Method for designing contact lens

Abstract

A method for designing a contact lens according to the present disclosure comprises: a step for setting a diameter value for each of three zones in a clearance formation area and a diameter value for each of two zones in a fitting formation area; a step for setting a sagittal depth value for the entire clearance formation area and a sagittal depth value for each of the three zones in the clearance formation area using the set diameter value for each of the three zones in the clearance formation area; and a step for setting a curvature radius value for each of the three zones in the clearance formation area and a curvature radius value for each of the two zones in the fitting formation area using the set diameter values and the set sagittal depth values.

Description

Contact lens design methods 【0001】 This disclosure relates to a method for designing contact lenses for vision correction. 【0002】 There are contact lenses for vision correction that are supported on the sclera and prescribed without contact with the cornea, generally known as scleral contact lenses (see, for example, Patent Document 1). Scleral contact lenses are suitable for cases where lens fitting and vision correction are difficult with conventional contact lenses, such as keratoconus, corneal damage, and post-LASIK complications. 【0003】 Special table 2018-517181 publication 【0004】 Scleral contact lenses tend to be more difficult to shape compared to regular contact lenses. 【0005】 Therefore, it is desirable to provide a contact lens design method that allows for the easy prescription of scleral contact lenses. 【0006】A contact lens design method according to one embodiment of the present disclosure is a contact lens design method having a clearance forming area that acts on vision correction and a fitting forming area formed around the clearance forming area and acting on fitting, wherein three zones are set in the clearance forming area: an optical zone, a peripheral first clearance curve zone formed around the optical zone, and a peripheral second clearance curve zone formed around the peripheral first clearance curve zone; two zones are set in the fitting forming area: a fitting curve zone formed around the clearance forming area and a peripheral curve zone formed around the fitting curve zone; a first step of setting the diameter value of the optical zone and the diameter value of the peripheral second clearance curve zone or the diameter value of the peripheral curve zone; and the respective diameter values ​​of the three zones of the clearance forming area. The method includes: a second step of setting the diameter value of each of the two zones of the fitting formation area, excluding the diameter value of the peripheral second clearance curve zone set in the first step, or the diameter value of the peripheral curve zone and the diameter value of the optical zone; a third step of setting the total sagittal depth value of the clearance formation area and the sagittal depth values ​​of each of the three zones of the clearance formation area using the diameter values ​​of each of the three zones of the clearance formation area set in the first and second steps; a fourth step of setting the radius of curvature value of each of the three zones of the clearance formation area using the respective diameter values ​​set in the first and second steps and the respective sagittal depth values ​​set in the third step; and a fifth step of setting the radius of curvature value of each of the two zones of the fitting formation area after the fourth step. 【0007】In a contact lens design method according to one embodiment of the present disclosure, among a plurality of parameters constituting the contact lens, first, the diameter values ​​of each of the three zones of the clearance formation area and the diameter values ​​of each of the two zones of the fitting formation area are set. Next, using the set diameter values ​​of each of the three zones of the clearance formation area, the sagittal depth value of the entire clearance formation area and the sagittal depth values ​​of each of the three zones of the clearance formation area are set. Next, using the set diameter values ​​and the set sagittal depth values, the radius of curvature values ​​of each of the three zones of the clearance formation area and the radius of curvature values ​​of each of the two zones of the fitting formation area are set. 【0008】 Figure 1 is a cross-sectional view showing an example of a contact lens configuration to which a design method according to one embodiment of this disclosure is applied. Figure 2 is an explanatory diagram showing an example of a plurality of parameters used in the contact lens design method according to one embodiment. Figure 3 is an explanatory diagram showing an example of a plurality of parameters used in the contact lens design method according to one embodiment. Figure 4A is a flowchart showing a specific example of the contact lens design method according to one embodiment. Figure 4B is a flowchart following Figure 4A. Figure 5 is an explanatory diagram showing a specific example of setting the overall Sag value of the clearance formation area. Figure 6 is an explanatory diagram showing an example of a method for adjusting the Sag value of each part of the clearance formation area. Figure 7 is an explanatory diagram showing an example of a matrix table used for selecting the radius of curvature of the fitting curve zone. Figure 8 is an explanatory diagram showing an overview of edge lift. Figure 9 is a top view showing an example of a method for setting the fitting formation area. 【0009】 The embodiments of this disclosure will be described in detail below with reference to the drawings. The description will be in the following order: 1. One Embodiment 1.1 Overview of the Contact Lens 1.2 Description of the Design Method 1.2.1 Overview of the Design Method 1.2.2 Specific Example of the Design Method 1.3 Example of Design Numerical Values ​​1.4 Effects 2. Other Embodiments 【0010】<1. One Embodiment> [1.1 Overview of Contact Lenses] Figure 1 is a cross-sectional view showing an example of the configuration of a contact lens 1 to which the design method according to one embodiment of the present disclosure is applied. 【0011】 The design method according to one embodiment is applicable to contact lenses 1, which generally belong to a category called scleral contact lenses. 【0012】 Scleral contact lenses generally refer to lenses that are supported on the sclera and prescribed with clearance on the cornea. Scleral contact lenses have the advantage of correcting vision in cases of irregular corneal shapes by creating a tear film between the cornea and the lens. However, lenses that are supported not only on the sclera but also partially on the cornea, depending on their size, may also be recognized as a type of scleral contact lens. There are various theories, but they can be classified by lens diameter, for example, as follows: In the following, a scleral contact lens classified as a miniscleral may be used as an example of a numerical example, but the design method for one embodiment is not limited to miniscleral lenses. Furthermore, the design method for one embodiment is applicable not only to scleral contact lenses but also to orthokeratology lenses, etc. 12.5 mm to 15.0 mm: Corneoscleral (corneal sclera) 15.0 mm to 18.0 mm: Miniscleral 18.0 mm or more: Full scleral (maximum of about 26 mm) 【0013】 The contact lens 1 has a clearance-forming area A1 that acts to correct vision, and a fitting-forming area A2 formed around the clearance-forming area A1 that acts to fit. 【0014】The clearance-forming area A1 includes the optical zone OZ and the peripheral clearance zone. The peripheral clearance zone consists of a peripheral first clearance curve zone 11 formed around the optical zone OZ and a peripheral second clearance curve zone 12 formed around the peripheral first clearance curve zone 11. In other words, the clearance-forming area A1 consists of three zones: the optical zone OZ, the peripheral first clearance curve zone 11, and the peripheral second clearance curve zone 12. 【0015】 The fitting formation area A2 consists of two zones: a fitting curve zone 21 formed around the clearance formation area A1 (around the peripheral second clearance curve zone 12), and a peripheral curve zone 22 formed around the fitting curve zone 21. 【0016】 As described above, the contact lens 1 has a base curve BC surface that includes a zone of 5 curves, and is configured to be divided into two main areas: the clearance-forming area A1 with 3 curves from the center, and the fitting-forming area A2 with 2 curves around the periphery. 【0017】 Figures 2 and 3 are explanatory diagrams showing an example of multiple parameters used in a design method for a contact lens 1 according to one embodiment. 【0018】 A method for designing a contact lens 1 according to one embodiment includes a step of setting a plurality of parameters that indicate the shape of the contact lens 1. The plurality of parameters that indicate the shape of the contact lens 1 include R1, R2, R3, R4, R5, which indicate the radius of curvature of each part of the contact lens 1, and W1, W2, W3, W4, W5, which indicate the diameter of each part of the contact lens 1. Furthermore, the plurality of parameters that indicate the shape of the contact lens 1 include the sagittal depth values ​​(hereinafter referred to as Sag values) TS, S1, S2, S3 of each part of the contact lens 1. 【0019】Here, TS represents the Sag value of the entire clearance formation area A1, S1 represents the Sag value of the optical zone OZ, S2 represents the Sag value of the peripheral first clearance curve zone 11, and S3 represents the Sag value of the peripheral second clearance curve zone 12. 【0020】 Also, W1 represents the diameter of the optical zone OZ, W2 represents the diameter of the peripheral first clearance curve zone 11, and W3 represents the diameter of the clearance formation area A1 (the diameter of the peripheral second clearance curve zone 12). W4 represents the diameter of the fitting curve zone 21, and W5 represents the diameter of the peripheral curve zone 22 (the overall diameter of the contact lens 1, the overall diameter of the fitting formation area A2). 【0021】 R1 represents the radius of curvature of the optical zone OZ, R2 represents the radius of curvature of the peripheral first clearance curve zone 11, R3 represents the radius of curvature of the peripheral second clearance curve zone 12, R4 represents the radius of curvature of the fitting curve zone 21, and R5 represents the radius of curvature of the peripheral curve zone 22. 【0022】 [1.2 Explanation of the Design Method] (1.2.1 Outline of the Design Method) In the design method of the contact lens 1 according to an embodiment, by limiting the adjustment method of some values among the plurality of parameters required for the design of the clearance formation area A1, the simplicity of the prescription system is improved. The Sag component of each part of the clearance formation area A1 is directly involved in the clearance component with the cornea in the prescription. The clearance formation area A1 is an area that acts on vision correction and is set to a shape that is non-contact with the cornea. 【0023】In addition, in the design method of the contact lens 1 according to an embodiment, the simplicity of the prescription system is improved by restricting the adjustment method of some of the values of a plurality of parameters required for the design of the fitting formation area A2. The radial (radius of curvature) component of each part of the fitting formation area A2 is directly involved in the fitting with the strong membrane in the prescription. The fitting formation area A2 is set to a shape that is supported on the strong membrane. That is, the contact lens 1 is supported on the strong membrane by the fitting formation area A2. 【0024】 FIGS. 4A and 4B are flowcharts showing a specific example of the design method of the contact lens 1 according to an embodiment. 【0025】 The design method according to an embodiment includes a step of setting three zones, namely an optical zone OZ, a peripheral first clearance curve zone 11, and a peripheral second clearance curve zone 12, in the clearance formation area A1, and setting two zones, namely a fitting curve zone 21 and a peripheral curve zone 22, in the fitting formation area A2 (first step). The first step also includes a step of setting the value of the diameter W1 of the optical zone OZ and the value of the diameter W3 of the peripheral second clearance curve zone 12, or the value of the diameter W5 of the peripheral curve zone 22 (step ST1 in FIG. 4A). 【0026】Furthermore, the design method according to one embodiment includes a step of setting the diameter values ​​of the peripheral second clearance curve zone 12, or the diameter value of the peripheral curve zone 22, and the diameter value of the optical zone OZ, from among the multiple parameters constituting the contact lens 1, specifically the diameter values ​​W1 to W3 of the three zones of the clearance formation area A1 and the diameter values ​​W4 and W5 of the two zones of the fitting formation area A2, excluding the diameter value W3 of the peripheral second clearance curve zone 12, or the diameter value W5 of the peripheral curve zone 22, and the diameter value W1 of the optical zone OZ, which were set in the first step (Step ST1 (second step) in Figure 4A). Furthermore, after the second step, the method includes a step of setting the overall Sag value TS of the clearance formation area A1 and the Sag values ​​S1 to S3 of the three zones of the clearance formation area A1, using the diameter values ​​W1 to W3 of the three zones of the clearance formation area A1 set in the first and second steps (Step ST2 (third step) in Figure 4A). Next, after the third step, the process includes setting the values ​​of the curvature radii R1 to R3 for each of the three zones of the clearance formation area A1 using the values ​​of the diameters W1 to W5 set in the first and second steps and the values ​​of the Sag values ​​TS, S1 to S3 set in the third step (step ST5 in Figure 4A (fourth step)). Next, after the fourth step, the process includes setting the values ​​of the curvature radii R4 and R5 for each of the two zones of the fitting formation area A2 (step ST5 in Figure 4A (fifth step)). 【0027】 In the design method according to one embodiment, the settings of several parameters required for design are set in a sequential manner so that the prescription of the contact lens 1 can be easily performed. In general contact lens design methods, the design is performed in the order of size (diameter) → radius of curvature → Sag value. The value of the radius of curvature is generally set before the Sag value. Also, the Sag value is generally determined to determine the overall Sag value of the contact lens 1. For the size (diameter), it is generally determined first by determining the diameter W5 of the peripheral curve zone 22 (the overall diameter of the contact lens 1). 【0028】(1.2.2 A Specific Example of a Design Method) Below, a specific example of a design method for contact lens 1 will be explained according to each step of the flowchart in Figures 4A and 4B. 【0029】 In one embodiment of the design method, a reference lens may be prepared in advance prior to design, and the contact lens 1 may be designed by changing some of the values ​​of a plurality of parameters constituting the reference lens in limited steps. The reference lens itself may also be designed using the design method according to one embodiment. In designing the reference lens, the diameter W1 of the optical zone OZ may be set to an arbitrary value between 6.0 mm and 12.0 mm, for example, considering general optical characteristics according to the case. In designing the reference lens, the values ​​of diameters W2 to W5 may also be set from the viewpoint of lens positional stability (centering) and wearability. The values ​​of the diameters W2 to W5 of the reference lens may be set to default values ​​predetermined from, for example, a general case, corneal shape, etc. The values ​​of the radius of curvature R1 to R5 and the Sag values ​​TS, S1, S2 may be set in accordance with these values ​​of diameters W1 to W5. 【0030】 (Step ST1: Setting the size (diameter) of each zone (first and second steps)) In the design method according to one embodiment, in the first step, the value of the diameter W1 of the optical zone OZ may be set to a fixed value, and the value of the diameter of any one of the zones other than the optical zone OZ may be set to a value that is changed by a predetermined step value from the reference value according to the case. The value of the diameter of any one of the zones may be the value of the diameter W3 of the peripheral second clearance curve zone 12 (diameter of the clearance formation area A1), or the value of the diameter W5 of the peripheral curve zone 22 (overall diameter of the contact lens 1). In addition, in the second step, the values ​​of the diameters of each zone excluding the value of the diameter W3 of the peripheral second clearance curve zone 12, or the value of the diameter W5 of the peripheral curve zone 22 and the value of the diameter W1 of the optical zone OZ may be set to a value calculated based on a predetermined diameter calculation formula using a predetermined amount of change. 【0031】A specific example is given below. First, it is assumed that the initial reference values ​​of the reference lens described above are set as the values ​​of diameter W1 to W5. 【0032】 (When the value of diameter W5 is varied as a reference) In this case, in the design method according to one embodiment, the value of diameter W1 of the optical zone OZ is set to a fixed value as the initial reference value, and the value of diameter W5 of the peripheral curve zone 22 is set to a value that is varied by x (mm) as a predetermined step value from the initial reference value of diameter W5, according to the case. Next, the values ​​of diameters W2 to W5 are modified (set) from the initial reference value based on the following predetermined diameter calculation formula using x (mm), which is the amount of variation. In the calculation of other parameters thereafter, the modified (set) diameters W2' to W5' are used as the new reference values ​​for diameters W2 to W5. W2' = W2 + x / 3 W3' = W3 + 2x / 3 W4' = W4 + x W5' = W5 + x 【0033】 (When the value of diameter W3 is varied as a reference) In this case, in the design method according to one embodiment, the value of diameter W1 of the optical zone OZ is set to a fixed value as the initial reference value, and the value of diameter W3 of the clearance formation area A1 is set to a value that is varied by x (mm) as a predetermined step value from the initial reference value of diameter W3, according to the case. Next, the values ​​of diameters W2 to W5 are modified (set) from the initial reference value based on the following predetermined diameter calculation formula using x (mm), which is the amount of variation. In the calculation of other parameters thereafter, the modified (set) diameters W2' to W5' are used as the new reference values ​​for diameters W2 to W5. W2' = W2 + x / 2 W3' = W3 + x W4' = W4 + 1.5x W5' = W5 + 1.5x 【0034】 (Step ST2: Setting the Sag value for each zone in clearance formation area A1 (third step)) 【0035】In one embodiment of the design method, in the third step, a reference value for the overall Sag value TS of the clearance formation area A1 is calculated using a predetermined calculation formula based on the value of the diameter W3 (diameter of the clearance formation area A1) of the peripheral second clearance curve zone 12 set in the first or second step. Next, the Sag value S1 of the optical zone OZ is set to a predetermined reference value. Then, the Sag value S2 of the peripheral first clearance curve zone 11 and the Sag value S3 of the peripheral second clearance curve zone 12 are set to values ​​calculated based on a predetermined calculation formula using the calculated Sag value TS, the Sag value S1 set as a predetermined reference value, and the respective diameter values ​​of the three zones of the clearance formation area A1 set in the first and second steps. 【0036】 A specific example is shown below. Figure 5 is an explanatory diagram showing a specific example of setting the overall Sag value TS of the clearance formation area A1. 【0037】 In one embodiment of the design method, for example, the reference value of the overall Sag value TS of the clearance formation area A1 with respect to the diameter W3 of the clearance formation area A1 (set in step ST1) is calculated using the following predetermined calculation formula: a is the shortest distance from a point on the circumference of a circle with radius b to the target clearance point (the vertex position on the back surface of the clearance formation area A1), and can take values ​​of, for example, 1.0 mm to 3.0 mm. b is the scleral radius of the eyeball 100, which is calculated from the average value of the eyeball diameter, and can take values ​​of, for example, 10.0 mm to 13.0 mm. As an example, as shown in Figure 5, when a = 1.8 mm, b = 11.5 mm, and W3 = 13.8 mm, the reference Sag value TS = 4.1 mm. In the following formulas, "SQRT" indicates the square root. As the final value of the Sag value TS, for example, two decimal places are rounded to one decimal place. TS=(b+a)-SQRT(b ２ - (W3 / 2) ２ ) 【0038】In the design method according to one embodiment, the reference Sag value S1 is set to a predetermined value, for example, S1 = 2.0 mm. In the design method according to one embodiment, the values ​​of the reference Sag values ​​S2 and S3 are calculated and set using the following predetermined formulas with respect to the reference Sag values ​​TS and S1 and the corresponding diameters W1 to W3 (set in step ST1). S2 = (TS - S1) × ((W2 - W1) / 2) / ((W3 - W1) / 2) S3 = (TS - S1) × ((W3 - W2) / 2) / ((W3 - W1) / 2) 【0039】 In the design method according to one embodiment, next, for example, it is determined whether or not adjustment of the Sag value is necessary depending on the case (step ST3). If adjustment of the Sag value is necessary (step ST3; Y), the Sag value is adjusted (step ST4). On the other hand, if adjustment of the Sag value is not necessary (step ST3; N), the design method according to one embodiment proceeds to step ST5. 【0040】 (Step ST4: Adjustment of Sag Values ​​(Sixth Step)) In one embodiment of the design method, a sixth step may be included after the third step in which each Sag value set in the third step is changed. In the sixth step, after changing the Sag value TS set in the third step by a predetermined step value change, the Sag value S1 may be changed by distributing the predetermined step value change in a predetermined ratio between the Sag value S1 and the Sag value (S2 + S3) of the zone formed by combining the peripheral first clearance curve zone 11 and the peripheral second clearance curve zone 12. Next, the Sag values ​​S2 and S3 may be changed to values ​​calculated based on a predetermined calculation formula, based on the changed Sag value TS, the changed Sag value S1, and the respective diameter values ​​of the three zones of the clearance formation area A1 set in the first and second steps. 【0041】 A specific example is shown below. Figure 6 is an explanatory diagram showing an example of a method for adjusting the Sag value of each part of the clearance formation area A1. 【0042】In one embodiment of the design method, for example, any problems with wearing the contact lens 1 associated with a particular case may be adjusted solely by changing the Sag value without changing the diameter of each part. In one embodiment of the design method, if it is necessary to change the overall Sag value TS of the clearance formation area A1 in relation to a particular case, the current Sag value TS can be changed within a limited range of values. The amount of change in the Sag value TS to be changed is set to a predetermined step value. For example, as shown in Figure 6, the amount of change in the Sag value TS is set to a predetermined step value of ±0.20 mm. 【0043】 Furthermore, in the design method according to one embodiment, the Sag value TS is changed by a predetermined step value of ±0.20 mm, and then the change in the Sag value TS after the change of ±0.20 mm is distributed to the optical zone OZ portion (Sag value S1) at a rate of ±0.1 mm and to "Sag value S2 + Sag value S3" at a rate of ±0.1 mm. The individual values ​​of the changed Sag value S2 and the changed Sag value S3 are calculated using the changed Sag values ​​TS and S1 from the same calculation formula as in step ST2 above. By limiting the numerical value of the change, the simplicity of formulation is improved. 【0044】(Step ST5: Setting the radius of curvature R1 to R5 for each zone (the fourth and fifth steps)) In the design method according to one embodiment, in the fourth step, the value of the radius of curvature of each of the three zones in the clearance formation area A1 is set to a value calculated based on a predetermined calculation formula using the value of the diameter of each of the three zones in the clearance formation area A1 set in the first and second steps and the value of each sagittal depth set in the third step. Also, in the fifth step, the value of the radius of curvature R4 of the fitting curve zone 21 may be set to a value selected from a group of numerical values set according to the correlation between the calculated value of the radius of curvature R1 of the optical zone OZ and the value of the diameter W5 of the peripheral curve zone 22 set in the second step. Next, the value of the radius of curvature R5 of the peripheral curve zone 22 may be calculated and set based on a predetermined calculation formula (Formula (1) described later) using the selected value of the radius of curvature R4 of the fitting curve zone 21, the values of the diameters of the two zones in the fitting formation area A2 set in the first or second step, and the edge lift (EL) described later. 【0045】 The following shows a specific example. In the design method according to one embodiment, first, based on the following predetermined calculation formula using the values of the diameters W1, W2, and W3 of each of the three zones in the clearance formation area A1 set so far and the Sag values TS, S1, S2, and S3, the radii of curvature R1 to R3 of each of the three zones in the clearance formation area A1 are calculated and set. As the final value of R1, for example, round off to three decimal places and use up to two decimal places. R1 = ((W1 / 2) ２ + S1 ２ ) / (2 × S1) R2 = SQRT(((((W1 / 2) ２ -(W2 / 2) ２ + S1 ２ -(S1 + S2) ２ ) / (2 × -S2)) - (S1 + S2)) ２ +(W2 / 2) ２ ) R3 = SQRT(((((W2 / 2) ２ -(W3 / 2) ２ +(S1 + S2)２ - (TS) ２ ) / (2×((S1+S2)-TS))-TS)) ２ + (W3 / 2) ２ ) 【0046】 Figure 7 is an explanatory diagram showing an example of a matrix table used to select the radius of curvature R4 of the fitting curve zone 21. 【0047】 Next, in the design method according to one embodiment, the value of the radius of curvature R4 of the fitting curve zone 21 is set to a value selected in accordance with the eye condition (case) from a set of numerical values ​​(matrix table in Figure 7) that have been set in advance based on the correlation between the radius of curvature R1 and the diameter W5. 【0048】 Next, in the design method according to one embodiment, the value of the radius of curvature R5 of the peripheral curve zone 22 is set to a value calculated using the following predetermined formula, which is obtained by using the previously determined radius of curvature R4 of the fitting curve zone 21 and the respective diameters W4 and W5 of the two zones of the fitting formation area A2. Here, EL is the edge lift. R5 = SQRT((SQRT((R4 + EL) ２ - (W5 / 2) ２ )-(((W4 / 2) ２ - (W5 / 2) ２ + (SQRT(R4 ２ - (W4 / 2) ２ )) ２ -(SQRT((R4+EL) ２ - (W5 / 2) ２ )) ２ ) / (2×(SQRT(R4 ２ - (W4 / 2) ２ )-SQRT((R4+EL) ２ - (W5 / 2) ２ ))))) ２ + (W5 / 2) ２ ) ...(Formula 1) 【0049】Figure 8 is an explanatory diagram illustrating the overview of edge lift (EL). Edge lift refers to a numerical value that indicates how much the curvature of the edge of the contact lens 1 (in this case, the peripheral curve zone 22) is changed (or has been changed) relative to the curvature of the zone in front of it (in this case, the fitting curve zone 21). The value is not limited to a specific number. 【0050】 (Step ST7: Shape adjustment of fitting formation area A2 (7th and 8th steps)) In the design method according to one embodiment, after the 5th step, for example, it may be determined whether or not shape adjustment of fitting formation area A2 is necessary depending on the case (Step ST6), and if shape adjustment is necessary (Step ST6; Y), shape adjustment may be performed (Step ST7, 7th and 8th steps). On the other hand, if shape adjustment is not necessary (Step ST6; N), the process is terminated. 【0051】 A design method according to one embodiment may further include a seventh step, after the fifth step, in which the value of the radius of curvature R4 of the fitting curve zone 21 set in the fifth step is changed by a predetermined step value change amount according to the case, and then the value of the radius of curvature R5 of the peripheral curve zone 22 set in the fifth step is recalculated and changed based on a predetermined calculation formula ((Formula 1)) used in the fifth step. 【0052】 Furthermore, after the fifth step, an eighth step may be included in which, depending on the case, multiple divided regions are set in the circumferential direction of the fitting formation area A2, and for each divided region, the value of the radius of curvature R4 of the fitting curve zone 21 set in the fifth step and the value of the radius of curvature R5 of the peripheral curve zone 22 set in the fifth step are changed. 【0053】 Figure 9 is a top view showing an example of how to set the fitting formation area A2. A specific example of adjusting the shape of the fitting formation area A2 will be explained with reference to Figure 9. 【0054】The width Wz4 of the fitting curve zone 21 and the width Wz5 of the peripheral curve zone 22 (the width of each annular zone) may remain constant regardless of changes in the diameter, Sag value, and radius of curvature of each part of the contact lens 1. Alternatively, the values ​​of the widths Wz4 and Wz5 may be kept constant while changing the radii of curvature R4 and R5 and the diameters W4 and W5 of the fitting curve zone 21 and peripheral curve zone 22, respectively. 【0055】 Furthermore, in the design method according to one embodiment, depending on the case, multiple divided regions with different values ​​of the radius of curvature R4 of the fitting curve zone 21 and the radius of curvature R5 of the peripheral curve zone 22 may be set in the circumferential direction of the fitting formation area A2, and the multiple divided regions may be joined at predetermined curve transition points. In Figure 9, as an example, an example is shown in which the fitting curve zone 21 is divided into four divided regions 21a, 21b, 21c, and 21d. Similarly, an example is shown in which the peripheral curve zone 22 is divided into four divided regions 22a, 22b, 22c, and 22d. Note that the number of divisions and the size of the divided regions are not limited to the example in Figure 9. 【0056】 The radii of curvature R4 and R5 may be modified by specifying a division area in the circumferential direction. The division area in the circumferential direction can be specified, for example, by specifying an angle. This angle may be set to 0° at the rightmost edge when viewed from the prescriber's perspective, similar to the angle chordography commonly used in ophthalmology, and the angle may be increased counterclockwise. 【0057】 To improve the fitting state, when the value of the radius of curvature R4 of the fitting curve zone 21 is changed by one step, the amount of change is defined as "y" (y = radius of curvature value: R value). For example, different amounts of change can be given to the four divided regions 21a, 21b, 21c, and 21d, as shown below. Here, the values ​​of the radius of curvature R4 in the four divided regions 21a, 21b, 21c, and 21d of the fitting curve zone 21 are R4a, R4b, R4c, and R4d, respectively. R4a = R4 - y R4b = R4 + y R4c = R4 - 2y R4d = R4 + 3y 【0058】 Using the values ​​of the radius of curvature R4 (R4a, R4b, R4c, R4d) for each of the four divided regions 21a, 21b, 21c, and 21d of the newly defined fitting curve zone 21, the values ​​of the radius of curvature R5 for each of the four divided regions 22a, 22b, 22c, and 22d of the peripheral curve zone 22 are recalculated using the above calculation formula (Equation 1). Here, the recalculated values ​​of the radius of curvature R5 for each of the four divided regions 22a, 22b, 22c, and 22d of the peripheral curve zone 22 are denoted as R5a, R5b, R5c, and R5d. 【0059】 For example, the value of the radius of curvature R5a of the divided region 22a is recalculated as follows: R5a = SQRT((SQRT((R4a + EL) ２ - (W5 / 2) ２ )-(((W4 / 2) ２ - (W5 / 2) ２ +(SQRT(R4a ２ - (W4 / 2) ２ )) ２ -(SQRT((R4a+EL) ２ - (W5 / 2) ２ )) ２ ) / (2×(SQRT(R4a ２ - (W4 / 2) ２ )-SQRT((R4a+EL) ２ - (W5 / 2) ２ ))))) ２ + (W5 / 2) ２ ) 【0060】 [1.3 Examples of Design Numerical Values] Below are examples of design numerical values ​​according to the design method of one embodiment. 【0061】(Step ST1: When varying based on the value of diameter W5) The following is an example of design values ​​when changing the values ​​of diameters W2 to W5 by changing the value of diameter W5 in the peripheral curve zone 22 from W5 = 16.4 mm to W5' = 17.6 mm, with a change amount x = 1.2 mm. The values ​​of diameters W2 to W5 before the change are W2 = 12.2 mm, W3 = 13.8 mm, W4 = 15.4 mm, and W5 = 16.4 mm. 16.4 → 17.6, W5 change amount = 1.2 W2' = W2 + 1.2 / 3 = 12.6 W3' = W3 + (2 × 1.2) / 3 = 14.6 W4' = W4 + 1.2 = 16.6 W5' = W5 + 1.2 = 17.6 【0062】 (Step ST1: When varying based on the value of diameter W3) The following is an example of design values ​​when changing the values ​​of diameters W2 to W5 by changing the value of diameter W3 of the clearance formation area A1 from W3 = 13.8 mm to W3' = 14.6 mm, with a change amount x = 0.8 mm. The values ​​of diameters W2 to W5 before the change are W2 = 12.2 mm, W3 = 13.8 mm, W4 = 15.4 mm, and W5 = 16.4 mm. W2' = W2 + 0.8 / 2 = 12.6 W3' = W3 + 0.8 = 14.6 W4' = W4 + (1.5 × 0.8) = 16.6 W5' = W5 + (1.5 × 0.8) = 17.6 【0063】 If the size changes, the value of the diameter W3 of the clearance formation area A1 changes, so the overall Sag value TS of the reference clearance formation area A1 is recalculated. As the reference Sag value TS changes, the Sag values ​​S2 and S3 also change, so the radii of curvature R2 and R3 are also recalculated. The radius of curvature R4 is also selected from the matrix table in Figure 7 and changed if necessary. The radius of curvature R5 is recalculated even if the radius of curvature R4 does not change, because the values ​​of the diameters W4 and W5 change. 【0064】 (Step ST4: Specific example of adjusting the Sag value) The following is an example of design values ​​when changing the values ​​of Sag values ​​S1 to S3 by changing the Sag value TS from TS = 4.1 mm to TS' = 4.3 mm, with a change amount X = +0.2 mm. Assume that S1 = 2.0 mm and S2 + S3 = 2.1 mm before the change. S1' = S1 + X / 2 = 2.1 mm S2' + S3' = S2 + S3 + X / 2 = 2.2 mm 【0065】 The following are examples of design values ​​when the modified Sag values ​​TS' and S1' are changed to TS and S1, and the modified Sag values ​​S2 and S3 are calculated using the same formula as in step ST2 above. S2 = (TS - S1) × ((W2 - W1) / 2) / ((W3 - W1) / 2) = 1.4000 S3 = (TS - S1) × ((W3 - W2) / 2) / ((W3 - W1) / 2) = 0.8000 【0066】 The specific design values ​​for the radii of curvature R1 to R5 can be calculated using the above design values ​​and the design method described in step ST5. 【0067】 [1.4 Effects] As described above, according to the design method for a contact lens 1 according to one embodiment, among the multiple parameters constituting the contact lens 1, first, the values ​​of the diameters W1 to W3 of the three zones of the clearance formation area A1 and the values ​​of the diameters W4 and W5 of the two zones of the fitting formation area A2 are set. Next, using the set values ​​of the diameters W1 to W3 of the three zones of the clearance formation area A1, the overall Sag value TS of the clearance formation area A1 and the Sag values ​​S1 to S3 of the three zones of the clearance formation area A1 are set. Next, using the set values ​​of the diameters W1 to W5 and the set values ​​of the Sag values ​​TS and S1 to S3, the values ​​of the radii of curvature R1 to R3 of the three zones of the clearance formation area A1 and the values ​​of the radii of curvature R4 and R5 of the two zones of the fitting formation area A2 are set. Thus, the settings of multiple parameters required for the design of contact lens 1 can be changed only for three limited parameters (lens size, clearance, and fitting), and by simply selecting from a limited range of step values, other peripheral parameters are linked and determined to reasonable values ​​for scleral contact lens design. This design method makes it possible to easily prescribe scleral contact lenses. 【0068】This application claims priority based on Japanese Patent Application No. 2024-216020, filed with the Japan Patent Office on 10 December 2024, and all contents of that application are incorporated herein by reference. 【0069】 Those skilled in the art will understand that various modifications, combinations, subcombinations, and changes can be conceived depending on design requirements and other factors, and that these fall within the scope of the attached claims and their equivalents.

Claims

1. A method for designing a contact lens having a clearance-forming area that acts on vision correction and a fitting-forming area formed around the clearance-forming area that acts on fitting, comprising: setting three zones in the clearance-forming area: an optical zone, a peripheral first clearance curve zone formed around the optical zone, and a peripheral second clearance curve zone formed around the peripheral first clearance curve zone; setting two zones in the fitting-forming area: a fitting curve zone formed around the clearance-forming area, and a peripheral curve zone formed around the fitting curve zone; and setting the diameter value of the optical zone and the diameter value of the peripheral second clearance curve zone, or the diameter value of the peripheral curve zone. A second step of setting the diameter values ​​of each of the three zones of the clearance forming area and the diameter values ​​of each of the two zones of the fitting forming area, excluding the diameter value of the peripheral second clearance curve zone set in the first step, or the diameter value of the peripheral curve zone and the diameter value of the optical zone; a third step of setting the sagittal depth value of the entire clearance forming area and the sagittal depth value of each of the three zones of the clearance forming area using the diameter values ​​of each of the three zones of the clearance forming area set in the first and second steps; a fourth step of setting the radius of curvature value of each of the three zones of the clearance forming area using the respective diameter values ​​set in the first and second steps and the respective sagittal depth values ​​set in the third step; A method for designing a contact lens, comprising the fourth step of setting the radius of curvature values ​​of the two zones of the fitting formation area after the fourth step.

2. The method for designing a contact lens according to claim 1, wherein in the first step, the diameter of the optical zone is set to a fixed value, and the diameter of the peripheral second clearance curve zone, or the diameter of the peripheral curve zone, is set to a value that is varied from a reference value by a predetermined step value according to the case.

3. The method for designing a contact lens according to claim 2, wherein in the second step, the diameter value of the peripheral second clearance curve zone set in the first step, or the diameter values ​​of each zone excluding the diameter value of the peripheral curve zone and the diameter value of the optical zone, are set to values ​​calculated based on a predetermined diameter calculation formula using the predetermined step value change amount.

4. The method for designing a contact lens according to claim 1, wherein in the third step, a reference value for the total sagittal depth of the clearance forming area is calculated using a predetermined formula based on the diameter value of the peripheral second clearance curve zone set in the first step or the second step, the sagittal depth of the optical zone is set to a predetermined reference value, and the sagittal depth of the peripheral first clearance curve zone and the sagittal depth of the peripheral second clearance curve zone are set to values ​​calculated based on a predetermined formula using the calculated total sagittal depth of the clearance forming area, the sagittal depth of the optical zone set as a predetermined reference value, and the respective diameter values ​​of the three zones of the clearance forming area set in the first step and the second step.

5. A sixth step, after the third step, of changing the sagittal depth values ​​set in the third step, wherein in the sixth step, after changing the sagittal depth value of the entire clearance formation area set in the third step by a predetermined step value change, the sagittal depth value of the optical zone is changed by distributing the predetermined step value change in a predetermined proportion between the sagittal depth value of the optical zone and the sagittal depth value of the zone formed by combining the peripheral first clearance curve zone and the peripheral second clearance curve zone, A method for designing a contact lens according to claim 4, wherein the sagittal depth value of the peripheral first clearance curve zone and the sagittal depth value of the peripheral second clearance curve zone are changed to values ​​calculated based on a predetermined calculation formula, based on the total sagittal depth value of the modified clearance forming area, the sagittal depth value of the modified optical zone, and the respective diameter values ​​of the three zones of the clearance forming area set in the first and second steps.

6. The method for designing a contact lens according to claim 1, wherein in the fourth step, the value of the radius of curvature of each of the three zones of the clearance forming area is set to a value calculated based on a predetermined formula using the diameter values ​​of each of the three zones of the clearance forming area set in the first and second steps and the sagittal depth values ​​set in the third step.

7. The contact lens design method according to claim 6, wherein in the fifth step, the value of the radius of curvature of the fitting curve zone is set to a value selected from a group of numerical values ​​set based on the correlation between the calculated value of the radius of curvature of the optical zone and the value of the diameter of the peripheral curve zone set in the first or second step, and the value of the radius of curvature of the peripheral curve zone is calculated and set based on a predetermined calculation formula using the selected value of the radius of curvature of the fitting curve zone and the respective diameter values ​​of the two zones of the fitting formation area set in the first or second step.

8. A method for designing a contact lens according to claim 7, further comprising: a seventh step, after the fifth step, changing the value of the radius of curvature of the fitting curve zone set in the fifth step by a predetermined step value change amount according to the case, and then recalculating and changing the value of the radius of curvature of the peripheral curve zone set in the fifth step based on the predetermined calculation formula used in the fifth step.

9. A method for designing a contact lens according to claim 7, further comprising, after the fifth step, setting a plurality of divided regions in the circumferential direction of the fitting formation area according to the case, and changing the value of the radius of curvature of the fitting curve zone set in the fifth step and the value of the radius of curvature of the peripheral curve zone set in the fifth step for each of the divided regions.

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