Progressive lens design method based on personalized lens viewpoint data and presbyopia model

Abstract

The invention relates to the field of ophthalmic lens design, in particular to a personalized progressive lens design method according to lens viewpoint data. According to the method, a personalized adjustable presbyopia model is constructed based on an optometry prescription of a wearer; the method comprises the following steps: acquiring lens viewpoint data of a wearer through lens viewpoint acquisition equipment, generating a viewpoint density map, and extracting a high-frequency use area to construct a multiple structure; evaluating the imaging quality of the traditionally designed progressive lens on the retina in the sight line moving process of the wearer by combining with an eye model; and adding a composite surface, and synchronously optimizing the appearance of the composite surface under multiple structures by minimizing wavefront aberration through a multiple structure editor to obtain the personalized progressive lens based on viewpoint data. The personalized progressive lens provided by the invention can effectively improve the imaging quality of a high-frequency viewpoint area.

Description

Technical Field

[0001] The present invention relates to the field of ophthalmic lens design, in particular to a personalized design method of progressive lenses suitable for wearers. Background Art

[0002] Traditional progressive lens design relies on fixed parameters, including spherical power, add power (ADD), and channel length. However, in situations where individual vision shifts, improper astigmatism distribution in the astigmatic zone and insufficient ADD may lead to visual discomfort.

[0003] A common method for personalized design based on gaze movement data is through ray tracing, which simulates gaze movement across the lens and the corresponding object distance to analyze the refractive power provided by the lens during dynamic head-eye movements. This method can, to a certain extent, evaluate the wearer's progressive lens wearing effect based on the gaze movement results, but there is still a problem that cannot directly obtain a personalized progressive lens based on the gaze movement data. Based on the evaluation results, the design needs to be modified from perspectives such as channel length and added light to optimize the lens' optical performance and achieve a personalized effect. Furthermore, this evaluation method is only used to assess the rationality of the lens' refractive power and astigmatism distribution, and the gaze movement evaluation results cannot be directly applied to lens design. Summary of the Invention

[0004] The present invention aims to provide a method for directly designing personalized progressive lenses tailored to the wearer based on personalized lens viewpoint data. By combining the wearer's prescription and lens viewpoint data, the method allows for direct personalized design based on traditional progressive lens design, improving visual clarity and wearing comfort.

[0005] To achieve the above objectives, the present invention adopts the following core technical steps:

[0006] S1. Build a personalized accommodative eye model based on the wearer's optometry prescription, and adjust the lens curvature radius (r a 、r p ) and refractive index distribution parameter (n r2 、n r4 ) obtain a presbyopia model under far and near vision accommodation states;

[0007] S2. Input the wearer's head-eye movement ratio parameters, establish a lens-eye rectangular coordinate system, calculate the wearer's line of sight during the movement of the line of sight, and obtain the coordinates of the gaze point;

[0008] S3. Establish an objective-lens-eye optical system and conduct visual clarity assessment;

[0009] S4. Use a lens viewpoint acquisition device to obtain the wearer's lens viewpoint data, and use a multiple structure editor to construct multiple structures with optimized positions. Superimpose a surface in front of the front surface of the progressive lens as a composite surface. By optimizing the surface morphology under multiple structures, the wearer's personalized designed lens is obtained.

[0010] Furthermore, the method for establishing the presbyopia model described in S1 is as follows:

[0011] Enter a wearer's optometrist prescription, which contains at least the eye's distance refraction P1 (D) and near refraction P2 (D), or the distance refraction and an additional ADD that can correct presbyopia. These data are used to construct an accommodative eye model based on the Liou-Brennan eye model in the optical design software Zemax. Liou-Brennan is an anatomically constructed model consisting of the cornea, aqueous humor, an eccentric pupil, a lens with two different gradient refractive index profiles in the front and back halves, a vitreous body, and a curved retinal surface. The lens refractive index fitting formula is:

[0012] n=n0+n r2 r 2 +n r4 r 4 +n r6 r 6 +n z1 z+n z2 z 2 +n z3 z 3

[0013] z is the thickness of the lens, and r is the radius of the lens.

[0014] This model can well simulate the state of the human eye under ideal far-sightedness. Based on this model, the present invention adjusts the lens parameters by inputting the eye refractive data to simulate presbyopia. Assuming that the lens does not change in the center thickness direction during presbyopia, the curvature radius r of the front and back surfaces of the lens is set to a , r p For the refractive index, the distribution of the refractive index n along the z direction is set to remain unchanged, and only the distribution along the radial direction changes. Therefore, n is set r2 and n r4 For these four variables, set constraints based on the variation law and statistical data of the lens. Set the object distance to 1000 / P1 (mm), and set the curvature radius of the front and back surfaces of the lens and n r2 Set it as a variable and perform optimization by minimizing the wavefront. Then remove the constraints and set n r4As variables, a new eye model is obtained by minimizing the wavefront, which is used as a presbyopia model for far vision. Similarly, a presbyopia model for near vision is obtained.

[0015] Furthermore, in S2, a rectangular coordinate system based on the lens and eye is established. The wearer's head-eye movement ratio parameters and lens wearing parameters are input, including at least pupil distance, lens-eye distance, tilt angle, and mirror angle. During eye movement, the center of eye rotation is used as the origin of the lens-eye coordinate system, denoted as point O', and the vertical rotation angle of the eye movement is denoted as α. e , the horizontal rotation angle is β e , α e is the vertical angle between the line of sight and the horizontal plane when the eye moves upward from the horizontal line of sight (OQ' axis). The vertical movement ratio parameter and the horizontal movement ratio parameter of the head and eye are κ α and κ β , the ratio value varies for different wearers, so the vertical and horizontal rotation angles of the head movement are calculated as

[0016]

[0017] α h and β h are the vertical rotation angle and horizontal rotation angle of the wearer's head movement respectively.

[0018] The lens-eye coordinate system when looking at the distance horizontally is used as the case where no head-eye movement occurs. At this time, the coordinate of the center of eye rotation is marked as point O. The key points of the wearer under this coordinate are input, which must include at least 4 points: P1 reading, P2 keyboard, P3 screen, and P4 distance vision. These points are fitted into a third-order Bezier curve, and then extended horizontally as the visual reference surface for the evaluation and optimization of progressive lenses.

[0019] The data of eye refraction is used to obtain a progressive lens designed by traditional methods. The surface topography of the progressive lens is imported into Zemax in the form of sagittal height and a coordinate discontinuity is inserted before the front surface of the lens to control lens wearing parameters such as eye-to-eye distance, tilt angle and mirror angle. The image coordinate is selected to be located at the center of the macula on the retina. According to the rotation angle α e and β e Control the movement of the eyeball and obtain the direction of sight after it is emitted from the progressive lens through ray tracing. The intersection of the sight direction and the visual reference plane is calculated as the coordinates of the object being gazed at that angle.

[0020] Furthermore, in S3, the lens imaging quality assessment includes the following steps:

[0021] S31, set the gaze object coordinates obtained in S2 as object coordinates, add a coordinate discontinuity surface in front of the corneal surface of the eye model, set the surface thickness to the distance from the corneal surface to the rotation center of the eyeball, and set the X tilt αe , Y tilt is set to β e , an objective-lens-eye optical system is constructed at this angle. The angle range of eye movement is set to α min ≤α e ≤α max , β min ≤β e ≤β max , set the step size to delta, and get the objective-lens-eye optical system at each angle under this step size.

[0022] S32, still set the lens curvature radius and refractive index variable n r2 、n r4 As a variable, add the optimization results of the far vision / near vision lens model as constraints, and continue to optimize using the default minimum wavefront evaluation function to obtain a rotation angle of α e and β e The wearer considers the clearest imaging situation after eye adjustment.

[0023] S33. Extract the viewpoint position on the lens, the RMS spot radius and the MTF value of the image on the retina, take the RMS spot radius value and the MTF value at 10 cycles / mm as evaluation indicators of the image quality on the retina, and generate the evaluation results of the entire lens.

[0024] Furthermore, in S4, the personalized lens design includes the following specific steps:

[0025] S41. Generate a density distribution of viewpoints based on the viewpoint density of the input viewpoint data, extract the peak position as the optimized position, and use a multi-structure editor to construct an objective-lens-eye optical system structure for each optimized position. Each system corresponds to a specific eye movement angle, head movement angle, and object distance.

[0026] S42. Add a surface in front of the front surface of the traditional lens design. Select the surface type as a composite surface. The composite surface and the base surface are combined by the sag superposition method. The superposition relationship is:

[0027] Z(x,y)=Z Base (x,y)+Z Comp (x,y)

[0028] Among them, Z Base (x, y) is the base surface sagittal height, (x, y) is the front surface sagittal height of the progressive lens, and (z) is the base surface sagittal height. Conp (x,y) is the composite surface sag.

[0029] The total surface topography is the linear superposition of the base surface sagitta and the composite surface sagitta. Setting the composite surface topography parameters as variables can simultaneously affect the optical properties of all multiple structures.

[0030] S43. By minimizing the evaluation function of wavefront aberration as the goal, the morphological parameters of the surface are optimized under multiple structures to obtain a composite surface morphology that improves the imaging quality of the viewpoint peak area. The optimized composite surface sagittal height data is superimposed on the basic surface to generate the final personalized progressive lens morphology. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Design a flowchart for personalization.

[0032] Figure 2 This is a structural diagram of the accommodative human eye model.

[0033] Figure 3 This is a model diagram of the lens of a presbyopic eye in the state of far vision and near vision.

[0034] Figure 4 MTF curves of the eye model and the Liou-Brennan eye model in the state of far and near accommodation.

[0035] Figure 5 This is a model diagram of the sight direction angle based on the center of eye rotation.

[0036] Figure 6 This is a diagram of the visual reference surface and gaze point for glasses wearers.

[0037] Figure 7 This is a flowchart for lens imaging quality assessment.

[0038] Figure 8 This is a graph of the RMS and MTF values of the image on the retina at different positions on the lens during the line of sight movement.

[0039] Figure 9 Flowchart for personalized lens design based on viewpoint data.

[0040] Figure 10 This is the density distribution diagram of the sight line data obtained by the lens viewpoint acquisition device.

[0041] Figure 11 Optimize position map for lens selection based on viewpoint distribution.

[0042] Figure 12 This is the change diagram of the surface height before the optimization process.

[0043] Figure 13 To optimize the process of sight movement, the RMS value and MTF value of the image on the retina at different positions on the lens are shown. DETAILED DESCRIPTION

[0044] Example 1

[0045] In this embodiment, the wearer's eye prescription is: spherical power is -2.00D, and additional ADD is 1.00D. Head-eye movement ratio parameter κ α =κ β =0.3, and the key gaze point coordinates are shown in Table 1. The spectacle frame data are: forward tilt angle 8°, mirror angle 5°, and lens-to-eye distance 12 mm.

[0046] Table 1 Coordinates of key gaze points

[0047]

[0048] P1, reading a book; P2, using a keyboard; P3, using a computer screen; P4, looking far away

[0049] like Figure 1 The figure shows a design flow chart of a personalized progressive lens provided by the present invention. The specific steps of the method are as follows:

[0050] S1. Determine the adjustment range of the eye model according to the prescription, and set the wearer's eye to have a clear viewing distance of 2D and 3D, i.e. 0.5m and 0.33m respectively. Establish the Liou-Brennan eye model as follows Figure 2 Taking the object distance of 0.5m as an example, the lens model of the eyeball is adjusted.

[0051] Front surface curvature radius constraint: (soft constraint) 12.3mm≤r a ≤12.4mm(hard constraint)

[0052] Back surface curvature radius constraint: (soft constraint) 7.87mm≤r p ≤8.1mm(hard constraint)

[0053] Set the hard constraint to a high weight and the soft constraint to a low weight. Set the object distance to 500 mm and the radius of curvature of the front and back surfaces of the lens to r. a 、r p and the lens refractive index parameter n r2 Set it as a variable and perform optimization by minimizing the wavefront. Then remove the constraints and set n r4 As a variable, a new eye model is obtained by minimizing the wavefront as a presbyopia model in the far vision state, such as Figure 3 (a). Similarly, an eye model with an object distance of 0.33m is obtained as the presbyopia model in the near vision state, as shown in Figure 3 (b) The eye model results under far vision and near vision accommodation conditions are shown in Table 2:

[0054] Table 2 Results of optimization variables for far vision and near vision models

[0055]

[0056] Comparing our optimized accommodative eye model with the Liou-Brennan eye model, we found that as the object distance gets closer, the spot radius increases, but it is still within the Airy radius. Figure 4 , it was found that the image quality on the retina decreased, but the OTF modulus value was still greater than 0.2 at 100 cycles / mm, and the degree of decrease was acceptable, indicating that the eye model is feasible under the conditions of far and near vision accommodation.

[0057] S2. Define the eye movement angle of the gaze direction as follows Figure 5 As shown, according to the input head-eye movement ratio parameter k α and k β , and the key gaze point coordinates, get the head movement angle. Set the eye movement vertical rotation angle range in Zemax to -20°≤α e ≤0°, step size is 2°. Vertical rotation angle -20°≤β e ≤20°, with a step size of 2°. Input the wearer's eyeglass frame data as follows: anteversion angle of 8°, mirror angle of 5°, eye relief of 12mm, and the fitting center is located at the center of the distance zone of the traditional progressive lens design. Set the coordinate discontinuity surface before the front surface of the lens to have an x-tilt of -8°, a y-tilt of 5°, and a thickness of 12. Figure 6 As shown, through the ray tracing function, the light is traced from the center of the retinal macula in reverse to the front surface of the lens, and the coordinates of the intersection of each light ray emitted from the front surface of the lens and the visual reference surface are calculated.

[0058] S3. The method for evaluating the imaging quality of the lens is as follows: Figure 7 The process shown is as follows:

[0059] S31. Add a coordinate discontinuity in front of the corneal surface of the eye model and set its thickness to be 12 mm from the corneal surface to the eyeball rotation center. e and β e Set the X tilt α e , Y tilt is set to β e , simulating eye movement, a objective-lens-eye optical system was constructed at this angle.

[0060] S32, set r a 、r p 、n r2 and n r4 As a variable, the r of the near-sighted eye model is used in the evaluation function. a =10.84 is r a The minimum value of the constraint is r of the far-sighted eye model a =11.84 is r aThe maximum value of the constraint, set the weight to 10 6 , as hard constraints. Similarly, all other parameters in the near vision and far vision eye models are set as hard constraints. Then, the default evaluation function constructed by minimizing the wavefront is added, and then the optimization is performed.

[0061] S33, extract the viewpoint position on the lens, the RMS spot radius and the MTF value of the image on the retina, and calculate the RMS and MTF graphs of the viewpoint position on the lens corresponding to the image on the retina. Figure 8 .

[0062] S4, through the composite surface, the lens personalized design method, such as Figure 9 The process shown is as follows:

[0063] S41, input the wearer's lens viewpoint data obtained by the lens viewpoint acquisition device according to the coordinates, divide it into 100×100 grid intervals, count the number of viewpoints in the grid intervals, divide the number of viewpoints in each interval by the total number of viewpoints, and obtain the viewpoint density result. Select the peak value of the density as the commonly used viewpoint result, such as Figure 10 The peak position is extracted as the coordinate of the optimized position as Figure 11 .

[0064] S42. Insert a surface in front of the front surface of the progressive lens, preferably a Zernike Fringe surface suitable for aberration correction, and set it to a composite surface type. Set the Zernike polynomial coefficients to 15 terms. Set these 15 coefficients and the surface curvature radius as variables to flexibly adjust the local curvature. Use the PRAM operand of the Multi-Structure Editor to set the eye rotation angle. Enter the eye rotation angle corresponding to the viewpoint peak position extracted in S41.

[0065] S43. Under multiple structures, the presbyopia model in the two accommodative states of far vision and near vision is still used as the hard constraint range. Under each multiple structure, the glass constraint of the progressive lens is added, and the thinnest and thickest thicknesses of the constrained surface are 2mm and 5mm respectively. By minimizing the wavefront, the surface curvature radius and 15 Zernike polynomial coefficients are obtained, and the surface sagitta change of the personalized design based on the traditional design is obtained. This change is controlled by the optimized surface curvature radius and 15 Zernike polynomial coefficients. The surface sagitta is as follows: Figure 12 The MTF and RMS values of the image on the retina after optimization are as follows: Figure 13 It can be seen that in the commonly used intermediate vision area, the MTF is significantly improved and the RMS value is small, indicating that the wearing comfort of the front surface of the progressive lens after the optimization result is greatly improved.

Claims

1. A method for designing a personalized progressive lens based on an accommodative eye model, comprising obtaining a conventional design of a progressive lens according to a wearer's eye prescription, characterized in that: Personalized design based on viewpoint data includes the following steps: S1, constructing a personalized accommodative eye model according to the optometry prescription, wherein the eye model is adjusted by adjusting the lens curvature radius (r a 、r p ) and refractive index distribution parameter (n r2 、n r4 ) Simulating the accommodation differences between distance and near vision in presbyopic eyes; S2. Input the wearer's head-eye movement ratio parameters, establish a lens-eye rectangular coordinate system, calculate the wearer's line of sight during the movement of the line of sight, and obtain the coordinates of the gaze point; S3. Establish an objective-lens-eye optical system and conduct visual clarity assessment; S4. Use a lens viewpoint acquisition device to obtain the wearer's lens viewpoint data, use a multiple structure editor to construct multiple structures with optimized positions, superimpose a surface in front of the front surface of the progressive lens as a composite surface, and optimize the surface morphology under multiple structures to obtain the wearer's personalized designed lens.

2. A personalized progressive lens design method according to claim 1, characterized in that: In S1, the adjustment variables used to construct the presbyopia model include the curvature radius of the front and back surfaces of the lens and the refractive index parameters of the lens.

3. The method for designing a personalized progressive lens according to claim 1, wherein: In S1, the method for constructing a presbyopia model includes: According to the optometrists' prescription, including the distance optical power P1 and the near optical addition ADD, an accommodative eye model simulating presbyopia is constructed by optimizing the adjustment variables by minimizing the wavefront aberration.

4. The method for designing a personalized progressive lens according to claim 1, wherein: In S4, the optimized position construction includes: extracting the optical optimization area from the viewpoint density distribution map generated according to the viewpoint data, and using a multi-structure editor to construct the objective-lens-eye optical system structure under various head-eye movement angles for each optimized position.

5. The method for designing a personalized progressive lens according to claim 1, wherein: In S4, the composite surface is constructed, including: In front of the front surface of the progressive lens, the insertion surface is a composite surface. The superposition relationship between the composite surface and the basic surface is: Z(x,y)=Z Base (x,y)+Z Comp (x,y) Among them, Z Base (x, y) is the base surface sagittal height, (x, y) is the front surface sagittal height of the progressive lens, and (z) is the base surface sagittal height. Comp (x,y) is the composite surface sag.

6. The method for designing a personalized progressive lens according to claim 1, wherein: In S4, the composite surface optimization includes: The composite surface morphology variables are set, and a multiple structure is constructed for the lens viewpoint data obtained by the lens viewpoint acquisition device through a multiple structure editor to obtain a composite surface morphology suitable for the wearer.

7. The composite surface construction method according to claim 5, characterized in that: In S4, the composite surface is a Zernike Fringe sag surface, which includes 15 Zernike coefficients.

8. The composite surface optimization method according to claim 6, characterized in that: In S4, the composite surface topography variables are surface curvature radius and 15 Zernike coefficients, and the surface curvature radius and 15 Zernike coefficients are determined by multiple structural optimization.

Images