Method for evaluating sensitivity and method for manufacturing pair of spectacle lenses

Abstract

The reference blurred image (Cp) is visually recognized by one of the two eyes (for example, the right eye), and the blurred images (Cp + 1, Cp + 2,...) are visually recognized by the other of the two eyes (for example, the left eye). Information relating to the sensitivity to the difference in the amount of blurring between blurred images (Cp + 1, Cp + 2,...) viewed by the other eye and a reference blurred image (Cp) viewed by one eye is acquired. Furthermore, the other eye is made to visually recognize the reference blurred image (Cp), the one eye is made to visually recognize the blurred images (Cp + 1, Cp + 2,...), and information relating to the sensitivity to the difference in the amount of blurring between the blurred images (Cp + 1, Cp + 2,...) visually recognized by one eye and the reference blurred image (Cp) visually recognized by the other eye is acquired.

Description

Technical Field

[0001] The present invention relates to a method for evaluating sensitivity and a method for manufacturing a pair of eyeglass lenses. Background Art

[0002] In binocular vision, it is known that the contrast sensitivity becomes higher and the visual acuity improves compared with monocular vision due to the effect called binocular load (also called binocular addition). In a progressive power lens (for example, see Patent Document 1), which is a type of spectacle lens, the range that can be clearly seen by both eyes (the range with small aberration) is overlapped in the distance portion having a power suitable for long-distance observation, so that objects can be seen more clearly by binocular vision. However, there are individual differences in the effect called binocular load, and the spectacle lenses need to be designed according to the sensitivity of the wearer.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2006 / 001409 Pamphlet Summary of the invention

[0006] A sensitivity evaluation method according to one embodiment of the present invention includes causing a right eye and a left eye to visually recognize an image with different blur amounts, and obtaining information related to sensitivity to a difference in blur amounts between the images visually recognized by the right eye and the left eye.

[0007] Another embodiment of the present invention provides a method for manufacturing a pair of eyeglass lenses, wherein the pair of eyeglass lenses is composed of a right-eye eyeglass lens for a right eye and a left-eye eyeglass lens for a left eye, wherein the method for manufacturing the pair of eyeglass lenses includes: causing the right eye and the left eye to visually recognize an image with different amounts of blur; obtaining information related to sensitivity to the difference in blur amounts between the images visually recognized by the right eye and the left eye; designing the right-eye eyeglass lens and the left-eye eyeglass lens based on the information related to sensitivity to the difference in blur amounts; and manufacturing the right-eye eyeglass lens and the left-eye eyeglass lens based on the design. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Schematic diagram showing a pair of eyeglass lenses according to this embodiment.

[0009] Figure 2 It is a top view of a pair of eyeglass lenses in cross section.

[0010] Figure 3 It is a block diagram showing a spectacle lens ordering and order receiving system.

[0011] Figure 4 This is a flowchart showing the flow of a method for manufacturing a pair of eyeglass lenses.

[0012] Figure 5 This is a diagram showing an example of an order screen.

[0013] Figure 6 (A) is a diagram showing an original image before being processed into a blurred image, and (B) is a diagram showing an example of a blurred image.

[0014] Figure 7 is a block diagram showing an evaluation device.

[0015] Figure 8 This is a flowchart showing the flow of the sensitivity evaluation method.

[0016] Fig. 9 This is a conceptual diagram showing an example of evaluating sensitivity.

[0017] Fig.10 This is a flowchart showing the flow of a method for designing eyeglass lenses.

[0018] Fig.11 (A) is a diagram showing the distribution of astigmatism in a spectacle lens designed under a first lens design condition, (B) is a diagram showing the distribution of astigmatism in a spectacle lens designed under a second lens design condition, and (C) is a diagram showing the distribution of astigmatism in a spectacle lens designed under a third lens design condition.

[0019] Fig.12 This is a graph comparing the magnitude of astigmatism in the distance portion of eyeglass lenses for each lens design condition.

[0020] Fig.13 This is a graph showing the magnitude of astigmatism in the distance portion of the spectacle lens when the spectacle lens is designed under the first lens design condition.

[0021] Fig.14 This is a graph showing the magnitude of astigmatism in the distance portion of the spectacle lens when the spectacle lens is designed under the second lens design condition.

[0022] Fig.15 This is a conceptual diagram showing a modified example of evaluating sensitivity. DETAILED DESCRIPTION

[0023] Hereinafter, preferred embodiments of the present invention will be described. Figure 1 and Figure 2 A pair of eyeglass lenses 1 according to this embodiment is schematically shown. Figure 1 and Figure 2As shown, a pair of eyeglass lenses 1 is composed of a right-eye eyeglass lens 10R for the right eye ER and a left-eye eyeglass lens 10L for the left eye EL. In this embodiment, as a general term for the right-eye eyeglass lens 10R and the left-eye eyeglass lens 10L, it is sometimes simply referred to as eyeglass lenses 10. The eyeglass lenses 10 are also called progressive power lenses. In addition, the positional relationship of "upper part", "lower part" and the like in the eyeglass lenses 10 represents the positional relationship when the eyeglass lenses 10 are processed for eyeglasses when the eyeglasses are worn. In addition, the upper and lower positional relationship in the eyeglass lenses 10 is the same as Figure 1 and Fig.11 The upper and lower positional relationship on the paper is consistent.

[0024] like Figure 1 As shown, the right eye spectacle lens 10R has: a far portion 11R for the right eye; a near portion 12R for the right eye, which is formed at a position different from the far portion 11R for the right eye; and a progressive portion 13R for the right eye, which is formed between the far portion 11R for the right eye and the near portion 12R for the right eye. For example, the far portion 11R for the right eye is formed at the upper portion of the right eye spectacle lens 10R, the near portion 12R for the right eye is formed at the lower portion of the right eye spectacle lens 10R, and the progressive portion 13R for the right eye is formed at the middle portion of the right eye spectacle lens 10R. The far portion 11R for the right eye has an optical power suitable for long-distance observation. The near portion 12R for the right eye has an optical power suitable for near-distance observation. The right-eye progressive portion 13R continuously changes the optical power from the optical power suitable for long-distance observation to the optical power suitable for near-distance observation as it moves from the side close to the right-eye far portion 11R toward the side close to the right-eye near portion 12R. In this embodiment, "degree" (unit: diopter (D)) is sometimes used as a numerical value representing the optical power.

[0025] like Figure 1 As shown, the left eye spectacle lens 10L has: a left eye distance portion 11L; a left eye near portion 12L formed at a position different from the left eye distance portion 11L; and a left eye progressive portion 13L formed between the left eye distance portion 11L and the left eye near portion 12L. For example, the left eye distance portion 11L is formed at the upper portion of the left eye spectacle lens 10L, the left eye near portion 12L is formed at the lower portion of the left eye spectacle lens 10L, and the left eye progressive portion 13L is formed at the middle portion of the left eye spectacle lens 10L. The left eye distance portion 11L has an optical power suitable for long-distance observation. The left eye near portion 12L has an optical power suitable for near-distance observation. The optical power of the left-eye progressive portion 13L continuously changes from an optical power suitable for distance observation to an optical power suitable for near observation as it moves from the side close to the left-eye distance portion 11L toward the side close to the left-eye near portion 12L.

[0026] according to Figure 2It can be seen from the line of sight SR1 of the right eye ER and the line of sight SL1 of the left eye EL that when the wearer W of the pair of spectacle lenses 1 visually recognizes the right side of the distant object OB, he uses the ear-side portion of the right-eye spectacle lens 10R (right-eye distance portion 11R) and the nose-side portion of the left-eye spectacle lens 10L (left-eye distance portion 11L). Figure 2 It can be seen from the line of sight SR2 of the right eye ER and the line of sight SL2 of the left eye EL that when the wearer W of a pair of eyeglass lenses 1 visually recognizes the left side of a distant object OB, he uses the nose side portion of the right eye eyeglass lens 10R (right eye far vision portion 11R) and the ear side portion of the left eye eyeglass lens 10L (left eye far vision portion 11L).

[0027] In the eyeglass lens 10, which is also called a progressive power lens, the optical power varies depending on the position of the lens, thereby generating astigmatism. In contrast, the distribution of astigmatism is changed by design, thereby improving the appearance of the object passing through the eyeglass lens 10. For example, in the far vision portion 11R for the right eye and the far vision portion 11L for the left eye, the distribution of astigmatism is changed in the part on the ear side and the part on the nose side, thereby changing the degree of blur of the right eye ER and the left eye EL when visually recognizing a distant object OB. However, there are individual differences in the difference in the degree of blur at the right eye ER and the left eye EL that allows the wearer W to visually recognize with both eyes. In this embodiment, during manufacturing, the eyeglass lens 10 corresponding to the wearer W is designed by evaluating the sensitivity of the wearer W to the difference in the degree of blur at the right eye ER and the left eye EL. In the following, the degree of blur is sometimes referred to as the amount of blur.

[0028] Next, a spectacle lens ordering and order receiving system for manufacturing a pair of spectacle lenses 1 according to the present embodiment will be described. Figure 3 Spectacle lens ordering and order acceptance system 50 is shown. Figure 3 As shown, the spectacle lens ordering and order receiving system 50 is configured to include an ordering device 60 provided at an optical shop (orderer side), an order receiving device 70 provided at a lens manufacturer, a processing machine control device 80, and a spectacle lens processing machine 85. The ordering device 60 and the order receiving device 70 are connected to each other via a network 90 such as the Internet, for example, so as to be communicable. In addition, the order receiving device 70 is connected to the processing machine control device 80, and the processing machine control device 80 is connected to the spectacle lens processing machine 85. In addition, in Figure 3 In the figure, for the convenience of illustration, only one ordering device 60 is recorded, but in fact, a plurality of ordering devices 60 installed in a plurality of eyewear stores are connected to the order receiving device 70.

[0029] The ordering device 60 is a computer that performs order processing of the spectacle lenses 10. The ordering device 60 includes a control unit 61, a storage unit 65, a communication unit 66, a display unit 67, and an input unit 68. The control unit 61 controls the ordering device 60 by executing a program stored in the storage unit 65. The control unit 61 includes an order processing unit 62 that performs order processing of the spectacle lenses 10. The communication unit 66 communicates with the order receiving device 70 via the network 90. ​​The display unit 67 is configured using a display device such as a CRT or a liquid crystal display. The display unit 67 displays an order screen for inputting information (order information) of the ordered spectacle lenses, etc. The input unit 68 is configured using a mouse, a keyboard, etc., for example. For example, order information corresponding to the content of the order screen is input via the input unit 68. In addition, the display unit 67 and the input unit 68 may also be integrally configured by a touch panel, etc.

[0030] The order receiving device 70 is a computer that performs order receiving processing, design processing, optical performance calculation processing, etc. of the spectacle lens 10. The order receiving device 70 is configured to include a control unit 71, a storage unit 75, a communication unit 76, a display unit 77, and an input unit 78. The control unit 71 controls the order receiving device 70 by executing a program stored in the storage unit 75. The control unit 71 includes an order receiving processing unit 72 that performs order receiving processing of the spectacle lens 10 and a design unit 73 that performs design processing of the spectacle lens 10. The storage unit 75 stores various data used for spectacle lens design in a readable manner. The communication unit 76 communicates with the ordering device 60 via the network 90. ​​In addition, the communication unit 76 communicates with the processing machine control device 80. The display unit 77 is configured using a display device such as a CRT or a liquid crystal display. The display unit 77 displays the design results of the spectacle lens 10, etc. The input unit 78 is configured using, for example, a mouse, a keyboard, etc. In addition, the display unit 77 and the input unit 78 may also be integrally configured by a touch panel, etc.

[0031] Next, refer to Figure 4 , the steps of manufacturing and providing a pair of eyeglass lenses 1 using the eyeglass lens ordering and order receiving system 50 are described. Figure 4 is a flow chart showing the process until a pair of spectacle lenses 1 is manufactured and provided. Figure 4 The left side shows the steps performed at the optical shop side. Figure 4 The right side of shows the steps performed on the lens manufacturer side. The orderer evaluates the wearer's sensitivity (step ST11). The sensitivity evaluation method will be described in detail later.

[0032] Next, the orderer displays an order screen on the display unit 67 of the ordering device 60, and inputs order information via the input unit 68 (step ST12). At this time, the orderer determines the order information of the spectacle lenses to be ordered, and the order information includes information related to the sensitivity to the difference in blur amount between the two eyes obtained when evaluating the wearer's sensitivity.

[0033] Figure 5 An example of an ordering screen 100 is shown. In the lens information item 101, items related to the customized degree of the lens, such as the product name, spherical power (S power), astigmatism power (C power), astigmatism axis, and additional power of the customized lens are input. The processing designation information item 102 is used to specify the outer diameter of the customized lens and the thickness at an arbitrary point. The dyeing information item 103 is used to specify the color of the lens. The fitting point (FP) information 104 inputs the position information of the eye of the wearer W. PD represents the pupillary distance. In the frame information item 105, the frame model name, frame category, etc. are input. In the sensitivity information item 106, as information related to the sensitivity to the difference in the amount of blur between the two eyes obtained when evaluating the wearer's sensitivity, a numerical value indicating the intensity of the sensitivity to blur is input. Figure 5 In the example shown, the intensity of the sensitivity to blur is expressed by 10 levels of numerical values ​​for the difference in blur degree at the right eye relative to the left eye and the difference in blur degree at the left eye relative to the right eye (the difference in blur degree at the right eye relative to the left eye is expressed as "5", and the difference in blur degree at the left eye relative to the right eye is expressed as "4"). The intensity of the sensitivity to blur is defined so that the larger the number, the stronger the sensitivity to blur.

[0034] The sensitivity to blur may be expressed as a larger numerical value as the sensitivity to blur decreases, or may be expressed using a symbol instead of a numerical value. There is no particular limitation on the method as long as the sensitivity to blur can be expressed and communicated according to a predetermined standard.

[0035] When the orderer enters Figure 5 When the order processing unit 62 of the ordering device 60 selects each item of the ordering screen 100 shown in the figure and clicks a send button (not shown), the order processing unit 62 of the ordering device 60 obtains the information (order information) inputted in each item of the ordering screen 100. The ordering device 60 transmits the order information obtained by the order processing unit 62 to the ordering device 70 via the communication unit 66 (step ST13). In addition, in the ordering device 60, the process of displaying the ordering screen 100, the process of obtaining the order information inputted in the ordering screen 100, and the process of transmitting the order information to the ordering device 70 are performed by the control unit 61 of the ordering device 60 executing a predetermined program pre-installed in the storage unit 65.

[0036] When the order information is sent from the ordering device 60, the order receiving processing unit 72 of the order receiving device 70 receives the order information from the ordering device 60 via the communication unit 76 (step ST21). The design unit 73 of the order receiving device 70 designs the spectacle lens 10 based on the received order information (step ST22). The design method of the spectacle lens 10 will be described in detail later. The order receiving device 70 outputs the design data of the spectacle lens 10 designed by the design unit 73 to the processing machine control device 80 via the communication unit 76.

[0037] The processing machine control device 80 sends a processing instruction to the eyeglass lens processing machine 85 based on the design data output from the order receiving device 70 (step ST23). As a result, the eyeglass lens processing machine 85 processes and manufactures the eyeglass lens based on the design data. The eyeglass lens 10 (i.e., a pair of eyeglass lenses 1) manufactured by the eyeglass lens processing machine 85 is shipped to an eyewear store, embedded in an eyeglass frame, and provided to a customer (wearer W). In addition, in the order receiving device 70, the processing of receiving order information from the ordering device 60, the processing of designing the eyeglass lens based on the received order information, and the processing of outputting the design data of the eyeglass lens to the processing machine control device 80 are performed by the control unit 71 of the order receiving device 70 executing a predetermined program pre-installed in the storage unit 75.

[0038] Next, the sensitivity evaluation method is described. In this embodiment, the wearer's eyes are made to visually recognize a plurality of blurred images C and / or original images C0 (see Figure 6 ), the wearer's sensitivity to blur is evaluated. In addition, the image before blurring is referred to as the original image C0. Figure 6 3 is a diagram illustrating an original image C0 and a blurred image C. Figure 6 (A) represents the original image C0 consisting of the letter “E”. Figure 6 (B) indicates that Figure 6 The original image C0 of (A) is blurred to different degrees to generate multiple blurred images Cα, Cβ, and Cγ. The blurred image Cα has a slight contour distortion, etc., and the degree of blur is small. The contour line of the blurred image Cβ is not clearly recognizable, and the degree of blur is medium. The blurred image Cγ is not clear as a whole, and the degree of blur is large.

[0039] The blurred image C is obtained by hypothetically generating a perceived image of the original image C0 when visually recognized through a spectacle lens having aberrations (astigmatism, error in optical power, etc.). The degree of aberration of the spectacle lens corresponds to the degree of blurriness of the generated blurred image C. Figure 6In the example shown, the degree of astigmatism of the spectacle lens corresponds to the degree of blur of the blurred image C. Therefore, the optical characteristics such as astigmatism of the spectacle lens 10 can be appropriately set to suit the wearer W based on information related to the wearer's sensitivity to blurred images C with different blur degrees.

[0040] In order to generate the blurred image C, for example, the original image C0 is arranged at a position away from the front surface of the eyeball by a predetermined distance (the distance between the wearer and the blurred image when evaluating the sensitivity), and in a model in which the eyeglass lens is arranged in the optical path from the original image C0 to the retina of the eyeball, ray tracing is performed from a certain point of the original image C0 to obtain the point spread function (PSF; Point spread function) on the retina. Then, the brightness and color concentration of each point of the original image C0 are convoluted and integrated by the point spread function to generate the blurred image C. In addition, the calculation of ray tracing can be performed using a PC (Personal Computer) or the like, for example. In the model in which ray tracing is performed, by appropriately changing the aberrations (astigmatism, error in optical power, etc.) of the eyeglass lens, a plurality of blurred images C with different blur amounts can be generated.

[0041] For example, the minimum aberration amount is set to 0 [D] (that is, the aberration amount of the eyeglass lens corresponding to the original image C0), the maximum aberration amount is set to 1 [D] to 3 [D], and the interval of the aberration amount is set to 0.05 [D] to 0.25 [D], and a plurality of blurred images C are generated. In this way, the aberration amount of the corresponding eyeglass lens can be known in association with the plurality of blurred images C having different blur amounts.

[0042] When visually recognizing a plurality of blurred images C or the original image C0, the display device 96 (see FIG. 1 ) provided in the evaluation device 95 is used. Figure 7 ), so that the wearer's eyes can recognize different images. Figure 7 As shown schematically, the evaluation device 95 includes a display device 96, a display control unit 97, a storage unit 98, and an input unit 99. The display device 96 is configured to enable the wearer's eyes to visually recognize different images simultaneously using, for example, a head-mounted display, a polarization display using a polarization filter (also called a three-dimensional display), etc. The display control unit 97 performs control to select one of the multiple blurred images C and the original image C0 and display it on the display device 96. The storage unit 98 can read and store image data of the multiple blurred images C and the original image C0 generated in advance. The input unit 99 is configured using, for example, a mouse, a keyboard, etc. For example, information related to the multiple blurred images C or the original image C0 displayed on the display device 96 is input via the input unit 99.

[0043] The evaluation device 95 can be assembled to the ordering device 60, or it can be set separately from the ordering device 60 in the eyewear store (on the orderer's side). In addition, the evaluation device 95 can also have an image generation unit (not shown) that generates a plurality of blurred images C. In the present embodiment, the plurality of blurred images C are sometimes referred to as blurred images C1 to Cn (n is an integer greater than 2). For example, when n=5, blurred images C1 to C5 represent blurred image C1 with the smallest amount of blur, blurred image C2 with the second smallest amount of blur, blurred image C3 with the third smallest amount of blur, blurred image C4 with the fourth smallest amount of blur, and blurred image C5 with the largest amount of blur. Similarly, blurred images C1 to Cn represent blurred image C1 with the smallest amount of blur, ..., and blurred image Cn with the largest amount of blur.

[0044] Figure 8 : is a flowchart showing the evaluation step of the wearer's sensitivity corresponding to step ST11. When evaluating the wearer's sensitivity, the subscriber adjusts the wearer's vision using corrective lenses or the like so that the wearer can clearly visually recognize the original image C0 (step ST111). At this time, the subscriber can also adjust the wearer's vision while the wearer wears the display device 96. By configuring the display device 96 using a head-mounted display, a polarization display (three-dimensional display), etc., the wearer's vision can be adjusted so that the wearer can clearly visually recognize the original image C0 at a position corresponding to a position away from the front surface of the eyeball at a predetermined distance (the distance between the wearer and the blurred image when evaluating the sensitivity) through the eyepiece optical system or the like provided in the display device 96.

[0045] Next, the orderer causes the wearer to wear the display device 96, and causes the wearer's eyes to visually recognize the original image C0 or the blurred images C1 to Cn, respectively, and obtains the permissible value Pb of astigmatism that allows the wearer to visually recognize the original image C0 or the blurred images C1 to Cn (step ST112). Specifically, Fig. 9 As shown, the wearer's eyes are made to visually recognize the original image C0, the blurred image C1 with the smallest blur amount, the blurred image C2 with the second smallest blur amount, the blurred image C3 with the third smallest blur amount, the blurred image C4 with the fourth smallest blur amount, and so on. At this time, the wearer who visually recognizes the blurred image is asked to answer whether to allow the blurred image to be visually recognized by both eyes through verbal or input operation to the input unit 99 of the evaluation device 95. Then, the blurred image that can be visually recognized by both eyes (for example, Fig. 9 Among the blurred images C1 to C3 in the image list, the blurred image with the largest blur amount (for example, Fig. 9The amount of aberration corresponding to the blurred image C3 in the image is used as the permissible value Pb of astigmatism. Hereinafter, the permissible value Pb of astigmatism is sometimes referred to as the basic permissible value Pb. In addition, the order of visually recognizing the original image C0 or the blurred images C1 to Cn is not limited to the order in which the blur amount increases from the original image C0, but may be the order in which the blur amount decreases from the blurred image Cn with the largest blur amount, or may be a random order.

[0046] When the orderer obtains the basic permissible value Pb, the orderer sets a blurred image corresponding to an aberration amount of 1 / 3 to 2 / 3 of the basic permissible value Pb among the blurred images C1 to Cn as a reference blurred image Cp. The orderer causes one eye (e.g., the right eye) of the wearer to visually recognize the reference blurred image Cp, and causes the other eye (e.g., the left eye) of the wearer to visually recognize a blurred image having a blur amount greater than that of the reference blurred image Cp, and obtains the permissible value PR of astigmatism that is allowed to be visually recognized by both eyes (step ST113). For example, Fig. 9 As shown, the other eye (for example, the left eye) is visually recognized in the order of a reference blurred image Cp, a blurred image Cp+1 having a larger blur amount than the reference blurred image Cp, a blurred image Cp+2 having a larger blur amount than the blurred image Cp+1, a blurred image Cp+3 having a larger blur amount than the blurred image Cp+2, a blurred image Cp+4 having a larger blur amount than the blurred image Cp+3, ... At this time, the wearer who visually recognizes the blurred image is asked to answer whether to allow the blurred image to be visually recognized by both eyes by verbal or input operation to the input unit 99 of the evaluation device 95. Then, the aberration amount corresponding to the blurred image having the largest blur amount that can be visually recognized by both eyes among the blurred images Cp+1, Cp+2, ... that are visually recognized by the other eye (for example, the left eye) is obtained as the allowable value PR of astigmatism. In addition, the difference ΔPR between the obtained allowable value PR of astigmatism and the basic allowable value Pb is obtained. Hereinafter, the difference ΔPR between the permissible value PR of astigmatism and the basic permissible value Pb may be referred to as a first permissible difference ΔPR.

[0047] Then, the orderer causes the other eye (e.g., the left eye) of the wearer to visually recognize the reference blurred image Cp, and causes one eye (e.g., the right eye) of the wearer to visually recognize a blurred image having a blur amount greater than that of the reference blurred image Cp, and obtains the allowable value PL of astigmatism that can be visually recognized by both eyes (step ST114). At this time, similarly to the above-mentioned step ST113, the aberration amount corresponding to the blurred image having the maximum blur amount that can be visually recognized by both eyes among the blurred images Cp+1, Cp+2, ... visually recognized by one eye (e.g., the right eye) is obtained as the allowable value PL of astigmatism. In addition, the difference ΔPL between the obtained allowable value PL of astigmatism and the basic allowable value Pb is obtained. Hereinafter, the difference ΔPL between the allowable value PL of astigmatism and the basic allowable value Pb may be referred to as the second allowable difference ΔPL.

[0048] In addition, the reference blurred image Cp or blurred images Cp+1, Cp+2, ... may be selected and used from blurred images C1 to Cn used in the previous step ST112, or may be regenerated based on the basic allowable value Pb. Fig. 9 In the example shown, the blurred image C3 with the third smallest blur amount is set as the reference blurred image Cp. In addition, the order of visually recognizing the reference blurred image Cp or blurred images Cp+1, Cp+2, ... is not limited to the order of increasing blur amount from the reference blurred image Cp, but may be the order of decreasing blur amount from the blurred image with the largest blur amount, or may be a random order.

[0049] In this way, information about the first allowable difference ΔPR and the second allowable difference ΔPL is obtained as information related to the sensitivity to the difference in blur amount between the two eyes. When each process of evaluating the wearer's sensitivity (steps ST111 to ST114) is completed, the process of inputting order information (step ST12) is entered. Figure 5 In the example of the order screen 100 shown, the numerical value indicating the intensity of the sensitivity to blur is expressed by 10 levels of numerical values ​​based on the first allowable difference ΔPR and the second allowable difference ΔPL.

[0050] Next, a method for designing the spectacle lens 10 will be described. Fig.102 is a flowchart showing the design steps of the spectacle lens 10 corresponding to step ST22. When designing the spectacle lens 10, the order receiving device 70 obtains the prescription data of the spectacle lens and the design parameters including information related to the sensitivity to the difference in blur amount between the two eyes (for example, information related to the first allowable difference ΔPR and the second allowable difference ΔPL described above) (step ST221). At this time, the order receiving device 70 also appropriately obtains fitting parameters such as the forward tilt angle, the curvature angle, and the distance between the eye and the lens of the frame.

[0051] Next, the design unit 73 of the order receiving device 70 sets the target aberration of the spectacle lens based on the design parameters including information related to the sensitivity to the difference in the amount of blur between the two eyes obtained in the previous step ST221 (step ST222). As described above, in the distance portion of the spectacle lens, which is also called a progressive power lens, by changing the distribution of astigmatism in the ear-side portion and the nose-side portion, that is, by changing the symmetry of the distribution of astigmatism, the degree of blur of the right eye and the left eye when visually recognizing a distant object can be changed. Here, the design parameter for adjusting the aberration amount of astigmatism in the ear-side portion of the distance portion of the spectacle lens is set to De. The design parameter for adjusting the aberration amount of astigmatism in the nose-side portion of the distance portion of the spectacle lens is set to Dn. The design parameters De and Dn are design parameters whose larger values ​​result in a wider area where the astigmatism becomes smaller, that is, an area that appears clear.

[0052] In addition, the design condition of De=+5, Dn=-5 is called the first lens design condition. The design condition of De=0, Dn=0 is called the second lens design condition. The design condition of De=-5, Dn=+5 is called the third lens design condition. Fig.11 (A) is a diagram showing the distribution of astigmatism in the spectacle lens 10 when the spectacle lens 10 is designed under the first lens design condition. Fig.11 (B) is a diagram showing the distribution of astigmatism in the spectacle lens 10 when the spectacle lens 10 is designed under the second lens design condition. Fig.11 (C) is a diagram showing the distribution of astigmatism in the spectacle lens 10 when the spectacle lens 10 is designed under the third lens design condition. Fig.11 In (A) to (C), the darker the area, the greater the astigmatism. Fig.11 As can be seen from (A) to (C), by changing the design parameters De and Dn, the symmetry of the distribution of astigmatism in the eyeglass lens 10 can be changed.

[0053] Fig.12 The magnitude of astigmatism in the distance portion of the spectacle lens is compared for each lens design condition. Fig.12 The solid line in the graph shown represents the magnitude of astigmatism when the lens is designed under the first lens design condition. Fig.12 The one-dot chain line in the graph shown represents the magnitude of astigmatism when the lens is designed under the second lens design condition. Fig.12 The double-dashed line in the graph shown in FIG. 1 represents the magnitude of astigmatism when the lens is designed under the third lens design condition. Fig.12 It can be seen that under the first lens design condition, the astigmatism of the ear side portion of the far vision portion of the spectacle lens becomes relatively small, and the astigmatism of the nose side portion becomes relatively large. On the other hand, under the third lens design condition, the astigmatism of the ear side portion of the far vision portion of the spectacle lens becomes relatively large, and the astigmatism of the nose side portion becomes relatively small.

[0054] Fig.13 The following diagram shows the magnitude of astigmatism in the distance portion of the spectacle lens when the spectacle lens is designed under the first lens design condition. Fig.13 The solid line of the graph shown in FIG. 1 represents the right-eye distance portion 11R (see FIG. 11R ) of the right-eye spectacle lens 10R designed under the first lens design condition. Figure 1 ) in the image. Fig.13 The double-dashed line in the graph shown in FIG. 1 represents the left-eye distance portion 11L (see FIG. 11L ) of the left-eye spectacle lens 10L designed under the first lens design condition. Figure 1 ) in the image. Fig.13 It can be seen that under the first lens design condition, the difference in astigmatism between the right-eye spectacle lens 10R (right-eye distance portion 11R) and the left-eye spectacle lens 10L (left-eye distance portion 11L) becomes larger.

[0055] Fig.14 The magnitude of astigmatism in the distance portion of the spectacle lens when the spectacle lens is designed under the second lens design condition is shown. Fig.14 The solid line of the graph shown in FIG. 1 represents the right-eye distance portion 11R (see FIG. 11B ) of the right-eye spectacle lens 10R designed under the second lens design condition. Figure 1 ) in the image. Fig.14 The double-dashed line in the graph shown in FIG. 1 represents the left-eye distance portion 11L (see FIG. 11L ) of the left-eye spectacle lens 10L designed under the second lens design condition. Figure 1 ) in the image. Fig.14 It can be seen that under the second lens design condition, the difference in astigmatism between the right-eye spectacle lens 10R (right-eye distance portion 11R) and the left-eye spectacle lens 10L (left-eye distance portion 11L) is reduced.

[0056] In the present embodiment, the target aberration of the spectacle lens is set based on the first allowable difference ΔPR and the second allowable difference ΔPL. Specifically, when the first allowable difference ΔPR and the second allowable difference ΔPL are large, the difference in astigmatism between the right-eye spectacle lens 10R (right-eye distance portion 11R) and the left-eye spectacle lens 10L (left-eye distance portion 11L) is set to be large, as in the first lens design condition. On the other hand, when the first allowable difference ΔPR and the second allowable difference ΔPL are small, the difference in astigmatism between the right-eye spectacle lens 10R (right-eye distance portion 11R) and the left-eye spectacle lens 10L (left-eye distance portion 11L) is set to be small, as in the second lens design condition. In other words, the larger the first allowable difference ΔPR and the second allowable difference ΔPL are set, the smaller the astigmatism of the ear side portion of the right eye far vision portion 11R of the right eye spectacle lens 10R is than the astigmatism of the nose side portion of the left eye far vision portion 11L of the left eye spectacle lens 10L, and the smaller the astigmatism of the ear side portion of the left eye far vision portion 11L of the left eye spectacle lens 10L is than the astigmatism of the nose side portion of the right eye far vision portion 11R of the right eye spectacle lens 10R.

[0057] When the difference in astigmatism is set to be larger as in the first lens design condition, Fig.13 As shown, in the right part of the far-distance portion 11R of the right eye spectacle lens 10R, that is, the ear side part, the area with smaller aberration becomes larger. Therefore, the range of objects in the distance that can be recognized by the right eye alone as in single vision becomes larger. And, in the left part of the far-distance portion 11L of the left eye spectacle lens 10L, that is, the ear side part, the area with smaller aberration becomes wider. Therefore, the range of objects in the distance that can be recognized by the left eye alone as in single vision becomes larger. However, the aberration amount of astigmatism is different in the ear side part and the nose side part of the far-distance portion of the spectacle lens, so the blur amount when visually viewing the right or left side of a distant object is different in the left and right eyes. Therefore, for the wearer who is prone to discomfort when the first allowable difference ΔPR and the second allowable difference ΔPL are small, that is, when there is a difference in the appearance (blur amount) at the two eyes, the design of the spectacle lens becomes uncomfortable.

[0058] On the other hand, when the difference in astigmatism is set to be small as in the second lens design condition, Fig.14 As shown in FIG. 1 , the distribution of astigmatism in the distance portion of the spectacle lens is nearly bilaterally symmetrical. As a result, the appearance (amount of blur) when visually recognizing the right or left side of a distant object is approximately the same in the left and right eyes, so that it is not easy to feel uncomfortable. However, for a wearer who is not likely to feel uncomfortable even if the first allowable difference ΔPR and the second allowable difference ΔPL are large, that is, there is a difference in the appearance (amount of blur) between the two eyes, the range in which clear visual recognition can be performed is narrower than that under the first lens design condition.

[0059] In addition, the design parameters De and Dn can be calculated based on the first allowable difference ΔPR and the second allowable difference ΔPL. First, in order to simplify the calculation, the case where the same design parameters De and Dn are used in the right-eye spectacle lens 10R and the left-eye spectacle lens 10L is described. In this case, the design parameter De is represented by the following formula (1), and the design parameter Dn is represented by the following formula (2). De = D0 + ΔP × k … (1) Dn=D0-ΔP×k …(2)

[0060] Here, ΔP is the arithmetic mean of the first allowable difference ΔPR and the second allowable difference ΔPL. D0 is a design parameter set when the same design parameter is used for the ear side and the nose side in adjusting the astigmatism, for example. k is a predetermined coefficient. D0 and k vary according to the prescription data of the spectacle lens and the limit of the allowable astigmatism (blur). In addition, the wearer often uses the part of the spectacle lens closer to the ear side than the part on the nose side, so the design parameter De of the ear side part of the spectacle lens is set to have a larger value than the design parameter Dn of the nose side part.

[0061] Next, a case where different design parameters are used in the right-eye spectacle lens 10R and the left-eye spectacle lens 10L is described. In this case, the design parameter DRe for adjusting the aberration amount of astigmatism of the ear side portion in the right-eye distance portion 11R of the right-eye spectacle lens 10R is expressed by the following equation (3), and the design parameter DRn for adjusting the aberration amount of astigmatism of the nose side portion is expressed by the following equation (4). DRe=D0+ΔPR×k …(3) DRn=D0-ΔPL×k …(4)

[0062] The design parameter DLe for adjusting the aberration amount of astigmatism on the ear side of the left eye distance portion 11L of the left eye spectacle lens 10L is expressed by the following equation (5), and the design parameter DLn for adjusting the aberration amount of astigmatism on the nose side is expressed by the following equation (6). DLe=D0+ΔPL×k …(5) DLn=D0-ΔPR×k …(6)

[0063] Here, D0 and k are the same as those described in the above equations (1) and (2).

[0064] When the target aberration of the spectacle lens is set, the order receiving device 70 determines the shape of the entire lens of the spectacle lens (step ST223). After determining the shape of the entire lens of the spectacle lens, the order receiving device 70 determines whether the optical characteristics of the spectacle lens, such as the power and astigmatism, meet the desired conditions (step ST224). When the optical characteristics do not meet the desired conditions, that is, when the determination in step ST224 is no, the process returns to the previous step ST223. When the desired conditions are met, that is, when the determination in step ST224 is yes, the design process of the spectacle lens is terminated. When each process of designing the spectacle lens (steps ST221 to ST224) is completed, the process of processing the spectacle lens is entered (step ST23).

[0065] In this embodiment, the right eye and the left eye of the wearer are caused to visually recognize images (for example, the original image C0 or blurred images C1 to Cn) with different blur amounts, and information related to the sensitivity to the difference in blur amount between the images visually recognized by the right eye and the left eye is obtained. In this way, the wearer's sensitivity to the difference in appearance (blur amount) between the two eyes can be evaluated, and appropriate eyeglass lenses can be designed based on the information related to the wearer's sensitivity obtained. For example, one of the wearer's eyes is caused to visually recognize a reference blurred image (first image) Cp with a predetermined blur amount (blur amount corresponding to the reference blurred image Cp), and the other eye is caused to visually recognize blurred images (second images) Cp+1, Cp+2, ... having a larger blur amount than the reference blurred image Cp. Then, information related to the sensitivity to the difference in blur amount between the blurred images Cp+1, Cp+2, ... visually recognized by the other eye and the reference blurred image Cp visually recognized by one eye is obtained. Specifically, the aberration amount corresponding to the blurred image with the maximum blur amount that can be visually recognized by both eyes among the blurred images Cp+1, Cp+2, ... that are visually recognized by the other eye is calculated as the allowable value PR of astigmatism, and the difference ΔPR (first allowable difference ΔPR) between the allowable value PR of astigmatism and the basic allowable value Pb (i.e., the aberration amount corresponding to the reference blurred image Cp) is calculated.

[0066] Furthermore, the other eye is caused to visually recognize the reference blurred image Cp, and the one eye is caused to visually recognize the blurred images Cp+1, Cp+2, ... that are visually recognized by the one eye and the reference blurred image Cp that is visually recognized by the other eye. Then, information related to the sensitivity to the difference in blur amount between the blurred images Cp+1, Cp+2, ... that are visually recognized by the one eye and the reference blurred image Cp that is visually recognized by the other eye is obtained. Specifically, the aberration amount corresponding to the blurred image having the maximum blur amount that is allowed to be visually recognized by both eyes among the blurred images Cp+1, Cp+2, ... that are visually recognized by the one eye is obtained as the allowable value PL of astigmatism, and the difference ΔPL (second allowable value ΔPL) between the allowable value PL of astigmatism and the base allowable value Pb is obtained. Thus, the wearer's sensitivity to the difference in appearance (blur amount) between the two eyes can be evaluated with high accuracy, and appropriate eyeglass lenses can be designed based on the information related to the wearer's sensitivity obtained (that is, information related to the first allowable difference ΔPR and the second allowable difference ΔPL).

[0067] In addition, in the present embodiment, one eye and the other eye are caused to visually recognize blurred images (third images) C1 to Cn with the same blur amount at both eyes, respectively, and information related to the sensitivity to the blur amount of blurred images C1 to Cn is obtained. Specifically, the aberration amount corresponding to the blurred image with the largest blur amount among the blurred images that can be visually recognized by both eyes is obtained as the allowable value Pb (basic allowable value Pb) of astigmatism. Then, based on the basic allowable value Pb, the reference blurred image Cp (that is, the prescribed blur amount corresponding to the reference blurred image Cp) is set. In this way, the wearer's sensitivity to the difference in appearance (blur amount) at both eyes can be evaluated with high accuracy, and appropriate eyeglass lenses can be designed.

[0068] In addition, in the present embodiment, the right-eye spectacle lens 10R and the left-eye spectacle lens 10L are designed in such a manner that the greater the maximum value of the difference in blur amount that can be visually recognized by both eyes, i.e., the first allowable difference ΔPR and the second allowable difference ΔPL, the smaller the aberration of the ear side portion of the right-eye distance portion 11R of the right-eye spectacle lens 10R is than the aberration of the nose side portion of the left-eye distance portion 11L of the left-eye spectacle lens 10L, and the smaller the aberration of the ear side portion of the left-eye distance portion 11L of the left-eye spectacle lens 10L is than the aberration of the nose side portion of the right-eye distance portion 11R of the right-eye spectacle lens 10R. Thus, the spectacle lens 10 can be appropriately designed and manufactured according to the wearer's sensitivity to the difference in appearance (blur amount) between the two eyes.

[0069] Furthermore, as described above, the right-eye spectacle lens 10R includes: a right-eye near portion 12R having a power suitable for near observation; and a right-eye progressive portion 13R provided between the right-eye distance portion 11R and the right-eye near portion 12R, and having a power varying between the power of the right-eye distance portion 11R and the power of the right-eye near portion 12R. The left-eye spectacle lens 10L includes: a left-eye near portion 12L having a power suitable for near observation; and a left-eye progressive portion 13L provided between the left-eye distance portion 11L and the left-eye near portion 12L, and having a power varying between the power of the left-eye distance portion 11L and the power of the left-eye near portion 12L. As described above, the spectacle lens 10 is preferably a progressive power lens.

[0070] In the above embodiment, in step ST112, the wearer's eyes are made to visually recognize the original image C0 or the blurred images C1 to Cn, respectively, and the permissible value Pb of astigmatism (basic permissible value Pb) that allows the wearer's eyes to visually recognize the original image C0 or the blurred images C1 to Cn is obtained, but the present invention is not limited to this. Fig.15 As shown in FIG. 1 , step ST112 can be omitted by setting the original image C0 as the reference blurred image Cp. Thus, the wearer's sensitivity to the difference in appearance (blur amount) between the two eyes can be evaluated by a simple method.

[0071] In this case, in step ST113, the orderer causes one eye (e.g., the right eye) of the wearer to visually recognize the original image C0, and causes the other eye (e.g., the left eye) of the wearer to visually recognize the original image C0 or blurred images C1 to Cn, and obtains the permissible value PR of astigmatism that allows visual recognition by both eyes. Fig.15 As shown, the other eye (for example, the left eye) is visually recognized in the order of the original image C0, the blurred image C1 with the smallest blur amount, the blurred image C2 with the second smallest blur amount, the blurred image C3 with the third smallest blur amount, the blurred image C4 with the fourth smallest blur amount, etc. At this time, the wearer who visually recognizes the blurred image is asked to answer whether to allow the blurred image to be visually recognized by both eyes by verbal or input operation to the input unit 99 of the evaluation device 95. Then, the aberration amount corresponding to the blurred image with the largest blur amount that can be visually recognized by both eyes among the blurred images C1 to Cn visually recognized by the other eye (for example, the left eye) is obtained as the allowable value PR0 of astigmatism. In addition, the difference ΔPR (first allowable difference ΔPR) between the obtained allowable value PR0 of astigmatism and the aberration amount corresponding to the original image C0 is obtained. Since the aberration amount corresponding to the original image C0 is zero, the first allowable difference ΔPR is equal to the allowable value PR0 of astigmatism.

[0072] In this case, in step ST114, the orderer causes the other eye (e.g., the left eye) of the wearer to visually recognize the original image C0, and causes one eye (e.g., the right eye) of the wearer to visually recognize the original image C0 or the blurred images C1 to Cn, and finds the allowable value PL0 of astigmatism that can be visually recognized by both eyes. At this time, as in the previous step ST113, the aberration amount corresponding to the blurred image having the maximum blur amount that can be visually recognized by both eyes among the blurred images C1 to Cn that are visually recognized by one eye (e.g., the right eye) is found as the allowable value PL0 of astigmatism. In addition, the difference ΔPL (second allowable difference ΔPL) between the obtained allowable value PL0 of astigmatism and the aberration amount corresponding to the original image C0 is found. Since the aberration amount corresponding to the original image C0 is zero, the second allowable difference ΔPL is also equal to the allowable value PL0 of astigmatism. The order of visually recognizing the original image C0 or blurred images C1 to Cn is not limited to the order of increasing blur amount from the original image C0, but may be the order of decreasing blur amount from the blurred image Cn having the largest blur amount, or may be a random order.

[0073] In the above-mentioned embodiment, the wearer's binocular vision recognizes the original image C0 or blurred images C1 to Cn, the reference blurred image Cp, or blurred images Cp+1, Cp+2, ..., but the present invention is not limited thereto. For example, the wearer's binocular vision may be made to recognize an image (for example, an image corresponding to blurred images C1 to Cn, the reference blurred image Cp, or blurred images Cp+1, Cp+2, ...) which is blurred by giving aberration to an actual lens such as a follower.

[0074] In the above embodiment, one eye is set as the right eye and the other eye is set as the left eye, but the present invention is not limited thereto. One eye may be set as the left eye and the other eye may be set as the right eye.

[0075] Description of symbols 1 pair of eyeglass lenses 10R: Right eye lens 10L: Left eye lens

Claims

1. A sensitivity evaluation method comprising: The right eye and the left eye are caused to visually recognize the image with different blur amounts; as well as Information related to sensitivity to a difference in blur amount between images visually recognized by the right eye and the left eye is acquired.

2. The sensitivity evaluation method according to claim 1, wherein: The sensitivity evaluation method includes: causing one of the right eye and the left eye to visually recognize a first image with a predetermined blur amount, and causing the other of the right eye and the left eye to visually recognize a second image with a blur amount greater than the predetermined blur amount; acquiring information related to sensitivity to a difference in blur amount between the second image visually recognized by the other eye and the first image visually recognized by the one eye; causing the other eye to visually recognize the first image with the predetermined blur amount, and causing the one eye to visually recognize the second image with a blur amount greater than the predetermined blur amount; and Information related to sensitivity to a difference in blur amount between the second image visually recognized by the one eye and the first image visually recognized by the other eye is acquired.

3. The sensitivity evaluation method according to claim 2, wherein: The sensitivity evaluation method includes: causing the right eye and the left eye to visually recognize a third image with the same blur amount, and obtaining information related to sensitivity to the blur amount of the third image visually recognized by the right eye and the left eye; and The predetermined blur amount is set based on information related to the sensitivity of the blur amount of the third image.

4. The sensitivity evaluation method according to claim 3, wherein: The information on the sensitivity to the blur amount of the third image is information on the maximum value of the blur amount of the third image that allows visual recognition by both the right eye and the left eye, that is, both eyes.

5. The sensitivity evaluation method according to claim 2, wherein: The sensitivity evaluation method includes setting the predetermined blur amount to zero.

6. The method for evaluating sensitivity according to any one of claims 1 to 5, wherein: The information on the sensitivity to the difference in blur amount is information on the maximum value of the difference in blur amount that allows visual recognition by the right eye and the left eye, that is, by both eyes.

7. A method for manufacturing a pair of spectacle lenses, the pair of spectacle lenses consisting of a right-eye spectacle lens for a right eye and a left-eye spectacle lens for a left eye, wherein: The method for manufacturing the pair of spectacle lenses comprises: The right eye and the left eye are caused to visually recognize the image with different blur amounts; acquiring information related to sensitivity to a difference in blur amount between images visually recognized by the right eye and the left eye; performing design of the right-eye spectacle lens and the left-eye spectacle lens based on information related to the sensitivity to the difference in blur amount; and The right-eye spectacle lens and the left-eye spectacle lens are manufactured based on the design.

8. The method for manufacturing a pair of eyeglass lenses according to claim 7, wherein: The method for manufacturing the pair of spectacle lenses comprises: causing one of the right eye and the left eye to visually recognize a first image with a predetermined blur amount, and causing the other of the right eye and the left eye to visually recognize a second image with a blur amount greater than the predetermined blur amount; acquiring information related to sensitivity to a difference in blur amount between the second image visually recognized by the other eye and the first image visually recognized by the one eye; causing the other eye to visually recognize the first image with the predetermined blur amount, and causing the one eye to visually recognize the second image with a blur amount greater than the predetermined blur amount; and acquiring information related to sensitivity to a difference in blur amount between the second image visually recognized by the one eye and the first image visually recognized by the other eye, The right-eye spectacle lens and the left-eye spectacle lens are designed based on information related to sensitivity to the difference in blur amount between the second image visually recognized by the other eye and the first image visually recognized by the one eye, and information related to sensitivity to the difference in blur amount between the second image visually recognized by the one eye and the first image visually recognized by the other eye.

9. The method for manufacturing a pair of spectacle lenses according to claim 7 or 8, wherein: The information related to the sensitivity to the difference in blur amount is information related to a maximum value of the difference in blur amount that allows visual recognition by the right eye and the left eye, that is, by both eyes, The right-eye spectacle lens and the left-eye spectacle lens are designed as follows: the larger the maximum value of the difference in the blur amount that can be visually recognized by the two eyes, the smaller the aberration of the ear-side portion of the right-eye spectacle lens is than the aberration of the nose-side portion of the left-eye spectacle lens, and the smaller the aberration of the ear-side portion of the left-eye spectacle lens is than the aberration of the nose-side portion of the right-eye spectacle lens.

10. The method for manufacturing a pair of eyeglass lenses according to claim 9, wherein: The right-eye spectacle lens has a right-eye distance portion, and the right-eye distance portion has an optical power suitable for long-distance observation. The left-eye spectacle lens has a left-eye distance portion, and the left-eye distance portion has an optical power suitable for long-distance observation. The right-eye spectacle lens and the left-eye spectacle lens are designed in the following manner: the larger the maximum value of the difference in the blur amount that can be visually recognized by the two eyes, the smaller the aberration of the ear-side portion of the far vision portion for the right eye than the aberration of the nose-side portion of the far vision portion for the left eye, and the smaller the aberration of the ear-side portion of the far vision portion for the left eye than the aberration of the nose-side portion of the far vision portion for the right eye.

11. The method for manufacturing a pair of eyeglass lenses according to claim 10, wherein: The right-eye spectacle lens comprises: a right-eye near portion having an optical power suitable for near-distance observation; and a right-eye progressive portion, which is arranged between the right-eye distance portion and the right-eye near portion, and the optical power of which varies between the optical power of the right-eye distance portion and the optical power of the right-eye near portion. The left-eye eyeglass lens comprises: a near portion for the left eye, having an optical focal length suitable for close-up observation; and a progressive portion for the left eye, which is arranged between the distance portion for the left eye and the near portion for the left eye, and the optical focal length varies between the optical focal length of the distance portion for the left eye and the optical focal length of the near portion for the left eye.

Images