WO2012007064A1

WO2012007064A1 - Retardation of progression of refractive error

Info

Publication number: WO2012007064A1
Application number: PCT/EP2010/064568
Authority: WO
Inventors: Herbert Krug; Timo Kratzer
Original assignee: Carl Zeiss Vision Gmbh
Priority date: 2010-07-16
Filing date: 2010-09-30
Publication date: 2012-01-19

Abstract

A method for designing an ophthalmic lens includes obtaining a refraction for a foveal vision of the eye; obtaining at least one refraction for a peripheral vision of the eye; and designing the ophthalmic lens so that it includes a first portion that provides a correction for the foveal vision and a second portion that provides a correction for the peripheral vision.

Description

RETARDATION OF PROGRESSION OF PROGRESSION OF REFRACTIVE ERRROR

This application claims priority to Provisional Patent Application No, 61/364,904, entitled "RETARDATION OF PROGRESSION OF REFRACTIVE ERROR," filed on July 16, 2010. the entire contents of which are incorporated herein by reference,

BACKGROUND

A means of arresting or retarding the progress of refractive error would provide enormous benefits to the millions of people who will be disadvantaged by increasing refractive error. To date, treatment strategies for myopia for example that have manipulated the effective focus of the eye for central vision (e.g., hi- locals or progressive lenses) have not been able to demonstrate a clinically significant effect in retarding the progression of myopia for all affected myopes. These previous efforts have implicitly assumed that eye growth is dominated by visual feedback associated with central vision and that, by further implication, vision-dependant mechanisms located in the center of the retina (i.e., fovea of the eye) control refractive development.

Conventional (single- vision) ophthalmic lenses are calculated to have the best optical performance in the central part of the retina (i.e., for foveal vision). Off-axis blur and perceptibility (e.g., peripheral vision) are not generally taken into account when making the lenses. In addition, most spectacles lenses are not large enough to have significant influence on the off-axis optical performance. Highly curved lenses are used for sport purposes (e.g., wind shield or shading), but these are not designed to have a positive influence on the off-axis optical performance.

SUMMARY

Recent research suggests that the off-axis focal length properties (e.g., peripheral vision) of the eye often differ from the axial and paraxial lengths. Further, it is believed that there is a benefit of higlily curved lenses in identifying off-axis objects with highly curved lenses compared to conventional non-curved lenses. In addition, highly curved lenses show a better performance in identifying off-axis objects. One can conclude that with highly curved lenses off-axis objects look sharper than with standard lenses, otherwise the performance in identifying off-axis objects would he the same,

The recently launched wavefront optimized lenses like LScription® (from Carl

Zeiss Vision) allow a better optical correction with spectacles. They achieve sharper pictures (e.g., smaller point spread functions) on the entire retina and increase the contrast sensitivity.

Embodiments of ophthalmic lenses are disclosed that combine the sharpest possible picture on the retina (e.g., where the prescription ("Rx") is determined from a wavefront measurement over the whole field of view with latest wavefront optimization technologies) and the lowest possible blur over the whole field of view (e.g.. with highly curved lenses). It is believed that such ophthalmic lenses may reduce progression of refractive error.

In some embodiments, a wavefront measurement of the central vision is made and used to optimize a highly curved lens to have the lowest available blur on corresponding areas on the retina over the whole field of view. In other words, the highly curved lens provides correction for both the fovea! vision and peripheral vision based on the wavefront measurement,

hi certain embodiments, several wavefront measurements are performed in various directions of gaze over the whole field of view. Every part of the highly curved lens is then optimized with the wavefront measurement in this direction to have the lowest blur on corresponding points on the retina. Alternatively, or additionally, a subjective refractive can be performed in one or more of the various directions to establish an Rx for foveal and peripheral vision.

Various aspects of the invention are summarized as follows.

In general, in one aspect, the invention features a method for designing an ophthalmic lens, including obtaining a refraction for a foveal vision of the eye; obtaining at least, one refraction for a peripheral vision of the eye; and designing the ophthalmic lens so that it includes a first portion that provides a correction for the foveal vision, and a second portion that provides a correction for the peripheral vision. implementations of the method can include one or more of the following features. For example, obtaining the at least one refraction for the peripheral vision can include obtaining multiple refractions each for a along a different vision direction. The different vision directions can include a direction in a horizontal viewing plane of the eye and a direction in a vertical viewing plane of the eye. At least one refraction for the peripheral vision can correspond to the peripheral vision in a horizontal viewing plane of the eye.

The at least one refraction for the peripheral vision can correspond to the peripheral vision in a vertical viewing plane of the eye.

At least one of the refractions can be obtained using a wavefront sensor.

At least one of the refractions can account for second order aberrations of the eye and for higher order aberrations of the eye.

At least one of the refractions can be obtained using a method that includes mathematically varying a preliminary prescription within a target space to determine die ophthalmic lens prescription, wherein mathematically varying the preliminary prescription comprises using an electronic processor to calculate, for each of multiple sets of parameter values, a value of a metric related to a caustic of a light ray passing through a corrective optic and the eye, each set of parameter val ues corresponding to a different prescription of a corrective optic, and the ophthalmic lens prescription is selected as the prescription for which the caustic meets predetermined requirements in an area of the retina of the eye.

At least one of the refractions is obtained using an autorefracior. At least one of the refractions can be obtained using a subjective refraction.

The foveal vision can correspond to vision of the eye within a cone of angles subtending a half-cone angle of 10 degrees or less (e.g., 9 degrees or less, 8 degrees or less). The foveal vision can correspond to vision of the eye within a cone of angles subtending a half-cone angle of 7 degrees or less (e.g., 6 degrees or less, 5 degrees or less, 4 degrees or less).

The peripheral vision can correspond to vision of the eye along directions outside of a cone of angles subtending a half-cone angle of 30 degrees or more (e.g., 35 degrees or more). In some embodiments, the peripheral vision corresponds to vision of the eye along directions outside of a cone of angles subtending a half-cone angle of 40 degrees or more (e.g., 45 degrees or more, 50 degrees or more, 55 degrees or more, 60 degrees or more).

The method can include making an ophthalmic lens based on the design, in general, in another aspect, the invention features an ophthalmic lens, including a first portion designed to provide a correction for a foveal vision of a patient's eye; and a second portion designed to provide a correction for a peripheral vision of the patient's eye.

Embodiments of the ophthalmic lens can include one or more of the following features and/or features of other aspects. The ophthalmic lens can be produced according to the foregoing method. The ophthalmic lens can include one or more additional portions each designed to provide a correction for the peripheral vision of the patient's eye along different directions. The lens can be a highly curved lens.

hi general, in another aspect, the invention features a pair of eyeglasses, including a first lens according to the foregoing aspect, the first and second portions of the first lens being designed to provide a correction for the foveal and peripheral vision, respectively, of a left eye of a patient; and a second lens according to the foregoing aspect, the first and second portions of the second lens being designed to provide a correction for the foveal and peripheral vision, respectively, of a right eye of the patient.

In general, in a further aspect, the invention features a method for retarding progression of refractive error of an eye, including providing the eye with an ophthalmic lens according to the foregoing aspects. The refractive error can include myopia and/or hyperopia.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 A is a perspective view of an embodiment of eyeglasses that include highly curved lenses.

FIG. IB is a perspective view of an embodiment of an ophthalmic lens.

FIG. !C is a top view of the ophthalmic lens shown in FIG, IB. FIG. 2A is a perspective view of another embodiment of an ophthalmic lens, FIG, 2B is a perspective view of another embodixnent of axi ophthalmic lens. FIG. 3 is a flowchart showing steps in a method for the production of eyeglasses containing highly-curved lenses.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Referring to FIGS. 1A-1C, a pair of eyeglasses 100 include frames 101 and ophthalmic lenses 110. Lenses 110 are highly-curved and include different zones 120 and 130, which are shaped to correct either for the eyeglass wearer's foveal vision or peripheral vision. A person's foveal vision corresponds to the field of view where 100% visual acuity can be achieved and includes lines of sight at the center of gaze. Peripheral vision is the part of a person's field of view outside of the foveal vision field, outside the center of gaze, Highly-curved lenses are bent lenses that wrap around part of the wearer's face between their eye and their ear providing an optical surface area that covers a significant portion (e.g., all) of the wearer's peripheral vision. It is believed that the use of such eyeglasses can retard progression of a wearer's refractive error that occurs as a person ages.

Zone 120 is the zone that covers the center of gaze (along direction 122) when the wearer looks straight ahead and is shaped based on a prescription ("Rx") for the wearer's foveal vision. Zone 130, corresponding to the wearer's peripheral vision when looking straight ahead, is shaped based on a Rx for the wearer's peripheral vision.

La general, the size and shape of zones 120 and 130 can vary as desired, depending on such factors as the size and curvature of the lenses (e.g., as dictated by the eyeglass frames shape), the difference between the wearer's foveal and peripheral Rx's, arid/or other considerations that may affect the wearer's vision.

A Cartesian co-ordinate system is shown in FIGS. IB and 1C, where the z-axis is parallel to direction 122. The horizontal viewing plane corresponds to the x-z plane. The vertical viewing plane corresponds to the y-z plane. Vision direction in the horizontal viewing plane is specified by an angle Θ. Typically, in the horizontal viewing plane, a person's foveal vision corresponds to Θ of about -10° to about +10°, with peripheral vision corresponding to values of Θ less than about -10° and greater than +10°. Of course, the exact range can vary from person to person.

While zones 120 and 130 are depicted as being circular in shape in FIG. IB, in general, the shape of zones can vary as desired. The shape of one zone can be the same or different as the shape of other zones. Zones can he circular, oval, polygonal, or irregular in shape. Typically, the shape of each zone is established based on the shape of the lens, the size of each zone, and the ability of the lens maker to form the a lens with the appropriate curvature and Rx's.

Zone 120 can border zone 130 (e.g., marked by a discontinuity in the lens surface curvature as the lens surface transitions between a different foveal vision Rx and peripherieal vision Rx), or there can be a transition area between these zones (e.g., characterized by a smoothly varying surface that corresponds to neither the foveal vision Rx or peripheral vision Rx).

In general, the size of the zones can vary as desired. Generally, the size of zone 120 encompasses to the angular viewing range for fovea! vision while the wearer looks straight ahead. The size of zone 120 may extend beyond this field of view to provide foveal vision correction where a person moves his/her eye to look in a direction away from straight ahead. In general, zone 120 subtends a solid angle δθ}20 in the horizontal viewing plane that is about 20° or less (e.g., 18° or less, 16° or less, 15° or less, 12° or less, 10° or less). Zone 120 can subtend a cone having a half-angle of 10° or less (e.g.. 9° or less, 8* or less, 7° or less, 6° or less, 5° or less, 4° or less).

Zone 120 also subtends a solid angle in the vertical viewing direct! on. in general, the solid angle that zone 120 subtends in the vertical viewing direction can be the same or different than δθ_120.

Zone 120 can subtend solid angles on either side of direction 120 that are the same or different, depending on the shape of the zone. For example, zone 120 can extend over a greater range of angles horizontally towards a person's ears compared to the range of angles it extends towards the person's nose- Zone 130 extends from an angle θ₁₃₀ in the horizontal viewing direction and subtends a solid angle δθ₁₃₀ in this plane. θ₁₃₀ can correspond to the angular position where zone 120 ends, or there can be a transition region from the angle at which zone 120 ends to θ_130· In some embodiments, θ₁₃₀ is about 15° or more (e.g., about 20° or more, about 25° or more, about 30° or more, about 35° or more, about 40° or more, about 45° or more, about 50° or more, about 55° or more, about 60° or more).

in general, δθ₁₃₀ can be the same or different than δθ₁₂₀. In some embodiments, δθ· 3ο is about 5° or more (e.g., about 8° or more, about 10° or more, about 12° or more about 15° or more, about 18° or more, about 20° or more). Zone 130 can extend to the end of lens 110 or can end at some position before the end of the lens.

Zone 130 also subtends a solid angle in the vertical viewing direction. In genera], the solid angle that zone 130 subtends in the vertical viewing direction can be the same or different than δθ₁₃₀.

While lens 1 10 has only two zones, lenses can, in general, have more zones than this. For example, in some embodiments, an ophthalmic lens has more than one zone for peripheral vision correction. Referring to FIG. 2 A, a lens 210 includes a zone 212 for fovea! vision correction, and additional zones 213-216, correcting peripheral vision. As discussed previously for zones 120 and 130. the size and shape of zones 212-216 can vary and adjacent zones can border one another or can be separated by a transitional region.

While the foregoing examples of ophthalmic lenses include different zones in a horizontal direction (i.e., in the plane of the wearer's eyes), other arrangements are also possible. Some lenses can include more than one zone in a vertical direction. For example, referring to FIG. 2B, an ophthalmic lens 220 includes zone 222, which provides fovea! vision correction, and zones 224 and 226, which provide peripheral vision, correction. In some embodiments, ophthalmic lenses include multiple zones in both horizontal and vertical directions.

Of course, while the examples of lenses described above are highly-curved lenses, peripheral vision zones can be provided in lenses having regular curvature as well. For example, in some embodiments, relatively small peripheral vision zones can be provided adjacent an foveal vision zone in a regular lens.

Turning now to the design and manufacture of the lenses and eyeglasses described abo ve, in general, a variety of methods can be used. Typically, the first step in making eyeglasses 100 is to obtain an Rx for each zone of each ophthalmic lens. This can be done by subjective refraction, wavefront refraction, or retinoseopy, and using any combination of conventional refractors (e.g., an autorefractor, a wavefront refractor, a retinoscope).

In some embodiments, the Rx for each zone is using the methods disclosed in U.S. Patent No. 7,744,217, the entire contents of which are incorporated herein by reference. For example, the Rx for each zone can be determined in a manner that takes into account the physiology of the eye in the calculation of a vision correction , based for example on a wavefront measurement of the eye. The procedure for determining the Rx for each zone can include mathematically varying a preliminary prescription within a target space or search space, which may or may not be known at the outset of the process. The preliminary prescription which is selected within the target space is that prescription for which the caustic of a light beam passing through a corrective optic (e.g., a lens or lenses) corresponding to the Rx and that satisfies specific given requirements in the retinal area of the eye. The term "caustic" in this context means the narrow constriction, that occurs instead of an image point as a result of imaging errors for a light bundle originating from an object point before it spreads out again. It is possible to vary the preliminary prescription until a criterion for terminating the process has been met. A termination criterion can for example be constituted by the attainment of an optimum or of a value that is very close to the optimum of a target criterion. The given requirements that are to be met may spell out that a metric describing the quality of the caustic has to exceed a certain threshold value or lie within a given range around an optimal value.

In general, the refraction for the foveal and peripheral vision zones can be performed in the same way. The Rx can account for second order aberrations alone or higher order aberrations in addition to the second order aberrations.

Once the Rx for each zone is established, an eye-care professional or lens maker designs the lenses based on the Rx's. Lens design can account for other vision factors, such as whether the eyeglasses will be used under special conditions (e.g., driving, computer work, bright daylight conditions), and physical constrain ts such as the frames the lenses are to be used in.

The lenses are then made based on the design using conventional lens making techniques. For example, the lenses can be ground from lens blanks in the same way as, for example, multi-vision lenses (e.g., bi-focal lenses or progressive lenses) are made. In some embodiments, free-form grinding can be used. In certain embodiments, the lenses can he molded.

Conventional lens materials can be used. For example, lenses can be made from glass (e.g., optical crown glass) or plastic (e.g., CR-39, Trivex, polycarbonate, polyurethanes).

The lenses can include any variety of conventional optical coatings or materials, such as hard coats, UV protective coatings, anti-reflection coatings, smudge resistant coatings, photochromic materials, etc.

Referring to the flow chart 300 shown in FIG. 3, in some embodiments, the eyeglasses for a patient are made as follows. First, an eye-care professional obtains an Rx for the fovea! vision of each of the patient's eyes (step 310). Next, the eye-care professional obtains an Rx for each of one or more vision directions corresponding to the peripheral vision of each eye (step 320). Based on these Rx's, an eye-care professional or lens maker designs ophthalmic lenses so that they include zones corresponding to each Rx determined in steps 3.10 and 320 (step 330). Finally, a lens-maker makes the ophthalmic lenses based on the designs (step 340) and assembles the lenses in a frame to provide the eyeglasses.

Other embodiments are in the following claims,

Claims

WHAT IS CLAIMED IS:

1. A method for designing an ophthalmic lens, comprising:

obtaining a refraction for a foveal vision of the eye;

obtaining at least one refraction for a peripheral vision of the eye; and designing the ophthalmic lens so thai it includes a first portion that provides a correction for the fovea! vision and a second portion that provides a correction for the peripheral vision,

2. The method of claim 1 , wherein obtaining the at least one retraction for the

peripheral vision comprises obtaining multiple refractions each for a along a different vision direction.

3. The method of claim 2, wherein the different vision directions comprise a

direction in a horizontal viewing plane of the eye and a direction in a vertical viewing plane of the eye,

4. The method of claim I, wherein the at least one refraction for the peripheral vision corresponds to the peripheral vision in a horizontal viewing plane of the eye.

5. The method of claim 1, wherein the at least, one refraction for the peripheral vision corresponds to the peripheral vision in a vertical viewing plane of the eye.

6. The method of claim 1 , wherein at least one of the refractions is obtained using a wavefront sensor.

7. The method of claim 1 , wherein at least one of the refractions accounts for second order aberrations of the eye and for higher order aberrations of the eye.

8. The method of claim 1, wherein at least one of the refractions is obtained using a method comprising mathematically varying a preliminary prescription within a target space to detexinine the ophthalmic lens prescription, wherein

mathematically varying the preliminary prescription comprises using an electronic processor to calculate, for each of m ultiple sets of parameter values, a value of a metric related to a caustic of a light ray passing through a corrective optic and the eye, each set of parameter values corresponding to a different prescription of a corrective optic, and the ophthalmic lens prescription is selected as the prescription for which the caustic meets predetermined requirements hi an area of the retina of the eye.

9. The method of claim 1, wherein at least one of the refractions is obtained using an autorefraetor.

10. The method of claim 1, wherein at least one of the refractions is obtained using a subjective refraction,

11. The method of claim 1, wherein the foveal vision corresponds to vision of the eye within a cone of angles subtending a half-cone angle of 10 degrees or less,

12. The method of claim 1, wherein the foveal vision corresponds to vision of the eye within a cone of angles subtending a half-cone angle of 7 degrees or less.

13. The method of claim 1 , wherein the peripheral vision corresponds to vision of the eye along directions outside of a cone of angles subtending a half-cone angle of 30 degrees or more.

14. The method of claim 1, wherein the peripheral vision corresponds to vision of the eye along directions outside of a cone of angles subtending a half-cone angle of 40 degrees or more.

15. The method of claim 1, further comprising making an ophthalmic lens based on the design.

16. An ophthalmic lens, comprising:

a first portion designed to provide a correction for a foveal vision of a patient's eye; and a second portion designed to provide a correction for a peripheral vision of the patient's eye.

17. The ophthalmic lens of claim 16, further comprising one or more additiorsal

portions each designed to provide a correction for the peripheral vision of the patient's eye along different directions.

18. The ophthalmic lens of claim .16, wherein the lens is a highly curved lens,

19. A pair of eyeglasses, comprising:

a first lens according to claim 16, the first and second portions of the first lens being designed to provide a correction for the fovea! and peripheral vision, respectively, of a left eye of a patient; and

a second lens according to claim 16, the first and second portions of the second lens being designed to provide a correction for the fovea! and peripheral vision, respectively, of a right eye of the patient.

20. A method for retarding progression of refractive error of an eye, comprising: providing the eye with an ophthalmic lens according to claim 16.

21. The method of claim 20, wherein the refractive error comprises myopia.

22. The method of claim 20. wherein the refractive error comprises hyperopia,