power profile with a relatively low add power for low add presbyopic subjects (e.g., presbyopic subjects requiring an add power correction of 0.25D to 1.00D); a second aspheric power profile having a moderate add power for moderate add presbyopes (e.g., presbyopes requiring add power correction of 1.25D to 1.75D); and a third aspheric power profile having a large add power for highly adducted presbyopic subjects (e.g., presbyopic subjects requiring an add power correction of at least 2.00D). Thus, the fitting process for the present multifocal contact lenses is simpler than existing fitting processes for existing multifocal contact lenses. In some methods, it can be understood that the present multifocal contact lenses and sets of multifocal contact lenses provide less than three different patient lens sets to low, medium, and high add presbyopes. This is because multifocal contact lenses have a similar lens design or aspheric power profile, which is different from some existing multifocal contact lenses having three different designs or power profiles for three different presbyopic groups. An example of such a simplified fitting system is illustrated in FIG. 8, as described herein. As can be understood from the drawings, a single lens design (lens a) with a power profile as illustrated in fig. 10B and 10C can be fitted according to the invention for each eye of low, medium and high add presbyopic subjects.

During the fitting process, the ECP can evaluate the vision provided with individual multifocal contact lenses and pairs of multifocal contact lenses, as well as the comfort and fitting characteristics of the multifocal contact lenses. If the presbyopic subject is acceptable for the vision provided by the contact lens, and the comfort and fit are acceptable, the ECP may develop a prescription for the present multifocal contact lenses. As understood in the art, the fitting process may include the following steps: the corneal diameter is recorded, and the distance, near, intermediate, cylindrical and prism power corrections required to correct the individual's vision are determined, and the optical axiality of the lens is observed, or the lens movement is observed, or any combination thereof, among others.

In the present methods, some methods may optionally include a second step of fitting the multifocal contact lens pair to a presbyopic subject. For example, the method may comprise the step of fitting a second multifocal contact lens pair, wherein the second multifocal contact lens pair comprises a first multifocal contact lens having the same aspheric power profile as the first aspheric power profile of the first multifocal contact lens of the first pair, and the aspheric power profile of the second contact lens of the second pair provides an AUC that is between 5% and 45% greater than the AUC of the aspheric power profile of the first multifocal contact lens of the second pair.

The above-described embodiments of the method can be understood with reference to fig. 11B and 13. For example, if a presbyopic subject is not satisfied with the fitting characteristics of the first multifocal lens pair, then the presbyopic subject may be fitted with a second multifocal contact lens pair, such as a pair consisting of: a first multifocal contact lens having an aspheric power profile as represented by lens a in fig. 11B and a second multifocal contact lens having an aspheric power profile as represented by lens C in fig. 11B. This may be particularly useful for highly undersized presbyopes, as reflected by the example fitting set depicted in FIG. 13.

As illustrated in fig. 13, if a presbyopic subject is fitted with a second pair of multifocal contact lenses of the present invention, the aspheric power profile of the second multifocal contact lens of the second pair is marked to provide a distance vision refractive power that is offset by about +0.25D to about +1.25D relative to the distance power correction for the non-dominant eye of the presbyopic subject, which is similar in principle to the second multifocal contact lens of the first pair.

Additionally, some of the present methods may further comprise the step of performing an eye examination of the presbyopic subject to determine which eye of the presbyopic subject is the dominant eye. As discussed above, the ocular dominance can be determined using any conventional technique, including lens fogging techniques.

The method may further include the steps of determining a prescription for a presbyopic subject and prescribing the presbyopic subject with the first and second multifocal contact lenses. The first and second multifocal contact lenses may be from either the first lens pair or the second lens pair described herein.

As can be appreciated from the present disclosure, the first and second multifocal contact lenses can be near-central aspheric surfaces, one or both can include a toric optic zone effective to correct astigmatism in presbyopic subjects, or can be hydrogel contact lenses or silicone hydrogel contact lenses, or a combination thereof.

Some of the present methods may further comprise the step of providing the multifocal contact lenses to the presbyopic subject for self-wear by the subject. As explained above, the present method is not a method of medical treatment and, therefore, in some contexts, it is not claimed that the wearing step is performed by a presbyopic subject or that the step is the subject of the present invention. Some other methods may include the step of obtaining data from an individual to determine a prescription for a presbyopic subject.

In addition to the foregoing, some embodiments of the multifocal contact lenses of the invention can have an aspheric power profile that does not include a transition zone within the optic zone. This may be due to the relatively slow rate of change of diopter/mm over a radial distance of 2.5mm as compared to multifocal contact lenses having a larger rate of change. However, although these embodiments do not have a transition zone in the optical zone, a transition or blend can be provided at a junction of the contact lens, such as a junction between the optical zone perimeter and the peripheral zone, or a junction between the peripheral zone and the edge region, or a combination thereof.

Examples of the invention

The following examples illustrate certain aspects and advantages of the present invention and are not to be construed as limiting thereof.

Example 1

Multifocal contact lens manufacture

Multifocal contact lenses having aspheric power profiles as described above and as illustrated in figures 1A-1F are produced using a static cast molding process.

Machining the metal insert to form an optical quality surface corresponding to a surface of the multifocal contact lens. A nominal or target or predetermined aspheric power profile is used to form an aspheric power profile within the optic zone portion of the optical quality surface of the insert. Examples of nominal aspheric power profiles are illustrated in figures 1C-1F.

The inserts are placed in an injection molding machine to form contact lens mold cavities when the inserts are placed adjacent to each other. Contact lens mold materials (e.g., particles of polystyrene, polypropylene, vinyl alcohol polymer, etc.) are melted and injected into contact lens mold cavities to form female and male contact lens mold members. The female contact lens mold member has a concave optical quality surface corresponding to the anterior surface of the contact lens. The male contact lens mold member has a convex optical quality surface corresponding to the posterior surface of the contact lens.

A volume of the lens-forming polymerizable composition is placed in contact with the concave surface of the female mold member. The male mold member is placed in contact with the female mold member to form a contact lens mold assembly comprising a contact lens molding cavity containing a polymerizable lens-forming composition. Multifocal contact lenses are produced from lens-forming polymerizable compositions having the names omafilcon a or hyperthenafilcon a, enfilcon a or stanffilcon a adopted in the United States (USAN). The resulting multifocal contact lenses are hydrogel contact lenses or silicone hydrogel contact lenses.

The contact lens mold assembly is placed in a thermal oven or an ultraviolet oven to polymerize the polymerizable composition by heat or ultraviolet radiation, respectively. The contact lens mold is exposed to curing conditions for about 1 hour or more.

After polymerization of the precursor composition, the contact lens mold assembly is demolded to separate the male and female mold members. The polymerized contact lens product is delensed from one of the mold members by immersing the lens and mold members in a delensing liquid or mechanically, such as by pressing the mold members to release the contact lens product.

The delensed lens product is then placed into a contact lens package, such as into a cavity of a blister package, and then filled with a contact lens packaging solution, or optionally washed with water, alcohol, or a combination thereof, prior to placement into a contact lens package. The contact lens packages, each containing a single multifocal contact lens, are then sealed and sterilized by autoclaving. The sterilized packets are placed in secondary packaging (e.g., cartons). The secondary package is then placed in a tertiary package (e.g., carton). The contact lens package can also be placed in a display device containing a contact lens storage area. The display device with contact lenses can be understood as a fitting set.

Multifocal contact lenses with different distance vision refractive powers or distance refractive powers are manufactured. The distance vision refractive power is in the range of-20.00D to + 20.00D. Multifocal contact lenses are manufactured in batches, each batch having a different distance vision refractive power. For example, batches were made with distance vision refractive powers of-20.00D to-10.00D (1D increments), -10.00D to +6.00D (0.25D increments), and +6.00D to +20.00D (1D increments).

Example 2

Visual acuity-moderate add light individuals

A set of presbyopic subjects requiring an add power correction of +1.25D to +1.75D (as determined by the ophthalmologist ECP; individuals having an add power prescription of +1.25D, +1.50D or +1.75D) is selected for fitting the multifocal contact lenses of the present invention as described above and as illustrated in figures 1A-1F. Multifocal contact lenses so fitted have an add power of about 1.00D to less than 1.25D, e.g., about 1.15D, over a 5mm diameter (2.5mm radial distance) of the center of the optic zone.

The ECP determines the ocular dominance, distance vision refractive power correction, and add power requirements of each individual. The distance vision of the dominant eye is optimally or fully corrected with the first multifocal contact lenses of the invention (e.g., the distance vision refractive power of the first multifocal contact lens corresponds to the distance vision prescription for the dominant eye as determined by ECP). That is, if the dominant eye of the individual requires about-3.00D vision correction to achieve acceptable monocular visual acuity (e.g., 20/30 or better, using snellen notation), the eye is provided with a first multifocal contact lens having-3.00D distance vision refractive power. The second multifocal contact lens of the invention is selected for the non-dominant eye such that the distance vision refractive power of the multifocal contact lens is over-corrected relative to the distance vision prescription for the non-dominant eye. Overcorrection is from about +0.25D to about + 1.25D; for example, overcorrection may be +0.25D, +0.50D, +0.75D, +1.00D, or + 1.25D. In this example, the overcorrection is + 0.75D. Thus, if the non-dominant eye of the individual requires-2.00D distance vision correction, the individual is fitted with a second multifocal contact lens having a distance vision refractive power of-1.25D. With this second multifocal contact lens having an add power of less than 1.25D, the individual achieves acceptable monocular near vision correction (e.g., 20/30 or better, using snellen notation). These first and second multifocal contact lenses are illustrated in fig. 2A and 2B as lens a.

The same set of individuals was fitted with multifocal contact lens pairs having a greater add power and a greater rate of change (first derivative) than the pairs described in the preceding two paragraphs. The two lenses of such a multifocal contact lens pair are illustrated in fig. 2A and 2B with lens B. As shown in figure 2B and described above, lens B has an add power greater than lens a, has a power rate of change greater than lens a, and accordingly, has an area under the curve (AUC) greater than lens a, as depicted by the power distribution shaded areas in figures 2A and 2B.

The high-illumination and high-contrast visual acuity of an individual wearing lens a lens pair is determined, and then the high-illumination, high-contrast visual acuity of an individual wearing lens B lens pair is determined. Visual acuity is measured at a far (distance or far) viewing distance (e.g., at least 6 meters), a near viewing distance (e.g., 60 centimeters or less), and a medium viewing distance (e.g., a distance between 60 centimeters and 1.5 meters). The visual acuity results are illustrated in fig. 3 and the data are expressed as logMAR values. 20/20 visual acuity is reflected as 0.00 on the logMAR chart, and better visual acuity is expressed as a relatively more negative logMAR value.

As shown in fig. 3, a lens pair (e.g., a multifocal contact lens of the invention) can improve visual acuity at far and intermediate viewing distances as compared to a lens B lens (i.e., lens a logMAR value is more negative than lens BlogMAR value). At near viewing distances, the lens a logMAR value was slightly more positive than the lens B logMAR value, but the difference was not statistically significant.

Low-light and low-contrast visual acuity at distance and near viewing distances was also determined for the individual for lens a and lens B lenses (see fig. 4). Although both logMAR values are greater than 0, lens a lenses provide improved distance visual acuity (more negative logMAR value) at low illumination and low contrast and equal near visual acuity at low illumination and low contrast compared to lens B lenses.

The visual acuity measurement was actually performed as described in example 2 and the results actually obtained were as predicted above.

Thus, lens a lenses are corrected for distance vision in the dominant eye and over-corrected for distance vision in the non-dominant eye and under-corrected for the add power needs of the individual (excluding over-correction for the non-dominant eye, as described herein), which provides clinically acceptable near visual acuity without compromising distance and intermediate visual acuity, as compared to lens B lenses, which have add powers that more closely correspond to the add power needs of the addition individual of the present invention.

Example 3

Visual acuity-high add-down individuals

A set of presbyopic subjects requiring an add power correction of +2.00D or greater (as determined by the ophthalmologist ECP; the subject has an add power prescription of +2.00D, +2.25D, +2.50D, +2.75D, or + 3.00D) is selected for fitting the multifocal contact lenses of the present invention as described above and as illustrated in figures 1A-1F. Multifocal contact lenses so fitted have an add power of about 1.00D to less than 1.25D, e.g., about 1.15D, within a diameter of 5mm at the center of the optic zone. These lenses have the same design or the same power profile as the lens a lens described in example 2.

This height add-down group of individuals is suitable for either lens a lenses or lens B lenses, as described in example 2. The main difference between example 2 and example 3 is that the individuals of example 3 required higher add power correction as determined by ECP.

Similar to the results described in example 2, the highly undersized individuals wearing lens a lens pairs (i.e., optimally or best corrected for distance vision in the dominant eye, and overcorrected +0.75D for distance vision in the non-dominant eye) exhibited improved visual acuity at distance of distance viewing at high illumination, high contrast and low illumination, low contrast (fig. 5 and 6, respectively). Lens a lens exhibits similar logMAR values at medium distance and high illumination and high contrast and similar logMAR values at near distance and high illumination, high contrast and low illumination, low contrast.

The visual acuity measurement was actually performed as described in this example 3 and the results actually obtained were as predicted above.

Thus, lens a lenses are optimally or best corrected for distance vision in the dominant eye and overcorrected for distance vision in the non-dominant eye and undercorrected for the individual's add power requirement, which provides clinically acceptable near visual acuity without compromising distance and intermediate visual acuity as compared to lens B lenses, which have add powers that more closely correspond to the add power requirement of the present highly-addicted individual.

Example 4

A similar study was conducted as described in examples 2 and 3 using 49 individuals (ranging in age from 42-65 years). Substantially similar results were obtained to those described in examples 2 and 3. For example, the results for all individuals demonstrate that lens a lenses provide improved distance visual acuity compared to lens B lenses without compromising intermediate and near visual acuity (e.g., lens a lenses and lens B lenses exhibit equal performance in intermediate and near visual acuity). When the individual's data is grouped into intermediate addition individuals (requiring addition power correction +1.25D to +1.75D) and high addition individuals (requiring addition power correction +2.00D to + 2.50D), lens a lenses provide significantly improved high contrast distance visual acuity compared to lens B lenses. The low contrast distance visual acuity was significantly improved for the high add subjects, and no significant difference was observed for the low contrast distance visual acuity for the moderate add subjects. For high contrast intermediate visual acuity, the lens a lenses performed similarly to the lens B lenses without any significant difference observed. For high contrast near visual acuity, the medium addition individuals wearing lens a lenses reported similar visual acuity as the medium addition individuals wearing lens B lenses, and the high addition individuals wearing lens B lenses appeared to show significant improvement. For low contrast visual acuity, lens a lenses performed similarly to lens B lenses without any significant visual acuity difference observed.

While the disclosure herein refers to certain illustrated embodiments, it is to be understood that these embodiments are presented by way of example only, and not limitation. While exemplary embodiments are discussed, the intent of the foregoing detailed description should be taken to cover all modifications, alternatives, and equivalents of the embodiments as may fall within the spirit and scope of the invention as defined by the claims.

A number of publications and patents are cited above. Each of the cited publications and patents is incorporated herein by reference in its entirety.

Claims (7)

1. A multifocal contact lens for a presbyopic subject, said presbyopic subject having a dominant eye and a non-dominant eye, said lens comprising:

fitting a first multifocal contact lens pair of the presbyopic subject, said presbyopic subject requiring an add power correction of at least 1.25 diopters (D), wherein a first multifocal contact lens of the first multifocal contact lens pair includes a first aspheric power profile derived from a first nominal aspheric power profile, and a second multifocal contact lens of the first multifocal contact lens pair includes a second aspheric power profile derived from the first nominal aspheric power profile, but the second aspheric power profile in the first multifocal contact lens pair provides a distance vision refractive power that is offset by +0.25D to +1.25D relative to the distance power correction for the non-dominant eye of the presbyopic subject, whereby the monocular distance visual acuity for each eye wearing each contact lens is different and the binocular summation is maintained when each contact lens is worn simultaneously.

2. The lens of claim 1, further comprising a second multifocal contact lens pair that fits the presbyopic subject, wherein the second multifocal contact lens pair comprises a first multifocal contact lens, the aspheric power profile of the first multifocal contact lens of the second multifocal contact lens pair being the same as the first aspheric power profile of the first multifocal contact lens pair, and the second contact lens of the second multifocal contact lens pair comprises a second multifocal contact lens, the aspheric power profile of the second multifocal contact lens provides a profile having an area under the curve that is between 5% to 45% greater than the area under the curve of the aspheric power profile of the first multifocal contact lens of the second multifocal contact lens pair.

3. The lens of claim 2, wherein the aspheric power profile of the second multifocal contact lens pair provides a distance vision refractive power that is offset by +0.25 diopters to +1.25 diopters relative to the distance power correction for the non-dominant eye of the presbyopic subject.

4. The lens of claim 1, wherein the first and second multifocal contact lenses so adapted are each near-center aspheric multifocal contact lenses.

5. The lens of claim 1, wherein at least one of the first multifocal contact lens and the second multifocal contact lens so fitted comprises a toric optic zone effective in correcting astigmatism of the presbyopic subject.

6. The lens of claim 1, wherein the multifocal contact lenses so fitted are hydrogel contact lenses.

7. The lens of claim 6, wherein the multifocal contact lenses so fitted are silicone hydrogel contact lenses.