Optimization design method of rigid corneal contact lens and rigid corneal contact lens

Abstract

The invention relates to an optimal design method of a hard corneal contact lens and the hard corneal contact lens. The method comprises the following steps: acquiring an original included angle of the front surface of the lens, wherein the original included angle of the front surface of the lens is used for representing an included angle between two adjacent arc segments on the front surface of the lens determined based on lens prescription parameters; judging whether the lens front surface original included angle needs to be optimized; if the original included angle of the front surface of the lens needs to be optimized, splitting at least one target arc section in two adjacent arc sections participating in forming the original included angle of the front surface of the lens into a first number of sub arc sections, and the width and rise of the target arc section are allocated to the first number of sub arc sections by taking the target that the new included angle of the front surface of the lens is closer to 180 degrees than the original included angle of the front surface of the lens, the width of any sub arc section is greater than or equal to a first threshold value and the included angle between any two adjacent sub arc sections is 170-190 degrees. Therefore, the original included angle of the front surface of the lens of the rigid corneal contact lens is optimally designed, so that the comfort can be improved.

Description

Technical Field

[0001] The present disclosure relates to the field of hard corneal contact lenses, and in particular to an optimized design of the front surface of a hard corneal contact lens. Background Art

[0002] In today's field of refractive correction and myopia control, hard contact lenses occupy a place with their unique advantages. Hard contact lenses can provide excellent visual effects, perform well in correcting vision, and bring clear and sharp visual experience to the wearer. At the same time, wearing hard contact lenses is also good for corneal health because it can provide high-quality tear and oxygen exchange. However, hard contact lenses are often not as well accepted in the market as soft contact lenses. One of the important reasons is the difference in comfort. In contrast, soft contact lenses are softer, fit the eyeball, and usually give people a more comfortable feeling when wearing them. However, due to the relatively hard material, hard contact lenses may make the wearer feel a foreign body sensation or even pain when they are first worn, which to a certain extent affects their promotion in the market.

[0003] Therefore, comfort is of vital importance for hard contact lenses. Only by continuously improving the comfort of hard contact lenses can more people be willing to choose them as a tool for refractive correction and myopia control. In order to achieve this goal, the industry is also constantly exploring and trying various methods to improve comfort. Summary of the invention

[0004] An object of the present disclosure is to optimize the front surface of a hard contact lens to improve comfort.

[0005] According to the first aspect of the present disclosure, there is provided a method for optimizing the design of a hard corneal contact lens, comprising: obtaining an original angle of the front surface of the lens, the original angle of the front surface of the lens being used to characterize the angle between two adjacent arc segments on the front surface of the lens determined based on lens prescription parameters; judging whether the original angle of the front surface of the lens needs to be optimized; if the original angle of the front surface of the lens needs to be optimized, splitting at least one target arc segment of two adjacent arc segments participating in forming the original angle of the front surface of the lens into a first number of sub-arc segments, and allocating the width and sagittal height of the target arc segment to the first number of sub-arc segments with the goal of making the new angle of the front surface of the lens closer to 180° than the original angle of the front surface of the lens, the width of any sub-arc segment being greater than or equal to a first threshold, and the angle between any two adjacent sub-arc segments being between 170° and 190°.

[0006] Optionally, the original angle of the front surface of the lens is the angle between the end of the optical area of ​​the front surface of the lens and the beginning of the peripheral area of ​​the front surface of the lens, and at least one target arc segment of two adjacent arc segments participating in forming the original angle of the front surface of the lens is split into a first number of sub-arc segments, including: splitting the peripheral area of ​​the front surface of the lens into a first number of sub-areas, each sub-area corresponds to a sub-arc segment.

[0007] Optionally, the first number is 3 to 12, and different sub-arc segments have the same width. If the original angle of the front surface of the lens is greater than 180°, the sagitta of the first number of sub-arc segments are arranged in a decreasing arithmetic sequence from inside to outside; if the original angle of the front surface of the lens is less than 180°, the sagitta of the first number of sub-arc segments are arranged in an increasing arithmetic sequence from inside to outside, and the level difference d of the arithmetic sequence satisfies: Wherein, N is equal to the first number.

[0008] Optionally, the first quantity is positively correlated with the absolute value of the difference between the original angle of the front surface of the lens and 180°.

[0009] Optionally, the original angle of the front surface of the lens is between 170° and 190°, the first number is 2, and different sub-arc segments have the same width. If the original angle of the front surface of the lens is greater than 180°, the sagittal height of the sub-arc segment relatively close to the center of the lens accounts for 61.8%, and the sagittal height of the sub-arc segment relatively close to the edge of the lens accounts for 38.2%. If the original angle of the front surface of the lens is less than 180°, the sagittal height of the sub-arc segment relatively close to the center of the lens accounts for 38.2%, and the sagittal height of the sub-arc segment relatively close to the edge of the lens accounts for 61.8%.

[0010] Optionally, the original angle of the front surface is less than 170° or greater than 190°, and the absolute value of the difference between the original angle of the front surface and 180° is less than a predetermined threshold value, the first number is 3, and different sub-arc segments have the same width. If the original angle of the front surface is greater than 180°, the sagitta of the sub-arc segment closest to the center of the lens accounts for 42% to 52%, the sagitta of the middle sub-arc segment accounts for 30% to 36%, and the sagitta of the sub-arc segment closest to the edge of the lens accounts for 18% to 22%. If the original angle of the front surface is less than 180°, the sagitta of the sub-arc segment closest to the center of the lens accounts for 18% to 23%, the sagitta of the middle sub-arc segment accounts for 31% to 36%, and the sagitta of the sub-arc segment closest to the edge of the lens accounts for 41% to 51%.

[0011] Optionally, allocating the width and the sag of the target arc segment to the first number of sub-arc segments includes: determining the width and the sag of each of the sub-arc segments based on the following formula:

[0012]

[0013] Among them, r(n) is the curvature radius of the nth sub-arc segment, S n is the sagittal height of the nth sub-arc segment, d n-1 is the inner diameter of the nth sub-arc segment, d n is the outer diameter of the nth sub-arc segment, A(n) is the angle between the nth sub-arc segment and the n+1th sub-arc segment, r n+1 is the curvature radius of the n+1th sub-arc segment.

[0014] Optionally, the method also includes: obtaining coordinate parameters of each of the sub-arc segments, the coordinate parameters including starting end coordinates and end end coordinates; inputting the coordinate parameters of each of the sub-arc segments into a CNC machining device in the form of a queue, and programming according to the coaxial circular arc interpolation method, so that the machining device completes the lens machining task through coaxial circular arc interpolation.

[0015] Optionally, the method further comprises: drawing a path diagram of the optimized designed lens, and delivering the path diagram to a numerical control processing device for processing the lens.

[0016] Optionally, the method further comprises: performing surface hydrophilization treatment on the lens material; and / or using a lens material with higher oxygen permeability; and / or performing thinning treatment on the edge of the lens.

[0017] According to a second aspect of the present disclosure, a hard corneal contact lens is provided, comprising a lens body, wherein a target arc segment located on the front surface of the lens of the lens body is split into a first number of sub-arc segments, the target arc segment is at least one arc segment of two adjacent arc segments participating in forming an original angle of the front surface of the lens, the original angle of the front surface of the lens is the front surface angle before optimization, and a new angle of the front surface of the lens formed after the splitting is closer to 180° than the original angle of the front surface of the lens, the width of any sub-arc segment is greater than or equal to a first threshold, and the angle between any two adjacent sub-arc segments is between 170° and 190°.

[0018] Optionally, the original angle of the front surface of the lens is the angle between the end of the optical area of ​​the front surface of the lens and the beginning of the peripheral area of ​​the front surface of the lens, and the target arc segment is the arc segment corresponding to the peripheral area of ​​the front surface of the lens.

[0019] Optionally, different sub-arc segments have the same width and different sag heights.

[0020] Optionally, the first number is 3 to 12, and if the original angle of the front surface of the lens is greater than 180°, the sagitta of the first number of sub-arc segments are arranged in a decreasing arithmetic progression from inside to outside; if the original angle of the front surface of the lens is less than 180°, the sagitta of the first number of sub-arc segments are arranged in an increasing arithmetic progression from inside to outside, and the level difference d of the arithmetic progression satisfies: Wherein, N is equal to the first number.

[0021] Optionally, the first quantity is positively correlated with the absolute value of the difference between the original angle of the front surface of the lens and 180°.

[0022] Optionally, the original angle of the front surface of the lens is between 170° and 190°, and the first number is 2. If the original angle of the front surface of the lens is greater than 180°, the sagittal height of the sub-arc segment relatively close to the center of the lens accounts for 61.8%, and the sagittal height of the sub-arc segment relatively close to the edge of the lens accounts for 38.2%. If the original angle of the front surface of the lens is less than 180°, the sagittal height of the sub-arc segment relatively close to the center of the lens accounts for 38.2%, and the sagittal height of the sub-arc segment relatively close to the edge of the lens accounts for 61.8%.

[0023] Optionally, the original angle of the front surface is less than 170° or greater than 190°, and the absolute value of the difference between the original angle of the front surface and 180° is less than a predetermined threshold value, and the first number is 3. If the original angle of the front surface is greater than 180°, the sagitta of the sub-arc segment closest to the center of the lens accounts for 42% to 52%, the sagitta of the middle sub-arc segment accounts for 30% to 36%, and the sagitta of the sub-arc segment closest to the edge of the lens accounts for 18% to 22%. If the original angle of the front surface is less than 180°, the sagitta of the sub-arc segment closest to the center of the lens accounts for 18% to 23%, the sagitta of the middle sub-arc segment accounts for 31% to 36%, and the sagitta of the sub-arc segment closest to the edge of the lens accounts for 41% to 51%.

[0024] Optionally, the first threshold is 0.2 mm.

[0025] Optionally, the angle between any two adjacent sub-arc segments is between 176° and 184°.

[0026] Optionally, the width and the sagittal height of each of the sub-arc segments are determined based on the following formula:

[0027]

[0028] Among them, r(n) is the curvature radius of the nth sub-arc segment, S n is the sagittal height of the nth sub-arc segment, d n-1 is the inner diameter of the nth sub-arc segment, d nis the outer diameter of the nth sub-arc segment, A(n) is the angle between the nth sub-arc segment and the n+1th sub-arc segment, r n+1 is the curvature radius of the n+1th sub-arc segment.

[0029] For the original angle of the front surface of the lens that needs to be optimized, the present disclosure divides at least one target arc segment of two adjacent arc segments that participate in forming the original angle of the front surface of the lens into a first number of sub-arc segments, and allocates the width and sagittal height of the target arc segment to the first number of sub-arc segments with the goal of making the new angle of the front surface of the lens closer to 180° than the original angle of the front surface of the lens, the width of any sub-arc segment is greater than or equal to the first threshold, and the angle between any two adjacent sub-arc segments is between 170° and 190°. In this way, the optimization design of the angle of the front surface of the lens can be achieved in a simple, easy and very effective way, thereby improving the comfort of wearing hard corneal contacts. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components in the exemplary embodiments of the present disclosure.

[0031] Figure 1 A flow chart of a method for optimizing the design of a hard corneal contact lens according to an embodiment of the present disclosure is shown.

[0032] Figure 2 , Figure 3 A schematic diagram showing the angle of the front surface of the lens.

[0033] Figure 4 , Figure 5 A schematic diagram showing the optimization of the angle of the front surface of the lens using three sub-arcs is shown. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0035] The discomfort when wearing contact lenses mainly comes from the collision and friction between the eyelids, cornea and lenses when blinking.

[0036] When you blink, the eyelid and lens move relative to each other, and the lens moves to a certain extent on the surface of the cornea.

[0037] This movement creates friction, just like a rough object rubbing against your skin, which can cause discomfort.

[0038] Especially the edge of the lens, if the design is unreasonable or not smooth enough, when it frequently contacts and rubs against the eyelids, the wearer will feel like there is a foreign body and feel very uncomfortable.

[0039] The commonly used comfort improvement methods are mainly the following.

[0040] First, optimize the lens design. The thinned and specially shaped edge design can effectively reduce the friction between the lens and the eyelid, thereby improving the wearing comfort.

[0041] Second, improve the material. Improve the hydrophilicity of the material surface to maximize the comfort of hard contact lenses while maintaining their optical properties.

[0042] Third, optimize lens fit. By improving the geometric design of the lens fit area, the movement of the lens on the cornea is reduced, thereby reducing the friction between the lens and the cornea and eyelid, and reducing the discomfort of wearing.

[0043] Fourth, use auxiliary medical devices or medicines such as lubricants to provide buffering and lubrication between the lens, eyelids, and cornea, while enhancing tear circulation, protecting corneal health and reducing discomfort.

[0044] Although these four types of improvement methods all have good effects, they also have their own shortcomings or limitations. Although thinning the edge of the lens can effectively reduce the impact and friction between the eyelid and the edge of the lens, the space for thinning the edge of the lens is limited. An overly thin edge design will greatly increase the difficulty of processing, and the lens is more likely to be damaged at the edge during wear and maintenance. Improving hydrophilicity can make the lens surface more lubricated and reduce friction and sluggishness when blinking. Plasma hydrophilic coating has become one of the standard processes for hard contact lenses, but its durability still needs to be improved. Adjusting the lens fit can reduce lens movement, thereby reducing friction with the cornea and eyelids, but it will also reduce the exchange of tears and oxygen, which is not good for corneal health. Auxiliary means such as lubricants are effective, but the durability is worse and leads to additional usage costs for the wearer.

[0045] In addition, although these four methods can cooperate with each other, they will also restrain each other. Hard contact lenses on the market today usually comprehensively consider and balance the use of the above four types of improvement methods in order to achieve the best comfort effect.

[0046] In summary, although hard contact lenses have advantages in visual effects and corneal health, their lack of comfort limits their market acceptance. By continuously exploring and applying comfort improvement methods, it is expected that the comfort of hard contact lenses will be improved, allowing them to play a greater role in the vision correction market.

[0047] The present disclosure provides a new method for improving the comfort of hard contact lenses, which is simple and easy to implement without any process difficulty. Moreover, the method can be used independently or in conjunction with the other four methods, making it easier to strike a balance between the comfort, safety and visual effect of hard contact lenses.

[0048] The present disclosure has found through research that the edges and corners of the front surface are one of the main causes of eyelid discomfort, especially for lenses with large positive and negative degrees, or multifocal lenses used for presbyopia correction or myopia control, this feeling is more obvious. Such edges and corners are an inherent problem faced by hard contact lenses, which is determined by the basic optical principles of lenses. Since the refractive power of the lens is mainly determined by the curvature radius of the front and back surfaces, the thickness difference between the center and the periphery of the lens with extreme degrees is large, resulting in edges and corners; and for zone-type multifocal lenses, due to the different degrees between zones, different degrees of edges and corners will also be generated.

[0049] Regardless of the shape of the edges and corners on the front surface of the lens, they will scratch the eyelids and even cause the lens to get stuck or tilted when moving, resulting in a foreign body sensation or even a stinging sensation, which greatly affects the comfort of wearing the lens. This public study found that the human eye is very sensitive to the angle. The closer the angle between the two arcs is to 180°, the less discomfort is caused when wearing. When the angle is less than 176° or greater than 184°, the human eye can clearly feel the presence of the lens, and when the angle is less than 170° or greater than 190°, a clear sense of discomfort will be felt when wearing it. Polishing the front surface of the lens can improve this problem to a certain extent, but its limitations are also very obvious. Polishing cannot handle more extreme angles, and over-polishing will seriously damage the most important optical performance of the lens. Therefore, optimizing the design of the angle of the front surface of the lens is a simple, easy and very effective improvement method.

[0050] In the present disclosure, the lens front surface angle that needs to be optimized may refer to the angle between any two adjacent arc segments on the lens front surface. For a single-focus lens, there is usually only one lens front surface angle that needs to be optimized (i.e., the angle between the edge of the optical area on the lens front surface and the peripheral area on the lens front surface), and for a multifocal lens, there may be several lens front surface angles that need to be optimized.

[0051] Through experiments, the present disclosure also found that the more outward the angle is, the more likely it is to cause discomfort. Firstly, this is because the contact with the eyelid is more frequent; secondly, this is because the angle itself is caused by the difference in curvature radius between the front and rear surfaces. The more outward the angle is, the stronger the tail effect is, so the angle is likely to be sharper.

[0052] Therefore, the present disclosure focuses on optimizing the angle of the front surface of the lens near the edge of the lens (e.g., the angle between the edge of the optical zone on the front surface of the lens and the peripheral zone on the front surface of the lens), while the angle of the front surface near the center of the lens (e.g., the angle within the optical zone on the front surface of the lens) may be optimized or not. For example, assuming that a multifocal lens has angles at diameters of 1 mm and 3 mm, these angles may not be optimized because they have little effect on comfort due to being close to the center of the lens. In addition, optimizing the angle between the edge of the optical zone on the front surface of the lens and the peripheral zone on the front surface of the lens will not affect the optical performance of the lens, so that the visual effect will not be affected while the comfort is improved.

[0053] Figure 1 A flow chart of a method for optimizing the design of a hard corneal contact lens according to an embodiment of the present disclosure is shown.

[0054] See also Figure 1 , in step S110, the original angle of the front surface of the lens is obtained.

[0055] The original angle of the front surface of the lens refers to the angle between two adjacent arc segments on the front surface of the lens determined according to the lens prescription parameters before the lens is optimized. The two adjacent arc segments involved in forming the original angle of the front surface of the lens may refer to any two adjacent arc segments on the front surface of the lens. That is, the angle of the front surface of the lens may refer to the angle between any two adjacent arc segments on the front surface of the lens determined based on the lens prescription parameters.

[0056] For ease of understanding, the present disclosure may define the convex edge angle as less than 180°, and the concave edge angle as greater than 180°, that is, the edge angle is defined as the angle of the material cross section. Figure 2 , Figure 3 Schematic diagram showing the angle of the front surface of the lens. Figure 2 , Figure 3 The angle of the front surface of the lens in the figure is the angle between the end of the optical area of ​​the front surface of the lens and the beginning of the peripheral area of ​​the front surface of the lens. "End" and "beginning" refer to the end and beginning in the direction from the center of the lens to the outside. Figure 2 The angle of the front surface of the lens is greater than 180°, that is Figure 2 The angle of the front surface of the lens in is a convex edge. Figure 3 The angle of the front surface of the lens is less than 180°, that is Figure 3 The angle of the front surface of the lens is a concave angle.

[0057] In the present disclosure, the definition of "arc" refers to a continuous arc / continuous curve on the center cross section of the lens. The earliest frame glasses and contact lenses were all designed with rotationally symmetrical spherical surfaces. The entire lens can be described by a cross section passing through the central axis of the lens. Such a cross section is composed of multiple arcs. Therefore, the continuous curved surface on the lens is also called an "arc" or "arc area". Later, the surface design of the lens became increasingly complex, and aspherical surfaces, toric surfaces, free high-order curved surfaces, etc. appeared. Their cross sections may not be arcs, but the term "arc" is still used.

[0058] In some embodiments, the original angle of the front surface of the lens may refer to the angle between the end of the optical zone of the front surface of the lens and the beginning of the peripheral zone of the front surface of the lens. In other words, only the angle on the outside of the front surface of the lens (i.e., outside the optical zone of the front surface of the lens) may be optimized. Optimizing the angle (usually one) outside the optical zone of the front surface of the lens can significantly improve comfort without affecting the visual effect. The optical zone is defined as the corresponding area that allows external light passing through the area to enter the pupil.

[0059] After the lens prescription parameters (such as base curve radius, total diameter, back vertex power, etc.) are determined, the shape of the lens is also determined, which is equivalent to the original angle of the front surface of the lens. According to the lens prescription parameters, the Euclidean geometry or analytic geometry method, or analytic geometry modeling can be used to analyze the cross-sectional shape of the lens to calculate the original angle of the front surface of the lens and the related parameters required to optimize the original angle of the front surface of the lens. For example, the original angle of the front surface of the lens refers to the angle between the end of the optical area of ​​the front surface of the lens and the beginning of the peripheral area of ​​the front surface of the lens. The diameter, width, sagittal height of the peripheral area of ​​the front surface to be optimized and the original angle of the front surface can be calculated based on the prescription parameters as a reference.

[0060] The following is an example explanation of the principle of calculating the distance between two adjacent arc segments.

[0061] When the diameter of the starting end, the diameter of the ending end, and the difference in sagittal height from the starting end to the ending end of a certain arc are known, the radius of curvature of the arc can be calculated through Euclidean geometry, and the tangent direction of the arc at the starting end and the ending end can be inferred. For special surfaces (such as arc segments composed of conic sections), analytical geometry can be used to describe the cross-sectional profile of the lens with a function formula, and the slope of the starting end and the ending end can be calculated through derivatives, and then the tangent direction of the arc at these two locations can be inferred.

[0062] According to the method of analytic geometry, for any continuously differentiable function curve f(x), its derivative f'(x) represents its slope at point x, that is, the tangent value of the angle between the tangent line at that point and the x-axis. Therefore, the angle between that point and the x-axis is acrtan[f'(x)]. The angle between two adjacent arc segments is the angle between the two tangent lines at the connection of the two arc segments.

[0063] Taking the quadratic aspheric surface as an example, the analytical formula for the arc section is:

[0064]

[0065] Among them, c is the curvature of the central vertex of the arc segment, K is the quadratic surface constant, and x is the distance from the central axis of the lens.

[0066] By taking a derivative of formula (1), the result can be expressed as:

[0067]

[0068] Substitute c and K of the arc segment into formula (2). Substitute 1 / 2 of the inner diameter of the arc segment as x into formula (2) to obtain the tangent slope at the beginning of the arc segment. Substitute 1 / 2 of the outer diameter of the arc segment as x into formula (2) to obtain the tangent slope at the end of the arc segment.

[0069] Assuming that c=0.125, K=-0.25, and x=3 for the arc segment, then f'(3)=0.397. Also, arctan[f'(3)]=0.377rad, which means that the angle between the end of the arc segment and the x-axis is 21.6°. Similarly, the angle between the starting point of the next arc connected to the end of the arc segment and the x-axis can be calculated, assuming it is 35°. Then the angle between the two adjacent arc segments can be calculated to be 180°+21.6°-35°=166.6°, which is a raised edge that needs to be optimized.

[0070] In step S120, it is determined whether the original angle of the front surface of the lens needs to be optimized.

[0071] In some embodiments, only the lens front surface angle less than 170° or greater than 190° may be optimized. That is, only when the original lens front surface angle is less than 170° or greater than 190°, it is determined that the original lens front surface angle needs to be optimized.

[0072] In some other embodiments, if the original angle of the front surface of the lens is already in the range of 170° to 190° (but not equal to 180°), it can also be optimized. In other words, as long as the original angle of the front surface of the lens is not equal to 180°, it can be optimized so that the optimized new angle of the front surface of the lens is closer to 180° than the original angle of the front surface of the lens.

[0073] In step S130, if the original angle of the front surface of the lens needs to be optimized, at least one target arc segment of the two adjacent arc segments participating in forming the original angle of the front surface of the lens is split into a first number of sub-arc segments, and the width and sagittal height of the target arc segment are allocated to the first number of sub-arc segments with the goal of making the new angle of the front surface of the lens closer to 180° than the original angle of the front surface of the lens, the width of any sub-arc segment being greater than or equal to a first threshold, and the angle between any two adjacent sub-arc segments being between 170° and 190°.

[0074] The following is an example of the original angle on the front surface of the lens being the angle between the end of the optical area on the front surface of the lens and the beginning of the peripheral area on the front surface of the lens, to illustrate the specific optimization process. It should be known that when the original angle on the front surface of the lens is the angle within the optical area on the front surface of the lens (such as the angle between areas with different focal powers), the optimization process described below can also be used (and other means can be combined to reduce the impact on the optical performance of the lens) to achieve the optimization of the angle.

[0075] Only the arc segment behind the two adjacent arc segments that participate in forming the original angle of the front surface of the lens (i.e., the arc segment corresponding to the peripheral area of ​​the front surface of the lens) can be split into a first number of sub-arc segments. The arc segment corresponding to the peripheral area of ​​the front surface of the lens is split into a first number of sub-arc segments, that is, the peripheral area of ​​the front surface of the lens is split into a first number of sub-arc segments, and each sub-area corresponds to a sub-arc segment. Optimizing the arc segment corresponding to the peripheral area of ​​the front surface of the lens will not affect the optical performance of the lens, so it can improve comfort without affecting the visual effect.

[0076] If the width of a single sub-arc segment is too small, it is difficult to optimize the original angle of the front surface of the lens by splitting the arc segments, and the processing difficulty is high. Therefore, the width of a single sub-arc segment should be greater than or equal to the first threshold. Exemplarily, the first threshold may be equal to 0.2 mm. The widths of different sub-arc segments may be evenly distributed or unevenly distributed. That is, the widths of different sub-arc segments may be the same or different. The sagittal heights of different sub-arc segments are not evenly distributed, but may be distributed with the goal of making the new angle of the front surface of the lens closer to 180° than the original angle of the front surface of the lens, and the angle between any two adjacent sub-arc segments is between 170° and 190°.

[0077] The angle between two adjacent sub-arc segments is in a certain functional relationship with the width and sagitta of the two sub-arc segments. Therefore, widths and sagitta can be assigned to these sub-arc segments according to this functional relationship to achieve the purpose of optimizing the original angle of the front surface of the lens. That is, according to this functional relationship, the width and sagitta of each sub-arc segment can be determined with the goal of making the new angle of the front surface of the lens closer to 180° than the original angle of the front surface of the lens, the width of any sub-arc segment being greater than or equal to the first threshold, and the angle between any two adjacent sub-arc segments being between 170° and 190°. The sum of the widths of all sub-arc segments is equal to the width of the peripheral area of ​​the front surface of the lens. The sum of the sagitta of all sub-arc segments is equal to the sagitta of the peripheral area of ​​the front surface of the lens.

[0078] The functional relationship between the angle between two adjacent sub-arc segments and the width and sag of the two sub-arc segments can be expressed as:

[0079]

[0080] Wherein, formula (3) is the calculation formula for the curvature radius of the sub-arc segment, and formula (4) is the calculation formula for the angle between two adjacent sub-arc segments. r(n) is the curvature radius of the nth sub-arc segment, S n is the sagittal height of the nth sub-arc segment, d n-1 is the inner diameter of the nth sub-arc segment, d n is the outer diameter of the nth sub-arc segment, A(n) is the angle between the nth sub-arc segment and the n+1th sub-arc segment, r n+1 is the radius of curvature of the n+1th sub-arc segment. The width of an arc segment is equal to the outer diameter minus the inner diameter. The outer diameter of a sub-arc segment refers to the diameter of a circle corresponding to the boundary line with the center of the lens as the center and the outer edge of the sub-arc segment as the circle. The outer diameter can also be called the diameter of the outer edge. The inner diameter of a sub-arc segment refers to the diameter of a circle corresponding to the boundary line with the center of the lens as the center and the inner edge of the sub-arc segment as the circle. The inner diameter can also be called the diameter of the inner edge.

[0081] Based on the above formula (3) and formula (4), the diameter (i.e., width) and sagittal height can be allocated for the sub-arc segments to ensure that the angles between adjacent sub-arc segments are within a reasonable range. The reasonable range may be between 170° and 190°. Preferably, it may be between 176° and 184°. In other words, the width and sagittal height of each sub-arc segment can be determined based on the above formula (3) and formula (4).

[0082] The new angle on the front surface of the lens refers to the angle between the end of the optical zone on the front surface of the lens and the first sub-arc segment. The new angle on the front surface of the lens can be calculated by referring to the above formula (3) and formula (4). Among them, the arc segment corresponding to the optical zone on the front surface of the lens can be regarded as the front sub-arc segment, and the first sub-arc segment can be regarded as the rear sub-arc segment.

[0083] In the present disclosure, the first number can be determined according to the degree to which the original angle of the front surface of the lens to be optimized deviates from 180°. Generally speaking, the more the original angle of the front surface of the lens deviates from 180°, the larger the first number is. That is, by dividing the peripheral area of ​​the front surface of the lens into a large number of sub-arc segments, the angle of any extreme degree can be improved.

[0084] Implementation Method 1

[0085] The first number may be 3 to 12, preferably 3 to 9. Different sub-arc segments have the same width.

[0086] If the original angle of the front surface of the lens is greater than 180°, the sagitta of the first number of sub-arc segments are arranged in a decreasing arithmetic progression from inside to outside. If the original angle of the front surface of the lens is less than 180°, the sagitta of the first number of sub-arc segments are arranged in an increasing arithmetic progression from inside to outside.

[0087] The difference d of an arithmetic sequence satisfies, Wherein, N is equal to the first number.

[0088] This method can be used to improve the angle of any extreme degree. The more arc segments are used, the better the improvement effect is, and the amount of calculation is relatively larger, but it does not affect the processing difficulty and processing efficiency. Exemplarily, the first number is positively correlated with the absolute value of the difference between the original angle of the front surface of the lens and 180°. That is, the greater the absolute value of the difference between the original angle of the front surface of the lens and 180° (that is, the more the original angle of the front surface of the lens deviates from 180°), the larger the first number can be set.

[0089] Implementation Method 2

[0090] The first number may be 2. Different sub-arc segments may have the same width.

[0091] If the original angle of the front surface of the lens is greater than 180°, the sagittal height of the sub-arc segment relatively close to the center of the lens accounts for 61.8%, and the sagittal height of the sub-arc segment relatively close to the edge of the lens accounts for 38.2%.

[0092] If the original angle of the front surface of the lens is less than 180°, the sagittal height of the sub-arc segment relatively close to the center of the lens accounts for 38.2%, and the sagittal height of the sub-arc segment relatively close to the edge of the lens accounts for 61.8%.

[0093] The sagittal height ratio is used to characterize the proportion of the sagittal height of a sub-arc segment to the sagittal height of the peripheral area of ​​the front surface of the lens.

[0094] This method is suitable for lenses that do not require much improvement in the original angle of the front surface of the lens. For example, the original angle of the front surface of the lens is already in the range of 170° to 190°, but the wearer hopes to further improve it.

[0095] Implementation 3

[0096] The first number may be 3. Different sub-arc segments may have the same width.

[0097] If the original angle of the front surface is greater than 180°, the sagittal height of the sub-arc segment closest to the center of the lens accounts for 42% to 52%, the sagittal height of the middle sub-arc segment accounts for 30% to 36%, and the sagittal height of the sub-arc segment closest to the edge of the lens accounts for 18% to 22%.

[0098] If the original angle of the front surface is less than 180°, the sagittal height of the sub-arc segment closest to the center of the lens accounts for 18% to 23%, the sagittal height of the middle sub-arc segment accounts for 31% to 36%, and the sagittal height of the sub-arc segment closest to the edge of the lens accounts for 41% to 51%.

[0099] This method can cover the improvement needs of most conventional lenses.

[0100] For example, this method can be applicable to the case where the original angle of the front surface is less than 170° or greater than 190°, and the absolute value of the difference between the original angle of the front surface and 180° is less than a predetermined threshold, that is, the original angle of the front surface is not an extreme angle. The predetermined threshold can be a value that is not too large, such as 20°.

[0101] Figure 4 , Figure 5 A schematic diagram showing the optimization of the angle of the front surface of the lens using three sub-arcs is shown. Figure 4 , Figure 5 The dotted lines in represent the three optimized sub-arcs. Figure 4 It is to optimize the front surface angle of the lens greater than 180°. Figure 5 It is to optimize the front surface angle of the lens less than 180°. Figure 4 , Figure 5 It can be seen that when the widths of the sub-arcs are the same, in order to better optimize the angle of the front surface of the lens, when the angle of the front surface of the lens is greater than 180°, the sagitta allocated to the three sub-arcs should be in a decreasing relationship. Conversely, when the angle of the front surface of the lens is less than 180°, the sagitta allocated to the three sub-arcs should be in an increasing relationship.

[0102] The present disclosure also tests the combination of the improvement scheme proposed in the present disclosure and a variety of different improvement methods, and evaluates the compatibility and advantages and disadvantages of the combination scheme. The improvement schemes for combined use include:

[0103] a. The multi-arc optimization scheme proposed in this disclosure;

[0104] b. Surface modification: The hydrophilicity of the material surface is improved by subjecting the material to surface hydrophilic treatment, such as low-temperature plasma treatment or hydrophilic coating treatment, that is, the water contact angle on the lens surface is reduced to below 45°;

[0105] c. Improvement of oxygen permeability: Replace materials and use raw materials with higher oxygen permeability to improve corneal oxygen supply when wearing lenses. The oxygen permeability coefficient of the lens materials used should be ≥125Dk;

[0106] d. Edge improvement: By thinning the edge of the lens, the friction and collision between the edge of the lens and the eyelid and cornea are reduced. The edge thickness used is 0.03-0.12mm;

[0107] e. Fitting improvement: by improving the fit of the back surface of the lens, the mobility of the lens is reduced, thereby reducing the friction between the lens and the eyelid and cornea. The improvements used include setting the base curve of the lens to an aspheric surface with an e value of 0.4 to 0.6, and / or adding a fitting arc with a smaller radius of curvature than the base curve between the optical zone and the edge curve on the back surface of the lens;

[0108] f. Lubrication aid: In the first few minutes before wearing the glasses, use a commercially available eye drop with lubrication function to drop into the eye wearing the lens 3 times.

[0109] The above-mentioned various improvement schemes were combined and the comfort of the lenses was evaluated according to the following scoring rules. The experimental results are as follows.

[0110]

[0111]

[0112] From the above experimental results, it can be seen that the comfort scores of combination schemes 4 to 9 are all higher than that of a single factor, but the coordination difficulty, compatibility, cost and benefits of the combination are different. The combination of multiple optimization and improvement methods can maximize the comfort of the lens, but the use of too many optimization and improvement methods will lead to diminishing marginal returns and increase additional costs and coordination difficulties. The combination of multi-arc optimization with multiple low-cost and highly compatible methods (Scheme 10) is an excellent solution with good comfort improvement effect, controllable cost and relatively high cost performance.

[0113] Therefore, the present disclosure adopts the above combined Figure 1 On the basis of the optimized design scheme described above, the following improvement measures can be combined to achieve an excellent scheme with good comfort improvement effect, controllable cost and relatively high cost performance. The combined improvement measures include any one or more combinations of the following: hydrophilic treatment of the lens material surface; use of lens material with higher oxygen permeability; thinning of the lens edge.

[0114] When the optimization design scheme disclosed in the present invention is applied to actual lens production, the following two methods can be selected.

[0115] First category method

[0116] After the diameter (i.e., width) and the sagittal height are assigned to each sub-arc segment, the coordinate parameters of each sub-arc segment can be obtained, and the coordinate parameters include the starting end coordinate and the end end coordinate. The coordinate parameters of each sub-arc segment are input into the CNC machining equipment in the form of a queue, and are programmed in a coaxial circular interpolation manner so that the CNC machining equipment can complete the lens machining task through coaxial circular interpolation.

[0117] In other words, the coordinate parameters of each sub-arc segment in the peripheral area of ​​the front surface of the lens can be obtained. Subsequently, the starting end coordinates and the end end coordinates of each sub-arc segment are input into a CNC lathe or other similar CNC processing equipment in the form of a queue, and programmed in the manner of coaxial arc interpolation, so that the production of the improved lens can be completed. In this process, there is no need to calculate the curvature radius of each sub-arc segment, and only equipment that supports arc interpolation is needed, even if its technical level lags behind the latest technology by two to three generations, it can successfully complete the processing task.

[0118] The second method

[0119] A path map of the optimized lens can be drawn, and the path map can be handed over to the CNC processing equipment for lens processing. In other words, the path map can be drawn using mapping software, and then imported into the CNC processing equipment for processing. In this case, the radius of curvature of each sub-arc segment needs to be calculated for mapping. The use of this optimization scheme does not involve complex geometric or algebraic calculations, which can not only greatly reduce the difficulty of mapping tasks, but also significantly improve the efficiency of design and processing.

[0120] Based on the above-mentioned optimization design method, the present disclosure also proposes a hard corneal contact lens.

[0121] Hard corneal contact lenses can be regarded as lenses produced according to the optimized design method mentioned above.

[0122] A hard contact lens comprises a lens body.

[0123] The target arc segment located on the front surface of the lens body is divided into a first number of sub-arc segments.

[0124] The target arc segment is at least one of two adjacent arc segments that participate in forming the original angle of the front surface of the lens.

[0125] The original angle of the front surface of the lens is the angle of the front surface that needs to be optimized (ie, before optimization).

[0126] The new angle of the front surface of the lens formed after splitting (i.e., optimized) is closer to 180° than the original angle of the front surface of the lens, the width of any sub-arc segment is greater than or equal to the first threshold, and the angle between any two adjacent sub-arc segments is between 170° and 190°.

[0127] For some details about hard corneal contact lenses, please refer to the relevant description above.

[0128] In some embodiments, the original angle of the front surface of the lens is the angle between the end of the optical zone of the front surface of the lens and the beginning of the peripheral zone of the front surface of the lens, and the target arc segment is the arc segment corresponding to the peripheral zone of the front surface of the lens. The new angle of the front surface of the lens may refer to the angle between the end of the optical zone of the front surface of the lens and the beginning of the first sub-arc segment.

[0129] In some specific embodiments, different sub-arc segments have the same width and different sag heights.

[0130] In some further embodiments, the first number is 3 to 12, and if the original angle of the front surface of the lens is greater than 180°, the sagitta of the first number of sub-arc segments are arranged in a decreasing arithmetic sequence from the inside to the outside; if the original angle of the front surface of the lens is less than 180°, the sagitta of the first number of sub-arc segments are arranged in an increasing arithmetic sequence from the inside to the outside, and the level difference d of the arithmetic sequence satisfies, Wherein, N is equal to the first number. Exemplarily, the first number is positively correlated with the absolute value of the difference between the original angle of the front surface of the lens and 180°.

[0131] In some further embodiments, the original angle of the front surface of the lens is between 170° and 190°, and the first number is 2. If the original angle of the front surface of the lens is greater than 180°, the sagitta of the sub-arc segment relatively close to the center of the lens accounts for 61.8%, and the sagitta of the sub-arc segment relatively close to the edge of the lens accounts for 38.2%. If the original angle of the front surface of the lens is less than 180°, the sagitta of the sub-arc segment relatively close to the center of the lens accounts for 38.2%, and the sagitta of the sub-arc segment relatively close to the edge of the lens accounts for 61.8%.

[0132] In some further embodiments, the original angle of the front surface is less than 170° or greater than 190°, and the absolute value of the difference between the original angle of the front surface and 180° is less than a predetermined threshold, and the first number is 3. If the original angle of the front surface is greater than 180°, the sagitta of the sub-arc segment closest to the center of the lens accounts for 42% to 52%, the sagitta of the middle sub-arc segment accounts for 30% to 36%, and the sagitta of the sub-arc segment closest to the edge of the lens accounts for 18% to 22%. If the original angle of the front surface is less than 180°, the sagitta of the sub-arc segment closest to the center of the lens accounts for 18% to 23%, the sagitta of the middle sub-arc segment accounts for 31% to 36%, and the sagitta of the sub-arc segment closest to the edge of the lens accounts for 41% to 51%.

[0133] In some embodiments, the width and the sag of each sub-arc segment are determined based on the above formula (3) and formula (4). The specific determination principle can be found in the above related description.

[0134] The optimization design method of the hard contact lens and the hard contact lens according to the present disclosure have been described above in detail with reference to the accompanying drawings.

[0135] The present invention can effectively improve the comfort of hard contact lenses, and has no conflict with other methods for improving the comfort of contact lenses, such as design adjustment, material modification, and auxiliary drugs, and can be used in coordination.

[0136] In addition, the present disclosure also provides a complete set of simple and easy-to-implement specific optimization solutions, which have no threshold from logical calculation to production processing. There is no need to use any complex hardware or software to complete the calculation, and no need for very professional manufacturing personnel. Ordinary people can easily understand and accept it, and it does not require powerful processing equipment for processing.

[0137] In general, the present invention is an improved solution with good compatibility, simplicity, effectiveness and low cost.

[0138] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for optimizing the design of a hard corneal contact lens, comprising: Acquire an original angle of the front surface of the lens, where the original angle of the front surface of the lens is used to characterize an angle between two adjacent arc segments on the front surface of the lens determined based on lens prescription parameters; Determining whether the original angle of the front surface of the lens needs to be optimized; If the original angle of the front surface of the lens needs to be optimized, at least one target arc segment of the two adjacent arc segments that participate in forming the original angle of the front surface of the lens is split into a first number of sub-arc segments, and the width and sagittal height of the target arc segment are allocated to the first number of sub-arc segments with the goal of making the new angle of the front surface of the lens closer to 180° than the original angle of the front surface of the lens, the width of any sub-arc segment being greater than or equal to a first threshold, and the angle between any two adjacent sub-arc segments being between 170° and 190°.

2. The method according to claim 1, wherein: The original angle of the front surface of the lens is the angle between the end of the optical area of ​​the front surface of the lens and the beginning of the peripheral area of ​​the front surface of the lens. Splitting at least one target arc segment of two adjacent arc segments participating in forming the original angle of the front surface of the lens into a first number of sub-arc segments, including: splitting the peripheral area of ​​the front surface of the lens into a first number of sub-areas, each sub-area corresponding to a sub-arc segment.

3. The method according to claim 2, wherein: The first number is 3 to 12, and different sub-arc segments have the same width. If the original angle of the front surface of the lens is greater than 180°, the vector heights of the first number of sub-arc segments are arranged in a decreasing arithmetic progression from the inside to the outside. If the original angle of the front surface of the lens is less than 180°, the vector heights of the first number of sub-arc segments are arranged in an increasing arithmetic progression from the inside to the outside. The difference d of an arithmetic sequence satisfies, Wherein, N is equal to the first number.

4. The method according to claim 3, wherein: The first quantity is positively correlated with the absolute value of the difference between the original angle of the front surface of the lens and 180°.

5. The method according to claim 2, wherein: The original angle of the front surface of the lens is between 170° and 190°. The first number is 2, different sub-arc segments have the same width, If the original angle of the front surface of the lens is greater than 180°, the sagittal height of the sub-arc segment relatively close to the center of the lens accounts for 61.8%, and the sagittal height of the sub-arc segment relatively close to the edge of the lens accounts for 38.2%. If the original angle of the front surface of the lens is less than 180°, the sagittal height of the sub-arc segment relatively close to the center of the lens accounts for 38.2%, and the sagittal height of the sub-arc segment relatively close to the edge of the lens accounts for 61.8%.

6. The method according to claim 2, wherein: The original angle of the front surface is less than 170° or greater than 190°, and the absolute value of the difference between the original angle of the front surface and 180° is less than a predetermined threshold value, The first number is 3, different sub-arc segments have the same width, If the original angle of the front surface is greater than 180°, the sagittal height of the sub-arc segment closest to the center of the lens accounts for 42% to 52%, the sagittal height of the middle sub-arc segment accounts for 30% to 36%, and the sagittal height of the sub-arc segment closest to the edge of the lens accounts for 18% to 22%. If the original angle of the front surface is less than 180°, the sagittal height of the sub-arc segment closest to the center of the lens accounts for 18% to 23%, the sagittal height of the middle sub-arc segment accounts for 31% to 36%, and the sagittal height of the sub-arc segment closest to the edge of the lens accounts for 41% to 51%.

7. The method according to claim 1, wherein: Allocating the width and the sag of the target arc segment to the first number of sub-arc segments includes: determining the width and the sag of each of the sub-arc segments based on the following formula, Among them, r(n) is the curvature radius of the nth sub-arc segment, S n is the sagittal height of the nth sub-arc segment, d n-1 is the inner diameter of the nth sub-arc segment, d n is the outer diameter of the nth sub-arc segment, A(n) is the angle between the nth sub-arc segment and the n+1th sub-arc segment, r n+1 is the curvature radius of the n+1th sub-arc segment.

8. The method according to any one of claims 1 to 7, further comprising: Acquire the coordinate parameters of each sub-arc segment, wherein the coordinate parameters include the starting end coordinate and the ending end coordinate; The coordinate parameters of each sub-arc segment are input into the numerical control processing equipment in the form of a queue, and are programmed in a coaxial circular interpolation manner, so that the numerical control processing equipment completes the lens processing task through coaxial circular interpolation.

9. The method according to any one of claims 1 to 7, further comprising: A path diagram of the optimized lens is drawn, and the path diagram is handed over to a numerical control processing device for processing the lens.

10. The method according to claim 1, further comprising: Treating the lens material to make it hydrophilic; and / or Use lens materials with higher oxygen permeability; and / or Thinning of the lens edges.

11. A hard corneal contact lens, comprising a lens body, The target arc segment located on the front surface of the lens body is divided into a first number of sub-arc segments, The target arc segment is at least one of the two adjacent arc segments that participate in forming the original angle of the front surface of the lens. The original angle of the front surface of the lens is the angle of the front surface before optimization, The new angle of the front surface of the lens is closer to 180° than the original angle of the front surface of the lens. The width of any sub-arc segment is greater than or equal to the first threshold, and the angle between any two adjacent sub-arc segments is between 170° and 190°.

12. The hard contact lens according to claim 11, wherein: The original angle of the front surface of the lens is the angle between the end of the optical area of ​​the front surface of the lens and the beginning of the peripheral area of ​​the front surface of the lens, and the target arc segment is the arc segment corresponding to the peripheral area of ​​the front surface of the lens.

13. The hard contact lens according to claim 12, wherein: Different sub-arc segments have the same width and different sags.

14. The hard contact lens according to claim 13, wherein: The first number is 3 to 12, If the original angle of the front surface of the lens is greater than 180°, the vector heights of the first number of sub-arc segments are arranged in a decreasing arithmetic progression from the inside to the outside. If the original angle of the front surface of the lens is less than 180°, the vector heights of the first number of sub-arc segments are arranged in an increasing arithmetic progression from the inside to the outside. The difference d of an arithmetic sequence satisfies, Wherein, N is equal to the first number.

15. The hard contact lens according to claim 14, wherein: The first quantity is positively correlated with the absolute value of the difference between the original angle of the front surface of the lens and 180°.

16. The hard contact lens according to claim 13, wherein: The original angle of the front surface of the lens is between 170° and 190°. The first number is 2, If the original angle of the front surface of the lens is greater than 180°, the sagittal height of the sub-arc segment relatively close to the center of the lens accounts for 61.8%, and the sagittal height of the sub-arc segment relatively close to the edge of the lens accounts for 38.2%. If the original angle of the front surface of the lens is less than 180°, the sagittal height of the sub-arc segment relatively close to the center of the lens accounts for 38.2%, and the sagittal height of the sub-arc segment relatively close to the edge of the lens accounts for 61.8%.

17. The hard contact lens according to claim 13, wherein: The original angle of the front surface is less than 170° or greater than 190°, and the absolute value of the difference between the original angle of the front surface and 180° is less than a predetermined threshold value, The first number is 3, If the original angle of the front surface is greater than 180°, the sagittal height of the sub-arc segment closest to the center of the lens accounts for 42% to 52%, the sagittal height of the middle sub-arc segment accounts for 30% to 36%, and the sagittal height of the sub-arc segment closest to the edge of the lens accounts for 18% to 22%. If the original angle of the front surface is less than 180°, the sagittal height of the sub-arc segment closest to the center of the lens accounts for 18% to 23%, the sagittal height of the middle sub-arc segment accounts for 31% to 36%, and the sagittal height of the sub-arc segment closest to the edge of the lens accounts for 41% to 51%.

18. The hard contact lens according to claim 11, wherein: The first threshold is 0.2 mm.

19. The hard contact lens according to claim 11, wherein: The included angle between any two adjacent sub-arc segments is between 176° and 184°.

20. The hard contact lens according to claim 11, wherein: The width and sagittal height of each sub-arc segment are determined based on the following formula: Among them, r(n) is the curvature radius of the nth sub-arc segment, S n is the sagittal height of the nth sub-arc segment, d n-1 is the inner diameter of the nth sub-arc segment, d n is the outer diameter of the nth sub-arc segment, A(n) is the angle between the nth sub-arc segment and the n+1th sub-arc segment, r n+1 is the curvature radius of the n+1th sub-arc segment.

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