Edge-improved design method

Abstract

The invention relates to the technical field of contact lenses, in particular to an edge-improved design method. The method comprises the following steps: defining lens parameters: determining the curvature radius R convex 1 of the convex surface of an optical region according to the luminosity of the lens, and calculating the rise Sag convex 1 of the convex surface; designing a middle arc section R convex 2; and a transition arc section R convex 3 is introduced. By introducing the middle arc section R bulge 2 and the transition arc section R bulge 3 and optimizing the arc section connecting mode, even if the edge of the inner surface of the lens is tilted, the peripheral thickness of the lens can be reduced, the comfort degree is improved, the peripheral thickness ET is accurately controlled to be 0.3 mm-0. 6mm, the wearing pressure distribution is more uniform, meanwhile, the edge tilting height is reduced through the smooth transition arc section R bulge 3, and the wearing comfort degree is improved. The tear exchange rate is improved, the cornea oxygen deficit risk is reduced, sharp corner depression is eliminated, the stress concentration area is reduced, the lens breakage rate is reduced, the design of the transition arc section width BFW2 avoids a narrow and deep annular band, and the cleaning efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of contact lenses, in particular to an edge-improved design method. Background Art

[0002] Both scleral and corneoscleral lenses offer advantages over corneal lenses. Keratoconus and limbal degeneration can cause irregularities in the corneal surface, but scleral lenses can cover these irregularities and restore a smooth front surface, allowing clear vision when light enters the eye. For patients with damaged corneal tissue, scleral lenses can create a reservoir of fluid behind the lens, which protects the cornea and may even aid healing. Furthermore, corneal lenses can easily become displaced or even shifted, while scleral and corneoscleral lenses, because they span the upper and lower eyelids, are less likely to shift.

[0003] In addition, it is generally believed that large-diameter scleral lenses are more comfortable than corneal lenses. Part of the reason is that scleral lenses are not easy to slide in the eye. When they do not slide, the exchange of tears in the lens is relatively less easy than that of corneal lenses. If tears are not exchanged for a long time after wearing scleral lenses, some complications may occur. In order to solve the problem of tear exchange, the design of scleral lenses will change the last edge arc on the inner surface of the lens to be more raised. The raised edge arc changes the problem of tear exchange. However, because the convex surface of existing scleral lenses mainly adopts a two-segment arc design, the mid-circumference thickness of the lens increases accordingly, which is accompanied by a decrease in comfort. Summary of the Invention

[0004] The purpose of the present invention is to provide an edge-improved design method to solve the problem of reduced comfort after flattening the edge arc proposed in the above background technology.

[0005] To achieve the above object, the present invention provides an edge improvement design method, comprising the following steps: S1. Define lens parameters: Determine the convex curvature radius R of the optical zone according to the lens power 凸1 , and calculate its vector height Sag 凸1 ; S2. Design the middle arc segment R 凸2 : Solve the curvature radius R of the middle arc segment 凸2 , to control the thickness ET of the mid-periphery; S3, introduce transition arc R 凸3 : Solve the transition arc curvature radius R 凸3 , to smoothly connect the middle arc segment with the edge arc segment; S4. Optimize edge connection: Ensure that the width of the transition arc meets the requirements to eliminate lens edge depression and stress concentration.

[0006] Compared with the prior art, the present invention has the following beneficial effects:

[0007] 1. Significantly improved comfort: The mid-circumference thickness ET is precisely controlled at 0.3mm-0.6mm, which is 30% lower than the traditional design (ET≥0.7mm), and the wearing pressure is more evenly distributed.

[0008] 2. Optimization of tear exchange efficiency: smooth transition arc (R 凸3 ) Reduce the height of the edge lift, increase the tear exchange rate by 20%, and reduce the risk of corneal hypoxia.

[0009] 3. Enhanced durability: Sharp corners and depressions are eliminated, stress concentration areas are reduced by 50%, and the lens breakage rate is reduced by 40%.

[0010] 4. Improved cleaning efficiency: The transition arc width BFW2 design avoids narrow and deep rings, and the cleaning efficiency is increased by 35%.

[0011] 5. Simplified manufacturing process: The three-stage turning of the CNC lathe (optical area, middle arc segment, edge arc segment) reduces the processing steps and increases the yield rate to 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a design diagram of the thickness of the mid-circumference area of ​​the present invention.

[0013] Figure 2 This is the design diagram for the existing mid-circumference thickness.

[0014] Figure 3 This is a comparison diagram of the thickness of the middle peripheral area of ​​the present invention and the existing one.

[0015] Figure 4 Schematic diagram of the lens CNC lathe turning process of the present invention. DETAILED DESCRIPTION

[0016] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0017] In a specific embodiment, Figure 1 As shown, the present invention provides an edge improvement design method, comprising the following steps:

[0018] The first step is to define the lens parameters: determine the convex curvature radius R of the optical zone according to the lens power 凸1 , and calculate its vector height Sag 凸1 .

[0019] CT is the center thickness of the lens, ranging from 0.08mm to 0.60mm. The range of CT values ​​can be further divided according to the lens power requirements. ET is the parameter that satisfies the control of lens edge thinning. Designers need to consider the durability of the lens and also the material and power of the lens. This article provides selection suggestions: Table 1 is the reference parameters for lens brightness selection Serial number Lens material Lens power Lens center thickness range Recommended ET thickness 1 Good toughness, can be bent to a certain extent Low degree (100 degrees 500 degrees) Negative degree: 0.25mm-0.40mm Positive degree: 0.25mm-0.40mm 0.3mm-0.35mm 2 Good toughness, can be bent to a certain extent Medium degree (500 degrees 1000 degrees) Negative degree: 0.13mm-0.30mm Positive degree: 0.25mm-0.45mm 0.35mm-0.40mm 3 Good toughness, can be bent to a certain extent Altitude (1000 degrees 2000 degrees) Negative degree: 0.08mm-0.15mm Positive degree: 0.45mm-0.60mm 0.40mm-0.45mm 4 Brittle, easy to break when bent Low degree (100 degrees 500 degrees) Negative degree: 0.25mm-0.40mm Positive degree: 0.25mm-0.40mm 0.4mm-0.45mm 5 Brittle, easy to break when bent Medium degree (500 degrees 1000 degrees) Negative degree: 0.13mm-0.30mm Positive degree: 0.25mm-0.45mm 0.45mm-0.50mm 6 Brittle, easy to break when bent Altitude (1000 degrees 2000 degrees) Negative degree: 0.08mm-0.15mm Positive degree: 0.45mm-0.60mm 0.50mm-0.60mm ;

[0020] Step 2: Design the middle arc segment R 凸2 .

[0021] The curvature radius R of the middle arc segment is solved by the following formulas: 凸3 , to control the thickness ET of the periphery to 0.3mm-0.6mm: ;

[0022] Among them, CT is the center thickness of the lens, Sag 凸 is the concave sag, Sag 凸2 is the sagittal height of the middle arc segment;

[0023] Among them, Sag 凸1 It can be obtained by the following formula: ;

[0024] R 凸1 is the radius of curvature of the convex surface of the lens optical zone; it is mainly determined by the lens's luminosity, which is an objective parameter required for patient fitting and is known. Once the luminosity is determined, then R 凸1 It is determined accordingly, and no special design is required by the designer. 凸1 The radius of curvature R of the convex surface of the lens optical zone 凸1 The vector height of

[0025] R 凸3 The radius of curvature of the convex surface of the lens periphery needs to be provided by the designer because the design of ET is different. 凸2 The numbers will be different, Sag 凸2 is the radius of curvature R of the convex surface of the lens optical zone 凸2 The vector height.

[0026] is the diameter of the optical zone of the lens; is the diameter of the lens's mid-circumference; K is the lens's aspheric factor, where 、 The designer can specify the parameters K according to the design. If the lens is aspherical, then K≠0; if the lens is spherical, then K=0;

[0027] R 凸4 is the radius of curvature of the convex surface of the lens edge area. Since the inner surface of the lens has been completely defined by the designer, R 凸1 The convex and concave surfaces of the lens edge need to be connected, so the curvature R of the convex surface of the edge area is determined by the light intensity. 凸4 It is also determined that no special design is required. The convex surface of the existing scleral lens is designed with two arcs, one of which is the R of the optical zone. 凸1 , the other section is the curvature radius of the connecting edge, so the designer cannot change the edge thickness of the existing scleral lens. The present invention first adds an R 凸2 design to realize the control of ET.

[0028] The range of the mid-peripheral thickness ET is dynamically adjusted according to the lens material and light intensity:

[0029] Tough material, low gloss (100-500 degrees): ET = 0.3mm-0.35mm;

[0030] Brittle material, high degree (1000-2000 degrees): ET = 0.5mm-0.6mm;

[0031] Step 3: Introduce transition arc R 凸3 .

[0032] The transition arc curvature radius R is solved by the following formulas: 凸3 , to smoothly connect the middle arc segment with the edge arc segment: ;

[0033] in, is the diameter of the optical zone (8.0-12.0 mm), The diameter of the mid-circumference area (12.5-18.0mm), the width of the upper half of the BFW1 transition arc, The diameter of the edge area (14.5-20.0mm), Sag 凸3a Sag is the upper half of the convex transition arc. 凸3b is the lower half of the convex transition arc height, R 凸4 It is the radius of curvature of the convex surface of the lens edge area.

[0034] Transition arc R 凸3 The curvature radius ranges from 5.0mm to 12.0mm, ensuring smooth connection of arc segments and uniform stress distribution.

[0035] Step 4: Optimize edge connections.

[0036] Ensure the width of the transition arc satisfy: ;

[0037] and = ×0.75 to eliminate lens edge depression and stress concentration.

[0038] Lens manufacturing is done by CNC lathe, such as Figure 4 As shown, the lens blank is rotated by the C-axis, and the X-axis and Y-axis are linked to feed the turning tool, and the optical area, the middle arc segment and the edge arc segment are turned in three sections.

[0039] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A design method for edge improvement, characterized in that: The following steps are involved: S1. Define lens parameters: Determine the convex curvature radius R of the optical zone according to the lens power 凸1 , and calculate its vector height Sag 凸1 ; S2. Design the middle arc segment R 凸2 : Solve the curvature radius R of the middle arc segment 凸2 , to control the thickness ET of the mid-periphery; S3, introduce transition arc R 凸3 : Solve the transition arc curvature radius R 凸3 , to smoothly connect the middle arc segment with the edge arc segment; S4. Optimize edge connection: Ensure that the width of the transition arc meets the requirements to eliminate lens edge depression and stress concentration.

2. The edge improvement design method according to claim 1, characterized in that: In step S2, the middle arc segment R is designed. 凸2 The specific operations are: The curvature radius R of the middle arc segment is solved by the following formulas: 凸2 , to control the thickness ET of the periphery to 0.3mm-0.6mm: ； Among them, CT is the center thickness of the lens, Sag 凸 is the convex sag, Sag 凹 is the concave sag, Sag 凸2 is the sagittal height of the middle arc segment, is the diameter of the optical zone, is the diameter of the mid-circumference area, K is a constant; Among them, Sag 凸1 It can be obtained by the following formula: 。 3. The edge improvement design method according to claim 2, characterized in that: The value range of the mid-peripheral thickness ET is dynamically adjusted according to the lens material and light intensity: Tough material, low gloss (100-500 degrees): ET = 0.3mm-0.35mm; Brittle material, high degree (1000-2000 degrees): ET = 0.5mm-0.6mm.

4. The edge improvement design method according to claim 2, characterized in that: In step S3, the transition arc segment R is introduced 凸3 The specific operations are: The transition arc curvature radius R is solved by the following formulas: 凸3 , to smoothly connect the middle arc segment with the edge arc segment: ； in, is the diameter of the optical zone (8.0-12.0 mm), The diameter of the mid-circumference area (12.5-18.0mm), is the edge area diameter (14.5-20.0mm), BFW1 is the width of the upper half of the transition arc, BFW2 is the width of the transition arc, Sag 凸3a Sag is the upper half of the convex transition arc. 凸3b is the lower half of the convex transition arc height, R 凸4 It is the radius of curvature of the convex surface of the lens edge area.

5. The edge improvement design method according to claim 4, characterized in that: The transition arc R 凸3 The curvature radius ranges from 5.0mm to 12.0mm, ensuring smooth connection of arc segments and uniform stress distribution.

6. The edge improvement design method according to claim 4, characterized in that: The specific operation of optimizing edge connections in step S4 is: Ensure that the transition arc width BFW2 satisfies: ； And BFW1=BFW2x0.75 to eliminate lens edge depression and stress concentration.

7. The edge improvement design method according to claim 1, characterized in that: The lens is manufactured by using a CNC lathe, which rotates the lens blank through the C axis and feeds the turning tool in conjunction with the X axis and Y axis, and turns the optical area, the middle arc segment and the edge arc segment in three sections.

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