Progressive power lens and method for designing progressive power lens

Abstract

This progressive power lens comprises: a far-sight part suitable for far sight; a near-sight part which is disposed at a position different from that of the far-sight part and has a refractive power suitable for near sight; and a progressive part having a refractive power that continuously changes between the far-sight part and the near-sight part. A virtual far position is provided in a range above an eye point and below the far-sight part. Addition power at the virtual far position is corrected on the basis of an addition power ratio of the position of the eye point.

Description

Progressive power lens and design method for progressive power lens

[0001] The present invention relates to a progressive power lens and a design method for a progressive power lens. This application claims priority to Japanese Patent Application No. 2023-214802, filed on December 20, 2023, the contents of which are incorporated herein by reference.

[0002] Intermediate-near lenses are lenses that increase the add power around the eyepoint on the lens, widening the range of vision for intermediate to near distances compared to near-distance progressive lenses. Because intermediate-near lenses have a high add power at the eyepoint, the distance prescription is positioned at the top, farther away, to smooth out the change in add power. A lens prescription is made up of a distance prescription and an add power based on the distance prescription. Therefore, the distance prescription is positioned at the center of the lens and far from the eyepoint. As a result, when optimizing the lens, performance near the center, which is frequently used, can deteriorate.

[0003] JP 2015-87439 A

[0004] One aspect of the present invention is a progressive power lens comprising a distance portion suitable for distance vision, a near portion located at a position different from the distance portion and having refractive power suitable for near vision, and a progressive portion in which refractive power changes continuously between the distance portion and the near portion, wherein a virtual distance position is located in a range above the eye point and below the distance portion, and the addition power at the virtual distance position is corrected based on the addition power ratio of the position of the eye point.

[0005] One aspect of the present invention is a method for designing a progressive addition lens having a distance portion suitable for distance vision, a near portion located at a position different from the distance portion and having refractive power suitable for near vision, and a progressive portion in which refractive power changes continuously between the distance portion and the near portion, the method comprising the steps of: acquiring the addition power of the wearer's distance prescription; acquiring the addition power ratio at the position of the eye point; and correcting the addition power at a virtual distance position located in a range above the eye point and below the distance portion based on the addition power ratio at the position of the eye point.

[0006] 1 is a diagram showing an example of a progressive power lens according to an embodiment; FIG. 2 is a diagram showing an example of an addition power curve of a progressive power lens according to an embodiment; FIG. 3 is a diagram showing an example of an addition power at a virtual distance position according to an embodiment; FIG. 4 is a diagram showing an example of a contour map of residual aberration according to an embodiment; FIG. 5 is a diagram showing an example of an addition power curve when an ordered eyepoint addition power ratio is 15% according to an embodiment; FIG. 6 is a diagram showing an example of an addition power curve when an ordered eyepoint addition power ratio is 25% according to an embodiment; FIG. 7 is a diagram showing an example of an addition power curve when an ordered eyepoint addition power ratio is 40% according to an embodiment;

[0007] (Embodiments) A first embodiment will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing an example of a progressive power lens 1 according to this embodiment. In FIG. 1, the progressive power lens 1 is in a state before the lens is processed to fit the shape of an eyeglass frame (a state before edging). The progressive power lens 1 is formed into a circular or elliptical shape in a plan view, or in some cases into an edged shape. In FIG. 1, the upper side of the progressive power lens 1 is positioned upward when worn, and the lower side is positioned downward when worn.

[0008] The progressive power lens 1 includes a distance portion FR1, a near portion NR1, and a progressive portion MR1. The distance portion FR1 is located in the upper portion of the progressive power lens 1. After the progressive power lens 1 is processed for eyeglasses, the distance portion FR1 becomes a region suitable for distance vision. The near portion NR1 is located in the lower portion of the progressive power lens 1. After the progressive power lens 1 is processed for eyeglasses, the near portion NR1 becomes a region having refractive power corresponding to near vision. In other words, the near portion NR1 is located in a position different from the distance portion FR1 and is a region having refractive power suitable for near vision. The progressive portion MR1 is located between the distance portion FR1 and the near portion NR1. The progressive portion MR1 is a region in which refractive power changes continuously between the distance portion FR1 and the near portion NR1.

[0009] The distance portion FR1 is located at the top of the progressive power lens 1, and becomes a portion having a refractive power corresponding to a distant view after the progressive power lens 1 is processed for eyeglasses. The near portion NR1 is located at the bottom of the progressive power lens 1, and becomes a portion having a refractive power corresponding to a near view after the progressive power lens 1 is processed for eyeglasses. The progressive portion MR1 is a portion that connects the distance portion FR1 and the near portion NR1 by continuously and smoothly changing the refractive power between them.

[0010] A main gaze line M1 is located approximately in the center of the progressive power lens 1. The main gaze line M1 is an imaginary line on the lens through which the wearer's line of sight passes when looking at an object located below the front from above, and moves inward as the wearer approaches a near object due to convergence associated with the near vision response.

[0011] The progressive addition lens 1 has a plurality of reference points on the main line of gaze M1. The reference points of the progressive addition lens 1 include, for example, a virtual distance position FF1, an eyepoint IP1, and a near measurement position NF1. The virtual distance position FF1, the eyepoint IP1, and the near measurement position NF1 are arranged in this order from top to bottom on the main line of gaze M1. The eyepoint IP1 serves as a reference point when the wearer wears the progressive addition lens 1.

[0012] The virtual distance position FF1 is the same as the distance measurement position of a progressive-power lens. The distance measurement position of a conventional progressive-power lens will now be described with reference to FIG.

[0013] 9 is a diagram showing an example of a prior art progressive-power lens 10. The progressive-power lens 10 includes a distance portion FR10, a near portion NR10, and a progressive portion MR10. A main gaze line M10 is provided at approximately the center of the progressive-power lens 10. The progressive-power lens 10 has a plurality of reference points on the main gaze line M10. The reference points of the progressive-power lens 10 include a distance measurement position FF10, an eyepoint IP10, and a near measurement position NF10. The distance measurement position FF10, the eyepoint IP10, and the near measurement position NF10 are arranged in this order from top to bottom on the main gaze line M10.

[0014] The near progressive addition lens 10 is a lens that is in focus from infinity to near working distances. In the near progressive addition lens 10, the prescription position at which the focus is at infinity is not the eyepoint IP10, but the distance measurement position FF10, which is located above the eyepoint IP10. In the near progressive addition lens 10, as an example, the distance measurement position FF10 is located in a range of 4 mm to 8 mm above the eyepoint IP10. The addition power of the near progressive addition lens 10 is, as an example, 2.00 diopters. FIG. 10 shows the addition power curve of the near progressive addition lens 10. As shown in FIG. 10, in the near progressive addition lens 10, the addition power in the distance portion FR10 is zero.

[0015] 1, the description of the progressive-power lens 1 will continue. The virtual distance position FF1 is the same position as the distance measurement position FF10 of the progressive-power lens 10 according to the prior art described above, for example.

[0016] Also, as an example, the virtual distance position FF1 is provided in a range of 4 mm to 8 mm above the eyepoint IP1. Here, the distance measurement position of the progressive-power lens is included in a range above the eyepoint IP1 and below the distance portion FR1. Also, the range of 4 mm to 8 mm above the eyepoint IP1 is included in a range above the eyepoint IP1 and below the distance portion FR1. Therefore, in the progressive-power lens 1, the virtual distance position FF1 is provided in a range above the eyepoint IP1 and below the distance portion FR1.

[0017] Next, the addition curve of the progressive power lens 1 will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of the addition curve of the progressive power lens 1 according to this embodiment. In Fig. 2, "height" indicates the height of the progressive power lens 1 in the vertical direction when the eye point IP1 of the progressive power lens 1 is used as a reference. Here, the height corresponding to the eye point IP1 is 0 mm. Hereinafter, the height of the progressive power lens 1 in the vertical direction may be simply referred to as the height of the progressive power lens 1.

[0018] Here, when the wearer's distance prescription has a spherical prescription power Sph0, an astigmatism prescription power Cyl0, an astigmatism axis Ax0, and a prescription add power Add0, the eyepoint add power ratio (also referred to as an ordered eyepoint add power ratio) of the progressive power lens 1 to be ordered is set to Xep (%). The eyepoint add power ratio Xep has a value between 0% and 50%. For example, when Xep = 25%, if the prescription add power Add0 = 2.50 D, the add power at eyepoint IP1 is 2.50 x 0.25 = 0.625 D. The eyepoint add power ratio Xep can be determined depending on the product, and can also be directly input when ordering eyeglass lenses based on a value calculated based on the wearer's desired viewing distance in straight-on vision or lifestyle habits, etc.

[0019] For the prescription of the ordered lens, the powers of the progressive-power lens 1 at the virtual distance position FF1 are defined as a virtual distance spherical power Sph1, a virtual distance astigmatic power Cyl1, and a virtual distance astigmatic axis Ax1. The relationships of these virtual distance spherical power Sph1, virtual distance astigmatic power Cyl1, and virtual distance astigmatic axis Ax1 to the spherical prescription power Sph0, astigmatic prescription power Cyl0, and astigmatic axis Ax0 of the wearer's distance prescription are shown in equations (1), (2), and (3), respectively.

[0020]

[0021]

[0022]

[0023] As shown in formulas (2) and (3), the virtual distance astigmatic power Cyl1 and the virtual distance astigmatic axis Ax1 maintain the same values ​​as the prescribed powers, while a plus power Add1 is added to the virtual distance spherical power Sph1 as shown in formula (1). The plus power Add1 is expressed by formula (4).

[0024]

[0025] The value of the addition power ratio X0 is in the range of 10% to 20%. The addition power ratio X0 is determined by the design boundary between the near-far progressive power lens and the intermediate-near progressive power lens. The addition power ratio X0 means the maximum addition power ratio at which the power required to see infinity at the distance position is obtained. In other words, the addition power ratio X0 means the maximum addition power ratio in the near-far progressive power lens. Note that if the value of the eyepoint addition power ratio Xep is smaller than the value of the addition power ratio X0, the value of the plus power Add1 in equation (4) is set to 0. The value of the parameter α is in the range of 0.15 to 0.25. The parameter α is a parameter for determining the ratio of addition power at the virtual distance position FF1. The parameter α is set so that the addition power at the virtual distance position FF1 is the same as that of an existing intermediate-near progressive power lens so that there is no sense of incongruity when replacing the lens with an existing intermediate-near progressive power lens.

[0026] According to formula (1), in the progressive power lens 1, the addition power at the virtual distance position FF1 is corrected based on the eyepoint addition power ratio Xep at the position of the eyepoint IP1. Figure 3 shows the addition power at the virtual distance position FF1. Figure 3 shows the addition power at the virtual distance position FF1 relative to the eyepoint addition power ratio Xep at the position of the eyepoint IP1.

[0027] As described above, in the progressive-power lens 1, the virtual distance position FF1 is provided in a range above the eyepoint IP1 and below the distance portion FR1. In the progressive-power lens 1, the change in addition power is equal to or less than a predetermined value in the range where the virtual distance position FF1 is provided. The value of the predetermined value can be set to, for example, ±0.12 D (diopters) or less.

[0028] In the progressive power lens 1, the power of the progressive power lens 1 is made as constant as possible with respect to changes in height at the virtual distance position FF1, as shown in the graph of the addition power curve in Fig. 2. In other words, making the power as constant as possible with respect to changes in height means making the graph of the addition power curve, where the horizontal axis is addition power and the vertical axis is height, as perpendicular as possible to the horizontal axis at the virtual distance position FF1. By making the addition power at the virtual distance position FF1 stable with changes in height, the range in which the vision of the distance assumed with that addition power is stable becomes wider, and the wearing comfort improves.

[0029] For comparison with the progressive power lens 1 according to this embodiment, a conventional intermediate-near progressive power lens 20 will be described. Fig. 11 is a diagram showing an example of the conventional intermediate-near progressive power lens 20.

[0030] The intermediate-near progressive power lens 20 includes a distance portion FR20, a near portion NR20, and a progressive portion MR20. A main line of gaze M20 is provided approximately in the center of the intermediate-near progressive power lens 20. The intermediate-near progressive power lens 20 has a plurality of reference points on the main line of gaze M20. The reference points of the intermediate-near progressive power lens 20 include a distance measurement position FF20, an eyepoint IP20, and a near measurement position NF20. The distance measurement position FF20, the eyepoint IP20, and the near measurement position NF20 are arranged in this order from top to bottom on the main line of gaze M20.

[0031] In the intermediate-near progressive power lens 20 according to the prior art, the distance measurement position FF20 is located at a position higher than that of the near-field progressive power lens 10 (see FIG. 9), and is determined by the addition power at the eye point IP20. Therefore, it is difficult to directly compare the intermediate-near progressive power lens 20 with a near-field progressive power lens (for example, the near-field progressive power lens 10) in terms of the range of vision for distance use.

[0032] The addition power of the intermediate-near progressive power lens 20 is 2.00 diopters, and the addition power ratio at eye point IP20 is 25%. Fig. 12 shows the addition power curve of the intermediate-near progressive power lens 20. As shown in Fig. 12, in the intermediate-near progressive power lens 20, the change in addition power is larger in the range of 4 mm to 8 mm above the eye point IP20 than the change in addition power of the progressive power lens 1 according to this embodiment (Fig. 2).

[0033] Furthermore, in the progressive-power lens 1, a position where the spherical equivalent power is the same as the distance prescription is provided above the virtual distance position FF1, thereby enabling the wearer of the progressive-power lens 1 to see farther than the distance set at the virtual distance position FF1.

[0034] Next, the residual aberration of the progressive power lens 1 will be described. Before describing the residual aberration of the progressive power lens 1, the residual aberration of a conventional intermediate-near progressive power lens 20 will be described for comparison. Fig. 13 is a diagram showing an example of a contour map P10 of the residual aberration of the conventional intermediate-near progressive power lens 20. The up-down direction of the contour map P10 in Fig. 13 coincides with the up-down direction in Fig. 11. In the contour map P10, the optimization reference position FP10 corresponds to the distance measurement position FF20 shown in Fig. 11.

[0035] In the intermediate / near progressive power lens 20 according to the conventional technology, optimization is performed based on the distance measurement position FF20 and the distance power. In the intermediate / near progressive power lens 20, residual aberration remains even after optimization, and the residual aberration becomes large particularly in prescriptions for strong myopia or strong hyperopia. The residual aberration tends to become large the further away from the position that serves as the reference for optimization. Therefore, when optimization is performed at the distance measurement position FF20 of the intermediate / near progressive power lens 20 according to the conventional technology, the residual aberration near the center of the lens, which is frequently used, may become large.

[0036] Fig. 4 is a diagram showing an example of a contour map P1 of residual aberrations according to this embodiment. The up-down direction of the contour map P1 in Fig. 4 coincides with the up-down direction in Fig. 1. In the contour map P1, the optimization reference position FP1 corresponds to the virtual distance position FF1 shown in Fig. 1.

[0037] As described above, in the progressive-power lens 1 according to this embodiment, the reference position for optimization is the virtual distance position FF1. The virtual distance position FF1 is closer to the eyepoint IP1 than the existing distance measurement position. Therefore, in the progressive-power lens 1, it is possible to suppress residual aberration in the region where the frequency of use is high.

[0038] 5 to 7 show examples of addition power curves for each ordered eyepoint addition power ratio. FIGS. 5, 6, and 7 are diagrams showing examples of addition power curves when the ordered eyepoint addition power ratios are 15%, 25%, and 40%, respectively. In FIGS. 5, 6, and 7, the addition power curve of a conventional intermediate / near progressive power lens 20 is superimposed on the progressive power lens 1 according to this embodiment for comparison. In the height range of approximately 0 mm to 6 mm, the addition power curve of the progressive power lens 1 is a downwardly convex curve and is located lower than the addition power curve of the intermediate / near progressive power lens 20. This ensures that the change in addition power is within a predetermined magnitude in the range where the virtual distance position FF1 is provided.

[0039] Next, a method for designing and manufacturing a progressive power lens 1 will be described with reference to Fig. 8 . Fig. 8 is a flowchart showing an example of a method for designing and manufacturing a progressive power lens 1 according to this embodiment. The design method shown in Fig. 8 is executed by a calculation device 2 (not shown). The manufacturing method shown in Fig. 8 is executed by a design device 3 (not shown). The calculation device 2 is a calculation device that calculates numerical values ​​related to the optical characteristics of the progressive power lens 1 based on information related to the progressive power lens 1 obtained by input from a user of the calculation device 2 or by communication, etc. Here, the user of the calculation device 2 (hereinafter simply referred to as the user) refers to a person who operates the calculation device 2, and includes, for example, a wearer of eyeglass lenses such as a customer visiting an eyeglass retailer, and a salesperson at the eyeglass retailer.

[0040] Step S10: The calculation device 2 acquires the prescription data of the wearer. The prescription data includes the spherical prescription power Sph0, the astigmatic prescription power Cyl0, the astigmatic axis Ax0, and the prescription addition power Add0 as the wearer's distance prescription. Therefore, the calculation device 2 acquires the addition power of the wearer's distance prescription.

[0041] Step S20: The calculation device 2 acquires the eyepoint add power ratio Xep at the eyepoint IP1. Here, the calculation device 2 calculates the eyepoint add power ratio Xep based on, for example, the distance at which the wearer desires to view in frontal vision, or a value calculated based on lifestyle habits, etc. The calculation device 2 may acquire the eyepoint add power ratio Xep input by the user from an input device.

[0042] Step S30: The calculation device 2 calculates the addition power at the eyepoint IP1. The calculation device 2 calculates the addition power at the eyepoint IP1 by multiplying the addition power included in the prescription data by the eyepoint addition power ratio Xep.

[0043] Step S40: The calculation device 2 calculates the addition power at the virtual distance position FF1. Here, the calculation device 2 calculates the virtual distance spherical power Sph1 at the virtual distance position FF1 by correcting the prescribed power based on the eyepoint addition power ratio Xep. The calculation device 2 corrects the virtual distance spherical power Sph1, for example, based on the above-mentioned formula (1). Therefore, the calculation device 2 corrects the addition power at the virtual distance position FF1, which is located in a range above the eyepoint IP1 and below the distance portion FR1, based on the addition power ratio at the position of the eyepoint IP1 (eyepoint addition power ratio Xep). The calculation device 2 calculates the virtual distance astigmatism power Cyl1 and the virtual distance astigmatism axis Ax1 to be the same values ​​as the prescribed power.

[0044] Step S50: The design device 3 acquires eyeglass lens design information. Here, the eyeglass lens design information includes the calculated virtual distance spherical power Sph1, virtual distance astigmatism power Cyl1, and virtual distance astigmatism axis Ax1 at the virtual distance position FF1, the addition power at the near measurement position NF1, the addition power at the eyepoint IP1, and information about the frame, etc. The eyeglass lens design information is transmitted to the design device 3 from, for example, an eyeglass store via an eyeglass lens ordering device and an eyeglass lens order receiving device (not shown).

[0045] Step S60: Based on the acquired eyeglass lens design information, the design device 3 designs each portion of the progressive power lens 1 so that the refractive power is continuously connected. Step S70: An eyeglass lens processing device (not shown) manufactures the designed progressive power lens 1. This completes the method for designing and manufacturing the progressive power lens 1.

[0046] As described above, the progressive-power lens 1 according to this embodiment includes a distance portion FR1 suitable for distance vision, a near portion NR1 located at a position different from the distance portion FR1 and having a refractive power suitable for near vision, and a progressive portion MR1 in which the refractive power changes continuously between the distance portion FR1 and the near portion NR1. In the progressive-power lens 1 according to this embodiment, a virtual distance position FF1 is provided in a range above the eyepoint IP1 and below the distance portion FR1, and the addition power at the virtual distance position FF1 is corrected based on the addition power ratio at the position of the eyepoint IP1 (in this embodiment, the eyepoint addition power ratio Xep).

[0047] With this configuration, in the progressive power lens 1 according to this embodiment, the distance visible in the distance portion FR1 can be directly compared with the addition power at the virtual distance position FF1, which makes it easier for the wearer to understand when deciding on the design type of the spectacle lens. The design type is the addition power ratio at the eyepoint.

[0048] A program for implementing the functions of any of the components of any of the above-described devices may be recorded on a computer-readable recording medium and then loaded and executed by a computer system. The term "computer system" as used herein includes hardware such as an operating system or peripheral devices. Furthermore, "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and compact disc (CD)-read-only memories (ROMs), as well as storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording medium" also includes devices that retain a program for a certain period of time, such as volatile memory within a computer system that acts as a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. Such volatile memory may be, for example, random access memory (RAM). The recording medium may also be, for example, a non-transitory recording medium.

[0049] The above program may also be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by transmission waves in the transmission medium. Here, the "transmission medium" that transmits the program refers to a medium that has the function of transmitting information, such as a network such as the Internet or a communication line such as a telephone line. The above program may also be intended to realize part of the above-mentioned functions. Furthermore, the above program may be a so-called differential file that can realize the above-mentioned functions in combination with a program already recorded in the computer system. A differential file may also be called a differential program.

[0050] Furthermore, the functions of any of the components in any of the above-described devices may be implemented by a processor. For example, each process in the embodiments may be implemented by a processor that operates based on information such as a program and a computer-readable recording medium that stores information such as the program. Here, the functions of each unit of the processor may be implemented by, for example, individual hardware, or may be implemented by integrated hardware. For example, the processor may include hardware, and the hardware may include at least one of a circuit for processing digital signals and a circuit for processing analog signals. For example, the processor may be configured using one or more circuit devices mounted on a circuit board, or one or both of one or more circuit elements. An integrated circuit (IC) or the like may be used as the circuit device, and a resistor or a capacitor may be used as the circuit element.

[0051] Here, the processor may be, for example, a CPU. However, the processor is not limited to a CPU, and various types of processors, such as a GPU (Graphics Processing Unit) or a DSP (Digital Signal Processor), may be used. The processor may also be, for example, a hardware circuit such as an ASIC (Application Specific Integrated Circuit). The processor may also be, for example, composed of multiple CPUs, or may also be composed of a hardware circuit such as multiple ASICs. The processor may also be, for example, composed of a combination of multiple CPUs and a hardware circuit such as multiple ASICs. The processor may also include, for example, one or more of an amplifier circuit or a filter circuit that processes analog signals.

[0052] One embodiment of the present invention has been described in detail above with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes and the like are possible within the scope that does not deviate from the gist of the present invention.

[0053] 1...progressive power lens, FR1...distance portion, NR1...near portion, MR1...progressive portion, FF1...virtual distance position, IP1...eye point, NF1...near measurement position

Claims

1. A progressive power lens comprising a distance portion suitable for far vision, a near portion located at a position different from the distance portion and having refractive power suitable for near vision, and a progressive portion in which refractive power changes continuously between the distance portion and the near portion, wherein a virtual distance position is located in a range above the eye point and below the distance portion, and the addition power at the virtual distance position is corrected based on the addition power ratio at the position of the eye point.

2. The progressive power lens according to claim 1, wherein the change in addition power within the range is equal to or less than a predetermined value.

3. The progressive power lens according to claim 1, wherein the virtual distance position is set in a range of 4 mm to 8 mm above the eye point.

4. The progressive power lens according to claim 1, wherein the virtual distance position is the same as a distance measurement position of a near-far progressive power lens.

5. The progressive power lens according to claim 1, wherein a position where the spherical equivalent power is the same as the distance prescription is provided above the virtual distance position.

6. A method for designing a progressive addition lens having a distance portion suitable for distance vision, a near portion located at a position different from the distance portion and having a refractive power suitable for near vision, and a progressive portion in which the refractive power changes continuously between the distance portion and the near portion, the method comprising: acquiring the add power of a wearer's distance prescription; acquiring an add power ratio at the position of the eye point; and correcting the add power at a virtual distance position located in a range above the eye point and below the distance portion based on the add power ratio at the position of the eye point.

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