Contrast evaluation method, eyeglass lens design method, and contrast evaluation device

Abstract

This contrast evaluation method for an eyeglass lens includes: acquiring an eyeball model, created on the basis of a prescription of the eyeglass lens, and a contrast binocular addition model indicating a contrast recognized in binocular vision; acquiring coordinate information about a plurality of index points set in a three-dimensional space based on the midway point between the corneal apex of the left eye and the corneal apex of the right eye of the eyeball model; calculating a left eye contrast value and a right eye contrast value for each index point, by tracing a ray that reaches the retina of the eyeball model from the index point via the eyeglass lens, on the basis of the eyeball model and the coordinate information about the index points; and calculating a binocular addition contrast value for each index point on the basis of the calculated left eye contrast value and right eye contrast value and the contrast binocular addition model.

Description

Contrast Evaluation Method, Method for Designing Eyeglass Lenses, and Contrast Evaluation Apparatus

[0001] The present invention relates to a contrast evaluation method, a method for designing eyeglass lenses, and a contrast evaluation apparatus. This application claims priority based on Japanese Patent Application No. 2024-228603 filed on December 25, 2024, and incorporates the contents thereof herein by reference.

[0002] Generally, binocular vision has an effect called binocular summation (binocular addition), and it is said that the contrast sensitivity and visual acuity increase compared to monocular vision. In the design of eyeglass lenses, particularly progressive power lenses, in the distance vision area, by overlapping the ranges where both eyes can see clearly (the ranges with small aberrations), objects can be seen more clearly with both eyes. For example, in Patent Document 1, the performance of binocular vision is improved by optimizing one lens according to the optical performance of the other.

[0003] International Publication No. 2012 / 014810

[0004] One aspect of the present invention is to obtain an eyeball model created based on a prescription of an eyeglass lens and a contrast binocular addition model showing the contrast recognized in binocular vision, to obtain coordinate information of a plurality of index points set in a three-dimensional space based on the center point between the corneal apex of the left eye and the corneal apex of the right eye of the eyeball model, and based on the eyeball model and the coordinate information of the index points, calculate left-eye contrast values and right-eye contrast values for each of the index points by ray tracing from the index points through the eyeglass lens to the retina of the eyeball model, and calculate binocular addition contrast values for each of the index points based on the calculated left-eye contrast values and right-eye contrast values and the contrast binocular addition model. This is a contrast evaluation method for eyeglass lenses.

[0005] One aspect of the present invention is a method for designing eyeglass lenses in which the design values of the power and aberration of each lens are arranged asymmetrically between the ear side and the nose side of each lens by evaluating the binocular addition contrast values of the left-eye lens and the right-eye lens using the above-described contrast evaluation method for eyeglass lenses.

[0006] One aspect of the present invention is a contrast evaluation device for eyeglass lenses, comprising: a model acquisition unit that acquires an eyeball model created based on the prescription of eyeglass lenses and a binocular contrast addition model that shows the contrast recognized in binocular vision; a coordinate information acquisition unit that acquires coordinate information of a plurality of indicator points set in a three-dimensional space based on the center point between the corneal vertex of the left eye and the corneal vertex of the right eye of the eyeball model; a monocular contrast value calculation unit that calculates left eye contrast values ​​and right eye contrast values ​​for each indicator point by tracing light rays that reach the retina of the eyeball model from the indicator points through the eyeglass lenses, based on the eyeball model and the coordinate information of the indicator points; and a binocular addition contrast value calculation unit that calculates a binocular addition contrast value for each indicator point based on the calculated left eye contrast values ​​and right eye contrast values ​​and the binocular contrast addition model.

[0007] This figure shows an example of the apparatus configuration of the eyeglass lens manufacturing system of this embodiment. This figure shows the flow of the eyeglass lens design method and eyeglass lens manufacturing method, including the eyeglass lens evaluation method of this embodiment. This figure shows an example of the configuration of indicator points of this embodiment. This figure shows an example of the configuration of multiple indicator points of this embodiment. This figure shows a modified example of the configuration of multiple indicator points of this embodiment. This figure shows an example of ray tracing for calculating the monocular contrast value of this embodiment. This figure schematically shows the monocular contrast value of this embodiment. This figure shows an example of eyeglass lens design that emphasizes suppression of astigmatism. This figure shows an example of eyeglass lens design that emphasizes suppression of spherical power error. This figure shows an example of the contrast value distribution at close range. This figure shows an example of the contrast value distribution at long range. This is an example of an eyeglass lens designed with different optimization targets on the temporal and nasal sides of the lens. This shows an example of the distribution of astigmatism in an asymmetrically designed eyeglass lens. This shows an example of the evaluation result of the contrast of one eye (close range) in an asymmetrically designed eyeglass lens. This shows an example of the evaluation result of the contrast of one eye (long range) in an asymmetrically designed eyeglass lens. This shows an example of the evaluation result of the contrast of both eyes (close range) in an asymmetrically designed eyeglass lens. This shows an example of the evaluation results (at long distance) of binocular contrast in asymmetrically designed eyeglass lenses. This figure shows an example of the design of an asymmetrically designed eyeglass lens considering the difference in magnification between the two eyes. This figure shows an example of the difference in magnification between the two eyes in an asymmetrically designed eyeglass lens. This figure shows an example of the calculation results of binocular contrast. This figure shows an example of the design results of the aberration balance in the distance vision portion of a progressive focal lens.

[0008] The eyeglass lens manufacturing system 1 of this embodiment will be described with reference to the drawings. The embodiments described below are merely examples, and the embodiments to which the present invention is applied are not limited to the embodiments described below. In all the figures used to describe the embodiments, components having the same function will be given the same reference numerals, and repeated explanations will be omitted.

[0009] [Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a diagram showing an example of the apparatus configuration of the eyeglass lens manufacturing system 1 of this embodiment.

[0010] The eyeglass lens manufacturing system 1 comprises an eyeglass lens evaluation device 10, a storage device 20, a processing machine control device 30, and an eyeglass lens processing machine 40. The eyeglass lens evaluation device 10 comprises a calculation unit 100, an input unit 130, a display unit 140, and a storage unit 150.

[0011] The arithmetic unit 100 is equipped with a central processing unit (CPU) and operates based on programs and data stored in the storage unit 150, providing various functions. The functions of the arithmetic unit 100 may be distributed across multiple devices, and the system may be configured to process information as a single unit while communicating information between the devices.

[0012] The storage unit 150 is composed of, for example, a non-volatile storage device such as a hard disk drive or semiconductor memory (flash memory, RAM, ROM), and stores various types of information, such as programs and data that the arithmetic unit 100 reads.

[0013] The memory unit 150 may be implemented by a virtual storage device such as a cloud server located outside the eyeglass lens manufacturing system 1.

[0014] The input unit 130 is comprised of an input device such as a keyboard and accepts input data necessary for processing in the calculation unit 100, such as the wearer's age, prescription data, frame shape, and data related to accommodation and convergence, such as convergent accommodation and accommodative convergence. The input unit 130 outputs the input data to the calculation unit 100 and also outputs it to the storage unit 150, which will be described later, for storage. The input unit 130 may also be equipped with a communication unit or the like and may be configured to accept input data by acquiring input data prepared in advance by another device.

[0015] The display unit 140 is composed of a device capable of displaying images such as a liquid crystal monitor, and displays various numerical values ​​such as input prescription data, evaluation results of the eyeglass lens 6, and design data of the eyeglass lens 6 based on those evaluation results.

[0016] The calculation unit 100 includes, as its functional units, an eyeglass lens design unit 110 and a contrast evaluation unit 120.

[0017] The spectacle lens design unit 110 designs the spectacle lens 6 based on prescription data input from the input unit 130 and / or evaluation results from the contrast evaluation unit 120. Note that part or all of the design of the spectacle lens 6 may be performed by an external design device to the spectacle lens evaluation device 10. Furthermore, the type of spectacle lens 6 is not particularly limited and can be set to any type of spectacle lens, such as a progressive power lens.

[0018] The contrast evaluation unit 120 evaluates the contrast when the wearer views an object at a predetermined distance and in a predetermined direction through the eyeglass lens 6. The contrast evaluation unit 120 includes, as its functional units, a model acquisition unit 121, a coordinate information acquisition unit 122, a monocular contrast value calculation unit 123, and a binocular additive contrast calculation unit 124 (binocular additive contrast value calculation unit).

[0019] The storage device 20 is configured, for example, as a cloud server, and stores various data such as the evaluation results of the eyeglass lens 6 and the design data of the eyeglass lens 6 based on those evaluation results.

[0020] The processing machine control device 30 controls the spectacle lens processing machine 40 based on the design data of the spectacle lens 6 transmitted from the spectacle lens evaluation device 10. The spectacle lens processing machine 40 manufactures the spectacle lens 6 based on the control of the processing machine control device 30.

[0021] Figure 2 is a diagram showing the flow of a method for designing eyeglass lenses and a method for manufacturing eyeglass lenses, including a method for evaluating eyeglass lenses according to this embodiment.

[0022] In step S1001, the input unit 130 receives input such as the wearer's age, prescription data and frame shape of the spectacle lenses 6, and data related to accommodation and convergence. The prescription data includes the spherical power, astigmatism power and astigmatism axis of the prescribed spectacle lenses 6, as well as the wearer's interpupillary distance, and if the prescribed spectacle lenses are progressive lenses, it also includes the add power, etc. The input prescription data is output to the spectacle lens design unit 110 of the calculation unit 100. The prescription data may also include the wearer's visual acuity information. The prescription data for the spectacle lenses 6 is also called spectacle lens prescription information D1. When step S1001 is completed, the process proceeds to step S1003.

[0023] In step S1003, the spectacle lens design unit 110 provisionally designs the spectacle lens 6 based on the input prescription data and frame shape. Based on the spherical power, astigmatism power and astigmatism axis of the prescription data, and the interpupillary distance of the wearer, the spectacle lens design unit 110 determines the shape, refractive index, power distribution on the side of the object and the side of the eyeball, and astigmatism distribution of the spectacle lens 6. Once step S1003 is completed, the process proceeds to step S1005.

[0024] In step S1005, the spectacle lens 6, which was provisionally designed in step S1003, is evaluated based on the contrast perceived by the wearer.

[0025] In step S1007, the calculation unit 100 determines whether the evaluation of the provisionally designed eyeglass lens 6 is above a predetermined standard. The calculation unit 100 incorporates the contrast calculated in step S1005 into a function (evaluation function) for evaluating the eyeglass lens during the optimization design process, and uses this evaluation function to evaluate and design the eyeglass lens. If the contrast value, or the parameters derived based on that contrast, satisfies predetermined conditions, the calculation unit 100 makes a positive determination in step S1007 and proceeds to step S1009. If the predetermined conditions are not met, the calculation unit 100 makes a negative determination in step S1007 and returns to step S1003 to redesign. Here, the predetermined conditions are set as appropriate, for example, the contrast value for the distance and / or direction that the wearer commonly looks at on a daily basis. For example, the spatial frequency of an object is determined by distance and direction, and the ratio of the region exceeding the contrast value at that time is used as a design condition. Alternatively, the system may be configured so that the wearer or a salesperson at an eyeglass lens store inputs their decision on whether or not to redesign the eyeglass lens 6 based on the evaluation results of the eyeglass lens 6, such as the distribution of visual acuity, displayed on the display unit 140, and the calculation unit 100 determines whether or not to redesign the lens according to that decision.

[0026] In step S1009, the spectacle lens design unit 110 either completes the design of the provisionally designed spectacle lens 6 or makes appropriate minor final adjustments to complete the design of the spectacle lens 6. The spectacle lens design unit 110 outputs the design result of the spectacle lens 6 to the processing machine control device 30. The processing machine control device 30 controls the spectacle lens processing machine 40 based on the design result of the spectacle lens 6. The spectacle lens processing machine 40 manufactures the designed spectacle lens 6.

[0027] [Design Evaluation of Eyeglass Lenses] A specific example of the evaluation of eyeglass lenses 6 in step S1005 described above will be explained in more detail with reference to Figure 3 and subsequent figures. The contrast evaluation unit 120 evaluates the contrast of eyeglass lenses 6 by calculating the contrast value of eyeglass lenses 6 designed according to the eyeglass lens prescription information D1. Indicators placed at indicator points P are used to evaluate the contrast of eyeglass lenses 6. Indicator points P are set at multiple mutually different coordinates in the three-dimensional space as seen from the wearer. The contrast evaluation unit 120 evaluates the contrast of eyeglass lenses 6 for each of the multiple indicator points P set in the three-dimensional space as seen from the wearer.

[0028] Generally, the clarity with which an object can be seen when viewed through eyeglass lenses 6 can be evaluated by calculating the contrast of the retinal image in the eye 5. For example, Modulation Transfer Function (MTF) is used as an index to evaluate the extent to which the contrast of an object is reduced in the retinal image.

[0029] Conventionally, optical calculations of contrast were limited to monocular vision. Although actual vision is generally improved by using both eyes, conventional evaluations of eyeglass lenses were limited to monocular performance. Furthermore, even when conventional eyeglass lenses were designed for binocular use, evaluations were limited to matching the performance of both eyes. Therefore, the contrast evaluation unit 120 of this embodiment evaluates contrast in binocular vision by binocular summation.

[0030] The perception of contrast in binocular vision is known as binocular addition. Binocular addition has been experimentally confirmed in various papers, and various models have been proposed to explain it. For example, the contrast binocular addition model M2 can be expressed by equation (1), where the right eye contrast value D3R is CR, the left eye contrast value D3L is CL, and the contrast perceived in binocular vision is C.

[0031]

[0032] This example shows an evaluation method for evaluating the contrast of eyeglass lenses 6, taking into account binocular summation, using the contrast evaluation unit 120 of this embodiment. First, the calculation of the monocular contrast value by the contrast evaluation unit 120 will be explained.

[0033] [Calculation of Monocular Contrast Value] (1) Setting of Index Points P Using the center of the corneal vertices of the left eye (5L) and right eye (5R) as the reference point, index points P are determined by the horizontal and vertical angles and the distance from the reference point. For evaluation of the entire visual field, points to be evaluated at equally spaced angles and multiple distances within the range of the visual field angle are determined to form a group of index points. For distance, the straight-line distance from the reference point to each index point P can be used, or index points P on the vertical plane at a predetermined distance along a line moving forward from the reference point can be set to the same distance.

[0034] The coordinate information acquisition unit 122 of the contrast evaluation unit 120 acquires the coordinate information D2 of the indicator point P as defined above. A more specific way of representing the coordinates of the indicator point P will be explained with reference to Figure 3.

[0035] Figure 3 shows an example of the configuration of the indicator points P in this embodiment. The indicator points P refer to a plurality of points set in a three-dimensional space based on the center point CP between the corneal vertex of the left eye 5L and the corneal vertex of the right eye 5R. The indicator points P are arranged in the direction of the optical axis OA with respect to the center point CP. The coordinates of the indicator points P are indicated by the distance d from the center point CP and the angle between the center line CL and the optical axis OA. The center line CL refers to a line perpendicular to the horizontal direction with respect to the line segment (for example, the visual baseline) connecting the corneal vertex of the left eye 5L and the corneal vertex of the right eye 5R. The left and right rotation angles of the optical axis OA with respect to the center line CL (rotation angle around the yaw axis) are represented by the horizontal angle φ, and the elevation and depression angles of the optical axis OA with respect to the center line CL (rotation angle around the pitch axis) are represented by the vertical angle θ.

[0036] Figure 4 shows an example of the configuration of multiple indicator points P in this embodiment. As shown in Figure 4, the coordinate information D2 contains coordinate information for multiple indicator points P (i.e., a group of indicator points) whose distance d, horizontal angle φ, and vertical angle θ are all different from each other.

[0037] For the sake of illustrating three-dimensional space in a plane, Figures 3 and 4 illustrate an example of the index point P(d, φ, θ1) when the vertical angle θ is a certain angle θ1. The coordinate information D2 also includes coordinate information for the index point P(d, φ, θ) for vertical angles θ other than angle θ1.

[0038] The coordinate information acquisition unit 122 acquires coordinate information D2 of multiple indicator points P set in a three-dimensional space based on the center point CP between the corneal vertex of the left eye 5L and the corneal vertex of the right eye 5R of the eyeball model M1.

[0039] The arrangement of indicator points P shown in Figures 3 and 4 above is merely an example and is not limited to those shown. For example, indicator points P can also be arranged as shown in Figure 5.

[0040] Figure 5 shows a modified configuration of the multiple indicator points P of this embodiment. In this modified configuration, the indicator points P are arranged on a plane parallel to the visual baseline. In this case, the distance d changes with changes in the horizontal angle φ and the vertical angle θ.

[0041] (2) Calculation of the amount of accommodation of the eye when fixating on each indicator point P The light rays passing from each indicator point P to the rotational center points of the right eye 5R and the left eye 5L are tracked, and the amount of accommodation of the eye required to focus on the retina is calculated from the power error and aberration with respect to the position. Since the eye's accommodative power decreases with age, the eye's accommodative power is estimated from the add power of eyeglass prescriptions, etc., and used in the calculation of the amount of accommodation.

[0042] The amount of accommodation required for each indicator point P may not be the same for the left and right eyes due to differences in the position of the indicator point P and the prescription for the left and right eyes. However, since the amount of accommodation response is generally considered to be the same for the right eye (5R) and the left eye (5L), the amount of accommodation for the eyes during binocular vision is determined accordingly.

[0043] The accommodation amount can be the average of the optimal accommodation amounts for both eyes, or a weighted average that takes the dominant eye into consideration. Alternatively, a value that considers the convergence amount of both eyes and age can be used. Or, a value that maximizes binocular contrast can be used. Furthermore, the minimum of the optimal accommodation amounts for both eyes may also be used.

[0044] For each index point P, the monocular contrast value calculation unit 123 calculates the left-eye contrast value D3L and the right-eye contrast value D3R respectively by applying a known ray tracing method or the like. FIG. 6 shows an example of ray tracing in the calculation of the monocular contrast value.

[0045] FIG. 6 is a diagram showing an example of ray tracing for calculating the monocular contrast value of the present embodiment. Specifically, the monocular contrast value calculation unit 123 calculates the left-eye contrast value D3L by ray-tracing the light rays that reach the retina of the left eye 5L from the index point P through the left-eye lens 6L by a known method. In the following description, the axis of the light ray from a certain index point P to the left-eye lens 6L is also referred to as the left-eye optical axis OAL.

[0046] Similarly, the monocular contrast value calculation unit 123 calculates the right-eye contrast value D3R in the same manner for the light rays that reach the retina of the right eye 5R from a certain index point P through the right-eye lens 6R. In the following description, the axis of the light ray from a certain index point P to the right-eye lens 6R is also referred to as the right-eye optical axis OAR.

[0047] (3) Calculation of Monocular Contrast The calculation of monocular contrast uses a general optical evaluation method. Using the eye model M1 created according to the prescription of the spectacle lens 6, ray tracing is performed from each visual target point P to the retina of the eye 5 (eyeball), the PSF (Point spread function) is calculated from the wavefront aberration, and the contrast value is calculated as the MTF. As an example, the contrast value represents the contrast on the retina when the fringe pattern of the contrast of the intensity distribution of the sine wave forms an image on the retina through the optical systems of the spectacle lens 6 and the eye 5. When calculating the contrast, the eye model M1 may be adjusted using the accommodation amount of the eye 5.

[0048] The right and left contrast values are calculated for a predetermined spatial frequency f, the rotation angle α of the fringe pattern of the visual target, and the visual target point P. The right-eye contrast value D3R is represented by CR(f, α, d, φ, θ), and the left-eye contrast value D3L is represented by CL(f, α, d, φ, θ).

[0049] In other words, the left eye contrast value D3L and the right eye contrast value D3R are represented by functions that take as arguments the spatial frequency f of a predetermined indicator pattern 71 placed at indicator point P, the rotation angle α of the indicator pattern 71 around the optical axis OA for ray tracing, the distance d from indicator point P to the retina, and the coordinate information D2 of indicator point P (first angle θ, second angle φ).

[0050] Figure 7 is a schematic diagram showing the monocular contrast value D3 of this embodiment. Figure 7[A] shows the positional relationship between the indicator point P, the spectacle lens 6, and the eye 5. Figure 7[B1] shows an example of an indicator pattern 71 placed at the indicator point P. This example shows an example of an indicator pattern 71 when the rotation angle α is 0[°]. The rotation angle α is the angle that indicates the direction of the pattern (for example, a striped pattern) of the indicator pattern 71. For example, if the indicator pattern 71 is a striped pattern, the rotation angle α = 0[°] is defined as the case where the striped pattern is arranged in the vertical direction.

[0051] The angle indicator pattern 71 is given a predetermined spatial frequency f. Figure 7[C1] shows an example of a spatial frequency graph 81 of the indicator pattern 71. The spatial frequency graph 81 has amplitude, frequency, and phase as parameters. In this example, the spatial frequency graph 81 is shown as a waveform with amplitude A1, frequency f1, and phase ρ1.

[0052] Figure 7 [B2] shows an example of contrast sensitivity 72, which is determined by the image projected onto the eye 5 (more specifically, the retina of the eye 5) when the subject views the indicator pattern 71 placed at the indicator point P through the spectacle lens 6.

[0053] Figure 7 [C2] shows an example of a spatial frequency graph 82 of contrast sensitivity 72. The spatial frequency graph 82 has amplitude, frequency, and phase as parameters. In this example, the spatial frequency graph 82 is shown as a waveform with amplitude A2, frequency f2, and phase ρ2.

[0054] In this example, the contrast sensitivity 72 shown in Figure 7[B2] indicates that the contrast is attenuated compared to the contrast of the index pattern 71 shown in Figure 7[B1]. More specifically, comparing the spatial frequency graph 81 of amplitude A1, frequency f1, and phase ρ1 shown in Figure 7[C1] with the spatial frequency graph 82 of amplitude A2, frequency f2, and phase ρ2 shown in Figure 7[C2], we see that frequencies f1 and f2, and phases ρ1 and ρ2, remain unchanged, but amplitude A2 decreases relative to amplitude A1.

[0055] In other words, the contrast value D3 can be calculated by estimating the amplitude A2 of the spatial frequency graph 82 of the contrast sensitivity 72 with respect to the amplitude A1 of the spatial frequency graph 81 of the indicator pattern 71 shown at indicator point P. The monocular contrast value calculation unit 123 uses the eyeball model M1 to estimate the amplitude A2.

[0056] The model acquisition unit 121 of the contrast evaluation unit 120 acquires the subject's eyeball model M1. The eyeball model M1 is information representing the refractive state of the subject's eyeball, created based on the prescription information D1 of the eyeglass lens 6 (i.e., the data used by the eyeglass lens design unit 110 to design the eyeglass lens 6).

[0057] In other words, the model acquisition unit 121 acquires an eyeball model M1 created based on the prescription information D1 (prescription of the eyeglass lens 6).

[0058] The monocular contrast value calculation unit 123 calculates the left eye contrast value D3L and the right eye contrast value D3R for each of the multiple indicator points P (for example, the multiple indicator points P shown in Figure 4).

[0059] In other words, the monocular contrast value calculation unit 123 calculates the left eye contrast value D3L and the right eye contrast value D3R for each indicator point P by tracing light rays that reach the retina of the eyeball model M1 via the spectacle lens 6 from the indicator point P, based on the eyeball model M1 and the coordinate information D2 of the indicator point P.

[0060] Furthermore, the contrast evaluation unit 120 may evaluate the contrast based on the angle of the visual target and the lateral magnification of the retinal image relative to the position of the indicator point P. In this case, the magnification of the right eye 5R is denoted as MR(α, d, φ, θ), and the magnification of the left eye 5L is denoted as ML(α, d, φ, θ). The ratio of the magnifications of the right eye 5R and the left eye 5L is denoted as Mratio(α, d, φ, θ). In this case, Mratio(α, d, φ, θ) can be expressed by equation (2).

[0061]

[0062] Mratio(α, d, φ, θ) is the ratio of the size of an object of a predetermined size at the same predetermined target point P in the retinal images of the right eye (5R) and the left eye (5L). General optical evaluation methods can also be used for each of the lateral magnifications.

[0063] [Calculation of Binocular Additive Contrast Value] Next, the calculation of the binocular additive contrast value by the binocular additive contrast calculation unit 124 of the contrast evaluation unit 120 will be explained. For the contrast of the left and right eyes at each target point P, the calculation is performed using the contrast binocular additive model M2 for each rotation angle α of the striped pattern which is the target. For example, the binocular additive contrast value D3B is obtained by the formula shown in equation (3).

[0064]

[0065] In other words, the model acquisition unit 121 acquires a contrast binocular additive model M2 that shows the contrast recognized in binocular vision.

[0066] The binocular additive contrast calculation unit 124 calculates the binocular additive contrast value D3B for each index point P based on the calculated left eye contrast value D3L and right eye contrast value D3R, and the binocular contrast additive model M2.

[0067] However, some binocular summing models include formulas that incorporate spatial frequency and contrast values ​​for the right eye (5R) and left eye (5L), and such formulas can also be used to calculate the binocular summed contrast value.

[0068] Furthermore, binocular summation becomes less effective when there is a difference in the size of the images in the two eyes, so this may be corrected. An example of a correction formula for binocular summation is shown in equation (4).

[0069]

[0070] Here, m(Mratio, f) is a correction coefficient whose variable is the binocular magnification ratio, and is assumed to have a value between 0 and 1.

[0071] When the magnification of the images in both eyes is the same, i.e., Mratio = 1, m(Mratio, f) = 1, and the binocular additive effect is maximized. When the spatial frequency f of the visual target is high, the phase shift of the target's striped pattern due to the difference in magnification becomes large, so even with the same difference in magnification Mratio, the correction coefficient m becomes small. Conversely, when the spatial frequency f is low, the effect of the difference in magnification Mratio on the correction coefficient m becomes small.

[0072] For example, the correction coefficient m can also be expressed by the following equation (5) using the spatial frequency f and the difference in magnification, Mratio.

[0073]

[0074] The minimum value of the correction coefficient m in equation (5) is 0, and γ is a proportionality constant that can be calculated experimentally or computationally from the range of the fovea on the retina, with γ having a value in the range of 0.1 to 1.0. For example, if we look at a target with a spatial frequency of 30 cpd (cycles per degree) and assume that the difference in magnification between the two eyes is 5% and the effect of binocular summation disappears, then γ = 0.67.

[0075] In other words, the binocular added contrast value D3B can also be corrected based on the ratio of the lateral magnification of the retinal image of the left eye 5L to the lateral magnification of the retinal image of the right eye 5R for each indicator point P, and the spatial frequency f of a predetermined indicator pattern 71 placed at indicator point P.

[0076] In addition, by taking into account the difference in visual acuity between the two eyes and the difference in the dominant eye depending on the direction of viewing, it can also be expressed as in equation (6).

[0077]

[0078] Here, kL(φ) and kR(φ) are values ​​obtained from the contrast sensitivity or visual acuity of both eyes, with the eye with the higher contrast sensitivity or visual acuity set to 1, and the other eye having a value of 1 or less. Furthermore, the effect of the dominant eye changing direction can be incorporated into the horizontal angle φ. Similarly, the difference in magnification can also be incorporated into equation (6) for calculation.

[0079] In other words, the binocular added contrast value D3B can also be corrected based on the contrast sensitivity of the left eye 5L and the right eye 5R, or the visual acuity of the left eye 5L and the right eye 5R, for each indicator point P.

[0080] In addition to the accommodative power described above, the amount of accommodation of the eye can also be adjusted so that the calculated binocular contrast Cb (or CBino) is maximized for each indicator point P. When there are directional aberrations such as astigmatism, the contrast has different values ​​for each angle of the target pattern. In the calculation of binocular contrast, the above binocular contrast calculation is performed for each angle, and an evaluation value is obtained from these multiple values. In this case, the contrast values ​​calculated for each angle can be expressed using the arithmetic mean or geometric mean, and it is also possible to use an average value (arithmetic mean, geometric mean) that takes into account the weighted value for each angle from the shape of a typical visual object (letter).

[0081] [Design Method for Eyeglass Lenses] Next, we will explain an example of a design method for eyeglass lenses 6 using the binocular additive contrast value D3B described above.

[0082] Generally, in eyeglass lenses 6, especially single-vision lenses, aberrations increase from the center to the periphery, and these aberrations degrade the quality of vision. By making the front, back, or both sides of the eyeglass lens 6 aspherical, it is possible to suppress aberrations in the periphery. The lens shape of an aspherical eyeglass lens 6 can be expressed, for example, by the following equation (7).

[0083]

[0084] Even with optimization using an aspherical shape, it is impossible to eliminate all aberrations in a configuration with two front and rear surfaces, such as in eyeglass lens 6. Of the aberrations in eyeglass lens 6, astigmatism and spherical power error have the greatest impact on vision.

[0085] Figure 8 shows an example of a spectacle lens 6 design that prioritizes suppressing astigmatism. Figure 9 shows an example of a spectacle lens 6 design that prioritizes suppressing spherical power error. By changing the optimization target of the spectacle lens 6, it is possible to create a design that prioritizes astigmatism (astigmatism-focused design) as shown in Figure 8, or a design that prioritizes spherical power error (power-focused design) as shown in Figure 9.

[0086] When evaluating visual contrast in visual space, the contrast decreases as you approach the periphery of the spectacle lens 6 compared to the center, due to the effects of aberrations. Furthermore, contrast changes with distance d to the target. Such contrast values ​​vary depending on whether the design prioritizes astigmatism correction or power correction, and their characteristics change with distance d as follows.

[0087] Figure 10 shows an example of the contrast value distribution at close range. As shown in Figure 10, when the distance to the indicator point P is short (for example, 1 [m]), the astigmatism-prioritizing design has a higher contrast value than the power-prioritizing design. This is because, at close range, the power error is corrected by the accommodation of the eye 5.

[0088] Figure 11 shows an example of the contrast value distribution at long distances. As shown in Figure 11, when the distance to the indicator point P is long (for example, 10 [m]), the power-focused design has a higher contrast value than the astigmatism-focused design. This is because, at long distances, the focus error becomes larger in the astigmatism-focused design.

[0089] As an example of a design that takes binocular contrast into consideration, it is also possible to design the lens so that the target of optimization is different on the temporal and nasal sides.

[0090] Figure 12 shows an example of an eyeglass lens 6 in which the optimization target differs between the temporal and nasal sides of the lens. In Figure 12, for the left eye lens 6L and the right eye lens 6R of the eyeglass lens 6, the nasal side is designated as the region for designing with an emphasis on astigmatism, and the temporal side is designated as the region for designing with an emphasis on power. The design of the eyeglass lens 6 shown in Figure 12 is an example of an asymmetrical design in which the region for designing with an emphasis on astigmatism and the region for designing with an emphasis on power are arranged asymmetrically on the left and right sides.

[0091] Figure 13 shows an example of the astigmatism distribution in an asymmetrically designed spectacle lens 6. Figure 13 compares the astigmatism distribution of conventional spectacle lenses designed with an emphasis on astigmatism, and conventional spectacle lenses designed with an emphasis on power, with the astigmatism distribution of the asymmetrically designed spectacle lens 6. In this example, the asymmetrically designed spectacle lens 6 is closer to the astigmatism distribution of the astigmatism-emphasizing design on the nasal side, and closer to the astigmatism distribution of the power-emphasizing design on the temporal side.

[0092] Figure 14 shows an example of the evaluation results (near distance) of the contrast of one eye with an asymmetrically designed spectacle lens 6. Figure 14 shows an example of the right eye contrast value D3R. Figure 15 shows an example of the evaluation results (far distance) of the contrast of one eye with an asymmetrically designed spectacle lens 6. Figure 15 shows an example of the right eye contrast value D3R.

[0093] When evaluating the contrast of one eye with an asymmetrically designed spectacle lens 6, the contrast values ​​differ depending on the distance d to the indicator point P, as shown by comparing Figures 14 and 15. Specifically, when the distance to the indicator point P in Figure 14 is short (e.g., 1 [m]), the contrast value on the nasal side is higher than that on the temporal side, and when the distance to the indicator point P is long (e.g., 10 [m]), the contrast value on the temporal side is higher than that on the nasal side.

[0094] Figure 16 shows an example of the binocular contrast evaluation results (near distance) for the asymmetrically designed spectacle lens 6. Figure 17 shows an example of the binocular contrast evaluation results (far distance) for the asymmetrically designed spectacle lens 6.

[0095] When evaluating the binocular contrast of the asymmetrically designed spectacle lens 6, it exhibits performance comparable to a design prioritizing astigmatism at close distances (e.g., 1 m) and performance comparable to a design prioritizing power at long distances (e.g., 10 m), thus achieving high contrast in the evaluation region of visual space.

[0096] Furthermore, as an example of a design where the nasal and temporal regions of the spectacle lens 6 have different designs, it is possible, if only considering the contrast of binocular vision, to have a power-focused design on the nasal side and an astigmatism-focused design on the temporal side.

[0097] Figure 18 shows an example of a spectacle lens 6 design using an asymmetric design that takes into account the difference in magnification between the two eyes. Figure 19 shows an example of the difference in magnification between the two eyes with an asymmetric design spectacle lens 6. Figure 19 shows that when a spectacle lens 6 with an asymmetric design that takes into account the difference in magnification between the two eyes, with the nasal side designed to prioritize astigmatism and the temporal side designed to prioritize power, the difference in binocular magnification is reduced. According to the asymmetric design of the spectacle lens 6 of this embodiment (Figure 18[C]), compared to conventional astigmatism-focused designs (Figure 18[A]) and power-focused designs (Figure 18[B]), the difference in magnification between the two eyes is reduced, thereby providing an improved contrast effect in binocular vision.

[0098] Figure 20 shows an example of the calculation results for binocular contrast. In Figure 20, the horizontal axis represents the target distance and the vertical axis represents the horizontal distance of the target, expressing the magnitude of the contrast value. According to the binocular design of the spectacle lens 6 of this embodiment (Figure 20[C]), a contrast improvement effect can be obtained compared to conventional astigmatism-focused designs (Figure 20[A]) and power-focused designs (Figure 20[B]).

[0099] Figure 21 shows an example of a design result for the aberration balance in the distance vision portion of a progressive lens. According to the design method for eyeglass lenses 6 that applies the binocular vision design of this embodiment, various design results can be obtained by changing the aberration balance in the distance vision portion of the progressive lens. In this example, the distribution of aberrations in the distance vision region of the progressive lens is different on the temporal and nasal sides. In the design of eyeglass lenses 6, the distribution of aberrations in the distance vision portion can be changed on the temporal and nasal sides. For example, as shown in Figure 21, using the second design result (Lens Design 2; Figure 21 [B]) as the reference design, the first design result (Lens Design 1; Figure 21 [A]) has a smaller aberration on the temporal side and a larger aberration on the nasal side, and the third design result (Lens Design 2; Figure 21 [C]) has a larger aberration on the temporal side and a smaller aberration on the nasal side. Even with such a design method, the balance of the visual appearance of eyeglass lenses 6 can be adjusted by evaluating the binocular contrast.

[0100] In other words, in the design of the spectacle lens 6, the binocular summed contrast value D3B of the left-eye lens 6L and the right-eye lens 6R may be evaluated using the contrast evaluation method for the spectacle lens 6 described above, and the design values ​​for the power and aberration of each lens may be arranged asymmetrically on the temporal and nasal sides of each lens.

[0101] [Summary of Embodiments] As described above, the eyeglass lens manufacturing system 1 of this embodiment allows for the design of eyeglass lenses 6 using binocular weighting (binocular addition), thereby improving contrast and widening the field of view.

[0102] While embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and design changes and the like are also included within the scope of the gist of the present invention. For example, a computer program for realizing the functions of each of the above-described devices may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read by a computer system and executed. The term "computer system" as used herein may include hardware such as an operating system and peripheral devices.

[0103] Furthermore, "computer-readable recording media" refers to writable non-volatile memory such as flexible disks, magneto-optical disks, ROMs, and flash memory, portable media such as DVDs (Digital Versatile Discs), and storage devices such as hard disks built into computer systems. In addition, "computer-readable recording media" also includes volatile memory (such as DRAM (Dynamic Random Access Memory)) within computer systems that act as servers or clients when programs are transmitted via networks such as the Internet or communication lines such as telephone lines, which retains programs for a certain period of time.

[0104] Furthermore, the above program may be transmitted from a computer system that stores the program in a memory device or the like to another computer system via a transmission medium or by transmission waves within the transmission medium. Here, the "transmission medium" for transmitting the program refers to a medium that has the function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. Also, the above program may be for the purpose of realizing a part of the functions described above. Furthermore, it may be a so-called differential file (differential program) that can realize the above functions in combination with a program already recorded in the computer system.

[0105] 1...Eyeglass lens manufacturing system, 10...Eyeglass lens evaluation device, 20...Storage device, 30...Processing machine control device, 40...Eyeglass lens processing machine, 100...Calculation unit, 110...Eyeglass lens design unit, 120...Contrast evaluation unit, 121...Model acquisition unit, 122...Coordinate information acquisition unit, 123...Monocular contrast value calculation unit, 124...Binocular additive contrast calculation unit

Claims

1. A method for evaluating the contrast of eyeglass lenses, comprising: obtaining an eyeball model created based on the prescription of eyeglass lenses and a binocular contrast additive model that shows the contrast recognized in binocular vision; obtaining coordinate information of a plurality of indicator points set in a three-dimensional space based on the center point between the corneal vertex of the left eye and the corneal vertex of the right eye of the eyeball model; calculating left eye contrast values ​​and right eye contrast values ​​for each indicator point by tracing light rays that reach the retina of the eyeball model through the eyeglass lenses from the indicator points, based on the eyeball model and the coordinate information of the indicator points; and calculating a binocular additive contrast value for each indicator point based on the calculated left eye contrast values ​​and right eye contrast values ​​and the binocular contrast additive model.

2. The method for evaluating the contrast of spectacle lenses according to claim 1, wherein the left eye contrast value and the right eye contrast value are expressed by a function whose arguments are the spatial frequency (f) of a predetermined indicator pattern placed at the indicator point, the rotation angle (α) of the indicator pattern around the optical axis of the ray tracing, the distance (d) from the indicator point to the retina, and the coordinate information (φ, θ) of the indicator point.

3. The method for evaluating the contrast of spectacle lenses according to claim 1, further comprising correcting the binocular summed contrast value based on the ratio of the lateral magnification of the retinal image of the left eye to the lateral magnification of the retinal image of the right eye for each indicator point, and the spatial frequency of a predetermined indicator pattern arranged at the indicator point.

4. The method for evaluating the contrast of spectacle lenses according to claim 1, further comprising correcting the binocular summed contrast value based on the contrast sensitivity of the left eye and the contrast sensitivity of the right eye, or the visual acuity of the left eye and the visual acuity of the right eye, for each of the index points.

5. A method for designing eyeglass lenses, which involves evaluating the binocular summation contrast values ​​of the left-eye lens and the right-eye lens using the contrast evaluation method for eyeglass lenses described in any one of claims 1 to 4, thereby arranging the design values ​​of the power and aberrations of each lens asymmetrically on the temporal and nasal sides of each lens.

6. A contrast evaluation device for eyeglass lenses comprising: a model acquisition unit that acquires an eyeball model created based on the prescription of eyeglass lenses and a binocular contrast addition model that shows the contrast recognized in binocular vision; a coordinate information acquisition unit that acquires coordinate information of a plurality of indicator points set in a three-dimensional space based on the center point between the corneal vertex of the left eye and the corneal vertex of the right eye of the eyeball model; a monocular contrast value calculation unit that calculates left eye contrast values ​​and right eye contrast values ​​for each indicator point by tracing light rays that reach the retina of the eyeball model from the indicator points through the eyeglass lenses, based on the eyeball model and the coordinate information of the indicator points; and a binocular addition contrast value calculation unit that calculates a binocular addition contrast value for each indicator point based on the calculated left eye contrast value and right eye contrast value and the binocular contrast addition model.

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