HK1139211B - Ophthalmic lens element - Google Patents

Description

Ophthalmic lens element

This international patent application claims priority from australian provisional patent application No.2006905101 filed on 9, 15, 2006 and australian provisional patent application No.2007901348 filed on 3, 15, 2007, the contents of each of which are hereby incorporated by reference.

Technical Field

The present invention relates to ophthalmic lens elements for retarding or preventing myopia, and methods of designing these lens elements.

Background

To provide focused vision, the eye must be able to focus light on the retina. The ability of the eye to focus light on the retina depends largely on the shape of the eyeball. If the eyeball is "too long" with respect to its "on-axis" focal length (meaning the focal length along the optical axis of the eye), or if the outer surface of the eye (i.e., the cornea) is too curved, the eye will not be able to properly focus distant objects on the retina. Similarly, an eyeball that is "too short" with respect to its on-axis focal length, or has a too flat outer plane, will not properly focus near objects on the retina.

An eye that focuses distant objects in front of the retina is called a myopic eye. The resulting condition is known as myopia and is typically corrected using appropriate single vision glasses. When fitted to a wearer, conventional single vision glasses correct myopia associated with central vision. Meaning that ordinary single vision glasses correct myopia associated with vision using the fovea and the near fovea (parafovea). Central vision is commonly referred to as foveal vision.

While ordinary single vision lenses can correct Myopia associated with central vision, recent investigations have shown (reviewed in r.a. stone & d.l. flitcrof (2004) Ocular Shape and Myopia, published by annals academic of Medicine, volume 33, page 1, pages 7-15) that the off-axis focal length characteristics of the eye often differ from the axial and paraxial focal lengths. In particular, myopic eyes show less myopia in the peripheral region of the retina than in the fovea. This difference is due to the prolate vitreous cavity shape of the eye in myopic eyes.

Indeed, recent American studies (Mutti, D.O., Sholtz, R.I., Friedman, N.E., Zadnik, K. Peripheral refraction and Ocular shape in children ("Peripheral refraction and Ocular shape in children"), invest, Ophthalmol. Vis. Sci.2000; Vol. 41, page 1022. 1030) observed that mean (. + -. Standard deviation) produces an equivalent sphere of + 0.80. + -. 1.29D relative to Peripheral refraction in a child's myopic eye.

Interestingly, studies using chickens and monkeys have shown that defocus in the peripheral retina alone can cause elongation of the foveal region with the fovea remaining clear (separate reports by JoshWallman and Earl Smith at the tenth international conference on myopia, cambridge, uk, 2004) and consequent myopia.

On the other hand, epidemiological studies have shown a correlation between myopia and near work. It is known that the prevalence of myopia in well-educated populations is significantly higher than that of unskilled labor. Too long a reading time can result in hyperopic foveal blur caused by insufficient accommodation. This allows many eye care professionals to formulate progressive or bifocal lenses for youngsters with increased myopia. Special progressive lenses suitable for children have been designed (us 6,343,8610). The therapeutic efficacy of these lenses in clinical trials has been shown to be statistically significant in slowing myopia progression, but clinical significance appears to be limited (e.g., Gwiazda et al, 2003, invest. ophthalmol. vis. sci., vol. 44, pp. 1492-1500). However, Walker and Mutti (2002), optom. vis. sci., vol. 79, page 424-430, have found that accommodation also increases relative peripheral refractive error, which may be caused by increased choroidal tension during the period that accommodation pulls the peripheral retina inward.

Unfortunately, conventional myopia correcting lenses occasionally produce clear or defocused images in the peripheral region of the retina. Thus, existing ophthalmic lenses for correcting myopia may not eliminate the stimulus for deepening myopia (stimuli).

The discussion of the background to the invention herein is included to explain the scope of the invention. This is not to be taken as an admission that any of the material referred to was published, known or part of the common general knowledge in the priority date of any of the claims.

Summary of The Invention

In summary, the present invention provides an ophthalmic lens element exhibiting a relatively positive refractive power (plus power) throughout the peripheral region of the lens compared to the central region, and a power and surface astigmatism distribution that provides clear distance vision in the central region and clear near vision in the regions of the peripheral region that may be used for the wearer's near vision task.

The distribution of relatively positive power across the peripheral region provides an optical correction for retarding or preventing myopia in the wearer. In use, providing a relative positive power through the peripheral region provides a "stop signal" around the periphery of almost the entire wearer's retina and may thus be more effective in retarding or preventing the progression of myopia than an ophthalmic lens element that provides the required positive power contributor only in the lower portion of the lens element.

The peripheral zone comprises a zone in the form of a lower or near vision zone adapted to the wearer's near vision task, connected by a channel of low astigmatism to an upper or far vision zone in the central zone. Providing a corridor and near vision zone may reduce the need for the lens wearer to tilt their head while reading and thus make the lens more comfortable to wear.

Thus, the present invention provides an ophthalmic lens element comprising:

a central region of low surface astigmatism, the central region comprising an upper vision zone providing a first refractive power suitable for a wearer's distance vision task; and

a peripheral region of positive refractive power relative to the first refractive power, the peripheral region surrounding the central region, the peripheral region providing an optical correction for reducing or preventing myopia of the wearer, the peripheral region comprising:

one or more regions of relatively high surface astigmatism;

a lower zone of low surface astigmatism for myopic tasks of the wearer; and

a channel of low surface astigmatism having a surface power that varies from the surface power of the upper viewing zone to the surface power of the lower viewing zone.

The present invention also provides a progressive ophthalmic lens element comprising:

an upper viewing zone providing a first refractive power for distance vision; and

a peripheral region surrounding the upper viewing zone and providing a positive power relative to the first power throughout the region, the peripheral region comprising an inferior or near viewing zone providing a power for near vision and a channel connecting the upper and lower viewing zones, the channel having a surface power that varies from the surface power of the upper viewing zone to the surface power of the lower viewing zone;

wherein the distribution of the average power across the peripheral region is positive relative to the distribution of the upper viewing zone and provides an optical correction for reducing or preventing myopia in the wearer.

The upper viewing zone will be adapted for the wearer's on-axis vision tasks and thus will generally be the viewing zone adapted for "straight ahead" or substantially "straight ahead" viewing. The upper viewing zone is generally located in the portion of the lens element that is likely to be used for distance vision.

The first refractive power is typically a prescribed refractive power corresponding to the optical correction for the wearer's need for distance vision. Thus, for the remainder of the description, reference to "far vision zone" is understood to be a reference to the upper viewing zone.

In one embodiment, the peripheral region of positive power is a region that exhibits a positive mean power relative to the first power over the entire region.

In an embodiment, the lower viewing zone is located in an area of the ophthalmic lens that may be used for near vision. The lower viewing zone (which will be referred to herein as the "near vision zone") may be inset to the nasal side of the lens relative to the distance vision zone.

The inclusion of a near vision zone may reduce the need for the wearer to tilt the head during near vision tasks such as reading and thus may make the lens more comfortable to wear. Still further, the inclusion of a near vision zone may reduce the need for accommodation to be applied on the wearer's eye for near vision tasks such as reading. Accordingly, ophthalmic lens elements according to embodiments of the present invention are particularly designed for adolescent use because adolescents typically do not have the need for myopia correction due to the effectiveness of accommodation of the eye to view closer objects. For example, a teenager can use the far vision zone to look at near objects with the aid of the accommodation system. However, the inclusion of a near vision zone in the peripheral zone may assist juvenile wearers in reducing their accommodation requirements during near vision tasks, which has been shown to have a small but not negligible effect on slowing the progression of myopia. Accordingly, embodiments of the present invention may be more effective in retarding or even preventing myopia progression in particular children than conventional myopia control lenses.

The distance vision zone of an ophthalmic lens element may be designed for use at relatively low positive and negative (plus and dminus) prescription powers. For example, a base arc of 0.50D to 5.00D may be used. It will be appreciated that the power of the distance vision zone may vary according to the wearer's needs, or may be in the range of, for example, flat (plano) to-4.00D.

The power profile of the peripheral region will contribute to the optical correction used to correct peripheral vision as the wearer views the object through the distance vision zone. In use, the power profile of the peripheral region may provide a stimulus for retarding or preventing myopia in the form of a "stop signal" for the undesirable growth of the eye that retards or prevents the progression of myopia.

Accordingly, one embodiment of the present invention provides an ophthalmic lens element that provides the proper optical correction for the wearer's on-axis distance vision needs while providing a stop signal to retard or prevent myopia resulting from distance vision blur resulting from long term exposure of the eye to the peripheral retina.

In one embodiment, the stop signal may compensate for the varying focal plane of the wearer's eye to remove most of the hyperopic blur from the peripheral region of the retina for the dominant hyperopic eye position. Thus, it is expected that the distribution of positive refractive power across the entire peripheral area of an ophthalmic lens element according to embodiments of the present invention will provide an optical correction that provides a stop signal for undesirable vision growth, thus resulting in retardation or prevention of myopia around substantially the entire periphery of the retina.

An ophthalmic lens element according to an embodiment of the present invention includes a front side and a back side (i.e., the surface closest to the eye). The front and back surfaces may be shaped to provide appropriate contours of optical power to the central and peripheral regions. In this specification, the positive average power of the peripheral region will be referred to as "peripheral power", and the power of the distance vision zone will be referred to as "distance power".

The front and back surfaces of the lens can have any suitable shape. In one embodiment, the front surface is aspheric and the back surface is spherical or toric.

In another embodiment, the front surface is spherical and the back surface is aspherical.

In yet another embodiment, the front and back surfaces are aspherical surfaces. It will be understood that aspheric surfaces may include, for example, toric surfaces, multifocal surfaces, or combinations thereof.

The first or distance optical power and the peripheral optical power will generally correspond to different optical correction requirements of the wearer. In particular, the distance power will correspond to the on-axis, paraxial, optical correction required to provide clear vision (i.e. foveal vision) for the wearer's distance vision task, whereas the peripheral power will generally serve the dual purpose of providing off-axis optical correction when viewing distant objects through the upper viewing zone and on-axis correction when viewing near objects through the near vision zone to reduce the wearer's accommodation requirements for near vision tasks.

The required peripheral power will typically be embodied as a single value of surface power and will typically be a positive mean power.

The positive mean refractive power of the peripheral region may be selected based on the optical correction requirement expressed in terms of clinical measurements that characterize the peripheral correction requirement of the wearer, i.e. the optical correction required to correct the peripheral vision of the wearer. Any suitable technique may be used to obtain these requirements, including but not limited to peripheral Rx data or ultrasound a-scan data. These data can be obtained using equipment known in the art, such as an open-type automatic refractometer (e.g., Shin-Nippon open-type automatic refractometer).

As explained above, the peripheral region is a region of positive power relative to the distance power, and thus provides "positive power correction". The positive power may range from about 0.50D to 3.00D relative to the distance power. However, a positive refractive power in the range of about 1.00D to 2.00D is also suitable.

In one embodiment, the power of the positive mean power over a radius of substantially 20mm in the peripheral region relative to the distance reference point of the upper viewing zone is at least 0.50D for any radius from the geometric center of the lens element.

In another embodiment, the average positive power in the peripheral region is at least 1.00D relative to a distance reference point of the upper viewing zone over substantially any radius of 20 mm.

In yet another embodiment, the positive mean power in the peripheral region is at least 1.50D over substantially any radius of 20mm relative to the power at the distance reference point of the upper viewing zone.

In one embodiment, the upper or distance vision zone may be shaped and/or sized to provide a range of vision corrections required for eye rotation for distance vision tasks. In other words, the distance vision zone may be shaped and/or sized to support the wearer's distance vision needs throughout the angular range of eye rotation. Similarly, the near vision zone may also have a shape and/or size that provides a low surface astigmatism region based on a series of eye rotations for the wearer's near vision task. In other words, the near vision zone or lower vision zone may be shaped and/or sized to support the wearer's near vision needs throughout the angular range of eye rotation.

The area of the distance vision zone will generally be greater than the area of the near vision zone.

The present invention also provides a progressive ophthalmic lens element comprising:

an upper viewing zone providing a first refractive power for distance vision, the first refractive power being in a range of substantially flat to-4.00D; and

a peripheral region surrounding the upper viewing zone and providing a positive power relative to the first power throughout the region, the peripheral region including a lower or near viewing zone providing a power for near vision, and a channel connecting the lower and upper viewing zones, the channel having a surface power that varies from the surface power of the upper viewing zone to the surface power of the lower viewing zone;

wherein the power of the positive mean power over all radii greater than substantially 20mm in the peripheral region relative to the far reference point of the upper viewing zone is at least 0.50D for any radius from the geometric center of the lens element, and wherein the distribution of the positive mean power throughout the peripheral region provides an optical correction for retarding or preventing myopia in the wearer.

Ophthalmic lens elements according to embodiments of the present invention may be formulated with any suitable material. In one embodiment, a polymer material may be used. The polymeric material may be of any suitable type, for example it may comprise a thermoplastic or thermoset material. Diallyl glycol carbonate based materials, such as CR-39(PPG industries, Inc.) may be used.

The polymeric member may be constructed from a crosslinkable polymeric casting composition, for example as described in U.S. patent No.4,912,155, U.S. patent application S/n.07/781,392, australian patent application 50581/93, 50582/93, 81216/87, 74160/91 and european patent specification 453159a2, the entire disclosures of which are incorporated herein by reference.

The polymeric material may comprise a dye, preferably a photochromic dye, which may for example be added to the monomer formulation used to produce the polymeric material.

An ophthalmic lens element according to an embodiment of the present invention may further comprise a standard additional coating, including an electrochromic coating, to the front or back side.

The front lens surface may include an anti-glare (AR) coating, such as the type described in U.S. patent No.5,704,692, the entire contents of which are incorporated herein by reference.

The front lens surface may include an abrasion resistant coating, such as the type described in U.S. Pat. No.4,954,591, the entire contents of which are incorporated herein by reference.

The front and back sides may further comprise one or more additives commonly used in casting compositions, such as inhibitors, dyes, e.g. as described above including thermochromic and photochromic dyes, polarizers, UV stabilizers and materials capable of modifying the refractive index.

The present invention also provides a method of formulating or designing an ophthalmic lens element for the purpose of retarding or preventing myopia, the method comprising:

obtaining by the wearer:

a first optically corrected required value for the upper viewing zone that provides foveal vision for the on-axis vision task; and

a second optical correction required value which provides a contributing factor to the retardation or prevention of myopia in the peripheral region of the wearer's eye;

selecting or designing an ophthalmic lens element according to the value of the optical correction, the ophthalmic lens element comprising:

a central region of low surface astigmatism, the central region including an upper viewing zone providing a first refractive power corresponding to a value required for a first optical correction; and

a peripheral region of positive power relative to the first power, the peripheral region surrounding the central region and providing a distribution of positive power including a value required for a second optical correction, the peripheral region comprising:

one or more regions of relatively high surface astigmatism;

a second zone of low surface astigmatism for myopic tasks of the wearer; and

a channel of low surface astigmatism having a surface power that varies from the surface power of the upper viewing zone to the surface power of the second viewing zone.

In an embodiment, a method according to the present invention may further comprise:

determining head movement and/or eye movement characteristics of the wearer; and

the size of the upper viewing zone, lower viewing zone and channels are determined according to the head movement and eye movement characteristics of the wearer.

Ideally, the size of the upper, second and corridor are adjusted to support clear vision over a range of eye rotation angles around the wearer's distance and near vision needs.

A method according to embodiments of the invention may be performed by a processing system comprising suitable computer hardware and software. Thus, the invention also provides a treatment system for dispensing or designing an ophthalmic lens for retarding or preventing myopia in an eye of a wearer, the system comprising:

an input device for obtaining the following properties for wearing:

a first optically corrected required value for the upper viewing zone that provides foveal vision for the on-axis vision task; and

a second optical correction required value which provides a contributing factor to the retardation or prevention of myopia in the peripheral region of the wearer's eye;

processing means for processing the optical correction value to select or design an ophthalmic lens element in accordance with the optical correction value, the ophthalmic lens element comprising:

a central region of low surface astigmatism, the central region including an upper viewing zone providing a first refractive power corresponding to a value required for a first optical correction; and

a peripheral region of positive power relative to the first power, the peripheral region surrounding the central region and providing a distribution of positive power including a value required for a second optical correction, the peripheral region comprising:

one or more regions of relatively high surface astigmatism;

a second zone of low surface astigmatism for myopic tasks of the wearer; and

a channel of low surface astigmatism having a surface power that varies from the surface power of the upper viewing zone to the surface power of the second viewing zone.

In an embodiment, a system according to the present invention may further comprise:

an input device for accepting or obtaining head movement and eye movement characteristics of a wearer; and

processing means for modifying the size and/or shape of the upper and/or second viewing zones in accordance with head movement and eye movement characteristics of the wearer.

The invention also provides a method of retarding or preventing myopia, the method comprising providing to a myopic patient spectacles having a pair of ophthalmic lens elements, each lens element for a respective eye and comprising:

a central region of low surface astigmatism, the central region comprising an upper vision zone providing a first refractive power suitable for a wearer's distance vision task;

a peripheral region of positive refractive power relative to the first refractive power, the peripheral region surrounding the central region, the peripheral region being for providing an optical correction for the relief or prevention of myopia in the wearer, the peripheral region comprising:

one or more regions of relatively high surface astigmatism;

a second zone of low surface astigmatism for a myopic task of the wearer; and

a channel of low surface astigmatism having a surface power that varies from the surface power of the upper viewing zone to the surface power of the second viewing zone.

A preferred embodiment of a lens element according to the present invention provides an ophthalmic lens element having a peripheral region that provides a positive mean refractive power (i.e., "positive power correction") relative to a first or upper vision zone of the central region. However, because positive refractive power is not adaptive, it will cause blurring on the fovea of the retina as the eye rotates to view objects in the periphery of the original range of vision. To compensate for this, embodiments of the ophthalmic lens element provide a central region comprising a distance vision zone sized to provide a prescribed power over a region corresponding to the wearer's normal eye rotation for distance vision tasks, and a near vision zone independently having a positive average power relative to the distance vision zone over a region corresponding to the wearer's normal eye rotation for near vision tasks.

Thus, embodiments may provide correct foveal correction not only for the wearer's distance and near vision needs, but also in regions representing the general range of eye rotation prior to head rotation.

Mutti et al (2000) found that assuming large scatter in the near peripheral refraction, the degree of positive refractive power correction required by the wearer will change. Thus, in a series of embodiments of the present invention, the plurality of peripheral aspherizations may have a positive power correction range.

Before turning to a description of embodiments of the present invention, some language should be used above or throughout the specification to describe the same.

For example, reference in this specification to the term "lens element" refers to all forms of individual refractive optical bodies employed in the ophthalmic field, including, but not limited to, ophthalmic lenses, lens wafers (lens wafers), and semi-finished lens blanks that require further processing as required by the particular wearer.

Still further, with reference to the term "surface astigmatism", these references are understood to be a measure of the degree to which the curvature of the lens varies between intersecting planes that are perpendicular to the lens surface at some point on the lens surface.

Throughout this specification, reference to the term "foveal region" is understood to be the region of the retina that includes the fovea and is bounded by the juxtafocal zone.

Further, throughout the specification, when used in relation to the retina, reference to the term "peripheral region" refers to the region of the retina that is outside of and surrounding the foveal region.

The ophthalmic lens element according to the invention simultaneously and substantially corrects both central and peripheral vision during a distance vision task. This type of correction is expected to eliminate or at least slow myopia progression in myopes, especially young people with myopia.

Brief Description of Drawings

The present invention will now be described with respect to various examples illustrated in the accompanying drawings. It must be understood, however, that the following description is not intended to limit the generality of the above description.

In the drawings:

FIG. 1 is a simplified diagram illustrating different zones of an ophthalmic lens element according to an embodiment of the present invention;

FIG. 2 is a contour plot of surface astigmatism of an ophthalmic lens element according to an embodiment of the present invention;

FIG. 3 is a contour plot of the tangential power of an ophthalmic lens element having the contour plot of surface astigmatism depicted in FIG. 2;

FIG. 4 is a contour plot of the sagittal power of an ophthalmic lens element having the contour plot of surface astigmatism depicted in FIG. 2;

figure 5 is a contour plot of the mean power of an ophthalmic lens element having the contour plot of surface astigmatism depicted in figure 2;

FIG. 6 is a graph showing the eye path tangential and sagittal curvature distributions of an ophthalmic lens having a contour plot of surface astigmatism depicted in FIG. 2; and

FIG. 7 shows another simplified representation of the ophthalmic lens element shown in FIG. 1, but with the peripheral area shown as a shaded area; and

FIG. 8 shows another simplified representation of the ophthalmic lens element shown in FIG. 1, but with the areas of relatively high surface astigmatism shown as shaded areas; and

fig. 9 is a flow chart of a method of selecting and/or designing an ophthalmic lens according to an embodiment.

Detailed description of the drawings

Fig. 1 depicts a simplified representation of an ophthalmic lens element 100 according to an embodiment of the present invention, with different zones identified for reference. Fig. 1 is simplified as much as possible, and is merely intended to generally identify and represent the relative positions of different zones of an ophthalmic lens element 100. Therefore, the shape of the different regions, or their size or precise location, is not limited to that shown in FIG. 1.

As depicted in fig. 1, the ophthalmic lens element 100 includes a region of relatively low surface astigmatism, shown here as a central region 102. The zone 102 includes a first or upper viewing zone 104 having a first refractive power (power) suitable for the wearer's distance vision task, a second or near viewing zone 106, and a corridor (corridor) 108. The second or near vision zone 106 is configured to accommodate the wearer's near vision tasks and is thus located in the lower viewing zone. For the remainder of this description, the first or upper viewing zone 104 will be referred to as the "distance viewing zone" and the second or lower viewing zone will be referred to as the "near viewing zone".

In the illustrated embodiment, the lens element 100 also includes a region of relatively high astigmatism 110 (shown here as the region bounded by the perimeter "P" of the lens element and the outer dashed line "D") surrounding the region of relatively low surface astigmatism 102. It will be appreciated that the region of relatively high astigmatism 110 does not necessarily surround the region of relatively low surface astigmatism 102.

The positive power of the near vision zone 106 will be adapted to the wearer's near vision task and reduce the need for accommodation when viewing near objects through the near vision zone 106.

The channel 108 provides a low surface power zone having a surface power that varies from the surface power of the distance vision zone 104 to the surface power of the near vision zone 106.

In the present invention, the near vision zone 106, channel 108 and zone 110 form a peripheral zone 112 of positive average power relative to the first power. For ease of illustration, the arrangement of the peripheral regions 112 is depicted in simplified form in FIG. 7, wherein the peripheral regions 112 are shown as shaded regions.

Referring back to fig. 1, the distance vision zone 104 provides a prescribed power suitable for the wearer's on-axis distance vision. On the other hand, the peripheral region 112 is a positive mean power zone (relative to the distance vision zone 104) having a profile that provides an optical correction for retarding or preventing myopia in the wearer and is adapted to the wearer's myopia needs. The peripheral region 112 will typically exhibit a range of positive power from low to intermediate relative to the power of the distance vision zone 104.

As shown in fig. 7, the peripheral region 112 surrounds the central region 102 in that it extends around the central region 102 to provide a continuous zone of positive power relative to the first power.

The near vision zone 106 of the peripheral zone 112, as well as the corridor 108, will have relatively low surface astigmatism compared to the zone 110 (in other words, the zone bounded by "D" and "P") which will provide relatively high surface astigmatism. For ease of explanation, fig. 8 depicts regions of relatively higher surface astigmatism 110 as shaded regions and regions of lower surface astigmatism (i.e., distance vision zone 104, near vision zone 106, and corridor 108) as non-shaded regions. Although in this example the region of relatively higher astigmatism is depicted as a single region completely surrounding the region of low astigmatism (in other words, the distance vision zone 104, the corridor 108 and the near vision zone 106), it will be appreciated that this need not always be the case. For example, in some embodiments, the corridor 108 and the near vision zone 106 intersect a region of relatively high astigmatism 110, such that the region forms an arc extending between opposite sides of the corridor 108 and the near vision zone 108 and over the far vision zone 104.

Returning again to fig. 1 and as described above, the peripheral region 112 provides a contributing factor in retarding or preventing myopia associated with the peripheral region of the retina by providing optical correction to the wearer's peripheral vision. Such an arrangement may be more effective in retarding or even preventing myopia progression than conventional myopia control lenses, particularly in children.

The positive mean refractive power of the peripheral region may be selected based on the optical correction requirement expressed in terms of clinical measurements that characterize the peripheral correction requirement of the wearer, i.e. the optical correction required to correct the peripheral vision of the wearer. Any suitable technique may be used to obtain these requirements, including but not limited to peripheral Rx data or ultrasound a-scan data. These data can be obtained using equipment known in the art, such as an open-type automatic refractometer (e.g., Shin-Nippon open-type automatic refractometer).

Ophthalmic lenses according to embodiments of the invention may be designed, distributed, and/or selected according to the wearer's peripheral corrective measurements. Fig. 9 shows a flow chart 900 of a method of dispensing or designing an ophthalmic lens element for the purpose of retarding or preventing myopia. As shown, at step 902, the optical correction required to provide foveal vision for the on-axis vision task is obtained.

At step 904, a second optical correction is obtained that is required to provide a contributing factor for retarding or preventing myopia in a peripheral region of the wearer's eye. In other words, optical correction is required to correct the peripheral vision of the wearer.

At step 906, an ophthalmic lens element is selected and/or designed according to the optical correction value obtained at steps 902, 904. The ophthalmic lens selected and/or designed comprises a central zone of low surface astigmatism comprising a distance vision zone 104 (with reference to figure 1) providing a first refractive power corresponding to the value required for the first optical correction; and a peripheral region of positive power with respect to the first power, which surrounds and includes one or more regions of relatively high surface astigmatism 110 (see figure 1). The peripheral region will also include a lower or near vision zone 108 for the wearer's near vision tasks and a channel 108 (see fig. 1) having a surface power that varies from the surface power of the upper vision zone 104 (see fig. 1) to the surface power of the lower vision zone 106 (see fig. 1). The peripheral region provides a distribution of positive average powers corresponding to or selected based on the value required for the second optical correction.

The selection and/or design of the lens elements also involves the selection and/or design of the size and/or shape of the distance vision zone 104 so as to correspond to the degree of normal eye rotation of the wearer before head rotation occurs. For example, the distance vision zone 104 may provide an aperture that is shaped and/or sized to provide clear foveal vision over a range of eye rotations. Similarly, the shape and/or size of the near vision zone 108 may be selected and/or designed based on measurements of the wearer's typical eye rotation before head rotation occurs.

Example 1

Referring to fig. 2 to 5, an optical lens element 200 according to an embodiment of the present invention is designed to have a base curve of 3.25D. In the depicted example, the lens element 200 has a diameter of 60 mm. Contour plots of surface astigmatism, tangential power, sagittal power, and mean surface power of the optical lens element 200 are given in fig. 2 to 5, respectively. Fig. 3-5 also depict a lens covering layer 300 representing an example of a lens shape that may be cut from the lens element 200 for reference. In the present case, the lens overlay 300 represents the outline of a frame of a 55 x 35mm area centered 2mm above the geometric center of the ophthalmic lens element 200.

As shown in fig. 2, the 0.5D astigmatism contour 202 defines a region of low surface astigmatism that includes the distance vision zone 104, the near vision zone 106, and the corridor 108. The depicted embodiment provides a relatively wide distance vision zone 104, referred to as the upper viewing zone, and a near vision zone 106 disposed below the distance vision zone 104 and connected thereto via a corridor 108.

In the depicted example, the region of relatively high surface astigmatism 112 surrounds the region 102 and includes astigmatism contours 204, 206, 208. In the present case, the contour lines 204 and 206 have the same value. As shown in fig. 5, region 112 provides a positive mean power up to about 1.50D relative to the mean power of the distance vision zone 104 at the Distance Reference Point (DRP). In the present example, the distance reference point 302 (refer to fig. 5) is located about 8mm above the geometric center of the ophthalmic lens element 200.

Fig. 6 depicts the tangential power 602 and the sagittal power 604 of the ophthalmic lens element 200 along the 280 degree meridian generally corresponding to the eye path (eyepath) below the ophthalmic lens element 200 of the wearer. As shown, in fig. 6, the ophthalmic lens element 200 provides a curvature of about 3.75D extending to a distance of about 10mm above the geometric center of the lens.

The depicted lens provides a tangential and sagittal power of at least 0.50 over a radius of 20mm from the geometric center of the lens element (in other words, the intersection of lines "a" and "B" in fig. 5). Indeed, in this example, for any radius starting from the geometric center of the lens element 200 and having a radius range of substantially 20mm, the positive mean power in the peripheral region is at least 0.50D compared to the power of the distance reference point of distance vision zone 104. It will be clearly understood that other embodiments of the invention may provide similar or greater positive mean power at lower radius ranges.

Finally, it will be understood that there may be other variations and modifications to the configurations described herein that also fall within the scope of the present invention.

Claims (15)

1. An ophthalmic lens element comprising:

a central region of low surface astigmatism, the central region comprising an upper vision zone providing a first refractive power suitable for a wearer's distance vision task; and

a peripheral region of positive power relative to the first power, the peripheral region surrounding the central region and comprising:

one or more regions of higher surface astigmatism than the central region;

a lower or near vision zone of low surface astigmatism, the lower vision zone for near vision tasks of the wearer; and

a channel of low surface astigmatism having a surface power that varies from the surface power of the upper viewing zone to the surface power of the lower viewing zone;

wherein the peripheral region provides an optical correction for retarding or preventing myopia of the wearer.

2. A progressive ophthalmic lens element comprising:

an upper viewing zone providing a first refractive power for distance vision; and

a peripheral region surrounding the upper viewing zone and providing a positive power relative to the first power throughout the region, the peripheral region including a lower viewing zone providing a power for near vision and a channel connecting the upper and lower viewing zones, the channel having a surface power that varies from a surface power of the upper viewing zone to a surface power of the lower viewing zone;

wherein the distribution of the average power across the peripheral region is positive relative to the upper viewing zone and provides an optical correction for reducing or preventing myopia in the wearer.

3. An ophthalmic lens element according to claim 1 or 2, wherein the first refractive power is a prescribed refractive power for providing an optical correction corresponding to the wearer's demand for coaxial hyperopic viewing.

4. An ophthalmic lens element according to claim 1 or 2, characterized in that the optical correction of the peripheral area provides a contributing factor for the retardation or prevention of myopia associated with the peripheral area of the retina.

5. An ophthalmic lens element according to claim 4, characterized in that the positive mean power over all radial elongations greater than 20mm from the geometric center of the lens element in the entire peripheral region is in the range of 0.50D to 3.00D relative to the power of the distance reference point of the upper viewing zone.

6. An ophthalmic lens element according to claim 4, characterized in that for any radius from the geometric center of the lens element, the positive mean refractive power over a radial extension of 20mm in the peripheral region is at least 0.50D relative to the power of the distance reference point of the upper viewing zone.

7. An ophthalmic lens element according to claim 4, characterized in that for any radius from the geometric center of the lens element, the positive mean refractive power over a radial extension of 20mm in the peripheral region is at least 1.00D relative to the power of the distance reference point of the upper viewing zone.

8. An ophthalmic lens element according to claim 4, characterized in that for any radius from the geometric center of the lens element, the positive mean power over a radial extension of 20mm in the peripheral region is at least 1.50D relative to the power of the far reference point of the upper viewing zone.

9. An ophthalmic lens element according to claim 1 or 2, characterized in that the refractive power in the upper viewing zone ranges from flat to-4.00D.

10. An ophthalmic lens element according to claim 9, characterized in that the upper viewing zone is sized to support their usual eye rotation for distance vision tasks prior to rotation of the wearer's head.

11. A series of ophthalmic lens elements comprising a plurality of ophthalmic lens elements according to claim 1 or 2, wherein each ophthalmic lens element of the series of ophthalmic lens elements provides a peripheral zone having a positive mean power range corresponding to different peripheral correction requirements.

12. A series of ophthalmic lens elements according to claim 11, characterized in that for each ophthalmic lens element in the series of ophthalmic lens elements and for a radius from the geometric center of the lens element, the positive mean refractive power over any radial extension greater than 20mm in the peripheral region is at least 0.50D relative to the power of the far reference point of the upper viewing zone, and the positive mean refractive power over this radial extension can vary up to 2.50D depending on the peripheral correction requirements of the wearer.

13. A series of ophthalmic lens elements according to claim 11 or 12, characterized in that for each ophthalmic lens element of the series of ophthalmic lens elements the upper viewing zone is sized to support a predetermined range of eye rotation for a distance vision task.

14. A progressive ophthalmic lens element comprising:

an upper viewing zone providing a first refractive power for distance vision, the first refractive power being in a range from flat to-4.00D; and

a peripheral region surrounding the upper viewing zone and providing a positive optical power relative to the first optical power throughout the region, the peripheral region including a lower viewing zone providing an optical power for near vision and a channel connecting the upper and lower viewing zones, the channel having a surface power that varies from a surface power of the upper viewing zone to a surface power of the lower viewing zone;

wherein the positive mean refractive power over all radial elongations greater than 20mm in the peripheral region for any radius from the geometric center of the lens element is at least 0.50D relative to the power of the far reference point of the upper viewing zone, and the distribution of positive mean refractive power throughout the peripheral region provides an optical correction for retarding or preventing myopia in the wearer.

15. A method of providing an ophthalmic lens element for retarding or preventing myopia of a wearer, the method comprising:

obtaining by the wearer:

a first optically corrected required value for the upper viewing zone that provides foveal vision for the on-axis vision task; and

a second optical correction required value which provides a contributing factor to the retardation or prevention of myopia in the peripheral region of the wearer's eye;

selecting or designing an ophthalmic lens element according to the values required for the first and second optical corrections, the ophthalmic lens element comprising:

a central region of low surface astigmatism, the central region comprising a first or upper viewing zone providing a first refractive power corresponding to a value required for a first optical correction; and

a peripheral region of positive mean refractive power relative to the first refractive power, the peripheral region surrounding the central region, the peripheral region comprising:

one or more regions of higher surface astigmatism than the central region;

a lower zone of low surface astigmatism for use in a wearer's near vision task; and

a channel of low surface astigmatism having a surface power that varies from the surface power of the upper viewing zone to the surface power of the lower viewing zone.

Wherein the peripheral region provides a distribution of positive mean powers corresponding to the value required for the second optical correction.