A method for designing the optical zone of multifocal soft contact lenses

Abstract

The present invention discloses a method for designing optical zones of multifocal soft contact lenses, wherein the optical zones include a farsighted optical zone, a progressive optical zone arranged in the outer circumference of the farsighted optical zone, and an alternating optical zone arranged in the outer circumference of the progressive optical zone, and the design method steps are as follows: Step 1: Obtain the farsighted diopter of the farsighted optical zone and the optical data of the lens, and calculate the convex farsighted base curve curvature radius of the farsighted optical zone of the contact lens; Step 2: Obtain the defocus amount of the progressive optical zone, and calculate the aspheric coefficient of the progressive optical zone using a formula; Step 3: Obtain several alternating diopter of the alternating area of ​​the alternating optical zone, optimize the spherical aberration of the alternating optical zone by an aspheric surface, and calculate the aspheric coefficient of the alternating optical zone. The present invention is a scheme of multifocal design by setting different optical zones, which can eliminate the peripheral hyperopic defocus of the human eye, thereby delaying the rapid growth of the eye axis, achieving the purpose of controlling myopia, and the discomfort of peripheral focal changes when the pupil is dilated at night.

Description

Technical Field

[0001] The invention relates to the technical field of contact lens design, and in particular to an optical zone design method of a multifocal soft contact lens. Background Art

[0002] In addition to orthokeratology lenses that can delay the progression of myopia, peripheral defocus soft lenses are also an option, especially for those whose diopter exceeds the optimal range that can be corrected by orthokeratology lenses. The correction principle of multifocal soft lenses is to make the front surface of the contact lens similar to the shape of the cornea after orthokeratology. When wearing such contact lenses, the same myopia control effect as orthokeratology can be achieved. Therefore, multifocal soft lenses are often called soft orthokeratology lenses.

[0003] Existing designs often have a relatively small optical zone diameter. When the pupil dilates at night, there is often some discomfort due to the rapid change in peripheral focal length. In addition, the curvature radius of each ring in the design is often spherical. When encountering patients with high degrees of defocus, the marginal spherical aberration is particularly obvious, reducing the effect of eliminating peripheral hyperopic defocus. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art. To achieve the above purpose, a method for designing the optical zone of a multifocal soft contact lens is adopted to solve the problems raised in the above background technology.

[0005] A method for designing an optical zone of a multifocal soft contact lens, wherein the optical zone comprises a distance optical zone, a progressive optical zone disposed circumferentially outside the distance optical zone, and an alternating optical zone disposed circumferentially outside the progressive optical zone. The steps of the optical zone design method are as follows:

[0006] Step 1: Obtain the distance optical power of the distance optical zone, the curvature radius of the concave base curve of the contact lens, the center thickness of the lens, and the refractive index of the lens, and calculate the curvature radius of the convex base curve of the distance optical zone of the contact lens;

[0007] Step 2: Obtain the distance diopter of the distance optical zone and the defocus amount of the progressive optical zone, and calculate the progressive diopter of the progressive optical zone;

[0008] Calculate the equivalent spherical curvature radius of the progressive optical zone based on the progressive diopter, the curvature radius of the concave base curve of the contact lens, the center thickness of the lens, and the refractive index of the lens;

[0009] Obtaining the diameter of the progressive optical zone and the equivalent spherical curvature radius of the progressive optical zone, and calculating the sagittal height of the equivalent sphere;

[0010] According to the obtained convex surface base curve radius of curvature and the sagittal height of the equivalent sphere, the aspheric coefficient of the progressive optical zone is calculated;

[0011] Step 3: Obtain several alternating photometric values ​​of the alternating regions of the alternating optical zone, optimize the spherical aberration of the alternating optical zone through the aspheric surface, and calculate the aspheric coefficient of the alternating optical zone.

[0012] As a further solution of the present invention: the calculation of the convex far base curve curvature radius R of the contact lens is FBC0 The specific calculation formula is:

[0013]

[0014] Among them, R BBC is the curvature radius of the concave base curve, ct L is the center thickness of the lens, n L is the refractive index of the lens, and PW0 is the distance power.

[0015] As a further solution of the present invention: the specific calculation steps of step 2 include:

[0016] First, obtain the defocus value PW d And the far-distance diopter PW0, calculate the progressive diopter PW1 of the progressive optical zone as PW1 = PW0 + PW d ;

[0017] According to the following formula and the obtained progressive light power PW1, calculate the equivalent spherical curvature radius R of the progressive optical zone FBC1 :

[0018]

[0019] Among them, R BBC is the curvature radius of the concave base curve, ct L is the center thickness of the lens, n L is the refractive index of the lens;

[0020] Then obtain the diameter of the progressive optical zone and calculate the sag of the equivalent sphere of the progressive optical zone 渐 :

[0021]

[0022] Then calculate the aspheric coefficient K of the progressive optical zone FBC1 :

[0023]

[0024] Wherein, FOZ1 is the diameter of the progressive optical zone.

[0025] As a further solution of the present invention: the step of calculating the aspheric coefficient of the alternating optical zone in step 3 comprises:

[0026] Acquiring a plurality of alternating photometric values ​​of alternating regions of the alternating optical zones, wherein the plurality of alternating photometric values ​​are alternatingly equal;

[0027] Using several alternating photometric and aspheric surfaces to optimize the spherical aberration in alternating optical zones;

[0028] According to the spherical aberration of the alternating optical zones after optimization and correction, the aspheric coefficients of the corresponding alternating zones are determined.

[0029] As a further solution of the present invention: the specific steps of optimizing the spherical aberration of the alternating optical zones by using a plurality of alternating photometric and aspherical surfaces include:

[0030] Optimize spherical aberration by using aspheric design based on several alternating equal photometric values;

[0031] Obtain the incident height h, the curvature ρ of the convex surface, and the focal length f of the lens, and substitute them into the spherical aberration formula to obtain the optimized and corrected spherical aberration;

[0032] Then, according to the following formula, the optimized lens brightness is obtained:

[0033]

[0034] Then calculate the aspheric coefficients of each alternating area corresponding to the corrected spherical aberration.

[0035] As a further solution of the present invention: the spherical aberration formula is:

[0036]

[0037] in, is the incident height, FOZ2 is the diameter of the alternating optical zone, n L is the refractive index of the lens, ρ is the curvature of the convex surface, and f is the focal length of the lens.

[0038] Compared with the prior art, the present invention has the following technical effects:

[0039] By adopting the above technical solution, the optical zone of the contact lens is designed in a regional manner, including a farsighted optical zone, a progressive optical zone, and an alternating optical zone. At the same time, the aspheric coefficients of different optical zones are determined according to the different luminosities required by different optical zones. Thus, the design method of each optical zone is realized. By setting a multifocal design scheme for different optical zones, the peripheral hyperopic defocus of the human eye can be eliminated, thereby delaying the rapid growth of the eye axis and achieving the purpose of controlling myopia. It can also solve the discomfort caused by the rapid change of peripheral focal power when the pupil is dilated at night. At the same time, the spherical aberration at the edge is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings:

[0041] Figure 1 A schematic diagram of the steps of the optical zone design method according to some embodiments disclosed in the present application;

[0042] Figure 2 It is a schematic diagram of the optical zone structure of the contact lens of some embodiments disclosed in the present application;

[0043] Figure 3 It is a schematic cross-sectional structural diagram of contact lenses of some embodiments disclosed in the present application;

[0044] Figure 4 A schematic diagram of spherical aberration when the height of the spherical surface design in the prior art is shown;

[0045] Figure 5 Schematic diagram of the high degree of spherical aberration of the aspheric surface design of some embodiments disclosed in this application.

[0046] In the figure: 10, distance optical zone; 20, progressive optical zone; 30, alternating optical zone. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] Please refer to Figure 1 and Figure 2 In an embodiment of the present invention, a method for designing an optical zone of a multifocal soft contact lens comprises:

[0049] like Figure 2 As shown, the optical zone includes a distance optical zone, a progressive optical zone arranged on the outer circumference of the distance optical zone, and an alternating optical zone arranged on the outer circumference of the progressive optical zone. The production and manufacturing of soft contact lenses are also divided into concave and convex surfaces. The design of the concave surface is generally consistent with that on the market, and the base curve of the concave surface is approximately 8.30-8.80mm. The present invention mainly achieves the effect of light intensity requirements through the design of the convex surface.

[0050] like Figure 1 As shown, the design method steps of the optical zone are as follows:

[0051] Step 1: Obtain the distance optical power of the distance optical zone, the curvature radius of the concave base curve of the contact lens, the center thickness of the lens, and the refractive index of the lens, and calculate the curvature radius of the convex base curve of the distance optical zone of the contact lens;

[0052] Specifically, the main function of the distance optical zone is to correct myopia. Figure 3 As shown, the distance optical power of the distance optical zone, the curvature radius of the concave base curve of the contact lens, the center thickness of the lens, and the refractive index of the lens are all known. During production, the curvature radius of the convex distance base curve is obtained, thereby facilitating the production and identification of the distance optical zone.

[0053] The calculation of the convex surface of the contact lens is based on the base curve curvature radius R FBC0 The specific calculation formula is:

[0054]

[0055] Among them, R BBC is the curvature radius of the concave base curve, ct L is the center thickness of the lens, n L is the refractive index of the lens, and PW0 is the distance power.

[0056] Step 2: Obtain the distance optical power of the distance optical zone and the defocus amount of the progressive optical zone, and calculate the progressive optical power of the progressive optical zone; specifically, by obtaining the defocus amount PW d And the above-mentioned far-distance diopter PW0, the progressive diopter PW1 of the progressive optical zone is calculated as PW1 = PW0 + PW d Among them, the defocus amount PW d Its value range is 0~5D. It is mainly realized by aspherical surface.

[0057] Calculate the equivalent spherical curvature radius R of the progressive optical zone based on the progressive diopter applicable to the progressive optical zone, the concave base curve radius of the contact lens, the center thickness of the lens, and the refractive index of the lens. FBC1 :

[0058]

[0059] Among them, R BBC is the curvature radius of the concave base curve, ct L is the center thickness of the lens, n L is the refractive index of the lens;

[0060] Get the diameter of the progressive optical zone and the equivalent spherical curvature radius of the progressive optical zone, and calculate the sag of the equivalent sphere of the progressive optical zone 渐 :

[0061]

[0062] According to the obtained convex far base curve curvature radius and equivalent spherical height, calculate the aspheric coefficient K of the progressive optical zone. FBC1 :

[0063]

[0064] Among them, FOZ1 is the diameter of the progressive optical zone, and the specific value range is 4 to 6 mm.

[0065] Step 3: Obtaining a plurality of alternating photometric values ​​of the alternating regions of the alternating optical zone, optimizing the spherical aberration of the alternating optical zone by the aspheric surface, and calculating the aspheric coefficient of the alternating optical zone comprises:

[0066] Obtain a plurality of alternating photometric values ​​of an alternating region of an alternating optical zone, and the plurality of alternating photometric values ​​are alternatingly equal; the alternating region is composed of a plurality of photometric values, {PW0=PW2=PW4=…=PW N-1};

[0067] {PW1=PW3=PW5=…=PW N ,3≤N≤20}.

[0068] like Figure 4 As shown in the figure, the existing design uses the same spherical design, and the spherical aberration is obvious at high degrees. Figure 5 As shown in the figure, the spherical aberration of the alternating optical zone is optimized by using an aspheric surface design. The spherical aberration of the alternating optical zone is optimized by using a number of alternating photometric and aspheric surfaces. The specific steps include:

[0069] Optimize spherical aberration by using aspheric design based on several alternating equal photometric values;

[0070] Obtain the incident height h, the curvature ρ of the convex surface, and the focal length f of the lens, and substitute them into the spherical aberration formula to obtain the optimized and corrected spherical aberration;

[0071] Then, according to the following formula, the optimized lens brightness is obtained:

[0072]

[0073] Then calculate the aspheric coefficients of each alternating area corresponding to the corrected spherical aberration.

[0074] The primary spherical aberration formula is:

[0075]

[0076] in, is the incident height, FOZ2 is the diameter of the alternating optical zone, n L is the refractive index of the lens, ρ is the curvature of the convex surface, and f is the focal length of the lens.

[0077] According to the spherical aberration of the alternating optical zone after optimization and correction, the corresponding aspheric coefficient of each alternating zone is determined. That is, h is half of the corresponding diameter of the optical zone of the lens, that is:

[0078] Get the curvature of the convex surface of the distance and progressive optical zones and the focal length of the lens:

[0079]

[0080]

[0081] Substituting into the primary spherical aberration formula, we can get: SP0 and δ SP1 .

[0082] At the same time, according to the optical principle, the optimized lens brightness is:

[0083]

[0084]

[0085]

[0086]

[0087] Similarly, by using optical knowledge, the aspheric coefficients of each alternating area corresponding to the corrected spherical aberration can be obtained.

[0088] Get the equivalent spherical curvature radius of each alternating area:

[0089]

[0090]

[0091] Get the vector height of the equivalent sphere in each alternating area:

[0092]

[0093]

[0094] Finally, the aspheric coefficients of each alternating area are obtained:

[0095]

[0096]

[0097] The data obtained at the same time needs to meet the following conditions in this design:

[0098] R FBC2 =R FBC4 =......=R FBCN ; R FBC3 =R FBC5 =......=R FBCN+1 ;

[0099] K FBC2 =K FBC4 =......=K FBCN ; K FBC3 =K FBC5 =......=K FBCN+1 ;

[0100] like Figure 3 FOZ0 is the diameter of the far optical zone, which ranges from 2 to 5 mm; FOZ2 is the diameter of the alternating optical zone, which ranges from 6 to 9 mm; the widths of the rings in the alternating zones are equal, W1 = W2 = ... = W N .

[0101] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents, and all should be included within the scope of protection of the present invention.

Claims

1. A method for designing an optical zone of a multifocal soft contact lens, characterized in that: The optical zone includes a distance optical zone, a progressive optical zone disposed in the outer circumference of the distance optical zone, and an alternating optical zone disposed in the outer circumference of the progressive optical zone. The steps of the design method of the optical zone are as follows: Step 1: Obtain the distance optical power of the distance optical zone, the curvature radius of the concave base curve of the contact lens, the center thickness of the lens, and the refractive index of the lens, and calculate the curvature radius of the convex base curve of the distance optical zone of the contact lens; Step 2: Obtain the distance diopter of the distance optical zone and the defocus amount of the progressive optical zone, and calculate the progressive diopter of the progressive optical zone; Calculate the equivalent spherical curvature radius of the progressive optical zone based on the progressive diopter, the curvature radius of the concave base curve of the contact lens, the center thickness of the lens, and the refractive index of the lens; Obtaining the diameter of the progressive optical zone and the equivalent spherical curvature radius of the progressive optical zone, and calculating the sagittal height of the equivalent sphere; According to the obtained convex surface base curve radius of curvature and the sagittal height of the equivalent sphere, the aspheric coefficient of the progressive optical zone is calculated; The specific calculation steps of step 2 include: First, obtain the defocus value PW d And the far-distance diopter PW0, calculate the progressive diopter PW1 of the progressive optical zone as PW1 = PW0 + PW d ; According to the following formula and the obtained progressive light power PW1, calculate the equivalent spherical curvature radius R of the progressive optical zone FBC1 : Among them, R BBC is the curvature radius of the concave base curve, ct L is the center thickness of the lens, n L is the refractive index of the lens; Then obtain the diameter of the progressive optical zone and calculate the sag of the equivalent sphere of the progressive optical zone 渐 : Then calculate the aspheric coefficient K of the progressive optical zone FBC1 : Among them, FOZ1 is the diameter of the progressive optical zone; Step 3: obtaining a number of alternating photometric values ​​of the alternating regions of the alternating optical zone, optimizing the spherical aberration of the alternating optical zone by the aspheric surface, and calculating the aspheric coefficient of the alternating optical zone; Step 3 The steps of calculating the aspheric coefficients of the alternating optical zones include: Acquiring a plurality of alternating photometric values ​​of alternating regions of the alternating optical zones, wherein the plurality of alternating photometric values ​​are alternatingly equal; The specific steps of optimizing the spherical aberration of the alternating optical zones by using a number of alternating photometric and aspheric surfaces include: Optimize spherical aberration by using aspheric design based on several alternating equal photometric values; Obtain the incident height h, the curvature ρ of the convex surface, and the focal length f of the lens, and substitute them into the spherical aberration formula to obtain the optimized and corrected spherical aberration; Then, according to the following formula, the optimized lens brightness is obtained: Then calculate the aspheric coefficients of each alternating area corresponding to the corrected spherical aberration; According to the spherical aberration of the alternating optical zones after optimization and correction, the aspheric coefficients of the corresponding alternating zones are determined.

2. The method for designing the optical zone of a multifocal soft contact lens according to claim 1, characterized in that: The calculation of the convex surface of the contact lens is based on the base curve curvature radius R FBC0 The specific calculation formula is: Among them, R BBC is the curvature radius of the concave base curve, ct L is the center thickness of the lens, n L is the refractive index of the lens, and PW0 is the distance power.

3. The method for designing the optical zone of a multifocal soft contact lens according to claim 1, characterized in that: The spherical aberration formula is: in, is the incident height, FOZ2 is the diameter of the alternating optical zone, n L is the refractive index of the lens, ρ is the curvature of the convex surface, and f is the focal length of the lens.

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